The Mechanism of Groundwater Salinization and Its Control in the Yaoba Oasis, Inner Mongolia

The arid area is one of the most concerned areas among the water resources researchers and economists. Northwest China will be an important developing region of China in the 21st century. Yaoba is a well-irrigation oasis within this arid area, which is located in the Alxa area west of the Helan Mountains and next to the Tengger desert in the east. It has contributed greatly to the local stock raising and agriculture since its development in 1970. However, the groundwater which the oasis depends on to survive has been getting salinized gradually and more serious in recent years.A comprehensive study was carried out using the methods of groundwater environment isotope analysis, lithofaci-es and palaeogeography, calculations of water-rock interaction and the existing form of chemical components in groundwater etc. It has been found that the salinization of groundwater is mainly caused by reinfiltration water solving the salt in soil which is deposited simultaneously with the sediments and accumulated in th     

Extent and chronology of Quaternary glaciation

In a recent INQUA project the extent of Pleistocene glaciations has been digitally mapped and the chronology of events reviewed. The onset of the present Ice Age in both hemispheres dates back to the Palaeogene. In Greenland, Iceland, North America and southernmost South America sizeable ice sheets formed well before 2.6 ka BP. In Alaska and on Tierra del Fuego the ice advanced further than in any later glaciations. Evidence for Early Pleistocene glaciation （2.6-0. 78 Ma） has been reported from many parts of the world, but in most cases dating remains problematic, and the size of the glaciers and ice sheets is unknown.     

40Ar/39Ar Geochronology of Weathering Process in the Tu-Ha Basin, Northwest China

<正>The Asian interior contains the most regionally extensive areas of mid-latitude deserts and semi-deserts in the word,and its timing and forcing mechanisms of aridification has attracted much attention.The Tu-Ha Basin is one of the major hyperarid areas in the northwestern China;however,the initiation and history of aridification of this basin have been poorly understood.     

On Continent-Continent Point-Collision and Ultrahigh-Pressure Metamorphism

Up to now it is known that almost all ultrahigh-pressure (UHP) metamorphism of non-impact origin occurred in continent-continent collisional orogenic belt, as has been evidenced by many outcrops in the eastern hemisphere. UHP metamorphic rocks are represented by coesite- and diamond-bearing eclogites and eclogite facies metamorphic rocks formed at 650-800℃ and 2.6-3.5 GPa, and most of the protoliths of UHP rocks are volcanic-sedimentary sequences of continental crust. From these it may be deduced that deep subduction of continental crust may have occurred. However, UHP rocks are exposed on the surface or occur near the surface now, which implies that they have been exhumed from great depths. The mechanism of deep subduction of continental crust and subsequent exhumation has been a hot topic of the research on continental dynamics, but there are divergent views. The focus of the dispute is how deep continental crust is subducted so that UHP rocks can be formed and what mechanism causes it to be subducte     

http://www.sciencedirect.com/science/article/pii/S1674987112000254

The applications of intelligent techniques have increased exponentially in recent days to study most of the non-linear parameters.In particular,the behavior of earth resembles the non-linearity applications.An efficient tool is needed for the interpretation of geophysical parameters to study the subsurface of the earth.Artificial Neural Networks(ANN) perform certain tasks if the structure of the network is modified accordingly for the purpose it has been used.The three most robust networks were taken and comparatively analyzed for their performance to choose the appropriate network.The single-layer feed-forward neural network with the back propagation algorithm is chosen as one of the well-suited networks after comparing the results.Initially,certain synthetic data sets of all three-layer curves have been taken for training the network,and the network is validated by the Held datasets collected from Tuticorin Coastal Region(78°7′30″E and 8°48′45″N),Tamil Nadu.India.The interpretation has been done successfully using the corresponding learning algorithm in the present study.With proper training of back propagation networks,it tends to give the resistivity and thickness of the subsurface layer model of the field resistivity data concerning the synthetic data trained earlier in the appropriate network.The network is trained with more Vertical Electrical Sounding(VES) data,and this trained network is demonstrated by the field data.Groundwater table depth also has been modeled.     

MICROSCOPICAL STUDY OF THE SHUIKOUSHAN LEAD-ZINC DEPOSIT IN CHANGNING DISTRICT, S. HUNAN

INTRODUCTION Shuikoushan is the most important and well known mining district for production of silver, lead, zinc and pyrite in China. It is situated at about 65 li N. E. of Changning, 90 li S. of Hengyang and 620 li from Changsha, the Capital of Hunan. It has been visited by many geologists and mining     

Seismic Hazard Assessment of District Mansehra,Khyber Pakhtoonkhawa,Pakistan

The site of Mansehra is located seismically in an active regime, known as the Crystalline Nappe Zone and Hazara-Kashmir Syntaxis in NW Himalayas, Pakistan. Seismic Hazard Assessment （SHA） for the site has been carried out by considering the earthquake source zones, selection of appropriate attenuation equations, near fault effects and maximum potential magnitude estimation. The Mansehra Thrust, Oghi Fault, Banna Thrust, Balakot Shear Zone, Main Boundary Thrust, Panjal Thrust, Jhelum Fault and Muzaffarabad Fault and, further to the south, the Sanghargali, Nathiagali, and Thandiani Thrusts are the most critical tectonic features within the 50 km radius of Mansehra. Using the available instrumental seismological data from 1904 to 2007, SHA has been carried out. Other reactivated critical tectonic features in the area have been investigated. Among them the Balakot-Bagh fault, with the fault length of 120 km from Balakot to Poonch, has been considered as the most critical tectonic feature on the basis of geological/structural/seismological data. The potential earthquake of maximum magnitude 7.8 has been assigned to the Balakot-Bagh fault using four regression relations. The peak ground acceleration value of 0.25 g （10% probability of exceedance for 50 years） and 0.5 g has been calculated with the help of the attenuation equation using probabilistic and deterministic approaches.     

Devonian Bivalve Faunas, Life-habits, and Biodiversity Changes in Guangxi, South China

正Objective The Devonian bivalves are well developed,highly diversified and widely distributed in Guangxi.However,they have not been well studied previously,although several papers have dealt with it.Meanwhile,the biodiversity change of bivalves which is one of the most important benthos during Devonian in South China has not been studied yet.The aim of present project is focused on the study of systematic palaeontology,the life-habits,     

Temporo-Spatial Distribution and Evolution of Ore Deposits in the West Sector of the Northern Qilian Mountains

The west sector of the northern Qilian Mountains is well-known for the Jingtieshan-type iron deposits. A new breakthrough has been made in prospecting for gold and copper in recent years. In this paper, the distribution characteristics of ore deposits in the study area are discussed from the viewpoint of tectonic evolution. It is suggested that there are 9 stages of mineralization from the Palaeoproterozoic to Indosinian. Four minerogenetic series and two minerogenetic subseries of ore deposits are recognized. Iron mineralization occurred in several stages, while most of the metals were accumulated in large amounts in the Caledonian. The enrichment and mineralization of gold is related to large-scale shear-strike-slip faults and the ascent and unloading of deep-seated fluids.     

Eopriapulites Sphinx—The Oldest Priapulid-Like Scalidophoran Animal

正Objective Priapulid belong to scalidophoran and is located in the Cycloneuralia branch of the Ecdysozoa.It has survived for more than 50 million years,is a real"living fossil".Priapulid was extremely prosperous in the Cambrian period.It is a small phylum in the modern ocean;only 18current types have been described.In the Cambrian life,priapulid is one of the most important living organisms in     

Morphology and Propagation of Hydraulic Fractures for CBM Wells

<正>Objective As the most widely used and effective technique in reservoir reconstruction of unconventional natural gas,hydraulic fracturing has been achieved good effect in CBM development.It is important to note that coal seam is both source rock and reservoir,and that hydraulic     

First Discovery of Dicerorhinus sumatrensis from Yanjinggou Provides Insights into the Pleistocene Rhinocerotidae of South China

The Rhinocerotidae is one of the most common and important families in the Pleistocene mammalian fauna of South China. Since the last century, most of the Pleistocene rhinocerotid fossils were prematurely assigned to Rhinoceros sinensis, which has resulted in confusion of taxonomy for decades, especially in South China. The Yanjinggou area in Chongqing Municipality of China, where the neotype of R. sinensis came from, has yielded abundant rhinocerotid fossils and is a key area to solve this problem. A recently discovered juvenile skull from a karstic fissure in this area can be referred to Dicerorhinus sumatrensis (Fischer, 1814), which is the first confirmed non-Rhinoceros rhinocerotid from the area. This new finding indicates that non-Rhinoceros fossils might have been mixed in AMNH collection from Yanjinggou and thus the diagnosis of Rhinoceros sinensis needs reformation. On the other hand, Stephanorhinus ?kirchbergensis is also detected in Granger’s collection based on our reobservation. The coexistence of Rhinoceros, Dicerorhinus and Stephanorhinus shows the higher diversity of Pleistocene rhinocerotids in South China.     

A geochemical study of redox behavior of As in a contaminated aquifer from Sonargaon, Central Bangladesh

The Bengal Basin has been exposed to the most serious As problem in the world. Although it has been agreed well among many researchers that the contamination has been induced by natural geochemical process, detailed mechanisms are still under debate. Arsenic is easily soluble into groundwater as pentavalent arsenate and trivalent arsenite. Their adsorption behavior for various solid phases, particularly for Fe oxyhydroxide （FeOOH）, is different. Thus speciation of As in solid phase is essential to examine the process of contamination. However, few studies have been done about As speciation in sediment due to its analytical difficulty. In this study, we applied XANES （X-ray adsorption near the edge structure） spectroscopy to determine oxidation states of As and Fe, and investigate As behavior along change in redox condition. We studied the Sonargaon area located 25 km southeast of Dhaka. Sediment core samples were collected from one site in the area up to the depth of 100 m using penetration-drilling method. The samples were packed into oxygen impermeable film with deoxidizer on site,     

我国某地区岩浆岩化学成分与区域地球化学特征

Based on a review of the available petrological and petrochemical data on magmarie rocks in a certain district in China, the average chemical composition of magmarie rocks has been calculated, and the frequenee distribution of elements in rocks,mineralization of rock bodies and regional geochemical characteristics have been discussed. In response to the temporal and. spatiai variations during the evolutionary process of magmatie activity, a systematic variation is obvious from this study in the chemical compositions of magmatie rocks, the frequence distribution patterns of elements, the concentration levels of various elements, the calc-alkaline index of the rocks as well as in the average atomic weight and average atomie valence. Particularly,different geochemical indicators have been observed for mineralized and barren rock bodies respectively. Crystallization-differentiation and postmagmatic metasomatism constitute the most important mechanisms controlling mineralization.     

The Discovery of a Crinoid Community in the LateTriassic Zhuganpo Formation of Guizhou Provinceand Its Geological Significance

Recently a rich and well-preserved crinoid community including Traumatocrinus and Encrinus has been found in the Late Triassic Zhuganpo Formation in Guanling and Xingyi, Guizhou province, China. Among the fossils Traumatocrinus is the richest, and most of it occurs as clusters, with each cluster containing 3-42 crinoid branches. Study of the stem and calyx of Traumatocrinus shows that the number of stem-joints (columnals) is equal to the total stem length × K (5.85 per cmx stem-diameter). There are about 376 first- and second-order columnals on the whole stem. This number seems to coincide with the number of days in a year at that time. According to the present study of the palaeoecological environment of the crinoid community, it is considered that the reproduction and preservation of the crinoid community were controlled by the Late Triassic regression and the restricted bay of an interior sea behind the S-shaped shoal zone.     

The Most Complete Sequence of Telychian Graptolite Zones in the World

This paper divides the Telychian into 7 graptolite zones, 12 subzones and 4 chitinoans in the Ziyangregion, China. The zones and subzones of England are almost totally suitable for the case of Ziyang in China, though they are 10000 km apart. All the above-mentioned biozones are found only in a unitary continuous section in Ziyang. It has been proved that the Ziyang section is the one with the most complete sequence of Telychian graptolite biozones in the world.     

The Equilibrium Coefficient Kp and Petroleum Exploration:Design of the New Generation of Petroleum Exploration Instrument

The main reason why the application of nuclear technology in petroleum exploration has not yet been accepted by most exploration workers is that they are not clear about the homologous distribution features of oil and gas fields and radioactive radiation. The authors hold that the disequilibrium of uranium, radium and radon as a natural radioactive series is the basic feature in the use of this technology in petroleum exploration. The invention Gamma-ray Spectral Measurement of the Equilibium Coefficient Kp and Its Embodiment of the senior author now can readily solve that problem and replace the impedient measure of normalization of uranium and potassium to thorium that had to be proposed before. Application of this impedient measure has some limitations. In areas where the surface is covered by beach or river sands, thorium minerals such as monazite may be concentrated by placering. This could result in local thorium highs that would yield local uranium and potassium lows after normalization to thoriu     

Petroleum System of the Sufyan Depression at the Eastern Margin of a Huge Strike-slip Fault Zone in Central Africa

Abstract: The present paper mainly studies the petroleum system of the Sufyan Depression in the Muglad Basin of central Africa and analyzes its control of hydrocarbon accumulation. On the basis of comprehensive analysis of effective source rock, reservoir bed types and source–reservoir–seal assemblages, petroleum system theory has been used to classify the petroleum system of the Sufyan Depression. Vertically, the Sufyan Depression consists of two subsystems. One is an Abu Gabra subsystem as a self generating, accumulating and sealing assemblage. The other subsystem is composed of an Abu Gabra source rock, Bentiu channel sandstone reservoir and Darfur group shale seal, which is a prolific assemblage in this area. Laterally, the Sufyan Depression is divided into eastern and western parts with separate hydrocarbon generation centers more than 10?000 m deep. The potential of the petroleum system is tremendous. Recently, there has been a great breakthrough in exploration. The Sufyan C-1 well drilled in the central structural belt obtained high-yielding oil flow exceeding 100 tons per day and controlled geologic reserves of tens of millions of tons. The total resource potential of the Sufyan Depression is considerable. The central structural belt is most favorable as an exploration and development prospect.     

巴塔哥尼亚(阿根廷)中侏罗世翼龙的骨骼学特征

The Ca?adon Asfalto Formation is mainly composed of lacustrine deposits and has provided the most diverse vertebrate fauna known for the Middle Jurassic in the Southern Hemisphere. Pterosaur remains have been discovered from several localities in this unit and briefly reported by Rauhut et al. (2001) and Unwin et al. (2004).     

VARISKIAN OR HERCYNIAN MOVEMENT IN SOUTH-EASTERN CHINA

It has been the habit of most geologists to speak of an earth-movement in some special regional term which, as a rule, primarily refers to the trend of the resulting flexures or fractures and eventually to the time when the moverment took place. This dual implication of a tectonic term is largely to be