拉脊山早古生代火山岩盆地开合演化岩石地球化学标志

LITHOGEOCHEMICAL SIGN OF THE OPENING-CLOSING EVOLUTION OF THE VOLCANIC ROCK BASIN IN THE LAJI MOUNTAINS IN EARLY PALAEOZOIC ERA

作者从地球化学的角度，包括对常量元素、微量元素、稀土元素的分析和计算，确定了拉脊山早古生代火山岩盆地演化经历了开→合、开→Ｏ１合、Ｏ２开、Ｏ３合３个开合阶段，并以慢速开裂（０．５ｃｍ／ａ）和快速闭合（８ｃｍ／ａ）为持征，最大开裂规模为２００ｋｍ，认为拉脊山早古生代只发育为小洋盆。

ased on the thought that opening alternated with closing is the most elementary tectonic movement form in course of the lithosphere development,and from the point of view of lithogeochemstry which includes the analysis and caculation of common elements, trace elements and rare earth elements, authors have traced the tectonic evolution history of La n mountains in Early Palaeozoic Ear.It can be divided into three opening-closing stages:opening closing,opening O1-closing and O2 opening-O3 closing,which are characterized by slow opening(0.5 cm/a) and relatively fast closing(8cm/a).The volcanic rock basin attained 200 km in width which indicates that the La n mountains volcanic rock basin in Early Palaeozoic Ear only developed into a small ocean basin.