pace of landscape evolution in the sierra nevada california revealed by cosmogenic dating of cave sediments we report 26 al 10 be based ages of sierra nevada caves that constrain detailed late pliocene and quaternary river incision his tories for five river canyons rapid incision of 0 2 mm yr from 2 7 to ca 1 5 ma slowed markedly to 0 03 mm yr thereafter likely reflecting the combined effects of a transient erosional re sponse to pliocene rock uplift and periodic mantling of riverbeds with glacially derived sediment in the late quaternary while 400 m of incision has occurred in the past 2 7 m y outpacing interfluve erosion and thereby increasing the local relief canyons as deep as 1 6 km existed prior to that time these new erosion rates strength en the case for tectonically driven late cenozoic uplift

hydrogen isotopes in eocene river gravels and paleoelevation of the sierra nevada we determine paleoelevation of the sierra nevada california by tracking the effect of topography on precipitation as recorded in hydrogen isotopes of kaolinite exposed in gold bearing river deposits from the eocene yuba river the data compared with the modern isotopic composition of precipitation show that about 40 to 50 million years ago the sierra nevada stood tall 2200 meters a result in conflict with proposed young surface uplift by tectonic and climatic forcing but consistent with the sierra nevada representing the edge of a pre eocene continental plateau

seismic structure of the lithosphere from teleseismic converted arrivals observed at small arrays in the southern sierra nevada and vicinity california 21 well distributed teleseisms 30 to 100 distance were recorded by mixed broad band bb and short period sp seismic arrays at mineral king mk and horseshoe meadow hm in the southern sierra nevada and at darwin plateau dp between the inyo and argus ranges these arrays permit identification and separation of direct p and s arrivals reflections from topography scattered energy and arrivals from different back azimuths multipath arrivals p to s conversions can be identified from beamed bb or sp seismograms least squares time domain processing recovered single event receiver functions from these beamed seismograms converted phases attributable to the moho are clear and uncomplicated at dp ps p times of 3 9 4 2 s correspond to crustal thicknesses of 31 33 km assuming a mean p crustal velocity of 6 2 km s and a poisson s ratio of 0 255 ps p times at hm eastern sierra are 3 9 4 6 s 32 37 km excepting some unusual seismograms from events at back azimuths of 225 239 mk western sierra times for ps p show a strong e w asymmetry 3 9 4 1 s 31 33 km from the east and 4 8 5 3 s 39 42 km from the west the mk arrivals from the east are multiple and substantially weaker by comparison with hm and dp these results confirm the absence of a thick crust under the southern high sierra inferred from both a refraction experiment coincident with this experiment and some earlier studies at dp the moho event follows an intracrustal negative polarity event defining the top of an s wave low velocity zone this feature dips west under the sierran crest at hm but is absent farther west at mk this feature appears to be a manifestation of extensional strain and thus indicates that the surficially undeformed sierra overlies a tectonized lower crust sub moho energy is absent under the basin and range dp but is conspicuous under the high sierra at positive arrivals 7 3 s mk and 9 s hm after the p these arrivals might be from the base of a low velocity low density upper mantle body supporting the sierra

paleotopography in the western u s cordillera issue 2 of volume 312 of the american journal of science brings together several new papers bearing on the history of orogenesis paleotopography and paleoclimate in a region whose geologic record has been more important to the modern development of ideas about these processes than any other in

the uplift of the sierra nevada and implications for late cenozoic epeirogeny in the western cordillera tilted cenozoic strata in the eastern great valley california record progressive late cenozoic uplift of the sierra nevada the magnitude of tilting is combined with other geologic data using a technique pioneered by grant and others to infer the rate and timing of post late miocene uplift between the kings river and the feather river angular unconformities of late neogene age have been reported throughout the east central great valley typically stratigraphic units of late oligocene through miocene pliocene age beneath the unconformities dip approximately 1 2 1 6 southwest middle to late pliocene units above the unconformities dip approximately 0 6 0 9 southwest and progressively overlap younger units from east to west these angular unconformities are interpreted to represent the onset of late cenozoic uplift of the sierra nevada due to westward tilting dated volcaniclastic units in the east central sacramento valley bracket the onset of tilting there between 3 4 and 8 4 ma stratigraphic and geologic relations from the stanislaus river area eastern san joa quin valley suggest that the late cenozoic tilting probably began approximately 5 ma previously published tilt data from the san joaquin valley combined with new work in the eastern sacramento valley indicate that the rate of post late miocene tilting has been approximately uniform in the east central great valley early to middle pleistocene units typically dip 0 5 0 7 southwest middle pleistocene units dip 0 2 0 4 middle to late pleistocene units dip 0 1 0 15 late pleistocene units dip 0 05 0 1 if it is assumed that major westward tilting began 5 ma these data indicate an approximately uniform tilting rate of 0 28 per million years these data have important implications for models of the uplift simultaneous inception of tilting in the east central great valley at approximately 5 ma does not support models that link uplift of the sierra nevada to the migration of the mendocino triple junction late cenozoic tilting of the sierra nevada block does not appear to coincide temporally with the onset of major basin and range extension the uplift may be due to thinning of the mantle lithosphere beneath the sierra nevada but the tilt data do not afford a direct test of this hypothesis post late miocene tilting of the sierra nevada is temporally associated with late cenozoic uplift of the northern basin and range uplift of the cascades uplift of the colorado plateau and uplift of the southern rocky mountains supporting the contention that tilting of the sierra nevada may have occurred as part of a cordillera wide uplift event

magnetism of a very young lunar glass recent paleomagnetic studies of apollo samples have established that a core dynamo existed on the moon from at least 4 2 to 3 56 billion years ga because there is no lunar dynamo today a longstanding mystery has been the origin of magnetization in very young lunar samples 10 t core dynamo field nor impact generated fields

exhumation of the inyo mountains california implications for the timing of extension along the western boundary of the basin and range province and distribution of dextral fault slip rates across the eastern california shear zone 1 new geologic mapping tectonic geomorphologic 10be terrestrial cosmogenic nuclide and u th he zircon and apatite thermochronometric data provide the first numerical constraints on late cretaceous to late quaternary exhumation of the inyo mountains and vertical slip and horizontal extension rates across the eastern inyo fault zone california the east dipping eastern inyo fault zone bounds the eastern flank of the inyo mountains a prominent geomorphic feature within the western basin and range province and eastern california shear zone u th he zircon and apatite thermochronometry yield age patterns across the range that are interpreted as indicating 1 two episodes of moderate to rapid exhumation associated with laramide deformation during the late cretaceous early tertiary 2 development of a slowly eroding surface during a prolonged period from early eocene to middle miocene 3 rapid cooling exhumation and initiation of normal slip along the eastern inyo fault zone accommodated by westward tilting of the inyo mountains block at 15 6 ma and 4 rapid cooling exhumation and renewed normal slip along the eastern inyo fault zone at 2 8 ma fault slip continues today as indicated by fault scarps that cut late pleistocene alluvial fan surfaces the second episode of normal slip at 2 8 ma also signals onset of dextral slip along the hunter mountain fault yielding a pliocene dextral slip rate of 3 3 1 0 mm a where a is years summing this dextral slip rate with estimated dextral slip rates along the owens valley death valley and stateline faults yields a net geologic dextral slip rate across the eastern california shear zone of 9 3 2 2 1 4 to 9 8 1 4 1 0 mm a

stable isotopic evidence for a pre middle miocene rain shadow in the western basin and range implications for the paleotopography of the sierra nevada 1 a recently proposed method for approximating the paleorelief of mountain belts makes use of the predictable relationship between the isotopic depletion of precipitation and the net elevation of an orographic barrier over which an air mass rises this rain shadow effect often creates desert regions on the lee side of mountain belts in which precipitation is isotopically light changes in the isotopic composition of precipitation can be estimated from the isotopic composition of authigenic or pedogenic minerals which can then be used to infer both the development of relief during orogenesis as well as the stability of a rain shadow formed by developing mountains the 18o of smectites formed from the weathering of middle miocene to late pliocene volcanic ashes currently exposed in the rain shadow of the modern sierra nevada of california show no indication of large scale late cenozoic surface uplift of the sierra and corresponding regional rain shadow development rather smectite isotope data tentatively suggest that elevations may have decreased over this time by as much as 2000 m toward the southern end of the range and 700 m in regions farther north this suggests that the modern rain shadow cast over the western basin and range has been in existence since pre middle miocene and that the sierra nevada have been a prominent orographic barrier since before this time these interpretations are in accord with several recent studies also suggesting a possible cenozoic elevation loss of an already developed sierra nevada mountain range

estimation of lignite reserve in the kalburcayiri field kangal basin sivas turkey abstract this paper addresses a case study on global estimation of lignite reserve in the kalburcayiri field from the sivas kangal basin which is one of the most productive lignite basins in eastern anatolia turkey the two lignite seams which were developed in a fresh water lacustrine depositional environment during the pliocene time are currently being exploited in the kalburcayiri open cast mine for feed coal to a power plant with 300 mw capacity tonnage thickness and quality parameters ash yield total sulphur content and calorific value of the lignite are variables considered in this study the global estimates of these variables together with 95 confidence limits are obtained using the approximation principle of global estimation a random stratified grid is fitted to available boreholes the variograms for thickness and lignite quality parameters are estimated and modeled the models are used in calculating estimation error variances that will later be used in constructing 95 confidence intervals for the true values

forecasting coal resources and reserves in heterogeneous coal zones using 3d facies models as pontes basin nw spain abstract forecasting coal resources and reserves is critical for coal mine development thickness maps are commonly used for assessing coal resources and reserves however they are limited for capturing coal splitting effects in thick and heterogeneous coal zones as an alternative three dimensional geostatistical methods are used to populate facies distribution within a densely drilled heterogeneous coal zone in the as pontes basin nw spain coal distribution in this zone is mainly characterized by coal dominated areas in the central parts of the basin interfingering with terrigenous dominated alluvial fan zones at the margins the three dimensional models obtained are applied to forecast coal resources and reserves predictions using subsets of the entire dataset are also generated to understand the performance of methods under limited data constraints three dimensional facies interpolation methods tend to overestimate coal resources and reserves due to interpolation smoothing facies simulation methods yield similar resource predictions than conventional thickness map approximations reserves predicted by facies simulation methods are mainly influenced by a the specific coal proportion threshold used to determine if a block can be recovered or not and b the capability of the modelling strategy to reproduce areal trends in coal proportions and splitting between coal dominated and terrigenous dominated areas of the basin reserves predictions differ between the simulation methods even with dense conditioning datasets simulation methods can be ranked according to the correlation of their outputs with predictions from the directly interpolated coal proportion maps a with low density datasets sequential indicator simulation with trends yields the best correlation b with high density datasets sequential indicator simulation with post processing yields the best correlation because the areal trends are provided implicitly by the dense conditioning data

optimum and robust 3d facies interpolation strategies in a heterogeneous coal zone tertiary as pontes basin nw spain coal exploration and mining in extensively drilled and sampled coal zones can benefit from 3d statistical facies interpolation starting from closely spaced core descriptions and using interpolation methods a 3d optimum and robust facies distribution model was obtained for a thick heterogeneous coal zone deposited in the non marine as pontes basin oligocene early miocene nw spain several grid layering styles interpolation methods truncated inverse squared distance weighting truncated kriging truncated kriging with an areal trend indicator inverse squared distance weighting indicator kriging and indicator kriging with an areal trend and searching conditions were compared facies interpolation strategies were evaluated using visual comparison and cross validation moreover robustness of the resultant facies distribution with respect to variations in interpolation method input parameters was verified by taking into account several scenarios of uncertainty the resultant 3d facies reconstruction improves the understanding of the distribution and geometry of the coal facies furthermore since some coal quality properties e g calorific value or sulphur percentage display a good statistical correspondence with facies predicting the distribution of these properties using the reconstructed facies distribution as a template proved to be a powerful approach yielding more accurate and realistic reconstructions of these properties in the coal zone

paleovalley morphology and fluvial system evolution of eocene oligocene sediments auriferous gravels northern sierra nevada california implications for climate tectonics and topography in the northern sierra nevada california eocene oligocene fluvial sediments the auriferous gravels rest unconformably in well defined basement incised paleovalleys providing a record of paleolandscape geomorphology and drainage system evolution paleovalley surface mapping shows that local topography and bedrock lithology controlled the location of broad terraced paleovalley segments which formed in the central and eastern metamorphic bedrock belts and subsequently became areas of significant fluvial deposition high gradient high energy deposits are present near the edges of these areas suggesting that tributaries and outlets resided in steeper narrow paleovalleys multiple strath terraces are common in broad paleovalleys indicating that incision events occurred both before deposition and during paleovalley widening followed by periods of aggradation broad paleovalley deposits contain predominantly braided stream facies deposited in an energetically variable system multiple upward fining cycles bounded by erosional surfaces are composed of alternating coarse grained channel belt and fine grained floodplain packages an overall upward fining succession suggests that the locus of fluvial deposition shifted and depositional energy waned over time as the system backfilled successive broad paleovalleys paleochannel slope estimates of 0 004 0 055 were obtained based on average grain sizes of coarse channel fills anomalously thick up to 11 m laterally continuous 1 3 km floodplain units containing kaolinite rich clay and oxisol intervals record high fine grained sediment supply driven by high rates of chemical weathering in the warm eocene climate based on sedimentary characteristics combined with floral and detrital zircon data braided stream deposition within the basin occurred from the late early eocene through late eocene and aggradation primarily occurred in broad lower gradient reaches behind a major bedrock knickpoint created in the late mesozoic early cenozoic possibly due to asymmetric batholith unroofing the diachronous localized nature of paleovalley incision and braided stream aggradation within the northern sierra nevada invalidates previous estimates of the timing and amount of range uplift based on paleochannel reconstructions and gradients both internal and external drivers influenced the evolution of the fluvial system through 1 the pattern of basin filling as the locus of deposition migrated east to west 2 the warm eocene climate which increased chemical weathering and contributed a high sediment supply and 3 changes in base level due to eustasy and or laramide tectonism this record of laramide tectonics in the sierra nevada and basin and range is important for the timing of sierra nevada uplift for tectonic reconstructions of western north america and for studies of landscape evolution in tectonically active orogens

trace elements in the lower pliocene fossiliferous kangal lignites sivas turkey abstract the kangal lignite basin which is one of the most productive lignite basins in eastern anatolia turkey includes two lignite seams containing abundant gastropoda shells in the lower pliocene kalburcayiri formation the seams are currently exploited in an open cast mine in the kalburcayiri field and supply feed coal to a power plant with 300 mw capacity the average thickness of each of the two seams in this mine is about 10 m and they are separated by about 20 m of tuffaceous sedimentary rocks a 15 20 cm thick tuff bed occurs within the upper seam the purpose of the study was to understand mineralogy and trace element concentrations of the two lignite seams in the kalburcayiri formation which were affected by volcanic ashes fifty nine core samples of the lignites from seven boreholes across the basin and eight channel samples from the working lignite seams were collected and analysed by proximate analysis x ray powder diffraction xrd inductively coupled plasma mass spectrometry icp ms and scanning electron microscopy sem with energy dispersive x ray microanalysis techniques the samples show that the worked lignite seams on an as received basis contain high moisture contents 43 4 57 8 all the samples on an air dried basis have high ash yields from 19 5 to 81 7 and a broad range of total sulfur contents from 1 16 to 7 04 and calorific values 684 to 4621 kcal kg except for two samples with no temperature rise due to high ash yield the mineral matter of the studied samples is made up of calcite quartz feldspar pyrite opal ct clay minerals gypsum and traces of aragonite the trace element analyses on a whole coal dry basis indicate that most of the borehole samples showed enrichment in specific elements including zn 15 1394 g g mo 13 368 g g and u 5 5 131 g g when compared to the range of these elements for most coals in the world the contents of zn mo and u for the samples from the worked lignite seams are respectively 38 187 54 161 and 28 55 g g the sem studies show that zn is hosted mainly in micron sized zn bearing mineral sphalerite but no mo and u bearing minerals have been detected during these studies except for monazites containing th and u traces the mo and u concentrations are negatively correlated with the ash yields and these elements are contained mainly within organic matter

stable isotope constraints on the elevation history of the sierra nevada mountains california research on the uplift history of the sierra nevada mountain range has yielded seemingly conflicting results some studies argue for substantial uplift within the past 3 5 m y others suggest that high elevations may have existed since the cretaceous the rain shadow across the sierra nevada is associated with a strong isotopic gradient with lower 18o values in precipitation on the leeward side of the range reconstruction of the 18o value of meteoric water as a monitor of paleoelevation has focused mainly on the leeward side of the sierras but interpretation of the results of these studies may be complicated by shifts in global climate and regional moisture sources we address these concerns by analyzing the 18o value of tooth enamel bioapatite from contemporaneous mammalian fossils on either side of the present sierra range by sampling across the range 18o differences induced by a rain shadow can be isolated from other complicating factors our results indicate that the sierra rain shadow has existed since at least 16 ma which is an important constraint on models for the tectonic evolution of the western united states unfortunately temporal resolution for localities is too coarse to differentiate between glacial and interglacial localities during the past 2 m y so we cannot evaluate if there was a latest cenozoic pulse of uplift or elevation loss

hydrocarbon generation potential and miocene pliocene paleoenvironments of the kangal basin central anatolia turkey abstract this study deals with the organic geochemical characteristics hydrocarbon generative potential and miocene pliocene paleoenvironments of the kangal coal district which developed in a limnic depositional environment and contains the hamal etyemez and kalburcayiri coal fields in the southern part of the sivas basin central anatolia around kalburcayiri the average thickness of each of the two coal seams approximately 10 m are currently being exploited based on open cast methods the coal from which is used by the nearby lignite fired kangal power station an attempt was made to elucidate depositional conditions through proximate and ultimate analyses coal petrography and the geochemical characteristics of the kangal coals these coals have a huminite reflectance value of rmax 0 40 accordingly from the standpoint of coal rank this is a dull brown coal of the subbituminous c type huminite is the most widespread maceral type while gelinites are the most often encountered macerals relative to liptinites the proportion of inertinites is high on the basis of maceral composition the depositional environment of the kangal coals was determined to be either a forest swamp or a lake bottom the distributions of the c27 and c28 c29 steranes for all these coal samples are very similar c29 c27 c28 tricyclic terpanes have low concentrations in all samples of the kangal coals and are dominated by low molecular weight compounds c20 c24 with a maximum at c23 total organic carbon toc wt values of the kalburcayiri samples are 4 64 30 64 wt in the hamal samples 0 83 2 53 wt and in the etyemez samples 8 91 10 39 wt on the basis of tmax values the samples are in the immature early mature stage according to rock eval pyrolysis data the coals have hydrocarbon source rock potential but the coaly shales and other organic matter rich levels have no hydrocarbon source rock potential the high inertinite levels and high vitrinite inertinite ratios suggest that the kangal coals have more potential for gas generation than oil

geomorphological analysis of neotectonic deformation northern owens valley california at the western edge of the basin and range province the owens valley is the site of active seismicity and deformation morphometric analyses of three geomorphological features are used to determine the patterns and rates of neotectonic deformation l a network of pleistocene channels cut on top of the bishop tuff 2 uplifted terraces of the owens river and 3 alluvial fans of the white mountain front

faulting on the volcanic tableland owens valley california the volcanic tableland brittle surface of the 764 000 yr old bishop tuff documents extensive faulting in the northern owens valley california during the late quaternary the tableland surface is cut by at least 226 fault scarps with a total of 328 km of surface rupture scarps are lens shaped rips in the surface of the bishop tuff with vertical offsets of a few meters to 140 m and lengths up to several kilometers the scarps have an average trend of n10 20 w and dip steeply both to the east and west the tableland records at least 290 m of cross valley extension in the last 764 000 yrs at an average rate of at least 400 m m y and a cumulative seismic moment of at least 2 8 cdot 10 28 dyne cm the volcanic tableland lies astride what has been called the white mountain seismic gap of the eastern california central nevada seismic zone seismic moment recorded on the tableland can be used to estimate average recurrence interval of surface rupturing earthquakes on the floor of the owens valley

magnetotelluric evidence of lithospheric mantle thinning beneath the southern sierra nevada a wideband 0 01 1000 s magnetotelluric survey across the southern sierra nevada has identified zones of enhanced conductivity in the lower crust and upper mantle that underlie the resistive batholithic rocks at depths greater than 10 20 km the eastern zone underlies the highest topography of the range and extends eastward this eastern conductive zone extends to depths in excess of 100 km based on model sensitivities and lies well below the moho depth of 32 38 km from seismological studies therefore the enhanced conductivity in the mantle cannot be attributed to conventional explanations for conductive continental crust and is instead likely due to partial melt such an interpretation is consistent with gravitational seismological and geologic evidence estimates of the partial melt fraction range from 2 to 5 at depths of 40 70 km which are consistent with fractions of melt inclusions observed in xenoliths from the eastern sierra nevada this partial melt accounts for approximately one third of the density decrease required in the mantle for support of the present high elevations the other two thirds of the density decrease could be due to thermal expansion of the upper mantle or due to mineralogical changes the western conductive zone also straddles the moho and extends into the mantle beneath western foothills of the sierra nevada and the great valley sediments to the west however xenoliths from this region indicate high velocity crustal rocks to depths in excess of 60 km and we therefore attribute the enhanced conductivity to graphitic metasediments and or dehydration of metaserpentinite emplaced by downward return flow of the host rocks during intrusion of the sierran plutons

geochemical correlation and 40ar 39ar dating of the kern river ash bed and related tephra layers implications for the stratigraphy of petroleum bearing formations in the san joaquin valley california abstract the kern river ash kra bed is a prominent tephra layer separating the k and g sands in the upper part of the kern river formation a major petroleum bearing formation in the southern san joaquin valley ssjv of california the minimum age of the kern river formation was based on the tentative major element correlation with the bishop tuff a 0 759 0 002 ma volcanic tephra layer erupted from the long valley caldera we report a 6 12 0 05 ma 40 ar 39 ar date for the kra updated major element correlations trace element correlations of the kra and geochemically similar tephra and a 6 0 0 2 ma 40 ar 39 ar age for a tephra layer from the volcano hills silver peak eruptive center in nevada both major and trace element correlations show that despite the similarity to the bishop tuff the kra correlates most closely with tephra from the volcano hills silver peak eruptive center this geochemical correlation is supported by the radiometric dates which are consistent with a correlation of the kra to the volcano hills silver peak center but not to the bishop tuff the 6 12 0 05 ma age for the kra and the 6 0 0 2 ma age for the tephra layer from the volcano hills silver peak eruptive center suggest that the upper age of the kern river formation is over 5 ma older than previously thought re interpreted stratigraphy of the ssjv based on the new significantly older age for the kern river formation opens up new opportunities for petroleum exploration in the ssjv and places better constraints on the tectonostratigraphic development of the ssjv

seam modeling and resource estimation in the coalfields of western anatolia abstract western anatolia turkey includes a number of lignite bearing neogene fields with difficult modeling and estimation problems resulting from severe tectonic movements and highly variable coal quality the paper considers the eynez soma and omerler tuncbilek coal fields and introduces a simple but effective way of defining the geological discontinuities that are vital for selective mining method after doing statistical analysis for both fields data taken from core samples of diamond drill holes are used to model fault blocks in order to establish a 3d coal seam model then block small mining unit modeling is performed for both coal fields and some coal quality parameters are estimated and assigned to the predefined blocks for estimation process a new method of wrinkling and unwrinkling is introduced and composited data is detrended each block is kriged by using the detrended data in unwrinkled space the volume of the blocks is converted into in situ tonnages based on their estimated densities in eynez the densities are derived from the mean lower calorific value of the blocks using the relationship between lower calorific value and density in omerler the block densities are estimated from the composited values of densities of the lithologic units in coal horizon by using ordinary kriging

petrographical properties and unusual features of kangal coals sivas turkey abstract in turkey low rank coal is used in three sectors power generation industry and household and commercial heating due to poor quality coal is suitable for thermal power generation only kangal coal is of low rank being mostly used in a thermal power station kangal coal basin located in eastern central turkey formed in a pliocene aged fresh water lacustrine depositional environment and includes kalburcayiri hamal and etyemez fields approximately 202 6 mt of coal reserve with calorific values between 1010 and 3420 kcal kg are hosted in the area kalburcayiri field is the only open pit production site in the basin fifty two channel samples were collected from different sites the composite profile samples of the seams were taken into considerations the content and depositional properties as well as some chemical and physical properties of the main coal seams are compared detailed organic petrographic and chemical analyses were applied for this study all coal samples tend to have similar coal petrographic properties and were deposited in a lacustrine basin later they were affected by faulting as a result there are variations in the properties and rank of the coal samples the most abundant maceral group is huminite and the most abundant maceral is gelinite liptinite and inertinite contents of the coal are low and the maceral assemblage of the coals show extremely unusual broken and deformed maceral contents tend to be more abundant considering the other turkish coals the maceral contents textures and the unusual appearances imply that the coals were formed as in a hypautochtonous way the reflectance measurements indicate the rank of the coals to be mostly as sub bituminous although some chemical analyses exhibit inefficient results

using cave deposits as geologic tiltmeters application to postglacial rebound of the sierra nevada california 1 secondary calcite shelfstone deposits in caves can be used to precisely measure tilting over geologic timescales calcite deposited along the edges of former pools can be surveyed to within a single millimeter and can be dated using uranium series disequilibrium two caves in the southern sierra nevada california contain tilted calcite deposits of glacial age a third cave contains a similar but untilted deposit of older interglacial age the cave deposits record glacio isostatic rebound of the sierra nevada following melting of an ice cap 15 000 years ago models of crustal flexure beneath mapped ice thickness reproduce the observed tilting with an effective elastic thickness te of approximately 5 km

stable isotope paleoaltimetry a critical review stable isotope paleoaltimetry makes use of systematic trends in the distribution and isotopic composition of modern precipitation with climate and topography and of the potential to estimate the isotopic composition of paleoprecipitation from authigenic in situ formed minerals to illustrate the usefulness as well as potential limitations of this method we review 1 processes controlling the isotopic composition of modern precipitation 2 stable isotope data from modern precipitation across regions of high topography and 3 stable isotope data from authigenic minerals that have been used to infer paleotopography from this we conclude that stable isotope studies of authigenic minerals can permit useful inferences on paleotopography with uncertainties that critically depend on a detailed understanding of local to global scale paleoclimate during the time interval of interest

lignite resource estimations and seam modeling of thar field pakistan abstract thar lignite field in pakistan contains more than 175 billion tons thus far not exploited to date the coalfield has been divided into 12 exploration blocks and each block is studied and investigated separately by different agencies as a result of exploration programs a large exploration database containing geological and coal quality information is constructed but geostatistical studies regarding to quantify entire thar lignite resources is not available yet this paper aims to generate 3d solid model of main thar seam and to produce spatial distribution maps for various coal quality attributes by geostatistical method ordinary kriging 3d seam model has a volume of 17 71 billion m3 the resulting spatial map of ash content shows structured distribution and lcv map shows fair agreement with ash map except in block vi where high and low values of ash and lcv occur in close proximity the moisture distribution reveals higher values in northern and southern parts whereas the central portion possesses lower moisture values the sulfur content shows homogenous distribution with some higher sulfur patches at places the kriging variance maps are generated to delineate areas of higher uncertainty these maps could be helpful to devise further exploration programs blocks were checked on the basis of global averages and swath plot comparison

using hilltop curvature to derive the spatial distribution of erosion rates 1 erosion rates dictate the morphology of landscapes and therefore quantifying them is a critical part of many geomorphic studies methods to directly measure erosion rates are expensive and time consuming whereas topographic analysis facilitates prediction of erosion rates rapidly and over large spatial extents if hillslope sediment flux is nonlinearly dependent on slope then the curvature of hilltops will be linearly proportional to erosion rates in this contribution we develop new techniques to extract hilltop networks and sample their adjacent hillslopes in order to test the utility of hilltop curvature for estimating erosion rates using high resolution 1 m digital elevation data published and new cosmogenic radionuclide analyses in the feather river basin california suggest that erosion rates vary by over an order of magnitude 10 to 250 mm kyr 1 hilltop curvature increases with erosion rates allowing calibration of the hillslope sediment transport coefficient which controls the relationship between gradient and sediment flux having constraints on sediment transport efficiency allows estimation of erosion rates throughout the landscape by mapping the spatial distribution of hilltop curvature additionally we show that hilltop curvature continues to increase with rising erosion rates after gradient limited hillslopes have emerged hence hilltop curvature can potentially reflect higher erosion rates than can be predicted by hillslope gradient providing soil production on hilltops can keep pace with erosion finally hilltop curvature can be used to estimate erosion rates in landscapes undergoing a transient adjustment to changing boundary conditions if the response timescale of hillslopes is short relative to channels