Leg 188 synthesis; transitions in the glacial history of the Prydz Bay region, East Antarctica, from ODP drilling

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doi: 10.2973/odp.proc.sr.188.001.2004
Author(s): Cooper, Alan K.; O'Brien, Philip E.
Ocean Drilling Program, Leg 188, Shipboard Scientific Party, College Station, TX
Author Affiliation(s): Primary:
Stanford University, Department of Geological and Environmental Sciences, Stanford, CA, United States
Other:
Australian Geological Survey Organisation, Australia
Ocean Drilling Program, United States
University of Leicester, United Kingdom
University of Nebraska, United States
University of Texas at Arlington, United States
Oxford University, United Kingdom
Istituto Nazionale di Geofisica e Vulcanologia, Italy
Norwegian Polar Institute, Norway
Christan-Albrechts-Universität zu Kiel, Federal Republic of Germany
University of Utah, United States
University of Toronto at Scarborough, Canada
Curtin University of Technology, Australia
Boston University, United States
British Antarctic Survey, United Kingdom
Ohio State University, United States
Florida State University, United States
University of Tasmania, Australia
Istituto Nazionale di Oceanografia e di Geofisico Sperimentale, Italy
University of Oulu, Finland
Jacques Whitford and Associates, Canada
California State University, United States
Lamont-Doherty Earth Observatory, United States
Volume Title: Proceedings of the Ocean Drilling Program; scientific results; Prydz Bay-Cooperation Sea, Antarctica; glacial history and paleoceanography; covering Leg 188 of the cruises of the drilling vessel JOIDES Resolution; Fremantle, Australia, to Hobart, Tasmania; Sites 1165-1167; 10 January-11 March 2000
Volume Author(s): Cooper, Alan K.; O'Brien, Philip E.; Richter, Carl; Barr, Samantha R.; Bohaty, Steven M.; Claypool, George E.; Damuth, John E.; Erwin, Patrick S.; Florindo, Fabio; Forsberg, Carl Fredrik; Grützner, Jens; Handwerger, David A.; Januszczak, Nicole N.; Kaiko, Alexander; Kryc, Kelly A.; Lavelle, Mark; Passchier, Sandra; Pospichal, James J.; Quilty, Patrick G.; Rebesco, Michele A.; Strand, Kari O.; Taylor, Brian; Theissen, Kevin M.; Warnke, Detlef A.; Whalen, Patricia A.; Whitehead, Jason M.; Williams, Trevor
Source: Proceedings of the Ocean Drilling Program; scientific results; Prydz Bay-Cooperation Sea, Antarctica; glacial history and paleoceanography; covering Leg 188 of the cruises of the drilling vessel JOIDES Resolution; Fremantle, Australia, to Hobart, Tasmania; Sites 1165-1167; 10 January-11 March 2000, Alan K. Cooper, Philip E. O'Brien, Carl Richter, Samantha R. Barr, Steven M. Bohaty, George E. Claypool, John E. Damuth, Patrick S. Erwin, Fabio Florindo, Carl Fredrik Forsberg, Jens Grützner, David A. Handwerger, Nicole N. Januszczak, Alexander Kaiko, Kelly A. Kryc, Mark Lavelle, Sandra Passchier, James J. Pospichal, Patrick G. Quilty, Michele A. Rebesco, Kari O. Strand, Brian Taylor, Kevin M. Theissen, Detlef A. Warnke, Patricia A. Whalen, Jason M. Whitehead and Trevor Williams; Ocean Drilling Program, Leg 188, Shipboard Scientific Party, College Station, TX. Proceedings of the Ocean Drilling Program, Scientific Results (CD ROM), Vol.188, 42p. Publisher: Texas A&M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 1096-2514
Note: In English. Also available on CD-ROM in PDF format and on the Web in PDF or HTML. 75 refs.CD-ROM format, ISSN 1096-2514; WWW format, ISSN 1096-7451; illus., incl. sects., strat. cols., sketch maps
Summary: Drilling during Leg 119 (1988) and Leg 188 (2000; Sites 1165-1167) of the Ocean Drilling Program (ODP) provides direct evidence for long- and short-term changes in Cenozoic paleoenvironments in the Prydz Bay region. Cores from across the continental margin reveal that in preglacial times the present shelf was an alluvial plain system with austral conifer woodland in the Late Cretaceous that changed to cooler Nothofagus rainforest scrub by the middle to late Eocene (Site 1166). Earliest recovered evidence of nearby mountain glaciation is seen in late Eocene-age grain textures in fluvial sands. In the late Eocene to early Oligocene, Prydz Bay permanently shifted from being a fluvio-deltaic complex to an exclusively marine continental shelf environment. This transition is marked by a marine flooding surface later covered by overcompacted glacial sediments that denote the first advance of the ice sheet onto the shelf. Cores do not exist for the early Oligocene to early Miocene, and seismic data are used to infer the transition from a shallow to normal depth prograding continental shelf with submarine canyons on the slope and channel/levees on the rise. Cores from the continental rise at Site 1165 show long-term (millions of years) early Miocene and younger decreases in sedimentation rates as well as short-term (Milankovitch periods) cyclicity between principally biogenic and terrigenous sediment supply-resulting from the cyclic presence of onshore glaciers and changes in ocean circulation. Middle Miocene transitions include rapid decreases in sedimentation rates, increased ice-rafted debris, shifts in clays and other minerals, and regional erosion of the slope and rise. These transitions may reflect enhanced glacial erosion and reduced glacial meltwater from progressively colder ice. At this time, seismic data show that depocenters began to shift from the outer continental rise to the base of the continental slope coincident with the initial stages of the glacial erosion and overdeepening of the continental shelf. During the late Miocene to early Pliocene there was a transition to greater subglacial activity on the shelf and more pronounced cyclic facies variations on the continental rise. At this time, severe glacial morphologies initiated on the shelf with the erosion of Prydz Channel and other troughs by fast-moving ice and the deposition of overcompacted glacial diamictons by slow-moving ice on adjacent banks. The Prydz trough-mouth fan also began to form with alternating deposition of debris flows (ice at shelf edge) and muddy units (reduced ice) (Site 1167). The fan also records a transition during the late Pleistocene for times younger than 780 k.y. when short-term glacial variations continued but ice reached the shelf edge only a few times. Both short-term and long-term transitions characterize the Cenozoic evolution of the Prydz Bay region from the Cretaceous nonglacial to late Neogene full-glacial paleoenvironments. These transitions are known only from ODP cores, and further insights will require additional drilling.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctica; Boreholes; Cenozoic; Climate change; Cores; Depositional environment; Diagenesis; East Antarctica; Glacial geology; Leg 188; Ocean Drilling Program; Paleoclimatology; Paleoenvironment; Paleotemperature; Prydz Bay; Southern Ocean; Variations
Coordinates: S674500 S640000 E0750000 E0670000
Record ID: 2004083813
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