内蒙古乌兰浩特地区正长花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义

doi:10.19388/j.zgdzdc.2019.01.08

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Abstract In order to investigate the formation age and tectonic background of the syengranite in Ulanhot region, the authors have studied its zircon U-Pb age and geochemical characteristics. The results show that LA-ICP-MS zircon U-Pb age is (219.7±1.2)Ma, which represents its formation age. The syengranite is rich in silicon and alkali, while the content of aluminum, calcium, magnesium and iron is low. These rocks also have high rare-earth elements content, inapparent fractional distillation between light rare-earth elements and heavy rare-earth elements, and obvious negative abnormal Eu. For the trace elements, these rocks are rich in large ion lithophile elements (Rb and K) and high field strength elements( U, Th, Hf and HREE), while they are poor in Sr, Eu, Ba and Ti. The 10 000×Ga/Al value (3.53 ~ 5.09) is higher than the lower limit value (2.6) of A-type granite, and significantly higher than the average value of the I-type and S-type granites (2.10 and 2.28, respectively). Therefore, the authors concluded that Triassic syenogranite is A-type granite, and the formation environment belongs to post-orogenic lithospheric extension tectonic setting after the closure of Paleo-Asian Ocean.

Key words： Ulanhot zircon U-Pb age rock geochemistry A-type granite extension tectonic setting

Received: 09 May 2018

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	QIU Jinxiong
	YANG Liang
	CHEN Mengchao
	WANG Wenyi
	GAO Yong

Cite this article:

QIU Jinxiong,YANG Liang,CHEN Mengchao, et al. LA-ICP-MS zircon U-Pb age of the syengranite in Ulanhot region of Inner Mongolia, and its geological significance[J]. , 2019, 6(1): 54-60.

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http://www.zgdzdcbjb.com/EN/10.19388/j.zgdzdc.2019.01.08 OR http://www.zgdzdcbjb.com/EN/Y2019/V6/I1/54

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