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Author: David Michael Harwood Publisher: ISBN: Category : Diatoms Languages : en Pages : 1190
Book Description
Abstract: The history of Cenozoic ice sheets in Antarctica has been interpreted largely from deep-sea data. A new approach, which provides a more direct evaluation of Antarctic ice history, involves the examination of reworked diatom assemblages in the Sirius Formation tillites. These diatoms originate from subglacial sedimentary basins in East Antarctica and indicate periods of relative warmth, ice sheet retreat and the repeated presence of marine seaways/embayments in the continental interior during the Cenozoic. Antarctic ice-minima conditions are indicated by marine diatoms and other microfossils recovered from Sirius Formation localities spread over 1300 km in the Transantarctic Mountains. The modern distribution and temperature limits of several Pliocene diatoms recovered from the Sirius Formation indicate marine water as warm as 2̃°-5°C in the antarctic interior to at least 85°S latitude. Geologic time intervals not represented by microfossils in the Sirius Formation may indicate times of extensive ice development. The glacial history these microfossils suggest is substantiated by comparison to global sea-level and benthic foraminiferal oxygen isotope data. A detailed analysis of isotopic and eustatic records, together with Sirius Formation data, indicate ice-minima conditions and relative warmth, with marine seaways across Antarctica, during the Pliocene (5̃ to 2.5 Ma), middle Miocene (1̃7 to 14 Ma), late Oligocene/early Miocene (2̃7 to 23 Ma) and during much of the early Oligocene and remaining Paleogene. Glaciations are indicated during the late Oligocene (3̃1 to 27 Ma), late Miocene (1̃0 to 5 Ma) and Pleistocene (2̃.5 Ma to present). Bottom-water/ice-shelf events, recognized in a detailed comparison of eustatic and benthic oxygen isotopic data, preceed late Oligocene and late Miocene ice-sheet growth by 5̃ million years. Analysis of diatom biostratigraphy and paleoecology from numerous in situ Oligocene through Pliocene sedimentary outcrops and drill-holes around the Antarctic periphery have aided dating of the above reworked microfossils and have documented glacial and marine fluctuations in more uniform environments. Of particular significance is the recovery of upper Oligocene glacial-marine sediments in the MSSTS-1 drill-hole, the oldest known from Antarctica.
Author: David Michael Harwood Publisher: ISBN: Category : Diatoms Languages : en Pages : 1190
Book Description
Abstract: The history of Cenozoic ice sheets in Antarctica has been interpreted largely from deep-sea data. A new approach, which provides a more direct evaluation of Antarctic ice history, involves the examination of reworked diatom assemblages in the Sirius Formation tillites. These diatoms originate from subglacial sedimentary basins in East Antarctica and indicate periods of relative warmth, ice sheet retreat and the repeated presence of marine seaways/embayments in the continental interior during the Cenozoic. Antarctic ice-minima conditions are indicated by marine diatoms and other microfossils recovered from Sirius Formation localities spread over 1300 km in the Transantarctic Mountains. The modern distribution and temperature limits of several Pliocene diatoms recovered from the Sirius Formation indicate marine water as warm as 2̃°-5°C in the antarctic interior to at least 85°S latitude. Geologic time intervals not represented by microfossils in the Sirius Formation may indicate times of extensive ice development. The glacial history these microfossils suggest is substantiated by comparison to global sea-level and benthic foraminiferal oxygen isotope data. A detailed analysis of isotopic and eustatic records, together with Sirius Formation data, indicate ice-minima conditions and relative warmth, with marine seaways across Antarctica, during the Pliocene (5̃ to 2.5 Ma), middle Miocene (1̃7 to 14 Ma), late Oligocene/early Miocene (2̃7 to 23 Ma) and during much of the early Oligocene and remaining Paleogene. Glaciations are indicated during the late Oligocene (3̃1 to 27 Ma), late Miocene (1̃0 to 5 Ma) and Pleistocene (2̃.5 Ma to present). Bottom-water/ice-shelf events, recognized in a detailed comparison of eustatic and benthic oxygen isotopic data, preceed late Oligocene and late Miocene ice-sheet growth by 5̃ million years. Analysis of diatom biostratigraphy and paleoecology from numerous in situ Oligocene through Pliocene sedimentary outcrops and drill-holes around the Antarctic periphery have aided dating of the above reworked microfossils and have documented glacial and marine fluctuations in more uniform environments. Of particular significance is the recovery of upper Oligocene glacial-marine sediments in the MSSTS-1 drill-hole, the oldest known from Antarctica.
Author: David Michael Harwood Publisher: ISBN: Category : Diatoms Languages : en Pages : 592
Book Description
Abstract: The history of Cenozoic ice sheets in Antarctica has been interpreted largely from deep-sea data. A new approach, which provides a more direct evaluation of Antarctic ice history, involves the examination of reworked diatom assemblages in the Sirius Formation tillites. These diatoms originate from subglacial sedimentary basins in East Antarctica and indicate periods of relative warmth, ice sheet retreat and the repeated presence of marine seaways/embayments in the continental interior during the Cenozoic. Antarctic ice-minima conditions are indicated by marine diatoms and other microfossils recovered from Sirius Formation localities spread over 1300 km in the Transantarctic Mountains. The modern distribution and temperature limits of several Pliocene diatoms recovered from the Sirius Formation indicate marine water as warm as ~2°-5°C in the antarctic interior to at least 85°S latitude. Geologic time intervals not represented by microfossils in the Sirius Formation may indicate times of extensive ice development. The glacial history these microfossils suggest is substantiated by comparison to global sea-level and benthic foraminiferal oxygen isotope data. A detailed analysis of isotopic and eustatic records, together with Sirius Formation data, indicate ice-minima conditions and relative warmth, with marine seaways across Antarctica, during the Pliocene (~5 to 2.5 Ma), middle Miocene (~17 to 14 Ma), late Oligocene/early Miocene (~27 to 23 Ma) and during much of the early Oligocene and remaining Paleogene. Glaciations are indicated during the late Oligocene (~31 to 27 Ma), late Miocene (~10 to 5 Ma) and Pleistocene (~2.5 Ma to present). Bottom-water/ice-shelf events, recognized in a detailed comparison of eustatic and benthic oxygen isotopic data, preceed late Oligocene and late Miocene ice-sheet growth by ~5 million years. Analysis of diatom biostratigraphy and paleoecology from numerous in situ Oligocene through Pliocene sedimentary outcrops and drill-holes around the Antarctic periphery have aided dating of the above reworked microfossils and have documented glacial and marine fluctuations in more uniform environments. Of particular significance is the recovery of upper Oligocene glacial-marine sediments in the MSSTS-1 drill-hole, the oldest known from Antarctica.
Author: Elisabeth S. Vrba Publisher: Yale University Press ISBN: 0300063482 Category : Social Science Languages : en Pages : 567
Book Description
Addressing the relationship between climatic and biotic evolution, this work focuses on how climatic change during the last 15 million years - especially the last three million - has affected human evolution and other evolutionary events.
Author: Gunter Faure Publisher: Springer Science & Business Media ISBN: 9048193907 Category : Science Languages : en Pages : 812
Book Description
This book presents a summary of the geology of the Transantarctic Mountains for Earth scientists who may want to work there or who need an overview of the geologic history of this region. In addition, the properties of the East Antarctic ice sheet and of the meteorites that accumulate on its surface are treated in separate chapters. The presentation ends with the Cenozoic glaciation of the Transantarctic Mountains including the limnology and geochemical evolution of the saline lakes in the ice-free valleys. • The subject matter in this book is presented in chronological order starting about 750 million years ago and continuing to the present time. • The chapters can be read selectively because the introduction to each chapter identifies the context that gives relevance to the subject matter to be discussed. • The text is richly illustrated with 330 original line drawings as well as with 182 color maps and photographs. • The book contains indexes of both subject matter and of authors’ names that allow it to be used as an encyclopedia of the Transantarctic Mountains and of the East Antarctic ice sheet. • Most of the chapters are supplemented by Appendices containing data tables, additional explanations of certain phenomena (e.g., the formation and seasonal destruction of stratospheric ozone), and illustrative calculations (e.g., 38Cl dates of meteorites). • The authors have spent a combined total of fourteen field seasons between 1964 and 1995 doing geological research in the Transantarctic Mountains with logistical support by the US Antarctic Program. • Although Antarctica is remote and inaccessible, tens of thousands of scientists of many nationalities and their assistants have worked there and even larger numbers of investigators will work there in the future.
Author: John Alden Publisher: Springer Science & Business Media ISBN: 1489916008 Category : Science Languages : en Pages : 565
Book Description
As forests decline in temperate and tropical climates, highly-developed countries and those striving for greater economic and social benefits are beginning to utilize marginal forests of high-latitude and mountainous regions for resources to satisfy human needs. The benefits of marginal forests range from purely aesthetic to providing resources for producing many goods and services demanded by a growing world population. Increased demands for forest resources and amenities and recent warming of high latitude climates have generated interest in reforestation and afforestation of marginal habitats in cold regions. Afforestation of treeless landscapes improves the environment for human habitation and provides for land use and economic prosperity. Trees are frequently planted in cold climates to rehabilitate denuded sites, for the amenity of homes and villages, and for wind shelter, recreation, agroforestry, and industrial uses. In addition, forests in cold climates reduce the albedo of the earth's surface in winter, and in summer they are small but significant long-lived sinks for atmospheric carbon dioxide. Finally, growth and reproductive success of forests at their geographic limits are sensitive indices of climatic change. As efforts to adapt forests to cold climates increase, however, new afforestation problems arise and old ones intensify. Austral, northern, and altitudinal tree limits are determined by many different factors. Current hypotheses for high-latitude tree limits are based on low growing-season temperatures that inhibit plant development and reproduction.
Author: James P. Kennett Publisher: American Geophysical Union ISBN: Category : Science Languages : en Pages : 408
Book Description
Papers based on work presented at a conference held at the University of California, Santa Barbara, August 28-31 1991, entitled 'The Role of the Southern Ocean and Antarctica in Global Change : an Ocean Drilling Perspective.' Papers deal with paleoenvironmental data from the Antarctic, including geology, climate, fossils, sediments and the eustatic record.
Author: David Michael Harwood
Author: David Michael Harwood
Author: David Michael Harwood
Author: David Michael Harwood
Author: 
Author: Elisabeth S. Vrba
Author: Michael Robert Alexander Thomson
Author: Gunter Faure
Author: John Alden
Author: 
Author: James P. Kennett