The relationship between the Alxa Block and the North China Plate during;the Early Paleozoic: New information from the Middle Ordovician detrial;zircon ages in the eastern Alxa Block

	The relationship between the Alxa Block and the North China Plate during;the Early Paleozoic: New information from the Middle Ordovician detrial;zircon ages in the eastern Alxa Block
	Zhang Jin 3; Li JinYi ; Liu JianFeng ; Li YanFeng ; Qu JunFeng ; Feng QianWen
刊名	ACTA PETROLOGICA SINICA
	2012
卷号	28 期号:9 页码:2912-2934
关键词	Middle Ordovician Alxa Block detrital zircon Miboshan Formation Helan Aulacogen
ISSN号	022HC
英文摘要	Located between the North China Plate to the east, and the North Qilian Orogenic Belt to the southeast, the eastern Alxa Block is the key region to answer many controversies surrounding the tectonic setting of this region in the Early Paleozoic; among them the debates on the basement composition of the Alxa Block, whether the Alxa Block connected to the North China Plate in the Early Paleozoic, when exactly this event did happen, where the Lower Paleozoic sedimentary rocks along the southwestern Ordos had their provenances, and whether the so-called Helan Aulacogen formed in the Ordovician are the key questions to be solved. Laser-ablation inductively coupled plasma mass spectroscopy U-Pb dating of detrital zircons in two samples from Middle Ordovician sandstones to the west of Helan Shan located in the eastern Alxa Block yields a majority of Pb-206/U-228 ages between 900Ma and 950Ma with peak ages at 916Ma in Sample Alxa-1 and 953Ma in Sample Alxa-2, respectively, a smaller group yields Pb-206/U-238 ages between 494Ma and 623Ma with peak ages at 505Ma and 588Ma in Sample Alxa-1 and 494Ma, 517Ma and 623Ma in Sample Alxa-2, respectively. Two samples all have a minor peak age at ca. 2500Ma with 2517Ma in Alxa-1 and 2552Ma and 2670Ma in Alxa-2. Moreover, there are a few zircons older than 3000Ma. The youngest Pb-206/U-238 ages of the two samples are similar with 451 +/- 8Ma in Alxa-1 and 483 +/- 4Ma in Alxa-2. These zircon U-Pb ages combined with several lines of sedimentary evidence imply that the so-called Helan Aulacogen did not exist in the Ordovician; a peripheral foreland basin related to the North Qilian Orogenic Belt developed instead, the Early Paleozoic detritals mainly came from the North Qilian Arc, the Neoproterozoic detritals mainly came from the Alxa Block, the detrital zircon ages along the whole western Ordos showing that the North Qilian Orogenic Belt ( Arc) came closer to the Alxa Block, and the ocean between them closed gradually, and the basement of the Alxa Block is different from that of North China Plate, the Alxa Block underwent important tectono-magmatic events during the Paleozoic and Neoproterozoic, which have not found in the North China Plate. The Alxa Block may connect with the North China Plate during the Middle Ordovician or after it.
学科主题	构造地质学
WOS关键词	U-PB AGES ; LA-ICP-MS ; TECTONIC IMPLICATIONS ; METAMORPHIC BASEMENT ; SEDIMENTARY BASINS ; SOUTHERN MARGIN ; TIBETAN PLATEAU ; KHONDALITE BELT ; INNER-MONGOLIA ; WESTERN CHINA
WOS研究方向	Geology
语种	中文
WOS记录号	WOS:000309947500020
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39759]
专题	中国地质科学院地质研究所
作者单位	1.Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China. 2.China Ctr Earthquake Disaster Emergency, Beijing 100049, Peoples R China. 3.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Zhang Jin,Li JinYi,Liu JianFeng,et al. The relationship between the Alxa Block and the North China Plate during;the Early Paleozoic: New information from the Middle Ordovician detrial;zircon ages in the eastern Alxa Block[J]. ACTA PETROLOGICA SINICA,2012,28(9):2912-2934.
APA	Zhang Jin,Li JinYi,Liu JianFeng,Li YanFeng,Qu JunFeng,&Feng QianWen.(2012).The relationship between the Alxa Block and the North China Plate during;the Early Paleozoic: New information from the Middle Ordovician detrial;zircon ages in the eastern Alxa Block.ACTA PETROLOGICA SINICA,28(9),2912-2934.
MLA	Zhang Jin,et al."The relationship between the Alxa Block and the North China Plate during;the Early Paleozoic: New information from the Middle Ordovician detrial;zircon ages in the eastern Alxa Block".ACTA PETROLOGICA SINICA 28.9(2012):2912-2934.