Anticlockwise P-T Path and Zircon U-Pb Dating of HP Mafic Granulites in Yushugou Granulite-Peridotite Complex, Southern Tianshan Mountains, China

The Yushugou HP granulite-peridotite complex is located at east of northern margin of southern Tianshan mountains,China,which consists of granulite unit and peridotite unit mainly.Because of the rare association of

New Ar-Ar Isotopic Ages of the Southern Tianshan Mountains, Kyrgyzstan and their Geological Implications

Objective The Late Paleozoic Southern Tianshan Ocean is usually considered to be the last-closed ocean in the Tianshan Orogeny. However, there is still no consensus if this is indeed the case. Blueschist, eclogite and ophiolite are present in the Atbashi Range, Kyrgyzstan, which are believed to be the relics of the Southern Tianshan Ocean. New data obtained through Ar-Ar isotopic analysis in this research provide reliable chronological restrictions for this problem.

Dual influence of the rejuvenation of Southern Tianshan and Western Kunlun orogen on the Cenozoic structure deformation of Tarim Basin,northwestern China:A superposition deformation model from Bachu Uplift

Based on new high-resolution seismic profiles and existing structural and sedimentary results,a superposition de-formation model for Cenozoic Bachu Uplift of northwestern Tarim Basin,northwestern China is proposed. The model presents the idea that the Bachu Uplift suffered structure superposition deformation under the dual influences of the Cenozoic uplifting of Southern Tianshan and Western Kunlun orogen,northwestern China. In the end of the Eocene (early Himalayan movement),Bachu Uplift started to be formed with the uplifting of Western Kunlun,and extended NNW into the interior of Kalpin Uplift. In the end of the Miocene (middle Himalayan movement),Bachu Uplift suffered not only the NNW structure deformation caused by the Western Kunlun uplifting,but also the NE structure deformation caused by the Southern Tianshan uplifting,and the thrust front fault of Kalpin thrust system related to the Southern Tianshan orogen intrudes southeastward into the hinterland of Bachu Uplift and extends NNE from well Pi1 to Xiaohaizi reservoir and Gudongshan mountain,which resulted in the strata folded and denuded strongly. In the end of the Pliocene (late Himalayan movement),the impact of Southern Tianshan orogen decreased because of the stress released with the breakthrough upward of Kalpin fault extending NE,and Bachu Uplift suffered mainly the structure deformation extending NW-NNW caused by the uplifting of Western Kunlun orogen.

Zircon U-Pb Dating of Yushugou Terrain of High-Pressure Granulite Facies in Southern Tianshan Mountain and Its Geological Significance

The Yushugou terrain of high\|pressure granulite facies in southern Tianshan Mountain is composed mainly of an ophiolite suite. Most selected zircons are round or elliptical in shape, and some are of tetragonal prism with round edges. The granulometric analyses show that they are well sorted in sedimentation. ZrO\-2/HfO\-2 ratios in zircons range from 45 to 57. These characters, together with the petrologic and geochemical characters of plagioclase\|garnet\|orthopyroxenite bearing zircons, indicate that the protolith of plagioclase\|garnet\|orthopyroxenite may be derived mainly from volcanic base surge sedimentary debris in oceanic islands and from clays formed by seafloor weathering. Zircons are simply of pyroclastic debris. The ophiolite formation age of (440±18) Ma and the first\|stage metamorphic age (amphibolite or granulite facies) of (364±5) Ma were obtained with a method of multiple grains in different groups and a method of concordia plot. These ages provide important information on the temporal and spatial occurrence of southern Paleozoic Tianshan Ocean, the subduction rate of the oceanic crust and the formation mechanism of ophiolite of granulite facies.

Seismotectonic Study on the West Part of the Interaction Zone Between Southern Tianshan and Northern Tarim

The interaction zone between southern Tianshan and northern Tarim is located at the northeast side of Pamir. It is a region with high seismicity. We constructed a seismotectonic model for the west part of this zone from geological profiles, deep crust seismic detection and earthquake focal mechanisms data. Based on the synthesized geological features, deep crust structure, and earthquake focal mechanisms, we think that the main regional tectonic feature is that the Tianshan tecto-lithostratigraphic unit overthrusts on the Tarim block. The Tianshan tectonic system includes the Maidan fault and thrust sheets in front of the fault; The Tarim tectonic system includes the underground northern Tarim margin fault, conjugate faults in basement and overthrust fault in shallow. The northern Tarim margin fault is a high angle fault deep in the Tarim crust, adjusting different trending deformation between Tianshan and Tarim. It is a major active fault that can generate large earthquakes. The other faults, such as the Tianshan overthrust system and the Tarim basement faults in this area may generate moderately strong earthquakes with different styles.

Differential Hydrocarbon Accumulation Controlled by Structural Styles along the Southern and Northern Tianshan Thrust Belt

The Kuqa and the Southern Junggar foreland thrust belts, which lie to the southern and northern Tianshan, respectively, were formed under a strong compressional tectonic setting. Due to the differential propagation and deformation under the control of the décollement horizon, the structural deformation styles differ in the Kuqa and Southern Junggar thrust belts. Imbricated stacking is developed in the Kuqa thrust belt, forming a piggyback imbricated pattern of faulted anticline and fault-block structural assemblage dominated by salt structures. In contrast, wedge-shaped thrusts are developed in Southern Junggar, mainly forming vertical laminated patterns of multi-wedge-structure stacks strongly influenced by the décollement horizons. The different deformation patterns and structural styles of the north and south of Tian Shan control the contrasting characteristics of hydrocarbon accumulation in the foreland thrust belts of the Kuqa and the Southern Junggar thrust belts, including the variance in the hydrocarbon trap types, pathway systems and hydrocarbon-bearing horizons. Proven by the hydrocarbon accumulation research and exploration achievements, recent exploration targets should focus on sub-salt piggyback imbricated structural patterns in the Kuqa and the deep laminated patterns in the Southern Junggar thrust belt.

Zircon U-Pb SHRIMP ages of high-pressure granulite in Yushugou ophiolitic terrane in southern Tianshan and their tectonic implications

Zircons from two high-pressure granulite samples from the Yushugou ophiolitic terrane, southern Tianshan have been investigated by cathodoluminescence, LAICPMS and ion microprobe (SHRIMP) for their internal textures, trace elemental compositions and in situ dating. Theweighted mean ages of these two samples are 392±7 and 390±11 Ma, respectively, representing the granulite-facies metamorphic age of the ophiolitic terrane, and indicating that the southern Tianshan ocean initiated its northward subduction since the early Devonian.

Paleozoic Accretion-Collision Events and Kinematics of Ductile Deformation in the Eastern Part of the Southern-Central Tianshan Belt, China

The Tianshan range could have been built by both late Early Paleozoicaccretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture ismarked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphicrelics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanicarc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along withunconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation.The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductileshearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductiledeformation, and the later deformation, a dextral strike-slip tectonic process, occurred during theLate Carboniferous-Early Permian. Early Carboniferous molasses were deposited unconformably onpre-Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early orogeny.The large-scale ductile strike-slip along the Aqqikkudug-Weiya zone was possibly caused by thesecond tectonic event, the Hercynian collision between the northern Tarim block and the southernSiberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this EarlyPaleozoic deformation belt. Results of geometric and kinematic studies suggest that the primaryframework of the Southern-Central Tianshan belt, at least the eastern part of the Tianshan belt, wasbuilt by these two phases of accretion events.

Variscan terrane of deep-crustal granulite facies in Yushugou area, southern Tianshan

The Yushugou terrane of deep-crustal granulite facies in southern Tianshan consists of two parts, granulite and metaperidotite. The whole terrane is a metamorphism of (high-pressure) granulite facies, and typical mineral associations are: Gt-Cpx-Pl-Tit-Ilm (±Qz) (silica-saturated and oversaturated mafic rocks), Gt-Ky (pseudomorph)-Pl-Ru-Ilm±Qz (metapelitic rocks) and Spi-Opx-Cpx-Ol (meta-ultramafic rocks). The peak-stage P-T conditions are 795—964℃, 0.97—1.42 GPa, which are obtained with mineral chemistry, assemblage analyses and P-T estimation. The Sm-Nd isochron age of peak-stage metamorphic minerals is (315±3.62) Ma. All of these indicate that the terrane is a deep-crustal body, which subduets to the depth of 40—50 km in the middle late-Paleozoic, undergoing metamorphism of (high-pressure) granulite facies, and exhumed again to the surface by tectonic uplifting.

高寒山区季节冻土冻融特征参数变化及其影响因素——以天山南坡为例

季节冻土在高寒山区广泛分布,其冻融过程会对水文水资源和生态环境产生深刻影响。研究气候变化背景下高寒山区季节冻土冻融特征参数变化及影响机理,可为高寒山区水资源管理和生态保护提供科学依据。本文选择天山南坡作为研究区,基于13个气象站点1958年以来季节冻土冻融参数(最大冻深、冻结期、始冻日、解冻日)、气温、地表温度、降雨和积雪等数据,使用空间分析和多元线性回归统计等方法对冻融参数的时空变化特征进行分析,量化不同气候因素对季节冻土冻融变化的影响权重。结果表明,季节冻土最大冻深在(48.5±11.4)~(96.8±8.5)cm之间,冻结天数在(102±10)~(141±14)d之间,多年平均始冻日在11月7日至19日之间,多年平均解冻日在3月1日至28日之间。1950年代至2010年代期间,始冻日逐渐推迟,解冻日逐渐提前,冻结天数缩短。空间分布上,最大冻深有“海拔高,最大冻深大”的规律;空间变化趋势上,最大冻深在研究区中部显著增加;冻结天数在研究区内大范围显著缩短。季节冻土冻融变化与气温相关性最强,温度(气温和地表温度)是季节冻土冻融变化的主导因子。定量评价发现,气温影响占比(24.1±3.6)%,地表温度影响占比(12.1±3.1)%,降雨影响占比(9.6±1.7)%,积雪影响占比(5.1±1.5)%。

Study on Snow Line in the Tianshan Mountains Based on MODIS Image

Using MOD10A1,temperature and precipitation of 21 meteorological observatories and HJ-1 / CCD data from July to September during 2002- 2013,this paper takes the Tianshan Mountains as the study area to analyze the space distribution characteristics of snow line and its influencing factors. The results show that the snowline distribution of southern and northern slopes of the Tianshan Mountains is that it is high in the south and east but low in north and west; the snowline of southern slope is sparse and there is a small spatial gradient change; the snow line is dense in the middle of northern slope,and the spatial gradient change is not large. Through the analysis of the whole study area,it is found that the correlation coefficient between snow line altitude and temperature is 0. 159,and the partial correlation coefficient between them is- 0. 212; the correlation coefficient between snow line altitude and precipitation is- 0. 668,and the partial correlation coefficient between them is- 0. 676. Precipitation is the dominant factor that affects the distribution of snow line of southern and northern slopes of the Tianshan Mountains.

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。

天山南麓绵羊沙门菌耐药基因检测及耐药性分析

为了研究天山南麓地区绵羊沙门菌(Salmonella)耐药性及耐药基因的流行现状,本试验从天山南麓地区选择10个采样点采集绵羊粪样进行沙门菌分离鉴定,采用K-B药敏纸片法进行药敏试验,并通过PCR法检测耐药基因。结果表明:共分离出67株沙门菌,分离株对青霉素、磺胺异噁唑耐药率较高,分别为98.51%、68.66%,其次为氨苄西林、链霉素、阿莫西林、四环素,耐药率分别为49.25%、47.76%、46.27%和43.28%,分离株多重耐药率为55.22%。分离株耐药基因中KN和sul1检出率最高,分别为100.00%和98.51%,aadA1、aph(3')-IIa、TEM、ant(3'')-Ia和CTX-M的检出率均在50%以上,分别为82.09%、71.64%、62.69%、58.21%和50.75%。药敏试验和耐药基因检测结果的综合分析表明天山南麓地区沙门菌的耐药性及耐药基因流行状况较为严重,呈区域性流行。

准噶尔—北天山盆山过渡带断裂系统发育特征及地质意义

准噶尔—北天山盆山过渡带自古生代以来经历了多期构造运动的叠加改造,断裂系统错综复杂,相互叠加,改造着褶皱构造的形态,控制着油气成藏过程。目前对盆山过渡带断裂体系的展布特征、发育规模和复杂程度缺少系统研究。本文综合运用野外踏勘、地震资料解释,结合断层像素长度、分形维数等定量分析方法,对研究区断裂系统发育特征和差异性进行了系统分析。研究认为:1)盆山过渡带断裂整体呈NWW向展布;以挤压构造样式为主,其次为走滑构造样式,反映研究区整体受控于压扭应力背景;北天山内部断裂构造样式、发育数量及规模多于山前带,反映了北天山内部地质构造和应力场的复杂性。2)盆山过渡带断裂发育具有很好的分形分维特征,山前带断裂分形维数值为1.207,北天山内部断裂分形维数值为1.485,表明北天山内部断裂构造发育和复杂程度明显高于山前带。3)盆山过渡带断裂的发育程度和复杂变形程度整体表现为由南向北、由东向西逐渐减弱,南北方向的差异与地层能干性及构造应力在传递过程中不断损耗,逐渐减弱有关;东西方向的差异与区域走滑断裂的调节和逆冲推覆过程中主应力面并非保持水平而是向东发生倾斜有关。研究成果对了解研究区应力场分布和指导山前带油气地质勘探具有重要意义。

天山南坡山前荒漠草地植物群落分布对环境因子的响应——以拜城县为例

为探明天山南坡拜城县山前荒漠草地植物群落分布对地形与土壤因子的响应,本研究选取了拜城山前荒漠草地典型区域进行调查,采用优势度法和典范对应分析(Canonical correspondence analysis,CCA)法,研究山地荒漠草地植物群落分布与地形和土壤因子之间的关系。结果表明:(1)不同调查样点灌木层和草本层物种多样性存在差异,东坡调查样点Shannon-Wiener指数、Pielou指数和Simpson指数均表现为灌木大于草本,西坡和北坡调查样点Shannon-Wiener指数、Pielou指数和Simpson指数均表现为草本大于灌木;(2)典范对应分析法分析结果表明,地形因子对植物群落的影响大小顺序为:坡向(SA)>坡度(SG)>坡位(SP),土壤因子对植物群落的影响大小为:30~100 cm土层土壤水分(SMC-2)>土壤总孔隙度(STP)>0~30 cm土层土壤水分(SMC-1)。地形和土壤因子对不同植物群落的形成具有一定的筛选作用,30~100 cm土层土壤水分和坡向是影响天山南坡拜城县山前荒漠草地植物群落分布的关键因子。

南天山库米什地区孔雀沟岩体年代学、岩石成因及地质意义

库米什地区孔雀沟岩体位于南天山造山带,岩性主要为正长花岗岩,其成岩年代学、成因类型对于限定南天山洋的闭合时限具有重要意义。通过锆石U-Pb定年、全岩分析,对孔雀沟岩体进行研究。锆石U-Pb定年结果显示,孔雀沟岩体成岩年龄为295.1~296.5 Ma,属于早二叠世岩浆活动产物。岩相学与元素组成表明,孔雀沟岩体具有高分异I型花岗岩特点,具体表现为:①低w(Zr)/w(Hf)值(19~26);②较低的Zr饱和温度(749℃~802℃);③发育角闪石。综合分析认为,在早二叠世南天山洋已经闭合,孔雀沟岩体形成于后碰撞环境。此外,孔雀沟岩体岩石地球化学特征与区内同时代的矽卡岩型钨矿化成矿岩体特征相似,表明其具有一定的钨找矿潜力。

南天山花岗岩类的年代学、岩石学、地球化学及其构造环境

在南天山褶皱带，分布有大量的花岗岩类岩石。按照由老到新的侵位顺序，岩石类型依次为：闪长岩、似斑状花岗岩、二云母花岗岩和碱长花岗岩。精确的锆石Ｕ－Ｐｂ法研究证明，它们形成于石炭纪末期至早二叠世末期。闪长岩、似斑状花岗岩的岩相学和岩石化学具有Ｉ型花岗岩的特征，而二云母花岗岩充分表现了Ｓ型花岗岩的岩相学和岩石化学特征。与洋中脊花岗岩相比，它们不同程度地富集Ｋ２Ｏ、Ｒｂ、Ｔｈ而贫于Ｔａ、Ｎｂ、Ｚｒ，显示了碰撞造山阶段花岗岩的地球化学特征。碱长花岗岩主要由钾长石、钠长石、石英和富羟铁云母组分的黑云母组成。它们普遍具有高的ＳｉＯ２、Ｎａ２Ｏ＋Ｋ２Ｏ、Ｎｂ、Ｙ、ＲＥＥ（Ｅｕ除外）丰度和Ｆｅ／Ｍｇ比值，以及低的ＣａＯ、ＴｉＯ２、Ｓｒ、Ｂａ、Ｅｕ丰度。从而，系统地显示了Ａ２型花岗岩的普遍特征。证明它们形成于后造山垮塌阶段。各种岩石的εＳｒ（ｔ）界于＋３７．７５和＋２１００．７之间，而εＮｄ（ｔ）界于－４．４２和－６．５１之间，证明它们全部源自于陆壳物质的深熔作用。北天山古洋盆于晚石炭世的闭合导致了南天山碰撞造山作用。而在早二叠世末期，更大范围的大陆伸展作用与南天山的后造山垮塌作用同步。

库车和北塔里木前陆盆地与南天山造山带的耦合关系

一个完全发育的陆－陆碰撞造山带往往会形成双前陆盆地。库车前陆盆地和北塔里木前陆盆地构成了南天山造山带的双前陆盆地。前者是中生代南天山造山带陆－陆碰撞造山阶段的原前陆盆地，后者则是新生代南天山造山带大规模陆内逆冲推覆阶段所形成的新前陆盆地。库车前陆盆地被后期的造山作用严重破坏，其楔顶带和前渊带的很大部分都已卷入了后期的造山作用。北塔里木前陆盆地是一个完整的前陆盆地，各沉积带发育齐全。分隔伊犁－中天山地块和塔里木古陆的古南天山洋盆于二叠纪末完全闭合（东部可能早一些），两陆壳地块完全碰撞到一起，库车前陆盆地形成；新生代喜马拉雅造山作用的远程效应导致南天山造山带重新活动，发生陆内造山，形成北塔里木前陆盆地。

南天山榆树沟高压麻粒岩地体锆石U—Pb定年及其地质意义

南天山榆树沟高压麻粒岩地体的主体为一套蛇绿岩。从该地体顶部单元的岩石中分离出的锆石绝大部分为浑圆形或椭球形，少量为两端略圆化的四方柱状晶体；镜下粒度分析结果显示分选良好的典型沉积特征；其ZrO2／HfO2比值在45—57之间。结合岩石的岩石学和地球化学特征，推测斜长石榴苏辉岩的原岩可能主要由来自洋岛的基性火山激浪沉积碎屑和洋底风化产生的粘土组成。所获锆石系单一来源的火山碎屑，故采用分组多颗粒锆石U-Pb同位素定年法，并依谐和图法，获得（440±18）Ma榆树沟蛇绿岩的形成年龄和（364±5）Ma的第一期（角闪岩相或麻粒岩相）变质年龄。该年龄值为确定古生代南天山洋的时、空展布，计算洋壳的俯冲速度，研究麻粒岩相蛇绿岩的形成机制提供了重要依据。

南天山库米什蛇绿混杂岩带中硅质岩的元素地球化学特征及其形成环境

南天山库米什铜花山地区蛇绿混杂岩带不同岩块中的硅质岩高Al2O3和Al2O3／TiO2，Zr、Nb、Hf、Ta和Th与Al2O3等陆源元素具较好正相关性，北美页岩标准化稀土模式呈现无Ce负异常（Ce／Ce＊=1．05～1.33）的典型大陆边缘硅质岩平坦稀土谱型，它们的（La／Ce）SN=0．74～0．98，Ti/V：5．10～122．18，V／Y=0．39～6．03，均与大陆边缘硅质岩值相当，表明这些硅质岩形成在明显受陆源物质影响与大陆边缘密切相关的环境。但不同岩块硅质岩的物源区仍存在一定差异。其中，与泥岩成互层产出的红色硅质岩的Th/Sc=0.56—4．35，具Eu负异常（Eu／Eu＊=0．56～0．71）明显的较陡右倾球粒陨石标准化稀土谱型（LaN／YbN=3．92～7．43），与分异岩浆弧源区特征类似，可能形成在相对近陆缘的弧前盆地，其源区物质主要来自分异岩浆弧。而成夹层产出于基性熔岩中的绿色硅质岩呈现为Eu负异常较弱（Eu／Eu＊=0．72～0．93）右倾较缓的稀土谱型（Lan／Ybn=4．15～6．69），其Th／Sc=0．57～0．87，反映有洋内弧物质加入的影响，因此它们可能形成于相对远离大陆、除有未分异基性程度较高的洋内弧物质输入外，仍受到陆缘物质影响的有限洋盆环境。根据硅质岩晚古生代初的放射虫化石推断，该地区硅质岩在晚古生代初期形成，南天山构造带已进入板块汇聚俯冲消减洋盆萎缩的发展演化阶段。