【摘要】：獅子崗含礦交代巖位于福建省政和縣城東,屬于鐵山巖體的西南端。鐵山巖體呈北東向展布于東峰-鐵山-張元庵一線,其侵位受北東向政和-大埔斷裂控制,長期以來被認為是中國東南部僅有的兩個印支期正長巖體之一。獅子崗地區(qū)以往也認為是正長巖體,通過詳細的野外地質(zhì)調(diào)查和鉆探工程驗證,發(fā)現(xiàn)該“巖體”具有明顯的銅鉛鋅多金屬礦化,出露隱爆角礫巖和次火山巖,特別是發(fā)育強烈的流體交代蝕變作用(包括青磐巖化、黃鐵絹英巖化、鉀化、硅化等),但缺乏典型的正長巖。因此,獅子崗地區(qū)的賦礦母巖究竟是正長巖、還是隱爆角礫巖或交代蝕變巖之爭。筆者通過對獅子崗不同巖類進行礦物學、地球化學、年代學研究,發(fā)現(xiàn)“巖體”角礫巖、淺色部分(包括鉀化脈及成因存在爭議的正長巖部分)具有類似地球化學、年代學特征,并具有相同的暗色礦物組合,由此可以認為獅子崗地區(qū)出現(xiàn)的巖石類型為交代蝕變巖。“巖體”中淺色部分(包括鉀化脈及成因存在爭議的正長巖部分)所有鉀長石均為微斜長石,其結(jié)構(gòu)溫度為200-370℃之間,低于中酸性巖漿巖的固相線溫度(650℃-925℃),這為該“巖體”的交代成因提供了又一重要的證據(jù)。獅子崗交代巖中不同巖類鋯石具有花崗巖的微量元素特征,鋯石LA-MC-ICP-MS定年集中在250-255Ma之間,顯示獅子崗地區(qū)存在印支期的巖漿活動。獅子崗交代巖鋯石具有變化較大的εHf(t),暗示其形成鋯石的初始巖漿為巖漿混合成因,而其中個別鋯石εHf(t)0,為幔源組分在巖漿的成巖活動過程的貢獻提供了直接證據(jù)。鋯石二階段模式年齡變化較大,范圍為1.20～1.86Ga,顯示中-古元古代地層為其最主要物源區(qū),但其年齡大多數(shù)小于華夏地殼基底變質(zhì)巖,這也為成巖過程中存在幔源組分參與提供了有力的證據(jù)。
[Abstract]:Shizigang ore-bearing metasomatism rock is located in the east of Zhenghe County, Fujian Province, and belongs to the southwest end of Tieshan rock mass. The Tieshan massif is distributed in the Dongfeng-Tieshan-ZhangYuanan line, and its emplacement is controlled by the NE-trending Zhenghe-Dapu fault. It has long been considered to be one of the only two Indosinian syenite bodies in southeastern China. Shizigang area also considered as syenite in the past. Through detailed field geological investigation and drilling engineering verification, it was found that the "rock mass" had obvious Cu, Pb and Zn polymetallic mineralization, and exposed cryptoexplosive breccia and subvolcanic rocks. Especially, strong fluid metasomatism and alteration (including cypress, pyrite sericite, potash, silicification, etc.), but lack of typical syenite. Therefore, whether the host rock in Shizigang area is syenite, cryptoexplosive breccia or metasomatism altered rock. On the basis of mineralogical, geochemical and chronological studies of different rocks in Shizigang, it is found that the breccia of "rock mass", the light-colored part (including potash vein and the disputed syenite part of origin), has similar geochemistry. Because of the chronological characteristics and the same dark mineral assemblage, the rock types in Shizigang area are metasomatism altered rocks. All of the potash feldspar are microplagioclase in the light color part of the "rock mass" (including potash vein and the disputed syenite), whose structure temperature is between 200 鈩，

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