松嫩地块及其研究意义

Songnen Massif and its research significance

块体拼贴是东北大地构造格架的基本特征,文中拟从这一构造背景出发,在区域地质研究基础上,选择目前研究相对薄弱的松嫩地块进行讨论。通过地层建造、古生物地理分区、构造-岩浆组合及年代学的资料,揭示松嫩地块与东北其他地质体拼贴的历史。松嫩地块西侧通过嫩江中古生代造山带与兴安褶皱带相接;南侧通过吉中晚古生代造山带和华北地台北缘的西拉木伦早古生代褶皱带相接;东侧通过张广才岭中生代造山带与佳木斯地块拼贴;北侧是蒙古-鄂霍茨克中生代造山带。此外,结合前人关于全球构造格局变迁的研究,讨论了东北地块的来源,并认为松嫩地块东界的张广才岭造山带是古亚洲洋构造域向太平洋构造域转折的标志。

Matching of massifs is one of the basic characteristics of Northeast China geotectonic framework.Upon such a background,the Songnen Massif,which has been relatively poorly researched,is studied in the present work in terms of its regional geology.The history of Songnen Massif matching with adjacent massifs has been explored through stratigraphy,palaeobiogeographic zoning,tectono-magmatic assemblage and isotopic chronology.It is found that the Songnen Massif is connected with Higgan foldbelt through the Middle-Paleozoic Nenjiang orogenic belt on the west,with the Early-Paleozoic Xar-Moren foldbelt in the northern margin of North China Craton through the Late-Paleozoic Central-Jilin orogenic belt on the south,with Jiamusi Massif through the Mesozoic Zhangguangcai Range orogenic belt on the east,and with the Mesozoic Mongolian-Okhotsk orogenic belt on the north.Furthermore,the origins of the massifs in Northeast China are studied in connection with the previous results of the global tectonic evolution history studies,and it is concluded that it is the Zhangguangcai Range that marks the transformation of Paleo-Asian Ocean domain into Circum-Pacific domain.