西藏地质旅游资源概况及开发建议

西藏地区孕育了如地貌、水体、地质构造、地层剖面和地质灾害遗迹等种类繁多的地质遗迹资源,使得西藏发展地质旅游成为可能。在概述西藏地质旅游资源的基础上,论述了开发西藏地质旅游资源对西藏社会经济可持续发展、改善西藏投资环境和提高招商引资环境容量的重要意义,提出了在开发过程中应遵循“在保护中开发和在开发中保护”的总体原则及几点相关建议。

全球首批100个地质遗产地名录公布2个中国西藏地质遗产地入选

2022年10月26日,国际地质科学联合会(IUGS)公布全球第一批地质遗产地名录,7个中国地质遗产地成功入选。其中珠峰奥陶纪岩石(中国/尼泊尔)和藏南绒布峡谷滑脱构造体系作为中国西藏地质遗产地被选入名录。这些遗产地涵盖岩石学、构造地质学、地层古生物学、地理学、地貌学等领域,在研究矿产资源形成、生命演化、人类起源等科学领域中发挥了重要作用。中国因此成为全球首批中获得地质遗产地最多的国家之一。这次中国入选的7个地质遗产地多数位于世界(国家)地质公园、世界遗产和国家级地质遗迹保护区内,其科学价值和研究水准得到国际学术界的一致认可,优良的保护状况受到国际社会的高度肯定。

神奇天路上的“东方哈达”

在东方古老的传说中,雪山的最高处有一种琼浆玉液,能让凡人益寿延年。怀揣执著的信念,多吉院士率领的西藏地质地热大队翻过十万大山,曾对全自治区100多个泉水点进行勘查,1987年发现了位于念青唐古拉山脉南麓、当雄断陷盆地北侧、海拔5100米处的曲玛弄泉。

Approach to Mountain Hazards in Tibet, China

Tibet is located at the southwest boundary of China. It is the main body of the Qinghai-Tibet Plateau, the highest and the youngest plateau in the world. Owing to complicated geology, Neo-tectonic movements, geomorphology, climate and plateau environment, various mountain hazards, such as debris flow, flash flood, landslide, collapse, snow avalanche and snow drifts, are widely distributed along the Jinsha River (the upper reaches of the Yangtze River), the Nu River and the Lancang River in the east, and the Yarlungzangbo River, the Pumqu River and the Poiqu River in the south and southeast of Tibet. The distribution area of mountain hazards in Tibet is about 589,000 km2, 49.3% of its total territory. In comparison to other mountain regions in China, mountain hazards in Tibet break out unexpectedly with tremendously large scale and endanger the traffic lines, cities and towns, farmland, grassland, mountain environment, and make more dangers to the neighboring countries, such as Nepal, India, Myanmar and Bhutan. To mitigate mountain hazards, some suggestions are proposed in this paper, such as strengthening scientific research, enhancing joint studies, hazards mitigation planning, hazards warning and forecasting, controlling the most disastrous hazards and forbidding unreasonable human exploring activities in mountain areas.

Debris Flow Dam Formation in Southeast Tibet

Glaciers with their deposits abound in the alpine areas of Southeast Tibet. Large debris flows occur frequently from these deposits and form dams that block streams. In this paper,3 events of large debris flows reported in Peilong Valley located in Southeast Tibet,and which resulted 2 blocking dams resulted,are discussed in details,focusing on the major factors controlling dam formation. The results shows that the first surge group caused by snow and ice avalanches,ice-lake breaks,and large-scale landslides,with a high peak discharge and high velocity,and an abundance of boulders,are most likely to form blocking dams.

Characteristics of Metamorphic Rock Magnetic Fabrics in the Nyalam Area of the Southern Tibet and Its Geological Significance, China

This paper reports Precambrian rock magnetic fabrics in the Nyalam area of southern Tibet. The analytical results of magnetic fabrics show that the values of H are high （〉 10% in general）, so the ductile deformations of the Precambrian rock are strong. The orientation of the maximum principal stress inferred from the minimum magnetic susceptibility is nearly S-N, NE-SW and NW-SE. The Flinn diagram of the magnetic fabrics show that the strain pattern is oblate and constrictional type. Magnetic foliation of great majority of rock samples is well developed and the magnetic lineation is poor and the magnetic susceptibility ellipsoid is flattened. The magnetic lineation of the minority rock samples is well developed and the magnetic foliation is poor and the magnetic susceptibility ellipsoid is prolate. According to the geological field and the magnetic fabrics, there are 3 times tectonic stress field in SN directed extruding, NW-SE directed extruding, NW-SE directed extension. It shows that the Nyalam area has undergone process the orientation of SN, NW-SE nappe structure and NW-SE directed extension structure. The change of tectonic stress is reflected by the field characteristics of the Precambrian rock magnetic fabrics that is the direct responding result of the arc-continental, continent-continental collision between the India and Asian continents in the late part of the Late Cretaceous to Late Eocene and subsequently shifted to intra-continental convergent, the plateau uplifting and extension structure stage since the Late Eocene.

Long-term Activity of Earthquake-induced Landslides: A Case Study from Qionghai Lake basin, Southwest of China

Earthquake-triggered landslides are a major geological hazard in the eastern Tibetan Plateau, and have prolonged impact on earth surface processes and fluvial system. To determine how long co-seismic landslides affect basins, a massive number of landslides existing in Qionghai Lake Basin were investigated for landslide distribution characteristics and geomorphological evidences, with further comparison and analysis using historic seismic analog method. The landslides found in Qionghai Lake Basin showed clear features of seismic triggering with strongly controlled by Zemuhe fault. These landslides are still active at present. Some new slides generally occur in ancient slope failure zones causing serious secondary hazards in recent years. In this study we strengthen the idea that the landslides triggered by the 185o Xichang earthquake （Ms7.5） have long term activity and prolonged impact on the mountain disasters with a period of more than 16o years. Our results support growing evidence that coseismic landslides have a prolonged effect on secondary disasters in a basin, and invite more careful consideration of the relationship between current basin condition and landslide history for a longer period.

Depositional features and sedimentary model of Buqu Stage in Mid-Jurassic in Qangtang Basin, Xizang (Tibet), China

The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of transgression-regression sedimentary cycle. Field outcrops and indoor analysis revealed 8 types of sedimentary facies markers in this region. 4 types of sedimentary facies have been recognized: platform facies, platform marginal facies, foreslope facies and basin facies. Influenced by the northern Lazhuglung-Jinshajiang suture zone, central uplift region and southern Bangongco-Nujiang suture zone, these facies belts extended east-west. The sedimentary model was established based on observed depositional features. From their biological features and sedimentary characteristics, it is suggested that the paleoclimate was warm and humid at that time. The Buqu Formation is a promising target for oil and gas exploration in Shuanghu-Duoyong area in future.

GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS AND RELATED MINERALIZATION OF CHERT FORMATIONS IN SOUTH TIBET

There occur abundant cherts in the Mesozoic and Cenozoic strata in southern Tibet. Some of them possess characteristic hydrothermal structures such as layered, laminated, massive and breccia structures. Ratios of Al/（Al＋Fe＋Mn）, Co/Ni, Fe/Ti and TiO2-A1203 demonstrate that their origin is related to hydrothermal sedimentation. The chert formations have close relationship with Sb, Au and poly-metallic mineralization, and the ore-forming fluid show strong correlation with fossil hydrothermal water. There occur abundant cherts in the Mesozoic and Cenozoic strata in southern Tibet. Some of them possess characteristic hydrothermal structures such as layered, laminated, massive and breccia structures. Ratios of A1/（AI＋Fe＋Mn）, Co/Ni, Fe/Ti and TiO2-A1203 demonstrate that their origin is related to hydrothermal sedimentation. The chert formations have close relationship with Sb, Au and poly-metallic mineralization, and the ore-forming fluid show strong correlation with fossil hvdrothermal water.

XU Xiaohui,CHEN Hui'e and WANG Gangcheng College of Construction Engineering,Jilin University,Changchun 130026,China

On the basis of geological investigating work and experimental studies on slide zone soil of one landslide in Tibet,the authors analyzed granulometric composition,clay mineral composition and physical and mechanical properties for the soil in the slide zone.The soil samples are gravel containing fine particle.Particles larger than 2 mm occupy the main proportion with the content 51.5%--68.5%.The relative content of clay minerals is low.The clay minerals are illite smectite mixed layer and kaolinite,and their relative contents are 6%--13% and 4%-11%,respectively.The main mineral ingredient is quartz and the relative content is over 30%.Therefore,the soil’s hydrophily is poor.The cohesion and internal friction angle are high,causing preferable physical-mechanical features of slide zone soil.On the basis of the obtained data,the landslide stability is evaluated by means of limit equilibrium method.The safety factors are 3.191 and 1.92 respectively under both natural and normal water level conditions.The study results show that the landslide is stable.It can provide the appropriate basis and reference for landslide stability evaluation and landslide control in Tibet.

Investigation on the Site of the 2003 South Bomi (Tibet) M_S5.7 Earthquake

An earthquake with magnitude of 5.7 took place on Aug. 18, 2003 in the Nyingchi Region, Tibet. The macroseismic epicenter was located in the unpopniated high mountain area, 13 km south of Zhamo town, Bond County. The seismic intensity in the meizoseismal region was Ⅶ degree. The Ⅶ and Ⅵ areas were 2000 km^2 and 11000 km^2 , respectively. This seismic event is related to the movements of the Lhari fault trending in the NW direction and the ZhamoManiweng fault trending in the NE direction. As a result of this earthquakes, the buildings in the areas were badly damaged.

Multivariant statistical analysis for diagenetic information of chert from southern Tibet,China

There are large scale chert formations of different ages exposed widely in southern Tibet, along Yarlung-Zangbo suture zone. The typical chert specimens were sampled from Pengcuolin, Xialu and Zongzhuo profiles. Multivariate statistical analysis is applied for effectively extracting the geochemical information of the chert, and the raw data are processed by R-factor analysis. The first, second and third factors representing terrigenous, authigenic and hydrothermal constituents are extracted from the analysis results. From Pengcuolin, Xialu to Zongzhuo chert profiles, the variance ratios of continental and authigenetic factors become higher （ 51. 1% →62.9 % →91.6 % ）, while hydrothermal factor rapidly decrease （ 40. 9 % →32.2 % →0 ）. This tend- eney also present in the analysis for traee elements, indicating that Pengeuolin chert is hydrothermal origin, The Zongzhuo chert belong to normal sedimentation and the Xialu chert exhibit normal deposition interacted with hydrothermal sedimentation. The facts provide significant implications for understanding the diagenetic and palaeomineralization information of southern Tibet.

Palynological evidence sheds new light on the age of the Liuqu Conglomerates in Tibet and its geological significance

The Liuqu Conglomerates consist of a suit of terrestrial molasse deposits formed in a foreland basin of the Himalaya-Tibet orogenic belt before the collision of India and Eurasia.These deposits record considerable geological information regarding the late tectonic evolution of the Neotethyan ocean.The palynological study of interlayers of mudstone and mud-sandstones indicates an Oligocene age.The palynological assemblage consists mainly of deciduous broad-leaved angiosperms,with some coniferous gymnosperms and evergreen broad-leaved angiosperms.The deposits reflect a broad-leaved deciduous forest or mixed with conifer-broad-leaved forest ecotypes,showing a warm-temperate or temperate zone climatic environment.This work provides significant new information about the tectonic evolution,paleogeography,and paleoenvironment of southern Tibet during the Cenozoic.