Abstract:

Hongtugou gold deposit is located in the boundary fault between the Middle Qilian block and North Qilian fold belt，the exposed stratas are mainly Middle Cambrian and Lower Ordovician Yingou Group.By studing the location of gold orebody，occurrence of gold，ore mineral and gangue mineral，we sum up geological characteristics and prospecting signs of Hongtugou gold deposit，it will be very important for next exploring.The gold orebodies are all occurrence in the second part of the mafic volcanic rocks within Yingou Group，which mainly consist of andesitic basalt，quartz sericite schist，biotite plagioclase granulite and some metamorphous malmstone，marble and so on.Orebodies distribute at bedded，lenticular and vein along the north-west or nearly east-west trending faults and the altered fracture zone near the faults.The ore minerals are mainly arsenopyrite，pyrite，a little native gold and native silver.Gangue minerals primarily include sericite，dolomite，muscovite and quartz.The change of gold grade is larger.Gold grains are mainly located and enriched in arsenopyrite and pyrite，which is closely related to the arsenic，sulfur metallic minerals and silicification.Gold grains are mainly in form of sub-microscopic grains （whose content is more than 90% in the ore），followed by the existence in the form of native gold.Ore is mainly disseminated structure，vein structure followed.

Key words: Geological characteristics, Prospecting signs, Hongtugou gold deposit, Qinghai Province