中朝断块区新生代玄武岩与该区上地幔成分特征

中生代时期,西太平洋强烈地喷发了安第斯型钙碱性火山岩,新生代时期,东亚大陆火山岩浆活动转为以玄武岩浆喷发为主,中朝断块区的新生代玄武岩是其中具有代表性的一部分。六十年代至七十年代初,对玄武岩、金伯利岩及其中深源超镁铁质包体所进行的世界规模的研究,扩展了人们对上地幔的认识。

CENOZOIC BASALT IN SINO-KOREA FAULT BLOCK REGION IMPLICATING TO CHEMICAL CHARACTERISTICS OF ITS UPPER MANTLE

Cenozoic basaltic volcanism in Sino-Korea continental fault block region can be divided into two periods: one is the Paleogene basalts(mostly belonging to continental rift-type basalt)which show the features of both E-type and N-type MOEB caused by strongly extensional lithosphere fractures and the other is the Neogene-Quaternary crack-type basalts within the continental fault block. The latter has geochemical characteristics similar to ocean island basalts on mantle plume. The chemical and isotopic heterogeneity of both the Neogene-Quaternary basalts and their ultramafic xenoliths in the Sino-Korea Fault Block region shows that the mantle heterogeneity during the Cenozoic time. It might be caused by selected mantle metasomatism(mainly on some HYG, LREE elements and alkalis)along the active contact zone between the continental and oceanic fault blocks and stronglier developing in the Miocene and the Pliocene. It seems to have some enriched ocean-like mantle beneath the region during the Cenozoic.