The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred duri... more The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred during the latest Eocene-earliest Oligocene. Prior to this, during the Early-Middle Eocene, Antarctica experienced warm climates, at least on the margins of the continent where geological evidence is present. Climates appear to have been warm and wet, the seas were warm and plants flourished in a frost-free environment, although there is some suggestion of valley glaciers on King George Island. Climate signals in the geological record show that the climate then cooled but not enough to allow the existence of significant ice until the latest Eocene.
Prostrate trees record average climate over decadal time periods in tree ring cellulose-δ 18 O. •... more Prostrate trees record average climate over decadal time periods in tree ring cellulose-δ 18 O. • Late Neogene Antarctic wood indicates a~12‰ enrichment in H 2 O-δ 18 O relative to today. • Evidence for marked changes in Antarctic hydrological cycle
Latitudinal Controls on Stratigraphic Models and Sedimentary Concepts, 2019
Climate plays a significant role in determining the style of depositional processes at different ... more Climate plays a significant role in determining the style of depositional processes at different latitudes, which in turn influences the location of hydrocarbon systems. Results of climate modelling may therefore provide important information for predicting the presence or absence of suitable hydrocarbon plays. The critical step is to validate the model results against proxy data where they are available, to determine whether the models provide realistic results. Paleoclimate proxy data are most often derived from more accessible low to mid latitude regions and are biased towards warm climate states. However, General Circulation Models (GCMs) have traditionally been biased to colder temperatures, in particular at high latitudes, struggling to maintain the high latitude regions warm enough to sustain forests that were present during greenhouse periods, such as the mid-Cretaceous (~110-90 Ma), without exaggerated warming of the equatorial regions. To the HadCM3L GCM, coupled with updated paleogeographic maps, can produce a good match to the climate proxy data in these difficult-to-model high latitude areas.
Extended Data Fig. 2 | Pollen abundance diagram. Percentages of the most abundant pollen and spor... more Extended Data Fig. 2 | Pollen abundance diagram. Percentages of the most abundant pollen and spores and their total counts in cores 9R and 10R at site PS104_20-2 are shown. Extended Data Fig. 4 | HG palaeothermometry. Presence of HGs at 27.03-27.04 mbsf at site PS104_20-2 (core 9R) and river or lake surface water temperature (SWT) estimates from the HG-based molecular palaeothermometer (HTI 30).
The Cretaceous-Paleogene (K-Pg) mass extinction event 66 million years ago led to large changes t... more The Cretaceous-Paleogene (K-Pg) mass extinction event 66 million years ago led to large changes to the global carbon cycle, primarily via a decrease in primary or export productivity of the oceans. However, the effects of this event and longer-term environmental changes during the Late Cretaceous on the global sulfur cycle are not well understood. We report new carbonate associated sulfate (CAS) sulfur isotope data derived from marine macrofossil shell material from a highly expanded high latitude Maastrichtian to Danian (69-65.5 Ma) succession located on Seymour Island, Antarctica. These data represent the highest resolution seawater sulfate record ever generated for this time interval, and are broadly in agreement with previous low-resolution estimates for the latest Cretaceous and Paleocene. A vigorous assessment of CAS preservation using sulfate oxygen, carbonate carbon and oxygen isotopes and trace element data, suggests factors affecting preservation of primary seawater CAS isotopes in ancient biogenic samples are complex, and not necessarily linked to the preservation of original carbonate mineralogy or chemistry. Primary data indicate a generally stable sulfur cycle in the early-mid Maastrichtian (69 Ma), with some fluctuations that could be related to increased pyrite burial during the 'mid-Maastrichtian Event'. This is followed by an enigmatic +4‰ increase in d 34 S CAS during the late Maastrichtian (68-66 Ma), culminating in a peak in values in the immediate aftermath of the K-Pg extinction which may be related to temporary development of oceanic anoxia in the aftermath of the Chicxulub bolide impact. There is no evidence of the direct influence of Deccan volcanism on the seawater sulfate isotopic record during the late Maastrichtian, nor of a direct influence by the Chicxulub impact itself. During the early Paleocene (magnetochron C29R) a prominent negative excursion in seawater d 34 S of 3-4‰ suggests that a global decline in organic carbon burial related to collapse in export productivity, also impacted the sulfur cycle via a significant drop in pyrite burial. Box modelling suggests that to achieve an excursion of this magnitude, pyrite burial must be reduced by >15%, with a possible role for a short term increase in global weathering rates. Recovery of the sulfur cycle to pre-extinction values occurs at the same time ($320 kyrs) as initial carbon cycle recovery globally. These recoveries are also contemporaneous with an initial increase in local alpha diversity of marine macrofossil faunas, suggesting biosphere-geosphere links during recovery from the mass extinction. Modelling further indicates that concentrations of sulfate in the oceans must have been 2 mM, lower than previous estimates for the Late Cretaceous and Paleocene and an order of magnitude lower than today.
The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high p... more The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process ‘big data’ collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets ...
The Paleocene (66-56 Ma) was a critical time interval for understanding recovery from mass extinc... more The Paleocene (66-56 Ma) was a critical time interval for understanding recovery from mass extinction in high palaeolatitudes when global climate was warmer than today. A unique sedimentary succession from Seymour Island (Antarctic Peninsula) provides key reference material from this important phase of the early Cenozoic. Dinoflagellate cyst data from a 376 m thick stratigraphical section, including the Cretaceous-Paleogene boundary, is correlated with biozones from New Zealand, the East Tasman Plateau and southeastern Australia. A detailed age model is suggested for the López de Bertodano (LDBF) and Sobral (SF) formations based on dinoflagellate cyst biostratigraphy and U-Pb dating of zircons, supported by correlated magnetostratigraphy and strontium isotope values from macrofossils. The top of the LDBF is confirmed as latest Maastrichtian to earliest Danian (~66.2-65.65 Ma) in age. The overlying SF is mostly Danian in age, with an inferred hiatus near the top overlain by sediments dated as ?late Thanetian. Rare Apectodinium homomorphum first appear in the uppermost SF; the earliest in situ record from Antarctica. The distribution of marine and terrestrial fossils from uppermost Cretaceous to Eocene sediments in Patagonia, Antarctica, New Zealand and Australia required both sea and land connections between these fragments of Gondwana. Fossil evidence and reconstructions of Antarctic palaeogeography and palaeotopography reveal evidence for persistent embayments in the proto-Weddell and Ross Sea regions at this time. We conclude that a coastal dispersal route along the palaeo-Pacific margin of Gondwana could explain the fossil distribution without requiring a transAntarctic strait or closely spaced archipelago. A region in the West to East Antarctic boundary zone, elevated until the early Paleogene, perhaps acted as a site for high elevation ice caps. This supports fossil, geochemical and sedimentological evidence for cold climate intervals and significant sea level falls during the Maastrichtian and Paleocene.
GSA Annual Meeting in Phoenix, Arizona, USA - 2019, 2019
Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 millio... more Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 million years ago shaped the composition and structure of modern ecosystems. The timing and nature of recovery has been linked to many factors including palaeolatitude, geographical range, the ecology of survivors, incumbency and palaeoenvironmental setting. Using a temporally constrained fossil dataset from one of the most expanded K-Pg successions in the world, integrated with palaeoenvironmental information, we provide the most detailed examination of the patterns and timing of recovery from the K-Pg mass extinction event in the high southern latitudes of Antarctica. The timing of biotic recovery was influenced by global stabilization of the wider Earth system following severe environmental perturbations, apparently regardless of latitude or local environment. Extinction intensity and ecological change were decoupled, with community scale ecological change less distinct compared to other locations, even if the taxonomic severity of the extinction was the same as at lower latitudes. This is consistent with a degree of geographical heterogeneity in the recovery from the K-Pg mass extinction. Recovery in Antarctica was influenced by local factors (such as water depth changes, local volcanism, and possibly incumbency and pre-adaptation to seasonality of the local benthic molluscan population), and also showed global signals, for example the radiation of the Neogastropoda within the first million years of the Danian, and a shift in dominance between bivalves and gastropods.
Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 millio... more Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 million years ago shaped the composition and structure of modern ecosystems. The timing and nature of recovery has been linked to many factors including palaeolatitude, geographical range, the ecology of survivors, incumbency and palaeoenvironmental setting. Using a temporally constrained fossil dataset from one of the most expanded K-Pg successions in the world, integrated with palaeoenvironmental information, we provide the most detailed examination of the patterns and timing of recovery from the K-Pg mass extinction event in the high southern latitudes of Antarctica. The timing of biotic recovery was influenced by global stabilization of the wider Earth system following severe environmental perturbations, apparently regardless of latitude or local environment. Extinction intensity and ecological change were decoupled, with community scale ecological change less distinct compared to other locations, even if the taxonomic severity of the extinction was the same as at lower latitudes. This is consistent with a degree of geographical heterogeneity in the recovery from the K-Pg mass extinction. Recovery in Antarctica was influenced by local factors (such as water depth changes, local volcanism, and possibly incumbency and pre-adaptation to seasonality of the local benthic molluscan population), and also showed global signals, for example the radiation of the Neogastropoda within the first million years of the Danian, and a shift in dominance between bivalves and gastropods.
Debate continues about the nature of the Cretaceous-Paleogene (K-Pg) mass extinction event. An ab... more Debate continues about the nature of the Cretaceous-Paleogene (K-Pg) mass extinction event. An abrupt crisis triggered by a bolide impact contrasts with ideas of a more gradual extinction involving flood volcanism or climatic changes. Evidence from high latitudes has also been used to suggest that the severity of the extinction decreased from low latitudes towards the poles. Here we present a record of the K-Pg extinction based on extensive assemblages of marine macrofossils (primarily new data from benthic molluscs) from a highly expanded Cretaceous-Paleogene succession: the López de Bertodano Formation of Seymour Island, Antarctica. We show that the extinction was rapid and severe in Antarctica, with no significant biotic decline during the latest Cretaceous, contrary to previous studies. These data are consistent with a catastrophic driver for the extinction, such as bolide impact, rather than a significant contribution from Deccan Traps volcanism during the late Maastrichtian.
The past vegetation and climate of West Antarctica and the evolution of its highly sensitive and ... more The past vegetation and climate of West Antarctica and the evolution of its highly sensitive and dynamic ice sheet are poorly constrained by geological data. The few existing far-field data, and even fewer proximal records, indicate a major ice-sheet build-up in West Antarctica from the Oligocene to the Miocene, with partial or even complete ice-sheet collapses during warm Late Cenozoic intervals with near-modern atmospheric CO2-concentrations. Here we present first palynological results from the MeBo70 seabed drill cores collected in early 2017 from the Amundsen Sea shelf. The cores contain unconsolidated to highly consolidated sediments of Cretaceous to Holocene age. Preliminary analyses of pollen, spores and dinoflagellate cysts indicate that during the Cretaceous and early Paleogene the Amundsen Sea Embayment was covered by warm-temperate and temperate forests. The paper will focus on Turonian to Santonian (ca. 93-85 Ma) peat layers in the oldest sections of the cores, which contain micro- and macrofossils documenting the evolution of a highly diverse, conifer-rich swamp forest during the Late Cretaceous.
Marine palynomorphs have been studied from a new section on Seymour Island in the James Ross Basi... more Marine palynomorphs have been studied from a new section on Seymour Island in the James Ross Basin, northern Antarctic Peninsula. At 65°S, both during the Maastrichtian and at the present day, it is an exceptional locality to investigate the nature of climates and sea level in the high southern palaeolatitudes across the Cretaceous-Paleogene (K-Pg) transition. Until now, Antarctic marine palynological studies have relied on dinoflagellate cyst zonation schemes from New Zealand and southeastern Australia. New high resolution data from this important location has allowed us to propose the first formal dinoflagellate cyst zonation scheme for the Antarctic Peninsula placing this Maastrichtian to earliest Paleogene succession from Seymour Island into a firm stratigraphical context. The shallow marine Lopez de Bertodano Formation (c.1100m thick) records the final c.3 myrs of the Cretaceous and crosses the K-Pg boundary. Varied and stratigraphically useful Manumiella spp. form the basis of two new ?late Maastrichtian zones (the Manumiella seymourensis Range Zone and the Manumiella bertodano Interval Zone). In addition, the exceptional expanded nature of this sequence allows the insertion of a new early Danian Hystrichosphaeridium tubiferum Acme Zone between the latest Maastrichtian Manumiella druggii Range Zone and the Danian Trithyrodinium evittii Acme Zone. The oldest beds correlate well with the late Maastrichtian of New Zealand. In a wider context, a review of Maastrichtian to earliest Paleogene marine palynofloras across the south polar region suggests the presence of a new South Polar Province for this time period with consequent implications for Antarctic palaeogeography.
Developments in earth and environmental sciences, 2008
The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred duri... more The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred during the latest Eocene-earliest Oligocene. Prior to this, during the Early-Middle Eocene, Antarctica experienced warm climates, at least on the margins of the continent where geological evidence is present. Climates appear to have been warm and wet, the seas were warm and plants flourished in a frost-free environment, although there is some suggestion of valley glaciers on King George Island. Climate signals in the geological record show that the climate then cooled but not enough to allow the existence of significant ice until the latest Eocene.
Review of Palaeobotany and Palynology, Feb 1, 2012
The thickest uppermost Cretaceous to lowermost Paleogene (Maastrichtian to Danian) sedimentary su... more The thickest uppermost Cretaceous to lowermost Paleogene (Maastrichtian to Danian) sedimentary succession in the world is exposed on southern Seymour Island (65° South) in the James Ross Basin, Antarctic Peninsula. This fossiliferous shallow marine sequence, which spans the Cretaceous-Paleogene boundary, has allowed a high-resolution analysis of well-preserved marine palynomorphs. Previous correlation of Cretaceous-Paleogene marine palynomorph assemblages in the south polar region relied on dinoflagellate cyst biozonations from New Zealand and southern Australia. The age model of the southern Seymour Island succession is refined and and placed within the stratigraphical context of the mid to high southern palaeolatitudes. Quantitative palynological analysis of a new 1102 m continuous stratigraphical section comprising the uppermost Snow Hill Island Formation and the López de Bertodano Formation (Marambio Group) across southern Seymour Island was undertaken. We propose the first formal late Maastrichtian to 2 early Danian dinoflagellate cyst zonation scheme for the Antarctic based on this exceptional succession. Two new late Maastrichtian zones, including three subzones, and one new early Danian zone are defined. The oldest beds correlate well with the late Maastrichtian of New Zealand. In a wider context, a new South Polar Province based on Maastrichtian to Danian dinoflagellate cysts is proposed, which excludes most southern South American marine palynofloras. This interpretation is supported by models of ocean currents around Antarctica and implies an unrestricted oceanic connection across Antarctica between southern South America and the Tasman Sea.
Antarctic and Southern Ocean science is vital to understanding natural variability, the processes... more Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to 'scan the horizon' to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A coordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone.
The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred duri... more The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred during the latest Eocene-earliest Oligocene. Prior to this, during the Early-Middle Eocene, Antarctica experienced warm climates, at least on the margins of the continent where geological evidence is present. Climates appear to have been warm and wet, the seas were warm and plants flourished in a frost-free environment, although there is some suggestion of valley glaciers on King George Island. Climate signals in the geological record show that the climate then cooled but not enough to allow the existence of significant ice until the latest Eocene.
Prostrate trees record average climate over decadal time periods in tree ring cellulose-δ 18 O. •... more Prostrate trees record average climate over decadal time periods in tree ring cellulose-δ 18 O. • Late Neogene Antarctic wood indicates a~12‰ enrichment in H 2 O-δ 18 O relative to today. • Evidence for marked changes in Antarctic hydrological cycle
Latitudinal Controls on Stratigraphic Models and Sedimentary Concepts, 2019
Climate plays a significant role in determining the style of depositional processes at different ... more Climate plays a significant role in determining the style of depositional processes at different latitudes, which in turn influences the location of hydrocarbon systems. Results of climate modelling may therefore provide important information for predicting the presence or absence of suitable hydrocarbon plays. The critical step is to validate the model results against proxy data where they are available, to determine whether the models provide realistic results. Paleoclimate proxy data are most often derived from more accessible low to mid latitude regions and are biased towards warm climate states. However, General Circulation Models (GCMs) have traditionally been biased to colder temperatures, in particular at high latitudes, struggling to maintain the high latitude regions warm enough to sustain forests that were present during greenhouse periods, such as the mid-Cretaceous (~110-90 Ma), without exaggerated warming of the equatorial regions. To the HadCM3L GCM, coupled with updated paleogeographic maps, can produce a good match to the climate proxy data in these difficult-to-model high latitude areas.
Extended Data Fig. 2 | Pollen abundance diagram. Percentages of the most abundant pollen and spor... more Extended Data Fig. 2 | Pollen abundance diagram. Percentages of the most abundant pollen and spores and their total counts in cores 9R and 10R at site PS104_20-2 are shown. Extended Data Fig. 4 | HG palaeothermometry. Presence of HGs at 27.03-27.04 mbsf at site PS104_20-2 (core 9R) and river or lake surface water temperature (SWT) estimates from the HG-based molecular palaeothermometer (HTI 30).
The Cretaceous-Paleogene (K-Pg) mass extinction event 66 million years ago led to large changes t... more The Cretaceous-Paleogene (K-Pg) mass extinction event 66 million years ago led to large changes to the global carbon cycle, primarily via a decrease in primary or export productivity of the oceans. However, the effects of this event and longer-term environmental changes during the Late Cretaceous on the global sulfur cycle are not well understood. We report new carbonate associated sulfate (CAS) sulfur isotope data derived from marine macrofossil shell material from a highly expanded high latitude Maastrichtian to Danian (69-65.5 Ma) succession located on Seymour Island, Antarctica. These data represent the highest resolution seawater sulfate record ever generated for this time interval, and are broadly in agreement with previous low-resolution estimates for the latest Cretaceous and Paleocene. A vigorous assessment of CAS preservation using sulfate oxygen, carbonate carbon and oxygen isotopes and trace element data, suggests factors affecting preservation of primary seawater CAS isotopes in ancient biogenic samples are complex, and not necessarily linked to the preservation of original carbonate mineralogy or chemistry. Primary data indicate a generally stable sulfur cycle in the early-mid Maastrichtian (69 Ma), with some fluctuations that could be related to increased pyrite burial during the 'mid-Maastrichtian Event'. This is followed by an enigmatic +4‰ increase in d 34 S CAS during the late Maastrichtian (68-66 Ma), culminating in a peak in values in the immediate aftermath of the K-Pg extinction which may be related to temporary development of oceanic anoxia in the aftermath of the Chicxulub bolide impact. There is no evidence of the direct influence of Deccan volcanism on the seawater sulfate isotopic record during the late Maastrichtian, nor of a direct influence by the Chicxulub impact itself. During the early Paleocene (magnetochron C29R) a prominent negative excursion in seawater d 34 S of 3-4‰ suggests that a global decline in organic carbon burial related to collapse in export productivity, also impacted the sulfur cycle via a significant drop in pyrite burial. Box modelling suggests that to achieve an excursion of this magnitude, pyrite burial must be reduced by >15%, with a possible role for a short term increase in global weathering rates. Recovery of the sulfur cycle to pre-extinction values occurs at the same time ($320 kyrs) as initial carbon cycle recovery globally. These recoveries are also contemporaneous with an initial increase in local alpha diversity of marine macrofossil faunas, suggesting biosphere-geosphere links during recovery from the mass extinction. Modelling further indicates that concentrations of sulfate in the oceans must have been 2 mM, lower than previous estimates for the Late Cretaceous and Paleocene and an order of magnitude lower than today.
The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high p... more The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process ‘big data’ collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets ...
The Paleocene (66-56 Ma) was a critical time interval for understanding recovery from mass extinc... more The Paleocene (66-56 Ma) was a critical time interval for understanding recovery from mass extinction in high palaeolatitudes when global climate was warmer than today. A unique sedimentary succession from Seymour Island (Antarctic Peninsula) provides key reference material from this important phase of the early Cenozoic. Dinoflagellate cyst data from a 376 m thick stratigraphical section, including the Cretaceous-Paleogene boundary, is correlated with biozones from New Zealand, the East Tasman Plateau and southeastern Australia. A detailed age model is suggested for the López de Bertodano (LDBF) and Sobral (SF) formations based on dinoflagellate cyst biostratigraphy and U-Pb dating of zircons, supported by correlated magnetostratigraphy and strontium isotope values from macrofossils. The top of the LDBF is confirmed as latest Maastrichtian to earliest Danian (~66.2-65.65 Ma) in age. The overlying SF is mostly Danian in age, with an inferred hiatus near the top overlain by sediments dated as ?late Thanetian. Rare Apectodinium homomorphum first appear in the uppermost SF; the earliest in situ record from Antarctica. The distribution of marine and terrestrial fossils from uppermost Cretaceous to Eocene sediments in Patagonia, Antarctica, New Zealand and Australia required both sea and land connections between these fragments of Gondwana. Fossil evidence and reconstructions of Antarctic palaeogeography and palaeotopography reveal evidence for persistent embayments in the proto-Weddell and Ross Sea regions at this time. We conclude that a coastal dispersal route along the palaeo-Pacific margin of Gondwana could explain the fossil distribution without requiring a transAntarctic strait or closely spaced archipelago. A region in the West to East Antarctic boundary zone, elevated until the early Paleogene, perhaps acted as a site for high elevation ice caps. This supports fossil, geochemical and sedimentological evidence for cold climate intervals and significant sea level falls during the Maastrichtian and Paleocene.
GSA Annual Meeting in Phoenix, Arizona, USA - 2019, 2019
Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 millio... more Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 million years ago shaped the composition and structure of modern ecosystems. The timing and nature of recovery has been linked to many factors including palaeolatitude, geographical range, the ecology of survivors, incumbency and palaeoenvironmental setting. Using a temporally constrained fossil dataset from one of the most expanded K-Pg successions in the world, integrated with palaeoenvironmental information, we provide the most detailed examination of the patterns and timing of recovery from the K-Pg mass extinction event in the high southern latitudes of Antarctica. The timing of biotic recovery was influenced by global stabilization of the wider Earth system following severe environmental perturbations, apparently regardless of latitude or local environment. Extinction intensity and ecological change were decoupled, with community scale ecological change less distinct compared to other locations, even if the taxonomic severity of the extinction was the same as at lower latitudes. This is consistent with a degree of geographical heterogeneity in the recovery from the K-Pg mass extinction. Recovery in Antarctica was influenced by local factors (such as water depth changes, local volcanism, and possibly incumbency and pre-adaptation to seasonality of the local benthic molluscan population), and also showed global signals, for example the radiation of the Neogastropoda within the first million years of the Danian, and a shift in dominance between bivalves and gastropods.
Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 millio... more Taxonomic and ecological recovery from the Cretaceous-Palaeogene (K-Pg) mass extinction 66 million years ago shaped the composition and structure of modern ecosystems. The timing and nature of recovery has been linked to many factors including palaeolatitude, geographical range, the ecology of survivors, incumbency and palaeoenvironmental setting. Using a temporally constrained fossil dataset from one of the most expanded K-Pg successions in the world, integrated with palaeoenvironmental information, we provide the most detailed examination of the patterns and timing of recovery from the K-Pg mass extinction event in the high southern latitudes of Antarctica. The timing of biotic recovery was influenced by global stabilization of the wider Earth system following severe environmental perturbations, apparently regardless of latitude or local environment. Extinction intensity and ecological change were decoupled, with community scale ecological change less distinct compared to other locations, even if the taxonomic severity of the extinction was the same as at lower latitudes. This is consistent with a degree of geographical heterogeneity in the recovery from the K-Pg mass extinction. Recovery in Antarctica was influenced by local factors (such as water depth changes, local volcanism, and possibly incumbency and pre-adaptation to seasonality of the local benthic molluscan population), and also showed global signals, for example the radiation of the Neogastropoda within the first million years of the Danian, and a shift in dominance between bivalves and gastropods.
Debate continues about the nature of the Cretaceous-Paleogene (K-Pg) mass extinction event. An ab... more Debate continues about the nature of the Cretaceous-Paleogene (K-Pg) mass extinction event. An abrupt crisis triggered by a bolide impact contrasts with ideas of a more gradual extinction involving flood volcanism or climatic changes. Evidence from high latitudes has also been used to suggest that the severity of the extinction decreased from low latitudes towards the poles. Here we present a record of the K-Pg extinction based on extensive assemblages of marine macrofossils (primarily new data from benthic molluscs) from a highly expanded Cretaceous-Paleogene succession: the López de Bertodano Formation of Seymour Island, Antarctica. We show that the extinction was rapid and severe in Antarctica, with no significant biotic decline during the latest Cretaceous, contrary to previous studies. These data are consistent with a catastrophic driver for the extinction, such as bolide impact, rather than a significant contribution from Deccan Traps volcanism during the late Maastrichtian.
The past vegetation and climate of West Antarctica and the evolution of its highly sensitive and ... more The past vegetation and climate of West Antarctica and the evolution of its highly sensitive and dynamic ice sheet are poorly constrained by geological data. The few existing far-field data, and even fewer proximal records, indicate a major ice-sheet build-up in West Antarctica from the Oligocene to the Miocene, with partial or even complete ice-sheet collapses during warm Late Cenozoic intervals with near-modern atmospheric CO2-concentrations. Here we present first palynological results from the MeBo70 seabed drill cores collected in early 2017 from the Amundsen Sea shelf. The cores contain unconsolidated to highly consolidated sediments of Cretaceous to Holocene age. Preliminary analyses of pollen, spores and dinoflagellate cysts indicate that during the Cretaceous and early Paleogene the Amundsen Sea Embayment was covered by warm-temperate and temperate forests. The paper will focus on Turonian to Santonian (ca. 93-85 Ma) peat layers in the oldest sections of the cores, which contain micro- and macrofossils documenting the evolution of a highly diverse, conifer-rich swamp forest during the Late Cretaceous.
Marine palynomorphs have been studied from a new section on Seymour Island in the James Ross Basi... more Marine palynomorphs have been studied from a new section on Seymour Island in the James Ross Basin, northern Antarctic Peninsula. At 65°S, both during the Maastrichtian and at the present day, it is an exceptional locality to investigate the nature of climates and sea level in the high southern palaeolatitudes across the Cretaceous-Paleogene (K-Pg) transition. Until now, Antarctic marine palynological studies have relied on dinoflagellate cyst zonation schemes from New Zealand and southeastern Australia. New high resolution data from this important location has allowed us to propose the first formal dinoflagellate cyst zonation scheme for the Antarctic Peninsula placing this Maastrichtian to earliest Paleogene succession from Seymour Island into a firm stratigraphical context. The shallow marine Lopez de Bertodano Formation (c.1100m thick) records the final c.3 myrs of the Cretaceous and crosses the K-Pg boundary. Varied and stratigraphically useful Manumiella spp. form the basis of two new ?late Maastrichtian zones (the Manumiella seymourensis Range Zone and the Manumiella bertodano Interval Zone). In addition, the exceptional expanded nature of this sequence allows the insertion of a new early Danian Hystrichosphaeridium tubiferum Acme Zone between the latest Maastrichtian Manumiella druggii Range Zone and the Danian Trithyrodinium evittii Acme Zone. The oldest beds correlate well with the late Maastrichtian of New Zealand. In a wider context, a review of Maastrichtian to earliest Paleogene marine palynofloras across the south polar region suggests the presence of a new South Polar Province for this time period with consequent implications for Antarctic palaeogeography.
Developments in earth and environmental sciences, 2008
The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred duri... more The change from a warm, ice-free greenhouse world to the glacial Antarctic icehouse occurred during the latest Eocene-earliest Oligocene. Prior to this, during the Early-Middle Eocene, Antarctica experienced warm climates, at least on the margins of the continent where geological evidence is present. Climates appear to have been warm and wet, the seas were warm and plants flourished in a frost-free environment, although there is some suggestion of valley glaciers on King George Island. Climate signals in the geological record show that the climate then cooled but not enough to allow the existence of significant ice until the latest Eocene.
Review of Palaeobotany and Palynology, Feb 1, 2012
The thickest uppermost Cretaceous to lowermost Paleogene (Maastrichtian to Danian) sedimentary su... more The thickest uppermost Cretaceous to lowermost Paleogene (Maastrichtian to Danian) sedimentary succession in the world is exposed on southern Seymour Island (65° South) in the James Ross Basin, Antarctic Peninsula. This fossiliferous shallow marine sequence, which spans the Cretaceous-Paleogene boundary, has allowed a high-resolution analysis of well-preserved marine palynomorphs. Previous correlation of Cretaceous-Paleogene marine palynomorph assemblages in the south polar region relied on dinoflagellate cyst biozonations from New Zealand and southern Australia. The age model of the southern Seymour Island succession is refined and and placed within the stratigraphical context of the mid to high southern palaeolatitudes. Quantitative palynological analysis of a new 1102 m continuous stratigraphical section comprising the uppermost Snow Hill Island Formation and the López de Bertodano Formation (Marambio Group) across southern Seymour Island was undertaken. We propose the first formal late Maastrichtian to 2 early Danian dinoflagellate cyst zonation scheme for the Antarctic based on this exceptional succession. Two new late Maastrichtian zones, including three subzones, and one new early Danian zone are defined. The oldest beds correlate well with the late Maastrichtian of New Zealand. In a wider context, a new South Polar Province based on Maastrichtian to Danian dinoflagellate cysts is proposed, which excludes most southern South American marine palynofloras. This interpretation is supported by models of ocean currents around Antarctica and implies an unrestricted oceanic connection across Antarctica between southern South America and the Tasman Sea.
Antarctic and Southern Ocean science is vital to understanding natural variability, the processes... more Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to 'scan the horizon' to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A coordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone.
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