摘要
位于郯庐断裂以东,北纬42°以南的辽东半岛地区,由辽南和辽北地体组成。辽南地体上的早元古代辽河群是区内金的矿源层。韧性剪切带和中生代同熔型花岗岩对金矿床的形成起重要作用。金矿化受辽南地体元古代区域变质作用和中生代构造岩浆活动所控制。主要金矿类型有变质热液型、大气降水热液型和岩浆热液型三种,它们是辽南地体地质发展与太平洋板块活动共同作用的结果。
The Liaodong Peninsula in Northeast China can be divided by the Gaixian-Tongyuanpu-Huanren-Dalizi fault into two terranes, the Liaonan terrane and the Liaobei terrane, which amalgamated between 10.0×10~8a and 17.0×10~8a. The Liaohe Group and the Laoling Group are Proterozoic sedimentary formations which developed in Liaonan and Liaobei terranes respectively. Gold deposits are closely related to Liaohe Group in Liaonan terrane. Consisting of bimodel volcanic rock series in the lower part and in 'black shale' of the upper part, Liaohe Group is a typical rift-type volcanic-sedimentary formation and the primary source bed of gold. The regional metamorphism resulted in the transportation of gold from high-grade inetamorphic facies at the lower part to low-grade inetamorphic facies in the upper part, thus forming the final richer source bed in the Gaixian Formation (primarily 'black shale' formation). The gold content of the final source bed is usually 3～30 times higher than that of the upper crust (1.8×1O^(-9)) proposed by Taylor (1985). The ore-control structures were recognized as ductile shear zones by some typical characteristics such as sheath folds, mylonite and subgrains of quartz. These ductile shear zones formed simultaneously with regional metamorphism. According to such features as petrology, mineralogy, rock chemistry, REE patterns and stable isotope composition, Mesozoic granites (1.46×10~8～2.31× 10~8a) related to the gold deposits in this region are identical with or similar to the syntaxis type granite of South China proposed by Xu Keqin.The formation of gold was commonly controlled by Proterozoic regional metamorphism and Mesozoic tectono-magmatic process. It is recognized that gold deposits belong to three main types, i.e., the metamorphic hydrothermal type, the meteoric hydrothermal type and the magmatic hydrothermal type.
The Mesozoic gold-forming process is very important in Liaodong Peninsula and exists widely in East China. It resulted from the subduction of the Pacific Plate to the Chinese Continental Plate. The gold deposits in Liaodong Peninsula were formed jointly by the geological evolution of the Liaonan terrane and the influence of Pacific Plate subduction.
出处
《矿床地质》
CAS
CSCD
北大核心
1993年第3期231-244,共14页
Mineral Deposits
基金
国家自然科学基金
