Environmental magnetic record of paleoclimate, unroofing of

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TitleEnvironmental magnetic record of paleoclimate, unroofing of the Transantarctic Mountains, and volcanism in late Eocene to early Miocene glaci-marine sediments from the Victoria Land Basin, Ross Sea, AntarcticaAbstractWe synthesize environmental magnetic results for sediments from the Victoria Land Basin (VLB), which span a total stratigraphic thickness of 2.6â€‰km and a Â 17â€‰Myr age range. We assess how magnetic properties record paleoclimatic, tectonic, and provenance variations or mixtures of signals resulting from these processes. The magnetic properties are dominated by large-scale magnetite concentration variations. In the late Eocene and early Oligocene, magnetite concentration variations coincide with detrital smectite concentration and crystallinity variations, which reflect paleoclimatic control on magnetic properties through influence on weathering regime; high magnetite and smectite concentrations indicate warmer and wetter climates and vice versa. During the early Oligocene, accelerated uplift of the Transantarctic Mountains gave rise to magnetic signatures that reflect progressive erosion of the Precambrian-Mesozoic metamorphic, intrusive, and sedimentary stratigraphic cover succession associated with unroofing of the adjacent Transantarctic Mountains. From the early Oligocene to the early Miocene, a consistent fining upward of magnetite particles through the recovered composite record likely reflects increased physical weathering with glacial grinding contributing to progressively finer grained Ferrar Dolerite-sourced magnetite. After 24â€‰Ma, the magnetic properties of VLB sediments are primarily controlled by the weathering and erosion of McMurdo Volcanic Group rocks; increased volcanic glass contents contribute to the fining upward of magnetite grain size. Overall, long-term magnetic property variations record the first-order geological processes that controlled sedimentation in the VLB, including paleoclimatic, tectonic, provenance, and volcanic influences.AcknowledgementsWe gratefully acknowledge the U.S. National Science Foundation Office of Polar Programs, the Programma Nazionale di Ricerche in Antartide (PNRA), the New Zealand Foundation for Research (Contract UOOX0207), and the New Zealand Ministry of Science and Innovation (Contract C05X1001), respectively, for supporting this work. We also acknowledge our colleagues from the Cape Roberts Project (led by Peter Barrett and Peter Webb) for numerous discussions that helped to develop someof the ideas expressed here. A.P.R. is grateful to the PNRA for funding a stayin Rome that enabled preparation of much of this paper. We thank Ted Evans and Stefanie Brachfeld for constructive review comments and Tom Parsons forefficient editorial handling.

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1st AuthorRoberts, A.AuthorRoberts, A.Sagnotti, L.Florindo, F.Bohaty, S.Verosub, K.Wilson, G.Zachos, J.Year2013JournalJournal of Geophysical Research: Solid EarthVolume118Number5Pages1845-1861DOI10.1002/jgrb.50151URLhttps://www.scopus.com/inward/recor.....8d2aadffd7c45bdba8cff6e74KeywordsEoceneglaciomarine depositmagnetic surveyMiocenepaleoclimatepaleoenvironmentvolcanism, AntarcticaEast AntarcticaRoss SeaSouthern OceanVictoria Land Basin, rank3

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TypeArticleCitationRoberts, A., Sagnotti, L., Florindo, F., Bohaty, S., Verosub, K., Wilson, G. and Zachos, J. (2013) Environmental magnetic record of paleoclimate, unroofing of the Transantarctic Mountains, and volcanism in late Eocene to early Miocene glaci-marine sediments from the Victoria Land Basin, Ross Sea, Antarctica. Journal of Geophysical Research: Solid Earth, 118(5): 1845-1861 doi:10.1002/jgrb.50151 IdentifierRoberts2013Relevancerank3

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Wilson, G.