Climate warming is significantly influenced by rising summer maximum temperatures: insights from tree-ring evidence of the Western Tianshan Mountains, China

As one of the regions most affected by global cli-mate warming,the Tianshan mountains has experienced sev-eral ecological crises,including retreating glaciers and water deficits.Climate warming in these mountains is considered mainly to be caused by increases in minimum temperatures and winter temperatures,while the influence of maximum temperatures is unclear.In this study,a 300-year tree-ring chronology developed from the Western Tianshan Moun-tains was used to reconstruct the summer(June-August)maximum temperature(T_(max6-8))variations from 1718 to 2017.The reconstruction explained 53.1% of the variance in the observed T_(max6-8).Over the past 300 years,the T_(max6-8)reconstruction showed clear interannual and decadal vari-abilities.There was a significant warming trend(0.18°C/decade)after the 1950s,which was close to the increasing rates of the minimum and mean temperatures.The increase in maximum temperature was also present over the whole Tianshan mountains and its impact on climate warming has increased.The T_(max6-8) variations in the Western Tianshan mountains were influenced by frequent volcanic eruptions combined with the influence of solar activity and the sum-mer North Atlantic Oscillation.This study reveals that cli-mate warming is significantly influenced by the increase in maximum temperatures and clarifies possible driving mech-anisms of temperature variations in the Western Tianshan mountains which should aid climate predictions.

Climate warming is significantly influenced by rising summer maximum temperatures:insights from tree-ring evidence of the Western Tianshan Mountains,China

As one of the regions most affected by global climate warming,the Tianshan mountains has experienced several ecological crises,including retreating glaciers and water deficits.Climate warming in these mountains is considered mainly to be caused by increases in minimum temperatures and winter temperatures,while the influence of maximum temperatures is unclear.In this study,a 300-year tree-ring chronology developed from the Western Tianshan Mountains was used to reconstruct the summer(June-August)maximum temperature(Tmax6-8) variations from 1718 to2017.The reconstruction explained 53.1% of the variance in the observed Tmax6-8.Over the past 300 years,the Tmax6-8reconstruction showed clear interannual and decadal variabilities.There was a significant warming trend(0.18 ℃/decade) after the 1950s,which was close to the increasing rates of the minimum and mean temperatures.The increase in maximum temperature was also present over the whole Tianshan mountains and its impact on climate warming has increased.The Tmax6-8variations in the Western Tianshan mountains were influenced by frequent volcanic eruptions combined with the influence of solar activity and the summer North Atlantic Oscillation.This study reveals that climate warming is significantly influenced by the increase in maximum temperatures and clarifies possible driving mechanisms of temperature variations in the Western Tianshan mountains which should aid climate predictions.

Geological Characteristics and Zircon U-Pb Dating of Volcanic Rocks from the Beizhan Iron Deposit in Western Tianshan Mountains, Xinjiang, NW China

The Beizhan large iron deposit located in the east part of the Awulale metallogenic belt in the western Tianshan Mountains is hosted in the Unit 2 of the Dahalajunshan Formation as lens, veinlets and stratoid, and both of the hanging wall and footwall are quartz-monzonite; the dip is to the north with thick and high-grade ore bodies downwards. Ore minerals are mainly magnetite with minor sulfides, such as pyrite, pyrrhotite, chalcopyrite and sphalerite. Skarnization is widespread around the ore bodies, and garnet, diopside, wollastonite, actinolite, epidote, uralite, tourmaline sericite and calcite are ubiquitous as gangues. Radiating outwards from the center of the ore body the deposit can be classified into skarn, calcite, serpentinite and marble zones. LA-ICP-MS zircon U-Pb dating of the rhyolite and dacite from the Dahalajunshan Formation indicates that they were formed at 301.3±0.8 Ma and 303.7±0.9 Ma, respectively, which might have been related to the continental arc magmatism during the late stage of subduction in the western Tianshan Mountains. Iron formation is genetically related with volcanic eruption during this interval. The Dahalajunshan Formation and the quartz-monzonite intrusion jointly control the distribution of ore bodies. Both ore textures and wall rock alteration indicate that the Beizhan iron deposit is probably skarn type.

Variations of Snow Temperature and their Influence on Snow Cover Physical Parameters in the Western Tianshan Mountains,China

This article discussed about snow temperature variations and their impact on snow cover parameters. Automatic temperature recorders were used to sample at lo-minute intervals at the Tianshan Station for Snow-cover and Avalanche Research, Chinese snow temperature Academy of Sciences. lo-layer and the snow cover parameters were measured by the snow property analyzer （Snow Fork） in its Stable period, Interim period and Snow melting period. Results indicate that the amplitude of the diurnal fluctuation in the temperature during Snow melting period is 1.62 times greater than that during Stable period. Time up to the peak temperature at the snow surface lags behind the peak solar radiation by more than 2.5 hours, and lags behind the peak atmospheric temperature by more than 0.2 hours during all three periods. The optimal fitted function of snow temperature profile becomes more complicated from Stable period to Snow melting period. 22 h temperature profiles in Stable period are the optimal fitted by cubic polynomial equation. In Interim period and Snow melting period, temperature profiles are optimal fitted by exponential equation between sunset and sunrise, and by Fourier function when solar radiation is strong. The vertical gradient in the snow temperature reaches its maximum value at the snow surface for three periods. The peak of this maximum value occurs during Stableperiod, and is 4.46 times greater than during Interim period. The absolute value of temperature gradient is lower than 0.1℃ cm-1 for 30 cm beneath snow surface. Snow temperature and temperature gradient in Stable period-Interim period indirectly cause increase （decrease） of snow density mainly by increasing （decreasing） permittivity. While it dramatically increases its water content to change its permittivity and snow density in Snow melting period.

Spatiotemporal variations in the growth status of declining wild apple trees in a narrow valley in the western Tianshan Mountains, China

Malus sieversii(wild apple tree),only distributed in the Tianshan Mountains in Central Asia,is a tertiary relic species and an ancestral species of cultivated apples.However,existing natural populations of wild apple trees have been declining.To date,spatiotemporal variations in the growth status of declining wild apple trees and influencing factors in the narrow valley areas in the Tianshan Mountains remain unclear.In this study,field investigation and sampling were carried out in three years(2016-2018)at four elevations(1300,1400,1500,and 1600 m)in the Qiaolakesai Valley(a typical longitudinal narrow valley in the Yili River Valley)of the western Tianshan Mountains in Xinyuan County,Xinjiang Uygur Autonomous Region,China.Projective coverage,dead branch percentage,and 18 twig traits(these 20 parameters were collectively referred to as plant traits)were determined to comprehensively reflect the growth status of declining wild apple trees.The values of dead branch percentage ranged from 36%to 59%,with a mean of 40%.Year generally showed higher impact on plant traits than elevation.In 2017 and 2018,projective coverage,leaf size,leaf nitrogen concentration,and nitrogen to phosphorous ratio were markedly higher than those in 2016.However,dead branch percentage and leaf and stem phosphorous concentrations showed the opposite trend.Most of the topological parameters of plant trait networks differed in the three years,but the strength of trait-trait association increased year by year.The mean difference between day and night temperatures(MDT),annual accumulative precipitation,soil electrical conductivity,and soil pH had the greatest impact on the plant trait matrix.The growth status of declining wild apple trees was directly and positively affected by MDT and leaf size.In conclusion,the growth of declining wild apple trees distributed in the narrow valley areas was more sensitive to interannual environmental changes than elevation changes.The results are of great significance for further revealing the decline mechanism of wild apple trees in the Tianshan Mountains.

The zircon SHRIMP chronology and trace elementgeochemistry of the Carboniferous volcanic rocksin western Tianshan Mountains

The genesis of the Carboniferous volcanic rocks in the Dahalajunshan group, mainly consisting of trachytes and trachy-andesites and distributing widely in western Tianshan Mountains, remains to be controversial. It has been proposed to be relevant to “rift” or “plume”. Detailed pe-trology and geochemical data presented in this paper show that these volcanic rocks represent typical continental arc magmatism. The volcanic rocks are mainly trachy-andesitic, and the magma source is enriched in LILE, Th and Pb, and depleted in HFSE and Ce. Trace element geochemical study suggests that the basalts could be modeled by 7%-11% partial melt of garnet lherzolite. The volcanic rocks in the Dahala-junshan group are neither the products of “rift” nor so-called “plume” but represent the continental island arc of the Pa-leo-Southern Tianshan Ocean. The mantle wedge had been modified by the melt generating in subduction zone during a long evolution history of this island arc. The continental crust materials (i.e. mainly sediment on ocean floor) had been added into island arc through melt in subduction zone. Volcanic rocks occurring in different regions might represent magma eruption in different time. The zircon SHRIMP dat-ing indicates that the ages of the basalt varies between 334.0 Ma and 394.9 Ma. The 13 analyses give an average age of 353.7 ±4.5 Ma (MSWD = 1.7). The apparent ages of zircons in trachy-andesite vary between 293.0 Ma and 465.4 Ma. All analyses fall on the U-Pb concordant line and are divided into two groups. 8 analyses produce an average age of 312.8±4.2 Ma (MSWD = 1.7), which represents the crystal-lizing age of zircon rims in trachy-andesite. The acquired two ages (i.e. 354 and 313 Ma) belong to the Early Carboniferous and Late Carboniferous epochs, respectively. Thus, the Da-halajunshan group would be separated into several groups with the accumulation of high-quality age dating and data of trace element and isotopic geochemistry, in our opinion.

The^(40)Ar/^(39)Ar age record of formation and uplift of the blueschists and eclogites in the western Tianshan Mountains

The 40Ar/39Ar ages indicate that the eclogite facies rocks of the Hasiate slice in the western Tianshan Mountains were formed at the early stage of Devonian （401 Ma） and had been uplifted to the greenschist facies tectonic level in the middle stage of Devonian （381 Ma）. The formation and uplift of the blueschists of the Akesayi slice are constrained to the late stage of Devonian （370-364 Ma）. The different tectonic slices in the high-pressure metamorphic belt have experienced the different uplift history.

Discovery of Radiolarian Fossils from the Aiketik Group at the Western End of the South Tianshan Mountains of Chinaand Its Implications

The Aiketik Group, distributed at the western end of the South TianshanMountains, China, is an important lithostratigraphic unit involved in the South Tianshan orogen. Itis separated from the adjacent rocks by faults. Generally, the geologists ascribed it to the UpperCarboniferous according to Pseudostaffella sp., Profusulinella sp. and Fusulinella sp. found fromthe limestone and sandy limestone of Aiketik. Our radiolarian fossils were obtained from the chertsamples collected from the Haladaok section located at the upper Tuoshihan River. The fossils mainlyinclude Albaillella undulata Deflandre, Albaillella paradoxa Deflandre, Albaillella sp. aff. A.paradoxa Deflandre, Albaillella sp. cf. A. deflandrei Gourmelon, Albaillella sp., Albaillellaexcelsa Ishiga, Kito and Imoto (?), Belowea variabilis (Ormiston et Lane), Callella cf. C.parvispinosa Won, Entactinia cf. E. tortispina Ormiston et Lane, Entactinia aff. E. tortispinaOrmiston et Lane, Entactinia variospina Won, Entactinia sp., Eostylodictya rota (Won),Latentifistula impella (Ormistone et Lane) (?), Latentifistula turgita Omiston et Lane,Latentifistulidae gen. et. sp. indet. and Polyentactinia cf. aranea Gourmelon. Among them,Albaillella excelsa Ishiga, Kito and Imoto (?) is a Late Permian species with some elementsuncertain as there is only one poorly-preserved fossil of this species found so far. And tworadiolarian assemblages can be identified from the other fossils. One is the early EarlyCarboniferous assemblage represented by Albaillella undulata Deflandre, Albaillella paradoxa andAlbaillella sp. cf. A. deflandrei Gourmelon. And the other is the late Early Carboniferousassemblage represented by Eostylodictya rota (Won). This is the first discovery of radiolarianfossils in the Aiketik Group, also the first discovery of Late Permian radiolarian fossils in theSouth Tianshan Mountains. Meanwhile, this is the current westernmost sampling site of radiolarianfossils in the South Tianshan Mountains.

A test of Snowmelt Runoff Model(SRM)for the Gongnaisi River basin in the western Tianshan Mountains,China

The Snowmelt Runoff Model (SRM) is one of a very few models in the world today that requires remote sensing derived snow cover as model input. Owing to its simple data requirements and use of remote sensing to provide snow cover information, SRM is ideal for use in data sparse regions, particularly in remote and inaccessible high mountain watersheds. In order to verify the applicability of SRM in an environment of continental climate, a test of SRM is performed for the Gongnaisi River basin in the western Tianshan Mountains, the results show that two SRM average goodness-of-fit statistics for simulations, Nash-Sutcliff coefficient (R2) and volume difference (DV), are 0.87 and 0.90%, respectively. As compared with the application results over 80 basins in 25 different countries around the world, SRM performs well in the Gongnaisi River basin. The results also show that SRM can be a validated snowmelt runoff model capable of being applied in the western Tianshan Mountains. On the basis of snowmelt runoff simulation, together with a set of simplified hypothetical climate scenarios, SRM is also used to simulate the effects of climate change on snow cover and the consecutive snowmelt runoff. For a given hypothetical temperature increase of 4℃, the snow coverage and snowmelt season shift towards earlier dates, and the snowmelt runoff, as a result, is changed significantly at the same time. The simulation results show that the snow cover is sensitive to changes of climate, especially to the increase of temperature, the major effect of climate change will be a time shifting of snowmelt runoff to early spring months, resulting in a redistribution of seasonally runoff throughout the whole snowmelt season.

Association of Late Paleozoic Adakitic Rocks and Shoshonitic Volcanic Rocks in the Western Tianshan, China

The late Paleozoic adakitic rocks are closely associated with the shoshonitic volcanic rocks in the western Tianshan Mountains, China, both spatially and temporally. The magmatic rocks were formed during the period from the middle to the late Permian with isotopic ages of 248-268 Ma. The 87Sr/86Sr initial ratios of the rocks are low in a narrow variation range (-0.7050). The 143Nd/144Nd initial ratios are high (-0.51240) with positive εND(t) values (+1.28-+4.92). In the εNd(t)-(87Sr/86Sr)i diagram they fall in the first quadrant. The association of the shoshonitic and adakitic rocks can be interpreted by a two-stage model: the shoshonitic volcanic rocks were formed through long-term fractional crystallization of underplated basaltic magma, while the following partial melting of the residual phases formed the adakitic rocks.

西昆仑乔尔天山一带铅锌矿床成矿模型及控矿要素

近年来,在西昆仑乔尔天山一带发现了一批以火烧云铅锌矿床为首的超大型及大中型铅锌矿床,通过研究典型矿床的时空分布与形成机制,认为西昆仑乔尔天山一带中生代盆地铅锌矿床从成因方面可分为沉积-交代型、MVT型及岩浆热液型3种。通过Pb、S同位素分析,初步认为研究区铅锌硫化物具有深源特征,后期生物有机硫部分参与了成矿作用;通过C、O同位素分析,认为成矿热液属于原生成因。在总结成矿物质来源、控矿要素的基础上建立了区域成矿模型,认为沉积相与同生断层是沉积-交代型矿床的主要控矿要素,断裂构造是MVT型矿床的主要控矿要素,岩浆侵入与热液接触交代是岩浆热液型矿床的主要控矿要素。

西天山小哈拉军金铜矿床地质特征及找矿勘查模型

小哈拉军金铜矿床位于天山山脉西段的那拉提山北坡,地处伊什基里克裂谷与伊宁地块的结合部,其上叠加石炭纪岛弧,成矿位置较为特殊,且矿床蚀变类型复杂,具有一定的典型性。本文基于该金铜矿床最新工作成果,对成矿地质条件、物化探异常特征、矿化蚀变特征等进行了阐述,对其形成时代及矿床成因进行了探讨,初步建立了地质-地球化学-地球物理综合信息找矿勘查模型,其对该区外围寻找同类型矿床具有一定的参考意义。

新疆塔乌尔别克金矿矿床地质及稳定同位素地球化学特征

新疆塔乌尔别克金矿位于西天山吐拉苏断陷盆地,与阿希金矿相邻。金矿体主要赋存于下石炭统大哈拉军山组第五岩性段的火山岩类中,受4个环形构造及伴生的线性构造控制。本文在阐述塔乌尔别克金矿床地质特征的基础上,论述了金矿石的碳、氢、氧、硫、铅等稳定同位素地球化学特征。认为成矿流体中的碳的主要为岩浆来源,但是较为复杂,部分受到深部碳酸盐岩同位素交换的影响;成矿流体中的水源来自岩浆热液和大气降水的混合;矿石中的硫来自于深部岩浆;铅则显示造山带的特征,主要来自上地壳。分析稳定同位素特征,结合矿床地质特征,塔乌尔别克金矿的矿床类型确定为低硫型浅成低温热液斑岩型金矿。矿床稳定同位素的研究不仅能深化矿床地质的研究,还可对进一步的找矿工作提供珍贵信息。

西天山南麓两次暴雪过程对比分析

利用常规气象观测、FY-4A卫星及ERA5再分析数据,对比分析2021年2月25—27日(过程I)和4月1—4日(过程II)西天山南麓阿克苏地区拜城县2次暴雪过程成因。结果表明:两次暴雨过程均在中亚低值系统影响下发生,300 hPa偏西急流、500 hPa低涡(低槽)、850 hPa偏东急流、地面冷高压冷锋及暴雪区上空垂直环流的发展是形成暴雪的主要动力机制;均有偏西和西南路径的水汽输送,水汽强辐合出现在700 hPa;降雪期间TBB极值、<-30℃的维持时间及>-5℃对降雪量级、持续时间及降水相态预报有指示意义。不同点主要表现在:过程I为中亚低槽快速东移型,偏东急流仅在850 hPa,急流强度较弱且位置偏南;过程II为中亚低涡缓慢东移型,700、850 hPa有明显偏东急流且持续时间长,位置西伸至阿克苏地区北部;过程II上升运动中心更接近暴雪中心,且强度强、伸展高、持续时间长,冷暖交汇更剧烈,偏东水汽输送明显且辐合强度更强、辐合持续时间更长。

中国天山西部区域云降水物理野外观测科学试验研究若干进展

天山西部区域是中亚地区降水量最多的区域,其向西开口独特河谷地形与西风环流构成了中亚区域独有的云降水物理过程,降水形成积雪、冰川和径流对中亚社会经济和生态环境形成重要影响。随着国家“丝绸之路经济带”建设的推进,对中亚水资源、气象防灾减灾和生态环境保护提出了严峻的科技挑战,而该区域云降水物理过程的观测和研究是科技基础,仍处于起步阶段,不能满足国家战略和中国气象事业发展需求,为此于2019年建设了天山西部区域云降水物理野外观测科学试验基地,并对云宏微物理、层状云/对流云雨滴谱、中/西天山雨滴谱特征异同、冷锋暴雪微物理等开展了相关研究并取得了前沿成果,本文对此进行提炼总结,以期推动中亚地区云降水物理学科发展。

新疆西天山阔库确科铁铜矿区成矿岩体锆石微量元素地球化学特征及其地质意义

新疆西天山北缘的博罗科努晚古生代岛弧带出露大量中酸性侵入体,并发育一系列斑岩-矽卡岩型铁铜多金属矿床。文章对该岛弧带中部阔库确科矽卡岩型铁铜矿床成矿岩体中的锆石开展了微量元素地球化学研究,查明了锆石成因、形成物理化学条件及其对成矿的启示意义等。数据显示,与成矿密切相关的正长花岗岩和闪长岩中锆石均表现为重稀土元素富集、轻稀土元素亏损,正长花岗岩中锆石的∑REE介于(627~1625)×10^(-6),闪长岩中锆石的∑REE介于(345~1439)×10^(-6)。锆石Ti温度计显示正长花岗岩锆石的结晶温度集中在598~810℃;闪长岩锆石结晶温度为651~932℃,正长花岗岩的氧逸度(ΔFMQ+4.25)高于闪长岩(ΔFMQ-1.01)。成矿岩体锆石均形成于封闭的岩浆体系中,主要为岩浆锆石,少量闪长岩中的锆石可能在岩浆晚期遭受了富集轻稀土元素的热液改造。锆石形成构造背景属于大陆岛弧环境。成矿岩体锆石的Ce^(4+)/Ce^(3+)值明显高于区域内不成矿岩体的Ce^(4+)/Ce^(3+)值,其中正长花岗岩锆石中更高的Ce^(4+)/Ce^(3+)值表明,阔库确科矿区内志留系与正长花岗岩发生接触交代形成的矽卡岩中可能有更大的Cu成矿潜力。

印度洋偏暖对春末夏初西天山极端降水的影响研究

利用NOAA(美国国家海洋和大气管理局)气候预测中心的逐日格点降水资料分析了春末夏初(5、6月)天山极端降水时空变化以及印度洋海盆一致模(IOBM)影响极端降水的机制。结果表明:春末夏初天山极端降水变化具有明显的空间差异,西天山地区极端降水显著增加,其他区域极端降水变化不显著。诊断分析和数值模式模拟结果表明,春末夏初西天山地区极端降水增加与同期IOBM正异常促进冷暖气流在西天山地区交汇有关。IOBM正异常,一方面有利于东欧至中亚北部反气旋异常加强,促进冷空气向南输送。另一方面使得印度洋海温非均匀增暖,产生异常垂直环流,其下沉支使阿拉伯海和印度半岛产生反气旋异常,异常反气旋和偏南气流共同促进印度洋暖湿水汽向西天山输送,从而有利于西天山地区极端降水增加。

西天山阿吾拉勒成矿带察汉乌苏铁矿赋矿玄武岩的成因:锆石U-Pb年代学、地球化学及Hf同位素约束

西天山为中亚成矿域的重要组成部分,是我国重要的富铁矿资源基地。察汉乌苏铁矿位于阿吾拉勒成矿带东段,赋存于石炭系大哈拉军山组火山岩中,目前火山岩成因认识还存在较大分歧,通过探讨火山岩成因,为深入找矿及区带研究提供新资料。通过对赋矿玄武岩岩石地球化学分析发现,玄武岩具相对较高Al_(2)O_(3),Na_(2)O,K_(2)O,低MgO,CaO,TiO_(2),里特曼指数(σ)为0.46~3.03,均小于3.3,岩石系列为钙碱性系列;玄武岩富集大离子亲石元素Rb,Th,U,K,亏损高场强元素Nb,Ta,P,Ti;微量、稀土元素分布模式介于OIB和EMORB之间。赋矿玄武岩形成于大陆岛弧火山岩环境。通过对玄武岩锆石U-Pb测年,获得^(206)Pb/^(238)U加权平均年龄为(325.3±2.8)Ma,属早石炭世末期。玄武岩锆石Lu-Hf同位素单阶段模式年龄tMD1为(522.24~642.70)Ma;二阶段模式年龄tMD2为(634.66~830.79)Ma,表明成岩成矿物质来源于亏损地幔并有新元古代基底物质加入。结合区域构造背景认为,察汉乌苏铁矿成矿作用发生于早石炭世末期北天山古洋盆向南侧俯冲和消亡过程地球动力学背景下。

塔北隆起西部地区白垩系碎屑岩油气成藏规律及成藏模式

以岩心观察、物性分析、地球化学分析和三维地震资料为基础,通过单井、连井沉积相分析、地震精细解释及优势砂体识别等方法,从油气来源、油气充注特征、输导体系及储盖组合等4个方面对塔北隆起西部地区白垩系碎屑岩油气成藏规律及模式进行了研究。研究结果表明:(1)研究区白垩系油气具有“陆源”特征,石油主要来自库车坳陷三叠系湖相烃源岩,天然气主要来自库车坳陷侏罗系煤系烃源岩,区内深部三叠系海相烃源岩贡献极小。(2)研究区白垩系油气充注持续时间长,成藏时期晚,早期生油,晚期生气,油成藏于中新世(4.0~22.0 Ma),气成藏于晚中新世—中上新世(3.5~11.0 Ma),受2.6~3.5 Ma构造隆升影响,气藏成熟度较低。(3)研究区油气输导体系较发育,天山南地区以断裂和不整合面作为主要运移通道;顺北地区以不整合面和巴西改组薄层砂体为运移通道。(4)研究区储层主要发育在舒善河组和巴西改组,含砂率一般高于60%,与其上部发育的连续泥岩构成良好的储盖组合;优质储层的分布受沉积相控制,天山南地区优质储层主要分布在扇三角洲前缘砂坝及滩坝,顺北地区优质储层主要分布在辫状河三角洲前缘朵体,目前探井未钻遇朵体最高部位,油气显示相对较差;顺北地区储层物性更佳。(5)研究区天山南与顺北地区因断裂活动强度及储盖组合特征存在差异造成了二者的油气藏类型不同,前者以低幅度构造、构造-岩性复合油气藏为主,后者以规模较小的岩性油气藏为主。

西天山古生代铜金多金属矿床类型、特征及其成矿地球动力学演化

根据铜金矿床的含矿主岩和成矿作用方式 ,西天山的铜矿床主要可划分为 3种类型 :斑岩型、夕卡岩型和火山热液型 ;金矿床可划分为 2种类型 :浅成低温热液型和斑岩型。研究区从北到南可划分为 3条东西向的成矿带 :1阿拉套—科古琴铜多金属成矿带 ,分布着与中元古界灰岩和海西中期中酸性浅成侵入岩有关的斑岩 -夕卡岩铜矿、与海西中期酸性浅成侵入岩有关的斑岩型铜矿 ;2博罗科洛金多金属成矿带 ,分布着与下石炭统中酸性火山碎屑岩和中—基性熔岩有关的浅成低温热液型金矿、与海西中期中酸性浅成侵入岩有关的斑岩型金矿 ;3阿吾拉勒铜银多金属成矿带 ,分布着与二叠纪陆相中基性火山岩有关的火山热液型铜矿、与海西晚期中酸性浅成侵入岩有关的斑岩型铜矿。通过对西天山古生代的地球动力学演化探讨 ,认为上述 3条成矿带对应的大地构造单元分别为阿拉套—科古琴晚古生代岛弧带、博罗科洛晚古生代弧后盆地和阿吾拉勒二叠纪裂谷带。