苏州西部成矿预测的矿物地球化学判别

Minerological and geochemical discrimination of metallogenic prognosis in the Western Suzhou

苏州西部地区岩浆多次活动常伴随多次成矿作用;与印支期石英斑岩有关的以遇里一吴宅铅锌(铜银)矿床为代表;

In quartz porphyry exocontact of Yuli—Wuzhai Pb—Zn (Cu—Ag) deposits, the main mineral association are sphalerite+galena+(Ag,Bi—bearing minerals)in the upper part;chalcopyrite+sphalerite+galena+pyrite+(Ag,Bi—bearing minerals)in the middle part and sphalerite+magetite in the lower part.The ratio of late stage andradite and early stage caswellite was increased in front of metasomatic zone.The flow direction of hydrothermal fluid reflected by the value of Gd/Yb is the same as geochemical anomaly of the deposit.The magnetite with high Ni and sphalerite with high Co,Fe,Cr,and poor Ag is located in the lower part of orebody,In granite exocontact of Tanjiaqiao—Wang mishan Fe,Zn deposit,the mineral associations have three zones,i.e.andradite+diopside,diop- side+andradite and diopside+andradite,Cu,Zn,Fe sulfides+W,Sn,Bi,Mo— bearing minerals+magnetite with poor Sn and high value of Co/Ni ratio+sphaterite with high Fe,In,Co is located in the lower part of orebody. The polymetallic deposits in the area is specialized to magmatic rock.There are some differences between above mentioned two kinds of deposits in the contents of metallic ele- ments,association of ore or mineral,trace elements,magnetite and sphalerite.Additional- ly,the REE partition of skarn minerals are similar to the mineralized host rock and granite. The occurrence of large amount of fluorite reflects that the mineralization is closely related to the granite.