钦-杭成矿带南段(广东廉江)南和地区区域地质特征及构造演化分析

A study of the regional geology and tectonic evolution in Nanhe area of Lianjiang County,Guangdong Province,in southern section of Qinzhou Bay-Hangzhou Bay metallogenic belt

南和地区位于钦-杭成矿带南段的广东廉江幅范围内,该地区的地质特征记录了钦-杭结合带南段的构造演化过程。根据对地层沉积建造的统计,发现研究区沉积地层形成的水动力环境主要为滨海相、浅海相和深海相3种海相沉积以及少量河流相与沼泽相沉积。研究区的岩浆活动具有明显的多期多阶段特征,总体可划分为加里东期和燕山期两个大的构造岩浆旋回。从研究区的岩性变化可以得到南和地区的变质作用规律,岩浆的参与程度因迁移距离的增加而降低,导致距离越远的变质作用与岩浆的关系越低,形成了变质程度逐级降低的混合岩→片岩→千枚岩(图幅外)→变质砂岩。上述区域地质特征反映南和地区主体经历了伸展-挤压地质演化过程,也指示了钦-杭成矿带南段与北段、中段具有类似的大地构造演化历史,即整体"两开、三合"历程。

The Nanhe area is located in Lianjiang County, Guangdong Province, southern section of Qinzhou Bay - Hangzhou Bay metallogenic belt （QHMB）, which has recorded the geological evolution of the south section of QHMB. According to the statistics of sedimentary strata, the hydrodynamic environment of stratigraphic forming in the study area were mainly littoral, shallow marine, deep-sea phase, and minor fluvial facies and swamp facies. Obviously, there was multi-stage of magmatic activity in the research area, which could be divided into two large cycles of Caledonian and Mesozoic. Based on the lithologieal change, regional metamorphism law could be summarized as that the participation of magma migration decreased due to distance increasing. Thus, the farther the metamorphism from the intrusive mass, the lesser relationship with the magma, resulting in the formation of a sequence with the metamorphic grade gradually reduced, i. e. , migmatite→schist→ phyllite →metamorphic sandstone.