Petrogenesis of metamorphic rocks within a subduction‐accretion terrane, Signy Island, South Orkney Islands
作者:
B. C. STOREY,
A. W. MENEILLY,
期刊:
Journal of Metamorphic Geology
(WILEY Available online 1985)
卷期:
Volume 3,
issue 1
页码: 21-42
ISSN:0263-4929
年代: 1985
DOI:10.1111/j.1525-1314.1985.tb00303.x
出版商: Blackwell Publishing Ltd
关键词: Key‐words:amphibolite;geochemistry;oceanic intraplate basalt;Scotia metamorphic complex;thermobarometry
数据来源: WILEY
摘要:
AbstractWhole‐rock and mineral analyses of polydeformed mica‐schist, quartzite, marble and amphibolite are presented from Signy Island, South Orkney Islands, part of the Scotia metamorphic complex. Whole‐rock chemistry suggests that the amphibolites are the metamorphosed equivalent of enriched tholeiitic and alkali basalts of an oceanic intraplate basalt series. These, together with limestones and Mn‐rich cherts of an oceanic island assemblage were tectonically mixed with trench or trench inner slope basin sediments in a subduction zone environment. Variation in mineral chemistry indicates an increase in temperature and decrease in pressure during metamorphism; pressures of 8 kbar and temperatures of approximately 545°C were reached during amphibolite facies metamorphism in the latter stages of deformation. These new data provide good evidence to support the previous interpretation of the Scotia metamorphic complex as a subduction
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