北京西山青白口──下苇甸一带印支期侵入活动特征

THE INDOSINIAN INTRUSIVE ACTIVE FEATURES IN THE QINGBAIKOU──XIAWEIDIAN REGION OF THE WESTERN HILLS, BEIJING

本文根据青白口─下苇甸一带发育的基性→中性→酸性岩脉（床）的变形与围岩一致；变质作用特点与发育于石炭─二叠系及三叠系双泉组岩石中的变质作用特点相似；在下苇甸穹隆中发育的辉长岩中获得了Ｋ─Ａｒ全岩稀释法年龄２２９Ｍａ，证实这套岩脉（床）是印支期岩浆侵入活动产物，并对其地质特征和岩石地球化学特征进行了讨论。

The following evidences are shown in this paper:The deformation of basic-intermediate-acidic dikes(or sills)in Qingbaikou-Xiaweidian region are developed as same as that of in the country rocks;Their features of metamorphism are similar to the rocks of the Carboniferous-Permian and Shuangquan Formation of Triassic;The gabbro age 229 Ma is obtained from the Xiaweidian Dome by the K -Ar dalution method of whole rock.All of these evidences proved that the set of dikes(or sills) were the product of Indosinian intrusive activity , and their geological features and lithogeochemical features are discussed.