Mineral characteristics and their geological significance of black shales in southeastern Ordos Basin by X-ray diffraction analysis

X-ray diffraction analysis of black shale of Upper Triassic Member Chang 7 of the Yanchang Formation in southeastern Ordos Basin showed that black shales were deposited in brackish, strongly reducing, semi-deep-deep lacustrine facies, and mainly composed of quartz, feldspar, carbonate （dolomite）, clay minerals （illite and il- lite/smectite） and a certain amount of pyrite. The mineral composition characteristics of this set of black shales are similar to those of highly productive shale gas in North America, for example shallow burial, low clay mineral and abundant brittle mineral, so the strata are conducive to the development of cracks and fractures. Thus, this area is favorable for shale oil/gas exploration and development.     

Deep-penetrating geochemistry of the Tuwu copper deposit, northwestern China

Desert terrains in northern China are covered by widespread regolith sediments which mask geochemical signals from ore bodies and are major obstacles to mineral exploration. There is a critical need to study the vertical distribution of elements in this regolith and to establish optimum sampling and analytical methods. The aim of this study is to understand the dispersion and variation of elements throughout the cover in a vertical profile. The results demonstrate that the main elements show a distribution pattern of enrichment in clay layers in the vertical profile, i.e., most elements tend to be enriched in the most upper part of the profile above the orebodies except for some elements like Cu, Ca and Ag. Meanwhile, both fine (-160 mesh) and coarse (+20 mesh) fraction samples from clay-rich horizons are favorable samples and selective leaching of the elements absorbed on clays or oxide coatings is effective for localizing buried deposits. The distribution of active Cu and Mo is quite different because chalcopyrite is weathered into Cu sulfate and CuCO3, and is precipitated in alkaline environments in a layer below close to the surface. Mo is soluble in the alkaline environment so it can penetrate the caliche layer and be enriched on the surface of soil enriched with weakly cemented clay.     

Distribution of Palygorskite in the Lingtai Profile of Chinese Loess Plateau： Its Paleoclimatic Implications

Palygorskite is a typical indicator mineral of the arid and strong evaporation environment. Distribution of palygorskite in loess-red clay sequences may act as an important indicator for reconstruction of the paleoenvironment and paleoclimate.In this paper,field emission scanning electron microscope and high-resolution transmission electron microscope observations on the red clay-loess-paleosol of the Renjiapo profile at Lingtai,Gansu Province indicate that palygorskite occurs widely in red clay sequences formed before 3.6 Ma,but no occurrence has been found in eolian sediments since 3.2 Ma.Micromorphological features and microstructure of palygorskite show that it is an autogenic mineral formed during pedogenesis,and transformed from illite-montmorillonite under the pore water action.In the Lingtai profile,the disappearance horizon of palygorskite is consistent with those of increasing magnetic susceptibility,dust flux and depositional rate.The distribution of palygorskite in the profile indicates that the interval of around 3.6 Ma was an important transformation period of the East Asian paleomonsoon,when changes took place in the East Asia paleoclimate pattern,i.e.a high-frequency strong fluctuation alternative evolution of the environment. Therefore,palygorskite is a key indicator mineral of the East Asian paleomonsoon evolution of that time.     

Distribution of Palygorskite in the Lingtai Profile of Chinese Loess Plateau: Its Paleoclimatic Implications

Palygorskite is a typical indicator mineral of the arid and strong evaporation environment. Distribution of palygorskite in loess-red clay sequences may act as an important indicator for reconstruction of the paleoenvironment and paleoclimate. In this paper, field emission scanning electron microscope and high-resolution transmission electron microscope observations on the red clay-loess-paleosol of the Renjiapo profile at Lingtai, Gansu Province indicate that palygorskite occurs widely in red clay sequences formed before 3.6 Ma, but no occurrence has been found in eolian sediments since 3.2 Ma. Micromorphological features and microstructure of palygorskite show that it is an autogenic mineral formed during pedogenesis, and transformed from iilite-montmorilionite under the pore water action. In the Lingtai profile, the disappearance horizon of palygorskite is consistent with those of increasing magnetic susceptibility, dust flux and depositional rate. The distribution of palygorskite in the profile indicates that the interval of around 3.6 Ma was an important transformation period of the East Asian paleomonsoon, when changes took place in the East Asia paleoclimate pattern, i.e. a high-frequency strong fluctuation alternative evolution of the environment. Therefore, palygorskite is a key indicator mineral of the East Asian paleomonsoon evolution of that time.     

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.     

Diatomaceous deposits of Fayium, Egypt; characterization and evaluation for industrial application

The Holocene lacustrine diatomaceous earth of Fayium,South West of Cairo,has been studied to define its minerals,chemistry,petrography and physical properties.Minerals were processed by way of calcination at 550℃ ,followed by acid leaching to reduce levels of mineral impurities.The diatomite is of biogenic opal A.with calcite as the main ganue mineral,quartz and clay minerals(smectite followed by kaolinite in abundance and a trace amount of illite).Silica in the diatomaceous earth accounts for about 63% on average.Positive correlation between CaO and CO2 indicates that Ca is present mainly as calcite.Al2O3,Fe2O3,MgO and K2O are attributed mainly to clay minerals.However,the physical properties of the diatomaceous earth as filter-aids and filler for paints and plastics are poor because of general high levels of impurities.The technological performances of the diatomaceous earth have been significantly improved owing to upgrading of diatoms through mineral processing trical.     

Geochemical characteristics of trace elements in sediments of Dongting Lake, central China

Although eutrophication and trace element contamination are two key environmental problems in Dongting Lake, a systematic study of the distribution of trace elements in sediments of this lake has not previously been undertaken. In order to identify the current levels of trace metal contamination in Dongting Lake, the concentrations of trace elements （Cd, Cr Cu, Ni, Pb, Zn, As and Hg） in the sediments at 53 locations were investigated in this study. The lake, the second largest fresh-water lake in China, boasts three China wetlands of international importance. Dongting Lake which lies in the south of the middle Yangtze River is the most important reservoir lake in the Yangtze River drainage area, and is characterized by fast flow-through water, large runoff volume and short period of exchanging water （no more than 20 days）. The granulometric analysis result of sediments shows that a large proportion of the sediments measures at 2-63 μm in size; the result of mineralogical analysis shows that original mineral is the main composition of the sediments, followed by clay mineral and carbonate. The contents of copper, lead, zinc, cadmium, arsenic and mercury are higher than the background levels of soil （ Ⅰ Soil） in China, but lower than the threshold values for severely polluted soil （Ⅲ Soil） in China except Cd higher than that in Ⅲ Soil. The concentrations of trace elements analyzed are higher than the Threshold Effect Level of Interim Sediment Quality Guideline by Canada EPA and are lower than the Probable Effect Level. The assessment by geoaccumulation index shows that the contamination of Cd reached strong level in Dongting Lake. Study on speciation of metals by a BCR procedure indicates that the trace elements （Cu, Zn, Cr, and Ni） analyzed are mainly distributed in residual phases but Pb in Fe/Mn oxhydroxide phase and Cd in soluble and carbonate-bound fraction. The potential risk was the highest in East Dongting Lake based on the calculated contamination factors which are mostly probably caused by the deposition of the trace element pollutants via the Xiangjiang River and the discharge of the pollution sources in the vicinity of East Dongting Lake.     

Characterization of a Lacustrine Shale Reservoir and the Evolution of its Nanopores: A Case Study of the Upper Cretaceous Qingshankou Formation in the Songliao Basin,Northeastern China

The Songliao Basin is one of the most important petroliferous basins in northern China. With a recent gradual decline in conventional oil production in the basin, the exploration and development of unconventional resources are becoming increasingly urgent. The Qingshankou Formation consists of typical Upper Cretaceous continental strata, and represents a promising and practical replacement resource for shale oil in the Songliao Basin. Previous studies have shown that low-mature to mature Qingshankou shale mainly preserves type Ⅰ and type Ⅱ1 organic matter, with relatively high total organic carbon(TOC) content. It is estimated that there is a great potential to explore for shale oil resources in the Qingshankou Formation in this basin. However, not enough systematic research has been conducted on pore characteristics and their main controlling factors in this lacustrine shale reservoir. In this study, 19 Qingshankou shales from two wells drilled in the study area were tested and analyzed for mineral composition, pore distribution and feature evolution using Xray diffraction(XRD), scanning electron microscopy(SEM), low-pressure nitrogen gas adsorption(N2-GA), and thermal simulation experiments. The XRD results show that clay, quartz, and feldspar are the dominant mineral constituents of Qingshankou shale. The clay minerals are mostly illite/smectite mixed layers with a mean content of 83.5%, followed by illite, chlorite, and kaolinite. There are abundant deposits of clay-rich shale in the Qingshankou Formation in the study area, within which many mineral and organic matter pores were observed using SEM. Mineral pores contribute the most to shale porosity;specifically, clay mineral pores and carbonate pores comprise most of the mineral pores in the shale. Among the three types of organic matter pores, type B is more dominant the other two. Pores with diameters greater than 10 nm supply the main pore volume;most are half-open slits and wedge-shaped pores. The total pore volume had no obvious linear relationship with TOC content, but had some degree of positive correlation with the content of quartz + feldspar and clay minerals respectively. However, it was negatively correlated with carbonate mineral content. The specific surface area of the pores is negatively related to TOC content, average pore diameter, and carbonate mineral content. Moreover, it had a somewhat positive correlation with clay mineral content and no clear linear relationship with the content of quartz + feldspar. With increases in maturity, there was also an increase in the number of carbonate mineral dissolution pores and organic matter pores, average pore diameter, and pore volume, whereas there was a decrease in specific surface area of the pores. Generally, the Qingshankou shale is at a low-mature to mature stage with a TOC content of more than 1.0%, and could be as thick as 250 m in the study area. Pores with diameters of more than 10 nm are well-developed in the shale. This research illustrates that there are favorable conditions for shale oil occurrence and enrichment in the Qingshankou shale in the study area.     

Sorption of phenanthrene on the complexes of kaolinite and different organic component

Sorption of hydrophobic organic chemicals by various components influences their behavior and fate in environment. In the natural environment, mineral components, organic matter and microorganism didn＇t exist alone. They combined or reacted one another and formed the mineral-humic, mineral-microorganic and mineral- humic- microorganic complexes. A clear understanding of the sorption of organic chemicals by the complexes of mineral and humic acid and/or microorganism will help to determine their sorptive mechanisms in environment. In this paper, the sorption patterns of phenanthrene on the complexes of kaolinite and different organic component （humic acid and microorganism） have been carried on. The results show that the combination of HA and kaolinite not only changed the structure of HA, but also modified the surface chemistry of clay mineral. Interaction between HA and kaolinite is presumably ascribable to coulombic interactions and ligand exchange between the -COOH groups of HA and OH groups at the kaolinite surface. During the sorption on mineral surface, aliphatic fractions of HA were preferentially sored by kaolinite while aromatic fractions were left in the solution. More linear isotherms and higher Koc values were observed for kaolinite-HA complex in comparison of the pure HA. The sorption capacity of kaolinite-HA complex increased with increasing ionic strength and pH, and showed more nonlinear character. Kaolinite, microorganism and kaolinite-microorganism complex can all sorb phenanthrene, but the sorption capacity significantly differed. Bacterial cell sorbed more phenanthrene than kaolinite. The biofllm coating of kaolinite affected its sorption to phenanthrene. Kaolinite with biolfilm coating sorbed more phenanthrene than that without biofilm coating. The sorption capacity of kaolinite-microorganism complex decreased with increasing ionic strength and decreasing pH, but showed more nonlinear character. Both HA and microorganism can alter the nature of kaolinite sorbing phenanthrene respectively.     

一个秃冻胀丘的热及水文动力学--关于其形成的暗示

Mud boils, classified as non-sorted circles, are a common patterned ground phenomenon of permafrost areas. They typically consist of a bare circle center of cryoturbated soil and are surrounded by vegetation on more stable soil. The objectives are to examine differences in seasonal hydrologic and thermal dynamic across this gradient of cryoturbation, i.e. the region below the organic border and the mud center. We installed instruments in a mud boil at a site close to Ny-@lesund, Spitsbergen, in September 1998. The bare soil circle center ranges about 1 m in diameter and is surrounded by a vegetated border consisting of a mixture of low vascular plants, mosses and lichens. Fine soil (>95% clay and silt) in the lower part of the profile is overlain by coarser grained material (silt and sand). The grain size distribution also suggests an upwelling of fine material in the center of the circle. Temperature and moisture sensors were installed over a vertical 1 m×1 m profile and hourly data recording started in September 1998. Surface irregularities, as well as variations of grain size and moisture, create a non-uniform thermal and hydrologic dynamic. We qualitatively analyze this dynamic with respect to the mud boils physical stability.     

Sedimentary Environment and Mineralization of the Black Shale Polymetallic Layer in the Early Cambrian, SW China: Constraints from in situ LA-ICP-MS Analysis of Pyrite

A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province. The mineral that makes up the polymetallic layer is related to the sedimentary facies. To analyze the differentiation mechanism between polymetallic deposits (Ni-Mo and V), the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of pyrite. The results show that δ34S values of pyrite vary widely from ?7.8 ‰ to 28 ‰ in the Gezhongwu profile, while the δ34S values are relatively uniform (from 27.8 ‰ to 38.4 ‰) in the Haishan profile. The isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive Yangtze platform; this indicates that the δ34SO42? values in seawater must be differently distributed in depositional environments. The sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid, while the V layer mainly originates from seawater. Overall, the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid.     

Compositions, Proportions, and Equilibrium Temperature of Coexisting Two-feldspar in Crystalline Rocks

Compositions, proportions, and equilibrium temperature of coexisting two-feldspar in crystalline rocks are of great importance to classification in petrography and interpretation of petrogenesis. Crystalline rocks are usually composed of 4-6 minerals (phases), depending on their independent chemical components and the equilibrium temperature of crystallizations. In general, number of mineral phases can be determined by the “Phase Rule”. According to the mass balance principle, bulk composition of coexisting two-feldspar could be evaluated from the bulk chemistry of a rock, provided that the compositions of the coexisting mafic mineral phases containing calcium, sodium, and potassium oxides are determined, e.g., by microprobe analysis. The compositions, proportions, and temperature of two-feldspar in equilibrium can thus be simultaneously resolved numerically from bulk composition of the rock, by incorporating the activity/composition relations of the ternary feldspars with the mass balance constraints. Upon the numerical approximation method presented in this paper, better-quality, internally consistent data on feldspar group could usually be obtained, which would be expected more realistic and accurate in consideration of thermodynamic equilibria in the system of crystalline rocks, as well as bulk chemistry of a rock and the composing minerals.     

Hydrogen and Oxygen Isotopic Compositions of Sedimentary Clay in the Sea Region off the Western Antarctic Peninsula and Their Material Sources

In the geochemical study of sedimentation, hydrogen and oxygen isotope data are useful for a discussionon formation conditions and material sources of sediments. Hydrogen and oxygen isotope analyses were madeon clays separated from the sea-floor surface sediments at 9 stations in the western sea region of the AntarcticPeninsula. On the basis of these isotopic data and the clay mineral components and by use of statistical dia-grams, it may be concluded that the clay fraction in this sea region is composed mainly of terrigenous detritus:i.e. it was formed by surface weathering or supergene alteration of the rocks from the terrigenous region in thepeninsular in the presence of meteoric water. However, at least a part of montmorillonite is a marine authigenicmineral formed by alteration of submarine eruptive materials or terrigenous pyroclasts in the presence of seawater. The above result is consistent with the idea derived from the study of clay mineralogy.     

Magnetic susceptibility of the Xifeng section and its paleoclimate significance

Magnetic susceptibility (MS) is one of the most important indicators of the East- Asia summer monsoon. Presented in this study is a high resolution magnetic susceptibility record from the Xifeng section, which consists of Quaternary loess-paleosol sequence and Pliocene red clay. Variations in magnetic susceptibility are well correlated with the δ18O record in deep-sea sediments and the eolian flux of Greenland. The climatic evolution in the Xifeng section shows that since the Late Tertiary, the driving forc...     

Compositional Distribution and Growth Mode of Garnet Porphyroblasts during Deformation and Metamorphism

Although porphyroblast microstructures play an important role in structural and metamorphic studies, there are still controversies in the interpretation. The focus is how porphyroblasts grow during deformation and metamorphism. In this paper, we introduce a new approach, the Synchrotron Radiation X-Ray Fluorescence, to a hemi-quantitative interpretation of the growth mode of porphyroblasts. The analysis was done at the Beijing Synchrotron Radiation Facility. The specimens were sampled from metapelite of the Baoyintu Group, northern Urad Middle Banner, Inner Mongolia. The new method is successful for determining the microscopic distribution of trace elements in porphybroblasts. The results support the theory of deformation partition, which has been brought forth by Bell and his colleagues, and demonstrate the existence of porphyroblast growth phases and the growth mode of porphyroblasts by hemi-quantitative mineral chemical analysis. The porphyroblast grows stage by stage in the manner of the distribution     

Paleoclimate and Paleoenvironment of Gonghe Basin, Qinghai-Tibet Plateau, During the Lastdeglacial: Weathering, Erosion and Vegetation Cover Affect Clay Mineral Formation

With the analysis of the sources and formation mechanism of the clay minerals in the sediment core from the Dalianhai lake in the Gonghe Basin,northeastern Tibet-Qinghai Plateau,clay mineral composition proxies,grain-size and carbonate contents have been employed for high-resolution study in order to reconstruct East Asian Summer Monsoon （EASM） over the northeastern Tibet-Qinghai Plateau during the lastdeglacial.The study also extended to establish a relationship between vegetation cover changes and erosion during the last 14.5 ka with pollen record and clay mineral proxies.Smectite/kaolinite and smectite/（illite＋chlorite） ratios allow us to assess hydrolysis conditions in lowlands and/or physical erosion process in highlands of the Gonghe Basin.Before 12.9 Cal ka BP,both mineralogical ratios show low values indicative of strong physical erosion in the basin with a dominant cold and dry phase.After 12.9 Cal ka BP,an increase in both mineralogical ratios indicates enhanced chemical weathering in the basin associated with a warm and humid climate.The beginning of Holocene is characterized by high smectite/（illite＋chlorite） and smectite/kaolinite ratios that is synchronous as with deposition of many peat laminae,implying the best warm and humid conditions specifically between 8.0 to 5.5 Cal ka BP.The time interval after 5.0 Cai ka BP is characterized by a return to high physical erosion and low chemical weathering with dry climate conditions in the basin.Comparing variations of clay mineral assemblages with previous pollen results,we observe a rapid response in terms of chemical weathering and physical erosion intensity to a modification of the vegetation cover in the basin.     

Ophiolites as Archives of Recycled Crustal Material Residing in the Deep Mantle

Deeply subducted lithospheric slabs may reach to the mantle transition zone(MTZ,410-660 km depth)or even to the core–mantle boundary(CMB)at depths of~2900km.Our knowledge of the fate of subducted surface material at the MTZ or near the CMB is poor and based mainly on the tomography data and laboratory experiments through indirect methods.Limited data come from the samples of deep mantle diamonds and their mineral inclusions obtained from kimberlites and associated rock assemblages in old cratons.We report in this presentation new data and observations from diamonds and other UHP minerals recovered from ophiolites that we consider as a new window into the life cycle of deeply subducted oceanic and continental crust.Ophiolites are fragments of ancient oceanic lithosphere tectonically accreted into continental margins,and many contain significant podiform chromitites.Our research team has investigated over the last 10 years ultrahigh-pressure and super-reducing mineral groups discovered in peridotites and/or chromitites of ophiolites around the world,including the Luobusa(Tibet),Ray-Iz(Polar Urals-Russia),and 12 other ophiolites from 8orogenic belts in 5 different countries(Albania,China,Myanmar,Russia,and Turkey).High-pressure minerals include diamond,coesite,pseudomorphic stishovite,qingsongite(BN)and Ca-Si perovskite,and the most important native and highly reduced minerals recovered to date include moissanite(Si C),Ni-Mn-Co alloys,Fe-Si and Fe-C phases.These mineral groups collectively confirm extremely high?pressures(300 km to≥660 km)and super-reducing conditions in their environment of formation in the mantle.All of the analyzed diamonds have unusually light carbon isotope compositions(δ13C=-28.7 to-18.3‰)and variable trace element contents that*d i stinguish them from most kimberlitic and UHPmetamorphic varieties.The presence of exsolution lamellae of diopside and coesite in some chromite grains suggests chromite crystallization depths around380 km,near the mantle transition zone.The carbon isotopes and other features of the high-pressure and super-reduced mineral groups point to previously subducted surface material as their source of origin.Recycling of subducted crust in the deep mantle may proceed in three stages:Stage 1–Carbon-bearing fluids and melts may have been formed in the MTZ,in the lower mantle or even near the CMB.Stage 2–Fluids or melts may rise along with deep plumes through the lower mantle and reach the MTZ.Some minerals,such as diamond,stishovite,qingsongite and Ca-silicate perovskite can precipitate from these fluids or melts in the lower mantle during their ascent.Material transported to the MTZ would be mixed with highly reduced and UHP phases,presumably derived from zones with extremely low f O2,as required for the formation of moissanite and other native elements.Stage 3–Continued ascent above the transition of peridotites containing chromite and ultrahigh-pressure minerals transports them to shallow mantle depths,where they participate in decompressional partial melting and oceanic lithosphere formation.The widespread occurrence of ophiolite-hosted diamonds and associated UHP mineral groups suggests that they may be a common feature of in-situ oceanic mantle.Because mid-ocean ridge spreading environments are plate boundaries widely distributed around the globe,and because the magmatic accretion of oceanic plates occurs mainly along these ridges,the on-land remnants of ancient oceanic lithosphere produced at former mid-ocean ridges provide an important window into the Earth’s recycling system and a great opportunity to probe the nature of deeply recycled crustal material residing in the deep mantle     

Enrichment of arsenic, antimony, thallium and selenium in high-arsenic coal from Xingren County, Guizhou Province

Since 1976 high arsenic coal in Xingren County, Guizhou Province, has attracted more and more attention because of coal-burning-type arsenic poisoning, There are many studies on enrichment of arsenic in high-arsenic coal and they come from difference materials： organic matter, authigenic pyrite, epigenetic pyrite, authigenic clay mineral and epigenetic clay mineral. In this paper, fourteen samples were examined by proximate analysis. Inductively coupled plasma mass spectrometry （ICP-MS） was used to determine the trace element contents of thirty-six samples in high-arsenic coal, As was determined by instrumental neutron activation analysis （INAA） and atomic fluorescence spectrometry （AFS）. SEM-EDX was used to analyze the contents of As, Sb, Tl and Se in sample XR-8 from Xingren, Guizhou, and we analyzed the petrographic compositions of the same sample.     

Mineralogy of Holocene Sediments from the Southwestern Black Sea Shelf (Turkey) in Relation to Provenance, Sea-level and Current Regimes

Grain size and mineral composition of core sediments were used to investigate influences of various terrestrial and marine conditions, which have prevailed on the southwestern Black Sea shelf during the Holocene. Siliciclastic mud with small amounts of sand and gravel from nearby coastal hinterland is the principal sediment type, whereas sediments deposited near the shelf edge and the Istanbul Strait and off the Duru Lake （a paleo-river mouth） constitued large quantities of sand and gravel of both biogenic and terrigenic origin. Variable amounts of aragonite, 1 nmmicas, quartz, feldspars, calcite and dolomite constitute the dominant non-clay minerals in bulk sediments. The clay mineral assemblage in the 〈 2 μm fraction is made up of smectite, illite, kaolinite and chlorite. Aragonite and calcite are mainly derived from benthic accumulations, whereas feldspars （mainly plagioclase） and smectite reflect magmaticvolcanic provenance and the distribution of 1 nm-micas and chlorite correlate with nearby metamorphic sources onland. Nevertheless, grain size and mineral distribution generally indicate a combination of effects of wind and wave climate, longshore and offshore cyclonic currents, changing sea-level stands and nearby source rock and morphological conditions. It is also suggested that at least part of clay minerals could be derived from the northwesterly Danube River input.     

Sorption of nonionic polar pesticides to smectite

Sorption of geosorbents including soils and sediments is a key process controlling the fate and transport of hydrophobic organic compounds （HOCs） in the environment. HOC sorption has been generally correlated to the nature and content of organic matter present in the geosorbents. However, several environments can have organic matter contents low enough so that clay mineral surfaces are the dominant sorbents, including low-organic carbon soils, some ground water aquifers, atmospheric water droplets （e.g. clouds, fogs, and raindrops）, and engineered environmental systems （e.g. clay barriers）. Furthermore, several previous studies demonstrated that clays or clay components in soils sorb HOCs higher than expected, especially those compounds containing strong polar functionalities. Because many environmentally related HOCs including a significant portion of pesticides and herbicides contain polar functional groups, studying the interactions of these compounds with mineral surface at the molecular level is of great theoretical and practical importance. In the present study, we studied sorption of a series of nonionic pesticides （e.g. dichlobenil, carbaryl, alachlor, metolachlor, monuron, diuron, cyanazine） containing polar functional groups and a polycyclic aromatic hydrocarbon, naphthalene, as a control on a reference smectite （SWy-2） saturated with K^＋ using combined batch sorption and FTIR methodologies.