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	The Luliangshan garnet peridotite massif of the North Qaidam UHPM belt, NW China - a review of its origin and metamorphic evolution
	Song, S. G. ; Niu, Y. L. ; Zhang, L. F. ; Bucher, K.
	2009
关键词	Alaskan-type ultramafic cumulates continental subduction and exhumation garnet peridotite metamorphic evolution North Qaidam BENEATH OCEAN RIDGES ALPE-ARAMI HIGH-PRESSURE COESITE EXSOLUTION KOKCHETAV MASSIF TIBETAN PLATEAU CONTINENTAL COLLISION ABYSSAL PERIDOTITES GARRETT TRANSFORM ULTRAMAFIC ROCKS
英文摘要	The Luliangshan garnet peridotite massif is an ultramafic complex in the North Qaidam UHPM belt, NW China. The strongly layered complex comprising garnet-bearing dunite, garnet-harzburgite, garnet-lherzolite and garnet-pyroxenite and garnet-free dunite, occurs together with eclogite embedded in various continental gneisses. The geological setting, the internal structure, bulk-composition, rare earth elements, isotopic and mineral composition data show that the garnet peridotite derives from a middle Ordovician Alaskan-type layered sub-arc cumulate intrusion of ascending mantle wedge melts. An abyssal peridotite protolith can be excluded. During the Ordovician-Silurian continental collision, thickening and foundering, the Luliangshan peridotite complex was exposed to ultrahigh pressures (UHP) reaching 5.5 GPa possibly > 6 GPa at temperatures of 900 degrees C (perhaps up to 1000 degrees C) corresponding to a depth of similar to 200 km. The extreme pressure conditions have been derived from thermobarometry using mineral compositions of the garnet peridotite assemblages, but they are supported by a wealth of decompression-induced mineral exsolutions in UHP minerals and by diamond inclusion in zircon. The Luliangshan garnet peridotite has experienced four stages of retrograde overprint during exhumation that lasted into the Devonian: (i) decompression-induced unmixing of the UHP minerals; (ii) garnet kelyphitisation; (iii) amphibole overprinting and (iv) serpentinization. Hydrous minerals occurring within peak metamorphic assemblage represent pseudo-inclusions, that is reaction products of reactions related to various stages of decompression and cooling rather than prograde inclusions during porphyroblast growth.; Geology; SCI(E); CPCI-S(ISTP); 11
语种	英语
DOI标识	10.1111/j.1525-1314.2009.00848.x
内容类型	其他
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/155875]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Song, S. G.,Niu, Y. L.,Zhang, L. F.,et al. The Luliangshan garnet peridotite massif of the North Qaidam UHPM belt, NW China - a review of its origin and metamorphic evolution. 2009-01-01.

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