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Miocene Glacial Dynamics Recorded by Variations in Magnetic Properties in the ANDRILL‐2A Drill Core
Author(s) -
Jovane Luigi,
Florindo Fabio,
Acton Gary,
Ohneiser Christian,
Sagnotti Leonardo,
Strada Eleonora,
Verosub Kenneth L.,
Wilson Gary S.,
Iacoviello Francesco,
Levy Richard H.,
Passchier Sandra
Publication year - 2019
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb016865
Subject(s) - geology , glacial period , antarctic ice sheet , sedimentary rock , neogene , ice shelf , drilling , paleontology , ice sheet , last glacial maximum , glacier , continental shelf , oceanography , geomagnetic reversal , ice core , sea level , sea ice , structural basin , cryosphere , mechanical engineering , physics , quantum mechanics , magnetic field , engineering
Abstract During the 2007 ANtarctic geological DRILLing (ANDRILL) campaign in the Ross Sea, Antarctica, the AND‐2A core was recovered through a stratigraphic succession spanning 1,138.54 m of Neogene sedimentary rocks that include an expanded early to middle Miocene sequence. The study reported here focuses on the magnetic properties of the interval from 778.63 m below sea floor (mbsf) to 1,138.54 mbsf, which comprises a time interval spanning 1.5 Myr, from ~18.7 to ~20.2 Ma. We recognize three main pulses of increased input of magnetic materials to the drill site between 778.34–903.06, 950.55–995.78, and 1,040–1,103.96 mbsf. Trends in the magnetic mineral concentration dependent parameters mirror changes in the proportion of sediments derived from McMurdo Volcanic Group rocks. We suggest that these pulses in magnetic mineral concentration reflect changes in sediment transport processes associated with changing glacial conditions at the drill site that included (1) subglacial and grounding zone proximal settings, (2) hemipelagic and neritic conditions with abundant sediment‐rich icebergs, and (3) grounding zone‐distal environment that was covered by land‐fast multiyear sea ice or a fringing ice shelf. The magnetic minerals record preserved in the AND‐2A core supports other data that indicate a highly dynamic and variable coastal environment during the early Miocene, where glaciers retreated inland under warm climatic conditions and advanced beyond the drill site across the continental shelf when cold climate prevailed.