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DOI	10.3390/min10121085
	Identification and Origin of Jurassic (similar to 182 Ma) Zircon Grains from Chromitite within the Peridotite of the Jijal Complex, Kohistan Arc in North Pakistan
	Ding, Xiang-Li; Ding, Lin; Zhang, Li-Yun; Wang, Chao; Yue, Ya-Hui
通讯作者	Ding, XL (通讯作者)
发表日期	2020
EISSN	2075-163X
卷号	10 期号:12
英文摘要	The Jijal ultramafic-mafic complex in Pakistan probably preserves the most complete fragments of the petrological Moho. However, a few studies argue for multiple origins (including petrogenetic speculations and tectonic reconstructions) for different lithologies. One of the main reasons for this dispute is the lack of direct age information of the ultramafic rocks. Zircon grains, despite generally being exotic in ultramafic rocks, can provide significant insights into the petrogenetic process of the host ultramafic rocks. This study reports the first zircon U-Pb age and Lu-Hf and trace element data for zircon grains separated from chromitite lenses within the peridotite, which is commonly considered the lowermost part of the Jijal complex. These zircon grains yield concordant Pb-206/U-238 ages of similar to 182 +/- 3 Ma, which is much older than the late Early Cretaceous age (<120 Ma) of the Jijal complex, and lying above it, the other complexes of the Kohistan paleo-arc. Furthermore, these Jurassic zircon grains present radiogenic epsilon Hf(t) values (+9.7 to +6.0) which are obviously lower than the values for the Cretaceous zircon grains of the Kohistan arc. From integrated analysis of the zircon trace element signatures (e.g., high Th, U, Th/U, and U/Yb ratios) and regional geology, we speculate that these zircon grains came from a 'missing' Early Jurassic arc akin to the Gangdese belt to the east, and entered the mantle by oceanic subduction processes. Although these Jurassic zircon grains cannot actually constrain the formation age of the chromitite as well as the peridotite, it reminds us that some cryptic pre-Cretaceous complexes and geodynamic processes were incorporated in building the oceanic crust of the Jijal intra-oceanic arc, or the mantle section (at least part of it) should probably belong to the Indus ophiolite melange. Further research, particularly chronological studies on mantle (or ultramafic) rocks, as well as detailed geological mapping, should be carried out in the future for solving this issue.
关键词	LHASA TERRANE IMPLICATIONS U-PB TRACE-ELEMENT ISOTOPIC CONSTRAINTS PODIFORM CHROMITITES OROGENIC PERIDOTITE TIBET IMPLICATIONS EARLY SUBDUCTION CRUSTAL SECTION VOLCANIC-ROCKS
英文关键词	Pakistan; zircon U-Pb age and Lu-Hf isotopes; chromite; mantle rock; Jijal complex; Jurassic
语种	英语
WOS研究方向	Geochemistry & Geophysics ; Mineralogy ; Mining & Mineral Processing
WOS类目	Geochemistry & Geophysics ; Mineralogy ; Mining & Mineral Processing
WOS记录号	WOS:000602632000001
来源期刊	MINERALS
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/259684
推荐引用方式 GB/T 7714	Ding, Xiang-Li,Ding, Lin,Zhang, Li-Yun,et al. Identification and Origin of Jurassic (similar to 182 Ma) Zircon Grains from Chromitite within the Peridotite of the Jijal Complex, Kohistan Arc in North Pakistan[J]. 中国科学院青藏高原研究所,2020,10(12).
APA	Ding, Xiang-Li,Ding, Lin,Zhang, Li-Yun,Wang, Chao,&Yue, Ya-Hui.(2020).Identification and Origin of Jurassic (similar to 182 Ma) Zircon Grains from Chromitite within the Peridotite of the Jijal Complex, Kohistan Arc in North Pakistan.MINERALS,10(12).
MLA	Ding, Xiang-Li,et al."Identification and Origin of Jurassic (similar to 182 Ma) Zircon Grains from Chromitite within the Peridotite of the Jijal Complex, Kohistan Arc in North Pakistan".MINERALS 10.12(2020).