The Study On Ore-Controlling Factors And Metallogenic Prognosis Of Tongkeng Tin Polymetallic Deposit, Dachang,Guangxi

Tongkeng tin polymetallic ore field which is located in west of Dachang ore zone in NanDan, the northwest of Guangxi, is the most large scale one and the most typical mineralization-characteristic one. It consists of the shallow vein-type ore body (large vein type, small vein type zone) and the deep stratoid ore body (No.91、No.92). This paper presents the follow conclusions by the study on geological survey and microelements combined with research on Carbon、Hydrogen、Oxygen isotope.(1) By geological survey in mines, it has been found that there is a SN-strike anticline in the deep region. The anticline is clear in355m and305m midsections. The attitude of its west limb is330～350°∠17～35°while it is60～80°∠16～45°in east limb. The hinge of anticline plunged northward, its dip16～21°.(2) The similar-stratiform orebody totally emerges by "petaloid ambulacra". The ore body which above the405#mesomere, is controlled by plunging crown of the EW anticline. The one, below the405#mesomere, especially the355#and305#mesomere is is controlled by plunging crown of the SN hidden anticline. (3) Based on studying microelements and the discipline of space variation their characteristic specific value and combining the previous data, Both NW Dachang fault and SN trending fracture in Tongkeng-Changpo deposit are ore fluid migration channel and the main ore conducting structure.(4) Based on studying distribution characteristics and the space variation discipline of ore-forming element concentration center in different mesomere orebody, the similar-stratiform orebody pitch by NE.(5) The average value of δ13C‰decreases from0.88�'-0.7�'-6.70�'-7.20by from surrounding rock without alteration, nearby surrounding rock with alteration, skarn zinc-copper ore to TongKeng tin polymetallic ore; the average value of δ18O℃decreases from10.95�'11.70�'15.17�'16.00�'22.58by from Longxianggai granite, skarn-type zinc-copper ore body, tin-polymetallic ore body, nearby surrounding rock with alteration to surrounding rock without alteration. It is a continuous changing process.The δ18OH2O value of tin-polymetallic ore varities from6.3to11, while δD‰value varities from-49.0～-139.0. it indicates that the metallogenic material of tin-polymetallic ore come from magama fluid, some juvenile fluids may added in.(6) According to the ore body was controlled by the SN-strike anticline and the ore body plunged to NE. it is concluded that plunging crown of the deep SN anticline is the best prospecting place is proposed.