安徽茅坦A型花岗岩研究  

A-type Granites in Maotan. Anhui

作　　者：吴才来[1] 周珣若[2] 黄许陈[3] 张成火[3] 吴多元[3] 黄文明[3] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质大学,北京100083 [3]安徽省地质矿产局321地质队,安徽铜陵244033

出　　处：《地质学报》1998年第3期237-248,共12页Acta Geologica Sinica

基　　金：国家教委博士学科点基金(编号9249101);"八五"国家科技攻关项目(8-901-03-09A);国家自然科学基金

摘　　要：安徽茅坦花岗岩体是由4次侵入的细粒花岗岩、花岗斑岩、中粒花岗岩和粗粒花岗岩组成的复式岩体。各期次岩石具有高硅、富碱、富LREE、Y、Nb、Zr等大离子高电价元素及低Al、Mg、Ca、Ni、Cr、Ti、V的特点,与国内外A型花岗岩相似。岩石中副矿物种类繁多,以含碳硅石、磷钛矿等深源矿物为特征。锆石晶形以正锥面(111)和四方柱面(110)最为发育,与一般Ⅰ型花岗岩有明显的差异。研究表明,该复式岩体为A_2型花岗岩,是在中生代晚期中国东部大陆各微块体之间的走滑拉分向新生代裂谷转变的过渡阶段,沿近东西向的童埠—三里店深断裂呈脉动式上升侵位的。The Maotan granite, situated on the south side of the Tongbu-Shanlidian deep fault in An-hui province, is a compound intrusion composed of fine-grained granite, granite-porphyry, middle-grained granite and coarse-grained granite. Their K-Ar ages are 99. 28 ±1Ma, 97. 36 ±1Ma, 91. 80±1 Ma and 85. 46±1 Ma, respectively. Granitic, quasi-porphyritic, graphic and granophyric textures are recognized in these rocks. Main rock-forming minerals are K-feldspar, quartz, biotite, plagioclase and albite. Quartz phenocrysts are mostly corroded, showing rounded and irregular embayed shapes. Biotite is filled in the interstices of other minerals, and some of it gather to form nodules. From fine-grained granite through granite-porphyry and middle-grained granite to coarse-grained granite the contents of quartz and K-feldspar increase and plagioclase decreases, the contents of SiO2, Na2O and K2O increase and Al2O3, MgO and CaO decrease, ∑REE becomes high, and the Eu anomaly becomes more pronounced. Compared with other types of granites, the Maotan granite is characterized by higher Si, K+Na, LREE, Y, Nb and Zr and lower Al, Mg, Ca, Ni, Cr, Ti and V; so it is similar to A-type granites in the world , especially to those in Gabo and Mumbulla, Austrialia, and Shouzhou and eastern Zhejiang, China. Besides, the rocks contain abundant accessory minerals such as magnetite, fluorite, apatite, zircon, anatase, cyrtolite and hematite with minor moissanite which might be derived from the mantle. The crystal form of zircon is characterized by the development of the tetragonal pyramid (111) and tetragonal prism (110). The mean points and mean TET of the zircon populations are plotted in the mantle field, and the crystalization temperatures of the granites range from 850-900 C , which is similar to the case of the Shuzhou A-type granite and different from the case of I-type granites. On the basis of the above, the Maotan granite belongs to A,-type named by Eby. It may be concluded that the Maotan granite originated by intrusion of highly d

关 键 词：A型花岗岩 地球化学 锆石晶形 岩石成因 花岗岩 

分 类 号：P588.121[天文地球—岩石学]