地质学报2017，Vol.91Issue(11)：2369-2386,18.
Columbia超大陆裂解:来自塔里木克拉通东南缘大红山A型花岗岩的证据
The Cracking of Columbia Supercontinent: Evidence from the Dahongshan A-Type Granite in the Southeastern Tarim Craton
摘要
Abstract
Lithological geochemical and geochrological study was carried out for the Dahongshan granite in the southeastern margin of the Tarim Craton.LA-ICP-MS dating for the zircons from the Dahongshan granite yields a weighted 207pb/206Pb age of 1732.3±7.4Ma,revealing late Paleoproterozoic granites in the Tarim craton.δ18OvsMow values of whole rocks range from 7.6‰ ～ 8.6‰.The granite is rich in Si (SiO2 =71.14％～ 75.85％) and alkali (Na2O+ K2O =8.32％ 9.94％).REE distribution diagram shows an obvious right-dipping seagull-shaped distribution,and strong Eu negative anomaly.Trace element analysis shows that the granite has high contents in Rb (80.9×10-6～129×10-6),Th (17.3×10-6～28.6× 10-6),Y (62×10-6～220×10-6),Ga (28.1×10-6～44.6×10-6) and Nb (52.6×10-6～145×10-6),and low in Sr (12.2×10-6～79.3× 10-6),with high Zr+Nb+Ce+Y and 104 ×Ga/A1,suggesting that the granite has the geochemical feature of A-type granite.In combination with Sc/Nb-Y/Nb diagram,the Dahongshan granite (which belongs to A1-type granite) formed in the low pressure setting.Zircon saturated temperature TZr,calculated from 18 granite samples,ranges from 732.45℃ to 1128.33℃ (averaging 916.3℃),suggesting a high temperature.The Dahongshan granite was the product of partial melting of the lower crustal material due to asthenosphere upwelling or the mantle-derived magma underplating at high temperature and low pressure.The Dahongshan granite,which records not only the whole transformation process from compression to extension but also high thermal event in the Tarim craton after aggregation of Columbia supercontinents,the tracer of the initial stage of large-scale break-up of the Tarim craton.关键词
A型花岗岩/LA-ICP-MS锆石U-Pb年龄/氧同位素/大红山花岗岩/塔里木克拉通东南缘Key words
A-type granites/zircon LA-ICP-MS U-Pb dating/oxygen isotope/Dahongshan granitc/southeastern Tarim Craton引用本文复制引用
王玉玺,王金荣,周小玲,王怀涛,第鹏飞,王晓伟,陈万峰..Columbia超大陆裂解:来自塔里木克拉通东南缘大红山A型花岗岩的证据[J].地质学报,2017,91(11):2369-2386,18.基金项目
本文为甘肃省地质勘查基金项目“甘肃省阿克塞县梁魏南山铌钽矿普查和甘肃省阿克塞县多坝沟金多金属矿普查”和甘肃省矿产资源补偿费项目“甘肃省多坝沟地区1∶5万矿产远景调查”联合资助成果. （）
