Emplacement age and tectonic implications of the Xilinhot A-type granite in Inner Mongolia, China

被引:125
作者
Shi, GH [1 ]
Miao, LC
Zhang, FQ
Jian, P
Fan, WM
Liu, DY
机构
[1] Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China
[2] Chinese Acad Geol Sci, SHRIMP lab, Inst Geol, Beijing 100037, Peoples R China
来源
CHINESE SCIENCE BULLETIN | 2004年 / 49卷 / 07期
基金
中国国家自然科学基金;
关键词
A-type miarolitic granite; SHRIMP; Xilin Gol; Inner Mongolia;
D O I
10.1360/03wd0436
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
A new rock type of granite, approximate 45 km(2) in area and located about 10 km south of Xilinhot, Inner Mongolia, was found in the Sunitezuoqi (or called Suzuoqi)-Xilinhot tectonic belt and identified as an A-type miarolitic intrusion. The pluton has miarolitic structure and is composed chiefly of perthite, quartz, euhedral albite and potassium feldspar. Various types of textures occur in the pluton, such as perthitie, graphic and myrmekite textures. Only quartz is found in miarolitic cavity. This A-type granite with seagull-shaped REE patterns and obvious negative Eu anomaly (deltaEu = 0.24-0.28) is high in SiO2 (76%-77%), K and Na (Na2O + K2O = 7.75%-8.15%) and low in Ca (CaO = 0.20%-0.22%), Fe and Mg. Both petrographical observations and chemical compositions indicate that it is an A-type granite. Zircon SHRIMP U-Pb analyses indicate that this A-type granite was emplaced at 276 +/- 2 Ma and coeval with the same type of granites in the adjacent areas. Therefore, it suggests that this pluton was likely formed in a post-orogenic extensional setting and probably related to break-off of subducted slabs in Central Asian Orogenic Belt (CAOB), which indicate that the Sunitezuoqi-Xilinhot belt was tectonically evolved into post-orogenic stage since early Permian.
引用
收藏
页码:723 / 729
页数:7
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