Geochemistry and genesis of magmatic PGE-bearing Cu-Ni sulphide deposit in Wadi Bayhan，southeastern Yemen

The Wadi Bayhan mafic-ultramafic intrusions associated with magmatic PGE-bearing Cu-Ni sulphide deposit are located in the south margin of the Arabian-Nubian Shield,SW Yemen.The intrusions consist of dunite,olivine-pyroxenite,lherzolite,hornblendite,gabbro and gabbronorite.The dunite and lherzolite are the main host rock for the Cu-Ni ores.The new data of the chemical compositions of the rocks have SiO2(50%-53.6%),Al2O3(0-32%) and MgO(4%-28%),and relatively low TiO2(0-3.2%) and K2O+Na2O(0.04%-5.2%).The geochemical characteristics indicate that the parental magma is high-magnesium tholeiitic.Sulfur had reached saturation and immiscible sulfides droplets segregated from silicate magmas before their emplacement.     

Sedimentary environments and depositional characteristics of the Middle to Upper Eocene whale‐bearing succession in the Fayum Depression,Egypt

The discovery of whale fossils from Eocene strata in the Fayum Depression has provoked interest in the life and lifestyle of early whales. Excellent outcrop exposure also affords the dataset to develop sedimentological and stratigraphic models within the Eocene strata. Previous work generally asserts that the thick, sand‐rich deposits of the Fayum Depression represent shoreface and barrier island successions with fine‐grained lagoonal and fluvial associations capping progradational successions. However, a complete absence of wave‐generated sedimentary structures, a preponderance of thoroughly bioturbated strata and increasingly proximal sedimentary successions upwards are contrary to accepted models of the local sedimentological and stratigraphic development. This study considers data collected from two Middle to Upper Eocene successions exposed in outcrop in the Wadi El‐Hitan and Qasr El‐Sagha areas of the Fayum Depression to determine the depositional affinities of Fayum strata. Based on sedimentological and ichnological data, five facies associations (Facies Association 1 to Facies Association 5) are identified. The biological and sedimentological characteristics of the reported facies associations indicate that the whale‐bearing sandstones (Facies Association 1) record distal positions in a large, open, quiescent marine bay that is abruptly succeeded by a bay‐margin environment (Facies Association 2). Upwards, marginal‐marine lagoonal and shallow‐bay parasequences (Facies Association 3) are overlain by thick deltaic distributary channel deposits (Facies Association 4). The capping unit (Facies Association 5) represents a transgressive estuarine depositional environment. The general stratigraphic evolution resulted from a regional, tectonically controlled second‐order cycle, associated with northward regression of the Tethys. Subordinate cycles (i.e. third‐order and fourth‐order cycles) are evidenced by several Glossifungites‐ichnofacies demarcated discontinuities, which were emplaced at the base of flooding surfaces. The proposed depositional models recognize the importance of identifying and linking ichnological data with physical–sedimentological observations. As such – with the exception of wave‐generated ravinement surfaces – earlier assertions of wave‐dominated sedimentation can be discarded. Moreover, this study provides important data for the recognition of (rarely reported) completely bioturbated sand‐dominated offshore to nearshore sediments (Facies Association 1) and affords excellent characterization of bioturbated inclined heterolithic stratification of deltaic deposits. Another outcome of the study is the recognition that the whales of the Fayum Depression are restricted to the highstand systems tracts, and lived under conditions of low depositional energy, low to moderate sedimentation rates, and (not surprisingly) in fully marine waters characterized by a high biomass.     

数字黑河的思考与实践1:为流域科学服务的数字流域

多学科数据的收集和积累、多学科模型的集成以及现代化的观测系统是发展流域科学的必要前提。"数字黑河"是为黑河流域科学研究和流域集成管理而搭建的集数据、模型和观测系统于一体的信息化平台,是"数字地球"在流域尺度上的一次实践性尝试。数字黑河由数据平台、模型平台和数字化观测系统组成,其核心是观测、数据和模型平台中的信息基础设施建设,但同时也外延而扩展为以流域综合模型为骨架的各种应用。"数字黑河"已阶段性地完成了数据集成,在线数据量超过1 000 GB,并实现了完全共享,有力地支持了黑河流域的各项研究工作;在模型集成方面已初步建成了流域综合模型和空间决策支持系统。"数字黑河"的进一步构想是在e-Science的框架下将数据系统、观测系统、模型系统、信息发布系统、高性能计算及科学计算可视化集成为一个整体。