A Study On The Characteristic And Origin Of The Antimony Deposit In Danchi Metallogenic Belt,Guangxi

Danchi metallogenic belt is an important nonferrous metal mining industry base of China.It locates in Nandan-Hechi coutries, northwestern of Guangxi province.which in thesouthwestern of Jiangnan old land,northeastern of Youjiang basin. Geologists has researchedfor nearly sixty years and accumulated abundant data on the regional geology,petrology,mineralogy and geochemical etc.Meanwhile,the study on the antimony deposits inthe belt is relatively weaker,So the thesis studied the geologic feature, mineralogy ofantimony and accompanying minerals, geochemistry of REE and isotope in Chashan andJianzhupo deposit, investigated the condition of mineralization and origin in order toestablished the metallogenic model,So the research has certain significance to find out theregularity of the mineralization and guide the prospecting. Achieved the followingunderstanding:The geological characteristic of ores shows that the orebodies in Chashan and Jianzhupoore areas exsit in mudstone and marl of Nabiao group of lower Devonian, Tungsten-antimonyore bodies are filling in the faults which has the distribution along north-east ornorth-south,and the main pattern of metallogenesis is filling.The ore in Chashan mainlyconsists of stibnite and a little marmatite,pyrite, boulangerite, silver tetrahedrite and so on,meanwhile stibnite and jamesonite all exsit in Jianzhupo,acompanyed with marmatite,pyriteand a litlle cassiterite.The consists of ore in the two deposits is quite different. Mineralogyresearch by microexamination, electron probe and X-ray diffraction shows that compositionand unit cell parameter of the same antimony mineral has little difference in different oreareas and levels, approach the theoretical value.Characteristics of the REE in stibnite and jamesonite concentrate the light rare earthelements and Eu has positive anomaly,similar to the sulfosalt minerals of advanced stage ofmineralization in Changpo-Tongkeng, According to the analysis of Liang Ting (2008), thevalue of δEu may indicate the oxidation-reduction condition，By contrast，the content of REEincreases ordering by cassiteriteâ†'senopyriteâ†'jamesoniteâ†'antimony,So it’s consider that theproperties of the fluid and enviorment of mineralizing was changed from cassiterite-sulfidemetallogenic epoch, cassiterite-sulfide-sulfosalt-carbonate metallogenic epoch to W-Sbmetallogenic epoch,and the condition of mineralization changed from reducing environmentinto the oxidation environment,and the antimony deposites formed in the relatively oxidizingenvironment.The research on the origin of metallogenic material suggest that stibium may came from magma and,the study of the sulfur isotope shows that the sulfur isotope from magma andstratum The oxyhydrogen istope research indicates that the ore fluid of the two ore areamainly origined from the magma, but the one in Chashan is from both magmatic water andrain,and the one in Jianhzupo is from magmatic water and metamorphic water.According to the content of trace elements in sphalerite and the analysis of fluidinclusion,the thesis considers that the ore forming temperature of antimony deposits islow-moderate. The fuild which mainly consisted of the magmatic water richly includedore-forming elements, simultaneously, extracted the Metallogenic material in wall rock,andraised along the fracture zones which extend northeast or north-south finally assembled at ashallow depth.Based on the aforementioned results, we established the mineralization model of theantimony deposits in Danchi metallogenic belt.