华北地台中生代热液成矿的构造环境

本文阐述的是在海西末期自初始欧亚板埠形成后,具有早前寒武结晶基底的华北地台,自中生代开始,便处于古太平洋板块强烈挤压俯冲以及与北面西伯利亚板块,南面华南板是一步挤压俯冲所造成的两大构造应力场和构造环境中。前者所造成的构造线方向主要为ＮＥ和ＮＮＲ走向,并由于古太平洋板块作用于我国东部大陆的Ｆａｒａｌｌｏｎ、Ｋｕｌａ和Ｉａｎａｇｉｓｌ板块都具有左行运动的特征,这就造成华北地台、整个中国东部大陆ＮＥ和Ｎ

THE MESOZOIC TECTONIC SETTING OF NORTH CHINA PLATFORM AND ITS RELATION TO HYDROTHERMAL METALLOGENESIS

The initial Eurasian plate was formed during the Late Hercynian cycle. Its intense interaction with Paleo-Pacific plate(including Farallon, Kula and Izanagi Plates) took place during the Indosinian event and was the kinetic source not only for the extensive metamorphism and ductile shearing, but also for A-type subduction and relevant granitoid formation in the North China Platform, especially along its margin.After the formation of initial Eurasian Plate in the final phase of the Hercynian cycle, North China Platform with its Early Precambrian crystalline basement was situated in an intensely compressive tectonic setting caused by two dominant stress fields related respectively to Paleo-Pacific subduction and further compression and to compression and A-type subduction between that platform and the Siberia plate to the north and the South China Plate to the south. Tectonic line created by the former stress field strikes in NE and NNE directions,along which there are important granitic and metallogenic belts in East China.Mineral deposits,ore fields and belts controlled by this tectonic line show sinistral strike-slip character following the pattern aiong which the components of the Paleo-Pacific,such as Farallon, Kuta and Izanapi, acted on East China continent' The latter stress field is related to intraplate compression in S-N direction and has brought about granitie belts and relevant hydrothermal ore deposits arransed in E-W strike."The remote tectonic effect" caused by the Paleo-Pacific acting on initial Eurasia Plate dies away from the subduction' zone or coast line, so that the predominant NE-and NNE-trending tectonic pattern in the coastal area gives its way to the NWW-and EW-trending pattern westwards.This is demonstrated by the examples from Mesozoic Au,Mo and other hydrothermal mineral deposits and orefields in Jiaobei and Huaxiong Terranes at the east and south margin of North China Platform.