Nonparametric Estimates of the Sea State Bias for the Jason-1 Radar Altimeter

The Jason-1 sea state bias (SSB) is analyzed in depth from the first year of GDR products. Compared to previous missions, this work benefits from two aspects of the empirical determination of the SSB from the altimetric data themselves. First, from a methodological point of view, a nonparametric technique (NP) has been developed and largely tested on TOPEX/Poseidon 1, GFO and Envisat data. The NP estimator has proven to be a useful tool in the SSB estimation, and it is now mature enough to be used for a refined analysis. On the other hand, the SSB can be extracted from three different data sets (crossovers, collinear data, and residuals) with different characteristics. It is then possible to cross calibrate various estimations of the SSB models and to determine the most accurate one. A systematic comparison is made between these different estimates for the Jason-1 altimeter. The collinear and crossover data sets yield very similar estimates despite their difference of spatial and temporal distributions. These SSB models assure consistency with the TOPEX mission when comparing Jason-1 and TOPEX residuals during the tandem phase. Thanks to the present work, the impact of the short wavelengths filtering on the SSB estimation is evidenced. More generally, our understanding of potential errors affecting the sea surface height and their impact onto the SSB estimation is also improved.     

Morphology,structure and kinematics of a rainfall controlled slow‐moving Andean landslide,Peru

The large slow‐moving landslide of Maca is located in the upper Colca valley (southern Peru), a region characterized by a well pronounced rainy period, and intense and recurrent sustained seismicity. The landslide, developed in deep lacustrine deposits, has recently accelerated, threatening the Maca village. This work aims at understanding the rupture mechanism and the causes of the recent landslide reactivation/acceleration. We present a multidisciplinary characterization of the Maca landslide that includes: (i) geological and morphological mapping in the field; (ii) remote sensing analysis using an historical aerial photograph of 1955 and the Pléiades satellite images (2013); (iii) global positioning system (GPS) including time‐series of surveys over 13 years, and continuous measurements over 14 months; (iv) a geophysical campaign with deep electrical resistivity tomography profiles acquired across the landslide mass. Our study shows that this 60 Mm³ landslide, which can be classified as a clay/silt compound landslide, moved by 15 m between 2001 and 2014 with a large inter‐annual velocity variation (up to a factor of 500) depending on the rainfall intensity. We suggest that these dramatic changes in velocity are the result of the combination of a threshold mechanism and the short intense rainy season in Peru. This study reveals three main driving factors acting at different timescales: (i) over several decades, the river course has significantly changed, causing the Maca landslide reactivation in the 1980s due to the erosion of its toe; (ii) at the year scale, a minimum amount of rainfall is required to trigger the motion and this amount controls the landslide velocity; (iii) transient changes in slide velocity may occur anytime due to earthquakes. This study particularly highlights the non‐linear behaviour of the motion with rainfall. Copyright © 2016 John Wiley & Sons, Ltd.     

苏鲁超高压变质岩中地震波速随围压的变化规律

我们在10~800MPa的静水压力下测量了中国大陆科学钻探(CCSD)主孔岩心和采自苏鲁地区地表露头上的共68块典型超高压变质岩试样的地震波速,并建立了波速和围压的定量关系,成功地解释了描述这一定量关系方程中4个参数的物理意义。笔者相信,本文将为超高压变质岩地区以及新老俯冲带地震波资料的解释提供必不可少的理论和实验支撑。     

Quantifying the Effects of Well Development in Unconsolidated Material

A fully instrumented physical model was designed and built to reproduce development by surging and monitor its effects during surging and after development. The model simulates a horizontal layer in a confined aquifer with control of vertical overburden pressure. An automatic apparatus produced development by surging in successive phases up to 24 hours. Aquifer tests in steady-state conditions were performed between successive phases. The paper reports the main results of three experiments performed with Johnson screens 200 mm in diameter; they had slot sizes between the D₅₄ and D₇₀ of the aquifer soil. This soil was placed under controlled conditions, and initial homogeneity was obtained as confirmed by initial control tests. Pore pressures (and thus hydraulic heads) were continuously monitored during development phases and aquifer tests by 22 electronic piezometers at distances between 0 and 1 m from the screen. These piezometers measured water pressures every 0.1 s when required. Solid particles passing through the screen were recovered to study the solid yield and the gradation of particles. Positive and negative values of local gradients reached values up to 400 close to the screen at the beginning of development and decreased with time of development. These high values produced high seepage forces displacing particles in the aquifer. The well yield was increased by a factor of 6 after development. These model test results confirmed empirical criteria on entrance velocity, internal stability criteria, and field values of "sand" production by development. In addition, they enabled a quantification of skin effects to be considered in interpreting an aquifer test.     

Source and possible tectonic driver for Jurassic–Cretaceous gold deposits in the West Qinling Orogen,China

The West Qinling Orogen (WQO) in Central China Orogenic Belt contains numerous metasedimentary rock-hosted gold deposits (>2000 t Au), which mainly formed during two pulses: one previously recognized in the Late Triassic to Early Jurassic (T3–J1) and one only recently identified in the Late Jurassic to Early Cretaceous (J3–K1). Few studies have focused on the origin and geotectonic setting of the J3–K1 gold deposits.Textural relationships, LA-ICP-MS trace element and sulfur isotope compositions of pyrites in hydrothermally altered T3 dykes within the J3–K1 Daqiao deposit were used to constrain relative timing relationships between mineralization and pyrite growth in the dykes, and to characterize the source of ore fluid. These results are integrated with an overview of the regional geodynamic setting, to advance understanding of the tectonic driver for J3–K1 hydrothermal gold systems. Pyrite in breccia- and dyke-hosted gold ores at Daqiao have similar chemical and isotopic compositions and are considered to be representative of J3–K1 gold deposits in WQO. Co/Ni and sulfur isotope ratios suggest that ore fluids were derived from underlying Paleozoic Ni- and Se-rich carbonaceous sedimentary rocks. The geochemical data do not support the involvement of magmatic fluids. However, in the EQO (East Qinling Orogen), J3–K1 deposits are genetically related to magmatism. Gold mineralization in WQO is contemporaneous with magmatic deposits in the EQO and both are mainly controlled by NE- and EW-trending structures produced by changes in plate motion of the Paleo-Pacific plate as it was subducted beneath the Eurasian continent. We therefore infer that the J3–K1 structural regime facilitated the ascent of magma in the EQO and metamorphic fluids in the WQO with consequent differences in the character of contemporaneous ore deposits. If this is correct, then the far-field effects of subduction along the eastern margin of NE Asia extended 1000's of km into the continental interior.     

A coarse-scale compositional model

In subsurface flow modeling, compositional simulation is often required to model complex recovery processes, such as gas/CO ₂ injection. However, compositional simulation on fine-scale geological models is still computationally expensive and even prohibitive. Most existing upscaling techniques focus on black-oil models. In this paper, we present a general framework to upscale two-phase multicomponent flow in compositional simulation. Unlike previous studies, our approach explicitly considers the upscaling of flow and thermodynamics. In the flow part, we introduce a new set of upscaled flow functions that account for the effects of compressibility. This is often ignored in the upscaling of black-oil models. In the upscaling of thermodynamics, we show that the oil and gas phases within a coarse block are not at chemical equilibrium. This non-equilibrium behavior is modeled by upscaled thermodynamic functions, which measure the difference between component fugacities among the oil and gas phases. We apply the approach to various gas injection problems with different compositional features, permeability heterogeneity, and coarsening ratios. It is shown that the proposed method accurately reproduces the averaged fine-scale solutions, such as component overall compositions, gas saturation, and density solutions in the compositional flow.     

Benthic remineralization at the land–ocean interface: A case study of the Rhône River (NW Mediterranean Sea)

Biogeochemical processes in sediments under the influence of the Rhône River plume were studied using both in situ microelectrodes and ex situ sediment core incubations. Organic carbon (OC) and total nitrogen (TN) content as well as stable carbon isotopic composition of OC (δ¹³C_OC) were analysed in 19 surface sediments to determine the distribution and sources of organic matter in the Rhône delta system. Large spatial variations were observed in both the total O₂ uptake (5.2 to 29.3 mmol m⁻² d⁻¹) and NH₄⁺ release (−0.1 to −3.5 mmol m⁻² d⁻¹) rates at the sediment–water interface. The highest fluxes were measured near the Rhône River mouth where sedimentary OC and TN contents reached 1.81% and 0.23% respectively. Values of δ¹³C_OC ranged from −26.83‰ to −23.88‰ with a significant seawards enrichment tracing the dispersal of terrestrial organic matter on the continental shelf. The amount of terrestrial-derived OC reaches 85% in sediments close to the Rhône mouth decreasing down to 25% in continental shelf sediments. On the prodelta, high terrestrial OC accumulation rates support high oxygen uptake rates and thus indicating that a significant fraction of terrestrial OC is remineralized. A particulate organic carbon (POC) mass balance indicates that only 3% of the deposited POC is remineralized in prodelta sediments while 96% is recycled on the continental shelf. It was calculated that a large proportion of the Rhône POC input is either buried (52%) or remineralized (8%), mostly on the prodelta area. The remaining fraction (40%) is either mineralized in the water or exported outside the Rhône delta system in dissolved or particulate forms.