vertical motion in the gulf stream near 68 w abstract the authors compute and compare vertical motions from three different data sources within a 300 km square domain centered in the gulf stream near 38 n 68 w and show that vertical motions inferred from all three independent data sources and different analysis methods give similar results the time derivatives of rafos float pressures on isopycnal surfaces are used to determine directly observed vertical motion wraf second vertical motions are inferred from the heat equation using measured temperature changes and the backing and veering of currents observed by a stack of current meters to produce wcm third vertical motions are calculated from the quasigeostrophic vorticity equation using geostrophic streamfunctions from inverted echo sounder measurements to produce wies wcm agrees well with wraf from all floats that pass within 10 km of a current meter mooring daily fields of wcm show very good coherence with time series of wcm for periods longer than 16 d but noise domination for periods

the effects of thermochemical sulfate reduction upon formation water salinity and oxygen isotopes in carbonate gas reservoirs abstract thermochemical sulfate reduction tsr is a well known process that can lead to sour h2s rich petroleum accumulations most studies of tsr have concentrated upon gas chemistry in this study we have investigated palaeoformation water characteristics in a deep anhydrite bearing dolomite sour gas reservoir of permian age in abu dhabi using fluid inclusion stable isotope petrographic and gas chemical data the data show that low salinity isotopically distinct water was generated within the reservoir by reaction between anhydrite and methane the amount of water added to the reservoir from tsr indicated by reduced fluid inclusion salinity and water 18o values varied systematically with the extent of anhydrite reaction with methane water salinity and isotope data show that the original formation water was diluted by between four and five times by water from tsr thus we have shown that large volumes of very low salinity water were generated within the gas reservoirs during diagenesis following gas emplacement the salinity of formation water in evaporite lithologies is therefore not necessarily high modelling based upon a typical khuff gas reservoir rock volume suggests that initial formation water volumes can only be increased by about three times as a result of tsr the extreme local dilution shown by the water salinity and 18o data must therefore reflect transiently imperfect mixing between tsr water and original formation water the creation of large volumes of water has important implications for the mechanism and rate of thermochemical sulphate reduction and the interpretation of gas volumes using petrophysical logging tools

bio physical changes in the coastal ocean triggered by typhoon a case of typhoon meari in summer 2011 abstract based on the combination of synchronous satellite and in situ observations we here for the first time provide the compelling evidence of bio physical response of coastal environment in the bohai sea china to the passage of typhoon meari over the northern yellow sea on june 26 2011 strong sustained winds induced a tongue like intrusion of cool water from the northern yellow sea into the bohai sea resulting in significant surface cooling and an anomalous increase in sea surface height along the coast of the western bohai sea this in return produced downwelling and transport of the warm and nutrient rich coastal water from the western coast to the central bohai sea as driven by the barotropic pressure gradient force in situ observational data confirmed the cooling of both surface and bottom layers with salinity increase however the measured temperature increase by 2 3 c concomitant salinity decrease by 0 3 psu and two fold increase in chlorophyll a in the middle layers suggested an influence from coastal downwelling ekman transport and typhoon enhanced mixing redistributed the nutrients and thus resulted in higher chlorophyll a concentrations in the upper layers

late palaeozoic to neogene geodynamic evolution of the northeastern oman margin when the highlands of arabia were still covered with an ice shield in the latest carboniferous early permian period separation of gondwana started this led to the creation of the batain basin part of the early indian ocean off the northeastern margin of oman the rifting reactivated an infra cambrian rift shoulder along the northeastern oman margin and detritus from this high was shed into the interior oman basin whereas carbonate platform deposits became widespread along the margin of the neo tethys northern rim of oman drifting and oceanization of the batain basin started only in late jurassic early cretaceous time extensional tectonics was followed in the late cretaceous by contraction caused by the northward drift of greater india and afro arabia this resulted in the collision of afro arabia with an intra oceanic trench and obduction of the semail ophiolite and the hawasina nappes south to southwestward onto the northern oman margin 80 m y ago during the middle cretaceous the oceanic lithosphere including the future eastern ophiolites of oman drifted northwards as part of the indian plate at the cretaceous palaeogene transition 65 ma oblique convergence between greater india and afro arabia caused fragments of the early indian ocean to be thrust onto the batain basin subsequently the lower permian to uppermost maastrichtian sediments and volcanic rocks of the batain basin along with fragments of indian ocean floor eastern ophiolites were obducted northwestward onto the northeastern margin of oman palaeogene neo autochtonous sedimentary rocks subsequently covered the nappe pile tertiary extensional tectonics related to red sea rifting in the late eocene was followed by miocene shortening associated with the collision of arabia and eurasia and the formation of the oman mountains

hydrogeochemical processes and quality assessment of groundwater in dumka and jamtara districts jharkhand india the hydrogeochemical study of groundwater in dumka and jamtara districts has been carried out to assess the major ion chemistry hydrogeochemical processes and groundwater quality for domestic and irrigation uses thirty groundwater samples were collected and analyzed for ph electrical conductivity total dissolved solids tds total hardness anions f cl no3 hco3 so42 and cations ca2 mg2 na k the analytical results show the faintly alkaline nature of water and dominance of mg2 and ca2 in cationic and hco3 and cl in anionic abundance the concentrations of alkaline earth metals ca2 mg2 exceed the alkali metals na k and hco3 dominates over so42 cl concentrations in the majority of the groundwater samples ca mg hco3 is the dominant hydrogeochemical facies in 60 of the groundwater samples while 33 samples occur as a mixed chemical character of ca mg cl hydrogeochemical facies the water chemistry is largely controlled by rock weathering and ion exchange processes with secondary contribution from anthropogenic sources the inter elemental correlations and factor and cluster analysis of hydro geochemical database suggest combined influence of carbonate and silicate weathering on solute acquisition processes for quality assessment analyzed parameter values were compared with indian and who water quality standards in majority of the samples the analyzed parameters are well within the desirable limits and water is potable for drinking purposes total hardness and concentrations of tds cl no3 ca2 and mg2 exceed the desirable limits at a few sites however except no3 all these values were below the highest permissible limits the calculated parameters such as sodium adsorption ratio percent sodium na and residual sodium carbonate revealed excellent to good quality of groundwater for agricultural purposes except at few sites where salinity and magnesium hazard mh values exceeds the prescribed limits and demands special management

a comparison of khuff and arab reservoir potential throughout the middle east a compilation of average porosity and permeability data for petroleum reservoirs in the permian triassic khuff formation and the jurassic arab formation shows that most khuff reservoirs have an average porosity of less than 12 whereas most arab reservoirs have an average porosity of 12 26 higher porosity correlates with shallower depth suggesting that burial diagenesis is the main cause of the overall porosity difference between these units deeper burial of khuff reservoirs is inferred to have resulted in greater porosity loss by chemical compaction and associated cementation a broad correlation also exists between average porosity and average permeability suggesting that deeper burial and the resulting porosity decrease are also a primary cause of the lower permeabilities of the khuff reservoirs in addition to greater burial depth however a combination of depositional and early diagenetic factors is also reflected in the lower average porosity and permeability values of the khuff reservoirs khuff strata were deposited on an extensive poorly circulated very low relief shelf and consist in large part of interbedded mudstones and grainstones having relatively fine grain size with major amounts of depositional calcium sulfate present arab reservoirs were deposited under better circulated conditions near platform margins facing deep intracratonic basins and thus have coarser more grain dominated fabrics and lesser overall content of chemically precipitated grains calcium sulfate and dolomite khuff deposits were likely composed of less stable mineralogy than arab sediments because the late permian was a time of aragonite seas whereas the late jurassic was a time of calcite seas the combined result of these factors is that arab reservoirs are characterized by greater preservation of primary depositional pore types more coarsely crystalline dolomite fabrics and lesser plugging by anhydrite finally a possible factor affecting the average porosity and permeability values is petroleum composition which is gas in most khuff reservoirs and oil in arab reservoirs lower economic cutoff values for gas production would favor inclusion of low permeability zones in khuff reservoirs thus reducing average reservoir values two main aspects of these results are innovative this is the first time that porosity and permeability values for either khuff or arab reservoirs have been examined regionally second the conclusion that thermal exposure is the primary control on average porosity and permeability in these units is consistent with previous work from other carbonates but is new for the middle east

hydrogeochemistry of coal mine water of north karanpura coalfields india implication for solute acquisition processes dissolved fluxes and water quality assessment mine water samples collected from different mines of the north karanpura coalfields were analysed for ph electrical conductivity total dissolved solids tds total hardness th major anions cations and trace metals to evaluate mine water geochemistry and assess solute acquisition processes dissolved fluxes and its suitability for domestic industrial and irrigation uses mine water samples are mildly acidic to alkaline in nature the tds ranged from 185 to 1343 mg l 1 with an average of 601 mg l 1 ca2 and mg2 are the dominant cations while so4 2 and hco3 are the dominant anions a high concentration of so4 2 and a low hco3 hco3 so4 2 ratio 0 50 in the majority of the water samples suggest that either sulphide oxidation or reactions involving both carbonic acid weathering and sulphide oxidation control solute acquisition processes the mine water is undersaturated with respect to gypsum halite anhydrite fluorite aluminium hydroxide alunite amorphous silica and oversaturated with respect to goethite ferrihydrite quartz about 40 of the mine water samples are oversaturated with respect to calcite dolomite and jarosite the water quality assessment shows that the coal mine water is not suitable for direct use for drinking and domestic purposes and needs treatment before such utilization tds th f so4 2 fe mn ni and al are identified as the major objectionable parameters in these waters for drinking the coal mine water is of good to suitable category for irrigation use the mines of north karanpura coalfield annually discharge 22 35 106 m3 of water and 18 50 103 tonnes of solute loads into nearby waterways

storm surge induced flux through multiple tidal passes of lake pontchartrain estuary during hurricanes gustav and ike abstract in september 2008 hurricanes gustav and ike generated major storm surges which impacted the lake pontchartrain estuary in louisiana this paper presents analyses of in situ measurements acquired during these storm events the main data used in the analyses were from three bottom mounted moorings equipped with conductivity temperature and depth sensors acoustic doppler current profilers adcps and a semi permanent laterally mounted horizontal acoustic doppler profiler adp these moorings were deployed in the three major tidal channels that connect lake pontchartrain with the coastal ocean a process similar to tidal straining was observed the vertical shear of the horizontal velocity was negligible during the inundation stage but a shear of 0 8 m s over a less than 5 m water column was recorded during the receding stage 2 3 times the normal tidal oscillations the surge reached its peak in the industrial canal 1 4 2 1 h before those in the other two channels the inward flux of water lasted for a shorter time period than that of the outward flux the inward flux was also observed to have much smaller magnitude than the outward flux 960 1200 vs 2100 3100 million m 3 the imbalance was believed to have been caused by the additional water into lake pontchartrain through some small rivers and inundation over the land plus rainfall from the hurricanes the flux through the industrial canal was 8 12 while the flux through the other two tidal passes ranged between 17 and 70 of the total but mostly split roughly half half of the remaining 88 92 of the total

evaluation of groundwater quality in the cihanbeyli basin konya central anatolia turkey the cihanbeyli basin is located in the northern part of konya in the central anatolian region turkey and is characterized by semi arid climatic conditions and scarcity in water resources the suitability of groundwater quality for drinking and agricultural purposes in the cihanbeyli basin was assessed by measuring physicochemical parameters including major cation and anion compositions ph total dissolved solid electrical conductivity and total hardness for this purpose 54 samples were collected from different sources viz deep wells shallow wells and springs results from hydrochemical analyses reveal that groundwater is mostly affected by salty and gypsiferous lithologies evaporite minerals such as gypsum anhydrite and chloride salts make high contributions from the recharge areas west northwest and southwest parts toward the discharge area central and eastern parts high values of total dissolved solids in groundwater are associated with high concentrations of all major ions a comparison of groundwater quality in relation to drinking water standards showed that most of the water samples are not suitable for drinking based on sodium absorption ratio values and percent sodium salinity appears to be responsible for the poor groundwater quality rendering most of the samples unsuitable for irrigation usage it is concluded that evaporation and mineral dissolution are the main processes that determine major ion compositions

hydrogeochemical processes in the groundwater environment of heihe river basin northwest china the heihe river basin is a typical arid inland river basin for examining stress on groundwater resources in northwest china the basin is composed of large volumes of unconsolidated quaternary sediments of widely differing grain size and during the past half century rapid socio economic development has created an increased demand for groundwater resources understanding the hydrogeochemical processes of groundwater and water quality is important for sustainable development and effective management of groundwater resources in the heihe river basin to this end a total of 30 representative groundwater samples were collected from different wells to monitor the water chemistry of various ions and its quality for irrigation chemical analysis shows that water presents a large spatial variability of chemical facies so42 hco3 so42 cl and cl so42 as groundwater flow from recharge area to discharge area the ionic ratio indicates positive correlation between the flowing pairs of parameters cl and na r 0 95 so42 and na r 0 84 hco3 and mg2 r 0 86 and so42 and ca2 r 0 91 dissolution of minerals such as halite gypsum dolomite silicate and mirabilite na2so4 10h2o in the sediments results in the cl so42 hco3 na ca2 and mg2 content in the groundwater other reactions such as evaporation ion exchange and deposition also influence the water composition the suitability of the groundwater for irrigation was assessed based on the us salinity laboratory salinity classification and the wilcox diagram the results show that most of the groundwater samples are suitable for irrigation uses barring a few locations in the dessert region in the northern sub basin

progress on upwelling studies in the china seas east asian marginal seas surrounding china exhibit rich ocean upwelling mostly in response to the southwesterly summer monsoon upwelling in the china seas namely the south china sea the taiwan strait the east china sea the yellow sea and the bohai sea has become increasingly important because the potential changes in the upwelling may have dramatic ecosystem socioeconomic and climate impacts this paper reviews the progress of upwelling studies in the china seas since the year 2000 by presenting the principal characteristics and new understanding of 12 major upwelling regions in the china seas upwelling exhibits long term variability at intraseasonal to multi decadal scales as well as short term variability frequently caused by tropical cyclones it is also associated with the el nino southern oscillation local environmental variation and biogeochemical factors the coastal upwelling around hainan island and the upwelling or cold dome northeast of taiwan island are specifically highlighted because they have attracted great interest for decades this paper summarizes upwelling mechanisms in terms of wind topography tide stratification and background flow with applications mostly to the china seas finally we propose some topics for future upwelling research i e potential intensification of coastal upwelling under global climate change downwelling intrusion of upwelling into coastal embayments and the influence of upwelling on fishery and biogeochemical processes

hydrochemical characterisation of water quality in the sarcheshmeh copper complex se iran hydrochemical investigations were conducted to identify variations in surface water chemistry in different parts of the sarcheshmeh copper complex twenty three water samples from mine drainage stream water processing water of the concentrator plant and tailings dam water were collected to understand processes that control the elements mobility changes in trace metal concentrations and variation of major ions show two distinct water types a neutral mine drainage nmd associated with the sarcheshmeh mine waters containing lower trace metal so42 concentrations and neutral ph values and b acid mine drainage amd with waters from tailings impoundments and waste rock dumps corresponding to higher trace metals fe cu zn mo and major anions so42 and cl than the first type with typically acidic ph contents as a result of cu mo sulphides flotation process under alkaline conditions high ph values high mo concentration and low contamination loads of al mn fe cu and cd were observed in reject waters from the concentrator plant sulphide oxidation especially pyrite dissolution precipitation of the secondary minerals and discharge of the reject waters from concentrator plant were some of the most important factors that influence water quality at the tailings impoundments the results of phreeqc speciation and solubility modelling indicated supersaturation of the waters in the tailings impoundments with respect to hydronium jarosite schwertmannite and gypsum

forced stage response to a moving hurricane abstract the upper ocean s response to three hurricanes norbert 1984 josephine 1984 and gloria 1985 is examined using field observations and a numerical ocean model our goal is to describe the physical processes that determine the structure and amplitude of hurricane driven upper ocean currents all three of these northern hemisphere hurricanes produced a rightward biased response of the mixed layer current and transport this asymmetry arises because the wind stress vector rotates clockwise on the right side of the track and remains nearly parallel with the inertially rotating mixed layer current during most of the hurricane passage the maximum observed mixed layer current varied from 0 8 m s 1 in response to josephine which was a large but comparatively weak hurricane to 1 7 m s 1 in response to gloria which was very large and also intense these cases have been simulated with a three dimensional numerical model that includes a treatment of wind driven vertical mixing within the primitive

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

major ion chemistry of the ganga brahmaputra river system weathering processes and fluxes to the bay of bengal the ganga brahmaputra one of the world s largest river systems is first in terms of sediment transport and fourth in terms of water discharge a detailed and systematic study of the major ion chemistry of these rivers and their tributaries as well as the clay mineral composition of the bed sediments has been conducted the chemistry of the highland rivers upper reaches of the ganga the yamuna the brahmaputra the gandak and the ghaghra are all dominated by carbonate weathering ca mg and hco3 account for about 80 of the cations and anions in the lowland rivers the chambal the betwa and the ken hco3 excess over ca mg and a relatively high contribution of na k to the total cations indicate that silicate weathering and or contributions from alkaline saline soils and groundwaters could be important sources of major ions to these waters the chemistry of the ganga and the yamuna in the lower reaches is by and large dictated by the chemistry of their tributaries and their mixing proportions illite is the dominant clay mineral about 80 in the bedload sediments of the highland rivers kaolinite and chlorite together constitute the remaining 20 of the clays in the chambal betwa and ken smectite accounts for about 80 of the clays this difference in the clay mineral composition of the bed sediments is a reflection of the differences in the geology of their drainage basins the highland rivers weather acidic rocks whereas the others flow initially through basic effusives the ganga brahmaputra river system transports about 130 million tons of dissolved salts to the bay of bengal which is nearly 3 of the global river flux to the oceans the chemical denudation rates for the ganga and the brahmaputra basins are about 72 and 105 tons km yr 1 respectively which are factors of 2 to 3 higher than the global average the high denudation rate particularly in the brahmaputra is attributable to high relief and heavy rainfall

preliminary studies on the geochemistry of the mahanadi river basin india water and suspended and bed sediments were collected during 1986 1987 for the two seasons and analysed to study the geochemistry of the mahanadi river basin which is one of the eight major drainage systems in india the water chemistry reflects the control exercised on weathering by the most abundant lithology namely the carbonates in the basin water composition is in equilibrium with dolomite kaolinite and chlorite xrd studies in suspended and bed sediments show the presence of dolomite kaolinite chlorite and minor quantities of montmorillonite the mahanadi annually delivers 15 74 106t of sediments to the bay of bengal which is high compared to its basin size the dissolved load dominates over physical load by a factor of 4 with 95 of the transport taking place in the monsoon season the basin is characterised by an erosion rate of 138 24 t km 2 yr 1 with a lowering rate of 0 31 mm yr 1 textural studies indicate that the bed sediments are relatively coarser grained than the suspended sediments due to reworking the sediments are finer downstream fe mn cu zn and pb concentrations in the sediments are higher compared to the other peninsular indian rivers eventhough mahanadi transports annually to the bay of bengal 10 of the total load by other indian rivers and its weathering in a complex geological terrain with rich mineral deposits controls to a larger extent the chemistry of the sediments in the bay of bengal

environmental geochemistry and quality assessment of mine water of jharia coalfield india a long mining history and unscientific exploitation of jharia coalfield caused many environmental problems including water resource depletion and contamination a geochemical study of mine water in the jharia coalfield has been undertaken to assess its quality and suitability for domestic industrial and irrigation uses for this purpose 92 mine water samples collected from different mining areas of jharia coalfield were analysed for ph electrical conductivity ec major cations ca2 mg2 na k anions f cl hco3 so4 2 no3 dissolved silica h4sio4 and trace metals the ph of the analysed mine water samples varied from 6 2 to 8 6 indicating mildly acidic to alkaline nature concentration of tds varied from 437 to 1 593 mg l 1 and spatial differences in tds values reflect the variation in lithology surface activities and hydrological regime prevailing in the region so4 2 and hco3 are dominant in the anion and mg2 and ca2 in the cation chemistry of mine water high concentrations of so4 2 in the mine water of the area are attributed to the oxidative weathering of pyrites ca mg so4 and ca mg hco3 are the dominant hydrochemical facies the drinking water quality assessment indicates that number of mine water samples have high tds total hardness and so4 2 concentrations and needs treatment before its utilization concentrations of some trace metals fe mn ni pb were also found to be above the desirable levels recommended for drinking water the mine water is good to permissible quality and suitable for irrigation in most cases however higher salinity residual sodium carbonate and mg ratio restrict its suitability for irrigation at some sites

estimates of horizontal divergence and vertical velocity in the equatorial pacific abstract horizontal divergence and vertical velocity in the surface mixed layer of the equatorial pacific between 90 and 150 w are estimated from current measurements obtained from trajectories of freely drifting buoys during 1979 1990 the 12 year averaged horizontal divergence is predominantly meridional and has a maximum magnitude of 3 4 10 6 s 1 in a 20 km wide latitude band cantered on the equator using the equation of continuity this divergence corresponds to an upwelling velocity of 1 5 2 10 4 m s 1 at 50 m depth the seasonal variations of equatorial divergence are in good agreement with the local zonal wind stress

microfacies depositional environment and diagenetic evolution controls on the reservoir quality of the permian upper dalan formation kish gas field zagros basin abstract the upper permian upper dalan formation contains one of the largest gas reservoirs in the world the formation consists of carbonates with some evaporite intercalations that developed on a gently sloping homoclinal carbonate ramp facing the late permian paleo tethys ocean this study focuses on the kish gas field zagros offshore basin situated between iran and qatar and is based on a 222 m thick continuous core based on the integration of core and wireline log data coupled with petrographic analyses of 580 thin sections three major depositional environments facies belts with 11 carbonate microfacies are identified these include 1 sabkha to tidal flat laminated to massive anhydrite dolomudstone with anhydrite nodules dolomudstone and intraclastic dolowackestone 2 lagoon and leeward shoals bioclastic wackestone dolowackestone to packstone and peloid dolopackstone and peloid bioclastic dolopackstone and 3 mobile windward sand shoal ooid peloid dolograinstone ooid dolograinstone ooid intraclast dolograinstone ooid bioclast dolograinstone packstone and coarse bioclast intraclast dolograinstone diagenetic evolution of the upper dalan formation is associated with evaporative marine shallow water normal marine meteoric and burial diagenetic environments common diagenetic effects include dolomite and calcite cementation mechanical and chemical compaction dissolution dolomitization and evaporative anhydrite mineralization reservoir quality is strongly affected by variations in the original rock fabrics and subsequent diagenetic alterations the most common pore types include interparticle moldic and connected vug fracture and cavernous the interparticle porosity permeability relationship for the studied facies suggests that the reservoir quality is not affected by different crystal sizes and most samples plot in the low porosity and low to high permeability field or display lucia class 1 or 2 petrophysical relationships the study shows that the pervasive pore filling anhydrite mineralization lead to a significant decrease in porosity and permeability poikilotopic anhydrite cement reduced matrix porosity but the pore size was less affected

solute geochemistry and its sources of the groundwaters in the qinghai lake catchment nw china major ion compositions were analyzed in 65 groundwater samples to decipher water quality solute geochemistry and sources of groundwater within the qinghai lake catchment ne tibetan plateau groundwaters were slightly alkaline with ph varying from 7 2 to 8 7 the total dissolved solids tds varied over two orders of magnitude from fresh 88 to brackish 12 with a mean value of 672 mg l higher than river waters within the qinghai lake catchment and river waters draining the himalayas and the southeastern tibetan plateau most of the samples approximately 80 were the ca 2 mg 2 hco 3 type and suitable for drinking and irrigation some of the lakeside the buha and the qinghai lake water were cl type and not suitable for drinking and irrigation water quality of hargai and shaliu samples was better than the others rock weathering ion exchange and precipitation are the major geochemical processes responsible for the solutes in the groundwater within the qinghai lake catchment anthropogenic input to the groundwater is minor the forward models on the input of groundwaters from various sources showed that the contributions were 40 1 for carbonate weathering 29 0 for evaporite dissolution 16 8 for atmospheric input and 14 1 for silicate weathering of the total dissolved cations for the whole catchment evaporite dissolution was dominating in the lakeside the buha and the daotang samples contributing 15 3 45 9 20 4 61 1 and 21 3 63 9 of the total dissolved cations respectively carbonate weathering was dominated in the shaliu and the hargai samples contributing 23 9 71 7 and 31 8 95 4 of the total dissolved cations respectively the result also demonstrated that carbonate weathering had higher contribution to the groundwaters than silicate weathering

dolomite and dolomitization of the permian khuff c reservoir in ghawar field saudi arabia abstract the permian khuff c reservoir in saudi arabia is known for its lateral and vertical heterogeneity caused mainly by dolomitization detailed petrographic analysis of 600 thin sections from six cored wells revealed three main replacive dolomite fabrics 1 fabric preserving mimetic fpm 2 fabric preserving nonmimetic fpnm and 3 fabric destructive fd dolomites crystal sizes are mostly less than or equal to 20 m for fpm dolomite less than or equal to 50 m for fpnm dolomite and less than or equal to 100 m for fd dolomite the fpm dolomite decreases in abundance and fpnm dolomite increases in abundance with increasing grain content of the facies the 18 o values of dolostones although considered an obsolete term dolostone is used here to mean rock containing 80 dolomite indicate early dolomitization at low temperatures in permian seawater or evaporated seawater with landward facies mudstone and wackestone generally dolomitized by more evaporated waters and seaward grainy facies generally dolomitized by less evaporated more normal marine seawaters stratigraphic variations in the dolostones 18 o values track with facies variations through fourth order depositional sequences and indicate that different stratigraphic bodies of dolomite formed from seawaters with different degrees of evaporation the 13 c values of the dolostones exhibit temporal trends inherited from the precursor limestones variations in the lateral and vertical abundance of dolomite and dolomite fabrics in the propensity for each facies to be dolomitized and in the dolomites oxygen isotopic values all suggest that multiple dolomitization events occurred in the khuff c reservoir as depositional cycles accumulated with some dolostones overprinted by younger events average porosities of grain rich dolostones are greater than those of mud rich dolostones indicating that depositional facies preordained porosity distribution within the dolostones however the more evaporated the dolomitizing fluid the more likely dolomitization resulted in lower porosity regardless of facies

upper layer circulation in the south china sea abstract upper layer circulation is investigated by using all available historical temperature profiles combined with climatological temperature salinity relationships in the south china sea two cyclonic eddies are revealed one is located east of vietnam called the east vietnam eddy and the other is off northwest luzon called the west luzon eddy both local ekman pumping and remotely forced basin scale circulation are important mechanisms controlling these two eddies the luzon strait transport relative to 400 db is estimated to be of the order 3 0 sv 1 sv 1 106 m3 s 1 in the mean and has a seasonal cycle dominated by the annual signal with a maximum 5 3 sv in january february and a minimum 0 2 sv in june july pressure gradients are also examined to explore the dynamics of the intrusion of waters from the pacific into the south china sea through the luzon strait

identification of groundwater contamination zones and its sources by using multivariate statistical approach in thirumanimuthar sub basin tamil nadu india hydrogeochemical studies have been made in the study area by using multivariate statistical analysis which is mainly helpful for interpretation of complex data matrices to better understand the geochemical evolution of the area and it allows identifying the possible factors sources that influence water systems the spatial distribu tion of electrical conductivity reveals that an untreated industrial effluents landfill and anthropogenic activities affecting their groundwater quality in its vicinity and the surrounding area the dominance of ions was in the order of na ca 2 mg 2 k cl hco3 so4 2 no3 and ca 2 mg 2 na k hco3 cl no3 so4 2 during pre monsoon prm and post monsoon pom respectively the statistical results reveals that the groundwater chemistry gets altered by silicate weathering ion exchange leaching anthropogenic input from agricultural return flow and longer distance of migrating groundwater the hydrogeochemical regimes are distributed along the upstream side northwestern western and eastern parts of the study area the study highlights the descriptive capabilities of conventional and multivariate techniques as effective tools in groundwater evaluation

diagnosis of 3d vertical circulation in the upwelling and frontal zones east of hainan island china abstractusing the generalized omega equation and cruise observations in july 2012 this study analyzes the 3d vertical circulation in the upwelling region and frontal zone east of hainan island china the results show that there is a strong frontal zone in subsurface layer along the 100 m isobath which is characterized by density gradient of o 10 4 kg m 4 and vertical eddy diffusivity of o 10 5 10 4 m2 s 1 the kinematic deformation term sdef ageostrophic advection term sadv and vertical mixing forcing term smix are calculated from the observations their distribution patterns are featured by banded structure that is alternating positive negative alongshore bands distributed in the cross shelf direction correspondingly alternating upwelling and downwelling bands appear from the coast to the deep waters the maximum downward velocity reaches 5 10 5 m s 1 within the frontal zone accompanied by the maximum upward velocity of 7 10 5 m s 1 on two sides the dynamic diagnosis indicates that sadv

groundwater quality assessment and its suitability in celtikci plain burdur turkey the celtikci burdur plain is located in the southwest of turkey and is a semi closed basin groundwater is densely used as drinking irrigation and domestic water in the plain hydrogeochemical processes controlling groundwater chemistry and geochemical assessment of groundwater were investigated in the celtikci burdur turkey plain in this study groundwater samples for two seasons were analyzed and major ion chemistry of groundwater was researched to understand the groundwater geochemistry two major hydrochemical facies ca hco3 and ca mg hco3 were determined in the area various graphical plots and multivariate statistical analysis were used for identifying the occurrence of different geochemical processes in the study area weathering is one of the key geochemical processes which controlled the solute concentration in groundwater chemical indexes such as sodium adsorption ratio na residual sodium carbonate magnesium hazard and permeability index were calculated and results show that groundwater is suitable for irrigation purpose except for permeability index values concentrations of mn no3 and total hardness exceed the prescribed limits of who and are the major limiting parameters of groundwater use for potable and domestic purposes

chemical and isotopic characteristics of the euphrates river water syria factors controlling its geochemistry hydrochemical parameters and stable isotope 18o and 2h ratios were monitored at 10 stations along the euphrates river er within the syrian reach during 2004 2006 the average concentrations of major ions in the er were comparable to those of semi arid and arid zone rivers temporal variations of major ion concentrations were small at the first two upper sites and more pronounced at the lower downstream stations temporal fluctuations of stable isotope ratios at the first two upper sites were identical and have a distinct opposite evolution trend to those of the remaining downstream stations with depleted values during summer autumn and enriched values during february may salinity and stable isotope values of the er systemically increase with the distance downstream with sharp enrichments in stable isotope values at al assad lake primarily because of evaporation from the lake the chemical and isotopic properties of the er water suggest negligible role of precipitation and local runoff compared with evaporation cluster analysis in q mode resulted in classifying the major ions into the most predominant species so42 hco3 cl ca2 and na liberated as a result of rock water interactions or dissolution of soluble evaporate salts and the less abundant ions mg2 k no3 and sio2 partially imported from different sources rainfall silicate weathering and anthropogenic pollution factor analysis suggests that the geochemistry of the er water is mainly controlled by four factors rock weathering or salt dissolution dissolved co2 partial pressure water temperature t and evaporation these factors explain more than 80 of the total variance in the data matrix

dolomite reservoirs porosity evolution and reservoir characteristics systematic analyses of the published record of dolomite reservoirs worldwide reveal that the majority of hydrocarbon producing dolomite reservoirs occurs in 1 peritidal dominated carbonate 2 subtidal carbonate associated with evaporitic tidal flat lagoon 3 subtidal carbonate associated with basinal evaporite and 4 nonevaporitic carbonate sequence associated with topographic high unconformity platform margin buildup or fault fracture reservoir characteristics vary greatly from one dolomite type to another depending upon the original sediment fabric the mechanism by which dolomite was formed and the extent to which early formed dolomite was modified by postdolomitization diagenetic processes e g karstification fracturing and burial corrosion this paper discusses the origin of dolomite porosity and demonstrates the porosity evolution and reservoir characteristics of different dolomite types

tropical cyclone enhanced vertical transport in the northwestern south china sea i mooring observation analysis for washi 2005 abstract using mooring observed horizontal velocities and temperature from july 28 to august 2 2005 this study analyzes the temporal vertical variation of the diagnostic vertical velocity and mass transport during passage of tropical storm washi 2005 over the northwestern continental shelf of the south china sea scs the results show that the total vertical velocity is of the order of o 1 10 4 m s 1 in the mixed layer above 25 m and of o 1 10 5 m s 1 in the lower layer dynamically the geostrophic advection and unsteady behavior of density induced by near inertial oscillation are dominant factors in the upper and lower layers respectively as tropical storm washi 2005 passed by from july 29 to 31 2005 the upward vertical velocity was dominant and significantly enhanced to the order of o 1 10 3 m s 1 the diagnosed vertical velocity in the upper layer is one order greater than the averaged ekman pumping velocity which occurred one day earlier the vertical advection transport calculated from the diagnosed vertical velocity reaches o 1 10 5 kg s 1m 3 one order greater than that induced by turbulent mixing time averaged transports by vertical advection and mixing are both upward in the layer above the thermocline during the storm passage

hydrogeochemical characterization and quality assessment of groundwater around umrer coal mine area nagpur district maharashtra india quality assessment as well as hydrogeochemical characterization of 45 representative groundwater samples around umrer coal mine area was undertaken the ph of the water lies in the normal range i e from 7 5 to 8 5 the electrical conductivity varies from 826 to 1 741 the total hardness varies from 289 to 1 302 and the tds values range from 528 6 to 1 114 2 mg l which reflects variation in lithology and thus the distinction in hydrogeological regime the cation chemistry is dominated by ca2 and mg2 while anion chemistry is dominated by cl and hco3 out of total ten hydrochemical facies the two dominant facies are mg ca hco3 37 7 and ca mg so4 hco3 17 7 the groundwater in the study area in general is useful for drinking and domestic use however it has marginal utility for irrigation purpose standard us salinity laboratory classification shows that water of the study area belongs to c2 s1 and c3 s1 classes the concentration of 9 trace elements analysed from 18 samples did not exceed the desirable limit

hydrochemistry of reservoirs of damodar river basin india weathering processes and water quality assessment water samples collected from the six reservoirs of damodar river basin in pre and post monsoon have been analysed to study the major ion chemistry and the weathering and geochemical processes controlling the water composition ca na and hco3 dominate the chemical composition of the reservoir water the seasonal data shows a minimum concentration of most of the ions in post monsoon and a maximum concentration in pre monsoon seasons reflecting the concentrating effects due to elevated temperature and increased evaporation during the low water level period of the pre monsoon season water chemistry of the reservoirs strongly reflects the dominance of continental weathering aided by atmospheric and anthropogenic activities in the catchment area higher concentration of so4 and tds in panchet durgapur and tenughat reservoirs indicate mining and anthropogenic impact on water quality the high contribution of ca mg to the total cations high concentration of dissolved silica relatively high na k tz ratio 0 3 and low equivalent ratio of ca mg na k suggests combined influence of carbonate and silicate weathering kaolinite is the possible mineral that is in equilibrium with the water implying that the chemistry of reservoir water favours kaolinite formation the calculated values of sar rsc and sodium percentage indicate the excellent to good quality of water for irrigation uses

dolomite occurrence evolution and economically important associations abstract dolomite is not a simple mineral it can form as a primary precipitate a diagenetic replacement or as a hydrothermal metamorphic phase all that it requires is permeability a mechanism that facilitates fluid flow and a sufficient supply of magnesium dolomite can form in lakes on or beneath the shallow seafloor in zones of brine reflux and in early to late burial settings it may form from seawater from continental waters from the mixing of basinal brines the mixing of hypersaline brine with seawater or the mixing of seawater with meteoric water or via the cooling of basinal brines bacterial metabolism may aid the process of precipitation in settings where sulfate reducing species flourish and microbial action may control primary precipitation in some hypersaline anoxic lake settings dolomite is a metastable mineral early formed crystals can be replaced by later more stable phases with such replacements repeated a number of times during burial and metamorphism each new phase is formed by the partial or complete dissolution of an earlier dolomite this continual re equilibration during burial detracts from the ability of trace elements to indicate depositional conditions and resets the oxygen isotope signature of the dolomite at progressively higher temperatures because subsurface dolomite evolves via dissolution and reprecipitation a bed of dolomite can retain or create porosity and permeability to much greater burial depths and into higher temperature realms than a limestone counterpart dolomitization also creates new crystals with new rhomb growth following the dissolution of less stable precursors repetition of this process without complete pore cementation can generate intercrystalline porosity a number of times in the rock s burial history intercrystalline porosity is a highly interconnected style of porosity that gives dolomite reservoirs their good fluid storage capacity and efficient drainage the fact that many dolomite reservoirs formed via brine reflux means that they sit beneath an evaporite seal in both platform and basinwide evaporite settings the same association of evaporites sulfate source and entrained hydrocarbons means that burial conditions are also suitable for thermochemical sulfate reduction and the precipitation of base metals this tends to occur at higher temperatures 60 c 80 c and so the resulting dolomites tend to be ferroan and consist of saddle shaped crystals

geochemical factors controlling the chemical nature of water and sediments in the gomti river india r mode factor analysis of the recently acquired data on water and sediment chemistry has been performed basic chemical parameters have been merged together which aid in interpreting a few empirical geochemical factors controlling the chemical nature of water and sediments of the gomti river a major himalayan tributary of the ganges drainage basin water chemistry seems to be controlled by three factors bicarbonate rainfall and silicate and phosphate factors sediment chemistry is largely controlled by the following four factors clay adsorption desorption fe mn hydroxide and mercury factors these factors show spatial and temporal variability in terms of their r scores

uranium depletion across permian triassic boundary in persian gulf and its implications for paleooceanic conditions abstract high resolution uranium analyses as well as oxygen carbon and strontium isotopes data through permian triassic boundary ptb in the marine sections of three offshore wells in persian gulf are illustrated in this paper a decreasing trend in u content from upper permian strata toward the ptb is recorded in all wells such a trend could not be adequately explained by the facies changes diagenetic events salinity variations dolomitization or total organic carbon toc content of the samples distinct and negative uranium anomalies coincide with the onset of the carbon isotope shifts which might indicate influx of anoxic waters the th u ratios below the ptb in the studied sections are mainly less than 2 reinforcing this possibility reducing conditions associated with the anoxia would have gradually increased the rate of u fixation on the deep sea floor resulting in low u concentration in the shallow water carbonates a negative 18o shift of about 4 could be seen at the ptb in all studied wells such excursion indicates a meteoric diagenesis below the boundary also abnormally higher 87sr 86sr ratios below the ptb indicate significant input of radiogenic 87sr during subaerial exposures at the end of permian this palaeoexposure surface is also reflected in depleted oxygen isotope values of this interval biostratigraphic studies also show that some important guide forms of late permian are absent in studied wells that could be due to several factors including non sedimentation subaerial exposure and erosion thus a near surface meteoric realm or emergent surface could be considered for the ptb in studied wells

multisatellite observation on upwelling after the passage of typhoon hai tang in the southern east china sea 1 the serial remote sensing based imageries clearly revealed large scale of upwelling within large regional enhancement of chlorophyll a chl a concentration in the southern east china sea ecs after the passage of super typhoon hai tang in july 2005 after the typhoon on 22 july the upwelling area 3 0 mg m3 appeared in the shelf region where the high chl a pattern matched the upwelling in terms of location and time on the other hand a large offshore sst cooling was also observed mainly to the right of typhoon track on 20 july it lasted in a period of 2 3 days this paper provides clear and high resolution evidence that typhoon significant increased upwelling and chl a concentration in the southern ecs

monitoring surface elevation changes in jharia coalfield india using synthetic aperture radar interferometry this paper investigates surface elevation changes that occurred during 1996 2004 in the jharia coalfield through the digital elevation model dem generated using synthetic aperture radar interferometry insar using ers 1 2 european remote sensing satellite tandem and radarsat 1 data the comparison of elevation values derived from the insar dem and topographic height data shows a bias of 23 08 m with root mean square error of 2 31 m 5 8 the accuracy of the dem was investigated by comparing the elevation profiles with the digitized elevation contour data at four different locations the profile comparison shows a mean bias of 22 68 m local topography shows changes in elevation up to 40 00 m due to mining activities on the 8 year time period the results of insar derived heights and topographic heights were comparable and well matched except at a few locations where topographic data were unavailable dem generated using insar due to its high spatial details is ideal for the detection and estimation of surface elevation changes in mining areas

vertical flow in the southern ocean estimated from individual moorings abstractthis study demonstrates that oceanic vertical velocities can be estimated from individual mooring measurements even for nonstationary flow this result is obtained under three assumptions i weak diffusion peclet number 1 ii weak friction reynolds number 1 and iii small inertial terms rossby number 1 the theoretical framework is applied to a set of four moorings located in the southern ocean for this site the diagnosed vertical velocities are highly variable in time their standard deviation being one to two orders of magnitude greater than their mean the time averaged vertical velocities are demonstrated to be largely induced by geostrophic flow and can be estimated from the time averaged density and horizontal velocities this suggests that local time mean vertical velocities are primarily forced by the time mean ocean dynamics rather than by for example transient eddies or internal waves it is also shown that in the context of these four moorings the time mean ver

gas souring by thermochemical sulfate reduction at 140 c reply natural gas in the permian triassic khuff formation of abu dhabi contains variable amounts of h2s gas souring occurred through thermochemical sulfate reduction of anhydrite by hydrocarbon gases sour gas is observed only in reservoirs hotter than a critical reaction temperature 140 c petrographic examination of core from a wide depth range showed that the anhydrite reactant has been replaced by calcite reaction product only in samples deeper than 4300 m gas composition data show that only reservoirs deeper than 4300 m contain large quantities of h2s i e 10 at present day geothermal gradients 4300 m is equivalent to 140 c fluid inclusion analysis of calcite reaction product has shown that calcite growth only became significan at temperatures greater than 140 c thus three independent indicators all show that 140 c is the critical temperature above which gas souring by thermochemical sulfate reduction begins the previously suggested lower temperature thresholds for other sour gas provinces 80 130 c derive from gas composition data that may not allow adequately either for the reservoir temperature history or for the migration of gas generated at higher temperatures into present traps conversely published proposals for higher threshold temperature 180 200 c derive from short duration experimental data that are not easily extrapolated to geologically realistic temperatures and time scales therefore the temperature of 140 c derived from our study of the khuff formation may be th best estimate of temperature required for in situ thermochemical sulfate reduction to produce the high h2s concentrations encountered in deep carbonate gas reservoirs

the indus river system india pakistan major ion chemistry uranium and strontium isotopes the indus river is one of the large river systems draining the himalaya we report in this paper the major ion chemistry sr and u isotope systematics of the indus system particularly its headwaters the results show that 1 on an average about a third of the cations in the waters can be from silicate weathering however most of the ca mg is likely to be from the weathering of carbonates and evaporites 2 the 87sr86sr of the waters ranges between 0 7085 and 0 7595 the higher values 0 72 are typical of the tributaries draining the precambrian granite gneissic terrains the 87sr86sr of the indus main channel throughout its entire stretch shows only minor variations 0 7104 0 7116 the indus transports 8 8 106 mol sr to the arabian sea annually with a 87sr86sr of 0 7111 if our results of sr concentration and 87sr86sr measured at thatta can be considered typical of the indus throughout the year and 3 the u concentration in the indus and its tributaries is generally high 0 37 10 3 g 1 1 the source for the high uranium can be the weathering of granites zones of uranium mineralisation and black shales the indus results when compared with our earlier data on the ganga brahmaputra show that in all these three river systems carbonate weathering is the dominant source of ca mg and hco3 and that u concentrations are high in the case of 87sr86sr the indus waters are less radiogenic however its tributaries draining the precambrian granites gneisses have 87sr86sr in excess of 0 72 similar to that in the rivers of the ganga system the low 87sr86sr of the indus 0 7111 suggests that its contribution to the sr isotope evolution of oceans since the cenozoic is less significant than that of the ganga brahmaputra

an unusual muddy epeiric carbonate reservoir the lower muschelkalk middle triassic of the netherlands the mud dominated lower muschelkalk carbonates middle triassic are a unique reservoir currently producing gas in the dutch de wijk field numerous gas shows scattered over the netherlands onshore and offshore suggest further currently unrecognized potential this study complements an extensive subsurface data set with selected outcrop information to localize missed opportunities and evaluates the factors controlling the development of this unusual reservoir type the muddy carbonates are deposits of a storm dominated epeiric carbonate ramp with negligible depositional gradient different marlstone dolomudstone and lime mudstone facies types reflect the low energy coastal plain to inner ramp and higher energy midramp to proximal outer ramp depositional environments the best reservoir facies is recognized in distal inner ramp algal dolomudstones porosity up to 24 and permeability up to 32 md because of the variable intensity of early facies related diagenesis the reservoir quality of dolomudstones decreases markedly in landward and seaward direction from the distal inner ramp the stacking of decimeter to meter thick reservoirs is reflected by a fourfold hierarchy of depositional cycles that can largely be recognized with conventional wire line logs high resolution outcrop and subsurface correlations reveal that stacks of thin bedded reservoir units most probably pinch out within a few kilometers and that their lateral continuity should not be overestimated despite the epeiric layer cake setting local reservoir occurrences are commonly situated above paleohighs of tectonic or halokinetic origin not only the reduced thickness of the lower muschelkalk above these paleohighs but also the presence and lateral extent of local reservoirs might be detected with seismic data the general facies and reservoir patterns exemplified by the lower muschelkalk may also be of use for reservoir prediction in similar epeiric settings elsewhere for instance in the middle east

the influence of rock fabric and mineralogy on thermochemical sulfate reduction khuff formation abu dhabi abstract thermochemical sulfate reduction tsr is the reaction between anhydrite and petroleum fluids at elevated temperatures to produce h2s and calcite in this study of the dolomite hosted hydrocarbon gas reservoirs in the permo triassic khuff formation abu dhabi a geochemically well constrained rock gas system we demonstrate for the first time a clear influence of rock texture and mineralogy on the rate and extent of tsr reactions and thus on h2s concentration in the gas phase the controls on the rate on h2s accumulation were tsr reaction kinetics tsr became significant as temperature exceeded 140 c a critical threshold temperature for chemical reaction between aqueous sulfate and aqueous methane anhydrite dissolution rate once initiated the subsequent reaction rate was controlled by the rate of supply of aqueous sulfate to the reaction site sulfate limitation is indicated by the lack of fractionation of sulfur isotopes between sulfate and sulfide i e suggesting total reaction for each unit of sulfate that dissolves also finely crystalline anhydrite began reacting at a lower temperature than coarse crystalline anhydrite likely a result of relative surface area suggesting that anhydrite dissolution was the rate limiting step transport rates are unlikely to have been rate limiting at the earliest stage of reaction because anhydrite was replaced in situ by calcite on the very edges of anhydrite nodules and crystals transport rate later as tsr proceeded it became transport controlled as calcite growing on the surface of anhydrite crystals began to isolate them from dissolved methane tsr ceased once calcite had effectively armor plated totally isolated the remaining anhydrite finely crystalline anhydrite underwent more extensive and more rapid tsr than coarser anhydrite crystals because these had a greater ratio of surface area to volume allowing more and faster dissolution and requiring more calcite to isolate them from methane localized loss of h2s occurred in the reservoir by reaction with indigenous fe bearing clays consequently reservoirs with a relatively high siliciclastic content have less h2s than would be expected from the advanced state of anhydrite replacement by calcite in order to predict tsr related h2s concentration in hydrocarbon gases it is thus important to understand the diagenetic and textural characteristics of the reservoir as well as the thermal and petroleum emplacement history

evaluation of hydrogeochemical processes and groundwater quality in the jhansi district of bundelkhand region india a base line study involving analysis of groundwater samples from the jhansi district were carried out to determine the major and trace element chemistry and to assess the hydrogeochemical processes and water quality for domestic and irrigation uses study results show that groundwater is mildly acidic to alkaline in nature and hco3 cl ca2 na and mg2 are the major contributing ions for the dissolved loads the data plotted on the gibbs and piper diagrams reveal that the groundwater chemistry is mainly controlled by rock weathering with secondary contribution from anthropogenic sources in a majority of the groundwater samples alkaline earth metals exceed alkalies and weak acid dominate over strong acids ca mg hco3 is the dominant hydrogeochemical facies in the majority of the groundwater samples the computed saturation indices demonstrate that groundwater is oversaturated with respect to dolomite and calcite kaolinite is the possible mineral that is in equilibrium with the water implying that the groundwater chemistry favors kaolinite formation a comparison of groundwater quality parameters in relation to specified limits for drinking water shows that the concentrations of tds f no3 total hardness and fe are exceeding the desirable limits in many water samples quality assessment for irrigation uses reveal that the groundwater is of good to suitable category higher salinity and residual sodium carbonate values at some sites restrict the suitability of groundwater and need an adequate drainage and water management plan for the area

multimodal structure of the internal tides on the continental shelf of the northwestern south china sea based on the moored current and temperature observations during the summer of 2005 the vertical structure of the internal tides on the continental shelf of the northwestern south china sea scs is studied the vertical structure of the internal tides was found to differ greatly between semidiurnal and diurnal constituents generally the diurnal constituents are dominated by the first mode motions which are consistent with the overwhelming first mode signals in the northeastern scs in contrast the semidiurnal internal tides unlike the predomination of the first mode variations in the northeastern area exhibit a higher modal structure with dominate second mode signals in the observational region moreover although the diurnal internal tides are much stronger than the semidiurnal component the shear caused by the latter over various scales was found to be significant compared to that induced by the diurnal tides probably due to the superposition of the first mode and higher mode smaller scale semidiurnal variations further analysis demonstrates that the shear induced by the diurnal internal tides is larger than that induced by the semidiurnal variations around 45 m depth where the first mode current reversal in the vertical happens while below 45 m depth higher mode semidiurnal internal tides generally produce larger shear than that by the diurnal component the northwest propagating semidiurnal internal tides of higher mode with small vertical scale probably do not originate from a distant source like luzon strait but were likely generated near the experiment site c 2011 elsevier ltd all rights reserved

summer upwelling and thermal fronts in the northwestern south china sea observational analysis of two mesoscale mapping surveys persistent coastal upwelling and upwelling induced thermal fronts in the northwestern south china sea are investigated using satellite measurements two intensive mesoscale mapping surveys and three bottom mounted adcps the results indicate that pronounced surface cooling and upwelling related fronts with a width of 20 50 km occur around hainan island and persist through the summer upwelling season driven by the prevailing southwesterly monsoon the subsurface cooling band is approximate to 6 degrees c colder than the water offshore of the east coast where the thermal gradients are generally more than 0 1 degrees c km the cold and nutrient rich coastal water is identified to be derived primarily from the deep water of the outer shelf at the same time the spatial structure of the upwelling and thermal front as well as the upwelling related coastal currents is significantly regulated by wind forcing a prominent lagged correlation between the moored temperature records and alongshore wind stress is detected in the east coast the correlation coefficient is 0 8 with the temperature lagging behind wind stress by 2 2 days indicating that the cooling band off the east coast is dominated mostly by the alongshore southwesterly monsoon during the upwelling season

biotic carbonate precipitation inhibited during the early triassic at the rim of the arabian platform oman abstract sedimentological palaeontological and geochemical data of a 152 m thick composite section of the saiq formation were used to describe the facies associations and the nature of carbonate precipitation during the late permian early triassic at the eastern rim of the arabian platform sultanate of oman saih hatat wadi aday changhsingian late permian platform carbonates dominated by bryozoans brachiopods and crinoids are truncated by a mineralized discontinuity surface the disappearance of permian calcified metazoans a negative 13ccarb excursion and a sharp facies contrast collectively suggest that the permian triassic boundary lies in this interval unfossiliferous siliciclastics with nodules of iron and manganese minerals on top of the unconformity were probably deposited during a phase when sea water was undersaturated with respect to calcium carbonate after a gap late dienerian carbonate deposition started with abiotically precipitated lime mudstone and biotically induced microbialites having the lowest observed 13ccarb values facies association a further up 1 2 m of bioclastic wacke and grainstones with a positive 13ccarb excursion indicate a short lived interval of biotically controlled carbonate precipitation facies association b the overlying sequence of siliciclastics laminated or bioturbated dolomitized mudstone microbialites dolomitic siltstone and black calcite which is characterized by a 2nd negative 13ccarb shift marks the return to biotically induced carbonate precipitation facies associations c d the recrystallized black calcite at the top of the sequence is capped by a thick palaeosol and overlain by late early to middle triassic cycles consisting of biotically precipitated carbonate the facies development of the rim of the arabian platform differs from that of the interior in having a pronounced discontinuity at the permian triassic boundary and an early triassic bioclastic carbonate unit sandwiched between abiotically precipitated carbonates the observed lateral changes in carbonate precipitation across the arabian platform could have been caused by changes in oceanic circulation such as episodic upwelling of deep water

uranium depletion across the permian triassic boundary in middle east carbonates signature of oceanic anoxia we present a geochemical profile through a 445 m 1459 9 ft section of shallow water carbonate platform strata in the upper part of the khuff formation the permian triassic boundary ptb is recognized in this section based on the immediately preceding negative shift in bulk rock carbonate carbon isotope composition equivalent to the end permian extinction horizon combined with biostratigraphic control from nearby wells these strata show an abrupt and long lasting decrease in bulk rock uranium u content coincident with the carbon isotope shift because of low siliciclastic content and the consequently low potassium and thorium of these carbonates the decrease in u is clearly reflected in the total gamma ray gr profile recorded by wire line logging published log curves show similar distinctive gr profiles throughout a large area of the middle east indicating that u depletion across the ptb is a regional characteristic this feature cannot be explained as diagenetic and is not related to the organic matter content of the host sediments but it is suggested to reflect the global depletion of u in earliest triassic seawater caused by the abrupt onset of deep ocean anoxia and the resulting increase in u precipitation in oxygen poor sediments this explanation carries the implication that similar u depletion should be characteristic of lowermost triassic carbonates from shallow water oxygenated settings worldwide analogous signatures of u depletion should also have developed in shallow water carbonates deposited contemporaneously with episodes of deep ocean anoxia during other periods of geological time these predictions can be tested by high accuracy u profiling of other well characterized carbonate successions potentially yielding a new approach for tracking the degree of oceanic circulation throughout earth s history

structural geology of the rub al khali basin saudi arabia the rub al khali basin lies below a quaternary sand sea and the structural evolution from the late precambrian to neogene is known only from reflection seismic gravity and magnetic data and wells gravity and magnetic data show north south and northwest southeast trends matching mapped precambrian faults the deepest structures imaged on reflection seismic data are undrilled precambrian rifts filled with layered strata at depths up to 13 km the distribution of ediacaran cambrian ara hormuz mobile salt is restricted to an embayment in the eastern rub al khali the precambrian rifts show local inversion and were peneplained at base phanerozoic a broad crustal scale fold qatar arch developed in the carboniferous and amplified in the late triassic separating subbasins in the west and east rub al khali a phase of kilometer scale folding occurred in the late cretaceous coeval with thrusting and ophiolite obduction in eastern oman these folds trend predominantly north south oblique to the northwesterly shortening direction and occasionally have steep fault zones close to their axial surfaces the trend and location of these folds closely matches the precambrian lineaments identified in this study demonstrating preferential reactivation of basement structures compression along the zagros suture reactivated these folds in the neogene this time the result of highly oblique north northeast to south southwest shortening cretaceous tertiary fold style is interpreted as transpression with minor strain partitioning permian jurassic and eocene evaporite horizons played no role in the structural evolution of the basin but the eocene evaporites caused widespread kilometer scale dissolution collapse structures in the basin center

geochemical alterations in surface waters of govind ballabh pant sagar northern coalfield india major ions showed high concentrations ionic strength and chemical activity in the surface waters of govind ballabh pant sagar reservoir various geochemical ratios showed the dominance of silicate over carbonate weathering and major ions such as na k account for about 52 of the cation budget the high na and k showed sedimentation of rock coal particles consisting of highly weathered silicate minerals contributed by the discharge of mine water fly ash mixing during transportation etc further ca2 mg2 na k ratio was 1 0 92 indicating the occurrence of silicate weathering in the reservoir catchment the comparative assessment showed that the proportion of ca2 mg2 na k tends to be lower along the coal mining belts compared to non coal mining regions in the world the ca2 so4 2 ratio 1 revealed not only h2co3 but h2so4 also acting as a source of protons for rock weathering the cause underlying these differences can be related directly to geological substrate and anthropogenic activities

diagnosing mesoscale vertical motion from horizontal velocity and density data the mesoscale vertical velocity is obtained by solving a generalized omega equation equation using density and horizontal velocity data from three consecutive quasi synoptic high resolution surveys in the alboran sea the atlantic jet aj and the northern part of the western alboran gyre wag were observed as a large density anticyclonic front extending down to 200 230 m the horizontal velocity uh in the aj reached maxima of 1 2 m s 1 for the three surveys with extreme rossby numbers of f 0 9 in

upper ocean response to typhoon kalmaegi 2014 typhoon kalmaegi passed over an array of buoys and moorings in the northern south china sea in september 2014 leaving a rare set of observations on typhoon induced dynamical and thermohaline responses in the upper ocean the dynamical response was characterized by strong near inertial currents with opposite phases in the surface mixed layer and in the thermocline indicating the dominance of the response by the excitation of the first baroclinic mode the thermohaline response showed considerable changes in the mean fields in addition to a near inertial oscillation in particular temperature and salinity anomalies generally exhibited a three layer vertical structure with the surface layer becoming cooler and saltier the subsurface layer warmer and fresher and the lower layer cooler and saltier again the response in the surface and subsurface layers was much stronger to the right of the typhoon track while that in the lower layer was stronger along the track and to the left these features of the upper ocean response were grossly reproduced by a three dimensional numerical model a model based heat budget analysis suggests that vertical mixing was mainly responsible for the surface cooling and subsurface warming while upwelling was the cause of cooling from below both observations and model results indicate that the whole upper ocean experienced an overall cooling in the wake of typhoon kalmaegi

holocene coastal carbonates and evaporites of the southern arabian gulf and their ancient analogues abstract the holocene sediments of the coast of the united arab emirates in the southeastern arabian gulf are frequently cited in the literature as type examples for analogous assemblages of carbonates evaporites and siliciclastics throughout the geologic record this paper is intended as a convenient single source for the description of sediments of this region providing information on how to reach the classic localities and some of the analogs the holocene sediments of the region accumulate over an area that is 500 km long and up to 60 km wide the sediments collecting offshore are predominantly pelecypod sands mixed with lime and argillaceous mud with these latter fine sediments increasing as the water deepens the pelecypod rich sediments also collect east of abu dhabi island both in the deeper tidal channels between the barrier island lagoons and in deeper portions of the protected lagoons west of abu dhabi island the shallow water margin is the site of coral reefs and coralgal sands whereas to the east oolites accumulate on the tidal deltas of channels located between barrier islands grapestones accumulate to the lee of the reefs and the oolite shoals where cementation becomes more common they are particularly common on the less protected shallow water margins of the lagoons west of abu dhabi island pelleted lime muds accumulate in the lagoons in the lee of the barrier islands of the eastern abu dhabi lining the inner shores of the protected lagoons of abu dhabi and on other islands to the west are cyano bacterial mats and mangrove swamps landward of these a prograding north facing shoreline is formed by supratidal salt flats sabkhas in which evaporite minerals are accumulating this paper describes the localities associated with 1 the mangrove swamps of the west side of the al dhabaiya peninsula 2 the indurated cemented carbonate crusts cyanobacterial flats and sabkha evaporites on the shore of the khor al bazam south of qanatir island 3 the reef and oolitic sand flats on the coast just east of jebel dhana and 4 the marine travertine and aragonite coats associated with the beach sediments in a small bay south of jebel dhana and 5 the sabkha mutti between jebel barakah and al sila similar sedimentological associations of carbonate and evaporites to those of the holocene of the united arab emirates are to be found in the tertiary and mesozoic sedimentary rocks of the immediate subsurface in the arabian gulf other analogs to this setting include the paleozoic carbonates of the western usa europe and asia mesozoic carbonates of the gulf of mexico europe and middle east and tertiary sedimentary rocks in the middle east

facies and sedimentary environment of the permian carbonates khuff formation in the united arab emirates abstract the late permian to early triassic khuff formation of the united arab emirates is a 625 970 m thick sequence of shallow water carbonates dolomites limestones and dolomitic limestones with subordinate anhydrite it can be subdivided into ten facies units distinguished on the basis of their depositional textures that represent an overall regressive carbonate evaporite sequence based on the paleoecology sedimentary structures and lithology four distinct depositional settings can be recognized supratidal sabkha lagoon shoal and shallow shelf the khuff formation has both primary interparticle and secondary dissolution vugs and intercrystalline porosities

hydrogeological and environmental impact of coal mining jharia coalfield india the jharia coalfield is the most important and active minig region it experiences groundwater inflow and affects groundwater levels in overlying aquifers and it provides the basis for a conceptual model of the hydrogeological impacts of coal mining the several sandstone aquifers of the overburden are separated by aquitards that limit vertical hydraulic connection but the inflow responds to seasonal events and seems to be linked to shallow groundwater behavior the mine drainage behavior suggests a hydraulic connection between the mine and the shallower groundwater system the greatest declines are directly above the panels with an immediate response to coal mining the inflow is localized by natural and induced fracture zones and is mostly into recent workings the groundwater behavior is controlled by hydraulic property changes caused by mine induced fracturing the hydrological and chemical qualities of the shallow groundwater regime in 13 mining collieries in mukunda block have been investigated water samples collected from 30 shallow monitoring dug wells were chosen for the study rainfall runoff and infiltration rates have been calculated in the area the water quality plottings were used to interpret the distribution of individual chemical parameters and in predicting the water quality the underground mine water has been classified as 1 unconfined groundwater in the calcareous siltstone and sandstone its composition is na ca so4 and na mghco3 with moderate total dissolved solids tds 200 1480 ppm 2 the deep groundwater originating from the coal seams and associated sediments in the near surface environments this is a na hco3 water with higher tds and 3 spoil dump waters are essentially na hco3 with high tds this article presents some hydrologic results and conclusions relating to the hydrogeological and environmental impacts of the coal mining in the jharia coalfield

modelling potential hydrological impact of abandoned underground mines in the monday creek watershed ohio abandoned underground mines aum have caused dramatic environmental effects that are closely linked to regional sustainability this paper explores the potential hydrological impact of aum in the monday creek watershed a typically mined area in appalachian region using the soil and water assessment tool swat 2005 model and sequential uncertainty fitting sufi 2 calibrated at both the global and local scales the locally calibrated model better incorporates those key parameters relevant to aum for specific sub basins and hydrologic response units data from the years 2003 2004 were used for calibration and 2005 2006 for validation the results were quite satisfactory both the coefficient of determination r2 and the nash sutcliffe efficiency statistic were over 0 80 the potential influences of aum were assessed by modelling an alternative scenario assuming no aum for the period 2003 2009 results show that the hydrological process of lateral subsurface flow plays a dominant role in linking aum to overall watershed hydrology the potential hydrological impact of aum is an increased annual lateral flow of 82 1 and a decrease in annual surface flow by 15 leading to an increase of 16 9 in annual water yield for the monday creek watershed the seasonal fluctuation of water yield has a similar trend to lateral flow decreasing from march to august and increasing from august to january higher volume higher flow peaks and higher recession constants characterized the hydrograph of daily streamflow from aum the results indicate that more emphasis should be put on lateral flow for further study of acid mine drainage and flooding control in those watersheds with aum copyright 2012 john wiley sons ltd

growth and dissipation of typhoon forced solitary continental shelf waves in the northern south china sea this study aims to gain insight into the sea level response to typhoon in the northern south china sea using typhoon records from 1978 to 1997 simultaneous tidal gauge records and satellite altimeter along track sea level data we find that the ocean sea level response signatures in the deep water agree well with a single sea level soliton of which the average soliton amplitude is 34 6 cm and the average characteristic half width is 115 12 km evolution of the single soliton as propagating across a shoaling bottom topography obeys solutions of the perturbed korteweg and de vries equation the solutions reveal that forced by the hyperbolic tangent shaped topography the single soliton evolves to a solitary wave packet consisting of a large leading soliton and smaller following waves in an oscillatory tail as approaching the shallow water this phenomenon is verified by observed sea level signatures of 19 storm surges the correlation coefficient between theoretical solution and observations is as high as 0 91 meanwhile the soliton amplitude grows with a soliton amplitude growth ratio sagr which depends on the deep water and shallow water depths however without consideration of viscous effects the sagr model overestimates the soliton amplitude growth thus the vorticity equation for viscous fluid is adopted to solve this issue the results indicate that turbulent viscosities are responsible to soliton amplitude decay concurring with the growth and causes dependence of the storm surge amplitude on the typhoon incident angle

wind and topography influence on an upwelling system at the eastern hainan coast 1 during the summer monsoon an upwelling dominates east of hainan island which can be observed by means of field studies and satellite sea surface temperature images the centers of cold water at the surface always show a strong patchiness a 3 d high resolution model is applied to study the impact of the topography on the wind driven upwelling system the experiments show that the upwelling favoring wind is the main driving force and we concluded that the formation of the centers of cold water at the surface significantly depends on the strength of southwesterly and southerly winds moreover the internal waves are generated at the shelf break representing the most prominent interaction between inner shelf and open ocean the alongshore topographic variations play an important role in the distribution of the upwelling centers this combined effect of wind and topography leads to the following processes 1 when the southwesterly or southerly wind is strong enough topographic variations cause upwelling centers at the downstream side of topographic high and a downwelling center at the upstream side which in turn lead to density variations 2 these density variations cause additional pressure gradients which advect the upwelling centers toward the northeast 3 a longer period of upwelling favorable winds support the advection processes which cause an enlargement of the cold water centers all these processes together can explain the observed uneven distribution of upwelling centers

the 2009 jiweishan rock avalanche wulong china precursor conditions and factors leading to failure abstract this study investigates the predisposing geological and anthropogenic factors and indicative precursors preceding the fatal 5 june 2009 jiweishan rock avalanche it began as a rockslide and transformed into a rock avalanche that killed 74 people and caused major property loss due to misdiagnosis of the failure mode and underestimation of volume and travel distance besides topography structure and stratigraphy that favoured failure mining below the failed rock mass had changed the state of stress and altered groundwater flow the anthropogenic factors caused deformation and accelerated failure of the slope and therefore were important contributions cracks and a karstic zone had developed along regional joints and defined several boundaries of the failed rock mass furthermore a 2 m wide crack developed since 1958 revealed a potential basal failure surface at the contact between karstic limestone and an underlying pre sheared thin shale aquiclude increasing magnitude and frequency of rockfalls and tension cracks at the front end of the sliding block appeared three days before the event and implied the likely movement direction of the sliding rock mass these could have warned of a developing giant failure topography included a large elevation difference between the toe of the failure surface and the cliff base a narrow valley to channel debris and the steep gradient of the downstream tiekuang creek could have suggested that failure might lead to a rapid and long runout rock avalanche however access to the densely vegetated source area before the failure was difficult and local investigators did not have all of the evidence that might have led them to recognize that potential danger was more than continuing rockfalls