STRESS FIELD EVOLUTION IN MESOZOIC ERA IN ERGUN REGION AND ITS RELATIONSHIP TO GOLD-LEAD-ZINC ORE DEPOSITS

In Ergun region, there are mainly three periods of stress fields during Mesozoic Era, i.e., Indosinian period (T₂J₁), Tamulangou periods of(J₃)and Shang kuli period (K₁).In Indosinian period, the orientation of primary stress is NNW-SSE, and two large ductile shear zones striking 0~20° were formed.In Tamulangou period, the orientation of primary stress is NWW-SEE, and two groups of conjugate joints striking respectively 60~90° and 320~340° were developed.In Shangkuli period, the orientation of primary stress is NNE-SSW, which made the conjugate joints formed in Tamulangou period remove as fractures, reverse faults, etc. There are many gold, lead and zinc ore deposits(spots)in Ergun.The attitudes of orebodies are identical with the structures formed in Tamulangouperiod and Shangkuli period.Therefore in Mesozoic Era, the master ore forming periods are Tamulangouand Shangkuli periods.The prospectimg for gold deposits in the region should be focused on or beside the two large shear zones.