Origin of potassic (C-type) adakite magmas: Experimental and field constraints

Xiao, L. and Clemens, J.D. (2007) Origin of potassic (C-type) adakite magmas: Experimental and field constraints. Lithos, 95(3-4), pp. 399-414. ISSN (print) 0024-4937

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Abstract

The postcollisional, Mesozoic, C-type or high-K adakitic intrusions (K-adakites) of China lack either temporal or spatial association with subduction and have K2O/Na2O around unity. Otherwise, their geochemistry is very similar to ordinary adakites. New experimental data, geological observations and theoretical considerations lead us to suggest that these K-adakites were high-T (> 1050 and probably > 1075 °C), rather hydrous magmas ( 6 wt.% H2O) produced by fluid-absent partial melting of metatonalites, meta-andesites, or possibly potassic metabasalts at pressures exceeding 2 GPa. Their peculiar chemistry is a consequence of both the elevated K2O/Na2O in the protolith and the very high pressure of partial melting. The most likely tectonic setting is one of extreme crustal thickening followed by delamination of the eclogitic keel and partial melting of this continental crustal material at mantle depths, with high mantle heat flow, during orogenic collapse.

Item Type: Article
Additional Information: First author is from Wuhan, China. This work was supported by the National Science Foundation of China [grant numbers 40472037 and 40334037] and the Royal Society, U.K.
Uncontrolled Keywords: adakite, K-rich, granite, petrogenesis, lower continental-crust, slab-derived melts, subduction zones, granitic magmas, isotopic compositions, Mindanao Philippines, quartz eclogite, flat subduction, Eastern China, trace-element
Research Area: Earth systems and environmental sciences
Faculty, School or Research Centre: Faculty of Science (until 2011) > School of Geography, Geology and Environment > Centre for Earth and Environmental Science Research (CEESR)
Depositing User: JOHN CLEMENS
Date Deposited: 02 Apr 2007
Last Modified: 25 Mar 2011 10:12
URI: http://eprints.kingston.ac.uk/id/eprint/373

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