geophysical and geological evidence of neotectonic deformation along the hovey lake fault lower wabash valley fault system central united states high resolution seismic shear wave reflection profiles were collected over a segment of the hovey lake fault a known paleozoic fault within a system of faults in the southernmost wabash river valley of the central united states although the fault zone called the wabash valley fault system lies in an area of recognized prehistoric and contemporary seismicity the seismogenic potential of this system remains poorly defined consequently the objectives of this study are to assess the hovey lake fault one of the more prominent fault strands in the system for neotectonic reactivation and if present collect sediment samples for dateable material from the disrupted horizons to provide an age constraint for the movement the resultant stacked profiles show high angle deformation extending above the paleozoic bedrock and into upper quaternary sediment time displacement calculations from the data show approximately 10 5 m of offset on the top of bedrock horizon and 2 m of inverted displacement along the earliest arriving quaternary soil reflector preliminary correlative coring and carbon 14 age dating of a disrupted soil horizon located 7 7 m below ground surface suggest fault movement at this site as late as approximately 37 000 years before present

late quaternary chronostratigraphic framework of terraces and alluvium along the lower ohio river southwestern indiana and western kentucky usa abstract the lower ohio river valley is a terraced fluvial landscape that has been profoundly influenced by quaternary climate change and glaciation a modern quaternary chronostratigraphic framework was developed for the lower ohio river valley using optically stimulated luminescence osl dating and allostratigraphic mapping to gain insights into the nature of fluvial responses to glacial interglacial stadial interstadial transitions and holocene climate change river deposits t0 youngest to t7 oldest were mapped along a 75 km reach of the lower ohio river and were dated using 46 osl and 5 radiocarbon samples the examination of cores combined with osl and radiocarbon dating shows that fluvial sediments older than marine oxygen isotope stage mis 2 are present only in the subsurface aggradation during mis 6 illinoian glaciation filled the valley to within 7 m of the modern floodplain and by 114 ka mis 5e sangamon interglacial the ohio river had scoured the mis 6 sediments to 22 m below the modern floodplain surface there were no fluvial sediments in the valley with ages between mis 5e and the middle of mis 3 the mis 3 ages 39 ka and stratigraphic position of t5 deposits suggest the ohio river aggraded 8 14 m during mis 4 or mis 3 near the end of mis 3 the ohio river incised the mid last glacial mid wisconsinan deposits 10 m and began aggrading again by 30 ka aggradation continued into mis 2 with maximum mis 2 aggradation occurring before 21 ka which is coincident with the global last glacial maximum lgm as the ohio river adjusted to changing fluxes in sediment load and discharge following the lgm it formed a sequence of fill cut terraces in the mis 2 outwash that get progressively younger with decreasing elevation ranging in age from 21 ka to 13 ka from 14 ka to 13 ka the ohio river rapidly incised 3 m to form a new terrace and by 12 ka at the onset of the holocene the ohio river established a meandering channel pattern the river formed a broad floodplain surface from 12 ka to 6 ka and then incised 1 m and formed a fill cut terrace from 6 ka to 5 ka after 5 ka likely in response to mid holocene drought in north america the ohio river incised 5 m and by 4 ka the river began aggrading again the ohio river has aggraded 4 m since aggradation began at 4 ka the chronostratigraphic framework and reconstructed history developed here suggest that the lower ohio river is highly sensitive to glacial interglacial transitions and abrupt holocene climate change and responds rapidly to these allogenic forcings

climate and vegetation history of the midcontinent from 75 to 25 ka a speleothem record from crevice cave missouri usa four missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago ka the thorium 230 dated records reveal that between 75 and 55 ka the midcontinental climate oscillated on millennial time scales between cold and warm and vegetation alternated among forest savanna and prairie temperatures were highest and prairie vegetation peaked between 59 and 55 ka climate cooled and forest replaced grassland at 55 ka when global ice sheets began to build during the early part of marine oxygen isotope stage 3

petrographical palynological and geochemical analyses of the hub and harbour seams sydney coalfield nova scotia canada implications for facies development abstract benched channel samples and continuous block samples of the hub and harbour seams from the sydney basin nova scotia were studied to define the variations in petrography geochemistry and palynology of the seams and to interpret the depositional environments of the precursor mires petrographic compositions of the seams are very similar with high vitrinite content low inertinite moderate liptinite and negligible clastic mineral content pyrite content is moderate there is little variation in petrographic composition between benches in either seam there are marked variations in petrographic compositions at the lithotype scale petrographic facies parameters indicate deposition of the bulk of both seams under fairly uniform conditions in relatively wet mires unusually wet or dry periods were rare the palynological assemblages of both seams indicate a middle to late westphalian d age the common to abundant palynomorphs are derived from arborescent and herbaceous lycopsids tree ferns and other ferns and sphenopsids the palynological assemblages support the petrographic interpretation of relatively wet mires cordaites pollen florinites is rare suggesting that there was little contribution from plants growing in dry or upland areas the absence of the densospore miospore phase and the petrographic data indicate there were no periods in which domed mires occurred the distinctive dull bands occurring in the hub and harbour seams are characterised by low vitrinite contents high inertinite content high liptinite and common detrital minerals sporinite showing varying degrees of degradation is commonly highly concentrated in thin bands the geochemistry is marked by much higher hi values than normally reported for coals but other indices are typical for coals of this rank the palynological assemblages of the dull bands are dominated by tree fern spores and other ferns with only a minor contribution by sphenopsid spores the dull bands were deposited during periods of inundation of mires relatively low mineral content indicates that the distributary channels which flooded the mires were quite distant from the depositional sites of the samples

the relationship between coal petrography and depositional environments from selected coal basins in canada abstract this paper reviews current research in canada relating to the sedimentology of coal bearing sequences and the petrographic character of contained seams from selected intermontane and foreland basin settings the intermontane cumberland and stellarton basins of nova scotia contain westphalian coal bearing strata of different character coal seams that formed in fluvial dominated depositional environments of the springhill coalfield cumberland basin commonly brighten upward and laterally display distinct areal zones a piedmont zone formed by interfingering of mire and distal fan sheetflow deposits an inner mire zone largely devoid of partings and a riverine zone with large scale seam splits about multistorey sandstone bodies maceral based groundwater influence and vegetation indices combined with miospore analyses indicate that the peat precursors of the no 3 seam of the inner mire zone accumulated from a groundwater influenced rheotrophic to mesotrophic forest mire swamp fen both the gelification of lignin derived maceral precursors and the domination of mire vegetation by lycopsid trees reflect this groundwater influence coal that formed from the frequently flooded paleomires of the stellarton basin is generally dull microbanded and mineral rich the location of mires within the basin was largely determined by basin subsidence rates when subsidence rates were high mires developed around the margin of a central basin lake coal seams that formed from these mires e g mcleod seam thicken toward basin margins and grade into sapropelic shale near the basin centre petrographic analyses of the mcleod seam suggest development from limnic to wet forest swamp conditions and a return to a limnic environment at the top of the seam thick coal e g foord seam developed near the basin centre during periods of lower subsidence rates and grades into red beds and paleosols toward the basin margin the foord seam of the basin centre is characterized by low mineral matter contents and a high proportion of degraded vitrinite macerals in the central parts of the seam interpreted to reflect prolonged peat accumulation with very limited clastic input the top and the base of the seam in contrast were subjected to significant clastic input as indicated by microbanding associated with significant amounts of detrital minerals and macerals coal seams of the lower cretaceous gates formation in the western canada basin formed in depositional settings ranging from coastal swamps strandplains to the upper delta plain strandplain coal is characterized by great lateral continuity and substantial thickness whereas coal of the upper delta plain is thin and discontinous the strandplain coal is characterized by variable lithotype sequences oscillatory brightening up dulling up maceral based facies parameters indicate a wide range of mire facies for these lithotype successions open moor forest moor herbaceous and or shrubby marshes and slightly raised mires results from megafossil and phyteral analyses suggest that the coastal plain mires were dominated by taxodiaceous conifers whereas ferns angiosperms and herbaceous lycopods are thought to have occupied the more marshy and or marginal stream lake side environments

geochemical and petrographical characteristics of low rank balingian coal from sarawak malaysia its implications on depositional conditions and thermal maturity abstract geochemical and coal petrographical analyses were undertaken on low rank upper pliocene balingian coal from sarawak malaysia in an attempt to reconstruct the conditions during peat accumulation and the subsequent coalification processes chemically the coal in this study is characterised by high moisture low ash yield and low sulphur content the low ash yield and low sulphur content together with the lack of epiclastic partings clearly indicate that it was deposited in ombrotrophic raised bogs the coal was plotted in the type iii terrigenous kerogen zone of the van krevelen diagram with h c value below 0 9 this shows that the coal was derived from plant materials of terrigenous origin and is still immature for petroleum generation the petrographical study reveals nonetheless the expulsion of early generated hydrocarbons from the disintegration of suberinite and also from phlobaphinite and cutinite petrographically the coal is dominated by huminite with low to moderate amounts of liptinite and low amounts of inertinite pointing to predominantly anaerobic deposition conditions in the paleomires with limited thermal and oxidative tissue destruction most of the studied samples are characterised by low tpi and high gi values and are plotted on the marsh field of the diessel s diagram or it could also originate from decomposed wood in forested swamps nevertheless coals originating from both these sources usually generate high ash yield which is not the case for the studied coal this shows that the interpretation as suggested by the diessel s diagram is not valid for the studied coal the coal has a mean random huminite reflectance between 0 26 and 0 35 suggesting a lignite coal rank for the coal nevertheless geochemical classification based on total moisture and calorific value suggests a subbituminous c rank

ams radiocarbon age of the upper mississippi valley roxana silt abstract accelerator mass spectrometer radiocarbon ages of the roxana silt loess along the upper mississippi valley of wisconsin and minnesota indicate that loess sedimentation of the roxana silt occurred between about 55 000 and 27 000 14 c yr b p however due to local environmental controls the basal age at any given site may range from 55 000 to 35 000 14c yr b p the radiocarbon ages presented here are in agreement with previous radiocarbon ages for the roxana silt in its type area of west central illinois but indicate that long term sedimentation rates along the bluffline of the upper mississippi valley were very slow 4 8 cm 1000 yr compared to long term sedimentation rates along the bluffline of the type area 40 70 cm 1000 yr comparison of radiocarbon ages for midcontinent middle wisconsinan loess deposits indicates that sedimentation along the mississippi river valley may have preceded loess sedimentation along the missouri river valley by as much as 20 000 yr or that basal ages for middle wisconsinan loess along the missouri valley are erroneously young the bracketing ages for the upper mississippi valley roxana silt indicate that the mississippi river valley was receiving outwash sedimentation between 55 000 and 27 000 14c yr b p

a mid late quaternary loess paleosol record in simmons farm in southern illinois usa abstract in unglaciated areas of the mississippi valley region the typical full loess paleosol succession contains the modern soil developed in peoria silt weakly developed farmdale geosol developed in roxana silt sangamon geosol developed in loveland silt and yarmouth geosol developed in crowley s ridge silt although a fifth loess called the marianna silt is reported at one area the paleosol that separates the crowley ridge and marianna silts is not well defined previous thermoluminescence tl and optical stimulated luminescence osl age chronology has suggested multiple phases of sangamon geosol developed in loveland silt but clear morphological evidence of polygenetic sangamon geosol profiles have not been found recently a thick loess paleosol sequence has been studied in the middle mississippi valley in unglaciated southern illinois usa soil morphology and analytical results revealed five loesses and associated paleosol units two sangamon bt horizons were found separated by a thick actk horizon interpreted to indicate two phases of sangamon geosol development this well preserved loess paleosol succession provides one of the most complete mid late quaternary loess records in the middle mississippi valley to date and is important for studying the stratigraphic framework and paleoclimate and environment changes

paleovalley fills trunk vs tributary a late mississippian early pennsylvanian eustatic sea level drop resulted in a complex lowstand drainage network being eroded across the illinois basin in the eastern united states this drainage system was filled during the early part of the pennsylvanian distinct differences can be recognized between the trunk and tributary paleovalley fills fills preserved within the trunk systems tend to be fluvially dominated and consist of bed load deposits of coarse to medium grained sandstone and conglomerate conversely the incised valleys of tributary systems tend to be filled with dark mudstone thinly interbedded sandstones and mudstones and siltstones these finer grained facies exhibit marine influences manifested by tidal rhythmites certain traces fossils and macro and microfauna examples of tributary and trunk systems separated by no more than 7 km 4 3 mi along strike exhibit these styles of highly contrasting fills useful analogs for understanding this pennsylvanian system include the quaternary glacial sluiceways present in the lower ohio white and wabash river valleys of indiana united states and the modern amazon river brazil both the amazon river and the quaternary rivers of indiana have or had trunk rivers that are were dominated by large quantities of bed load relative to their tributaries the trunk valley systems of these analogs aggraded much more rapidly than their tributary valleys which evolved into lakes because depositional rates along the trunk are were so high that the mouths of the tributaries have been dammed by bed load deposits these holocene systems illustrate that sediment yields can significantly influence the nature of fill successions within incised valleys independent of rates of sea level changes or proximity to highstand coastlines

the geology petrology palynology and geochemistry of permian coal basins in tanzania 1 namwele mkomolo muze and galula coalfields abstract permian coal bearing strata occur in a number of intracratonic rift basins in tanzania this study examines coals shales and mudstones of the namwele mkomolo muze and galula coalfields rukwa basin by coal petrological palynological and rock eval techniques for the coals the focus was on the establishment of coal seam characteristics and related quality and utilization potentials whereas the shales and mudstones were examined for age relationships flora and related palaeodepositional environments and source rock potential the coal seams which have a thickness of up to 2 95 m are high in ash yields 25 63 wt and have calorific values ranging from 5344 to 18947 j g typical for many of the seams is their detrital nature as indicated by the high content in finely disseminated clay minerals quartz and detrital macerals pyrite content is variable 0 60 5 81 wt vitrinite reflectance ranges from 0 43 to 0 66 rrandom subbituminous to high volatile b bituminous use of the coals in small scale power generations and for domestic use would greatly reduce the dependency of rural tanzania on wood and wood derived charcoal as the main source of fuel palynomorph assemblages are characterized by the predominance of nontaeniate and taeniate pollen and trilete spores in the namwele mkomolo and muze coalfields at galula coalfield the palynomorph assemblages were poor rare trilete alete and monolete spores on the basis of age correlations with karoo basins to the south and the collie basin of western australia an artinskian to kungurian age is suggested for the coal measures in the rukwa basin the diversity of palynomorph assemblages suggests a variety of floras and contemporary depositional environments throughout deposition of the karoo strata this is consistent with coal petrographic parameter which would indicate that peat accumulation occurred in upper delta plain braided plain and lacustrine depositional environments rock eval parameters indicate kerogen type iii for all samples investigated and indicate very poor hydrocarbon source rock potential

vegetation and environment in eastern north america during the last glacial maximum abstract knowledge of the vegetation and environment of eastern north america during the last glacial maximum lgm is important to understanding postglacial vegetational and biogeographic dynamics assessing climate sensitivity and constraining and evaluating earth system models our understanding of lgm conditions in the region has been hampered by low site density problems of data quality particularly dating and the possibility that lgm vegetation and climate lacked modern analogs in order to generate improved reconstructions of lgm vegetation and environment we assembled pollen and plant macrofossil data from 21 and 17 well dated lgm sites respectively all sites have assemblages within the lgm timespan of 21 000 1500 calendar yr bp based on these data we prepared maps of isopolls macrofossil presence absence pollen analogs biomes inferred mean january and july temperatures and mean annual precipitation for the lgm tundra and open picea dominated forest grew along the laurentide ice sheet with tundra predominantly in the west in the east pinus dominated vegetation mainly p banksiana with local p resinosa and p strobus occurred extensively to 34 n and possibly as far south as 30 n picea glauca and a now extinct species p critchfieldii occurred locally picea dominated forest grew in the continental interior with temperate hardwoods quercus carya juglans liriodendron fagus ulmus growing locally near the lower mississippi valley at least as far north as 35 n picea critchfieldii was the dominant species in this region the florida peninsula was occupied by open vegetation with warm temperate species of pinus eastern texas was occupied by open vegetation with at least local quercus and picea extensive areas of peninsular florida and the continental interior had vegetation unmatched by any modern pollen samples the paleovegetational data indicate more extensive cooling in eastern north america at the lgm than simulated by either the ncar ccm0 or ccm1 climate models the occurrence of cool temperate conifers and hardwoods as far north as 34 35 n however indicates less severe cooling than some previous reconstructions paleoclimate inferences for the lgm are complicated by lowered atmospheric co 2 concentrations which may be responsible for the open nature and dominance of conifers in lgm vegetation

organic geochemical characteristics and depositional environment of the tertiary tanjong formation coals in the pinangah area onshore sabah malaysia article i nfo article history the tertiary tanjong formation coals exposed in the west middle block of the pinangah coalfield central part of southern sabah were analyzed and their depositional environments were interpreted the tertiary tanjong coals are humic and generally dominated by vitrinite with significant amounts of liptinite and low amounts of inertinite macerals total organic carbon contents toc of the coals range from 51 2 to 77 7 wt and yield of bitumen values ranging from 57 300 to 140 000 ppm which meet the standard as a source rock with good hydrocarbon generative potential in support good liquid hydrocarbons generation potential can be expected from the tanjong coals based on significant liptinitic content 15 this is supported by their high hydrogen index up to 300 mg hc g toc consistent with type ii and mixed type ii iii kerogens and py gc s2 pyrograms with n alkane alkene doublets extending beyond c30 the coal samples have vitrinite reflectance values in the range of 0 42 0 66 ro indicating immature to early mature stage for hydrocarbon generation these vitrinite reflectance values also indicated that the tanjong coals are with sub bituminous b a and high volatile bituminous c rank tmax values ranging from 419 to 451 c are good agreement with the vitrinite reflectance data this is supported by biomarker maturity parameters as suggested by the c32 homohopane the saturated fraction of the tanjong coals are characterized by dominant odd carbon numbered n alkanes n c23 to n c33 high pr ph ratios 8 18 high tm ts ratios 6 28 and pre dominant of regular sterane c29 all biomarker parameters clearly indicate that the organic matter was de rived from terrestrial inputs and deposited under oxic condition

evidence of strong earthquake shaking in the lower wabash valley from prehistoric liquefaction features earthquake induced liquefaction features in holocene sediments provide evidence of strong prehistoric shaking magnitude m b 6 2 to 6 7 in the wabash valley bordering indiana and illinois the source of the one or more earthquakes responsible was almost certainly in or near the wabash valley the largest event is interpreted to have occurred between 7500 and 1500 years ago on the basis of archeological pedological and stratigraphic relations

petrography and depositional environment of coal seams in the carboniferous morien group sydney coalfield nova scotia the morien group westphalian a stephanian of the sydney basin nova scotia contains numerous coal seams many of which can be traced across the onshore part of the basin depositional environments during coal formation range from proximal fluvially dominated to intercalated distal fluvial to restricted marine most of the coal samples analyzed in this study come from the bras d or section a near continuous coastal exposure of the sydney mines formation petrographic compositions of the samples are discussed in the context of the depositional setting of the enclosing strata the coal seams have a high vitrinite content 70 90 vol with moderate inertinite and low liptinite petrographic indices suggest that most coals of the sydney mines formation are similar to seams deposited in interdistributary or lower delta plain settings in other basins and provide support for the interpreted sedimentological setting of this sequence the coal seams of the bras d or section show little variation in gross

biomarker and micropetrographic investigations of coal from the krepoljin brown coal basin serbia abstract we investigated early diagenetic processes of the extractable organic matter from the miocene freshwater sequence which consists of coal fragments in clays sandstones and shales alternating with continuous brown coal layers we examined eight coals thirteen sediments and three non coaly underground layers the molecular assemblages of the identified aliphatic hydrocarbons in the krepoljin basin reflect the abundance of plant taxa as precursors or participants in the early diagenetic stage the data provide insight into the conditions prevailing in the lakes and bogs during early diagenesis the dominance of diterpanes indicates that the prevalent of the organic matter was of gymnosperous origin the hopanoid contents are considered to reflect microbial activity that the organic matter in the miocene krepoljin coal basin is immature was confirmed by the presence of biolipids such as hopanes c 27 17 h trisnorhopan saturated and aromatized abietanes pimaranes and phyllocladanes the most abundant compounds in all samples indicate a predominantly higher plant input related to the coniferous group but identification of the individual plant families was not possible amyrin and other triterpenoid derived triaromatic and triaromatic c ring cleaved hydrocarbons with triterpenoid structures are thought to be characteristic for angiosperms unsaturated compounds 2 triterpanes early intermediaries in the diagenetic transformation of angiosperms also indicate a low degree of sediment maturity

regional aridity in north america during the middle holocene increased aridity throughout the great plains and rocky mountain region during the middle holo cene has been documented from pollen records aeolian proxy variables in lake cores and active sand dune migration varve calibration provided by a continuously varved record of the holocene from a core from elk lake northwestern minnesota shows that the influx of aeolian clastic material increased beginning about 8 ka and ended about 3 8 ka with peak aeolian activity at about 6 ka if aeolian influx to elk lake corresponds in time to aeolian influx in other lakes and to maximum dune activity in minnesota dune fields then the varve calibration in elk lake provides precise time calibration of periods of peak aeolian activity in minnesota palaeowind studies from the minnesota dune fields show that the dominant wind direction when the dunes were active was from the northwest the same as the dominant wind direction in dune fields throughout the great plains and rocky mountains if the mid holocene aeolian act

stratigraphy and chronology of mississippi valley loess in western tennessee the stratigraphy and chronology of loess deposits in the mississippi valley provide an important proxy record of the number and timing of glacial advances into the upper mississippi drainage basin the stratigraphy of loess and paleosols from two exposures in northwestern tennessee reveals three major loess units that are correlated with the loveland loess roxana silt and peoria loess from oldest to youngest detailed measurements of clay and secondary pedogenic iron contents suggest that the loveland loess may consist of multiple loess units which have been pedogenically welded to one another to form a composite sangamon soil the mineralogy of the coarse silt fraction from one exposure reveals both primary mineralogical differences between the peoria loess and the roxana silt and pedogenic overprinting by the sangamon soil grain size and iron data suggest that the degree of pedogenic alteration increases from west to east away from the loess source area which probably reflects the role of sedimentation rate on the degree of pedogenic alteration of loess however only the peoria loess shows the expected exponential eastward decrease in thickness the thickness of older loess units appears to be controlled more by the occurrence of localized erosion than by distance from source area most samples are resistant to solar resetting of the thermoluminescence signal which if unrecognized could yield thermoluminescence ages that significantly underestimate the true age of the deposits the best match between thermoluminescence age using the total bleach method and radiocarbon age of the peoria loess and roxana silt is achieved when either long durations of optical bleaching by sunlight 32 hr or artificial ultraviolet uv light are applied to define the residual thermoluminescence level partial bleach analysis indicates that long duration optical bleaching by sunlight or uv lamp bleaching does not systematically overbleach samples of peoria loess and roxana silt three thermoluminescence age estimates between 38 4 1 and 53 5 ka from the basal half of the roxana silt and six age estimates between 18 2 and 25 3 ka from the basal half of the peoria loess are consistent with numerous finite radiocarbon dates from around the central mississippi valley thermoluminescence age estimates suggest that the oldest of the intra loveland loess units is 127 12 ka one age and may have been deposited during marine oxygen isotope stage 6 the younger two of these loess units were deposited between 113 10 and 70 6 ka three ages this latter age range for loess that underlies the top of the presumed sangamon soil is problematic because it requires that pedogenesis may have begun as late as approximately 70 ka moreover loess deposited between about 120 and 70 ka suggests that the southern margin of the laurentide ice sheet was within some part of the upper mississippi valley during this interval this conflicts with some glacial geologic evidence but it is consistent with global sea level and 18o records of ice volume which indicate several intervals of moderate glaciation during this time

evidence for multiple episodic mid holocene hypsithermal recorded in two soil profiles along an alluvial floodplain catena southeastern tennessee usa abstract floodplain soil paleosol successions are valuable archives for reconstructing pleistocene holocene climate changes but have been relatively unstudied in the southern appalachian region two soil profiles on a small floodplain in southeastern tennessee usa were described and sampled in detail using both pedological and geological approaches including stable carbon isotope analysis of soil organic matter som correlation between the 2 profiles was constrained by uncalibrated ams 14c ages of bulk humates and using som 13c values both mobile and immobile elements four distinct 2 5 4 shifts towards less negative 13c values for som suggest 300 yr cyclicity and transient warmer and drier climate events with either water stressed c3 vegetation or as much as 35 c4 plants present during the mid holocene these postulated multi episodic drier climate conditions have never before been documented in the southern appalachian region and are tentatively correlated with mid holocene warming and drying in the eastern us the nearly time equivalent mid holocene events documented in texas the us high plains and in the gulf of mexico high rates of floodplain sediment accumulation 0 5 3 mm yr high clay content and maintenance of poorly drained soil conditions favor preservation of high resolution climate archives in floodplain deposits by inhibiting oxidation and translocation of organic c

sedimentological and petrographical characteristics of cretaceous strandplain coals a model for coal accumulation from the north american western interior seaway abstract coal seams formed on many cretaceous wave dominated strandplain sediments in north america are characterized by great lateral continuity tens to hundreds of kilometres substantial thicknesses up to 12 m relatively low ash and sulphur contents the coals formed behind an active shoreline in areas undergoing subsidence due to shale compaction and dewatering the zone of peat accumulation was remote from the shoreline and storm tidal inundations and generally protected from fluvial flooding if the rate of subsidence was too great lakes formed and peat did not accumulate statistical evaluation of petrographic properties by correspondence analysis of the lower cretaceous coals show that the strandplain coals form distinctive petrographic groups that are characterized by relatively low vitrinite contents and high inertinite contents semifusinite and inertodetrinite dominate in the inertinite maceral group liptinite contents are negligible tissue preservation indices and gelification indices indicate for the strandplain coals a forest type paleodepositional environment in which a relatively low water table allowed the accumulation of oxidized and partly oxidized components fusinite and semifusinite significant amounts of detrital components such as inertodetrinite and vitrinite b are diagnostic that some transportation of the organic material took place prior to deposition comparison of coal facies and depositional environments from permian coals of australian show that the lower cretaceous strandplain coals have petrographic similarities to coals that were formed under regressive back barrier conditions in the permian due to differences in nomenclature previously interpreted regressive back barrier environments may be similar to the strandplain environments discussed here

the age palaeoclimate palaeovegetation coal seam architecture mire types paleodepositional environments and thermal maturity of syn collision paralic coal from mukah sarawak malaysia abstract the mukah coal accumulated in the balingian formation where the time stratigraphic position is poorly defined by fauna though a probable late miocene age has always been assigned to this formation samples collected in the present study that yielded an abundance of casuarina pollen associated with occurrences of dacrydium stenochlaena palustris florschuetzia levipoli and also stenochlaena areolaris spores compare closely to zone pr9 of the palynological zonation of the malay basin and can be tied to depositional sequences of malay basin seismic sequences i2000 i3000 indicating an early miocene age for the studied coal the early miocene age shows that the mukah coal was formed during the collision between luconia block dangerous grounds with the borneo that lasted from late eocene to late early miocene the rapid increase of deposition base level caused by the collision is clearly reflected by the architecture of the mukah coal seams that were generally thin and also by the reverse order of the paleo peat bodies the studied coal samples contained large amounts of detrohuminite without the enrichment of liptinite group macerals usually explained by the dominance of herbaceous plants in the paleomires however the pollen assemblages recovered in the present study provide no support for a herbaceous swamp instead the peats were likely formed mainly from forest vegetation based on the recovery of dominant arboreal pollen assemblages in the present study palynomorph assemblages recovered in the present study with abundance of casuarina pollen associated with common occurrences of dacrydium strongly suggest kerangas vegetation and kerapah type peat swamps indicating a very wet climate the occurrence of rattan and pandanus pollens shows that the kerapah type peat swamps were locally bordered by rattan and pandanus swamps this shows that the prevailing use of coal petrography to discern the type of vegetation that was present in the peat forming mires may lead to wrong conclusions therefore a multi disciplinary approach must be applied for a more accurate and reliable spatial interpretation of the type of vegetation that was present in the peat forming mires consistent with the low sulphur content evidence from the palynomorph assemblages recovered from the coal seams shows that the coal forming peat was deposited in freshwater mires with little or no marine influence despite the fact that the accumulation of the mukah coal forming peat took place within a coastal plain setting moreover the fauna present in the host rock formation also suggested a brackish water environment of deposition

paleoecology of central kentucky since the last glacial maximum pollen grains and spores plant macrofossils and sponge spicules from a 7 2 m sediment core from jackson pond dating back to 20 000 yr b p are the basis for new interpretations of vegetational limnological and climatic changes in central kentucky during the full glacial interval 20 400 to 16 800 yr b p upland vegetation was closed spruce forest with jack pine as a subdominant aquatic macrophyte and sponge assemblages indicate that the site was a relatively deep open pond with low organic productivity during late glacial time 16 800 to 11 300 yr b p spruce populations continued to dominate while jack pine declined and sedge increased as the vegetation became a more open taiga like boreal woodland between 11 300 and 10 000 yr b p abundances of spruce and oak pollen oscillated reciprocally possibly reflecting the younger dryas oscillation as boreal taxa underwent a series of declines and increases at the southern limit of their ranges before becoming extirpated and replaced by deciduous forest in the early holocene 10 000 to 7300 yr b p a mesic deciduous woodland developed it was replaced by xeric oak hickory forest during the middle holocene between 7300 and 3900 yr b p grass increased after 3900 yr b p indicating that the presettlement vegetation mosaic of mixed deciduous forest and prairie the kentucky barrens became established in central kentucky after the hypsithermal interval sponge spicules increased in number during the holocene reflecting reduced water depths in the pond sediment infilling as well as climatic warming and the expansion of fringing shrub thickets increased nutrient and habitat availability for freshwater sponges

changing patterns of pennsylvanian coal swamp vegetation and implications of climatic control on coal occurrence abstract improved regional and interregional stratigraphic correlations of pennsylvanian strata permit comparisons of vegetational changes in euramerican coal swamps the coal swamp vegetation is known directly from in situ coal ball peat deposits from more than 65 coals in the united states and europe interpretations of coal swamp floras on the basis of coal ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps changes in composition of pennsylvanian coal swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate paleobotany and paleogeography of the euramerican province indicate a moist tropical paleoclimate rainfall runoff and evapotranspiration were the variable climatic controls in the distribution of coal swamp vegetation peat accumulation and coal resources in relative terms of climatic wetness the pennsylvanian period is divisible into five intervals which include two relatively drier intervals that developed during the lower middle and middle upper pennsylvanian transitions the climate during early pennsylvanian time was moderately wet and the median in moisture availability early middle pennsylvanian was drier probably seasonally dry wet late middle pennsylvanian was the wettest in the midcontinent early late pennsylvanian was the driest and late late pennsylvanian was probably the wettest in the dunkard basin the five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation regional differences in basinal geology and climate were significant variables but the synchronous control of paleoclimate was of primary importance

radiocarbon analyses from cincinnati ohio and their implications for glacial stratigraphic interpretations abstract detailed analysis of a site near cincinnati ohio shows that 14c ages of samples in a single geologic unit can have a range of several thousand years and ages from different stratigraphic units can overlap at the sharonville site four 14c samples from organic silt below glaciogenic deposits have an inverted chronologic sequence suggesting contamination but nevertheless they indicate the silt was deposited before 27 000 yr b p a stump cluster in growth position wood fragments and moss from the upper surface of the silt may differ by as much as 2300 14c yr five ages from the stump cluster constrain the timing of a glacier advance of the laurentide ice sheet to its southern limit in the cincinnati area at 19 670 68 yr b p overlying glaciogenic sediments contain transported wood that may be as much as 3200 yr older than the advance this range of ages points out that for a given site several age measurements are required to determine when a glacier advance occurred because the measured ages in this study span the entire interval suggested for a twofold sequence of advance retreat and readvance of the margin of the miami sublobe we suggest a single advance to its terminal position in the cincinnati area as an alternate hypothesis for testing

paleopedology plus tl 10be and 14c dating as tools in stratigraphic and paleoclimatic investigations mississippi river valley u s a thick 35 m loess deposits are present on ridges and high bluffs in the northern half of the lower mississippi valley lmv u s a detailed descriptions of the loess sections and pedologic physiochemical and mineralogic analyses and tl 14c and 10be age determinations allow preliminary paleoclimatic reconstructions for the late quaternary of central north america no age data are available for the oldest fifth loess 10be and tl age data suggest a 250 200 ka age for the fourth or crowleys ridge loess and indicate that the loveland or third loess is time equivalent to oxygen isotope stage 6 190 120 ka a weakly developed paleosol is present in the basal half of the loveland the sangamon geosol is present in the upper 5 m and represents all of oxygen isotope stage 5 130 60 ka it formed in a climate as warm as but drier and or with greater variation in precipitation than the present the roxana silt second loess was deposited during oxygen isotope stages 4 and 3 65 26 ka the early wisconsinan interglacial glacial transition represented by the sangamon geosol and the unnamed paleosol in the basal roxana silt was slow the paleoclimate during the 35 k yr of roxana deposition was cool to cold and wet age and pedologic data indicate that deposition of the peoria loess the youngest began around 25 ka when the area s climate changed abruptly from cool or cold and wet to cold and dry with periods of sustained high winds

post impact event bed tsunamite at the cretaceous palaeogene boundary deposited on a distal carbonate platform interior we show crucial evidence for the cretaceous palaeogene k pg boundary event recorded within a rare succession deposited in an inner platform lagoon on top of a mesozoic tropical intra oceanic western tethys adriatic carbonate platform which is exposed at likva cove on the island of brac croatia the last terminal maastrichtian fossils appear within a distinct 10 12 cm thick event bed that is characterized by soft sediment bioturbation and rare shocked quartz grains and is interpreted as a distal tsunamite directly overlying this is a 2 cm thick reddish brown clayey mudstone containing planktonic foraminifera typical of the basal danian and with elevated platinum group elements in chondritic proportions indicating a clear link to the chicxulub asteroid impact these results strongly support the first discovery of a potential k pg boundary tsunamite on the neighboring island of hvar and these two complementary sections represent probably the most complete record of the event among known distal shallow marine successions

initiation and development of the laurentide and cordilleran ice sheets following the last interglaciation abstract fossil records from sites overridden by or adjacent to the laurentide ice sheet indicate that the climate of the last interglaciation oxygen isotope substage 5e ca 130 116 ka was warmer than today following the last interglaciation the laurentide ice sheet first developed during stage 5 over keewatin quebec and baffin island along its northern margin the ice sheet reached its maximum extent of the last glaciation during stage 5 the ice sheet advanced across baffin island onto the continental shelf early during stage 5 5d whereas the advance into the western canadian arctic occurred late during stage 5 5b the ice sheet also may have advanced into the st lawrence lowland during substage 5b although this event may be younger stage 4 the hudson bay lowland became ice free during substage 5a retreat of the ice sheet on baffin island occurred during late stage 5 probably substage 5a the exact timing of retreat from the western canadian arctic is unknown but it occurred before 48 ka the southern sector including the st lawrence lowland was ice free during late stage 5 the hudson bay lowland may have remained ice free through stage 4 and much of stage 3 because of conflicting chronologies however it is more likely that this area was glaciated throughout stage 3 and perhaps stage 4 nevertheless the data demonstrate that the lowland was ice free during part of the last glaciation an independent ice cap developed over the appalachian uplands and advanced across nova scotia during stage 4 perhaps as far as the edge of the continental shelf the ice cap remained active over nova scotia as a setellite to the laurentide ice sheet throughout the remainder of the last glaciation the ice sheet advanced into the st lawrence lowland during stage 4 and subsequently overwhelmed the local ice cap in the appalachian uplands advancing perhaps into northern new england but not farther south the lowland remained covered by the ice sheet until late stage 2 the ice sheet may also have advanced into the lake ontario basin during stage 4 the position of the northern margin of the laurentide ice sheet during stage 4 is not known but it remained an unknown distance behind its maximum position reached during stage 5 cores from baffin bay indicate a substantial decrease in high latitude glaciation during stage 4 following retreat the keewatin sector of the ice sheet may have remained over much of northwestern canada as a quasi stable ice mass until it readvanced during stage 2 similarly the baffin island sector of the ice sheet may have remained largely intact the southern margin of the ice sheet may have advanced into the lake ontario basin and upper mississippi valley during the middle of stage 3 ca 50 ka reaching its maximum extent of the last glaciation during stage 2 ca 18 21 ka advance of the northern margin was younger ca 8 13 ka than that of the southern margin this advance was less extensive than the penultimate advance stage 5 paleoenvironmental records indicate that the last interglaciation in areas covered by and near the cordilleran ice sheet was as warm as or warmer than present the cordilleran ice sheet appears to have developed during stage 5 or 4 at that time it advanced over southern british columbia and into the northern puget lowland there is no record of this event in northern areas that were later covered by the ice sheet the ice sheet disappeared before 59 ka at the beginning of a lengthy nonglacial interval paleoenvironmental records indicate that climate was similar to the present during part of this interval the ice sheet was absent and glaciers probably were confined to mountain areas throughout stage 3 climatic deterioration marking the end of this nonglacial interval may have begun as early as 29 ka by 14 15 ka the ice sheet had achieved its maximum extent of the last glaciation because there are few suitable dating methods capable of resolving events beyond the radiocarbon limit and because sites that preserve a record of events from the last glaciation are spatially restricted we consider this synthesis as tentative and subject to significant revision as dating methods improve nevertheless this perspective of the north american ice sheets through the last glaciation demonstrates their complex and dynamic behavior and attendant rapid fluctuations in ice volume

mapped plant macrofossil and pollen records of late quaternary vegetation change in eastern north america abstract macrofossil presence absence maps and isopoll maps in 3000 year intervals show how ranges and abundance maxima for 12 eastern north american tree and shrub taxa picea p glauca p mariana larix laricina abies balsamea tsuga canadensis pinus strobus p resinosa p banksiana betula papyrifera b alleghaniensis b series humiles have changed from the last glacial maximum to the present the macrofossil maps corroborate patterns shown by the isopoll maps and provide spatial detail and taxonomic resolution the macrofossils confirm the inference from pollen data that unglaciated southeastern north america was cooler during the last glacial maximum 18 and 15 ka than simulated by the cohmap experiments with the ncar ccm0 general circulation model the geographic distribution of macrofossil occurrences during the late glacial 12 and 9 ka indicate that migration lag of boreal species did not occur at regional to subcontinental scales and that pollen assemblages lacking modern analogs resulted from climate gradients lacking modern analogs early holocene 9 and 6 ka macrofossil maps show rapid northward expansion of tree species ranges into deglaciated regions the data also show modest contractions of northern range limits of temperate species and expansions of southern range limits of boreal species in response to cooling trends during the late holocene 3 and 0 ka comparison of modern macrofossil maps of nine of these taxa with corresponding range maps confirm that the macrofossils record the geographic ranges accurately comparison of the modern macrofossil maps with maps of tree growing stock volume shows that for some taxa abies tsuga macrofossil occurrences were most frequent in regions of maximum tree abundance comparison of modern isopoll maps with the modern range and growing stock volume maps indicate that in contrast to the macrofossil data the pollen data provide poorer resolution of range limits for most taxa but better indications of abundance maxima and minima within the ranges

crustal uplift in southern england evidence from the river terrace records abstract much of the past work on the quaternary rivers of northwest europe has been concerned with river terraces which characterise almost every valley while these terraces are undoubtedly striking features of the landscape the incision achieved by quaternary rivers is equally significant in terms of river behaviour and for an understanding of the factors affecting landform development during the quaternary this paper examines the incision achieved during the quaternary by the thames in both its upper and lower catchments and by the hampshire avon in southern england valley incision rates of ca 0 07 0 10 m ka 1 have been identified although in the lower catchment of the thames these have been enhanced by additional incision in response to glacio isostasy and valley shortening a model is proposed in which regional uplift is recognized as the primary cause of incision by these quaternary rivers possible mechanisms for regional uplift are considered

petrology palynology coal facies and depositional environments of an upper carboniferous coal seam minto coalfield new brunswick canada coal petrology and palynology of the minto coal seam enable depositional environments of the precursor mire to be established in terms of facies critical maceral ratios maceral assemblages and spore and pollen assemblages the overall petrographic composition indicates a vitrinite rich coal mean 67 followed by inertinite mean 27 and liptinite mean 7 pyrite is common to abundant maximum 15 lithotype logs demonstrate a dominance of dull lithotypes dull and banded dull petrographic composition at the lithotype and seam subsection level is highly variable vitrinite maceral assemblages are enriched in brighter lithotypes banded bright and bright whereas liptinite and inertinite maceral assemblages are enriched in dull and banded dull lithotypes the duller lithotypes are enriched by mineral matter based on spores the seam is assigned to the vestispora zone of atlantic canada with the basal torispora securis torispora laevigata sl zone of western europe and the lower torispora secur

holocene climate variability although the dramatic climate disruptions of the last glacial period have received considerable attention relatively little has been directed toward climate variability in the holocene 11 500 cal yr b p to the present examination of similar to50 globally distributed paleoclimate records reveals as many as six periods of significant rapid climate change during the time periods 9000 8000 6000 5000 4200 3800 3500 2500 1200 1000 and 600 150 cal yr b p most of the climate change events in these globally distributed records are characterized by polar cooling tropical aridity and major atmospheric circulation changes although in the most recent interval 600 150 cal yr b p polar cooling was accompanied by increased moisture in some parts of the tropics several intervals coincide with major disruptions of civilization illustrating the human significance of holocene climate variability c 2004 university of washington all rights reserved

palynological correlation of major pennsylvanian middle and upper carboniferous chronostratigraphic boundaries in the illinois and other coal basins

control of coal facies to adsorption desorption divergence of coals a case from the xiqu drainage area gujiao cbm block north china abstract adsorption and desorption of coal to methane are substantially related to coal facies referring to the production potential of a coalbed methane cbm well based on analyses of the stratified channel samples from coal seams no 2 no 4 and no 9 in the xiqu drainage area gujiao cbm block north china the relationship between coal facies and adsorption desorption behaviors was first proposed and discussed using the coal facies diagrams suggested by previous investigators four types of coal facies were distinguished in the coal seams including the upper delta plain wet forest swamp i the lower delta plain fen ii the lower delta plain marsh iii and the back barrier low moor iv the upper delta plain wet forest swamp occurred dominantly developing at the bottom and top of all the coal seams both the ash yield and groundwater index gwi tend to increase from coal facies i to iv whereas the volatile compounds fixed carbon organic sulfur total sulfur micropore volume and specific surface area tissue preservation index tpi and vegetation index vi decreased which indicates changes in the vegetation types water supplements and disturbance acid base properties and redox conditions in the paleomires paleomire evolution accompanied the rise and drop of the sea level with a transgression or regression process that could be represented by the coal facies sequence coal seams no 2 no 4 and no 9 were discriminated into two three and two evolving stages respectively and these stages were characterized by complete cycles except stage 4 i from the lower delta plain marsh mudstone partings in the coal seams deposited during the highest sea level collectively paleomire environments especially the variation of vegetation types and mire water condition result in adsorption and desorption divergences among different coal facies arborescent plants decrease from coal facies i to iv as the hydrodynamic intensity increases leading to corresponding changes in botanical tissue preservation medium oxidizability mineral content and ultimately adsorption and desorption behaviors in view of the gas content and desorption capacity of the coal layers in the same coal seam the layers from the upper delta plain wet forest swamp may have the best potential for cbm drainage followed by those from the lower delta plain fen and marsh while those from the back barrier low moor may have the worst potential

lacustrine sediments in porter cave central indiana usa and possible relation to laurentide ice sheet marginal positions in the middle and late wisconsinan abstract proglacial lakes formed in the late quaternary with the advance of the laurentide ice sheet into mill creek valley of central indiana these lakes backfilled into the mouth of porter cave deposited organic matter and thinly bedded silty sediment that conforms to the underlying cave floor and shelves optical and radiocarbon ages indicate that deposition of fine grained sediments into porter cave occurred in two proglacial lake phases during marine oxygen isotope stage mis 3 ca 40 to 30 cal ka and mis 2 ca 27 to 18 cal ka the latter phase is consistent with other proxy evidence for ice sheet extent and timing we contend that the ice sheet lobe that dammed a proglacial lake during mis 3 in central indiana was 7 km behind the last glacial maximum limit based on current topography this conclusion is in opposition to previous assessments which infer ice free conditions in central illinois and central indiana ca 130 to 25 ka the paucity of mis 3 deposits may be due to erosion by the more extensive mis 2 ice sheet with glacial lacustrine sediments preserved in the protective confines of porter cave this outlet lobe in central indiana may be short lived and reflects a variable response of lobes of the laurentide ice sheet during mis 3 with expansion possibly associated with cooling during heinrich event 4

luminescence dating applications in geomorphological research abstract chronological control remains critical to the interpretation of environmental change and to establishing long term rates of geomorphological processes radiocarbon dating will continue to be the central technique for age assessment of carbon bearing sediments deposited in the last ca 40 ka but alternative absolute dating strategies are required for older or non carbon bearing sediments they include uranium series dating of precipitated sediments k ar and ar ar dating of primary volcanic materials and cosmogenic isotopic dating of surface exposure ages an additional family of methods collectively termed luminescence techniques is increasingly providing a basis for the age assessment of detrital sedimentary deposits these methods directly date the deposition of detrital mineral grains typically quartz and feldspar and have been demonstrated to provide accurate deposition chronologies for up to 800 ka although 150 ka is more typical in the past decade a subset of luminescence techniques which employ optical sample stimulation methods called optical dating has made it possible to date samples from a much wider range of depositional systems given that the methods directly date sedimentation they allow direct assessment of depositional dynamism in numerous terrestrial and subaqueous including marine sedimentary systems and have demonstrated particular potential in the elucidation of chronologies from aeolian dune and loess fluvial colluvial coastal and volcaniclastic environments this paper provides a summary of the principles of the luminescence especially optical dating methods and shows how recent developments specifically single aliquot dating procedures have dramatically enhanced the scope and potential of the method the luminescence techniques are increasingly being incorporated into a wide range of geomorphological studies which seek to establish the nature of landscape changes over the past interglacial glacial cycle and beyond

an optical age chronology of late pleistocene fluvial deposits in the northern lower mississippi valley the lower mississippi valley lmv contains many large braided channel belts that are preserved west of the holocene floodplain previous efforts to establish geochronologic control on channel belt construction have been hindered by the lack of organic material for radiocarbon dating luminescence techniques provide a burial date for the sediment itself and may prove useful in this context samples from three channel belts in the northern lmv were analyzed using the single aliquot regenerative technique on 90 125mm quartz optical ages 19 7 17 8 16 1 15 0 and 12 5 12 1 ka are consistent with geomorphic relationships and indicate that channel belts were formed in the late pleistocene under glacial conditions these optical ages provide the first detailed chronology of lmv channel belt formation and are the first step towards developing a chronology for the entire lmv r 2003 elsevier science ltd all rights reserved

late pleistocene and holocene climate and geomorphic histories as interpreted from a 23 000 14c yr b p paleosol and floodplain soils southeastern west virginia usa abstract field micromorphological pollen whole soil xrf and stable isotope geochemical methods were used to evaluate the latest pleistocene to holocene climate record from a floodplain terrace system in southeastern west virginia a late pleistocene 22 940 150 14 c yr b p silt paleosol with low chroma colors formed from fluviolacustrine sediment deposited during the last glacial maximum wisconsinan and records a cooler full glacial paleoclimate fluvial gravel deposited between the latest pleistocene and earliest holocene prior to 6360 40 14 c yr b p was weathered in the middle holocene under warmer drier climate conditions possibly correlated with the hypsithermal and altithermal events of the eastern and southwestern united states respectively the glacial to interglacial climate shift is recorded by 1 changes from a poorly drained landscape with fine textured soil characterized by high organic c and redoximorphic features related to fe removal and concentration to a well drained coarse textured setting without gley and with significant argillic bt horizon development 2 changes from a high zr and ti silt dominated parent material to locally derived coarse fluvial gravels lower in zr and ti 3 a shift from dominantly conifer and sedge pollen in the paleosol to a modern oak hickory hardwood assemblage and 4 a shift in 13 c values of soil organic matter from 28 to 24 pdb suggesting an ecosystem shift from cooler c3 dominated flora to one that was mixed c3 and c4 but still predominantly composed of c3 plants a root restrictive placic horizon developed between the late pleistocene silt paleosol and the overlying fluvial gravel because of the high permeability contrast between the two textures of soil materials this layer formed a barrier that effectively isolated the pleistocene paleosol from later holocene pedogenic processes

high resolution proxy record of holocene climate from a loess section in southwestern nebraska usa abstract multi proxy analysis was used to produce a high resolution paleoclimatic record from an exceptionally thick section of the holocene bignell loess near wauneta southwestern nebraska in the central great plains the wauneta section has excellent age control based on optically stimulated luminescence osl and radiocarbon dating and records multiple episodes of rapid loess deposition alternating with slower deposition and soil formation the lowermost and uppermost osl ages obtained from the bignell loess are 10 250 610 years 5 9 m depth and 100 10 years 0 1 m depth respectively as a result the holocene has been temporally confined stratigraphically the bignell loess overlies the late pleistocene peoria loess deposited 21 14 ka and the two units are separated by the brady soil which is distinguished by its color and other pedogenic features l a b color parameters and organic carbon content of bignell loess are sensitive proxies to differentiate drought induced aeolian sediment layers from the intercalated soil horizons soil organic carbon derived 13 c data suggest that the c 3 dominated floral environment during peoria loess deposition shifted dramatically to a c 4 dominated environment during brady soil formation in response to a warming trend even greater c 4 abundance characterized the late holocene high resolution 13 c data support the contention that c 3 vs c 4 vegetation change in the holocene reflects ecosystem response to frequent vegetation disturbance under arid conditions time series analysis reveals that 13 c and color parameters display high frequency variation with periodicities of 103 118 years and 103 years respectively similar periodicities were also reported in studies of north dakota lakes though the physical mechanism responsible is uncertain comparison of bignell loess color and tropical pacific sea surface temperatures ssts allows evaluation of a proposed teleconnection between drought in the great plains and la nina like conditions in the tropical pacific the loess color index and eastern tropical pacific sst display broad similarities through the late pleistocene and holocene that are consistent with this teleconnection on the other hand drought centered at 3800 years ago is not consistent with the teleconnection and the end of early holocene aridity at the wauneta section around 6500 years ago is much earlier than the corresponding rise in sst and increase in el nino frequency in the eastern tropical pacific

mid to late holocene climate change an overview the last 6000 years are of particular interest to the understanding of the earth system because the boundary conditions of the climate system did not change dramatically in comparison to larger glacial interglacial changes and because abundant detailed regional palaeoclimatic proxy records cover this period we use selected proxy based reconstructions of different climate variables together with state of the art time series of natural forcings orbital variations solar activity variations large tropical volcanic eruptions land cover and greenhouse gases underpinned by results from general circulation models gcms and earth system models of intermediate complexity emics to establish a comprehensive explanatory framework for climate changes from the mid holocene mh to pre industrial time the redistribution of solar energy due to orbital forcing on a millennial timescale was the cause of a progressive southward shift of the northern hemisphere nh summer position of the intertropical convergence zone itcz this was accompanied by a pronounced weakening of the monsoon systems in africa and asia and increasing dryness and desertification on both continents the associated summertime cooling of the nh combined with changing temperature gradients in the world oceans likely led to an increasing amplitude of the el nin o southern oscillation enso and possibly increasingly negative north atlantic oscillation nao indices up to the beginning of the last millennium on decadal to multi century timescales a worldwide coincidence between solar irradiance minima tropical volcanic eruptions and decadal to multi century scale cooling events was not found however reconstructions show that widespread decadal to multi century scale cooling events accompanied by advances of mountain glaciers occurred in the nh e g in scandinavia and the european alps this occurred namely during the little ice age lia between ad w1350 and 1850 when the lower summer insolation in the nh due to orbital forcing coincided with solar activity minima and several strong tropical volcanic eruptions the role of orbital forcing in the nh cooling the southward itcz shift and the desertifi cation of the sahara are supported by numerous model simulations other simulations have suggested that the fingerprint of solar activity variations should be strongest in the tropics but there is also evidence that changes in the ocean heat transport took place during the lia at high northern latitudes with possible additional implications for climates of the southern hemisphere sh

the geology petrology palynology and geochemistry of permian coal basins in tanzania 2 songwe kiwira coalfield abstract this study provides coal quality petrological palynological and geochemical rock eval data on permian coal seams and associated shales and mudstones of the karoo supergroup of the songwe kiwira coalfield tanzania the coal seams which have a cumulative thickness of 6 80 m occur in the shale coal sandstone facies of the mchuchuma formation of artinskian to kungurian age coal quality data calorific values volatile matter contents and vitrinite reflectances indicate high volatile c bituminous to high volatile a bituminous coals having relatively high ash yields 22 49 wt and highly variable sulphur contents 0 17 9 2 wt they could be used to fuel small scale power generation units thereby providing electricity to nearby towns and villages also the coals could be used as a substitute for wood which is becoming increasingly scarce in rural tanzania charcoal is still the main energy source for cooking and wood is used extensively in brick kilns and for making roofing tiles petrological analysis indicated that the coals are dominated by dull to banded dull lithotypes with seams at the base of the mchuchuma formation enriched in inertinite macerals up to 83 vol whereas up section vitrinite contents increase palynological analyses indicated that the assemblage in the lower mchuchuma formation scheuringipollenites assemblage is dominated by trilete spores whereas in the remainder of the section non taeniate disaccates dominate scheuringipollenites protohaploxypinus assemblage facies critical macerals suggest for most seams a marsh wet forest swamp depositional setting which is consistent with the palynological data rock eval analyses indicate type ii iii kerogen with tmax c values ranging from 426 to 440 corresponding to the early stage of hydrocarbon generation thermal alteration indices 2 to 2 and vitrinite reflectance levels 0 60 0 83 ro support the rock eval maturity assessment and despite the predominance of terrestrial derived organic matter there is evidence of oil generation and expulsion in the form of cavity and fracture filling exsudatinite

a fault controlled newly discovered eskisehir alpu coal basin in turkey its petrographical properties and depositional environment abstract recent findings suggest that turkey contains about 15 billion tons of coal within its borders a small proportion of it nw part is bituminous but the rest is sub bituminous and lignite coal about 80 of the coals are utilized in power generation the newly found coal field alpu basin contains about 1 3 billion tons of coal the coal basin is a fault controlled and deeply buried basin which is close to the industrial areas in turkey in the studied area there are two coal horizons in the middle miocene aged m2 unit the average mineable coal seam thickness is approximately 13 14 m in order to determine the coalification degree petrographic composition and depositional environment of the coals petrographic and xrd analyses were conducted on coal samples taken from three boreholes which were drilled by mta in the eskisehir alpu basin according to the astm classification the rank of the coals is sub bituminous alpu coals contain two prominent types of maceral assemblages either containing high amounts of funginites macrinites ulminite and gelinites or high amounts of liptinites associated with detrital huminites attrinite and densinites the first type exhibits rather more homogeneous features but the second has a more complex mixed appearance with detrital macerals intensive lineation laminations and considerably higher pyrite contents the alpu coals contain montmorillonite heulandite quartz pyrite gypsum kaolinite illite illite montmorillonite orthoclase and clay minerals which indicate variation in the ph conditions the tissue preservation index tpi and gelification index gi indicate a limnic environment the sample points are located between open marsh and clastic marsh areas on the tpi gi diagram this case indicates that the water table was variable during the coal formation

variations in loess accumulation rates in the mid continent united states as reflected by magnetic susceptibility detailed magnetic susceptibility records of late wisconsin loess sequences in the southwest indiana region show several distinct changes in magnitude that reflect variations in loess accumulation rate the comparison of the magnetic susceptibility signal and sedimentary features within the loess reveal the following relations 1 low magnetic susceptibility values correspond to incipient paleosols that record periods of low loess accumulation rates 2 highly variable values within intermediate to high magnetic susceptibility zones correspond to stratified loess that represents periods of high loess accumulation rates and 3 moderate to high magnetic susceptibility values correspond to massive loess that may reflect periods of moderate to high loess accumulation rates we suspect that soil moisture controls the loess accumulation rate and if so our work shows that soil moisture alternated about 24 times between 25 and 14 ka in the middle of north america

uplift driven valley incision and climate controlled river terrace development in the thames valley uk abstract the sequence of terraces of the river thames in southeast england has previously been shown to span the period from the earliest pleistocene to the present this terrace sequence contains biostratigraphical and sedimentary evidence that testifies to the high amplitude climatic changes of the quaternary large scale fluvial incision resulting in basin wide terrace formation appears to have been concentrated at the warming limbs of the major climatic glacial interglacial cycles when sediment supply was greatly reduced this incision and subsequent valley floor widening created the accommodation space for the later aggradation of the terrace sediments during the following warm cold transitions and during the cold stages when high sediment supply conditions prevailed although the timing of terrace aggradation may be controlled by climate change the progressive valley incision recorded by terrace staircases cannot easily be explained in terms of quaternary climatic change alone and recently developed models suggest that long term incision by the thames has been driven by uplift this paper presents an overview of the available terrace data and tabulates incision amounts and rates between key stratigraphic horizons superimposed upon these broad changes revealed by the complex internal sedimentary architecture of many terrace sediments are the geomorphological system responses to both higher frequency climate driven changes and more localized intrinsic fluvial system adjustments

pliocene pleistocene incision of the green river kentucky determined from radioactive decay of cosmogenic 26al and 10be in mammoth cave sediments cosmogenic 26al and 10be in sediments washed into mammoth cave kentucky record the history of 3 5 m y of water table position governed by incision and aggradation of the green river a tributary of the ohio river upper levels of the cave formed during a period of slow river incision and were later filled with sediment due to river aggradation at 2 3 2 4 ma a brief surge of river incision ca 2 ma was followed by river stability and cave passage formation at a lower level rapid incision through 15 m of bedrock ca 1 5 ma was prompted by repositioning of the ohio river to its present course along an ice sheet margin renewed incision ca 1 2 ma and aggradation at 0 7 0 8 ma correlate with major ice advances in the ohio river basin measurements of 26al and 10be also indicate that sandstone capped uplands have maintained slow erosion rates of 2 7 m m y for the past 3 5 m y despite accelerated pleistocene river incision rates of 30 m m y

development of an osl chronology for late pleistocene channel belts in the lower mississippi valley usa abstract the broad alluvial valley of the lower mississippi river contains large channel belts for which age control has been limited by the lack of organic material for radiocarbon dating and deposit ages greater than the limit of radiocarbon in order to produce a detailed chronology of fluvial evolution samples for optical dating were collected from late pleistocene channel belt deposits quartz sand was analyzed using the coarse grained single aliquot regenerative dose sar technique samples showed little evidence of partial bleaching and optical ages are for the most part consistent with the available radiocarbon and relative age constraints optical ages range from 85 to 11 ka and along with geomorphic and stratigraphic relationships indicate that the mississippi river was meandering during the end of the last interglacial 85 83 ka and switched to a braided regime by 64 50 ka during initial marine oxygen isotope stage ois 4 3 glaciation of the upper mississippi drainage basin the mississippi river switched back to a meandering regime after formation of the youngest braid belt at 11 ka the 69 optical ages presented here provide the first detailed chronology of lower mississippi valley braid belt and pleistocene meander belt formation and provide an example of the utility of optical dating in fluvial settings where material for radiocarbon dating is scarce

coal facies interpretations based on lithotype and maceral variations in lower cretaceous gates formation coals of western canada abstract maceral analyses of lithotype samples from lower cretaceous coal seams have been used to define compositional characteristics of the various lithotypes and to assess coal facies changes within the seams based on maceral and lithotype variations the mean petrographic compositions of the lithotypes show a general trend to decreasing vitrinite increasing inertinite and increasing mineral matter contents from the bright to dull varieties the bright lithotypes are considered to have been formed in wet and densely forested swamps whereas the banded lithotypes were formed under somewhat drier conditions within the dull lithotype two distinct types were recognized based on differences in petrographic composition and the occurrence or absence of facies diagnostic macerals it is suggested that these differences are due to formation in distinct mire facies under the influence of open moor or raised mire conditions the lithotype variations within the seams together with the data on their petrographic composition were used to define facies changes which occurred during accumulation of the peats three types of seam development are recognized a seams containing a high proportion of clastic beds indicative of frequent floodings of the swamps these seams are characterized by the dominance of oscillatory sequences of bright lithotypes and dulling upward sequences below clastic beds the brighter lithotypes were formed in forested swamps and fens whereas for the duller sequences influences of open moor conditions are indicated b seams containing only minor thin clastic beds indicating relative stability of water levels during formation of the peat these seams are characterized by the predominance of duller lithotypes with common repetitions of dulling upward sequences the dulling up sequences indicate transitions from wet and very wet forest swamps to drier conditions with lower tree density c transitional seams characterized by a few clastic beds these seams formed under intermediate conditions of stability in respect to flooding events the seams are characterized by the predominance of banded lithotypes dull lithotypes near partings and brightening and dulling up sequences the brightening up sequences represent transitions from dry forest swamp to wet and very wet forest swamps while a reverse trend is indicated for the dulling up sequences the overall petrographic characteristics of full seam sections indicate that the seams are in general relatively low in vitrinite and relatively rich in inertinite macerals liptinite content is negligible and mineral matter contents are low based on petrographic indices obtained from facies diagnostic macerals an accumulation of the ancient peats under prevailing wet to very wet forest swamps is suggested vicinity to more open moor conditions is indicated for one seam by the higher input of dispersed macerals

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research