Eocene-Oligocene paleoenvironmental changes in the South Orkney Microcontinent (Antarctica) linked to the opening of Powell Basin

Journal Pre-proof Eocene-Oligocene paleoenvironmental changes in the South Orkney Microcontinent (Antarctica) linked to the opening of Powell Basin Adrián López-Quirós, Carlota Escutia, Johan Etourneau, Francisco J. Rodríguez-Tovar, Sabine Roignant, Francisco J. Lobo, Nick Thompson, Peter K. Bijl, Fernando Bohoyo, Ulrich Salzmann, Dimitris Evangelinos, Ariadna Salabarnada, Frida S. Hoem, Marie-Alexandrine Sicre PII: S0921-8181(21)00166-1 DOI: https://doi.org/10.1016/j.gloplacha.2021.103581 Reference: GLOBAL 103581 To appear in: Global and Planetary Change Received date: 3 November 2020 Revised date: 25 June 2021 Accepted date: 13 July 2021 Please cite this article as: A. López-Quirós, C. Escutia, J. Etourneau, et al., EoceneOligocene paleoenvironmental changes in the South Orkney Microcontinent (Antarctica) linked to the opening of Powell Basin, Global and Planetary Change (2018), https://doi.org/10.1016/j.gloplacha.2021.103581 This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2018 © 2021 Elsevier B.V. All rights reserved. 1 Eocene-Oligocene paleoenvironmental changes in the South Orkney Microcontinent (Antarctica) linked to the opening of Powell Basin Adrián López-Quirósa, b*, Carlota Escutiab, Johan Etourneaub, c, d, Francisco J. Rodríguez-Tovare, Sabine Roignantf, Francisco J. Lobob, Nick Thompsong, Peter K. Bijlh, Fernando Bohoyoi, Ulrich Salzmanng, Dimitris Evangelinosb, Ariadna Salabarnadab, Frida S. Hoemh, Marie-Alexandrine Sicref aDepartment of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, 8000, Aarhus C, Denmark. bInstituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain. cEPHE, PSL Research University, Paris, France. dUMR 5805 EPOC CNRS, University of Bordeaux, Bordeaux, France. eDepartment of Stratigraphy and Paleontology, University of Granada, 18071, Granada, Spain. fUMR 7159 LOCEAN CNRS-IRD-MNHN, Sorbonne Universités, Paris, France gDepartment of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, UK. hMarine Palynology and Paleoceanography, Laboratory of Palaeobotany and Palynology, Department of Earth Science, Utrecht University, Budapestlann 4, 3584 CB Utrecht, The Netherland. iInstituto Geológico y Minero de España, Rios Rosas 23, 28003 Madrid, Spain. * Corresponding author: alquir[email protected]u.dk (A. López-Quirós). Abstract The scarcity of paleo-records from the Antarctic Peninsular region of the Southern Ocean hinders our understanding of the timing of the opening of Drake Passage, specifically in the region of the South Orkney Microcontinent (SOM) and Powell Basin, between the Scotia and Antarctic plates. At Ocean Drilling Program (ODP) Hole 696B, SOM sediments recovered from the upper Eocene-lower Oligocene (~37.6-32.2 Ma) enable us to gain insight into paleoceanographic and paleoclimatic changes during gateway opening across the major Cenozoic climate shift —the Eocene-Oligocene transition— when the Antarctic ice sheet first reached sea-level. We propose the following sequence of events, based on a multi-proxy analysis of sediment facies, mineralogy, and organic matter geochemistry (TOC, TN, C/N ratio, δ13C, δ15N, and n-alkanes). During the late Eocene (~37.6–35.5 Ma) the SOM was attached to the Antarctic Peninsula, and terrigenous sediments of likely local origin were deposited in shallow waters under conditions of reduced-oxygen/low-salinity, and temperate climate. In the latest Eocene (~35.5–34.1 Ma), terrigenous input was reduced due to the separation of the SOM from the Antarctic Peninsula by proto-Powell Basin opening. Decreased sediment supply during continuous deepening of the SOM led to deposition of a condensed section with significant glauconitization, recurrent winnowing by bottom currents, and suboxic conditions near the sediment-water interface. At the time of the Eocene-Oligocene transition (EOT; ~34.1–33.6 Ma) two upward-coarsening sediment sections were deposited within an overall upwardfining section, which we interpret as records of regressive phases due to ice sheet expansion. During the early Oligocene (~33.6–33.2 Ma) the SOM deepened further because of continued opening of Powell Basin, and organic-rich sediments were deposited as a result of enhanced biological production, partially driven by enhanced upwelling. Major cooling caused a change from forests indicating relatively humid temperate conditions in the late Eocene, to forests indicative of dry and cool conditions in the Oligocene, as shown by biomarker records, which also indicate weakening contributions of terrestrial organic matter to the marine sedimentary record. We thus conclude that a shallow gateway, the proto-Powell Basin, formed at ~35.5 Ma, as seen in the decreased delivery of proximal, coarse terrigenous sediments to the SOM margin; this was followed by a long-term deepening trend, interrupted by EOT regression due to continent-wide ice sheet build-up. Opening of the proto-Powell Basin could have provided a shallow-water pathway for water flowing from the Drake Passage-Scotia Sea towards the northern Weddell Sea, enhancing upwelling at the southern SOM shelf margin. Hence, increased marine productivity across the EOT might have resulted from the combined effects of the opening of Powell Basin and climate cooling. Keywords: Late Eocene-early Oligocene, Drake Passage, South Orkney Microcontinent, ODP 696, Paleoenvironment. 1. Introduction The Eocene-Oligocene Transition (EOT), marked by a 1.5‰ positive excursion of δ18O values in deep-sea benthic foraminifera at 34–33.5 Ma, was a major global climatic event involving cooling, the onset of full-scale glaciation in Journal Pre-proof Journal Pre-proof 2 Antarctica (e.g., Zachos et al., 2001; Coxall et al., 2005; Passchier et al., 2017), progressive global sea-level fall (e.g., Miller et al., 2005; Stocchi et al., 2013), and a global or regional increase in oceanic primary productivity at high southern latitudes (e.g., Egan et al., 2013; Houben et al., 2013; Villa et al., 2014). Geological consequences of the dramatic changes were conspicuous around Antarctica and the Southern Ocean. Middle Eocene sediments in the Antarctic Peninsula region indicate mild, frost-free winters and moisture availability sufficient to support highly diverse subtropical and temperate rain forests (e.g., Mohr, 2001; Poole et al., 2005; Francis et al., 2008). During the late Eocene, from approximately 2 myr before the EOT, large-scale changes in flora composition and diversity recorded the onset of prolonged cooling in the Antarctic Peninsula (e.g., Askin, 2000; Anderson et al., 2011; Warny and Askin, 2011), and associated moisture changes led to periods of drought (Hosking and Hutcheson, 1988; Suarez et al., 2004). Vegetation persisted across the EOT, but the warm Eocene vegetation was replaced by shrubby vegetation (i.e., southern beech Nothofagus, mosses and ferns), which could survive in tundra-like conditions (Francis et al., 2006). Another significant change during the EOT was the switch from chemical to physical weathering dominance around Antarctica (e.g., Ehrmann and Mackensen, 1992; Escutia et al., 2011; Basak and Martin, 2013; Passchier et al., 2013). Offshore, the arrival of ice sheets at the Antarctic continental margins was recorded by deposition of subglacial and iceproximal deposits on the continental shelves, as well as by iceberg transport and delivery of Ice Rafted Debris (IRD) to the seabed all around Antarctica (e.g., Barker et al., 1988 for the Weddell Sea; Passchier and Krissek, 2008 for the Ross Sea; Escutia et al., 2011, 2014 for Wilkes Land). The opening and deepening of the Tasmania and Drake oceanic passages has been invoked as the cause of these major climatic changes, by enabling the exchange of water masses between the Atlantic, Indian and Pacific oceans in the Antarctic Circumpolar Current (ACC) (e.g., Kennett et al., 1977; Lawver and Gahagan, 1998; Exon et al., 2001), implying the thermal isolation of Antarctica and ultimately growth of its massive ice sheets. A major drawback to this hypothesis is that the timing of Drake Passage´s opening and deepening remains highly controversial, with potential timing from the Eocene to the Miocene (e.g., Barker and Burrell, 1977; Barker, 2001; Lawver et al., 2003; Barker and Thomas, 2004; Livermore et al., 2004, 2007; Eagles et al., 2006; Scher and Martin, 2006; Cramer et al., 2009; Lagabrielle et al., 2009; Maldonado et al., 2014). Thus we cannot independently link the formation of ocean gateways, the development of a modern-like ACC, and the establishment of the Antarctic ice sheet. The opening of Powell Basin was part of a regional response to relative plate motion of South America away from Antarctica, the ultimate stage of Drake Passage opening (e.g., Eagles and Livermore, 2002; Livermore et al., 2007). The paucity of records and lack of age control hinder not only our understanding of the timing and patterns of Drake Passage opening and deepening, but also of the regional paleoenvironmental and paleoceanographic changes across the EOT. More specifically, questions surround the region of the South Orkney Microcontinent (SOM) and Powell Basin, viewed as an integral part of Drake Passage opening. Analysis of organic matter in marine sediments provides information widely utilized to evaluate past ocean and continental climates and environmental changes (e.g., Freeman et al., 1994; Meyers et al., 1997; Muller and Voss, 1999; Ficken et al., 2000; Huon et al., 2002; Schefuß et al., 2003; Lamb et al., 2006; Vogts et al., 2009; Arbi et al., 2018). Organic matter contains some of the longest-living proxies of delivery and accumulation in marine settings, providing information about its sources, nutrient cycling and vegetation, and even depositional conditions. Organic matter is a mixture of molecular compounds of diverse origins, with different degrees of preservation, susceptible to diagenesis and biological alteration during and after sinking to the seafloor and subsequent downslope transport. An integration of geochemical techniques based on determination of elemental and stable isotopic compositions and lipid biomarkers (i.e., total organic carbon/total nitrogen (TOC/TN) ratios, δ13C, δ15N and molecular n-alkanes) is needed to tease out these effects so as to optimize paleoenvironmental and paleoecological reconstructions. The SOM, located on the South Scotia Ridge (SSR) between the Scotia and Antarctic plates, is a remnant of a former continental link between the Antarctic Peninsula and South America (e.g., Dalziel, 1984; Barker et al., 1991). Availability of a revised age model for Ocean Drilling Program (ODP) Leg 113 Site 696, drilled on the southeastern margin of the SOM (Barker et al., 1988; Houben et al., 2013, 2019), provides an opportunity to evaluate the paleoenvironmental and paleoceanographic changes of the initial phases of opening of Powell Basin, a product of the opening and deepening of the Drake Passage across the EOT. The goals of this study are: (1) to determine the changes in sedimentary environments from the late Eocene to the early Oligocene and their timing (~37.6–32.2 Ma), potentially linked to the initial phase of separation and deepening of the SOM from the Antarctic Peninsula; (2) to estimate sources (terrestrial vs. marine) of organic matter; (3) to infer paleoclimatic and paleoceanographic processes and their relation to the preservation of organic matter. Journal Pre-proof Journal Pre-proof 3 2. Geological setting The SOM is the largest (about 70,000 km2) continental fragment along the southern boundary of the Scotia Arc (Fig. 1), being a remnant of the land bridge connecting South America and the Antarctic Peninsula prior to the Paleogene continental break-up (Dalziel and Elliot, 1973; de Wit, 1977; Dalziel, 1984; Barker et al., 1991). Estimates of the timing of SOM´s break from the Antarctic Peninsula range from the mid-Eocene to the early Oligocene (40–30 Ma; King and Barker, 1988; Coren et al. 1997; Eagles and Livermore, 2002). The SOM drifted and rotated eastward in conjunction with the rifting and subsequent opening of Powell and Jane Basins (King and Barker, 1988; Trouw et al., 1997; Maldonado et al., 1998; Busetti et al., 2000; Bohoyo et al., 2002; Maestro et al., 2013), attaining its current location during the early Miocene (King and Barker, 1988; Coren et al., 1997). The South Orkney Islands are the only emerged areas (Figs. 1, 2A) by the active northern SOM margin, with outcropping Permian-Triassic sandstones and mudstones (i.e., metapelites and metagreywackes of the Greywacke Shale Formation and the Scotia Metamorphic Complex), interpreted as turbidites (Dalziel, 1984; Flowerdew et al., 2011). The southeast and southwest SOM passive margins are connected to the Powell and Jane oceanic basins, respectively, whereas the southern SOM margin is connected to the oceanic Weddell Basin (King and Barker, 1988; Lawver et al., 1991). The deformational style of the southwestern margin resulted in both steep and gentle slopes, as well as locally detached elevations. In contrast, the southeastern margin is more irregular and less steep overall (King and Barker, 1988). The SOM has two main structural domains: (1) an older domain characterized by an east-west trend comprising a magmatic arc, a fore-arc basin filled with up to 5000 m of sediments (the Newton Basin; Fig. 2A), and a Mesozoic accretionary complex, reflecting the location of the SOM on the Pacific margin; and (2) a younger N-S trending domain encompassing three epicontinental basins (Airy, Bouguer and Etvs; Fig. 2A), with horsts and grabens formed during the Eocene-Oligocene fragmentation of the Scotia Ridge (King and Barker, 1988). According to the ODP stratigraphy (Barker et al., 1988), Eötvös Basin is filled at least by upper Eocene-Quaternary sediments. 3. Materials and methods 3.1. Site descriptions and age model of ODP Site 696 At ODP Site 696 (61°50.96' S, 42°56' W) two holes were drilled at 650 m water depth in Eötvös Basin, at the southeastern margin of the SOM, northern Weddell Sea (Barker et al., 1988; Fig. 2A). Terrigenous to authigenic sediments (646-530 meters below seafloor–mbsf), pelagic sediments (530-214 mbsf), and hemipelagic sediments (2140 mbsf) were deposited from the late Eocene to the Quaternary (Barker et al., 1988; Gersonde and Burckle, 1990; Wei and Wise, 1990; Fig. 2B). Onboard the ship, the upper Eocene-lower middle Miocene terrigenous to authigenic lithological unit designated as Unit VII (646-530 mbsf) was tentatively subdivided into four subunits (Barker et al., 1988): Subunit VIID (645.6 to 606.9 mbsf), organic-rich sandy mudstone facies; Subunit VIIC (606.9 to 569.7 mbsf), glaucony-bearing packstone facies (Barker et al., 1988; López-Quirós et al., 2019); Subunit VIIB (569.7 to 548.9 mbsf), claystone and limestone facies; and Subunit VIIA (548.9 to 529.8 mbsf), rhythmically interbedded sandy mudstone facies with glauconite-bearing sandstone beds (Barker et al., 1988; López-Quirós et al., 2020). This study focuses on subunits VIID, VIIC and VIIB from Hole 696B, interpreted onboard as deposited in a shallow marine environment (Barker et al., 1988; Fig. 3). Stratigraphic age control of Subunit VIID was established through calcareous nannofossils (Wei and Wise, 1990 sensu Villa et al., 2008; Fig. 3). The First Consistent Occurrence (FCO) of Isthmolithus recurvus (617 mbsf; Wei and Wise, 1990) and the occurrence of Reticulofenestra bisecta (643.62 mbsf; Wei and Wise, 1990) places the base at ~36.5 Ma, although the subunit could be as old as 37.6 Ma (Villa et al., 2008). The First Occurrence (FO) of Reticulofenestra oamaruensis is recorded at the base of Subunit VIIC (598.42 to 588.72 mbsf; Wei and Wise, 1990), suggesting a maximum age of about 35.5 Ma (Villa et al., 2008). For the overlying sediments (including subunits VIIC and VIIB), a revised dinocyst-based age model gave a late Eocene to early Oligocene age (Houben et al., 2013, 2019) (Fig. 3). The FO of Stoveracysta kakanuiensis was calibrated to the latest Eocene (>33.8 Ma) in sediments and rocks from the East Tasman Plateau (ODP Site 1172) and in New Zealand (Clowes, 1985). In ODP Hole 696B, the FO of S. kakanuiensis (Houben et al., 2013, 2019) (34.1 Ma; 571.55 mbsf) predates the FO of Malvinia escutiana, used as indicator of the Oligocene isotope event 1 (Oi-1; 33.6 Ma) (Houben et al., 2013, 2019) (569.11 mbsf), which suggests that the EOT was well recovered at this site. The FO of the low-latitude taxon Chiropteridium galea (<33.26 Ma) (Pross et al., 2010) at 552.2 mbsf (Houben et al., 2019) suggests a quite complete and expanded lowermost Oligocene succession. Journal Pre-proof Journal Pre-proof 4 3.2. Methodology and analyses The sediments of the interval under consideration were subjected to different types of analyses: 3.2.1. Facies analyses Sediment facies analyses were conducted for the interval ~646 mbsf to ~549 mbsf (Fig. 3) to establish a stratigraphic framework and attempt a paleoenvironmental reconstruction. Sediment facies were defined on the basis of visual core descriptions, thin sections and core slabs, expanding on the lower-resolution preliminary shipboard descriptions by Barker et al. (1988). Macroscopic visual core observations were aided by high-resolution digital images obtained from archive halves using a Nikon 60mm camera lens mounted on a custom-built line scanner at the Coast Gulf Repository (CGR), Texas A&M University (College Station, Texas, USA). Facies type determination included lithology, sediment textures, grain sizes, sedimentary structures and bioturbation, following Tucker (2001) and references therein. Facies classification is after Dunham (1962) and Mount (1985). Additionally, high-resolution digital images were used for ichnological facies analyses applying a previously established digital procedure (Dorador and Rodrguez-Tovar, 2014, 2018; and references therein). Ichnotaxonomical characterization at the ichnogenus level is based on the recognition of ichnotaxobases in cores (Knaust, 2012, 2017). Composition of biogenic and terrigenous grains, grain size and shape were determined microscopically using petrographic and environmental scanning electron (ESEM) microscopes. The petrographic characterization was made under polarized and cross-polarized light with an OLYMPUS BX60 microscope at the Instituto Andaluz de Ciencias de la Tierra (CSIC-University of Granada, Spain). Back-scattered electron (BSE) and secondary electron (SE) observations were made with an ESEM FEI Quanta 400 microscope at the Centro de Instrumentación Científica (CIC, University of Granada, Spain). Bulk grain-size analyses were completed at the Environnements et Paloenvironnements Ocaniques et Continentaux lab (EPOC, Bordeaux, France). A total of 41 sediment samples were dried overnight in an oven at 40ºC, sieved to remove coarse-grained (>2000 μm in diameter) particles, then measured in a laser microgranulometer Malvern mastersizer hydro 2000G with automatic sampling (0.020 to 2000 μm). X-ray diffraction (XRD) measurements at the Instituto Andaluz de Ciencias de la Tierra (CSIC-University of Granada, Spain) were used to determine the average bulk mineralogical composition of the different facies. 3.2.2. Elemental and stable isotope analyses Total organic carbon (TOC), total nitrogen (TN) and the carbon (δ13C) and nitrogen (δ15N) isotopic composition of bulk sediments were measured to derive a record of the biological origins of the organic matter in the sediments (i.e., the mixing trend between terrestrial and aquatic sources of organic matter) (e.g., Meyers, 1997; Muller and Voss, 1999; Huon et al., 2002). Weight percentages of total organic carbon (% TOC) and total nitrogen (% TN) were obtained using a LECO C-S 125 analyser at the Environnements et Paloenvironnements Ocaniques et Continentaux lab (EPOC, Bordeaux, France) through the total combustion of 70 sediment samples treated with 1N HCL to eliminate inorganic carbon. The precision of TOC measurements based on standards and replicates was better than 0.5%, while TN measurements were better than 0.3%. Portions of carbonate-free sediments were analyzed at the University of Bordeaux to determine δ13C and δ15N composition using a Carlo Erba CN analyzer 2500 interfaced directly to a Micromass-Isoprime mass spectrometer. The δ15N and δ13C values were determined on dried, ground bulk sediments and reported in delta notation (equations 1, 2). Sediments were encapsulated in tin and injected into a Flash 200 elemental analyzer. Each sample was first oxidized under high temperature conditions (~1040ºC) by cobalt and chrome oxides, then reduced in a second column by copper. The resulting gas (N2) was: (1) transferred to the mass spectrometer where it was ionized, (2) accelerated under high voltage (400 μA), (3) deflected after its molecular weight, and (4) caught in a collector. Moreover, δ15N values from certified and in-house standards (Acetanilide, Casein, Glycine, N1 and sdk) were measured and used to adjust the δ15N values from each sediment sample. The precision of the δ15N analyses based on standards and replicates was better than 0.2 ‰. δ13C ratios were obtained following the same procedure as for the δ15N measurements. According to replicates and internal standards, the absolute precision of δ13C is better than 0.1‰. Journal Pre-proof Journal Pre-proof 5 Equation (1): δ15N (‰ vs. Air) = ( N15/N14Csample N15/N14standard− 1) x 103 in which atmospheric N2 is the reference standard (with a G15N = 0‰). Equation (2): δ13C (‰ vs. Air) = ( C13/C12Csample C13/C12standard−1) x 103 in which Vienna PeeDee Belemnite (VPDB) is the reference standard (with a G13C= 0‰). In order to identify the primary factors influencing variations in the elemental and stable isotope analysis, we conducted a Principal Component Analysis (PCA), the simplest multivariate analysis involving a mathematical procedure that transforms a number of possibly correlated variables into a smaller number of groups of closely related variables (e.g., Jolliffe, 2002). PCA computations were performed using the PAST free software package version 2.10 (Hammer et al., 2001). 3.2.3. Lipid biomarker (n-alkane) analyses Long-chain normal n-alkanes (C23-C31) provide details about the production, delivery, and preservation of organic matter in sediments, and their distribution can be used to discriminate between terrigenous and marine organic matter, thus providing insight into paleovegetation and paleoclimates (e.g., Meyers et al., 1997; Ficken et al., 2000; Schefuß et al., 2003; Vogts et al., 2009; Duncan et al., 2019). The n-alkane analyses were performed at the Laboratoire d’Ocanographie et du Climat, Exprimentations et Approches Numériques (LOCEAN-Université Pierre et Marie Curie, Paris, France). First, 70 sediment samples were freeze-dried and crushed to a fine powder. Total lipids were extracted from ~9.5 to 15g of homogenized sediment using a solvent mixture of 40 mL CH2Cl2/CH3OH (3:1, v/v) to which an internal standard (5 α-cholestane) was added. The n-alkane fraction was separated from the polar lipids over a silica column using 3 mL hexane as eluent. After drying the fraction, elemental sulfur was removed through the TBA (tetrabutylammonium) sulfite method (Jensen et al., 1977; Riis and Babel, 1999). Samples were analyzed on a gas chromatograph (GC) (Agilent 6890 N) equipped with a flame ionization detector (FID) and fitted with a 30 m long DB5 fused silica capillary column (0,32 mm i.d., 0.25 μm film thickness). Quantification of n-alkanes was performed manually, by peak area integration in FID chromatograms relative to the internal standard, following equation (3). The GC oven temperature program was set at 120 ºC at a rate of 30 ºC/min, then raised to 320 ºC at a rate of 5 ºC/min. Equation (3): [CnH2n+2](ng/g)= Area ChH2n+2 x standard concentration (ng/g) Injected vol / (Area standard x sample weight (g)) Contribution of n-alkane in sediments from different biological sources (vascular land plants, marine algae or petroleum origin) can be assessed on the basis of specific carbon chain length variations (e.g., Cranwell, 1973; Rieley et al., 1991; Bi et al., 2005). The following n-alkane-based indices were used in this study: 1. Carbon Preference Index (CPI) (Farrington and Tripp, 1977; Kennicutt et al., 1987; Rieley et al., 1991; Hedges and Prahl, 1993; Bush and McInerney, 2013): CPI=1 2((Σodd (𝑛−C25-31) Σeven (𝑛−C24-30))+(Σodd (𝑛−C25-31) Σeven (𝑛−C26-30))) 2. Average chain length (ACL) (Poynter et al., 1989; Simoneit et al., 1991; Ficken et al., 2000; Schefuß et al., 2003): ACL= Σ[Ci]·𝑖 Σ[Ci] Ci = carbon number of the odd chain length n-alkanes (i.e., from n-C25 to n-C31). i = concentration of the odd n-alkanes. Journal Pre-proof Journal Pre-proof 6 3. Terrestrial n-alkanes Index (TI) (Mahiques et al., 2017): TI= ΣC27+29+31 TOC 4. Aquatic plant n-alkane proxy (Paq) (Ficken et al., 2000): Paq = C23 +C25 C23 +C25 +C29 +C31 Relationships between n-alkane indices were investigated using Pearson’s correlation coefficients, considered statistically significant at p < 0.05. 3.2.4. Palynological data Terrestrial palynomorph identification in a total of eight samples collected between 645.6–597.2 mbsf spanning the late Eocene (~37.6–35.5 Ma; Fig. 3) served to compliment sedimentological interpretations. Fossil spores/pollen grains were identified microscopically using Leica DM500 and Leica DM2000 transmitted light microscopes at 200x and 1000x magnification at the Department of Geography and Environmental Sciences (University of Northumbria, England). In addition, we compare our new results to palynological investigations on the same sedimentary record (late Eocene-early Oligocene, ~37.6–32.2 Ma; Houben et al., 2013, 2019), in view of the abundance of terrestrial palynomorphs relative to the abundance of marine dinocysts, a commonly used proxy to trace organic matter sourcing. 4. Results 4.1. Sediment facies in Hole 696B Four lithofacies could be defined, numbered F-I through F-IV, from top to bottom (in contrast with the three subunits by Barker et al., 1988) (Fig. 3). a) Facies I – Claystone and clayey mudstone Facies I extends from 558 to ~550 mbsf (cores 53R sections 1 to 7). This facies consists of massive very dark gray to dark brown claystones and gray clayey mudstones (Figs. 3 and 4A). Black carbonaceous-rich mudstone bands up to 1.5 cm thick were observed interbedded throughout core 53R section 5 (556.4 to 554.9 mbsf) (Fig. 4B). Facies I is scarcely to moderately bioturbated, containing sparse laminations. Local occurrences of ichnofossils mainly consist of Chondrites, probable Nereites and rare Planolites (Figs. 4A and B). Rare millimeter-sized ice rafted debris (IRD) was observed in core 53R sections 1 and 2 (Fig. 3). The claystone matrix consists of clay-size particles and clay minerals, dominated by smectite (Fig. 5A). Quartz, feldspar, rare diatom tests and indistinct, pyritized siliceous bioclast fragments, as well as pyrite and barite, are present in the clay fraction (e.g., Fig. 5B, C; Supplementary Fig. S1A-C). Organic matter relicts were observed in the black carbonaceous-rich mudstone bands, as shown by ESEM analysis including EDX spectra (Fig. 5C, D). b) Facies II – Silty to sandy mudstone Facies II extends from 575.9 to 558.5 mbsf (core 55R sections 1 through 6 and 54R sections 1 through 4), while no sediments were recovered from 568.2 to 563 mbsf (Fig. 3). This facies consists of massive and mottled light olive gray and pale yellow silty mudstones (Figs. 3 and 4C-E). Sandy mudstones are interbedded throughout core sections 55R-5 and 55R-3, forming two coarse-grained intervals that consist mainly of subto well-rounded quartz and rock fragments (Fig. 5E, F). Quartz grains are marked by conchoidal fracture surfaces (Fig. 5F). Reworked glaucony grains were also identified. Sediments within these two coarse-grained intervals show coarsening-upward sequences. No primary sedimentary structures were observed due to ubiquitous moderate to intense bioturbation. The ichnoassemblage is relatively diverse, mainly consisting of Planolites, Chondrites and Nereites. Furthermore, traces of Thalassinoides, Ophiomorpha and Asterosoma are locally observed in core 55R sections 3 to 5 (Fig. 4C-E). Burrows are filled with silt and fine sand (e.g., Fig. 5G). Common millimeter-sized IRD was also observed (see Fig. 3). Alkali feldspar, glaucony fragments and mostly pyritized radiolarian tests (and probably diatoms) were also identified (Fig. Journal Pre-proof Journal Pre-proof 7 5H). c) Facies III – Glauconitic packstone Facies III extends from ~588.8 to 577.9 mbsf (core 57R section 1 to 56R section 1; Fig. 3); no sediments were recovered from 580.5 to 587.6 mbsf. Facies III (very poorly recovered) includes greenish gray glauconitic packstone and pale yellow to light olive gray silty and sandy mudstone with abundant glaucony grains (López-Quirós et al., 2019) (Fig. 4F). According to López-Quirós et al. (2019), mature glauconitized grains of 125–500 μm within the glauconitic packstone facies form by authigenic transformation of pellets in sandy to silty smectite-rich, mixed terrigenouscarbonatic sediments (Fig. 5I and Supplementary Fig. S1E). Other authigenic minerals such as zeolite, pyrite and silica are found in the matrix among glaucony grains. Quartz, alkali feldspar and clay minerals are present in the clay fraction (see e.g., Fig. 3 and Supplementary Fig. S5 in López-Quirós et al., 2019). This facies is moderately bioturbated, with Phycosiphon exclusively (e.g., Fig. 4F). d) Facies IV – Sandy mudstone Facies IV extends from the bottom of the hole at 645.6 to ~597.2 mbsf (core 62R section 8 to 58R section 1; Fig. 3). Facies IV consists of pale olive to olive gray sandy mudstone. Minor lithologies include glaucony-bearing, carbonatecemented sandy mudstone (Fig. 4G) and clayey mudstone. Sediments are structureless, and contain abundant millimeter-size bivalve and probably gastropod shell fragments (Fig. 4H). Terrigenous components are mainly angular to subangular grains of predominantly quartz with subordinate alkali feldspar, mica and undifferentiated rock fragments (Fig. 5J, K), although moderate occurrences of well-rounded grains were observed in core 59R. Benthic foraminifera are very abundant and diverse in the lower part of Facies IV (cores 61R, 62R) (Figs. 3 and 6A), decreasing in abundance above 626 mbsf (cores 59R, 60R). Overall, benthic foraminifera are moderate to well-preserved (Fig. 6A). Sediments of this facies are barren of planktonic foraminifera, with the exception of a carbonate-cemented sandy mudstone at 640 mbsf (core section 62R-4; Fig. 6B) with moderately abundant but low-diversity planktonic assemblage. Phytoplankton Bolboforma were recognized in cores 62R-60R (Fig. 6B). The pollen and spore assemblage contains the paratropical taxa Arecipites (Arecaceae), Beaupreaidites (Beauprea), Myrtaceidites (Myrtaceae) and Dacrydiumites (Dacrydium), in addition to the typical Nothofagus (pollen taxa: Nothofagidites) podocarp conifer assemblage (Fig. 6C). In addition, Barker et al. (1988) reported rare reworked freshwater diatoms in core 58R-CC. Silt-sized orange to brownish-green immature (nascent or slightly evolved) glaucony grains were observed throughout (Fig. 5J), but more abundant at some levels: 641-639, 632-630, and 608597.2 mbsf (Fig. 3). The bioturbation is moderate to intense, with well-preserved traces of pellet-lined Ophiomorpha throughout (e.g., Fig. 4H). Well-preserved Asterosoma and Teichichnus ichnofossils were observed in the carbonatecemented sandy mudstone at ~599 mbsf (Fig. 4G). 4.2. Vertical distributions of TOC, TN, C/N ratio, δ13C and δ15N The vertical distributions of TOC and TN display a progressive increase from the late Eocene to the early Oligocene (Fig. 7). Highest TOC and TN concentrations were found in Facies I (Table 1; Fig. 7), the highest one detected at 556 mbsf in a black carbonaceous-rich mudstone band within core section 53R-5 (TOC: 1.25% and TN: 0.09%; see Supplementary Fig. S1A). Facies II, III and IV display progressively lower TOC and TN concentrations (Table 1; Fig. 7). The vertical distribution of C/N exhibits small variations with the exception of a large peak (18%; Table 1) in the carbonate-cemented sandy mudstone horizon at ~599 mbsf (core section 58R-2; Facies IV) (Fig. 7), as shown for each facies (from I to IV) in Table 1 (Supplementary Table S1). The vertical distribution of δ13C varies from –25.60 to – 23.95‰, whereas δ15N varies from 1.34 to 3.49 (Fig. 7; Table 1). The highest δ15N values were found in Facies III and IV (Table 1), in the glauconitic packstone at ~580 mbsf (core section 56R-2; Facies III). In contrast, δ15N values could not be determined because of low N concentration in the carbonate-cemented sandy mudstone horizon at ~599 mbsf (core section 58R-2) (Table 1; Supplementary Table S2). For the δ13C and δ15N range and average values in each facies (from I to IV) see Table 1 (for complete information see Supplementary Table S1). The result of PCA revealed two main axes that explain most variation in geochemical parameters (TOC, TN, C/N, δ13C and δ15N) (see Supplementary Fig. S2). The first principal component (PC1) accounted for 82.3% of the variation; Journal Pre-proof Journal Pre-proof 8 together with the second principal component (PC2), this value increased to 91%. The correlation between TOC, C/N and δ13C with PC1 is high, but correlation with TN and δ15N is low. In contrast, the correlation of TN and δ15N with PC2 is moderate, whereas the TOC, C/N and δ13C exhibited low values. The PCA biplot mainly revealed a deviation of the δ15N and C/N ratio with respect to the rest of the components. 4.3. Distribution of n-alkane variables Total concentrations of C23-C31 n-alkanes range from 236 ng/gTOC to 1639 ng/gTOC in Facies I, with an average value of 953.8 ng/gTOC (Fig. 8; Supplementary Table S2). Long chain n-alkanes n-C27, n-C29 and n-C31 are the most common (Supplementary Table S2 and Fig. S3), n-C29 being the most prominent. However, n-C27 and n-C29 are the dominant n-alkanes in the interbedded black carbonaceous-rich mudstone bands, which also have increased proportions of n-C23 and n-C25 (Fig. 8; Supplementary Table S2 and Fig. S3). The average values of CPI, ACL, Paq, TI, n-C29/n-C27, n-C27/n-C31 and n-C23/n-C29 are shown in Table 1 (Supplementary Table S2). The highest Paq and lowest TI concentrations occur in the interbedded black carbonaceous-rich mudstone bands (Fig. 8; Supplementary Table S2). Total concentrations of C23-C31 n-alkanes range from 424 to 1523 ng/gTOC, averaging 687 ng/gTOC in Facies II (Fig. 8; Supplementary Table S2). Long chain n-alkanes such as n-C27, n-C29 and n-C31 dominate, with n-C29 most prominent (see Supplementary Fig. S3). The average values of CPI, ACL, Paq, TI, n-C29/n-C27, n-C27/n-C31 and n-C23/nC29 are shown in Table 1 (for details, see Supplementary Table S2). TI exhibits the highest values in the studied section (Table 1). Total concentrations of C23-C31 n-alkanes range from 468 ng/gTOC to 742 ng/gTOC, averaging 592.7 ng/gTOC in Facies III (Fig. 8; Supplementary Table S2). Although n-C25, n-C27, n-C29 and n-C31 are abundant, n-C29 is the most prominent (Supplementary Fig. S3). The average values of ACL, Paq and the n-C29/n-C27, n-C27/n-C31 and n-C23/n-C29 display slight variability, with higher variability in CPI and TI (Table 1; Fig. 8). CPI exhibits the highest values in the studied section (Table 1). Total concentrations of C23-C31 n-alkanes average 487 ng/gTOC in Facies IV (Fig. 8; Supplementary Table S2). The n-alkane distributions display prominent peaks in n-C23, n-C25, n-C27, n-C29 and n-C31 (Supplementary Fig. S3). Midchain n-alkanes (i.e., n-C23 and n-C25) show slightly lower concentrations than long chain homologs (> n-C27). Alkanes n-C23, n-C24, n-C26, n-C28 and n-C30 were below detection at ~599 mbsf (core section 58R-2) (Table 1; Supplementary Table S2). The average values of CPI, ACL, TI, Paq, n-C29/n-C27, C27/n-C31 and n-C23/n-C29 are indicated in Table 1. Pearson’s correlation coefficients were estimated between the n-alkane variables (Supplementary Fig. S4). Significant statistical correlations are found between ACL and Paq (r = 0.989, p < 0.0000), ACL and n-C23/n-C29 (r = 0.964, p < 0.0000), and Paq and n-C23/n-C29 (r = 0.965, p < 0.0000), with weaker correlations between ACL and nC27/n-C29 (r = 0.720, p < 0.0000) and TI and n-C23/n-C29 (r = 0.616, p < 0.0000). 5. Interpretations and discussion 5.1. Evolution of depositional environments: Evidence of a sustained relative sea-level rise The succession of sedimentary facies documents a long-term trend driven by tectonic and climatic processes, and several depositional phases can be distinguished. 5.1.1. Late Eocene (~37.6–35.5 Ma) This interval is characterized by the sandy mudstones of Facies IV (Fig. 3), deposited with an average sedimentation rate of ~4 cm/kyr when the SOM was attached to, or quite close to, the Antarctic Peninsula. The SOM, Seymour Island and James Ross Basin constitute the remnants of an ancient back-arc basin at the northern Antarctic Peninsula (Elliot, 1988; Fig. 1B). Poorly consolidated and bioturbated sands and silts from the nearby Seymour Island and James Ross Basin reflect shallow-marine and coastal environments (e.g., Stilwell and Zinsmeister, 1992; Marenssi et al., 1998, 2002; Wellner et al., 2011) (Fig. 1B). The similar paleogeographic setting and sediment composition in Facies IV and Seymour Island could point to related sediment sources and depositional environments. However, evidence of longdistance sediment transport and reworking —e.g. well-rounded terrigenous grains, significant taphonomic features or occurrence of relict foraminifera tests— is not found (Figs. 5J, K and 6A, B). In addition, previous interpretations proposed that long-distance transport from the Weddell Sea hinterland and the Dronning Maud land via large icebergs could be a viable mechanism for the accumulation of the sand-sized fractions within Facies IV (Carter et al., 2017), Journal Pre-proof Journal Pre-proof 15 tectonic units for the Antarctic Peninsula (modified after Elliot, 1988). Tectonic features after Maldonado et al. (2000, 2014). SOM: South Orkney Microcontinent; SOI: South Orkney Islands; BB: Bransfield Basin; SFZ: Shackleton Fracture Zone; HFZ: Hero Fracture Zone. Figure 2. Geological setting of the South Orkney Microcontinent (SOM). A) Regional bathymetry of the SOM shelf and location of ODP (696, 695 and 697) and dredge sites, with selected bathymetric profiles (A-A’ and B-B’) and a multichannel seismic line (Th87006). Structural features after Busetti et al. (2000) and King and Barker (1988). Bathymetric map extracted from GEBCO 2014 (NOAA/NCEI). PBn: Protector Basin; PBk: Pirie Bank; DBn: Dove Basin; BBk: Bruce bank. B) Multichannel seismic profile (Th87006; available at the Antarctic Seismic Data Library System: http://sdls.ogs.trieste.it/) crossing Eötvös Basin. EOT and MPT (Eocene-Oligocene and Miocene-Pliocene transitions, respectively) are age assigned to seismic reflectors based on the ODP Site 696 stratigraphy, shown in a simplified lithological log of Site 696 (modified after Barker et al., 1988). Age assessment for the ‘EOT’ seismic marker is from Houben et al. (2013). Figure 3. Stratigraphic log of the studied sedimentary section from Hole 696B. From left to right: Age-depth plot based on biostratigraphy, cores, core recovery, lithology/facies, sediment textures, relative abundance of ichnofacies types, authigenic/diagenetic mineral occurrences, grain size, and clay minerals (%). Core recovery: black = recovery, white = no recovery. Note that divisions in the recovery denote the sections for each core, from 1 to X from top to bottom. Biostratigraphic age constraints are from Wei and Wise (1990) and Houben et al. (2013, 2019). For comparison, lithologic subunits are represented as defined on shipboard (Barker et al., 1988) together with the lithologies re-defined in this work. Grain size is represented here as down-section total grain size distribution. In this distribution plot (for each characteristic individual sample particle size distribution), the y-axis represents depth down the section, x-axis is particle size, and the colors represent the volume of the sample within those grain-size classifications, warmer colors being higher percentages, cooler colors lower percentages. Additionally, the mean grain size evolution (D50 µm) is plotted. Clay minerals are from Robert and Maillot (1990). Figure 4. Detailed sediment facies and associated ichnofabrics identified at Hole 696B. A) and B) Core slab examples of Facies I (claystone and clayey mudstone; core sections 53R-5) showing Chondrites (Ch) and Nereites (Ne) burrows. C), D) and E) Core slab examples of Facies II (sandy to silty mudstone; core 54R section 3 and 55R sections 1 and 4, respectively) displaying burrows of Chondrites (Ch), Nereites (Ne), Planolites (Pl), Ophiomorpha (Oph), Asterosoma (As) and Thalassinoides (Th). F) Core slab example of Facies III (glauconitic packstone; core section 56R-2) with possible Phycosiphon (Ph) burrows. G) and H) Core slab examples of Facies IV (carbonate-cemented [G] and structureless [H] sandy mudstone; core 58R section 2 and 59R section 1, respectively) displaying burrows of Asterosoma, Planolites, Ophiomorpha and Teichichnus (Te). Shell fragments are also shown in (H). The vertical white bar scale is 2 cm. Figure 5. Sedimentation at the studied Hole 696B sedimentary section. A) SEM photomicrograph (SE) of Facies I (core sections 53R-4) showing a smectite-dominated matrix. B) SEM (SE) photomicrograph and related energy-dispersive Xray (EDX) analysis of Facies I (core section 53R-5) framboidal pyrite. C) SEM (SE) photomicrograph showing examples of organic matter (OM) relicts, barite and framboidal pyrite in Facies I (core section 53R-5, black organic rich-layer). EDX analysis of the OM relict (see C peak in the spectrum) and barite (see the triple Ba peaks in the spectrum) are also shown. D) SEM (SE) photomicrograph of a detailed OM (carbon) relict within Facies I (core section 53R-5, black organic rich-layer). Note also bioclast remains (yellow arrow). E) and F) Sieved siliciclastic grains (binocular glass and SEM (SE) photomicrographs, respectively) corresponding to one of the coarse-grained mudstone intervals observed within Facies II (core section 55R-3). Quartz and alkali feldspars grains dominate the siliciclastic components. The red arrow in (E) is points to a possible magmatic rock fragment, whereas yellow arrows in (F) indicate quartz grains with conchoidal fracture surfaces. G) Plane-polarized light (PPL) photomicrograph showing burrowed silty mudstone of Facies II (core section 55-4). H) PPL photomicrograph of Facies II (core section 55R-4). G: detrital glaucony grain; R: radiolarian tests. I) PPL photomicrograph of Facies III (glaucony-rich packstone sediments; core section 56R-2). Enlarged area corresponds to a SEM (SE) photomicrograph displaying a flaky honeycombed and lamellar glaucony nanostructure. J) PPL photomicrograph of Facies IV (core section 62R-4) showing predominantly angular to subangular grains of quartz and alkali feldspars. G: poorly evolved glaucony grains; F: benthic foraminifer. K) Cross-polarized light (CPL) photomicrograph of Facies IV (core section 58R-2) showing subangular to wellrounded siliciclastic components: quartz, alkali feldspar, plagioclase and mica grains. Journal Pre-proof Journal Pre-proof 16 Figure 6. A) SEM (SE) photomicrographs of moderate to well-preserved benthic foraminifera whole tests in Facies IV (cores 62R-60R). A detailed cross-sectional view of the wall of a benthic foraminifera test is also shown. Note that corresponding surface EDX analysis of benthic foraminifera indicate a calcium carbonate composition. B) SEM (SE) photomicrographs of moderateto well-preserved planktonic foraminifera (white arrow) and Bolboforma (yellow arrow) in Facies IV (core section 62R-4). A detailed artificially broken planktonic foraminiferal test (to reveal internal texture) is also shown. Enlarged area corresponds to the cross-sectional view of the wall texture, displaying moderate to good preservation. C) Selected fossil spore/pollen grains of Facies IV. Figure 7. Vertical down section distribution of total organic carbon (TOC), total nitrogen (TN), C/N, δ13C and δ15N values for studied Hole 696B sediment section, versus age. Gray shading: organic rich core 53R section 5 within Facies I; Green shading: glauconitic Facies III. Dinocyst assemblages are from Houben et al. (2013, 2019). Figure 8. Vertical distribution of n-alkane variables/ratios (ACL, CPI, Paq, n-C29/n-C27, n-C27/n-C31, n-C23/n-C29, TI and total concentrations of C23-C31) at Hole 696B sediment section versus age. Gray shading: organic rich core 53R section 5 within Facies I; Green shading: glauconitic Facies III. Terrestrial palynomorphs (undifferentiated) are from Houben (2012). Sporomorph (fern spores and pollen grains) diversity is from Mohr (1990, 2001). ACL: average chain length; CPI: carbon preference index; Paq: aquatic plant n-alkane proxy; TI: terrestrial n-alkane index. Figure 9. A) Total nitrogen (TN) to total organic carbon (TOC) correlation. Very high correlation indicates that TN is mostly organic. The Redfield ratio of marine phytoplankton (6.6) is plotted for comparison. B), C) and D) Marine vs. terrestrial origin of the sediment organic matter as a function of δ13C, δ15N and C/N values. The estimated ranges of marine algae, lacustrine algae, marine cyanobacteria and C3 land plants are indicated for comparison (adapted from Meyers, 1997; for complete end member ranges see references in the discussion). Figure 10. Paleoceanographic and paleogeographic reconstructions deduced from the preset study at the EoceneOligocene transition (EOT ~34 Ma). A) 3-D depositional model involving organic-rich deposition in the shallow-water epicontinental Eötvös Basin during sustained sea-level rise conditions. Upwelled nutrient-rich deep waters led to high productivity in surface waters, while organic matter settling through the water column triggered a mid-water oxygendepleted zone intersecting the continental slope. B) Paleogeographic reconstruction at the EOT (~34 Ma) around the Drake Passage-Scotia Sea, with the estimated location of the South Orkney Microcontinent (SOM) and ODP Site 696. Plate reconstruction adapted from GPlate software (Boyden et al., 2011). Structural features displayed in the map are adapted from Eagles and Jokat (2014) and references therein. T: Terror Bank; PB: Pirie Bank; BB: Bruce Bank; DB; Dove Bank; SGM: South Georgia Microcontinent; WSDW: Weddell Sea Deep Water; AABW: Antarctic Bottom Water; CDW: Circumpolar Deep Water. Table 1. Average values of the bulk organic matter (TOC, TN, related C/N ratio, δ13C and δ15N) and molecular (nalkane) variables. Min-max values in parenthesis. For complete information see Supplementary Tables S1 and S2. Note that average values in Facies IV distinguish between background sedimentation (BS) and carbonate-cemented (CC). REFERENCES Altabet, M. A., François, R., 1994. Sedimentary nitrogen isotopic ratio as a recorder for surface ocean nitrate utilization. Global Biogeochemical Cycles, 8, 103-l 16. Amorosi, A., 1995. Glaucony and sequence stratigraphy: a conceptual framework of distribution in siliciclastic sequences. Journal of Sedimentary Research 65, 419– 425. Amorosi, A., 1997. Detecting compositional, spatial and temporal attributes of glaucony: a tool for provenance research. Sedimentary Geology, 109, 135–153. Amorosi, A., 2012. The occurrence of glaucony in the stratigraphic record: distribution patterns and sequence stratigraphic significance. International Association of Sedimentologists Special Publications 45, 37–54. Anderson, J.M., Warny, S., Askin, R.A., Wellner, J.S., Bohaty, S.M., Kirshner, A.E., Livsey, D.N., Simms, A.R., Smith, T.R., Ehrmann, W., Lawver, L.A., Barbeau, D., Wise, S.W., Kulhenek, D.K., Weaver, F.M., Majewski, W., 2011. Progressive Cenozoic cooling and the demise of Antarctica's last refugium. Proceedings of the Journal Pre-proof Journal Pre-proof 17 National Academy of Sciences 108, 11299–11726. Arbi, I., Liu, S., Zhang, J., Wu, J., Huang, X., 2018. Detection of terrigenous and marine organic matter flow into a eutrophic semi-enclosed bay by δ13C and δ15N of intertidal macrobenthos and basal food sources. Science of the Total Environment, 613, 847–860. Arndt, J.E., Schenke, H.W., Jakobsson, M., Nitsche, F.O., Buys, G., Goleby, B., Rebesco, M., Bohoyo, F., Hong, J., Jenny Black, J., Greku, R., Udintsev, G., Barrios, F., Reynoso-Peralta, W., Taisei, M., Wigley, R., 2013. The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0—A new bathymetric compilation covering circum-Antarctic waters. Geophysical Research Letters, 40(12), 3111-3117. Askin, R.A., 2000. Spores and pollen from the McMurdo Sound erratics, Antarctica. In: Stilwell, J.D., Feldmann, R.M. (Eds.), Paleobiology and Paleoenvironments of Eocene Fossiliferous Erratics, McMurdo Sound, East Antarctica. AGU Ant. Res. Series 76, pp. 161–181. Askin, R.A., Raine, J.I., 2000. Oligocene and Early Miocene Terrestrial Palynology of the Cape Roberts Drillhole CRP-2/2A, Victoria Land Basin, Antarctica. Terra Antarctica 7, 493–501. Bakun, A., 2017. Climate change and ocean deoxygenation within intensified surface-driven upwelling circulations. Phil. Trans. R. Soc. A 375: 20160327. Banerjee, S., Bansal, U., Pande, K., Meena, S.S., 2016. Compositional variability of glauconites within the Upper Cretaceous Karai Shale Formation, Cauvery Basin, India: Implications for evaluation of stratigraphic condensation. Sedimentary Geology, 331, 12–29. Banerjee, S., Chattoraj, S. L., Saraswati, P. K., Dasgupta, S., Sarkar, U., 2012. Substrate control on formation and maturation of glauconites in the Middle Eocene Harudi Formation, western Kutch, India. Marine and Petroleum Geology, 30(1), 144–160. Barker, P. F., Thomas, E., 2004. Origin, Signature and Palaeoclimatic Influence of the Antarctic Circumpolar Current. Earth Science Review, 66: 143-162. Barker, P.F., 2001. Scotia Sea regional tectonic evolution: implications for mantle flow and palaeocirculation. Earth Science Review, 55, 1–39. Barker, P.F., Burrell, J., 1977. The opening of Drake Passage. Marine Geology, 25, 15–34. Barker, P.F., Dalziel, I.W.D., Storey, B.C., 1991. Tectonic evolution of the Scotia Arc region. In: Tingey, R.J. (Ed.), Antarctic Geology. Oxford Univ Press, pp. 215–248. Barker, P.F., Kennett, J.P., Shipboard Scientific Party, 1988. Proceedings of the Ocean Drilling Program, Initial Reports, 113. Ocean Drilling Program, College Station, Texas. Basak, C., Martin, E.E., 2013. Antarctic weathering and carbonate compensation at the Eocene–Oligocene transition. Nature Geosciences, 6, 121–124. Bi, X., Sheng, G., Liu, X., Li, C., Fu, J., 2005. Molecular and carbon and hydrogen isotopic composition of n-alkanes in plant leaf waxes. Organic Geochemistry 36, 1405–1417. Bohaty, S.M., Zachos, J.C., Delaney, M.L., 2012. Foraminiferal Mg/Ca evidence for Southern Ocean cooling across the Eocene–Oligocene transition. Earth and Planetary Science Letters, 317, 251–261. Bohoyo, F., Galindo-Zaldívar, J., Maldonado, A., Schreider, A. A., Suriñach, E., 2002. Basin development subsequent to ridge-trench collision: the Jane Basin, Antarctica. Marine Geophysical Researches, 23, 413–421. Bourbonniere, R.A., Meyers, P.A., 1983. Characterization of sedimentary humic matter by alkaline hydrolysis. Organic Geochemistry. 3: 131–142. Boyden, J.A., Müller, R.D., Gurnis, M., Torsvik, T.H., Clark, J.A., Turner, M., Ivey-Law, H., Watson, R.J., Cannon, J.S., 2011. Next-generation plate-tectonic reconstructions using GPlates. Geoinformatics, 95–114. Brandes, J.A., Devol, A.H., 2002. A global marine-fixed nitrogen isotopic budget: implications for Holocene nitrogen cycling. Global Biogeochemical Cycles, 16 (4), 1120. Breitburg, D., Levin, L.A., Oschlies, A., Grégoire, M., Chavez, F.P., Conley, D.J., Garçon, V., Gilbert, D., Gutiérrez, D., Isensee, K., Jacinto, G.S., Limburg, K.E., Montes, I., Naqvi, S.W.A., Pitcher, G.C., Rabalais, N.N., Roman, M.R., Rose, K.A., Seibel, B.A., Telszewski, M., Yasuhara, M., Zhang, J., 2018. Declining oxygen in the global ocean and coastalwaters. Science. 359 (6371). Bromley, R.G., Ekdale, A.A., 1984. Chondrites: a trace fossil indicator of anoxia in sediments, Science, 80, 872–875. Journal Pre-proof Journal Pre-proof 18 Busetti, M., Zanolla, C., Marchetti, A., 2000. Geological Structure of the South Orkney Microcontinent. Terra Antartica 8(2), 71-78. Bush, R.T., McInerney, F.A., 2013. Leaf wax n-alkane distributions in and across modern plants: implications for paleoecology and chemotaxonomy. Geochimica et Cosmochimica Acta, 117, 161–179. Bush, R.T., McInerney, F.A., 2015. Influence of temperature and C4 abundance on nalkane chain length distributions across the central USA. Organic Geochemistry 79, 65–73. Baas, M., Pancost, R., van Geel, B., Sinninghe Damsté, J.S., 2000. A comparative study of lipids in Sphagnum species. Organic Geochemistry 31, 535–541. Calvo, E., Pelejero, C., Logan, G.A., De Deckker, P., 2004. Dust-induced changes in phytoplankton composition in the Tasman Sea during the last four glacial cycles. Paleoceanography 19, PA2020. doi:10.1029/2003PA000992. Carter, A., Riley, T. R., Hillenbrand, C.‐D., Rittner, M., 2017. Widespread Antarctic glaciation during the Late Eocene. Earth and Planetary Science Letters, 458, 49–57. Case, J. A., 1988. Paleogene floras from Seymour Island, Antarctic Peninsula. Geological Society of American Memoir, 169:523-530. Case, J.A., Woodburne, M.O., 1988. A new genus of polydolopid marsupial from Antarctica. Geological Society of American Memoir, 169:505-521. Chattoraj, S.L., 2016. Glauconite in Stratigraphic Framework of Palaeogene of Kutch, India. Lambert Academic Publishing, Saarbrcken, Germany (ISBN: 978-3-659-97455-7). Chattoraj, S.L., Banerjee, S., Saraswati, P.K., 2009. Glauconites from the late palaeocene-early eocene naredi formation, western kutch and their genetic implications. Journal of the Geological Society of India, 73, 567–574. Cline, J. D., Kaplan, I. R., 1975. Isotopic fractionation of dissolved nitrate during denitrification in the eastern tropical North Pacific Ocean. Marine Chemistry, 3, 271–299. Clowes, C.D., 1985. Stoveracysta, a new gonyaulacacean dinoflagellate genus from the upper Eocene and lower Oligocene of New Zealand. Palynology 9, 27–35. Cook, P.J., Marshall, J.F., 1981. Geochemistry of iron and phosphorus-rich nodules from the East Australian continental shelf. Marine Geology 41, 205-221. Coren, F., Ceccone, G., Lodolo, E., Zanolla, C., Zitellini, N., Bonazzi, C., Centonze, J., 1997. Morphology, seismic structure and tectonic development of the Powell Basin, Antarctica. Journal of the Geological Society, London, 154, 849 – 862. Coulon, F., Pelletier, E., Gourhant, L., Delille, D., 2005. Effects of nutrient and temperature on degradation of petroleum hydrocarbons in contaminated sub-Antarctic soil. Chemosphere 58, 1439–1448. Coxall, H.K., Wilson, P.A., Pälike, H., Lear, C.H., Backman, J., 2005. Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean. Nature, 433, 53–57. Cramer, B.S., Toggweiler, J.R., Wright, J.D., Katz, M.E., Miller, K.G., 2009. Ocean overturning since the Late Cretaceous: Inferences from a new benthic foraminiferal isotope compilation. Paleoceanography 24, PA4216. DOI: 10.1029/2008PA001683. Cranwell, P.A., 1973. Chain-length distribution of n-alkanes from lake sediments in relation to post-glacial environmental change. Freshwater Biology, 3, 259–265. Crouch, E.M., Brinkhuis, H., 2005. Environmental change across the Paleocene-Eocene transition from eastern New Zealand: A marine palynological approach. Marine Micropaleontology. 56 : 138-160 Dale, B., 1996. Dinoflagellate Cyst Ecology: Modeling and Geological Applications (eds) Jansonius, J., McGregor, D. C. In Palynology: Principles and applications AASP Foundation. 3 : 1249-1275. Dalziel, I.W.D., 1984. Tectonic evolution of a forearc terrane, southern Scotia Ridge, Antarctica. Geological Society of America, Special Paper 200, 32pp. Dalziel, I.W.D., Elliot, D.H., 1971. Evolution of the Scotia arc. Nature, 233, 246–252. De Mahiques, M.M., Hanebuth, T.J.J., Nagai, R.H., Bícego, M.C., Figueira, R.C.L., Sousa, S.H.M., Burone, L., Franco-Fraguas, P., Taniguchi, S., Salaroli, A.B., Dias, G.P., Prates, D.M., Freitas, M.E.F., 2017. Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil). Ocean Science 13, 209–222. Journal Pre-proof Journal Pre-proof 19 De Wit, M.J., 1977. The evolution of the Scotia Arc as a key to the reconstruction of the southwestern Gondwanaland. Tectonophysics, 37, 53–81. DeConto, R. M., Pollard, D., 2003. Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2. Nature, 421(6920), 245–249. Demaison, G.J., Moore, G.T., 1980. Anoxic environments and oil source bed genesis. American Association of Petroleum Geology Bulletin, 64:1179–1209. Diefendorf, A.F., Freeman, K.H., Wing, S.L., Graham, H.V., 2011. Production of n-alkyl lipids in living plants and implications for the geologic past. Geochimica et Cosmochimica Acta 75, 7472–7485. Diefendorf, A.F., Freimuth, E.J., 2017. Extracting the most from terrestrial plant-derived n-alkyl lipids and their carbon isotopes from the sedimentary record: a review. Organic Geochemistry 103, 1–21. Dorador, J., Rodríguez-Tovar, F.J., 2014. A novel application of digital image treatment by quantitative pixel analysis to trace fossil research in marine cores. PALAIOS 29 (10), 533–538. Dorador, J., Rodríguez-Tovar, F.J., 2018. High-resolution image treatment in ichnological core analysis: initial steps, advances and prospects. Earth-Science Review, 177, 226–237. Droser, M.L., Bottjer, D.J., 1993. Trends and patterns of Phanerozoic ichnofabrics. Annual Review of Earth and Planetary Sciences 21, 205–225. Duncan, B., McKay, R., Bendle, J., Naish, T., Inglis, G. N., Moossen, H., Levy, R., Ventura, G.T., Lewis, A., Chamberlain, B., Walker, C., 2019. Lipid biomarker distributions in Oligocene and Miocene sediments from the Ross Sea region, Antarctica: Implications for use of biomarker proxies in glacially influenced settings. Palaeogeography, Palaeoclimatology, Palaeoecology 516, 71-89. Dunham, R.J., 1962. Classification of carbonate rocks according to depositional texture. In: Ham, W.E. (Ed.), Classification of Carbonate Rocks. A Symposium. American Association of Petroleum Geology Memoir 1, pp. 108– 121. Eagles, G., Jokat, W., 2014. Tectonic reconstructions for paleobathymetry in drake passage. Tectonophysics, 611, 28– 50. Eagles, G., Livermore, R.A., 2002. Opening history of Powell Basin, Antarctic Peninsula. Marine Geology, 185, 195– 205. Eagles, G., Livermore, R.A., Morris, P., 2006. Small basins in the Scotia Sea: the Eocene Drake Passage gateway. Earth and Planetary Science Letters, 242, 343–353. Egan, K. E., Rickaby, R.E.M., Hendry, K.R., Halliday, A.N., 2013. Opening the gateways for diatoms primes Earth for Antarctic glaciations. Earth and Planetary Science Letters, 375, 34–43. Ehrmann, W.U., Mackensen, A., 1992. Sedimentological evidence for the formation of an East Antarctic ice sheet in Eocene/Oligocene time. Palaeogeography, Palaeoclimatology, Palaeoecology, 93, 85–112. Eiserhardt, W. L., Svenning, J.-C., Kissling, W. D., Balslev, H., 2011. Geographical ecology of the palms (Arecaceae): determinants of diversity and distributions across spatial scales. Annals of Botany, 108, 1391–1416 Ekdale A.A., Mason T.R., 1988. Characteristic trace-fossil associations in oxygen-poor sedimentary environments. Geology 16, 720–723. Elliot, D.H., 1988. Tectonic setting and evolution of the James Ross Basin, Northern Antarctic Peninsula. In Geology and Paleontology of Seymour Island, Antarctic Peninsula (eds RM Feldmann and MO Woodburne), pp. 541–55. Boulder, Colorado: Geological Society of America, Memoir no. 169. Escutia, C., Brinkhuis, H., Klaus, A. and the Expedition 318 Scientists. 2011. Wilkes Land Glacial History: Cenozoic East Antarctic Ice Sheet evolution from Wilkes Land margin sediments. Proceedings of the Integrated Ocean Drilling Program, Volume 318. Integrated Ocean Drilling Program Management International Inc., Tokyo, https://doi.org/10.2204/iodp.proc.318.2011. Escutia, C., Brinkhuis, H., and the Expedition 318 Science Party. 2014. From Greenhouse to Icehouse at the Wilkes Land Antarctic margin: IODP 318 synthesis of results. Pp. 295–328 in Earth and Life Processes Discovered from Subseafloor Environment. R. Stein, D. Blackman, F. Inagaki, and H.C. Larsen, eds, Developments in Marine Geology, vol. 7, doi.org/10.1016/ B978-0-444-62617-2.00012-8. Espitalié, J., Laporte, J.L., Madec, M., Marquis, F., Leplat, P., Paulet, J., Boutefeu, A., 1977. Méthode rapide de Journal Pre-proof Journal Pre-proof 20 characterisation des roches mères, de leur potential ptrolier et de leur degr d’volution. Revue de l’Institut Francais du Pétrole 32, 23–42. Exon, N. J., Kennett, J. P., Malone, M., 2001. ODP Leg 189 initial results. Proceedings of the ocean drilling program, initial reports of the ODP, College Station, TX, USA 189. Falkowski, P.G., Algeo, T., Codispoti, L., Deutsch, C., Emerson, S., Hales, B., Huey, R. B., Jenkins, W.J., Kump, L.R., Levin, L.A., Lyons, T.W., Nelson, N.B., Schofield, O.S., Summons, R., Talley, L.D., Thomas, E., Whitney, F., Pilcher, C.B., 2011. Ocean deoxygenation: past, present, and future. Eos, 92, 409–10. Farrington, J.W., Tripp, B.W., 1977. Hydrocarbons in western North Atlantic surface sediments. Geochimica et Cosmochimica Acta, 41, 1627–1641. Ficken, K.J., Li, B., Swain, D.L., Eglinton, G., 2000. An n-alkane proxy for the sedimentary input of submerged/floating freshwater aquatic macrophytes. Organic Geochemistry 31, 745–749. Flowerdew, M.J., Riley, T.R., Haselwimmer, C.E., 2011. Geological Map of the South Orkney Islands (1:1 50 000 scale). BAS GEOMAP 2 Series, Sheet 3, British Antarctic Survey, Cambridge. Francis, J. E., Marenssi, S., Levy, R., Hambrey, M., Thorn, V. C., Mohr, B., Brinhkuis, H., Warnaar, J., Zachos, J. C., Bohaty, S. M., DeConto, R. M., 2009. From Greenhouse to Icehouse - The Eocene/Oligocene in Antarctica, in: Antarctic CLimate Evolution, edited by: Florindo, F., and Siegert, M., Elsevier, Amsterdam, 309-368. Francis, J.E., Ashworth, A., Cantrill, D.J., Crame, J.A., Stephens, R., Tosolini, A.-M., Thorn, V., 2008. 100 million years of Antarctic climate evolution: evidence from fossil plants. In: Cooper, A.K., Barrett, P.J., Stagg, H., Storey, B., Stumb, E., Wise, W., the 10th ISAES editorial team (Eds.), Antarctica: A Keystone in a Changing World. Proceedings of the 10th International Symposium on Antarctic Earth Sciences, Washington, D.C., pp. 19– 27. Freeman, K.H., Wakeham, S.G., Hayes, J.M., 1994. Predictive isotopic biogeochemistry: hydrocarbons from anoxic marine basins. Organic Geochemistry, 21, 629–644. Gersonde, R., Burckle, L.H., 1990. Neogene Diatom biostratigraphy of ODP Leg 113, Weddell Sea Antarctic Ocean. In: Barker, P.F., Kennett J.P., et al., Proceeding of the Ocean Drilling Program, Scientific Results, Leg 113, Volume 113: 761–789. College Station, Texas: Ocean Drilling Program. Giresse, P. Wiewiora, A., 2001. Stratigraphic condensed deposition and diagenetic evolution of green clay minerals in deep water sediments on the Ivory Coast-Ghana Ridge. Marine Geology, 179, 51–70. Grimalt, J., Albaigés, J., Al-Saad, H. T., Douabul, A. A. Z., 1985. n-Alkane distributions in surface sediments from the Arabian Gulf. Naturwissenschaften, 72(1), 35–37. Hammer, Ø., Harper, D.A.T., Ryan, P.D., 2001. PAST: Paleontological statistics software package for education and data analysis. Palaeontolologia Electronica, 4(1), 9. Harris, N.B., 2005. Deposition of Organic-Carbon-Rich Sediments: Models Mechanisms, and Consequences. SEPM Special Publication 82. Hedges, J.I., Prahl, F.G., 1993. Early diagenesis: consequences for applications of molecular biomarkers. In: Engel, M.H., Macko, S.A. (Eds.), Organic Geochemistry – Principles and Applications. Plenum Press, pp. 237–253. Helly, J.J., Levin, L.A., 2004. Global distribution of naturally occurring marine hypoxia on continental margins. DeepSea Research I 51, 1159–1168. Hendy, I.L., 2010. Diagenetic behavior of barite in a coastal upwelling setting. Paleoceanography 25(4), PA4103. doi:10.1029/2009PA001890. Hosking, G.P., Hutcheson, J.A., 1988. Mountain beech (Nothofagus solandri var. cliffortoides) decline in Kaweka Range, North Island, New Zealand. New Zealand Journal of Botany 26, 393–400. Houben, A. J. P., 2012. Triggers and consequences of glacial expansion across the Eocene-Oligocene Transition. Utrecht, the Netherlands: LPP Contribution Series No. 39 (Utrecht University). Houben, A.J., Bijl, P.K., Pross, J., Bohaty, S.M., Passchier, S., Stickley, C.E., Rhl, U., Sugisaki, S., Tauxe, L., van de Flierdt, T., Olney, M., Sangiorgi, F., Sluijs, A., Escutia, C., Brinkhuis, H., and the Expedition 318 Scientists, 2013. Reorganization of Southern Ocean plankton ecosystem at the onset of Antarctic glaciation. Science, 340(6130), 341–344. Houben, A.J.P ., Bijl, P .K., Sluijs, A., Schouten, S., Brinkhuis, H., 2019. Late Eocene Southern Ocean cooling and Journal Pre-proof Journal Pre-proof 21 invigoration of circulation preconditioned Antarctica for full-scale glaciation. Geochemistry, Geophysics, Geosystems, 20, 2214–2234. Huon, S., Grousset, F. E., Burdloff, D., Bardoux, G., Mariotti, A., 2002. Sources of fine-sized organic matter in North Atlantic Heinrich Layers: δ13C and δ15N tracers. Geochimica et Cosmochimica Acta, 66, 223–239. Jeng, W.L., 2006. Higher plant n-alkane average chain length as an indicator of petrogenic hydrocarbon contamination in marine sediments. Marine Chemistry, 102, 242–251. Jensen, S., Renberg, L., Reutergardh, L., 1977. Residue analysis of sediment and sewage sludge for organochlorines in the presence of elemental sulphur. Analytical Chemistry, 49, 316–318. Jolliffe, I.T., 2002. Principal Component Analysis, 2nd Edition, Springer, New York. Kennett, J.P., 1977. Cenozoic evolution of Antarctic glaciation, the Circum Antarctic Ocean, and their impact on global paleoceanography. Journal of Geophysical Research, 82, 3843–3860. Kennicutt, M.C., Barker, C., Brooks, J.M., DeFreitas, D.A., Zhu, G.H., 1987. Selected organic matter source indicators in the Orinoco, Nile and Changjiang deltas. Organic Geochemistry, 11, 41–51. King, E.C., Barker P.F., 1988. The margins of the South Orkney microcontinent. Journal of the Geological Society, London, 145, 317-331. Knaust, D., 2012. Trace-fossil systematics. In: Knaust, D., Bromley, R.G. (Eds.), Trace Fossils as Indicators of Sedimentary Environments. Developments in Sedimentology 64. Elsevier, Amsterdam, pp. 79–101. Knaust, D., 2017. Atlas of Trace Fossils in Well Core: Appearance, Taxonomy and Interpretation. Springer, Dordrecht, 209 pp. Lagabrielle, Y., Goddéris, Y., Donnadieu, Y., Malavieille, J., Suarez, M., 2009. The tectonic history of Drake Passage and its possible impacts on global climate. Earth and Planetary Science Letters, 279, 197–211. Lamb, A.L., Wilson, G.P., Leng, M.J., 2006. A review of coastal palaeoclimate and relative sea-level reconstructions using δ13C and C/N ratios in organic material. Earth-Science Review, 75, 29–57. Larcher, W., Winter, A., 1981. Frost suceptibility of palms: experimental data and their interpretation. Principes, 25, 143–155, 1981. Lawver, L., Gahagan, L.M., 2003. Evolution of Cenozoic seaways in the circum-Antarctic region. Palaeogeography, Palaeoclimatology, Palaeoecology, 198, 11–37. Lawver, L.A., Della Vedova, B., Von Herzen, R.P., 1991. Heat flow in Jane Basin, Northern Weddell Sea. Journal of Geophysical Research, 96/B2, 2019–2038. Lawver, L.A., Gahagan, L.M., 1998. Opening of Drake Passage and its impact on Cenozoic ocean circulation, in Tectonic Boundary Conditions for Climate Reconstructions, edited by T. J. Crowley, and K. C. Burke, pp. 212–223, Oxford Univ. Press, New York. Lear, C.H., Bailey, T.R., Pearson, P.N., Coxall, H.K., Rosenthal, Y., 2008. Cooling and ice growth across the Eocene-Oligocene transition. Geology, 36, 251–254. Limburg, K.E., Breitburg, D., Swaney, D.P., Jacinto, G., 2020. Ocean Deoxygenation: A Primer. One Earth 2, 24– 29. Liu, K.-K., Kaplan, I. R., 1989. Eastern tropical Pacific as a source of 15N-enriched nitrate in seawater off southern California. Limnology and Oceanography, 34, 820–830. Liu, Z., Pagani, M., Zinniker, D., DeConto, R., Huber, M., Brinkhuis, H., Shah, S.R., Leckie, R.M., Pearson, A., 2009. Global cooling during the Eocene‐Oligocene climate transition. Science, 323 (5918), 1187–1190. Livermore, R. A., Hillenbrand, C. D., Meredith, M., Eagles, G., 2007. Drake Passage and Cenozoic climate: an open and shut case? Geochemistry, Geophysics, Geosystems 8, Q01005. DOI :10.1029/2005GC001224. Livermore, R.A., Eagles, G., Morris, P., Maldonado, A., 2004. Shackleton Fracture Zone: no barrier to early circumpolar ocean circulation. Geology 32, 797–800. López-Quirós, A., Escutia, C., Sánchez-Navas, A., Nieto, F ., García-Casco, A., Martín-Algarra, A., Evangelinos, D., Salabarnada, A., 2019. Glaucony authigenesis, maturity and alteration in the Weddell Sea: An indicator of paleoenvironmental conditions before the onset of Antarctic glaciation. Scientific Reports 9:13580. López-Quirós, A., Sánchez-Navas, A., Nieto, F., Escutia, C., 2020. New insights into the nature of glauconite. American Mineralogist 105, 674-686. Journal Pre-proof Journal Pre-proof 22 Lucchi, R. G., Rebesco, M., 2007. Glacial contourites on the Antarctic Peninsula margin: insight for palaeoenvironmental and palaeoclimatic conditions. Geological Society Special Publications, 276, 111–127. Maestro, A., López-Martínez, J., Bohoyo, F., 2013. Mesozoic to recent evolution of intraplate stress fields under multiple remote stresses: The case of Signy Island (South Orkney Microcontinent, Antarctica). Geological Society, London, Special Publications 381, 45-65. Maldonado, A., Balanyá, J.C., Barnolas, A., Galindo-Zaldivar, J., Hernández, J., Jabaloy, A., Livermore, R., Martínez-Martínez, J.M., Rodríguez-Fernández, J., De Galdeano, C.S., Somoza, L., Suriñach, E., Viseras, C., 2000. Tectonics of an extinct ridge-transform intersection, Drake Passage (Antarctica). Marine Geophysical Research, 21 (1–2), 43–67. Maldonado, A., Zitellini, N., Leitchenkov, G., Balanya, J.C., Coren, F., Galindo-Zaldívar, J., Lodolo, E., Jabaloy, A., Zanolla, C., Rodrigues-Fernandez, J., Vinnikovsakya, O., 1998. Small ocean basin development along the Scotia-Antarctica plate boundary and in the northern Weddell Sea. Tectonophysics 296, 371-402. Maldonado, M., Bohoyo, F., Galindo-Zaldvar, J., Hernndez-Molina, F.J., Lobo, F.J., Lodolo, E., Martos, Y.M., Prez, L.F., Schreider, A.A., Somoza, L., 2014. A model of oceanic development by ridge jumping: opening of the Scotia Sea. Global and Planetary Change, 123, 152–173. Marenssi, S.A., Net, L.I., Santillana, S.N., 2002. Provenance, environmental and paleogeographic controls on sandstone composition in an incised valley system: the Eocene La Meseta Formation, Seymour Island, Antarctica. Sedimentary Geology 150, 301–21. Marenssi, S.A., Santillana, S.N., Rinaldi, C., 1998. Stratigraphy of La Meseta Formation (Eocene), Marambio Island, Antarctica. In Paleógeno de América del Sur y de la Península Antártica (ed. S Casadío), pp. 137–46. Maipú: Revista de la Asociación Paleontológica Argentina, Publicación Especial no. 5. Martin, J.H., 1990. Glacial–interglacial CO2 change: the iron hypothesis. Paleoceanography 5 (1), 1–13. Martin, J.H., 1991. Iron, Liebig’s Law, and the greenhouse. Oceanography 4 (2), 52–55. Meyers, P. A., 1994. Preservation of elemental and isotopic source identification of sedimentary organic matter. Chemical Geology 144, 289-302. Meyers, P. A., 1997. Organic geochemical proxies of paleoceanographic, paleolimnologic, and paleoclimatic processes. Organic Geochemistry, 27: 213–250. Miguez-Salas, O., Rodríguez-Tovar, F.J., 2019. Ichnofacies distribution in the Eocene-Early Miocene Petra Tou Romiou outcrop, Cyprus: sea level dynamics and palaeoenvironmental implications in a contourite environment. International Journal of Earth Sciences, 108, 2531–2544. Miller, K.G., Kominz, M.A., Browning, J.V., Wright, J.D., Mountain, G.S., Katz, M.E., Sugarman, P.J., Cramer, B.S., Christie-Blick, N., Pekar, S.F., 2005. The Phanerozoic Record of Global Sea Level Change, vol. 310. Science, New York, N.Y., pp. 1293–1298. Minoura, K., Hoshino, K., Nakamura, T., Wada, E., 1997. Late Pleistocene-Holocene paleoproductivity circulation in the Japan Sea: Sea-level control on d13C and d15N records of sediment organic material. Palaeogeography, Palaeoclimatology, Palaeoecology, 135, 41–50. Mohr, B.A.R., 1990. Eocene and Oligocene sporomorphs and dinoflagellate cysts from Leg 113 drill sites, Weddell Sea, Antarctica. In P. F. Barker, J. R. Kennett, et al. (Eds.), Proceedings of the Ocean Drilling Program, Scientific Results 113 (pp. 595–612). Mohr, B.A.R., 2001. The development of Antarctic fern floras during the Tertiary, and palaeoclimatic and palaeobiogeographic implications. Palaeontographica B, 259, 167–208. Moossen, H., Bendle, J., Seki, O., Quillmann, U., Kawamura, K., 2015. North Atlantic Holocene climate evolution recorded by high-resolution terrestrial and marine biomarker records. Quaternary Science Reviews 129, 111-127. Mount, J., 1985. Mixed siliciclastic and carbonate sediments: a proposed first‐order textural and compositional classification. Sedimentology 32, 435– 442. Muller, A., Voss, M., 1999. The paleoenvironments of coastal lagoons in the southern Baltic Sea, II. D13C and d15N ratios of organic matter – sources and sediments. Palaeogeography, Palaeoclimatology, Palaeoecology 145:17-32. Murphy, A.E., Sageman, B.B., Hollander, D.J., Lyons, T.W., Brett, C.E., 2000. Black shale deposition in the Devonian Appalachian Basin: siliciclastic starvation, episodic water-column mixing, and efficient recycling of Journal Pre-proof Journal Pre-proof 23 biolimiting nutrients. Paleoceanography, 15, 280-291. Nichols, J.E., Booth, R.K., Jackson, S.T., 2006. Paleohydrologic reconstruction based on n-alkane distributions in ombrotrophic peat. Organic Geochemistry 37, 1505–1513. Norris, R.D., Turner, S.K., Hull, P.M., Ridgwell, A., 2013. Marine ecosystem responses to Cenozoic global change. Science 341, 492–498. Nott, C.J., Xie, S., Avsejs, L.A., Maddy, D., Chambers, F.M., Evershed, R.P., 2000. n-Alkane distributions in ombrotrophic mires as indicators of vegetation change related to climatic variations. Organic Geochemistry 31, 231–235. Orsi, A.H., Nowlin, W.D., Whitworth, T., 1993. On the circulation and stratification of the Weddell Gyre. Deep Sea Research Part I: Oceanographic Research Papers, 40(1), 169–203. Passchier, S., Bohaty, S.M., Jimenez-Espejo, F., Pross, J., Roehl, U., van de Flierdt, T., Escutia, C., Brinkhuis, H., 2013. Early Eocene to middle Miocene cooling and aridification of East Antarctica. Geochemistry, Geophysics, Geosystems, 14, 1399–1410. Passchier, S., Ciarletta, D. J., Miriagos, T. E., Bijl, P. K., Bohaty, S. M., 2017. An Antarctic stratigraphic record of stepwise ice growth through the Eocene-Oligocene transition. Geological Society of America Bulletin 129(3–4), 318–330. Passchier, S., Krissek, L.A., 2008. Oligocene-Miocene Antarctic continental weathering record and paleoclimatic implications, Cape Roberts drilling project, Ross Sea, Antarctica. Palaeogeography, Palaeoclimatology, Palaeoecology,,260, 30– 40. Paytan, A., Mearon, S., Cobb, K., Kastner, M., 2002. Origin of marine barite deposits: Sr and S isotope characterization. Geology 30(8):747–750. Pedersen, T.F., Calvert, S.E., 1990. Anoxia vs productivity; what controls the formation of organic-carbon-rich sediments and sedimentary rocks? AAPG Bull 74(4):454–466. Peters, K.E., Sweeney, R.E., Kaplan, I.R., 1978. Correlation of carbon and nitrogen stable isotope ratios in sedimentary organic matter. Limnology and Oceanography, 23: 598–604. Peterson, B.J., Howarth, R.W., 1987. Sulfur, carbon, and nitrogen isotopes used to trace organic matter flow in the salt-marsh estuaries of Sapelo Island, Georgia. Limnology and Oceanography 32, 1195-1213. Poole, I., Cantrill, D., Utescher, T., 2005. A multi-proxy approach to determine Antarctic terrestrial palaeoclimate during the Late Cretaceous and Early Tertiary. Palaeogeography, Palaeoclimatology, Palaeoecology 222, 95–121. Poynter, J.G., Farrimond, P., Robinson, N., Eglinton, G., 1989. Aeolian-derived higher plant lipids in the marine sedimentary record: links with palaeoclimate. In: Paleoclimatology and Paleometeorology: Modern and Past Patterns of Global Atmospheric Transport. Springer, Netherlands, pp. 435–462. Prahl, F. G., Bennett, J. T., Carpenter, R., 1980. The early diagenesis of aliphatic hydrocarbons and organic matter in sedimentary particulates from Dabob Bay, Washington. Geochimica et Cosmochimica Acta 44, 1967-1976. Prebble, J.G., Raine, J.I., Barrett, P.J., Hannah, M.J., 2006. Vegetation and climate from two Oligocene glacioeustatic sedimentary cycles (31 and 24 Ma) cored by the Cape Roberts Project, Victoria Land Basin, Antarctica. Palaeogeography, Palaeoclimatology, Palaeoecology 231, 41–57. Pross, J., Brinkhuis, H., 2005. Organic-walled dinoflagellate cysts as paleoenvironmental indicators in the Paleogene; a synopsis of concepts. Paläontologische Zeitschrift 79 (1): 53-59. Pross, J., Houben, A.J.P., Simaeys, S., Williams, G.L., Kotthoff, U., Coccioni, R., Wilpshaar, M., Brinkhuis, H., 2010. Umbria–Marche revisited: A refined magnetostratigraphic calibration of dinoflagellate cyst events for the Oligocene of the Western Tethys. Review of Palaeobotany and Palynology 158, 213–235. Rabalais, N.N., Díaz, R.J., Levin, L.A., Turner, R.E., Gilbert, D., Zhang, J., 2010. Dynamics and distribution of natural and human-caused hypoxia. Biogeosciences, 7, 585–619. Reichgelt, T., West, C. K., Greenwood, D. R., 2018. The relation between global palm distribution and climate. Scientific Reports, 8(1), 4721. Riedinger, N., Kasten, S., Gröger, J., Franke, C., Pfeifer, K., 2006. Active and buried authigenic barite fronts in sediments from the Eastern Cape Basin. Earth and Planetary Science Letters, 241(3):876–887. Rieley, G., Collier, R.J., Jones, D.M., Eglinton, G., 1991. The biogeochemistry of Ellesmere Lake, U.K.—I: source Journal Pre-proof Journal Pre-proof 24 correlation of leaf wax inputs to the sedimentary lipid record. Organic Geochemistry, 17, 901–912. Riis, V., Babel, W., 1999. Removal of sulfur interfering in the analysis of organochlorines by GC-ED. Analyst, 124, 1771–1773. Robert, C., Maillot, H., 1990. Palaeoenvironments in the Weddell Sea area and Antarctic climates, as deduced from clay mineral associations and geochemical data, ODP Leg 113. In Proceedings of the Ocean Drilling Program (eds. Barker, P.F., Kennett, J.P., et al.) 51–66 (Scientific Results 113). Rodríguez-Tovar, F.J., Dorador, J., Grunert, P., Hodell, D., 2015a. Deep-sea trace fossil and benthic foraminiferal assemblages across glacial Terminations 1, 2 and 4 at the ‘Shackleton Site’ (IODP Expedition 339, Site U1385). Global and Planetary Change, 133, 359–370. Rodríguez-Tovar, F.J., Dorador, J., Hodell, D.A.V., 2019. Trace fossils evidence of a complex history of nutrient availability and oxygen conditions during Heinrich Event 1. Global and Planetary Change, 174, 26–34. Rodríguez-Tovar, F.J., Dorador, J., Martín-García, G.M., Sierro, F.J., Flores, J.A., Hodell, D.A., 2015b. Response of macrobenthic and foraminifer communities to changes in deep-sea environmental conditions from Marine Isotope Stage (MIS) 12 to 11 at the ‘Shackleton Site’. Global and Planetary Change, 133, 176–187. Rodríguez-Tovar, F.J., Dorador, J., Mena, A., Francés, G., 2020. Regional and global changes during Heinrich Event 1 affecting macrobenthic habitat: Ichnological evidence of sea-bottom conditions at the Galicia Interior Basin. Global and Planetary Change, 192, 103227. Rodríguez-Tovar, F.J., Miguez-Salas, O., Duarte, L.V., 2017. Toarcian Oceanic Anoxic Event induced unusual behaviour and palaeobiological changes in Thalassinoides tracemakers. Palaeogeography, Palaeoclimatology, Palaeoecology, 485, 46-56. https://doi.org/10.1016/j.palaeo.2017.06.002. Rodríguez-Tovar, F.J., Nagy, J., Reolid, M., 2014. Palaeoenvironment of Eocene prodelta in Spitsbergen recorded by the trace fossil Phycosiphon incertum. Polar Research, 33, 23786. Rodríguez-Tovar, F.J., Puga-Bernabéu, Á., Buatois, L.A., 2008. Large burrow systems in marine Miocene deposits of the Betic Cordillera (Southeast Spain). Palaeogeography, Palaeoclimatology, Palaeoecol.ogy,268, 19-25. Romero, E. J., Zamaloa, M. C , 1985. Polen de Angiospermas de la Formacion Rio Turbio (Eoceno), Provincia de Santa Cruz, Republica Argentina. Ameghiniana, 22:43-51. Romero, E.J., Castro, M.T., 1986. Material fungico y granos de polen de angiospermas de la Formacion Rio Turbio (Eoceno), Provincia de Santa Cruz, Republica Argentina. Ameghiniana 23:101-118. Röhl, H-J., Schmid-Röhl, A., 2004. Lower Toarcian (Upper Liassic) black shales of the Central European epicontinental basin: a sequence stratigraphic case study from the SW German Posidonia Shale. In: Harris NB (ed) The deposition of organic-carbonrich sediments: models, mechanisms, and consequences. SEPM Special Publication, 82, pp 165-189. Sachs, J.P., Repeta, D.J., 1999. Oligotrophy and nitrogen fixation during eastern Mediterranean sapropel events. Science, 286, 2485–2488. Schefuß, E., Ratmeyer, V., Stuut, J.-B.W., Jansen, J.H.F., Sinninghe Damsté, J.S., 2003. Carbon isotope analyses of n-alkanes in dust from the lower atmosphere over the central eastern Atlantic. Geochimica et Cosmochimica Acta 67, 1757–1767. Scher, H.D., Martin, E.E., 2006. Timing and climatic consequences of the opening of the Drake Passage. Science, 312, 428–430. Schmidtko, S., Stramma, L., Visbeck, M., 2017. Decline in global oceanic oxygen content during the past five decades. Nature 542, 335–339. Schoepfer, S.D., Shen, J., Wei, H.Y., Tyson, R.V., Ingall, E., Algeo, T.J., 2015. Total organic carbon, organic phosphorus, and biogenic bariumfluxes as proxies for paleomarine productivity. Earth-Science Review, 149:23–52 Simoneit, B.R., Cardoso, J.N., Robinson, N., 1991. An assessment of terrestrial higher molecular weight lipid compounds in aerosol particulate matter over the South Atlantic from about 30–70 S. Chemosphere 23, 447–465. Sluijs, A., Brinkhuis, H., Stickley, C. E., Warnaar, J., Williams, G. L., Fuller, M., 2003. Dinoflagellate Cysts from the Eocene-Oligocene Transition in the Southern Ocean: Results from ODP Leg 189 eds. Exon, N. F., Kennett, J. P., Malone, M. J. Proceedings of the Ocean Drilling Program, Scientific ResultsVolume189 : 1-41. Sluijs, A., Pross, J., Brinkhuis, H., 2005. From greenhouse to icehouse; organicwalled dinoflagellate cysts as Journal Pre-proof Journal Pre-proof ! ! Figure!3.!! ! ! ! ! Figure!4.!! ! ! ! ! Figure!5.!! ! ! ! ! Figure!6.!! ! ! ! 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