کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4715725 1638665 2015 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Early Jurassic subduction of the Paleo-Pacific Ocean in NE China: Petrologic and geochemical evidence from the Tumen mafic intrusive complex
ترجمه فارسی عنوان
فروپاشی پیشین ژوراسیک از اقیانوس پالئویی-اقیانوس آرام در شمال غربی چین: شواهد پترولوژی و ژئوشیمیایی از مجتمع مزاحم مافیک تونمن
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی


• The Early Jurassic Tumen mafic intrusion crystallized in a water-saturated magma.
• The parental magma was calc-alkaline with arc-type elemental and isotopic features.
• The N–S-trending magmatic belt in NE China was formed by the westward subduction of the Paleo-Pacific Ocean.

Subduction of the Paleo-Pacific Oceanic Plate is widely considered to have caused extensive Mesozoic magmatism, lithospheric deformation and mineralization in East Asia. However, it is still unclear when this subduction began. Here we report an Early Jurassic (~ 187 Ma) mafic intrusive complex (including olivine norite, gabbro, and diorite) from the Tumen area in NE China. The olivine norite contains a mineral assemblage of olivine, pyroxene, Ca-plagioclase, and hornblende that crystallized in a water-saturated parental magma. The rocks in the complex show variable degrees of plagioclase and ferromagnesian mineral accumulation as reflected by positive Sr and Eu anomalies in primitive mantle-normalized incompatible element patterns. Mass-balance calculations indicate that the parental magma was calc-alkaline with arc-type trace element features (i.e., large ion incompatible and light rare earth element enrichment and Nb–Ta depletion). It also had Sr–Nd–Hf isotopic compositions (87Sr/86Sr(i) = 0.7042 to 0.7044, εNd(t) = + 2.5 to + 3.5 and εHf(t) = + 8.4 to + 10.5) similar to those of modern arc basalts. The parental magma was likely derived from 5 to 20% melting of a mantle wedge metasomatized by an addition of 3–4% hydrous sediment melt from the subducting Paleo-Pacific Oceanic slab. The Tumen mafic intrusive complex, together with other contemporaneous mafic intrusions, I-type granitoids, and felsic lavas, constitutes an Early Jurassic N–S-trending arc magmatic belt that was formed by westward subduction of the Paleo-Pacific Ocean.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volumes 224–225, May 2015, Pages 46–60
نویسندگان
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