The petrology of lower crustal xenoliths from the Executive Committee Range, Marie Byrd Land volcanic province, West Antarctica

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doi: 10.1016/0024-4937(95)00017-8
Authors:Wysoczanski, R. J.; Gamble, J. A.; Kyle, P. R.; Thirlwall, M. F.
Author Affiliations:Primary:
Victoria University of Wellington, Geology Department, Wellington, New Zealand
Other:
University of New South Wales, Australia
New Mexico Institute of Mining and Technology, Socorro, NM, United States
University of London, Egham, Surrey, United Kingdom
Volume Title:Special issue; The xenolith window to the lower crust
Volume Authors:O'Reilly, Suzanne Y., editor; Hensen, B. J.
Source:Lithos (Oslo), 36(3-4), p.185-201; International workshop ; The xenolith window to the lower crust, Sydney, Australia, Oct. 1993, edited by Suzanne Y. O'Reilly and B. J. Hensen. Publisher: Elsevier, Amsterdam, International. ISSN: 0024-4937
Publication Date:1995
Note:In English. 40 refs.; illus., incl. 1 plate, 4 tables, sketch map
Summary:Alkaline magmas from the late-Cenozoic Marie Byrd Land Volcanic Province, West Antarctica, have entrained lithospheric xenoliths which vary from spinel lherzolites to supracrustal rocks. Lower crustal xenoliths have been collected from the Executive Committee Range (Mounts Hampton in the north and Mound Sidley in the south) in central Marie Byrd Land, and their petrological characteristics together with preliminary geochemical data are discussed here. Granulite xenoliths include matigneous gabbros and norites with varying proportions of clinopyroxene, spinel and either olivine or orthopyroxene. Pyroxenites occur together with granulites, which on the basis of their similar mineral assemblage, texture and composition are considered to be related to the granulites. The composition of xenoliths from Mounts Hampton and Sidely differ (e.g. Mount Sidley xenoliths have Mg 32-80, are relatively LREE enriched and have 87Sr/86Sr of 0.70286 and 143Nd/144Nd of 0.512864-0.512870, whereas Mount Hampton xenoliths have Mg 68-78, are LREE depleted and have 87Sr/86Sr of 0.70420-0.70458 and 143Nd/144 Nd of 0.512771-0.512819), defining a major lateral lower crustal discontinuity beneath the Executive Committee Range. Relict igneous textures and low abundances of incompatible elements indicate that the xenoliths initially formed as cumulates rather than as trapped melts. The xenolith suite differs in composition to the host rocks (Mount Sidley volcanics = 87Sr/86Sr of 0.70300-0.70312 and 143Nd/144 Nd of 0.512814-0.512907) and cannot be co-genetic with them. They are interpreted here to represent the cumulates of mantle melts that evolved by crystal fractionation at lower crustal depths. Abstract Copyright (1995) Elsevier, B.V.
Subjects:Alkaline earth metals; Alkalinity; Cenozoic; Chemical analysis; Chemical composition; Crust; Crystal fractionation; Discontinuities; Genesis; Granulites; Igneous rocks; Inclusions; Isotope ratios; Isotopes; Lower crust; Magmas; Mantle; Melting; Metals; Metamorphic rocks; Mineral assemblages; Nd-144/Nd-143; Neodymium; Peridotites; Petrography; Plutonic rocks; Pyroxenite; Rare earths; Sr-87/Sr-86; Stable isotopes; Strontium; Ultramafics; Upper Cenozoic; Volcanic rocks; Xenoliths; Antarctica; Marie Byrd Land; West Antarctica; Executive Committee Range; Marie Byrd Land volcanic province; Mount Hampton; Mount Sidley
Abstract Numbers:97M/2066
Record ID:1996012210
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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