Soft-sediment Deformation Structures Related to Earthquake from the Devonian of the Eastern North Qilian Mts.and Its Tectonic Significance

Devonian in the North Qilian orogenic belt and Hexi Corridor developed terrestrial molasse of later stage of foreland basin caused by collision between the North China plate and Qaidam microplate. The foreland basin triggered a intense earthquake, and formed seismites and earthquake-related soft-sediment deformation. The soft-sediment deformation structures of Devonian in the eastern North Qilian Mts. consist of seismo-cracks, sandstone dykes, syn-depositional faults, microfoids （micro-corrugated lamination）, fluidized veins, load casts, flame structures, pillow structures and brecciation. The seismo-cracks, syn-depositional faults and microfolds are cracks, faults and folds formed directly by oscillation of earthquake. The seismic dykes formed by sediment instilling into seismic cracks. Fluidized veins were made by instilling into the seismo-fissures of the fluidized sands. The load casts, flame structures and pillow structures were formed by sinking and instilling caused from oscillation of earthquake along the face between sandy and muddy beds. The brecciation resulted from the oscillation of earthquake and cracking of sedimentary layers. The seismites and soft-sediment deformations in Devonian triggered the earthquake related to tectonic activities during the orogeny and uplift of North Qilian Mts.

Climate change in Mt. Qomolangma region since 1971

Using monthly average, maximum, minimum air temperature and monthly precipitation data from 5 weather stations in Mt. Qomolangma region in China from 1971 to 2004, climatic linear trend, moving average, low-pass filter and accumulated variance analysis methods, the spatial and temporal patterns of the climatic change in this region were analyzed. The main findings can be summarized as follows： （1） There is obvious ascending tendency for the interannual change of air temperature in Mt. Qomolangma region and the ascending tendency of Tingri, the highest station, is the most significant. The rate of increasing air temperature is 0.234℃/decade in Mt. Qomolangma region, 0.302 ℃/decade in Tingxi. The air temperature increases more strongly in non-growing season. （2） Compared with China and the global average, the warming of Mt. Qomolangma region occurred early. The linear rates of temperature increase in Mt. Qomolangma region exceed those for China and the global average in the same period. This is attributed to the sensitivity of mountainous regions to climate change. （3） The southern and northern parts of Mt. Qomolangma region are quite different in precipitation changes. Stations in the northern part show increasing trends but are not statistically significant. Nyalam in the southern part shows a decreasing trend and the sudden decreasing of precipitation occurred in the early 1990s. （4） Compared with the previous studies, we find that the warming of Mt. Qomolangma high-elevation region is most significant in China in the same period. The highest automatic meteorological comprehensive observation station in the world set up at the base camp of Mt. Qomolangma with a height of 5032 m a.s.l will play an important role in monitoring the global climate change.

Seasonal variations in heavy metals concentrations in Mt.Qomolangma Region snow

The concentrations of heavy metals Ba, Pb, Cu, Zn and Co in snow pit collected in September, 2005 from the accumulation area of the East Rongbuk Glacier （6523 m a.s.l.）, which lies on the northern slope of Mt. Qomolangma, were determined by inductively coupled plasma mass spectrometry （ICP-MS）. Concentrations （pg/ml） of heavy metals are Ba2-227, Co2.8-15.7, Cu10-120, Zn29-4948 and Pb14-142, respectively. The 5180 was determined by MAT-252. The time period of the snow pit spans from autumn 2005 to summer 2004. Seasonal variations of the concentrations and δ^18O are observed, of which Pb, Cu, Zn and Co are much lower in summer monsoon season than that in non summer monsoon season, suggesting that different sources of heavy metals contributed to the site. EFc （crustal enrichment factors） is Co3.6, Cu27, Pb33 and Zn180, respectively. Higher EFo values of Pb, Cu and Zn suggest that Pb, Cu especially Zn are mainly contributed by anthropogenic sources.

FROM BACK-ARC BASIN TO BACK-ARC FORELAND BASIN—THE SEDIMENTARY BASIN AND TECTONIC EVOLUTION OF THE LATE CALEDONIAN—EARLY HERCYNIAN STAGES IN CORRIDOR AND NORTH QILIAN MTS

Qilian orogenic belt is a typical orogenic belt formed by polycyclic collisions between the North China plate and Qaidam microplate. Qilian ocean originated from the rift of the late Proterozoic Rodinia continent(Pangea\|850), evolved through rift basin and became an archipelagic ocean in the Caledonian stage. The Lower Proterozoic strata in Qilian area are mid\|high\|rank metamorphic rocks that constitute the metamorphic basement of the area. The “Huangyuan Movement" (in South Qilian and Central Qilian) and "Alashan Movement" (in North Qilian) in the latest Late Proterozoic formed a regional unconformity. The middle Proterozoic in the area are mudstones and carbonate rocks with stromatolites and ooids. The Qingbaikou System of the upper Proterozoic in the North Qilian and Corridor region is also mudstone and carbonate rock with stromatolites. The Qingbaikou System in Central Qilian is sandstones and mudstones. There are alkaline and tholeiite in the Sinian System in North Qilian and Corridor. The contact between Qingbaikou System and Sinian System is a regional unconformity (Quanji Movement). Qilian ocean began to rift away in Caledonian tectonic stage on the Pre\|Sinian basement.

Role of blowing snow in snow processes in Qilian Mountainous region

Blowing snow is an important part of snow hydrologic processes in mountainous region, however the related researches were rare for the Qilian mountainous region where blowing snow is frequent. Using the observation dataset in 2008 snow season in Binggou wa- tershed in Qilian mountainous region, we systematically studied the energy and mass processes of blowing snow by field observation and model simulation. The results include the analysis of snow observation, the occurrence probability of blowing snow, blowing snow transport and blowing snow sublimation. It was found that blowing snow was obvious in high altitude region （4,146 m）, the snow redislribution phenomena was remarkable. In Yakou station in the study region, blowing snow was easily occurred in midwinter and early spring when no snowmelt, the blowing snow transport was dominated in this period; when snowmelt beginning, the occur- rence probability of blowing snow decreased heavily because of the increasing air temperature, melt, and refrozen phenomena. The blowing snow sublimation accounted for 41.5% of total snow sublimation at Yakou station in 2008 snow season.

Geochemical Characteristics of C_5–C_7 Light Hydrocarbons in Gas Hydrates from the Permafrost Region of Qilian Mountains

As an important part of gas hydrates, light hydrocarbons （LHs）, especially C5 to C7 hydrocarbons with various monomer compounds, provide a wide variety of geological and geochemical information, which have received much attention from organic geochemists and petroleum geologists.

Gas Sources for Natural Gas Hydrates in the Permafrost Region of the Qilian Mountains

Objective As a new type of gas hydrates,the natural gas hydrates in the perfost region of the Qilian Mountains are characterized by their shallow burial depth,welldeveloped coal seam,high content of heavy hydrocarbons and multiple sets of mature and over-mature source rocks.Gas sources of these gas hydrates in the study area include coal-type gas and oil-type gas.

Shallow Genetic Structure of Pholis fangi in Bohai Sea and Yellow Sea Inferred from mt DNA Control Region

Pholis fangi is an ecologically important fish species inhabiting Chinese coastal waters of Yellow Sea and Bohai Sea. To investigate the genetic diversity and population genetic structure of P. fangi, a fragment of 487 bp in the first hypervariable region (HVR-1) of the mitochondrial DNA (mtDNA) control region was sequenced for 181 individuals collected from Bohai Sea and Yel- low Sea. A total of 18 polymorphic sites were detected, which defined 25 haplotypes. A moderate level of haplotype diversity (h = 0.7052) and a low level of nucleotide diversity (π= 0.0028) were detected. Both the phylogenetic tree and the haplotype network showed no significant genealogical structure difference among sampling locations. Pairwise FST comparison and hierarchical mo- lecular variance analysis (AMOVA) revealed that no significant genetic structure difference existed throughout the investigated re- gions, suggesting a high gene exchange among different populations. The results of neutrality test and mismatch distribution analysis indicated that a late Pleistocene population expansion (38000 127000 years ago) happened. Seasonal schooling migration may con- tribute to the genetically homogeneous population structure of the species.

WUGONG MTS.REGION AS A CALEDONIAN MEDIUM-HIGH PRESSURE METAMORPHIC BELT:EVIDENCE FROM b_0 VALUES OF WHITE MICAS

The Wugong Mts. region may have experienced three stages of metamorphism in Early Paleo-zoic, which may be closely related to the generations of regional deformation. The first stage ismedium-pressure metamorphism, the second medium- and high-pressure one with stress on high-pressure metamorphism, and the third low-pressure and high-temperature metamorphism. Theregion, as a whole, is a Caledonian medium-high pressure metamorphic belt.

LATE CENOZOIC LITHOLOGY AND MAGNETIC POLARITY STRATIGRAPHY IN THE JIUXI BASIN: IMPLICATIONS FOR TECTONIC EVENTS OF THE WEST QILIAN MT

The synorogenic sediments in the foreland basins preserve a potential record of varied depositional environments that respond to and are largely controlled by tectonic events of the mountain along the basin margin. In the exploration of the uplift process of the Qinghai—Tibet Plateau, research on the foreland basins around the plateau is of vital significance. Much work have been carried out on the southern margin along the Himalayas and on the eastern margin, however, seldom work was reported along the northern boundary of the plateau, this have blocked the generation of an integrative image of the evolution of the entire plateau. The Gansu Corridor, located on the northeast margin of the Qinghai—Tibet Plateau, is a Cenozoic foreland basin system formed due to the northward overthrust and overload of the plateau. Thousand of meters detrital sediments derived mainly from denudation of the Qilian orogen have deposited in the basin since Oligocene. Here we report a detailed lithologic and magnetostratigraphic work carried out on the late Cenozoic sedimentary sequences in the Jiuxi Basin, western Gansu Corridor, to investigate the neotectonism of the western Qilian Mt.

Early Cretaceous Thrust and Nappe Tectonics in North Qilian Shan,Northern Tibetan Plateau:Evidence from Field Mapping,Geochronology,and Deep Structural Analysis

The North Qilian Shan fold and thrust belt,located at the northern Tibetan Plateau and southern margin of the Hexi Corridor,is a key tectonic unit to decode the formation and expansion of the plateau.Previous studies emphasize the Cenozoic deformation due to the far-field response to the Indo-Asian collision,but the Mesozoic deformations are poorly constrained in this area.We conducted detailed field mapping,structural analysis,geochronology,and structural interpretation of deep seismic reflectional profiling and magnetotelluric(MT)sounding,to address the superposed results of the Mesozoic and Cenozoic deformation.The results recognized the North Qilian thrust and nappe system(NQTS),the root and the frontal belt are the North Qilian thrust(NQT),and the Yumu Shan klippe(YK),respectively.The middle belt is located between the NQT and the YK.Monzonitic granite zircon U-Pb dating from the middle belt yields an age of ca.415 Ma,which is similar to south NQT.The thrusting displacement is estimated at ca.48 km by structural interpretation of deep profiles.The timing is constrained in the early stage of the Early Cretaceous by the formation of simultaneous growth strata.We suggest that the NQTS has resulted from the far-field effect of the Lhasa-Qiangtang collision,and the Yumu Shan is uplifted by the superposed Cenozoic deformation.

新疆大红柳滩伟晶岩型锂矿深部结构与区域成矿模型解释

为揭示花岗岩-伟晶岩型锂等稀有金属矿成矿系统的深部结构,对西昆仑造山带大红柳滩伟晶岩型锂矿集区开展了大地电磁测深法(MT)探测。通过MT三维反演电阻率模型,探测到两个0~20 km深度范围的高阻体,反映了出露于地表的大红柳滩复式花岗岩基和半隐伏的大红柳滩东花岗岩基;20~80 km深度范围内发现的大范围高导异常,则反映了深达上地幔的地壳重熔形成的大规模长英质岩浆储库。可见,成矿母岩大红柳滩花岗岩基是有根的,而且是规模巨大深达上地幔的岩浆储库,它们为超大型大红柳滩伟晶岩型锂矿的形成提供了物源和热源。与松潘-甘孜甲基卡超大型伟晶岩型锂矿集区对比,尽管川西甲基卡地区地表出露的花岗岩有限,但MT三维反演电阻率模型显示,其也存在深达上地幔的大范围高导异常,同样反映了大规模长英质岩浆储库的存在,只是剥蚀深度浅,上侵的花岗岩未被剥蚀出来而已。从而,深剥蚀的大红柳滩地区表现为大面积花岗岩出露的“热隆”特征,而浅剥蚀的甲基卡地区则表现为花岗岩围岩“片麻岩穹隆”热变质构造特征。西昆仑-松潘-甘孜伟晶岩型锂等稀有金属巨型成矿带两端的晚三叠世超大型矿床是大规模地壳重熔长英质岩浆作用中心的产物,由于锂等稀有金属的喜水性,H2O的饱和度是造就伟晶岩型锂超常富集的关键,并在长英质岩浆储库、上侵花岗岩和伟晶岩不同分异演化阶段,锂的“预富集”为大规模伟晶岩型锂矿成矿奠定了重要基础。

祁连山地区维管植物区系特征

研究植物区系对植物资源保护及利用意义重大。祁连山地区作为生态过渡带具有丰富的植物多样性,但该区植物区系组成尚未得到系统化整理。为保证物种名录的准确性,探究植物区系分布状况,该研究通过对不同文献分散数据的搜集整理完成初步统计,利用植物标本信息进行校对以确定区系组成。结果表明:(1)祁连山地区共有维管植物1952种,隶属108科527属,其中国家级保护植物44种,受威胁植物100种。(2)祁连山地区植物以草本为主,灌木次之,乔木最少,大多耐寒、耐旱,其中仅含1种植物的属数目最多,占比最大,区系地理成分多样且温带分布型占绝对优势。(3)祁连山东段物种丰富度最高,其次是中段,西段最少;随经度西移,相似性指数下降。这表明物种组成及地理成分性质是当地气候条件、地形条件及多样化的生境类型综合作用的结果。(4)特有现象较为显著,共计中国特有种717种,祁连山地区特有种45种,反映该地区生态系统的独特性、多样性及复杂性。该研究结果为该地区物种多样性维持及资源可持续开发利用提供了本底资料及科学依据。

山区MT资料精细处理与效果分析

在山区获得的 MT野外资料不可避免地受到各种干扰及地形与局部异常体的影响 ,常规方法很难满足山区 MT资料处理与解释的要求。本文提出了山区 MT资料精细处理方法 ,与常规资料处理方法相比较 ,主要从以下三个方面进行了改进 :1TE与 TM极化曲线的精细识别 ;2二维精细反演 ;3电法、地质交互式处理解释。实测资料处理表明 :采用精细处理的方法来进行解释 ,与常规方法相比 ,得到了较好的地电剖面。

CSAMT在祁连山永久冻土区天然气水合物调查中的应用

根据祁连山永久冻土区区域地质背景、成矿条件和岩石物性特征,开展了CSAMT方法的探测研究。通过对CSAMT原始数据的分析解释,发现测区浅部0～100m深度段,呈现一似层状的高电阻率异常;在中深部存在纵向条带状低电阻率异常且电阻率呈现横向不连续变化。结合地质、钻孔资料得出浅部0～100m深度段的高电阻率异常为冻土层的反映,中深部呈现横向不连续的电阻率变化或纵向条带状低阻异常为断裂构造引起。因此认为CSAMT能够很好地分辨出天然气水合物形成、运移所需要的冻土盖层和断裂构造。

祁连山地区水资源-人口-经济-生态环境系统协调发展的时空演变及预测

利用熵权TOPSIS模型测度2007—2021年祁连山地区30个县域水资源-人口-经济-生态环境系统综合发展水平,采用耦合协调模型分析水资源-人口-经济-生态环境系统的协调度,采用GM(1,1)灰色预测模型预测2022—2031年水资源-人口-经济-生态环境协调发展状况。结果表明:祁连山地区水资源-人口-经济-生态环境系统综合发展水平逐年升高,水资源子系统发展水平呈波动上升趋势,人口子系统发展水平缓慢上升,经济子系统发展起点较低但增速较快;生态环境子系统发展起点相对较高但波动较大,且除水资源子系统外,甘肃片区指标优于青海片区。祁连山地区水资源-人口-经济-生态环境系统耦合度处于高水平耦合状态,协调度等级波动上升已达到中级协调;各地区增速具有异质性,南部增速最快,西北部次之,中部最慢。祁连山地区水资源-人口-经济-生态环境系统协调度呈现稳步上升态势,逐渐由中级协调升至良好协调等级,且甘肃片区协调度略高于青海片区。

祁连山国家公园(甘肃片区)土地利用时空演变及驱动因素分析——以黑河流域为例

黑河发源于祁连山北麓,黑河流域拥有丰富的生态资源,但受气候变化和人类活动的影响,生态风险明显增加。本文以黑河流域为例,分析2009—2018年祁连山国家公园(甘肃片区)土地利用时空演变,指出生态保护存在的主要问题,然后提出政策建议,以推动生态修复,遏制生态退化。总体来说,要强化监管,长效维持生态修复成果;加强管护能力,提升林区队伍专业化水平;提高居民生态意识,减少人类活动对环境的负面影响;开展综合治理,加速生态修复。

Adaptation Management of Mountain Tourism Service: The Case of the Source Regions of the Yangtze and Yellow River

Mountain areas are often rich in ecological diversity and recreational opportunities. Mountain tourism is thought to be an effective and important means for maintaining and expanding rural economies and, thus, improving the living conditions of rural societies. As mountain tourism service research is a professional field with several disciplines involved, a multi-disciplinary management pIatform is needed and it facilitates participation in sustainable mountain development by diverse stakeholders. With the source regions of the Yangtze and the Yellow River as a case study, this paper presents a conceptual framework for an adaptation management of mountain tourism services according to technical, policy, social and economic dimensions. The framework is based on a vulnerability assessment of mountain ecosystems, and can serve as a reference for the development of tourism service in other mountain areas.

Relationship between Granite and Eclogite on the Southern Margin of the Qilian Mountains: Evidence from Zircon SHRIMP Agesof the Aolaoshan Granite

Zircon SHRIMP ages of the Aolaoshan granite on the south margin of the QilianMts. range from 445 + - 15.3 to 496 + - 7.6 Ma (averaging 473 Ma), belonging to the EarlyOrdovician. Geochemically, the granite is similar to I-type granite and, tectonically, was formed inan island-arc environment based on relevant diagrams for structural discriminations. Consideringalso the regional geology, the authors suggest that the granite is part of an ultrahigh-pressurebelt on the south margin of the Qilian Mts. and that its formation bears a close relationship tothis belt.

CRUSTAL STRUCTURE IN EASTERN REGION OF QINGHAI—TIBET PLATEAU

A geophysical survey including Magnetotelluric sounding(MT), gravity and geomagnetism was carried out in eastern region of Qinghai—Tibet plateau in 1998. It is to be known from tectonic map that study area was divided into four blocks by three large sutures, but we have very little information on deep\|seated structure which have close relationship with evolution of Tibet plateau, our purpose is to find some deep crustal structure evidences of the blocks and sutures for understanding deep tectonic feature in this region. The geophysical survey region is located in about 97～98°E and 35～26°N, the profile with the length of 760km runs through Bayanhar, Qingtang and Gandise block in NS direction, 349 gravity and geomagnetic data were acquired simultaneously, and 31 MT sites are be placed along the profile with about 18km\|interval to detect electrical conductive feature.