Metallogenic Model And Orebody Target Prediction Of The Haigou Gold Deposit, Jilin Province

Tectonically located at the transitional portion between the North China Craton to thesouth and the Xing-Meng orogenic belt to the north, the Haigou gold deposit is hosted in theintersecting portion of a northeast-trending Liangjiang Fault and a northwest-trending Faultfrom Qingchaguan and Jinyinbie. Main geological units in the Haigou deposit include theMid-Proterozoic Selouhe metamorphic complex, the Hercynian Haigou intrusion consistingmainly of monzonite and monzogranite and varied dykes of diorite, syenite diorite porphyryand andesite of subvolcanic origin. In the mine, NE-NNE, nearly E-W and NWW trendingfaults are well developed, with the nearly E-W trending faults being ore-conductive andNE-NNE trending faults being ore-productive.The Haigou gold deposit consists of dozens of auriferous quartz veins and they can begrouped into28#,38#,43#and33#vein swarms based on the nature of ore-controlling faultsand their occurrence and spatial distribution pattern. The gold mineralization in Haigou golddeposit is mainly quartz vein type, locally is alteration rock type. Most gold veins aredistributed in the NE-NNE trending faults, and only a few of them NS and nearly EWtrending faults. Most of gold lodes are hosted in the Mesozoic monzonite and monzograniteof the Haigou intrusion and a few in the Seluohe group metamorphic rocks. Ore mineralsare mainly pyrite, chalcopyrite, native gold, molybdenite, galena, minor of sphalerite, ganguemineral is quartz, calcite, chlorite and some potassium feldspar and plagioclase. The wall rockalteration developed around gold lodes include potassic alteration, silicification, pyritization,sericitization, chloritization, and carbonation, locally barite, epidotization, tourmalinization,zeolitization and so on.Comprehensive study shows that, the most favorable temperature for the formation ofthe Haigou gold deposit is at220~300℃, and the metallogenic depth is about3~12.3km; theore-forming fluid are mainly mantle-derived and are featured by the characteristic of "highcarbon and low salt", typical features of the orogenic gold deposit. In the late period of goldmineralization the meteoric waters were involved. The formation age of the dykes typical in the Haigou deposit can represent the age of gold mineralization in the area, mostly probablybetween132.4to128Ma, similar to the age of other orogenic gold deposits in the North ChinaPlatform.Based on regional geological background, geological features, deposit research, themodel of the Haigou gold deposit has been set up. The Haigou gold deposit was formed in atransitional period from collisional orogeny to extension The asthenosphere mantle upwellingand related geological and mineralization is the main causes for the formation of the HaigouGold Deposit. Ancient Archean and Proterozoic metamorphic basement rocks provide someore-forming materials and the source of the ore-forming fluid was very complicated: partlyfrom the deep mantle source, partly from magmatic hydrothermal fluid and partly frommeteoric water. Mantle fluid and magmatic hydrothermal fluids rose, extracted ore-formingmaterial from surrounding the channels and came across with the shallow meteoric waters,leading to the precipitation of varied gold-bearing quartz lodes in favorable ore-bearing faultsor portion of faults.The geological and geochemical indicators for searching for deeply seated ore bodytargets at depth are summarized as the followings: ore-controlling faults wide and multiplyoverprinted; the underlying portion of intense phyllic alteration, silicification and carbonateand abundant pyrite; at the sites where gold mineralization and other alteration are seen orwhere basic dykes are common; the head halo element association is abnormally developedand/or apparent element zoning are seen.Based on the summary on the geological characteristics of the Haigou gold deposit, theresearch on the metallogenic model and regularity, and integrated with varies variedstatistical analysis of the primary halo mining samples, we have carried out the ore bodytarget prediction at the deep of the Haigou gold deposit. We suggest that the deep levels of theLode No.28is prospective, and especially in its northeast end. The deep of the Lode No.38isless prospective; though at the present tunnel levels, Lode No.43is less attractive, but it ispotential at deep; Ore targets slightly below the present explorative levels could be mostprobably met in Lode No.33.