Study Of Orebody Space Location Regularity And Prospecting Direction Of Jiehe Gold Deposit In Zhaoyuan City, Shandong Province

Jiehe gold deposit is located in the north-west of the Jiaobei Uplift of eastern Shandong shield, Sina-Korea Block. It belongs to the Jiaojia-Xincheng gold ore field of the Zhaolai gold belt, Jiaodong gold deposit concentration area. The gold deposit is occurred in the northern of Wang’ershan fault zone which is a branch of the Jiaojia fault zone. The gold ore bodies are strictly controlled by fracture structures. As a typical altered rock type gold deposit, Jiehe gold deposit is mainly composed of Ⅳ, Ⅰ and Ⅶ orebody. Now, the exploration engineering expose that the vertical depth of the orebody is about800meters, which reveals the second mineralization enrichment zone very typically and completely.Based on the field geologic survey in Jiehe mining area, combining to the field geologic survey and contrastive analysis of its peripheral gold deposit Wang’ershan and Shangzhuang, and by studying fault-controlled regularities and space fine structural features of the mineralization field, this paper studies systematically the orebody space location regularity of Jiehe gold doposit, including equidistant distribution regularity of orebodies, regularity of lateral prostration, geometric features of orebodies, vertical variation of the mineralization and lower limit of orebodies et al. Finally, this paper discussed prospecting perspective of the orebidies and delineated prospecting target. The main results are as following:1.The main fault presents undulation along trend and tendency. The fracture surface is uneven and becomes slow gradually from the shallow mining area to the deep mining area, which shows a large slope dipping northwestward. The main orebodies are occurred in the transfer sites between the concave surface and convex surface. Vertical variation of the mineralization is controlled by the main fault. In vertical the occurrence of the orebodies changes as the occurrence of the fracture plan and becomes slow gradually from the shallow mining area to the deep mining area. In addition, the different types of mineralization are also controlled by nature of the main fault. The degrees of mineralization are controlled by the density of secondary faults.2.In the mining area the crystal habit of pyrite is very simple, made of the simplex form caystal which accounts for about70.5%and combinate form crystal which accounts for about29.5%. Thermoelectricity of pyrite is mainly N type with few N>P mixed type. The variation characteristics of pyrite’s typomorphic parameter Xpy, crystal morphology index f1, pyroelectric coefficient a, pyroelectricity parameter Xnp et al, reflecting that I orebody has a long total extended depth.3.Gold mineralization shows inhomogeneous distribution in the space, which changes between strong and weak in vertical. The mineralization becomes slow gradually from the shallow mining area to the deep mining area. Orebody’s thickness, length and ore grade show positive correlation. Trace element content shows inhomogeneous change in the space with many apparent concentration center. The same trace element content shows independent and similar spatial distribution characteristics in the first, second mineralization enrichment zone. The occurrence of front and rear halo elements at the middle and lower part of the second mineralization enrichment zone, indicating that the orebody still be some extension to the deep.4.The orebody presents some regular spatial distribution. The Ⅳ, Ⅰ, Ⅶ orebody is Nearly isometric distribution, the distance between two oredodies is about220m and300m. Main orebodies pitch to southwest. The pitch angle of orebody in different part presents some regular change. The pitch angle of orebody in the first mineralization enrichment zone is bigger than which in the second mineralization enrichment zone, and The pitch angle of orebody occurred in the hanging wall of the main fracture is smaller than which in the footwall. The oredodies are characteristic by concentration occurrence, appearing in groups, parallel arrangement in the plane and discontinuity, branching swollen contraction in the vertical. There is geometric proportion between main orebody’s thickness and vertical depth, which shows a geometric ratio.5.Mineralization shows obviously zoning of enrichment in vertical. The orebodies has piecewise enrichment characteristics in vertical, now there was found the first and second mineralization enrichment zone by exploration engineering. Orebody scale becomes small and mineralization intensity decreases gradually from shallow part to deep part, which shows that it will be weak gradually in the deep mining area. The mineralization type zone is that altered rock type mineralization occurs mainly in the first mineralization enrichment zone with few the fissure vein type mineralization, while there is mainly made of the fissure vein type mineralization in the second mineralization enrichment zone with some altered rock type mineralization.6.0n the base of comprehensive study, this paper first establishes the three-segment zoning model of gold mineralization in vertical direction, eastern Shandong. Quartz vein type mineralization occurs mainly in the shallow mining area. Pyritization sericitization altered rock type mineralization occurs mainly in the middle mining area while potassic alteration granite type fissure vein type mineralization occurs mainly in the deep mining area. Although it still need to validate whether the model is universal by exposing mineralization characteristics in deep part of the gold deposit, this model can offer important theoretical guidance and reference meaning to help exploration in the deep mining area of gold deposit, especially for the exploration in the third mineralization enrichment zone in Jiaodong. According to the model, if there is the third mineralization enrichment zone in gold deposit, especially for altered rock type gold deposit in Jiaodong, it can be infered that it’s more likely to find potassic alteration granite type fissure vein type mineralization or have both pyritization sericitization altered rock type mineralization potassic alteration granite type fissure vein type mineralization in third mineralization enrichment zone.7.By studying on the lower limit of orebody in Jiaojia fault and Wang’ershan fault, pyrite’s pyroelectricity parameter, it’s inferred that main orebody should thin out at least-1200m level in Jiehe gold deposit. By study of exploration engineering’s exposing, orebodies’ geometric proportion and pyrite’s pyroelectricity parameter, combine with exploration engineering’s exposing for the second mineralization enrichment zone in Shangzhuang gold deposit, this paper inferred that the I orebody of the second mineralization enrichment zone should thin out at about-850m level in Jiehe gold deposit. In addition, this paper estimates that the second non-ore area’s distance is about100m by using analogy of the first non-ore area’s distance which is about100m, inferred that there will be possibly to find the third mineralization enrichment zone at about-950m to-1000m level in Jiehe gold deposit.8.On the base of comprehensive study of orebody space location regularity, Prospecting perspective for these deposits is discussed. There is a good prospect exploration for deep of I orebody. Because the Ⅳ orebody below-586m level has been found in Shuangzhuang gold deposit beyond line407of mining right boundary, it’s no use prospecting in Jiehe gold deposit. For the deep part of Ⅶ orebody, its ore-forming geological conditions is not good and its structure, altered and mineralization in the deep part are also much weaker than in the shallow part, These characteristics indicate that there is not good ore-forming geological conditions and it’s not optimistic to find new orebodys in the deep part of VII orebody. Finally, this paper delineated two prospecting targets in the deep part of I orebody, estimating that333level resources of the targets is about6.05tons.