A Preliminary Study on Paleomagnetism and Rock Magnetism of Eclogite from the Maobei Area

A preliminary study of paleomagnetism and rock magnetism has been done on 55 eclogite samples collected from the Chinese Continental Scientific Drilling (CCSD) site at the Maobei (毛北) area, Donghai (东海) County, Jiangsu (江苏) Province. Also the isothermal remanence, hysteresis loop, magnetic fabric, thermal susceptibility were measured, and analyses were made by electron-probe and scanning electric microscope on some samples synchronously. The result indicates that there are two groups of stable remanence, the normal and reversed magnetization. The remanence orientations are: D=94.3o, I=-29.1o and D=273.7o, I=15.4o, respectively. The magnetization intensity and the density of the samples which carry the normal magnetization are very different from those bearing reversed magnetization. The magnetic anisotropy is weak, and the minimum axis is hardly determined. The isothermal remanence and the hysteresis loop show that the magnetic carriers of the eclogite are likely SD (single domain) and PSD (pseudo-single domain) magnetite. According to the magnetic property, the cause of formation of magnetic carriers, the mechanism of the remanence, and the significance for the tectonics are discussed.     

Study on the Safety of the Rock Mass in the Tongling Bank of Taipinghu Bridge

The Taipinghu Bridge is an important engineering construction, and the safety of rock mass of its foundation is very crucial. This article adopts FLAC 3D to analysis the geologic model. The simulating process shows that no mater the excavating process or the loading process the rock mass are safe. The modeling and analyzing process can be used for reference.     

A Study of Iron Deposits in the Jining Area based on Correlation Analysis Gravity and Magnetic Anomalies

Please?refer?to?the?attachment(s)?for?more?details.     

A Thermodynamic Model of the Water–Rock Interaction under Hydrothermal Exposure of the Bazhenov Formation

Thermodynamic modeling of the hydrothermal exposure of the rocks of the Bazhenov Formation resulted in revealing the equilibrium mineral associations at 50–350°C and the pressure of saturated water vapor. The calculation results show that mineral parageneses varied slightly with the increase of temperature. Thus, zeolites were characterized by the stilbite–laumontite–wairakite series; kaolinite, pyrite, dolomite, and brannerite were replaced by montmorillonite and/or albite, pyrrhotite, calcite, and uraninite, respectively. The modeling results were confirmed in experiments.     

Study on the Safety of the Foundation Rock Masses in the Tangkou Bank of the Taipinghu Bridge

The Taipinghu Bridge is an important project, and the safety of rock masses of its foundation is very crucial. This article analyzes the potential causes of the deformation of the rock masses of the bridge foundation, and uses the Fast Lagrangian Analysis of Continua to analyze the geologic model. The simulating process shows that no mater in the excavating process or in the loading process the rock masses are suit for the engineering. The modeling and analyzing process can be used for reference.     

Study on the Safety of the Rock Mass in the Tongling Bank of Taipinghu Bridge

The Taipinghu Bridge is an important engineering construction，and the safety of rock mass of its foundation is very crucial．This article adopts FLAC3D to analysis the geologic model．The simulating process shows that no mater the excavating process or the loading process the rock mass are safe．The modeling and analyzing process can be used for reference．     

Study on the Safety of the Foundation Rock Masses in the Tangkou Bank of the Taipinghu Bridge

The Taipinghu Bridge is an important project，and the safety of rock masses of its foundation is very crucial．This article analyzes the potential causes of the deformation of the rock masses of the bridge foundation，and uses the Fast Lagrangian Analysis of Continua to analyze the geologic model． The simulating process shows that no mater in the excavating process or in the loading process the rock masses are suit for the engineering．The modeling and analyzing process can be used for reference．     

Deterministic and Probabilistic Stability Analysis of Soil Slope – A Case Study

This paper deals with the soil slope stability analysis along the road section (National Highway-05) near Luhri area, Himachal Pradesh, India. The area constantly experiences local as well as regional slides which enhances the siltation, reduce carrying capacity of the Sutlej river with time and further increases the water level on the banks of the slope. High traffic congestion puts the area at high risk zone and therefore, stability analysis was done using probabilistic as well as deterministic approach under static conditions through limit equilibrium method (LEM) and finite element method (FEM). FEM was used for stability analysis, mainly to obtain deformational characteristics, under static conditions and compared with LEM results. The results of both the methods help in identifying the zones of vulnerability in the case study. Further, the values of safety factor obtained from both the methods are in close approximation. The study also reveals that the slope is critically stable and a remedial measure has been suggested by modifying the geometry of the slope, which needs proper protection from any external factors like rainfall and earthquakes that may cause unforeseeable circumstances.     

Stratigraphic Division and Correlation of the Nihewan Beds by Multivariate Statistical Analysis

Described in paper is the principle of optimal partitioning method for stratigraphic division and correlation.The Nihewan Beds are taken for example to show how to apply this approach in stratigraphic division and correlation.The semiquantitative spectral analysis data on aggregate trace elements in 324 samples taken from the nine sections in the Nihewan Basin are treated with multivariate statistical method for stratigraphic division and correlation.First ,the data from all the sections are respectively calculated by the optimal partitioning method to establish the stratigraphic boundaries.The optimal partitioning method has proved itself to be applicable to stratigraphic division and correlation. In our practice the Nihewan Beds are divided into five zones (I-V).Zone I includes subzones Ia and Ib,Zones Ia,Ib,II and III are considered to be corresponding to the Pliocene(N2),the early Early Pleistocene,the late Early Pleistocene,and the Middle Pleistocene,respectively .Zones IV and V are probably Late Pleistocene in age.This indicated that sediments deposited con-temporaneous in the sections of the same basin are similar in geochemical characteristics,although dif-ferent in geographical location.However,the sediments also show some variations ,with a transitional relationship from one section to another .For example ,in Zone II,the sediments of the Xiaodukou section show not only the characteristics of the Nangou-Hongya and Hutouliang sections,but also those of the Xiashagou,Shixiaxi,Shixiadong and Wulitai sections.It can be seen from the above that the zones can be characteristically correlated with one another.In addition the feasibility of the optimal partitioning method is also described in the present paper.     

Experimental Study on the Leaching of Gold from Greenstone

Experiments were conducted on the leaching of gold from greenstone by chloride solution under the temperature of 200—550℃ and the pressure of 60 MPa. During part of the experiments, the oxygen fugacity was controlled. The results show that the leaching rate of gold is related to temperature, composition of the solution, pH and oxygen fugacity. In the experiment with oxidative acidic solution, the leaching rate was up to 50％ or more. It is known that the leaching of gold is restricted by the reaction in which the gold is dissolved from the rock to form gold chloride complex. Therefore, the authors hold that the acidic chloride solution derived from granite magma has caused the remobilization-migration of gold from greenstone and its enrichment into ore.     

Sandbox Experimental Study on the Influence of Rock Strength and Gravity on Formation of Thrusts

INTRODUCTIONRock deformation is normally explained by tec-tonic stress as rock deformation results fromthe tec-tonic stress field. The classic tools that explainedfracture mechanisms were the Coulomb shear fracturerule and the Anderson mode derived fromit (Zhu,1999) . More and more studies have shown that it isdifficult to explain rock deformation in a large strainrange using only the Coulomb shear fracture rule( Waltham,2002 ; Gutscher et al .,2001 ; Tikoff andWojtal ,1999) . As a ver…     

Rock slope stability assessment using finite element based modelling – examples from the Indian Himalayas

Numerical modelling of rock slides is a versatile approach to understand the failure mechanism and the dynamics of rock slopes. Finite element slope stability analysis of three rock slopes in Garhwal Himalaya, India has been carried out using a two dimensional plane strain approach. Two different modelling techniques have been attempted for this study. Firstly, the slope is represented as a continuum in which the effect of discontinuities is considered by reducing the properties and strength of intact rock to those of rock mass. The equivalent Mohr-Coulomb shear strength parameters of generalised Hoek-Brown (GHB) criterion and modified Mohr-Coulomb (MMC) criterion has been used for this continuum approach. Secondly, a combined continuum-interface numerical method has been attempted in which the discontinuities are represented as interface elements in between the rock walls. Two different joint shear strength models such as Barton-Bandis and Patton’s model are used for the interface elements. Shear strength reduction (SSR) analysis has been carried out using a finite element formulation provided in the PHASE². For blocky or very blocky rock mass structure combined continuum-interface model is found to be the most suitable one, as this model is capable of simulating the actual field scenario.     

A GIS and Remote Sensing-based Analysis of Land Use Change Using the Asymmetric Relation Analysis Method: A Case Study from the City of Hangzhou,China

Urbanization has been an important component of land use and land cover change. Quantifying land use patterns and their changes is essential for monitoring and assessing the impact of urbanization. Data on existing and changing land use provide crucial clues for future development. Combining the application of remote sensing with geographic information systems (GIS) data, this study accomplishes (i) the creation of time-series land use maps in the core urban area of the city of Hangzhou, China; (ii) the examination of the land use cross-tabulation matrix to assess the transitions between land use types; and (iii) the introduction of a new asymmetric relation analysis method to explore the dependency relationship of different times in land use. The investigation was based on a 12-year time series dataset (1990–2002), compiled from fine-resolution satellite imagery and GIS-based maps. The results of the study showed that, first, there are strong associations between different stages (1990, 1996, and 2002) in land use development, and, secondly, the dependency between land use states was asymmetric in both stages of development. In addition, urbanization in Hangzhou has resulted in notable increases in the surface area of urban land and sharp decreases in the surface area of cropland.     

A Study on the Middle Upper Proterozoic and Lower Palaeozoic Source Rock from the Huabei Area in China

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Mineral Composition of Loess—Paleosol Samples from the Loess Plateau of China and Its Environmental Significance

34samples of loess-paleosol from the Luochuan and Xifeng sections in the Loess Plateau,northern China were eparated into sand,silt and clay fractions and analyzed for their mineral compositions.The results indicate that there is almost no difference between loess and paleosol in mineral composition.Major mineral species are quartz,mica,feldspar and chlorite,accounting for about 88-92% of the total;other minerals are kandite,smectite,vermiculite and a few heavy minerals.The calcite,magnetite and hematite were not taken into consideration because of their removal in the process of sample preparation.The main difference with respect to the mineral composition of samples collected from different sections and different statigraphic levels lies in the amount and grain size of minerals hosted.Comparisons between the Luochuan section and the Xifeng section,between paleosol and loess and between the upper part and the lower part of some paleosol layers show that the formers contain less feldspar but more mica and vermiculite and are finer in grain size,indicating the co-occurrence of both biochemical weathering process responsible for mineral change and physical weathering process leading to grain-size change during the soil-forming processes.This result favours such an explanation of the soil-forming mechanism that loess deposition and paleosol development occurred synchronously,though the rate of soil formation was greater than that of loess deposition,thus leading to soil development.     

Erratum to: “Study of Changes in the Physiological State of Cyanobacteria Caused by Weak Ultrasonic Treatment”

Doklady Earth Sciences - The surname of the second author should read Grigoryeva     

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.