characterization and migration of atmospheric ree in soils and surface waters abstract rainwater and snow collected from three different sites in france vosges mountains french alps and strasbourg show more or less similar shapes of their ree distribution patterns rainwater from strasbourg is the most ree enriched sample whereas precipitations from the two mountainous less polluted catchments are less ree enriched and have concentrations close to seawater they are all strongly lree depleted different water samples from an alpine watershed comprising snow interstitial puddle and streamwater show similar ree distributions with lree enrichment rainwater normalized but mree and hree depletion in this environment where water transfer from the soil to the river is very quick due to the low thickness of the soils it appears that ree in streamwater mainly originate from atmospheric inputs different is the behaviour of the ree in the spring and streamwaters from the vosges mountains these waters of long residence time in the deep soil horizons react with soil and bedrock ree carrying minerals and show especially significant negative eu anomalies compared to atmospheric inputs their sr and nd isotopic data suggest that most of the sr and nd originate from apatite leaching or dissolution soil solutions and soil leachates from the upper soil horizons due to alteration processes strongly depleted in ree carrying minerals have ree distribution patterns close to those of lichens and throughfall throughfall is slightly more enriched especially in light ree than filtered rainwater probably due to leaching of atmospheric particles deposited on the foliage and also to leaf excretion data suggest that sr and nd isotopes of the soil solutions in the upper soil horizons originate from two different sources 1 an atmospheric source with fertilizer dust and seawater components and 2 a source mainly determined by mineral dissolution in the soil these two different sources are also recognizable in the sr and nd isotopic composition of the tree s throughfall solution the atmospheric contributions of sr and nd to throughfall and soil solution are of 20 to 70 and 20 respectively in springwater however the atmospheric sr and ree contribution is not detectable

modelling the effect of evaporation on the salinity 87 sr 86 sr relationship in modern and ancient marginal marine systems the mediterranean messinian salinity crisis abstract palaeosalinity reconstructions in marginal marine environments based on sr isotope data assume simple two end member mixing of river and ocean water an improved model that incorporates the effect of evaporation is used to demonstrate that this approach is not valid in evaporation dominated systems however sr isotope records combined with faunal and lithological constraints on salinity can be used to assess the palaeohydrological conditions of ancient marginal marine systems this new method is used to interpret deviations from the global seawater sr isotope curve observed in mediterranean successions during and up to 3 myr prior to messinian evaporite deposition results suggest that no absolute change in the net evaporation flux is required to explain the three to four fold rise in salinity of mediterranean water at the carbonate evaporite transition modelled sr isotope records indicate that this increase in salinity was synchronous with an increase in the dominance of atlantic water inflow in the hydrological budget of the mediterranean the messinian salinity crisis may therefore have been the response to a marine transgression

origin and emplacement of an inferred late jurassic subduction accretion complex euboea eastern greece in northern euboea central eastern greece an up to 3 km thick polygenetic melange pagondas complex is structurally interleaved between a triassic jurassic carbonate platform pelagonian zone and an overriding harzburgitic ophiolite the melange mainly comprises late triassic shallow water limestone and calciturbidites radiolarites triassic jurassic tholeiites alkaline basalts and minor andesites the units concerned range from kilometre sized thrust sheets and detached blocks to broken formation and structureless or bedded matrix supported conglomerates diamictite the melange includes remnants of neotethyan oceanic lithosphere overlain by radiolarites hemipelagic carbonates and distal calciturbidites derived from a mesozoic carbonate platform tholeiites were erupted at a triassic jurassic spreading axis whilst within plate type alkali basalts are interpreted mainly as seamounts kilometre scale detached blocks of shallow water coralline limestone are identified as collapsed atolls formed within an ocean and or along the rifted continental margin volcaniclastic sediments are locally interbedded with radiolarite and reflect post volcanic erosion of the ocean floor intra oceanic convergence began apparently in late early jurassic time giving rise to the euboea ophiolite above an inferred westwards dipping subduction zone the pagondas complex then developed as an accretionary prism the subduction trench later collided with the pelagonian passive margin driving the hot euobea ophiolite over the accretionary complex to produce amphibolites and greenschists of the metamorphic sole trench margin collision then drove the entire supra subduction zone complex apparently eastwards downflexing the pelagonian carbonate platform to form a foredeep in which late jurassic kimmeridgian tithonian radiolarian sediments accumulated during emplacement the accretionary complex was disrupted and partly resedimented as debris flows turbiditic volcaniclastic sandstone and shale in a foredeep or foreland basin setting

birth death and resurrection the life cycle of suprasubduction zone ophiolites 1 suprasubduction zone ssz ophiolites display a consistent sequence of events during their formation and evolution that suggests that they form in response to processes that are common to all such ophiolites this sequence includes the following 1 birth which entails the formation of the ophiolite above a nascent or reconfigured subduction zone this stage is typically characterized by the eruption of arc tholeiite lavas and the formation of layered gabbros and sheeted dike complex 2 youth during which is continued melting of refractory asthenosphere depleted during birth occurs in response to fluid flux from the subducting slab with extensional deformation of the older plutonic suite eruption of refractory lavas and the intrusion of wehrlite pyroxenite 3 maturity with the onset of semistable arc volcanism typically calc alkaline as the subduction zone matures and stabilizes and the intrusion of quartz diorite and eruption of silicic lavas and 4 death which is the sudden demise of active spreading and ophiolite related volcanism which in many cases is linked to collision with an active spreading center and the onset of shallow underthrusting of the buoyant spreading axis expressed as dikes and lavas with oceanic basalt compositions that crosscut or overlie rocks of the older suites 5 resurrection with emplacement by obduction onto a passive margin or accretionary uplift with continued subduction the early stages 1 3 may be diachronous and each stage may overlap in both time and space the existence of this consistent progression implies that ophiolite formation is not a stochastic event but is a natural consequence of the ssz tectonic setting

major hydrological shifts in the black sea lake in response to ice sheet collapses during mis 6 130 184 ka bp abstract the saalian was one of the largest glaciations during the quaternary with an ice sheet extending considerably wider into the eurasian continent than during other glacials orbital variations caused the ice sheet to switch between growing and shrinking the partial retreat of the ice sheet and meltwater discharge resulted in global sea level rise and increased lake levels of inland seas with broader environmental implications during marine isotope stage 6 mis 6 meltwater entered the formerly enclosed black sea at least twice as documented in a 18o record from anatolian speleothems here we present a sedimentary record from the black sea lake covering mis 6 and provide evidence for three meltwater periods coinciding with insolation maxima bswp 6 1 180 167 ka bp bswp 6 2 160 145 ka bp bswp ii 133 130 ka bp while 18oostracods and sr caostracods point to pronounced meltwater supply and decreasing salinity 87sr 86srostracods shed light on meltwater sources and pathways during all three periods meltwater drained most likely via the dnieper and volga into the black and caspian seas and connected both basins relatively low 87sr 86srostracods values during the oldest meltwater period suggest melting solely of the eastern eurasian ice sheet in contrast during the younger meltwater periods exceptional high 87sr 86srostracods values point towards additional meltwater from the western eurasian ice sheet a surplus from melting glaciers in the tian shan and pamir mountains that finally entered the caspian sea via the amu darya and sry darya probably amplified the input of high radiogenic sr isotope water we also show that higher temperatures and productivity suggest dansgaard oeschger like climate variability during the first half of mis 6

structure of the musandam culmination sultanate of oman and united arab emirates and the straits of hormuz syntaxis the musandam mountains form a link both in time and space between the late cretaceous ophiolite obduction tectonics of the oman mountains and the late tertiary continental collision tectonics of the zagros fold belt of iran culmination of the musandam shelf carbonates occurred after the turonian maastrichtian thin skinned thrusting of the oman mountains was completed the basal hagab thrust cuts up section to the west from at least mid permian level up to the late cretaceous aruma group and breached up into the overlying previously allochthonous cretaceous hawasina cherts in the hagil window ras al khaimah the shelf carbonates show from 4 to 15 km of westward translation extrapolation of foreland sequences suggests that upper cretaceous aruma group and hawasina complex sediments could occur in the subsurface along the footwall east of the mountain front the hagab thrust and musandam structures plunge south southwest at increasingly greater depth and with decreasing amount of translation and carry all overlying late cretaceous thrust sheets of the oman mountains in a piggy back fashion the eocene lr oligocene pabdeh foredeep developed as a result of loading in front of the musandam thrust sheets wedging out to the south the trailing south eastern edge of the musandam culmination is a hinged listric normal fault downthrowing to the south east up to 2 5 km at bayah and less than 500 m at the western end of batha mahani and is interpreted as a dorsal culmination collapse feature

stable isotope 2h 18o and 87sr 86sr and hydrochemistry monitoring for groundwater hydrodynamics analysis in a karst aquifer gran sasso central italy this paper deals with chemical and isotope analyses of 21 springs which were monitored 3 times in the course of 2001 the monitoring program was focused on the groundwater of the gran sasso carbonate karst aquifer central italy typical of the mountainous mediterranean area based on the hydrogeological setting of the study area 6 groups of springs with different groundwater circulation patterns were distinguished the hydrogeochemistry of their main components provided additional information about groundwater flowpaths confirming the proposed classification the spatial distribution of their ion concentrations validated the assumptions underlying the hydrogeological conceptual model showing diverging groundwater flowpaths from the core to the boundaries of the aquifer geochemical modelling and saturation index computation elucidated water carbonate rock interaction contribution by alluvial aquifers at the karst aquifer boundaries as well as impacts of human activities the analysis of 18o 16o and 2h h values and their spatial distribution in the aquifer substantiated the hydrogeology based classification of 6 groups of springs making it possible to trace back groundwater recharge areas based on mean isotope elevations the latter were calculated by using two rain monitoring stations 87sr 86sr analyses showed seasonal changes in many springs in winter spring the changes are due to inflow of new recharge water infiltrating into younger rocks and thus increasing 87sr 86sr values in summer autumn when there is no recharge and spring discharge declines changes are due to base flow groundwater circulating in more ancient rocks with a subsequent drop in 87sr 86sr values the results of this study stress the contribution that spatio temporal isotope monitoring can give to the definition of groundwater flowpaths and hydrodynamics in fissured and karst aquifers taking into account their hydrogeological and hydrogeochemical setting

stratigraphic versus environmental significance of permian serrated conodonts around the cisuralian guadalupian boundary new evidence from oman abstract conodonts from the cephalopod limestones of rustaq and ba ad oman have for many years been dated as wordian because of the presence of the ammonoid waagenoceras revised definitions for guadalupian stages and major differences of conodont morphology among apparently coeval faunas necessitate a review of this age assignment the lack of serration within the oman conodont faunas as well as from waagenoceras bearing limestone blocks in sicily differs markedly from conodonts in the guadalupian stratotype sections of west texas these differences have previously been interpreted to be the result of upwelling cold bottom water that may have restricted the distribution of serrated warm water jinogondolella species however our samples from oman are dominated by species with a carinal configuration that is comparable to gondolellids from the equatorial warm water province ewwp abundant species include mesogondolella siciliensis in the lower ammonoid beds and mesogondolella idahoensis lamberti in the upper ammonoid beds if cold bottom water currents were present at oman then these taxa must have been pelagic living in warm surficial water in contrast the north cool water province ncwp includes coeval conodonts that have a different carinal configuration and are dominated by long ranging mesogondolella idahoensis idahoensis these taxa and their morphologic variations represent a geographic cline between the ewwp and ncwp in addition early roadian serrated gondolellids have been recognized in temperate cool water settings in the jilin province ne china the phosphoria basin idaho usa and the sverdrup basin arctic canada these serrated forms extend above the lower roadian in only the phosphoria basin indicating a distribution into temperatures cooler than previously thought at least during the early guadalupian other conodonts from the deep water cephalopod limestones of oman include rare shallow warm water sweetognathids suggesting that these too must have been pelagic if true then cold bottom waters probably played little role in conodont distribution the identified conodont taxa at oman best correlate with the uppermost kungurian at the luodian section of south china and in the guadalupe mountains of west texas suggesting that the lack of serration is not a result of cold water but rather of a stratigraphic position prior to the evolution and expansion of serrated gondolellids in the roadian it is possible that other paleoecologic controls affected distribution and an alternative age assignment of early roadian is considered for these conodonts the ammonoids including advanced species of waagenoceras suggest that the best correlation is with the third limestone of the word formation willis ranch member which correlates with the upper roadian according to ratified global stage definitions there is still an apparent discrepancy between conodont and ammonoid ages but discounting previous wordian ages has considerably reduced this associated fusulinaceans cannot resolve this argument because of profound provincialism but they can contribute to correlation of the global stages with tethyan stages it is here suggested that the kungurian correlates with the upper bolorian to upper murgabian and that the roadian correlates with the lower midian or upper murgabian and lower midian

early permian location of western north american terranes based on brachiopod fusulinid and coral biogeography abstract brachiopod rugose coral and fusulinid faunas present in early permian rocks along northern and western margins of north america in both cratonal localities and accreted terranes have been compared statistically allowing refinement in placement of these terranes relative to the north american continental margin at that time statistical tests including conventional and probabilistic indices of similarity as well as multivariate analysis show that the faunas of wrangellia alexander are most similar to those of stikinia and quesnellia and to the yukon canadian rocky mountains part of the continental margin they also show that faunas of the eastern klamath terrane are most similar to those of stikinia quesnellia and the central cordilleran part of the continental margin these results suggest that during the early permian wrangellia alexander was the northernmost of these terranes lying west of the yukon canadian rocky mountains region and the eastern klamath terrane was the southernmost lying west of the central cordillera stikinia and quesnellia were in intermediate positions these relative latitudes are compatible with latitudinal determinations based on paleomagnetic data faunal diversity in the eastern klamath and stikine terranes is similar to that at similar latitudes on the craton whereas diversity in the wrangellia alexander terrane is considerably lower than that of the latitudinally similar yukon canadian rocky mountains area as diversity is in part a function of temperature this may suggest water around the wrangellia alexander terrane was cooler than that along the continental margin therefore we suggest that warm water currents bathed the southern terranes and the southern and central parts of coastal north america whereas cool water currents influenced the northernmost terrane wrangellia alexander revised otsuka similarity coefficients for corals show higher similarities between western north american terranes and the western continental margin than previously published but they still are relatively low this and the overall patterns of similarity and limits on distribution of tethyan corals and fusulinids in the eastern panthalassa suggest that wrangellia alexander stikinia and the eastern klamath terranes were at approximately the same distance estimated at 2000 3000 km from their latitudinally equivalent segments of the north american craton

fractionation of rare earth elements in plants during experimental growth in varied clay substrates abstract the distribution and content of rare earth elements rees were determined in two radish species the cultivated raphanus sativus and the wild raphanus raphanistrum that were grown under laboratory controlled conditions in three substrates consisting of illite for one and two smectite substrates for the others with the two smectite substrates being characterised by different porosities the plants were split into leaves and stems roots for analysis the results indicate that both species take up systematically higher amounts of rees when grown in the illite substrate even considering that the smectite equivalent contains about three times more rees the ree uptake is also more plant species than mineral composition dependent r raphanistrum takes up 3 5 6 7 times more rees than r sativus depending on the substrate its porosity and the considered plant segments increased substrate porosity favours the take up of the rees but no specific uptake is observed in leaves relative to that in the combined stems and roots the transfer of the rees from minerals to plant organs does not appear to induce systematically identical patterns 1 in the case of r sativus a positive eu anomaly is visible in all patterns from both segment groups grown in both substrates when grown in illite the heavy rees are also enriched in the stems and roots which has not been observed in any other organ or in the other substrate and 2 in the case of r raphanistrum a very significant positive gd anomaly which is not expected to fractionate relative to the other rees as do ce and eu is observed in all segments of the plants grown in both substrates a slight negative ce anomaly is also visible in some of the ree patterns suggesting some changes in the oxidation reduction conditions in the substrates near the roots during plant growth the comparison of the ree patterns from leaves relative to those of the roots stems shows that those of r raphanistrum grown in illite provide a spectrum that is very specific with significant deficits in la ce gd tm yb and lu in the leaves in the other cases the patterns do not outline significant differences except for r sativus grown in illite in which the leaves are enriched in light and medium rees from la to gd relative to the stems roots

island arc carbonates characterization and recognition in the ancient geologic record abstract carbonates of island arc origin that are preserved in paleozoic mesozoic terranes of the north american cordillera exhibit a distinctive suite of paleontologic and lithologic features and share a fundamental similarity with limestones forming in modern volcanic arcs this study provides the first detailed synthesis of carbonate depositional systems in island arcs and documents primary sedimentary constituents based on facies relationships and faunal communities models are developed that show patterns in the long term evolution of shallow marine organisms and the construction evolution and demise of carbonate platforms in island arcs a suite of criteria is identified that may be used to differentiate island arc carbonates from limestones that accumulated in other platform settings biogeographic isolation prolonged subsidence steep submarine slopes and tectonic instability of volcanic edifices contribute to the development of relatively high levels of species endemism impoverished normal marine faunas complex provincial affinities and relict biotas in limestones that are characterized by exceptionally thick platform and periplatform sequences fringing and barrier reefs at the shelf margin extensive lagoonal deposits and rapid lateral and vertical facies changes although destructive tectonic and geologic processes in island arcs may hinder determining the original size and extent of the carbonate platform and particular facies types may not be represented e g fringing and barrier reefs may be replaced by sand shoals at the platform margin many characteristics have potential value for identifying carbonates of island arc origin in the ancient rock record apart from being associated with calc alkaline volcanic and volcaniclastic assemblages the most valuable suite of features for recognizing island arc carbonates is marine biotas that exhibit elevated levels of endemism and mixed paleobiogeographic affinities extraordinary thicknesses of platform shallow marine and periplatform carbonates and rapid facies changes between volcanic and carbonate rocks and between shallow and deep water limestones recognizing that an ensemble of features is distinctive within island arc carbonates considerably enhances identification of volcanic arcs in the ancient geologic record and thus improves the likelihood of successfully unraveling the complex geologic history of ocean basins

the marine permian of east and northeast asia an overview of biostratigraphy palaeobiogeography and palaeogeographical implications abstract the permian marine biostratigraphy faunal successions and mutual correlations where possible throughout east and northeast asia are synthesized region by region based on both published literature and the author s field observations in certain parts of the region the correlation of the permian marine successions of ne asia with the permian international timescale and in particular with gondwanan permian marine sequences remains a major challenge due to profound marine provincialism during the permian however by employing biogeographically mixed faunas from east asia se mongolia ne china south primorye of far east russia and the south kitakami terrane of japan as biostratigraphic gateways coupled with some bipolarly and bi temperately shared permian marine taxa and faunas it has been possible to correlate with reasonable confidence some of the high palaeolatitude permian marine rock units and faunas of ne asia with those of the tethyan region and gondwana palaeobiogeographically the permian marine faunas of east and ne asia are assigned to four major provinces verkolyman sino mongolian japanese cathaysian and panthalassan provinces on the basis of their palaeogeographical distribution patterns and characteristics of faunal assemblages of these the sino mongolian japanese province has considerable significance for regional palaeogeographical plate tectonic and palaeoceanographical reconstructions during the middle permian because of its conspicuously mixed cool and warm water marine biota the origin of this biogeographically mixed marine biota is interpreted to have resulted from a combination of some key factors including the increased tectonic convergence between the bureya jiamusi terrane and the sino korean platform during the permian and the intermingling of both warm and cold water ocean currents off the eastern coastal areas of the bureya jiamusi terrane and the sino korean platform during the middle permian

natural tracer approach to characterize groundwater in the coastal sahel of oualidia morocco a natural tracer approach is applied to study the processes of salinization of the coastal carbonate aquifers in the sahel of oualidia morocco analyses of chloride sulfate bromide strontium and nitrate confirm the existence of seawater intrusion and reveal an evaporitic contamination and an anthropogenic pollution affecting both surficial and deep aquifers the evaporitic contamination is explained by the washing away of the gypsum marl of the basement of the limestone of dridrate and also by the rise of evaporitic waters from deep gypsum formations anthropogenic pollution is induced by excessive use of fertilizers in agriculture enrichment by chloride originating from the surface could also be invoked on the other hand to explain chloride content in the surficial aquifer the possible existence of connections between the layers of the aquifer system can be demonstrated by this study

the permian antitropical fusulinoidean genus monodiexodina distribution taxonomy paleobiogeography and paleoecology all the documented occurrences with illustration of specimens of the permian fusulinoidean genus monodiexodina from a total of 33 areas in 11 regions are reviewed and their taxonomic positions are reexamined in this paper among 17 species including two subspecies of monodiexodina in the current taxonomy the following 10 species are recognized as valid m kattaensis m wanneri m caracorumensis m sutchanica m shiptoni m kumensis m wanganensis m neimongolensis m delicata and m rhaphidoformis in addition species once referred to monodiexodina but now should be excluded from the genus are also investigated in terms of their generic positions in reconstructed mid permian paleomap monodiexodina bearing areas can be restored to either northern or southern middle latitudes between high latitudinal cool cold water climatic realm and paleo tropical warm water realm these two middle latitudinal areas each corresponding to the northern and southern transitional zones respectively can be best interpreted climatologically as mesothermal warm temperate belts in both hemispheres thus suggesting the genus to be a paleobiogeographically typical antitropical fusulinoidean taxon moreover the genus is generally found in a monotypic crowded manner in sandy sediments with their shells being often aligned uni directionally this mode of occurrence of monodiexodina strongly suggests that it was adapted to shallow marine high energy environments which would probably be essentially maintained by the acquisition of highly elongated fusiform subcylindrical shells with well developed polar torsion this morphological feature is adapted to increase septal pores per unit area in polar regions thus increasing possibility to develop more pseudopodia on both sides of test it probably has a functional significance for not only locomotion but also anchoring their tests on the surface of bottom sediments in agitated water conditions the genus itself is considered to be a rather long ranging taxon from the late yakhtashian artinskian to the early midian capitanian it is therefore concluded that monodiexodina had an opportunistic character occurring repeatedly only when favorable high energy conditions such as sand shoal appeared in warm temperate climatic belts in both hemispheres monodiexodina originated in the southern transitional zone from an elongated eoparafusulina stock at late early permian around late artinskian time it flourished in southern middle latitudinal areas in latest early and early middle permian time the genus then migrated to the northern hemisphere northern transitional zone by some dispersion mechanism at around the early middle permian and prevailed there during the remaining period of the middle permian

a late permian coral reef complex south kitakami terrane japan abstract the early late permian kubergandian to midian iwaizaki limestone of the south kitakami terrane situated in northeast japan represents a coral reef complex which was formed on a faulted bank in an active continental margin the reef building organisms include cerioid and dendroid rugose corals a fasciculate tabulate coral and solenoporacean algae as constructors calcisponges bryozoans and crinoids as bafflers and tubiphytes archaeolithoporella and cyanobacteria as binders the biotic composition is more diverse than the other coeval reefs characterized by the existence of an obvious framework this reef is similar to the recent coral reefs and unique among late permian reefs most of which are mainly formed by calcisponges and calcareous algae the distribution of late permian reefs is closely related to the palaeoclimate coral reefs were developed mainly around the south china and indochina continental masses between the tethys sea and the panthalassa ocean in the tropics while calcisponge reefs and tubiphytes algal crust reefs were common in tropical to subtropical regions and stromatolite bryozoan reefs developed in arid areas the gradational distribution of late permian organic reefs including localized development of coral reefs were probably caused by decreasing of the glaciers and changing of the ocean current systems

the late permian climate what can be inferred from climate modelling concerning pangea scenarios and hercynian range altitude abstract a major unsolved geodynamic problem is the permian pangea plate configuration at the end of paleozoic era around 255 ma while consensual geology indicates a plate arrangement close to that of the jurassic prior to the atlantic opening pangea a paleomagnetic data indicates a nearly 3000 km more eastward position of gondwana with respect to laurussia leading to major plate and relieves reorganisation during permo triassic times pangea b using an atmospheric general circulation model agcm we simulate the climatic response to both configurations we also test the fundamental role of paleo elevations through sensitivity experiments each simulated climate is then compared with the aim of constraining the best fit to a particular paleogeographic scenario main trends of simulated late permian climate in agreement with paleoclimatic indicators are 1 a warm temperate climate accompanied by a monsoon circulation over the eastern side of gondwana 2 a cold temperate climate marked by strong annual thermal amplitude at high latitudes in gondwana and in siberia 3 an arid belt in the subtropics over the western side of gondwana and laurussia and 4 strong climatic differences over both hemispheres respectively main variance is found over laurussia with a simulated tropical climate while an arid climate is suggested by paleodata simulating different paleo elevations of the appalachian and the variscan fold belts can solve this discrepancy the best model data fit is reached for a mean altitude of 4500 m in the appalachians and appears to be dependent of pangea configuration with a southern europe variscan range of some 3000 m in a pangea a configuration or only 2000 m in for pangea b taking into account the geodynamic context we argue that pangea b appears to be the more probable configuration

a longitudinal carbonate fan from the jurassic of the oman mountains the guweyza limestone formation of the hamrat ad duru abstract when sedimentological stratigraphical and structural data are considered the continental rise sediments of oman neo tethys the hamrat duru group can be restored to their original basin configuration prior to their southwest directed emplacement with the semail ophiolite onto the oman continental margin during the late cretaceous the hamrat duru group sediments are preserved in well exposed imbricate fans the largest of which forms the hamrat ad duru range in the south central oman mountains in the south central hamrat ad duru middle and upper jurassic ooid rich carbonate sediment was transported from the adjacent oman carbonate platform during periods of tectonic instability into the oman neo tethys hawasina basin by high and low density turbidity currents to form sediment sheets with a margin parallel axis of deposition palaeocurrents are northwest directed parallel to the oman margin along the southwest of the hamrat ad duru and northeast directed away from the margin in structurally higher more distal imbricates of the northeastern hamrat ad duru this implies sediment input at the southern end of the hamrat ad duru these trends are reflected in the distribution of sedimentary facies with most proximal facies developed in the southern hamrat ad duru passing into progressively more distal facies to the northwest and northeast sediment thinning and fining is more accentuated away from the margin towards the northeast and sedimentation was concentrated parallel to the oman margin the hamrat ad duru represents a longitudinal fan that was at least 120 km long and extended at least 60 km away from the margin

short term impact of de vegetation on organic inorganic interactions and cation transfers in uppermost soil horizons abstract the soil solutions of a natural soil covered by grass and of the same soil after grass removal were collected and analyzed after each rainfall and percolation through the two soils during a fifteen month experiment to identify and quantify the water mineral plant interactions during this period of time plastic tubes containing calcite and smectite particles were inserted into the two soils some powder of both being recovered after three and fifteen months water leached and the leachates analyzed the contents of various elements including the rare earth elements were measured in the soil solutions and the water leachates to identify the extent of the interactions and evaluate the contribution of the plants the immediate impact of de vegetation was recorded in the soil solutions that exported systematically more si and ca and often more mg from de vegetated soil the supplement of exported si was probably released by altering microorganisms as a response to de vegetation whereas that of mg resulted probably from dissolution of oxy hydroxides and that of ca from partial dissolution of the calcite reference mineral the removed elements were about 50 times higher in the soil solutions than in the plain rainwater before percolation through the soils the contents of the dissolved organic carbon and ammonia of the soil solutions from de vegetated soil were about one third higher than in those of the vegetated soil on the basis of the elemental contents of the soil solutions that percolated through the two soils removal of plants did not significantly affect adsorption of the nutrient k on the inserted smectite and calcite during the initial three months however less k was adsorbed on smectite and calcite of the de vegetated soil than on the same minerals of the same soil covered with grass during the following twelve months indicating in turn that more k was removed from de vegetated soil within a one year time

high resolution stratigraphy with strontium isotopes the isotopic ratio of strontium 87 to strontium 86 shows no detectable variation in present day ocean water but changes slowly over millions of years the strontium contained in carbonate shells of marine organisms records the ratio of strontium 87 to strontium 86 of the oceans at the time that the shells form sedimentary rocks composed of accumulated fossil carbonate shells can be dated and correlated with the use of high precision measurements of the ratio of strontium 87 to strontium 86 with a resolution that is similar to that of other techniques used in age correlation this method may prove valuable for many geological paleontological paleooceanographic and geochemical problems

timing of early and middle permian deglaciation of the southern hemisphere brachiopod based 87sr 86sr calibration abstract earth s transition from an icehouse to hothouse during the late paleozoic was characterized by a series of high paleolatitude glacial interglacial events however the exact timing of these events remains unresolved here we report on fifty five calcitic shells of brachiopods and bivalves screened to obtain reliable 87sr 86sr ratios for cisuralian 298 9 272 95 ma and guadalupian 272 95 259 1 ma seawater specifically we used well preserved shells to build a 87sr 86sr seawater curve for the sydney basin and then with the marine look up table of the permian calculated numerical ages of the stratigraphic succession this allowed us to match seawater changes to the coeval p1 p3 glacial interglacial cycles recorded in the sedimentary successions of the sydney basin evaluation of the 87sr 86sr results revealed that onsets of the p2 and p3 glaciations in the sydney basin should be assigned to the early artinskian and late wordian respectively the range of 87sr 86sr values recorded by brachiopods from the wandrawandian siltstone coupled with recent geochronological dating of the broughton formation suggest that glacial phase p3 lasted about 2 myr and was confined to the late wordian early capitanian dating obtained using the sr isotope proxy from brachiopods agrees with the geochronologic ages and they suggest that the glacial phases p1 to p3 became progressively shorter in duration and less intense conversely the corresponding interglacials became progressively longer and thus documenting the gradual transition of the permian icehouse to an ice free greenhouse world our study confirms that strontium isotopes measured in screened brachiopod shell archives are sufficiently robust to date paleozoic marine sedimentary successions and are most valuable in sedimentary successions that otherwise lack geo chronological dating

high precision radiogenic strontium isotope measurements of the modern and glacial ocean limits on glacial interglacial variations in continental weathering existing strontium radiogenic isotope 87sr 86sr measurements for foraminifera over quaternary glacial interglacial climate cycles provide no evidence for variations in the isotope composition of seawater at the 9 13 ppm level of precision however modelling suggests that even within this level of uncertainty significant up to 30 variations in chemical weathering of the continents are permitted accounting for the longer term rise in 87sr 86sr over the quaternary and the apparent imbalance of sr in the oceans at the present day this study presents very high precision 87sr 86sr isotope data for modern seawater from each of the major oceans and a glacial interglacial seawater record preserved by planktic foraminifera from ocean drilling program odp site 758 in the north east indian ocean strontium isotope 87sr 86sr measurements for modern seawater from the atlantic pacific and indian oceans are indistinguishable from one another 87sr 86sr 0 7091792 0 0000021 n 17 at the level of precision obtained in this study 4 9 ppm 2 this observation is consistent with the very long residence time of sr in seawater and underpins the utility of this element for high precision isotope stratigraphy the 87sr 86sr seawater record preserved by planktic foraminifera shows no resolvable glacial interglacial variation 87sr 86sr 0 7091784 0 0000035 n 10 and limits the response of seawater to variations in the chemical weathering flux and or composition to 4 9 ppm or less calculations suggest that a variation of 12 around the steady state weathering flux can be accommodated by the uncertainties obtained here the new data cannot accommodate a short term weathering pulse during de glaciation although a more a diffuse weathering pulse accompanying protracted ice retreat is permissible however these results still indicate that modern weathering fluxes are potentially higher than average over the quaternary and such variations through glacial cycles can also account for the longer term rise in 87sr 86sr over this time interval the very high precision measurements made for the marine 87sr 86sr record in this study place clear limits on the magnitude and timing of changes in the chemical weathering flux during glacial interglacial cycles further constraints must be sought from even higher precision measurement or elements with shorter residence times in the ocean such as osmium os that have the capacity to respond to short term variations in input

strontium and oxygen isotopic composition of east greenland rivers and surface waters implication for palaeoenvironmental interpretation abstract isotopic composition of strontium and oxygen and strontium concentrations from 4 hydrographic sites in scoresby sund fjord and 6 rivers draining the adjacent jameson land have been investigated schuchert flod the major river on jameson land erodes a large celestite srso4 deposit dissolved sr in schuchert flod has 87sr 86sr 0 7137 and is responsible for most of the continental sr flux to the fjord the sr isotope data have been used to construct a mixing model for the surface water in scoresby sund fjord salinity s and sr concentrations csr of brackish water from the fjord show conservative mixing between river water and seawater results of the 87sr 86sr salinity mixing model of seawater and fresh water were used to interpret the isotopic composition of sr 87sr 86sr and oxygen 18oc of recent and interglacial eemian 120 ka shallow water bivalve shells from the coast of jameson land because of the high csr in some of the rivers draining jameson land a correlation exists between 87sr 86sr and 18oc of recent and interglacial shallow water bivalve shells from the coast of jameson land higher than seawater 87sr 86sr values in shells from the langelandselv interglaciation can be explained only if the shells were formed close to a sr rich fresh water source which is not present in the langelandselv area today these results suggest that there was a different river and drainage system on the jameson land peninsula during the last interglacial the 87sr 86sr values indicate that shell formation took place in waters with salinities between 20 and 31 in a fjord with less glacial melt water than seen today

seawater paleotemperature and paleosalinity evolution in neritic environments of the mediterranean margin insights from isotope analysis of bivalve shells the first step of ice sheet build up on antarctica at the eocene oligocene boundary was followed by a phase of climate instability culminating during the miocene with a warming event called the middle miocene climate optimum mmco that ended with a marked cooling phase identified as the middle miocene climate transition mmct while numerous benthic foraminifera 18o and mg ca data have been used to capture the global climate evolution during this interval of climate and ice sheet instability geochemical records from shallow water carbonates still remain scarce yet such records are crucial to capture the diversity of regional environmental responses to global climate changes and thus to better understand the behavior of our climate system during this critical interval in this work we test the potential of a multi proxy approach 18o clumped isotope 47 strontium isotopes 87sr 86sr applied to bivalves recovered from the liguro provencal basin and rhodano provencal basin northwestern of the mediterranean sea to reconstruct the evolution of shallow seawater temperature and salinity in this region over the latest oligocene to middle miocene interval 10 myrs our results highlight a local cooling in the northwestern mediterranean sea during the mmco that contrasts with the warming observed in other regions with seawater temperatures inferred from 47 analyses in the 13 18 c range these cool seawater temperatures recorded in the studied region during the mmco are much cooler than those recorded in the open oceans but are in agreement with the proliferation of bryozoan observed in the castillon du gard area during this interval low bivalve 18o values 3 24 in average are recorded during this episode are interpreted to reflect enhanced freshwater inputs lowering local salinity and seawater 18o such enhanced freshwater inputs point to a phase of enhanced hydrological cycle in the studied region possibly linked to the global mid miocene warming event bivalve 87sr 86sr data mostly fall within the global seawater sr isotope reference curve but remain compatible with enhanced freshwater inputs during the aquitanian and during the langhian as these inputs were probably not important enough to induce a large departure from the seawater curve at a regional scale

corals from a dismembered late paleozoic paleo pacific plateau a coral belonging to the rare late mississippian early pennsylvanian family pseudopavonidae and a specimen of the permian waagenophyllid coral genus parawentzelella have been recovered from the cache creek assemblage in northern british columbia and from a small limestone block in southern british columbia canada respectively both of these fossils are closely related to corals known from eastern japan and western sze chuan china parawentzelella also occurs in indochina these corals apparently occur in shallow water carbonates that overlie pieces of oceanic volcanic ridges or plateaus in both asia and north america these corals now lie geographically close to coeval but completely different coral faunas that lived on shallow carbonate platforms built on continental shelves this suggests that the circum pacific terranes bearing these unusual corals were displaced from a single shallow water oceanic region that in late paleozoic time lay in the paleo pacific ocean far from any continental margin in late permian or early mesozoic time the region colonized by these fossils was torn apart the rock masses bearing these fossils were then carried on oceanic plates to subduction zones at continental margins on opposite sides of the pacific ocean where they became lodged

obduction processes in ancient modern and future ophiolites geologic and tectonic processes of ophiolite obduction deduced from structural mapping timing of deformation and metamorphism and palinspastic reconstruction of ancient ophiolite complexes compare closely with modern processes operative in the western pacific many ongoing arguments about the origin of ophiolite complexes oceanic island arc or marginal basin and their emplacement subduction related or not are largely semantic and depend on exactly what individuals regard as island arcs marginal basins or subduction zones a review of tectonic processes currently active in the western pacific region shows a wide range in size shape and duration of arcbasin complexes and some of these show uniformitarian models similar to those proposed for emplacement of ancient ophiolites the tethyan ophiolites of the semail oman mountains and spontang western himalaya of ladakh zanskar and the ordovician western newfoundland ophiolites are compared with recent examples of the mariana basin yap trench banda arc luzon arc and papua new guinea it is concluded that they are all connected in some way with marginal basins and island arcs in varying stages of development and maturity emplacement of these ophiolites is related to continental underthrusting of a trapped marginal basin and accretionary prism comparable to present day examples of the n australian margin underthrusting timor and the banda sea and the se china margin underthrusting the luzon arc

the effect of land plants on weathering rates of silicate minerals abstract land plants and their associated microbiota directly affect silicate mineral weathering in several ways by generation of chelating ligands by modifying ph through production of co2 or organic acids and by altering the physical properties of a soil particularly the exposed surface areas of minerals and the residence time of water in laboratory experiments far from equilibrium 1 mm oxalate a strong chelator of al has a negligible effect on the dissolution rate of alkali feldspars but some effect on calcic feldspars and olivine by analogy to oxalate the overall effect of organic ligands on the weathering rate of silicate minerals in nature is likely to be small except perhaps in microenvironments adjacent to roots and fungal hyphae the effect of ph on silicate mineral dissolution rate depends on ph below ph 4 5 the rate increases with decreasing ph in the circumneutral region the rate is ph independent and at ph values above around 8 the rate increases with increasing ph vegetation should thus cause an increase in weathering rate through the ph effect only where the ph is below 4 5 as an overall generalization the effect of plants on weathering rate through changes in soil solution chemistry is probably small for granitic rocks it may be greater for more mafic rocks it is the release of ca and mg from mafic rocks that has the greatest influence on the global co2 budget the effect of changes in soil physical properties on weathering rate can be major by binding fine particles plants can greatly increase weathering rates in areas of high physical erosion where erosion rates are lower the effect of plants is less clear on long timescales plants may decrease chemical weathering by binding secondary products and isolating unweathered minerals from meteoric water a major unknown in estimating the effect of the advent of land plants on weathering rates is the nature thickness particle size distribution permeability of the regolith on the pre silurian continents the indirect effect of vegetation through changing the regional distribution of precipitation may be as important as the direct effects

tectonic forcing of early to middle jurassic seawater sr ca the jurassic period ca 201 145 ma is marked by fundamental reorganizations of paleogeography paleoceanography ecosystems and the progressive shift from aragonite to calcite as the favored marine biogenic carbonate polymorph sr ca ratios of well preserved jurassic oysters and belemnites from sections in the uk and poland demonstrate that the sr ca ratio of seawater varied systematically throughout the early and middle jurassic in parallel with already documented seawater 87 sr 86 sr the sr flux from increased mid ocean ridge activity in the early jurassic outbalanced the input of riverine sr leading to gradually lower seawater 87 sr 86 sr associated with the parallel and strong decrease in seawater sr ca ratios this downward trend was reversed by enhanced continental input in the toarcian and aalenian but resumed in the bajocian and continued to the callovian parallel changes of seawater 87 sr 86 sr and sr ca suggest a common cause for these long term variations and are best explained by changes in the balance of continental weathering and hydrothermal fluxes these findings underline the strong control of global tectonic processes on the evolution of biomineralization and downplay the role of biomineral evolution in influencing strontium chemistry of seawater in the mid mesozoic

controls over the strontium isotope composition of river water abstract strontium concentrations and isotope ratios have been measured in river and ground waters from the ganges orinoco and amazon river basins when compared with major element concentrations the data set has allowed a detailed examination of the controls over the strontium isotope systematics of riverine input to the oceans in the following environments 1 1 typical drainage basins containing limestones evaporites shales and alumino silicate metamorphic and igneous rocks 2 2 shield terrains containing no chemical or biogenic sediments and 3 3 the floodplains that constitute the largest areas of many large rivers the strontium concentration and isotope composition of river waters are largely defined by mixing of strontium derived from limestones and evaporites with strontium derived from silicate rocks the strontium isotope composition of the limestone endmember generally lies within the phanerozoic seawater range which buffers the 87 sr 86 sr ratios of major rivers a major exception is provided by the rivers draining the himalayas where widescale regional metamorphism appears to have led to an enrichment in limestones of radiogenic strontium derived from coexisting silicate rocks the strontium isotope systematics of rivers draining shield areas are controlled by the intense transportlimited nature of the weathering reactions and thereby limits variations in the strontium flux from these terrains floodplains are only a minor source of dissolved strontium to river waters and precipitation of soil salts in some floodplains can reduce the riverine flux of dissolved strontium to the oceans the most effective mechanisms for altering the isotope ratio and flux of riverine strontium to the oceans are increased glaciation and large scale regional metamorphism of the type produced during continental collision both mechanisms provide a means for increasing the 87 sr 86 sr ratio of the global riverine flux

discrepancy between sr isotope and biostratigraphic datings of the upper middle and upper miocene successions eastern north sea basin denmark abstract one hundred and fifty six 87sr 86sr analyses have been performed on 129 samples from 18 outcrops and boreholes in oligocene miocene deposits from jylland denmark these analyses were mainly conducted on mollusc shells but foraminiferal tests bolboforma and one shark tooth were also analysed the main purpose of the study is to compare the ages of the danish succession suggested by the biostratigraphic zonation on dinoflagellate cysts dybkjaer and piasecki 2010 with the ages based on analyses of the 87sr 86sr composition of marine calcareous fossils in the same succession analyses of samples from the danish brejning vejle fjord klintinghoved arnum odderup hodde ornhoj and gram formations gave ages between 25 7 my late oligocene and 10 3 my late miocene the sr isotope ages from the lower part of the succession i e brejning to odderup formations agree with the age estimates based on biostratigraphy however the 87sr 86sr ratios of fossil carbonates from the middle upper miocene hodde to gram succession consistently indicate ages older than those recorded by biostratigraphy post depositional processes as an explanation for this offset are inconsistent with good preservation of shell material and little reworking a palaeoenvironmental cause for the observed mismatch is therefore indicated search for geological events that could explain the older ages obtained by sr isotope compositions have not led to any conclusions and we had recognised the same problem in earlier reports and communications we conclude that this is a general and possibly global middle late miocene problem that has to be reconsidered and explained geologically

middle permian capitanian seawater 87 sr 86 sr minimum coincided with disappearance of tropical biota and reef collapse in ne japan and primorye far east russia abstract to investigate the secular changes in permian seawater chemistry and to constrain the global environmental changes during the end guadalupian middle permian extinction we analyzed 87sr 86sr ratios in capitanian upper guadalupian shallow marine limestones in ne japan and in southern primorye far east russia these limestones were deposited on the continental shelf platform of the northern part of greater south china which faced the northern connecting seaway between the tethys and panthalassa the measured limestone samples were collected from the capitanian fusuline lepidolina bearing intervals and overlying beds at iwaizaki in the south kitakami belt ne japan and at senkina shapka in the sergeevka belt southern primorye the present analysis of bulk 87sr 86sr ratios clarified extremely low 87sr 86sr ratios of 0 7068 0 7070 from all measured samples these sr isotopic values support a capitanian age for these strata the topmost 30 m thick interval of the iwaizaki limestone in particular witnessed a stepwise biodiversity decline in the shallow marine warm water biota and the collapse of the carbonate factory after the reef development during the capitanian in the northern part of greater south china the disappearance of the tropical biota and the collapse of the reef during the late capitanian suggest that the biotic responses to a significant environmental change appeared relatively earlier at mid latitudes than in the tropical regions

paleoceanography of the late cretaceous maastrichtian western interior seaway of north america evidence from sr and o isotopes abstract well preserved fossils of the late cretaceous western interior seaway wis of north america have been analyzed for sr concentration and sr and o isotopes in order to decipher paleosalinities and paleotemperatures the samples are from four biofacies within the seaway late maastrichtian offshore interior pierre shale nearshore interior fox hills formation brackish reduced salinity fox hills formation and freshwater hell creek formation samples were also obtained from the severn formation of maryland considered to be representative of the open ocean all biofacies except the freshwater are demonstrably within the jeletzkytes nebrascensis ammonite zone 87 sr 86 sr ratios show significant and systematic decreases from marine mean 1 s d 0 707839 0 000024 to brackish facies mean 1 s d 0 707677 0 000036 consistent with dilution by freshwater with a lower 87 sr 86 sr ratio than seawater such variation disallows using the 87 sr 86 sr ratios of fossil shell material to assign ages to fossils from the late cretaceous wis without knowledge of the salinity in which the organism grew the sr isotope ratios for scaphitid ammonites within a single biofacies are similar to each other and different from those for scaphites in other biofacies implying that these organisms are restricted in their distribution during life the 87 sr 86 sr values of freshwater unionid mussels range widely and are not compatible with the freshwater endmember 87 sr 86 sr ratio required by the trend in 87 sr 86 sr vs biofacies established from the other samples paleosalinities for the biofacies are estimated to range from 35 in the open marine to a minimum of 20 in the brackish based on the presence of cephalopods in all four facies and the known salinity tolerance of modern cephalopods producing reasonable 87 sr 86 sr values for the freshwater endmember of a 87 sr 86 sr vs 1 sr plot requires a sr concentration 0 2 0 5 that of seawater for the dominant freshwater input to the wis such high sr concentrations relative to seawater are not observed in modern rivers and we suggest that the brackish environment in the wis arose through the mixing of freshwater and seawater in a nearshore aquifer system reactions of the solution with aquifer solids in this subterranean estuary moore mar chem 65 1999 111 125 produced brackish water with the sr concentration and isotopic composition recorded in the brackish biofacies 18 o values of the fossils show decreases from the marine to brackish biofacies consistent with increasing temperatures from 13 to 23 c or if temperatures were relatively constant to a decrease in the 18 o of the water in which the shell formed the latter interpretation is consistent with less than fully marine salinities in the nearshore biofacies but both changes in temperature and the isotopic composition of the water may have occurred in this environment

structural geology of the lardeau group near trout lake british columbia implications for the structural evolution of the kootenay arc the lardeau group is a heterogeneous assemblage of lower paleozoic eugeoclinal strata present in the kootenay arc in southeastern british columbia it is in fault contact with lower paleozoic mioge

hydromagmatic eruption during the buildup of a triassic carbonate platform oman exotics eruptive style and associated deformations abstract oman exotics represent remnants of a triassic carbonate platform also named misfah formation several basaltic intrusions or lava flows were coeval with the carbonate platform buildup we present field observations related to one of these volcanic events including associated deformation of the host rocks and interaction of volcanism with the sedimentation these observations allow us to reconstruct the structure of the volcanic conduit and vent and the successive stages of the evolution of the eruption the initial ascent of magma probably occurred along on a normal fault related to gravity driven sliding towards the platform edge magma was first emplaced in a saucer shaped sill a few tens of meters below the sea floor this intrusion provided a decollement layer that may have sped up the gravity driven sliding opening fractures that brought sea water into contact with the magma hence triggering a hydromagmatic eruption eruption was followed by the collapse of the host limestones that formed a megabreccia infilling the eruptive vent and prohibiting further contact between sea water and magma most of the magma was emplaced at depth in two superposed small magmatic bodies 300 100 m and 200 50 m in sections respectively that replaced the host sediments and uplifted the overlying vent despite the shallow submarine setting this eruption produced a vent quite similar to sub aerial maars developed in soft substrate this emphasizes that the rheology of the substrate may be more important than the amount of water to control magma water interaction in hydromagmatic eruptions in an active carbonate platform like misfah formation during triassic times the early diagenesis of lime mud determined the mechanical comportment of the sediment at the time of eruption and especially the way it could be mixed with the magma and or slide into the vent

storm generated sedimentary structures in subtidal marine facies with examples from the middle and upper ordovician of southwestern virginia abstract the role of storms is of major importance in forming stratification in open shelf facies though storm processes on modern shelves are not fully understood enough is known to see how sediments are influenced storms transport sand away from coastal areas and suspend and transport sand and mud on the open shelf when wave base is lowered storms generate winnowed lag deposits of shells or gravel but coarser sediment and shells of megafauna are little transported except in very near shore environments the martinsburg formation middle and upper ordovician of southwestern virginia was deposited on a storm influenced open marine platform in contrast to the classic turbidite flysch basin of the martinsburg in the great valley of virginia to the northeast deposition of most martinsburg sediments was due to storms sediments deposited during single storm events occur in characteristic fining upward sequences 1 to 80 cm thick in both carbonate and terrigenous clastic dominated areas of the platform individual storm deposits consist of a sharp erosional base overlain by a couplet of whole fossil packstone and laminated calcarenite siltite or quartzose siltstone to very fine sandstone which is gradational to shale packstones are typically intraclastic have shells aligned parallel o bedding and convex up often with adhering or contained mud and have abundant infiltration textures such as cement filled shelter voids packstones grade abruptly to a laminated bed with horizontal plane lamination large and small scale in phase undulatory lamination and wave ripple cross lamination commonly occurring in ordered vertical sequences laminated beds contain escape burrows are weekly graded and have irregularly mounded upper bed surfaces laminated beds grade upward to shale containing horizontal branching burrows and marine fossils the faunal content of the fining upward sequences matches that of the interbedded shale storm generated beds vary greatly in thickness laterally and frequently pinch out completely fining upward sequences formed by scouring winnowing and suspension of the sand and mud during the height of the storm to form the erosional base and autochthonous lag of whole fossils storms preferentially preserve whole fossils rather than fragmenting them infiltration of finer sediment into the lag deposit and deposition of the laminated bed occurred as the storm waned laminated beds are molded into a distinctive suite of sedimentary structures by wave generated currents the shale represents deposition of finest storm suspended material and continued hemipelagic sedimentation similar sequences are widely distributed in the geologic record variability of storm generated sequences can be related to changing water depth thus storm deposits may be useful in basin analysis to estimate relative water depths and trace transgressive and regressive events

occurrence and mobilization of radium in fresh to saline coastal groundwater inferred from geochemical and isotopic tracers sr s o h ra rn abstract salinization in groundwater systems can induce water rock interaction including the release of naturally occurring trace elements of health significance such as radium ra with possible implications for the usability of water resources in addition to the increase of dissolved solids tds concentrations in general radium mobility is limited by chemical removal mechanisms including adsorption onto clays and or mn and fe oxides exchange processes and coprecipitation with secondary barite in order to examine the effect of aquifer salinity gradients on the distribution of naturally occurring ra in fresh to saline groundwater and the relationship to water rock interaction and ra removal mechanisms two contrasting systems were investigated the shallow unconfined coastal aquifer in agadir southwestern morocco and the confined cretaceous cape fear and pliocene yorktown aquifers of the atlantic coastal plain north carolina usa geochemical and isotopic indicators of salinity sources e g cation ratios 18o 2h br cl 34 s so 4 2 18 o so 4 2 were used to identify the relative contributions of seawater and other saline waters and subsequent geochemical modification by water rock interaction radium activities 224ra 226ra 228ra radon 222 alkaline earth metal mg ca sr ba concentrations and ratios and 87sr 86sr ratios were analyzed to identify water rock interaction processes affecting alkaline earth metals including ra the morocco coastal aquifer is generally oxic exhibits a range of salinity and water types cl 163 2120 mg l median 932 mg l and exhibits ca na ratios above the seawater value typical of monovalent divalent cation exchange base exchange reactions in coastal aquifers in contrast the atlantic coastal plain aquifers are anoxic sulfate reducing cover a wider salinity range cl 5 9890 mg l median 800 mg l representing a transition between na hco 3 and na cl waters and exhibit ca na ratios below that of modern seawater typical of reverse base exchange reactions possible salinity sources in the morocco coastal aquifer include seawater intrusion mesozoic evaporites other natural saline waters and or wastewater whereas the atlantic coastal plain is primarily affected by old seawater present in the aquifer system radium activities are generally low and vary significantly within each aquifer for example 226ra ranges from 1 8 27 7 mbq l in the morocco coastal aquifer median 8 1 mbq l and 1 9 214 mbq l in the atlantic coastal plain median 18 9 mbq l the highest ra activities were observed in the most saline wells sampled in the atlantic coastal plain at total dissolved solids tds concentrations above an apparent threshold of 5000 mg l radium activities increase in a generally linear fashion with salinity in the atlantic coastal plain broadly comparable to previous studies indicating a threshold range of 3000 10 000 mg l at lower tds concentrations water rock interaction processes that vary with local aquifer conditions appear to control ra distribution rather than merely salinity in the morocco coastal aquifer adsorption of ra and coprecipitation with secondary barite are apparently favorable to control ra levels in groundwater radium removal in the anoxic atlantic coastal plain aquifers appears to be associated with adsorption and or exchange processes with the additional possibility of barite precipitation in the cape fear aquifer indicated by barite saturation overall the locally variable factors that can control ra sources and mobility in fresh to brackish groundwater at near neutral ph include variation in solid phase radioactivity redox state affecting adsorption sites availability of competing divalent cations and barite saturation

significance of tethyan fossils in the american cordillera equatorial faunas of the ancient tethyan seaway which extended from western europe to southeastern asia comprise some of the most diverse marine taxa in the fossil record comparable or identical tethyan species that occur far from the tethyan seaway in paleozoic and mesozoic rocks of the north and south american cordillera have long been considered as a major biogeographic anomaly two leading theories to account for the occurrence of these anomalous tethyan faunas in the cordillera are that they were transported long distances to the east on tectonic blocks suspect terranes that originated near the tethys or that they migrated westward via undiscovered marine corridors through continental areas of pangea an alternative model is that these tethyan fauna were pantropic species that extended with attenuated diversities into the eastern proto pacific ocean this pantropic model can better account for the distribution patterns of many paleozoic and early mesozoic tethyan species in the american cordillera and provides a steady state hypothesis against which the other models can be tested the distribution of pre cretaceous tethyan faunas is similar to the known pantropic distribution of many cretaceous and cenozoic tropical biotas during the cenozoic taxa were most diverse in the tethys and indo west pacific regions but extended with attenuated diversity to many parts of the equatorial pacific ocean including the west coasts of north and south america the eastern pacific occurrence of many indo west pacific species provides a modern analog for the occurrence of many anomalous tethyan fossils in the american cordillera

experimental evidence for mobility of zr and other trace elements in soils a soxhlet extraction was carried out over a period of 27 d on a column comprising 3 cm of quartz overlain by 4 cm of soil from the b horizon and then 1 cm of soil from the a horizon of a granitic podzol major and trace elements were leached from the column and accumulated in a reservoir at the base of the column total loss of elements from the soil over the course of the experiment ranged from 0 002 to 1 wt with major elements and the light and heavy rare earth elements ree showing the largest percentage losses zirconium 0 002 and then al 0 008 showed the lowest percentage loss the light ree were leached out of the soil preferentially to the mid ree all elements showed accumulation by a factor of 2 to 11 in the quartz layers at the base of the column particularly in the upper first 1 cm of the quartz major elements were leached from the column at a rate of 0 02 to 0 59 mol h 1 whereas zr nd sm gd dy rb and sr were leached at the rate of 0 5 to 30 10 6 mol h 1 concentrations of other ree in the reservoir increased over the duration of the experiment but they were poorly correlated with time so leaching rates were not calculated normalization of the major element leaching rates to take into account the constant flushing of water through the column the average annual rainfall in the allt a mharcaidh catchment in scotland from where the soil was sampled and the cross sectional area of the soil in the column together with the temperature of the soil in the column 70 c compared with the average annual temperature of the allt a mharcaidh catchment 5 7 c gave major element release rates from the soil of 0 002 to 0 97 meq m 2 yr 1 depending on the choice of ea the dissolution activation energy which are generally less than those measured in the field of 0 1 to 40 9 meq m 2 yr 1 calculations showed that despite the redistribution and loss of zr from the column assumptions of zr mobility would have had a negligible effect on calculated element release rates of na ca fe and mg however significant underestimates of the release of k 5 ti 57 al 5 and si 10 as well as some trace elements e g nd 23 rb 54 sr 24 would have occurred concentrations of ca and sr leached from the column correlated well rsq 0 93 p 0 01 supporting the idea of the use of sr release as a proxy for ca release in weathering rate calculations the release rates and percentage loss of ree from the soil varied between elements indicating that ree distribution patterns of rocks and soils may not be preserved in drainage waters

diagenetic processes associated with unconformities in carbonate successions on isolated oceanic islands case study of the pliocene to pleistocene sequence little cayman british west indies abstract the youngest part of the neogene carbonate succession on little cayman is a thin

south kitakami region an allochthonous terrane in japan the pre cretaceous geology of the japanese islands may be interpreted as an accretion complex in which many terranes of several origins are juxtaposed and a number of allochthonous blocks are involved the south kitakami and abukuma regions of northeast japan and probably also silurian and devonian blocks in the kurosegawa fault zone and the border fault zone of the hida metamorphic terrane are the allochthonous blocks the stratigraphic sequence and paleobiofacies of the regions are similar to each other and their lithologic characters are of continental affinity but however are quite different from those of the other terranes having oceanic characters the south kitakami and abukuma regions have been fragments of a lost continent less remotely situated to gondwana during the middle paleozoic and may have drifted and incorporated with the other part of the japanese islands before late mesozoic to early tertiary igneous activity

stromatolitic biotic systems in the mid triassic of israel a product of stress on an epicontinental margin abstract phanerozoic microbialites are carbonate precipitating biotic forms that are often described in modern systems from inter or supratidal hypersaline or fresh water environments and from beds associated with a variety of ecologically stressed environments over geologic time middle to late triassic microbialitic successions from southern israel were commonly subtidal and thrived under cryptic ecological stress conditions related to the regional configuration of the levant margin at that time the ladinian and carnian sequence at the ramon outcrop contains 18 successions with 28 microbialitic horizons these microbialites form isolated patches small bioherms and biostromes interleaved with other calcareous sediments including poorly diverse molluscan accumulations three distinct microbialitic facies and two associated molluscan facies were identified most were distinctly subtidal the two associated molluscan biofacies include a subtidal bivalve boundstone forming mounds and a bedded packstone of minute gastropods the ladinian carnian microbialites were not climatically forced environmental stress was caused by partial restriction of marine circulation due to tectonic movements and biotic accumulation on the outer edge of the levant margin comparison of coeval successions from central and northern israel and the north calcareous alps and southern alps in europe indicates a tethyan or global carbonate system of microbial producers separated from the open marine environment by shelf edge barriers therefore we conclude that the ramon microbialites represent a response to ecological stress of the carbonate system within the subtidal environment rather than solely to normal stresses of the intertidal environment

nina creek group and lay range assemblage north central british columbia remnants of late paleozoic oceanic and arc terranes in north central british columbia a belt of upper paleozoic volcanic and sedimentary rocks lies between mesozoic arc rocks of quesnellia and ancestral north america these rocks belong to two distinct terranes the nina creek group of the slide mountain terrane and the lay range assemblage of the quesnel terrane the nina creek group is composed of mississippian to late permian argillite chert and mid ocean ridge tholeiitic basalt formed in an ocean floor setting the sedimentary and volcanic rocks the mount howell and pillow ridge successions respectively form discrete generally coeval sequences interpreted as facies equivalents that have been interleaved by thrusting the entire assemblage has been faulted against the cassiar terrane of the north american miogeocline west of the nina creek group is the lay range assemblage correlated with the harper ranch subterrane of quesnellia it includes a lower division of mississippian to early pennsylvanian sedimentary and volcanic rocks some with con

strontium isotope variations in middle jurassic late bajocian callovian seawater implications for earth s tectonic activity and marine environments abstract strontium isotope ratios of well preserved belemnite rostra and ammonite shells are presented from stratigraphically well dated upper bajocian callovian sediments of the polish jura chain in central poland nekto benthic belemnites show a narrow trend of changes of 87 sr 86 sr ratio that are interpreted to record secular variations in the strontium isotope composition of seawater a new fit of the seawater strontium isotope curve for the late bajocian callovian is presented based on current and literature data the data show a gradual decrease of seawater 87 sr 86 sr ratio throughout the late bajocian earliest middle callovian lowest 87 sr 86 sr ratios 0 706850 and the flat minimum of the curve were reached in the latest middle and the late callovian the middle jurassic decrease in seawater 87 sr 86 sr ratio is interpreted to have been a result of the increased volcanic activity of the seafloor studied nektonic ammonites are considered to have lived in surface or shallow near coastal waters of the polish jura chain basin and been affected by the freshwater influx a slight enrichment of ammonite shells in 87 sr isotope is linked to a change in strontium isotope composition of the surface or near coastal waters due to the riverine strontium input

island dolostones genesis by time transgressive or event dolomitization abstract thick cenozoic dolostone successions found on many isolated carbonate islands have commonly been attributed to dolomitization events whereby time restricted dolomitization processes repeatedly affected the original limestone successions any model invoked to explain dolomitization of these successions depends on accurate dating of the events because that may allow correlation with other processes such as sea level oscillations or climate change the 87sr 86sr ratios available from island dolostones throughout the world which have been used to date dolomitization under the premise that seawater mediated its formation indicate that most of these island dolostones developed between the late miocene and late pleistocene 10 to

the jabal akhdar dome in the oman mountains evolution of a dynamic fracture system the mesozoic succession of the jabal akhdar dome in the oman mountains hosts complex networks of fractures and veins in carbonates which are a clear example of dynamic fracture opening and sealing in a highly overpressured system the area underwent several tectonic events during the late cretaceous and cenozoic including the obduction of the samail ophiolite and hawasina nappes followed by uplift and compression due to the arabia eurasia convergence this study presents the results of an extensive tectonic survey and correlates subseismic scale structures in jabal akhdar faults fractures veins and stylolites with the main tectonic events in the northeastern arabian plate as some of the studied formations host large oil reserves in neighboring areas determining the relative timing of these events in the exhumed rocks is important to understand hydrocarbon distribution and fracture patterns in these reservoirs the formation of early veins and stylolites in the oman mountains is followed by top to the south layer parallel shearing that may be associated with the obduction of the samail and hawasina nappes this compressional tectonic event is followed by normal dip slip to oblique slip faults and veins top to the northeast layer parallel shearing which corresponds to the first stage of exhumation of the autochthonous rocks offsets these structures our new data indicate that this first phase of events is overprinted by complex strike slip networks of veins and fractures as well as by the reactivation and onset of seismic scale faults strike slip structures belong to three distinct events the first one nw se oriented compression is probably associated with the oblique collision of the indian plate against the arabian platform during the late campanian to the mid eocene the second event e w oriented compression is likely to have been formed during the late oligocene middle miocene during uplift the last event ne sw oriented compression probably took place during the miocene pliocene structures of the first two strike slip events have the same orientation as seismic scale faults observed in the subsurface of oman and abu dhabi in addition increasing vein intensity towards the top of the autochthonous formations in the oman mountains as well as the small angle between conjugate vein sets indicate that high fluid pressures that are thought to be present during strike slip deformation

allochthonous permian micro and macrofauna kamloops area british columbia the first waagenophyllid coral to be described from the western hemisphere has been found in permian rocks of the harper ranch group near kamloops southern british columbia it is parawentzelella miyagiella johnstonae sp nov associated with the tabulate coral multithecopora larushi sp nov numerous brachiopods and other fossils the containing rocks are considered to be allochthonous originating in the western part of the paleopacific tethyan ocean or in an island arc complex farther to the north the outcrop yielding the fossils appears to be a stratigraphic misfit both in age and origin fusulinids from adjacent areas are of early permian wolfcampian age but those associated with the fossils indicate a late permian guadalupian age these conflicting dates cannot at present be reconciled the tethyan origin of the fauna also contrasts with that of surrounding rocks which are non tethyan

processes of late cretaceous to late miocene episodic thrust sheet translation in the lycian taurides sw turkey the lycian taurides of sw turkey consist of an allochthonous mesozoic passive margin succession that was episodically detached from its autochthon and translated southeastwards between latest cretaceous to late miocene times a combination of structural analysis sedimentology palaeontology and geochemistry allows subdivision of this orogenic event into 1 latest cretaceous trench passive margin collision causing ophiolite obduction and detachment of the koycegyiz thrust sheet 2 mid late eocene continent continent collision renewing southeastwards thrusting and causing detachment of the teke dere thrust sheet and yavus thrust sheets 3 miocene extensional collapse of the orogen with southeastwards translation of the allochthon coeval with rift basin formation in the hinterland

structural evolution metamorphism and restoration of the arabian continental margin saih hatat region oman mountains abstract 170 m y of relatively stable passive margin sedimentation along the northern continental margin of arabia was abruptly terminated during the cenomanian turonian 95 ma when the oman continental margin collapsed and subsided rapidly aruma basin to accommodate obduction of the semail ophiolite complex and underlying thrust sheets haybi and hawasina complexes in the oman mountains the ophiolite was emplaced at least 200 km over the passive margin probably over 450 km in total from ne to sw during the later stages of obduction the leading edge of the continental margin was subducted to depths where carpholite bearing rocks 6 8 kbar blueschist 12 15 kbar and eclogite ca 20 kbar facies metamorphism formed in a ductile deforming ne dipping subduction zone along the northeastern margin of the saih hatat culmination in ne oman the mesozoic shelf carbonates are deformed by recumbent folding on all scales the present day structure is dominated by four sw vergent thrust slices in carpholite grade rocks at higher structural levels overlying lower units of crossite bearing blueschist hulw unit garnet glaucophane chloritoid blueschists and garnet clinopyroxene phengite glaucophane eclogites 15 20 kbar the largest shear zone separates 7 8 kbar hulw unit blueschists above from 12 15 kbar retrogressed eclogites and ca 20 kbar eclogites of the as sifah unit below further inboard sw a major shear zone separates the lower plate hulw blueschist facies rocks from the upper plate sedimentary rocks upper plate lower plate discontinuity which also show carpholite grade hp metamorphism towards the ne restoration of the entire saih hatat continental margin shows that the upper plate lower plate discontinuity cuts down section to the sw as far as the proterozoic hatat schists ne directed extensional crenulation schistosity and nne oriented stretching lineations in the eclogite and blueschist facies rocks are consistent with sw directed exhumation of footwall hp rocks ne facing folds and spectacular sheath folds with greatly attenuated limbs in the upper plate sediments are interpreted as antithetic backfolds with shortening in the upper plate balanced by the subduction of the lower plate consistent with a ne directed subduction of the continental margin rocks beneath the sw obducting ophiolite haybi and hawasina thrust sheets recent suggestions of a nascent sw directed subduction beneath the oman margin are not consistent with the sedimentary evolution of the shelf and slope carbonates or the geological structure of saih hatat two main phases of tectonic uplift of saih hatat and jebel akhdar are firstly the latest cretaceous ramp culmination associated with foreland propagating thrusts in the sw and backfolds in the ne and secondly post late eocene oligocene uplift by ca 2000 m

plant decay as a major control of river dissolved potassium a first estimate abstract living plants which acquire significant amounts of k primarily from weathered silicate materials may be considered as an intermediate storage for part of k that is ultimately of the origin of silicate mineral weathering part of this plant k is transferred to streams and rivers as dead vegetation on the ground surface and within the soil beneath the surface becomes decomposed and leached by surface and ground waters with the remaining k being recycled to new growth of plants the plant k transferred to rivers was never included in any previous budget model that assessed the sources and pathways of k in global river a popularly current view claims that nearly 87 of the total k in global river water comes from weathered silicate source relative to 5 from evaporite deposits 1 from atmospheric salt cycling and 7 from fertilizers in fact some fraction of this silicate material derived k in global river should belong to plant source k derived from leaching of dead vegetation on the surface and in the soils by surface and ground waters the importance of decay of vegetation on the surface and in soils as being a source of k in global river was assessed by using a mass balance equation that expresses the k rb weight ratio of global river in terms of fractional contributions of k from various sources to global river water and the k rb ratios of the contributing sources considering a wide range of values for the k rb ratio of each source of k in global river water calculations have shown that of the proposed 87 silicate derived k in global river water nearly 70 to 30 can be attributed to leaching of dead vegetation on the surface and in soils by surface and ground waters whereas the remaining 17 to 57 can be assigned to leaching of the weathered silicate materials by surface and ground waters a more realistic estimate can be based on taking into account the average crustal silicate k rb ratio of about 250 300 by this measure the k derived from leaching of decayed plant by surface and ground waters is at least as important as the k derived from leaching of weathered silicate materials by surface and ground waters 43 44 each and may be even more important than the k derived from leaching of the weathered silicate materials 70 72 for the plant source k in contrast to 15 17 for the silicate source k as a control of the dissolved k in global river water we have also estimated that nearly 97 98 of k released from dead vegetation on the surface and in the soils is cycled back each year to newly grown plants

extension of cathaysian flora during the permian climatic and paleogeographic constraints abstract recent paleobotanic investigations have been described during the late permian intermingled cathaysian south china block gondwanian and euramerian flora assemblage in oman arabian plate by analogy with present rainforest flora cathaysian floral elements in northeastern gondwana require permanent precipitation even if a short dry season may be endured on the contrary eurasian flora is most probably adapted to dryness we investigate the temporal and spatial extension of this surprising flora assemblage using numerical climatic simulations and paleomagnetic reconstructions we suggest that the settlement of cathaysian flora was possible as soon as this area reached about 20 s according to paleomagnetic data the southeastern arabian plate reached this latitude during late permian which exactly corresponds to the age of the oldest discovered cathaysian flora elements in oman moreover the paleomagnetic configuration of plates allows for easy chinese to gondwana connections using migrating blocks in the tethys or island arcs however the climatic simulations suggest the presence of a dry season lasting about 5 months in southeastern arabia such precipitation conditions would probably prevent the settlement of cathaysian plants we thus propose that the intermingled assemblage reflected the paleoenvironmental conditions cathaysian plants grew in a flood plain with perennial water supply whereas euramerian plants lived out of the flood plain over adjacent hills where water was only supplied by seasonal precipitation migration paths of these different floras are also discussed

stratigraphy of deformed permian carbonate reefs in saraburi province thailand kilometre scale thrusts affect the stratigraphic order of the sedimentary rocks that form the khao khwang platform in central thailand the effect of these thrusts requires detailed analysis to unravel the original distribution of the sedimentary units and their associated facies the khao khwang platform comprises three carbonate dominated units identified previously as the phu phe khao khad and khao khwang formations these carbonates are intercalated with clastic mixed siliciclastic and carbonate sequences the sap bon pang asok and nong pong formations the palaeogeography of the area prior to the indosinian orogeny is poorly known and has herein been investigated by combining structural reconstructions microfacies and biostratigraphy in the saraburi area a stratigraphic model for the yakhtashian midian carbonate platform palaeogeography using the well developed exposed sections of the khao khwang platform located in the saraburi province of thailand is presented this has revealed the presence of several separate carbonate platforms dominated by four major middle permian facies peritidal platform interior algal reef and basin slope which are dated using foraminifera and algae this model integrates recent structural studies and considers their impact on the present day distribution of the facies in terms of platform development using biostratigraphy and detailed microfacies analysis supplementary material characteristic images of the six facies high resolution stratigraphic logs a timescale correlation chart and a table detailing the common fossils identified in this study are available at https doi org 10 6084 m9 figshare c 3861796

the break up of east gondwana along the northeast coast of oman evidence from the batain basin recent detailed studies on the batain nappes northeast coast of oman which represent a special part of the so called oman exotics have led to a better understanding of the neotethyan geodynamic evolution the batain exotics bear witness to volcanic activity sea level changes tectonic instability rifting and oceanization along the eastern oman margin during late palaeozoic and mesozoic times they allow definition of the batain basin as an aborted permian branch of neotethys this marine basin was created in early permian times extending southward to the east african madagascar region and was linked to the karoo rift system the presented revised classification of the batain nappes considers the batain basin to be no longer a part of the hawasina basin and the neotethyan margin proper we attribute the batain basin to a mozambique somali masirah rift system somoma this system started in early permian times creating a marine basin between arabia and india madagascar rifting in the late triassic and oceanization during late jurassic times led to the separation of east gondwana

geochemical evidence for the origin of late triassic melange units in the oman mountains as a small ocean basin formed by continental rifting a useful tool to elucidate past tectonic environments is the geochemistry of volcanic and sedimentary rocks when used together the regional structural setting of the oman mountains indicates that deep water sediments and volcanic rocks formed adjacent to the rifted arabian margin in the late triassic near the axis of a narrow ocean basin of red sea type tholeiitic to trachytic extrusives formed seamounts associated with late triassic reefal build ups immobile trace element compositions point to a within plate origin the interbedded and overlying late triassic deep sea sedimentary cover comprises ribbon radiolarites and both distal siliclastic and calcareous turbidites that accumulated on an abyssal plain at least ca 180 km northeast of the arabian continent associated ferromanganiferous oxide sediments are interpreted as chemical precipitates derived from high temperature vents in the spreading axis of the young ocean basin pervasive regional subsidence took place during end triassic early jurassic time later in the cretaceous oceanic crust was consumed in a northeast dipping subduction zone morb type crust was subducted while late triassic volcanic edifices and sedimentary cover were accreted during eventual trench margin collision the semail ophiolite split into blocks allowing sub ophiolite melange rocks to be expelled upwards through corridors creating the batinah melange as the ophiolite nappe ploughed inboard over already thrust assembled abyssal plain sediments hawasina complex some duplexes were uplifted oversteepened overturned and then slid backwards onto the ophiolite to form the batinah sheets

promotion of chemical weathering by higher plants field observations on hawaiian basalts abstract an electron microprobe and petrographic microscope were used to study the biota rock interface beneath higher plant communities and lichens as well as unvegetated surfaces on hawaiian basalt flows ranging from a few years to several thousand years in age and currently receiving moderate to extremely high annual rainfall we find dramatic order of magnitude minimum acceleration of weathering rates beneath vascular plants on the youngest flows relative to adjacent non or primitively vegetated controls notably rocks colonized by the common fruticose lichen stereocaulon uulcani bulk dissolution of plagioclase accounts for most of the weathering observed beneath higher plants on these young basalts analysis of older flows under mature forests reveals that chemical weathering beneath vascular plant communities continues unabated for thousands of years after initial colonization moreover such weathering is not limited to exterior basalt surfaces but is commonly found adjacent to joints and vesicles within the rock where it is often associated with fine sub 2 mm diameter plant roots plagioclase dissolution was also observed on lichen encrusted and unvegetated flows a few hundred to thousands of years in age but it was typically much less advanced than beneath higher plants and rarely extended more than several millimeters from exterior rock surfaces chemical denudation rates on older flows with higher plants are at minimum ten times greater than those with only lichens or microbiota in the environments studied if s uulcani and associated microflora resemble the terrestrial precursors to vascular plant communities then the results of studies such as this have implications for the history of atmospheric co 2 and the earth s climate

seawater 87sr 86sr ratios along continental margins patterns and processes in open and restricted shelf domains abstract to better constrain the sr isotope budget in marginal domains without any fluvial inputs we analyzed the chemical composition and 87sr 86sr ratio of waters and shells from four locations two coastal lagoons one hemipelagic platform and one open marine shelf our results highlight homogeneous 87sr 86sr ratios typical of oligotrophic oceanic waters oow i e 0 709172 0 000023 in the pacific tatakoto atoll and along a mediterranean shore to offshore transect 25 km off banyuls sur mer bsm this attests that oceanic inputs from oligotrophic areas remain the main sr source in open shelf areas compared with submarine groundwater discharges sgd or particulate dissolution influences in bsm only foreshore data are more radiogenic possibly due to rainwater mixing local groundwater springs or more efficient particle dissolution in the intertidal zone in restricted areas we report variable 87sr 86sr ratios between the salses leucate france and oualidia morocco lagoons the first one has homogeneous 87sr 86sr ratio typical of oow except close to sgd in oualidia 87sr 86sr ratios decrease by 1 2 10 3 from oow values close to the atlantic inlet to progressively less radiogenic ones upstream within the interior of the lagoon these differences depend on several factors including the leaky restricted or choked morphology of lagoons modulating the oceanic sr inputs but also sgd fluxes whose 87sr 86sr ratios and sr concentrations are highly variable according to the nature of rocks leached in karstic aquifer in oualidia the low 87sr 86sr ratios correspond to high sr concentrations up to 150 mol l 1 issued from the dissolution of mesozoic evaporites leading to sgd fluxes accounting for 60 of the local sr budget through data compilation we show that similar 87sr 86sr gradients and processes prevail at the whole mediterranean scale finally we postulate that high coastal water retention times can also account for anomalous coastal 87sr 86sr ratios and that the combination of water mass restriction sgd bioadsorption and early diagenetic processes could decrease seawater sr concentrations in some marginal areas

rift related sedimentation and volcanism of the north indian margin inferred from a permian triassic exotic block at lamayuru indus suture zone ladakh himalaya and regional comparisons abstract stratigraphical petrographical and geochemical work on an important limestone exotic within the indus suture zone near lamayuru reveals the following history of events i late permian deposition on a shallow water carbonate platform open to the neotethys ocean ii late permian early triassic break up tilting fissuring and subsidence iii early triassic mantling by ammonite bearing pink pelagic carbonate and chlorite rich volcaniclastic sediment iv deposition of fe mn and or mn rich oxide sediments as crusts and fissure fills the metal rich oxides were precipitated from hydrothermal solutions related to nearby volcanism v late triassic eruption of pillowed and massive basalts of within plate type on an irregular seafloor taking account of evidence from similar exotic units associated with upper cretaceous melange beneath the spontang ophiolite further south in the zanskar mountains e g photoskar unit the lamayuru exotic is interpreted as part of a small carbonate platform formed somewhere between the zanskar lamayuru passive continental margin and a permian triassic neotethyan spreading axis to the north the carbonates probably capped a volcanic seamount that later collapsed and was covered by pelagic sediments and basic extrusives the lamayuru exotic was later detached from its igneous basement and tectonically emplaced probably in the latest cretaceous and was also influenced by early tertiary suturing of neotethys and mid late tertiary backthrusting

sequence of thrusting and origin of culminations in the northern and central oman mountains abstract detailed mapping and structural analysis of three large scale culminations sumeini and asjudi half windows and haybi hawasina window in the oman mountains shows a considerably more complex history of deformation than a simple foreland or downward sequence of thrust development early thrusting processes tended to create a regular stacking order of imbricate slices and major thrust sheets complying with the rules of thrust propagation assembled progressively downwards and forwards in the direction of translation out of sequence thrusts can also be demonstrated in places by truncation of footwall structures folds imbricate slices etc gross strain differences between thrust sheets downward facing structures in footwall units and elimination of thrust sheets beneath late stage thrusts frequently cut up section through the previously assembled stack putting previously younger lower thrust sheets over previously older higher ones many of the culminations in the northern and central oman mountains were formed by ramping associated with this late stage leap frog rethrusting event

morphology of the basement and hormuz salt distribution in offshore abu dhabi from constrained 3 d inversion of gravity and magnetic data abstract many seismic surveys and exploration wells have been conducted in offshore abu dhabi united arab emirates however the neoproterozoic basement and the infracambrian hormuz salts were not imaged or penetrated by seismic and well data to delineate the morphology of the basement and distribution of salt bodies we applied a 3 d constrained inversion method to aerogravity and aeromagnetic data covering offshore abu dhabi well and seismic data were used to constrain and validate the inversion results the magnetic inversion model resulted in a robust basement model that varies in depth from 8 to 10 km with two highs at 8 and 8 5 km highlighting possibly magmatic bodies in contrast the gravity inversion model does not delineate very well the basement morphology possibly due to the lower density salt bodies masking the gravity response of the higher density basement by calculating and removing the gravity response of the magnetic basement model from the observed gravity data we recovered the residual gravity response of the hormuz salts the 3 d gravity inversion of the residual shows that the hormuz salts are more wide spread and thicker than previously thought with a depth to top of salt varying from 5 5 to 8 5 km this salt model suggests that the giant oilfields in offshore abu dhabi such as umm shaif nasr abu al bukhoosh zakum sarb and hail occur exactly above crests of salt pillows in addition a series of smaller oilfields are found located at the margin of the northern basement high and three structural lineament trends ne sw nw se and n s were identified from the inverted basement and salt models reactivation of these fault trends and associated diapiric salt uplifts as observed in the seismic sections and curvature map played a major role in shaping the basement morphology and mobilization of the hormuz salts

structure and evolution of the passive margin of the eastern tethys abstract an extensive passive margin was formed in the triassic along the periphery of arabia including the tauric carbonate platform this event is related to the opening of the mesozoic tethys when a number of microcontinents split off from gondwana triassic extension and continental rifting resulted in the formation of a structural pattern which is uniform from the dinarides to oman it includes the following elements 1 1 shelf 2 2 continental slope 3 3 deep basin probably with a floor of attenuated sialic crust 4 4 inner carbonate platform in the jurassic cretaceous stable conditions prevailed influenced only by eustatic oscillations of the sea level turbidites accumulated on the continental rise while cherts and radiolarites were deposited in the deep basins hawasina pichakun antalya pindus below the ccd level sedimentation on the shelf was controlled by north northeast transverse tectonic elements which also continued across the passive margin dividing it into a number of segments collision with an island arc led to obduction of the oceanic crust deformation of the passive margin and overthrusting of its sedimentary cover onto the arabian shelf obduction and deformation lasted for about 10 m y and created a new tectonic pattern with concentric structural zones surrounding the arabian promontory these zones include 1 1 the flysch basin a remnant of the closing tethys 2 2 an uplift a site of periodical emergence and erosion corresponding to the frontal part of the ophiolitic nappes 3 3 the border furrow a depocenter of low energy calcareous marls 4 4 the arabian shield constantly emerged during the tertiary tectonic deformation of these zones caused by the collision of arabia with eurasia began prior to the early miocene and it is still going on data on afghanistan demonstrate that its central part the gelmend argandab and kabul blocks belonged during the paleozoic and early mesozoic to the continental shelf of india

strontium isotopic paleontological method as a high resolution paleosalinity tool for lagoonal environments a combined strontium isotopic 87 sr 86 sr and paleontological method is newly applied to a modern lagoon in egypt s nile river delta to test its applicability as a paleosalinity proxy analyses of 22 surficial samples collected throughout the lagoon include 81 sr isotopic analyses of mollusks foraminifera ostracods barnacles bryozoans serpulid worm tubes pore water and gypsum crystals two salinity groups are distinguished in each sample a lower salinity group 1 ppt mixed with a higher salinity group 3 10 ppt that respectively are interpreted as the modern biocoenosis and an older relict fauna the relict fauna denotes higher salinity conditions in the lagoon prior to closure of the aswan high dam 1964 and the modern fauna records freshening of the lagoon recent decreased salinity is a response to regulated nile river flow and increased discharge into manzala of fresh water via canals and drains quantification of this short term salinity change holds promise for study of modern lagoons in other world settings and may provide paleoclimatic information for older lagoon sequences in the nile river delta and the geologic record

oman exotics oceanic carbonate build ups associated with the early stages of continental rifting the so called oman exotic limestones form isolated masses from boulder size to 1 000 m thick of middle to upper permian and upper triassic fossiliferous limestones and crop out within imbricated thrust slices beneath the semail ophiolite in the oman mountains permian exotics are of dominantly reef and forereef facies whereas triassic exotics are more typically of back reef and lagoonal facies they are commonly associated with a substrate of alkalic and transitional tholeiitic basalts and are interpreted as a series of reef associated carbonate buildups deposited in part on oceanic islands or seamounts close to the site of initial rifting of the oman continental margin

crustal volume balance during the india eurasia collision and altitude of the tibetan plateau a working hypothesis a working hypothesis is developed for the two stages of evolution of the tibetan plateau during the continental collision between india and eurasia the first phase was dominated by crustal shortening and thickening in what is now tibet while indochina was expelled southeastward away from eurasia at the end of this phase at 17 ma the estimated tibetan crustal thickness was 51 km the second phase has been dominated by thickening of tibet by the influx of crustal material from india with no associated crustal shortening the crustal thickening that is inferred to have occurred by this process is only feasible because leakage of crust from beneath the plateau is restricted by neighboring archean cratons that block lower crustal flow this leakage to the east and south from tibet to beneath yunnan is estimated as 20 30 of the influx at present but was much smaller at the start of this second phase of deformation it is suggested that at 11 ma the force exerted against the tibetan upper crust by this flowing material first exceeded the threshold that this brittle layer could resist and tibet began to extend eastward any satisfactory working hypothesis for the tibetan plateau must explain its dimensions its 17 ma ending of shortening and 11 ma start of extension and volcanism the eastward slip sense on its active normal and strike slip faults and the ratios of their displacements to present day slip rates which imply that their slip rates have gradually increased this working hypothesis accounts for these features and predicts a smooth and continuing increase in altitude

strontium isotopic composition of modern and holocene mollusc shells as a palaeosalinity indicator for the baltic sea abstract the 87sr 86sr isotope ratio in subfossil carbonate mollusc shells from raised beach sediments is used as a palaeosalinity indicator for the baltic sea the main purpose is to demonstrate the applicability of the method in a formerly glaciated area using 87sr 86sr ratios found in modern shells mytilus edulis macoma baltica and radix balthica to elucidate the parameters and conditions to be used for palaeosalinity determinations based on subfossil shells proxy salinity data are calculated assuming that the sr concentration in baltic sea water is controlled by a two component conservative mixing between seawater and river water based on replicate determinations of the 87sr 86sr ratio in modern shells proxy salinity data can be quantified with a relative precision of better than 5 for salinities up to 10 comparison with measured present day salinities indicates that the accuracy is generally better than 5 for the proxy data with this precision and accuracy the present day salinity differences between the major baltic sub basins bothnian bay bothnian sea and baltic proper can be detected palaeosalinities were determined using subfossil shells m edulis and m baltica with calibrated 14c ages of 6770 3070 cal bp the shell deposits occur from 65 m a s l down to the present day sea level the palaeosalinities determined for the bothnian bay 4 8 10 3 and the bothnian sea 7 3 10 3 are in good agreement with earlier estimates of the maximum littorina sea stage palaeosalinity in these sub basins 8 10 at one locality two different shell species from the same shell deposit were dated m edulis and m baltica the shells differed in age by 460 70 14c years a possible indication that the ecological conditions at a locality may have been favourable to different faunas at different times

nonhomogeneous seawater sr isotopic composition in the coastal oceans a novel tool for tracing water masses and submarine groundwater discharge here we present high precision 2 3 ppm 87sr 86sr measurements in coastal waters together with salinity to evaluate water mass mixing and the influence of submarine groundwater discharge sgd in coastal waters and marginal seas nonhomogeneous sr isotopic variations in water columns were documented in the southern okinawa trough sot south china sea and kao ping canyon kpc where seawater 87sr 86sr varied up to 70 ppm seawater sr isotopic composition changes only slightly in the upper 200 m of the sot but was detectable and highly correlated with salinity indicating a mixing between radiogenic north pacific tropical water high 87sr 86sr and high salinity at 100 150 m and a less radiogenic component with low 87sr 86sr and low salinity at 200 m vertical profiles of seawater 87sr 86sr along the kpc show significant variations suggesting dynamic mixing affected by continental inputs i e river runoff and sgd in this region these results highlight the potential use of seawater sr isotopes as a powerful tracer for determining mixing ratios and the dynamic mixing of oceanic water masses especially in coastal and marginal seas