北淮阳东段塘湾岩体地球化学特征、锆石U-Pb测年及地质意义

位于安徽北淮阳东段的塘湾岩体为凌家冲杂岩体的重要组成部分，岩石类型为石英闪长岩。该岩体偏铝质、低硅、富碱、高钠，属于高钾钙碱性系列岩石；稀土元素含量中等，（La/Yb）N与HREE/LREE值较高，重稀土相对亏损，Eu弱负异常，属轻稀土富集型；大离子亲石元素Rb、Ba、K、La、Nd富集，高场强元素Nb、Ta、Ti、P亏损。LA-ICP-MS锆石U-Pb测年结果显示塘湾岩体206Pb/238U年龄为（138.0±2.9）Ma，表明岩体为早白垩世岩浆活动的产物。基于区域地质背景及构造环境判别，塘湾石英闪长岩形成于后碰撞伸展构造环境。

Geochemical characteristics, zircon U-Pb dating and geological significance of the Tangwan rock mass in the eastern section of North Huaiyang

The Tangwan rock mass located in the eastern section of the North Huaiyang is an important part of the Lingjiachong complex. Its rock type is quartz diorite. The rock body is aluminum, low silicon, alkali-rich and high sodium. It falls into high-calcium and high-calc alkaline rock. Due to its medium rare earth element content, high (La/Yb)N and HREE/LREE value, heavy rare earth relative loss, Eu weak negative anomaly, it is of a light rare earth enrichment type. Its large ion lithophile elements of Rb, Ba, K, La, Nd are rich, while high field strength elements of Nb, Ta, Ti, P are depleted. The LA-ICP-MS zircon U-Pb dating showed that the 206Pb/238U age of the Tangwan rock mass is (138.0±2.9) Ma, indicating that the rock mass is the product of the Early Cretaceous magmatism. Based on the regional geological background and tectonic setting discrimination, the Tangwan quartz diorite is formed in the post-collisional extensional tectonic setting.