Identifying provenance of aeolian deposits in the mid-latitude deserts of Asia is essential for understanding formation and changes of Earth surface processes due to palaeoclimatic fluctuations. ...While some earlier studies focused on the interpretation of palaeoenvironments on the basis of aeolian deposits mainly in the desert margins and inter-dune lacustrine sediments, research on provenance of desert sands in the vast Asian mid-latitude deserts is still rare. In this paper, we present new geochemical data which provide insight to the provenance of dune sands in the Badain Jaran Desert, northwestern China, an important part of this desert belt. We sampled aeolian and lacustrine sediments in various parts of the Badain Jaran Desert, and examined their major, trace and rare earth elements (REE) in bulk samples, coarse and fine fractions, respectively. In addition, we took and analyzed samples from a rarely known dune field with red sands, northeast of the Badain Jaran. Our results show that the sands from the Badain Jaran Desert are generally different from those in the red sand dune field in terms of REE pattern and geochemical characteristics, suggesting different sediment origins. Geochemical composition of the aeolian sand samples indicates these sediments should be mainly derived from mixed source rocks of granite, granitoids and granodiorite. Comparing the immobile trace elements and REE ratios of the samples from the Badain Jaran Desert, red sand dune field with rocks of granite, granitoids in their potential source areas, we conclude that: (1) The aeolian deposits in the Badain Jaran Desert are predominantly derived from the Qilian Mountains, northeastern Tibetan Plateau initially via fluvial processes; (2) The Altay Mountains and Mongolian Gobi are the ultimate source areas for the red sand dune field; (3) The Altai Mountains and Mongolian Gobi in the northwest, that could produce massive amounts of materials via intensive deflation and alluvial process, are additional sand sources of the Badain Jaran Desert although their contribution is of secondary significance. As the Badain Jaran Desert acts as sediment sinks of sediments from the Qilian Mountains of northeastern Tibetan Plateau via fluvial processes, it is likely that zircon grains of loess on the Chinese Loess Plateau with age distributions similar to those of the northern Tibetan Plateau could be derived from the Badain Jaran Desert, as the wind data suggest.
•New geomorphological and geochemical studies about the deserts of northwestern China.•Dune sands of the Badain Jaran blown directly from fluvial and lacustrine sediments.•Sediments in the Badain Jaran initially eroded from the northeastern Tibetan Plateau.•Red sand dune field sediments northeast of the Badain Jaran Desert sourced from Altay Mountains and Gobi.•Loess Plateau's loess likely derived from wind-blown dust from the Badain Jaran.
Identifying the provenance of aeolian sediments in deserts is of great importance for understanding the Earth surface processes. In this context, we conducted detailed fieldwork in the Ordos Deserts ...(Maowusu and Kubuqi) in the middle portion of the desert belt in northern China, and measured the major, trace and rare earth elements (REE) of aeolian sands and their potential source rocks and sediments. Our results show that aeolian sands in the eastern (northeastern) and western (southwestern) Maowusu (Mu Us) Sandy Land exhibit different degrees of mineralogical maturity and Eu/Eu* values. Thus, we interpret that these aeolian sands have different provenances, though in the same sandy land. Our data suggest that the local lacustrine sediments and sandstones are the main sources of aeolian sands in the eastern province of the Maowusu Sandy Land, while aeolian sands in the western Maowusu Sandy Land and the Kubuqi Desert have the same external sources. The comparison of geochemical compositions of sediments in the Ordos Deserts with their potential sources in adjacent regions indicates that there is no genetic linkage between the Helan Mountains, the Yinshan Mountains and the Ordos Deserts although they are not far apart. The Qilian Orogenic Belt in the northeastern margin of the Tibetan Plateau is, however, the most likely original provenance for the western Maowusu (Mu Us) Sandy Land and the Kubuqi (Hobq) Desert, but with fluvial sediments in the Ningxia-Inner Mongolian section of the Yellow River as the immediate source. In one side, our results demonstrate that dune fields that are close to each other can have significantly different source sediments. On the other hand, our work suggests that some dune fields and landforms that are far apart from one another, e.g., the Badain Jaran Desert in western Inner Mongolia, the Ordos Deserts and the fluvial sediments in Ningxia-Inner Mongolian section of the Yellow River, can share the same ultimate sources.
•Dunefields close to each other may have different sources of sand.•Yellow River sediments are direct sources of sand in the Kubuqi and western Maowusu.•Tracing provenance via geochemistry needs to be verified by geomorphology.
As a key technology of network security situational awareness, this paper focuses on network security situational prediction technology and proposes a new network security situational prediction ...model based on Hidden Markov Model. The paper proposes a network security posture prediction method based on the improved Hidden Markov Model for the problem that the Baum-Welch parameter training method of the traditional Hidden Markov Model for posture prediction is sensitive to initial values and easily falls into local optimum. The method obtains the initial parameters by introducing the simulated annealing algorithm and using its excellent probabilistic burst-jump property to find the optimal in the global range. The Baum-Welch algorithm is used to optimize the initial parameters further to obtain the optimal model parameters, and then a more accurate posture prediction model is established. The probability of occurrence of the alarm information sequence corresponding to the network security posture value of 3 at
= 4 is obtained by simulating the network environment for testing, which is 0.000268, 0.000152, 0.000147, 0.000284, and 0.000187. Comparing the generated network security posture values with the real situation, it is found that the predicted results in this paper are highly similar to the real values. It is verified that the improved Hidden Markov method can effectively improve the accuracy of the network security posture prediction model and reflect the network security situation more objectively and realistically.
In environmentally sensitive areas, particularly the arid or semi-arid regions, different factors such as relief and human activity, can greatly influence the landscape on a local scale. Using ...satellite imageries and field investigations, we have studied the distribution of sand dunes in the Maowusu (Mu Us) Sandy Land in the southern Ordos Plateau, northern China. Key research questions are which factors are critically responsible for the spatial pattern evident in the landscape and what is the relative importance of such factors? We used a new approach, i.e., the Geographical Detector to improve our spatial analysis. Using the combined methods of the Geographical Detector, digital image processing, field investigation and spatial and temporal analysis of the Normalized Difference Vegetation Index (NDVI), we aimed to clarify the causal relations governing the different landform patterns within this Sandy Land and beyond. The primary factors include local relief, drainage, climatically controlled potential plant productivity, wind action and rock type as explanatory parameters x and the landscape properties as the output y. Our results show the quantified links between the spatial distribution of various landscapes and their controlling factors. This study revealed that the climatic potential productivity, local relief and drainage are the key factors in shaping the landscape spatial pattern. Owing to different regional climates and land use histories, the responses to changes of external forcing between the western and eastern parts of the Maowusu Sandy Land are out-of-step. We conclude that the desertification of the eastern part of Maowusu Sandy Land has been mainly caused by human activities while the western part is governed by natural factors.
•Application of the Geographical detector model over a sandy land in north China•Assessment of the relative importance of driving forces on landscape spatial patterns•Analysis of the causes of landscape distribution on different scales•Discussion about the role of human activities in shaping the Maowusu landscape
5-Hydroxymethylcytosine (hmC) is an oxidation product of 5-methylcytosine which is present in the deoxyribonucleic acid (DNA) of most mammalian cells. Reduction of hmC levels in DNA is a hallmark of ...cancers. Elucidating the dynamics of this oxidation reaction and the lifetime of hmC in DNA is fundamental to understanding hmC function. Using stable isotope labelling of cytosine derivatives in the DNA of mammalian cells and ultrasensitive tandem liquid-chromatography mass spectrometry, we show that the majority of hmC is a stable modification, as opposed to a transient intermediate. In contrast with DNA methylation, which occurs immediately during replication, hmC forms slowly during the first 30 hours following DNA synthesis. Isotopic labelling of DNA in mouse tissues confirmed the stability of hmC in vivo and demonstrated a relationship between global levels of hmC and cell proliferation. These insights have important implications for understanding the states of chemically modified DNA bases in health and disease.
We report remote sensing evidence and reconnaissance field observations for an actively evolving transpressional duplex 150 km north of Tibet, in the southern Beishan region of western China. We ...analyze Landsat-8, Google Earth and SRTM-30 data to reveal active fault traces, kinematics, offset contacts and landforms, and the overall duplex geometry in an area of limited recorded seismicity compared to surrounding regions. Eight NE-striking faults transfer sinistral displacement between E-W bounding faults and accommodate N-S shortening by sinistral-reverse displacements that have tilted the internal duplex blocks. The potential moment magnitude of a surface-rupturing event on one fault, that displays a twenty km-long, 1–3 m-high surface scarp, is estimated to be 6.6. Our study adds to the growing body of evidence that suggests the Beishan is a region of subtly expressed, but widespread, continental interior, strike-slip reactivation at low strain rates - challenging the long-held view that the Beishan has anomalous crustal stability within the huge Indo-Eurasia deformation field.
•Discovery of an actively evolving transpressional duplex in the Beishan, west China.•Duplex is within sinistral fault array which has reactivated Beishan crust N of Tibet.•Quaternary fault scarps suggest potential earthquake hazard.•Crustal stability of Beishan region needs further assessment.•Crustal reactivation of Beishan is part of modern Indo-Eurasia deformation field.
Li Tongxuan’s View of the Dharmadhātu Yang, Xiaoping
Journal of Indian and Buddhist Studies (Indogaku Bukkyogaku Kenkyu),
2021/12/20, Letnik:
70, Številka:
1
Journal Article
Odprti dostop
Li Tongxuan李通玄 （635-730 or 646-740）, a contemporary of Fazang法蔵, devoted himself to reinterpreting the Gaṇḍavyūha-sūtra with the logic of indigenous Chinese thought such as the Zhouyi周易, was excluded ...from the orthodox genealogy of the Huayan School which was formed in the Song dynasty, and was rejected by the orthodox lineage of Dushun杜順, Zhiyan智厳, Fazang, Chengguan澄観, and Zongmi宗密. However, Li Tongxuan’s explanation of the dharmadhātu had an important influence on the construction of the dharmadhātu theory of Huayan Buddhism which unifies the Four realms of reality （si fajie 四法界） with the One true realm of reality （yizhen fajie一真法界）.This paper systematically analyzes Li Tongxuan’s interpretation of the concept of dharmadhātu, focusing on the forty volumes of the Xin huayanjing lun 新華厳経論, and draws two conclusions. First, although Li Tongxuan’s view on the concept of dharmadhātu is based on the acceptance and inheritance of the theory of principle and phenomena of orthodox Huayan, his introduction of the concept of true wisdom provides a new direction for interpretation of the Gaṇḍavyūha-sūtra, offers a new perspective for the explanation of the dharmadhātu, and greatly enriches the content of the doctrine of dharmadhātu. Second, Li explains the concept of dharmadhātu in the context of the relationship between essence-function and principle-awareness, and asserts that the dharmadhātu is the “One true” （yizhen 一真） itself. He constructed the theoretical basis for the sansheng yuanrong 三聖円融 （perfect interfusion of the three holy ones, Vairocana, Mañjuśrī, and Samantabhadra） from the essence-function of the dharmadhātu.
This paper reviews our current understanding of Quaternary climate and landscape changes in the desert areas of northern China, a key portion of the middle-latitude drylands on Earth. Combining ...earlier studies with our recent research and experience, we offer a comprehensive picture of the state of Chinese deserts during the Quaternary and, in the interest of enhancing future research, identify knowledge gaps and areas of uncertainty.
Lacustrine deposits found over an area ranging from China’s western Taklamakan Desert to the eastern Hunshandake Sandy Lands suggest that extensive lakes occurred in China’s deserts during the Pleistocene. Analysis of digital elevation models from SRTM (Shuttle Radar Topography Mission) data supports this interpretation and shows the significant extent of these former lakes. New estimates of mean annual evaporation of ca. 1000 mm from lake surfaces and ca. 100 mm from land surfaces, confirms that local and regional rainfall is critical for maintenance of desert lakes in this temperate zone, especially during intervals when the mean annual rainfall is more than 100 mm.
Rapid shifts between sand seas and lakes in geologically and environmentally diverse settings suggest that the drylands of China are very sensitive ephemeral systems, and not long-lasting as previously thought. Available chronologies suggest that there were large lakes in the western Taklamakan Desert and the Chadamu Basin during MIS (Marine Isotope Stage) 3, at ∼30 ka, probably related to a period of strong influence of northern hemispheric westerly winds. Channels and elevation models revealed by SRTM data and remains of lacustrine sediments also indicate that there was a large lake in the Hunshandake Sandy Lands in the eastern portion of the desert belt during the Quaternary.
There is significant evidence that during the middle Holocene strong summer monsoons led to a relatively large increase in moisture availability in the entire desert belt of northern China. Lacustrine records from the Badain Jaran Desert in western Inner Mongolia suggest that it was generally dry before 10 cal ka, becoming wetter from 10 to 4 cal ka, and dry again afterwards. Study of palaeosols widely occurring in dune stratigraphy in the eastern portion of the desert belt, suggests that there was a period of wet and warm climate in this region during the mid-Holocene Optimum, at a minimum between 6 ka and 4 ka, but possibly lasting longer.
Recent observations dealing with the generation and transport of dust from Central Asia indicate that the causal relationship between sand seas and loess sequences is not as close as previously assumed. These results suggest that there is an urgent need to examine whether the frequency and amplitude of climatic variation in Chinese deserts are somehow similar to that having occurred in the Sahara Desert of North Africa.
Deserts in northern China were also important focal regions for Neolithic cultures during intervals when environmental conditions supported a denser vegetative cover. There is evidence that some areas of woody vegetation to the west of Badain Jaran Desert were deforested by humans by ca. 4000 yr B P, although it is still debatable whether humans have had a significant impact in other areas at that time. Opinions on the severity of desertification vary and are sometimes contradictory due to the lack of long-term, field-based, investigations.
The structural connectivity and kinematic relationship between the Altyn Tagh sinistral strike‐slip fault (ATF) and Qilian Shan fold‐and‐thrust belt along the north Tibetan margin east of 96°E is an ...important question for tectonicists interested in the evolving active deformation field of Central Asia and associated earthquake hazards of China's Hexi Corridor region. New results from a detailed 130‐km‐long N‐S magnetotelluric (MT) survey from the Qilian Shan to Beishan elucidates the locations and down‐dip orientations of major faults. Importantly, the results indicate that the Heishan‐Jinta’Nanshan fault system roots steeply into the lower crust, is unconnected to the Qilian Shan thrust wedge, and has reactivated the margin of the North China Craton and an older, regional ductile shear belt. The structurally linked ATF‐Heishan‐Jinta’Nanshan system defines a fundamental kinematic boundary in central Asia between the NE directed Qilian Shan thrust belt to the south and the eastwardly extruding Beishan‐Alxa Block to the north.
Plain Language Summary
In this study, we present results of a comprehensive electrical resistivity survey conducted in the western Hexi Corridor region of China. The survey reveals significant sub‐surface faults and crustal boundaries, providing insights into the crustal structure between northernmost Tibet (Qilian Shan) and the Beishan. We document how the strike‐slip crustal boundary known as the Altyn Tagh Fault (ATF)‐Heishan‐Jinta’Nanshan system is steep and spatially unconnected to the Qilian Shan east of 98°E. It separates crustal blocks with contrasting motion histories; the southern block experiences compressional deformation, whereas the northern block accommodates extensional and transtensional deformation. Furthermore, the northeast trending ATF bends and converges into the more east‐west‐oriented Heishan‐Jinta’Nanshan system. We propose that this is a result of the Heishan‐Jinta’Nanshan system reactivating an older ductile shear belt and a mechanically weak boundary along the northwestern margin of the Precambrian North China Craton. Our study confirms the significance of inherited crustal structures in localizing continental interior reactivation and associated earthquake hazards.
Key Points
A new detailed 3D resistivity model from Northern Tibet to the Southern Beishan clarifies the crustal structure in the NW Hexi Corridor
The Heishan fault system penetrates steeply to the lower crust and is unconnected to the Qilian Shan thrust wedge
Crustal thickening and mountain uplift in Qilian Shan is kinematically separated from eastward Beishan‐Alxa Block extrusion further north
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