Paleoceanography of the eastern Indian Ocean from ODP Leg 121 drilling on Broken Ridge

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doi: 10.1130/0016-7606(1990)102<0679:POTEIO>2.3.CO;2
Author(s): Rea, David K.; Dehn, Jonathan; Driscoll, Neal W.; Farrell, John W.; Janecek, Thomas R.; Owen, Robert M.; Pospichal, James J.; Resiwati, Purtyasti; Peirce, John W.; Weissel, Jeffrey K.; Fourtanier, Elisabeth; Frey, Frederick A.; Gamson, Paul D.; Gee, Jeffrey S.; Gibson, Ian L.; Klootwijk, Chris; Lawrence, James R.; Littke, Ralf; Newman, Jerry S.; Nomura, Ritsuo; Saunders, Andrew D.; Smit, Jan; Smith, Guy M.; Tamaki, Kensaku; Taylor, Elliott; Weis, Dominique; Wilkinson, Craig
Ocean Drilling Program, Leg 121, Shipboard Scientific Party
Volume Title: Geological Society of America Bulletin
Source: Geological Society of America Bulletin, 102(5), p.679-690. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7606 CODEN: BUGMAF
Note: In English. 48 refs.; illus. incl. 3 tables, sketch maps
Summary: Broken Ridge, in the eastern Indian Ocean,is overlain by about 1,600 m of middle Cretaceous to Pleistocene tuffaceous and carbonate sediments that record the oceanographic history of southern hemisphere mid-to high-latitude regions. Prior to about 42 Ma, Broken Ridge formed the northern part of the broad Kerguelen-Broken Ridge Plateau. During the middle Eocene, this feature was split by the newly forming Southeast Indian Ocean Ridge; since then, Broken Ridge has drifted north from about 55° to 31°S.The lower part of the sedimentary section is characterized by Turonian to Santonian tuffs that contain abundant glauconite and some carbonate. The tuffs record a large but apparently local volcanic input that characterized the central part of Broken Ridge into the early Tertiary. Maestrichtian shallow-water(several hundred to 1,000 m depth) limestones and cherts accumulated at some of the highest rates ever documented from the open ocean, 4 to 5 g (cm2 · 103 yr)-1. A complete (with all biostratigraphic zones) Cretaceous-Tertiary boundary section was recovered from site 752. The first 1.5 m.y. of the Tertiary is characterized by an order-of-magnitude reduction in the flux of biogenic sediments, indicating a period of sharply reduced biological productivity at 55°S, following which the carbonate and silica sedimentation rates almost reach the previous high values of the latest Cretaceous. We recovered a complete section through the Paleocene that contains all major fossil groups and is more than 300 m thick, perhaps the best pelagic Paleocene section encountered in ocean drilling. About 42 Ma, Broken Ridge was uplifted 2,500 m in response to the intra-plateau rifting event; subsequent erosion and deposition has resulted in a prominent Eocene angular unconformity atop the ridge. An Oligocene disconformity characterized by a widespread pebble layer probably represents the 30 Ma sea-level fall. The Neogene pelagic ooze on Broken Ridge has been winnowed, and thus its grain size provides a direct physical record of the energy of the southern hemisphere drift current in the Indian Ocean for the past 30 m.y.
Year of Publication: 1990
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 12 Stratigraphy, Historical Geology and Paleoecology; Broken Ridge; Carbonate rocks; Cenozoic; Chemically precipitated rocks; Chert; Continental drift; Cores; Cretaceous; Depositional environment; Indian Ocean; Kerguelen Plateau; Leg 121; Limestone; Lithostratigraphy; Marine environment; Marine sedimentation; Marine sediments; Mesozoic; Mid-Indian Ridge; Mid-ocean ridges; Ocean Drilling Program; Paleo-oceanography; Paleocurrents; Plate tectonics; Sedimentary rocks; Sedimentation; Sedimentation rates; Sediments; Southeast Indian Ridge; Southeastern Indian Ocean; Stratigraphic boundary; Stratigraphy; Volcaniclastics; Volcanism
Coordinates: S313000 S303000 E0940000 E0930000
Record ID: 1990030250
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