Tectonic controls on the geochemical composition of Cenozoic, mafic alkaline volcanic rocks from West Antarctica

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Authors:Hole, M. J.; LeMasurier, W. E.
Author Affiliations:Primary:
University of Aberdeen, Department of Geology and Petroleum Geology, Aberdeen, United Kingdom
Other:
University of Colorado, United States
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 117(2), p.187-202. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1994
Note:In English. 83 refs.; illus., incl. 2 tables, geol. sketch maps
Summary:Cenozoic, mafic alkaline volcanic rocks throughout West Antarctica (WA) occupy diverse tectonic environments. On the Antarctic Peninsula (AP), late Miocene-Pleistocene (7 to 1 Ma) alkaline basaltic rocks were erupted 1 to 45 million years after subduction ceased along the Pacific margin of the AP. In Marie Byrd Land (MBL), by contrast, alkaline basaltic volcanism has been semi-continuous from 25-30 Ma to the present, and occurs in the West Antarctic rift system. Basaltic rocks throughout WA have uniform geochemical characteristics, with especially narrow ranges in initial 87Sr/86Sr, 143Nd/144Nd, and La/Nb ratios. However, there are significant differences in the relative and absolute abundances of the LILE (large-ion-lithophile elements), and these divide WA into two provinces. This geochemical contrast is accompanied by a three-fold increase in the age range of volcanic activity and a three orders of magnitude increase in the volume of eruptive products within MBL. Most MBL geochemical traits are shared by the volcanic rocks of the western Ross Sea, suggesting that a large plume head underlies the West Antarctic rift system. The uniformity of basalt compositions throughout WA and the entire rift system suggest uniformly minimal extension throughout this region during late Cenozoic time. (Auth. mod.)
Subjects:Alkali basalts; Alkalic composition; Alkaline earth metals; Basalts; Cenozoic; Cerium; Chemical composition; Igneous rocks; Isotopes; Mafic composition; Metals; Mid-ocean ridge basalts; Ocean-island basalts; Rare earths; Rift zones; Scandium; Sr-87/Sr-86; Stable isotopes; Strontium; Structural controls; Trace elements; Volcanic rocks; Ytterbium; Antarctica; Marie Byrd Land; West Antarctica; Ce/Yb; Fractionation; Sc/Yb
Abstract Numbers:95M/603
Record ID:1995027065
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from the Antarctic Bibliography, United States
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