Miocene reversal of bottom water flow along the Pacific margin of the Antarctic Peninsula; stratigraphic evidence from a contourite sedimentary tail

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doi: 10.1016/j.margeo.2005.12.010
Author(s): Hernández-Molina, F. J.; Larter, R. D.; Rebesco, M.; Maldonado, A.
Author Affiliation(s): Primary:
Universidad de Vigo, Departamento de Geociencias Marinas, Vigo, Spain
British Antarctic Survey, United Kingdom
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Italy
University of Granada, Spain
Volume Title: Marine Geology
Source: Marine Geology, 228(1-4), p.93-116. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227
Note: In English. 88 refs.; illus., incl. sects., 1 table, sketch maps
Summary: A Fossil Mounded Sedimentary Body (MB) has been identified in the sedimentary record on the central continental rise west of Adelaide Island, on the Antarctic Peninsula Pacific margin. The growth patterns of the MB are defined through a detailed regional stratigraphic analysis using multichannel seismic reflection profiles. The MB has an elongated NE trend. It overlaps and continues to the NE of an extensive cluster of seamounts, and it developed between two non-depositional troughs. Nine seismic units have been identified: Unit 9 (the pre-MB stage), Unit 8 (MB growth stage), Units 7 and 6 (MB maintenance stage), Units 5 and 4 (transitional stage), and Units 3, 2 and 1 (inactive stage). We interpret the MB as a patch drift plastered against the NE, lee side of an obstacle, as a long Contourite Sedimentary Tail (CST), within a deep current that flowed northeastward. This segment of the rise is, however, affected at present by a SW-flowing branch of the Lower Circumpolar Deep Water (LCDW) from the Weddell Sea. The depositional patterns of the MB growth and maintenance stages, which are attributed an early Miocene age on the basis of regional correlation of MCS profiles with DSDP Site 325 and ODP Leg 178 drill sites, provide the first evidence that bottom currents on the central continental rise flowed towards the NE at that time, probably as part of the Lower Circumpolar Deep Water (LCDW) of the Antarctic Circumpolar Current (ACC). We suggest that significant palaeocirculation and palaeoceanographic changes occurred in this area, and probably more widely, during the middle Miocene or at the Miocene/Pliocene boundary. Although these results do not modify the regional stratigraphy of the major sediment drifts found on the continental rise of the Antarctic Peninsula's Pacific margin, they do indicate that the bottom current regime controlling the development of contourite deposits may have changed over time and also that more than one water mass has probably affected their distribution. Abstract Copyright (2006) Elsevier, B.V.
Year of Publication: 2006
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctic Circumpolar Current; Antarctic Peninsula; Antarctica; Bottom water; Cenozoic; Chronostratigraphy; Clastic sediments; Continental margin; Contourite; Cores; DSDP Site 325; Deep Sea Drilling Project; Depositional environment; Drift; Geophysical methods; Geophysical profiles; Geophysical surveys; Leg 178; Leg 35; Miocene; Neogene; Ocean Drilling Program; Ocean circulation; Ocean floors; Paleo-oceanography; Paleocirculation; Paleocurrents; Pliocene; Quaternary; Reconstruction; Reflection methods; Seamounts; Sediments; Seismic methods; Seismic profiles; Seismic stratigraphy; Southern Ocean; Surveys; Tertiary
Coordinates: S663000 S650000 W0700000 W0740000
Record ID: 2006053502
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands