新疆阿尔泰区域矿产特征与古老基底的关系探讨

STUDY ON THE OLD BASEMENT AND ITS RELATION WITH CHARACTERISTICS OF THE REGIONAL MINERAL RESOURCES IN ALTAY XINJIANG

新疆阿尔泰地区矿产存在着明显的东西差异，究共原因是阿尔泰处于三大板块的会聚部位．不同的基底性质有所不同。该地区前寒武系基底主要由元古代克木齐群和富蕴群岩石组成，克木齐群属中下元古代，主要分布于阿尔泰西部和南部．富蕴群属中上元古代．主要分布于阿尔泰东部、东北部。岩石学和岩石化学特征表明，克木齐群更多具有上地幔和下地壳的成分．富蕴群则具有上地壳的成分；稀土元素分配特征和铅同位素特征表明东西部矿床和各自的基底关系密切，后者的差异导致了新疆阿尔泰地区矿产特征的差异。

On the basis of the study on the ore deposits, the differences of the characteristics between different metal deposits are shown in the western and the eastern Altay, Xinjiang. The differences resulted from the various old basements. Based on the evidence of the isotopic traces and chronology, we can consider the basement of the Altay orogenic zone as a Proterozoic product. The Proterozoic can be divided into two suite rocks. The one is Kemuqi group of the early middle Proterozoic which is distributed in the western and the southern Altay. The other is Fuyun group of the middle - late Proterozoic which is distributed in the eastern and the northeastern A1tay. Characteristics of metamorphic petrology and petrochemistry show that Kemuqi group has a high temperature - high pressure metamorphic mineral aggregate, their primary rocks are mainly basic volcanic rocks and magmatic rocks. Fuyun group has a high temperature -low pressure metamorphic mineral aggregate and their primary rocks are sedimentary rocks and acid pyroclastic rocks. The former has a higher SiO2, a lower Al2O3 content and a smoother REE patterns than that of the latter. Therefore, rocks of Kemuqi group have more materials of mantle and the lower crust but that of Fuyun group have more materials of the upper crust showing as an orogenic belt. The main deposits in the western and the eastern A1tay have some features of the basememt respectively. The petrochemistry differences between Kemuqi group and Fuyun group in Xinjiang Altay result in the different characteristics of Au、Cu、Pb、Zn and rare metals between the western and the eastern Altay.