宁芜马山式黄铁矿床的地质特征和成因探讨

马山式黄铁矿是玢岩铁硫矿床早期成矿阶段的产物。矿石矿物成分简单,品位低,规模大,埋藏浅,伴生组分Co、Ni、Ga、Se、Te 等可综合利用。矿体产于宁芜早白垩世大王山组火山隆起构造的爆破角砾岩简附近,分上、中、下3个矿带,分别对应一套特征的蚀变岩蒂。从黄铁矿标型特征、测温数据、硫同位素及Co/Ni 比值等判断,矿床属火山喷气热液成因。形成于宁芜玢岩铁矿主体之前,找矿潜力很大。

GEOLOGICAL CHARACTERISTIC AND GENETIC EXPLORATION OF MASHAN TYPE PYRITE ORE DEPOSIT IN NINGWU AREA

Mashan type pyrite deposits are the products of early metallogenetic epoch of porphyrite Iron-Sulfur ore deposits in Ningwu(Nanjing-Wuhu)area.Generally,they are occurred around the volcanic fractural eruptive-intrusive zone,caused byvolcanic basement fault and controlled by volcanic structures such as volcanic dome,volcanic uplift and cryptoexplosive breccia pipe,etc.Mashan pyrite deposit is located in a volcanic uplift,rounded the south marginof Aoshan volcanic dome,in which the orebodies are mainly controlled bytrachyandesite or boundary surface between it and breccia lava,belonging toDawangshan formation of early cretaceous period each other.The orebodies aregenerally in form of bed-like and lens,and may be divided into upper,middle andlower 3 ore-zones,corresponded to a suit of typical altered rock zone.Now,24 suchore-bodies have been verified,which are generally in length of 160-1 400 m withaverage of 508 m;in width of 150-1 600 m with average of 356 m and in thicknessof 4-111 m with average of 16 m.Their geological characteristics are of simple oremineral component,low-grade,large scale and shallow occurrce.Besides,theyalways associate with elements of Co,Ni,Ga,Se,Te,etc.,which can besynthetically used.Basing on the determination of typical forms,temperature and sulphur isotopicdata and Co/Ni ratios of pyrite ores,the Mashan type pyrite ore deposits mightbelong to volcanic eruption gas-hydrothemal origin.Owing to the wide distribution of natural electronic anomalies over these typeddeposits in Ningwu area,so they should have larger prognosis target.