The Vegetation of Antarctica through Geological Time

The Vegetation of Antarctica through Geological Time

Author: David J. Cantrill

Publisher: Cambridge University Press

Published: 2012-11-22

Total Pages: 489

ISBN-13: 113956028X

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The fossil history of plant life in Antarctica is central to our understanding of the evolution of vegetation through geological time and also plays a key role in reconstructing past configurations of the continents and associated climatic conditions. This book provides the only detailed overview of the development of Antarctic vegetation from the Devonian period to the present day, presenting Earth scientists with valuable insights into the break up of the ancient supercontinent of Gondwana. Details of specific floras and ecosystems are provided within the context of changing geological, geographical and environmental conditions, alongside comparisons with contemporaneous and modern ecosystems. The authors demonstrate how palaeobotany contributes to our understanding of the paleoenvironmental changes in the southern hemisphere during this period of Earth history. The book is a complete and up-to-date reference for researchers and students in Antarctic paleobotany and terrestrial paleoecology.


Evaluating Thresholds in Fluvial Response to the Eocene Thermal Maximum 2 in the Bighorn Basin (Wyoming, U.S.A)

Evaluating Thresholds in Fluvial Response to the Eocene Thermal Maximum 2 in the Bighorn Basin (Wyoming, U.S.A)

Author: Grace Marie Sutherland

Publisher:

Published: 2021

Total Pages: 272

ISBN-13:

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Earth's climate experienced a set of hyperthermal events during the greenhouse climate state of the early Paleogene. The Paleocene-Eocene Thermal Maximum (PETM) was the largest of these abrupt global warming events, occurring at ~56 Ma and lasting for ~200,000 years. The PETM is identifiable by a large negative carbon isotope excursion and associated with significant changes in global temperature, hydrology, ocean chemistry, and biology. Subsequent smaller hyperthermal events appear to have commensurately smaller effects on marine environments, but the scaling of the complementary nonmarine environmental responses is unclear. The Bighorn Basin of northwest Wyoming contains the most detailed nonmarine record of the PETM, and recent work has identified a significant perturbation of fluvial deposition associated with it. The PETM generated a thick and laterally extensive sandbody likely due to enhanced channel mobility potentially mediated by higher sediment flux related to an increase in rainfall variability. This study compares and contrasts fluvial deposition spanning a younger hyperthermal event at ~53 Ma, the ETM2 event, which was approximately 50,000 years in duration and displays a carbon isotope excursion with half the magnitude of the PETM. Herein I present sandbody geometries, lithofacies patterns, flow depths, and paleocurrent patterns spanning the ETM2 for comparison to PETM-induced fluvial changes. I find channel-fills are dominated by fining upward sequences of trough crossbedding and ripple cross lamination and abundant bar clinoform deposition. Sandbodies are typically single-storied and 3 meters in thickness. Notably, there are no significant changes in fluvial deposition across the ETM2. Several hypotheses may explain this observation: (1) there were no major hydrologic changes associated with the ETM2; (2) there were no major changes in vegetation associated with the ETM2; and/or (3) environmental perturbations were insufficient to overcome the internal autogenic thresholds of the river systems. These three hypotheses are not mutually exclusive, and each is evaluated in the context of existing datasets.


Circum-Arctic Structural Events

Circum-Arctic Structural Events

Author: Karsten Piepjohn

Publisher: Geological Society of America

Published: 2019-05-23

Total Pages:

ISBN-13: 0813725410

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"To recognize the 25th anniversary of the Circum-Arctic Structural Events program, an effort organized by the Bundesanstalt für Geowissenschaften und Rohstoffe, this volume presents results from 18 major field expeditions involving 100+ geoscientists from a spectrum of disciplines. The volume focuses on the Proterozoic to Cenozoic tectonic evolution of the circum-Arctic region with correlations to adjacent orogens"--


The Paleocene Eocene Thermal Maximum

The Paleocene Eocene Thermal Maximum

Author: Eric Petermann

Publisher: GRIN Verlag

Published: 2009-12-10

Total Pages: 10

ISBN-13: 3640491122

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Essay from the year 2009 in the subject Geography / Earth Science - Geology, Mineralogy, Soil Science, grade: 1,3, University of Leipzig (Institut für Geophysik und Geologie), course: M.Sc. Modul Paläoklimatologie, language: English, abstract: At the Paleocene/Eocene boundary (55 Ma BP) a general global warming trend was overruled by an outstanding 4-6 °C (Dickens et al. 1997; Zachos et al. 2001) short-term warming event. This information is derived from a -2 to -3‰ negative δ 18O excursion accompanied by an -2.5 ‰ δ13C excursion (Fig.1). Both isotope excursions occur simultaneously and reach their minimal values very rapidly within less than 10 ka. They return to initial values after ~200 ka. PETM climate conditions resulted in extinction of archaic mammals while modern mammalian ancestors have appeared as well as in extinction or temporal disappearance of many deep-sea species (Dickens et al. 1997). δ 18O values of benthic foraminifera of all oceans and planktic foraminifera at high-latitude locations are marked by a sharp decrease (Fig.1) indicating a striking global temperature increase of the deep-sea and high-latitude surface water temperatures (Dickens et al. 1997). A simultaneous negative δ13C excursion is documented in marine as well as in terrestrial environments all over the world. The carbon isotope excursion is attributed to the release of massive quantities of biogenic methane (δ13C = -60‰) adding large amounts of 12C to the inorganic carbon reservoir. Mass balance calculations suggest a transfer of 1400 to 2800 Gt (Dickens et al.1997) respectively 1500 to 2200 Gt (Katz et al. 2001) of CH4 to the ocean/atmosphere system to explain the negative carbon isotope excursion.


Polar Environments and Global Change

Polar Environments and Global Change

Author: Roger G. Barry

Publisher: Cambridge University Press

Published: 2018-08-09

Total Pages: 445

ISBN-13: 1108423167

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Surveys atmospheric, oceanic and cryospheric processes, present and past conditions, and changes in polar environments.


The Arctic in the Anthropocene

The Arctic in the Anthropocene

Author: National Research Council

Publisher: National Academies Press

Published: 2014-07-31

Total Pages: 240

ISBN-13: 0309301866

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Once ice-bound, difficult to access, and largely ignored by the rest of the world, the Arctic is now front and center in the midst of many important questions facing the world today. Our daily weather, what we eat, and coastal flooding are all interconnected with the future of the Arctic. The year 2012 was an astounding year for Arctic change. The summer sea ice volume smashed previous records, losing approximately 75 percent of its value since 1980 and half of its areal coverage. Multiple records were also broken when 97 percent of Greenland's surface experienced melt conditions in 2012, the largest melt extent in the satellite era. Receding ice caps in Arctic Canada are now exposing land surfaces that have been continuously ice covered for more than 40,000 years. What happens in the Arctic has far-reaching implications around the world. Loss of snow and ice exacerbates climate change and is the largest contributor to expected global sea level rise during the next century. Ten percent of the world's fish catches comes from Arctic and sub-Arctic waters. The U.S. Geological Survey estimated that up to 13 percent of the world's remaining oil reserves are in the Arctic. The geologic history of the Arctic may hold vital clues about massive volcanic eruptions and the consequent release of massive amount of coal fly ash that is thought to have caused mass extinctions in the distant past. How will these changes affect the rest of Earth? What research should we invest in to best understand this previously hidden land, manage impacts of change on Arctic communities, and cooperate with researchers from other nations? The Arctic in the Anthropocene reviews research questions previously identified by Arctic researchers, and then highlights the new questions that have emerged in the wake of and expectation of further rapid Arctic change, as well as new capabilities to address them. This report is meant to guide future directions in U.S. Arctic research so that research is targeted on critical scientific and societal questions and conducted as effectively as possible. The Arctic in the Anthropocene identifies both a disciplinary and a cross-cutting research strategy for the next 10 to 20 years, and evaluates infrastructure needs and collaboration opportunities. The climate, biology, and society in the Arctic are changing in rapid, complex, and interactive ways. Understanding the Arctic system has never been more critical; thus, Arctic research has never been more important. This report will be a resource for institutions, funders, policy makers, and students. Written in an engaging style, The Arctic in the Anthropocene paints a picture of one of the last unknown places on this planet, and communicates the excitement and importance of the discoveries and challenges that lie ahead.