喀喇昆仑—西昆仑地区基性—超基性岩初步考察

A PRELIMINARY STUDY ON THE BASIC-ULTRABASIC ROCKS OF THE KARAKORAM-WESTERN KUNLUN MTS.

本文报道了考察区若干基性-超基性岩体的初步考祭结果。库地岩体属于传统观念的阿尔卑斯型岩体,但与典型蛇绿岩中的变质橄榄岩有所差异;阿卡兹、一些克沟蚀变火山岩可能发育在大洋环境,而晚古生代火山岩大概是在大陆边缘喷出的。本区在新生代时期陆相火山活动相当频繁,其分布规律和岩石特征表明它们与青藏高原的隆升有密切的关系。文中还讨论了昆仑山南侧新生代火山岩喷发的期次。

The preliminary exploratory results about the basic-ultrabasic rocks of the Karakoram and western Kunlun Mts. are reported in this paper. The Kudi ultramafic rock bodies belong to the Alpine-type associations in general, but there are some differences between the Kudi bodies and the typical ophiolitic metamorphic peridotites in petrochemistry. At present, there is insufficient evidence to make a full interpretation of the formation of these bodies. The Middle Proterozoic metamorphic volcanics in Akazi section may have originated in a strongly attenuated continental lithosphere. According to the discriminations of the rare element and REE geochemistry the Upper Proterozoic metamorphic mafic lavas in Yixikgou section probably are formed at a Mid-ocean ridge and present truce oceanic lithosphere. Late Paleozoic volcanics may have erupted in a continental margin area. Relative strong continental volcanic activity existed in Cenozoicera, in which especially the Quaternary continental floor volcanics may be related to the rapid uplifting of the Qinghai-X izang plateau. The occurrences, petrological and geochemical characteristics and erupting stages of the volcanics found in southern Kunlun Mts. have been discussed in detail in the paper.