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The Characteristics and Mechanism of Island‐Arc Volcanism on the Central and Southern Fildes Peninsula, King George Island, Antarctica
Author(s) -
Zhaonai Li,
Xiaohan Liu,
Ruxiang Shang
Publication year - 1992
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.1992.mp5001003.x
Subject(s) - geology , andesite , geochemistry , basalt , dacite , volcanic rock , magma chamber , fractional crystallization (geology) , magma , volcanism , basaltic andesite , volcano , island arc , subduction , igneous rock , paleontology , tectonics
The volcanic rock series on the Fildes Peninsula is the product of the later subduction of the Pacific plate beneath the Antarctic plate. It consists mainly of basalt, basaltic andesite and andesite with minor dacite. Its isotopic ages range from 64.6 ± 1 to 43 ± 2 Ma, belonging to Palaeocene to Eocene. Volcanism in the area may be divided into two phases. The contents of major oxides, rare earth elements (REE) and trace elements in volcanic rocks formed in different phases show regular changes, which are mainly related to the rock associations of these phases. Isotope geochemical studies indicate that the primitive magma in the area originating by partial melting in the upper mantle underwent fractional crystallization and ascended to the high‐level (shallow) magma chamber. Before eruption the primitive basalt‐andesitic magma was subjected to differentiation in the high‐level magma chamber, forming zones of derivative magmas of different compositions. In various phases magma‐conducting faults experienced periodic extension and cut through various derivative magma zones in different parts of the peninsula, leading to the eruption of magmas of different compositions on the surface and the formation of volcanic rock associations of corresponding compositions.