| The Dawenkou Basin is the largest ore-forming basin in the Luxi area.It has accumulated 66.74 billion tons of gypsum ores and 7.521 billion tons of rock salt ores.However,the spatiotemporal distribution characteristic of gypsum and rock salt ore deposits and their ore-controlling factors have not been systematically studied from the entire basin.This has restricted the in-depth understanding of the metallogenic regulation of the basin and the reasonable deployment of exploration planning to a certain extent.To this end,the thesis focuses on the evaporites rocks and typical ore deposits in the Dawenkou Basin,by studying the metallogenic regulation and ore-controlling factors of gypsum and rock salt ore deposits,integrating effective ore-prospecting methods and techniques to establish a survey model.The thesis achieved the following main results:(1)A systematic study of the spatiotemporal distribution characteristic of gypsum and rock salt deposits revealed that the deposits were concentrated in carbonate-sulfate-sodium salt deposits in the middle of the Dawenkou Formation;From the edge of the basin to the center,the number of ore layers increases and the thickness increases;And the settlement center of the secondary depression on the slope of the basin is also a favorable place for thick gypsum deposits.(2)The variegated mudstone layer and gray-white glutenite layer are used as landmark layers,and the comparison of cores of typical ore deposits and previous work results are used to determine the third-order sedimentary rhythm of evaporite rocks.According to this,it is pointed out that the tops and bottom of the basin slope depressions and central depressions are the main distribution areas of gypsum ore deposits.Syngenetic faults on the periphery of Dongxiang depressions are concentrated distribution areas of rock salt deposits and the sodium,magnesium and potassium magnesium salts.(3)Utilizing the new exploration results of the Yangjiapo Mine Section,the petrographic map of the evaporite rocks in the basin was revised,which broke through the original understanding of the rock-free salt deposit in Manzhuang-Daxiniu depression.It is inferred that the Manzhuang-Daxiniu depression and the basin center Dongxiang depression were the same depression in the early salt formation period,forming a unified rock salt deposit,subsequently,the F3 syngeneic fault activity split the depression into the upper Manzhuang-Daxiniu depression and the lower Dongxiang depression.Based on this,the drilling and deployment of the Xinzhaizi Mine Section was guided to expose the salt-bearing section of nearly 100 meters and several layers of rock salt ore deposits.(4)By systematically studying the metallogenic conditions and environment,and comprehensively evaluating the effectiveness of methods such as geology,gravity measurement,seismic measurement,integrated exploration wells and drilling,this thesis integrates the four-stage ore-prospecting method technology combination of regional mineralization geological environment research and regional gravity measurement methods to delineate strategic selection,large-scale gravity measurement and seismic measurement basin positioning,sparse drilling engineering verification basin evaluation and drilling combined with earthquakes,integrated geophysical solutions to ore layer positioning,four stages of finding Mining method technology combination.Based on this,a ore prospecting model for the gypsum and rock salt deposits in the Dawenkou Basin was established,which has guiding significance for subsequent exploration work.(5)According to the ore-forming elements and their combination characteristics,necessary to determine the strata,tectonic setting,metallogenic environment,metallogenic epoch and ore-controlling conditions.Combined with the regional gravity,seismic and drilling results obtained in the region,Two rock salt deposits,one Gypsum Deposit II prediction area and one Gypsum Deposit III prediction area have been delineated. |
PDF Full Text Request