FHA结构域蛋白TagH对霍乱弧菌肠道定植能力及致病力的影响

目的探究FHA结构域蛋白TagH对非O1/非O139群霍乱弧菌肠道定植能力和致病力的影响,并探讨这种影响是否依赖于溶血素HlyA和蛋白酶PrtV的表达。方法通过生长曲线实验测定各菌株的生长速率。取CD1乳鼠和CD1小鼠各分为PBS阴性对照组、WT菌株感染组、ΔtagH菌株感染组、ΔtagHΔhlyA菌株感染组和ΔtagHΔprtV菌株感染组,通过乳鼠肠道定植实验分析各菌株的肠道定植能力;通过小鼠灌胃感染实验测定各菌株感染组小鼠外周血白细胞数量以及IL-6、IL-8和TNF-α水平;观察各菌株感染组小鼠回肠组织病理损伤及7 d的生存情况。结果细菌生长曲线实验发现,各菌株的生长速度基本一致并无明显差异。乳鼠肠道定植实验发现,与WT菌株相比,ΔtagH菌株的肠道定植能力增强(P<0.01),ΔtagHΔhlyA菌株的肠道定植能力较ΔtagH菌株进一步增强(P<0.05),ΔtagHΔprtV菌株的肠道定植能力弱于ΔtagH菌株(P<0.05)。小鼠灌胃感染实验发现,与WT菌株相比,ΔtagH菌株的白细胞数升高(P<0.05)且肠组织损伤更严重,ΔtagHΔhlyA菌株的白细胞数较ΔtagH菌株明显下降(P<0.05)且几乎没有肠组织损伤,ΔtagHΔprtV菌株感染现象与ΔtagH菌株相似。WT菌株感染组、ΔtagH菌株感染组、ΔtagHΔhlyA菌株感染组和ΔtagHΔprtV菌株感染组的小鼠生存率分别为62.5%、75%、100%和75%。结论TagH抑制霍乱弧菌的肠道定植能力和致病力,其调控作用主要依赖于霍乱弧菌溶血素HlyA,而蛋白酶PrtV的作用不明显。

新疆阿尔金西段瓦石峡南锂铍稀有金属矿成矿背景与勘查进展

锂、铍等稀有金属矿产是重要的战略矿产资源。近年来,在阿尔金地区发现了多处稀有金属伟晶岩型矿床,已成为我国一处新的稀有金属成矿带,但调查研究水平总体较低。通过对阿尔金造山带的成矿动力背景的讨论,得出阿尔金造山带的稀有金属成矿作用涵盖了多个不同的造山运动构造演化阶段,证明该区域具备良好的稀有金属成矿条件,并具有巨大的找矿潜力。通过对位于阿尔金西段的瓦石峡南锂铍稀有金属矿进行勘查评价,发现其具有大型远景:瓦石峡南锂铍稀有金属矿体主要赋存于绿片岩相-角闪岩相变质岩系中的伟晶岩脉中,矿床类型为花岗伟晶岩型稀有金属矿床;已有勘查成果显示此矿床目前推断的稀有金属资源量达到中型以上矿床规模,并且随着勘查工作的进行,在深部及外围还有极大增储空间。研究成果对在阿尔金造山带内寻找同类型矿床具有借鉴意义。

柴北缘骆驼泉剖面新生代地层磁组构特征及其构造意义

青藏高原东北部新生代构造演化对理解高原隆升和变形模式具有重要意义,而目前对于该地区挤压应力方向转变过程仍存在很大争议.本文对柴北缘逆冲带北西部骆驼泉剖面新生代地层开展系统磁组构(本文特指磁化率各项异性)研究,以揭示该地区挤压应力方向的转变特征.系统岩石磁学结果表明,骆驼泉剖面新生代样品中主要磁性矿物是顺磁性组分和赤铁矿以及少量磁铁矿.通过对磁组构特征分析及其与古水流方向对比表明,骆驼泉剖面新生代地层磁组构主要为初始变形磁组构,可用于指示沉积成岩时期的挤压应力方向.磁组构结果揭示,骆驼泉地区挤压应力方向在上干柴沟组下部沉积时期为NNE-SSW向,而上干柴沟组上部和油砂山组沉积时期转变为NE-SW向.结合柴北缘逆冲带已有磁组构结果指出,该地区早期N-S向或NNE-SSW向挤压应力可能与印度—欧亚板块早新生代以来近N-S向碰撞挤压过程有关,指示印度—欧亚碰撞的挤压应力自下干柴沟组下部沉积时期就已传播至高原东北部地区;而后期NE-SW向挤压应力方向与该地区现今GPS揭示的上地壳运动方向一致,可能与该时段高原东北部巨型走滑断裂构造体系(尤其是阿尔金断裂)有关.此外,柴北缘逆冲带新生代挤压应力方向转变在其北西部起始于上干柴沟组下部沉积时期,而南东部起始于上油砂山组下部沉积时期,与地震反射剖面揭示的断裂活动等地质证据共同揭示柴北缘逆冲带新生代的构造活动自靠近阿尔金断裂的北西部向南东部传播和扩展.综合分析青藏高原东北部地区挤压应力方向转变和其他地质证据发现,挤压应力方向转变显示出自柴北缘逆冲带北西部向东、西和南向扩展特征,与阿尔金断裂在上干柴沟组下部-上油砂山组下部沉积时期剪切应力集中于断裂本身,而上油砂山组下部沉积以来开始散布于高原东北部内部地区的两阶段走滑活动相关.

阿尔金山喀拉大湾地区早古生代火山岩岩石学特征、U-Pb年龄及构造环境特征

阿尔金山喀拉大湾地区出露一套海相火山岩,据火山岩组构特点及岩性组合划分出6个喷发韵律、3个喷发亚旋回、1个火山喷发旋回。通过对铅锌赋矿层顶底板晶屑凝灰岩进行锆石U-Pb测年,获得年龄为487.9~489.8 Ma,时代为晚寒武—早奥陶世。与铅锌矿有关的火山岩主要为钙碱性高钾英安岩、流纹岩类火山岩,岩石地球化学具Nb,Ta,Sr,Hf,Y相对亏损和Ba,Th,Zr,U相对富集及形成于俯冲带环境的钙碱性火山岩微量元素地球化学特征,即轻稀土富集,Eu极度亏损。结合前人研究成果,认为大地构造环境属拉张弧后盆地。

(TAGH)ClO_4的结构、热力学及感度性能

以三氨基胍和高氯酸为原料,合成了三胺基胍高氯酸盐(TAGH)ClO4)。利用X-射线单晶衍射仪测定了其晶体结构。结果表明,晶体属于单斜晶系,空间群为P2(1)/c,晶胞参数为a=1.0213(11)nm,b=1.4869(15)nm,c=1.0936(11)nm,β=102.91(2)°。该化合物的分子式为CH9ClN6O4是由三胺基胍离子和高氯酸根结合形成的离子化合物,分子中含有大量的氢键。利用元素分析、红外光谱、DSC、TG-DTG等方法对标题化合物的组成和热力学行为进行了表征,结果表明,在10℃/min线性升温速率下标题化合物在457.03℃时质量损失达到99.7%。感度实验结果表明,标题化合物具有较低的摩擦感度,在撞击和火焰作用下均不发火。

阿尔金西段库木塔什萤石矿床成矿流体特征及成矿机制探讨

库木塔什萤石矿床位于阿尔金西段卡尔恰尔超大型萤石矿带内,是近年来新发现的一处大型萤石矿床,矿体以萤石-方解石脉型为主,伴生含锂带云母,产于古元古界阿尔金岩群的NE向与近EW向断裂中。目前,关于矿床成矿流体特征与成矿机制的研究较为薄弱。本研究以不同成矿阶段萤石和方解石的流体包裹体为研究对象,开展流体包裹体岩相学、显微测温、激光拉曼光谱和H、O同位素研究。成矿过程可划分早阶段(Ⅰ)、晚阶段(Ⅱ)两个阶段。早阶段形成块状矿石,主要发育富气两相水溶液包裹体和CO_(2)三相包裹体,均一温度为225.1~410.8℃,盐度为5.20~9.63 wt%NaCl_(eqv),密度为0.25~0.76 g/cm^(3);晚阶段形成角砾状、网脉状矿石,主要发育富液两相和富气两相水溶液包裹体,均一温度为117.2~347.8℃,盐度为0.53~12.73 wt%NaCl_(eqv),密度为0.40~0.91 g/cm^(3)。包裹体的液相成分以H_(2)O为主,含有少量CO_(2),气相成分以CO_(2)为主,含少量的CH4、N2、H_(2)及H_(2)S等。成矿早期流体为中高温、中低盐度、低密度的NaCl-H_(2)O-CO_(2)热液体系,成矿晚期流体为中低温、低盐度、低密度的NaCl-H_(2)O-CO_(2)热液体系。H、O同位素研究结果表明,成矿流体来源于岩浆热液和大气降水的混合。成矿早期萤石的沉淀机制主要为岩浆热液和大气降水混合以及水-岩反应,晚期进一步发生流体混合作用,致使温度降低,形成角砾状及网脉状矿石。库木塔什萤石矿床属岩浆热液充填型脉状萤石矿床。

阿尔金西段库木塔什萤石矿床成因:磷灰石U-Pb年龄、原位Sr-Nd同位素、地球化学约束

近年来,阿尔金西段取得萤石找矿重大突破,相继发现卡尔恰尔和库木塔什等矿床,但成矿时代和成矿机制研究薄弱。笔者选取库木塔什矿床与萤石密切共生磷灰石为研究对象,开展原位U-Pb定年、Sr-Nd同位素及地球化学分析,以探讨萤石矿成矿时代及矿床成因。磷灰石常呈自形-半自形结构,表面均匀,单偏光下近乎透明,主要与萤石、方解石、带云母、氟碳铈矿等矿物共生。结果显示,磷灰石U-Pb同位素年龄为(448±27)Ma,成矿作用与碱长花岗岩侵入活动密切相关,均为晚奥陶世构造-岩浆活动产物。磷灰石中F含量为4.20%~5.12%,Cl含量小于0.02%,极低的Cl含量表明出溶的流体Cl含量较低。磷灰石稀土元素含量较高(908×10^(-6)~2164×10^(-6)),稀土配分曲线显示强烈Eu负异常和Ce正异常,且与萤石、方解石、碱长花岗岩有明显的一致性,推测与岩浆-热液阶段大量流体出溶密切相关。磷灰石的^(87)Sr/^(86)Sr值为0.70913~0.71047,^(143)Nd/^(144)Nd值为0.51138~0.51153,εNd(t)值为-13.3~-10.3,表明成矿物质具有壳幔混合特征。综合研究表明,阿尔金西段萤石成矿时代为奥陶纪,与同期碱长花岗岩密切相关,形成于后碰撞伸展阶段,成矿流体来源于碱长花岗岩的熔体-流体演化,为岩浆热液充填型矿床。

阿尔金卡尔恰尔地区超大型萤石成矿带地质特征与流体性质

1地质特征卡尔恰尔超大型萤石矿带位于青藏高原北缘,大地构造位置处于塔里木地块与柴达木地块之间,构造单元划分属于阿中地块。卡尔恰尔超大型萤石矿带内自东向西依次分布小白河沟、卡尔恰尔西南、拉依旦北、库木塔什和托盖里克等一系列大中型萤石矿床。这些矿床主要受控于北东向区域断裂及北东东、东西向次级断裂.

阿尔金断裂东段的河流阶地累积位错

阿尔金断裂带是青藏高原北缘的大型左旋走滑断裂,其东段与NW走向的祁连山逆冲断裂带斜接。文中基于无人机摄影测量技术(SfM)获得的高分辨率影像数据,对阿尔金断裂带东段长约127km的段落开展了详细解译,并对其中9个典型河流阶地位错点进行测量与统计。沿阿尔金断裂带向E,晚第四纪左旋累积位移总体呈衰减趋势,且以断裂带东侧NW走向斜接逆冲断裂或逆冲走滑断裂为界,其累积位错量在同一断裂段内大致相当,但相邻断裂段之间表现为阶梯状递减,指示了斜接断裂的构造转换关系及可能的地震破裂分段作用,为阿尔金断裂带活动性分段研究与潜在发震能力评价提供了依据。

The Tashisayi nephrite deposit from South Altyn Tagh, Xinjiang,northwest China

The Tashisayi nephrite deposit is located in South Altyn Tagh.in Qiemo County,Xinjiang Province,northwest China.It is a recent discovery in the vast,well-known Kunlun-Altyn nephrite belt distributed along the south of the Tarim Basin,producing more than half of the nephrite from the whole belt in 2017.Field investigations revealed that it is a dolomitic marble-related(D-type)nephrite deposit,but little is known about its age of formation and relationships between the granites and marble.Here we report field investigations,petrography of the neph rite,as well as petrography,geochemistry,geochronology of the zoisite-quartz altered intrusive rock and adjacent granites.An A-type granite is identified with a SHRIMP U-Pb zircon age of 926±7 Ma,suggesting it was emplaced in an extensional tectonic environment at that time.The altered intrusive rock has a cluster of U-Pb zircon age of 433±10 Ma.with similar trace element features to the A-type granite,suggesting it was formed in an extensional regime at this later time.Nephrite formed because of the metasomatism of dolomite marble by hydrothermal fluids.It is inferred that Ca^2+was released from the dolomitic marble by metasomatism forming Ca-rich fluids,which caused alteration of both the intrusive rocks(6.00-8.22 wt.%CaO)and granite(1.76-3.68 wt.%CaO)near the nephrite ore bodies.It is also inferred that Fe^2+from the granite migrated towards the dolomite marble.The fluids gave rise to the formation of Ca-minerals.such as zoisite,in the nephrite and altered intrusive rock,and epidote in the granite.Based on the contact relationships.similarity in hydrothermal processes,and consumption of Ca^2+,the Tashisayi nephrite is considered to have formed at the same time as the alteration of the intrusive rocks,i.e.~433 Ma.The geochronological similarity(~926 Ma.433 Ma)of South Altyn and North Qaidam may suggest that tectonically they belong to one single complex in the past,which was offset by the Altyn Tagh fault(ATF).The similar formation ages of the nephrites from Altyn Tagh(433 Ma)and the previously studied areas of West Kunlun(378-441 Ma)and East Kunlun(416 Ma)indicate that these nephrites formed during the closure of Proto-Tethys and in the accompanving post-collisional.extensional environment.

Timing,Displacement and Growth Pattern of the Altyn Tagh Fault:A Review

The Altyn Tagh Fault（ATF） is the longest, lithospheric scale and strike-slip fault in East Asia. In the last three decades, multidisciplinary studies focusing on the timing, displacement of strikeslip and growth mechanics of the ATF have made great progresses. Most studies revealed that the ATF is a sinistral strike-slip and thrust fault, which underwent multiple episodes of activation. The fault is oriented NEE with a length of 1600 km, but the direction, timing of activity and magnitude of its extension eastward are still unclear. The AFT was predominately active during the Mesozoic and Cenozoic, in relation to the Mesozoic collision of the Cimmerian continent（Qiangtang and Lhasa block） and Cenozoic collision of India with Asia. The AFT strike-slipped with a left-lateral displacement of ca. 400 km during the Cenozoic and the displacement were bigger in the western segment and stronger in the early stage of fault activation. The slip-rates in the Quaternary were bigger in the middle segment than in the western and eastern segment. We roughly estimated the Mesozoic displacement as ca. 150-300 km. The latest paleomagnetic data showed that the clockwise vertical-axis rotation did not take place in the huge basins（the Tarim and Qaidam） at both side of ATF during the Cenozoic, but the rotation happened in the small basins along the ATF. This rotation may play an important role on accommodating the tectonic deformation and displacement of the ATF. Even if we have achieved consensus for many issues related to the ATF, some issues still need to be study deeply; such as：（a） the temporal and spatial coupling relationship between the collision of Cimmerian continent with Asia and the history of AFT in the Mesozoic and（b） the tectonic deformation history which records by the sediments of the basins within and at both side of AFT and was constrained by a high-resolution and accurate chronology such as magnetostratigraphy and paleomagnetic data.

Late Quaternary Tectonic Deformation of the Eastern End of the Altyn Tagh Fault

The Quaternary activity of the faults at the eastern end of the Altyn Tagh fault, including the Dengdengshan-Chijiaciwo, Kuantanshan and Heishan faults, was studied on the basis of interpretation of satellite images, trenching, geomorphologic offset measurements and dating. The Altyn Tagh fault has extended eastwards to Kuantanshan Mountain. The left-slip rates of the Altyn Tagh fault decreased through the Qilianshan fault and were transformed into thrust and folds deformation of many NW-trending faults within the Jiuxi basin. Meanwhile, under NE-directed compression of the Tibetan plateau, thrust dominated the Dengdengshan-Chijiaciwo fault northeast of the Kuantanshan uplift with a rate lower than that of every fault in the Jiuxi basin south of the uplift, implying that tectonic deformation is mainly confined to the plateau interior and the Hexi Corridor area. From continual northeastward enlargement of the Altyn Tagh fault, the Kuantanshan uplift became a triangular wedge intruding to the east, while the Kuantanshan area at the end of this wedge rose up strongly. In future, the Altyn Tagh fault will continue to spread eastward along the Heishan and Jintananshan faults. The results have implications for understanding the propagation of crustal deformation and the mechanism of the India-Eurasian collision.

NORMAL-SLIP ALONG THE NORTHERN ALTYN TAGH FAULT, NORTH TIBET

The east\|west striking Northern Altyn Tagh Fault, about 240km long between Bashkaogong (90°E, 39°25′N) and Lapeiquan (92°15′E, 39°25′N), was previously mapped as a north\|dipping thrust, juxtaposing late Archean\|Mesoproterozoic gneisses in the hanging wall over Paleozoic volcanics, plutons, turbidite, and melange complexes in the footwall. In order to estimate the total magnitude of slip along the Cenozoic Altyn Tagh fault, we conducted geologic mapping along four traverses across the Jinyan Shan where the fault lies. Our field observations suggest that the fault is south\|dipping, with dip angles varying from <25° in the east to about 40° in the west. The eastern fault zone exhibits mylonitic fabrics, whereas the western fault zone is characterized by cataclastic deformation. Kinematic indicators in the ductily deformed mylonitic shear zone consistently show a top\|to\|the\|south sense of shear, suggesting that the Northern Altyn Tagh fault is a south\|dipping normal fault, not a north\|dipping thrust.. The ductile shear zone is typically 30～40m thick, consisting of highly sheared metasediments (pelite and marble), granites, and granitic veins.The latter are systematically cut by small\|scale, south\|dipping ductile normal faults with displacements between 10s of cm to several meters, forming spectacular asymmetric boudinages in the sheared meta\|pelite matrix.The minimum displacement along the detachment is about 20km, as measured by the north\|south width of the exposed footwall gneisses. We renamed the Northern Altyn Tagh Fault in the Jinyan Shan region as the Lapeiquan detachment fault to avoid confusion with other east\|west trending Cenozoic faults to the west along the northern edge of the Altyn Tagh range (e.g., the Cenozoic Jianglisai fault near Qiemo), collectively known as the Northern Altyn Tagh fault system (see Cowgill et al., Geology,in press). The lower age bound of the Lapeiquan fault is Ordovician, as the fault cuts Ordovician volcanics and plutons in its hanging wall. As the Ordovician volcanic rocks are folded together with Carboniferous marbles and Jurassic sedimentary strata, it is likely that normal faulting along the Lapeiquan detachment postdates the Jurassic. The Lapeiquan detachment fault is covered by Quaternary sediments of the Tarim basin in the west, and is apparently truncated by the Cenozoic left\|slip Altyn Tagh fault to the east as indicated by regional geologic maps. If true, this relationship implies that the Lapeiquan fault predates the Cenozoic Altyn Tagh fault. The apparent truncational relationship between the Lapeiquan fault and the Altyn Tagh fault posses an important question: where is the counterpart of the Lapeiquan fault south of the Altyn Tagh fault? Preliminary mapping in the Yema Nan Shan south of the Altyn Tagh fault reveals a fragment of a low\|angle mylonitic shear zone, which is interpreted as a detachment fault because it puts lower\|grade meta\|pelite over higher\|grade mylonitic quartzite. The correlation of detachment faults in the Yema Nan Shan and the Lapeiquan area would imply an amount of about 280～300km left slip along the Altyn Tagh fault. Alternatively, movement along the Lapeiquan detachment fault could have been synchronous with the development of the Cenozoic Altyn Tagh fault. This interpretation requires no counterpart of the Lapeiquan fault south of the Altyn Tagh fault. Instead, it implies that a major topographic collapse event occurred in the Cenozoic along the northern edge of the Tibetan plateau during movement along the Altyn Tagh fault. On\|going thermochronologic analysis will provide constraints on the age of the detachment fault and a test for the two distinctive hypotheses.

The First Quantitative Slip-Rate Estimated Along the Ashikule Fault at the Western Segment of the Altyn Tagh Fault System

As one of the longest strike-slip fault in Asia,the Altyn Tagh Fault（ATF）defines the northern boundary of the Tibetan Plateau and plays a significant role inaccommodating the deformation resulting from the IndiaAsia convergence.

Deformation at the Easternmost Altyn Tagh Fault: Constraints on the Growth of the Northern Qinghai–Tibetan Plateau

How the Altyn Tagh fault(ATF) extends eastwards is one of the key questions in the study of the growth of the Qinghai–Tibetan Plateau. Detailed fieldwork at the easternmost part of the ATF shows that the ATF extends eastward and bypasses the Kuantan Mountain;it does not stop at the Kuantan Mountain, but connects with the northern Heishan fault in the east. The ATF does not enter the Alxa Block but extends eastward along the southern Alxa Block to the Jintanan Mountain. The Heishan fault is not a thrust fault but a sinistral strike-slip fault with a component of thrusting and is a part of the ATF. Further to the east, the Heishan fault may connect with the Jintananshan fault. A typical strike-slip duplex develops in the easternmost part of the ATF. The cut and deformed Quaternary sediments and displaced present gullies along the easternmost ATF indicate that it is an active fault. The local highest Mountain(i.e., the Kuantan Mountain) in the region forms in a restraining bend of the ATF due to the thrusting and uplifting. The northward growth of the Qinghai–Tibetan Plateau and the active deformation in South Mongolia are realized by sinistral strike-slipping on a series of NE–SW-trending faults and thrusting in restraining bends along the strike-slip faults with the northeastward motion of blocks between these faults.

SEDIMENTARY PROCESS OF THE CENOZOIC BASIN AND ITS RESPONSE TO THE SLIP-HISTORY OF THE ALTYN TAGH FAULT, NW CHINA

The NEE\|striking Altyn Tagh Fault (ATF) has been well known as one major point to know the growth history of the Tibetan plateau. Lots of investigations done since 1970’s were mostly focus on active features, particularly on determining slip, slip rate and their distribution along the fault. However, Cenozoic slip\|history of this fault remains poorly understood, and the age of initiation and total offset are controversial. Several Cenozoic sedimentary basins develop in Suo’erkulinan to Mangya regions (Fig.1). Their sedimentary processes are closely related with the ATF. The studies of the Neogene sedimentary sequences and the reconstruction of the paleo\|geography are essential to establish the displacement history of the fault during Late Cenozoic.Located at the southern side of the ATF, the Suo’erkulinan basin consists of more than 600\|meter\|thick Pliocene Shizigou Formation below and about 120\|meter\|thick Early to Middle Pleistocene Qigequan Formation above according to the 1∶200000 geological map by Xinjiang Province. An obvious erosional surface can be seen on the top of the lower sequence. Sediments in the Shizigou Formation are characterized by 400\|meter\|thick yellow to red cobble\|sized conglomerates in the bottom, up\|grading to sandstones and grey\|green mudstones. This indicated that the sedimentary facies changed from alluvial fan to fluvial fan and sediments became more and more mature. The upper sequence, the Qigequan Formation, corresponds to an alluvial facies series composed of yellow to white cobble\|sized conglomerates intercalated with lenticular sandstones. Paleo\|current indicators showed that the Shizhigou conglomeratic series were sourced from northwest. Well\|developed syn\|sedimentary faults, normal faults mostly inherited from syn\|sedimentary faults, and some striation lineations on the surface indicated transtensional tectonic environment of the strike\|slip faulting.

AGE OF THE ALTYN TAGH STRIKE—SLIP FAULT

A 100～500m\|wide mylonite zone in the Altun Group of Lower Proterozoic age was discovered along the Altyn Tagh strike\|slip fault. The zone is mainly composed of amphibolitic and granitic mylonites. The planar joints of the rocks strike in NE70 and dip steeply (nearly vertical), coincident with the striking of Altyn Tagh fault zone, and their stretched lineations are nearly horizontal. Shear strains are well developed and show sinistral sheared. The amphibolitic and granitic mylonites are most probably the products of deep\|seated melting caused by sinistral strike\|slip shearing as suggested by the evidence below: (1) The migmatization is intensely developed and spatially controlled by the shear zone, and the rock has a set of NNE perspective foliation which is in accord with the direction of the Altyn Tagh strike\|slip fault zone. (2) The recrystallized hornblende aggregate is distributed in band with obvious nebulous texture, indicating the characteristics of anatexis, and the hornblendes are oriented and form the nearly horizontal stretching lineation; some hornblendes have titanite inclusions, and magmatic long\|columnar zircons are in directional arrangement.(3) The banded felsic material is developed, and the plagioclase is characteristic of high\|temperature plastic deformation and shows sinistral shear stain. (4) In mylonites, all the axis C fabric of quartz shows the feature of sinistral shearing and the majority is generally middle to low temperature fabric, but there also exists high temperature fabric, which suggests that high temperature shearing occur in the early stage of strike\|slip deformation and it is characterized by middle to low temperature shearing at the beginning of anatexis or in the late stage of the deformation. (5) On the XZ plane of mylonite and mylonitized rocks, there exists the consistent sinistral shear stain, which suggests the products of the same strike\|slip shearing.Zircons were separated from three samples of mylonitized granitic rocks for age dating. Two groups of zircon were distinguished in morphology: one is elongate prismatic grains, and the other shows slight rounding. Some zoned structure of selected grains were examined by cathodoluminescence. Dating was completed in the SHRIMP laboratory of Stanford University. Fifteen analyses were made on 14 zircon grains. Sample S99\|25 show two obvious two age groups, one is 527～549Ma, and the other is 466～472Ma. Sample S99\|9 contains two age groups either, one is 475～507Ma and the other is 279Ma. Sample S99\|6 shows three groups: ① 528Ma; ② 365Ma and③ 238～243Ma, here the 365Ma is explained as mixture age between the other two age groups according to its exact location in the grain. In summary, from the three samples we found at least three age groups: 507～548Ma; 466～472Ma; 238～243Ma.The ages of 507Ma to 548Ma and 466Ma to 472Ma represent the deformation and metamorphism of Early Paleozoic age, which is most likely correspond to the close of the Qilian Sea and continental subduction and collision reported in recent papers (Yang Jingsui et al., 1998; Zhang Jianxin et al., 1999; Xu Zhiqin et al., 1999). The 238～243Ma most likely represent the formational age of the Altyn Tagh strike\|slip fault, which is consistent with the formational age (200～240Ma) of the large\|scale sinistral strike\|slip fault zone of the South Margin of East Kunlun (Li Haibing et al., 1996), and both can be attributed to the oblique subduction and collision of the Bayan Har terrane with the East Kunlun terrane during Indosinian period.

Tourmaline geochemistry and boron isotopic variations as a guide to fluid evolution in the Qiman Tagh W-Sn belt, East Kunlun, China

The Qiman Tagh W-Sn belt lies in the westernmost section of the East Kunlun Orogen, NW China, and is associated with early Paleozoic monzogranites, tourmaline is present throughout this belt. In this paper we report chemical and boron isotopic compositions of tourmaline from wall rocks, monzogranites, and quartz veins within the belt, for studying the evolution of ore-forming fluids. Tourmaline crystals hosted in the monzogranite and wall rocks belong to the alkali group, while those hosted in quartz veins belong to both the alkali and X-site vacancy groups. Tourmaline in the walk rocks lies within the schorl-dravite series and becomes increasingly schorlitic in the monzogranite and quartz veins. Detrital tourmaline in the wall rocks is commonly both optically and chemically zoned,with cores being enriched in Mg compared with the rims. In the Al-Fe-Mg and Ca-Fe-Mg diagrams,tourmaline from the wall rocks plots in the fields of Al-saturated and Ca-poor metapelite, and extends into the field of Li-poor granites, while those from the monzogranite and quartz veins lie within the field of Li-poor granites. Compositional substitution is best represented by the MgFe_(-1), Al(NaR)_(-1), and AlO(Fe(OH))_(-1) exchange vectors. A wider range of δ^(11)B values from -11.1‰ to -7.1‰ is observed in the wall-rock tourmaline crystals, the B isotopic values combining with elemental diagrams indicate a source of metasediments without marine evaporates for the wall rocks in the Qiman Tagh belt. The δ^(11)B values of monzogranite-hosted tourmaline range from -10.7‰ and-9.2‰, corresponding to the continental crust sediments, and indicate a possible connection between the wall rocks and the monzogranite. The overlap in δ^(11)B values between wall rocks and monzogranite implies that a transfer of δ^(11)B values by anataxis with little isotopic fractionation between tourmaline and melts. Tourmaline crystals from quartz veins have δ^(11)B values between -11.0‰ and-9.6‰, combining with the elemental diagrams and geological features, thus indicating a common granite-derived source for the quartz veins and little B isotopic fractionation occurred. Tourmalinite in the wall rocks was formed by metasomatism by a granite-derived hydrothermal fluid, as confirmed by the compositional and geological features.Therefore, we propose a single B-rich sedimentary source in the Qiman Tagh belt, and little boron isotopic fractionation occurred during systematic fluid evolution from the wall rocks, through monzogranite, to quartz veins and tourmalinite.

THE FORMATION AND EVOLUTION OF ALTYN TAGH FAULT SYSTEM AND ITS RELATIONSHIP TO THE GROWTH OF TIBETAN PLATEAU

One of the focus views of the uplifting of Tibetan Plateau is the growth history of the plateau. This is an unresolved question because of the poor study in north margin, where the ATF (Altyn Tagh Fault) is acting an important role in the growth and deformation of the plateau. The fault links two huge contractional belts, e.g. Qilian Nan Shan and West Kunlun, and merges a series of thrusting\|folding arcs in southeast. Mapping of piercing points, such as unconformities between Cenozoic, Mesozoic and Paleozoic strata, and magmatic arcs, shows left slips of ca. 240km and ca. 550km along the middle and western segments of the ATF. About 140～450km of crustal shortening, approximately the same magnitude as the west segment of the ATF, is deduced from balanced sections in West Kunlun foreland thrusting belt. This implies that left\|slip displacement along the west segment of the ATF was absorbed by the contraction in West Kunlun. The ATF system merged bunches of WNW arcuated fold\|fault belts in Qaidam basin, implying anti\|clockwise rotation. Tertiary and some Lower to Middle Pleistocene strata involved in fold\|fault belts, and dip in ESE due to the uplifting of Altyn Tagh. The newest strata involved in the deformation is more and more younger from south to north, that is, from Lower Pliocene to Middle Pleistocene, showing the uplifting trends from south to north in the SE side of the fault.

LARGEST ALTYN TAGH LITHOSPHERIC SHEAR FAULT IN CENTRAL ASIA

The Altyn Tagh fault (ATF) extending in NEE—SWW direction lying at the northwestern boundary of Qinghai—Tibet plateau is the largest strike\|slip fault in Central Asia. On the basis of recent geologic mapping and detailed study of lithotectonic characteristics for the paleotectonic units at the two sides of the Altyn Tagh Fault ( Altun Mt. to west and the Qilian Mt. to east ) we propose that the paleotectonic units in the Altun Mt. can be correlated with those in the Qilian Mt. assuming 400km left\|lateral displacement for the Altyn Tagh fault. Natural seismic data across the Altun Mt. indicate that the Altyn Tagh fault is a lithospheric shear fault and the lithospheric shearing is probably related to southward intracontinental oblique subduction of the Tarim terrane beneath the Altun Mt.1\ Comparison of the major paleotectonic units at the two sides of the Altyn Tagh fault\;(1) The Alxa\|Dunhuang Massif:The Alxa massif lying at the southern margin of the Sino\|Korean craton consists mainly of an Early Proterozoic basement including high\|grade and middle\|grade metamorphic rocks, which were intruded by granite at 1719Ma. The Paleozoic passive margin sediments is well developed. In the Altun Mt., the Early Proterozoic and late Archean basement of the Duhuang massif includes high\|grade and middle\|grade metamorphic rocks dating 2789Ma (Sm\|Nd method) and 2405Ma (U\|Pb method).