The Study Of Mineralization By Relay Structure Of Normal Fault On Typical Metal Ore Deposit

The relay structure which is not only common feature of normal fault systems but also reflect normal fault segmentation propagation mechanism, is a new research subject of structure geology. Based on propagation and development feature of relay structure in normal fault, the author has used the mode of relay structure in normal fault to study metallotectonics characteristics of metal deposit controlled by normal fault in extension setting, discovered and recovered the whole structure form of deposit, has discussed new factor and mechanism of metallotectonics, and it has important theory meaning and applied significance to the presently large-scale mineral resource surveying work in our country. The main new views obtained are as follows:(1) According to systematic studying geological feature of ore body in Xitieshan deposit, the author proposed that the exhalative sedimentary primitive shape of Xitieshan deposit is "ore body fan", and has analyzed formation mechanism and relation with zonation of deposit of "ore body fan", enriched the content of metallotectonics of exhalative sedimentary deposit.(2) Based on study of ore deposits and ore-body structures of two sedimentary-exhalative ore-deposit, Changba and Xitieshan ore deposit, the author found that the structural patterns of metallogenic basin of seafloor exhalative sulfide deposits in the ancient graben systems are controlled by relay structures in normal faults. The shapes of metallogenic basins dominate migration of gravity current of ore-hosted fluid and shape of ore-body sedimentary fan in the ramp. By measuring and comparing the difference of length-to-thickness ratios of ore-body sedimentary fan, it shows that the occurrence of the ramp has a remarkable impact on shape of ore-body. It provides new research thinking to recognize metallotectonics of exhalative sedimentary deposit.(3) Take Xitieshan deposit as an example, the author discuss the relation between the spout structure of exhalative sedimentary deposit and relay structure of normal fault, it is the first time to propose that the spout structure of exhalative sedimentary deposit is controlled by relay structure of normal fault. According to mechanical properties of relay structure in normal fault, the spout structure should locate in end of en echelon fault, which has stress concentration and the biggest stress difference, is position which the ore fluid first spouts.(4) In the case study of typical exhalative sedimentary deposit, combine the propagation feature of relay structure of normal fault, the influence of the multi-activity growth fault on exhalative sedimentary deposit in terms of kinematics is discussed, which is: a, the propagation of growth fault reduce the change of mineralize basin shape, influence the migration and sediment ore-hostd fluid; b, the propagation of fault make the position of fault tip move, influence the position and distribution of spout structure.(5) The segmentation propagation of normal fault produce different form of relay structure, such as en echelon-type and symmetry-type relay structure, which restrict the distribution of exhalative sedimentary deposit in structure basin controlled by growth faults of graben systems, and different scale relay structure of growth faults has different control of mineralization.(6) Take Liming and Xiaoliugou deposit as an example, accord with the propagation feature of relay structure of normal fault, the author discuss the metallotectonics feature of the ore-hosted normal fault by magma invade, re-recognize the distribution form and mineralize law of ore body, set up the ore-controlling pattern by relay structure, and according to mechanics characteristic of relay structure in normal fault, discuss the ore-control mechanism by relay structure of normal fault.