A biological origin for gravel mounds in inland Australia

More than 1000 near-circular mounds up to 40 m diameter and 2.1 m high, which contain 15–1250 m³ (mean 159 m³) of gravel, have been identified in western New South Wales. Mounds are more pebble-rich than the surrounding surface regolith and contain abundant pebbles to 1196 g weight. Resemblance to smaller gravel nest mounds of the malleefowl (Leipoa ocellata) suggests they were constructed by a similar although larger bird. Pebbles were inadvertently concentrated in the nest mounds during construction and maintenance. Formation by geological mechanisms, as burrow spoil or burial mounds is not compatible with the features of the mounds. The mounds are undated, but partial blanketing by eolian sand suggests they predate the Last Glacial Maximum. The mounds are now spatially associated with Casuarina trees. Pollen records in southeastern Australia reveal that shrub and grassland replaced Casuarina woodland as aridity increased after ca 35 000 yrs BP. Climate change driven habitat loss in the semi-arid zone likely caused the extinction of the apparently Casuarina woodland dependent megapode responsible for the gravel mounds. The mounds partly map the megapode distribution and provide an opportunity to date the local extinction of a megafauna member, compare this to climate and vegetation changes, and determine the duration of overlap with human occupation.     

Absence of overall feedback in a benthic estuarine community: A system potentially buffered from impacts of biological invasions

Species introductions are among the most dramatic human-induced impacts on aquatic and terrestrial ecosystems around the world. Stability patterns of an estuarine benthic community were investigated through guild interaction models representing the community before and after human-mediated species invasions. The study area was Yaquina Bay, a developed estuary on the central Oregon coast, U.S., where at least 12 species of nonindigenous invertebrates have been inadvertently introduced. Three of the introduced species (the polychaetes Hobsonia florida and Pseudopolydora kempi and the cumacean Nippoleucon hinumensis) are probably among the 10 most abundant invertebrate species in the intertidal benthic community. To estimate effects and potential risks of species introductions on the native community we constructed 2 types of community models based on functional-group interactions, namely, activity guild models and trophic guild models. In both cases we observed that overall feedback has a strong tendency towards zero in pre-invasion and post-invasion models. We generated 12,000 random models of similar size and could not detect this tendency. We suggest that the weak or absent overall feedback in this community may be an ecological property and not an intrinsic property of large systems as such. The reduced response to input from either invertebrate invasions or removal of native top predators, may to some extent buffer the community from such impacts. Alternative guild models suggested increased risk of stability decline in the invaded community even after accounting for potential complexity effects on stabllity. Further species introductions in this intermediately invaded estuary should be avoided.     

Mn(II) partitioning between calcium and magnesium sites in studies of dolomite origin

In an Electron Spin Resonance (ESR) study of over 30 dolomites, representing a variety of probable sedimentary origins, we observed a Mg-site to Ca-site ratio in the Mn distribution that suggests two groups of dolomite. In one group the dolomites have a Mn distribution ratio near 5.0 and an excess of Ca; in the other group the dolomites are near-stoichiometric but have a Mn distribution ratio that varies from near 5 to near 70. We suggest that these two groups reflect different origins for the dolomites. The wide variation in the manganese distribution ratio for the near-stoichiometric dolomites supplies a parameter against which other variables can be plotted in studies of dolomite origin.     

The deep Cretaceous aquifer in the Aleppo and Steppe basins of Syria: assessment of the meteoric origin and geographic source of the groundwater

A drilling project was carried out in Syria to assess the potential of the deep groundwater resources of the Cretaceous aquifer, composed of Cenomanian-Turonian limestones and dolomites. In this context, isotope (¹⁴C, ³H, δ¹³C, δ¹⁸O, δ²H) and hydrochemical analyses were performed on wells in and around the Aleppo and Steppe basins. The interpretation includes complementary results from published and unpublished literature. The results provide evidence that many new wells pump mixed groundwater from the Cretaceous aquifer and the overlying Paleogene aquifer. Radiocarbon measurements confirmed dominating Pleistocene groundwater in the Cretaceous aquifer and mainly Holocene groundwater in the Paleogene aquifer. Most groundwater in the Cretaceous aquifer seems to be recharged in the western limestone ridges, stretching from Jebel az Zawiyah (south of Idlep) via Jebel Samane (south of Afrin and A’zaz) to the region north of Aleppo, and in the Northern Palmyrides mountain belt. Some recharge also occurs around the basalt plateau of the Jebel al Hass, south east of Aleppo. It is concluded that the Taurus Mountains and the Euphrates River do not recharge the Cretaceous aquifer. The sources of recharge seem to be occasionally occurring intensive winter storms that approach from Siberia.     

Combining multivariate statistical analysis with geographic information systems mapping: a tool for delineating groundwater contamination

Multivariate Statistical Analysis (MSA) has successfully been coupled with geographic information system (GIS) mapping tools to delineate zones of aquifer contamination potential. While delineating contaminants is key to site remediation, it is often compromised by a poor understanding of hydrogeologic conditions, and by uncertainties in contaminant observations. MSA provides improved estimates of contamination potential by augmenting observed contaminant concentrations with auxiliary information from other water-quality parameters. GIS is useful for organizing and managing water-quality information by visually communicating large amounts of information. The proposed method first establishes appropriate areal extents, GIS coverages, and scales for displaying groundwater contamination concentrations of tritium and the volatile organic contaminants trichloroethylene (TCE) and tetrachloroethylene (PCE) at the Savannah River Site, South Carolina, USA. Principal components analysis is used to group variables that are most indicative of contamination potential. Tritium contamination potential is best represented as the combination of tritium with the cations Al, Mg, Na and total dissolved solids, while PCE contamination potential is predicted using PCE and Cl. Maps of contamination potentials for 1993–1995 geochemical data compare favorably with measured contaminant concentrations during 1999. Cluster analysis of water-quality data groups geochemical and contaminant concentrations into zones of homogeneous behavior.

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Resumen El Análisis Estadístico Multivariado (AEM) se ha acoplado con éxito con herramientas cartográficas del Sistema de Información Geográfico (SIG), para delinear zonas de potencial contaminación de acuíferos. En tanto que la delimitación de contaminantes es importante para recuperación del sitio, ella está a menudo amenazada por una comprensión pobre de las condiciones hidrogeológicas, y por las incertidumbres en las observaciones del contaminante. El AEM proporciona estimaciones mejoradas de contaminación potencial al aumentar las concentraciones observadas del contaminante, con la información auxiliar de otros parámetros de calidad de agua. El SIG es útil para organizar y manejar la información de calidad de agua, a través de la comunicación visual de cantidades grandes de información. El método propuesto establece primero magnitudes de área apropiadas, el área cubierta por el SIG, y las escalas para mostrar las concentraciones de contaminación del agua subterránea, a partir de tritio y de contaminantes orgánicos volátiles como tricloroetileno (TCE) y tetracloroetileno (PCE) en el sitio del Río al Savannah, Carolina del Sur, EE.UU. El análisis de componentes principales se usa para agrupar variables que son más indicativas de contaminación potencial. El potencial de contaminación Tritio, se representa mejor como la combinación de tritio con los cationes Al, Mg, Na y los sólidos disueltos totales, mientras la contaminación potencial de PCE se predice usando PCE y Cl. Los mapas de potenciales de contaminación para los datos geoquímicos de 1993–1995 se comparan favorablemente con las concentraciones medidas del contaminante durante 1999. El análisis de racimo hecho en datos de calidad de agua, agrupa concentraciones geoquímicas y concentraciones del contaminante en las zonas de comportamiento homogéneo.

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Résumé L’Analyse Statistique Multivariée (ASM) a été couplée avec succès avec les outils cartographiques des Sytèmes d’Information Géographique (SIG), afin de délimiter les zones à potentiel de contamination des aquifères. Alors que la connaissance de l’extension des contaminants est primordiale pour la réhabilitation des sites, elle est fréquemment compromise par une compréhension limitée du contexte hydrogéologique, et par les incertitudes sur l’observation des contaminants. L’ASM fournit une meilleure estimation du potentiel de contamination, en complétant les concentrations observées en contaminants par des informations annexes issues d’autres paramètres qualitatifs. Les SIG, par leurs capacités à conjuguer visuellement de grandes quantités d’information, sont utiles pour organiser et gérer les informations sur la qualité de l’eau. La première étape de la méthode proposée consiste à définir les limites spatiales appropriées, les couvertures SIG, ainsi que les échelles de visualisation des concentrations en contaminants des eaux souterraines, soit le tritium et les composés organiques volatiles trichloroéthylène et tetrachloroéthylène, sur le site de la rivière Savannah (Californie du Sud, USA). L’analyse en composantes principales est utilisée afin de regrouper les variables caractérisant de manière optimale le potentiel de contamination. Le potentiel de contamination en tritium est représenté le plus significativement par la combinaison du tritium, des cations Al, Mg et Na, et des solides dissous totaux (TDS). Le potentiel de contamination en tétrachloroéthylène est quant à lui estimé en utilisant le tetrachloroéthylène et Cl. Les cartes des potentiels de contamination établies sur les données géochimiques de la période 1993–1995 renvoient une image comparable aux concentrations en contaminants effectivement mesurées en 1999. Une analyse de groupement des données sur la qualité de l’eau rassemble les concentrations géochimiques et en contaminants dans des zones aux comportements homogènes.

     

Application of dynamic parameters for recording during acoustic profiling

The possibilities for the application of dynamic parameters of acoustic records (amplitude, reflection polarity, and frequency composition) for identifying the lithology of deposits and their physical properties, as well as their gas saturation, are discussed. Using examples of different field measurements it is shown that application of the dynamic parameters of acoustic records during interpretation allowed us in some cases to understand in detail the physical nature of visually recognized acoustic anomalies, while in other cases it provided grounds for a different interpretation of the data, and in some cases even permitted correction of errors of visual interpretation of time sections.     

Efficient solution for matrix-fracture flow with multiple interacting continua

An efficient numerical procedure for implementing the multiple interacting continua (MINC) method for fractured porous media in a general-purpose multiphase simulator is presented. This procedure is substantially faster, requires less memory, is amenable to any n-component, multiphase non-isothermal package, and is readily adaptable for parallel processing computers. The present procedure results in a reduction of the computing time by a factor of the order of NMINC³ as compared to the band algorithm, where NMINC is the number of nested continua into which each matrix block is further discretized. The memory requirement approaches a reduction factor of the order of NMINC² for larger problems compared to the band algorithm. The code for the algorithm was structured so as to set up the time consuming, but independent, computations for each matrix block in a subroutine that was parallelized and tested using a Sequent machine accessed under a UNIX environment. For NMINC=10, total computing time was reduced by 33 per cent for the use of two versus one processor, with the savings increasing for increasing NMINC. The proposed procedure can be implemented with the same ease and efficiency in conjunction with any iterative or direct method, and the grid-blocks can be ordered in any non-standard manner such as in D-4, D-2, and others. Copyright © 1999 John Wiley & Sons, Ltd.     

Geochemical evidence for the origin of moldavites

Forty-eight moldavites and samples of rocks from the impact crater of Ries were analyzed using non-destructive neutron activation analysis. The following elements have been determined: La, Ce, Sm, Eu, Lu, Sc, Co, Cs, Hf and Th; and Rb and Cr in two moldavites. The darker moldavites, more common in Moravia, show higher contents of trace elements than those lighter in colour, from Southern Bohemia.Terrestrial igneous rocks cannot be regarded as a suitable source material, but terrestrial sandy to silty claystones show strong similarities in major and trace element abundances, and exhibit analogous inter-element variations to moldavites. The Tertiary claystones and sandstones which probably covered the Ries area before the impact, are a possible source rocks for moldavites.     

Petrogenetic model for the origin of carbonatites

The petrological significance and distribution of igneous carbonatites is discussed. Particular attention is paid to the relationship that exists between carbonatites and volcanism in East Africa. Using a simple model of a carbonatite-nephelinite-ijolite volcanic complex it was discovered that all the peralkaline and carbonatitic rocks found in such a complex could be derived from a single primary nephelinitic magma. The origin of such a primary magma, and the subsequent evolution carbonatitic sub-magmas, is examined.     

用Hooke-Jeeves方法进行水文地质参数寻优的研究

模型验证阶段的水文地质参数调整一直是地下水数值模拟过程中的关键步骤。传统的参数调试方法如试估—校正法既需要大量的时间，又必须凭借经验进行人工干预。这对于本就缺少经验的人来说是无法逾越的难题。因此前人研究了包括单纯形等多种自动优化方法来反求水文地质参数。本文采用的Hooke-Jeeves法是一种算法简单，便于使用的优化方法，它避免了单纯形法必须先形成一系列单纯形顶点及通过形心寻优的麻烦，而是根据误差下降趋势直接寻优获得结果。方法首先将反求水文地质参数问题简化为一无约束优化问题，最终运用Hooke—Jeeves方法对问题进行求解，是一种简单且实用的方法。     

地下工程施工监控地质地理信息系统研究

主要设计与实现了地下工程施工监控地质地理信息系统（MGGIS）。首先分析了系统特点、结构、具有的功能以及采用的平台和相关技术,定义了数据的获取和存储格式。然后在此基础上进行了3个功能独立的子系统的详细设计与实现,分别为工程计划显示子系统、平面时空效应子系统和断面图显示子系统。首次提出在RIA技术支持下,实现B/S架构下的工程地质地理信息系统;提出了反映随施工进度变化地下工程及环境空间信息的显示平台技术方案,充分反应了地下工程施工中空间信息具有时空效应的特点,适合地下工程安全风险管理的需要。该系统与同类型地理信息系统平台相比具有使用简单、交互性强、速度快等优点,研究成果已经在北京轨道交通工程安全风险监控系统和南京地铁工程安全风险监控系统等相关项目中得以应用。     

Application of the GRACE satellite mission for solving geological and geographic problems

In this paper we provide a literature review of the geological and geographic problems that were successfully solved via the application of the Gravity Recovery And Climate Experiment (GRACE) satellite mission data. GRACE is a gravitational satellite mission whose purpose is the precise mapping of variations of the Earth’s gravity field. The data have high resolution, which provides the opportunity to solve many geological and geographical problems.     

Speaking with the same voice: geographic interpretation and representation of literary resources

New forms of literary resource interpretation in geogarphy have come to the fore in recent years. However, representation has not kept pace with this interpretive advance. I explore the background of this idea, discuss its potential, and present an example of alternative representations using the writings of Michael Shaara and Robert Penn Warren.     

A radical pathway for organic phosphorylation during schreibersite corrosion with implications for the origin of life

Phosphorylated compounds (e.g., DNA, RNA, phospholipids, and many coenzymes) are critical to biochemistry. Thus, their origin is of prime interest to origin of life studies. The corrosion of the meteoritic mineral schreibersite ((Fe, Ni)₃P) may have significantly contributed to the origin of phosphorylated biomolecules. Corrosion of synthetic schreibersite in a variety of solutions was analyzed by nuclear magnetic resonance spectroscopy, mass spectrometry, and electron paramagnetic resonance spectroscopy. These methods suggest a free-radical reaction pathway for the corrosion of schreibersite to form phosphite radicals () in aqueous solution. These radicals can form activated polyphosphates and can phosphorylate organic compounds such as acetate to form phosphonates and organophosphates (3% total yield). Phosphonates (O₃P-C) are found in the organic P inventory of the carbonaceous meteorite Murchison. While phosphonates are rare in biochemistry, the ubiquity of corroding iron meteorites on the early Earth could have provided a source of organic phosphorous compounds for the origin of life, and may have led to the role of organophosphates as a product of early evolution.     

Shallow groundwater dynamics and origin of salinity at two sites in salinated and water-deficient region of North China Plain,China

Large salinated areas are distributed in the middle and east of the North China Plain (NCP), where the fresh water shortage is serious. In this study, two sites in Cangzhou (CZ) and Hengshui (HS) of Hebei Province were selected to study the dynamics of shallow groundwater level and salinity. Electrical conductivity (EC) of groundwater was combined with the isotope compositions of δ¹⁸O and δ²H to identify the origin of salinity. Results showed that the dynamics of groundwater level at both sites were mainly controlled by precipitation and evaporation. Soil texture and structure played a significant role in the dynamics of salinity. The summer precipitation diluted the EC of groundwater at the HS site with homogeneous soil of sand loam, suggesting the larger infiltration rate; however, it did not dilute the EC at the CZ site with heterogeneous soil of sand loam and silt loam, suggesting that the summer precipitation could not recharge the groundwater directly. In winter, the EC decreased rapidly due to the temperature gradient underground if the groundwater was above the threshold level (at least 3 m below the ground surface) after the rainy season. Isotopes of δ¹⁸O and δ²H showed that precipitation was the major recharge source for the groundwater at the two sites. The salt mainly comes from the dissolution of soil or rock at the CZ site. While, the evaporation effect was strong at the HS site leading to the increase of the salt concentration.     

A new analytical model for consolidation with multiple vertical drains

Various analytical theories of consolidation for soils with vertical drains have been proposed in the past. Most conventional theories are based on a cylindrical unit cell that contains only a single vertical drain. This paper described a new analytical model where a vertical drain located at the centre (the ‘inner vertical drain’) and is surrounded by two or three vertical drains (the ‘outer vertical drains’), the number of which depends on whether the configuration is triangular or rectangular. Both types of drains are combined into a cylindrical unit cell, and the water is assumed to flow both inwards to the inner vertical drain and outwards to the outer vertical drains distributed around the circumference. The outer radial boundary of the unit cell is regarded as a permeable boundary, with a drainage capacity of two or three separate vertical drains for triangular and rectangular configurations, respectively. The smear effects and the drainage resistances for both the inner and outer vertical drains are considered in the analysis as well. In this way, the equations governing the consolidation process with multiple vertical drains are derived, and the corresponding analytical solutions are obtained for instantaneously loading, ramp loading and multi‐stage of instantaneously loading and multi‐stage of ramp loading. The present solutions are finally compared with several conventional solutions for a single vertical drain in the literature. The results show that the present model predicts the same average degree of consolidation as conventional models do, which verifies the correctness of this new model. Finally, the settlement predicted by the present solution is compared with the measured settlement from a field test at the Port of Brisbane, Australia, which shows a good agreement between them. Copyright © 2016 John Wiley & Sons, Ltd.