辽南盖州卧龙泉岩体LA-ICP-MS锆石U-Pb年龄及岩石地球化学特征

LA-ICP-MS ZIRCON U-Pb DATING AND GEOCHEMISTRY OF WOLONGQUAN INTRUSION IN GAIZHOU,SOUTHERN LIAONING PROVINCE

卧龙泉岩体分布于辽宁南部盖州市卧龙泉镇,岩性主要为似斑状黑云母二长花岗岩,岩石锆石206Pb/238U年龄加权平均值为1888.4±5.3 Ma,形成时代为古元古代.卧龙泉似斑状黑云母二长花岗岩地球化学特征显示,Na2O/K2O均值为0.70,属高钾钙碱性系列;里特曼指数σ平均值为2.18,属钙碱系列;铝饱和指数A/CNK平均值为1.16,属过铝型;岩石中稀土元素总量平均值为299.04×10-6,稀土元素配分模式右倾,属具中负铕异常的轻稀土富集、重稀土亏损型,富集大离子亲石元素,亏损高场强元素,具有活动陆缘钙碱性岩系特征,属于同碰撞科迪勒拉型(I型)花岗岩,应与古元古代造山运动造成下地壳加厚熔融有关.

The Wolongquan intrusion,distributed in Wolongquan Town,Gaizhou City of southern Liaoning Province,is lithologically composed of mainly porphyritic biotite monzogranite,with the LA-ICP-MS zircon U-Pb age of1888.4±5.3Ma,forming in the Paleoproterozoic.The geochemical characteristics of the rock body show that the average value of Na2O/K2O is0.70,belonging to high-K calc-alkaline series.The average Rittmann indexσof2.18also indicates calc-alkaline series.The A/CNK ratio is averagely1.16,representing a peraluminous type.The average of total REE content is299.04×10^-6with right-dipping distribution patterns,characterized by moderately negative Eu anomaly with enrichment of LREEs and depletion of HREEs,enriched LILEs and depleted HFSEs,which are the features of active continental margin calc-alkaline series,belonging to the syn-collision I-type Cordillera granite.From the above,it can be inferred that the intrusion should be related to the thickening and melting of the lower crust caused by Paleoproterozoic orogeny.