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南大西洋14.0°S热液区是由我国在大西洋中脊首次发现的热液区,该热液区位于南大西洋中脊与卡蒂诺(Cardno)转换断层相交的离轴内角位置。本文利用透反显微镜和X射线衍射(XRD)方法,对14.0°S热液区的热液硫化物进行了矿物学研究。结果显示,热液硫化物按照矿石构造可分为块状硫化物和烟囱残片两类,块状硫化物包括富铁和富铜硫化物,烟囱残片为富铁硫化物。块状硫化物矿石根据孔隙发育程度的差异,又可分为致密型和多孔硫化物矿石,这种致密程度的差异取决于硅质物质的含量。块状硫化物矿相学特征表明,本区热液活动至少存在3个期次,表层堆积矿石中硅质物质的大量产出很可能与侵入型网脉矿的发育有关。表层堆积矿石贫Zn的特征,指示虽然该区热液具有多期次性,但热液系统内Zn再活化作用不显著,这种特征很可能是由于本区洋壳较好的渗透性导致。
The hydrothermal zone of the southern Atlantic 14.0 ° S is the hydrothermal region first discovered by the mid-ocean ridge of the Mid-Atlantic Ocean in China. The hydrothermal zone is located within the off-axis internal angular position where the mid-Atlantic ridge intersects with the Cardino transition fault. In this paper, the hydrothermal sulphides in 14.0 ° S hydrothermal zone were studied by means of transflective microscopy and X-ray diffraction (XRD). The results show that hydrothermal sulfide can be divided into two types according to the ore structure: massive sulphide and chimney fragments. The massive sulphides include iron-rich and copper-rich sulphides, while the chimney fragments are iron-rich sulphides. According to the differences in the degree of pore development, massive sulphide ores can be divided into dense and porous sulphide ores. The difference in density depends on the content of siliceous material. The characteristics of massive sulfide minerals show that there are at least three periods of hydrothermal activity in this area. The large amount of siliceous material in the surface sedimentary ore is likely to be related to the development of the invaded network veins. The characteristics of depleted Zn in surface-deposited ore indicate that although the hydrothermal fluids in this area are multi-temporal, the reactivation of Zn in the hydrothermal system is not significant, which is probably due to the better permeability of the oceanic crust in this area.