Emplacement age and tectonic implications of the Xilinhot A-type granite in Inner Mongolia,China
会议名称：《中国科学院地质与地球物理研究所2004学术年会》
会议日期：2004年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
基 金：supported by the National Natural Science Foundation of China (Grant Nos.40234045 and 40302030) the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX 2-104)
关 键 词：A-type miarolitic granite SHRIMP Xilin Gol Inner Mongolia
摘 要：A new rock type of granite,approximate 45 km 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 *** pluton has miarolitic structure and is composed chiefly of perthite,quartz,euhedral albite and potassium *** types of textures occur in the pluton,such as perthitie,graphic and myrmekite textures. Only quartz is found in miarolitic *** A-type granite with seagull-shaped REE patterns and obvious negative Eu anomaly(δEu=0.24—0.28) is high in SiO(76%—77%),K and Na(NaO+KO=7.75%—8.15%) and low in Ca(CaO =0.20%—0.22%),Fe and *** petrographical observations and chemical compositions indicate that it is an A-type *** 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 ***,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.