Development And Regularity Of Evaporates And Its Metallization In Kuqa Basin From Paleogene To Neogene

There are abundant copper resources, but it is not given a approving requirement to increase of economy in China, and about 62% material of copper is imported now, so the copper ore is still one of much lack ore sorts. The datum of Stat. makes shown that sandstone-type mineralization is the second largest in copper ore sorts than Porphyry copper deposit either amount or reserves. Many sandstone-type coppers had been developed in fragmentary rock in Neogene in Kuqa Basin, especially Baicheng Dishui small copper, has been exploited from Qing dynasty, and these are closely contacted with much evaporates in the Basin. So searching for metal mineral or copper, and researching the connection between evaporates systems and sandstone-type copper et al. metallization, it is given a new research domain which has been cut on copper prospecting.Evaporates sediment with gigantic thickness had been developed in Kuqa Basin from Paleogene to Neogene period and the thickness of salt or gypsum changes from tens of meters to two thousands meters. A series of copper mineralization has been developed in sandstones in Jidike Group and Kangcun Group in Neogene. It is well known that by field investigation and indoor analysis, the mineralization lies near by salt domes and distributes on structure belt from west to east, and the main copper mineral is Atacama (Cu2 (OH)3 Cl) which is also connected with brain and drought climates, not only has the Atacama been born with crystal remains of brain in structure belt of limestone, but also dip-dyed in gypsum which had been full of joint planes of sandstone, the Atacama and native copper are lied in epigenetic gypsum gobbet or the former lies in cranny of sandstone which the brain exuded, it is primary chemical sediment for Atacama and filling of cranny of sandstone with nervation or arborization by analyzing with Electron probe, sulfureted hydrogen is overflowing from structure belt, native sulfur and calcium carbonate are depositing, covellite (CuS) is found in native sulfur, all this give a conclusion that thermochemical sulfate reduction has been in existence, the outcome move by breakage and so reducing environment come into being, Some metals including Atacama, copper, zinc, silver, uranium and native gold are discovered in samples of evaporates including salt samples of salt domes, gypsum samples in petroleum drill holes with depth 4412 meters, and salt shell samples forming in the earth's surface in the first in Kuqa Basin. These tell us that metals or sandstone-type copper mineralization are close connection with evaporates and breakage.For the seek of explaining these geological phenomena and giving a approving answer for the relations on metals or sandstone-type copper mineralization, evaporates, and faults, we need to research the development rules of evaporates, characteristics and mechanism of sandstone-type copper mineralization, especially the relations on evaporates systems (evaporate body, wall rock, and faults of wall rock) and sandstone-type copper mineralization, and the key is the action of evaporates systems in the courses of sandstone-type copper mineralization, and so resolve the issue weather the evaporates systems can make metal ore or not.For the purpose some techniques are used. First distribution characteristics of salt domes, relations on evaporates and copper mineralization, distribution characteristics of fragmentary rock in Neogene by field investigation, and collecting some samples such as spring, barine, salt frost, copper mineralization or evaporates samples, and measuring sections, collecting some samples of salt domes or fragmentary rock. Second, indoor analyzing the samples by SEM, slice analysis, X diffraction, Electron probe, isotopes analysis, chemistry analysis of solid and water samples, and experiment on evaporation and leaching, and so we can find out mineral component, compose, configuration, conformation, et al. of solid, variety relations on elements of water samples, origin of brain, ore sources and ore-hosting, cause of formation of copper mineralization in salt and gypsum, conditions and environment of copper leached and enriched. In the same time, we can research diversification of evaporates in space time by division of evaporates sedimentary cycle and establishment of dimensional models.As a result for the research, the stratum of evaporates lie in mainly Kumugeliemu group, Suweiyi group in Paleogene, and Jidike group in Neogene. The-types of evaporates are main halite, gypsum, and a few dolomite and limestone, comprised of some minerals such as brongniartine, anhedritite, carnallite, halo-sylvite, kaluszite, and hydrophilite. By studying for sedimentary cycles of evaporates from Paleogene to Neogene in the basin, five cycles are identified, andâ… 1 andâ… 2 cycles lying in Kumugeliemu group,â… 3 cycle in Sweiyi group,â… 4 andâ… 5 cycles in Jidiek group.â… 2 cycle was expanded from north to south based onâ… 1 cycle in Kumugeliemu period, accompanying with the floor has been raised in the northwest of the basin, brine began to move so that two sedimentary areas came into being, accordingly, the areas began to move by oneself from northwest to south and east, in Jidike period the evaporites sediment with gigantic thickness had kept on development in the areas. The space model of salt and gypsum are showed that the undulate trend of orebody is consistent with Qiulitage and Kelasu tectonic zone, and two sedimentary centre which lie in Baich and in south of it are reflected in the west of the basin in Kumugeliemu period, so is it in the east of the basin in Jidike period, but its sedimentary centre lie in Luntai and in north of it.Two mini-type copper ores and eight copper mineralization spots are discovered in the Basin by field investigation and indoor analysis, that the Kezier copper mineralization spot and Age copper mineralization spot are the first discovered, and the distribution of mineralization is near by salt domes which lie in two big tectonic zone from north to south and spread out from west to east. Four sorts of mineralization had been developed including limestone type, sandstone type, mudstone type, and sulfide type comprised quartz reef. the main copper minerals are Atacamite, azurite, and native copper. Kangcun group of Pliocene is main ore bed, and the other is Jidike group of Miocene, which lie in alar part near by axis part of anticline. The evaporates, maroon siltstone, and maroon mudstone are source bed and the essential ore beds are celadon siltstone, fine stone, and grey grit stone.The brine roots in primary bittern and evaporates dissolved by atmospheric water, the first origin of copper come from old copperish stratum of the south Tianshan tectonic belt, and the evaporates, maroon fragmentary rock offer the second origin of copper. Intergranular dehydration, unload of salt body, and tectonic extrusion are main momentum on movement of coppery brine. The good channels for ore brine are rift, fracture zone of late Jidike period. It is a hint that Coppery sulfid would come into being when brine enriched copper ions had happened to brine enriched sulfidion in deep stratum by discovering existence of thermochemical sulfate reduction(TSR) in Kuqa Basin from Paleogene to Neogene, and these are already approved by drilling for copper ore in Dishui.The sandstone-type copper metallization, not only connected closely on brine, but also related with prime deposition of sandstones. The metallization epoch is from later Miocene to middle or later Pliocene, and not later than forepart of Pleistocene. In this article the metals especially sandstone-type copper metallization in sandstones are not detached from evaporates systems (evaporates body, wall rock, and fracture structure), and it is possible that metallization can happen in the systems.