天山的中新生代大地构造性质问题

一般认为,今天所见巍峨的天山是一条海西地槽褶皱带山脉。依著者等实地观察结果,并非如此,而是有其比较复杂的发展史,特别表现在中新生代构造特点上。如所周知,天山地区在古生代时,确曾是个加里东一海西期地槽区。依千沟一库尔勒、三工河上游、石人子沟、祁家沟和乌鲁木齐河上游及玛纳斯河上游等剖面所见,在天山地区,位于元古界片麻岩、片岩夹大理岩之上的,大部分为奥陶纪一石炭纪的含基、中及酸性火山岩的碎屑岩建     

吉林通化地区地洼型花岗岩与成矿的某些特征

Magmatism with its relation to mineralization has long been considered one of the important topics in geotectonics and metallogeny. Based on a rough summary of the geotectonic features of this region, a tentative investigation has been made on Mesozoic granitic rocks as related in time and space to mineralization. This region has experienced three major periods in its geotectonic evolution: the Presinian geosynclinal period, the platform period spanning from Sinian to Middle Triassic, and the diwa period beginning from Late Triassic. In accordance with these periods, three principal tectonic stages with their successive substages have been identified (See Fig. 1). During Late Triassic, the platform collapsed and yielded its place to a new type active region.-the diwa region. According to the present geotectonic features, this paper has divided the region into tectonic areas of various classes, indicating that EW and NE trending structural systems together with their combinations make up the basic tectonic framework. This paper has also described quite in detail some basic characteristics of diwa type granitic xocks and their related endogenic ore deposits, denoting that tectono-magmatic-matallogenic zones were formed spatially under the control of tectonic stages, tectonic areas and tectonic systems. ln the Jingyu geodome series, granitic rocks occur chiefly in diwa; in the Hunjiang diwa series, there exists JianFusong intense tectono-magmatic zone-one of the major endogenic metallogenic zone in this region. Different tectono-magmatic periods have been indicated in this paper with their respective ore types illustrated. The evolution in time and space of granitic rocks have been further demonstrated petrologically and geochemically. Petrochemical data of 164 samples from 35 intrusive bodies reveal that SiO₂, K₂O+Na₂O, Fe₂O₃+FeO+MgO and Fe₂O₃/FeO increase regularly from early to late periods, accompanied by an apparent evolution of rocks and minerals. All this implies that this region bears the basic characteristics of magmatic activities of Cathaysoid diwa in eastern China while has its own regional peculiarity in rock and ore formation-and geotectonic evolution. The earliest intrusion of the Early Yenshanian Period has quite different qualities as compared with intrusions of other periods in such aspects as rock types, petrochemistry and metallogenic specialization, suggesting the probale existence of another independent evolution series of magmatic source. The contents of minor elements reflect the geochemical characteristics and the inherent metallogenic evolution trend in this region. They are direct indicators for ore-bearing parent rocks, as evidenced by the coincidence of the high concentration of these elements with the anomalies of geochemical exploration and of heavy placer mineral prospecting.     

吉林通化地区地洼型花岗岩与成矿的某些特征

岩浆活动与成矿的研究,是大地构造与成矿学中的一个重要课题,它着重探讨构造运动—岩浆活动—成矿作用之间的密切关系。本文根据作者在区内历年野外工作所见,结合有关单位的资料,以地洼学说为指导,在总结区内大地构造基本特征的基础上,对中生代花岗岩类与成矿的时空分布和其特征作些探讨。