In‐situ analysis of trace elements and Sr–Pb isotopes of K‐feldspars from Tongshankou Cu–Mo deposit,SE Hubei Province,China: Insights into early potassic alteration of the porphyry mineralization system

In the Tongshankou porphyry deposit (SE Hubei Province, South China), three types of K‐feldspars are recognized: (I) the phenocryst type in the porphyry that crystalized during the magmatic stage, (II) the megacryst type and (III) the vein type in the altered porphyry and orebody that was produced by hydrothermal fluids. A detailed in‐situ analysis of trace elements and Sr–Pb isotopes was carried out on K‐feldspars in an attempt to unravel their formation processes and to trace the element sources during potassic alteration. The Type III K‐feldspars show lower Sr contents and Sr‐isotope ratios but higher Pb contents and Pb‐isotope ratios than the Type I and II K‐feldspars, possibly reflecting a contribution from the country carbonate rocks with less radiogenic Sr but more radiogenic Pb sources, and indicate that the ore‐forming fluids and materials may have been partially derived from external sources such as the host sedimentary rocks during the early potassic alteration stage.     

Meteorological disaster frequency at prefecture-level city scale and induced losses in mainland China during 2011–2019

Natural Hazards - Meteorological disasters (MDs), including drought, flood, hail, low temperature and frost (LTF), are causing severe damage to human life and economic development in China. Mapping...     

An analytical study on three‐dimensional versus two‐dimensional water table‐induced flow patterns in a Tóthian basin

Although it has been increasingly acknowledged that groundwater flow pattern is complicated in the three‐dimensional (3‐D) domain, two‐dimensional (2‐D) water table‐induced flow models are still widely used to delineate basin‐scale groundwater circulation. However, the validity of 2‐D cross‐sectional flow field induced by water table has been seldom examined. Here, we derive the analytical solution of 3‐D water table‐induced hydraulic head in a Tóthian basin and then examine the validity of 2‐D cross‐sectional models by comparing the flow fields of selected cross sections calculated by the 2‐D cross‐sectional model with those by the 3‐D model, which represents the “true” cases. For cross sections in the recharge or discharge area of the 3‐D basin, even if head difference is not significant, the 2‐D cross‐sectional models result in flow patterns absolutely different from the true ones. For the cross section following the principal direction of groundwater flow, although 2‐D cross‐sectional models would overestimate the penetrating depth of local flow systems and underestimate the recharge/discharge flux, the flow pattern from the cross‐sectional model is similar to the true one and could be close enough to the true one by adjusting the decay exponent and anisotropy ratio of permeability. Consequently, to determine whether a 2‐D cross‐sectional model is applicable, a comparison of hydraulic head difference between 2‐D and 3‐D solutions is not enough. Instead, the similarity of flow pattern should be considered to determine whether a cross‐sectional model is applicable. This study improves understanding of groundwater flow induced by more natural water table undulations in the 3‐D domain and the limitations of 2‐D models accounting for cross‐sectional water table undulation only.     

An asynchronous Geoprocessing Workflow and its application to an Antarctic ozone monitoring and mapping service

The integration of Sensor Web Enablement services with other Open Geospatial Consortium (OGC) Web Services as Geospatial Processing Workflows (GPW) is essential for future Sensor Web application scenarios. With the help of GPW technology, distributed and heterogeneous OGC Web Services can be organized and integrated as compound Web Service applications that can direct complicated earth observation tasks. Under the Sensor Web environment, asynchronous communications between Sensor Web Services are common. We have proposed an asynchronous GPW architecture for the integration of Sensor Web Services into a Web Service Business Process Execution Language workflow technology. We designed a Sensor Information Accessing and Processing workflow, an asynchronous GPW instance, to take an experiment of observing and mapping ozone over Antarctica. Based on our results, our proposed asynchronous workflow method shows the advantages of taking environmental monitoring and mapping tasks.     

Thermal equation of state of natural tourmaline at high pressure and temperature

Synchrotron-based in situ angle-dispersive X-ray diffraction experiments were conducted on a natural uvite-dominated tourmaline sample by using an external-heating diamond anvil cell at simultaneously high pressures and temperatures up to 18 GPa and 723 K, respectively. The angle-dispersive X-ray diffraction data reveal no indication of a structural phase transition over the P–T range of the current experiment in this study. The pressure–volume–temperature data were fitted by the high-temperature Birch–Murnaghan equation of state. Isothermal bulk modulus of K ₀ = 96.6 (9) GPa, pressure derivative of the bulk modulus of \(K_{0}^{\prime } = 12.5 \;(4)\), thermal expansion coefficient of α ₀ = 4.39 (27) × 10^?5 K^?1 and temperature derivative of the bulk modulus (?K/?T) _P  = ?0.009 (6) GPa K^?1 were obtained. The axial thermoelastic properties were also obtained with K _a0 = 139 (2) GPa, \(K_{a0}^{\prime }\) = 11.5 (7) and α _a0 = 1.00 (11) × 10^?5 K^?1 for the a-axis, and K _c0 = 59 (1) GPa, \(K_{c0}^{\prime }\) = 11.4 (5) and α _c0 = 2.41 (24) × 10^?5 K^?1 for the c-axis. Both of axial compression and thermal expansion exhibit large anisotropic behavior. Thermoelastic parameters of tourmaline in this study were also compared with that of the other two ring silicates of beryl and cordierite.     

华南壳幔结构与动力学的宽频地震观测研究

了解华南各岩石圈块体壳幔结构和各向异性方面的差异是揭示华南深部构造演化的基础。本文利用布设于华南的两条宽频地震测线观测数据,采用多种地震学方法对华南的地壳上地幔结构和各向异性进行了研究。接收函数结果表明,华南地区地壳厚度和岩石圈厚度都较薄,地壳厚度自东南沿海向西北内陆增厚,扬子克拉通的泊松比(波速比)低于华夏块体,表明扬子克拉通地壳较华夏块体更偏长英质。约北纬29°以北的扬子克拉通地幔转换带厚度明显增厚,可能是由地幔转换带底部停滞的冷的古太平洋板片或中生代克拉通碰撞残留造成的。层析成像结果显示华南上地幔具有很强的横向差异性,上地幔中的强烈低速异常体可能对应了晚中生代发生广泛岩浆作用时的岩浆房和岩浆通道。台湾下方的上地幔存在南北横向差异明显的高速异常,分别对应台湾南部向东俯冲的欧亚板块及台湾北部向北俯冲的菲律宾海板块。俯冲的欧亚板块在台湾南部是连续的,而在台湾中北部,由于与菲律宾海板块的相互作用,俯冲的欧亚板块被折断。剪切波分裂结果显示,以江绍断裂为界,华夏块体与扬子克拉通的岩石圈地幔各向异性存在明显的横向变化,表明两者的构造演化过程有显著差异。     

塔里木盆地西部阿克莫木气藏地层压力特征

阿克莫木气田目前已有多口井完钻,各井在钻揭白垩系砂岩储层前,对地层压力纵向上的变化规律认识不清,在什么层位及深度下7″套管意见仍不统一。本文根据目前研究现状和生产面临问题,对白垩系各组地层分布规律、压力特征进行了详细研究,认为白垩系克孜勒苏群、库克拜组分布稳定,压力窗口相近,白垩系东巴组与上覆古近系阿尔塔什组压力窗口相近。建议今后该区钻探7″套管应下至库克拜组顶部-东巴组底部,减少地层漏失和油气勘探风险。     

地史上巨量蒸发岩省的成因及其地质意义

全球蒸发岩从震旦纪到新近纪均有发育, 其最发育时期为震旦纪-寒武纪、二叠纪-三叠纪以及侏罗纪-白垩纪, 且具有幕式分布特点.它们在一定区域(低纬区)常大规模集中发育, 跨越不同的沉积盆地类型, 面积和厚度巨大, 时代跨度较短且连续, 笔者称之为巨量蒸发岩省.本文基于全球蒸发岩层系古板块再造、沉积岩相恢复、地层柱状对比、盆地构造分析等方法, 对巨量蒸发岩省的发育、分布、成因及其地质意义进行了探讨.巨量蒸发岩省形成、分布与地史中的造山带演化、超大陆的聚合与裂解、干旱气候带(南北纬30°之间)、海平面变化等因素有着密切联系; 其主要形成于干旱环境下相对封闭、靠海水潜流补给的台地和盆地中; 所处的构造单元主要为泛大陆板块内部狭长的裂谷带、特提斯造山带的残余洋盆、海-陆过渡带、陆表海或孤立板块的台地中心.