Petrology and geochemical comparisons

• Main Authors: Mineralogy, Petrology Sofia, Borislav K. Kamenov
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Antarctic Peninsula; West Antarctica; Bransfield Strait; Pacific; Byrd; Greenwich; Livingston Island; Marie Byrd Land; Inott Point; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.482.7098; http://www.geology.bas.bg/mineralogy/gmp_files/gmp41/kamenov.pdf

Abstract. Late Cenozoic mafic alkaline volcanic rocks occur throughout the entire Pacific coast of West Antarctica, including in some of the islands adjacent or within the Bransfield Strait. Amongst them, Livingston Island is the least well-known, particularly in respect to mineralogy, petrology and geochemistry of the sparse manifestations of this type rocks, known as Inott Point Formation. The petrographic and geoche-mical aspects of old and new-discovered outcrops of primitive volcanic rocks are described. The new chemi-cal analyses specify the nomenclature as low-Ti undersaturated olivine basalts mainly, and hawaiites rarely. Comparisons with the trace element characteristics of the similar rocks from the islands Greenwich, Penguin, Deception and Bridgemen revealed common features: high LILE/HFSE ratios (e.g. Ba/Zr 1.4-2.2; Ba/Nb 42-67; Rb/Nb 2.7-4; Ce/Nb 2.5-10; Th/Nb 0.25- 0.90; K/Zr 39-67 etc.). These ratios are opposite to the low LILE/HFSE ratios in the alkalic provinces in Antarctic Peninsula (AP) and in Marie Byrd Land (MBL). The generally low absolute abundances of HFSE in all within and around the Bransfield Strait alkaline basalts and the high Zr/Nb (19-43) and Sr/Nb (>100) ratios are in contrast to such ratios in AP and MBL exposures. Higher degree of melting and variable interaction with the continental lithosphere is probably responsible for the geochemical differences with the alkaline basalts from the other provinces in West Antarctica. The regional geochemical LILE differences between MBL and AP substantiate the