Zircon geochronology of Xingxingxia quartz dioritic gneisses: Implications for the tectonic evolution and Precambrian basement affinity of Chinese Tianshan orogenic belt

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	Zircon geochronology of Xingxingxia quartz dioritic gneisses: Implications for the tectonic evolution and Precambrian basement affinity of Chinese Tianshan orogenic belt
	He, ZY (He ZhenYu); Zhang, ZM (Zhang ZeMing); Zong, KQ (Zong KeQing); Wang, W (Wang Wei); Yu, F (Yu Fei)
刊名	ACTA PETROLOGICA SINICA
	2012
卷号	28 期号:6 特刊 SI 页码:1857-1874
关键词	Quartz dioritic gneisses Early Carboniferous Mesoproterozoic Xingxingxia Central Tianshan block
ISSN号	1000-0569
英文摘要	The Tianshan orogen is the major component of the Central Asian Orogenic Belt (CAOB). There has been a continued debate on the derivation of the old Precambrian crustal basements and Paleozoic tectonic divisions and evolutions of the orogen. In this paper we present petrological characteristics, zircon U-Pb ages and Hf isotope compositions as well as the whole rock geochemistry of the quartz dioritic gneisses from west of the Xingxingxia Town. Based on the mineral assemblies, their protoliths are speculated to be quartz dioritic. Zircon grains from two collected samples have similar internal structures identified on the cathodoluminescence (CL) images, which is characterized by CL-dark, homogeneous rims surrounding the oscillatory zoning cores with rare inherited inner cores. Zircon U-Pb dating results indicate that their protoliths were formed in Early Paleozoic time at similar to 425Ma, and were metamorphosed during Early Carboniferous at approximately 320 similar to 360Ma. The inherited zircon cores yield a wide age range of ca. 1381 similar to 1743Ma. The crystallization zircons from the protolith show positive and varying epsilon(Hf)(t) values (from 0.9 to 17.8), and the inherited zircon cores give t(DM2) model ages of 1.54Ga to 2.44Ga. The quartz dioritic gneisses are characterized by marked positive Rh, Ba, Th and K anomalies and depletion in Nb, Ta and Ti on the primitive mantle-normalized spider diagrams. Through integration of these new data with the previous results of Precambrian basements, high-grade metamorphic rocks, ophiolitic melanges and igneous rocks from the Tianshan orogen, we suggest that 1) the Precambrian crustal basements in the Tianshan orogen don't have much affinity with the Tarim Block, and are inferred to be formed through a magmatic arc accretionary orogen along the margins of Baltica during the Mesoproterozoic; 2) the eastern segment of Central Tianshan was an active continental margin during the Early Paleozoic, due to the subduction of the South Tianshan Ocean; 3) the closure of the South Tianshan Ocean may be synchronous in its eastern and western segments.
学科主题	前寒武纪地质
WOS关键词	ND ISOTOPIC COMPOSITION ; U-PB AGE ; NW CHINA ; EASTERN TIANSHAN ; SOUTHERN TIANSHAN ; WESTERN TIANSHAN ; CENTRAL-ASIA ; CRUSTAL EVOLUTION ; NORTHERN XINJIANG ; GEODYNAMIC EVOLUTION
WOS研究方向	Geology
语种	中文
出版者	SCIENCE PRESS
WOS记录号	WOS:000305817000011
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39858]
专题	中国地质调查局
作者单位	China Univ Geosci, Fac Earth Sci, Wuhan 430074, Peoples R China
推荐引用方式 GB/T 7714	He, ZY ,Zhang, ZM ,Zong, KQ ,et al. Zircon geochronology of Xingxingxia quartz dioritic gneisses: Implications for the tectonic evolution and Precambrian basement affinity of Chinese Tianshan orogenic belt[J]. ACTA PETROLOGICA SINICA,2012,28(6 特刊 SI):1857-1874.
APA	He, ZY ,Zhang, ZM ,Zong, KQ ,Wang, W ,&Yu, F .(2012).Zircon geochronology of Xingxingxia quartz dioritic gneisses: Implications for the tectonic evolution and Precambrian basement affinity of Chinese Tianshan orogenic belt.ACTA PETROLOGICA SINICA,28(6 特刊 SI),1857-1874.
MLA	He, ZY ,et al."Zircon geochronology of Xingxingxia quartz dioritic gneisses: Implications for the tectonic evolution and Precambrian basement affinity of Chinese Tianshan orogenic belt".ACTA PETROLOGICA SINICA 28.6 特刊 SI(2012):1857-1874.