新疆库地西北一些克沟深海蛇绿质沉积岩岩石学特征及沉积环境

PETROLOGICAL CHARACTERISTIS AND DEPOSITIONAL ENVIRONMENT OF THE PELAGIC OPHIOLITIC SEDIMENTARY ROCKS OF YIXIEKEGOU ON THE NORTHWEST OF KUDE, XINJIANG

在对该岩系野外考察的基础上,通过岩石矿物组合、岩石化学及颗粒分析的研究,找出这套岩系独特的蛇绿质性质,讨论了它们与下部基性火山岩的密切关系;提出这一岩系属于远陆大洋深处的产物,具有远洋深水扇的沉积特点。

A set of variegared volcaniclastic rocks outcropping in Yixiekegou on the northwest of Rude, Xinjiang, is underlied by the middle proterozic basic lavas. All the clastic fragments which constitute the volcaniclastic rocks are derived from the underlying volcanic rocks, so the mineral associations and chemical components of the volcaniclastic rocks are perfectly consistent with those of the underlying volcanic rocks. Obviously they have common characters, implying that they are closely related in origin.By comparing their chemical components, i: is found that the ophiblitic sedimentary rocks are different not only from the normal greywacke but also from the developing island arc oasalt. But there are obvious similarites between the volcaniclastic rocks and the oceanic tholeiite. This shows the sedimentary rocks possess the ophiplidc characters.The various parameters (XM, D, C, M, G) of the grain size analyses reveal that the rhythmic sedimentary cycling of the rocks is clear, the sorting of most samples is comparatively good, but the hydrodynamic is from weaker to weak. The Suhu's distinguishing parameters (<9.84) stand for that this set of sedimentary rocks are products of gravity flow in the range of deep sea fan (turbidite fan).In summary, we can determine that it was deposited in oceanic deep-water (far from the continent).