西藏冈底斯中部淡色花岗岩锆石U-Pb年龄及其地质意义

U-Pb zircon age of leucogranite in the central Gangdise, Tibet, and its geological significance

对冈底斯花岗岩带中段罗扎岩体淡色花岗岩进行的锆石U-Pb同位素定年和岩石地球化学研究表明,淡色花岗岩锆石U-Pb年龄为133.9Ma±0.9Ma,为早白垩世岩浆活动的产物,岩石属于钙碱性系列,具有强过铝质花岗岩的特征,暗示着本区在早白垩世时期发生过同碰撞事件。这一研究成果为冈底斯地区早白垩世时期发生地壳缩短增厚提供了新证据。

Zircon U-Pb dating and a geochemical study of leucogranite in the Luoza intrusion in the central segment of the Gangdise granite belt, Tibet, indicate that leucogranite has a zircon U-Pb age of 133.9±0.9 Ma and is the product of Early Cretaceous magmatism; the rock belongs to the calc-alkaline series and has the features of strongly peraluminous granite, which suggests that a syn-collision event took place during the Early Cretaceous in the study area. This research result provides new evidence for the crustal shortening and thickening in the Gangdise area during the Early Cretaceous.