Cooling history of nested plutons from the Variscan Tichka plutonic complex (Morocco)

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作者：

Lecuyer, Christophe，D Gasquet，P Allemand，Martineau, Francois，I Martinez

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摘要：

Four imbricated mafic to felsic plutons of Variscan age from Morocco have been investigated for their cooling history and geochemical interactions with surrounding continental rocks. Oxygen isotope compositions of whole rocks and minerals have been used to model the cooling rates of these kilometer-sized intrusions. By combining both the knowledge of oxygen-self diffusion data of rock-forming minerals and the determination by IR-spectroscopy of the water content of quartz, the cooling times are estimated ranging from 10 5 to 5×10 5 years in agreement with the shallow emplacement (4–6km depth) of these intrusions into the continental crust. Such fast cooling rates could explain why after assimilation of the various country rocks, heterogeneities of both neodymium and strontium isotope ratios were still preserved. A progressive δ 18 O increase from the mafic to felsic terms of the plutonic suite, which does not excess 1 to 1.5‰, could be explained by the assimilation of metamorphosed pelitic and volcanic rocks that constitute the basement of the Tichka plutonic complex.

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关键词：

Variscan orogeny Crustal growth Cooling rate Oxygen isotopes Tichka massif Morocco

DOI：

10.1007/s00531-017-1463-z

年份：

2017