Lithospheric Xenoliths from the Marie Byrd Land Volcanic Province, West Antarctica

• Main Author: Wysoczanski, Richard J
• Format: Thesis
• Language: unknown
• Published: 1993
• Subjects: Earth Sciences not elsewhere classified; Volcanology; Vulcanology; Antarctica area; Igneous rocks; Crust (geology); School: School of Geography; Environment and Earth Sciences; 049999 Earth Sciences not elsewhere classified; Marsden: 260103 Vulcanology; Marsden: 260102 Igneous and Metamorphic Petrology; Marsden: 260107 Structural Geology; Degree Discipline: Geology; Degree Level: Doctoral; Degree Name: Doctor of Philosophy; Antarctic; Byrd; Executive Committee Range; Hampton; Marie Byrd Land; Marsden; Mount Murphy; Usas Escarpment; Walgreen Coast; West Antarctica; Antarc*; Antarctica; Walgreen coast
• Online Access: https://doi.org/10.26686/wgtn.16958932.v1; https://figshare.com/articles/thesis/Lithospheric_Xenoliths_from_the_Marie_Byrd_Land_Volcanic_Province_West_Antarctica/16958932

Studies of the Earths lithosphere, and particularly the lower crust, have in the past relied on geophysical methods, and on geochemical studies of granulite terrains exposed at the surface. Geophysical studies can not evaluate the compositions to any large extent. Granulite terrains typically represent ancient rather than present day sections, have invariably suffered retrograde metamorphism, and have been affected by fluids during uplift. More recently, studies of lithospheric xenoliths (fragments of the lithosphere brought to the surface by entraining (typically alkaline) melts) have been used to study the composition of, and processes influencing, the lithosphere. Xenoliths have the advantage of representing relatively unaltered and young fragments of the lithosphere, and together with other studies have added much to our understanding of the Earths composition and processes. The study of the lithosphere in Marie Byrd Land (MBL), West Antarctica, is complicated by the difficult access and harsh climate of the region. Geophysical studies are limited, and deep crustal exposures are entirely absent. In an attempt to study the composition and structure of the MBL lithosphere, xenoliths were collected from various volcanic edifices in MBL, including the volcanoes of the Executive Committee Range (ECR), and the USAS Escarpment in central MBL, and Mount Murphy on the Walgreen coast. The xenolith suite consists of peridotites, pyroxenites and granulites, spanning a vertical section from upper mantle to lower crust, that are in pristine condition, due to the arid Antarctic conditions. The peridotite suite from MBL consists of spinel Iherzolites from Mounts Hampton and Cumming in the ECR, the USAS Escarpment, and Mount Murphy. Cr-diopside rich peridotites also occur at Mounts Hampton and Murphy, indicating a more chemically diverse upper mantle in these regions (e.g. Mg# 75-92 in Cr-diopside rich peridotites compared to Mg# 87-92 in spinel Iherzolites). REE contents of the peridotites vary from LREE-depleted (up to ...