Structural Framework And Ore-controlling Structures Of The Huogeqi Copper Polymetallic Deposit In Inner Mongolia

There is rift sedimemary during Meso-Neoproterozoic in the Inner Mongolia and the rift begins in the early Mesoproterozoic,which results in the division of the northern part of North China plate into two rift trough at about 1800-950Ma.They extend along the plate boundary and make the deposition of the Bayan Obo group and the Chaertai group,respectively.The two rift trough are separated by an ancient island chain,meanwhile the passive continental margin develops in this region.This region experience the collision until the late Neoproterozoic(950-700 Ma).The Huogeqi deposit area is located at Bayinbaolige town,Wulatehouqi.It tectonically belongs to the north limb of Langshan anticlinorium.Tectonically,through the field observations and laboratory analysis we divide the ore field into three parts:northern,central and southern belt.Also,we can obtain that the northern belt is charactered by the development of the horizontal lineations.To the opposite,the southern belt is characterized by the development of steep lineations while the central zone is characterized by the development of superposed folds.Based on abundant previous work,we complete the field investigation and indoor analysis to write this paper.Through analysis about the outcrops of rock and various lineations and foliations,we consider the ore field has experienced multi-phase deformation and initially propose that the ore field is affected by three phases of deformation,which has different effects in different belts.The first period of deformation performances for the NW-SE shearing action,mainly in the southern and central belt,which results in the formation of a recumbent fold in the central belt.The second period of deformation performances for the NE-SW shearing action,mainly in the northern and the central belt,which results in the bend of the recumbent fold in the central belt;The third period of deformation performances for the NW-SE stress,which results in the fold of the Huogeqi ore field as a whole.Finally,the northern belt correspondingly develops horizontal lineation,the southern part steep lineation and the central belt southwest plunging anticline.Deformation has a obvious control on the deposit:the first phase of deformation(D1)and the second phase of deformation(D2)plays an important role on the alteration and re-enrichment of the deposit.Tectonic analysis reveals that the deposit extends much longer than its length on the surface.D1 destroys the deposit,making it becomes many of lens and the measurements of lens axis reveal that the length of transverse is far less than the extension of the deep;D2 deformation is characterized by plunging vertical fold,whose turning side is the most favorable place for ore.It makes the re-enrichment of the deposit,which is useful for the forming of the deposit.The third phase of deformation performance for the overall of the ore field bending as a northern limb of the fold.Generally,the formation of the deposit is based on the physical replacement.