Hoh Xil Region Research Articles

Distribution Characteristics and Formation Mechanisms of Rubidium and Cesium in the Water Bodies of the Northern Hoh Xil Region

Distribution Characteristics and Formation Mechanisms of Rubidium and Cesium in the Water Bodies of the Northern Hoh Xil Region

Recent rapid initiation and growth of retrogressive thaw slumps in the Hoh Xil region of the Qinghai-Tibetan Plateau

With persistent climate warming, a rapid increase in retrogressive thaw slump (RTS) activity has been observed in the permafrost region of the Qinghai-Tibetan Plateau (QTP). However, the initiation and growth dynamics of these RTSs have not yet been fully investigated. In this study, annual RTS observations from 2013 to 2021 within the Hoh Xil region (HXR), based on field investigations and satellite imagery interpretations, are presented. The total number and affected areas of RTSs in the HXR significantly increased during the last 8 years, and such an increase mainly occurred in 2016 when an anomalously high air temperature appeared during the thawing season, which induced the massive occurrence of active layer detachment slides. The mean headwall retreat rate of RTSs in the HXR ranged from 2.4–3.2 m/y from 2013, or their initialization, to 2021, and the highest headwall retreat occurred in the first 2–3 years after RTS initiation. In addition, the headwall retreat rate of RTSs in the study region was significantly affected by the climatic factors, including average daily air temperature, thawing degree days, and cumulative precipitation and also controlled by the ratio of slump floor slope to undisturbed terrain slope, the headwall height, and permafrost conditions. The study’s findings can serve as a reference for hazard mitigation and regional carbon cycle assessment of the QTP.

Microbial difference and its influencing factors in ice-covered lakes on the three poles

Most lakes in the world are permanently or seasonally covered with ice. However, little is known about the distribution of microbes and their influencing factors in ice-covered lakes worldwide. Here we analyzed the microbial community composition in the waters of 14 ice-covered lakes in the Hoh Xil region of northern Qing-Tibetan Plateau (QTP), and conducted a meta-analysis by integrating published microbial community data of ice-covered lakes in the tripolar regions (the Arctic, Antarctica and QTP). The results showed that there were significant differences in microbial diversity, community composition and distribution patterns in the ice-covered tripolar lakes. Microbial diversity and richness were lower in the ice-covered QTP lakes (including the studied lakes in the Hoh Xil region) than those in the Arctic and Antarctica. In the ice-covered lakes of Hoh Xil, prokaryotes are mainly involved in S-metabolic processes, making them more adaptable to extreme environmental conditions. In contrast, prokaryotes in the ice-covered lakes of the Arctic and Antarctica were predominantly involved in carbon/nitrogen metabolic processes. Deterministic (salinity and nutrients) and stochastic processes (dispersal limitation, homogenizing dispersal and drift) jointly determine the geographical distribution patterns of microorganisms in ice-covered lakes, with stochastic processes dominating. These results expand the understanding of microbial diversity, distribution patterns, and metabolic processes in polar ice-covered lakes.

Climatic characteristics of precipitation change and its multiscale causes over Central Qinghai–Tibet Plateau

AbstractRegional climates have changed as a result of global warming, which has sped up cirrus circulation and altered the temporal and spatial distribution of precipitation. As climate change intensifies, the pattern of precipitation in the Hoh Xil (HX) region has changed. The dislocation of rain and heat in summer hinders ecological restoration and brings great ecological threat. And it is important to clarify the causes and scopes of the midsummer drought (MSD). In this study we highlight the causes of MSD in terms of water vapour transport, circulation structure and the related influencing factors. We found that (1) the HX region gradually entered a drying‐warming process as MSD developed after 2005. (2) The change in the water vapour balance is the direct cause of MSD in the HX. (3) As a typical climate key zone, the HX is located in the transition region between the westerlies and the Indian monsoon. (4) Regional evaporation capacity is the main factor affecting the occurrence of MSD. The dominant factor shifted from being energy to water with the occurrence and enhancement of MSD. This study complements the scarce research on precipitation anomalies in the HX, provides support for clarifying the impact of climate change on the Qinghai–Tibet Plateau (TP) and contributes to understanding the trends and mechanisms of climate change over the TP under global warming.

Permafrost characteristics and potential influencing factors in the lake regions of Hoh Xil, Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau (QTP) is one of the regions in the world where permafrost and lakes are widely developed. Yet, the current understanding of permafrost characteristics surrounding large alpine lakes is still not clear. Based on the observation of permafrost surrounding Zonag Lake and Yanhu Lake (>100 km2) in the Hoh Xil region since 2012, we first investigated the permafrost characteristics and potential influencing factors around large alpine lakes on the QTP. The results indicate that the large alpine lakes have only a marginal thermal effect on the surrounding permafrost. Except for the sites located at the lake bottom and adjacent to the lakeshore, cold permafrost is extensively developed around the lakes, where the mean annual ground temperature is below −1.0℃, and the permafrost thickness is generally more than 40 m. Moreover, significant differences exist in ground temperature between boreholes located in the Yanhu Lake basin and those outside the basin, which the permafrost temperature in the lake basin is remarkably lower. These phenomena are closely related to the high soil water content around lakes. Statistical results show that ground temperature decreases and permafrost thickness increases gradually with increasing soil water content. The latent heat effects play an important role in the thermal dynamics of permafrost, which can buffer the increase of permafrost temperature under climate warming. Meanwhile, the salinity of water can weaken the thermal erosion effect of the lake on the surrounding permafrost to a certain extent. Overall, the permafrost thermal regime in the lake regions is not only controlled by altitude but also affected by soil water content. This study will provide us with a basis for understanding the state and characteristics of the frozen ground around lakes in the permafrost regions of the QTP, as well as for conducting research on the interaction of frozen ground with lakes and even the atmosphere.

Spatiotemporal variations and overflow risk analysis of the Salt Lake in the Hoh Xil Region using machine learning methods

Global warming is inducing dramatic changes in fluvial geomorphology and reshaping the hydrological connections between rivers and lakes. The water level and area of the Salt Lake have increased rapidly since the outburst of the Zonag Lake in the Hoh Xil region of the Qinghai–Tibet Plateau in 2011, threatening the downstream infrastructure. However, fewer studies have focused on its spatiotemporal variation and overflow risk over long time series. Here, we used three machine learning algorithms: Classification and Regression Trees (CART), Random Forest (RF), and Support Vector Machine (SVM) to extract the area of the Salt Lake for a long time series, analyzed its spatiotemporal variation from 1973 to 2021, and finally assessed the overflow risk. The Kappa coefficient (KAPPA) and the overall accuracy (OA) were used to evaluate the performance of the models. The results showed that Random Forest performs superior in lake extraction (KAPPA = 0.98, overall accuracy = 0.99), followed by Classification and Regression Trees and Support Vector Machine. normalized difference water index is the relatively important feature variable in both RF and CART. Before the outburst event, the area change of the Salt Lake was consistent with the variation in precipitation; after that, it showed a remarkable area increase (circa 350%) in all orientations, and the main direction was the southeast. Without the construction of the emergency drainage channel, the simulation result indicated that the earliest and latest times of the Salt Lake overflow event are predicted to occur in 2020 and 2031, respectively. The results of this paper not only demonstrate that RF is more suitable for water extraction and help understand the water system reorganization event.

A novel approach for high-quality drainage network extraction in flat terrains by using a priori knowledge of hydrogeomorphic features to extend DEMs: A case study in the Hoh Xil region of the Qinghai-Tibetan Plateau

Being a fundamental type of hydrogeomorphic parameter, drainage networks have been widely applied in the fields of geographic cartography, hydrologic and hydraulic modeling, water resource management, flood risk analysis, and so on. The rapid developments of modern remote sensing technologies have greatly improved the resolution and precision of spatial data providing a plenty of microtopographic information that could have significant impacts on the surface runoff, but most of the drainage network extraction methods have paid less attention to it especially for flat terrains. In order to deal with this problem, we propose a novel approach for high-quality drainage network extraction in flat terrains, in which the hydrogeomorphic features with the function of obstruction, guidance or collection to the runoff are considered as a priori knowledge used to extend digital elevation models (DEMs). Firstly, the hydrogeomorphic features that have obvious influences on surface runoff are classified, and used as a priori knowledge to extract drainage networks. After mathematically described by reorganizing their data into raster form and semanticizing their responses to runoff, this prior knowledge is then incorporated into a DEM to construct a Digital elevation-eXtended Model (DXM). Secondly, in order to solve the problem of erroneous or indeterminate flow directions in drainage network extraction based on the DEM alone, a method of drainage network extraction based on DXM is thereby developed. Finally, the proposed approach is applied and validated in a case study in Yanhu Lake area of Hoh Xil in the Qinghai–Tibet Plateau. The DEMs and digital orthophoto maps (DOMs) with sub-meter resolution were collected by employing unmanned aerial vehicle-based (UAV-based) structure-from-motion (SFM) photogrammetry. The hydrogeomorphic features with runoff responses were extracted from the DOMs and used as a priori knowledge. Various DXMs are constructed based on the extracted hydrogeomorphic features and DEMs to extract the drainage networks of the study area. The extraction results are qualitatively and quantitatively evaluated by visual comparisons and statistical analysis to validate the proposed approach. Additionally, the effects of DEM resolution and the presence of a priori knowledge on the quality of drainage network extraction were investigated. It is found that the DXM can clearly determine the flow directions by adding useful auxiliary information into the conventional D8 algorithm. This approach provides a new high-efficient way to extract the drainage networks in flat terrains.

Improve the Accuracy of Water Storage Estimation—A Case Study from Two Lakes in the Hohxil Region of North Tibetan Plateau

Lake water storage is essential information for lake research. Previous studies usually used bathymetric data to acquire underwater topography by interpolation method, and to therefore estimate water storage. However, due to the large area of Tibetan Plateau (TP) lakes, the method of bathymetry was challenging to cover the whole region of one lake, and the accuracy of the underwater topography, in which no bathymetric data covered, was low, which resulted in a comparatively large error of lake water storage estimation and its change. In this study, we used Shuttle Radar Topography Mission (SRTM) and in situ bathymetric data to establish the underwater topography of Hohxil Lake (HL) and Lexiewudan Lake (LL) in the Hohxil Region of North TP and estimate and analyzed the changes of lake level and water storage. The results showed HL and LL’s water storage was 5.12 km3 and 5.31 km3 in 2019, respectively, and their level increased by 0.5 m/y and 0.57 m/y during 2003−2018, respectively. They were consistent with those (0.5 m/y and 0.5 m/y) from altimetry data, and they were much more accurate than those results (0.077 m/y and 0.156 m/y) from bathymetric data. These findings indicated that this method could improve the accuracy of lake water storage and change estimation. We estimated water storage of two lakes by combining with multitemporal Landsat images, which had doubled since 1976. Our results suggested that the increasing precipitation may dominate the lake expansion by comparing with the change of temperature and precipitation and the increasing glacial meltwater contributed approximately 4.8% and 10.7% to lake expansion of HL and LL during 2000–2019 based on the glacier mass balance data, respectively.

Rapid expansion of lakes in the endorheic basin on the Qinghai-Tibet Plateau since 2000 and its potential drivers

The QTP (Qinghai-Tibet Plateau) holds the greatest concentration of high-elevation inland lakes in the world, and most of these lakes are located in the QTP endorheic basin. Accelerated lake expansion in the endorheic basin since 2000 has been confirmed by many studies, but there is disagreement as to which components of the water balance explain most of the lake expansion. In this paper, based on Landsat images, meteorological data, glacier data and permafrost monitoring data, we analyzed the spatial–temporal changes in lake area and further explored the driving factors behind rapid lake expansion in different zones in the endorheic basin. The results suggested that the spatial pattern of trends in lake area in the endorheic basin from 2000 to 2017 showed a southwest-northeast transition from contracting to slightly expanding to rapidly expanding. More importantly, the dramatic lake expansion observed in most regions was statistically significant (0.01 ~ 26.29 km2/yr). Although retreating glaciers may have contributed to lake growth, this can not fully explain the recent lake expansion. We find that increasing precipitation was the primary driver behind lake expansion, and that permafrost degradation accelerated lake expansion. Lakes on the northern slope of the Gangdise Mountains, fed by the most rapidly retreating glaciers, were relatively stable or even contracted. In contrast, most of the non-glacier-fed lakes in the Hoh Xil region and the central endorheic basin nevertheless experienced significant expansion and slight expansion, respectively, which were mainly attributed to the greatest increase in AP (annual precipitation). Remarkable lake expansion was found in the continuous permafrost zone. The increasing ALT (active layer thickness) and soil temperature of permafrost resulted in an increase in meltwater from ground ice, the partial release of soil moisture and an amount of unfrozen water content, which has contributed to supply lakes and accelerated lake expansion.

Dynamic changes in lakes in the Hoh Xil region before and after the 2011 outburst of Zonag Lake

Zonag, Kusai, Hedin Noel and Yanhu Lakes are independent inland lakes in the Hoh Xil region on the Qinghai-Tibet Plateau. In September 2011, Zonag Lake burst after the water level had increased for many years. Floods flowed through Kusai and Hedin Noel Lakes into Yanhu Lake; since then, the four small endorheic catchments merged into one larger catchment. This hydrological process caused the rapid shrinkage of Zonag Lake and continuous expansion of Yanhu Lake. In this study, based on satellite images, meteorological data and field investigations, we examined the dynamic changes in the four lakes and analyzed the influencing factors. The results showed that before 2011, the trends in the four lake areas were similar and displayed several stages. The change in the area of Zonag Lake corresponded well to the change in annual precipitation (AP), but the magnitude of the change was less than that of a non-glacier-fed lake. Although increased precipitation was the dominant factor that caused Zonag Lake to expand, increased glacier melting and permafrost thawing due to climate warming also had significant effects. After the 2011 outburst of Zonag Lake, due to the increasing AP and accelerating glacier melting, the increases in water volume of the three lakes were absorbed by Yanhu Lake, and Yanhu Lake expanded considerably. According to the rapid growth rates in water level and lake area, Yanhu Lake is likely to burst in 1–2 years.

Early Miocene expansion of C4 vegetation on the northern Tibetan Plateau

Abstract The proliferation of C4 photosynthesis in land plants marks the most important ecological shift in tropical and subtropical terrestrial ecosystems during the Cenozoic. Despite the wealth of geochemical data indicating an increased C4 biomass in the paleovegetation since the Late Miocene spatial and temporal variations of C4 plants abundance are not well known. The driving force for their expansion such as CO2 starvation, aridification and fire frequency are controversially discussed. Here we present an integrated review of the stable isotope stratigraphy, trace elements, palynology, lithological and phytolith record from early-middle Miocene lacustrine sediments in the Hoh Xil Basin. We report the first known silicified wood fossils from the genus Picea and indicate the Hoh Xil region might have already reached an elevation above 2500 m at least in the early Miocene, representing the early uplift stage of northern Tibetan Plateau. Our results show that the expansion of C4 vegetation and the appearance of Picea in the interior of the Tibet during the early Miocene may be related to early uplift of the northern Tibetan Plateau and the consequent cooling event, PCO2 decrease, and aridification. We suggest that the C4 signal in vertebrate faunas predating the early Miocene is due to the ecology of the herbivores (who preferred plants with C3 metabolism) rather than the lack of C4 plants in the vegetation.

Overflow probability of the Salt Lake in Hoh Xil Region

After the bursting of Huiten Nor in Hoh Xil Region in September, 2011, the topic on whether the water overflowed from the Salt Lake would enter into the Chumaer River and become the northernmost source of the Yangtze River has aroused wide concern from public and academic field. Based on Landsat TM/ETM+/OLI remote sensing images during 2010–2015, SRTM 1 arc-second data, Google Earth elevation data and the observation data from the Wudaoliang meteorological station, the study initially analyzed the variations of the Salt Lake and its overflowing condition and probability. The results showed that the area of the Salt Lake expanded sharply from October 2011 to April 2013, and then it stepped into a stable expansion period. On October 27, 2015, the area of the Salt Lake had arrived at 151.38 km2, which was about 3.35 times the area of the lake on March 3, 2010. The Salt Lake will overflow when its area reaches the range from 218.90 km2 to 220.63 km2. Due to the differences between SRTM DEM and Google Earth elevation data, the water level of the Salt Lake simulated would be 12 m or 9.6 m higher than the current level when the lake overflowed, and its reservoir capacity would increase by 23.71 km3 or 17.27 km3, respectively. Meanwhile, the overflowed water of the Salt Lake would run into the Qingshui River basin from its eastern part. Although the Salt Lake does not overflow in the coming decade, with watershed expansion of the Salt Lake and the projected precipitation increase in Hoh Xil region, the probability of water overflow from the Salt Lake and becoming a tributary of the Yangtze River will exist in the long term.

Late Cretaceous–Cenozoic basin evolution and topographic growth of the Hoh Xil Basin, central Tibetan Plateau

The Hoh Xil Basin in the central Tibetan Plateau was the locus of thick accumulation of terrestrial sediments from the Late Cretaceous to Neogene, providing an archive of regional tectonic activity both before and after initiation of the early Paleogene India-Asia collision. This work focuses on the stratigraphy and provenance of the poorly studied western part of the Hoh Xil Basin. Lithostratigraphy, carbonate oxygen isotopic composition, and deformation features suggest that the braided river and alluvial-fan that dominated the Kangtuo Formation in the southern West Hoh Xil subbasin can be correlated with the Late Cretaceous-early Eocene Fenghuoshan Group deposits of the East Hoh Xil subbasin, whereas deltaic, shallow lacustrine, and evaporite strata of the Suonahu Formation in the central-northern West Hoh Xil subbasin can be correlated to the middle Eocene-early Oligocene-Yaxicuo Formation of the East Hoh Xil subbasin. These observations suggest that the eastern and western parts of Hoh Xil Basin evolved as a unified basin during Late Cretaceous-Oligocene time. Detrital zircon U-Pb ages indicate that the Kangtuo Formation and Feng-huoshan Group mainly received detritus from the Qiangtang terrane to the south, whereas the age probability distributions of the Suonahu Formation and Yaxicuo Formation sandstones are more similar to zircon ages reported for the northern Qiangtang terrane and within the Hoh Xil terrane. We favor a tectonic model with Late Cretaceous-early Eocene contractional deformation and topographic growth of the south-central Qiangtang terrane that caused flexural subsidence of the south-central Hoh Xil region within a retroarc foreland basin, relative to the Tanggula thrusts in central Qiangtang. Following the onset of India-Asia collision, the locus of contractional deformation moved northward, marked by activity of the Fenghuoshan and Hoh Xil thrust systems within the Hoh Xil region, and resulting in transformation of the Hoh Xil foreland basin to a hinter-land basin. We suggest that both middle Eocene to late Oligocene upper-crustal shortening and associated thickening of the lower crust and mantle lithosphere as well as late Oligocene to Miocene loss of dense mantle lithosphere contributed to the topographic growth of the Hoh Xil Basin.

Changes in inland lakes on the Tibetan Plateau over the past 40 years

Inland lakes and alpine glaciers are important water resources on the Tibetan Plateau. Understanding their variation is crucial for accurate evaluation and prediction of changes in water supply and for retrieval and analysis of climatic information. Data from previous research on 35 alpine lakes on the Tibetan Plateau were used to investigate changes in lake water level and area. In terms of temporal changes, the area of the 35 alpine lakes could be divided into five groups: rising, falling-rising, rising-falling, fluctuating, and falling. In terms of spatial changes, the area of alpine lakes in the Himalayan Mountains, the Karakoram Mountains, and the Qaidam Basin tended to decrease; the area of lakes in the Naqu region and the Kunlun Mountains increased; and the area of lakes in the Hoh Xil region and Qilian Mountains fluctuated. Changes in lake water level and area were correlated with regional changes in climate. Reasons for changes in these lakes on the Tibetan Plateau were analyzed, including precipitation and evaporation from meteorological data, glacier meltwater from the Chinese glacier inventories. Several key problems, e.g. challenges of monitoring water balance, limitations to glacial area detection, uncertainties in detecting lake water-level variations and variable region boundaries of lake change types on the Tibetan Plateau were discussed. This research has most indicative significance to regional climate change.

Spatial-temporal variations of lake ice phenology in the Hoh Xil region from 2000 to 2011

Lake ice phenology, i.e. the timing of freeze-up and break-up and the duration of the ice cover, is regarded as an important indicator of changes in regional climate. Based on the boundary data of lakes, some moderate-high resolution remote sensing datasets including MODIS and Landsat TM/ETM+ images and the meteorological data, the spatial-temporal variations of lake ice phenology in the Hoh Xil region during the period 2000–2011 were analyzed by using RS and GIS technology. And the factors affecting the lake ice phenology were also identified. Some conclusions can be drawn as follows. (1) The time of freeze-up start (FUS) and freeze-up end (FUE) of lake ice appeared in the late October–early November, mid-November–early December, respectively. The duration of lake ice freeze-up was about half a month. The time of break-up start (BUS) and break-up end (BUE) of lake ice were relatively dispersed, and appeared in the early February–early June, early May–early June, respectively. The average ice duration (ID) and the complete ice duration (CID) of lakes were 196 days and 181 days, respectively. (2) The phenology of lake ice in the Hoh Xil region changed dramatically in the last 10 years. Specifically, the FUS and FUE time of lake ice showed an increasingly delaying trend. In contrast, the BUS and BUE time of lake ice presented an advance. This led to the reduction of the ID and CID of lake. The average rates of ID and CID were–2.21 d/a and–1.91 d/a, respectively. (3) The variations of phenology and evolution of lake ice were a result of local and climatic factors. The temperature, lake area, salinity and shape of the shoreline were the main factors affecting the phenology of lake ice. However, the other factors such as the thermal capacity and the geological structure of lake should not be ignored as well. (4) The spatial process of lake ice freeze-up was contrary to its break-up process. The type of lake ice extending from one side of lakeshore to the opposite side was the most in the Hoh Xil region.

Surface textural analysis of quartz grains from varved sediments of Lake Kusai in the Hoh Xil area, Tibetan Plateau

湖泊是风成沉积的理想载体，利用扫描电镜分析石英砂的表面微结构特征，可以用于判断石英颗粒被风或水流搬运的相对距离和湖泊的水动力条件，从而判断其沉积环境与演化历史.库赛湖位于青藏高原北部可可西里地区，是青海省沙尘天气频发的地区之一，为进一步证实库赛湖年纹层粗颗粒层的风成成因，以库赛湖沉积年纹层为研究对象，结合青藏高原北部典型沙丘沉积、库赛湖冰面风成沉积、典型河流沉积和库赛湖湖滨相水成粗颗粒沉积样品，利用扫描电镜对上述沉积物石英颗粒表面特征进行观察研究，并统计35种特征的出现频率.结果表明：库赛湖地区典型风成物石英颗粒表面具有圆形轮廓、中低浮雕、翻板、新月型撞击坑、球根状边缘、直形阶梯、弓形阶梯、碟形坑等微形貌特征；典型水成物石英颗粒表面具有V型撞击坑、小型和中型贝壳状断口、少量溶蚀坑等微形貌特征；库赛湖年纹层粗颗粒层石英颗粒表面具有圆形轮廓、低浮雕、翻板、新月形撞击坑、球根状边缘、碟形坑等明显风成特征，与研究区风成物的石英颗粒表面特征相似，而与研究区典型水成物的石英颗粒表面特征差别很大.因此，库赛湖年纹层中的粗颗粒层是由风成作用形成的.;Lake sediments containing aeolian deposits in the arid areas are one of the important archives for sedimentary studies. Surface textural analysis of quartz grains by scanning electron microscopy can provide an insight into the sedimentary history of clastic sediments, depositional environment and successive sedimentary cycles. Lake Kusai is located in almost uninhabited Hoh Xil region of the Northern Tibetan Plateau, and is one of the frequently dust storm-occurred areas occurring in Qinghai Province. In order to confirm the coarse grained layers formed by aeolian processes in varved sediments of Lake Kusai, 35 types of surface features of quartz grains are analyzed in different sediments, such as coarse grained layers in varved sediments of Lake Kusai, aeolian dune sediments, fluvial sediments, aeolian dust samples in the ice of Lake Kusai, lacustrine deposits in the lakeside. The results show that quartz grains in aeolian sediments have surface microtextures of rounded outline, low or medium relief, acuate steps, straight steps, crescent percussion marks, upturned plates, bulbous edges and dish-shaped depression, etc. The quartz grains in fluvial sediments have microtextures of angular or subangular outline, medium or high relief, V-shaped percussion cracks, small or medium conchoidal fractures, and solution pits, etc. The microtextures of quartz grains in the coarse-grained layers of varved sediments in Lake Kusai are rounded outline, low relief, acuate steps, straight steps, crescent percussion marks, upturned plates, bulbous edges, and dish-shaped depression, etc, which are similar to these of the aeolian sediments, but quite different from these of fluvial sediments. Thus, it is indicated that the coarse grained layers in varved sediments of Lake Kusai are formed by aeolian processes.

Analysis on Metallogenic Conditions of Polymetallic Ore in Hoh Xil Region: Stratigraphy, Sedimentary and Tectonics

Acta Geologica Sinica - English EditionVolume 88, Issue s2 p. 1723-1723 Meeting Abstracts Analysis on Metallogenic Conditions of Polymetallic Ore in Hoh Xil Region: Stratigraphy, Sedimentary and Tectonics Jun ZHANG, Corresponding Author Jun ZHANG College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaCorresponding author. E-mail: szxyzj@sina.cnSearch for more papers by this authorYusheng LI, Yusheng LI College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorMing TIAN, Ming TIAN College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorPeng WU, Peng WU College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorXuyuan HAN, Xuyuan HAN College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorYuhong GUO, Yuhong GUO College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorXinyoung WU, Xinyoung WU College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this author Jun ZHANG, Corresponding Author Jun ZHANG College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaCorresponding author. E-mail: szxyzj@sina.cnSearch for more papers by this authorYusheng LI, Yusheng LI College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorMing TIAN, Ming TIAN College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorPeng WU, Peng WU College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorXuyuan HAN, Xuyuan HAN College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorYuhong GUO, Yuhong GUO College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this authorXinyoung WU, Xinyoung WU College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059 ChinaSearch for more papers by this author First published: 29 December 2014 https://doi.org/10.1111/1755-6724.12385_59Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume88, Issues2Special Issue: Meeting Abstracts: The 14th Quadrennial International Association on the Genesis of Ore Deposits Symposium. August 19–22, 2014, Kunming, ChinaDecember 2014Pages 1723-1723 RelatedInformation

Spatial-temporal characteristics of lake area variations in Hoh Xil region from 1970 to 2011

As one of the areas with numerous lakes on the Tibetan Plateau, the Hoh Xil region plays an extremely important role in the fragile plateau eco-environment. Based on topographic maps in the 1970s and Landsat TM/ETM+ remote sensing images in the 1990s and the period from 2000 to 2011, the data of 83 lakes with an area above 10 km2 each were obtained by digitization method and artificial visual interpretation technology, and the causes for lake variations were also analyzed. Some conclusions can be drawn as follows. (1) From the 1970s to 2011, the lakes in the Hoh Xil region firstly shrank and then expanded. In particular, the area of lakes generally decreased during the 1970s–1990s. Then the lakes expanded from the 1990s to 2000 and the area was slightly higher than that in the 1970s. The area of lakes dramatically increased after 2000. (2) From 2000 to 2011, the lakes with different area ranks in the Hoh Xil region showed an overall expansion trend. Meanwhile, some regional differences were also discovered. Most of the lakes expanded and were widely distributed in the northern, central and western parts of the region. Some lakes were merged together or overflowed due to their rapid expansion. A small number of lakes with the trend of area decrease or strong fluctuation were scattered in the central and southern parts of the study area. And their variations were related to their own supply conditions or hydraulic connection with the downstream lakes or rivers. (3) The increase in precipitation was the dominant factor resulting in the expansion of lakes in the Hoh Xil region. The secondary factor was the increase in meltwater from glaciers and frozen soil due to climate warming.

Carbonate contents of lake sediments determined by XRD method

湖泊沉积中的碳酸盐对于气候环境具有很好的指示意义.利用化学分析方法(气量法)和X衍射(XRD)方法,对青藏高原可可西里库赛湖KS-2006孔沉积物中的碳酸盐含量进行了半定量分析.结果表明:虽然KS-2006孔沉积物中的矿物种类达9种之多,且XRD的测量误差(±5%)高于气量法的测量误差(±0.8%);但XRD法获得的KS-2006孔沉积物碳酸盐总含量的平均值(18.9%)以及波动范围(7%~39%),同气量法所获得的碳酸盐含量的平均值(19.4%)和波动范围(5.0%~30.7%)基本一致,而且二者具有很好的正相关关系(相关系数R²为0.3940),随深度的波动趋势一致,说明XRD方法在半定量分析湖泊沉积物碳酸盐矿物种类及其含量方面,具有很高的可靠性.;Carbonate in lake sediments has an indicative significance for climate and environment. In this paper, the carbonate contents were semi-quantitatively analyzed by meaning of chemical analysis(gasometric method) and X-ray diffraction(XRD method), which were from the sediments of the core KS-2006 of Lake Kusai in Hoh Xil region, Qinghai-Tibetan Plateau. The results showed that there were at least nine kinds of minerals in the core KS-2006, and the measurement error of XRD method(± 5%) was higher than that of gasometric method(± 0.8%). However, the XRD method obtained the average value(18.9%) and variation range(7%-39%) of the total carbonate contents from the sediments of the core KS-2006, which was basically identical with the average value(19.4%) and variation range(5.0%-30.7%) comparing with both of the result. Meanwhile, it showed a positive correlation between the XRD method and gasometric method, and fluctuation tendency with the depth was uniform. This indicated that the XRD method was a reliable method which can be well used to semi-quantitatively analyze the kinds of carbonate minerals and determine their content in lake sediments.

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

Abstract: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.