New Jurassic Pseudopolycentropodids from China (Insecta: Mecoptera)

Abstract: In this paper two new species of fossil Pseudopolycentropus Handlirsch, 1906 are described: Pseudopolycentropus janeannae sp. nov. and P. novokshonovi, sp. nov. All of them were recovered from the Middle Jurassic non-marine sedimentary strata of northeastern China. The new material from China reveals that the early diversification of pseudopolycentropodids was well underway by the Middle Jurassic.     

Fluids during diagenesis and sulfate vein formation in sediments at Gale crater,Mars

We model the fluids involved in the alteration processes recorded in the Sheepbed Member mudstones of Yellowknife Bay (YKB), Gale crater, Mars, as revealed by the Mars Science Laboratory Curiosity rover investigations. We compare the Gale crater waters with fluids modeled for shergottites, nakhlites, and the ancient meteorite ALH 84001, as well as rocks analyzed by the Mars Exploration rovers, and with terrestrial ground and surface waters. The aqueous solution present during sediment alteration associated with phyllosilicate formation at Gale was high in Na, K, and Si; had low Mg, Fe, and Al concentrations—relative to terrestrial groundwaters such as the Deccan Traps and other modeled Mars fluids; and had near neutral to alkaline pH. Ca and S species were present in the 10^?3 to 10^?2 concentration range. A fluid local to Gale crater strata produced the alteration products observed by Curiosity and subsequent evaporation of this groundwater‐type fluid formed impure sulfate‐ and silica‐rich deposits—veins or horizons. In a second, separate stage of alteration, partial dissolution of this sulfate‐rich layer in Yellowknife Bay, or beyond, led to the pure sulfate veins observed in YKB. This scenario is analogous to similar processes identified at a terrestrial site in Triassic sediments with gypsum veins of the Mercia Mudstone Group in Watchet Bay, UK.     

Late Silurian–Middle Devonian long-term shoreline shifts on the northern Gondwanan margin: eustatic versus tectonic controls

Long-term shoreline shifts reflect eustatic changes, tectonic activity, and sediment supply. Available lithostratigraphical data from northern Africa, Arabia, and the Tethys Hymalaya, coupled with facies interpretations, permit us to trace late Silurian–Middle Devonian long-term shoreline shifts across the northern Gondwanan margin and to compare them with constraints on global sea-level changes. Our analysis establishes a regression–transgression cycle. Its coincident global sea-level changes reveal the dominance of the eustatic control. A transgression–regression cycle observed in Arabia is best explained by regional subsidence. Our study highlights the importance of constraining the role of regional tectonics when interpreting shoreline shifts.     

灰色动态预测方法及其在变形预测中的应用

在分析比较了GM(1,1)预测模型的不足之后,提出一种实时引入新信息的等维新息和等维灰数递补组合动态预测方法。首先同常规预测法作了比较,然后进行了三峡链子崖危岩体变形发展趋势预测及有效性验证。     

三角形形状因子对地壳形变计算精度的影响

引入三角形内切圆半径与外接圆半径之比值作为三角形形状因子，讨论利用三角形法计算应变分量的精度与三角形形状因子之间的关系。设计一种涵盖所有三角形形状的方法，计算分析了用三角形法计算应变分量精度的分布。研究表明：当三角形形状因子达到0．36时，计算得到的应变分量均方差，一般不会超过位移数据均方差的3倍；而当三角形形状因子小于0．1时，计算得到的应变分量均方差会陡然增大，这样的三角形一般不适合用于应变分量的计算。在利用GPS观测站组成三角形计算地应变时，建议所组成的三角形形状因子的阈值应取为0．1～0．36。     

Quantifying the effect of humic matter on the emission of mercury from artificial soil surfaces

A set of surface samples was created using purified laboratory grade sand treated with 0.05 μg/g Hg as the HgCl₂ salt and various concentrations of purified humic and fulvic acids. Emissions of elemental Hg from these substrates to the atmosphere were inversely correlated with the organic content of the samples (99% confidence level). The greatest differences in Hg emissions were found between samples containing the lowest concentrations of humic matter (0% versus 0.01% humic, and 0.01% versus 0.1% humic), only small differences in Hg flux were found to exist for samples with higher concentrations of humic acid (1%, 5%, and 100%). This effect was independent of the type of humic substance used, with both humic and fulvic acids showing an inhibitory effect on surface Hg emissions.     

The Influence of Benthic Macrofauna on the Erodibility of Intertidal Sediments with Varying mud Content in Three New Zealand Estuaries

Fine sediment inputs can alter estuarine ecosystem structure and function. However, natural variations in the processes that regulate sediment transport make it difficult to predict their fate. In this study, sediments were sampled at different times (2011–2012) from 45 points across intertidal sandflat transects in three New Zealand estuaries (Whitford, Whangamata, and Kawhia) encompassing a wide range in mud (≤63 μm) content (0–56 %) and macrofaunal community structure. Using a core-based erosion measurement device (EROMES), we calculated three distinct measures of sediment erosion potential: erosion threshold (? _c ; N m^?2), erosion rate (ER; g m^?2 s^?1), and change in erosion rate with increasing bed shear stress (m _e ; g N^?1 s^?1). Collectively, these measures characterized surface (? _c and ER) and sub-surface (m _e ) erosion. Benthic macrofauna were grouped by functional traits (size and motility) and data pooled across estuaries to determine relationships between abiotic (mud content, mean grain size) and biotic (benthic macrofauna, microbial biomass) variables and erosion measures. Results indicated that small bioturbating macrofauna (predominantly freely motile species <5 mm in size) destabilized surface sediments, explaining 23 % of the variation in ? _c (p ≤ 0.01) and 59 % of the variation in ER (p ≤ 0.01). Alternatively, mud content and mean grain size cumulatively explained 61 % of the variation in m _e (p ≤ 0.01), where increasing mud and grain size stabilized sub-surface sediments. These results highlight that the importance of biotic and abiotic predictors vary with erosion stage and that functional group classifications are a useful way to determine the impact of benthic macrofauna on sediment erodibility across communities with different species composition.     

Quantitative analysis of top-seal capacity: offshore Netherlands,southern North Sea

Sealing characteristics of the caprock to the Main Buntsandstein reservoir sands in the P blocks in the Dutch offshore are assessed based on a core from the P15 well. The core which represents the Main Buntsandstein, Solling, Röt, and Muschelkalk interval has been analyzed using standard geologic and petrophysical techniques including mercury-injection capillary-pressure tests. The caprock to the Main Buntsandstein reservoir sands consists of anhydritic and/or dolomitic sandstone to argillaceous siltstone, silty shale, and dolostone. Early emplacement of nodular anhydrite followed by cementation and replacement by anhydrite, dolomite, and siderite has resulted in tight, submicroporous pore geometries which act as good to excellent seals. Capillary entry pressures of the best caprock lithologies are such that gas columns of the order of 300 m could potentially be trapped. The actual column height in P15 is about 125 m as indicated by RFT data. The presence of significant gas accumulations in the Main Buntsandstein in the P12, P14, P15, P18 and adjoining Q8 and Q16 blocks suggests that the P15 top-seal quality may be representative for that area.     

Flux between soil and atmosphere, vertical concentration profiles in soil, and turnover of nitric oxide: 2. Experiments with naturally layered soil cores

Intact soils cores were taken with a stainless steel corer from a sandy podzol and a loamy luvisol, and used to measure the flux (J) of NO between soil and atmosphere and the vertical profile of the NO mixing ratios (m) in the soil atmosphere, both as function of the NO mixing ratio (m _a) in the atmosphere of the headspace. These measurements were repeated after stepwise excavation of the soil column from the top, e.g. by removing the upper 2 cm soil layer. The gaseous diffusion coefficients of NO in the soil cores were either computed from soil porosity or were determined from experiments using SF6. The NO fluxes (J) that were actually measured at the soil surface were compared to the fluxes which were calculated either from the vertical NO profiles (J _c ) or from the NO production and uptake rates (J _m ) determined in the excavated soil samples. In the podzol, the actually measured (J) and the calculated (J _m , J_m) NO fluxes agreed within a factor of 2. In the luvisol, the measured NO fluxes (J) and those calculated from the vertical NO profiles (J _c ) also agreed well, but in the upper 6 cm soil layer the NO fluxes (J _m ) calculated from NO production and uptake rates were up to 7 times higher than the measured NO fluxes. This poor agreement was probably due to the inhomogeneous distribution of NO production and consumption processes and the change of diffusivities within the top layers of the luvisol. Indeed, the luvisol showed a pronounced maximum of the NO mixing ratios at about 6 cm depth, whereas the podzol column exhibited a steady and exponential decrease of the NO mixing ratios with depth. The inhomogeneities in the luvisol were confirmed by incubation of the soil cores under anoxic conditions. This treatment resulted in production of NO at several depths indicating a zonation of increased potential activities within the luvisol profile which may have biased the modelling of the NO surface flux from turnover measurements in soil samples. Inhomogeneities could be achieved even in homogenized soil by fertilization with nitrate solution.