evaporites and siliciclastics of the permian nippewalla group of kansas usa a case for non marine deposition in saline lakes and saline pans the mid permian nippewalla group of kansas consists of bedded evaporites red bed siliciclastics and grey siliciclastics deposited in a non marine environment lithologies and sedimentary features indicate lacustrine and aeolian deposition subaerial exposure and palaeosol formation grey siliciclastic mudstones characterized by planar and convolute laminations ostracods peloids and plant material represent a freshwater brackish perennial lake facies bedded anhydrites containing gypsum crystal pseudomorphs clastic anhydrite grains and grey mud drapes and partings suggest deposition in saline lakes bedded halites consist of chevron and cumulate crystals dissolution surfaces and pipes and mudcracked microcrystalline salt crusts which were deposited in saline pans dominated by flooding evaporative concentration and desiccation chaotic halite composed of red bed mudstone and siltstone with displacive halite crystals formed in saline mudflats red bed mudstone and siltstone with little or no displacive halite but with abundant cracking root and plant features suggest deposition in a dry mudflat red bed sandstone composed of well sorted well rounded quartz grains cemented with halite indicate aeolian and rare shallow water deposition most deposition took place in halite dominated ephemeral saline lakes surrounded by saline and dry mudflats sandflats and sand dunes evaporation desiccation flooding and wind played significant roles in this environment the nippewalla group siliciclastics and evaporites represent an evolution from a perennial lacustrine system to a non marine acidic saline pan system in the mid continent of north america the problem of distinguishing between ancient marine and non marine evaporites as well as recognizing those evaporites deposited in acid settings with detailed field core and petrographical study of both evaporite deposits and associated sedimentary rocks has successfully been addressed in addition interpretations of mid permian palaeoclimate data in the form of short term air temperature proxies within longer term wet dry trends have been made these data provide a new palaeogeographic and palaeoclimatic model for the mid permian of western pangaea

environmental implications of salt facies in the dead sea thick sequences of salt halite have been recovered in a 456 m long core drilled at the deepest floor of the dead sea by the dead sea deep drilling project and extending 200 k y back in time the salt sequences were precipitated in the ancient lake that occupied the dead sea basin during the last three interglacials during intervals of extreme aridity in the lake s watershed the salt layers alternate with mud layers that indicate wetter periods in the watershed when floods transported fine detritus matter to the lake the salt sources include brine discharge and freshwater runoff that dissolved halite units dissolved salts accumulated in the lake during glacials and relatively wet periods when the lake expanded and precipitated during interglacials when the lake levels dropped this study establishes for the first time the evaporite facies and sedimentological features of the deep dead sea brine during interglacial periods by using the modern precipitation of halite in the dead sea as an analogue for past halite depositional periods as recorded in the drill core the halite intervals provide a record of facies characterizing a deep water evaporitic environment the halite layers consist mainly of two types of crystals small cumulate crystals containing halite rafts which indicate precipitation from the surface brine of the lake epilimnion and bottom growth usually large halite crystals that precipitated on the lake floor hypolimnion the layers of small halite crystals formed during drier periods as compared to the bottom growth crystals the bottom growth halite crystals contain variable quantities of detritus and show mild dissolution structures at the contact between the mud and the halite crystals these two main types of halite in combination with muds and gypsum comprise seven categories of salt facies that reflect the hydrological conditions dry to wet and that display a cyclic decadal to millennial pattern along the sampled core intervals frequent alternation of these two salt crystal types suggests seasonal changes whereby the small cumulate crystals were formed during the summer and the bottom growth crystals were formed during the winter when the surface temperatures of the lake were low and the surface water was less saline and less likely to be saturated with respect to halite comparison of the last interglacial halite with the modern halite facies together with the absence of significant dissolution features within the halite and the cyclic nature of the facies indicates that the lake was continuously deep 100 m during the last 200 k y

origin of secondary potash deposits a case from miocene evaporites of nw central iran abstract in early miocene times an extensive carbonate shelf developed in central iran and during several cycles of sea level fluctuations evaporite bearing carbonate sequences of the qom formation were deposited however in the early middle miocene development of restricted marine conditions led to a facies change from shelf carbonates of the qom formation to the evaporite series of the m 1 member of the overlying lower red formation this member is a facies mosaic of lagoonal and salina evaporites mainly halite beds admixed with wadi siliciclastics the purpose of this study which focuses on two salt mines in the northwestern portion of central iran in the zanjan province was to reveal the origin sedimentary environment and diagenesis of these potash bearing evaporite sequences petrographic examination revealed the following mineral assemblage halite gypsum anhydrite and carnallite as primary precipitates and langbeinite and aphthitalite as secondary metamorphic potash salts in the iljaq mine distorted halite beds are dominated by burial and deformational textures and a great deal of secondary potash salts in the qarah aghaje mine however the bedded halite shows pristine primary textures and is devoid of the secondary potash salts high bromine content of most evaporite minerals suggests their marine origin and confirms the absence of the extensive meteoric alterations and subsequent bromine depletions potash salts are mainly secondary and resulted from diagenetic replacements of distorted halite beds during thermal and dynamic metamorphism in a burial setting

aspects of the marine nitrogen cycle of the chukchi sea shelf and canada basin abstract as a highly productive seasonally ice covered sea with an expansive shallow continental shelf the chukchi sea fuels high rates of sedimentary denitrification this contributes to its fixed nitrogen n deficit relative to phosphorus p which is among the largest in the global ocean making the chukchi sea severely n limited during the phytoplankton growth season here we examine aspects of the n cycle on the chukchi sea shelf and the downstream canada basin using nutrients dissolved oxygen o 2 and the stable isotopes of nitrate no 3 in the northward flow path across the chukchi shelf bottom waters experienced strong o 2 drawdown from which we calculated a nitrification rate of 1 3 mmol m 2 d 1 this nitrification was likely primarily in sediments and directly fueled sedimentary denitrification historically measured at similar rates we observed significant accumulations of ammonium nh 4 in bottom waters of the chukchi shelf up to 5 m which were inversely correlated with 15 n no 3 indicating a sediment source of 15 n enriched nh 4 this is consistent with a process of coupled partial nitrification denitrification cpnd which imparts significant 15 n enrichment and 18 o depletion to pacific origin no 3 this cpnd mechanism is consistent with a significant decrease in 18 o no 3 relative to bering sea source waters indicating that at least 58 of no 3 populating the pacific halocline was regenerated during its transit across the north bering and chukchi shelves rather than arriving preformed from the bering sea slope this pacific origin no 3 propagates into the canada basin and towards the north atlantic being significantly 15 n enriched and 18 o depleted relative to the underlying atlantic waters

origin and chemical evolution of formation waters from silurian devonian strata in the illinois basin usa abstract a suite of formation water samples from silurian devonian reservoirs in the illinois basin has been analyzed for major minor and trace element concentrations and for h o and sr isotopic compositions in order to interpret origin of salinity and geochemical evolution of brine compositions in this evaporite and shale poor cratonic basin although chloride concentrations range from 2000 to 137 000 mg l cl br ratios 291 18 are consistent with those of seawater or seawater evaporated short of halite saturation cl br 292 thus during silurian devonian time subaerially evaporated penesaline brine entered the subsurface where it was chemically modified through brine rock interactions cation br ratios and mineralogy of associated strata indicate that na and k were depleted through interaction with clay minerals ca was enriched and mg depleted by dolomitization and sr was enriched as a result of caco3 recrystallization and dolomitization although significant dilution of the modified brine with meteoric water is supported by d 18o covariance original marine waters have not been completely expelled from silurian devonian strata hydrogen and oxygen isotopes exhibit covariant relations with cation and anion concentrations implying that isotopic exchange between h2o and minerals has not greatly influenced the d 18o trend brine 87 sr 86 sr ratios range from 0 7092 to 0 7108 when these ratios are plotted versus 1 sr a two component mixing trend is suggested although sr concentrations have experienced local diagenetic modification a 87sr enriched fluid may have accompanied petroleum migration from new albany shales into adjacent silurian devonian carbonates where it mixed with remnant evaporated seawater this event probably preceded the influx of meteoric water as gdd and 18o are not correlated with sr isotopic compositions of formation waters

geotechnical properties of evaporite soils of the dead sea area the dead sea basin is the lowest point on earth and is tectonically subsiding during the holocene period the climate became much drier with increasing evaporation whereby initially lacustrine sediments were deposited from the non marine brines giving a multi layered stratigraphy of lime carbonate and halite sediments the lime carbonate sediments are comprised of laminated clay to silt sized clastic sediments calcite and authigenic aragonite and gypsum the halite commonly appears as rock salt chemical industries based on harvesting the salts from the dead sea have developed on both the israeli and the jordanian sides of the basin the lime carbonate soils are used for dike construction and these soils together with significant salt layers are encountered in the foundations of structures dikes and tailings dams requiring definition of their geotechnical properties use of standard soil mechanics definitions and testing approaches for the lime carbonates have been found inapplicable particularly in view of their exceptionally high saline content and it has been necessary to develop new concepts the rock salt is encountered at shallow depths with unit weights considerably lower than those usually discussed in the literature and with correspondingly different mechanical properties the geotechnical properties of these soils and approaches used to define them are discussed in the paper

geochemical and geophysical evidence of methane release over the east siberian arctic shelf the east siberian arctic shelf esas which includes the laptev sea the east siberian sea and the russian part of the chukchi sea has not been considered to be a methane ch 4 source to hydrosphere or atmosphere because subsea permafrost which underlies most of the esas was believed first not to be conducive to methanogenesis and second to act as an impermeable lid preventing ch 4 escape through the seabed here recent observational data obtained during summer 2005 2006 and winter 2007 expeditions indicate the ubiquitous presence of elevated dissolved ch 4 and an elevated atmospheric ch 4 mixing ratio the ch 4 data were also analyzed together with high resolution seismic hrs data obtained by means of a sonic m 141 system consisting of a high resolution profiler and side scan sonar mounted in a towed fish during the transdrift x expedition 2004 onboard the r v yakov smimitskiy results show anomalously high concentrations of dissolved ch 4 up to 5 m and an episodically nongradually increasing atmospheric mixing ratio of ch 4 up to 8 2 ppm in some areas of the esas a most likely source is year round ch 4 release through taliks columns of thawed sediments within permafrost from seabed ch 4 reservoirs such as shallow hydrates and geological sources such releases occur not only within the areas underlain by fault zones but also outside of them this points to permafrost s failure to further preserve ch 4 deposits in the esas the total amount of carbon preserved within the esas as organic matter and ready to release ch 4 from seabed deposits is predicted to be 1400 gt release of only a small fraction of this reservoir which was sealed with impermeable permafrost for thousands of years would significantly alter the annual ch 4 budget and have global implications because the shallowness of the esas allows the majority of ch 4 to pass through the water column and escape to the atmosphere

seasonal and spatial patterns of sedimentary denitrification rates in the chukchi sea abstract recent constructions of the global nitrogen budget estimate that at least half of the ocean s fixed nitrogen is lost by sedimentary denitrification the majority of which occurs in continental shelves the arctic contains approximately 20 of the world s continental shelf suggesting it is a substantial contributor to the global sedimentary denitrification rate during two cruises in the summer and spring of 2002 and 2004 respectively denitrification rates were calculated from the downward diffusive flux of nitrate in the shelf and slope sediments of the chukchi sea in the western arctic additionally in the spring of 2004 denitrification rates were determined by whole core incubations in which the flux of nitrogen gas out of the sediments was measured measurements were made along three transects crossing the shelf and slope 50 3000 m each transect having different overlying water characteristics denitrification rates generally decreased with increasing water depth rates varied from about 1 6 mmol n m 2 d 1 for the shallow water sediments to undetectable in deep water sediments rates showed little variation between the two seasons however rates were found to correspond with differences in annual overlying primary productivities and particulate organic carbon export fluxes an extrapolation to the whole arctic yielded an average arctic sedimentary denitrification rate of 13 tg n yr 1 taken in the context of the global nitrogen budget it is about 4 13 of the total sink of fixed nitrogen in the ocean

textural features of holocene perennial saline lake deposits of the taoudenni agorgott basin northern mali abstract the holocene salt lake deposits of the taoudenni agorgott basin northern mali mainly consist of sediments with a high glauberite na2ca so4 2 content the remainder of the deposits largely consists of salt beds with a bloedite na2mg so4 2 4h2o thenardite na2so4 or halite nacl composition a petrographical study of the deposits demonstrates that they formed in a perennial lake that experienced a gradual decrease in water depth textural features of the glauberite dominated deposits are found to be related to water depth through the control that this factor exerts on the sensitivity of the lake to changes in water supply and to short term variations in evaporation rates in this way layering due to variations in glauberite content and crystal size is inferred to be typical of deposits that formed in shallow water whereas unstratified deposits are the product of high lake level stages halite textures are found to be indicative of the place within the water column where crystal growth occurred along the lake bottom or higher which is mainly determined by water depth and partly by evaporation rates the oldest halite beds are largely unaltered cumulate deposits whereas the youngest layers developed exclusively through bottom growth the basal part of one thick halite bed at a level between these two groups of halite layers developed by an alternation of both types of growth in response to variations in evaporation rates variations in mineralogical composition between and within the salt beds that formed during the earliest periods with a higher salinity up to the first stage with halite formation record a change in lake water chemistry with time but they are in one instance also determined by an early diagenetic mineral transformation

paradigm shift in determining neoproterozoic atmospheric oxygen acknowledgments we thank the geological survey of australia for permission to sample the empress 1a and lancer 1 cores the natural sciences and engineering research council of canada for financial support grant 7961 15 of u brand and the national natural science foundation of china for support of f meng and p ni grants 41473039 and 4151101015 we thank m lozon brock university for drafting and constructing the figures we thank the editor brendan murphy as well as three reviewers steve kesler erik sperling and an anonymous reviewer for improving the manuscript into its final form

the distribution of methane on the siberian arctic shelves implications for the marine methane cycle 1 the seepage of methane ch4 through the seabed of the world s shelves is considered to be ubiquitous although numerous observations of methane seepages from shallow marine sources have been reported there were only a very few observations made over the arctic shelves and none for the east siberian sea ess or laptev sea ls we present two years of data obtained during the late summer period september 2003 and september 2004 for both the ess and ls shelves according to our data the surface layer of shelf water was supersaturated up to 2500 relative to the present average atmospheric methane content of 1 85 ppm anomalously high concentrations up to 154 nm or 4400 supersaturation of dissolved methane in the bottom layer of shelf water suggest that the bottom layer is somehow affected by near bottom sources considering the possible formation mechanisms of such plumes we favor thermo abrasion and the effects of shallow gas or gas hydrates release

salt usually seals but sometimes leaks implications for mine and cavern stabilities in the short and long term abstract thick evaporite masses bedded and halokinetic dominated by the mineral halite are currently mined using conventional solution mining techniques after excavation the resulting salt cavities are sometimes used as subsurface storage vessels for hydrocarbons or various types of waste including low level nuclear waste there are plans being discussed to use purposed designed solution cavities in thick salt masses for the long term storage of high level nuclear waste if high level nuclear waste is ever to be safely stored in salt it will involve a need for the encasing salt not to leak over time frames measured in tens of thousands of years understanding how where and why accessible salt masses leak is the rationale for this review it is the first step in assessing it a particular site s salt geology is suitable for storage we know salt can act as an excellent longterm seal over hundreds of thousands of years as evidenced by its ability to hold back significant columns of highly overpressured fluids even in structurally complex settings but we also know that locally salt bodies do occasionally leak large volumes of fluid as evidenced by the loss of a number of salt mines to uncontrolled floods the rapid creation of solution dolines atop subcropping salt masses and to black salt haloes around highly pressurized hydrocarbon reservoirs these types of leakage are usually tied to the edges of a salt body being exposed to longterm crossflows of undersaturated pore waters or to the build up of internal pressure to levels that exceed lithostatic in fact most zones where a salt body is liable to leak or has leaked are indicated by anomalous textural or mineralogical features when compared to the regional character of the salt the time of leakage can be early eogenetic related to burial mesogenetic or related to uplift telogenetic if the salt mass is not entirely dissolved in the fluid crossflow then the remaining salt tends to re seal especially in zones of ongoing salt flow however if non salt sediment remains in the re annealed salt mass it will tend to retain permeability and when intersected in a salt mine or by a well bore it will flow fluid more problematic in terms of significant leakage are zones in contact with an aquifer external to the salt mass these anomalous areas can transfer large volumes of fluid for this reason active telogenetic anomalies in a salt mass are the most problematic in terms of both mine safety and waste storage identifying the type of salt anomaly the time in diagenesis when leakage occurred and proximity and volume of intersected fluids in the zone of leaking salt is fundamental to mine safety and reliable waste storage

tracing pacific water in the north atlantic ocean 1 in the arctic ocean pacific source water can be distinguished from atlantic source water by nitrate phosphate concentration relationships with pacific water having higher phosphate concentrations relative to those of nitrate furthermore pacific water originally from the inflow through bering strait is clearly recognizable in the outflows of low salinity waters from the arctic ocean to the northern north atlantic ocean through the canadian arctic archipelago and through fram strait in the canadian arctic archipelago we observe that almost all of the waters flowing through lancaster and jones sounds most of the water in the top 100 m in smith sound containing the flow through nares strait and possibly all waters in hudson bay contain no water of atlantic origin significant amounts of pacific water are also observed along the western coast of baffin bay along the coast of labrador and above the 200 m isobath of the grand banks there is a clear signal of pacific water flowing south through fram strait and along the east coast of greenland extending at least as far south as denmark strait pacific water signature can be seen near the east coast of greenland at 66 n but not in data at 60 n temporal variability in the concentrations of pacific water has been observed at several locations where multiple year observations are available

coexistence of nitrous oxide undersaturation and oversaturation in the surface and subsurface of the western arctic ocean the nitrous oxide n2o distributions in a shelf slope basin section from the chukchi sea shelf to the chukchi abyssal plain cap in the western arctic ocean were observed for the first time during the fourth chinese national arctic research expedition 4th chinare in late august 2010 the n2o concentrations were 11 4 16 9 nmol l 1 corresponding to saturation values of 92 118 in the surface water in the surface biological factor was negligible to n2o production and physical process dominated the surface n2o distribution the n2o undersaturation may be the result of dilution by sea ice meltwater the oversaturation may be caused by the diffusing of n2o rich shelf bottom water below the surface n2o concentrations ranged from 11 4 to 21 4 nmol l 1 on the chukchi sea shelf n2o concentrations increased from the surface to the near bottom water indicating sediment n2o produced by nitrification or denitrification emission may be a significant source the subsurface maxima in the upper halocline layer uhl may receive partial contribution from nitrification production but was primarily caused by the spreading of shelf water

a geotechnical study of evaporitic lacustrine sediments in the saline environment of the dead sea area this paper is the third by the authors relating to the geotechnical properties of the evaporitic lacustrine sediments of the saline environment in the dead sea area the earlier papers identified difficulties involved in establishing the water content of sediments in a saline environment a different approach was adopted whereby fluid content rather than water content was used to define geotechnical properties the present paper expands on the geological background presented in the previous papers and discusses additional geotechnical aspects of the materials behavior the three major sediment types encountered in the region are fluvial granular soil cohesive lime carbonate deposits and granular to massive halite sediments the granular soils composed predominantly of sand and pebbles of dolomite with minor chert and limestone have gradations which vary widely both with depth and laterally shear wave velocities are higher than those estimated from common existing correlations with standard penetration test spt blow counts while compression indices cc and cyclic shear response of the saturated lime carbonates are consistent with behavior of clay soils their effective friction angle of about 34 on average is significantly higher than that of clays the geotechnical properties of the rock salts encountered in the region are shown to be intimately related to the extent of diagenesis and burial with very significant difference between the younger more porous deposits of holocene age and the older mt sdom diapiric salt wall of upper miocene age the latter are seen to have properties consistent with those of older rock salt deposits at greater depths reported in the literature

strontium boron oxygen and hydrogen isotope geochemistry of brines from basal strata of the gulf coast sedimentary basin usa abstract significant spatial heterogeneities exist in the stable isotopic composition of saline formation waters from reservoirs of the smackover formation upper jurassic we focused on the southwest arkansas shelf a structurally simple portion of one of the interior basins of the northern gulf coast sedimentary basin here faulting and facies changes juxtapose dominantly oolitic carbonate strata against basal evaporites red beds and siliciclastics as well as metamorphosed basement rocks brines from this area have exceptionally high br and alkali element concentrations and have spatially heterogeneous hydrogen sulfide concentrations strontium boron oxygen and hydrogen isotope compositions exhibit coherent relations with other aspects of brine geochemistry sr isotope compositions range from those expected for carbonates and evaporites deposited from jurassic seawater 0 7071 to radiogenic ratios as high as 0 7107 generally most radiogenic sr isotope values are associated with h 2 s rich waters which also have elevated alkali element li b k rb concentrations these alkali element rich waters are associated with portions of the south arkansas fault system which reach basement boron isotope compositions are similarly heterogeneous ranging from values of 26 to 50 brines with highest b contents are most depleted in 11 b consistent with boron input from brines generated from high temperature siliciclastic diagenetic reactions normalizing b contents to br in the brines reveals a reasonable mixing trend between a dead sea type composition and texas gulf coast type shale sand reservoir waters oxygen and hydrogen isotope data exhibit regional variations which are controlled by meteoric water invasion along the northern limb of the southwest arkansas fault which has surface expression although oxygen isotope compositions are often near equilibrium with respect to reservoir carbonate it is more difficult to ascribe trends in d values to local water rock interaction the stable isotope trends can be explained either in terms of an evolved marine evaporite brine or a water evolved via water rock interaction and mixing with meteoric water in the vicinity of the southwest arkansas fault spatial heterogeneity in isotopic composition of formation waters from this relatively restricted study area suggests that assumptions of a homogeneous sr reservoir in dating regional mineralization events require careful assessment in ancient systems

in situ evaluation of air sea gas exchange parameterizations using novel conservative and volatile tracers measurements of air sea gas exchange rates are reported from two deliberate tracer experiments in the southern north sea during february 1992 and 1993 a conservative tracer spores of the bacterium bacillus globigii var niger was used for the first time in an in situ air sea gas exchange experiment this nonvolatile tracer is used to correct for dispersive dilution of the volatile tracers and allows three estimations of the transfer velocity for the same time period the first estimation of the power dependence of gas transfer on molecular diffusivity in the marine environment is reported this allows the impact of bubbles on estimates of the transfer velocity derived from changes in the helium sulphur hexafluoride ratio to be assessed data from earlier dual tracer experiments are reinterpreted and findings suggest that results from all dual tracer experiments are mutually consistent the complete data set is used to test published parameterizations of gas transfer with wind speed a gas ex change relationship that shows a dependence on wind speed intermediate between those ofliss and merlivat 1986 and wanninkhof 1992 is found to be optimal the dual tracer data are shown to be reasonably consistent with global estimates of gas exchange based on the uptake of natural and bomb derived radiocarbon the degree of scatter in the data when plotted against wind speed suggests that parameters not scaling with wind speed are also influencing gas exchange rates

synsedimentary dissolution pipes and the isolation of ancient bacteria and cellulose coarse clear halite from synsedimentary dissolution pipes in the permian salado formation in southeastern new mexico usa yielded viable halotolerant bacteria and well preserved cellulose believed to be permian in age here we show that geologic and hydrologic conditions have isolated these rocks since permian time pipes were dissolved most likely along cracks created by thermal contraction or desiccation and the boundaries of salt polygons saucers on exposed salado formation salt pan surfaces down to the level of the water brine table macropores developed at the brine level in some horizons as the water level rose coarse halite cemented the open space fluid inclusions millimeter scale trapped bacteria which were probably in a spore state as well as cellulose inclusion water from pipes in some cycles may have isotopic values reflecting permian meteoric water while other cycles may show evaporated permian seawater exposure surfaces are more prominent in the upper part of salado formation depositional cycles due to basin desiccation as indicated by cracks and dish shaped laminae clays were concentrated on many exposure surfaces by floods wind and dissolution dissolution pipes formed from these surfaces and a synsedimentary age is confirmed by undisturbed overlying halite beds salado formation halite has very low permeability 10 22 m 2 effectively preventing significant fluid flow and passage of fluids through the formation either to recrystallize salt or to introduce modern bacteria stratigraphic relationships halite textures fluid inclusion chemistry and hydraulic properties are all consistent with a synsedimentary origin of the dissolution pipes their crystals and the bacteria and cellulose recovered from the salado formation

acid saline lake systems of the triassic mercia mudstone group county antrim northern ireland abstract the triassic mercia mudstone group of county antrim northern ireland is dominated by red beds and evaporites after only limited study both marine and continental environments have been proposed previously here we describe these rocks for the first time from core and petrographic observations to interpret depositional environments and conditions such as water depth salinity and aridity bedded halite bedded gypsum displacive halite and red siliciclastic mudstone lithologies comprise most 80 of the 591 6 m thick mercia mudstone group in the gaelectric carnduff 2 core bedded halite consists of chevron and cornet crystals indicating bottom growth from shallow surface brines bedded gypsum lithology is composed of halite replaced pseudomorphs after swallowtail bottom growth gypsum crystals both bedded halite and bedded gypsum contain dissolution features and are commonly overlain by mud drapes bedded halite and bedded gypsum lithologies are interpreted to have formed in shallow saline lakes influenced by flooding and evapoconcentration the displacive halite lithology is composed of sub cubic halite crystals randomly oriented in mudstone and represents deposition in a saline mudflat some mudstones contain ripple cross lamination dewatering structures mudcracks and rip up clasts suggesting shallow surface water and desiccation other mudstones are massive structureless and may have been deposited by wind both of these mudstone units were likely deposited in dry mudflats other red mudstones contain soil slickensides blocky peds and circumgranular cracks and are interpreted as paleosols our observations indicate that the triassic mercia mudstone group was formed by shallow perennial saline lakes and associated continental environments in an arid climate furthermore lack of carbonates lack of fossils and paucity of organic matter suggest acid saline lakes and groundwaters the triassic mercia mudstone group is similar to some other pangean red beds and evaporites therefore we hypothesize that the supercontinent was an arid barren landscape hosting acid saline lakes

observed increases in bering strait oceanic fluxes from the pacific to the arctic from 2001 to 2011 and their impacts on the arctic ocean water column 1 mooring data indicate the bering strait throughflow increases 50 from 2001 0 7 sv to 2011 1 1 sv driving heat and freshwater flux increases increase in the pacific arctic pressure head explains two thirds of the change the rest being attributable to weaker local winds the 2011 heat flux 5 1020j approaches the previous record high 2007 due to transport increases and warmer lower layer ll temperatures despite surface temperature sst cooling in the last decade warmer ll waters arrive earlier 1 6 1 1 days yr though winds and sst are typical for recent decades maximum summer salinities likely set in the bering sea remain remarkably constant 33 1 psu over the decade elucidating the stable salinity of the western arctic cold halocline despite this freshwater flux variability strongly driven by transport exceeds variability in other arctic freshwater sources remote data winds sst prove insufficient for quantifying variability indicating interannual change can still only be assessed by in situ year round measurements

pliocene pleistocene climate change at the ne tibetan plateau deduced from lithofacies variation in the drill core sg 1 western qaidam basin china abstract the pliocene pleistocene sedimentologic evolution of the western qaidam basin at the ne tibetan plateau was studied on the nearly thousand meter deep drill core sg 1 spanning ca 2 8 0 1 ma recovered from the chahansilatu sub depression with an average recovery rate of 95 lithofacies variation records the regional climatic change in relation to asian drying and tibetan plateau uplift sedimentary textures and structures demonstrate a continuous slight coarsening and an increase of evaporites upward we recognized five lithofacies 1 gray black laminated mudstone 2 gray massive mudstone and siltstone 3 bedded halite 4 loose muddy halite and 5 brownish yellowish saliferous siltstone and mudstone representing 1 semi deep fresh to semi brackish lake 2 shallow brackish lake 3 perennial saline lake 4 playa saline lake and 5 saline mudflat conditions respectively variation of the lithofacies through the core demonstrates a clear trend of lake shrinkage since the late pliocene and the final termination of the chahansilatu paleolake accelerations of lake shrinkages are observed at ca 2 5 ma 2 2 ma 1 6 ma 1 2 ma 0 9 ma 0 6 ma and 0 1 ma our results suggest that the long term stepwise drying of the asian inland may have been forced by the change of the global ice volume

traces of evaporites in upper cretaceous lacustrine deposits of korea origin and paleoenvironmental implications abstract diverse types of halite and sulfate evaporite traces occur in the upper cretaceous lacustrine deposits of the jindong formation and the jangdong tuff in korea in which dinosaur tracks are common the halite traces usually occur as casts or moulds and they include traces of primary halite hoppers primary and intrasedimentary skeletal halite and intrasedimentary tiny halite the sulfate traces occur as intrasedimentary and displacive casts filled with sediments and sparry calcite and the casts occur as diverse modes from single crystal casts through nodular aggregates to massive aggregates some aggregates of the sulfate casts are aligned in crack pattern and selective occurrence of the laths in ripple troughs are observed soluble sulfate evaporite minerals such as gypsum glauberite or mirabilite are probable for the precursors of these traces these halite and sulfate traces are interpreted to have been formed in a saline lake and mudflats it is interpreted that meteoric water was responsible for the evaporite precipitation in the jindong lake and jangdong lake recycled brine produced by the repeated dissolution of evaporites might contribute to the evaporite precipitation in the paleo jindong lake and the paleo jangdong lake the development of saline lake deposits in the jindong formation and the jangdong tuff suggests that the southern part of the korean peninsula remained an inland continental area during the cretaceous resulting in semi arid paleoclimatic condition due to an orographic effect by the location of the korean peninsula on continental margin in mid latitude with topographic barriers during the cretaceous the occurrence of dinosaur tracks in the lake margin deposits of saline lake with frequent inflow of dilute meteoric water suggests that upper cretaceous dinosaurs inhabiting lakes on the korean peninsula might have drunken brackish water

new evidence for 250 ma age of halotolerant bacterium from a permian salt crystal the purported oldest living organism the spore forming bacterium virgibacillus sp perm ian strain 2 9 3 was recently cultured from a brine inclusion in halite of the 250 ma permian salado formation however the antiquity of virgibacillus sp 2 9 3 has been chal lenged it has been argued that the halite crystal and the fluid inclusion from which the bacterial spores were extracted may be younger than the permian salado salts here we report that brine inclusions from the same layer of salt that housed virgibacillus sp 2 9 3 are composed of evaporated late permian seawater that was trapped in halite cement crys tals precipitated syndepositionally from shallow groundwater brines at temperatures of 17 37 8c these results support the 250 ma age of the fluid inclusions and by inference the long term survivability of microorganisms such as virgibacillus sp 2 9 3

the canada basin 1989 1995 upstream events and far field effects of the barents sea 1 the effects of upstream events on southern canada basin waters were examined using physical and geochemical data collected at one location between 1989 and 1995 these events included atlantic layer warming relocation of the atlantic pacific water mass boundary and increased ventilation of boundary current waters early signals of change in the canada basin first appeared in 1993 along the continental margin and by 1995 were evident in the basin interior and farther downstream differences in physical and geochemical properties nutrients oxygen 129i and cfcs were observed between 150 and 1600 m of the water column by 1995 the boundary between pacific and atlantic origin water was shallower and atlantic origin water occupied more of the canada basin water column atlantic origin lower halocline water was colder and more ventilated fram strait branch water was colder fresher and more ventilated and barents sea branch water was warmer fresher more ventilated and occupied a larger volume of the water column than in previous years water mass analysis showed that the composition of atlantic origin water in the canada basin in 1995 included 20 more water from the barents sea two related events upstream appear to be the source of this change an atmospheric regime shift in 1989 that increased cyclonic circulation a transition unprecedented within the latter half of the 20th century in magnitude geographic reach and apparent oceanographic impacts and a large volume of dense water flowed from the barents sea to the arctic ocean between 1988 and 1989 these two phenomena illustrate the close relationship between atmospheric and oceanic events whose combined influence was evident 6 years later and 5100 km downstream in the canada basin at depths 1000 m

a vertical gradient of nitrous oxide below the subsurface of the canada basin and its formation mechanisms the ocean is regarded as a significant source of n2o which is an ozone depleting greenhouse gas however the contribution of the arctic ocean to the global n2o budget is not yet known herein the first observations of n2o concentrations in the canada basin cb and greenland sea basin gsb are presented a correlation between the historic atmospheric n2o record and n2o concentrations at the corresponding depth in the gsb suggests that the n2o distribution pattern is dominated by air sea exchanges and hydrographic processes in this region the consistency between the observed n2o concentrations in the cb and calculated results based on the above correlation suggest that the n2o concentrations in the cb are most likely dominated by n2o dynamics and subsequent hydrographic processes in the sea adjacent to the gsb the n2o concentration in the canada basin intermediate water cbiw reflects anthropogenic influences whereas the n2o concentration in the canada basin deep water cbdw suggests that the cbdw may be a preindustrial relict

are sedimentary salt layers always impermeable we report here for the first time the finding of a 24 to 31 m deep 10 000 y old water saturated and highly hydraulically conductive salt layer composed of idiomorphic halite crystals in the coastal area of the dead sea the high hydraulic conductivity of the layer was evidenced by laboratory and field tests and by the rapid fluctuations of the water table in a well penetrating the layer following variations in the water level of the dead sea such layers may lead to intensive and rapid flow of water and non polar liquids

microstructural evolution of deformation modified primary halite from the middle triassic rot formation at hengelo the netherlands the microstructure of halite from the subhorizontal bedded main rot evaporite member at hengelo the netherlands akzo well 382 depth interval of 420 460 m was studied by transmitted and reflected light microscopy of gamma irradiation decorated samples primary microstructures compare favourably with those found in recent ephemeral salt pans large blocky fluid inclusion poor halite grains and elongated chevrons are interpreted to have formed in the saline lake stage while void filling clear halite is interpreted to have formed during the desiccation stage of the salt pan in addition in all layers the grains are rich in deformation related substructures such as slip bands and subgrains indicating strains of a few percent the study of gamma irradiation decorated thin sections shows that the main recrystallization mechanism is grain boundary migration grain boundary migration removes primary fluid inclusions and produces clear strain free new grains differential stresses as determined by subgrain size piezometry were 0 45 0 97 mpa the deformation of the salt layers is probably related to cretaceous inversion in the area

coupled nitrification denitrification in sediment of the eastern bering sea shelf leads to 15n enrichment of fixed n in shelf waters 1 we studied the nitrogen biogeochemistry of the ice covered eastern bering sea shelf using the isotope ratios 15n 14n and 18o 16o of no3 and other n species the 15n 14n of late winter no3 on the shelf decreases inshore and is inversely correlated with bottom water nh4 consistent with an input of low 15n 14n no3 from partial nitrification of nh4 remineralized from the sediments an inshore 15n 14n increase in total dissolved n tdn suggests that 1 the sediment derived nh4 is elevated in 15n due to the same partial nitrification that yields the low 15n 14n no3 and 2 15n deplete no3 from partial nitrification within the sediments is denitrified to n2 the proportion of newly nitrified no3 on the shelf evidenced by an inshore decrease in no3 18o 16o is correlated with the n deficit further implicating nitrification coupled to denitrification however a simple n isotope budget indicates a comparable rate of denitrification supported by diffusion of no3 into the sediments the isotopic impact of benthic n loss is further demonstrated by a correlation between the 15n 14n of shelf surface sediment and the n deficit of the overlying water column both of which increase inshore and northward as well as by arctic no3 isotope data indicating that the fixed n transported through bering strait has a 15n 14n higher than is found in the open bering sea the significant net isotope effect of benthic n loss on the bering shelf 6 8 is at odds with previous assumptions regarding the global ocean s n isotope budget

circulation of winter water on the chukchi shelf in early summer abstract using a variety of data sources we investigate the properties and pathways of pacific origin winter water as it spreads across the eastern chukchi shelf in early summer the focus is on the time period june july 2011 during which an extensive shipboard hydrographic velocity survey was undertaken as part of the impacts of climate on ecosystem and chemistry of the arctic pacific environment icescape program a revised circulation scheme is constructed revealing that the transport pathways on the chukchi shelf are more complex than previously thought notably the well known branch progressing northward from the central channel bifurcates as it reaches hanna shoal flowing around both sides of the shoal and dividing into smaller filaments that continue towards barrow canyon mass is conserved in the circulation scheme with approximately 1 sverdrup flowing poleward across the chukchi shelf within these pathways then exiting barrow canyon the salinity of the winter water varied on the shelf in 2011 with saltier water found in the upstream portion of what is defined as the central pathway using sea ice concentration data and atmospheric reanalysis fields we argue that salinization of the winter water in the central pathway occurred via brine rejection as the parcels progressed north and passed through the cape lisburne polynya this demonstrates that winter water pervading the interior shelf can be transformed by convective overturning north of bering strait presumably stirring up nutrients from the sediments and thereby influencing primary productivity in the region of hanna shoal

solution precipitation creep and fluid flow in halite a case study of zechstein z1 rocksalt from neuhof salt mine germany zechstein z1 rocksalt from the fulda basin from the immediate vicinity of the hessen potash bed is folded into tight to isoclinal folds which are cut by an undeformed 1 cm thick coarse grained halite vein microstructures were investigated in etched gamma irradiated thin sections from both the wall rock and the vein the lack of synsedimentary dissolution structures and the widespread occurrence of plate shaped and hopper grains in the wall rock suggests that the sedimentary environment was perennial lake deformation microstructures are in good agreement with solution precipitation creep process and salt flow under very low differential stress strength contrast between anhydrite rich and anhydrite poor layers caused the small scale folding in the halite beds the vein is completely sealed and composed mainly of euhedral to subhedral halite grains which often overgrow the wall rock grains those microstructures together with the presence of occasional fluid inclusion bands suggest that the crystals grew into a solution filled open space based on considerations on the maximum value of in situ differential stress the dilatancy criteria the amount of released fluids from the potash bed during metamorphism and the volume change it is proposed that the crack was generated by hydrofracturing of the rocksalt due to the presence of the salt metamorphic fluid at near lithostatic pressure

methane and nitrous oxide distributions across the north american arctic ocean during summer 2015 we collected arctic ocean water column samples for methane ch4 and nitrous oxide n2o analysis on three separate cruises in the summer and fall of 2015 covering a 10 000 km transect from the bering sea to baffin bay this provided a three dimensional view of ch4 and n2o distributions across contrasting hydrographic environments from the oligotrophic waters of the deep canada basin and baffin bay to the productive shelves of the bering and chukchi seas percent saturation relative to atmospheric equilibrium ranged from 30 800 for ch4 and 75 145 for n2o with the highest concentrations of both gases occurring in the northern chukchi sea nitrogen cycling in the shelf sediments of the bering and chukchi seas likely constituted the major source of n2o to the water column and the resulting high n2o concentrations were transported across the arctic ocean in eastward flowing water masses methane concentrations were more spatially heterogeneous reflecting a variety of localized inputs including likely sources from sedimentary methanogenesis and sea ice processes unlike n2o ch4 was rapidly consumed through microbial oxidation in the water column as shown by the 13c enrichment of ch4 with decreasing concentrations for both ch4 and n2o sea air fluxes were close to neutral indicating that our sampling region was neither a major source nor sink of these gases our results provide insight into the factors controlling the distribution of ch4 and n2o in the north american arctic ocean and an important baseline data set against which future changes can be assessed

loule the anatomy of a squeezed diapir algarve basin southern portugal the loule salt diapir grew through the jurassic and early cretaceous when tight subvertical curtain folds were developed it was then squeezed during the alpine orogeny in the oligocene and miocene this produced an intense array of brittle faults veins and brittle ductile shear zones through most of the diapir the diapir exhibits more localized shear and brittle structures than any other previously described diapir the most unusual deformation structures are streaky shear vein zones a new term with an average spacing of 1 5 m and usually less than 30 cm wide they consist of a central coarse grained halite vein surrounded by parallel zones of wispy discontinuous shale streaks and recrystallized halite a new mechanism is proposed for the development of these zones where repeated pulses of fluid flow have caused extensive halite recrystallization and streaking out of unlithified mud intercalated with crystalline halite this explains the formation of wide zones of well aligned mud streaks now lithified to shale but with only small amounts of simple shear offset observed across these zones

a 100 ka record of water tables and paleoclimates from salt cores death valley california abstract sedimentary and petrographic features of evaporites and associated sediments from a 185 m deep core taken in death valley ca together with uranium series dating have been used to reconstruct the history of water table fluctuations and climate changes in death valley for the past 100 ka death valley has been arid during the holocene 0 10 ka with predominantly mudflat and saline pan subenvironments a perennial lake up to 90 m deep existed in death valley from 10 to 35 ka saline pan and mudflat subenvironments dominated death valley from 35 to 100 ka the chronology of changing subenvironments and water table fluctuations in death valley generally correlates with other climate records in the western us owens lake and searles lake ca browns room cave calcite nv the marine oxygen isotope record and the vostok ice core record core intervals through saline pan sediments are composed of interbedded halite chaotic muddy halite and mud the halite contains abundant vertical dissolution pipes cemented with clear halite these sediments record repeated flooding by dilute waters dissolution of subaerially exposed surface salt crusts deposition of mud from suspension precipitation of halite during the saline lake phase and cementation by diagenetic halite mudflat sediments consist of clayey silt with sand patches and mud cracks which document long periods of desiccation and the formation of efflorescent salt crusts from the evaporation of groundwater brines saline pan and mudflat deposits formed during periods when death valley was relatively arid similar to the modern climate lacustrine deposits consist of mudhalite cycles accumulated during the early lake stage bedded thenardite na 2 so 4 and mud above and a cap of massive halite formed during the latest lake stage all of which record fluctuating salinities and lake levels in a perennial system such deposits document a relatively wet climate with a high ratio of water inflow to evaporation ostracodes in mud layers represent the least saline deepest lake phases halite layers are made of fine grained cumulates and clear vertically oriented crystals precipitated during shallower perennial lake stages of significance is the nearly complete absence of syndepositional dissolution of saline minerals in the lacustrine interval indicating that accumulated salts were permanently protected from dissolution by saline lake waters such evidence strongly suggests that lakes existed continually without desiccating for 25 ka between 10 and 35 ka b p

quantitative temperature records of mid cretaceous hothouse evidence from halite fluid inclusions abstract quantitative temperature reconstructions for the mid cretaceous are still rare although its typical greenhouse climate is regarded as one of the best analogues for future global warming for the first time mid cretaceous temperatures were quantitatively reconstructed based on homogenization temperatures th of halite fluid inclusions from the lower member of the nong bok formation in the thakhek mining area laos petrological features and primary textures of halite indicate a shallow water setting during halite formation that allows the use of homogenization temperatures as air temperature proxy obtained homogenization temperatures mainly range from 30 to 50 c probably representing local air temperature conditions of laos during the mid cretaceous the determined temperatures are relatively similar to temperatures in many modern and ancient evaporative settings the maximum homogenization temperature th max for the nong bok formation of 62 1 c is significantly higher than existing mid cretaceous paleotemperature records from both continental and marine sediments and comparable with the temperature records from the contemporaneous mengyejing formation of yunnan southern china the correspondence of the temperature records from laos and yunnan implies that very high temperature conditions prevailed in the region our results and other reconstructed very high temperatures from potash deposits e g 59 c for the silurian michigan basin and 58 c for the quaternary lop nur region suggest that extremely high temperatures probably had an important impact on the formation of the large potash deposits of the world however more studies are needed to improve our understanding of the detailed and quantitative relationships between temperature conditions and potash formation

evolution of a late jurassic carbonate evaporite platform conecuh embayment northeastern gulf coast u s a successive time slice lithofacies maps of the smackover haynesville depositional sequence constrained by marker beds an interpreted maximum flooding surface and interpreted sequence boundaries show an onlapping and retrograding sequence of lithologies characteristic of a transgressive systems tract tst the tst is followed by several prograding sequences characteristic of a highstand systems tract hst and stacked shelf margin wedges smw comparison of stratigraphic cross sections lithofacies maps and a paleotopographic map of the sub smackover transgressive surface shows that the distribution of lithofacies within the tst was strongly controlled by two types of sub smackover paleotopographic highs 1 norphlet dune fields and 2 eroded basement rock as th tst became progressively buried during deposition distribution of lithofacies within the hst and the smws was controlled less by these early paleotopographic features and more by 1 differential compaction around shoal water facies in the tst 2 early louann salt movement 3 basement related faulting and 4 freshwater influx along the basin rim

permian paleoclimate data from fluid inclusions in halite abstract this study has yielded surface water paleotemperatures from primary fluid inclusions in mid permian nippewalla group halite from western kansas a cooling nucleation method is used to generate vapor bubbles in originally all liquid primary inclusions then surface water paleotemperatures are obtained by measuring temperatures of homogenization to liquid homogenization temperatures ranged from 21 c to 50 c and are consistent along individual fluid inclusion assemblages indicating that the fluid inclusions have not been altered by thermal reequilibration homogenization temperatures show a range of up to 26 c from base to top of individual cloudy chevron growth bands petrographic and fluid inclusion evidence indicate that no significant pressure correction is needed for the homogenization temperature data we interpret these homogenization temperatures to represent shallow surface water paleotemperatures the range in temperatures from base to top of single chevron bands may reflect daily temperatures variations these permian surface water temperatures fall within the same range as some modern evaporative surface waters suggesting that this permian environment may have been relatively similar to its modern counterparts shallow surface water temperatures in evaporative settings correspond closely to local air temperatures therefore the permian surface water temperatures determined in this study may be considered proxies for local permian air temperatures

diagenesis of saline pan halite comparison of petrographic features of modern quaternary and permian halites abstract petrographic studies of modern saline pan halites saline valley ca salina omotepec baja california mexico and quaternary shallow buried 0 200 m halites saline valley ca bristol dry lake ca searles lake ca qarhan saline pan qaidam basin china lake uyuni bolivia show that the diagenetic modification of halite begins contemporaneously with deposition is most intense within the upper few meters of burial and is essentially complete within the first 45 m of burial halite crusts from modern saline pans that have undergone repeated episodes of flooding evaporative concentration and desiccation contain abundant syndepositional diagenetic features these mature modern halites are dominated by dissolution textures and fabrics formed during flood stages and cementati n textures formed during desiccation stages interlayered mud beds contain varying amounts of displacive halite crystals at shallow burial depths halites retain many textural features of mature modern saline pan halite halites below the first few meters are no longer susceptible to dissolution from floodwaters but continue to be cemented by clear halite within the first 10 m of burial cementation reduces the porosity of halite crusts to less than 10 the remaining pore spaces are completely filled by burial depths of approximately 45 m displacive growth of halite in muds continues at shallow burial depths and is probably limited to the first few tens of meters of burial depth the mechanisms for cementation and displacive growth of halite at shallow burial depths probably include 1 evaporative concentration of groundwater brines and 2 cooling of surface brines when they sink below the sedime t surface undeformed halites from the permian salado and rustler formations of new mexico contain delicate syndepositional textures and abundant clear halite cements that are comparable to those observed in modern saline pan halites and shallow buried halites the permian halites are interpreted to have undergone a depositional and early diagenetic history similar to the modern and quaternary analogs complete cementation of saline pan halites at shallow burial depths has important implications for the origin of saline formation waters in sedimentary basins parent evaporite brines may not be stored in the pores of halite rocks and later expelled during burial compaction if the rocks are cemented early and tightly crystallized halite rocks may also impede the downward migration of dense syndepositional brines

paleobrine temperatures chemistries and paleoenvironments of silurian salina formation f 1 salt michigan basin u s a from petrography and fluid inclusions in halite abstract a 3 7 m stratigraphic section of the silurian salina group f 1 salt detroit salt company mine michigan basin was studied to document the paleodepositional conditions including brine chemistry and temperature of evaporite precipitation sedimentary features including rippled surfaces halite chevrons cumulate halite and dissolution surfaces confirm a shallow water depositional setting penecontemporaneous dissolution surfaces indicate that waters undersaturated with respect to halite were introduced into the michigan basin and that the basin brines were nonstratified during flooding allowing inflow waters to come into contact with halite crystals at the bottom fluid inclusions in primary chevron halite have homogenization temperatures between 5 and 25 c which represent brine temperatures during halite precipitation these temperatures are lower than expected for a marginal marine basin at a subtropical paleolatitude and they suggest a climatic cold spell for a period of thousands of years the major ions in fluid inclusion brines analyzed using the esem x ray eds method have relatively low concentrations of na mg2 and so42 and elevated concentrations of ca2 compared to modern seawater brine inclusion chemistries from the f 1 salt compare closely with the major ion composition of fluid inclusions from other silurian marine halites a 1 a 2 and b evaporites of the salina group and carribuddy group canning basin australia these results indicate a seawater parentage of the michigan basin f 1 salts and that the major ion chemistry of seawater remained more or less constant during the last 15 million years of the silurian detailed documentation of the temperatures brine chemistries and environments of halite deposition is a prerequisite for geobiological study of the entrapment of ancient microbes in salt the results reported here can help pinpoint the timing of entrapment of microorganisms in fluid inclusions in halite and can be used to argue that brine inclusions in the f 1 halites have been isolated and preserved in an unmodified state for more than 400 million years

sedimentology of acid saline lakes in southern western australia newly described processes and products of an extreme environment naturally acid saline systems with ph values between 1 7 and 4 are common on the yilgarn craton of southern western australia a combination of physical and chemical processes here yield a previously undescribed type of modern sedimentary environment flooding evapoconcentration desiccation and eolian transport at the surface as well as influx of acid saline groundwaters strongly influence these lakes halite gypsum kaolinite and iron oxides precipitate from acid hypersaline lake waters shallow acid saline groundwaters affect the sediments of the lakes and associated mudflats sandflats channels and dunes by precipitating early diagenetic halite gypsum iron oxides clays jarosite and alunite these modern environments would likely yield a rock record composed mostly of bedded red siliciclastic and reworked gypsum sand alternating with less common beds of bottom growth gypsum and halite with alteration by early diagenetic features diagnostic of acid saline waters this documentation of sedimentary processes and products of modern acid saline environments is an addition to the comparative sedimentology knowledge base and an expansion of the traditional models for classifying brines implications include better interpretations of terrestrial redbeds and lithified martian strata improved acid remediation methods new models for the formation and occlusion of pores and the new setting for finding previously undescribed extremophiles

spreading of salt structures in the gulf of mexico abstract past and present overhangs on diapirs ductile intrusions of salt are potential hydrocarbon traps and increasing numbers of larger overhangs are being recognised as seismic acquisition and processing improves salt overhangs develop by three process drag by ductile surroundings sinking around salt diapirs thinning of diapiric stems or the topic considered here gravity spreading gravity spreads salt where it is easier for salt to flow sideways than it is to float or sink the potential level to which individual salt diapirs rise depends on the pressure applied to their source by the overburden load and any lateral forces the potential level to which salt diapirs rise can be independent of both the top free surface and the level of neutral buoyancy of the salt even the most vigorous diapirs cannot rise indefinitely they gravitationally spread at barriers they cannot penetrate below at or above their level of neutral buoyancy it has been suggested that salt diapirs spread below their level of neutral buoyancy in weak layers beneath stiff barriers however no case of deep subsurface salt spreading appears to have been documented instead shales rise with salt along the us gulf coast some salt diapirs in the gulf of mexico may simulate ductile ice flows and spread both upwards and downwards to a subsurface level of neutral buoyancy in surroundings of similar strain rate however most diapirs in the gulf are driven above their level of neutral buoyancy so that they spread downwards back towards it these spread over denser or stifter layers in less dense and weaker barriers of air water or unconsolidated sediments this work focuses on the geological implications of the shapes of the tops of small scale secondary salt bodies that spread superficially in weaker and less dense barriers under the northern gulf of mexico analytical material and natural models are used to show that the shape of the top free surface of spreading salt contains information about both the properties of the materials involved and their kinematics many salt diapirs in the gulf spread downslope from viscous salt fountains in muds over sand salt flowing downslope towards a lower level of neutral buoyancy exhibits dynamic extrusion the temporary dynamic nature of salt sheets is emphasised by restating standard arguments for overburden strength in terms of low strain rates contrary to recent views that salt spreading occurs in weak horizons during fast sedimentation it is argued that most salt spreads superficially during periods of slow sedimentation small salt laccoliths advance downslope at long term rates between 1 and 5 mm a after burial spreading and gliding of their overburdens can detach such laccoliths from their source and smear them to salt sills that advance downslope at 8 mm a as development wells are likely to be complicated by such active salt flow we should begin now direct measurements of the rates at which salt spreads at superficial levels beneath the northern gulf of mexico

new constraints on carbonate diagenesis from integrated sr and s isotopic and rare earth element data jurassic smackover formation u s gulf coast a reply isotopic sr s o c and trace element including rare earth element ree compositions of calcite cements metal sulfides and sulfate minerals from oolitic carbonate grainstones of the smackover formation jurassic southwest arkansas shelf constrain the mechanism of sulfate reduction and establish temporal relations between sulfur and carbonate diagenesis strontium isotopic values of calcite cements range from near jurassic age sea water values 0 7068 up to values of 0 7096 this evidence coupled with variation in o and c isotopic compositions and in cement zoning under cathodoluminescence suggests that calcite cement precipitated over the course of burial diagenesis strontium isotopic compositions of pyrite marcasite and native s range up to maximum values observed for calcite cements but galena and sphalerite are less radiogenic the sr contents of sulfides and native s are 30ppm but the rb content is sufficiently low that in situ growth of87sr would not dramatically alter the initial sr isotope ratio diagenetic sulfate minerals also exhibit a range of sr isotopic compositions anhydrites range from 0 7071 to 0 7081 while celestites are more radiogenic 0 7096 the ree patterns of early and late calcite cements and framework grains differ using sm yb ratios as an indicator of heavy vs light ree enrichment early calcites have sm yb ratios 1 whereas late calcite cements have ratios of 1 8 3 2 importantly both cement signatures differ from framework grain ratios 1 3 1 7 indicating lack of rock buffering in fluids from which the cements precipitated furthermore the sympathetic increase in sm yb and sr isotopic ratios from early to late calcites is consistent with input of light ree from siliciclastic sources sulfur isotopic compositions of metal sulfide minerals range from 32 to 8 cdt native s and anhydrite values 18 are near jurassic age sulfate values while celestites are heavier 28 although thermochemical sulfate reduction has been proposed to explain h2s in deeply buried carbonate units associated with evaporite s lack of s isotopic homogenization between sulfate and sulfide minerals lack of s isotopic equilibration of oil with reservoir so4 and the limited distribution of h2s rich brines in southwest arkansas demand a more complex origin

the nature of roof thrusts in the moine thrust belt nw scotland implications for the structural evolution of thrust belts buried thrust systems commonly analysed in terms of duplex structures are often interpreted as forming in a particular sequence this model considers that only one thrust is active at a time and the resulting structural geometry is well ordered however a reappraisal of structural geometries from the moine thrust belt in nw scotland has shown that many apparent duplex structures are more complex although the upper roof thrust of some duplexes may be folded and bulged by underlying imbricate slices in accordance with simple duplex models the footwall to these roof thrusts cut up and down stratigraphic section in conflict with the simple duplex models examples include the glencoul thrust with its underlying imbricate system and the foinaven duplex simultaneous slip on an array of imbricate thrusts can bulge duplex roofs relationships classically used to infer piggy back sequences of thrust propagation however activity on more hinterland ward imbricate thrusts can cause the roof onto which they branch to truncate more foreland ward structures in this fashion the duplex roof can cut up and down stratigraphic section mimicking an extensional fault by varying thrust activity in three dimensions within an imbricate system local parts of roof thrusts can generate domains of overstep behaviour that have only local significance existing interpretations of overstep relationships in the moine thrust belt as representing late orogenic low angle extensional faults may need revision the new interpretations of deformation activity where displacements in thrust arrays happen synchronously rather than sequentially are consistent with emergent thrust and fold belts with analogue experiments and with mechanical models of orogenic wedges

active faulting and folding without topographic expression in an evaporite basin chile the salar de atacama in northern chile accumulated halite during the pliocene and quaternary under conditions that alternated between a saline lake and a dry salt flat hidden beneath its uninterrupted flat surface is the salar fault system the halite deposits provide a high resolution history of deformation contours on the ca 5 ma base of the halite unit in the southern salar defined in a deep oil exploration borehole and traced through reflection seismic lines reveal that net reverse offset across the salar fault system is down to the east by 900 m of that total 200 m occurred during the quaternary and 700 m during the pliocene distributions thicknesses and geometries of eight stratigraphic sequences within the halite unit reveal a history of episodic faulting and demonstrate that faulting during approximately half the 5 m y interval including the holocene did not generate fault scarps we suggest that deposition caused by evaporation of ground water brines in the salt flat rather than either dissolution or deflation has smoothed the topography of the dry lake bed across the active fault zone for the case of west directed groundwater flow we propose that the east facing salar fault system focuses groundwater flux along the eastern flank of the fault which enhances halite precipitation in the downthrown block during desiccated stages and counteracts fault driven topographic relief the realization that a seismic risk may exist even though the salar fault system is hidden leads to the appreciation that similar unrecognized seismic risks may exist in more populous arid basins

contrasting siliciclastic evaporite strata in subsurface and outcrop an example from the permian nippewalla group of kansas u s a abstract geologists tend to expect that rocks as they appear in outcrop are a very good approximation of the same strata in the subsurface but this is not the case in mixed siliciclastic evaporite units strata that contain both a siliciclastic and an evaporite mineral component distinct differences in lithologic and stratigraphic descriptions of ancient siliciclastic evaporite strata exist between outcrop and core these differences present challenges in stratigraphic nomenclature lithologic correlation age determinations and interpretations about past depositional environments diagenetic history and paleoclimate an example of siliciclastic evaporite strata is the middle permian to early triassic gypsum and or anhydrite hereby referred to as gypsum anhydrite and halite bearing red beds throughout the midcontinent of north america and equivalent strata from other pangean deposits here we use core and field observations of the middle permian nippewalla group in kansas to show the range of similarities and differences in lithologies and thicknesses of specific lithofacies in outcrop and at various depths for example the displacive halite lithology consisting of red mudstones dominated by randomly oriented halite crystals is abundant in cores and interpreted as saline mudflat deposits the outcrop counterpart is less common friable massive red mudstones with some gypsum anhydrite pseudomorphs after displacive halite crystals we interpret these lithologic differences of this saline mudflat lithofacies as the result of excellent preservation of buried displacive halite and late stage dissolution of near surface halite additionally bedded halite and intergranular halite cements in siltstones and sandstones are also vulnerable to late stage dissolution near the surface further modifying lithologies and thicknesses thickness of the nippewalla group in the amoco rebecca k bounds core of western kansas is 931 feet 284 meters thick but it is estimated to be only half as thick in the outcrop belt of south central kansas to estimate amount of rock lost to late stage dissolution we conducted dissolution experiments on displacive halite units from cores which resulted in 60 95 loss of rock thickness and mass due to dissolution of halite the unconsolidated red sediment resulting from these dissolution experiments compares favorably with much of the fine massive red siliciclastics that make up the greater part of the nippewalla group outcrops we propose that major lithologic differences resulting from near surface diagenetic processes must be expected in any evaporite bearing siliciclastic unit besides guiding correlation attempts between surface and subsurface this knowledge is vital for making accurate interpretations of depositional and diagenetic history of siliciclastic evaporite units

a 106ka paleoclimate record from drill core of the salar de atacama northern chile abstract a 100 m long salt core sqm 2005 from the salar de atacama northern chile 23 s 68 w a dry lake bed contains a 106 kyr paleoclimate record of hydrologic balances on the western slopes of the central andes of south america six u series disequilibrium dates range sequentially from 106 1 6 4 to 5 4 2 7 ka based on sedimentary structures and petrographic textures of salts and associated siliciclastic sediments interpretations of paleoenvironments and net hydrologic balance suggest that relatively wet periods saline lakes and expanded mudflats existed in the salar de atacama from 75 7 to 60 7 ka and from 53 4 to 15 3 ka with the wettest perennial lake interval from 26 7 to 16 5 ka short relatively wet periods also occurred in the holocene from 11 4 to 10 2 ka and from 6 2 to 3 5 ka these wet periods at salar de atacama correspond well with other late pleistocene climate records from the central andes that are a function of the net hydrologic budget the minchin tauca lake sequence from salar de uyuni bolivia is synchronous with the 53 4 15 3 ka saline lake wet period at salar de atacama the tauca phase coincided with the wettest perennial lake interval at salar de atacama from 26 7 to 16 5 ka the coipasa lake phase from uyuni was probably contemporaneous with the early holocene wet period at salar de atacama from 11 4 to 10 2 ka the early holocene wet interval at salar de atacama was also synchronous with the maximum holocene lake levels of the chilean altiplano lakes to the east and with grass rich rodent middens between 11 8 and 10 5 ka in age from the atacama basin the lake period at salar de atacama between 26 7 and 15 3 ka compares closely with low 18o values low anion concentrations and high accumulation rates from the sajama glacial ice core southwestern bolivia between 25 and 15 5 ka it is concluded that wet and dry phases were synchronous in the central andean plateau of southwestern bolivia and along the western flank of the andes of northern chile over the past 50 kyr this region which today receives its moisture from the amazon basin to the east probably also did so in the past the wet periods at salar de atacama are in phase with january insolation maxima at 15 s at 70 45 and 20 ka which suggests that past changes in summer insolation influenced precipitation patterns in the central andes however there are no major wet periods linked to the january insolation maximum at 93 ka and the present day extremely dry climate in the atacama desert is associated with a peak in summer insolation therefore there must be other important influences over precipitation in the central andes which modify the first order insolation controls

the evaluation of brine prospects and the requirement for modifications to filing standards the recent increase in demand for lithium has led to the development of new brine prospects particularly in the central andes the brines are hosted in closed basin aquifers of two types mature halite dominant and immature clastic dominant the estimate of elemental resources in these salars depends on a detailed knowledge of aquifer geometry porosity and brine grade the geometry of the aquifers can be evaluated by classical geophysical and drilling techniques but because the resource is a fluid with the attendant problems of in aquifer mixing and reorganization existing codes for filing resource and reserve estimates need modification total porosity is relatively straightforward to measure but effective porosity and specific yield which are required to estimate the resource are more difficult recovery factors are low compared with most metalliferous and industrial mineral deposits due to reliance on pumping of the brine from wells for extraction these and related issues lead us to believe that modifications to the existing standards for reporting mineral resources and reserves are required for these prospects

palaeohydrological evolution and implications for palaeoclimate since the late glacial at laguna de fuente de piedra southern spain abstract here we present a terrestrial multi proxy record of late quaternary environmental changes in the southern iberian peninsula covering approximately 30 ka this sedimentary record originates from a saline playa lake laguna de fuente de piedra hosted within a complex geological setting dominated by triassic claystones and evaporites jurassic carbonates and miocene deposits leading to a complex hydrogeological setting dissolution of evaporites in the catchment and intense evaporation are responsible for saline waters fluctuating in the basin thus salinity as palaeohydrological proxy requires a decoupling of internal and external hydrogeochemical processes the greatest accumulation of evaporites in the lfp late pleistocene holocene record coincides with a more humid or at least less evaporative period based on multi proxy data we describe five lacustrine lithofacies 2 5 and fluvial deposits 1 from sediment cores the proposed conceptual lake margin model contains three main lake water stages repeated within the sedimentary succession and building up the characteristic lithofacies lake water stages refer to a flooding stage influx outflux high water stage influx outflux and low water stage influx

a large methane plume east of bear island barents sea implications for the marine methane cycle a pockmark field extending over 35 km2 at 74 54 n 27 3 e described by solheim and elverhoi 1993 was re surveyed and found to be covered with more than 30 steep sided craters between 300 and 700 m in diameter and up to 28 m deep the craters are thought to have been formed by an explosive gas eruption anomalously high concentrations of methane in the shelf waters around the craters suggest that a strong methane source near this area is still active today methane enrichment more than 10 km away from the crater field indicates the large dimensions of a plume and the amount of gas released from sources below the seafloor of the barents sea shelf from the characteristic vertical decrease of methane towards the sea surface it is concluded that biota are extensively using this energy pool and reducing the methane concentration within the water column by about 98 between 300 m depth and the sea surface degassing to the atmosphere is minimal based on the shape of the methane concentration gradient nevertheless the net flux of methane from this area of the barents sea is about 2 9 104 g ch4 km 2 yr 1 and thus in the upper range of the presently estimated global marine methane release this flux is a minimum estimate and is likely to increase seasonally when rough weather leads to more effective vertical mixing during autumn and winter the amount of methane consumed in the water column however is about 50 times greater and hence should significantly contribute to the marine carbon inventory

wind erosion on the north eastern tibetan plateau constraints from osl and u th dating of playa salt crust in the qaidam basin the arid qaidam basin is the largest 3 88 x 10 4 km 2 basin on the north eastern tibetan plateau wind erosion in the area has been regarded as an important trigger for intra basin tectonic balance upheaval geomorphologic development and as a major supplier of dust to the chinese loess plateau downwind an initial estimate of the rate of wind erosion kapp et al 2011 based on geological cross sections has suggested up to 3 2 x 10 4 km 3 of sediments has been deflated over the past 2 8 ma lowering the landscape by an average of 0 29 mm yr in this paper we re evaluate this estimate by dating surface crusts present on three playas within the basin understanding the development of these playas is crucial to assessing the overall role of the wind in shaping the regional landscape because they are typically capped with a thick salt crust which effectively protects them from wind erosion optically stimulated luminescence osl and u series dating from a pit section and from the top of a deep drill core together with results from magnetostratigraphy and a climate proxy record correlated to the marine oxygen isotope record are used here to determine the age of the playa plains and suggest that the salt crusts have an age of c 0 1 ma this young age and the wide distribution of resistant thick salt crusts of the playa plains indicate a much lower degree of wind erosion than previously suggested the crusts protect the surface from significant surface erosion including sediment exhumation and unloading and whilst some wind erosion does occur it is unlikely to be sufficient to trigger tectonic uplift of the basin or to be a major dust source for the loess plateau as previously suggested copyright c 2013 john wiley sons ltd

contributions of denitrification and mixing on the distribution of nitrous oxide in the north pacific 1 we analyzed n2o isotopomer ratios distribution of isotopes within n2o molecules in the eastern tropical north pacific the n2o isotopomer ratios indicate the contribution of denitrification in the oxygen minimum zone omz 600 m in depth in the western north pacific which is not consistent with the widely accepted nitrification hypothesis our models indicate that the n2o yield per mole o2 consumed dn2o do2 is 0 008 0 0 015 nmol mol during remineralization and nitrification in the western north pacific nitrification in aerobic deep waters is a minor source of oceanic n2o whereas the n2o production in the omz is the dominant factor for the oceanic n2o distribution the denitrification in the omz is consistent with the correlation between n2o level above atmospheric equilibrium and aou apparent oxygen utilization and the parallel 18o enrichment of n2o and o2 in the omz which have been believed to support the nitrification hypothesis

structural micro structural and kinematic analyses of channel flow in the karmostaj salt diapir in the zagros foreland folded belt fars province iran abstract one of the main characteristic of the zagros foreland fold and thrust belt and the zagros foreland folded belt are wide distributions of surface extrusion from the hormuz salt diapirs this study examines the structure and kinematic of channel flow in the karmostaj salt diapir in the southwestern part of the zagros foreland folded belt this diapir has reached the surface as a result of the channel flow mechanism and has extruded in the southern limb of the kuh gach anticline which is an asymmetric decollement fold with convergence to the south structural and microstructural studies and quantitative finite strain rs and kinematic vorticity number wk analyses were carried out within this salt diapir and its namakier this was in order to investigate the structural evolution in the salt diapiric system the characteristics and mechanism of the salt flow and the distribution of flow regimes within the salt diapir and interaction of regional tectonics and salt diaprism the extruded salt has developed a flow foliation sub parallel to the remnant bedding recorded by different colors a variety of internal folds including symmetrical and asymmetrical folds and interference fold patterns shear zones and boudins these structures were used to analyze mechanisms and history of diapiric flow and extrusion the microstructures reveal various deformation mechanisms in various parts of salt diapir the measurements of finite strain show that rs values in the margin of salt diapir are higher than within its namakier which is consistent with the results of structural studies mean kinematic vorticity number wm measured in steady state deformation of diapir and namakier is wm 0 45 0 48 0 13 the estimated mean finite deformation wm values indicate that 67 8 pure shear and 32 2 simple shear deformation were involved the implications of which are discussed the vorticity of flow indicates that in the early stage of growth poiseuille flow was the dominate mechanism especially in the core of diapir with higher pure shear component relative to simple shear component whilst a couette flow at the margins of diapir is the dominate mechanism with higher simple shear component relative to pure shear component the obtained kinematic vorticity number reflects spatial partitioning of dominantly poiseuille flow in core and couette flow along edges of diapir these two mechanisms reflect a persistent flow governed by a simultaneous combination of pure shear and simple shear in a hybrid poiseuille coutte flow

sedimentology of ancient saline pans an example from the permian opeche shale williston basin north dakota u s a abstract the mid permian opeche shale of north dakota consists of bedded evaporites and red bed siliciclastics detailed core and petrographic study has documented sedimentary and early diagenetic features in order to develop a depositional model and to refine paleoclimatic data and paleogeographic setting for the late paleozoic of the u s midcontinent lithologies and sedimentary features indicate lacustrine distal alluvial and minor eolian deposition subaerial exposure and soil formation bedded halites consisting of chevron and cumulate crystals dissolution surfaces and pipes and mudcracked microcrystalline salt crusts were deposited in a saline pan dominated by flooding evaporative concentration and desiccation bedded halites containing chevron and cumulate crystals but lacking any dissolution or desiccation features formed in perennial saline lakes chaotic halite composed of red mudstone and siltstone with displacive halite crystals represents saline mudflat deposits red mudstone and siltstone with little or no displacive halite but with abundant cracks and root features suggest deposition in a dry mudflat red bed sandstones and conglomerates composed of poorly sorted subrounded quartz grains cemented with halite indicate distal alluvial deposition with possible transport by ephemeral streams sheet floods and debris flows most deposition took place in halite dominated shallow perennial and ephemeral saline lakes surrounded by saline and dry mudflats evaporation desiccation flooding and wind played significant roles in this environment therefore the opeche evaporites and red beds are representative of an ancient saline pan system an inland playa setting is favored as a depositional model for the opeche shale the abundance of soil features and halite dominance as well as lack of nearshore carbonates and lack of restricted marine fossils suggest a closed basin nonmarine setting for the mid permian of the u s midcontinent

coupled fluid flow and sediment deformation in margin scale salt tectonic systems 1 development and application of simple single lithology models 1 a methodology is presented to model coupled fluid flow and deformation in rifted continental margin composite salt and siliciclastic tectonic systems and we investigate their compaction and overpressuring behavior associated with continental margin scale gravitational spreading compaction driven darcy fluid flow in clastic sediments is coupled through the effective pressure to their frictional plastic yielding and mechanical deformation viscous flow of underlying salt is independent of fluid pressure numerical models are adapted to the oligo miocene phase of large scale gravitational failure in the northwestern gulf of mexico and represent the first study of this system that includes dynamically evolving fluid pressure here we present the methodology and prototype models with single uniform sediment lithologies and simple parameterizations of their properties the models serve to illustrate the interactions among compaction generation of fluid overpressure and gravitational failure and spreading mechanical and viscous compaction behavior of sandstone type and shale type sediments are investigated results demonstrate that mechanical compaction can generate moderate overpressure in thick shale type material whereas high overpressure requires viscous compaction in sandstone type material only viscous compaction can generate significant overpressure though this requires tens of millions of years changes in the stress regime during gravitational driven deformation enhance compaction and overpressure although illustrative of the methodology and basic processes none of the prototype single lithology models satisfactorily reproduces oligo miocene fluid pressure and deformational regimes of the gulf of mexico numerical models of layered sediments together with an improved formulation of viscous compaction presented in part 2 of this set of companion papers are more successful

halite cementation and carbonate diagenesis of intra salt reservoirs from the late neoproterozoic to early cambrian ara group south oman salt basin late neoproterozoic to early cambrian carbonates of the ara group form important intra salt stringer reservoirs in the south oman salt basin differential loading of thick continental clastics above the six carbonate to evaporite cycles of the ara group led to the formation of salt diapirs encasing a predominantly self charging hydrocarbon system within partly highly overpressured carbonate bodies stringers these carbonates underwent a complex diagenetic evolution with one stage of halite cementation in a shallow early and another in a deep late burial environment early and late halite cements are defined by their microstructural relationship with solid bitumen the early phase of halite cementation is post dated by solid reservoir bitumen this phase is most pervasive towards the top of carbonate stringers where it plugs nearly all available porosity in facies with initially favourable poroperm characteristics bromine geochemistry revealed significantly higher bromine contents up to 280 p p m in the early halite compared with the late halite 173 p p m the distribution patterns and the high bromine contents of early halite are consistent with precipitation caused by seepage reflux of highly saturated brines during deposition of the overlying rock salt interval later in burial history relatively small quantities of early halite were dissolved locally and re precipitated as indicated by inclusions of streaky solid bitumen within the late halite cements late halite cement also seals fractures which show evidence for repeated reopening initially these fractures formed during a period of hydrothermal activity and were later reopened by a crack seal mechanism caused by high fluid overpressures porosity plugging by early halite cements affects the poroperm characteristics of the ara carbonates much more than the volumetrically less important late halite cement the formation mechanisms and distribution patterns of halite cementation processes in the south oman salt basin can be generalized to other petroliferous evaporite basins

sulfate cavity filling in the lower werra anhydrite zechstein permian zdrada area northern poland evidence for early diagenetic evaporite paleokarst formed under sedimentary cover abstract paleokarst developed in sulfate deposits is common and it is usually formed along the contact with the overlying permeable rocks or it is due to near surface dissolution of bedded evaporites in the lower werra anhydrite zechstein of northern poland the paleokarst cavities are usually filled by bluish semitransparent anhydrite and more rarely by celestite polyhalite halite and carbonate in small cavities a few centimeters across a rim of rod like anhydrite crystals arranged in narrow bundles occurs and the inner part of the cavity is filled with a mosaic aggregate of short prismatic crystals of anhydrite and celestite as well as coarse irregular anhydrite celestite crystals and fan shaped aggregates as well as spherulites of anhydrite are rare in bigger cavities some ten centimeters across multiple zones of fibrous anhydrite are arranged in different directions in the middle part of the cavity fill the innermost parts of large karst cavities remain hollow in some cases with the cavity walls encrusted by coarse well developed crystals of anhydrite and celestite the karst cavities in the lower werra anhydrite developed in the subsurface by dissolution of caso4 strata in halite rich intervals due to gypsum dehydration water during gypsum dehydration dissolution of that halite would have increased the sodium chloride content of the solution and thus the solubility of calcium sulfate dissolved calcium sulfate was removed from a leaching zone by diffusion and or downward flow in interstitial space and the minerals in karst cavities precipitated from the same solutions as those solutions became oversaturated because of decreases in nacl concentration over time this study suggests that karst in sulfate deposits can develop in the subsurface and without uplift and or near surface conditions

submarine salt flows in the central red sea the central red sea an oceanic basin floored by miocene evaporites reaching kilome ters in thickness in places is at an early stage of development where seafl oor spreading has geologically only recently replaced continental rifting surveys using a high resolution multibeam echo sounder around thetis deep a new spreading center have revealed a remarkable series of structures resembling viscous gravity fl ows which are here interpreted as originating from fl owage of the evaporites laterally unloaded by axial rifting and other processes developing the relief of the deep the fl ow margins are marked by stream wise lineaments and some apparently rotated markers their fronts in the fl oor of the deep are rounded in plan view and profi le their surfaces contain small closely spaced features resembling extensional faults in one area below declining gradients the surface contains along slope ridges and valleys typical of compression folds ogives flowparallel lineaments and extensional faults lie respectively parallel and orthogonal to the direction of maximum seabed gradient movement is apparently heterogeneous at least in part because of varied blocking by relief in underlying basement observed protruding between fl ows flowage is currently transporting materials into the fl oor of the deep where they have the potential to become incorporated into the young oceanic crust by repeated eruption of axial lavas over them in the light of these new data we reexamine the possibility and implications of fl owage in the south atlantic marginal evaporites in particular whether fl owage contaminated early oceanic crust in such areas

paleotemperatures from fluid inclusions in halite method verification and a 100 000 year paleotemperature record death valley ca abstract maximum homogenization temperatures of fluid inclusions thmax in halite laboratory grown crystals and modern samples death valley ca match maximum brine temperatures during halite precipitation maximum brine temperatures during halite precipitation in death valley late april 1993 34 4 c agree with thmax 34 c and correlate well with average maximum air temperatures in april 31 3 c and may 37 6 c thmax may be used for paleoclimate interpretations based on the close relationship between saline lake temperatures and average air temperatures from modern settings lower homogenization temperatures demonstrably below the temperatures at which halite grew are interpreted to reflect collapse of some fluid inclusion walls due to the pressure difference between the inside and outside of inclusions by only using thmax the problems of anomalously low homogenization temperatures due to possible collapse of fluid inclusions are avoided halite samples from 30 stratigraphic intervals 90 to 0 m 100 to 0 ka core dv93 1 death valley ca were used to measure homogenization temperatures of fluid inclusions virtually all homogenization temperatures from core dv93 1 are below the modern thmax of 34 c halite precipitation late april 1993 lacustrine halites deposited in a perennial saline lake 35 to 10 ka have thmax between 19 c and 30 c which suggests brine temperatures approximately 4 c to 15 c below modern late april values ephemeral saline lake halites precipitated 60 to 35 ka have thmax between 23 c and 28 c 6 to 11 c below modern values the highest thmax value in the 100 ka record up to 35 c is from a halite sample formed approximately 100 ka in a climate regime somewhat colder than the modern

structural evolution of continental and marine permian rock salt of the north german basin constraints from microfabrics geochemistry and u pb ages analyzing the dynamics of microstructural response on natural deformation in rock salt we present microfabric ebsd geochemical and u pb data obtained from permian salt formations of the kiel honigsee salt wall in northern germany the samples were recovered from deep drillings which penetrated through an overturned rock salt sequence of both rotliegend and zechstein deposits the bromide concentration in halite indicates a continental and marine origin for the rotliegend and zechstein deposits respectively despite intense deformation relics of early diagenetic fabrics are still preserved deformation of the impure rotliegend rock salt was accommodated by pressure solution and hydrofracturing as is indicated by the microfabrics and bromide concentration in halite fractures in siliciclastic domains were filled with fibrous halite and deformed by subgrain rotation recrystallization sgr fluid rich zechstein rock salt on the other hand was deformed by formation of subgrains and grain boundary migration gbm the distribution of mineral phases and fluids had a significant impact on the fabric evolution and on strain localization u pb dating of carbonate phases of the rotliegend sequence yielded permian depositional ages and jurassic to cretaceous deformation ages the latter related to diapiric ascent the combination of results traces a dynamic evolution of the rock fabric inside the diapir structure driven by locally active deformation processes that can be correlated with early stages of halite deposition and diagenesis and syntectonic fabric reorganization related to diapirism in an extensional setting

an assessment of stratigraphic completeness in climate sensitive closed basin lake sediments salar de atacama chile abstract dated subsurface cores 40 m 100 m and 200 m in length from the salar de atacama chile record changes in climate and tectonics over the past 325 ka these cores were used to assess completeness of the stratigraphic record and how that record was influenced by faulting and climate change the same basic facies efflorescent halite crust and cement subaerial halite and chevron halite saline lake occur in each core the dominant facies is efflorescent halite formed in a subaerial environment like that in the atacama basin today thick well preserved efflorescent crusts in the salar de atacama cores illustrate that major sediment aggradation occurred in subaerial environments by growth of efflorescent halite from evaporation of groundwater brines similar pedogenically formed evaporites may be pre served in the geologic record the n s trending salar fault system has downdropped the eastern block of the salar de atacama core 2002 relative to the western block cores 2005 and 2031 relative faulting rates over the past 60 ka were determined from stratigraphic offset and uranium series ages from core 2005 major faulting along the salar fault system occurred between 16 5 and 5 4 ka with offset of 26 5 m and faulting rates of 2 4 m kyr aggradation of efflorescent halite crusts on the downdropped eastern block served to smooth out topographic variations created by faulting although stratigraphic units in core 2002 shifted down 30 m over the past 60 ka the thickness and sedimentary features are similar for all but one equivalent stratigraphic unit in all three cores faulting along the salar fault system despite significant offset did not alter the basic stratigraphic record temporal completeness of the stratigraphic record within the limits of the age dates and their errors of greater than 3 ka was examined qualitatively by comparing long term sedimentation rates 0 6 0 9 m kyr and shorter term sedimentation rates 0 3 3 6 m kyr the similarity of sedimentation rates on the 10 kyr scale and the longer 100 to 300 kyr scale suggests temporal completeness of salar de atacama sediments at least at the 10 kyr scale although hiatuses long periods of subaerial exposure and dissolution of evaporites may have occurred the main climate fluctuations at salar de atacama over the last 100 ka are recorded in all three subsurface cores paleoclimate records obtained from such cores are therefore representative of basin wide climate change and are valid for regional paleoclimate reconstructions

origin of deformed halite hopper crystals pseudomorphic anhydrite cubes and polyhalite in alpine evaporites austria germany the alpine haselgebirge formation represents an upper permian to lower triassic evaporitic rift succession of the northern calcareous alps eastern alps although the rocksalt body deposits are highly tectonised consisting mainly of protocataclasites and mylonites of halite and mudrock the early diagenetic history can be established from non tectonised mudrock bodies cm sized euhedral halite hopper crystals formed as displacive cubes within mud just during shallow burial the crystals were deformed by subsequent compaction later migrating fluids led to the replacement of halite by anhydrite retaining the shapes of deformed halite cubes polyhalite formed from subsequent enhanced fluid migration mudrock provided water by dewatering while potassium and magnesium were dissolved from primary salt minerals when these fluids interacted with sulphates polyhalite precipitated 40ar 39ar analyses date the polyhalite from within the retaining shapes of deformed halite hopper shaped cubes from two localities to ca 235 232 ma middle triassic at this time ca 20 25 ma after sedimentation polyhalite crystallised at shallow levels