Characteristics of Listric Normal Fault and Its Role in Prospecting Prediction:An Example from Xixibao Large Manganese Deposit,Songtao County,East of Guizhou Province

Listric normal fault is formed under the system of local or regional tensile stress,produced in the stretch of resilient rock bottom under the system of brittle rocks.Listric normal fault in the plane is bent and secondary faults on both sides of the fault are featured by branch compound.In profile,with depth increase,the fault dip angle becomes gentle gradually and fault distance grows progressively,forming secondary faults with steep branch occurrence.F₁ fault developed in Xixibao large manganese deposit,Songtao in eastern Guizhou is a listric normal fault,whose stretching time should be consistent with the time of the transfer of early Cretaceous regional compression tectonic system to extension tectonic system.The entire F₁ fault and its branch fault causes the manganese-bearing rock series to fall and stetch in ladder shape,leading to the disconinuity of the mangnese-bearing series.The deeper the fault,the gentler the fault detachment plane and the wider the pulling zone.The fault and its secondary fault break the manganese-bearing rock series and cut it into several parts,affecting the continuity of the manganese-bearing rock series and forming a spatial association of ore body-empty band pulling-ore body.The falling of the upper wall of F₁ fault deepens the burial of the mangnese-bearing upper wall.Hence,we should take full account of the fault distance and scale rationally the empty belt in mineral prediction so as to prevent the exploration from drilling into the empty belt.