کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8912727 | 1639572 | 2017 | 64 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Late Archean high-pressure pelitic granulites in the Yinshan Block, North China Craton
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
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چکیده انگلیسی
Ancient high-pressure metamorphism provides constraints for the understanding of Archean tectonic processes. Archean high-pressure metamorphic rocks, however, are rarely preserved in old cratons. Here, we report the newly discovered Archean high-pressure metapelites in the Yinshan Block of the North China Craton. The peak metamorphic stage (M2) is represented by kyanite, garnet, plagioclase, K-feldspar, quartz, rutile and melt. Kyanite was replaced by sillimanite during post-peak (M3) decompression process. Phase equilibria modelling in the MnNCKFMASHT system indicates nearly isothermal decompression with peak conditions of 840-870 °C and >14-11 kbar. Secondary ion mass spectrometry (SIMS) zircon U-Pb dating of leucosome (13XWL35) and monazite U-Pb dating of kyanite-garnet-bearing metapelite (13XWL22) yield similar ages of â¼2520 Ma, which represent the crystallization age of granulite-facies melt. The high-pressure metapelites are enriched in Na2O (1.8-3.0 wt.%), MgO (3.4-5.7 wt.%), Cr (245-421 ppm) and Ni (21.0-91.9 ppm) contents, suggesting that volcanic rocks are probably the main sedimentary provenance. High δ18O(WR) values (up to 12.4â°) and zircon oxygen isotopes (av. 11.4â°) of the metasediment source indicate they have undergone low-temperature alteration. The pressure-temperature-time constraints of this study provide a rare record indicating that surficial sediments have been buried to a depth of >40 km at ca. 2520 Ma in the Yinshan Block. Such crustal thickening, combined with available synchronous magmatism suggests that high-pressure metamorphism was triggered in a late Archean deep arc setting in the Yinshan Block of the North China Craton.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Precambrian Research - Volume 303, December 2017, Pages 251-267
Journal: Precambrian Research - Volume 303, December 2017, Pages 251-267
نویسندگان
Dan Wang, Jinghui Guo,