The Tectonic Environment Of Mesozoic Magmatic Rocks In The Northeast China

The northeast china has experienced the evolution and restriction of paleo pacific and mongolia okhotsk ocean tectonic domain,have formated different stages of magmatic activity.This paper summarizes the mesozoic igneous rocks in northeast of China U-Pb zircon age,rock combination,spatial distribution and geochemical characteristics to explore the northeast China mesozoic tectonic evolution.According to the structure of the 1:500 million asian geological map of the geological map of the division and the zircon U-Pb dating results.The mesozoic magmatic activities in the study area can be divided into 6 stages: Early indosinian stage(252?230 Ma);Late indosinian stage(200?230 Ma);Early yanshan stage early(200?170 Ma);Early yanshan stage late(170?135 Ma);Late yanshan stage early(135?110 Ma);Late yanshan stage late(80?110 Ma).The songnen plain and the east,the early indosinian stage in the volcano arc tectonic environment to the subduction of the paleo pacific continental margin;The late indosinian stage in ancient subduction of the pacific plate piece steepened after collision arc extensional tectonic environment,related to the paleo pacific subduction;Early yanshan stage early paleo pacific subduction related arc extensional tectonic environment;Early yanshan stage late in northeast China affiliated belongs to paleo pacific and mongolia okhotsk ocean tectonic domain of igneous rock,formed in the collision orogenic environment;Late yanshan stage early wandashan terrane formation and paleo pacific strike slip subduction and under the influence of songliao basin in intraplate extensional tectonic environment;Late yanshan stage late the plate stretching and thinning center from the songliao basin to the jiamusi block,the paleo pacific is transformed from oblique strike slip subduction to forward subduction.West of the songnen plain,in the early indosinian stage the paleo asian ocean remains closed,north of China and northeast block group final collision effect;The late indosinian stage the tectonic collision after post orogenic extension;Early stage of yanshan early is active continental margin of mongolia okhotsk ocean southward subduction;Early yanshan stage late,the tectonic environment of extensional tension in the western part of songliao basin due to the oblique direction of the paleo pacific ocean;Late yanshan stage early by paleo pacific subduction,but also is mongolia okhotsk ocean transform to the paleo pacific ocean tectonic domain period.