کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4717156 1638736 2010 14 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Miocene high Sr/Y magmatism, south Tibet: Product of partial melting of subducted Indian continental crust and its tectonic implication
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Miocene high Sr/Y magmatism, south Tibet: Product of partial melting of subducted Indian continental crust and its tectonic implication
چکیده انگلیسی

Post-collisional (26–10 Ma) high Sr/Y and HREE-depleted intrusive rocks occur in an E–W trending belt paralleling the Yarlung–Zangbo suture in south Tibet. Their petrogenesis has been a subject of debate. Here, we present chronological, geochemical and Sr–Nd–Hf isotopic data for two newly discovered large-volume high Sr/Y granitoids (the Pagu granodiorite and the Nanmuqie granite) and three high Sr/Y porphyries intruding the granitoids in the Lhasa terrane. LA-ICP-MS zircon U–Pb dating for the Pagu granodiorite and Nanmuqie granite yielded identical magma crystallization ages of 14.0–14.4 Ma, which is indistinguishable from their associated high Sr/Y porphyries (14.2–14.6 Ma). The granitoid was intruded at middle-crust depth, whereas the porphyry was intruded at upper-crust depth, indicating that the Lhasa terrane has experienced a rapid crustal uplift during the high Sr/Y magma emplacement. Zircon Hf isotopic and whole-rock Sr–Nd isotopic compositions for these granitoids and porphyries suggest that their magmas were dominantly derived from partial melting of crustal materials. The granitoids and porphyries have εHf(t) values overlapping with the mafic granulites in the Himalayan terrane (Indian plate). Their Sr–Nd isotopic compositions show two-endmember mixing between the Himalayan mafic lower crust and the ultrapotassic lavas/the Lhasa lower crust. We suggest that the high Sr/Y magmas in the Lhasa terrane could be derived from partial melting of subducted Indian mafic lower crust with incorporation of the ultrapotassic lava and/or the Lhasa lower crust components. Our study suggests a new model for the high Sr/Y magma generation in the Lhasa terrane and provides a line of geochemical evidence that the Indian continental crust was subducted beneath the southern Lhasa terrane in the early–middle Miocene.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volume 114, Issues 3–4, February 2010, Pages 293–306
نویسندگان
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