安徽凤凰山岩体岩浆侵位过程的磁性研究

通过对安徽省铜陵地区凤凰山岩体25个采样点302件岩石样品的磁性分析,认为研究区内所得的岩石磁组构能代表岩浆侵位时的流动型磁组构,它受岩浆形成之后的构造活动的影响较小;岩浆侵位过程是准静态过程,岩浆流动性较弱、分异作用和同化混染作用强烈;岩浆侵位过程的早期可能受北北东方向的最大主压应力的控制,后期受西南方向最大主压应力场的控制;凤凰山岩体的西南部(药园山矿床所在地段)是岩体的上盘,北东部(仙人冲矿床所在地)是岩体的下盘,即凤凰山岩体向西南方向倾伏;凤凰山岩体的西南部附近地区(如来龙山等地),可能有与凤凰山岩体侵位同时期形成的小岩株,是找矿的远景区段。

MAGNETIC STUDY OF MAGMATIC EMPLACEMENT PROCESS OF FENGHUANGSHAN ROCK BOTY IN ANHUI PROVINCE

According to magnetic analysis of 302 rock samples from 25 sampling points of Fenghuagshan rock body in Tongling area, Anhui Province, the magnetic fabrics obtaned in the study area can represent flow magnetic fabrics during magmatic emplacement, because they were not considerably influenced by tectonic activity after the formation of magma; the process of magmatic emplacement was a quasi-static process, in which the mobility of magma was rather weak, and the differentiation and assimilation-hybridization were quite strong; the early stage of magmatic emplacement might have been controlled by the NNE-trending maximum principal compressional shear, whereas the late stage was probably conditioned by the southwest maximum principal compressional shear; the southwest part of Fenghuangshan rock body where the Yaoyuanshan ore deposit is located is the hanging wall of the rock body, whereas the northeast part where the Xianrenchong ore deposit is situated is the lying wall of the rock body, suggesting that Fenghuangshan rock body pitches southwestward; in areas adjacent to the southwest part of Fenghuangshan rock body (such as in Lailong Mountain) there might exist small stocks formed in the same period as the emplacement of Fenghuangshan rock body, which are promising areas for ore prospecting.