The heavy mineral record in the Pliocene to Quaternary sediments of the CIROS-2 drill core, McMurdo Sound, Antarctica

摘要: The heavy mineral assemblages of the Lower Pliocene to Quaternary glacial sediments CIROS-2 drill site, situated near mouth Ferrar Glacier on McMurdo Sound shelf, Antarctica, were analysed by optical means in order reconstruct source areas and dynamics late Cenozoic Antarctic ice masses. are dominated pyroxenes, amphiboles, altered minerals opaque minerals. Within pyroxene group, clinopyroxenes most abundant; within amphibole green brown hornblendes dominant. Other important present minor amounts zircon, titanite, epidote, garnet apatite. downcore distribution allows a subdivision sedimentary sequence into two major units, which can both be further subdivided subunits. interval between 166 110 mbsf is characterized relatively high concentrations apatite, garnet, epidote hornblende. This assemblage accounts for some 40‐60% points west Transantarctic Mountains, where intrusive, metamorphic rocks cover large areas. 166‐137 (Lower Pliocene) contains additional hornblende palagonite, indicative volcanic, probably hyaloclastitic source, possibly has sought beneath Glacier. In contrast, uppermost top core clinopyroxenes, record main area south or east, occupied basaltic Volcanic Group. A slight change composition group occurs this interval, at 48 mbsf. Thus, document different therewith changes dynamics. During discharged through Mountains Sound. shifted south, region present-day Ross Ice Shelf. © 1999 Elsevier Science B.V. All rights reserved.