Quantitative Zoning Assessment of Crustal Stability Along the Yunnan-Tibet Railway Line,Western China

The planned Yunnan-Tibet railway goes through the northwest of Yunnan Province and the southeast of the Tibet Autonomous Region. Because of its location near the collision belt of the Eurasian and Indian plates, complex engineering geological conditions and difficult engineering geological problems are encountered. The study is aimed at making the zoning assessment of crustal stability along the railway line so as to provide a better base for its construction, especially its line selection. For this purpose, the following seven influencing factors of crustal stability were selected and quantified by grading and scoring： active fault, seismic activity, geo-stress field, geo-strain field, geothermal field, geo-hazard, and lithologic character. Of these factors, the active fault, seismic activity and geo-hazard are the three most prominent factors influencing the railway construction. Along the railway line there are 1731703 calculation units to be divided. The zoning assessment calculation was completed by ArcGIS-based information fusion method. The assessment results aid railway line selection and show that there are 10 stable sectors, 28 relatively stable sectors, 23 relatively unstable sectors, and 20 unstable sectors along the Yunnan-Tibet railway line.

Railway Construction in Tibet

Authored by Li Ping and Li Xinhu, the book actually is the result of research into “schemes of construction of railways in Yunnan and Tibet.” The book centers around research into the scheme of construction of the YunnanTibet Railway, conducting comprehensive studies involving political, economic, technological, social and State security fields.

Crustal stress field in Yunnan: implication for crust-mantle coupling

We applied the g CAP algorithm to determine 239 focal mechanism solutions 3：0≤MW≤ 6：0） with records of dense Chin Array stations deployed in Yunnan,and then inverted 686 focal mechanisms（including 447 previous results） for the regional crustal stress field with a damped linear inversion. The results indicate dominantly strike-slip environment in Yunnan as both the maximum（r1） and minimum（r3） principal stress axes are sub-horizontal. We further calculated the horizontal stress orientations（i.e., maximum and minimum horizontal compressive stress axes： S H and S h, respectively） accordingly and found an abrupt change near ＊26°N. To the north, S H aligns NW-SE to nearly E-W while S h aligns nearly N-S. In contrast, to the south, both S H and S h rotate laterally and show dominantly fan-shaped patterns. The minimum horizontal stress（i.e., maximum strain axis） S h rotates from NW-SE to the west of Tengchong volcano gradually to nearly E-W in west Yunnan, and further toNE-SW in the South China block in the east. The crustal strain field is consistent with the upper mantle strain field indicated by shear-wave splitting observations in Yunnan but not in other regions. Therefore, the crust and upper mantle in Yunnan are coupled and suffering vertically coherent pure-shear deformation in the lithosphere.

UPLIFT AND DENUDATION AT SOUTHEAST MARGIN OF TIBET PLATEAU IN QUATERNARY

The southeast margin of Tibet plateau mainly consists of the Western Yunnan plateau (WYP). The uplift and denudation at the southeast margin of Tibet plateau can be represented by that of the WYP. Based on the uplift of ancient plantain surface, river terrace and sedimentary response in peripheral basins of the WYP, suggest that the WYP experienced a rapid uplift and denudation in Quaternary. The WYP have been uplifted about 610～700m, and eroded away about 1095～1600m since Quaternary, average denudation rate reach 0 68～0 94mm/a. Uplift rates in different time interval were calculated according to river terrace. Relations between WYP and Tibetan plateau are discussed further..The Yinggehai basin located at the south termination of the Red River fault, it is the younger (mainly Neogene) pull\|apart basin, which developed at releasing bend of the Red River right\|lateral wrench fault. Since the Neogene, the subsidence center of the Yinggehai basin shifted southward and, connected with the Southeast Hainan basin. Both basins collected large amounts of the Holocene and Quaternary deposits of marine origin. They are peripheral marine basin of the WYP.. Silicate clastic sediments in both basins have been large supported from the WYP into both basins through the Red River system. The total volumes derived from the WYP in the Neogene and Quaternary is 2 8004×10 14 t(1 and 5 1206×10 14 t. The sedimentation rate in Yinggehai basin rose from 0 52mm/a in the Neogene to 1 39mm/a in the Quaternary. The facts that accumulation volume and sedimentation rate rose greatly after the Neogene, suggested a rapid uplift in the WYP. The rapid uplift was responsible for the unconformity between the Neogene and Quaternary. Elevation of ancient planation surface,and river terrace supported the rapid uplift of the WYP also. The ancient planation surface was elevated from 2500～2600m to 3000～3200m during Quaternary, seven terraces in Tue can be traced through the field area in elevation from 20 5m to 612m above the modern river surface in the Lancang River. The Jinsha River also incised into bed rocks about 700m in Shigu. All the facts suggest that southeast margin of Tibet plateau rose rapidly; the plateau was elevated about 610～700m in the Quaternary.

THE LATE QUATERNARY RIGHT LATERAL STRIKE-SLIPPING OF ZHONGDIAN—DAJU FAULT IN NORTHWEST YUNNAN, CHINA

The Zhongdian—Daju fault is the transitional fault connecting the Kalakorum\|Jiali right lateral strike slip faulting zone and the Red River Fault, and a part of the south boundary of the eastward extrusive Tibet plateau. Field observations, associated with the analyses of the satellite images and air photographs, show that the Zhongdian—Daju fault, a 250km long fault in northwest Yunnan, is a nascent right lateral strike slip fault zone with the slip rate of 2～8mm/a. The Zhongdian—Daju fault is not a simple right lateral strike slip fault. There are several subparallel, slightly en échelon fault strands from Deqing to Yongsheng with the total length of 200km and perhaps 250km. Like the typical strike\|slip faults in this area, the morphological features of the fault, which can be seen clearly in the satellite images, are characterized as straight volleys and displaced gullies and ridges. In addition, Several Quaternary basins distribute along Zhongdian—Daju fault. The are controlled by the right lateral strike slipping of the fault in late Quaternary.

Episodes of Cenozoic Gold Mineralization on the Eastern Margin of the Qinghai-Tibet Plateau:40Ar/39Ar Dating and Implication for Geodynamic Events

A lot of new gold deposits have been found on the eastern margin of the Qinghai-Tibet Plateau during the past two decades. Among them, three main types of gold deposits have been recognized, including quartz-vein-type, shear- zone-type and porphyry-type. The former two types of gold deposits are mainly hosted within metamorphic rocks, while the latter is related to Cenozoic magmatism. Although all of these gold deposits are believed to have been formed during the uplift process of the Qinghai-Tibet Plateau in the Cenozoic era (Wang et al., 2002b), precise isotopic age constraints have still been lacking until quite recently. This paper presents new 40Ar/39Ar data of some gold deposits on the eastern margin of the Qinghai-Tibet Plateau, which indicate that gold mineralization in the region occurred in response to the episodic stages of the orogenies. Recently obtained 40Ar/39Ar data on quartz and feldspars from several gold deposits, such as the Sandiao deposit, the Baijintaizi deposit, the Pusagang deposits, provide new constraints on gold mineralization on the eastern margin of the Qinghai-Tibet Plateau. Geochronological studies of gold deposits along the Daduhe River indicate that there are three stages of gold mineralization. The early two stages occurred as early as 65.1 Ma in the Shuibaiyang deposit and 58.95 Ma in the Ruoji deposit, while the latter stage occurred as late as 25.35 Ma in Baijintaizi and 24.70 Ma in Sandiao. Isotopic dating of three plagioclases from the Beiya deposit, Zhifanggou deposit and Luobodi deposit and a K-feldspar from the Jinchangqing deposit in Yunnan Province indicates that these deposits were formed at two stages. The Zhifanggou and Jinchangqing deposits have early stage records as old as 58.82 Ma in Zhifanggou and 55.49 Ma in Jinchangqing, but all of the above four deposits in Yunnan have late stage records of 23.18 Ma in Jinchangqing, 24.54 Ma in Zhifanggou, 24.60 Ma in Luobodi and 24.56 Ma in Hongnitang. The above results suggest that the gold deposits on the eastern margin of the Qinghai-Tibet Plateau were formed concentratedly at two main episodes, i.e. the end of the Paleocene (about 58 Ma) and the boundary between the Paleogene and the Neogene (about 25 Ma). The later episode appears to be looks like more important and was coupled with the Sichuan movement, which was extensively activated at that period. The beginning of the Cenozoic Era (about 65 Ma) might be another episode of gold mineralization, but only one deposit (Shuibaiyang) in this study has been proved to have been be formed at this stage and might be earlier than the initial collision between the Indian Plate and the Eurasia Plate. In view of geology, the above three episodes of gold mineralization are associated with three events of tectonic- magmatism and/or fluid events. Even though the gold deposits (for example, the Shuibaiyang deposit, Ruoji deposit and Pusagang deposit) were formed at different episodes, all of them are genetically related to tectonic movements in large- scale shear zones. It looks like theat tectonic events (including large-scale strike-slip) between Paleogene and Neogene had a wide influence upon gold mineralization, with new deposits formed and old deposits enriched or superimposed to be a higher grade by new stage of mineralization. The above data suggest that gold deposits were not only concentrated in some areas, but also formed mainly at different boundaries of geological times, indicating that there existed some peak stages of gold mineralization (metallogenic episodes), and that the gold deposits were formed mainly by episodic mineralization.

ALL TUNNELS ON LHASA-NYINGCHI RAILWAY COMPLETE

Construction on the last two(Mainling Tunnel and Zagar Tunnel)of the 47 tunnels pertaining to a railway linking Lhasa and Nyingchi in Tibet Autonomous Region has been completed on April 7.Lhasa-Nyingchi Railway is a section of Sichuan-Tibet Railway,which is the first electrified railway in Tibet with a total length of 435 km and a designated speed of 160 km per hour.It is expected to be completed by the end of 2020,and start operation in 2021.

EXPERIENCE THE RAILWAY FROM LHASA TO NYINGCHI

On June 25,2021,Tibet's first ectric railway,the Lhasa-Nyingchi Railway,was officially put into operation.This is the third railway to be opened in the Tibet Autonomous Region after the Qinghai-Tibet Railway and the Lhasa-Shigatse Railway.

滇西高黎贡山地区培里伟晶岩型锂矿化的发现及其意义

稀有金属锂矿是我国紧需的战略性矿产资源。滇西地区是我国重要的稀有金属成矿远景区,但目前区内已知的稀有金属资源主要为Be-Nb-Ta-Sn矿,鲜有锂矿的报道。本研究首次在滇西高黎贡山培里地区发现了锂辉石伟晶岩型锂矿,为云南省新增一处有潜力的锂辉石型伟晶岩锂矿床,对区域稀有金属锂矿床的找矿工作具有重要意义。6个样品的全岩主微量元素分析显示培里地区伟晶岩主要发育有Li、Be、Rb、Cs、Nb、Ta矿化。LA-ICP-MS铌钽矿U-Pb年代学结果显示培里地区锂矿伟晶岩形成于18.4±0.3Ma,这一结果与共生的锡石U-Pb年代学(17.5±1.2Ma)结果一致,表明其为新生代成岩成矿作用产物。这一成矿年代与高黎贡山地区变质年代以及淡色花岗岩成岩年代一致,暗示培里伟晶岩可能为变质重熔产物,也可能是淡色花岗岩进一步结晶分异的产物。在大区域尺度上,该成矿事件与藏南稀有金属成矿时代一致,结合区域显著的地球化学背景异常,我们认为滇西地区可能是喜马拉雅稀有金属成矿带的南延部分,具有良好的稀有金属锂矿找矿前景。

滇藏铁路沿线重要活动断裂带晚第四纪活动性初步研究

滇藏铁路位于青藏高原东南缘板块碰撞和构造活跃的地形急变带,沿线活动断裂发育,地震频发,地震烈度强,且地质灾害频繁,其规划施工建设和长期运营面临的地质安全风险问题严峻。滇藏铁路香格里拉—波密段沿线发育了哈巴—玉龙雪山东麓断裂带、中甸—龙蟠断裂带、德钦—中甸—大具断裂带、维西—乔后断裂带、金沙江断裂带、巴塘断裂带、澜沧江断裂带、怒江断裂带、边坝—洛隆断裂带、嘉黎—察隅断裂带等10余条活动断裂带。受断裂黏滑位错、蠕滑变形和引发强震风险的突出影响,迫切需要厘定区域活动断裂带的几何展布和活动性。基于前人资料、遥感解译和野外调查,本文总结分析了沿线10余条活动断裂带的几何展布、运动性质、滑动速率和古地震历史等,以期为滇藏铁路等国家重大工程规划建设与安全运营提供基础资料。

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。

20世纪初金敦·沃德对滇藏交界怒族人群的考察述论

20世纪初,英国博物学家金敦·沃德数次前往滇藏交界的怒江一带进行旅行和考察,他在收集植物种子的同时,对该地区的民族文化予以较多的关注,尤其是对分布于该地区的怒族人群作了大量的记录和描述,为我们了解20世纪初滇藏交界一带怒族人的生活样貌提供了重要的资料参考。金敦·沃德根据自己的观察,把地处滇藏交界地区的怒族人群从文化特征上分为“黑”怒族和“白”怒族两个亚群体,这两个怒族的亚群体之间,虽然存在生态环境与文化特征上的巨大差异,但经济上仍保持着紧密联系与互相依赖的关系。从金敦·沃德的考察和记录中,我们能够看到地处滇藏交界地区的怒族在20世纪初的基本生活样貌及其与毗邻民族及内地民族间的交往与交融情况。

川藏滇青民族服饰研究对铸牢中华民族共同体意识的价值思考

针对川藏滇青民族服饰研究如何有利于铸牢中华民族共同体意识,采用文献整理方法,从历史的角度,对川藏滇青民族服饰进行了梳理和分析,得到川藏滇青民族服饰研究是有利于积极落实、落细、落小、落巧“铸牢中华民族共同体意识”这一民族工作重大命题的全民化、生活化、国际化举措。研究表明,对川藏滇青民族服饰的研究和保护,有利于在弘扬优秀的民族服饰文化的基础上,增强国家意识和民族团结意识,增强中华各民族的凝集力,铸牢中华民族共同体意识。

滇西新生代超钾质煌斑岩的元素和Sr-Nd同位素特征及其对岩石圈地幔组成的制约

系统分析了滇西早第三纪晚期煌斑岩的主元素、微量元素和Sr-Nd同位素组成。绝大多数煌斑岩属超钾质系列岩石(K2O/Na2O=2.1～5.2),少数为钾玄质系列(K2O/Na2O=1.6～1.7)。这些超钾质煌斑岩富集大离子亲石元素、轻稀土元素和Pb,亏损高场强元素,具有高的初始87Sr/86Sr比值(0.70624～0.70924)和负的εNd(t)值(-1.7～-4.6),类似于与俯冲环境有关的高K/Ti-低Ti钾质系列岩石。这些超钾质煌斑岩母岩浆来源于含金云母的交代地幔,经历了不同程度的结晶分异和地壳物质的同化混染。与藏北钾玄质系列岩石相比,滇西超钾质煌斑岩的Th/U比较低、Rb/Sr比较高,而且Nd模式年龄系统偏低0.1～0.4Ga,表明青藏高原北部和东南部岩石圈地幔组成存在区域性的差异。

青藏高原东南缘滇西早古生代早期造山事件

野外观察、LA-ICP-MS锆石U-Pb测年和Hf同位素分析结果表明:青藏高原东南缘滇西芒市地区存在奥陶系底砾岩与前寒武-寒武系之间的地层不整合;龙江眼球状片麻岩锆石边部U-Pb年龄约为502～518Ma,代表原岩花岗岩结晶时代;继承性锆石核部具有与拉萨地体相似的年龄谱,说明早古生代早期腾冲地体与拉萨地体属于统一陆块;锆石边部具有负的、变化范围较大的εHf(t)值(-15.7～-2.0),结合眼球状片麻岩野外、岩相学特征及区域构造背景说明原岩花岗岩来源于古老地壳部分熔融,并伴随不同程度幔源物质的注入,可能为岩浆弧的一部分。综合野外观察及锆石同位素研究结果,明确了青藏高原东南缘存在早古生代早期造山事件。与喜马拉雅、拉萨、羌塘等地体的同一时代构造事件对比,认为青藏高原东南缘滇西地区早古生代早期造山带为形成在冈瓦纳大陆北缘的安第斯型造山带的一部分,为认识冈瓦纳大陆北缘早古生代演化提供新的证据。

滇藏铁路滇西北段蒙脱石化蚀变岩的工程地质研究

滇西北地区是中国西南地区最重要的构造成矿带之一,与其相伴出现的蚀变岩常引起一系列工程问题。野外地质调查和室内测试表明:滇藏铁路滇西北段出露的多为蒙脱石化蚀变岩带,蚀变岩的黏土矿物组成绝大多数都是单矿物的蒙脱石,导致该地区的蚀变岩既是强度极低的软岩,又是典型的膨胀岩。蒙脱石化蚀变岩的发育分布与三江地区热液矿床的分布具有相似的规律。本文以滇藏铁路滇西北段为例,阐述了蒙脱石化蚀变岩的发育特征和工程特性,并针对隧道建设中由蚀变岩引起的工程问题提出了相应的防治对策。

滇藏铁路滇西北段主要地质灾害类型及发育规律的探讨

滇藏铁路滇西北段位于青藏高原东南缘向云贵高原的过渡部位，地貌复杂、峡谷深切，新构造运动十分强烈，地震活动频繁。该区的降雨主要集中在5～10月份，降雨强度大且集中。复杂的地质环境加之降雨、人类活动等外部因素造成该地区成为崩塌、滑坡和泥石流等地质灾害多发区，常引起交通中断、毁坏房屋及人员伤亡事故。本文在野外地质调查的基础上，着重阐述了滇藏铁路滇西北段主要地质灾害类型及发育规律，对于减少和预防铁路遭受崩塌、滑坡和泥石流等的危害具有重要的理论和实际意义。

滇藏铁路重大工程地质问题及线路走向研究

研究目的:在复杂地质山区条件下,选择滇藏铁路线路走向方案。研究方法:基于对滇藏铁路重大工程地质问题的研究与认识,首先采用地质选线方法初选线路走向,然后再结合线路技术条件、经济据点与吸引范围、国土资源开发等方面综合论证比选最佳线路方案。研究结论:滇藏铁路地处我国西南部新构造运动最强烈地区,沿线地质灾害突出,主要有活动断裂与地震、高地应力、地温(热)、有害气体、崩塌、滑坡、泥石流、冰川、雪崩、岩溶、软土、冻土、膨胀岩(土)、冰碛层、风沙、砂土液化、放射性等工程地质问题,可谓"世界地质博物馆"。滇藏铁路的工程地质条件远比已建成的宝成、成昆、南昆、青藏铁路更为复杂,生态环境更为脆弱,工程更为艰巨,勘察设计与施工的难度更大,堪称"世界铁路艰险工程之最"。滇藏铁路的线路走向,建议采用"大理-丽江-德钦-林芝-郎县-拉萨"方案,建设时序可先建东、西两段,后建中段,以缓解国家一次投入巨大工程投资的负担。

中新世以来滇西高原隆升的沉积学证据

印度与欧亚大陆的碰撞不仅造就了青藏高原，带动周围地区不同程度的隆起，而且通过隆升和剥蚀向高原内部盆地和环绕高原的周缘盆地提供了巨量的硅质碎屑，这些盆地的沉积记录了青藏高原隆升历史和隆升机制［１～４］。青藏高原周缘地区已成为窥视其隆升历史和机制的重要窗...

对滇藏铁路三江段工程地质问题的深化认识

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