multi scale variability of the sea surface temperature in the tropical atlantic 1 tropical atlantic ta sea surface temperature sst variability is studied using the continuous wavelet transform cwt of the sst indices in the tropical north atlantic tna tropical south atlantic tsa and equatorial atlantic eqa cwt of the difference index tnsd between the tna and tsa indices and the cross wavelet spectrum for the tna and tsa indices are also examined the analyses focus the short interannual interannual and decadal scales the global wavelet power of the tna tsa and eqa indices confirm previous findings on the dominant scales of the sst variability in different ta sectors the decadal peaks are dominant for the tna and tsa indices while the interannual peaks are significant only for the eqa index the scale averaged series for all scales feature a number of abrupt reversals of 180 which depends on the scale with larger number for smaller scales the during the period between two subsequent abrupt reversals remains close to 180 or varies within sub intervals of the 180 to 180 range thus the dipole like cross equatorial sst anomaly gradient monopole and equatorial patterns are established as evolving modes for all scales the periods of abrupt reversals of 180 occur within the periods with change in the meridional propagation directions of the sst anomalies or with reduced sst anomalies this result strongly suggests that the establishment of the sst anomaly patterns in the ta depends crucially on the meridional propagation of the sst anomalies this is a new aspect not discussed before

linking the 8 2 ka event and its freshwater forcing in the labrador sea 1 the 8 2 ka event was the last deglacial abrupt climate event a reduction in the atlantic meridional overturning circulation amoc attributed to the drainage of glacial lake agassiz may have caused the event but the freshwater signature of lake agassiz discharge has yet to be identified in 18o of foraminiferal calcite records from the labrador sea calling into question the connection between freshwater discharge to the north atlantic and amoc strength using mg ca paleothermometry we demonstrate that 3 c of near surface ocean cooling masked an 1 0 decrease in western labrador sea 18o of seawater concurrent with lake agassiz drainage comparison with north atlantic 18o of seawater records shows that the freshwater discharge was transported to regions of deep water formation where it could perturb amoc and force the 8 2 ka event

present day south american climate abstract this paper documents the main features of the climate and climate variability over south america on the basis of instrumental observations gathered during the 20th century it should provide a modern reference framework for paleoclimate research in south america targeting high resolution proxies over the past few centuries several datasets suitable for present day climate research are first described highlighting their advantages as well as their limitations we then provide a basic physical understanding of the mean annual cycle of the precipitation and atmospheric circulation over the continent and the adjacent oceans in particular the diversity of precipitation temperature and wind patterns is interpreted in terms of the long meridional extent of the continent and the disruption of the large scale circulation caused by the andes cordillera the contrasting oceanic boundary conditions and the landmass distribution similarly the intensity and timing of the interannual and interdecadal climatic fluctuations exhibit considerable geographical dependence as some regions are more influenced by large scale phenomena rooted in the tropical oceans while others are more influenced by high latitude phenomena the impact of these large scale phenomena over south america is documented by a regression analysis between selected atmospheric indices and the precipitation and temperature fields we have included a discussion on the seasonality and long term stability of such impacts and complemented our general description by an updated review of the literature on climate variability over specific regions

discriminating depositional environments of sands from modern source terranes using modal analysis abstract composition of modern beach dune and fluvial sands from the gulf of mexico coast and the kapiti and foxton coasts new zealand were compared in order to establish petrological criteria that discriminate between depositional environments and subenvironments the three areas were chosen because of their different sand compositions sand from the gulf of mexico is quartzofeldspathic to feldspatholithic sand from the kapiti coast sands is feldspatholithic and sand from the foxton is lithofeldspathic using a confidence level of 95 petrographic data were plotted as bar charts for each environment beach dune river and for each subenvironment inshore foreshore backshore of the beaches stoss crest lee face of eolian dunes upstream and mouths of the river the best discrimination of beach dune and river environments was achieved for the gulf of mexico sands using q f l and qm k p plots terranes with multiple source rock types such as the gulf of mexico enhance petrological discrimination between sands from beach dune and river subenvironments and environments in terranes with few rock source types such as the kapiti coast only the river sands can be discriminated from those of other environments the single rock source of the foxton coast allows little petrological discrimination between the beach dune and river sands this study examines compositional differences between beach dune and river subenvironments and environments and the degree to which these differences are dependent on the variation of rock types in the source terrane the study also shows the usefulness of q f l qm k p and lv lm ls bar charts the discrimination among beach dune and river sands is partly due to grain size variation

influence of vegetation on aeolian sand transport rate from a backshore to a foredune at hasaki japan the influence of vegetation on aeolian sediment transport rate in the region from a backshore to a foredune was investigated at the hasaki coast in japan where an onshore wind was predominant and the creeping beach grasses carex kobomugi and calystegia soldanella were major species the comparison of cross shore distributions of the cross shore component of aeolian sand transport rate with and without vegetation which were estimated on the basis of the beach profile changes and a mass conservation equation showed that the creeping grasses influenced the aeolian sand transport rate the landward aeolian sand transport rate rapidly decreased landward from the seaward limit of vegetation when the grasses grew the aeolian sand transport rate reduced by 95 with a vegetation cover of 28 on the other hand when the grasses were absent the landward aeolian sand transport rate did not decrease near the seaward vegetation limit but near the foot of the foredune

mid holocene climatic variability reconstruction from pollen records 32 52 s argentina abstract this study reviews 42 published pollen records to gain a better understanding of holocene climate variability especially of the past displacement and location of the arid semiarid region asr between 32 and 52 s in argentina at present the asr is delimited approximately between the 500 mm isohyet in the pampa region and the 300 mm isohyet in the andean sector south of 37 s represented by arid and semiarid climate types where precipitation can be as low as 200 mm mid holocene climatic variability affected the regional vegetation patterns and the borders of the asr paleoenvironmental reconstruction is based on comparison of fossil pollen records from different depositional environments maps of distribution patterns of plant formations are reconstructed at 2000 500 year intervals from 8000 to 4000 14 c years bp vegetation changes are mainly explained by changes in the position and the seasonal amplitude of latitudinal shifts of the pacific and atlantic anticyclones and of the westerlies from 8000 to 4000 bp the eastern limit of the asr was displaced eastward the western limit reached the maximum eastward displacement in the southern extreme of patagonia at 6000 years bp at this time at the center of asr shrub steppes and the monte developed suggesting maximum dry conditions and the establishment of the arid diagonal north of 42 s while the present day espinal dry pampa ecotone became established at 4000 years bp paleodata suggest a transitional stage towards the present situation of the asr

late quaternary paleosols stratigraphy and landscape evolution in the northern pampa argentina the field properties micromorphology grain size geochemistry and optically stimulated luminescence osl ages of two late quaternary sections have been used to reconstruct the sequence of pedosedimentary processes and to provide insights into landscape evolution in part of the northern pampa of argentina paleosols developed in paludal sediments adjacent to the parana river at baradero and in loess at lozada can both be correlated and linked to other sites thus enabling for the first time the tentative recognition and tracing of a diachronous soil stratigraphic unit that probably spans the equivalent of at least part of marine oxygen isotope stage ois 5 the paleosol at lozada was truncated and buried beneath fluvial sediments during the time span of ois 4 and 3 eolian gradually replaced paludal inputs at baradero over this period and there were also two clearly defined breaks in sedimentation and development of paleosols the period corresponding to ois 2 was marked by significant loess accumulation at both sites with accretion continuing into the mid holocene only at lozada the more developed nature of the surface soil at baradero probably reflects a combination of a moister climate and a longer soil forming interval

tropical oceanic causes of interannual to multidecadal precipitation variability in southeast south america over the past century abstract observations atmosphere models forced by historical ssts and idealized simulations are used to determine the causes and mechanisms of interannual to multidecadal precipitation anomalies over southeast south america sesa since 1901 about 40 of sesa precipitation variability over this period can be accounted for by global sst forcing both the tropical pacific and atlantic oceans share the driving of sesa precipitation with the latter contributing the most on multidecadal time scales and explaining a wetting trend from the early midcentury until the end of the last century cold tropical atlantic sst anomalies are shown to drive wet conditions in sesa the dynamics that link sesa precipitation to tropical atlantic sst anomalies are explored cold tropical atlantic sst anomalies force equatorward flowing upper tropospheric flow to the southeast of the tropical heating anomaly and the vorticity advection by this flow is balanced by vortex stretching and ascent which drives the increased prec

distribution of arsenic selenium and other trace elements in high pyrite appalachian coals evidence for multiple episodes of pyrite formation abstract pennsylvanian coals in the appalachian basin host pyrite that is locally enriched in potentially toxic trace elements such as as se hg pb and ni a comparison of pyrite rich coals from northwestern alabama eastern kentucky and west virginia reveals differences in concentrations and mode of occurrence of trace elements in pyrite pyrite occurs as framboids dendrites or in massive crystalline form in cell lumens or crosscutting veins metal concentrations in pyrite vary over all scales from microscopic to mine to regional because trace elements are inhomogeneously distributed in the different morphological forms of pyrite and in the multiple generations of sulfide mineral precipitates early diagenetic framboidal pyrite is usually depleted in as se and hg and enriched in pb and ni compared to other pyrite forms in dendritic pyrite maps of as distribution show a chemical gradient from as rich centers to as poor distal branches whereas se concentrations are highest at the distal edges of the branches massive crystalline pyrite that fills veins is composed of several generations of sulfide minerals pyrite in late stage veins commonly exhibits as rich growth zones indicating a probable epigenetic hydrothermal origin selenium is concentrated at the distal edges of veins a positive correlation of as and se in pyrite veins from kentucky coals and of as and hg in pyrite filled veins from alabama coals suggests coprecipitation of these elements from the same fluid in the kentucky coal samples n 18 as and se contents in pyrite filled veins average 4200 ppm and 200 ppm respectively in alabama coal samples as in pyrite filled veins averages 2700 ppm n 34 whereas as in pyrite filled cellular structures averages 6470 ppm n 35 in these same alabama samples se averages 80 ppm in pyrite filled veins but was below the detection limit in cell structures in samples of west virginia massive pyrite as averages 1700 ppm and se averages 270 ppm n 24 the highest concentration of hg 102 ppm is in alabama pyrite veins improved detailed descriptions of sulfide morphology sulfide mineral paragenesis and trace element concentration and distribution allow more informed predictions of 1 the relative rate of release of trace elements during weathering of pyrite in coals and 2 the relative effectiveness of various coal cleaning procedures of removing pyrite for example trace element rich pyrite has been shown to be more soluble than stoichiometric pyrite and fragile fine grained pyrite forms such as dendrites and framboids are more susceptible to dissolution and disaggregation but less amenable to removal during coal cleaning

palaeoclimates in central and south america since 18 000 bp based on pollen and lake level records abstract the last 18 ka of palaeoclimates are discussed at 3 ka intervals based on palaeoenvironmental changes shown in pollen and lake level records from central and south america a total of 61 pollen records fulfill the requirements of continuity and chronology to be used in this synthesis 8 records from tropical and subtropical lowlands in central and south america 7 records from the central american highlands 26 records from the high andes north and south of the equator 2 records from the southern subtropics and 18 from the southern andes and subantarctic islands palaeoclimatic interpretation of the pollen records is semiquantitative based on bioclimatic parameters such as e g elevational temperature gradients or latitudinal precipitation gradients that can be related to vegetation zonation additional palaeoclimatic information is obtained from lake level records derived either from dated shorelines or from the limnological history of lake sediment sections large scale palaeoclimatic comparison of the proxy data records indicates that full and late glacial climates throughout central and south america were cooler than today by about 4 to 5 c but that moisture patterns showed regional differentiation thus in both the southern subtropics and high latitudes in southern chile conditions were substantially moister than today during full and late glacial times whereas everywhere else conditions were far drier than today in terms of palaeocirculation this scenario can be interpreted as a poleward shift of the subtropical as well as the westerly circulation a scenario that has been suggested by palaeoclimatic simulations from general circulation models gcm another major palaeoclimatic aspect predicted by the gcm simulations is the suppressed early holocene summer monsoon in the southern subtropics although proxy records are few from this zone their palaeoenvironmental history during that time shows a period of aridity that would support the model one of the most controversial aspects of south american palaeoclimates concerns the existence of a younger dryas equivalent a cold period between 11 and 10 ka bp based on the existing data from south america that show a great diversity of palaeoclimatic trends the concept of an interval that is characterized by the same climatic signal as documented for the north atlantic seems too simplistic moreover at this point only very few records have been analysed in sufficient detail to yield unambiguous climatic information for the interval in question the principal outcome of this palaeoenvironmental and palaeoclimatic synthesis is the better understanding of the type and quality of data available at present and the realization of regions and periods where much more and concerted effort is needed to address problems of intra and interhemispheric palaeoclimatic correlations only then can questions concerning the mechanism of climatic change be tackled successfully

the east australian current and property transport at 27 s from 2012 to 2013 abstractthe east australian current eac is the complex and highly energetic poleward western boundary current of the south pacific ocean a full depth current meter and property temperature and salinity mooring array was deployed from the continental shelf to the abyssal waters off brisbane australia 27 s for 18 months from april 2012 to august 2013 the eac mooring array is an essential component of the australian integrated marine observing system imos during this period the eac was coherent with an eddy kinetic to mean kinetic energy ratio of less than 1 the 18 month mean poleward only mass transport above 2000 m is 22 1 7 5 sverdrups sv 1 sv 106 m3 s 1 the mean poleward only heat transport and flow weighted temperature above 2000 m are 1 35 0 42 pw and 15 33 c respectively a difference in the poleward only and net poleward mass and heat transports above 2000 m of 6 3 sv and 0 24 pw reflects the presence of an equatorward eac retroflection at the eastern offshore end of the

geomorphology and chronology of late quaternary dune fields of western argentina abstract stabilized dune fields are common in western argentina and potentially reflect drought variability in the late quaternary this study focussed on deciphering geomorphic and stratigraphic record of three vegetated dune fields from east to west san luis medanos negros and medanos grandes with a mean annual precipitation from 700 to 91 mm optically stimulated luminescence single aliquot regeneration protocols yield ages on eolian quartz grains constraining depositional events the san luis dune field the wettest area exhibits evidence for repeated activation during the last glaciation ca 33 20 ka generally coincident with regional loess deposition these dunes were locally reformed in the past 100 years which is apparently coincident with intensified agrarian use and drying in the late 19th and early 20th century the two driest and western most dune fields medanos negros and medanos grandes show reactivation at ca 2 5 ka 0 9 and 0 5 ka and ca 4 3 4 2 1 and 0 6 0 4 ka respectively eolian depositional events at ca 2 5 2 1 ka and 0 6 0 4 ka may be coeval for medanos grandes and negros dune fields sustained drought conditions conducive for eolian activity is associated with warmer sea surface temperatures in the south atlantic a weakened south american convergent zone and a dispersed and southeasterly flow of tropical moisture from the low level chaco jet this nascent analysis indicates drought variability beyond historic observations with potentially at least four dune reactivation events in the past ca 4 5 ka

the distribution of apparent dose as determined by optically stimulated luminescence in small aliquots of fluvial quartz implications for dating young sediments abstract we noted recently murray et al 1995 that quartz samples taken from in channel fluvial deposits have apparent doses ranging over several orders of magnitude we suggested that these dose distributions are best explained by a mixture of a small number of poorly bleached grains and a larger number of well bleached grains in this paper we examine the distribution of apparent dose in small aliquots each composed of 2000 grains of different particle size fractions 63 90 m 90 125 m 125 180 m 180 212 m 212 250 m diameter from two samples collected from the murrumbidgee river new south wales australia the samples are of known burial age the first being 70 years old and the second being its modern equivalent 0 2 gy the difference in the lowest apparent dose in the two samples is considered to be the result of their different burial times we suggest a method for dating recently deposited

paleoclimate controls on late paleozoic sedimentation and peat formation in the central appalachian basin u s a abstract in the central appalachian basin at least two major climate changes affected sedimentation during the late paleozoic stratigraphically these two changes are indicated by the distribution of coal beds the variation in coal quality and the variation in rock lithologies in latest mississippian or earliest pennsylvanian time the climate changed from dry seasonal tropical to ever wet equable tropical the equable climate prevailed into the middle pennsylvanian influencing the morphology and geochemistry in peat forming environments many of the peat deposits which formed under the equable climate were probably domed raised bogs low concentrations of dissolved solids in peat formation water resulted in low buffering capacity organic acids caused acidic ph another climate change occurred in late middle pennsylvanian time when evapopation periodically exceeded rainfall resulting in an increase of both dissolved solids and ph 4 to 7 in surface and near surface water throughout the remainder of the pennsylvanian the surfaces of peat deposits were probably planar not domed water in peat forming and other depositional environments became more nearly neutral the coal beds derived from these peats are highly variable in both ash and sulfur contents drier or more seasonal climates are also indicated by sequences of 1 calcareous sandstone and shale 2 nonmarine limestone that shows shallow water and subaerial exposure features and 3 calcareous paleosols that have caliche characteristics our data and observations indicate that physical depositional environment models for the origin of coal do not adequately explain variations in mineral matter content and composition in commercial quality coal beds in the central appalachian basin stratigraphic variation in mineral matter in coal beds and in syngenetic and early diagenetic minerals in rocks associated with the coal beds appears to be better explained by changes in geochemical conditions of nonmarine sedimentation paleoclimate was a principle control on these geochemical conditions

interhemispheric anti phasing of rainfall during the last glacial period abstract we have obtained a high resolution oxygen isotopic record of cave calcite from caverna botuvera 27 13 s 49 09 w southern brazil which covers most of the last 36 thousand years ka with an average resolution of a few to several decades the chronology was determined with 46 u th ages from two stalagmites tests for equilibrium conditions show that oxygen isotopic variations are primarily caused by climate change we interpret our record in terms of meteoric precipitation changes hence the variability of south american monsoon sam intensity the oxygen isotopic profile broadly follows local insolation changes and shows clear millennial scale variations during the last glacial period with amplitudes as large as 3 but with smaller centennial scale shifts 1 during the holocene the overall record is strikingly similar to but strongly anti correlated with a number of records from the northern hemisphere we compared our record to other precisely dated contemporaneous records from hulu cave eastern china minima in 18o wet periods intense sam at our site are synchronous with maxima in 18o dry periods weak east asian monsoon eam in eastern china within precise dating errors and vice versa this anti phased precipitation relationship between two low latitude locations may be interhemispheric in extent based on comparison with records from other sites precipitation anti phasing may be related to north south shifts in the mean position of the intertropical convergence zone itcz and asymmetry in hadley circulation in two hemispheres associated not with seasonal changes as observed today but with millennial scale climate shifts the millennial scale atmospheric see saw patterns that we observe could have important controls and feedbacks on climate within hemispheres because of water vapor s greenhouse properties

geochemistry of major and trace elements in permian coal with an emphasis on no 8 coal seam of zhuji coal mine huainan coalfield china a better understanding on geochemistry of elements in coal has both environmental and geological implications in this study 53 coal samples were collected from no 8 coal seam of the zhuji coal mine huainan coalfield the concentrations of 49 elements ash yield and total organic compound toc as well as mineralogical phases in coal were determined as compared with chinese the usa and world coals si k se cd sn sb and w in studied coal seam are higher whereas zn as and lu are lower the enrichment factor and concentration coefficient show that se cd sn sb and w are preferably enriched in studied coals the enrichment of se and cd is probably attributed to their higher proportions of organic forms most major and trace elements tend to concentrate in either the upper or lower sections of coal seams which suggest that depositional micro environment was important in controlling elements migration and enrichment the correlation analysis of elements with ash yield shows that the behavior of elements in coal follows the periodic change of metallic activity the modes of occurrence of major and trace elements are elaborated by statistical methods silicon is mainly in form of montmorillonite or presents as free quartz iron is associated with chlorite siderite lepidocrocite and other iron bearing minerals ti shows obviously organic association three groups of elements are divided in accordance with the cluster dendrogram group 1 sc hree be y v co cu p sr b sn se bi toc s ba as group 2 lree zn al mn li na th cr fe mg and group 3 ca mo si w ad ti pb k many trace elements including li sc v cr zn sr la ce nd sm eu gd tb lu pb bi and th correlate positively with al suggesting their occurrence mainly in clay such as kaolinite and chlorite ree in the studied coalfield was primarily supplied by terrestrial clastics coming from north china coal basin the differentiation of lree and hree is probably attributable to their different physicochemical characterisitcs and specific paleo sedimentary environment various indexes e g b content ash index c value and the existence of certain minerals suggest a reducing and anoxic sedimentary environment of coal swamp with a stable supply of terrigenous detrital materials in a moist environment the origins of enriched elements are primarily derived from the source rock sedimentary environment and thermally contact metamorphism or possibly magmatic hydrothermal fluids

procedures used for luminescence dating of sediments abstract an account of the procedures for thermoluminescence tl and optically stimulated luminescence osl dating of sediments used at the nordic laboratory for luminescence dating is given the topics discussed include sampling sample preparation separation of quartz and feldspars using heavy liquids dose rate estimation and methods for estimating the equivalent dose special attention is paid to the partial bleach tl technique of mejdahl 1988 which appears to give reliable results for partially bleached sediments optically stimulated luminescence dating using stimulation by infra red ir and green light has been taken up and especially added dose methods using stimulation by ir or green light have been tried with some success some sources of error are discussed including the adverse effect of shallow traps

paleoecological interpretation of a middle pennsylvanian coal bed in the central appalachian basin u s a abstract at least 180 small spore species assignable to 62 miospore genera have been identified from the middle pennsylvanian hernshaw coal bed in southern west virginia and its stratigraphic equivalent the fire clay coal bed in eastern kentucky the established natural affinities of a majority of these miospore taxa indicate that the hernshaw fire clay peat swamp supported a diverse flora consisting of arborescent and herbaceous lycopods ferns tree like and small varities calamities and cordaites four floral groupings are recognized in the hernshaw fire clay coal bed the inferred paleoecology and vertical stratification of each of these four floral groupings is similar in structure to the phasic floral communities found in modern domed peat systems suggesting that the ancient hernshaw fire clay peat swamp was a domed deposit compositional characteristics petrographic make up ash yield and sulfur content associated with the four groupings are consistent with and support this interpretation where uninterrupted by inorganic partings the hernshaw fire clay coal bed commonly contains basal coal layers dominated by lycospora bearing arborescent lycopods with successive increments showing a progression to a more fern and herbaceous lycopod dominant flora in younger layers these observations are corroborated by petrographic analyses which show the bed to be compositionally stratified increments dominated by lycospora have high vitrinite contents in contrast to increments containing increased percentages of fern and herbaceous lycopod affiliated taxa that are enriched in inertinite macerals the volcanic ash fall preserved as the flint clay parting in the hernshaw fire clay coal bed had a considerable effect on the development of the ancient hernshaw fire clay peat swamp besides interrupting peat formation the presence of an inorganic substrate represent a major change in edaphic conditions within the swamp this disruption is demonstrated by a change in palynflora and by the establishment and proliferation of some plant groups notably cordaites and calamites that may have been better adapted to growth on mineral soils these palynologic and petrographic relationships thought to be indicative of a domed peat swamp origin are not confined to the hernshaw fire clay coal bed but appear to be characteristic of many coal beds in the appalachian basin and also of coal beds in other basins

chaco low level jet events characterization during the austral summer season 1 previous studies showed a relationship between convection maxima and the convergence of vapor flux over southeastern south america nicolini and saulo 2000 explored the hypothesis of an intensification of this mutual dependency during the chaco jet events they defined these events as extreme cases of low level jets east of the andes that penetrate southernmost to 25 s using eta operative products during the 1997 1998 austral warm season the interest of the present paper centers on the climatic characterization of the chaco jet events cjes and the possibility of researching this hypothesis using the european centre for medium range weather forecasts reanalyses era which cover a 15 year period 1979 1993 the cjes represent a subensemble of low level jet events east of the andes that are infrequent in the era data set their duration varies from 1 to 10 days more frequently extending from 1 to 5 days the outstanding features of the circulation and the thermodynamic field that represent this ensemble are a maximum contrast of air masses in a latitude close to 39 s the presence of a trough centered on 70 w within a baroclinic wave train penetrating from the pacific ocean and a maximum of heat and moisture over northen argentina and paraguay during the cjes there is an important flux of moisture and convergence at low and mid levels that is about 10 times more intense than the summer mean the intensity found in the water vapor flux anomaly reinforces the importance of studying these episodes for the purpose of determining the water balance over southeastern south america the statement that the cjes represent an important characteristic of the southeastern south american climate is founded on the fact that although the cjes only represent 17 of the austral summer days they account for a significant fraction of the precipitation a maximun of 55 over northeastern argentina however it is indispensable to contrast these results with future field experiments to test the hypothesis addressed in this paper

lake highstands on the altiplano tropical andes contemporaneous with heinrich 1 and the younger dryas new insights from 14 c u th dating and δ 18 o of carbonates this study provides new geochronological and stable isotope constraints on late pleistocene fluctuations in lake level that occurred in the closed watershed of the central altiplano between 25 and 12 ka u series isochrons and 14 c ages from carbonates are used to confirm and refine the previous chronology published placzek et al 2006b our new data support three successive lake highstands during the late pleistocene i the lake sajsi cycle from 25 to 19 ka that culminated at 3670 m at about 22 ka almost synchronously with the global last glacial maximum ii the lake tauca cycle that lasted from 18 to 14 5 ka and was characterized by the highest water level reached at least 3770 m from 16 5 to 15 ka iii the lake coipasa cycle from 12 5 to 11 9 ka that reached an elevation of 3700 m 42 m above the elevation of the salar de uyuni 3658 m these high amplitude lake level fluctuations are in phase with the cold warm oscillations that occurred in the north atlantic and greenland during the late pleistocene heinrich 1 bolling allerod younger dryas such temporal coincidence supports the hypothesis that wet events recorded in the central altiplano are controlled by the northesouth displacement of the inter tropical convergence zone resulting from changes in the meridional temperature gradient finally the oxygen isotope ratios measured in these lacustrine carbonates allows for calculation of the 18 o value of paleolake waters estimates of water 18 o v smow are 2 8 0 7 for lake tauca and 1 6 0 9 for lake coipasa these data are used to constrain changes in lake hydrology and can be interpreted to indicate that the proportion of precipitation arising from local water recycling was less than 50

geochemistry of environmentally sensitive trace elements in permian coals from the huainan coalfield anhui china abstract to study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the permian period from the huainan coalfield anhui province china borehole samples of 336 coals two partings and four roof and floor mudstones were collected from mineable coal seams major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry icp oes inductively coupled plasma mass spectrometry icp ms and hydride generation atomic absorption spectrometry haas the depositional environment abundances distribution and modes of occurrence of trace elements were investigated results show that clay and carbonate minerals are the principal inorganic constituents in the coals a lower deltaic plain where fluvial channel systems developed successively was the likely depositional environment of the permian coals in the huainan coalfield all major elements have wider variation ranges than those of chinese coals except for mg and fe the contents of cr co ni and se are higher than their averages for chinese coals and world coals vertical variations of trace elements in different formations are not significant except for b and ba certain roof and partings are distinctly higher in trace elements than underlying coal bench samples the modes of occurrence of trace elements vary in different coal seams as a result of different coal forming environments vanadium cr and th are associated with aluminosilicate minerals ba with carbonate minerals and cu zn as se and pb mainly with sulfide minerals

stable isotopic record of hydrological changes in subtropical laguna mar chiquita argentina over the last 230 years laguna mar chiquita a highly variable closed saline lake located in the pampean plains of cetral argentina is presently the largest saline lake in south america 6000km2 the availability of hitorical instrumental lake level and salinity data for the past 100 years allows for the calibration of the isotopic archive recorded in the lake sediments prolonged intervals with either negative or positive hydrlogical balances have severely modified lakewater levels salinity and primary productivity and have also controlled the isotopic composition of both the authigenic carbonate 8ooarb and f133ccarb and sedimetary organic matter 6 c0 extensive evaporation during lowstand stages results in an enrichment of 180 and 13c in the lake waters and is recorded in the sediments as the most positive 8o8arb and 613c carb compositions 0 0 o and 1 9yoo respectively conversely more negative 6f 8ocarb and 813ccarb values 1 8 o and 3 8yoo respectively are the result of increasing freshwater input into

the el nino impact on the summer monsoon in brazil regional processes versus remote influences the el nino impact on brazil s summer monsoon has not been adequately assessed through seasonal analysis because it shows significant subseasonal variations in this study the el nino influence on the summer monsoon circulation rainfall and temperature is analyzed with monthly resolution using data from a dense network of stations the expected precipitation percentiles during the monsoon season of el nino en events are calculated as well as anomalies of surface temperature and thermodynamic parameters this information is analyzed jointly with anomaly composites of several circulation parameters the analysis shows that some precipitation and circulation anomalies which are consistent and important during part of the season are smoothed out in a seasonal analysis there are abrupt changes of anomalies within the summer monsoon season suggesting the prevalence of regional processes over remote influences during part of the season the probable role of remote influences and regional processes is assessed the anomalous heat sources associated with el nino perturb the walker and hadley circulations over south america and generate rossby wave trains that produce important effects in the subtropics and extratropics in the early summer monsoon season remotely produced atmospheric perturbations prevail over brazil anticyclonic low level anomalies predominate over central east brazil in the tropics and subtropics due to the subsidence over the amazon and to rossby waves in the subtropics easterly moisture inflow from the atlantic is favored but diverted toward northern south america sa and south brazil there are negative precipitation anomalies in north and central east brazil and positive ones in south brazil these precipitation anomalies are favored by the perturbation in the walker and hadley circulation over the east pacific and south america and by a rossby wave train over southern sa that originates in the eastern pacific in january with the enhancement of the continental subtropical heat low by anomalous surface heating during the spring there is anomalous low level convergence and cyclonic circulation over southeast brazil while at the upper levels anomalies of divergence and anticyclonic circulation prevail this anomalous circulation directs moisture flux toward central east brazil causing moisture convergence in this region a favorable thermodynamic structure enhances precipitation over central east brazil the dry anomalies in north brazil are displaced northward and the anomalies in south brazil almost disappear in february after the above normal precipitation of january the surface temperature anomalies turn negative and the precipitation diminishes in central east brazil there are negative rainfall anomalies in north brazil and in the south atlantic convergence zone sacz and positive ones in south brazil influence function analysis shows that while the anomalies of circulation over southeast brazil in the spring of el nino years are mostly due to remote influences from the tropical east pacific those in january are probably due to local influence during this month the monsoonlike circulation is enhanced simultaneous and lagged correlation analysis of sst and rainfall in central east brazil shows that sst anomalies in the atlantic ocean off the southeastern coast of brazil fluctuate on the same timescale as the circulation and precipitation anomalies

holocene paleohydrology and glacial history of the central andes using multiproxy lake sediment studies here we document at century to millennial scale the regional changes of precipitation evaporation from the late pleistocene to present with multiproxy methods on a north south transect of lake sites across the eastern cordillera of the central andes the transect of study sites covers the area from v14 s to 20 s and includes core studies from seven lakes and modern calibration water samples from twenty three watersheds analyzed to constrain the down core interpretations of stable isotopes and diatoms we selected lakes in different hydrologic settings spanning a range of sensitivity to changes in the moisture balance these include 1 lakes directly receiving glacial meltwater 2 overflowing lakes in glaciated watersheds 3 overflowing lakes in watersheds without active glaciers and 4 lakes that become closed basins during the dry season the results of our current work on multiple lakes in the bolivian andes show that while the overall pattern of holocene environmental change is consistent within the region conditions were not always stable over centennial to over millennial timescales and considerable decadal to centuryscale climate variability is evident abbott et al quat res 47 1997 70 80 quat res 47 1997 169 180 quat sci rev 19 2000 1801 1820 polissar master s thesis university of massachusetts 1999 comparison of the paleoclimate record from one well studied site lago taypi chaka kkota ltck with others within the region illustrates a consistent overall pattern of aridity from the late glacial through the middle holocene previous work noted a difference between the timing of water level rise in lake titicaca v5 0 3 5 ka b p abbott et al quat res 47 1997 169 180 cross et al holocene 10 2000 21 32 rowe et al clim change 52 2002 175 199 and the onset of wetter conditions at 2 3 ka b p in ltck a lake that drains into the southern end of lake titicaca abbott et al quat res 47 1997 70 80 sedimentary and oxygen isotope evidence from paco cocha 13 54ps located in the northern reaches of the expansive 57 000 km 2 titicaca watershed which spans v14 s to 17 s indicates that

mid holocene paleoenvironments and the archeological record of southern mendoza argentina the environmental heterogeneity of southern mendoza led to different environmental responses during the mid holocene more arid conditions and perhaps higher temperatures were dominant in the lowlands while the high andes experienced increased snowfalls and neoglacial readvances from ca 6000 to 4000 years bp the opposing climate pattern of the region in comparison with the western pacific foothills of the andes is apparently related to the different influences exerted by the westerlies on both sides of the cordillera the archeological record of this time period is represented by very few sites with a low density of material both the temporal distribution of the radiocarbon dates and the occupation index suggest a significant decrease of human occupations manifested by a chronological hiatus which varies in timing and duration according to the areal scale of analysis the coincidence of the occupational hiatus and the low amount of archeological evidences would point to abandonment and or a change related to a low intensity pattern of land use across the region these human responses seem to parallel the general arid climatic conditions of the mid holocene although more detailed information and particularly numerical dates are needed to test the hypothesis site formation processes including site disturbance produced by later human occupations are alternative explanations also evaluated to give account of the archeological record

quantification of the modes of occurrence of 42 elements in coal abstract a series of 20 coal samples were subjected to sequential leaching with ammonium acetate hydrochloric acid hydrofluoric acid and nitric acid to quantify the modes of occurrence of about 42 elements the results indicate that within a coal rank the leaching behavior of many elements are broadly similar however the behavior of many elements varies between bituminous and subbituminous coals while the leaching behavior of most elements is consistent with previous mode of occurrence interpretations there were a number of unanticipated results about 75 of the arsenic in bituminous coals appears to be associated with sulfides probably pyrite however only 40 of the arsenic in the low rank coals appears to be associated with pyrite in the bituminous coals we interpret that about 60 of the beryllium is associated with silicates but in the low rank coals only 30 is silicate associated in the bituminous coals 25 of the magnesium is associated with carbonates but in the low rank coals 75 of the magnesium is in the carbonates fifty five percent of the molybdenum was associated with the sulfides in the bituminous coals and in the low rank coals 65 was in the silicates in the bituminous coals the rare earth elements ree are predominantly in the phosphate minerals 70 for the light ree and 50 for the heavy ree but in the low rank coals the ree 50 60 are associated with the clays sodium is predominantly 80 associated with silicates in the bituminous coals and with the organics 65 in the low rank coals titanium appears to occur more in the clays 65 bituminous 70 low rank than in oxides 35 bituminous 15 low rank tungsten is in the sulfides 50 in the bituminous coals but in the clays 60 in the low rank coals uranium is associated with the silicates 40 and insoluble phases such as zircon 30 in the bituminous coals but is associated with the organics 55 in the low rank coals many of these rank differences reflect a higher detrital input and greater sulfide mineralization of the bituminous coals

loess of southern south america abstract loess and loessoid loess like reworked loess sediments extend across the chaco pampean plains and the nw mountain environments of argentina and in neighbouring countries paraguay brazil uruguay bolivia loessoid sediments are much more abundant than primary loess the beginning of the loessoid sedimentation cycle was related to a phase of late miocene orogeny in the andes the plio pleistocene record is mostly composed of loessoid sediments modified by pedogenesis which produced welded palaeosols the late pleistocene holocene loess record reveals a heterogeneous composition across the region coarse textures and an andean derived volcanic composition prevail in the southern pampas finer textures and material coming from the andes and the other two sources sierras pampeanas and the parana basin characterize the loess deposits of the northern pampas and the eastern chaco a southern patagonian source is also suggested for the mountain valley loess of tucuman although a western andean provenance has been proposed it is believed that the material in the western chaco was derived from the bolivian andes loess deposition was related to a multistage transport mechanism involving fluvial and aeolian processes inferred westerly and southwesterly wind directions as dominant carriers of the aeolian deposits are in agreement with westerly palaeowind simulations using climate models however the role played by westerly tropospheric winds and northerly winds remains to be established

midsummer low level circulation and precipitation in subtropical south america and related sea surface temperature anomalies in the south atlantic abstract the midsummer interannual variability of the low level tropospheric circulation and of the precipitation field in subtropical south america sa associated to the sea surface temperature sst anomalies in the western subtropical south atlantic ocean wssa is investigated using reanalyses regional precipitation datasets and monthly ssts the region of the wssa where sst has the strongest relation with precipitation in subtropical sa was identified using canonical correlation analysis this region extends from 20 to 30 s and from 30 to 50 w composites corresponding to extreme ssts in this area show two well differentiated patterns in the low level circulation and in the precipitation fields in the composite corresponding to the more positive sst anomalies in this area the mainstream of the low level flow and of the moisture transport from the continental low latitudes starts to follow a southeastward direction at 10 s and converges with the west flow at 35 s over the atlantic ocean on t

holocene eolian activation as a proxy for broad scale landscape change on the gila river indian community arizona abstract eolian sediments are common within the middle gila river valley southern arizona and reflect variability in eolian and fluvial processes during the late holocene this study focuses on deciphering the stratigraphic record of eolian deposition and associated luminescence dating of quartz extracts by single aliquot regeneration sar protocols stratigraphic assessment coupled with luminescence ages indicates that there are four broad eolian depositional events at ca 3145 220 yr 1950 1360 yr 800 100 yr and 690 315 yr this nascent chronology correlated with regional archeological evidence and paleoclimate proxy datasets leads to two general conclusions 1 loess deposits transverse dune formation and sand sheet deposition in the late holocene are probably linked to flow variability of the gila river though the last two events are concordant with regional megadroughts and 2 the stability of eolian landforms since the 19th century reflects the lack of eolian sediment supply during a period of fluvial incision resulting in entisol formation on dunes the prime catalyst of eolian activity during the late holocene is inferred to be sediment supply driven by climate periodicity and variable flow within the gila river catchment

early to mid holocene aridity in central chile and the southern westerlies the laguna aculeo record 34 s abstract central chile 32 35 s lies at the northern border of strong westerly influence and thus exhibits a steep precipitation gradient therefore the palaeoclimatic archives in the region are suitable for detecting past moisture changes the study of laguna aculeo 33 50 s 70 54 w presents a multiproxy holocene lake record including sedimentology geochemistry mineralogy pollen diatoms and radiocarbon dating 17 dates results indicate an arid early to mid holocene period about 9500 5700 cal yr b p after 5700 cal yr b p effective moisture increased progressively and around 3200 cal yr b p modern humid conditions were established numerous intercalated clastic layers reflect flood deposition during rainy winters a fluvial unit was deposited shortly before 9000 cal yr b p subsequently flood events were absent until 5700 but have become frequent since 3200 cal yr b p the frequency of flood layers possibly points to weak or no el nino activity during the early and mid holocene with a subsequent increase during the late holocene during the early and mid holocene the westerlies were probably blocked and hence deflected southward by the subtropical high pressure cell higher precipitation during the last 3200 yr seems strongly related to a weakened subtropical high pressure cell with intensified westerlies and possibly increased el nino activity

mid holocene paleoenvironments in northwestern argentina main patterns and discrepancies abstract this paper summarizes the available paleoenvironmental information for the mid holocene in northwestern argentina in order to systematize a multi scale scenario for human adaptation in the area the main results of the studies carried out by several research teams that have studied the conditions during this period in the tropical andean region are described and compared taking into account their geographical setting the proxies involved and their particular space time resolution the paleoenvironmental situation prior to the onset of mid holocene conditions i e starting at the late glacial maximum is summarized to estimate the nature and extent of the changes occurred during this period paleoenvironmental results their characteristics and interpretation are also considered a general trend towards an aridization process that fostered a hydrologic stress process is traceable along the mid holocene in northwestern argentina and the tropical andes however several localities seem to have retained wetter conditions increasing the contrast between highly productive environments and the generally dry landscape this paper is only a first step towards a full understanding of the diversity and complexity of the mid holocene in different space time scales but a necessary one in order to start to model the resources structure available for human groups in the past in the andes

petrology of indus river sands a key to interpret erosion history of the western himalayan syntaxis the indus river has been progressively transformed in the last decades into a tightly regulated system of dams and channels to produce food and energy for the rapidly growing population of pakistan nevertheless indus river sands as far as the delta largely retain their distinct feldspar and amphibole rich composition which is unique with respect to all other major rivers draining the alpine himalayan belt except for the brahmaputra both the indus and brahmaputra rivers flow for half of their course along the india asia suture zone and receive major contributions from both asian active margin batholiths and upper amphibolite facies domes rapidly exhumed at the western and eastern himalayan syntaxes compositionofindussandschangesrepeatedlyandmarkedlyinladakhandbaltistan indicatingoverwhelmingsedimentflux from each successive tributary as the syntaxis is approached provenance estimates based on our integrated petrographic mineralogical data set indicate that active margin units karakorum and transhimalayan arcs provide 81 of the 250f50 10 6 t ofsedimentsreachingthetarbelareservoireachyear partitioningofsuchfluxamongtributariesandamongsourceunitsallowsus to tentatively assess sediment yields from major subcatchments extreme yields and erosion rates are calculated for both the karakorum belt up to 12 500f4700 t km 2 year and 4 5f1 7 mm year for the braldu catchment and nanga parbat massif 8100f3500t km 2 yearand3 0f1 3mm year thesevaluesapproachdenudationratescurrentlyestimatedforsouthkarakorum and nanga parbat crustal scale antiforms and highlight the major influence that rapid tectonic uplift and focused glacial and fluvial erosion of young metamorphic massifs around the western himalayan syntaxis have on sediment budgets of the indus system detailed information on bulk petrography and heavy minerals of modern indus sands not only represents an effective independent method to constrain denudation rates obtained from temperature time histories of exposed bedrock but also

selenium distribution and mode of occurrence in the kanawha formation southern west virginia u s a abstract selenium concentrations were measured in five rock cores from a mine in boone county west virginia to determine their relationship to sulfur rock type and stratigraphic location the samples spanned the winifrede and coalburg coal beds of the middle pennsylvania upper kanawha formation and included coals and clastic lithologies the coals generally contained the highest concentrations of se and the sandstones the lowest no correlation was observed between total se and sulfur concentrations for either the entire data set or for individual lithologies better correlations were identified for log concentrations between total se and total organic carbon principal component analysis identified a strong sulfur acid component interpreted to be due to sulfide mineral presence which correlates well with s but not with se coal sample chemistry is more likely to load onto this component while clastic rock chemistry is more likely to load onto the second non sulfur component se concentrations load onto both components indicating they are not controlled by a single overriding chemistry selective extractions indicate that se is distributed between both sulfide and organically bound fractions as defined by the test overall the lack of correlation between se and s the distribution of se among extracted fractions and the loading of se onto both sulfur and non sulfur components support that the se in these rock layers is distributed in more than one chemically bound form non coal rock units with the highest concentrations of se were found adjacent to coal beds suggesting that redistribution of se may have occurred post deposition the acidic domed swamps that formed these coals were low in sulfur and a reasonable chemical setting to accumulate se if it were introduced the preservation of se in the domed swamp peat coupled with post depositional redistribution may partly explain the data presented

pleistocene periglacial eolian deposits in southwestern alaska sedimentary facies and depositional processes abstract pleistocene periglacial eolian sediments are widespread in the nushagak holitna and upper kuskokwim lowlands of southwestern alaska these sediments comprise mainly sand sheet deposits and sand loess intergrades with subordinate sand dune deposits and loess sand sheet deposits range from 1 sharply defined parallel low angle laminae formed by migrating wind ripples to 2 irregular subhorizontal strata which reflect migration of poorly segregated wind ripples accumulation on a sparsely vegetated surface adhesion on a quasi planar bed and or niveo eolian deposition sand loess intergrades represent alternating bed load and suspension deposition related mainly to the stochastic and seasonal variability of former wind systems the dominance of sand sheet deposits over deposits of well formed dunes in the pleistocene eolian record of southwestern alaska reflects the limited availability of loose dry sand in this former periglacial environment immobilization of sand after deposition as low relief sheets resulted from a seasonally variable combination of ice cementation sparse vegetation high water tables and snow cover

eolian sand sheet deposition in the san luis paleodune field western argentina as an indicator of a semi arid environment through the holocene abstract eolian deposits are common in the western pampas of argentina and most are assumed to be associated with glacial conditions stratigraphic and sedimentologic studies coupled with osl dating in san luis province document for the first time a nearly continuous sequence of eolian sand sheet deposits that span most of the holocene petrology and geochemical analyses indicate that the source of the sand is from pre existing pleistocene eolian sediments sand sheet deposition between ca 12 and 1 ka is associated with sparse monte type vegetation that occurs with drier conditions map 450 100 mm than the late 20th century 700 mm this paleoenvironmental inference is consistent with nearby pollen and lake level records a persistent semi arid environment in western argentina during the holocene may reflect sustained warm ssts in the western equatorial atlantic ocean which may have suppressed the pressure gradient between the south atlantic anticyclone and chaco low and thus the flux of summer moisture to western argentina there appears to be a paleoclimatic dipole response between a dry western argentina and a wet southeastern brazil which is consistent with the increasing strength of the south american monsoon through the holocene sand sheet accretion appears to cease by 800 to 200 years ago with wetter conditions and succession to espinal vegetation prior to european contact

the occurrence and origin of selenium minerals in se rich stone coals spoils and their adjacent soils in yutangba china abstract several se bearing minerals have been identified in se rich stone coal spoils and their adjacent organic rich soils in yutangba of enshi china where human se toxicity occurred in the 1960s these minerals mainly include native se se 0 krutaite cuse 2 klockmannite cuse mandarinoite fe 2 seo 3 3 6h 2 o se bearing chalcopyrite cufe se s 2 and pyrite fe se s 2 the assemblage of native se krutaite klockmannite and se bearing pyrite and chalcopyrite is primarily present in the stone coal near a fault plane while the assemblage of native se and krutaite is found in the se rich carbonaceous mudstone and organic rich soils which are 60 m away from the stone coal exposure the assemblage of mandarinoite and native se is present in abandoned stone coal spoils where natural combustion occurred native se is quite extensive in the stone coal spoils and nearby soils derived from them the co occurrence of cu se minerals and native se indicates that these minerals could have formed under a relatively acidic and reducing environment below 220 c and suggests that cu could play a significant role in fixing reduced se ions in the acidic organic rich surface environment furthermore the occurrence of mandarinoite suggests that iron oxides constrain the geochemical behavior of se in oxidizing environments our observations provide new insights into the mechanisms of se fixation and accumulation during weathering of se rich rocks

late quaternary palaeosol records from subtropical 38 s to tropical 16 s south america and palaeoclimatic implications abstract loess and palaeosols in the subtropical lowlands of south america 23 38 s have a large potential to serve as archives of late quaternary environmental and climate changes at present mean annual precipitation generally decreases from n to s and from e to w though with a complex seasonal pattern with austral summer rainfall related to the monsoonal circulation and with austral winter rainfall related to the se trades in this paper we present results of multiproxy geochemical analyses from three representative eolian alluvial soil profiles along a s n transect aiming at the reconstruction of past climate changes i profile chasico at the southern border of the subtropics 38 s ii d4 in misiones at the northern border of the subtropics 27 s and for comparison iii laguna sucuara in the savannas of the bolivian lowlands 16 s our results show that before 16 ka bp conditions were likely very cold and dry except for in d4 loess or soils are not preserved due to rather scarce vegetation cover and resultant deflation in chasico accumulation of sands directly overlying the tertiary starts only during the late glacial indicating increasing temperatures and increased monsoonal precipitation coinciding with the tauca wet phase on the altiplano in d4 a palaeosol is preserved below the late glacial sediments and the deflation hiatus this palaeosol is dated to 40 ka bp and documents an earlier but less intensive southward reaching phase of monsoonal precipitation inca huasi on the altiplano whereas the seasonality during the late glacial seems to have been very pronounced conditions for organic matter production and preservation became much more favourable at chasico and d4 during the early holocene we suggest that extra tropical winter precipitation played a more important role than before and than today between 7 5 and 3 ka bp the expansion of c4 plants along the s n transect suggests increasing aridity probably due to a weakening of the extra tropical circulation in combination with a relatively weak monsoonal circulation only after 3 ka bp climate became more humid again due to the re strengthening of the monsoon

geochemistry of sediments from quaternary sand ramps in the southeastern mojave desert california abstract trace element analyses of sediment from sand ramps in the bristol trough and clark s pass aeolian corridors of the mojave desert california were conducted to determine their depositional history and relation to sources of sediment within sand transport corridors sand ramps are topographically controlled depositional systems consisting of amalgamated accumulations of aeolian fluvial and talus deposits these landforms contain a variety of deposits formed in different environments and are therefore a valuable source of paleoenvironmental information sediments were studied from three sand ramps the iron mountain big maria and dale lake sand ramps and from two sand sheets rice valley and cactus plain cactus plain is located on the eastern side of the colorado river in arizona but previous researchers have suggested that it is related to the corridors of the western california side geochemical data from units within individual sand ramps indicate that sources for each sand ramp changed through time probably as sediment availability from different local fluvial playa systems changed in response to climate fluctuations analyses also indicate that each sand ramp is composed of sediment from discrete local sources sand deposits in the bristol trough are not integrated and thus the corridor does not act as a coherent sand transport pathway comparisons of sand from cactus plain and sediment from the bristol trough and clark s pass corridors indicates that the cactus plain sand on the east side of the colorado river was not derived from sources on the west side of the river

deep freeze petrology of lena river sand siberia modern sand from the vast 2 430 000 km 2 high latitude lena river watershed occupies a low lying mostly unglaciated craton covered by thick widespread permafrost totally different from the watersheds of large temperate and tropical rivers whose sands have been previously studied to establish modern baselines for the interpretation of ancient sandstones fifty nine lena sands are rich in rock fragments and feldspar and reflect well the three major tectonic provinces that underlie it platform shield and collisional suture although the platform and shield sands are still very immature long exposure to cool middle tertiary climates at first and dry sub arctic to arctic climates later is the underlying cause of the mineralogically immature river sands of the lena river

palynological evidence for increased aridity on the central chilean coast during the holocene abstract the late quaternary vegetation of the semiarid coast of central chile is inferred from the palynological analysis of profiles from quereo 31 55 s and quintero 32 47 s prior to 11 400 yr b p wet conditions are suggested by the abundance of pollen indicators of swamp and aquatic taxa such as cyperaceae and myriophyllum and by the presence of traces of arboreal pollen since ca 10 000 yr b p a trend toward increasingly drier conditions is implied by the almost complete absence of arboreal and aquatic taxa and a general decrease in the diversity of the semiarid shrubland indicators from 3000 yr b p onward the pollen records show the reappearance of swamp and aquatic taxa presumably associated with wetter conditions which led to recolonization by forest taxa at 1720 yr b p in quintero the drier climate detected along the semiarid coast of central chile during most of the holocene extended inland to the andean foot hills within the present mediterranean type climate zone of chile and also affected the distribution of the winter deciduous nothofagus forests and the northern boundary of the temperate rain forests

concentration distribution and modes of occurrence of selenium in huaibei coalfield anhui province china selenium a toxic element is highly enriched in the coals of the huaibei coal deposit china for this study se content along with rock forming and trace element abundances was determined in 123 coal and 19 rock samples collected from the main coal seams in seven coal mines in the huaibei coalfield this was done to investigate the se geochemistry in the huaibei coals compared with average chinese coal and other coals around the world the huaibei coals are enriched in se by a factor of five differences in the boron content in the sequence of huaibei coal seams show that the depositional environment of the formations hosting the coal seams evolved from a delta front to a prodelta setting and then to a delta plain environment selenium is distributed unevenly both horizontally and vertically in the huaibei coal deposit pearson correlation coefficients between se with several elements ca fe and s indicate that iron bearing clay minerals and carbonates are the dominant carriers of se in coals of the lower shihezi formation selenium in coals from no 3 and no 10 coal seams are mainly associated with sulfide minerals the well developed faults in huaibei coalfield may have contributed to the enrichment of se in huaibei coals