中国西部新生代火山活动及其大地构造背景——青藏及邻区火山岩的形成机制

在青藏高原及邻区考察了新生代火山岩 ,并对西藏的 5个火山岩省进行了岩石学和同位素地球化学的综合研究 ,探讨了火山岩的源区特征。西昆仑省喷发了钠质熔岩 ,而其它省均为钾质熔岩类 ;甘肃礼县新生代盆地主要以超镁铁质熔岩为主 ;云南的金沙江北段、腾冲以及滇东南的火山岩类在岩石组合、喷发时代和意义上独具特色。文中以陆内俯冲、岩石圈深部的大地构造演化 ,特别是“壳幔过渡带”的部分熔融 ,对它们的成因及科学意义进行了综合讨论。

CENOZOIC VOLCANIC ACTIVITY AND ITS GEOTECTONIC BACKGROUND IN WEST CHINA--Formative excitation mechanism of volcanic rocks in Qinghai-Xizang and adjacent districts

Cenozoic volcanic rocks in the Qinghai Xizang plateau and its adjacent districts were investigated. On the basis of the scientific investigation, a comprehensive research on the petrology , isotope geochemistry of the five types and the eruption activities of volcanic rocks in Qinghai and Xizang has been carried out. The origins of volcanic rocks are discussed. The melt region of volcanic magma has been subjected to some of the sodic lavas erupted in the west Kunlun Mts, but the potassic lavas were produced only in other regions; the ultramafic lavas were produced in Cenozoic in Lixian County of the Gansu Province. The petrological association,the eruption time and its significance of volcanic rocks in the Jinshajiang , Tengchong and S\|E of the Yunnan Province are extremely important. The genesis and scientific significance of the continental subduction, the tectonic evolution of deep lithosphere, especially partial melting of the "crust\|mantle intermediate zone" are comprehensively discussed.