Training Image Free High-Order Stochastic Simulation Based on Aggregated Kernel Statistics

Mathematical Geosciences - A training image free, high-order sequential simulation method is proposed herein, which is based on the efficient inference of high-order spatial statistics from the...     

The World Karst Aquifer Mapping project: concept,mapping procedure and map of Europe

Karst aquifers contribute substantially to freshwater supplies in many regions of the world, but are vulnerable to contamination and difficult to manage because of their unique hydrogeological characteristics. Many karst systems are hydraulically connected over wide areas and require transboundary exploration, protection and management. In order to obtain a better global overview of karst aquifers, to create a basis for sustainable international water-resources management, and to increase the awareness in the public and among decision makers, the World Karst Aquifer Mapping (WOKAM) project was established. The goal is to create a world map and database of karst aquifers, as a further development of earlier maps. This paper presents the basic concepts and the detailed mapping procedure, using France as an example to illustrate the step-by-step workflow, which includes generalization, differentiation of continuous and discontinuous carbonate and evaporite rock areas, and the identification of non-exposed karst aquifers. The map also shows selected caves and karst springs, which are collected in an associated global database. The draft karst aquifer map of Europe shows that 21.6% of the European land surface is characterized by the presence of (continuous or discontinuous) carbonate rocks; about 13.8% of the land surface is carbonate rock outcrop.

     

The early Cretaceous orogen-scale Dabieshan metamorphic core complex: implications for extensional collapse of the Triassic HP–UHP orogenic belt in east-central China

International Journal of Earth Sciences - The Dabieshan massif is famous as a portion of the world’s largest HP–UHP metamorphic belt in east-central China that was built by the Triassic...     

The zircon evidence of temporally changing sediment transport—the NW Gondwana margin during Cambrian to Devonian time (Aoucert and Smara areas,Moroccan Sahara)

International Journal of Earth Sciences - Detrital zircon provenance studies are an established tool to develop palaeogeographic models, mostly based on zircon of siliciclastic rocks and isotope...     

Water solubility in haplogranitic melts coexisting with H2O-H2 fluids

The water solubility in haplogranitic melts (normative composition Ab₃₉Or₃₂Qz₂₉) coexisting with H₂O-H₂ fluids at 800 and 950 °C and 1, 2 and 3 kbar vapour pressure has been determined using IR spectroscopy. The experiments were performed in internally heated pressure vessels and the hydrogen fugacity (f _H2) was controlled using the double capsule technique and oxygen buffer assemblages (WM and IW). Due to the limited lifetimes of these oxygen buffers the water solubility was determined from diffusion profiles (concentration-distance profiles) measured with IR spectroscopy in the quenched glasses. The reliability of the experimental strategy was demonstrated by comparing the results of short- and long-duration experiments performed with pure H₂O fluids. The water solubility in Ab₃₉Or₃₂Qz₂₉ melts equilibrated with H₂O-H₂ fluids decreases progressively with decreasing f _H2O, as f _H2 (or X _H2) increases in the fluid phase. The effect of H₂ on the evolution of the water solubility is similar to that of CO₂ or another volatile with a low solubility in the melt and can be calculated in a first approximation with the Burnham water solubility model. Recalculation of high temperature water speciation for AOQ melts coexisting with H₂O-H₂ fluids at 800 °C, 2 kbar suggests that the concentrations of molecular H₂O are proportional to f _H2O (calculated using available mixing models), indicating Henrian behaviour for the solubility of molecular H₂O in haplogranitic melts. Received: 29 June 1998 / Accepted: 10 March 1999     

The production of cosmogenic nuclides in stony meteoroids by galactic cosmic‐ray particles

Abstract— We present a purely physical model for the calculation of depth‐ and size‐dependent production rates of cosmogenic nuclides by galactic cosmic‐ray (GCR) particles. besides the spectra of primary and secondary particles and the excitation functions of the underlying nuclear reactions, the model is based on only one free parameter—the integral number of gcr particles in the meteoroid orbits. We derived this value from analysis of radionuclide data in Knyahinya. We also show that the mean GCR proton spectrum in the meteoroid orbits has been constant over about the last 10 Ma. For the major target elements in stony meteoroids, we present depth‐ and size‐dependent production rates for ¹⁰Be, ¹⁴C, ²⁶Al, ³⁶Cl, and ⁵³Mn as well as for the rare gas isotopes ³He, ²⁰Ne, ²¹Ne, ²²Ne, ³⁶Ar, and ³⁸Ar. The new data differ from semi‐empirical estimates by up to a factor of 4 but agree within ～20% with results obtained by earlier parametric or physical approaches. The depth and size dependence of the shielding parameter ²²Ne/²¹Ne and the correlations ²⁶Al vs. ¹⁰Be, ²⁶Al vs. ⁵³Mn, ¹⁰Be/²¹Ne vs. ²²Ne/²¹Ne, and ³⁶Ar vs. ³⁶Cl for deciphering preatmospheric sizes, shielding depths, terrestrial residence times, and exposure histories are also discussed.     

Variability of the transgressive stacking pattern under environmental changes control: Example from the Post-Glacial deposits of the Gulf of Lions inner-shelf,Mediterranean, France

At a regional scale, high-resolution seismic dataset analysis provides an accurate image of the stratigraphic organization of the Post-Glacial transgressive deposits of the Gulf of Lions inner-shelf. Architectural and stratigraphic characteristics are different in four main sectors, clearly demonstrating that depositional models have to be adapted from place to place following the interplay of various genetic factors.     

The flood probability distribution tail: how heavy is it?

This paper empirically investigates the asymptotic behaviour of the flood probability distribution and more precisely the possible occurrence of heavy tail distributions, generally predicted by multiplicative cascades. Since heavy tails considerably increase the frequency of extremes, they have many practical and societal consequences. A French database of 173 daily discharge time series is analyzed. These series correspond to various climatic and hydrological conditions, drainage areas ranging from 10 to 10⁵ km², and are from 22 to 95 years long. The peaks-over-threshold method has been used with a set of semi-parametric estimators (Hill and Generalized Hill estimators), and parametric estimators (maximum likelihood and L-moments). We discuss the respective interest of the estimators and compare their respective estimates of the shape parameter of the probability distribution of the peaks. We emphasize the influence of the selected number of the highest observations that are used in the estimation procedure and in this respect the particular interest of the semi-parametric estimators. Nevertheless, the various estimators agree on the prevalence of heavy tails and we point out some links between their presence and hydrological and climatic conditions.