Search

China is facing many challenges in the area of high‐precision exploration for deep mineral resources, and also in environmental and engineering fields. It has become an urgent task to realize geophysical explorations with high precision and high efficiency in complex environments. It has been found that the traditional transient electromagnetic method (TEM) had a series of problems related to theory, method, and instrument, as well as data interpretation. Based on the reviews of present TEM achievements, three new improved measurements are introduced. The central‐loop system was improved by a large fixed‐loop system; the long‐offset system was changed to the short‐offset one; the resistivity profile was transformed into a virtual wave‐field profile. Finally, this paper points out that the future research direction of the TEM method is in terms of equipment, data processing, and big data information. [ABSTRACT FROM AUTHOR]

This paper addresses the surface and Holocene aeolian deposits in the southeastern Mu Us Desert, N. China, systematically analysing the evolution of the geochemical characteristics of aeolian sand-palaeosol sequences and their environmental significance. Our results indicate that the geochemical components of the Holocene aeolian deposits and surface deposits had the similar material sources, sediment transport and deposition processes in the study region, which were dominated by SiO2, Al2O3, and Na2O. In the weathering process of the Jinjie (JJ) profile, the Na, K, and Si presented the slight leaching and migration in general, while the other elements were relatively accumulated. The Holocene aeolian deposits and surface deposits incurred weaker geochemical weathering under cold and dry conditions and were only weakly leached, which implies a relatively arid environment in the Holocene epoch and the modern era. The weathering degree was controlled by the regional temperature and precipitation, and was probably more sensitive to the precipitation changes. In the sedimentary profile, the geochemical parameters and migration of elements demonstrated that there have been several alternating warm-wet and cold-dry intervals in the Mu Us Desert in the Holocene epoch; there were relatively warm and wet conditions prior to 4.6 ka, and it has been cold and dry since then. Six millennial-scale dry events were recorded during the Holocene, which were not only accordant with the history of palaeoclimatic changes in the different latitudes and archives of the Northern Hemisphere, but also correspond to the millennial-scale variation of cosmic radiation and solar activity during that period. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Naotic dissepiments are special structures of rugose corals, characterized by a column of distally arched plates at peripheral parts of thick septa or within the cystozone. In this study, naotic‐dissepimented colonial rugose corals Gyanyimaphyllum crassiseptatum and Ipciphyllum naoticum and their associated microfacies were documented from the Late Permian Gyanyima section in Tibet, southwestern China. The morphology of the Gyanyima naotic‐dissepimented corals is cerioid massive forms or fasciculate forms with connected individuals, with broken skeletons. Between coral colonies and/or skeletons, the interspaces are occupied by highly fragmented bioclasts and sparry calcite. These biotic and sedimentary characteristics suggest that the Gyanyima naotic‐dissepimented corals could have developed in high water‐energy environments above fair‐weather wave‐base. This implies that the development of naotic dissepiments was probably related to an enhanced hydrodynamic force. According to a review on the Permian naotic‐dissepimented rugose corals in China, they are mainly composed of massive colonial forms with a few fasciculate colonial and solitary forms. Current available data indicate that they could occur in bioclastic grainstones and oncoid limestones with eroded skeletons, which also support a conclusion that naotic dissepiments formed in turbulent environments. Based on the ontogenic studies on naotic‐dissepimented rugose corals, naotic dissepiments occur sporadically in the neanic stage and are well developed but not permanently and uniformly in adult stage. Furthermore, different species in the same genus have different degrees of development of naotic dissepiments, which might imply that naotic dissepiments are not suitable to be an important taxonomic character in higher than species level. [ABSTRACT FROM AUTHOR]

Based on a detailed morphologic and tomologic investigation of a fossil endocarp, a new species of Diploclisia (Menispermaceae) is described from the Late Miocene of Jiahu, Zhejiang Province, eastern China. This represents the first record of the genus in the Neogene. The fossil endocarp closely resembles that of the Chinese endemic, Diploclisia affinis. The past and present distribution of Diploclisia shows that the genus probably originated in north‐east China in the Palaeocene (66–56 Ma) at the latest, which has undergone various phases of expansion and contraction. The more advanced Diploclisia glaucescens probably expanded into south and south‐east Asia in the Pleistocene, when global sea‐levels were lower. [ABSTRACT FROM AUTHOR]

China ranks as the world's largest gold producer and as the second largest gold consumer since the last few years and hosts one of the fastest growing gold markets in the world. The gold mineralization in China has been divided into several super‐large (>100 t Au), large (50 to 100 t Au), and numerous medium to small (20 to 50 and <20 t Au) deposits. Geologically, these are classified into different types such as gold‐only deposits, base metal‐rich type including skarn, porphyry, and vein deposits, and placer accumulations. Integrated genetic models based on geological investigations propose that the gold deposits formed through multiple stages of subduction–accretion–collision associated with different orogenic cycles, with most of the giant gold deposits related to extensive lithospheric destruction and recycling. China has a long history of gold mining starting from the days of the Xia, Shang, and Zhou Dynasties at ca. 2,100–256 bc, which further flourished in the "Silk Road" era, although in the modern times, the country was "officially" reported producing hardly 2 tons of gold for nearly 40 years until a major revival occurred between 1982 and 1993, with a dramatic increase to 160 tons per year. According to recent statistics, China ranks as the world's largest producer of gold with over 460 tons, contributing significantly to the growth of world gold production. In the Asian region, 91% of gold production comes from China and five other countries, with China contributing the major share. With regard to gold consumption, the amount of gold bought in China rose steadily over the past several years from around 204.5 tons in 2002 to 832.18 tons in 2012. Among the various forms of gold jewellery in China, fine gold is the most popular, with 24 K gold accounting for more than 80% of the gold jewellery sold in the country. Studies identify a positive relationship between the rate of technical expertise and economic growth in state‐owned and mixed sectors of gold industry in China. Attracting more private investment into capital‐intensive and state‐owned sectors is considered to help boost the mining industry. China's gold output sustained the world gold market even during the global financial crisis in other bulk commodities. Quantitative analysis in recent studies reveals a power‐law cross‐correlation between price and volume in gold spot and futures markets and predicts long‐term stability despite short‐term fluctuations. Extensive mining activities invariably raise environmental issues and anthropogenic health hazards. With the country announcing the discovery of new gold deposits, such as the biggest ever gold mine in Shandong with gold resources valued more than $22 billion, and moving forward to new horizons in gold mining and production, insightful policies from decision makers are important in the areas of promoting research and development in academic and technical fields, involving technical expertise and advanced technology in gold mining and processing, and implementing strict regulations for environmental protection. [ABSTRACT FROM AUTHOR]

The Jiaodong gold province in northeastern China is the country's premier gold resource and globally one of the most important gold provinces. The late Early Cretaceous gold metallogeny in this belt remains an enigma as it is hosted in the Archean Jiaobei Terrane of the North China Block and, to a lesser extent, within the Palaeoproterozoic Sulu Terrane of the South China Block. The driving force for widespread Late Jurassic and Early Cretaceous granitic magmatism, the switchover from a compressional to extensional tectonic regime, and gold mineralization are considered to be a combination of plate subduction with lithospheric delamination and consequent asthenospheric upwelling. Although many aspects related to the genesis of the gold deposits in Jiaodong have been resolved, the spatial distribution of the world‐class gold deposits in this belt, which is of vital importance to brownfields and greenfields exploration, has been poorly understood in terms of the structural evolution of the province. In the northwestern segment of the Jiaobei Terrane, the world‐class gold deposits of Sanshandao in the west, through Jiaojia, to Linglong in the east define a broadly E–W corridor. This corridor links a series of east‐verging jogs on ore‐controlling NNE‐trending oblique‐slip faults that are subparallel to an lithospheric‐scale Tan‐Lu Fault to the west. There is cryptic evidence that these jogs line up in the E–W trend due to reactivation of Palaeoproterozoic to Mesozoic faults and folds that were part of the structural architecture of the terranes prior to the gold event. These jogs induced deviations in the local principal stresses relative to regional equivalent stresses, with resultant heterogeneous strain, increased rock permeability, and focussed ore‐fluid ingress. Both disseminated/microbreccia‐stockwork and vein‐type gold deposits formed in this corridor, with the former being predominant and the latter having a higher gold grade. In contrast, predominant vein‐type gold deposits in the eastern segment of the Jiaobei and Sulu terranes tend to form N–S corridors. These vein‐type ores may relate to rotational strain induced by movement on pairs of more linear NNE‐trending faults with the same kinematic movement sense. [ABSTRACT FROM AUTHOR]

By integrating diagenesis and sedimentary facies, the distribution of diagenetic alterations and their impacts on reservoir quality were investigated within a lacustrine fan delta depositional environment in the Lower Cretaceous of the Western sub-sag in the Chagan Sag, Yin-E Basin, northern China. Core observation and analyses of petrography and geochemistry of the sandstones revealed that the eogenetic alterations display spatial and temporal distribution patterns associated with sedimentary facies, including distributary channels of a fan delta front (DC), distributary bays (DB) and sheet sands (SS) and mouth bar (MB) (SS and MB are collectively referred to as S). Percolation of meteoric waters occurring in high permeability DC sandstones resulted in leaching of feldspar, the formation of kaolinite, as well as mechanical infiltrated clays around detrital grains. Conversely, the DB deposits containing abundant ductile lithic fragments were subjected to mechanical compaction and thus the development of a pseudomatrix. During a long burial residence time (the Early Cretaceous period) in a lacustrine environment, abundant early carbonate cements were precipitated, especially in the distal S sandstones. The sandstones lacking eogenetic cements were subjected to stronger mechanical compaction. Additionally, eogenetic alterations have an important impact on the distribution of the mesogenetic alterations. Sandstones containing few eogenetic cements or thin or discontinuous infiltrated clay rims around the detrital grains were subjected to quartz cementation. However, during the hydrocarbon generation stage, the most efficient percolation of meteoric waters and organic acid dissolved feldspar minerals and carbonate cements, resulted in DC sandstones having more intragranular and intergranular porosity. Owing to high matrix contents and early calcite cement contents, the DB and S sandstones had lower permeability and were rarely dissolved. During the late mesogenetic stage, late carbonate cements occurred in all sedimentary facies and iron and magnesium ions were released from the transformation from kaolinite to illite or to chlorite. The results from this study show possible diagenetic evolutionary pathways in the reservoir sandstones within the fan delta depositional environment, which in turn provides some insights into the controls on reservoir potential. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Wind is the primary control on the formation of aeolian geomorphology. In this study, we combined wind regime data from automated weather stations in the western and southwestern Tengger Desert of the Inner Mongolia region in China with remote-sensing data to analyse the relationship between the wind energy environment and aeolian geomorphology. Tengger Desert is one of the main dust storm sources in northwestern China. Therefore, efforts aimed at controlling desertification and dust storm require a deeper understanding of the processes that govern the formation and subsequent evolution of dunes in this area. Wind speed was largest in the northwest (3.3 m/s in the Xiqu station) and smallest in the southeast (1.2 m/s in the Haizitan station). Potential sand transport was also largest in the northwest (195 in the Jiahe station) and smallest in the southeast (33 in the Tumen station). The sand-driving wind (5.92 m/s) directions were from the NW and SE quadrant across the study area, at >76% of all sand-driving wind, reaching 99% in the Tumen station. The sand-driving wind in the NW quadrant reached >48%, and in the SE quadrant, >12% of all sand-driving wind in all stations. In the study area, sand dunes included crescent, dune networks, transverse, and coppice dunes. Dune crest directions had similar trends from upwind to downwind, at 133° in the middle region, and 124° in the southwestern region. Mean dune spacing changed with dune patterns; the maximum spacing for crescent dunes was 147 m, for dune networks 118 m, and for transverse dunes it was 77 m. The mean crest length was 124m (maximum) for crescent dunes in the northwest, 121m for transverse dunes, and 84m for dune networks. However, because of gullies in the southern region, the mean crest length was only 58m (least) for the crescent dunes in that area. The defect density ranged from 0.007 to 0.014. The spatial differences in dune patterns reflected the evolution of the dune field, where older dunes had been formed upwind and younger downwind. [ABSTRACT FROM AUTHOR]