中文摘要：

通过对城上复式岩体中黑云母进行详细的岩相学观察和矿物化学成分分析及对黑云母组分的特征及其成岩指示意义的讨论，发现城上花岗岩类中的黑云母均具有富铁贫铝高钛低镁的特征，北部中细粒黑云母花岗闪长岩中的黑云母属镁质黑云母，形成的结晶温度约670℃～710℃，氧逸度10-12.4MPa10-13.2MPa，成岩压力68MPa～234MPa，相应的侵位深度为2．6km～8．9km，属I型花岗岩，源区物质可能为未经风化的火山岩或少量地壳酸性岩浆和地幔基性岩浆的混合产物；南部大斑中粗粒黑云母二长花岗岩中的黑云母属铁质黑云母，形成的结晶温度约648℃～710℃，氧逸度1014.8MPa～10-16.1MPa，成岩压力为265MPa～377MPa，相应的侵位深度为10．0km～14．2km，而中斑中细粒黑云母二长花岗岩中的黑云母属铁叶云母-铁质黑云母，形成的结晶温度约600℃～645℃，氧逸度10-16.6MPa～10-17.6MPa，成岩压力为417MPa～559MPa，相应的侵位深度为15．8km～21．1km，与他共存的热液流体中相较其他更富氟，均为典型的S型花岗岩，源区物质应是较纯的沉积物质。

英文摘要：

The lithological,mineralogical,compositional characteristics and forming conditions of the biotite in Chengshang granite are discussed. Electron microprobe analysis shows that the biotite from Chengshang granite has high Fe and Ti contents but lower A1 and Mg content. The biotite from the northern medium-fine grained biotite granodiorite is magnesia biotite with formation temperature of about 670℃- 710 ℃ ,with oxygen fugacity of about 10-12.4 MPa-10-13.2 MPa. Its diagenesis pressure ranges from 68 MPa to 234 MPa,corresponding to the depth of 2.6 km--8.9 km and belonging to I-type granite. The biotite from medium-coarse grained porphyritic biotite adamellite belongs to ferruginous biotite with the crystallization temperature and oxygen fugacity of about 648℃- 710℃ and 10-14.8 MPa-10-16.1 MPa respectively. Its diagenetic pressure is 265 MPa-377 MPa,corresponding to the depth of 10.0 km-14. 2 km. The biotite from medium-fine grained porphyritic biotite adamellite belongs to siderophyllite-ferruginous biotite with the crystallization temperature and oxygen fugacity of about 600℃-645℃ and 10-16.6 MPa- 10-17.6 MPa respectively. Its diagenetie pressure is 417 MPa-559 MPa, corresponding to the depth of 15.8 km-21.1 km. This type of granite is rich in hydrothermal fluid compared with other granite,characteristic of typical S-type granite. It is considered that the source materials may be relatively pure sedimentary matter.