کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4716486 1638703 2012 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A-type granite belts of two chemical subgroups in central eastern China: Indication of ridge subduction
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
A-type granite belts of two chemical subgroups in central eastern China: Indication of ridge subduction
چکیده انگلیسی

Early Cretaceous A-type granites in the Lower Yangtze River belt, central eastern China, with both A1 and A2 chemical subgroups, formed at 125 ± 2 Ma, after a Cretaceous ridge subduction. Remarkably, A1 and A2 group granites are distributed in three zones, roughly parallel to each other and to a slightly older adakite belt. In general, A1 granites form in intraplate settings, whereas A2 granites near paleo-convergent margins. The alternate distribution of these two subgroup A-type granites is compatible with a proposed Cretaceous ridge subduction in the region. The subduction of a dry and hot spreading ridge may have only released small amount of fluids, so that metasomatism on the overriding lithosphere was undetectable, correspondingly resulted in A1 granites later on. In contrast, wetter and colder oceanic crust away from the spreading ridge was responsible for mantle metasomatism and consequently the formation of A2 granites. Further away from the ridge, the subduction angle was much steeper, and dehydration of the slab had occurred earlier during the subduction, and thus dramatically reduced mantle metasomatism, corresponding to A1 granites again. Both A1 and A2 granites formed within a short period of time due to slab window/rollback, after the ridge subduction. The distribution of the A1 and A2 granites together with the adakite belt may be taken as discrimination indice for ancient ridge subduction.


► A1 granite forms in intraplate settings, whereas A2 granite forms at convergent margins.
► A-type granites in central eastern China are classified into A1 and A2 chemical subgroups.
► Spreading ridge is a major component of the mega engine that initiates and drives plate tectonics.
► Ridge subduction may results in both A1 and A2 types of granites, together with adakitic rocks.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volume 150, 1 October 2012, Pages 26–36
نویسندگان
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