中文摘要:对金堆城斑岩钼矿含矿裂隙系统的定点等积测量数据用分块三次多项式汉梅特插值趋势面分析程序进行电算，编制了各主要成矿阶段的裂隙密度和含脉率等值线图以及裂隙产状等密图。研究结果表明。成矿期裂隙含脉率峰值区以矿化斑岩小岩体为中心向外逐渐降低，与钼品位变化趋势一致，这类裂隙是在斑岩造成的热应力破裂基础上，再经区域构造应力多次作用形成，成矿前和成矿后裂隙系统的含脉率极值区偏离或远离斑岩体，仅与区域构造应力作用有关。裂隙系统主导走向为北北西，成矿产生在以压应力为主的构造环境中，含矿裂隙系统的特征与成矿过程有密切的内在联系。
Abstract:The hypogene mineralization in the Jingduicheng molybdenum deposit of Shaanxi province can be divided into two mineralization episodes composed of ten paragenetic stages, which axe (J-1) potash feldspar, (1-2) quartz + potash feldspar + pyrite, (I-3) quartz + potash feldspar + molybdenite, (I-4) quartz + molybdenite; (I-5) pyrite, (11-1) quartz + potash feldspar, (11-2) molybdenite + quartz, (11-3) quartz + pyrite + fluorite + molybdenite; (II-4) quartz and (11-5) quartz + calcite. Three measured parameters-fissure- apertrure (in cm), fissure density (in cm-l) and fissure abundance (in percentage)-are used to describe features of the fissure system at different stages. Quantitative data are derived by direct measurement of fissure at 210 observation points in an area-of l.26 km2 within the open pit. The data of fissure densities and fissure abundance are computed and fitted precisely to a trend surface by a program of piecewise bicubic polynomial Hermite interpolation method. Pores of these fissures are plotted on equal-area nets and the fissure strike is illustrated by rosette histograms. The investigation results show: 1. The configuration of total fissure abundance contour is in rough agreement with the one of Mo-ore grade contour, whereas the total fissure density contour is quite different from the Mo-ore grade contour in shape. 2. The configuration of total fissure abundance contour is approximately consistent with that of fissure abundance, contour of each mineralization stage. nevertheless, it is somewhat unlike the contour configuration of the pre-mineralization stage and apparently different from that of the post-mineralization stage. 3. The fissure abundance at mineralization stage decreases from the center where granite porphyry outcrops beyond the open pit. The area with maximum fissure abundance at post-mineralization stage is 1ocated near the margin of the studied area and controlled by a ENE-trending fault zone. 4. Pole and strike diagrams show that all the veins and mineralized joint sets are systematically oriented in a simple pattern that consists of an approximately horizontal to approximately vertical system of fissures striking 325°~340°, 310°~290°, 40°-75°and 15°-25°, among which the NW-trending ones are predominant. On the basis of the above data, a genetic model for the fissure system in the Jingduicheng porphyry molybdenum deposit is formulated to the effect that the thermal stress and magmatic pressure were likely to produce a set of blind or fine tensile and shear fissures within the porphyry body and host rocks around the top of the intrusion, and the mineralized fissure system was eventually formed during the repeated activation of tectonic stress. It js difficult to interprete the resulting geometrical distribution of fissure pattern by a simple collision-subduction model of coeval plate convergence, and this distribution may therefore be related to A-type subduction. The high permeabilities as represented by the high fissure abundance around granite porphyry must have stimulated the mixing of magmatic and meteoric waters. This process has caused the low salinity and low δ18OH2O value of ore-forming solution, and might have generated an unusual variation trend of sulfur isotopic composition of sulfides. Repeated activation of this fissure system probably played an important role in mechanically preparing prerequisite for porphyry molybdenum mineralization to attain ore grade.
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任启江，吴俞斌，武耀城，周会群，徐兆文.1987.陕西金堆城斑岩钼矿含矿裂隙分布规律与成因[J].矿床地质,6(3):35~48.1987.Distribution Pattern And Origin Of Ore-Bearing Fissures In The Jingduicheng Po'rphyry Molybdenum Deposit,Shaanxi Promnce[J].Mineral Deposits6(3):35~48
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