Geochronology and geochemistry of the Hegenshan ophiolitic complex: Implications for late-stage tectonic evolution of the Inner Mongolia-Daxinganling Orogenic Belt, China

doi:10.1016/j.jseaes.2007.11.005

	Geochronology and geochemistry of the Hegenshan ophiolitic complex: Implications for late-stage tectonic evolution of the Inner Mongolia-Daxinganling Orogenic Belt, China
	Miao, Laicheng 1; Fan, Weiming 1; Liu, Dunyl 2; Zhang, Fuqin 1; Shi, Yuruo 2; Guo, Feng 3
刊名	JOURNAL OF ASIAN EARTH SCIENCES
	2008-04-15
卷号	32 期号:5-6 页码:348-370
关键词	ophiolite geochronology geochemistry late paleozoic inner mongolia
ISSN号	1367-9120
DOI	10.1016/j.jseaes.2007.11.005
文献子类	Article
英文摘要	The Hegenshan ophiolite in the Inner Mongolian-Daxinganling Orogenic Belt (IMDOB), northern China, consists of several discontinuous blocks composed dominantly of serpentinized ultramafic rocks with subordinate cumulate gabbros, mafic lavas and dikes, intruded by younger granodiorite dikes. The ultramafic rocks are highly depleted, serpentinized harzburgites with minor dunite, characterized by relative enrichment in large ion lithophile elements (LILE, e.g., Ba and Rb) and light rare earth elements (LREE). They are interpreted to be oceanic mantle that has undergone extensive melt extraction and variable degrees of metasomatism. The cumulate rocks consist mainly of gabbro and troctolite with LREE-depleted chondrite-normalized REE patterns showing significant positive Eu. nomalies. They are enriched in LILE, depleted in Nb, and have high positive epsilon(Nd)(t) (+8 to +11), suggesting derivation from a subduction-modified N-MORB-Hke source. The gabbros and mafic dikes have essentially the same age (295 +/- 15 and 298 +/- 9 Ma, respectively). The mafic dikes have flat to LREE-depleted, chondrite-normalized REE patterns, are depleted in Nb, enriched in LILE and have N-MORB-type Nd isotopic signatures (epsilon(Nd)(t) = +8.1 to +10). The mafic lavas, erupted at 293 +/- 1 Ma, can be divided into two groups; one composed of strongly deformed metabasalts similar in chemical and Nd-Sr isotopic compositions to the mafic dikes, and the other composed of undeformed and unmetamorphosed basalts with oceanic island basalt (OIB)-like trace element signatures and Nd isotopic compositions. The granodiorite dikes, which were intruded at 244 +/- 4 Ma, have LREE-enriched, chondrite-normalized REE patterns with no Eu anomalies. Their abnormally high epsilon(Nd)(t) values (+6.3 to +6.8) and low I-Sr (0.70412 to 0.70450) suggest formation from melts derived from thickened oceanic crust during or shortly after closure of the Paleo-Asian Ocean. The structure, lithology and geochemistry of the Hegenshan ophiolite suggest that it is a Cordilleran-type body formed in a supra-subduction zone (SSZ) environment and amalgamated by collision of several fragments of Paleo-Asian lithosphere. Final emplacement and amalgamation occurred in the latest Permian or earliest Triassic. (C) 2007 Elsevier Ltd. All rights reserved.
WOS关键词	UNDERPLATED BASALTIC CRUST ; MID-ATLANTIC RIDGE ; OCEANIC PLAGIOGRANITES ; SOUTHERN TIBET ; DACITE GENESIS ; ORIGIN ; PETROGENESIS ; MAGMAS ; CONSTRAINTS ; TONALITE
WOS研究方向	Geology
语种	英语
出版者	PERGAMON-ELSEVIER SCIENCE LTD
WOS记录号	WOS:000256265700005
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/69776]
专题	中国科学院地质与地球物理研究所
通讯作者	Miao, Laicheng
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China 2.Chinese Acad Geol Sci, Inst Geol, Beijing SHRIMP Ctr, Beijing 100037, Peoples R China 3.Chinese Acad Sci, Guangzhou Inst Geochem, Guangzhou 510640, Peoples R China
推荐引用方式 GB/T 7714	Miao, Laicheng,Fan, Weiming,Liu, Dunyl,et al. Geochronology and geochemistry of the Hegenshan ophiolitic complex: Implications for late-stage tectonic evolution of the Inner Mongolia-Daxinganling Orogenic Belt, China[J]. JOURNAL OF ASIAN EARTH SCIENCES,2008,32(5-6):348-370.
APA	Miao, Laicheng,Fan, Weiming,Liu, Dunyl,Zhang, Fuqin,Shi, Yuruo,&Guo, Feng.(2008).Geochronology and geochemistry of the Hegenshan ophiolitic complex: Implications for late-stage tectonic evolution of the Inner Mongolia-Daxinganling Orogenic Belt, China.JOURNAL OF ASIAN EARTH SCIENCES,32(5-6),348-370.
MLA	Miao, Laicheng,et al."Geochronology and geochemistry of the Hegenshan ophiolitic complex: Implications for late-stage tectonic evolution of the Inner Mongolia-Daxinganling Orogenic Belt, China".JOURNAL OF ASIAN EARTH SCIENCES 32.5-6(2008):348-370.