祁连山北缘早中更新世新构造运动的地层记录

巳有研究发现在早、中更新世之交,青藏高原及其领区发生重大的构造隆升事件,并命名为“昆仑-黄河运动”,简称昆黄运动。河西走廊是青藏高原北缘祁连山的山前凹陷。在走廊西端酒西盆地老群庙背斜开展的古地磁和ESR年代学研究发现祁连山在约1.23MaBP发生构造活动,造成玉门砾岩内部出现不整合;第2幕强烈活动发生于0.93-0.84Ma,造成河西走廊地区酒泉砾石层和玉门砾岩区域性角度不整合。这两次构造运动在时间上与昆黄运动吻合。因此,本研究提供了昆黄运动在青藏高原北部表现的新证据。     

Molecular phylogeny of the specialized schizothoracine fishes （Teleostei： Cyprinidae）,with their implications for the uplift of the Qinghai-Tibetan Plateau

Molecular phylogeny of three genera containing nine species and subspecies of the specialized schizothoracine fishes are investigated based on the complete nucleotide sequence of mitochondrial cytochrome b gene. Meantime relationships between the main cladogenetic events of the specialized schizothoracine fishes and the stepwise uplift of the Qinghai-Tibetan Plateau are also conducted using the molecular clock, which is calibrated by geological isolated events between the upper reaches of the Yellow River and the Qinghai Lake. Results indicated that the specialized schizothoracine fishes are not a monophyly. Five species and subspecies of Ptychobarbus form a monophyly. But three species of Gymnodiptychus do not form a monophyly. Gd.integrigymnatus is a sister taxon of the highly specialized schizothoracine fishes while Gdo pachycheilus has a close relation with Gd. dybowskii, and both of them are as a sister group of Diptychus maculatus. The specialized schizothoracines fishes might have originated during the Miocene(about 10 MaBP), and then the divergence of three genera happened during late Miocene (about 8 MaBP). Their main specialization occurred during the late Pliocene and Pleistocene (3.54-0.42 MaBP). The main cladogenetic events of the specialized schizothoracine fishes are mostly correlated with the geological tectonic events and intensive climate shift happened at 8, 3.6, 2.5 and 1.7 MaBP of the late Cenozoic.Molecular clock data do not support the hypothesis that the Qinghai-Tibetan Plateau uplifted to near present or even higher elevations during the Oligocene or Miocene, and neither in agreement with the view that the plateau uplifting reached only to an altitude of 2000 m during the late Pliocene(about 2.6 MaBP).     

青藏高原的地质特征与形成演化

 青藏高原由于在全球所处的特殊地位,一直是各国科学家关注和竞争研究的热点地区,但仍有众多科学问题尚未达成一致。结合最新的研究进展,着重分析讨论青藏高原形成演化中的隆升过程及其地质学证据和动力学问题。青藏高原是一个独特的地质单元,有着条块相间的构造格局,地壳厚度巨大,其隆升已是不争的事实,在古生物学、沉积学、古地貌学、岩溶学和古地磁学等方面仍在积累大量证据,但对隆升过程的具体细节仍有不同认识。目前在探测地壳的精细结构方面取得了长足进展,对青藏高原下方俯冲的前沿位置、几何形态和运动方向等取得了相对统一的认识。     

青藏高原：全球气候变化的驱动机与放大器──Ⅲ．青藏高原隆起对气候变化的影响

新生代出现的几次重大气候变化事件与青藏高原形成过程中经历的几次强烈构造运动在发生年代上的良好对应关系表明两者存在紧密的联系．或许正是青藏高原的隆起导致了气候的巨大变化和现代东亚季风的形成及加强．高大的高原对大气系统有两个重要影响，热力作用和动力作用．它们在亚洲冬季形成蒙古高压、夏季形成印度低压，从而导致东亚季风出现．青藏高原越高，其对大气的作用越显著，形成的蒙古高压、印度低压和东亚季风越强大．因此，东亚季风的形成和加强是青藏高原隆起的结果．东亚季风的加强和高原动力作用使西风带波动增加，造成冰期极地冷空气不断南侵、气候波动变大．青藏高原抬升和季风造成的化学风化增强还使大气ＣＯ２含量降低、气候变冷．因此，青藏高原隆起是控制新生代气候变化的重要因素．     

黄土高原朝那剖面风尘堆积序列磁化率的古环境意义

黄土高原中部连续的风尘堆积黄土-红粘土序列,蕴含着东亚季风演化与高原隆升等重要的古气候与构造信息.结合已有的古地磁年代,根据磁化率的变化特征对黄土高原中部朝那黄土-红粘土剖面记录的古环境变化进行了划分,共划分I(8.1～5.6 MaBP)东亚季风的初显期、Ⅱ(5.6～4.8 MaBP)东亚夏季风开始增强期、Ⅲ(4.8～...     

1.2～0.6MaBP青藏高原的隆升与东亚地表各圈层的相互作用

结合近年来黄土、河流阶地、冰冻圈、沙漠、植被等地表各个圈层在1.2～0.6 MaBP青藏高原构造隆升期间环境变化的最新研究成果,综合论述了在此期间青藏高原的隆升对地表其他各个圈层的影响.研究表明:1.2～0.6 MaBP期间,青藏高原的隆升对东亚地表环境产生了重大影响,中国内陆主要沙漠(主要是西部沙区的沙漠)在这一时期形成并极端扩张;黄土在祁连山、昆仑山、天山等高山山前和西秦岭等地开始大范围地堆积;以昆仑山和念青唐古拉山为代表的西部高山开始了冰冻圈的发育,各地植被变化都不同程度地反映了环境的逐步干旱化.结合这些研究,提出了1.2～0.6 MaBP期间东亚地表圈层间相互作用的简单模式,并探讨了青藏高原隆升与地表圈层变化之间的内在耦合.     

祁连山东段冲积扇的发育时代及其成因

第四纪期间祁连山东段山麓地带广泛发育了多级冲积扇,它们是研究区域构造抬升与气候变化最为直接的载体.本文主要通过ESR,IRSL以及14C等绝对测年手段对该区冲积扇的形成年代进行研究,结果表明祁连山东段北麓最高级冲积扇形成于0.85 MaBP,而毛毛山南麓的最高级冲积扇形成于0.43 MaBP.随后各地又相继发育了0.25,0.16,0.06,0.01 MaBP等多级冲洪积台地.根据主要冲积扇的形成年代及其与区域构造气候事件的对比,认为它们是构造运动与气候变化共同作用的产物.     

Uplift processes for the Qinghai-Tibet Plateau: A comparative study of Yecheng section and Siwalik group

Comparative studies of the Yecheng section at the northern piedmont of the Kunlun Mountain, and the Surai Khola section at the southern piedmont of the Himalayan Mountain, indicates that the Qinghai-Tibet Plateau is dominated by continuous uplift over the past 10 Ma. And the effective time scale for dividing the uplift stages would be 1 Ma. The uplift processes of the entire plateau can be divided mainly into three stages, i.e., a slow uplift stage (10.0-6.0 MaBP), a transitional uplift stage (6.0-2.5 MaBP) and a rapid uplift stage (since 2.5 MaBP). The plateau might have risen to 2000 m above sea level by 4.6 MaBP in response to uplift and to more than 3000 m by 2.5 MaBP.     

Speculation on the timing and nature of Late Pleistocene hunter－gatherer colonization of the Tibetan Plateau

1 Human biogeography on the edge The Qinghai-Tibetan Plateau occupies nearly 1.25 million km2 of the Asian continent and reaches an average elevation of more than 4000 m a.s.l. (Fig. 1). In addition to playing a critical role in global climate systems[1,2], the plateau is distinguished as the largest continuous high elevation ecosystem on the planet. This harsh, barren Fig. 1. Map of the Qinghai-Tibetan Plateau (left) and an elevation cross-section from the Badanjaran Desert in the n…     

Global pollution shown by lead and cadmium contents in precipitation of polar regions and Qinghai-Tibetan Plateau

The analysis of the major ions, lead and cadmium has been performed for snow-pit samples collected from the Arctic, the Qinghai-Tibetan Plateau and the Antarctic Ice Sheet. These snow pits were excavated respectively from the snowpack in Canadian Northwest Territory (NWT) and the central Arctic, three glaciers on the Qinghai-Tibetan Plateau and surface snow along the route of the International Trans-Antarctic Expedition (ITAE). The source regions for the lead pollution of central Arctic have been identified by analyzing of stable lead isotopic ratios, meteorological and atmospheric chemistry studies. It shows that the central Arctic is still under intensive lead input, despite the fact that lead content in Greenland Ice Sheet displays a rapid decreasing since the 1970s due to US and some European countries’ campaigns to reduce lead-containing gasoline-additives. This is because there are multiple lead sources for the central Arctic, including the countries that have not performed gasoline-additives reducing. The backgrounds of atmospheric aerosol compositions, as well as the concentrations of lead and cadmium in precipitation of the early 1990s, are contrasted among the Arctic, Antarctica and Qinghai-Tibetan Plateau. The measured lead content in the snowfall at the typical sites of the three regions is divided into natural (background) and anthropogenic components. It is found that natural lead concentration (mainly crustal and/or sea-salt lead) is roughly equal among the three regions (< 3×10¹²g · g¹). However, the percentage of the natural lead to the measured lead is negligible in precipitation in the central Arctic and the Qinghai-Tibetan Plateau, while it is considerable in Antarctic precipitation. The anthropogenic component of lead (>50% in Antarctic precipitation, >97% in the Arctic and the Qinghai-Tibetan Plateau ) is mainly responsible for the lead input to both polar regions and to the Qinghai-Tibetan Plateau. Lead pollution may have spread into the whole troposphere and the most remote regions on earth.     

Development of a pediment on western slopes of Liupan Mountain related to the Neotectonic Uplift

The late Cenozoic uplift of Qinghai-Xizang Plateau plays an important role in adjacent geomorphic evolution and depositional environments. Liupan Mountain, located at the northeast margin of Qinghai-Xizang Plateau, has different landforms on the east and west sides. Recently, a pediment, which lies above the highest terrace of the Yellow River at the northeast edge of Longzhong Basin, has been described. The paleomagnetic measurements indicate that the pediment had developed at least 1.8 MaBP and its age is in accordance with that of the peneplains near Lanzhou and Linxia, in the southwest of Longzhong Basin. The results suggest that the Longzhong Basin lying to the west of Liupan Mountain had been subject to erosion and developed an extensive pediment; this pediment is named the Gansu Period Peneplain. It also indicates that Qinghai-Xizang Plateau and Liupan Mountain were uplifted strongly at that time, which caused not only the end of pediplanation but also Yellow River appearance and loess accumulation.     

Deep seismic reflection profile across the juncture zone between the Tarim Basin and the West Kunlun Mountains

Fine structures of the crust and upper mantle of the basin-and-range juncture on the northwestern margin of the Qinghai-Tibetan Plateau are first delineated by the deep seismic reflection profile across the juncture zone between the Tarim Basin and the West Kunlun Mountains. Evidence is found for the northward subduction of the northwest marginal lithosphere of the Qinghai-Tibetan Plateau and its collision with Tarim lithosphere beneath the West Kunlun Mountains. The lithosphere image of the face-to-face subduction and collision determines the coupling relationship between the Tarim Basin and the West Kunlun Mountains at the lithosphere scale and reflects the process of continent-continent collision.     

Magnetostratigraphy of Late Cenozoic fossil mammals in the northeastern margin of the Tibetan Plateau

~~Magnetostratigraphy of Late Cenozoic fossil mammals in the northeastern margin of the Tibetan Plateau~~~~     

论青藏高原大气折射对地面精密测量的影响

首次提出了青藏高原大气折射对地面精密测量影响的特殊性问题，论述了开展高原大气折射研究的重要意义，分析了国内外研究现状，阐明了研究的目标和主要内容。     

Early tectonic uplift of the northern Tibetan Plateau

The Hexi Corridor is the northmost foreland basin of the Tibetan Plateau and its formation is controlled by the northern marginal fault of Tibet, Altyn Tagh Fault （ATF）-North Qilian Shan marginal Fault （NQF）, and the southern Kuantan Shan-Longshou Shan Fault （KLF）. So its study is important to understanding the mechanism of Tibet formation and its influence on global climate change. The oldest Cenozoic sediments in the Corridor is the Huoshaogou Formation which consists of terrigenous fine conglomerate, sandstone, sandy mudstone and mudstone, depositing in al- luvial to lacustrine and fan delta sedimentary environments. Detailed paleomagnetic measurements of this sequence at Yumen clearly reveal eleven pairs of normal and reversed polarities. Fossil mammals found around the section support that most of the observed polarities can be well correlated with chrons between 13n and 18r of the standard geomagnetic polarity time scale, yielding ages of 40.2-33.35 Ma. The mean declinations of this sequence and its immediately above stratigraphy indicate an 18.3° rapid clockwise rotation of the Hexi Corridor. Since this sequence has been strongly folded and is capped by an angular unconformity, we think that the presence of the thick alluvial fan conglomeration at the bottom of the foreland basin may indicate the initial deformation and uplift of the northern Qilian Shan. This process could occur at latest at 40.2 Ma, driven by the faults NQF and KLF that thrust onto the Hexi corridor respectively from its southern and northern margins. These faults are in an early response to the collision of India with Asia, while the unconformable termination and rotation of the Huoshaogou Formation at -33.35 Ma indicate other early episode of rapid tectonic deformation and uplift of the northern Tibet.     

冻土退化过程中植被覆盖度的变化研究

在全球气候变暖的背景下,青藏高原的多年冻土出现了不断退化的现象.退化的多年冻土隔水作用减弱或消失,并导致依赖于冻结层上水的植被变化.在模拟高原多年冻土分布的基础上,分析了冻土的退化过程植被覆盖度的变化,结果表明,冻土的变化可分为3个阶段:冻土稳定段(80年代)、冻土快速退化段(90年代)和冻土缓慢退化段(最近十几年).同时,采用GIMMS(global inventory modeling and mapping studies)第3代NDVI数据(1982—2012年)分析青藏高原植被覆盖度的斜率变化特征,结果显示:在近31a来,青藏高原的植被覆盖度斜率整体上呈微弱增加趋势;植被覆盖在冻土退化的3个时段内的变化特征为:从20世纪80年代冻土相对稳定期到90年代的冻土退化期,比退化面积增大11%;近十几年来,冻土退化逐步减缓,植被退化的增幅减弱,面积比90年代增大了3%,但退化的区域更为集中.冻土退化与植被的变化机制复杂,本文的分析与发现对理解冻土对生态的影响有一定的意义.     

青藏高原地区生态边坡抗冲刷试验研究

 为减少交通工程建设对青藏高原生态环境的影响,分析了青藏高原地区降雨特性,制定了3个地区的暴雨公式;用青藏高原典型土壤进行了裸土、纯草皮、三维网草皮的边坡冲刷试验,获得了两种草皮的抗冲刷流速,并与西安黄土的抗冲刷流速进行对照;考虑坡面微地形的影响,将坡面水流概化为抛物线形浅沟流,通过现场实测确定了相关参数;计算了西宁、玉树、拉萨、德令哈4个地区的边坡水流参数,并结合室内冲刷试验结果,提出适用于4个地区的生态边坡防护方案。     

Formation of the Yazi Spring Stream and its significance on tectonics-climate on the northern slope of Kunlun Mountains

The sequences of fluvial terraces in the Yazi Spring Stream are signs of the stepwise uplift of the Kunlun Mountains in the northern part of the Tibetan Plateau since the Late Pleistocene. Geomorphic and sedimentary features of the terraces reveal that they have resulted from the phased tectonic uplift and the consequent river incision in the northern plateau. Using the method of Single-aliquot Regenerative-dose （SAR） Protocol and Radiocarbon ^14C dating, the deposit ages of three-grade terraces were obtained, which are 57.5, 12.8 and 5.7 kaBP, respectively. The features and ages of terraces reveal that the incision rate of the stream accelerated at the beginning of the Holocene. The incision rate changed suddenly at 12.8 KaBP, from 0.43±0.07 mm/a to 1.59±0.55 mm/a. This implicates that uplift of the Kunlun Mountains is intensive at the first onset of the Holocene, corresponding to the obvious change of slip-rate on the AItyn Tagh Fault. But its uplift rate is much lower than that of the latter, which suggests that growth of the northern margin of the Tibetan Plateau is stronger than its interior.     

青藏铁路格拉段常见灾害的扩散演化机理及应对策略研究

青藏铁路格拉段地处海拔最高、面积最大、气候条件最为恶劣的青藏高原,特殊的地理、地质、气候条件使得青藏铁路伴生了一些常见灾害。文章总结了青藏铁路常见灾害的地域分布特征,分析了其扩散演化路径,阐述了其扩散方式,最后提出青藏铁路在运营过程中的一些应急策略,以期为青藏铁路的运行及灾害防治提供可参考意见。     

甘肃临夏盆地8～6 MaBP的构造变化

甘肃临夏盆地毛沟剖面上半部高精密度古地磁测年结果表明该剖面磁极性年龄为4.34～13.07 MaBP,其中东乡组、柳树组与何王家组的年龄分别为13.07～7.8 Ma,7.8～6.4 Ma和6.40～4.34 MaBP.该测年结果与文献[1]测得的结果基本一致.临夏盆地6.40～6.16 MaBP湖泊沉积环境突变,8 MaBP左右毛沟剖面地层磁偏角发生明显偏转,盆地中王家山剖面银川沟背斜大约在6 MaBP左右发生倾斜与变形,这表明临夏盆地8～6 MaBP经历了一次强烈的构造运动.