东秦岭早古生代古海洋研究

STUDY ON PALEOOCEANOGRAPHY OF THE EARLY PALEOZOIC IN EAST QINLING

本文在岩石地层、古生物、沉积地球化学、流体包裹体研究的基础上，运用古地磁学与构造地质学原理与方法对东秦岭早古生代古海洋的构造演化及其构造古地理格局进行了系统的、定量化研究，从不同的角度论述了古秦岭海的发展与演化。

Based on the study on the lithostratigraphy,paleontology,sedimentary geochem-istry and fluid inclusion,the authors made a systematic and quantitative study on the pa-leooceanographic tectonic evolution and its paleogeographic pattern of the Early Paleo-zoic in East Qinling,applying with the principles and methods of the paleomagnetismand tectonic geology.By means of the synthetical analysis, it is made known that theEast Qinling Sea was an intercontinental sea located between Yangtze platform andNorth China platform under the control of fracture(up to the Ordovician Period,the EastQinling Sea reached the maximum of about 1000kms in width and it was composed of aseries of narrow basins arranging alternately with narrow ridges which struck nearnorthwest by west in the Early Paleozoic,and the northern part of Yangtze platform andOrdos syneclise in North China Platform all belonged to the vast continental sea at thisperiod.The differential tectonic movement between Yangtze platform and North ChinaPlatform caused Qinling Sea(geosyncline)to rifting- open gradually eastwards from EarlyCambrian to late Middle Ordovician (the intercontinental rift was formed in the strongrifting zone,and the geosynclinal uprise was formed in the strong uplifting zone)and toclose westwards in Late Ordovician and then extensive progression and marine regres-sion occurred.The ancient East Qinling Sea, which was wider in the west than in theeast,also went through the variations from narrow to wide and from wide to narrow. The ancient Qinling Sea only remained a narrow sea basin in Ziyang,Ankang and Xun-yang in Shanxi Province up to the Middle Silurian Period.