【摘要】 陕西马元地区铅锌矿位于扬子地台北缘碑坝隆起东南缘一带。矿化带长大于60 km,宽10～200 m,可分为南、东、北3个铅锌矿化带,已圈出了40多条铅锌矿体。其中南矿化带长大于20 km,宽20～120 m,已圈出了30多条铅锌矿体;东矿化带长大于30 km,宽20～200 m,地表已发现7条铅锌矿体;北矿化带长大于10 km,宽10～100 m。矿体一般长100～2 560 m,厚0．80～10．01 m,锌品位1．05%～10．82%,铅品位0．55%～7．54%。主矿体长2 560 m,厚1．46～32．53 m,平均厚约7．60 m,最厚28．40 m,锌品位1．45%～11．42%,平均4．47%。矿化带地层主体由震旦系灯影组白云岩组成,矿化产于灯影组的砾状白云质角砾岩带中。研究表明,基底岩系可能为成矿元素Pb、Zn的主要来源;原始铅主要来源于壳幔混合的造山带;硫同位素富集重硫,可能主要来源海水硫酸盐;矿石中稀土元素富集,轻稀土分异较明显,而重稀土分异不明显;成矿流体推测为热卤水性质;成矿温度为中低温,具有低压浅成成矿特点;矿床形成的初期应始于震旦纪灯影世晚期。结合成矿地质特征,与国外MVT型铅锌矿对比,初步认为区内铅锌矿成因类型类似于MVT型铅锌矿,但有着明显的差异,人们称之为“台缘型”或“扬子型”铅锌矿。经预测,陕西碑坝—马元、云河—庙坝、阳平关—宽川铺—阜川、司上—镇巴、镇坪及湖北竹溪、神农架、黄陵等地区有较好的找矿前景。更多还原

【Abstract】 The Mayuan lead-zinc mineralization belt is tectonically located on the southeastern marngin of the Beiba rise in the northern Yangtze platform.The belt is over 60km long and 10～200m wide and can be divided into the southern,eastern and northern zones,in which over 40 orebodies have been delineated. The southern Pb-Zn mineralization zone having 30 orebodies is more than 20 km long and 20～120m wide.The eastern zone with 7 orebodies is 30 km in length and 20～200m in width.The northern zone is over 10 km long and 10～100m wide.The length of orebodies in the area generally ranges from 100 m to—2 560m,thickness in between 0.80～10.01m,Zn grade is 1.05%～10.82%,and Pb 0.55% and 7.54%. The major orebody is 2 560 m long,1.46～32.53 m thick (averaging 7.60m) and has 1.45%～11.42% Zn (averaging 4.47%).The mineralization belt mainly occurs in psephitic dolomitic breccias of the Sinian Dengying Formation,which is controlled by stratigraphy and structures.The study indicates that the Pb and Zn ore-forming elements probably come from the basement rocks;The initial Pb isotope could be derived from the crust-mantle mixing in the orogenic belt;sulfur isotope composition is enriched in heavy sulfur that may have come from the seawater sulfate in the synchronous sedimentation;the ore is characterized with REE enrichment,obvious fractionation of LREE and flat-pattern of HREE;ore-forming media is thermal brine fluid;both mineralization temperature and pressure are low;the metallogenic epoch is probably in late Dengying epoch of Sinian period.Integrate the geological characteristics and compare Mayuan lead-zinc mineralization belt with the MVT type Pb-Zn ore deposit abroad,we suggest that the mineralizatine type here is similar to the genesis of the MVT type Pb-Zn ore deposit with some differences. It is expected that favourable prospecting is in the areas of Beiba-Mayuan,Yunhe-Miaoba,Yangpingguan- Kuanchuanpu-Fuchuan,Sishang-Zhenba,Zhenping in Shaanxi province,and Zuxi,Shennongjia and Huanling in Hubei province.更多还原