Geodynamic significance of S-type granites in circum-Pacific orogens

Collins, W.J., and Richards, S.W. (2008) Geodynamic significance of S-type granites in circum-Pacific orogens. Geology (Boulder), 36 (7). pp. 559-562.

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In Phanerozoic circum-Pacific orogenic belts, most "post-collisional" S-type granites and associated high-temperature, low-pressure metamorphic complexes formed during early arc extension. The granites are part of a tripartite association consisting of (1) inboard S-type granite, (2) outboard oceanic arc, and (3) intervening, turbidite-filled backarc basin. S-type granites herald the formation of new outboard oceanic arc and extensional backarc systems, but thickening of a preexisting, sediment-dominated back-arc basin is a prerequisite for their generation. In these environments, S-type plutonism is triggered by renewal of arc magmatism following thickening, when hot basaltic magmas are intruded into the thickened backarc crust once slab retreat is reestablished. With ongoing extension during retreat, the crust becomes progressively thinned, the sedimentary contribution is diminished, and the granites lose their S-type character. Such tripartite associations involving S-type granite are probably diagnostic of repeated slab-retreat episodes, and the Jurassic U.S. cordillera might be an example.

Item ID: 6358
Item Type: Article (Research - C1)
ISSN: 1943-2682
Keywords: s-type granite; subduction retreat; extension; backarc; Tasmanides
Date Deposited: 08 Mar 2010 02:54
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040313 Tectonics @ 50%
04 EARTH SCIENCES > 0403 Geology > 040304 Igneous and Metamorphic Petrology @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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