Neogene tectonic and climatic evolution of the Western Ross Sea, Antarctica — Chronology of events from the AND-1B drill hole


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gerhard.kuhn [ at ] awi.de

Abstract

Stratigraphic drilling from the McMurdo Ice Shelf in the 2006/2007 austral summer recovered a 1284.87m sedimentary succession from beneath the sea floor. Key age data for the core include magnetic polarity stratigraphy for the entire succession, diatom biostratigraphy for the upper 600m and 40Ar/39Ar ages for in-situ volcanic deposits as well as reworked volcanic clasts. A vertical seismic profile for the drill hole allows correlation between the drill hole and a regional seismic network and inference of age constraint by correlation with well-dated regional volcanic events through direct recognition of interlayered volcanic deposits as well as by inference from flexural loading of pre-existing strata. The combined age model implies relatively rapid (1m/2-5ky) accumulation of sediment punctuated by hiatuses, which account for approximately 50% of the record. Three of the longer hiatuses coincide with basin-wide seismic reflectors and, along with two thick volcanic intervals, they subdivide the succession into seven chronostratigraphic intervals with characteristic facies:1.The base of the cored succession (1275-1220mbsf) comprises middle Miocene volcaniclastic sandstone dated at approx 13.5Ma by several reworked volcanic clasts;2.A late-Miocene sub-polar orbitally controlled glacial-interglacial succession (1220-760mbsf) bounded by two unconformities correlated with basin-wide reflectors associated with early development of the terror rift;3.A late Miocene volcanigenic succession (760-596mbsf) terminating with a ~1my hiatus at 596.35mbsf which spans the Miocene-Pliocene boundary and is not recognised in regional seismic data;4.An early Pliocene obliquity-controlled alternating diamictite and diatomite glacial-interglacial succession (590-440mbsf), separated from;5.A late Pliocene obliquity-controlled alternating diamictite and diatomite glacial-interglacial succession (440-150mbsf) by a 750ky unconformity interpreted to represent a major sequence boundary at other locations;6.An early Pleistocene interbedded volcanic, diamictite and diatomite succession (150-80mbsf), and;7.A late Pleistocene glacigene succession (80-0mbsf) comprising diamictite dominated sedimentary cycles deposited in a polar environment. © 2012 Elsevier B.V.



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31922
DOI https://www.doi.org/10.1016/j.gloplacha.2012.05.019

Cite as
Wilson, G. S. , Levy, R. H. , Naish, T. R. , Powell, R. D. , Florindo, F. , Ohneiser, C. , Sagnotti, L. , Winter, D. M. , Cody, R. , Henrys, S. , Ross, J. , Krissek, L. , Niessen, F. , Pompillio, M. , Scherer, R. , Alloway, B. V. , Barrett, P. J. , Brachfeld, S. , Browne, G. , Carter, L. , Cowan, E. , Crampton, J. , DeConto, R. M. , Dunbar, G. , Dunbar, N. , Dunbar, R. , von Eynatten, H. , Gebhardt, C. , Giorgetti, G. , Graham, I. , Hannah, M. , Hansaraj, D. , Harwood, D. M. , Hinnov, L. , Jarrard, R. D. , Joseph, L. , Kominz, M. , Kuhn, G. , Kyle, P. , Läufer, A. , McIntosh, W. C. , McKay, R. , Maffioli, P. , Magens, D. , Millan, C. , Monien, D. , Morin, R. , Paulsen, T. , Persico, D. , Pollard, D. , Raine, J. I. , Riesselman, C. , Sandroni, S. , Schmitt, D. , Sjunneskog, C. , Strong, C. P. , Talarico, F. , Taviani, M. , Villa, G. , Vogel, S. , Wilch, T. , Williams, T. , Wilson, T. J. and Wise, S. (2012): Neogene tectonic and climatic evolution of the Western Ross Sea, Antarctica — Chronology of events from the AND-1B drill hole , Global and Planetary Change, 96-97 , pp. 189-203 . doi: https://www.doi.org/10.1016/j.gloplacha.2012.05.019


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