摘要
笔者通过二年多的野外地质调查和室内研究,首次确认了别鲁乌图铜硫多金属矿区火山喷气成因条纹状电气石岩的存在。电气石岩产出地质环境、全岩化学成分和矿物学特征均与世界范围内火山成因硫化物矿床中电气石岩相类似,这一发现不仅有助干人们对矿床形成过程的了解,而且对于在华北地台北缘古生代大陆边缘进一步寻找火山岩型硫化物矿床具有重要意义。
Tourmalinites associated with volcanogenic sulfide deposits have been discovered for the first time in the Bieluwuto area, Nei Mongol Most of the tourmali- nites occur in ore-bearing volcanic-sedimentary rocks as concordant beds 3.0—20m wide and 50—700 m long. Discontinuous irregular lenses of tourmalinites are found in ore bodies distributed along a certain stratigraphic horizon. Tourmalinites associated with Cu-Pb-Zn-Ag ore consist of tourmaline and quartz and minor amount of plagioclase, biotite, chlorite, sericite, calcite, pyrite, pyrrhotite, chalcopyrite, galena and sphalerite. Both of chemical and electron microprobe analyses show that the tourmalines from the bedded tourmalinites are Mg-rich dravite, with FeO/(FeO+MgO) =0.46—0.66 (avg. 0.55), which is the same as the tourmaline in other submarine exhalative deposits. The range of some trace elements is as follows:Cu 10—328ppm, Sr143—142 ppm, Ni 45—15 ppm, Co 40—55 ppm, Zn 25—420 ppm, and Mo 19—16 ppm. The whole-rock composition of the tourmalinites is characterized by high contents of SIO2, Al_2O_3, B_2O_3, MgO and FeO.The geological setting, rock association, sedimentary structures and tourmaline chemistry suggest that tourmalinites were deposited in areas where volcanism resulted in the formation of a high geothermal gradient in abyssal basins. The boronand metal-rich fluids might be submarine hot spring waters which leached a thick pile of volcanic-sedimentary rocks. Studies show that the geochemical and petrological characters of the tourmalinites may serve as a valuable prospecting guide in search for volcanogenic base metal sulfide deposits on the northern margin of the North China Platform.
出处
《地质论评》
CAS
CSCD
北大核心
1990年第5期467-472,共6页
Geological Review
