| 甘肃北山成宣地区二长花岗岩年代学、地球化学特征及其地质意义 |
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| 关键词:monzogranite petrogeochemistry Permian Beishan area |
| 基金项目:甘肃省地勘基金项目“甘肃省敦煌市成宣铜镍矿普查(2024年续作)”(编号: 202401-D01)、甘肃省科技计划项目“甘肃北山地区镍钴成矿预测与找矿方法研究”(编号: 24YFGA014)、甘肃省局创新项目“敦煌地块北缘高尖山岩体-岩相划分与铜镍找矿方法研究”(编号: 2024CX01)；深地国家科技重大专项“荒漠戈壁；高寒草原浅覆盖景观区地球化学勘查新技术”(编号: 2024ZD1002400)和省级基础地质调查项目(编号: 甘财资环[2023] 26号) |
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| Chronological and Geochemical Characteristics of the Chengxuan Monzogranite in the Beishan Area, Gansu Province, and Their Geological Significances |
| To better understand the intrusion age and petrogenesis of monzogranite in the Chengxuan area, Beishan, Gansu, and to further assess the Late Paleozoic tectonic evolution of the Beishan orogenic belt, we conducted a detailed field geological survey and petrographic analyses and examined the LA-ICP-MS zircon U-Pb chronology and petrogeochemical characteristics of monzogranite in this area. The magmatic zircons of the monzogranite in Chengxuan have a weighted average U-Pb age of (278.9±1.2) Ma. The rocks have high SiO? contents (73.51%–76.23%, average 75.03%), total alkali (Na?O+K?O) contents ranging from 7.90% to 8.33% (average 8.13%), and low MgO contents (0.19%–0.63%, average 0.40%), with A/CNK and A/NK values of 0.96–1.02 and 1.04–1.08, respectively, indicating that the monzogranites are peraluminous and belong to a high-potassium calcium-alkaline series. Furthermore, the rocks are enriched in large-ion lithophile elements (Rb, Pb, and K) and incompatible elements (Th and U) but depleted in Ba, Nb, P, and Ti, with a strong negative Eu anomaly. Based on the regional geology, the above characteristics reflect that the Chengxuan granites were the mixing products of crustal and mantle derived magmas and formed under the tectonic setting of post-collisional extension in Early Permian. The post-collisional granites are widely distributed in the study area and that the southern margin of the Beishan Mountains reached a post-collisional evolutionary stage during the Early Permian. |
| YANG Huaiyu,ZHAO Binbin,ZHANG Qinchuan,YANG Jiexuan,WANG Yongqiang,CHEN Jing.2025.Chronological and Geochemical Characteristics of the Chengxuan Monzogranite in the Beishan Area, Gansu Province, and Their Geological Significances[J].Acta Geoscientica Sinica,46(6):1149-1162. |
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