华南与燕山期花岗岩有关的稀土、稀有、有色金属矿床成矿系列

本文所述及的地区在地质构造上属黄汲清先生所划分的华南加里东褶皱带的范围。该区在下古生代时期为冒地槽,志留纪时发生加里东运动,褶皱隆起,结束了地槽阶段。加里东运动之后,此区仍不断经受构造运动,成为比较典型的构造活化区。主要表现为:在海西时期一些地带强烈断陷,堆积了巨厚的沉积物,如湘南、河池—南丹等地区;印支—燕山时

The metallogenetic series of the rare-earth, rare and nonferrous metal deposits related to the Yenshanian granites sin south China

South China used to be a miogeosyncline in early Paleozoic times, The development of geosyncline was closed by the Caledonian folding. Intensive mobiIization of tectonics took place during the indo-Sinian-Yenshanian, especially the Yenshanian movement, when block movement and vigorous granitic magmatism constituted the most striking feature, accompanied by polyphase mineralizations of rare-earth, rare and nonferrous metals, which gave birth to a great abundance of mineral resources. With the development of the Yenshanian movement and the continuous evolution andintrusion of granitic magma, the metallogenic elements and mineralization characteristics varied regularly, forming a metallogenetic series of rare-earth, rare and nonferrous metals deposits (TR, Ta, Nb, Be, W, Sn, Bi, Mo, Cu, Pb, Zn, As, Sb and Hg)associated intrinsically with the hypabyssal acid granites in space, time, and genesis. This metallogenetic series consists from early to late Yenshanian of four magmatic mineralization stages or four subseries. The first subseries, pertainiag to early Yenshanian (160-184 m. y.) and distributed in the uplifted areas of the Caledonian fold basement in southern Jiangxi, western Fujian and northern Guangdong, is characterized mainly by rare-earth, niobium, tantalum, and tungsten mineralizations. The second subseries, which is of early-middle Yensha:nian (121-172rn. y.) and occurs within a late Paleozoic depression covering southern Hunan, northern Guangdong and eastern Guangxi, is represented metallogenically by niobium, tantalum, beryllium, tungsten, tin, lead, zinc, and a subordinate amount of bismuth and molybdenum. The third subseries, being of late Yenshanian (91-107m. y.) and appearing mostly along the peripheral depression within a block in the Hechi-Handan area, northwestern Guangxi, is embellishecl with min.eralizations of cassiterite-sulfides, copper, lead, zinc, antimony, arsenic, mercury and a small amount of tungsten. The fourth subseries, belonging to late Yenshanian and Himalayan (47.6-56.7 m. y.) and observed mainly in huge granitic bodies, is dominated by uianium mineralization controlled by silicified and fractured zones. The biotite granites from all stages of Yenshanian movement are acidic-K2O>Na2O, with some variations in chemical composition with respect to different stages. The granites of the first and second subseries contain 74% SiO2 and 8-8.7% K2O+Na2O while the third subseries has 71-74% SiO2 and 7.1% K2O+Na2O, suggesting an apparent decrease in both the acidity and alkalinity for the third subseries, with a corresponding marked change in mineralization. The metallogenetic series on the whole constitutes the following associations of mineral deposits relative to the ore-bearing granites: (l) the rare-earth deposits of the granite type related to potash feldsparthization in the upper part of the intrusive body; (2) the rare-earth, niobium and tantalum deposits of granite type related to potash feldsparthization and albitization in the upper and the top parts of the intrusive body; (3) the niobium, tantalum, beryllium, tungsten, tin and bismuth deposits in the top part of the intrusive body as well as in, the greisenization and pegmatoidization zones adjacent to the contacts; (4) the tungsten, molybdenum, bismuth, beryllium, copper and zinc deposits of the skarn type in the exo-contact zones in case the country rock consists of carbonates; (5) the tungsten, tin, beryllium, lead, zinc, antimony and arsenic deposits of the pneumato-hydrothermal type in the wolframite-quartz (or feldspar) vein systems or in the stratoid metasomatic zones within or close to the intrusive bodies, (6)the lead, zinc, antimony and arsenic deposits of epi-mesothermal type around the intrusive bodies and the mercury deposits farther away from the intrusive bodies; (7) the uranium deposits in the surrounding granite batholithes. Based on these facts, an ideal metallogenetic model for this: metallo-genetic series is given by the author in the present paper.