ORE-FORMING DYNAMICS OF TECTONIC REGIME TRANSFORMATION AND MULTI-LAYER FLUID CIRCULATION
-
摘要: 运用定量计算和计算机模拟与传统地质学相结合的方法, 研究胶东矿集区中剪切构造变形和围岩蚀变与物质迁移及金矿富集的相互关系.结果表明, 在剪切-蚀变作用过程中, 各种物质组分发生了不同程度的迁移, 存在较大的流体/岩石比值, 体积应变为增加型.成矿作用发生的最主要原因是剪切挤压-拉张构造作用引起的成矿元素活化→运移→富集.成矿早期, 形成以包体金为主的贫矿石; 成矿晚期, 形成含裂隙金和多金属细脉的富矿石.Abstract: In a metallogenic system, tectonism and fluid process occurred at the same time and therefore, they are coupled with each other. The action of ore-forming fluids is bound up with formation and evolution of ore-controlling structures. Structural-fluid temporal-spatial evolution track is, in essence, the mobilization, migration, aggregation and location process of ore-forming materials, i.e. the coupled process of structural fluid mineralization. In this paper, the geological analysis for the gold-deposit concentration region of Jiaodong, Shandong Province, China, is conducted with the Gresens' equation, Grant's isocon diagram and O'hara microelement calculation method, to reveal the interactions among the shear tectonic deformation, the wall-rock alteration, mass transfer and gold mineralization. The research results show that the shear deformation and hydrothermal alteration not only include the deformational condition, feature and mechanism of the shear zone, but also are related to the formation, component, flow or circulation model and flux of the fluids in the zone, resulting in the reallocation of elements and the migration of the chemical materials. During the shear-alteration process in the Jiaodong gold concentration area, all kinds of components were transferred in different amounts, the fluid-rock ratio was relatively high and the volume strain was of dilation type. The major reason for this mineralization is the mobilization, migration and enrichment of ore-forming elements induced by the shear compressive-extensional tectonism. The low-grade ores dominated by the inclusion gold were formed in the early ore-forming stage, while the high grade ores containing fissure gold and polymetallic veinlets were formed in the late ore-forming stage.
-
Key words:
- shear-alteration /
- mass transfer /
- ore-forming process
-
表 1 胶东焦家金矿蚀变岩石平均化学成分
Table 1. Mean chemical components of altered rocks in Jiaojia gold deposit of Jiaodong area
表 2 胶东夏甸金矿剪切-蚀变作用过程中相对于原岩组分迁移量、体积变异和流体流量
Table 2. Component transfer, volume variation and fluid flux during the process of shear-alteration in Jiaodong area of Shandong Province
-
[1] Ramsay J G, Graham R H. Strain variation in shear belt[J]. Can J Earth Sci, 1970, 7: 789~801. [2] Bonnemaison M. "Filons de aurifere"an cas particulier de shear aurifere[J]. Chron Rech Min, 1986, 482: 55~66. [3] 邓军, 翟裕生, 杨立强, 等. 论剪切带构造成矿系统[J]. 现代地质, 1998, 12(4): 493~500. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ804.005.htm [4] 邓军, 杨立强, 孙忠实, 等. 剪切带构造成矿动力机制与模式[J]. 现代地质, 1999, 13(1): 1~7. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ902.000.htm [5] 邓军, 翟裕生, 杨立强, 等. 剪切带构造-流体-成矿系统动力学模拟[J]. 地学前缘, 1999, 6(1): 115~129. doi: 10.3321/j.issn:1005-2321.1999.01.010 [6] Gresens R L. Composition-volume relationships of metasomatism[J]. Chemical Geology, 1967, (2): 47~65. [7] James A Grant. The isocon diagram—a simple solution to greses equation for metasomatic alteration[J]. Economic Geology, 1986, 81: 1976~1982. doi: 10.2113/gsecongeo.81.8.1976 [8] O'hara. Fluid flow and volume loss during mylonitization: an origin for phyllonite in an overthurst setting, North Carolina, USA[J]. Tectonophysics, 1988, 156: 21~36. doi: 10.1016/0040-1951(88)90280-6 [9] Dong F X, Li Z J, Chen B L, et al. A study on high-temperature and high-pressure experiment of correlativity between deformational system of Aubearing rocks element adjustments[J]. Acta Geologica Sinica, 1999, 73(1): 40~46. doi: 10.1111/j.1755-6724.1999.tb00810.x [10] Детников Ф А. Кпроблеме вертикальной зональности и рудоносности глубинных разломов докембрия[J]. Геология рудных месторождений, 1991, (2): 15~24. [11] Cameron E M, Hattori K. Archean gold mineralization and oxidized hydrothermal fluids[J]. Ecology Geology, 1987, 82(5): 1177~1191. doi: 10.2113/gsecongeo.82.5.1177 [12] Cameron E M. Derivation of gold by oxidative metamorphism of a deep ductile shear zone: part 1. conceptual model[J]. Journal of Geochemical Exploration, 1989, 31: 135~147. doi: 10.1016/0375-6742(89)90003-4 [13] Newton R C. Fluids and shear zones in the deep crust[J]. Tectophysics, 1990, 182: 21~27. doi: 10.1016/0040-1951(90)90339-A [14] Nesbitt B E, Murowchick J R, Muhlenbachs K. Dualo rigins of lodegold deposits in the Canadian Cardillera[J]. Geology, 1986, 14: 501~509. [15] 邓军, 翟裕生, 杨立强, 等. 构造演化与成矿系统动力学[J]. 地学前缘, 1999, 6(2):315~323. doi: 10.3321/j.issn:1005-2321.1999.02.010