多年冻土区热融滑塌型滑坡稳定性评价方法

Landslide of thaw-slumping in permafrost regions of the Qinghai-Tibet Plateau is studied in this paper. Thaw-slumping belongs to shallow landslide with small depth-length ratio. Therefore the infinite slope analysis method is available to be applied in the stability analysis. Considering identical seepage directions to slope surface, we deduced analytical expressions of safety factor according to the effective stress principle and plotted stability analysis chart of slopes with dry or fully saturated soils.Taking an example of landslide of thaw-slumping at the mileage of K3035 of the Qinghai-Tibet Highway, we evaluated the analytical expressions.     

Aftershock of the Wenchuan Earthquake in Sichuan Triggers Large Earthquake in Minxian County, Gansu

Because of the confining compression of the Pacific,Eurasian and Indian plates,the Chinese mainland is frequently stricken with earthquakes,especially in the Qinghai-Tibet Plateau and surrounding areas and along the NS-trending tectonic zone from Yinchuan to Lanzhou,Chengdu,and finally to the Kunming tectonic belt (Fig.1).Historical records show that there are 14 earthquakes of＞Ms 8 occurring in the two regions,eight of which occurred along the latter tectonic belt.The 2008 Wenchuan earthquake located on both the NS tectonic zone and the Longmenshan fault zone along the eastern margin of the Qinghai-Tibet Plateau.     

Chinese Scientists Have Obtained Great Achievements in Comprehensive Research on the Qinghai-Tibet Plateau

The China Geological Survey carried out 1:250000 regional geological surveys of the Qinghai-Tibet Plateau from 1999 to 2005.With a total investment of 300 million yuan,more than 1000 geologists were involved annually to conduct mapping at a grid of one line to every four km along the Kunlun Mts-Altyn Shan-Tanggula Shan,Kokoxili-Qiangtang,Gangdese,Yalun Zangbu River,and finally to the Himalayan ranges.The extensive mapping culminated in a total of 112maps covering an area of 152 square kilometers.Based on this success,the China Geological Survey launched another program,the "Integration and Comprehensive Study of Basic Geological Survey Result(s) in the Qinghai-Tibet Plateau".The program lasted from 2006 to 2010 and has yielded copious research results,making big strides in upgrading our understanding of the Qinghai-Tibet Plateau.The achievements are manifold.     

Crustal Structural and Tectonic Evolution and Oil Prospect Evaluation in the Songpan-Zoigê Block

1 Introduction The Songpan-Zoigê Block (SRB) lies in the east of the Qinghai-Tibet Plateau. It is a triangle block confined and surrounded by three structure belts: the east Kunlun-west Qinling belt (EK-WQLB) to the north, the Sichuan Basin to the southeast and the Garzê-Litang-Jinsha River belt to the southwest. This block is also the joint part of three tectonic domains: the North China, South China and Qinghai-Tibet domains (Huang and Chen, 1987). The development and evolutio…     

The Crustal Structure and Assembly of Terranes in the Qaidam-Qilian-Beishan Area, Western China

Through a study of the geotransect from Golmud to Ejin Qi published recently, the tectonics of the crust beneath the area from the northern Qinghai-Tibet plateau (Qaidam and the Qilian Mountains) to the border between China and Mongolia and its structure, composition and tectonic evolution have been revealed, and abundant information about the deep structures has been provided. Based on the research into the geotransect, it is suggested that the crust in this area was formed by the assembly of the terranes in different geological stages. Following the formation of the Palaeo-Asian continent, the north part of the corridor of the transect became a part of the huge unifying continent by the end of the Early Permian. In the Mesozoic and Cenozoic, as a result of the compression mainly by the push of the Qinghai-Tibet plateau on the south, the unique crustal structure and geomorphologic features on the northern Qinghai-Tibet plateau were formed. This geotransect together with the Yadong-Golmud geotransect co     

Enrichment of Mantle-derived Fluids in the Formation Process of Granitoids: Evidence from the Himalayan Granitoids around Kunjirap in the Western Qinghai-Tibet Plateau

Taking the Himalayan granitoids around Kunjirap in the western Qinghai-Tibet plateau as an example, the authors present in this paper the characteristics of the granitoids rich in mantle-derived fluid components and discuss their rock-forming mechanism. The research results indicate that the rock assemblage of the studied granitoids involves diopside syenite-diopside granite-biotite (monzonitic) granite, consisting mainly of K-feldspar, oligoclase, quartz, iron-phlogolite, diopside and edenite. The rocks are rich in mantle-derived fluid components of volatiles including F, alkali metal elements such as K, Na, Rb, Sr and Ba, and radiogenic heat-producing elements such as U and Th. They were generated by the influx of mantle-derived fluids into the lower crust to give rise to partial melting during the lithosphere thinning in the Qinghai-Tibet plateau.     

The Quaternary Pan-lake (Overflow) Period and Paleoclimate on the Qinghai-Tibet Plateau

Lake geomorphology and high-level lacustrine deposits since the mid-late Pleistocene are well preserved in lakes of the Qinghai-Tibet Plateau. According to geological surveys of 17 lake districts in different locations of the plateau, combined with interpretations of satellite images and topographic maps, the authors studied the timing of formation and scopes of the pan-lake areas of the plateau and their paleoclimate. The latest two high lake levels （overflow surfaces） on the Qinghai-Tibet Plateau in the Quaternary occurred at N40 to 30/35 ka and N65 to 53 ka respectively. In these time intervals, the plateau was covered by huge interconnected pan-lake systems with a total area of -36 km^2 and a total volume of lake water of 〉530 million km^2, which are about 38 times and 659 times larger than those of the modern lakes respectively. Before this pan-lake period in the late Pleistocene, there had been three high lake levels that occurred at N 132-112 ka, 110-95 ka and 91-72/-83-75 ka respectively, suggesting that the late Quaternary climate on the plateau was unstable and changed rapidly. The -40-30 ka high lake level also appeared in the Tengger desert north of the plateau, suggesting that there existed very strong summer monsoons from South Asia then; the variation in solar radiation with a 20,000 precessional period has special importance for the high-altitude Qinghai-Tibet Plateau in the low-latitude zone of the Earth. Around 30 ka, the pan-lakes at the peripheries of the Qinghai-Tibet Plateau drained out suddenly with rapid uplift of the plateau and cooling. In a short time the huge amount of cold lake water emptied into the Indian Ocean and Western Pacific. The draining event of the pan-lakes brought about the environmental changes of rivers and lakes at peripheries of the plateau.     

Permafrost and taliks and their changes on the south and north banks of the Tuotuo River in the Qinghai-Tibet Plateau under the climate warming北大核心CSCD

The distribution of permafrost and taliks is very complex in the Tuotuo River Basin(TRB), which is located in interior of the Qinghai-Tibet Plateau. Characterizing the spatial distribution and the thermal stability of permafrost and taliks is of great significance to community activities and engineering construction in TRB. Based on the zonation of permafrost and talik distribution around TRB conducted in the 1980s, the soil temperature and its variation process of permafrost and taliks in the south and north banks of the Tuotuo River were analyzed by using the observation data of five boreholes(N1~N5)along the Qinghai-Tibet Railway in the north bank and five boreholes(S1~S5)on the first terrace in the south bank. The results showed that, under the climate warming, permafrost and taliks in the north banks experienced significant degradation and warming process. From 2005 to 2020, the permafrost at the N1 borehole has undergone a significant down-draw degradation process, from extremely unstable and high-temperature permafrost to thawed zone. From 2005 to 2013, the annual average ground temperature of the talik at N2 increased at a rate of 0. 3~0. 4 °C·(10a)-1. At Maqutang on the south bank, permafrost prevails from the first-class terrace to the gentle slope of the Kaixinling Mountain, with both through and non-through taliks on the first-class terrace. The spatial distribution and the thermal stability of permafrost and talik in the TRB are further promoted by analyzing the changes in temperatures at boreholes in the basin. However, to meet the requirements of mapping and engineering construction of permafrost and taliks in the TRB, it is still necessary to carry out geological investigation with multiple methods and in-depth research on development mechanism of taliks in the future. © 2022 Nanjing Forestry University. All rights reserved.     

Time Sequence of Himalayan Endogenetic Mineralization on the East Side of the Qinghai-Tibet Plateau

Among the endogenetic deposits in the Sanjiang area and at the west margin of the Yangtze platform, Himalayan deposits are the most important and contribute a large proportion of the resources of superlarge deposits. Among the controlled resources of this region, 84% of copper resources, 67% of Pb-Zn, 31% of Ag, 77% of gold and 24% of tin come from Himalayan deposits on the east side of the Qinghai-Tibet plateau. Himalayan endogenetic mineralization shows a relatively complete sequence evolution in the Sanjiang area and on the west margin of the Yangtze platform. Mineralization is manifested by gold deposits related to K-rich lamprophyre, REE deposits related to alkalic complexes and Cu-Au-polymetallic deposits related to alkaline porphyry. Six sequences of mineralization evolution since 65 Ma B.P. in the Sanjiang area and on the west side of the Yangtze platform can be recognized. Himalayan endogenetic mineralization on the east side of the Qinghai-Tibet plateau reached its peak before the Oligo-cene,     

Tectonic Landform of Quaternary Lakes and Its Implications for Deformation in the Northern Qinghai‐Tibet Plateau

The Hohxil region in the northern Qinghai-Tibet Plateau is occupied by numerous plateau lakes, which have long been inferred as being tectonic products. However, so far little evidence has been found to support this tentative inference. Field survey and morphotectonic analysis of TM satellite images in the eastern segment of the Hohxil region revealed that Kusai Lake and Yelusu Lake are S-shaped pull-apart basins, which were dominated by left strike-slip master faults trending WNW–ESE. The pull-apart distances of the two lakes are analyzed to be <15-20 km and 15 km respectively. Based on studies of the faulting rate, the initiation ages of the pull-apart basins are suggested to be approximately in the Early Pleistocene. The pull-apart basin tectonics is further regarded as a common mechanism for the widely distributed large lake basins in the northern Qinghai-Tibet Plateau. Regional distribution of these pull-apart basins and their substantial intra-block slip suggest that a sinistral shear stress, which is independent of the distinguished strike-slip faults, has been imposed on across the northern Qinghai-Tibet Plateau. Thus, the intra-block slip may be an important expression of the eastward extrusion of the Plateau crustal material in accommodating the ongoing continent–continent convergence between India and Eurasia. The revelation of pull-apart tectonics within the Plateau hinterland provides field evidence and a possible style of deformation for the newly proposed continuous deformation by the global positioning system (GPS) measurement across the northern Qinghai-Tibet Plateau. A model, with respect to systematic tectonic landform development, for pull-apart basins is finally proposed.     

Study on Distribution Rule of Geostress in Qinghai-Tibet Area

The distribution curve of the Ratios of the Average Horizontal Geostress and the Vertical Geostresses(RAHVG) varying with depth and regression equation were obtained in Qinghai-Tibet area of China for the first time by collecting and analyzing 200 in-situ measured geostress results based on the analysis of distribution rule of geostress in China. Then the geostress distribution rule and the characteristics were analyzed, and it is found that the geostress in Qinghai-Tibet area conforms to the geostress distribution rule in China, but the geostress in Qinghai-Tibet area is significantly subjected to tectonic squeezing and the tectonic geostress is very obvious in magmatic rock. The RAHVG of the magmatic rock varying with depth in Qinghai-Tibet area is significantly greater than that in China between the depth of 100 m and 800 m. It shows that the stress of the magmatic rock in Qinghai-Tibet area is significantly subjected to squeezing tectonic. The RAHVG of the sedimentary rock varying with depth in Qinghai-Tibet area is basically consistent with that in China, but the value in Qinghai-Tibet area is greater. It shows that the stress of the sedimentary rock in Qinghai-Tibet area is not significantly subjected to squeezing tectonic. The RAHVG of the metamorphic rock varying with depth in Qinghai-Tibet area is significantly greater than that in China. It shows that the stress of the metamorphic rock in Qinghai-Tibet area is subjected to squeezing tectonic in some degree. This study can provide references to the study of distribution characteristics of geostress in Qinghai-Tibet area. It also has important practical value for underground engineering survey, design, structural analysis and construction in Qinghai-Tibet area.     

青藏铁路多年冻土区工程复杂性分析

青藏铁路穿越550km多年冻土区,多年冻土地温、冻土类型以及沿线生态环境等存在较大的差异,使多年冻土区工程较为复杂。因此本文提出了冻土工程复杂性概念,建立冻土工程复杂性评价模型,并利用GIS平台对青藏铁路沿线唐古拉山越岭地段工程复杂性进行了分析和研究。研究结果表明,青藏铁路穿越的唐古拉山越岭地段工程复杂性相对较小,而青藏公路的工程复杂性相对较大。这表明了青藏公路沿线冻土工程比青藏铁路沿线更为复杂,在各种因素的影响下,青藏公路路基稳定性变化比青藏铁路更加复杂。     

青藏高原大陆动力学的科学问题

在初步分析大陆动力学的基本含义及其与岩石圈动力学关系的基础上,提出了青藏高原大陆动力学8个方面的科学问题,其核心科学问题是:青藏高原的形成是印度板块与欧亚板块碰撞的滞后效应还是大陆板内构造过程;青藏高原不同构造演化阶段是否具有不同的动力学机制;解体的青藏高原岩石圈下地壳何时、何处、如何和为何流动;青藏高原怎样与周边的盆地同步强耦合作用;如何通过青藏高原大陆动力学的创新带动能源、资源、环境、灾害等应用基础理论的创新.     

巴伦支-喀拉海海温和青藏高原冬季地表气温的年代际联系

基于1961—2017年中国气象局地表气温数据、JRA-55大气再分析数据以及美国国家海洋和大气管理局延伸重建的海温资料,研究了青藏高原冬季地表气温的年代际变化特征及其与海温的可能联系。结果表明：巴伦支-喀拉海冬季海温年代际变化可以激发出向东传播的Rossby波,在西伯利亚对流层高层产生异常的气旋或反气旋性环流,通过影响副极地以及副热带西风急流强度,在青藏高原的南侧产生异常的反气旋或气旋性环流,从而使得青藏高原上空的垂直运动发生变化,导致青藏高原冬季地表气温异常。     

青藏铁路建设和冻土技术问题

青藏铁路建设三大技术难题的核心是冻土问题. 我国40 a的多年冻土研究为青藏铁路建设打下坚实的技术基础, 但是大规模的铁路建设实践给我们提出了大量深层次的冻土技术问题. 以青藏铁路建设为背景, 结合冻土区科研、设计、施工和建设管理工作的实践, 对青藏铁路建设的冻土技术问题进行了深层次的分析, 提出一些创新性见解, 这些都已经在青藏铁路冻土区工程建设中广泛应用, 卓有成效, 推动了青藏铁路冻土区工程建设的进展.     

青藏高原层状地貌特征及其成因初探

青藏高原是全球海拔最高、形成时代最新和面积最广阔的高原,作为青藏高原典型的地貌特征,层状地貌成因研究对高原隆升、环境气候演化过程的认识具有非常重要的作用,通过野外调查和已有观测数据分析,对层状地貌形成进行探讨,重点从高原现今地貌特征分析的角度,提出主平面和山顶面形成于高原隆升过程中。青藏高原是在印度大陆与欧亚大陆俯冲-碰撞的强烈挤压环境下,内外动力地质作用共同作用的结果,其内动力地质作用具有差异性整体隆升的特征。希望能对青藏高原隆升过程的深入研究提供新的思路和依据。     

环青藏高原构造形变场的数值模拟研究

本文综合论述了环青藏高原地区主要断裂活动性及其内部构造块体运动状况两方面的构造形变场特征，并将其置于 青藏高原这个完整的地球动力学环境体系中，在建立青藏高原构造动力学模型式的基础上，用离散元法模拟分析了环青藏高原地区上述两方面的构造形变场特征。     

青藏高原泛非—早古生代造山事件研究重大进展——冈底斯地区寒武系和泛非造山不整合的发现

在申扎地区发现了较为完整的寒武纪地层和奥陶系与寒武系之间的"泛非运动"角度不整合。这是迄今为止青藏高原南部发现的唯一确切的寒武纪地层,不但进一步丰富和健全了青藏高原的地层系统,而且也是在青藏高原和周边发现的唯一的下奥陶统与寒武系"泛非运动"角度不整合界面。通过对申扎"泛非运动"界面的研究,可以准确界定"泛非运动"的时限及其动力学过程,也是研究"泛非运动"之前冈瓦纳大陆北缘沉积作用不可替代的标本,对青藏高原构造演化研究具有重要、深远的意义。     

Microplastic contamination in lacustrine sediments in the Qinghai-Tibet Plateau: Current status and transfer mechanisms

This paper aims to investigate the present situation and transfer mechanisms of microplastics in lacustrine sediments in the Qinghai-Tibet Plateau. The study surveyed the average abundance of microplastics in sediments. The abundance of microplastics in sediments of lakes from the Qinghai-Tibet Plateau is 17.22–2643.65 items/kg DW and 0–60.63 items/kg DW based on the data of the Qinghai Lake and the Siying Co Basin. The microplastic abundance in sediments from small and medium lakes is very high compared to that in other areas in the world. Like microplastics in other lakes of the world, those in the lakes in the Qinghai-Tibet Plateau mainly include organic polymers PA, PET, PE, and PP and are primarily in the shape of fibers and fragments. The microplastic pollution of lacustrine sediments in the Qinghai-Tibet Plateau is affected by natural changes and by human activities, and the concentration of microplastics in lacustrine ecosystems gradually increases through food chains. Furthermore, the paper suggests the relevant administrative departments of the Qinghai-Tibet Plateau strengthen waste management while developing tourism and pay much attention to the impacts of microplastics in water environments. This study provides a reference for preventing and controlling microplastic contamination in the Qinghai-Tibet Plateau.©2022 China Geology Editorial Office.     

青藏铁路多年冻土工程的研究与实践

青藏铁路建设需穿越高原多年冻土区, 在探明沿线多年冻土分布特征的基础上, 合理确定了青藏铁路线路的走向方案.在多年的冻土研究和工程实践的指导下, 有针对性地开展了 5 个不同类型冻土工程试验研究, 取得重要科研成果, 指导设计和施工.全面总结4 a来青藏铁路多年冻土工程的研究与实践, 提出了“主动降温, 冷却地基, 保护冻土”的设计思想, 制定了路基、桥涵、隧道成套工程技术措施和先进施工工艺, 对确保多年冻土工程质量发挥了重要作用.