泰国西部比洛克(Pilok)锡钨矿区二长花岗岩SHRIMP锆石U-Pb年龄及其地质意义

SHRIMP zircon U-Pb dating of the monzogranites in the Pilok tintungsten mining area, western Thailand, and its geological implications

使用SHRIMP技术测得泰国西部比洛克(Pilok)钨锡矿区的2件二长花岗岩的锆石U-Pb年龄分别为181.7±4.8Ma和175.3±3.3Ma,属于早侏罗世Toarcian期,代表了岩体的侵位年龄。岩石主量和微量元素特征分析表明,比洛克钨锡矿区的二长花岗岩为高钾钙碱性S型过铝质花岗岩。结合区域地质特征,比洛克矿区二长花岗岩应是班公湖—怒江—抹谷洋壳向西侧的腾冲—德林达依陆块俯冲的产物。

The Pilok tin-tungsten mining area is located in the central segment of the west granite belt in Southeast Asia, western Thailand. The precise dating of the granites from the mining area is very important for deep understanding of the crystallization time and tectonic background of this granite belt as well as the regional magmatism-mineralization. The new SHRIMP U-Pb dating results of magmatic zircons in two monzogranite samples from the Pilok tin-tungsten mining area of western Thailand show that their crystallization ages are 181.7±4.8Ma and 175.3±3.3Ma respectively, belonging to the Toarcian period of early Jurassic. Geochemical analyses reveal that the monzogranites are of the high-K calc-alkaline and peraluminous S-type. Combined with regional geological setting, the authors hold that the monzogranites in Pilok mining area should be the products of the Bangonghu-Nujiang-Mogok oceanic crust which subducted beneath the west Tengchong-Tanintharyi continental block.