Reconstruction of the Triassic Tectonic Lithofacies Paleogeography in Qiangtang Region, Northern Qinghai-Tibet Plateau, China

The Triassic petrostratigraphic system and chronologic stratigraphic sketch have been updated and perfected in the Qiangtang area, Qinghai-Tibet Plateau based on the integrated 1：250000 regional geological survey and the latest research progeny. The first finished 1：3000000 Triassic tectonic lithofacies paleogeographic maps in the Qiangtang area shows that the Triassic tectonic unit in the Qiangtang area can been divided into three parts from north to south： northern Qiangtang block; Longmucuo-Shuanghu suture zone; and southern Qiangtang block. The early-middle Triassic tectonic paleogeography in the Qiangtang area is divides into three sub- units： northern Qiangtang passive continental marginal basin （NQPB）, Longmucuo- Shuanghu residual basin （LSRB） and southern Qiangtang residual basin （SQRB）. The NQPB can be subdivided into four paleogeography units： The Tanggula-Zangxiahe shallow and bathyal sea; The Wangquanhe- Yingshuiquan carbonate platform; The Rejuechaka-Jiangaidarina littoral- shallow sea; and Qiangtang central uplift. The above units of The NQPB possess EW trend, geomorphology high in the south and low in the north, the seawater depth northward. The basinal paleo-current direction is unidirectional, and basinal tectonic subsidence center is in accord with the depo-center, located in the Tanggula-Zangxiahe belt, north of the basin. The sedimentation and tectonic evolution of the NQPB are characterized with passive continental marginal basin. The Qiangtang central orogenic denuded area （ancient land） may be as a sedimentary materials source of the NQPB. SQRB can be divided into two units： Duoma carbonate platform and southern Qiangtang neritic-deep sea. The late Triassic tectonic paleogeography in the Qiangtang area is the framework of the ＂archipelagic-sea＂ as a whole, and it may be divided into three sub-units： northern Qiangtang back- arc foreland basin（NQFB）, Longmucuo-Shuanghu residual basin（LSRB） and southern Qiangtang marginal-sea basin（SQMB）. Thereinto, NQFB can be divided into five paleogeography units： the Zangxiahe-Mingjinghu bathyal basin characterized with the flysch; the Tanggula shallow-sea shelf with the fine-clastics; the Juhuashang platform with carbonates; the Tumenggela-Shuanghu coastal- delta with coal-bearing clastics and the Nadigangri- Geladandong arc with volcanics and tuffs. In transverse section, the NQFB fills is wedge-shaped, and the sediments characterized with thicker in north and thinner in south, and with double materials derived from the Ruolagangri orogenic belt in north and the Shuanghu central orogenic belt in south. The late Triassic depocenter of NQFB is located in the middle of the basin, the Yakecuo-Bandaohu-Quemocuo belt, but the subsidence center in the north, the Zangxiahe- Mingjinghu belt, and basinal tectonic subsidence center not concordant with the depo-center. Late Triassic, the SQMB may be divided into three sub-units： Xiaochaka shallow-sea; Riganpeicuo platform~ and South Qiangtang southern bathyal basin. In transverse section, the basement of the SQMB is characterized with low in the northern and southern, but high in the middle; forming wedge shaped sediments with thicker in the north and thinner in the south; the sedimentary materials derived from the Qiangtang central uplift and Nadigangri arcs in north. The late Triassic subsidence centre of the SQMB is located in the northern （Xiaochaka area）, but the depocenter in the southern （Qixiancuo Suobucha area）. The sedimentation and tectonic evolution of the SQMB are characterized with marginal sea.

Analysis of the Cooling Mechanism of a Crushed Rock Embankment in Warm and Lower Temperature Permafrost Regions along the Qinghai-Tibet Railway

Based on data monitored in situ and theoretical analysis,the characteristics of the temperature field and mechanism of thermal conduction of a crushed rock embankment were studied along the Qinghai-Tibet Railway.The results of experi-ments in the field revealed that the cooling effect of a crushed rock embankment is influenced mainly by the natural con-vection in winter and shield effect in summer,the ventilation of crushed rocks,and the ground temperature regime be-neath the embankment.Consequently,these three factors should be taken into account in numerical simulations,but it is as a result of natural convection only.

Early Permian–Late Triassic Magmatism in the Tuotuohe Region of the Qinghai–Tibet Plateau: Constraints on the Tectonic evolution of the Western Segment of the Jinshajiang Suture

In this paper we present new zircon U-Pb ages,whole-rock major and trace element analyses,and zircon Hf isotopic data for magmatic rocks in the Tuotuohe region of the western segment of the Jinshajiang suture.Our aim is to constrain the Early Permian-Late Triassic tectonic evolution of the region.Zircons from the magmatic rocks of the Tuotuohe region are euhedralsubhedral in shape and display fine-scale oscillatory zoning as well as high Th/U ratios （0.4-4.6）,indicating a magmatic origin.The zircon U-Pb ages obtained using LA-ICP-MS are 281 ± 1 Ma,258 ± 1 Ma,244 ± 1 Ma,and 216 ± 1 Ma,which indicate magmatism in the Early Permian-Late Triassic.A diorite from Bashihubei （BSHN） has SiO2 =57.18-59.97 wt％,Al2O3=15.70-16.53 wt％,and total alkalis （Na2O ＋ K2O） =4.46-6.34 wt％,typical of calc-alkaline and metaluminous series.A gabbro from Bashibadaoban （BSBDB） belongs to the alkaline series,and is poor in SiO2 （45.46-54.03 wt％） but rich in Al2O3 （16.19-17.39 wt％） and total alkalis （Na2O ＋ K2O =5.48-6.26 wt％）.The BSHN diorite and the BSBDB gabbro both display an enrichment of LREEs and LILEs and depletion of HFSEs,and they have no obvious Eu anomaly; they have relatively low MgO contents （2.54-4.93 wt％）,Mg# values of 43 to 52,and low Cr and Ni contents （8.07-33.6 ppm and 4.41-14.2 ppm,respectively）,indicating they differentiated from primitive mantle magmas.They have low Nb/U,Ta/ U,and Ce/Pb ratios （1.3-9.6,0.2-0.8,and 0.1-18.1,respectively）,and their initial Hf isotopic ratios range from ＋9.6 to ＋16.9 （BSHN diorite） and ＋6.5 to ＋12.6 （BSBDB gabbro）,suggesting their primary magmas were derived mainly from the partial melting of a mantle wedge that had been metasomatized by subduction fluids.Taking all the new data together,we conclude that the western and eastern segment of the Jinshajiang suture regions underwent identical processes of evolution in the Early Permian-Late Triassic：oceanic crust subduction before the Early Permian,continental collision during the Early-Middle Triassic,and post-collisional extension from the Late Triassic.

Applying the AHP-FUZZY method to evaluate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau: a case study of Chaidaer-Muli Railway

This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of rubble roadbed engineering in permafrost regions. The AHP(Analytic Hierarchy Process) method is thus employed to establish the evaluation indicator system. The evaluation factor is selected by analyzing the mutual relation between the permafrost environment and roadbed engineering. Thus, a hierarchical structure model is established based on the selected evaluation indices. Each factor is weighted to determine the status in the evaluation system, and grading standards are built for providing a basis for the evaluation. Then, the fuzzy mathematical method is introduced to evaluate the measure effect of rubble roadbed engineering in permafrost regions along the Chadaer-Muli Railway. Results show that most of the permafrost roadbed is in a preferable condition(b) along the Chaidaer-Muli Railway due to rubble engineering measures. This proportion reaches to 86.1%. The proportion in good(a), general(c) and poor states(d) are 0.0%, 7.5% and 6.4%, respectively, in all the evaluation sections along the Chaidaer-Muli Railway. Ground-temperature monitoring results are generally consistent with AHP-FUZZY evaluation results. This means that the AHP-FUZZY method can be applied to evaluate the effect of rubble roadbed engineering measures in permafrost regions. The effect evaluation of engineering measures will provide timely and effective feedback information for further engineering design. The series of engineering measures will more effectively protect permafrost stability.

Review on Regional Climate Change Induced by Qinghai-Tibet Plateau Uplift

[Objective]The aim was to study the influence of Qinghai-Tibet Plateau uplift on regional climate in China.[Method] Trough relevant study of Qinghai-Tibet Plateau and its surrounding movement,the tectonic movement of the Qinghai-Tibet Plateau and its surrounding areas,especially the case of the impact caused by plateau phased uplift were studied based on paleomagnetic measurements.[Result]The increasing Qinghai-Tibet Plateau led to obvious transition from dry to cold in northwest China and it became dry quickly,which led to loess accumulation,replacement of vegetation types and human activity.Meanwhile,it was dry,and there was certain degree of climate changes in the area.[Conclusion] Qinghai-Tibet Plateau had far-reaching significance on basic climate characteristics in northwest China.

Water Environmental Degradation of the Source Area of the Yellow River on Northeast Qinghai-Tibet Plateau

The issue on water environmental degradation in the source area of the Yellow River has been one of very serious ecological and socially economic problems. The temporal-spatial changes of water environment led to the decreasing of land capacity and river disconnecting. The status of water environmental degradation in this paper was analyzed based on the data and field investigation. The results indicated that the surface water area in the region has obviously decreased owing to the climate changes and human irrational use of water resources and the continuous lowering of the regional groundwater table and the steadily decreasing tendency of the flow rate in the source areas of the Yellow River.

Joint Inversion of the 3D P Wave Velocity Structure of the Crust and Upper Mantle under the Southeastern Margin of the Tibetan Plateau Using Regional Earthquake and Teleseismic Data

The special seismic tectonic environment and frequent seismicity in the southeastern margin of the Qinghai-Tibet Plateau show that this area is an ideal location to study the present tectonic movement and background of strong earthquakes in China's Mainland and to predict future strong earthquake risk zones. Studies of the structural environment and physical characteristics of the deep structure in this area are helpful to explore deep dynamic effects and deformation field characteristics, to strengthen our understanding of the roles of anisotropy and tectonic deformation and to study the deep tectonic background of the seismic origin of the block＇s interior. In this paper, the three-dimensional （3D） P-wave velocity structure of the crust and upper mantle under the southeastern margin of the Qinghai-Tibet Plateau is obtained via observational data from 224 permanent seismic stations in the regional digital seismic network of Yunnan and Sichuan Provinces and from 356 mobile China seismic arrays in the southern section of the north-south seismic belt using a joint inversion method of the regional earthquake and teleseismic data. The results indicate that the spatial distribution of the P-wave velocity anomalies in the shallow upper crust is closely related to the surface geological structure, terrain and lithology. Baoxing and Kangding, with their basic volcanic rocks and volcanic clastic rocks, present obvious high-velocity anomalies. The Chengdu Basin shows low-velocity anomalies associated with the Quaternary sediments. The Xichang Mesozoic Basin and the Butuo Basin are characterised by low- velocity anomalies related to very thick sedimentary layers. The upper and middle crust beneath the Chuan-Dian and Songpan-Ganzi Blocks has apparent lateral heterogeneities, including low-velocity zones of different sizes. There is a large range of low-velocity layers in the Songpan-Ganzi Block and the sub-block northwest of Sichuan Province, showing that the middle and lower crust is relatively weak. The Sichuan Basin, which is located in the western margin of the Yangtze platform, shows high-velocity characteristics. The results also reveal that there are continuous low-velocity layer distributions in the middle and lower crust of the Daliangshan Block and that the distribution direction of the low-velocity anomaly is nearly SN, which is consistent with the trend of the Daliangshan fault. The existence of the low-velocity layer in the crust also provides a deep source for the deep dynamic deformation and seismic activity of the Daliangshan Block and its boundary faults. The results of the 3D P-wave velocity structure show that an anomalous distribution of high-density, strong-magnetic and high-wave velocity exists inside the crust in the Panxi region. This is likely related to late Paleozoic mantle plume activity that led to a large number of mafic and ultra-mafic intrusions into the crust. In the crustal doming process, the massive intrusion of mantle-derived material enhanced the mechanical strength of the crustal medium. The P-wave velocity structure also revealed that the upper mantle contains a low-velocity layer at a depth of 80-120 km in the Panxi region. The existence of deep faults in the Panxi region, which provide conditions for transporting mantle thermal material into the crust, is the deep tectonic background for the area＇s strong earthquake activity.

Study on the Landcover Changes Based on GIS and RS Technologies: A Case Study of the Sanjiangyuan National Nature Reserve in the Hinterland Tibet Plateau, China

With global warming and increased human activity, more and more ground surface areas have been affected, which leads to the creation of many problems. To understand the ecological environment changes in a typical alpine region, information on landcovers changes in the study area from 2000 to 2020 was obtained by combining remote sensing, geographic information system, and traditional statistical analysis for the Sanjiangyuan National Nature Reserve on the Qinghai-Tibet Plateau, China. The results show that the changes of surface cover in Sanjiangyuan National Nature Reserve are relatively concentrated, mainly distributed in the sections of south, northwest, central, and northeast, with the area of the changed regions and the unchanged regions being 31,127.45 km2 and 271,941.37 km2, respectively. The transformation between the various types of ground landcover is mainly characterized by a shift from other types to grassland and from grassland to bare land. And the regions of change are mostly concentrated between 3500 - 4600 m in elevation.

不同水平分辨率区域气候模式对青藏高原气候特征模拟

青藏高原地区气候特殊、地形复杂,气象观测站点稀少,对其区域气候和水循环过程的观测和模拟存在很大的困难。本文基于RegCM模式和WRF模式,探究不同水平分辨率10km、25km、50km下区域气候模式对该地区1989—2008年气候时空分布规律的模拟能力。研究结果表明:在10 km水平分辨率下,RegCM模式模拟多年平均气温绝对误差为0.33℃,WRF模式模拟绝对误差为1.77℃,比25 km和50 km水平分辨率下绝对误差减少1.60~2.12℃,且四季气温模拟值与实测值的相关性有所提高;随着水平分辨率的提高,WRF模式对青藏高原东南部和南部的降水量高估有所改善,RegCM模式模拟值逐渐接近实测值(模拟年降水量相对误差由169%降至75%)且对高原北部降水量的模拟有所改善,但整体上模式对降雨的高估依然存在;两个模式随水平分辨率的提高对地形起伏最大的雅鲁藏布江源区降水量的误差减少最为明显。本研究可为揭示气候变化下青藏高原水文响应机理奠定基础。

青藏高原地区能源碳排放时空格局及驱动因素

青藏地区经济发展滞后,自然本底脆弱,开展能源碳排放时空格局演变及其驱动因素研究,对突破经济发展对能源消耗的路径依赖,降低生态环境代价具有重要的现实价值。基于青藏地区2005—2020年能源碳排放与经济发展数据,分析了碳排放的部门来源及其时空演化过程,并探讨了其内在机理。研究表明:(1)青藏地区能源碳排放规模15年间扩张2.37倍,增速显著高于全国其他地区,生态恶化和环境污染风险较高。(2)青藏地区能源碳排放重心主要位于高原北缘和东缘,研究期内空间格局总体稳定,但青藏南部生态脆弱区碳排放规模逐渐上升。(3)工业为青藏地区能源碳排放最主要来源,占比高达72.4%。服务业为增速最快部门,能源碳排放规模15年增长408.7%。(4)青藏地区总体处于“低经济发展水平-低能源消耗”的滞后发展阶段中,研究时段内交通与服务业能源碳排放与经济增长呈现增长连接和扩张负脱钩状态,经济发展产生较大环境压力。(5)青藏地区经济发展与能源碳排放具有紧密的因果联系,但影响程度具有明显的空间异质性。最后,基于青藏地区自然本底,经济发展,环境压力的三元互馈关系,探讨了不同区域经济发展与二氧化碳减排的协调路径。

近红外高光谱传感器在地震有关气体监测中的应用:以青藏高原东边界为例

为了促进高光谱技术在地震有关气体监测中的应用,本文选取对近地表信息敏感度较强的近红外高光谱传感器TROPOMI的二级产品数据,分析研究了青藏高原东北缘和川滇地区地震相关气体时空特征及其与构造和地震活动关系,评价了近红外传感器在地震有关气体监测中的应用效果和应用前景。结果表明:TROPOMI反演的研究区CH_(4)和CO气体在时间上呈现明显的季节变化,受气候变化、地貌、人类活动等影响;空间上在银川、渭河和四川盆地表现为高值,受地质背景、地形地貌和人类活动等因素影响。目前近红外高光谱传感器在时间分辨率和有效数据量上具有一定的局限性,但是相对于热红外高光谱传感器,近红外传感器可以较好地反映气体与近地表构造的关系。未来随着近红外高光谱传感器的应用和发展,近红外数据可以逐渐弥补热红外传感器数据对近地表信息敏感度低的不足,提高异常与地震关系的判断力。

不同高寒草地生态区种植模式对饲草产量和营养品质的影响

研究燕麦(Avena sativa)分别与饲用豌豆(Pisum sativum)、箭筈豌豆(Vicia sativa)、蚕豆(V.faba)混播及4种作物单播在高寒不同生态区的生产性能,探讨适宜各生态区的最佳种植模式,为高寒不同生态区一年生混播草地的栽培提供依据。结果表明:1)各混播组合间,燕麦+饲用豌豆组合的干草产量和粗蛋白含量最高,分别为10.56 t·hm^(−2)和16.15%;3种混播组合的粗蛋白含量、可溶性糖含量、粗脂肪含量、中性洗涤纤维含量均介于燕麦单播和饲用豌豆、箭筈豌豆、蚕豆单播之间。2)各生态区间,燕麦和3种豆类的平均株高均随海拔高度的上升呈先增加后降低的趋势;门源的干草产量最高,为9.78 t·hm^(−2);除贵南外,粗蛋白含量亦随海拔高度的升高呈降低趋势,贵南的粗蛋白含量最高,为17.69%。3)综合评价得出,适宜各生态区种植的混播组合分别是祁连山流域门源和湟水谷地湟中的燕麦+饲用豌豆组合、三江源区贵南的燕麦+蚕豆组合、环青海湖区共和的燕麦+箭筈豌豆组合,干草产量分别为13.00和10.63、10.59、10.73 t·hm^(−2),粗蛋白含量分别为14.65%和16.11%、13.56%、12.01%;各生态区最佳混播组合的干草产量较燕麦单播分别增加了48.57%(门源)、23.17%(湟中)、23.00%(贵南)、47.80%(共和)。

青藏地区矿山企业安全发展问题研究

在前期深入矿山督导调研、指导帮扶重点县以及在大数据分析的基础上,梳理出青藏地区矿山企业特征和安全发展面临的主要问题,为推动青藏地区矿山企业安全发展提出相应的对策措施。认为,作为国家矿山安全监察派驻机构,青海局需立足法定职责,理顺矿山安全监管体制、完善矿山安全联合执法机制、强化监管执法人员培养培训、严格规范矿山安全执法行为、切实提高矿山安全执法效能、加大科技成果推广应用力度、积极争取国家政策资金支持。

多年冻土区热融湖塘状态及侵蚀路基病害防治措施

近年来,随着气候变暖和青藏高原降水的逐年增加,青藏铁路沿线的热融湖塘数量和面积也明显增加,开始影响青藏铁路路基安全。通过现场调查和统计分析,对青藏铁路多年冻土的热融湖塘发育状态和应对措施进行研究,研究结论包括,随着气候变暖和青藏高原降水的逐年增加,青藏铁路沿线的热融湖塘数量和面积也明显增加,且离路基越来越近;青藏铁路路基两侧20 m范围内发育热融湖塘14处,部分热融湖塘已延伸至路基坡脚,严重影响地基多年冻土的稳定,进而影响路基稳定性;对影响铁路路基安全的2处典型热融湖塘进行分析,提出包括地表水、地下水双隔离及太阳能热棒增强冻土稳定性的措施。

The surface geochemical exploration of oil and gas in the Gangbatong-Ya'anxiang and the Dongqiao-Nam Co of the Qinghai-Tibet region

Due to the complexity of geological background and the adverseness of natural geographical environment in the Qinghai-Tibet Plateau,it is very difficult to carry out petroleum geological study in this region. The Qinghai-Tibet Plateau is the only blank space of petroleum exploration on a large scale. The authors carried out the surface geochemical exploration of oil and gas in the Gangbatong-Ya'anxiang and Dongqiao-Nam Co of the Qinghai-Tibet region. Based on the data of actual detection and experiments in the studied area,the characteristics of concentration and profile distribution of the main geochemical exploration indicators(total adsorbed hydrocarbon,altered carbonate,thermal released mercury,etc.) were discussed. The origin of hydrocarbon was also discussed. Moreover,the oil and gas potential of different sections in the Qiangtang Basin and the Biru Basin were evaluated,which could provide references for the exploration and prediction of oil and gas in this region. The concentrations of total adsorbed hydrocarbons in the Ya'anxiang of Suoxian County-Zadong of Baqing County and the Jiecha-Dangxiong of Anduo County in the Qinghai-Tibet region are high,averaging 312.64 μL·kg-1 and 164.36 μL·kg-1. Their altered carbonate concentrations are relatively low,averaging 0.11% and 0.56%. Their concentrations of thermal released mercury are relatively high,averaging 13.09×10-9 and 1.94×10-9. Geochemical exploration results in fact reflect hydrocarbon information in the underground,which are mainly petroleum associated gas and over-matured cracking gas. The Jiecha-Charenluma and the Xiamaya'ertong-Suoba sections in the Qiangtang Basin are the most favorable ones for oil and gas and the Ekou-Zadong section is relatively favorable one,while the Nam Co and the Zigetangcuo-Dongqiao sections in the Biru Basin are the favorable ones for oil and gas,and the Jiang Co-Nading Co and the Ya'anxiang-Ya'ertong sections are relatively favorable ones.

盐湖漫溢对多年冻土区桥梁墩台影响对策研究

近年来,青藏高原多年冻土区盐湖面积不断扩大,漫溢后形成高矿化度水流流经铁路、公路的桥梁墩台,给线路运营造成了较大的安全隐患。针对盐湖漫溢河道处的桥梁工程进行研究,分析了盐湖漫溢对桥梁墩台带来的主要影响,提出了针对性的防治对策,并基于现场监测数据对工程效果进行了评价。主要结论包括:高矿化度水流对桥梁墩台造成的影响主要有河道下切严重,对地基多年冻土热干扰严重和对桥墩及基础混凝土腐蚀。针对高矿化度水流对桥梁墩台的影响,提出了区域河流疏导和冻土防护、桥墩基础冻土热防护、桥梁结构构造防腐蚀3个方面的整治技术;根据初期监测数据分析,高矿化度水流流量较大,造成下部冻土退化严重,但在合理的整治工程实施后,近1年多来未发现桥梁墩台变形。同时,地温监测数据验证了热棒具有保持多年冻土稳定的作用。

New evidence for the Qinghai-Xizang (Tibet) Plateau as a pilot region of climatic fluctuation in China

Over 40 a observed temperature data in 172 stations in China and historical proxy data were analyzed. Evidence suggested that during 1980-1994, the warmest year appeared first in southeastern part of the Qinghai_Xizang (Tibet) Plateau (henceforth SETP) and then gradually spread northwards and eastwards to eastern China. The climatic change on century time scale in recent 600 a shows 3 relatively warm and clod stages in China. Each warm and cold stage appeared first in Tibet Plateau (henceforth TP) and then in the Qilian Mountains, then in the eastern parts of China. The warm and cold stages in TP were 10-60 a earlier than in the eastern China. The facts show that TP is a pilot region of climatic fluctuation in China on the time scale shorter than 10\+3a.

青藏高原土地沙漠化区划

青藏高原是土地沙漠化正在发展—强烈发展的重要区域 ,土地沙漠化区域分异明显。本文在确定区划原则和区划指标的基础上 ,将青藏高原沙漠化区域划分为藏南河谷湖盆区、藏北高原区、阿里高原区、藏东南三江河谷区、柴达木盆地区、共和盆地区、青海湖盆地环湖区、青南高寒区和川西甘南高原区等 9区 2 3亚区 ,各区域土地沙漠化的基本特征、现状与发展态势各有不同。按照高原沙漠化地域分异规律与特点 ,结合生态建设的要求 ,青藏高原沙漠化防治的基本思路是 :全面保护 ,综合治理 ,适度开发 ,协调发展。

青藏高原区域地质调查中几个重大科学问题的思考

在世纪之交,中国地质调查局部署的青藏高原近百幅1∶25万区域地质调查填图,取得了一系列重要新发现、新进展、新成果,神秘的青藏高原地质构造、结构、组成、演化等问题得到了进一步的认识和理解。喜马拉雅奠基于5.5亿年左右的泛非造山事件基底上,历经奥陶纪至泥盆纪台地沉积,并于石炭纪末转化为印度板块北缘的弧后伸展裂陷带;雅鲁藏布江蛇绿混杂岩带曾是特提斯大洋南侧与冈底斯古岛弧带相对应的中生代弧后扩张盆地;冈底斯带曾经历了晚古生代岛弧造山作用;班公湖-怒江带两侧大量地质特征重大差异表明,班公湖-怒江带是冈瓦纳大陆北界,是印度(滇藏)地层区和华南(羌塘-三江)地层区的分界,是新元古代Rodinia超大陆解体后显生宙特提斯大洋俯冲、消减、碰撞,最后消亡的遗迹。

我国蒙新区、青藏区马胃蝇多样性及感染分析

【目的】研究新疆、内蒙、青海3个地区的草原、荒漠草原和高寒草原马胃蝇蛆病的发生情况、感染多样性和区系组成。【方法】采用伊维菌素于同一年冬季分别对蒙新区的新疆卡拉麦里有蹄类自然保护区普氏野马、内蒙古多伦县当地家马以及青藏区的青海省玛多县当地家马进行驱虫,对获取的马胃蝇数量、种类进行调查和分析。【结果】1)马胃蝇蛆病发生普遍,感染率在3个地区马科动物中均为100%,感染程度有明显的地域性:蒙新区重于青藏区;新疆卡拉麦里有蹄类自然保护区马胃蝇感染数量显著高于同区的内蒙古多伦县,后者的感染量明显高于青藏区的玛多县;2)同属于蒙新区的新疆卡拉麦里有蹄类自然保护区和内蒙古多伦县具有相同的马胃蝇种类,所涉及的6个种(黑腹胃蝇、鼻胃蝇、肠胃蝇、黑角胃蝇、红尾胃蝇和裸节胃蝇)均为我国现有记录种;而属于青藏区的青海玛多县马胃蝇调查到2个种(黑腹胃蝇和鼻胃蝇);卡拉麦里与多伦县的马胃蝇组分相似性指数为1,二者与玛多县的相似性指数均为0.33;3)多伦县的马胃蝇多样性指数(H'=1.31)显著大于玛多县(H'=0.23)以及新疆卡拉麦里(H'=0.21);宿主感染马胃蝇的均匀度指数(J)同样为多伦县(0.73)最高,其次为玛多县(0.34),卡拉麦里(0.12)最低;4)黑腹胃蝇为卡拉麦里和玛多县马胃蝇的绝对优势种,分别占这2个地区采样总量的96.17%和93.17%;而在多伦县,肠胃蝇感染率最高(52.40%),其次为鼻胃蝇(23.80%),二者成为该地区的马胃蝇优势种。【结论】1)蒙新区的马胃蝇种类较青藏区丰富;2)多伦县具有丰富的马胃蝇类群;3)马胃蝇多样性受宿主所在环境条件影响,蒙新区和青藏区马胃蝇物种的差异与2个地区巨大的自然条件差异有直接关系;干旱、荒漠以及高寒等恶劣生境下马胃蝇多样性低,其原因为某单一物种数量过大新疆或物种数少(青海);4)黑腹胃蝇具有成功适应严酷生境的生存方式,黑腹胃蝇在干旱荒漠以及高寒环境感染量均占马胃蝇感染量的90%以上,与其与众不同的传播方式——将卵产于草上"污染"草场有着密切的联系。