| The reworked ore deposit is one type paralleled to sedimentary, magmatic and metamorphic deposit indicated last century by chinese academician Tu Guangchi, a famous ore geologist.At least,the direct mineralization of reworked deposit may include diagenesis of sedimentary rock and faulting.Southwetern Guizhou(SWG) depression is important part of Nanpanjiang-Youjiang sedimentary basin, where many metal deposits exist, e.g., Qinglong antimony deposit associated with diagenesis, Carlin type gold deposits and lead-zinc deposits related with thrust-fold strucure.This doctoral dissertation will analysis dynamics of sedimentary basins and structure geometry of SWG depression, ore forming model of diagenesis-structure at Qinglong Sb deposits, metallogenic regularity of Carlin Au deposits controlled by thrust-fold strucure and metallogenic prognosis. The study bases on geophysical and geological test data, the following new knowledge are acquired:1.Interpreted by seismic lines, the framwork of SWG depression is considered that to be similar to eastern adjacent Nanpanjiang (NP) depression which basin basement are composed of lower paleozoic fold and belongs to South China fold belt, but not Southern Guizhou depression in Yangtze paraplatform.2. SWG depression may be divided into 4 secondary geological units. Three units (Unitâ… ,â…¢,â…£)are characteristics of compressional structures,and one unit (Unitâ…¡)is extensional tectonics on surface. The sections of seismic and MT show us many big faults are positive inversion structure. On maps of gravity, magnetic, electric and seismic prospecting, it is clear that there are many uplifts and sub-depressions on the top level of Dian-Qian-Gui old land in Early Palaeozoic Era which is formed by Yunan Movement, and Changtian-poping uplift is biggest one.3. The original rocks of Dachang Strata are dominated by volcanic rock of explosive facies overlaps upon the Dongwu unconformable contact, and composed of volcanic breccia, tuffaceousvolcanic breccia and tuff. The original rock of Dachang strata may be comparable in SWG depression, even in upper Yangtze area. There are differentiations with K2O>Na2O in Dachang Strata and Na2O>K2O in Emeishan basalt, although they are both belong to basalt series. This may be integrated to come from different source area. The quartz and ankerite alteration occurs in volcanic rock during burial period in Qinglong antimony deposit. 4.Qinglong antimony deposit shows certain ore structure characteristics of diagenesis deposits. The curve of buried history based on apatite fission-track, porosity-depth curve and bed thickness show us rapidly bury from late Permian to Triassic, slowly uplift from Jurassic to middle Eocene, rapidly uplift from late Eocene to now. The main ore-forming age is from the late of middle Triassic to the early of late Triassic,and the ore-forming depth is about 3815m.Ore-forming fluid is characterized by lower REE, higher F- and reducibility. The ratios of Y/Ho, Zr/Hf and Nb/Ta indicated the polyphyleticism of ore-forming fluids. Its W-type tetrad effect is the preference of the fixation of seawater or groundwater REE onto sedimentary rocks.The ore forming setting of Qinglong antimony deposit is believed as multiple half-graben which bases on old uplift. Qingshanzhen fault is interpreted to be main controlled fault by MT data in multiple half-graben system. The diagenesis-structure ore forming model of Qinglong antimony deposit may be described as followings: The explosive land volcanic rock bring about rich Sb element in latest Permian period, the basin metallogenic fluid is driven to Dachang paleo uplift in Triassic period by lithostatic pressure, and then form ore deposit in favorable areas. Dongwu unconformity plays as horizontal pathway, faults with NE trend as a vertical one during ore fluid flowing.5. The seismic lines provide us that ore-controlled structure is characteristics of thrust-fold belt with low angle thrust and unsymmetrical anticline. The thrust detach into coal measures of Longtan Formation in upper Permian, tuff of Dachang Strata and Dongwu unconformity, so the angle of thrust in deep is gentler than in shallow area. Gold deposits may be classified into two kinds, i.e. thrust-controlled and thrust-accompanied ore by their position in thrust-fold belt. The thrust-controlled gold ores occur in fault with vein and low angle strata-dissecting ore bodies. The thrust-accompanied gold ores occurs in interlayer-gliding structures with stratiform-like ore bodies. The thrust-folding is key factor in ore forming, although the paleo uplift has an initially enrichments of gold. Thrust-folding impel basin ore fluid flow along Dongwu unconformity. On other hand, thrust-fold is a trap where ore fluid precipitates. The closure of Paleo-Tethys Ocean in South China began from W parts then to E parts, and formed NW and NE trends thrust-gold structures in later Indosinian epoch.6. Using Geological Stereomapping and IP Sounding Method, our team localized secondary concealed NE trend fault attached to multiple half graben system and got antimony inferred reserves (333) 51 012t by exploration holes and tunnels.
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