modeling the mineralogy of atmospheric dust sources the variability of atmospheric dust mineralogy influences the impact of desert dust on the earth s radiative budget and biogeochemical cycles until now atmospheric transport models have assumed that dust was a constant homogeneous mixture hence neglecting this variability the lack of mineralogical data in arid areas prevented a better description of the atmospheric dust composition and we propose here a new formulation to estimate the mineral content of arid surfaces on a global scale first we collect a database of arid soil surface mineralogy for eight major minerals quartz feldspar calcite gypsum illite kaolinite smectite and hematite both for the clay and silt fraction on the basis of this we formulate a mean mineralogical table that relates classical soil types to surface mineralogy we use this table and the geographical distribution of soil types given in the food and agriculture organization soil map of the world to obtain the mineralogy of arid surfaces globally in order to validate these results we present a compilation of measured mineralogical composition of dust samples with identified sources the correlation between observed dust mineralogy and those inferred from soil types in corresponding areas is between 0 70 and 0 94 we then calculate the maps of the single scattering albedo and of the ratio of infrared extinction to visible extinction for the erodible fraction of arid areas mineralogical maps presented here will be used in future studies with an emission scheme in a global transport model

aeolian dust in europe african sources and european deposits abstract a conceptual model is presented for the provenance and dispersal patterns of small dust that falls on europe generally its sources are in north africa and it is distributed across all europe several key sources can be distinguished sahelian dust comes largely from the old lake chad region this is a clay rich unimodal material saharan dust comes from the great sand sheets it contains small monomineralic particles and may have a bimodal size range three simple deposition zones can be recognised a d1a zone where sufficient dust is deposited to form a discrete soil layer not well classified as a rendoll in the extreme south of europe a d1b zone where the airborne dust simply provided a silty admixture to soil systems across middle europe and a northern zone d1c where the dust is a fugitive cloud but very occasionally forms noticeable deposits two particle formation methods can be noted particle control in sahelian dust is via the sedimentation in the original lake this gives an open structure which can be modelled using a simple monte carlo approach the open structure ensures that only small particles are produced size control is via particle packing a chipping mechanism can produce fine quartz particles from sandy deserts the aeolian energy is by and large not sufficient to cause major impact fracturing but small mineral chips can be produced in the small dust size fine and very fine silt which go into high level suspension and travel to europe and beyond the saharan material can have a wider more variable size distribution than the sahelian material the canary islands loess is largely sahelian material the cape verde islands deposits from the nearby sandy regions are saharan deposits large dust has fallen on europe and produced widespread loess deposits large dust is essentially an in continent deposit small dust comes from outside from africa

microscopy and mineralogy of airborne particles collected during severe dust storm episodes in beijing china 1 asia dust storm ads samples were collected during two severe dust storm episodes in beijing china high resolution field emission scanning electron microscopy fesem and environmental scanning electron microscopy energy dispersive x ray detector esem edx coupled with an image analysis system were used to study the morphology chemical compositions and number size distributions of ads particles fesem analysis indicated that beijing ads samples were mainly composed of irregularly shaped mineral particles more than 50 of the ads particles were larger than 1 m measured as equivalent spherical diameter esd image analysis showed that when the dust storm episodes ended in beijing the number of anthropogenic particles such as soot aggregates and coal fly ash in the samples increased and the number of mineral particles decreased analysis of individual ads particles showed that about one fifth of all the particles were mineral aggregates and at least one fourth of the particles contained sulfur x ray diffraction xrd was used to quantify the phase and the clay mineral compositions of ads samples phases in the ads sample collected during the 20 march 2002 dust storm episode included clay minerals noncrystalline materials quartz calcite plagioclase potassium feldspar pyrite hornblende and gypsum in descending order clay minerals were mainly illite smectite mixed layers 78 followed by illite 9 kaolinite 6 and chlorite 7 particulate matter pm less than 10 m were enriched with clay minerals and deficient with quartz by mass compared with the total suspended particulates collected during an ads episode the pm less than 10 m collected during the two severe dust storm episodes was characterized by the absence of dolomite high quartz clay ratio and dominance of illite smectite mixed layers in clay minerals

geochemistry and mineralogical composition of the airborne particles of sand dunes and dust storms settled in iraq and their environmental impacts five dust storms that occurred in 2008 15 march 11 april 28 april 25 may and 26 june in addition to the many sand dunes disseminated in the western desert of iraq are sampled the worse dust storm that occurred in iraq in 11 april 2008 covered 75 of the iraq area and deposited 6 9 million tons approximately as a total weight of fallout during just 8 h declining temperature 6 c during the episodes of dust storms visibility decreased enormously no more than 30 m many people were taken to hospitals after sustaining breathing problems some of them died clay fraction is the dominant part in the dust storms forming 70 besides a little silt 20 6 and sand 9 4 then classified as mature arkose of clay to sandy clay whereas sand dunes are formed from 72 7 sand 25 1 silt and 2 19 clay then classified as mature arkose of silty sand sand dunes have much maturity mineralogical composition of dust storms and sand dunes are quartz 49 2 67 1 feldspar 4 9 20 9 calcite 38 5 gypsum 4 8 0 4 dolomite 0 8 1 and heavy minerals 3 2 6 6 respectively heavy mineral suites in the dust storms are represented by zircon pyroxene hornblende chlorite and magnetite whereas the sand dunes are represented by zircon tourmaline garnet and pyroxene concentrated within sand fraction heavy minerals according to satellite images revealed the dry land of sahara desert in north africa and the arabian peninsula as well as syria and jordan were a major source of the dust storms that have occurred in asia including iraq

evolution and distribution of the conodonts sweetognathus and iranognathus and related genera during the permian and their implications for climate change abstract the conodont genus sweetognathus which is characterized by pustulose ornamentation on a wide flat topped carina originated in the earliest permian as s expansus from diplognathodus edentulus the asselian through artinskian part of the sweetognathus lineage is well represented in kansas by the successive evolution of s expansus s merrilli s aff s merrilli s whitei and s bucaramangus sweetognathus and iranognathus lineages were mainly confined to tropical areas from the kungurian onward the kungurian and guadalupian part of the sweetognathus lineage is well represented in south china by the successive evolution of s whitei artinskian s guizhouensis lower kungurian s subsymmetricus upper kungurian s iranicus hanzhongensis roadian and s fengshanensis capitanian an additional lineage in west texas is represented by the evolution of s sulcatus to s aff adjunctus to s adjunctus and to s bicarinum in the urals and northwestern pangea the late part of the sweetognathus lineage is represented by rare specimens of s bogoslovskajae upper artinskian lower kungurian during the late artinskian s whitei radiated into s toriyamai and s bucaramangus and also gave rise to neostreptognathodus pequopensis and probably pseudosweetognathus costatus neostreptognathodus exsculptus may have evolved from adetognathus paralautus through adetognathus telfordi sp nov iranognathus characterized by a narrow carina with poorly developed denticles and bearing subtle and smaller pustulose micro ornament replaced sweetognathus at or near the guadalupian lopingian boundary it probably also evolved from diplognathodus in the topmost guadalupian a lineage of iranognathus sp nov a to i erwini can be recognized for the guadalupian and lopingian boundary interval a lineage of iranognathus sp nov a to i movschovithschi to i sosioensis to i tarazi is found throughout the guadalupian and lopingian boundary interval and the wuchiapingian of south china sweetognathus and iranognathus tend to develop homeomorphic accessory nodes iteratively during lowstand periods of global sea level near the artinskian kungurian and guadalupian lopingian boundaries and in the late wuchiapingian sweetognathus and iranognathus seem to be equatorial warm water inhabitants distribution patterns reflect glaciation in gondwana during the asselian and sakmarian a warm climate during the artinskian cooling in north pangea during the kungurian and later permian slight amelioration during the guadalupian warming during the wuchiapingian and cooling during the changhsingian in the peri gondwana region definitions for most of the important sweetognathus species are refined three new species and subspecies iranognathus sp nov a adetognathus telfordi sp nov gullodus duani sp nov are described

characterization of late glacial continental dust in the greenland ice core project ice core twelve glacial dust samples extracted from the greenland ice core project ice core have been characterized in terms of mineralogy sr and nd isotopic composition and rare earth element concentrations the ice samples are taken from the younger dryas the bolling the last glacial maximum and both cold and mild glacial periods back to 44 kyr b p a comparison with samples from possible dust source areas determines eastern asia as being the main source area at all times hereby confirming and extending earlier results biscaye et al 1997 this finding is partly in agreement with recent atmospheric general circulation model simulations of glacial atmospheric dust transport andersen et al 1998 mahowald et al 1999 a low intersample variability in tracer characteristics is discussed in the context of a volcanogenic influence grain size dependence and variability in the conti nental dust source areas the clay mineralogy of the ice core dust shows a weak climatic de pendence while the isotopic composition of sr and nd does not correlate with climate this is interpreted as a geographical variation of source areas on a regional scale within asia two ice dust samples were size fractionated at 2 gm and the grain size dependence on tracer characteristics is in accordance with the literature

paleoclimate and paleoceanography over the past 20 000 yr in the mediterranean sea basins as indicated by sediment elemental proxies abstract marine sediments record paleoenvironmental changes over time through variations in major and trace element concentrations the main objective of this paper is to review such changes in the mediterranean sea basins over the last 20 ka using the inorganic chemistry and mineralogy of marine sediment records elemental ratio proxies that are mostly used are discussed and the uncertainties involved in using them for paleoclimate and paleoceanographic reconstructions are evaluated the focus on the mediterranean region is based on the sensitivity of this region to global climate changes due to its semi enclosed nature the elemental ratios that have been particularly useful for reconstructing terrigenous inputs into the mediterranean have been ti al and zr al ratios as proxies for eolian dust input and mg al k al and rb al ratios as proxies for fluvial input redox sensitive elements e g u mo v co ni cr have provided reliable reconstructions of oxygen conditions at the time of deposition some of these elements are also particularly susceptible to post depositional remobilization and record diagenetic processes instead of the original environmental signatures regarding productivity fluctuations most of the paleoproductivity reconstructions are based on the abundance of barite and ba excess algorithms the biogeochemistry of ba is however not fully understood and mechanisms for barite precipitation in the water column are not yet known two case studies are presented the eastern mediterranean sapropel s1 deposited between 10 8 and 6 1 cal ka bp and the westernmost mediterranean paleoclimate record over the last 20 ka

late miocene to early pliocene climate variability off nw africa odp site 659 abstract a high resolution 18 o record obtained on benthic foraminifera cibicides wuellerstorfi combined with clay mineralogy major element concentrations and sr nd isotopes have been investigated for the odp site 659 located off north africa in order to reconstruct african monsoon intensity between 6 2 and 4 9 myr mineralogical and geochemical results indicate that sedimentation on the cape verde plateau results from a mixture of sediments deriving from the neighbouring saharan arid region and the wet african equatorial zone sahelian band characterised by a low and a high state of weathering respectively past variations in terrigenous inputs from these areas allow us to track past extension and displacement of the west african monsoon itcz system maximal summer insolation induced a northward migration of the inter tropical convergence zone itcz wetter conditions in the sahel and a diminishing of wind erosion over the south sahara and sahel in addition there was an increase in river input to the cape verde plateau of sediments derived from southern sedimentary sources which are characterised by high kaolinite contents and cia values and low k al and ti al ratios on the other hand minimal summer insolation induced a southward movement of the itcz drier climate in the sahel and stronger easterly winds resulting in an increase in dust transport from the sahara to the cape verde plateau dust particles are characterised by high illite and smectite content and by a low chemical state of weathering low cia values and high k al and ti al ratios finally our results provide new clues regarding the re flooding of the mediterranean sea at the end of the msc 5 33 myr this event was associated with enhanced aridity in the sahara implying a reorganisation of the atmospheric circulation and a southward migration of the itcz

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

african dust observed over canary islands source regions identification and transport pattern for some summer situations bulk filtration samples of dust were collected on fuerteventura canary islands in july 1985 in order to investigate african dust transport over this region during summer air mass trajectories and elemental and mineralogical analyses allowed us to distinguish between oceanic and continental influences three african dust transport cases occured during this period geochemical and mineralogical tracers combined with air mass trajectories indicate that two different source regions of dust sahelian and moroccan ones are involved each of these exhibits specific si al and fe al ratios that can be considered as tracers of dust origin a meteorological study based on satellite imagery meteorological maps and air mass trajectories confirms the previous identification of the source region it is also possible to describe the meteorological situation controlling the atmospheric pathway of the dusts from the source regions up to the canary islands this study suggests that some source regions especially the sahelian one of dust affecting the canary islands during summer are rather different from the moroccan ones observed in a spring situation by coude gaussen et al 1987

variation of soluble and insoluble calcium in red rains related to dust sources and transport patterns from north africa to northeastern spain 1 we use the chemical composition of african dust delivered by red rains at a rural site in northeastern spain montseny 4146 0 n 221 0 e to describe its relationship with the possible provenance areas and the processes occurring during transport to this end we obtained the red rain insoluble composition for the major elements al fe ca mg k p ti and na in 30 filters the 210 pb concentration in 23 filters and the soluble cation concentrations na k ca and mg in 28 coincident red rain samples these samples comprised most major events occurring at the site from 1983 to 2002 on the basis of back trajectories and satellite images a distinction has been made between an eastern and western air mass flux with respect to 0 greenwich for the analyzed samples principal component and anova analyses between the two provenance groups have shown striking differences in the insoluble phase with eastern samples being significantly richer in insoluble ca mg and sr compared to western samples conversely western samples had significantly higher concentrations of insoluble al fe k v and 210 pb than eastern samples therefore in the insoluble phase the ratios of various elements to ca were significantly higher in western provenances however these differences disappeared when considering bulk ca ratios bulk ca insoluble soluble ca neither of the ratios fe al and ti fe showed significant differences this lack of differences is interpreted in view of a similar carbonated lithology broadly underlying both areas the difference in insoluble ca with respect to total ca between provenances cainsoluble catotal 0 10 and 0 70 for western and eastern trajectories respectively is interpreted as a difference in calcite dissolution during transport evidence from 210 pb data and from the length of the back trajectories indicates that western trajectories covered a longer distance than the eastern ones their higher soluble ca could be due to 1 higher calcite dissolution due to longer contact with wet fronts from the atlantic and 2 particle segregation during transport with finer carbonate particles more prone to dissolution due to a higher surface to volume ratio

mineralogical variation of sr nd isotopic and elemental compositions in loess and desert sand from the central loess plateau in china as a provenance tracer of wet and dry deposition in the northwestern pacific we determined sr and nd isotopic compositions and major trace and rare earth element ree compositions of evaporite and detrital minerals in loess and desert sand from the central loess plateau clp where 80 of the loess deposits in china are found the loess exhibited a narrow range of variation in 87sr 86sr 0 715 0 001 a sequential extraction experiment on the loess however showed that water and acetic acid hoac soluble minerals mainly halite and calcite hydrochloric acid hcl soluble minerals chlorite and phosphate and hcl insoluble minerals illite kaolinite smectite vermiculite feldspar and quartz have distinct 87sr 86sr ratios approximately 0 7111 0 0004 0 7141 0 0004 and 0 7195 0 0010 respectively the water and hoac soluble ratios were regionally uniform and were close to the 87sr 86sr value of river water from the huanghe yellow river and the maximum 87sr 86sr value of spring rainwater in japan suggesting selective solution of eolian halite and calcite into the chinese river water and into the japanese rainwater the mineralogical elemental and sr nd isotopic compositions of hcl soluble and insoluble minerals in the clp loess were different from those of the northern desert sand but were indistinguishable from those of its fine grained fraction supporting the view that the loess is composed of the fine grained fraction of desert sand that was transported to the southeast in the atmosphere the 87sr 86sr end and gd yb values of hcl insoluble minerals in the clp loess were almost identical to those of airborne dust soil minerals and deep sea sediments in the northwestern pacific considered to be of eolian origin suggesting dissolution of the loess evaporite minerals during atmospheric transportation these relationships demonstrate the usefulness of sr isotopes of water and hoac soluble minerals and sr and nd isotope ratios and ree compositions of acid insoluble minerals in loess as provenance markers for wet and dry deposition respectively

bulk composition of northern african dust and its source sediments a compilation abstract this paper presents a review of bulk compositional data of northern african dust and its potential source sediments and includes elemental isotope and mineralogical data northern african dust represents about one half of the total global atmospheric mineral dust burden and its uplift transport and deposition have strong impacts on climate and various terrestrial and marine ecosystems the chemical data set shows that an average northern african dust exhibits comparable si fe and mn contents with respect to the average composition of the upper continental crust is slightly depleted in the alkali metals k and na and enriched in ti and p however the complete data set yields clear evidence that northern african dust and its source sediments are compositionally heterogeneous on a regional scale and that this heterogeneity can be used to differentiate between major potential source areas on the basis of so called source markers an evaluation of these compositional fingerprints shows that the following parameters and especially their combination are effective in the discrimination of the most active source areas in northern africa ratio of ca mg fe wt calcite or carbonate content palygorskite occurrence and abundance illite kaolinite ratio nd 0 value and 87sr 86sr ratio for example the data set corroborates previous ideas which assign carbonate illite and palygorskite rich mineral dusts to north west ern source regions because most of the above listed source markers do not change substantially during transport even far traveled dusts may be assigned to specific potential source areas in northern africa some limitations of the presented data set are also discussed our compilation reveals some substantial gaps in the knowledge of the composition of source sediments and mineral dusts from important potential source areas that should be filled in the future the here compiled data set can be used as a reference frame when incorporating the composition of source sediments e g mineralogy into global or regional dust transport models and can be compared with source analysis by remote sensing or back trajectory analysis however source apportionment studies supported by our data set will not only be useful for actual dust samples but will also be helpful for the understanding of paleo wind directions and hence paleo climatological conditions through the investigation of quaternary eolian sediments deposited in and around northern africa

mineralogy as a critical factor of dust iron solubility 1 to understand the impact of dust deposition on ocean primary productivity the evaluation of dust input is not sufficient and the soluble iron supply is also needed measurements of iron in aerosols suggest a much higher solubility than in soil implying substantial atmospheric processing of chemical or physical nature here we have investigated the effect of the mineralogy on iron solubility we have measured iron solubility from some minerals commonly found in dust clay feldspar and iron hydr oxides firstly we observe a greater solubility of iron resulting from clays 4 in comparison to iron hydr oxides 1 independently of specific surface of minerals secondly by considering amount of dissolved iron and the mineralogical composition of dust our results indicate that dissolved iron fraction mainly comes from clay dissolution in contrast to that assumed in some biogeochemical models in consequence it appears that iron solubility is closely linked to the mineralogical composition of aerosol

the contemporary physical and chemical flux of aeolian dust a synthesis of direct measurements of dust deposition abstract the deposition of aeolian or windblown dust is widely recognized as an important physical and chemical flux to ecosystems dust deposition adds exogenous mineral and organic material to terrestrial surfaces and can be important for the biogeochemical cycling of nutrients there have been many studies that characterize the physical and chemical composition of dust however few studies have synthesized these observations in order to examine patterns geochemical fluxes we have compiled observations of dust deposition rates particle size distributions psd mineralogy and bulk elemental and organic chemistry the rates of dust deposition observed across the globe vary from almost 0 to greater than 450 g m 2 yr 1 sites receiving dust deposition can be partitioned into broad categories based on there distance from dust source regions when compared to global dust models our results suggest some models may underestimate dust deposition rates at the regional and local scales the distance from the source region that dust is deposited also influences the particle size distributions mineralogy and chemical composition of dust however more consistent dust sampling and geochemical analyses are needed to better constrain these spatial patterns on average the concentrations of most major elements si al fe mg ca k in aeolian dust tend to be similar 20 to the composition of the upper continental crust ucc but there is substantial variability from sample to sample in contrast some elements tend to be depleted na or enriched ti in dust likely as a result of soil weathering processes prior to dust emissions trace elements especially heavy metals are consistently enriched in dust relative to the ucc ecologically important nutrients such as n and p are also present in dust deposition the geochemical flux attributable to dust deposition can be substantial in ecosystems located proximal to dust source regions we calculate estimates of elemental flux rates based on the average chemical composition of aeolian dust and varying rates of deposition these estimated flux rates are useful as a rough gauge of the degree to which dust deposition may influence biogeochemical cycling in terrestrial ecosystems and should be utilized to better constrain deposition estimates of global dust models

comments on some permian conodont faunas reported from southeast asia and adjacent areas and their global correlation abstract some important conodont faunas reported from southeast asia excluding south china and japan are re evaluated on the basis of the improved taxonomy and resulting newly established provincialism these faunas are representative of either the equatorial warm water province ewwp or the peri gondwana cool water province gcwp except that the fauna from jilin north china represents the north cool water province ncwp the gcwp is marked by vjalovognathus and or merrillina in the cisuralian vjalovognathus merrillina and mesogondolella in the guadalupian and vjalovognathus and mesogondolella sheni or merrillina in the lopingian the ewwp is characterized by the absence of gondolelloides and vjalovognathus in the early and middle cisuralian abundance of sweetognathus and pseudosweetognathus in the kungurian late cisuralian dominance of jinogondolella and sweetognathus in the guadalupian and dominance of clarkina and iranognathus in the lopingian mixed faunas are recognized in regions on the border between the ewwp and gcwp including western timor during the artinskian southeast pamirs during the kungurian and the salt range during the guadalupian and lopingian

evolution of permian conodont provincialism and its significance in global correlation and paleoclimate implication the main components of asselian through artinskian conodont faunas found around the world are basically the same and the provincialism is indicated only by less common endemic elements such as gondolelloides and new genus a henderson in north pangea sweetognathus bucaramangus around the equator and vjalovognathus in eastern gondwana provincialism is marked by differences at the species level of mesogondolella neostreptognathodus and sweetognathus during the kungurian and becomes very distinct with differences at the genus level during the guadalupian and lopingian three provinces of permian conodonts referred to as the north cool water province ncwp the equatorial warm water province ewwp and the peri gondwana cool water province gcwp are recognized the ncwp is marked by gondolelloides in the early cisuralian dominance of neostreptognathodus and no or rare sweetognathus in the late cisuralian dominance of merrillina and mesogondolella and absence of sweetognathus in the guadalupian and dominance of merrillina and mesogondolella and absence of iranognathus in the lopingian the ewwp is characterized by the absence of gondolelloides and vjalovognathus in the cisuralian abundance of sweetognathus and pseudosweetognathus in the kungurian late cisuralian jinogondolella and sweetognathus in the guadalupian and clarkina and iranognathus in the lopingian the gcwp is marked by vjalovognathus merrillina in the cisuralian vjalovognathus merrillina and mesogondolella in the guadalupian and vjalovognathus and merrillina in the lopingian mixed faunas are recognized in regions bordering between the ewwp and gcwp including western timor during the artinskian pamirs during the kungurian and the salt range during the guadalupian and lopingian three different conodont zonations are proposed one for each of the three conodont provinces four potential horizons for inter provincial correlation of permian conodonts are recognized they are in ascending order 1 the first appearance of sweetognathus whitei which is closely related to the last occurrence of carboniferous type conodonts such as streptognathodus and adetognathus 2 the first appearance of neostreptognathodus pequopensis 3 the base of the jinogondolella nankingensis zone and 4 the base of the clarkina postbitteri iranognathus erwini zone the spatial and temporal distribution pattern of permian conodonts suggests that temperature is the primary controlling factor evolution of permian conodont provincialism reveals a glaciation during the asselian and sakmarian a global warming during the artinskian a climate cooling in north pangea during the kungurian a continuation of kungurian climate trends in the guadalupian a relatively minor warming during the wuchiapingian a returned cooling in the changhsingian and lower and middle griesbachian and a global warming in the late griesbachian which ended the permian conodont lineage

the potential influence of dust flux and chemical weathering on hillslope morphology convex soil mantled carbonate hillslopes in the eastern mediterranean abstract convex soil covered hillslopes are ubiquitous in various tectonic and climatic settings and their morphologic characteristics can be significantly altered by dust flux and chemical weathering carbonate hillslopes across the eastern mediterranean display a classic convex morphology despite high rates of dust deposition which are apparently similar in magnitude to denudation rates and despite a highly soluble bedrock lithology these high rates of dust flux and bedrock dissolution result in soil composition which is strikingly different from the underlying bedrock in this study we apply a modified regolith mass balance equation which includes dust input and chemical depletion and utilize a combination of field work and geochemical methods immobile and major elements xrd to estimate the fraction of dust derived materials in the soil and the fraction of the soil that was lost via dissolution soil and bedrock were sampled at 7 eastern mediterranean study sites across a prominent north to south gradient in both precipitation 250 to 900 mm yr 1 and dust flux 150 to 40 g m 2 yr 1 and compared with dust composition our results indicate that the dust fraction in the soil correlates with modern measurements of dust deposition rates and decrease from nearly 100 of the 2 mm indicating that mechanical weathering of the underlying bedrock contributes to regolith formation and plays a role in shaping carbonate hillslopes using a commonly used soil transport model we show that the observed dust fraction and chemical weathering can potentially account for a 50 change in hillslope curvature furthermore the predicted steady state hilltop curvature based on our results fits well the observed curvature based on high resolution lidar derived topographic data our results highlight the potential importance of dust and chemical weathering in soil production formulations and hillslope evolution models and we propose that these contributors to soil mass balance could also be relevant for silicate terrain in addition we also demonstrate that the source material of mediterranean soils varies with environmental factors such as rainfall dust deposition rates and bedrock mechanical properties

are mediterranean mountains entisols weakly developed the case of orthents from sierra nevada southern spain two orthents from sierra nevada national park spain classified as loamy skeletal mesic typic xerorthent and loamyskeletal frigid lithic cryorthent were studied they were situated at 1460 and 2000 m derived from micaschists and quartzites under mediterranean mountain climate conditions with mesic and cryic temperature regimes and xeric moisture regime these orthents are weakly developed as shown by their reduced thickness their lack of diagnostics subsurface horizons sandy loam textures skeletal and lithochromic colors quartz is present in significant amounts particularly in the fine light sand fraction analysis of the quartz grains of the fine light sand by scanning electron microscope sem and backscattered electron images bse revealed the presence of significant physical and chemical alteration features such as fractures corrosion gulfs fields of etch pits and dissolution of intergranular surfaces this process is confirmed by electron microprobe analysis empa since the edges of the quartz grains have a higher proportion of cations other than si compared to their centre further evidence indicates the authigenic nature of the process starting from quartz etching an assessment of soil weathering has been made w index from marcelino et al 1999 the alteration of the quartz together with the development of a ultramicrofabric with several fabric units investigated with sem and other characteristics mineralogical chemical etc are considered indicative of some pedogenic evolution these facts are especially interesting in the case of weakly developed mediterranean mountain soils from sierra nevada where processes of chemical weathering have traditionally not been considered very active d 2003 elsevier b v all rights reserved

significance of atmospheric inputs of calcium over the southwestern mediterranean region high mountain lakes as tools for detection 1 we quantified dry and wet atmospheric deposition of calcium over the southwest mediterranean region and we assessed its impact on calcium dynamics of two high mountain lakes differing in morphometry and catchment characteristics atmospheric deposition of ca averaged 40 mmol m 2 yr 1 and it showed a seasonal pattern similar to that reported for saharan dust export to the mediterranean region with maxima during spring and summer ca enrichment from nonmarine sources was significantly related to the toms total ozone mapping spectrometer aerosol index atmospheric inputs significantly affected ca concentration of the selected lakes which do not presumably receive significant ca inputs from weathering the intensity of the effect depended on their corresponding sensitivities to evaporation total atmospheric inputs of ca to each study lake catchment 11300 and 3100 moles were enough to explain the lake ca content 5400 and 111 moles respectively the results obtained in this study reveal that atmospheric inputs particularly saharan dust deposition may be a significant source of calcium to remote mountain lakes

triple oxygen isotope composition of leaf waters in mpala central kenya abstract variations in triple oxygen isotopes have been used in studies of atmospheric photochemistry global productivity and increasingly in studies of hydroclimate understanding the distribution of triple oxygen isotopes in plant waters is critical to studying the fluxes of oxygen isotopes between the atmosphere and hydrosphere in which plants play an important role in this paper we report triple oxygen isotope data for stem and leaf waters from mpala kenya and explore how 17 o the deviation from an expected relationship between o 17 o 16 and o 18 o 16 ratios in plant waters vary with respect to relative humidity and deuterium excess d excess we observe significant variation in 17 o among waters in leaves and stems from a single plant up to 0 16 range in 17 o in leaf water in a plant over the course of a signal day which correlates to changes in relative humidity a steady state model for evaporation in leaf water reproduces the majority of variation in 17 o and d excess we observed in leaf waters except for samples that were collected in the morning when relative humidity is high and the degree of fractionation in the system is minimal the data and the steady state model indicate that the slope transp that links 17 o and 18 o values of stem and leaf waters and characterizes the fractionation during transpiration is strongly influenced by the isotopic composition of ambient vapor when relative humidity is high we observe a strong positive relationship between d excess and 17 o with a slope 2 2 0 2 per meg 1 which is consistent with the observed relationship in tropical rainfall and in water in an evaporating open pan the strong linear relationship between d excess and 17 o should be typical for any process involving evaporation or any other fractionation that is governed by kinetic effects

variations in terrigenous dilution in western mediterranean sea pelagic sediments in response to climate change during the last glacial cycle hemipelagic intervals in four giant calypso piston cores from the balearic abyssal plain western mediterranean sea were studied in order to determine fluctuations in the supply of terrigenous sediments to the basin during the last 130 000 years and possible climatic modulation of terrigenous sediment and particle flux carbonate records from hemipelagic intervals in these cores display distinct atlantic type cycles where glacial periods show on average 20 lower calcium carbonate contents than interglacial period equivalents the decrease in calcium carbonate seen during glacials may be the result of increased dilution by terrigenous aeolian and fluvial particles derived from aeolian and or fluvial sources higher glacial aeolian particle fluxes to the western mediterranean sea may have been caused by changes in the prevailing atmospheric conditions resulting in drier and colder climatic conditions in the source areas and more frequent and intense outbreaks of dust transport the colder and drier climatic conditions in combination with a lowered sea level would allow rivers to dump their sediment load closer to the shelf edge promoting enhanced fluvial input into the basin besides significant calcium carbonate variations that correlate with glacial interglacial cycles several short term abrupt changes in the calcium carbonate content are recorded which appear coincident with enhanced magnetic susceptibility values especially the events within marine isotope stage mis 3 the timing of these short term events may be linked with cooling events in the north atlantic particularly heinrich events and cold events within mis 5 these short term trends may possibly be explained by increased terrigenous particle transport due to drier and colder climate in the mediterranean borderlands our results further show that about 90 of the sedimentary sequence of the balearic abyssal plain consists of turbidites generally these appear not to have caused significant erosion and an almost complete continuous time stratigraphy is present in the intercalated hemipelagic intervals

the 7 13 march 2006 major saharan outbreak multiproxy characterization of mineral dust deposited on the west african margin mineral dust deposits were collected at mbour senegal throughout the spring of 2006 and especially during the well documented march 7 13 large saharan dust outbreak during this 7 day period significant changes in mass flux grain size clay mineralogy and sr and nd isotopic compositions were recorded indicating distinct provenances for the dust transported and deposited during and outside the event all these terrigenous proxies as well as freshwater diatom taxa also showed significant temporal variations during the outbreak implying contributions from at least two different provenance regions tri dimensional back trajectories and satellite imaging enabled us to link those distinct signatures to regions increasingly to the southeast within a large area covering mauritania mali and southern algeria identified by the total ozone mapping spectrometer toms as the main source of the prominent winter spring plume over the tropical atlantic the multiproxy characterization of the march 7 13 dust fall therefore enables us to typify the terrigenous signature of two different regions supplying dust off west africa and provide valuable clues for the interpretation of northeastern tropical atlantic ocean dust sedimentary records in terms of changes in provenance regions and transport systems additionally because dust deposition data are scarce flux and grain size data obtained in this study among other parameters such as clay assemblages provide important constraints for atmospheric transport models and dust deposition budget estimates in this area

combined measurements of 17oexcess and d excess in african monsoon precipitation implications for evaluating convective parameterizations water stable isotopes d18o dd are useful tools to depict and to understand the atmospheric water cycle in tropical regions they record the variations of convective activity and their implementation in convection schemes brings constraints on our understanding and parameterization of this phenomena here we present for the first time measurements of a new isotopic marker of the hydrological cycle 17oexcess resulting from the combination of d17o and d18o of water in convective regions on two different time scales i during the african monsoon onset and intra seasonal variability banizoumbou 2006 and ii during the squall line of the 11th of august 2006 niamey 17oexcess responds to the monsoon onset by a 30 per meg increase as well as to different convective processes in squall lines by 20 per meg variations these variations parallel those of d excess at first order and display significant correlation with relative humidity in the lower troposphere still higher correlation coefficients are observed between d excess and relative humidity than between 17oexcess and relative humidity suggesting a higher influence of relative humidity on d excess than on 17oexcess using a simple reevaporation model and a more sophisticated 2d model of a squall line we show that reevaporation is the process explaining the increase of d excess and 17oexcess with relative humidity for these two studies we also show that the combination of 17oexcess and d excess is a powerful tool to constrain the representation of isotopic processes during rain reevaporation in turn a good representation of such processes enables to use water isotopes to evaluate convective parameterization in atmospheric models 2010 elsevier b v

a three year time series of mineral dust deposits on the west african margin sedimentological and geochemical signatures and implications for interpretation of marine paleo dust records keywords saharan dust deposition flux grain size clay mineralogy sr and nd isotopes amma program a b s t r a c t mineral dust deposits in the northeastern tropical atlantic ocean netao are an important contribution for reconstructing paleoenvironments and paleoclimates of west africa however the interpretation of the changes in the sedimentological and geochemical characteristics of the dust deposits recorded in the marine sediments from the netao remains incomplete in order to improve our understanding of dust proxies in particular its mineralogical and geochemical provenance tracers present day dust deposition has been monitored at mbour 80 km south of dakar on the senegalese margin here we report a multi proxy investigation of a unique three year continuous time series of mineral dust deposits collected at a weekly or better temporal resolution over the march 2006 march 2009 period mass deposition flux and mean modal grain size display marked but reverse seasonal features with higher flux during the winter spring seasons and coarser grain size mode in summer when flux is minimal reflecting contrasting transport patterns throughout the year similarly clay mineralogy the illite kaolinite ratio in particular shows seasonal fluctuations manifesting the latitudinal displacement of the contributing domains of provenance in response to the seasonal migration of the itcz position and the associated wind systems our three year record also reveals the occurrence of major deposition events superimposed on the seasonal pattern generally during the winter spring dry seasons and most frequently during the month of march our study shows that these major events which contribute a large fraction of the total annual deposition flux all originate from the western sahara sahel a major area of emission in the region beside the bodele depression stretching from the mauritanian and western saharan coasts to the hoggar mountains combined with air mass tri dimensional back trajectories and satellite images the mineralogical and sr nd isotopic compositions of these large dust events enable us to identify several mineralogically and geochemically distinct provenance sectors within this vast western area unlike the background dust deposits the 87 sr 86 sr and the e nd isotopic signatures of the major dry events closely match that of the netao late holocene sediments supporting the hypothesis that these events account for most of the aeolian terrigenous supply reaching the ocean floor although this database needs to be expanded our results already provide useful constraints for the interpretation of the dust proxies variations in marine sedimentary archives off mauritania senegal in terms of changes in wind regimes and aridity over west africa

triple isotope δd δ17o δ18o study on precipitation drip water and speleothem fluid inclusions for a western central european cave nw switzerland abstract deuterium d and oxygen 18o isotopes are powerful tracers of the hydrological cycle and have been extensively used for paleoclimate reconstructions as they can provide information on past precipitation temperature and atmospheric circulation more recently the use of 17oexcess derived from precise measurement of 17o and 18o gives new and additional insights in tracing the hydrological cycle whereas uncertainties surround this proxy however 17oexcess could provide additional information on the atmospheric conditions at the moisture source as well as about fractionations associated with transport and site processes in this paper we trace water stable isotopes d 17o and 18o along their path from precipitation to cave drip water and finally to speleothem fluid inclusions for milandre cave in northwestern switzerland a two year long daily resolved precipitation isotope record close to the cave site is compared to collected cave drip water 3 months average resolution and fluid inclusions of modern and holocene stalagmites amount weighted mean d 18o and 17o are 71 0 9 9 5 2 for precipitation 60 3 8 7 4 6 for cave drip water and 61 3 8 3 4 7 for recent fluid inclusions respectively second order parameters have also been derived in precipitation and drip water and present similar values with 18 per meg for 17oexcess whereas d excess is 1 5 more negative in drip water furthermore the atmospheric signal is shifted towards enriched values in the drip water and fluid inclusions of 10 for d the isotopic composition of cave drip water exhibits a weak seasonal signal which is shifted by around 8 10 months groundwater residence time when compared to the precipitation moreover we carried out the first 17o measurement in speleothem fluid inclusions as well as the first comparison of the 17o behaviour from the meteoric water to the fluid inclusions entrapment in speleothems this study on precipitation drip water and fluid inclusions will be used as a speleothem proxy calibration for milandre cave in order to reconstruct paleotemperatures and moisture source variations for western central europe

biostratigraphy and palaeobiogeography of lower permian lower kungurian conodonts from the tak fa formation saraburi limestone thailand abstract lower permian lower kungurian conodonts are reported from the indochina block of southeast asia the fauna from the tak fa formation of the saraburi limestone group exposed in limestone hills nnw of khok samrong thailand includes sweetognathus subsymmetricus wang ritter and clark early forms and pseudosweetognathus costatus wang ritter and clark the co occurrence of these species indicates a lower permian age upper half of the lower kungurian for the sampled limestones representative of the mesogondolella siciliensis s subsymmetricus zone of south china sweetognathus and pseudosweetognathus are for the first time reported from the indochina terrane located in the palaeoequatorial belt in the kungurian pseudosweetognathus appears restricted to the kungurian of the south china and indochina terranes thus supporting palaeogeographic reconstructions that isolate these terranes within the palaeo tethys during the kungurian

the role of african dust in the formation of quaternary soils on mallorca spain and implications for the genesis of red mediterranean soils abstract african dust additions explain the origin of terra rossa soils that are common on the carbonate platform island of mallorca spain mineralogical and geochemical analyses indicate that quaternary carbonate eolianites on mallorca have a very high purity usually composed of more than 90 carbonate minerals calcite dolomite and aragonite in contrast terra rossa soils developed on these eolianites have lower carbonate contents and contain higher concentrations of quartz and other silicates analyses of immobile trace elements indicate that the non carbonate fractions of the eolianites have distinctive zr hf la yb cr sc and th ta values that differ from the superjacent terra rossa soils these observations indicate that even if sufficient dissolution of the eolianite had taken place to create the soils by residual accumulation immobile element ratios in the soils require an external source however zr hf la yb cr sc and th ta values in the soils fall within the range of values for these element ratios in african dust collected on barbados and mainland spain we conclude that the silicate fractions of terra rossa soils on mallorca are derived mainly though not wholly from far traveled african dust and this process may explain the origin of other terra rossa soils found in southern europe

record of δ18o and 17o excess in ice from vostok antarctica during the last 150 000 years 1 we measured 17 o and 18 o in recent antarctic snow and down the vostok ice core and calculated the excess of 17 o with respect to vsmow the magnitude of the 17 o excess in the holocene and the last interglacial is 45 per meg and it remains constant in a transect from the coast to the continental interior analysis of the transect data shows that the 17 o excess is not sensitive to temperature variations over the continent there are significant shifts in 70 excess from low values in glacial to high values in interglacial times the observed shifts suggest higher normalized relative humidity and or wind speeds over the source oceanic regions in glacial times

permian artinskian to wuchapingian conodont biostratigraphy in the tieqiao section laibin area south china permian strata from the tieqiao section jiangnan basin south china contain several distinctive conodont assemblages early permian cisuralian assemblages are dominated by the genera sweetognathus pseudosweetognathus and hindeodus with rare neostreptognathodus and gullodus gondolellids are absent until the end of the kungurian stage in contrast to many parts of the world where gondolellids and neostreptognathodus are the dominant kungurian conodonts a conodont changeover is seen at tieqiao and coincided with a rise of sea level in the late kungurian to the early roadian the previously dominant sweetognathids were replaced by mesogondolellids the middle and late permian guadalupian and lopingian series witnessed dominance of gondolellids jinogondolella and clarkina the common presence of hindeodus and decimation of sweetognathus twenty main and seven subordinate conodont zones are recognised at tieqiao spanning the lower artinskian to the middle wuchiapingian stage the main first appearance datum zones are in ascending order by stage the sweetognathus sw whitei sw toriyamai and sw asymmetrica n sp zones for the artinskian the neostreptognathodus prayi sw guizhouensis sw iranicus sw adjunctus sw subsymmeticus and sw hanzhongensis zones for the kungurian the jinogondolella j nankingensis zone for the roadian the j aserrata zone for the wordian the j postserrata j shannoni j altudaensis j prexuanhanensis j xuanhanensis j granti and clarkina c hongshuiensis zones for the capitanian and the c postbitteri zone and c transcaucasica zone for the base and middle of the wuchiapingian the subordinate interval zones are the pseudosweetognathus ps costatus ps monocornus hindeodus h gulloides pseudohindeodus ramovsi gullodus g sicilianus g duani and h excavates zones in addition three new species gullodus tieqiaoensis n sp pseudohindeodus elliptica n sp and sweetognathus asymmetrica n sp are described age assignments for less common species e g g duani h catalanoi and pseudosweetognathus monocornus etc are reassessed based on a rich conodont collection

airborne dust transport to the eastern pacific ocean off southern california evidence from san clemente island 1 islands are natural dust traps and san clemente island california is a good example soils on marine terraces cut into miocene andesite on this island are clay rich vertisols or alfisols with vertic properties these soils are overlain by silt rich mantles 5 20 cm thick that contrast sharply with the underlying clay rich subsoils the silt mantles have a mineralogy that is distinct from the island bedrock silt mantles are rich in quartz which is rare in the island andesite the clay fraction of the silt mantles is dominated by mica also absent from local andesite and contrasts with the subsoils dominated by smectite ternary plots of immobile trace elements sc th la and ta nd cr show that the island andesite has a composition intermediate between average upper continental crust and average oceanic crust in contrast the silt and to a lesser extent clay fractions of the silt mantles have compositions closer to average upper continental crust the silt mantles have particle size distributions similar to loess and mojave desert dust but are coarser than long range transported asian dust we infer from these observations that the silt mantles are derived from airborne dust from the north american mainland probably river valleys in the coastal mountains of southern california and or the mojave desert although average winds are from the northwest in coastal california easterly winds occur numerous times of the year when santa ana conditions prevail caused by a high pressure cell centered over the great basin examination of satellite imagery shows that easterly santa ana winds carry abundant dust to the eastern pacific ocean and the california channel islands airborne dust from mainland north america may be an important component of the offshore sediment budget in the easternmost pacific ocean a finding of potential biogeochemical and climatic significance

characterisation of the input signal to aquifers in the french basque country emphasis on parameters influencing the chemical and isotopic composition of recharge waters summary a hydrochemical and isotopic survey of rainwater and groundwater has been carried out during almost two years on the ursuya mount in the northern basque country southwestern france with the aim of enhancing the understanding of the behaviour of this aquifer and more peculiarly the recharge mode of groundwater the input signal of this aquifer is defined thanks to 112 rainwater samples the computed meteoric water line d 7 3 18 o 5 1 r 0 96 is consistent with that defined in the european iaea wmo network stations the weighted mean deuterium excess about 9 7 is really close to the value obtained for atlantic precipitations and clearly demonstrates an oceanic major origin the computations conducted on the chemical dataset show that the rainwater composition is controlled by four major factors 1 a mixed source of anthropogenic pollution and crustal material 2 a marine source 3 an urban source 4 an acid source further the quantification of neutralizing potentials clearly revealed below cloud processes in which crustal and anthropogenic components are responsible for the neutralization of anions besides the major atlantic origin of the recharge water the chemical and isotopic content of the samples coupled with the corresponding air mass back trajectories revealed four major geographical origins of the components 1 northwestern part of atlantic ocean and 2 southwestern part of atlantic ocean the oceanic influence in airmasses from these origins is highlighted by the stable isotopic content weighted mean close to the atlantic ocean signature and by the chemical concentrations dominated by sea salt elements 3 northern europe with a continental influence shown by a light depletion on isotopic signal besides purely oceanic origin and a higher concentration of crustal and anthropogenic components 4 southeastern area southeastern europe northern africa and mediterranean sea with an isotopic signature consistent with the mediterranean one and a chemical composition clearly influenced by the industrial activities of this region the dataset is confronted with the chemical and isotopic characteristics of groundwater in order to assess the recharge water signature of the aquifer of the ursuya mount the groundwater isotopic signal is close to the defined lmwl showing actual and local recharge nevertheless a slightly difference is observed between the mean value of stable isotopic content in groundwater and in rainwater the slightly depleted values of groundwater besides rainwater can be attributed to a preferential winter autumn recharge an altitudinal gradient about 0 11 18 o 100 m is defined and both water rock interactions and physicochemical processes fingerprint on the groundwater composition are characterised

variations of 17o 16o and 18o 16o in meteoric waters the variations of d 17 o and d 18 o in recent meteoric waters and in ice cores have proven to be an important tool for investigating the present and past hydrologic cycle in order to close significant information gaps in the present distribution ofd 17 o and d 18 o of meteoric water we have run precise measurements with respect to vsmow on samples distributed globally from low to high latitudes based on the new and existing data we present the global meteoric water line gmwl ford 17 o andd 18 o as ln d 17 o 1 0 528 ln d 18 o 1 0 000033 r 2 0 99999 in addition to meteoric water we carried out the first measurements of seawater from the pacific and atlantic oceans with respect to vsmow the obtained results show that the slope of the trend line ln d 17 o 1 vs ln d 18 o 1 of seawater samples is 0 528 the same as for meteoric water but the regression intercept is 5 per meg thus the positive intercept in the gmwl indicates an excess of 17 o in meteoric waters with respect to the ocean an excess or depletion of 17 o in water is defined as 17 o excess ln d 17 o 1 0 528 d 18 o 1 most meteoric water samples have positive 17 o excess of varying magnitudes with an average of 37 per meg with respect to vsmow we explain how these positive values originate from evaporation of sea water into marine air which is undersaturated in water vapor and how subsequent increase of 17 o excess occurs when atmospheric vapor condenses to form liquid and solid precipitation we also clarify the effect of excessive evaporation on 17 o excess finally based on the new results on 17 o excess of seawater we recalculated the relationship of d 17 o vs d 18 o in vapor diffusion in air as 18 adiff 1 0096

saharan dust on fuerteventura island canaries chemical and mineralogical characteristics air mass trajectories and probable sources from april 12 to 19 1984 dust was collected by cascade impactor on fuerteventura island 100 km from the saharan coast the samples were analyzed by x ray fluorescence spectrometry elemental composition by x ray diffraction mineral constituents and by scanning electron microscope sem and energy dispersive x ray analyzer edxa examination shape surface features and mineralogy of particles with the aim of determining the possible source areas of the dust on the scale of dust clouds another method allowed us to define the displacements of the dust using remote sensing meteosat ii national oceanic and atmospheric administration noaa and computing trajectories for any starting or ending point at any time these various methods gave complementary results and pointed out two successive episodes of dust with two different continental origins the first originated from a nearby source in the souss plain southern morocco and was characterized by very fine quartz particles the second drifted above more remote calcareous regions this study allows us to show how different methods can be used to characterize dust and to find the source areas the results suggest some general questions about the occurrence of coarse particles in the atmosphere and their role in the atmospheric deposition flux budget

the permian of timor stratigraphy palaeontology and palaeogeography the permian of timor in the lesser sunda islands has attracted the attention of palaeontologists since the middle of the nineteenth century because of the richness diversity and excellent state of preservation of its fauna these abundant fossil data have been compiled and updated for the present account the permian rocks of timor were deposited on the northern margin of australia at the present time the northern margin of australia in the region of timor is involved in a continent arc collision where australia is colliding with the banda arcs as a result of this collision permian rocks of the australian margin have been disrupted by folding and faulting with the generation of mud matrix melange and uplifted to form part of the island of timor due to this tectonic disruption it has proved difficult to establish a reliable stratigraphy for the permian units on timor especially as the classic fossil collections were obtained largely from the melange or purchased from the local people and do not have adequate stratigraphic control detailed systematic structural stratigraphic and sedimentological studies since the 1960s have provided a firmer stratigraphic and palaeogeographic background for reconsideration of the significance of the classic fossil collections permian rocks on timor belong either to a volcanic carbonate sequence maubisse formation or to a clastic sequence atahoc and cribas formations in which volcanics are less prominent the permian sequences were deposited on australian continental basement which was undergoing extension with spasmodic volcanic activity carbonates of the maubisse formation were deposited on horst blocks and volcanic edifices while clastic sediments of the atahoc and cribas formations were deposited in grabens the clastic sediments are predominantly fine grained derived from a distant siliciclastic source and are interbedded with sediments derived from the volcanics and carbonates of adjacent horst blocks bottom conditions in the graben were often anoxic in the present account events on timor during the permian are related to the regional tectonic context with the northward movement of australia leading to the amelioration of the climate from sub glacial to sub tropical together with the separation of crustal blocks from the northern australian margin to form the meso tethys

the influence of local sources on the mineral content of bulk deposition over an altitudinal gradient in the filabres range se spain mineralogical characteristics of bulk deposition have been determined at seven sites along an altitudinal gradient in the southern face of filabres range from 1770 m altitude to sea level over a period of 8 months the rainiest in this semiarid area x ray diffraction and scanning electron microscopy were used for identifying and semiquantifying minerals the aim was twofold to ascertain the contribution of mineral particles to both the high ph and alkalinity of bulk deposition the highest in europe and to use mineralogy of bulk deposition as a possible fingerprinting technique to identify the source of insoluble particles the ph alkalinity and electrical conductivity of rainwater increase down the altitudinal gradient as precipitation decreases indicating a clear increase in alkaline particles in agreement with the presence of calcite aragonite dolomite and gypsum which also explains high ph and alkalinity of the bulk deposition moreover ph and conductivity of rainwater are somewhat more related to e se winds than to w nw ones in addition to carbonates and gypsum seven silicate minerals were found some minerals like feldspars chlorite and aragonite are neither related to site nor to rain events some others like quartz high crystalline illite paragonite and kaolinite are only related to rain events finally a few minerals like low crystalline illite palygorskite paragonite and to some extent calcite and gypsum are site related some minerals have been interpreted to come from local sources e g high crystalline illite gypsum and paragonite others like palygorskite and low crystalline illite smaller in size may come from distant sources

mineralogical composition of african dust delivered by red rains over northeastern spain the african dust deposition mineralogy source regions and influence on rain chemistry were analyzed for a site in the montseny mountains catalonia northeastern spain for the period august 1 1983 through august 1 1994 dust deposition was highly variable two events collected on november 9 11 1984 and march 22 25 1991 accounted for 62 of the total dust input in the 38 red rain events recorded in the period the average annual dust deposition was 5 3 g m 2 se 2 6 three source regions in the african continent were identified with back trajectory analysis 1 western sahara 2 moroccan atlas and 3 central algeria events from the moroccan atlas predominated in terms of number of events amount of rainfall and dust deposition the meteorological situations during red rains were identified western sahara events occurred principally with a depression at high latitudes 50 n forming a trough in the north atlantic moroccan atlas events occurred with a depression in front of portugal and events from central algeria were associated with a depression over spain or north africa by order of abundance median of n 13 the minerals identified in the dust by x ray diffraction were as follows illite quartz smectite palygorskite kaolinite calcite dolomite feldspars differences in mineralogy between source regions were significant for smectite kaolinite quartz and dolomite smectite and kaolinite content was highest in the algerian events while quartz and dolomite content was lowest events from the moroccan atlas had the lowest smectite and kaolinite the red rain soluble chemistry was clearly influenced by the dissolution of calcite high alkalinity calcium concentration and basic ph and by marine components high na cl arid mg 2 concentrations because of the very alkaline character of red rains they had a strong weight on the annual mean ph of rainwater this was reflected by the significant relationship r 0 71 p 0 01 between the percentage of annual precipitation as red rain and annual mean precipitation ph red rains provided 25 45 of the annual dissolved input of the major ions in precipitation and 34 of the calcium required for holm oak quercus ilex l forest growth at the study site

bulk and single particle mineralogy of asian dust and a comparison with its source soils 1 the mineralogical properties of asian dust have been examined in detail and the results have been compared with the chinese source soils using high resolution scanning electron microscopy transmission electron microscopy x ray diffraction and chemical analysis mineralogical classification of asian dust particles showed that the most common single particles were clay aggregates 48 that were often mixed with nanosized calcite followed by particles of quartz 22 plagioclase 11 coarse calcite 6 k feldspar 5 muscovite chlorite kaolinite amphibole gypsum fe and ti oxides which were either partly or entirely attached with clay size mineral grains the clay minerals in asian dust were mostly illite and interstratified illite smectite the average mineral composition of the bulk dust samples by x ray diffraction was quartz 28 plagioclase 11 k feldspar 8 calcite 8 illite 19 interstratified illite smectite 22 chlorite 2 smectite 1 and kaolinite 1 in the silty soils from the source regions the clay minerals and nanosized pedogenic calcite aggregated and covered silt size minerals while the sands were mostly composed of quartz and feldspars and were lined with clay minerals the mineralogy of asian dust was similar to that of the silty soil from the loess plateau but the total phyllosilicate content increased from desert sands 7 silty soil 23 to asian dust 45 fining eastward the optical properties of asian dust and its interaction with atmospheric gases and cloud are probably affected by the clay rich mineral composition the aggregation and attachment of the clay minerals on the coarser minerals and the nanosized calcite

cisuralian guadalupian conodont sequence from the shaiwa section ziyun guizhou south china abstract a sequence of successive conodont datums and zones for the cisuralian and guadalupian series for the south china region of the equatorial warm water province is proposed based on the shaiwa section ziyun guizhou the seven conodont zones in ascending order are sweetognathus aff whitei zone of artinskian stage a set of three new kungurian zones of sweetognathus guizhouensis zone sweetognathus subsymmetricus zone mesogondolella nashuiensis zone the mesogondolella idahoensis lamberti zone of uppermost kungurian the guadalupian zones of jinogondolella aserrata followed by jinogondolella postserrata the base of the kungurian stage is tentatively defined by the first occurrence of s guizhouensis 174 5 m above the base of the sidazhai formation this suite of conodont datums and zones will help to improve the global correlations of permian strata of the kungurian stage

progress problems and prospects an overview of the guadalupian series of south china and north america abstract the guadalupian epoch is marked by the formation of the pangean supercontinent global sea level change rifting and drifting of the cimmerian continents formation of large igneous provinces and dramatic biotic changes a high resolution biostratigraphic chemostratigraphic and high precision geochronologic framework of this critical transition is fundamental to understanding these events extensive studies of the latest cisuralian and guadalupian series in both south china and north america reveal the same conodont lineages but the conodont interval zones based on jinogondolella within the guadalupian series are slightly diachronous high precision u pb geochronological studies ca id tims method calibrate the base of the guadalupian series base roadian at 273 01 0 14 ma a previously reported age from an ash bed overlying the emeishan flood basalts 259 51 0 21 ma is adopted for the guadalupian lopingian boundary glb based on recently published geochronology and bayesian age modeling from the guadalupian series the base of the capitanian is constrained at 264 28 0 16 ma and the base of the wordian is interpolated to be 266 9 0 4 ma the illawarra reversal is of early middle wordian age both north america and south china possess a distinct negative 13ccarb excursion of 3 5 at the latest kungurian and early roadian lk er cie which coincides with the early stages of a significant 3rd order sea level rise the large end guadalupian 13ccarb negative excursion may have been affected by post depositional diagenesis or a warming event associated with the emeishan volcanism the 87sr 86sr ratios in both regions declined from the latest kungurian to the late capitanian but have different ratios and reveal several fluctuations in the middle guadalupian measured 18oapatite values suggest that the delaware basin was 3 4 c cooler than the eastern yangtze block analysis of a new high resolution database of marine taxa indicates only a minor pre lopingian diversity drop from 261 04 ma to 259 98 ma which coincides with the peak emeishan volcanism the widely perceived end guadalupian mass extinction in north america is evidently masked by and possibly an artefact of a stratigraphic truncation effect due to rapid lithofacies changes from limestone to laminated evaporites with the closure of the west texas basins

hafnium and neodymium isotopes in surface waters of the eastern atlantic ocean implications for sources and inputs of trace metals to the ocean we present hafnium hf and neodymium nd isotopic compositions and concentrations in surface waters of the eastern atlantic ocean between the coast of spain and south africa these data are complemented by hf and nd isotopic and concentration data as well as rare earth element ree concentrations in saharan dust hafnium concentrations range between a maximum of 0 52 pmol kg in the area of the canary islands and a minimum value of 0 08 pmol kg in the southern angola basin neodymium concentrations also show a local maximum in the area of the canary islands 26 pmol kg but are even higher between 20n and 4n reaching maximum concentrations of 35 pmol kg these elevated concentrations provide evidence of inputs from weathering of the canary islands and from the partial dissolution of dust from the sahara sahel region the inputs from ocean island weathering are also reflected in radiogenic hf and nd isotopes the hf isotopic compositions of dust samples themselves are highly variable ranging between ehf 20 and 0 6 the combined hf and nd isotopic compositions of dust plot close to the terrestrial array during periods of appreciable dust load in the atmosphere during low atmospheric dust loading combined hf and nd isotopic compositions similar to seawater are observed most of the variability can be explained in terms of variable degrees of zircon loss from the dust samples which in turn is linked to sorting during atmospheric transport to the eastern atlantic ocean and possibly presorting by sedimentary redistribution on the continent in addition increasing relative proportions of radiogenic clay minerals with decreasing grain size may contribute to the radiogenic hf isotopic compositions observed while the nd isotopic composition in the surface ocean reflects the nd isotopic composition of the saharan dust adjacent to the sahara sahel region the release of hf from that dust appears to be incongruent and results in surface ocean hf isotopic compositions which are 10 ehf more radiogenic than the bulk dust radiogenic hf appears to be released from clays and possibly from trace apatite rare earth element patterns of dust samples indicate the presence of apatite but provide no evidence for ferromanganese grain coatings suggesting that such coatings are insignificant in the release of hf and nd from saharan dust to the surface ocean the nd isotopic composition of the surface waters becomes less radiogenic south of the equator most likely reflecting the release of nd from congo river sediments the release of hf from saharan dust and the congo river sediments however does not produce distinct hf isotopic signatures in the surface ocean implying that the mobile fraction of hf integrated over large continental areas is isotopically uniform the hf isotopic uniformity in the surface ocean means that the limited variability in deep water isotopic compositions is consistent with a short deep water residence time and reflects homogenous continental inputs rather than efficient deep water homogenization

stretching the envelope of past surface environments neoproterozoic glacial lakes from svalbard the oxygen isotope composition of terrestrial sulfate is affected measurably by many earth surface processes during the neoproterozoic severe snowball glaciations would have had an extreme impact on the biosphere and the atmosphere here we report that sulfate extracted from carbonate lenses within a neoproterozoic glacial diamictite suite from svalbard with an age of similar to 635 million years ago falls well outside the currently known natural range of triple oxygen isotope compositions and indicates that the atmosphere had either an exceptionally high atmospheric carbon dioxide concentration or an utterly unfamiliar oxygen cycle during deposition of the diamictites

response of iberian margin sediments to orbital and suborbital forcing over the past 420 ka here we report 420 kyr long records of sediment geochemical and color variations from the southwestern iberian margin we synchronized the iberian margin sediment record to antarctic ice cores and speleothem records on millennial time scales and investigated the phase responses relative to orbital forcing of multiple proxy records available from these cores iberian margin sediments contain strong precession power sediment redness a and 570 560 nm and the ratio of long chain alcohols to n alkanes c26oh c26oh c29 are highly coherent and in phase with precession redder layers and more oxidizing conditions low alcohol ratio occur near precession minima summer insolation maxima we suggest these proxies respond rapidly to low latitude insolation forcing by wind driven processes e g dust transport upwelling precipitation most iberian margin sediment parameters lag obliquity maxima by 7 8 ka indicating a consistent linear response to insolation forcing at obliquity frequencies driven mainly by high latitude processes although the lengths of the time series are short 420 ka for detecting 100 kyr eccentricity cycles the phase relationships support those obtained by shackleton antarctic temperature and the iberian margin alcohol ratios c26oh c26oh c29 lead eccentricity maxima by 6 kyr with lower ratios increased oxygenation occurring at eccentricity maxima co2 ch4 and iberian sst are nearly in phase with eccentricity and minimum ice volume as inferred from pacific 18oseawater lags eccentricity maxima by 10 kyr the phase relationships derived in this study continue to support a potential role of the earth s carbon cycle in contributing to the 100 kyr cycle

lower middle triassic conodont biostratigraphy of the qingyan section guizhou province southwest china abstract the middle triassic qingyan formation at its type section the qingyan section of guizhou southwest china yields more than 300 species belonging to 17 fossil groups which mark the radiation of benthic organisms following the end permian mass extinction this study intends to establish a primary conodont biostratigraphical succession through the lower and middle triassic sequence at qingyan to provide a time framework for the understanding of the recovery and radiation process from the mass extinction a total of 30 species in 8 conodont genera are stratigraphically significant and assigned to the neospathodus dieneri neospathodus cristagalli neospathodus waageni neospathodus homeri chiosella timorensis and neogondolella cf bulgarica zones in ascending order most conodont zones correlate well with their counterparts recognized from elsewhere in china and even worldwide the first appearance of ns waageni marks the induan olenekian boundary which is placed at the lower middle part of the luolou formation 121 47 m above the permian triassic boundary the olenekian anisian early middle triassic boundary is here defined by the first occurrence of chiosella timorensis at the base of the qingyan formation although no conodonts retrieved from the upper qingyan formation containing the extraordinarily diverse biota i e the qingyan biota stratigraphical correlation with the neighbouring conodont bearing sections in guizhou and the ammonoid zones suggest that the qingyan biota has an age of early late anisian early middle triassic

connection between south mediterranean climate and north african atmospheric circulation during the last 50 000 yr bp north atlantic cold events abstract high resolution clay mineralogical analyses were performed on sediment deposited during the last 50 000 yr in the alboran sea odp site 976 the clay mineral record is compared with pollen assemblages and with annual precipitation pann and mean temperatures of the coldest month mtco reconstructed with the modern analog technique mat enhanced contribution of palygorskite a typical wind blown clay mineral characterizes the north atlantic cold climatic events coeval development of the semi arid vegetation artemisia rich associated with a drastic fall of reconstructed precipitations and temperatures suggest cold and arid continental conditions in the west mediterranean area during north atlantic cold events the clay mineral association especially the palygorskite content and the illite to kaolinite ratio indicate western morocco as one of the major source of the clay size fraction during the north atlantic cold events the maximum abundance of artemisia associated with the presence of argania pollen both indicate morocco as the main origin for pollen during these cold periods the comparison of these pollen and clay mineral specific features allows us to pinpoint western morocco as the dominant source of wind blown particles during north atlantic cold events these specific mineralogical composition and palynological assemblages reveal enhanced aridity over north africa and intensification of winds favouring dust erosion and transport from north africa toward the alboran sea during the north atlantic cold events according to atmospheric models such a meridian transport 1 likely results from the development of strong and stable anticyclonic conditions over the tropical atlantic and north africa similar to today s summer meteorological configuration and 2 implies a northward position of the westerly winds during north atlantic cold events finally the synoptic situation over the west mediterranean during the north atlantic cold events is compared with the north atlantic oscillation nao suggesting that during the cold atlantic events weather regimes over europe and north africa may have been systematically shifted towards a positive nao situation

contrasting environmental memories in relict soils on different parent rocks in the south western italian alps abstract soils on the alps are usually weakly developed both because of the extensive pleistocene glaciations and because of slope steepness and climate enhancing erosion however on some stable relict surfaces particularly in the outermost sections of the alpine range some highly developed soils are apparently in contrast with holocene soil forming conditions in this work we assess the extent of pedogenesis in some of these soils located under montane level vegetation in the ligurian alps sw piemonte italy and relate it to the effects of climate and parent material the considered well developed profiles showed signs of extremely different pedogenetic processes on the different lithotypes in particular podzols with extremely thick e horizons up to more than 2 m thick and very hard thick ortstein or placic horizons were formed on quartzite reddish terra rossa luvisols were formed on limestone red extremely acidic alisols were formed on shales the chemical properties the micromorphology and the clay mineralogy demonstrated high intensity pedogenic trends and were characteristic of processes usually occurring under different climates they may therefore represent excellent pedo signatures of different specific past climatic environmental conditions as a response of different lithologies to specific soil forming environments which range from warm and humid climates typical of red alisols and luvisols to cool and humid wet climates leading to the formation of podzols with ortstein placic horizons