Geohazards induced by anthropic activities of geoconstruction: a review of recent failure cases     

Khalid Elbaz  Jack S. Shen  Arul Arulrajah  Suksun Horpibulsuk 《Arabian Journal of Geosciences》2016,9(18):708

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Textural characteristics of sediments along the southern Red Sea coastal areas,Saudi Arabia     

Omar A. Alharbi  Allan T. Williams  Michael R. Phillips  Tony Thomas 《Arabian Journal of Geosciences》2016,9(19):735

A lack of understanding exists of the origin and textural characteristics of Saudi Arabian Red Sea coastal sediments. This paper concerns the southern coastline of Jizan on the Saudi Red Sea. It is some 160 km long characterised by either narrow rocky headlands with intermittent pocket beaches or wide low-lying beaches dissected by wadis. Granulometric testing of samples from 135 locations showed that beach sand size was mainly very fine to medium grained (M _z = 3.93 Ø), sorting ranged from 1.65 to 0.41 and skewness values from ?051 to 0.39, being mainly negative; dune sands were medium to fine grained (M _z = 1.13 Ø; average sorting 2.8), while skewness variations within dune samples indicated symmetrical to fine skewed values (б _Ι = 0.55 to 0.89). Most foreshore samples were derived from wadis. Wadi mud levels can be high, e.g. Baysh (84%), and wadi Samrah (90%) with mean grain size ranging from very fine to medium sand (M _z = 3.9 Ø), sorting being well to poor (0.45 to 1.52) due to sediment influxes. Sabkha had a wide range of sand/mud and significantly higher carbonate percentages than other environments. Sediment source differences and littoral reworking contributed to grain size variation. The carbonate content varied between 1.5 and 31.5% due to hinterland contributions, and spatial analysis showed increasing quantities of carbonate minerals towards the south. On the wider geographical front, findings from Jizan are similar to those of the Northern United Arab Emirates (UAE), including sabkhas, being composed of sand, skeletal carbonate, fine fluvial material and wind-blown silt and clay components of wadi origin. Further work on the northeastern Red Sea edge can hopefully confirm these findings.  相似文献   

Time and frequency domains response analyses of April 2015 Greece’s earthquake in the Nile Delta based on GNSS-PPP     

Mosbeh R. Kaloop  Mostafa Rabah 《Arabian Journal of Geosciences》2016,9(4):316

Earthquake response characteristic and sensitivity of 1-Hz Global Navigation Satellite System - precise point positioning (GNSS-PPP) for a seismic response in time and frequency domains are the main objectives of this study. The Delta and Cairo areas, Egypt, experiencing the shock of the Greece earthquake occurring on April 16, 2015 (18:50 hours), is presented in this study. The results of this study reveal that the seismic wave effect is very small and can be neglected inside the Delta region and the strong motion occurred in an upward direction for the whole monitoring area. Furthermore, the time-frequency analysis illustrates the ability of the time and frequency domains to use and analyze the surface motion based on a 1-Hz sampling frequency and to detect the small- and high-strength motions of seismic waves.  相似文献   

Design and simulation of a vertical broadband seismometer     

E. Habbak  H. Nofal  E. Lotfy  S. El-Sabban  Z. Nossair 《Arabian Journal of Geosciences》2016,9(5):408

In this paper, a new vertical broadband seismometer is designed, simulated, and evaluated. The proposed seismometer has a bandwidth from 40 s to 50 Hz and sensitivity to ground velocity of 1500 V’/m/s. The mechanical suspension used in the proposed design is a mass-leaf spring rotational pendulum. The displacement of the seismic mass is sensed by a laser interferometer and then forwarded to an electronic force feedback system which feeds a linear actuator to keep the mass almost fixed in its position. The current needed to fix the mass in its position is an indication of the ground acceleration. The performance of the simulated seismometer is evaluated by applying a data record of two actual earthquakes to the simulated model and comparing its response to the earthquakes with that of a real seismometer (Trillium-40) having the same bandwidth and sensitivity. The proposed seismometer has performed within 0.4 % residual variance for the local event and 0.03 % residual variance for the regional one compared to Trillium-40.  相似文献   

Wetland economic valuation approaches and prospects in China   总被引：1，自引：0，他引：1  

Bo Jiang  Christina P. Wong  Lijuan Cui  Zhiyun Ouyang 《中国地理科学(英文版)》2016,26(2):143-154

Ecosystem services valuation seeks to increase the social relevance of ecosystem characteristics, the underlying biological mechanisms that support services, by making the contribution of ecosystems to human well-being explicit. Economic valuation can help management by clarifying the full range of benefits and costs of proposed management actions. In the past two decades, economic valuation of wetland ecosystem services has become one of the most significant scientific priorities for wetland protection. In this paper, we provide an overview of ecosystem services, and summarize the main interdisciplinary approaches to measure and value wetland ecosystem services. We identified four main methodological gaps preventing progress on wetland valuation of ecosystem services in China, which are: 1) confusion on terminology like intermediate and final ecosystem services, 2) lack of ecological production functions to link ecosystem characteristics to final ecosystem services, 3) static valuation making it difficult to evaluate the trade-offs and synergies among ecosystem services, and 4) lack of clear guidance on relating ecological compensation programs to conservation targets. Overcoming these gaps is important to inform wetland compensation mechanisms and conservation policies. We propose future research on wetland ecosystem services in China should be focused on: 1) defining final ecosystem services based on beneficiary preferences and underlying biophysical mechanisms, 2) establishing wetland monitoring programs at specific sites to collect data on final ecosystem service indicators and ecosystem characteristic metrics to create ecological production functions for economic valuation and rescaling techniques, and 3) incorporating wetland ecosystem service values into decision-making processes to inform wetland management.  相似文献   

Geochemical constraints on the tectonic setting of the Sonakhan Greenstone Belt,Bastar Craton,Central India     

S. D. Deshmukh  K. R. Hari  P. Diwan  M. P. Manu Prasanth 《中国地球化学学报》2018,37(3):489-499

The Neo-Archean Sonakhan Greenstone Belt (SGB) located in the north-eastern fringes of Bastar craton, Central India, is dominated by Basalts, Andesites, Dacites and Rhyolites association. Partial melting modeling on the SGB metabasalts indicates that these rocks were derived by 20% melting of spinel peridotite. Fractional crystallisation modeling with REE reveal that the most evolved samples represent the product of fractional crystallization of least evolved magma with 35% plagioclase, 35% clinopyroxene, 20% olivine, 5% magnetite and 5% ilmenite as fractionating minerals with 40% remaining magma. Depletion of HFSE with reference to the LILE and LREE/HFSE ratios and Nb, Zr anomalies in the multi-element diagram of the mafic rocks of SGB indicate Island arc magmatic setting. The enriched Th/Yb values further substantiate that the mantle arrays were modified by subduction-related fluids or melts. The general conclusions drawn indicate that the metabasalts from the SGB were formed as a result of subduction of an intraoceanic lithosphere in a fore-arc suprasubduction zone environment.  相似文献   

Constraints on sedimentary ages of the Chuanlinggou Formation in the Ming Tombs,Beijing, North China Craton: LA-ICP-MS and SHRIMP U–Pb dating of detrital zircons     

Jing Ding  Yuruo Shi  Alfred Kröner  J. Lawford Anderson 《中国地球化学学报》2018,37(2):257-280

Detrital zircons in five sedimentary samples, MC1 to MC5, from the bottom of the Chuanlinggou Formation in the Ming Tombs District, Beijing, were dated with the LA-ICP-MS and SHRIMP U–Pb methods. Age spectra of the five samples show a major peak at 2500 Ma and a secondary peak at 2000 Ma, suggesting their provenances were mainly from the crystalline basement of the North China Craton and the Trans-North China Orogen. The youngest zircon has an age of 1673 ± 44 Ma, indicating that the Chuanlinggou Formation was deposited after this age. From sample MC4 to MC5, lithology changed from a clastic rock (fine-grained sandstone) to a carbonate rock (fine-grained dolomite), suggesting that the depositional basin became progressively deeper. The age spectrum of sample MC5 shows a major peak at 2500 Ma and a secondary peak at 2000 Ma. Sample MC4, which is stratigraphically lower than sample MC5, only had one peak at 2500 Ma. We conclude that there was a transgressive event when sediments represented by MC5 was deposited, and seawater carried ca. 2000 Ma clastic materials to the basin where the Chuanlinggou Formation was deposited, leading to the addition of ca. 2000 Ma detritus. Our research indicates that the source area for the sediments became more extensive with time. We conclude that the Chuanlinggou Formation in the Ming Tombs District was deposited in a low-energy mud flat sedimentary environment in the inter-supra tidal zone because it is mainly composed of silty mudstone and fine-grained sandstone with relatively simple sedimentary structures.  相似文献   

Basic formation mechanisms of Lake Doroninskoye soda water,East Siberia,Russia     

Svetlana V. Borzenko  Leonid V. Zamana  Larisa I. Usmanova 《中国地球化学学报》2018,37(4):546-558

The primary scientific goal of studying salt lakes is to better understand the formation of small continental-type hydrogeochemical systems. Many scientists have attributed the metamorphism of the chemical composition of salt lakes to the evaporative concentration of water. However, the formation of soda water is inconsistent with this hypothesis. Thus, analyzing intrabasinal biochemical processes and water—rocks interactions during the evaporative concentration of water allows us to understand the major mechanisms of the formation and evolution of water compositions. Therefore, the aim of this paper is to identify the key processes involved in the formation of the chemical composition of the water in Lake Doroninskoye. An analysis of the distribution of major components shows that Na⁺, HCO₃ ^?, CO₃ ^2?, and Cl^? are dominant in this water. High concentrations of these elements are the result of evaporative water concentration. Calcium, magnesium, and potassium are not accumulated because the water is saturated in minerals containing these elements. The main barrier to the growth of the sulfate content of water is sulfate reduction. This process also contributes to the additional reproduction of carbon dioxide, which reacts with the products of the hydrolysis of aluminosilicates OH^? to form HCO₃ ^? and CO₃ ^2?, thus further contributing to the natural processes of soda formation.  相似文献   

Erratum to: The oceanic cycles of the transition metals and their isotopes     

Derek Vance  Corey Archer  Susan H. Little  Michael Köbberich  Gregory F. de Souza 《中国地球化学学报》2018,37(1):151-151

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Borehole Stability in Deep Bedding Formations     

Wang Z.Q.  Ding L.Q.  Yang J.  Liu B.L. 《《地质学报》英文版》2018,92(Z1):196-196

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