Geological Geochemistry And Prospecting Prediction Of Sandstone-type Copper Deposits In Chuxiong Basin

This doctoral dissertation, Studying on the Geology and Geochemistry, and the Prospecting Prognosis for the Sandstone Copper Deposit, in the Chuxiong Basin—Taking Liuju and Haojiahe Copper Deposit As the Case, is based on the Project of Superseding Resources Exploration for the State Crisis Mine—"Superseding Resources Exploration to the Xiaohe-Shimenkan Ore-body in Liuju Copper Deposit, Daoyao,Yunnan Province(NO.200453001)" and "Superseding Resources Exploration to the Haojiahe Copper Deposit, Mouding,Yunnan Province(NO.200653098)". Study on the geology and geochemistry, and the prospecting prognosis has guiding significance for metallogenic mechanism of sandstone copper deposit and exploration of copper resources in the Chuxiong Basin.Take the Liuju and Haojiahe copper deposits as study objects; based on the geological features of deposit, it summarized the tectonic evolution and ore-controlling regularity in study area. Element geochemistry characteristics in different deposits and different color rocks were contrasted. The data of fluid inclusion and isotope geochemistry was used for the study of ore-forming fluid. On the basis of the electron probe analysis and sandstone-type uranium deposit research results, this paper discussed the formation of mauve sandstone and grayish sandstone, and the mechanism of mineral and element zonation. It builted the metallogenic model of the deposit, that is "copper aggregation during sandstone mauve alteration".By adopting geochemical sections method from drill holes, it established the geochemical anomaly model. Combination with surface geochemical exploration and the synthetical geology analysis, it gained a good effect on prospecting prognosis in the deep and periphery.1. It expounded the spatial relationship between the "Mouding Slope" and Arcuate Sandstone Copper Belt in Chuxiong Basin. The sedimentary environment of "Mouding Slope" was favorable to copper preconcentrtion. The tectonism controlled the formation of sandstone copper deposit.2. It defined the exposure strata in detailed, and put forward the dividing indexes. Grayish sandstone was the main version in ore-bearing strata (K2m11?K2mx2), which is mauve pebbled and medium to coarse grained sandstones at the top and the bottom.3. It summarized the tectonic evolution and ore-controlling regularity. The Nearly North-South compresso-shearing structures lead to copper activation and transport, and ore bodies reenrichment by late tectonic reworking. The Nearly East-West compresso-shearing faults formed in the last stage pushed ore-bodies to the grayish bed.4. Analyzed of ore deposit geochemistry show that ore-bearing strata had experienced two processes fluid flow:?.Fading sandstone formed by reductive fluid (from mauve to grayish);?. Interlayer oxidative fluid came from the mauve direction. The sandstone copper deposit was formed in mid-low-temperature environmental, and ore-forming fluid derived from meteoric water, with low salinity. Ore-bearing hydrothermal solution came from the mauve direction and toward to the grayish direction. It builted the metallogenic model of the deposit, that is "copper aggregation during sandstone mauve alteration"5. By adopting geochemical sections method from drill holes, it established the geochemical anomaly model. Combination with surface geochemical exploration and the synthetical geology analysis, it enclosed prospecting areas, such as Haojiahe A, B, C block; Haojiahe-Laohudong belt; northwest side of Shimenkan; pitching end of Boji and Daxueshan anticline, which had taken good effect by field examination.