| 东北地区珍珠岩矿床地质特征及成因探讨 |
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| 引用本文：.1983.Geological features and genesis of the pearlite deposits in northeast China[J].Mineral Deposits,2(3):60~68 |
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| Geological features and genesis of the pearlite deposits in northeast China |
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| Abstract:An investigation into some pearlite deposits in northeast China reveals their striking similarity in geologic features, which can be summarized as follows: (1) All of these deposits were formed in Mesozoic Era, mostly in Late Jurassic and Early. Cretaceous Periods, with certain difference in time exhibited between the deposits in the eastern part and those in the western part. (2) Ore deposits and occurrences, all trending in NNE direction, are spatially controlled by mutually-isolated tenestrial basins governed by Neocathaysian tectonic system. (3) The characteristics of major oxides and petrochemical indexes of pearlite indicate that the magma is of calc-alkaline series: K2O+ Na2O = 5. 88 – 7.14, K2O/Na2O = l. (4) The deposits are related unexceptionally to Mesozoic acid volcanic rocks, pertaining to volcanic-magmatic type. (5) The bottoms of the deposits are predominantly composed of tuff, tuff breccia, vesicular thyolite and thyolite occuning in some places alternatively. (6) Pearlite is often found together with zeolite and bentonite. (7) The ore bodies are chiefly stratoid, banded or lobate in shape. (8) Geomorphologically, they often constitute precipices. The author holds the idea that the generation of pearlite-related magma, most likely under the structural environment of the epeiric island arc type, must have had much to do with the subduction of Kula plate underneath Eurasia. In addition to rapid cooling, the formation of pearlite deposits might be attributed to a "gas-release" process probably in existence previous to their formation. The sudden decrease in pressure are also likely to have played an important part in the process of their formation. |
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