The Ore-Controlling Conditions And Target Prognosis Of Banmiaozi Gold District And Its Peripheryin Huadian City Of Jilin Province

Banmiaozi gold mineralized district and its periphery ore deposit (including Damiaozi,Yunanchaogou,and Caiqiangai mineral deposit, etc) is located eastwardly about 50km to Huadian city of Jilin province, geographical coordinate is E : 127°11′30″-127°21′05″, N: 42°56′00″-43°57′50″.West-east length is 15km,south-north width is 5km,the whole area is 75km2.Since 1958 , through a large amount of geological work ,especially geochemical prospecting and geochemical anomaly investing and verifying etc., medium and small gold mineral deposits have already been found in the district, and more than 40 ore bodies and mineral belts have been delineated. The prospect of ore prospecting is good.The mineralized district lies in the tectonic position of north costae east segment boundary of North China Platform, where eastnorth orientation Huifa river fracture belt and westnorth orientation Huiquanzhan and Qingchaguan-Baishuitan extruding fracture belt convergence lie in the Midwest of Dalazi-Jiapigou northeast arching metallogenic feature belt.The given mineral deposits or ore bodies wall rock horizon is Sandaogou formation in Jiapigou group in the mineralized district ,which is a set of neutral-basic metavolcano-sedimentary rock. The rock type from upper part to downward part is forissite, issitic gneiss, mica-granulite and magnet-quartzite etc,ore mostly located in issitic horizon neighborhood. The average abundance of the element Au in the original rock of Sandaogou formation is 5.0×10-9 ,and Au element abundance in the issite is 29.2×10-9. In the site where issites grow , soil geochemistry anomaly usually concentrates. So issite is the guiding horizon condition in prospecting ore bodids.In addition, the formation and existence of the mineral body are closely related with the lamprophyre,diabase,granite-pegmatite,diorite-porphyrite and granite-porphyry veins on the space . These rock veins are distributed in large areas of monzonitic granite or granodiorite . The type of ores varies with its concomitant veins . Combinations of ores and veins are: the gold-pyrite type ore + diabase; the gold-pyrite type ore + diabase + granite-pegmatite; the gold-pyrite type ore + lamprophyre + granite-pegmatite; the gold-polymetallic type ore + diabase + granite-pegmatite; the gold-polymetallic type ore + diorite-porphyrite + granite-pegmatite,etc. Q type clustering analysis shows that the gold-pyrite ore is related with the diabase,lamprophyre and granite-pegmatite;the gold-polymetallic ore is related with the granite-porphyry and diorite-porphyrite. Those veins are the magma rock conditions under which the ore body forms and remains.The mineral body is subjected to Dalazi-Jiapigou eastnorth zone of fracture.The various shear crack which come from shear action in the ductility- brittleness shear and metamorphous zone are the ore-lodging structures in this mineral deposits,not only control the stretch of the mineralized zone,but also control the form and the prolongation of the ore body;not only aggravate the metamorphism and deformation ,leading to mineralized substance to gather and deposit ,but also supply good structure space for magmatism and metallization .It is important geognosy condition that ductility- brittleness shear and metamorphous zone.The mostly ore type is quartz veinlet that is crushed. lode mostly are lenticular and lenses and minority are vein and. Following the strike and the incline the alteration of lode is complicated shaped with apparent branching and merging ,pinching and swelling, as a whole ,the deepening is greater than the prolong. The ore mineral mainly is natural gold , pyrite, chalcopyrite,and secondly has magnetite, pyrrhotite, siderite and a small amount blends and galena etc.; The ore texture is mostly xenomorphic granular texture,cataclactic texture, spotted structure and secondly is metasomatic relict texture and hypidiomorphic texture etc.; The ore structure has banded structure, netted structure, massive structure and breccia structure etc. country wall alteration type has silicification, carbonation, pyritization, chloritization, secondly has fade action and sericitization etc.. Above-mentioned Internal characteristic and exterior characteristic Constituting this area marked conditions of prospecting ore bodies and mineralized bodies.Geophysical information show that the deposit is located in the negative magnetic anomaly. Above the ore bodies anomaly show high chargeability negative point of intersection, and high charging rate low resistivity, the number of Ms is 10%～50% and the number ofρs is 50～400ΩM . Geochemicaly the deposit or ore body occurs at the high anomaly of ore-forming elements, anomalous elements concentration belt. Anomalous elements are Au—Bi—W—Cu—Cd. The internal anomalous elements are Cu and Cd ,and middle internal anomalous elements are Bi and W, and outer internal anomalous element is Au. The research finds Au and Bi elements have high gathering center , showing it is good district to prospect gold and bismuth deposit or ore body.Through the research above ,it induced and summarized the ore-prospecting information and marks. Its geological information is:①The contact zone neighborhood that is between mesograined and fine-grained plagioclase-granite (TTG rock formation) and plagioclase-issite relic is the good site existing mineralized body ;②The position where the diabase,lamprophyre and granite-pegmatite grow is the good position which the gold-pyrite type ore bodies could exit on; The position where the granite-porphyry and diorite-porphyrite grow is the good position which the gold-polymetallic type ore bodies could exit on;③The various shear crack in the ductility- brittleness shear and metamorphous zone is the good configuration space;④silicification, kaolinization, carbonation and pyritization, chloritization is the marked information near the ore bodies;⑤The telescope abnormity belts including in Au—Bi—W—Cu—Cd are the prospective district, and the oil Au element abnormity zones consist in east-west and"V"are the good marks for prospecting the ore bodies;⑥The lower resistivity and higher polarizability anomaly is the indirect reflect;⑦The superimposed positions including in doughnut structure and east-west lineament are the prospective district prospecting the deposits and ore bodies.Prospecting targets prognosis and ore body location forecast carried on, based on the synthesis prospecting information. It was established: one I grade targets and two II grade target in Damiaozi gold mineral district, one ore body forecast location in Banmiaozi gold mineral district, five ore body forecast locations in Yuanchaogou gold mineral district and three ore body forecast locations in Caiqiangzi gold mineral district.