کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4731562 1640419 2012 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
U–Pb zircon age, geochemical and Sr–Nd isotopic data as constraints on the petrogenesis and emplacement time of andesites from Gerze, southern Qiangtang Block, northern Tibet
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
U–Pb zircon age, geochemical and Sr–Nd isotopic data as constraints on the petrogenesis and emplacement time of andesites from Gerze, southern Qiangtang Block, northern Tibet
چکیده انگلیسی

Mesozoic post-collisional andesites occur in the Gerze area within the Qiangtang Terrane of northern Tibet, China. Geochronological, geochemical, and whole-rock Sr–Nd isotopic analyses were performed on this suite of volcanic rocks to characterize their petrogenesis. Laser ablation-inductively coupled plasma-mass spectrometry U–Pb zircon analyses yielded consistent ages ranging from 122.4 ± 0.4 Ma to 124.4 ± 0.4 Ma for two andesite samples (JC01 and GZ01). The andesites belong to the alkaline and sub-alkaline magma series in terms of K2O + Na2O contents (4.7–10 wt.%), and belong to the high-K calc-alkaline and calc-alkaline series on the basis of their high K2O contents (1.0–3.3 wt.%). The volcanic rocks are further characterized by the enrichment of light rare earth elements [(La/Yb)N = 7.4–11.5] and large-ion lithophile elements (e.g., Rb), slightly negative Eu anomalies (Eu/Eu* = 0.79–0.94), and negative anomalies in high field strength elements (e.g., Nb, Ta, and Ti) relative to primitive mantle. The samples show slightly elevated (87Sr/86Sr)i values that range from 0.7049 to 0.7057, and low εNd(t) values of −3.4 to 0.7. These results suggest that the rocks were derived from a compositionally heterogeneous mantle source and that their parent magmas are basalt magma. The parent mafic magmas may have undergone fractional crystallization of olivine, pyroxene, hornblende, and to a lesser extent, plagioclase during ascent through the thickened crustal pile, with minor or no crustal contamination, before the finally erupting as andesites.


► U–Pb, chemical and Sr–Nd isotopic analyses are presented for andesite from Gerze.
► U–Pb zircon dating yields consistent ages of 122.4–124.4 Ma for this volcanism.
► Geochemical and isotopic data show that the magmas formed through plate collision.
► The Gerze area parental magmas originated via flux melting in the mantle wedge.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Asian Earth Sciences - Volume 45, 2 February 2012, Pages 150–161
نویسندگان
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