青海省柴达木北缘小区达肯大坂岩群中—末志留纪侵入岩特征

Intrusive rock characteristics of late Silurian Dakendaban Group Complex in the northern margin district of Qaidam,Qinghai

对青海省柴达木北缘小区达肯大坂岩群中侵入体进行了重新厘定;通过岩石化学及岩石地球化学特征的研究对本区侵入岩的形成环境、成因提出了新的认识;样品微量元素地球化学特征表明,地幔与地壳经不同程度的部分熔融形成花岗岩类,岩浆中有较多的物质来自于地壳,并且含有地幔物质及较老的大陆地壳物质参与到岩浆源区中。稀土元素地球化学特征也显示壳幔混源型岩浆的特点。在南祁连弧盆系与全吉地块继续碰撞背景下形成的岛弧花岗岩,其同位素测年确定了达肯大坂岩群中末志留世时期的岩浆活动事件,为重塑测区地质演化历史提供了新的资料。

This paper redefined intrusions of Dakendaban Group Complex in northern margin district of Qaidam,Qinghai Province.Through study on petrochemical and lithogeochemical characteristics,it puts forward a new understanding of intrusive rock formation environment and causes in the area;Geochemical characteristics of trace elements in the sample shows that the mantle and the crust partially melting form granitoid,there are more substances in the magma from the earth's crust and the magma contains mantle material and older continental crustal matter which participate in the magma source region.The geochemical characteristics of the rare earth elements also show the characteristics of crust mantle mixed source magma.The island arc granite formed under continuing collision background between the southern Qilian arc basin system and the Quanji Block,whose isotopic dating to determine the magma event dakendaban Group belong to the late Silurian period.It provides new information for remolding geological evolution history of the survey area.