Geothermal History And Uplifting Processes In The Almalyk Copper-Gold Cluster,Uzbekistan

The deposit would undergo different evolutions after its formation.The uplift and denudation of the ore deposit after the mineralization has a great influence on the change and preservation of the deposit.The Almalyk gold-copper ore deposit consists of five large-sized super-large porphyry Cu-Au deposits,21 large epithermal Au deposits and the Kurgashinkan large skarn Zn–Pb deposit.It is the second largest porphyry copper-gold ore area in Asia.A large number of previous studies in the ore concentration area have revealed that large-scale copper-gold mineralization occurred in the Late Carboniferous,but it is still unclear what kind of geothermal history evolution has occurred in the ore area after mineralization? How does the ore-bearing porphyry body be exposed to the surface? What is the potential for deep prospecting? It is for further study.In this study,the apatite/zircon fission track thermochronology method was used to study the uplift-denudation process of the Almalyk ore deposit.The experimental sampling is mainly fresh unaltered medium-acid volcanic rocks,the apatite fission track age distribution is 133-177 Ma,the zircon fission track age distribution is 155-213 Ma,and fission track age is concentrated in Mesozoic.The thermal history simulation curve shows that the Almalyk ore deposit has experienced two rapid cooling uplifts and one settling process since the Mesozoic: The first uplifting process took place at around 320-290 Ma.There was a certain difference in the amount of uplift in different regions during this period.The uplifting process was due to the closure of the Turkestan ocean at the end of the Carboniferous,the collision between the Kyzylkum plate and the middle Tianshan block led to the uplift of the mining area.The sedimentation process occurred at around 290Ma-280 Ma,which may be due to the localized extension of the subduction plate rotation/plate segmentation,which caused the settlement to be buried and caused the formation temperature to rise rapidly during this period.The second uplift occurred at 280 Ma to the present,and the upper limit was limited by the sericite K-Ar dating data,combined with apatite and zircon fission track data.The ore-forming depth of the porphyry deposit in the ore-concentrating area is calculated by the hornblende temperature gauge to be about 2722.2-5316.8m.Calculating the ore-forming depth of epithermal deposits in the quartz by fluid inclusions in quartz is about 500-1200 m.Through the statistical calculation of the uplift-erosion data of each sample,the uplift and denudation model of the Almalyk ore-concentrating area since the formation of the main deposit in the ore-concentrating area was established.The denudation degree is small in the central area of the ore concentration area and its surrounding area,and the denudation amount is about 1-1.5km;The degree of denudation is the largest in the southern part of the mining area,and the amount of denudation is about 3km;In the northern part of the mining area,the degree of denudation is relatively large,and the amount of denudation is about 2-3km.In Kauldy epithermal gold deposit and its surrounding denudation quantity is small.The predecessors found porphyry copper-gold mineralization in the deep drilling of the deposit,and attention should be paid to the prospecting and exploration of the porphyry cu-au deposit in the deep part of the deposit.The Kalmakyr and Sari-Cheku porphyry deposits have a large amount of denudation around them,and the shallow hypothermal hydrothermal deposits in the upper part are denuded.It is necessary to pay attention to the prospecting work of deep porphyry deposits and skarn deposits.