摘要
通过对我国与Fe,Cu,Mo,W,Sn等主要矿化类型有关的矽卡岩的研究,揭示出不同矿化类型的矽卡岩有其特定的共生单斜辉石-石榴子石矿物对的成分特征、含铁率比值及其变化规律。依据Fe、Al等组分在共生单斜辉石-石榴子石间的分配,估算各种矿化类型矽卡岩形成的氧逸度和酸度条件,从而划分出我国含矿矽卡岩的氧逸度—酸度相。不同矿化类型的矽卡岩共生单斜辉石-石榴子石的成分特征、形成环境及其变化规律密切联系于其成矿母岩特征、成因类型和成岩条件。
Studies of skarns related to Fe, Cu, Mo, W and Sn mineralizations show that the paragenetic clinopyroxene-garnet pairs in skarns of different mineralization types each have their specific composition and ferriferous ratios. In the direction of Fe-Cu-Mo-W-Sn, the diopside-andradite pair in skarn grades progressively into hedenbergite-grossular pair, accompanied by the increase in K_p value. According to mineral assemblages in skarn and composition of paragenetic pyroxene-garnet pair, oxygen fugacities for the formation of various mineralized skarns have been calculated; the formulae for estimating formation acidities of skarns are given on the basis of the composition of paragenetic clinopyroxene-garnet pair(see formulae 19, 20 in the paper proper). In this way, several oxygen fugacity-acidity phases have been distinguished: high oxygen fugacity-low acidity phase, characterized by log fo_2≥-20 and pH≥5 or 5.5; intermediate oxygen fugacity-normal aoidity phase, with log fo_2=-20- -23 and pH=4.5-5.9; low oxygen fugacity-high acidity phase, with log fo_2≤-23 and pH=3.5-5.5. Various mineralized skarns were formed under the condition of log fo_2=-26- -17 and pH=3.5-7.5.The variation trend of oxygen fugacity-acidity during the formation of various types of skarns is discussed; it is also pointed out that deep internal relations in rock-forming and ore-forming geologic-geochemical characteristics and metallogenic physicochemical conditions do exist among magmatism, skarnization, acidic leaching metasomatism and metallization in the process of the formation of skarn deposits.
出处
《矿床地质》
CAS
CSCD
北大核心
1990年第3期195-207,共13页
Mineral Deposits
