| 中国东南部中生代火山岩区域成矿条件 |
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| REGIONAL METALLOGENETIC CONDITIONS OF THE MESOZOIC VOLCANICS IN SOUTH CHINA |
| The regional metallogenetic condition of the volcanics in South China depends firstly upon the characteristics of volcanic basins. Accordingly, three types of volcanic basin have been recognized, i.e., Mesozoic superimposed type (Fig. 1) Paleozoic superimposed type (Fig. 2) and explosive type (Fig. 3). Each of them has its own types of mineral deposits (Table 1). The conditions of development of the volcanic cycle controls the ore-bearing degree of the. volcanic basin, and generally speaking, the better developed volcanic formations are of the better mineralization possibilities (Fig. 4). "The principal lithological (petrological) character"of the basin-the bulk composition of its total volcanics predominates oyer the metallogenic attribute of the basin. When "the principal lithological character"is of intermdiate volcanic rock,the metallogenic attributes of the rocks would be of Fe, V, Au, S, and P; in the case of intermediate-acidic volcanics, the attributes would be of Pb, Zn, Ag, Cu, and Au; and acidic ones, Pb, Zn, W, Mo, and Sn (Table 3). The most favourable ore-forming conditions are provided by the subvolcanic rocks and volcano-intrusive rocks whose principal lithological character is similar to that of the same volcanic basin, and moreover, the best occurrence site for ore bodies is situated at the front position of intrusive rocks (Fig. 6). The fractures, especially the persistently active ones, control not only the formation of volcanic basins and the eruption of volcano, but also metallogenesis. Besides, the derived fractures and two sets of intersecting fractures (Fig. 7) as well as the breccia belt (Fig. 8) are also favourable storage structures for ores. Wall rock alteration may be classified as regional and metallogenic wall rock alterations. The former is only restricted to the alteration of the volcanic rock of the early stage caused by regional volcanic eruption of the late stage, which has nothing to do with ore formation. But the latter is closely connected with metallogenesis, with certain alteration corresponding to certain relevant minerals (Table 5). Moreover, wall rock alteration is of zoning character. The more distinct the zoning of alteration, the better the ores are developed, and the more concentrated the ore bodies are in the intensely altered parts (Fig. 9 and 10). |
| PEI Rong-fu,WU Liang-shi.1987.REGIONAL METALLOGENETIC CONDITIONS OF THE MESOZOIC VOLCANICS IN SOUTH CHINA[J].Acta Geoscientica Sinica,9(2):99-112. |
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