中国东南大陆沿海火山带研究的新进展

本文综述了东南大陆沿海火山带研究的主要进展。指出175~75Ma火山活动具有平行火山带与垂直火山带方向的迁移性。确定火山构造类型、总体布局及其与基底构造的关系。就构造意义而言,火山带实质上是断陷盆地带。明确早期175~120(11O)Ma为高钾钙碱性火山岩系列且具向酸性岩系列过渡的特征;晚期120(117)Ma以玄武岩—英安流纹岩双峰式火山岩为特征并向碱性岩系列过渡。酸性岩浆起源于由元古界变质杂岩组成的中下地壳,玄武岩起源于上地幔并经演化。阐明了火山岩系基底变质杂岩时代、性质及江山—绍兴、长乐—南澳、莲花山断裂变质带的性质与意义以及火山带岩浆作用动力学模式与区域成矿作用的总体特征。

NEW PROGRESS IN RESEARCH ON THE VOLCANIC ROCK ZONE ALONG COASTAL MARGIN OF SOUTHEAST CHINA CONTINENT, CIRCUM PACIFIC

This paper reviews the major progress made in the study of volcanic rock zone a-long coastal margin of southeast China continent for the scientific and technological project funded by Ministry of Geology and Mineral Resources from 1986 to 1990. From 175 to 75Ma, the volcanic activities migrate both parallel with and perpendicular to the volcanic zone. The types of volcanic structures, their distribution pattern and the relationship with base structure are defined. In fact, the volcanic rock zone is a fault subsidence basin zone in tectonic sense. The volcanic rocks formed in early stage, from 175-120(117)Ma, are high-K calc-alkali series, with a trend of transition to acid rock series. The late stage, 120(117) Ma, is characterized by bimodal volcanic rock, with a trend of transition to alkaline. The acid magma are derived from middle-low crust composed of proterozoic metamorphic complex, and the basalt originates from upper mantle and undergoes evolution. The ages and properties and significances of faults including Jiangshan-Shaoxing fault, the Changle-Nanao fault and the Lianhuashan fault are also discussed in the paper. Finally the dynamic model of magmatism in this belt and the general character of regional mineralization process are synthetically expounded.