Research On The Metallogenic Regularity And Metallogenic Prediction Of Nanjiang Lead-zinc Polymetallic Deposit In Danzhou City, Hainan Province

Nanjiang lead-zinc polymetallic deposit in Danzhou city Hainan province is located in north-central Hainan Island, in department of Lingnan fold belt north edge of Wuzhishan and in the south of Wang wu to Wenjiao deep faults. Combined with actual production, through investigating regional geological background, mining area geological features, and geophysical and geochemical works, we discuss the lead and limonite ore geological features comprehensively and systematically for the first time, demonstrate the ore genesis and metallogenetic rules, propose mineralization model in this area, summarize ore-hunting indicators and forecast the mining and resource prospecting area in this article.The follwing facts have been discovered after careful study:Kong liecun formation(S1k) strata in lower Silurian, Nanhao Formation(Cn—q) strata in lower Carboniferous and Quaternary were exposed in the mining area;the fold structure was not developeded and there is only one monoclinic stratum in the mining area; fractures and joints were developed, and there are seven fractures with strick direction of NNE, NW and EW in the mining area;Hercynian-Indosinian biotite monzogranite was appeared in the south and northwest of the mining area and vein rocks was found here.Lead-zinc ore and limonite body were developed in the mining area. lead-zinc ore was discovered with their occurrence being vein state and lens, and limonite body is composed by four ore blocks which was labeled by ore blockⅠ,ore blockⅡ, ore blockⅢand ore blockⅣ, respectively. The orebody with strick direction of NNE, tilt direction of SE and dip 40(degrees)-70(degrees) extend 800 meter sapproximately.The orebody with their occurrence being vein state and lens was exposed at the surface of the earth and its width is about 10-100 meters.According to analysis of geophysical and geochemical anomalies, one place with abnormal polarization geophysical anomaly, two places with low apparent resistivity geochemical anomaly and three places with geochemical anomaly were found.The above geophysical and geochemical anomalies are identical with the geological works. It is believed by investigating that ore-forming material sources in the mining area are mainly from the stratum and magmatic hydrothermal sources, and lead-zinc and limonite are mainly controled by the strata, fracture and magmatic. The wall rocks of lead-zinc is crystalline limestone which is hosted in Kong Lie Cun Formation strata(S1K) in Silurian. Nanjiang lead-zinc deposit is controlled by F6 fault and the channels for ore solution migration is provided by the NE-trending faults(F6 fault). A series of cracks were developed after the fault formed and the ore-hosting structures are composed by them. Limonite deposit is hosted in the Nanhao Formation (C1n—2) strata in lower carboniferous, and the orebody is controlled by the NNE-trending faults and the channels for ore solution migration is provided by these faults. The Lanyang rock mass is alkali-rich, K-rich, calc-alkaline, and it has high differentiation index and good degree of differentiation, and hydrothermal fluids and materials sources for lead-zinc ore and limonite mineralization are provided by it. According to geological characteristics, combined with geophysical and geochemical anomalies, we speculate preliminarily that lead-zinc deposit is a middle and small hypabyssal metasomatic hydrothermal deposits, which mineralization period is Hercynian Indosinian; The mineralization period of limonite ore is from the Hercynian-Indosinian to the Mesozoic and it is a middle-low temperature hydrothermal type related tometasomstic filling-weathering and leaching deposit.