Granites of Edward VII Peninsula, Marie Byrd Land: anorogenic magmatism related to Antarctic-New Zealand rifting
Weaver, S.D.; Adams, C.J.; Pankhurst, R.J.; Gibson, I.L.. 1992 Granites of Edward VII Peninsula, Marie Byrd Land: anorogenic magmatism related to Antarctic-New Zealand rifting. Transactions of the Royal Society of Edinburgh: Earth Sciences, 83 (1-2). 281-290. 10.1017/S0263593300007963
Full text not available from this repository. (Request a copy)Abstract/Summary
Syenogranites and monzogranites of Edward VII Peninsula, Marie Byrd Land, represent magmatism associated with continental rifting and the separation of New Zealand from W Antarctica in the mid-Cretaceous. These coarse-grained, leucocratic, subsolvus biotite granites occur as five small plutons cutting Lower Palaeozoic metasediments. Petrographic features include the predominance of microcline perthite over albite, bipyramidal smoky quartz, red-brown biotite and accessory ilmenite, zircon, apatite, monazite and fluorite. Enclaves are absent and miarolitic cavites are rare.The granites are a weakly peraluminous, potassic, and highly fractionated suite with high concentrations of Rb, Nb, Y, HREE and F in the most evolved compositions. REE patterns vary from LREE-enriched (CeN/YbN = 8·4), to flat REE patterns (CeN/YbN = 1·1) with large negative Eu anomalies (Eu/Eu* = 0·02). Initial 87Sr/86Sr ratios are 0·7116-0·7206 and initial εNd values are −5·5 to −7·7. Generalised fractionation trends for the suite are explicable in terms of the modal mineralogy. Monazite crystallisation exerted a predominant control on LREE concentrations.The geochemistry of the Edward VII Peninsula granites suggests an infracrustal I-type source, and regionally available Devonian-Carboniferous I-type granodiorites and tonalites satisfy the isotopic constraints. The granites classify as A-type (preferred term A-subtype) and Within-Plate Granites on standard diagrams, but the least fractionated rocks clearly indicate the I-type, Volcanic Arc Granite geochemical signatures of their inferred crustal sources.
Item Type: | Publication - Article |
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Digital Object Identifier (DOI): | 10.1017/S0263593300007963 |
ISSN: | 0263-5933 |
Additional Keywords: | A-subtype, Cretaceous, fractionation trends, granodiorite-tonalite source, isotopes, I-type, monzogranite, petrogenesis, syenogranite |
NORA Subject Terms: | Earth Sciences |
Date made live: | 25 Jan 2018 11:03 +0 (UTC) |
URI: | https://nora.nerc.ac.uk/id/eprint/519103 |
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