Glaucony authigenesis, maturity and alteration in the Weddell Sea: An indicator of paleoenvironmental conditions before the onset of Antarctic glaciation

This research used samples from the ODP. We thank the staff at the Gulf Coast core repository for assistance in ODP Leg 113 core handling and shipping.We acknowledge the help of Dr. María del Mar Abad, Dr. Isabel Sánchez Almazo, Dr. Miguel Angel Hidalgo, Dr. Miguel Angel Salas, and Isabel Nieto (Scientific Instrumentation Center of the University of Granada, CIC) for their help along different phases of the laboratory work. We also acknowledge the constructive comments of two anonymous reviewers that have helped to improve this paper. We wish to thank Prof. C. Hans Nelson for their constructive comments and improvement of our English, which contributed greatly toward clarification of the text. Thanks are also given to Dr. Francisco J. Lobo and Dr. Fernando Bohoyo for their helpful comments related to the study area and regional tectonics.Three types of glaucony grains were identified in the late Eocene (~35.5–34.1 Ma) sediments from Ocean Drilling Program (ODP) Hole 696B in the northwestern Weddell Sea (Antarctica). The grains are K2O-rich (~7 wt%) and formed by smectite-poor interstratified ~10 Å glauconite-smectite with flaky/ rosette-shaped surface nanostructures. Two glaucony types reflect an evolved (types 1 and 2 glaucony; less mature to mature) stage and long term glauconitization, attesting to the glaucony grains being formed in situ, whereas the third type (type 3 glaucony) shows evidences of alteration and reworking from nearby areas. Conditions for the glaucony authigenesis occurred in an open-shelf environment deeper than 50 m, under sub-oxic conditions near the sediment-water interface. These environmental conditions were triggered by low sedimentation rates and recurrent winnowing action by bottomcurrents, leading to stratigraphic condensation. The condensed glaucony-bearing section provides an overview of continuous sea-level rise conditions pre-dating the onset of Antarctic glaciation during the Eocene-Oligocene transition. Sediment burial, drop of O2 levels, and ongoing reducing (postoxic to sulphidic) conditions at Hole 696B, resulting in iron-sulphide precipitation, were a key limiting factor for the glauconitization by sequestration of Fe2+.Funding for this research is provided by the Spanish Ministry of Science and Innovation (grants CTM2014-60451-C2-1-P and CTM2017-89711-C2-1-P, CGL2016-75679P) cofunded by the European Union through FEDER funds and RNM-208 group (Discontinuidades estratigráficas, Junta de Andalucía, Spain)

The evolution of the Antarctic Circumpolar Current in the SouthwestPacific sector of the Southern Ocean throughout the Cenozoic era

EGU General Assembly in Viena, Austria, 7–12 April 2019The establishment and evolution of the Antarctic Circumpolar Current (ACC) throughout the Cenozoic remainspoorly known, mainly because of the lack of continuous long-term records at strategic locations. Here we presentnew records from marine sediments collected by the Deep Sea Drilling Project (DSDP) Site 278, located in theSouthwestern Pacific sector of the Southern Ocean (Southern Emerald Basin), spanning from the mid-Oligoceneto the Pleistocene (ie. the∼28-2 Ma). Our site is ideally situated to reconstruct changes in the ACC sincethe mid-Oligocene as it remained along the polar frontal zone as shown by paleolatitude reconstructions andmicrofossil assemblage data. To track its evolution, we combined (i) mean grain size of sortable silt (SS) datawith (ii) primary productivity proxies including biogenic silica (BSi), calcium carbonate (CaCO3) and organicmatter, and (iii) neodymium isotope ratios (εNd) generated from fossil fish teeth and debris. Our results documenta significant increase in SS, enhanced marine productivity and a decrease inεNd values towards present-dayCircumpolar deep waterεNd values, suggesting a progressive strengthening of the proto-ACC flow over the last28 Ma. However, we find that the development of a modern-like, homogenous and deep-reaching current wasfully established solely during the Pliocene-Pleistocene transition, concomitantly with the onset of the NorthernHemisphere glaciation

Absence of a strong, deep-reaching Antarctic Circumpolar Current zonal flow across the Tasmanian gateway during the Oligocene to early Miocene

The vigorous eastward flow of the Antarctic Circumpolar Current (ACC) connects all major ocean basins and plays a prominent role in the transport of heat, carbon and nutrients around the globe. However, the establishment of a deep circumpolar flow, similar to the present-day ACC, remains controversial thereby obscuring our understanding of its climatic impact. Deciphering the chemical composition of Circumpolar Deep Water (CDW) within the ACC can provide critical insights about its development and evolution. Here we present new fossil fish teeth/bone debris neodymium isotope (ε) records from Deep Sea Drilling Project (DSDP) Sites 278 and 274 in the southwest Pacific Ocean, with the aim to trace changes in deep water masses across the Tasmanian Gateway between the early Oligocene and early Miocene (~ 33–22 Ma). Site 274 provides the first Nd isotope record proximal to the Ross Sea during the Oligocene (33.5–23.4 Ma). Its Nd isotope composition shows excursions to very radiogenic values, ε = −3.1 and ε − 3.7, at 33.5 Ma and 23.8 Ma, respectively, in response to major steps in Antarctic ice sheet expansion. A shift to lower, more unradiogenic ε values between 29.7 and 29.1 Ma is linked to an increased influence of proto-CDW upwelling at the site. In contrast, the Nd isotope record from Site 278 in the southern Emerald Basin shows little variability (ε = −6.0 to −6.7) throughout the Oligocene and early Miocene (30.9–21.8 Ma). Comparison with published data north of the ACC path, demonstrates the presence of two deep water masses in the South Pacific prior to the inferred onset of the ACC (33–30 Ma), one occupying depths between ~2500 and 3000 m (ε ~ −3 to −5) and a deep/bottom water mass (> 3000 m) with a more unradiogenic Nd isotope composition (ε ~ −6). Site 278 located close to the proto-polar front (proto-PF) indicates that following the inferred onset of the ACC, deep waters bathing the southern Emerald Basin remained more radiogenic in the Southwest Pacific compared to sites along the proto-PF in the South Atlantic and Indian Ocean (ε ~ −8.1). This indicates a provinciality in Nd isotope compositions of deep waters along the proto-PF across the Tasmanian Gateway. Our data are incompatible with the existence of a modern-like homogenous (lateral and vertical) Nd isotope composition of CDW along the main flow path of the ACC in all oceanic basins in the Oligocene to early Miocene. We attribute distinct Nd isotope compositions of deep waters across the Tasmanian Gateway to reflect a less deep reaching and weaker ACC (proto-ACC) than today. Our findings suggest that the modern strong and deep-reaching ACC flow must have been developed at a later point in the Neogene.Funding to this research is provided by the Alexander S. Onassis Public Benefit Foundation Ph.D. research grant: F ZL 016-1/2015-2016; the Spanish Ministry of Economy, Industry and Competitivity (grants CTM2017-89711-C2-1/2-P), co-funded by the European Union through FEDER funds; and an ECORD Research grant awarded to DE. PKB and FH acknowledge funding through the European Research Council starting grant #802835 OceaNice and NWO polar programme grant ALWPP2016.001. This paper is a contribution to the SCAR PAIS Programme

Continental slope and rise geomorphology seaward of the Totten Glacier, East Antarctica (112°E-122°E)

The continental slope and rise seaward of the Totten Glacier and the Sabrina Coast, East Antarctica features continental margin depositional systems with high sediment input and consistent along-slope current activity. Understanding their genesis is a necessary step in interpreting the paleoenvironmental records they contain. Geomorphic mapping using a systematic multibeam survey shows variations in the roles of downslope and along slope sediment transport influenced by broad-scale topography and oceanography. The study area contains two areas with distinct geomorphology. Canyons in the eastern part of the area have concave thalwegs, are linked to the shelf edge and upper slope and show signs of erosion and deposition along their beds suggesting cycles of activity controlled by climate cycles. Ridges between these canyons are asymmetric with crests close to the west bank of adjacent canyons and are mostly formed by westward advection of fine sediment lofted from turbidity currents and deposition of hemipelagic sediment. They can be thought of as giant levee deposits. The ridges in the western part of the area have more gently sloping eastern flanks and rise to shallower depths than those in the east. The major canyon in the western part of the area is unusual in having a convex thalweg; it is likely fed predominantly by mass movement from the flanks of the adjacent ridges with less sediment input from the shelf edge. The western ridges formed by accretion of suspended sediment moving along the margin as a broad plume in response to local oceanography supplemented with detritus originating from the Totten Glacier. This contrasts with interpretations of similar ridges described from other parts of Antarctica which emphasise sediment input from canyons immediately up-current. The overall geomorphology of the Sabrina Coast slope is part of a continuum of mixed contourite-turbidite systems identified on glaciated margins.Australian Government 4333Australian Research Council DP170100557Italian Programma Nazionale di Richerch in Antartide (PNRA)Spanish Government CTM2014-60451-C2-1-P CTM2017-89711-C2-1-

Late Oligocene-Miocene proto-Antarctic Circumpolar Current dynamics off the Wilkes Land margin, East Antarctica

At present, the Southern Ocean plays an important role in the global climate system and in modern Antarctic ice sheet dynamics. Past Southern Ocean configurations are however poorly understood. This information is yet important as it may provide important insights into the climate system and past ice-sheet behavior under warmer than present day climates. Here we study Southern Ocean dynamics during the Oligocene and Miocene when reconstructed atmospheric CO2 concentrations were similar to those expected during this century. We reconstruct snapshots of late Oligocene to earliest Miocene (~24.2–23 Ma) paleoceanographic conditions in the East Antarctic Wilkes Land abyssal plain. For this, we combine marine sedimentological, geochemical (X-ray fluorescence, TEX86,), palynological and isotopic (εNd) records from ocean sediments recovered at Deep Sea Drilling Project (DSDP) Site 269. Overall, we find that sediments, delivered to the site by gravity flows and hemipelagic settling during glacial-interglacial cycles, were persistently reworked by a proto-Circumpolar Deep Water (CDW) with varying strengths that result from climatically controlled frontal system migrations. Just prior to 24 Ma, terrigenous input of predominantly fine-grained sediments deposited under weak proto-CDW intensities and poorly ventilated bottom conditions dominates. In comparison, 24 Ma marks the start of episodic events of enhanced proto-CDW current velocities, associated with coarse-grained deposits and better-ventilated bottom conditions. In particular, the dominance of P-cyst and low Calcium (Ca) in the sediments between ~ 24.2 Ma and 23.6 Ma indicate the presence of an active open ocean upwelling associated with high nutrient conditions. This is supported by TEX86-derived sea surface temperature (SST) data pointing to cool ocean conditions. From ~ 23.6 to 23.2 Ma, our records reveal an enrichment of Ca in the sediments related to increased calcareous microfossil preservation, high amounts of G-cysts and increasing TEX86-SSTs. This implies warmer water masses reaching the Antarctic margin as the polar front migrated southward. Together with the radiogenic Nd isotope data indicating modern-like CDW values, our records suggest a prominent poleward expansion of proto-CDW over our study site and reduced AABW formation during the latest Oligocene (i.e. ~23.2 Ma ago). Our findings support the notion of a fundamentally different Southern Ocean, with a weaker proto-ACC than present during the late Oligocene and the earliest Miocene

Late Miocene onset of the modern Antarctic Circumpolar Current

The Antarctic Circumpolar Current plays a pivotal role in global climate through its strong influence on the global overturning circulation, ocean heat and CO uptake. However, when and how the Antarctic Circumpolar Current reached its modern-like characteristics remains disputed. Here we present neodymium isotope and sortable silt records from sediment cores in the Southwest Pacific and South Indian oceans spanning the past 31 million years. Our data indicate that a circumpolar current like that of today did not exist before the late Miocene cooling. These findings suggest that the emergence of a homogeneous and deep-reaching strong Antarctic Circumpolar Current was not linked solely to the opening and deepening of Southern Ocean Gateways triggering continental-scale Antarctic Ice Sheet expansion during the Eocene–Oligocene Transition (∼34 Ma). Instead, we find that besides tectonic pre-conditioning, the expansion of the Antarctic Ice Sheet and sea ice since the middle Miocene Climate Transition (∼14 Ma) played a crucial role. This led to stronger density contrast and intensified Southern Westerly Winds across the Southern Ocean, establishing a vigorous deep-reaching circumpolar flow and an enhanced global overturning circulation, which amplified the late Cenozoic global cooling.This research used samples provided by the International Ocean Discovery Program (IODP). We acknowledge the staff and shipboard party from Leg 28 and Leg 119. We thank the staff at the Gulf Coast core repository (GCR) for curating these cores and for assistance in core handling and shipping. Funding for this research is provided by the Spanish Ministry of Economy, Industry and Competitivity (grant CTM2017-89711-C2-1/2-P; PID2021-126495NB-C31), co-funded by the European Union through FEDER funds. D.E. was funded by the Alexander S. Onassis Public Benefit Foundation PhD research grant (F ZL 016-1/2015-2016), by MOPGA postdoctoral visiting fellowship programme funded by the French Ministry of Europe and Foreign Affairs (grant MOPGA postdoc-3–5669831615), by the Juan de la Cierva-formation postdoctoral research grant (FJC2020-043650-I) funded by MCIN/AEI/ 10.13039/501100011033 and the ‘European Union NextGenerationEU/PRTR’ and by the UK Research and Innovation Engineering and Physical Sciences Research Council (grant number EP/X02623X/1). D.E. received additional funding from an ECORD research grant and IODP-France. I.S. and A.K. were supported by the Australian Research Council Special Research Initiative for Antarctic Gateway Partnership (project ID SR140300001) and the Australian Research Council’s Discovery Project 180102280. Model runs were undertaken with the assistance of resources from the National Computational Infrastructure (NCI), which is supported by the Australian Government. We thank the Paleomagnetic Laboratory CCiTUB-Geo3Bcn CSIC for the support on palaeomagnetic analysis. The GRC Geociències Marines thanks the Generalitat de Catalunya for the Grups de Recerca Consolidats grant 2021SGR01195 and for the ICREA-Academia award to I.C. This paper is a contribution to the SCAR INSTANT Programme.Peer reviewe

The Equality, Diversity and Inclusion

Geoscience (EDIG) online conference. 14th-16tj december 202

Cenozoic ice sheets and ocean variability controls on sedimentation in glaciated margins

The Antarctic Circumpolar Current (ACC) connects all major ocean basins, links the deep and shallow layers of the oceans and has a strong influence on global ocean circulation, biogeochemical cycles, the stability of the Antarctic ice sheet and thereby Earth´s climate system. However, the timing of the onset of the ACC and the establishment of a vigorous, deep circumpolar flow, similar to presentday remain controversial. Moreover, the links between the ACC and the Antarctic ice sheet in past warmer than today climates are poorly known. This knowledge is essential for improving our understanding on ACC-Antarctic ice sheet interactions in the ongoing climate warming that can inform coupled ocean-ice sheet global climate models used to forecast future changes. In this context, this PhD thesis aims to advance our understanding on the evolution of the ACC since its initiation (proto-ACC) to the time when the modern deep ACC is established over the last 34 million years (Ma). In addition, we aim to relate proto-ACC dynamics offshore the eastern Wilkes Land margin to Antarctic ice sheet behaviour during the warm late Oligocene and the earliest Miocene (24-23 Ma), including the second major Antarctic glaciation (23.03 Ma). To achieve these objectives, we conducted sedimentological, geochemical, and isotopic analyses on sedimentary sequences recovered by the Deep Sea Drilling Project Leg 28 (Sites 269 and 274) and Leg 29 (Site 278) across both sides of the Tasmanian Gateway. In addition, we conducted a study in the glaciated margins of Lake Baikal (Russia). There the tectonic and sea level histories are well known allowing us to test, using bathymetric and seismic reflection data, the climate vs. sea-level changes and tectonic controls on deep-water deposition in glaciated margins. This PhD Thesis shows that between 34-30 Ma, deep waters from the South Atlantic and Indian Ocean did not flow into the Southwest Pacific via the Tasmanian Gateway. Instead, the Southwest Pacific deep water circulation was characterised by the presence of two deep water masses, one occupying depths between ~2500-4000 m (Equatorial-like Deep Water) and another one, a bottom water mass, occupying depths >= 4000m South Pacific Deep Water). These results indicate the absence of a Circumpolar Deep Water (CDW) connection, like the one found today within the ACC, across the Tasmanian Gateway before 30 Ma. The first evidence of proto-CDW in the Southwest Pacific was previously reported at 30 Ma. Our study however shows the absence of a homogenous deep-reaching proto-CDW in the eastern and western side of the Tasmanian Gateway between 30 Ma and 19 Ma, which indicates a proto-ACC shallower and weaker than the present-day ACC. Between 19 and 4 Ma, we find evidence of a long-term intensification of bottom current flow speeds, coinciding with increasing influence of North Atlantic Deep Water (NADW) in the deep Southwest Pacific. We suggest that the modern deep-reaching ACC flow established at 4 Ma as indicated by a prominent shift to (i) intensified ACC frontal system resulting in enhanced biogenic productivity, (ii) stronger bottom current flow speeds, and (iii) establishment of a homogenous CDW along the polar front in the Southern Ocean Moreover, our results show that the proto-ACC frontal system offshore the Wilkes Land margin was weaker compared to that of the present-day during the late Oligocene-earliest Miocene (24-23 Ma), allowing warm subtropical waters to reach close to this Antarctic margin. In addition, proto-CDW was circulating closer to the Wilkes Land margin especially during interglacial times (e.g., 23.23 Ma), likely due to reduced Antarctic Bottom Water (AABW) export and ice sheets where retreated in the continent. The Antarctic Circumpolar Current (ACC) connects all major ocean basins, links the deep and shallow layers of the oceans and has a strong influence on global ocean circulation, biogeochemical cycles, the stability of the Antarctic ice sheet and thereby Earth´s climate system. However, the timing of the onset of the ACC and the establishment of a vigorous, deep circumpolar flow, similar to presentday remain controversial. Moreover, the links between the ACC and the Antarctic ice sheet in past warmer than today climates are poorly known. This knowledge is essential for improving our understanding on ACC-Antarctic ice sheet interactions in the ongoing climate warming that can inform coupled ocean-ice sheet global climate models used to forecast future changes. In this context, this PhD thesis aims to advance our understanding on the evolution of the ACC since its initiation (proto-ACC) to the time when the modern deep ACC is established over the last 34 million years (Ma). In addition, we aim to relate proto-ACC dynamics offshore the eastern Wilkes Land margin to Antarctic ice sheet behaviour during the warm late Oligocene and the earliest Miocene (24-23 Ma), including the second major Antarctic glaciation (23.03 Ma). To achieve these objectives, we conducted sedimentological, geochemical, and isotopic analyses on sedimentary sequences recovered by the Deep Sea Drilling Project Leg 28 (Sites 269 and 274) and Leg 29 (Site 278) across both sides of the Tasmanian Gateway. In addition, we conducted a study in the glaciated margins of Lake Baikal (Russia). There the tectonic and sea level histories are well known allowing us to test, using bathymetric and seismic reflection data, the climate vs. sea-level changes and tectonic controls on deep-water deposition in glaciated margins. This PhD Thesis shows that between 34-30 Ma, deep waters from the South Atlantic and Indian Ocean did not flow into the Southwest Pacific via the Tasmanian Gateway. Instead, the Southwest Pacific deep water circulation was characterised by the presence of two deep water masses, one occupying depths between ~2500-4000 m (Equatorial-like Deep Water) and another one, a bottom water mass, occupying depths >= 4000m South Pacific Deep Water). These results indicate the absence of a Circumpolar Deep Water (CDW) connection, like the one found today within the ACC, across the Tasmanian Gateway before 30 Ma. The first evidence of proto-CDW in the Southwest Pacific was previously reported at 30 Ma. Our study however shows the absence of a homogenous deep-reaching proto-CDW in the eastern and western side of the Tasmanian Gateway between 30 Ma and 19 Ma, which indicates a proto-ACC shallower and weaker than the present-day ACC. Between 19 and 4 Ma, we find evidence of a long-term intensification of bottom current flow speeds, coinciding with increasing influence of North Atlantic Deep Water (NADW) in the deep Southwest Pacific. We suggest that the modern deep-reaching ACC flow established at 4 Ma as indicated by a prominent shift to (i) intensified ACC frontal system resulting in enhanced biogenic productivity, (ii) stronger bottom current flow speeds, and (iii) establishment of a homogenous CDW along the polar front in the Southern Ocean Moreover, our results show that the proto-ACC frontal system offshore the Wilkes Land margin was weaker compared to that of the present-day during the late Oligocene-earliest Miocene (24-23 Ma), allowing warm subtropical waters to reach close to this Antarctic margin. In addition, proto-CDW was circulating closer to the Wilkes Land margin especially during interglacial times (e.g., 23.23 Ma), likely due to reduced Antarctic Bottom Water (AABW) export and ice sheets where retreated in the continent. Lastly, our results from Lake Baikal highlight that climate is the main control on the development of turbidite system in this glaciated margin. We provide evidence that show that despite the nearly constant lake levels, the late Pleistocene to Holocene changes in lake Baikal turbidite system evolution are the same as marine turbidite systems with ~120 m of sea-level lowering. These results are relevant, when interpreting deep-water deposits in the glaciated margins of Antarctica, which are governed by a complex interplay between ice sheet dynamics, sea level changes and tectonic control.La Corriente Circumpolar Antártica (CCA) conecta todas cuencas oceánicas, las aguas superficiales y profundas de los océanos e influye en la circulación oceánica global, los ciclos biogeoquímicos, la estabilidad del casquete de hielo Antártico, y por ende en el sistema climático terrestre. El origen y la evolución de la CCA hasta la alcanzar la configuración actual de una corriente circumpolar, fuerte y profunda, sigue creando controversia. También, es poco el conocimiento sobre la relación entre la evolución de la CCA y la del casquete de hielos Antártico en épocas cálidas del pasado. Sin embargo, en el contexto actual de calentamiento global, este conocimiento es importante para poder informar los modelos acoplados del sistema climático océano-criósfera, utilizados en las predicciones de cambios futuros. En este contexto, esta tesis doctoral tiene como objetivos el avanzar nuestro conocimiento sobre la evolución de la CCA desde su inicio (proto-CCA) hasta el establecimiento de la CCA actual, abarcando los últimos 34 millones de años (Ma). Además, pretende relacionar la dinámica de la proto-CCA con la del casquete de hielos en el margen continental de la Tierra de Wilkes durante el Oligoceno cálido y el Mioceno inferior (24-23 Ma), periodo que incluye la segunda mayor glaciación continental en la Antártida (23.03 Ma). Para lograr estos objetivos, hemos realizado análisis sedimentológicos, geoquímicos e isotópicos en sedimentos recuperados por el Deep Sea Drilling Project (DSDP) Leg 28 (Sites 269 y 274) y Leg 29 (Site 278) a cada lado del Paso de Tasmania. Además, se ha realizado un estudio en el Lago Baikal (Rusia). La historia tectónica y de los cambios del nivel del Lago Baikal son bien conocidas permitiéndonos testar, usando datos batimétricos y de sísmica de reflexión, el control climático vs. nivel del mar y tectónica en la formación de depósitos profundos en márgenes continentales influenciados por la actividad glaciar. Los resultados de esta tesis revelan que entre 34-30 Ma, no había flujo de aguas profundas del Atlántico Sur y del Océano Indico a través del Paso de Tasmania. La circulación profunda en el Pacifico Sur estaba caracterizada por la presencia de dos masas de agua, una ocupando profundidades entre ~2500-4000 m (tipo Agua Profunda del Pacifico Ecuatorial), y otra ocupando profundidades >= 4000m (Aguas Profundas del Pacífico Sur). Estos resultados indican la ausencia de la Corriente Profunda circumpolar (CDW), componente principal de la CCA, atravesando el Paso de Tasmania antes de 30 Ma. La primera evidencia de una proto-CDW en el Pacifico suroccidental había sido informada a los 30 Ma. Sin embargo, nuestro estudio muestra la ausencia de una proto-CDW homogénea en la parte occidental del Paso de Tasmania entre 30 y 19 Ma, lo que indica la existencia de una CCA más somera y débil que la actual. Entre 19 y 4 Ma, los sedimentos registran un aumento en la velocidad del flujo de corriente la profunda, coincidiendo con un incremento de la influencia de las Aguas Profundas del Atlántico Norte (NADW) en el Pacífico suroccidental. Nuestros datos sugieren que la formación de una CCA similar a la actual tuvo lugar a los 4 Ma indicado por un marcado cambio en: (i) la intensificación del sistema frontal y como resultado en la productividad biogénica, (ii) intensificación en la velocidad de flujo de la corriente, y (iii) el establecimiento de una CDW de composición homogénea. Además, nuestros resultados indican que la existencia de una proto-CDW más débil que la actual durante el Oligoceno superior-Mioceno inferior (24-23 Ma) permitía la llegada de aguas cálidas subtropicales cerca de la Antártida. Nuestros datos muestran que la proto-CDW circulaba más próxima al margen de la Tierra de Wilkes durante periodos interglaciares (e.g., 23.23) probablemente debido a la reducción en la producción de Aguas Profundas Antárcticas (AABW) y cuando los casquetes estaban retirados en el continente. Por último, nuestros resultados en el Lago Baikal muestran el clima como el factor que controla el desarrollo de sistemas turbidíticos en el margen del lago influido por procesos glaciares. Pese a que los niveles del lago permanecen casi constantes durante el Pleistoceno superior y el Holoceno, la evolución de los sistemas turbidíticos es similar a la observada en sistemas turbidíticos marinos con ~120 m de descenso del nivel del mar. Estos resultados son importantes a la hora de interpretar depósitos profundos en los márgenes glaciares de la Antártida, en los que gobierna una compleja interacción entre factores de control que incluyen la dinámica glaciar, los cambios del nivel del mar y la actividad tectónica.Tesis Univ. Granada.Onassis Foundation Scholarship ID: F ZL 016- 1/2015-2016Spanish Ministry of Science and Innovation (grants CTM2014-60451-C2-1-P and CTM2017- 89711-C2-1-P

Late Quaternary climatic control of Lake Baikal (Russia) turbidite systems : implications for turbidite systems worldwide

Lake Baikal (Russia) contains a variety of turbidite systems in different tectonic and depositional settings that provide tests for the role of Quaternary climatic change on turbidite system growth. During Pleistocene glacial climates, all types of systems exhibit increased sediment supply (high sedimentation rates, high net sand percent, thick sand turbidites) and progradation. During Holocene interglacial climate, all systems exhibit reduced sediment supply and retreat. Seismic profiles from the large Selenga Fan and small Tompuda Fan show (1) maximum fan growth during the late Pleistocene glacial melt time, where lobes and large channels reached the distal outer fan, and (2) fan retreat during the transition to the fully developed Holocene interglacial climate. For example, the Selenga Fan surface lobes backstepped ∼55 km from the distal outer fan to the distal inner fan, and the large outer fan surface channel (∼750 m wide, ∼20 m levee relief) evolved to a smaller surface channel (∼450 m wide, ∼13 m levee relief) that extended only to the end of the inner fan. These results show that Quaternary climate controls the growth of the Lake Baikal turbidite systems in a setting where there are no significant water-level changes, which often are cited as the main control on turbidite system growth. The Lake Baikal and other marine turbidite systems suggest that climatic control of sediment supply, unrelated to sea-level lowering and tectonic effects, may have been a much more important control for turbidite systems than previously believed, not only during the Pleistocene, but perhaps also for ancient systems

Early Oligocene to middle Miocene surface ocean conditions offshore Cape Adare (Ross Sea, Antarctica); palynological and temperature records of DSDP Site 274

13th International Conference on Paleoceanography 2-6 September 2019 Sydney, Australi