南秦岭古生代沉积岩的地球化学特征及其反映的区域地壳活动性

各类地质体的地球化学特征是地球物质化学运动的记录。深部岩石圈层次卷入地表地质作用的程度反映区域地壳的活动性。古生代南秦岭的区域地壳活动性在早古生代有增强的趋势，晚古生代则又逐渐减弱，以志留纪早期区域地壳活动性最强；空间上以紧邻松潘－甘孜地块的康县－褒河小区和紧邻扬子克拉通北缘的紫阳－竹溪小区构成的近东西向狭长地带区域地壳活动性最强，而且东西两段各有特色。这种区域地壳活动性的时空变化格局可能与新元古代至早古生代松潘－甘孜与扬子联合大陆北部边缘的地壳伸展及早古生代末与华北地台的碰撞拼合有关。

The Regional Crustal Mobility Reflected By the Geochemistry of Paleaozoic Sedimentary Rocks in South Qinling

The geochemistry of a geologic body is the record left by the chemical movement of earth materials. The involvement of deep lithospheric layers into geological processes in the surface is the reflection of regional crustal mobility. The regional crustal mobility of South Qinling during Paleaozoic era tended to become stronger gradually in Early Paleaozoic and weaker again in the Late Paleaozoic being strongest in Early Silurian epoch. Spatially, it got strongest along a nearly EW trending narrow and elongated zone composed of Ziyang-Zhuxi subarea and Kangxian-Baohe subarea closely adjacent to northern edge of Yangtze craton and Songpan--Ganzi massif seperately displaying distinct features in its eastern and western parts. Such a temporal and spatial frame of regional crustal mobility is considered to be related to the crustal extension of the northern margin of the united continent pieced together by Yangtze and Songpan-Ganzi blocks during the period from Neoproterozoic to Early Paleaozoic, and to the convergence and collision with North China craton by the end of Early Paleaozoic.