Wallrock Alteration And Mineralization Of The Bilihe Porphyry Gold-deposit In Inner Mongolia China

Bilihe gold deposit in Inner Mongolia is located in in the southern side of splice subduction zone in the northern margin of North China plate , the ore-body is produced in interacidity volcanic-subvolcanic rock of Jurassic system, mostly presented as lentoid, nervation type, it is strictly controlled by NW faults.Through field investigation, rock appraisal and fluid inclusions, REE and trace elements research, altered petrological and geochemical characteristics were studied systematically, some conclusions about Bilihe gold deposit were drawed out: the main wall-rock alteration types are quartzitification, kaolinitization, pyrization, sercitization, chloritization , kaolinitization and carbonatization. Gold mineralization is closely related to quartzitification, pyrization and sercitization-quartzitification. Wall-rock alteration zonation is obvious, from center to outward, it is divided into quartz-sericite zone, kaolinitization zone, sercitization-quartzitification zone and propylitization zone, the ore shoot is focused in the sericitization-quartzification zones, so it is a sign of further prospecting in this area; fluid inclusions research indicates that homogenization temperature is from 108℃to 375℃and most are less than 200℃; the salinity of fluid inclusions is from 0.88% to 8.68%, most are from 1.5% to 4.5%, which point out characteristic of epithermal gold deposit; REE distribution patterns have a rich light REE and a loss heavy REE, the curve is steep in light, heavy and light rare-earth elements fractionates obvious and europium anomaly faint; trace elements study shows that Au, Pb, Ba, Zn and Mo relative enrichment, which indicates that this area have a good mineralizing potential on gold and polymetallic deposit; main metallogenic elements such as Pb,Zn,Cu,Co and Ni are enriched in depth, which indicated that extending depth also have very good industrial prospects. Through this research, it can be concluded that there have a good prospecting perspective in extending and deepening of southwest zoneⅡ, it has vital significance to determine the genetic type and further prospecting.