The Antarctic Peninsula is considered to be the last region of Antarctica to have been fully glaciated as a result of Cenozoic climatic cooling. As such, it was likely the last refugium for plants and animals that had inhabited the continent since it separated from the Gondwana supercontinent. Drill cores and seismic data acquired during two cruises (SHALDRIL I and II) in the northernmost Peninsula region yield a record that, when combined with existing data, indicates progressive cooling and associated changes in terrestrial vegetation over the course of the past 37 million years. Mountain glaciation began in the latest Eocene (approximately 37-34 Ma), contemporaneous with glaciation elsewhere on the continent and a reduction in atmospheric CO2 concentrations. This climate cooling was accompanied by a decrease in diversity of the angiosperm-dominated vegetation that inhabited the northern peninsula during the Eocene. A mosaic of southern beech and conifer- dominated woodlands and tundra continued to occupy the region during the Oligocene (approximately 34-23 Ma). By the middle Miocene (approximately 16-11.6 Ma), localized pockets of limited tundra still existed at least until 12.8 Ma. The transition from temperate, alpine glaciation to a dynamic, polythermal ice sheet took place during the middle Miocene. The northernmost Peninsula was overridden by an ice sheet in the early Pliocene (approximately 5.3-3.6 Ma). The long cooling history of the peninsula is consistent with the extended timescales of tectonic evolution of the Antarctic margin, involving the opening of ocean passageways and associated establishment of circumpolar circulation.
Anderson, J.B., Department of Earth Science, Rice University, Houston, TX 77005-1892, United States; Warny, S., Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, United States; Askin, R.A., 1930 Bunk House Drive, Jackson, WY 83001, United States; Wellner, J.S., Department of Earth and Atmospheric Sciences and Museum of Natural Science, University of Houston, Houston, TX 77204-5007, United States; Bohaty, S.M., School of Ocean and Earth Science, University of Southampton, Southampton S0143ZH, United Kingdom; Kirshner, A.E., Department of Earth Science, Rice University, Houston, TX 77005-1892, United States; Livsey, D.N., Department of Earth Science, University of California, Santa Barbara, CA 93106-9630, United States; Simms, A.R., Department of Earth Science, University of California, Santa Barbara, CA 93106-9630, United States; Smith, T.R., Department of Earth Science, Rice University, Houston, TX 77005-1892, United States; Ehrmann, W., Institute of Geophysics and Geology, University of Leipzig, D-04103 Leipzig, Germany; Lawver, L.A., Institute for Geophysics, University of Texas at Austin, Austin, TX 78758-4445, United States; Barbeau, D., Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC 29208, United States; Wise, S.W., Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306-4100, United States; Kulhenek, D.K., Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306-4100, United States; Weaver, F.M., Department of Earth Science, Rice University, Houston, TX 77005-1892, United States; Majewski, W., Institute of Paleobiology and Museum of Natural Science, Polish Academy of Sciences, 00-818 Warsaw, Poland
Recommended Citation:
Anderson J.B.,Warny S.,Askin R.A.,et al. Progressive Cenozoic cooling and the demise of Antarctica's last refugium[J]. Proceedings of the National Academy of Sciences of the United States of America,2011-01-01,108(28)