Prediction of hydraulic conductivity for soil–bentonite mixture

Owing to its low hydraulic conductivity, soil and bentonite mixture is applied as a liner material. However, the experimental determination of hydraulic conductivity, which is controlled by various physical, chemical and mineralogical factors, requires an expensive and time-consuming setup. In the present work, multigene symbolic, genetic programming was used to model functional relationships for hydraulic conductivity. The developed model was able to generalize highly nonlinear variations in data as well as predict system behavior from experimental observations. It was found that the predictions obtained from developed model agree well with experimental observations.     

Derivation of the Chortis and Chiapas blocks from the western Gulf of Mexico in the latest Cretaceous–Cenozoic: the Pirate model

Currently, two basic models describe the genesis of the Caribbean Plate: (i) a Pacific model that derives the Caribbean Plate off southern Mexico and (ii) an in situ model. The Pacific model requires the 1100–1400 km sinistral displacement recorded across the Cayman Trough to pass through the Gulf of Tehuantepec into the Middle America Trench, but no evidence of such a connection exists. The in situ model is inconsistent with the 1100–1400 km displacement across the Cayman Trough. A way through this impasse is indicated by the northwestward curvature of active oblique reverse to sinistral transcurrent faulting in southeast Mexico. Extending this potential solution back to ca. 80 Ma forms the basis of the new Pirate model, in which the Caribbean Plate and the Chortis and Chiapas blocks are derived from the northwest by anticlockwise rotation during the latest Cretaceous and Cenozoic. Following passage of the Chortis Block, the northern and southern parts of the Yucatan block collided along the intra-Yucatan suture, producing the 11–9 Ma Chiapas fold-and-thrust belt. The Pirate model accounts for the N-trending segment of the Laramide Sierra Madre Oriental–Zongolica foldbelts by anticlockwise drag, Palaeogene palaeocanyons, the second, 66–40 Ma phase of rifting in the western Gulf of Mexico, and post-10 Ma extension in the Chortis Block (Chortis–Sula rift province). Impingement of the East Pacific Rise on the Middle America Trench led to modification of the Pirate model involving subduction erosion of the ～200 km-wide, Eocene–Oligocene forearc at ca. 25 Ma, opening of the Gulf of California at ca. 6 Ma, and birth and ESE movement of the Southern Mexico block (<5 Ma) followed by its fragmentation. The Pirate mechanism indicates that the North American Plate is relatively weak and so tears and rotates into the trailing edge of the Caribbean Plate.     

Roman Law and political control — from a primitive society to the dawn of the Modern World

The purpose of this paper is to survey the history of Roman Law in order to shed light upon processes whereby society may grow more dynamic. Roman Law is the only one whose development can be traced for over thousand years, a time during which two main epochal crises brought about far-reaching changes to Roman society. The first was a consequence of the second Carthaginian war (218-200 BC), when the raw inhabitants of Latium, in a mere space of sixty years, attained supremacy over the ancient world. The second followed closely upon the death of Emperor Alexander Severus (235 AD), when the growing strength of alien populations was becoming a serious threat to the Empire.These two historical watersheds mark three different ages and three correspondingly quite different law systems that can be named: (i) the Quiritarian or strictly Roman Law, (ii) the Universal-Roman Law, (iii) the Greek-Roman Law. The legal sytem of the first epoch was suitable to a narrow rural society. The law system of the second age was suitable to the ends and values of an open civilised society. The last stage of Roman Law unfolded in the Eastern Empire, and the well-known Code of Emperor Justinian (527–29) marked the climax of this process.As a result of cautious reforms lasting several centuries, the political structures of primitive Roman society(familiae, gentes, tribus) declined, a powerful central authority was built, the nuclear family became the basic building block of society displacing extended family and clan structures, the condition of women was freed from obnoxious tutelage.Traditionally, the Roman estate of thefamilia was nearly a territorial State. Primitive buildings, often mere huts, were independent from each other. The drive to an increasingly civilised urbanisation inevitably brought about a closer spatial integration of the built-up area, and therefore made it necessary the establishment of more and more frequent praedial servitudes. To allow the organisation of urban space to emerge, the builder had to be granted a right to hold the building thus erected, for a limited time or in perpetuity, by lease or sale, against the territorial pretence of extended family or clan authority. Usucaption, pledges, mortgages, initially used in provincial lands, replaced the traditional Roman land transfer procedure(fiducia). In the time of the late Empire, slavery declined and was to some extent replaced by serfdom(colonatus). Roman citizenship was granted to all (212 AD), but the commoners(humiliores) suffered under heavy disabilities. Powerful families(honestiores) often retreated to the countryside, while the rest of the urban population was left to her own devices under an oppressive taxation system. Many luckless heads of families had to become tax proctors: they were held responsible for the gathering of taxes to the extent of their whole estate, and even on pain of torture. The State increasingly took control over most features of social and economic activity, from agriculture to the prices of foodstuffs; while individual enterprise, progress and creativity became more and more stagnant. All these are indicators of an increasingly static society. Oriental despotism became the dominant form of political organisation.Thus, while private law became more and more modernised, paving the way to the present legal systems, the social structure and the spatial organisation became more rigid and less open to innovation. Therefore a very incomplete modernisation occurred. The emergence of more open and dynamic societies was to take place many centuries after the fall of the Western Empire, precisely in the same geographical space that had belonged to it, mainly under the impulse of the more efficient and civilised among the new (Germanic) peoples (Angles, Saxons, Jutes, Franks, Longobards, etc.) who immigrated there with theVölkerwanderung and injected fresh blood into the lands of the former Western Empire, thereby ending oriental despotism. The heritage left by the evolution of Roman Law, however, was to be felt and assimilated by these peoples: it was to become a considerable part of their own cultural and legal heritage, and one of the many factors paving the way to the eventual emergence of dynamic Western societies.The age-long process of change of Roman Law can provide useful glimpses on how attitudes and cultural values not hostile to development may arise and grow to full maturity. Its study can help — though by no means alone — to understand how that part of Europe which came under its direct influence was able to achieve cultural traits open to socio-economic innovations and development.Though each social and spatial system follows its own distinctive path to development (or stagnation), some necessary cultural preconditions are broadly similar for any society. Stress upon individual values is doubtless one such inescapable precondition to the emergence of a dynamic society capable of endogenous development. Unfortunately, utterly opposite values are firmly entrenched in many Third World countries, and social evolution there is, under this viewpoint, exceedingly slow — if any.Centuries had still to elapse for individual values to prevail in Europe after the age of Justinian, and more centuries went by between the triumph of these individual values and the actual take-off stage, which only came about with the industrial revolution. Bearing in mind these facts, the inescapable conclusion arises that the apparent lack of significant cultural change leading towards a dynamic society in many countries must necessarily be a matter of the deepest concern. This is aggravated by other disquieting features of the Third World, such as the propensity to authoritarian regimes — a propensity which in its own turn is closely related to poorly developed individual values.     

The Coulomb–Mohr Law and the Change in the Stress–Strain State of a Landslide Prone Mass

Doklady Earth Sciences - The stresses at the points of the ground mass are determined and distributed according to the Coulomb–Mohr law in the main stresses, under compression conditions. The...     

U–Pb geochronological constraints on the Triassic–Jurassic Ayú Complex,southern Mexico: Derivation from the western margin of Pangea-A

We present LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) U–Pb detrital and igneous zircon data of poly-deformed metamorphic and igneous rocks of the Ayú area, southern Mexico. These rocks were previously inferred to be part of the Late Paleozoic Acatlán Complex, but new age data indicate that they formed in the Mesozoic and should be placed in the newly designated Ayú Complex. The Ayú Complex comprises polydeformed metasedimentary rocks (Chazumba Lithodeme) of a turbidite-like protolith that are intercalated with boudinaged ortho-amphibolites with transitional arc- to MORB tholeiitic geochemistry. In the south, the metasedimentary sequence is affected by a ca. 171 Ma partial melting which formed the Magdalena Migmatite. Migmatization was accompanied by 171–168 Ma intrusions of granodioritic, dioritic, and granitic dikes and sheets as well as pegmatite bodies, which are characterized by inherited zircon populations of ca. 260–290, 320–360, 420–480, 880–990, and 1080–1250 Ma that are also found in the Chazumba Lithodeme. U–Pb (detrital zircon) dating of seven metasedimentary samples from the migmatized and unmigmatized Chazumba Lithodeme yielded youngest detrital zircons and clusters of 192, 198, 214, 250, 266, and 291 Ma, and are interpreted to reflect the Late Triassic–Middle Jurassic deposition of turbiditic rocks. The transitional arc–tholeiitic geochemistry of the Chazumba amphibolites is consistent with turbidite sedimentation in a back-arc environment along a rifted passive margin, close to a contemporaneous magmatic arc. Inferred flattening of the subduction zone led to subduction erosion during the Early–Middle Jurassic and underthrusting of the Chazumba Lithodeme to depths equivalent to amphibolite facies metamorphism. Steepening of the subducting slab and diachronous rifting within the Gulf of Mexico contributed to extensional tectonics recorded on the Mexican mainland and facilitated the tectonic exhumation of the Chazumba Lithodeme by normal faulting along the reactivated Providencia shear zone during the Middle–Late Jurassic. More generally, the documentation of arc-back arc assemblages in the Ayú Complex requires deposition adjacent to a subducting ocean, and thus supports a Pangea-A reconstruction that was synchronous with the breakup of Pangea.     

Application of U-Pb-systems from detrital Zircons for palaeogeographic reconstructions a – case-study from the Rhenohercynian

Abstract

U-Pb. systematics of detrital zircons carry a mineral-specific information summarizing important geologic events during the preelastic slate of the minerals. Comparisons with U/Pb isotope rati of zircons from potential provenances reveal relationships between source areas of the zircons and their final location of deposition in a sedimentary basin. The Palaeozoic zircon detritus accumulated in sedimentary basins on the Rhenohercynian crustal segment is taken as an example to elucidate the plate-tectonical induced changes of the source areas by significant changes of the ²⁰⁶Pb/²³⁸ vs. ²⁰⁷Pb/²³⁵ratios in the zircons.

The U-Pb systematic of detrital zircon- from the Cambrian sediments deposited in the Brabant Massif and in the Ardennes indicale two source areas. Part of the detritus derived from an area. where strong Cadomian-Panafrican events influenced the U-Pb systems of the zircons. The oilier part reflects a source, in which the U-Pb systems were able to preserve their Arehaean to Early Proterozoic age information. Zircons of the latter source record the most ancient ages so far observed in detrital zircons of the later Rhenohercynian crustal seg ment. The similarities with the U/Pb isotope ratios of zircons from the Armorican Massif, the Bohemian Massif. and certain regions of the Mps indicate a geotectonic position of the sedimentar) basin during Cambrian times in the periphery of the Condwana mega-continent.

The detrital zircons accumulated in the Variscan Rhenish basin during the Lower Devonian show a completely different summarizing age information. The majority of the zircons reflect a Laurussian-type origin. which suggests a palaeogeographic position of the Variscan Rhenohercynian basin close to Laurussia. Euhedral zircons crystallized during Caledonian times document the erosion of Caledonian granitoids from structural highs in the Mid European Caledonides.

Zircons of the Lower Carboniferous flysch sediments of todays Eastern Rhenish Massif originate from two source areas characterised by very different geologic histories. Euhedral zircons represent a rather young component of about 410 Ma in the detritus, whereas. in contrast. the well rounded crystals show a summarizing age-information identical to that of the zircons found in the Cambrian sandstones. The low ages resemble intrusion ages as recorded from the Mid-German-Crystalline-Rise, the high age reflect a Gondwana-type input into the Rhenohercynian sedimentary basin during Lower Carboniferous times. The detritus thus documents the Variscan collision and a renewed coherence of the Rhenohercynian crustal segment to Cnndwana.

The zircon population from Upper Carboniferous molasse deposits is comprised of Condwana-tуpc material and of mate rial with similar U/Pb ratios as recorded in the Lower Devonian zircons. In parts the Variscan molasse must have been derived from sediments once deposited in a southern part of the Rhenohercynian basin and in the Saxothurìngian basin. U/Pb ratios of euhedral and round diamond-like lustrous zircons indicate a major geologic event at the Namurian/Westphalian boundary (310-315 Ma). These zircons thus reflect an influx of detritus into the molasse from other source rocks, probably synsedimentary volcanics.     

Character of spatiotemporal variations in the chemical composition of lake water under the influence of emission from copper–nickel plants: Prediction of acidification

In this paper, we analyze the influence of variations in the emission of sulfur dioxide and solid substances by the Pechenganikel and Severonikel copper–nickel plants in Murmansk oblast on the chemical composition of lake water and development of acidification. The dynamics of ~100 lakes examined in 1990, 1995, 2000, 2005, and 2009 and response of the chemical composition of the lake waters on the impact of acidifying substances was explored depending on the magnitude of load (distance from the plants), geologically controlled vulnerability of the lake catchments to acid precipitation, and the size of the lakes. Possible further changes in the sulfate concentration and pH values of lake waters were estimated for scenarios assuming an increase or a decrease in sulfur dioxide emission from the plants. It was shown that, in the zone of maximum and high load, a 20% change in sulfur dioxide emission will result in a mean change in sulfate concentration of ±8 μeq/L (which is comparable with the regional background) and a change in pH value of ±0.1 in acid-sensitive lakes and will have almost no effect on these parameters in lakes insensitive to acid precipitation.     

Theoretical Prediction of Gibbs Free Energies of Formation for Crystalline α-MOOH and α-M2O3 Based on a Linear Free-Energy Relationship

In the present study, the modified Sverjensky–Molling equation, derived from a linear-free energy relationship, is used to predict the Gibbs free energies of formation of crystalline phases of α-MOOH (with a goethite structure) and α-M2O3 (with a hematite structure) from the known thermodynamic properties of the corresponding aqueous trivalent cations (M3+). The modified equation is expressed as ΔG0f,MVX=aMVXΔG0n,M3++bMVX+βMVXγM3+, where the coefficients aMVX, bMVX, and βMVX characterize a particular structural family of MvX (M is a trivalent cation [M3+] and X represents the remainder of the composition of solid); γ3+ is the ionic radius of trivalent cations (M3+); ΔG0f,MVX is the standard Gibbs free energy of formation of MvX; and ΔG0n,M3+ is the non-solvation energy of trivalent cations (M3+). By fitting the equation to the known experimental thermodynamic data, the coefficients for the goethite family (α-MOOH) are aMVX=0.8838, bMVX=?424.4431 (kcal/mol), and βMVX=115 (kcal/mol.?), while the coefficients for the hematite family (α-M2O3) are aMVX=1.7468, bMVX=?814.9573 (kcal/mol), and βMVX=278 (kcal/mol.?). The constrained relationship can be used to predict the standard Gibbs free energies of formation of crystalline phases and fictive phases (i.e. phases that are thermodynamically unstable and do not occur at standard conditions) within the isostructural families of goethite (α-MOOH) and hematite (α-M2O3) if the standard Gibbs free energies of formation of the trivalent cations are known.     

A review of the pressure–temperature–time evolution of the Limpopo Belt: Constraints for a tectonic model

Published literature argues that the Limpopo Belt can be subdivided into three zones, each with a distinctive geological character and tectono-metamorphic fingerprint. There are currently two contrasting schools of thought regarding the tectono-metamorphic evolution of the CZ. One camp argues that geochronological, structural and prograde pressure–temperature (P–T) evidence collectively indicate that the CZ underwent tectono-metamorphism at ca. 2.0 Ga which followed a clockwise P–T evolution during a transpressive orogeny that was initiated by the collision of the Kaapvaal and Zimbabwe cratons. Deformation and metamorphism consistent with this scenario are observed in the southern part of the NMZ but are curiously absent from the whole of the SMZ. The opposing view argues that the peak metamorphism associated with the collision of the Kaapvaal and Zimbabwe cratons occurred at ca. 2.6 Ga and the later metamorphic event is an overprint associated with reactivation along Archean shear zones. Post-peak-metamorphic conditions, which at present cannot be convincingly related to either a ca. 2.6 or 2.0 Ga event in the CZ reveal contrasting retrograde paths implying either near-isothermal decompression and isobaric cooling associated with a ‘pop-up’ style of exhumation or steady decompression–cooling linked to exhumation controlled by erosion. Recent data argue that the prograde evolution of the ca. 2.0 Ga event is characterised by isobaric heating prior to decompression–cooling. Contrasting P–T paths indicate that either different units exist within the CZ that underwent different P–T evolutions or that some P–T work is erroneous due to the application of equilibrium thermobarometry to mineral assemblages that are not in equilibrium. The morphology of the P–T path(s) for the ca. 2.6–2.52 Ga event are also a matter of dispute. Some workers have postulated an anticlockwise P–T evolution during this period whilst others regard this metamorphic event as following a clockwise evolution. Granitoid magmatism is broadly contemporaneous in all three zones at ca. 2.7–2.5 suggesting a possible causal geodynamic link. P–T contrasts between and within the respective zones prevent, at present, the construction of a coherent and inter-related tectonic model that can account for all of the available evidence. Detailed and fully-integrated petrological and geochronological studies are required to produce reliable P–T–t paths that may resolve some of these pertinent issues.     

Experiment and Pitzer Model Prediction for the Solid + Liquid Equilibria of the Ternary System LiCl–CaCl2–H2O

正1 Introduction Lithium resources are widely distributed in the oilfield brine from the Nanyishan district in the Qaidam Basin(Fan et al.,2007).The investigation of the thermodynamics and phase diagram of the brine system is valuable in providing the theoretic foundation and scientific guidance in the comprehensive exploitation of the mixture salts effectively.Comprehensive     

Experimental Assessment of the Stress–Strain Behaviour of Leighton Buzzard Sand for the Calibration of a Constitutive Model

A number of constitutive models are nowadays implemented in numerical codes which simulate the stress–strain behaviour of soil from very small to large strain. In this paper, the mechanical behaviour of Leighton Buzzard sand (grade E), used worldwide for physical modelling, has been thoroughly characterized by laboratory testing along several stress paths. Tests were aimed at calibrating a constitutive model, that allows considering stiffness nonlinearities in a wide range of strains, in the framework of isotropically hardening plasticity. As a validation, the results of dynamic centrifuge tests on a layer of the same sand were compared with finite element predictions.     

The large-wavelength deformations of the lithosphere： materials for a history of the evolution of thought from the earliest times to plate tectonics

The notable authority on tectonics and the history of geosciences, Professor Celal Sengor from Istanbul, has produced another remarkable book-which, as he tells the reader, grew rapidly from an initial paper into a massive tome. Just as Georges Cuvier liked the idea of ‘bursting the limits of time‘, so Professor Sengor has again ‘burst the limits of a paper‘!     

Oxides of the Pyrochlore Supergroup from a Nonsulfide Endogenic Assemblage of Pb–Zn–Sb–As Minerals in the Pelagonian Massif,Macedonia

Geology of Ore Deposits - The specific features of the chemical composition, isomorphism, and zoning have been studied for pyrochlore supergroup minerals (PSM) from metasomatic rocks of ore...     

Recognition of an Elastic–Plastic Constitutive Law by a Multiobjective Evolutionary Algorithm

This study presents the recognition of an elastic–plastic constitutive law by a multiobjective evolutionary algorithm (MOEA). This idea is illustrated by the identification of ellipse aspect ratio and plastic modulus of a reported bounding surface model. Based on the multi-goals of well predicting all available drained or undrained stress–strain behaviors simultaneously, the compromising solutions of these two parameters are found by a strength Pareto evolutionary algorithm 2 (SPEA2). Their fittest values are then determined by additionally introducing the Akaike information criterion. Experimental data for the Ottawa sand are used to test such processes. The results show that an MOEA is an efficient and automatic tool to identify the fittest form of an elastic–plastic constitutive law from a large amount of experimental data. However, sufficient data are required to determine the correct searching range of parameters to be identified.     

Particle size composition of Holocene–Pleistocene deposits of the Laptev Sea (Buor-Khaya Bay)

New data on the particle size composition of the Laptev Sea shelf deposits were obtained on the basis of results of low-angle laser light-scattering of core samples from the columns studied. It was revealed that the sand fraction dominates. The results of comparative analysis of the particle size composition of deposits show that the Laptev Sea shelf zone was characterized by highly variable spatial–temporal conditions and settings of sedimentation in the Quaternary, a polygenic character of deposits, and a pulsating influence of fluvial and slope processes on the conditions of sedimentation. A tendency of coarsening in the vertical sequence that contributes to thawing of the permafrost was revealed in the Ivashkina lagoon.     

Prediction of underground cavity roof collapse using the Hoek–Brown failure criterion

Preventing roof collapse in underground cavities is a challenge to geotechnical engineering. In this study, three independent methods have been used to evaluate the roof collapse of underground rectangular cavities for a range of geometries and rock properties. The rock mass strength has been described by the Hoek–Brown failure criterion. The results of the analysis allow for prediction of roof collapse and to determine whether the failure surface that develops in the rock mass remains localised or extends through the full depth of cover. This is of significance if there are overlying cavities and when estimating surface subsidence.     

Subrecent spore–pollen spectra from the Lower Kolyma River basin and their importance for the reconstruction of the Quaternary paleogeography of the region

Spore–pollen spectra of surface samples characterizing different plant associations in the Lower Kolyma River basin are studied. The formation features of the studied spore–pollen spectra are determined, as well as their potential for past vegetation reconstruction, paleogeographic constructions, and stratigraphic correlation of Quaternary deposits in Northeastern Russia.     

GMM—a gas monitoring module for long-term detection of methane leakage from the seafloor

A new seafloor lander module, the Gas Monitoring Module (GMM), has been developed for continuous and long-term measurements of methane concentration in seawater at the benthic boundary layer, as a result of marine environmental geology and technology synergy. The module is designed to host a series of sensors controlled and managed by a data acquisition and control system able to perform first-level data quality checks. The prototype includes semiconductor methane sensors, an H₂S sensor and a CTD for temperature, salinity, pressure recording, as well as interfaces for additional sensors. The GMM can be linked to submarine cables for real-time data transmission to onshore operators and is suitable for long-term monitoring of natural gas emissions from seafloor or leakages from pipelines and boreholes.     

Some Effects of Shearing Velocity on the Shear Stress-Deformation Behaviour of Hard–Soft Artificial Material Interfaces

Shear behaviour of the joints formed by the interface of two different material types, such as rock and cemented paste backfill, rock and concrete or two different rock types, have practical importance in many rock engineering activities. This paper presents the results of an experimental investigation into the shear behaviour of these special joints under pseudo-static shear velocity. Direct shear tests on concrete–plaster interfaces were carried out under boundary conditions of constant normal load and constant normal stiffness. Shearing velocities of the performed tests were in the range of 0.3–30 mm/min. The results of the shear tests conducted on the planar and rough artificial prepared joints showed that the shearing velocity has a significant influence on the shear strength, friction angle and shear stiffness of the hard–soft material interface. So that, these parameters were decreased when shear velocity was increased. Also, comparison of the tests results that performed on the concrete–plaster joints with those from tests on the plaster–plaster and concrete–concrete interfaces showed that the shear behaviour of concrete–plaster interface is governed mainly by the shear parameters of the plaster block (namely softer material).