novel paleoecology of a postextinction reef famennian late devonian of the canning basin northwestern australia reefs are widely supposed to be particularly susceptible to mass extinction events and to survive only as low diversity remnant communities dominated by holdover or disaster taxa famennian late devonian reefs exposed in the windjana limestone of the canning basin northwestern australia demonstrate however that a novel reef ecology was established in the immediate aftermath of the frasnian famennian mass extinction here diverse calcimicrobes including rothpletzella spp shuguria spp ortonella and girvanella together with bryozoans brachiopods and stromatoporoid sphinctozoan and lithistid sponges grew as complex framework intergrowths in previously undocumented morphological forms forming spectacular elevated laminar to platy structures to 3 m in diameter and 0 35 m thick at least 15 morphospecies of lithistids are now identified where only two were previously documented these communities show no substantial reduction in biodiversity compared to frasnian counterparts nor any change in tiering or loss of complex ecological interactions these observations suggest that where stable carbonate platforms persisted after mass extinction events reef building could continue more important they demonstrate that no protracted interval of time was necessarily required either for recovery to ecological stability or for completely new reef ecologies to assemble such studies highlight the need to document ecosystem recovery after mass extinction events using detailed paleoecological analyses in addition to simple compilations of global biodiversity changes

on the characteristics and origin of closed depressions in loess derived soils in europe a case study from central belgium abstract a closed depression cd is a landform where the hillslopes encircle a common sediment depository and the sediment eroded from the surrounding hillslopes is trapped in the system despite the fact that closed depressions cds have been regularly reported in the literature little research on their origin exists therefore a case study was made of the morphological characteristics and genesis of cds in central belgium that are still visible in the landscape through field surveys 26 cds were found in a 43 km2 study area southwest of leuven most cds were situated on a plateau far from villages but close to important rural roads the morphological features of the cds i e diameter area maximum depth and steepest slope were measured the results show that there were significant differences between the morphology of the cds under forest and under cropland cds under cropland were larger shallower and had gentler slopes compared to those under forest based on these morphological features a hypothetical evolution scheme of cds was formulated through a detailed literature search eight out of 26 cds were identified as having an anthropogenic origin they were former quarries mines for calcareous sandstone or iron sandstone in four other cds augerings were made and detailed studies of their soil profiles within and in the vicinity of cds indicated that they are quarries for calcareous loess in one of the four cds with a catchment area of 0 588 ha the soil erosion rate was calculated using soil sequences phosphate content and charcoal analysis since 1950 ad the mean annual soil loss due to water and tillage erosion within the catchment of the cd ranged between 5 5 and 9 8 ton ha or 0 37 0 65 mm based on 14c dating it was calculated that mean annual soil loss since 430 ad amounted to 2 1 ton ha or 0 14 mm

history of the newark east field and the barnett shale as a gas reservoir david martineau is a certified petroleum geologist and received his b s degree in geology from the university of texas in 1960 he joined pitts in 1972 and is the exploration manager pitts has been involved in the barnett play since its inception prior to pitts he worked for prudential drilling funds and coastal states gas producing company now el paso in 2006 the newark east field was the largest producing gas field in texas and according to the energy information administration eia latest reserves estimate eia 2006 tables b2 and b4 newark east field ranks third in the nation and second in the nation in terms of production the newark east field has generated considerable attention because the gas is produced from the barnett shale as opposed to conventional sandstone conglomerate or carbonate reservoirs the field was discovered in 1981 by mitchell energy corporation mec in wise county texas located in the fort worth basin in north central texas george mitchell founder and chief executive officer of mec had the vision and leadership behind mec s continued exploration and research for the correct technology to extract gas from this unconventional gas reservoir dan steward was the chief geologist for mec during the critical exploration development of the barnett shale and was honored by aapg with the 2007 outstanding explorer award the development of the field started slowly and only 100 wells were completed between 1981 and 1990 in 1998 a major breakthrough in completion technique occurred when water fracturing replaced gel fracturing from 1997 to 2006 more than 5829 wells were put on production and hundreds of additional wells were drilled completed or waiting on a pipeline the field has been divided into two areas 1 the original core area where the barnett sits on top of the viola limestone

human induced soil erosion and gully system development in the late holocene and future perspectives on landscape evolution the myjava hill land slovakia in humid climate zones like central europe past soil erosion and gullying are strongly connected with agricultural expansion and extreme soil erosion events often play an important role in land abandonment this paper provides a case study to demonstrate the interaction between land use soil erosion floodplain development and land use changes in a 0 order catchment in the babikovce catchment myjava hill land situated in western slovakia sedimentological pedological geoarchaeological and historical data indicate two main periods of intensive hillslope erosion and gullying since the high middle ages in particular a few extreme precipitation events or rapid snowmelts caused intensive runoff events and gullying on cleared land the formation of the gully system and fan deposits in the babikovce catchment and other areas also forced the occurrence of intensive muddy floods and caused floodplain aggradation and meander changes along rivers in the myjava hill land as a result the development of the dense network of permanent gullies in the myjava hill land can be associated with the transformation of woodland into farmland and later land abandonment today the area is highly truncated by soil erosion and very difficult to farm

depositional facies and stratal geometry of an upper carboniferous prograding and aggrading high relief carbonate platform cantabrian mountains n spain seismic scale continuous exposures of an upper carboniferous bashkirian moscovian carbonate platform n spain provide detailed information about the lithofacies and stratal geometries quantified with differential global positioning system measurements of microbial boundstone dominated steep prograding and aggrading platform margins progradational and aggradational platform to slope transects are characterized by distinct lithological features and stratal patterns that can be applied to the understanding of geometrically comparable high relief depositional systems the bashkirian is characterized by rapid progradation at rates of 415 970 m my 1 characteristic outerplatform facies are high energy grainstones with coated intraclasts ooids and pisoids moderate energy algal skeletal grainstones to packstones and lower energy algal packstone and boundstone units the moscovian aggradational phase is characterized by aggradation rates of 108 m my 1 coated grain shoals are less common whereas crinoidal bars nucleated in well circulated settings below wave base boundstones form a belt 30 300 m wide at the platform break and interfinger inwards with massive algal skeletal wackestones mud rich banks the progradational phase has divergent outer platform strata with basinward dips of 12 to 2 steep clinoforms with dips of 20 28 are 650 750 m in relief and possibly sigmoidal to concave in the lower part the basinward dipping outer platform strata might be depositional for less than 6 consistent with lithofacies deepening seaward the basinward dip is attributed to the downward shift of upperslope boundstone forced by late highstand and relative sea level fall and to compaction induced differential subsidence during progradation the aggradational phase is characterized by horizontally layered platform strata clinoforms steepen to 30 45 reaching heights of 850 m and are planar to concave the evolution from progradation to aggradation at the bashkirian moscovian boundary is attributed to increased foreland basin subsidence and decreased boundstone accumulation rates progradation was primarily controlled by boundstone growth rather than by highstand shedding from the platform top within the major phases aggradational progradational increments are produced by third to fourth order relative sea level

monterey formation porcelanite reservoirs of the elk hills field kern county california oil and gas production from monterey formation porcelanite at the elk hills field in california s san joaquin basin occurs from intervals that have quartz phase mineralogy however characteristics differ from chert and porcelanite reservoirs of the coastal california monterey formation in that matrix porosity is more typical of the opal ct phase petroleum storage is mostly in the matrix and natural fracture patterns are dominantly small scale several elk hills reservoirs located on two large anticlines produce from porcelanite the 29r ab and 31s d are the most productive porcelanite reservoirs each having cumulative oil production of about 40 million bbl although interbedded with siliceous shale sandstone and dolomite most of the porous reservoir rock is laminated porcelanite porosity averages between 20 and 25 and is evenly distributed throughout the porcelanite as extremely small pores ranging in size from 1 to 10 m matrix permeability averages 0 8 md but flow of oil and gas is enhanced through fractures parallel with and perpendicular to bedding higher than anticipated porosity may be in part due to migration of hydrocarbons into the porcelanite reservoirs while still in opal ct phase mineralogy the dissolution of opal ct and precipitation of quartz occurs in place and the resulting quartz phase mineral structure mimicks the porous opal ct framework

a temporarily changing holocene sediment budget for a loess covered catchment central belgium abstract this study presents a holocene sediment budget for the nethen catchment a typical river catchment 55 km 2 in the belgian loess belt soil erosion and hillslope sediment storage are quantified by extrapolating detailed data obtained from soil profile truncation studies in three representative zero order sub catchments floodplain sediment storage is estimated by augerings along several transects across the main river and some of its tributaries the sediment budget shows that ca 38 of the soil eroded during the holocene is redeposited as colluvium on hillslopes and in dry valley bottoms another 23 of the eroded sediment is now stored as alluvium in the floodplain the remaining 39 or 21 10 6 mg is exported from the catchment dating of both colluvial and alluvial sediment deposits reveals that sediment dynamics between the hillslopes the dry valley bottoms and the floodplain behave highly non linearly before 500 bc sediment delivery from the hillslopes to the river channels was near maximum however since the onset of significant agriculture in the late bronze age early iron age increased rates of soil erosion are only reflected in the colluvium but not in the floodplain resulting in very low hillslope sediment delivery ratios from the medieval period onwards soil erosion increased even further mainly as a result of a further increase in agricultural land use but now also accelerated floodplain sedimentation took place due to an improved slope channel coupling and the management of floodplains

unlocking the spatial dimension digital technologies and the future of geoscience fieldwork the development of affordable digital technologies that allow the collection and analysis of georeferenced field data represents one of the most significant changes in field based geoscientific study since the invention of the geological map digital methods make it easier to re use pre existing data e g previous field data geophysical survey satellite images during renewed phases of fieldwork increased spatial accuracy from satellite and laser positioning systems provides access to geostatistical and geospatial analyses that can inform hypothesis testing during fieldwork high resolution geomatic surveys including laser scanning methods allow 3d photorealistic outcrop images to be captured and interpreted using novel visualization and analysis methods in addition better data management on projects is possible using geospatially referenced databases that match agreed international data standards collectively the new techniques allow 3d models of geological architectures to be constructed directly from field data in ways that are more robust compared with the abstract models constructed traditionally by geoscientists this development will permit explicit information on uncertainty to be carried forward from field data to the final product current work is focused upon the development and implementation of a more streamlined digital workflow from the initial data acquisition stage to the final project output

reefal platform development devonian of the canning basin western australia growth of devonian reefal limestone platforms on the canning basin was nearly continuous from the late givetian to the late famennian the earliest givetian and early frasnian platforms were low relief banks later frasnian and famennian platforms were normally reef rimmed with high relief upright reef margins predominated in the frasnian with intervals of backstepping associated with widespread drowning and the development of pinnacle reefs a brief emergence occurred at the frasnian famennian boundary and the succeeding famennian platforms advanced basinward over equivalent marginal slope and basin facies platform extinction in the late famennian resulted from abrupt drowning an important initial control on platform trends was basement topography resulting from middle devonian or older faulting continued faulting during the late devonian influenced the morphology of some platforms contemporary seismicity also led to neptunian fracturing and the collapse of platform margins the hypothetical sea level curve for the canning basin devonian is believed to be a combined result of global eustatism and regional diastrophism it shows gross resemblance to the equivalent euramerican curve rates of sea level rise or subsidence are thought to have largely controlled platform evolution banks and advancing platforms were associated with slow rises in sea level upright reef scarpsmore with moderately rapid rises and backstepping pinnacle reefs and drowning with very rapid rises shoaling upward cycles in back reef limestones resulted from periodic abrupt rises of a few meters followed by longer stillstands seismic stratigraphic modeling together with observed seismic records and well data suggest that the evolutionary model for the devonian platforms deduced from outcrop studies can also be applied in the subsurface less

the compatibility of erosion data at different temporal scales abstract soil erosion processes have been studied intensively throughout the last decades and rates have been measured at the plot scale as well as at larger scales however the relevance of this knowledge for the modelling of long term landscape evolution remains a topic of considerable debate some authors state that measurements of current rates are irrelevant to landscape evolution over a longer time span as they are inconsistent with some fundamental characteristics of landscapes such as the fact that the long term sediment delivery ratio needs to be equal to 1 and that extrapolation of current rates would imply that all soils in europe should have disappeared by now e g parsons a j wainwright j brazier r e powell d m 2006 is sediment delivery a fallacy earth surface processes and landforms 31 1325 1328 in this study we investigate if and to what extent estimates of long term erosion rates are consistent with information obtained over much shorter time spans for the loam belt of belgium in a first step observed short term and long term patterns in the belgian loess area are compared statistically by classifying the study area into landscape element classes and comparing average erosion values per class this analysis shows that the erosion intensities on the two temporal scales are of the same order of magnitude for each landscape element class next the spatially distributed model watem lt water and tillage erosion model long term is calibrated based on the available short term data by optimising average erosion values for the same landscape element classes finally the calibrated model is used to simulate long term landform evolution and is validated using long term data based on soil profile truncation we found that the model allows simulating landscape evolution on a millennial time scale using information derived from short term erosion and deposition data however it is important that land use is taken into account for the calibration in order to obtain realistic patterns on a longer time scale our analysis shows that at least for the study area considered data obtained on erosion and deposition rates over various temporal scales have the same orders of magnitude thereby demonstrating that measurements of current rates of processes can be highly relevant for interpreting long term landscape evolution

reconstructing rainfall and land use conditions leading to the development of old gullies knowledge of past erosion events and their controlling factors is an important key to understanding the impacts of environmental change climate land use on the landscape in this study knowledge about erosion processes on the development of present day ephemeral gullies is used for reconstructing conditions leading to the formation of old permanent gullies empirical relations between flow hydraulics and channel geometry have been recently established for gullies hence using measured bottom width wbttom of old gullies as input peak flow discharges qp of these gullies can be estimated in two forested areas in central belgium 52 old gullies were mapped the old gullies had an average wbottom ranging between 1 1 and 1 5 m corresponding calculated qp values ranged between 0 04 and 0 07 m3 s rainfall intensities i were also deduced from qp using the rational formula by simulating various land use scenarios and thus various runoff coefficient c values i and concentration time tc could be ca

prehistoric and roman gullying in the european oess belt a case study from central belgium in contrast with the understanding of present day soil erosion processes knowledge on past soil erosion phenomena is still rather limited although some studies report on severe gully erosion phases during the fourteenth and eighteenth centuries almost no evidence is available that documents earlier gully erosion phases this study investigates the development and age of two old permanent gullies that are conserved in the ancient meerdaal forest in central belgium the development history of both gullies is very similar in the first gully archaeological evidence was found indicating an erosion phase during roman times followed by a partial infilling of the gully in the second gully radiocarbon dating provided evidence of the same roman activity phase cal yr 46 bc ad 78 but also of an earlier incision phase during the middle bronze age cal yr 1743 1602 1568 1533 bc also here the erosion phase was followed by a partial infilling this limited infilling indicates that the catchment of the gullies was reforested quite rapidly hereby cutting off all runoff and sediment production this has led to a unique situation in the meerdaal forest with the conservation of about 43 similar large gullies in an area of about 17 km 2 this area has a high geovalue as the studied gullies are among the oldest and best conserved gullies in northwestern europe

pollen records of mardel deposits the effects of climatic oscillations and land management on soil erosion in gutland luxembourg typically for the geomorphology of the luxembourger gutland is the occurrence of mardels a local name for small closed depressions they occur on various substrates and can have a natural or anthropogenic genesis in general mardels on the strassen marls are abandoned quarries related to historical clay extraction and mardels on the luxembourger sandstone are sinkholes related to joint patterns probably most of the mardels on the keuper marls are also abandoned quarries but some of them have a natural genesis as subsidence basins related to subsurface dissolutions of gypsum lenses present in the marl deposits during the late holocene the mardels became filled with colluvial deposits the pollen records documented in these deposits can be correlated to subatlantic climatic oscillations and correspond to changes in the rate of soil erosion and land management in particular the little ice age stands out as a period with increased denudation and temporary extension of arable land

establishing a holocene sediment budget for the river dijle abstract a holocene sediment budget was constructed for the 758 km 2 dijle catchment in the belgian loess belt in order to understand long term sediment dynamics hillslope sediment redistribution was calculated using soil profile information from 809 soil augerings which was extrapolated to the entire catchment using morphometric classes as large parts of the forests within the catchment prove to have undergone little or no erosion since medieval times a correction was applied for the presence of forests total holocene erosion amounts 817 66 mt for the catchment of which 327 34 mt was deposited as colluvium this corresponds with a net holocene soil erosion rate of 10 8 0 8 10 3 mg ha 1 for the entire dijle catchment alluvial deposits were studied through 187 augerings spread over 17 cross valley transects the total alluvial sediment deposition equals 352 11 mt or 42 of total eroded sediment mass results indicate that at the scale of a medium sized catchment the colluvial sediment sink is as important as the alluvial sediment sink and should not be neglected as a result the estimation of erosion through alluvial storage and sediment export would yield large errors dating of sediment units show an important increase in alluvial deposition from medieval times onwards indicating the important influence of agricultural activities that developed from that period mean sediment export rates from the catchment for the last 1000 1200 years range between 0 8 and 1 3 mg ha 1 a 1 and are consistent with present suspended sediment measurements in the dijle erosion for agricultural land for this period is 9 2 2 2 mg ha 1 a 1 sediment budgets for the various tributary catchments provide an insight in the sources and sinks of sediment at different scales within the catchment

characteristics and controlling factors of old gullies under forest in a temperate humid climate a case study from the meerdaal forest central belgium abstract in many forests of northwestern europe old gullies can be found but few studies have reported their genesis and characteristics this study investigates these old gullies under forest in the large case study area of meerdaal forest in the central belgian loess belt the objectives are 1 to determine the spatial distribution of these gullies 2 to measure their morphological and topographical characteristics and 3 to reconstruct the factors that led to their development in the 1329 ha study area 252 channel like incisions were mapped different types of incisions could be distinguished besides small and large gullies many incisions were sunken lanes or road gullies these road gullies are aligned along north south oriented lines whereas the concentration of old gullies is strongly related to the distribution of archaeological sites out of the 252 mapped incisions 43 large gullies and 21 representative road gullies were selected for detailed morphological and topographical measurements the characteristics of these two types of incisions were compared with ephemeral gullies formed under nearby cropland significant differences in morphology between the three types could be demonstrated ephemeral gullies under cropland and large gullies under forest differ significantly in all measured parameters except bottom width both the old gullies and road gullies under forest have a significantly larger cross section and total eroded volume compared with the ephemeral gullies observed under cropland this indicates that once formed the old gullies were not ploughed in nor were they filled by sediment originating in their drainage areas because of limited sediment production comparing topographical characteristics i e slope at the gully head and runoff contributing area of forest gullies and ephemeral gullies that formed under cropland yields important indications about their formation the larger sedimentation slope of forest gullies compared with ephemeral gullies and road gullies suggests that the forest gullies incised on vegetated slopes as a consequence of runoff from the adjacent plateau where the forest cover was disturbed for the old gullies under forest no relation between slope at the gully head and runoff contributing area is observed probably because most gullies occur on very steep slopes when simulating arable land use in the study area zones where ephemeral gullies are expected to develop can be predicted using published topographical threshold relationships comparing the zones where ephemeral gullies are predicted with the position of old gullies under forest leads to the conclusion that gully incision was most probably not triggered by extreme rainfall events and that they are not of periglacial origin the observed gully pattern can best be explained by local anthropogenically determined land use changes

sequence stratigraphy of carbonate rocks in the first contribution to tle s geologic column j m mulholland concluded that sequence stratigraphy is a tool that every explorationist must master i agree in fact sequence stratigraphy is more than a versatile tool in exploration and production geology it is in many ways a role model for applied earth sciences the fundamental task for much of the applied earth sciences is to predict occurrence and properties of sedimentary rocks in the subsurface forward modeling from first principles is insufficient to accomplish this goal the nonlinear dynamics of depositional systems is too complex

origin and evolution of closed depressions in central belgium european loess belt closed depressions cds are lower lying areas where the sediment eroded from the surrounding soil surfaces draining towards the cd is trapped in the system cds have been reported in several regions of the european loess belt and are attributed either to natural processes e g dissolution of subsurface horizons or to human intervention e g quarrying previous studies focussed mainly on cropland areas where however only few and largely filled in cds remain the objectives of this study were to i assess the spatial distribution of cds under forest and cropland ii to determine and compare the morphology of cds under forest and under cropland and iii to determine the origin and age of these cds under forest in a study area located partly in ancient forest 13 km2 and partly in cropland 29 km2 a systematic survey revealed the presence of 71 cds under forest 5 3 cd km 2 and 30 cds under cropland 1 cd km 2 comparison of their morphology showed that cds under forest were significantly deeper with steeper sidewalls and a smaller surface area because of the erosion and deposition processes acting on the cds under cropland by comparing cds that had been under cropland for different time intervals the rate of this morphological evolution could be reconstructed analysis of the soil stratigraphy of two representative cds in the ancient forest area confirmed their origin as quarries most probably calcareous loess was excavated since this soil horizon about two to five meters thick was completely absent within the cds dating of the infilling of one cd by optically stimulated luminescence osl shows that the cd filled in between the first century bc and the fourth century ad this dating corresponds to the dating of sediment deposits in nearby human induced gullies that were attributed to an agricultural land use phase between the 18th century bc and the third century ad

three deep resource plays in the san joaquin valley compared with the bakken formation a continuous oil accumulation is one that is pervasive throughout a large area and is not affected by natural hydrodynamic influences three source rocks in the san joaquin valley of california are actively producing hydrocarbons and represent potential continuous oil accumulations the monterey kreyenhagen and moreno formations the energy information administration announced in 2014 that there are potentially 15 billion bbl of recoverable oil in the monterey formation in california spiking huge interest such a resource would make the monterey by far the largest continuous oil accumulation in north america this number has since been reduced dramatically to 600 million bbl of oil for the state and 21 million bbl of oil within the san joaquin valley in this study the subsurface character of the bakken formation of north dakota is compared with the three source rocks in the san joaquin valley at oil window depths to characterize these reservoirs hundreds of well logs core descriptions and mud logs were studied a technique to rank character of oil show data was developed in which interesting possibly interesting or not interesting wells were located on thermal maturity maps interesting wells have significant oil shows whereas not interesting wells have minor or no shows in the bakken formation the character of the oil show correlates with well productivity applying this same classification to the san joaquin valley source rocks leads to a more disappointing conclusion although there are oil shows in the source rocks of the san joaquin valley at oil window depths suggesting the presence of a continuous oil accumulation the distribution of shows is both laterally and vertically heterogeneous and not predictable moreover recent attempts to produce from source rocks at these depths have not been economically successful we conclude that the three source rocks in the san joaquin valley represent heterogeneous and discontinuous oil accumulations at oil window depths in the subsurface likely there are billions of barrels of oil in these discontinuous oil accumulations source rocks in the bakken are rated as world class source rocks in the san joaquin valley are good to excellent quality however the quality of the oil shows in the san joaquin valley appears poorer than the bakken formation it is possible that effective drainage between the source rocks and the up dip reservoirs has left large volumes of the source rocks at oil window depths with only residual oil saturation complex structural and stratigraphic architecture heterogeneity and continuity create issues of predictability for optimal areas to target rapid rates of subsidence over the past few million years and accompanying thrusting and folding resulted in a complex subsurface pressure regime the lack of clear hydraulic fracture targets analogous to the middle bakken further complicates drilling decisions and likely deliverability in addition the oil windows in the san joaquin valley are significantly deeper than the bakken formation which would result in substantially higher well cost recent drilling results support this study and suggest that heterogeneous and discontinuous oil accumulations in the san joaquin are unlikely to become economic without dramatic changes in technology

holocene evolution of closed depressions and its relation to landscape dynamics in the loess areas of poland past pleistocene topography of the loess uplands is rich in local sinks closed depressions cds influencing sediment fluxes soil sediment sequences from cds constituting geoarchives where lands

guidelines for evaluating petroleum source rock using programmed pyrolysis rock eval pyrolysis is used to rapidly evaluate the petroleum generative potential and thermal maturity of rocks accurate conclusions require programs every 30 60 ft 9 18 m understanding of interpretive pitfalls and supporting data such as visual kerogen vitrinite reflectance and elemental analyses the generative potential of coals is commonly overestimated by pyrolysis and is best determined by elemental analysis and organic petrography most coals show high s2 s3 5 and low hi values 300 mg hc g toc migrated oil and mud additives which alter rock eval data can sometimes be removed by special processing for immature rocks bimodal s2 peaks and pi values over 0 2 indicate contamination pyrolysis downgrades organic poor clay rich rocks which show lower hi and higher tmax values than isolated kerogen because of adsorption of pyrolyzate on the clays tmax values for small s2 peaks 0 2 mg hc g toc are unreliable tmax is affected by maturation organic matter type contamination and the mineral matrix s3 is sensitive to inorganic and adsorbed carbon dioxide and to instrumentation problems acidification of carbonate rich samples and proper maintenance improves s3 measurement constant sample weights 100 mg are recommended below a threshold weight tmax increases by up to 10 c and other parameters decrease organic rich samples which overload the detector can be diluted with carbonate detector linearity is determined by pyrolyzing various weights of an organic rich rock

chemometric differentiation of crude oil families in the san joaquin basin california chemometric analyses of geochemical data for 165 crude oil samples from the san joaquin basin identify genetically distinct oil families and their inferred source rocks and provide insight into migration pathways reservoir compartments and filling histories in the first part of the study 17 source related biomarker and stable carbon isotope ratios were evaluated using a chemometric decision tree cdt to identify families in the second part ascendant hierarchical clustering was applied to terpane mass chromatograms for the samples to compare with the cdt results the results from the two methods are remarkably similar despite differing data input and assumptions recognized source rocks for the oil families include the 1 eocene kreyenhagen formation 2 eocene tumey formation 3 4 upper and lower parts of the miocene monterey formation buttonwillow depocenter and 5 6 upper and lower parts of the miocene monterey formation tejon depocenter ascendant hierarchical clustering identifies 22 oil families in the basin as corroborated by independent data such as carbon isotope ratios sample location reservoir unit and thermal maturity maps from a three dimensional basin and petroleum system model five families originated from the eocene kreyenhagen formation source rock and three families came from the overlying eocene tumey formation fourteen families migrated from the upper and lower parts of the miocene monterey formation source rocks within the buttonwillow and tejon depocenters north and south of the bakersfield arch the eocene and miocene families show little cross stratigraphic migration because of seals within and between the source rocks the data do not exclude the possibility that some families described as originating from the monterey formation actually came from source rock in the temblor formation

rapid development and infilling of a buried gully under cropland central belgium abstract analysis of contemporary and past gully erosion and infilling processes allowed to reconstruct the long term evolution of a permanent gully system under cropland an active and a buried gully under cropland were investigated the recent sediment deposits within the active gully adjacent to the buried gully showed that the recent gully was filling in at a mean rate of 6 4 cm a 1 in the buried gully several erosion and deposition phases could be identified and the type of deposited sediments revealed a complex infilling history charcoal pottery and brick fragments of different sizes were found at all depths of the gully infilling their age indicates that the first gully incised after the midst of the 17th century most probably in the second half of the 18th century or the early 19th century gully morphology and analogy with the processes in the recent gully indicate that the buried gully filled in rapidly overall five cycles of cut and fill occurred in 350 years or less and four cycles even within little less than a few decades indicating that gully development and infilling under cropland can be very rapid processes

tectonic depositional and diagenetic history of monterey formation miocene central san joaquin basin california the miocene monterey formation in the central san joaquin basin of california consists of biogenic siliceous rocks with a significant terrigenous clastic component correlation of electric logs in conjunction with analysis of outcrop sections core samples and paleontologic data suggests that deposition of the monterey was controlled by an interplay of basin geometry san andreas related tectonics fluctuations in sea level and changes in climate the basin is bounded on the east by the sierran magmatic arc complex and on the west by the san andreas fault during the late saucesian through early mohnian 20 10 ma the basin was reshaped by tectonism related to the migrating mendocino triple junction creating a broad gently sloping shelf to the east that cut off the supply of clastics to the central basin with the subsequent evolution of the san andreas fault the salinian block was emplaced along the western basin margin restricting the seaway and permitting low oxygen nutrient rich waters to occupy the basin as a result laminated organic rich fine grained pelagic to hemipelagic sediments of the monterey formation were deposited a warmer climate during saucesian through luisian time with less intensive upwelling le to more calcareous less siliceous sedimentation a cooling trend during late miocene time 10 5 ma increased upwelling activity diatom productivity in the water column and deposition of diatomaceous debris although turbidites accumulated on the basin floor and terrigenous clastics were deposited on the eastern shelf relatively undiluted diatomaceous deposits developed on outer shelves and slopes atop anticlinal banks generated by wrench tectonism and in some areas of the basin floor a mid mohnian eustatic sea level rise caused fine grained deposition to extend onto the eastern shelf slightly later a mid late mohnian period of exceptionally cool temperatures resulted in the most extensive development of upwelling related siliceous sediments throughout the basin with diagenesis these deposits formed the siliceous shales and porcelanites of the monterey formation high sedimentation rates coincident with a eustatic drop in sea level led to clastic progradation in latest miocene time as the basin filled analysis of organic matter from cores of the monterey formation shows that kerogen type reflects overall sedimentation trends samples from northern and eastern areas contain abundant terrestrial organic matter whereas samples from western areas mostly contain marine kerogens source potential is thus strongly influenced by geographic locality as well as lithology maturity of kerogen was assessed using vitrinite reflectance thermal alteration indices and pyrolysis techniques the latter two appear to be the more reliable indicators of organic matter maturity in the monterey formation of the san joaquin valley although much of the monterey formation in the study area may be thermally immature portions are probably generating hydrocarbons today in deep synclinal areas

spatial analysis of factors controlling the presence of closed depressions and gullies under forest application of rare event logistic regression abstract although numerous studies have reported on past geomorphic change it is a common difficulty to identify the relative role of driving human or climatic forces to that end the possibilities of rare events logistic regression are explored in a 1300 hectare large ancient forest in central belgium here 43 permanent gullies and 71 closed depressions were observed that were probably caused by an anthropogenically induced land use change in the past this human origin was confirmed for a limited number of case study areas by recent geomorphic research with dating and soil profile analysis the objective of this study is to analyze the factors controlling the position of all gullies and closed depressions in the study area and investigate their mutual relation this will indicate whether or not the results obtained for the small case study areas can be extrapolated to the rest of the geomorphic features found in the whole study area the obtained logistic regression models show that both anthropogenic and physical factors are important in the spatial distribution of both geomorphic features for the prediction of the occurrence of closed depressions anthropogenic factors are most important however the probability of finding a depression is larger close to reported prehistoric and roman archaeological sites on well developed undisturbed luvisols and on northeast to southeast facing slopes the local slope gradient of the soil surface is the most important factor in the multivariate model for predicting the presence of the permanent gullies the occurrence probability of permanent gullies is also larger on northeast to southeast facing slopes the anthropogenic factor expressed by the distance to the closed depressions is significant as a univariate model this suggests that a critical slope gradient is a prerequisite for gully incision but gully formation still needs to be triggered by a human induced land use change it can therefore be concluded that both the gullies and the closed depressions in the meerdaal forest are related to past human activity either directly through mining of loess or indirectly through runoff production on cropland this study also showed the potential of rare events logistic regression for analyzing the spatial pattern of geomorphological features in relation to environmental factors

late devonian carbon isotope stratigraphy and sea level fluctuations canning basin western australia the upper devonian reef complexes of the canning basin contain some of the world s best exposed continuous stratigraphic sections through the frasnian famennian boundary the facies distribution and composition of these reef complexes record interactions among sea level changes sediment supply ocean chemistry and paleoecology changes in relative sea level produced spatial shifts in reef platform development and regional changes in sediment supply that can be correlated across facies boundaries using a combination of sequence stratigraphy biostratigraphy and carbon isotope stratigraphy during the lowstand interval below the frasnian famennian boundary the reef margin advanced down the reef slope in shallow water environments and siliciclastics locally dominated in the marginal slope environment compilation of a broad late frasnian to early famennian sequence stratigraphic framework for the canning basin demonstrates that transgressive intervals correlate to positive carbon isotopic excursions within the basin these isotopic shifts also can be correlated to time equivalent positive carbon isotopic excursions reported from transgressive intervals in europe thus the late frasnian transgressions in the canning basin were primarily eustatic rather than tectonic in origin and positive carbon isotopic signatures of the kellwasser horizons are globally correlative c 2002 elsevier science b v all rights reserved

searching for ancient forests a 2000 year history of land use in northeastern french forests deduced from the pollen compositions of closed depressions evidence of the agricultural use during roman or medieval times of forested areas formerly considered to be ancient as well as legacies of this former land use on plant biodiversity and soil pro

sequence stratigraphy of a late devonian ramp situated reef system in the western canada sedimentary basin dynamic responses to sea level change and regressive reef development the alexandra formation located in the northwest territories of canada is formed of a late devonian frasnian reef system that developed on a gently sloping epicontinental ramp in the western canada sedimentary basin high resolution sequence stratigraphic analysis of its deposits delineates two reef complexes that are separated by a type i sequence boundary the second reef complex developed on the outer ramp basinward of the first after sea level fell 17 m stratigraphic complexity of the second reef complex was a result of its initiation during forced regression and its development through an entire cycle of sea level rise followed by sea level fall its highstand systems tract was not characterized by high rates of carbonate production or sediment shedding rather these features took place as sea level fell after its highstand systems tract the sequence stratigraphic framework of this regressive reef system highlights a number of depositional parameters that differ from high relief shelf situated reef systems with steep narrow margins these have implications for understanding the controls on the development of ramp situated reef systems and the nature of reef systems with gently sloping profiles this study demonstrates that the development of stromatoporoid reef systems may be far more complex than generally realized and that high resolution sequence stratigraphy may provide the tools for better understanding of complex often enigmatic aspects of these systems

scale model simulations of the deposition of loess in hilly terrain the sedimentation of loess in a 40 km2 area on the northern border of the belgian loess belt is investigated by means of wind tunnel experiments loess deposition is simulated on a relief scale model for different wind directions it appears that simulation with northeast winds produces a loess deposition pattern that coincides closely to the field pattern which may be an indication that the loess bearing winds at the end of the weichselian came from the northeast loess deposition occurs preferably on windward slopes and not on leeward ones the wind shadow concept which is important in the case of sand deposition may therefore not necessarily apply to fine materials such as fine silt and clay

closed depressions in the european loess belt natural or anthropogenic origin abstract closed depressions cds are typical geomorphological features of the loess belt in europe cds have been reported in several regions of the european loess belt where they are described as hollows mardeles wymoki crovuri bludtsa and zapadiny the natural and anthropogenic origins of cds are debated in literature moreover no comprehensive review of the geomorphic properties or the evolution of these depressions exists therefore this paper reviews the characteristics of cds in the european loess belt and attempts to better understand their genesis based on detailed case studies the main morphometric features as well as sediment deposits within cds in several sub regions of europe were analysed and compared morphometric properties of cds from the west european and east european loess belt were investigated through a comparison of cds from two representative regions i e east poland and central belgium in both study areas cds under cropland are similar however a comparison of morphological features of cds under forest revealed clear differences suggesting a different origin of cds from both regions infilled sediments in cds show various litho genetical features in different regions of the european loess belt the morphometric features ages and stratigraphy of infillings clearly indicate that both anthropogenic and natural processes have shaped these landforms within the loess belt of europe cds observed in eastern europe may have a very different origin than those documented in western europe detailed analysis of cds in poland and in neighbouring regions of east europe suggest that cds are natural landforms thermokarst deflation and dissolution of loess are reported as probable genetic processes in contrast several studies in western europe indicate a dominant anthropogenic origin i e digging of calcareous loess or marls bomb and mining craters collapse of underground limestone quarries although cds formed by natural processes i e piping dissolution of limestone and salt lenses below the loess cover are reported as well cds act as important archives allowing one to reconstruct both natural and anthropogenic processes operating in the past as cds store most sediments eroded within their catchment they provide ideal sediment traps to assess long term erosion rates in these environments which have hitherto been under researched more research is needed to unravel the genesis and evolution of these depressions to better understand the importance of the late glacial and holocene stages for the morphogenesis of the loess belt in europe

the transient nature of the empty bucket model of reef sedimentation abstract the geometry of modern reefs has been likened to an empty bucket with the narrow reef rim comprising the container pail that encloses the water filled bucket while the analogy is valid the assumption that this constitutes a final geometry is not examples from the indian pacific and atlantic oceans individually and collectively demonstrate current filling of the lagoons by reef perimeter sand aprons since sea level only approximated its present position 3 to 6 ky ago it follows that the observed extent of modern highstand lagoon filling is minimal if the filling process was to continue unabated the result would be a flat topped bank but during the pleistocene low stands of sea level aborted the filling process extrapolating these relationships to the geologic record suggests that the empty bucket model of unfilled reef lagoon space is greatest during icehouse high frequency glacial fluctuations of sea level alternatively filled buckets in which cycle thickness approximates accommodation space are probably largely restricted to greenhouse time intervals the co occurrence of quaternary high amplitude frequency sea level changes with rapidly growing scleractinian corals probably enhanced the occurrence of empty bucket morphologies

reconstruction of late holocene slope and dry valley sediment dynamics in a belgian loess environment to unravel the evolution of a dry valley in the belgian loess area soils and sediments along a slope catena were studied in detail a 67 m long trench was opened from the upper slope to the centre of the valley bottom the exposed soils and sediments showed evidence of severe soil erosion and other human disturbances that significantly changed the valley topography the early holocene slope gradient was up to 25 whereas now it is less than 10 in the thalweg a remnant of the early holocene soil was found underneath colluvial deposits which were more than 3 m thick a chronology for the valley evolution was established based on ams 14c dating of charcoal fragments and optical dating of colluvial sediments the first sediment deposition occurred in the early iron age with an average sedimentation rate of approximately 3 4 1 3 t ha per yr this increased to c 5 4 2 2 t ha per yr during the roman period and further to 18 0 2 2 t ha per yr in the middle ages although sediment accumulation in the

the history of soil erosion and fluvial deposits in small catchments of central europe deciphering the long term interaction between humans and the environment a review abstract during the last few decades many case studies focused on the dynamics of fluvial systems in response to hillslope erosion land use impact and climate changes this paper will review the current state of knowledge of the dynamics of past soil erosion and gullying in small catchments

petroleum geology of the giant elm coulee field williston basin the elm coulee field of the williston basin is a giant oil discovery in the middle bakken formation devonian mississippian discovered in 2000 horizontal drilling began in the field in 2000 and to date more than 600 wells have been drilled the estimated ultimate recovery for the field is more than 200 million bbl of oil 31 8 million m3 the bakken formation in the field area consists of three members 1 upper shale 2 middle silty dolostone and 3 lower siltstone the total bakken interval ranges in thickness from 10 to 50 ft 3 1 to 15 3 m over the field area the upper shale is dark gray to black hard siliceous slightly calcareous pyritic and fissile the shale consists of dark organic kerogen minor clay silt size quartz and some calcite and dolomite the kerogen consists mainly of amorphous material and the organic material is distributed evenly throughout the shale interval not concentrated in laminations or lenses the upper shale ranges in thickness from 6 to 10 ft 1 8 to 3 1 m over the field area the middle member consists of a silty dolostone and ranges in thickness from 10 to 40 ft 3 1 to 12 2 m the lower member in the elm coulee field consists of brownish gray argillaceous organic rich siltstone burrowing and brachiopod fragments are common in the lower member this facies is equivalent to the lower bakken black shale facies on the northern side of the field and is interpreted to be an updip landward equivalent to the deeper water black shale facies the lower member ranges in thickness from 2 to 6 ft 0 61 to 1 8 m based on the abundance of fossil content and amount of burrowing the members of the bakken formation are interpreted to have been deposited under aerobic middle member common burrows and rare fossils dsyaerobic lower member common fossils and lesser amount of burrows and anaerobic conditions upper member rare fossils and burrows the main reservoir in elm coulee field is the middle member which has low matrix porosity and permeability and is found at depths of 8500 to 10 500 ft 2593 to 3203 m the current field limits cover approximately 450 mi2 1165 km2 the middle bakken porosities range from 3 to 9 and permeabilities average 0 04 md overall the reservoir quality in the middle bakken improves upward as the amount of clay matrix decreases the middle bakken is interpreted to be a dolomitized carbonate shoal deposit based on subsurface mapping and dolomite lithology the main production is interpreted to come from matrix permeability in the field area occasional vertical and horizontal fractures are noted in cores the vertical pay ranges in thickness from 8 to 14 ft 2 4 to 4 3 m the bakken is slightly overpressured with a pressure gradient of 0 53 psi ft 0 02 kpa m horizontal wells are drilled on 640 to 1280 ac 259 to 518 4 ha spacing units long single laterals dual laterals and trilaterals have all been drilled in the field the horizontal intervals are sand gel and water fracture stimulated initial production ranges from 200 to 1900 bopd 31 8 to 302 1 m3 day initial potential rates for vertical wells are generally less than 100 bopd 15 9 m3 day the upper bakken shale probably also contributes to the overall production in the field the exact contribution is unknown but estimated to be less than 20 of the total production the elm coulee field illustrates that the bakken petroleum system has enormous potential for future oil discoveries in the williston basin

the intrinsic effect of shape on the retrogradation motif and timing of drowning of carbonate patch reef systems lower frasnian bugle gap canning basin western australia the evolution and architecture of a set of retreating lower frasnian patch reef outcrops in the canning basin of western australia were evaluated and their depositional and stratigraphic contacts spatially recorded using digital surveying tools the geological data together with high resolution digital elevation models were assembled in three dimensional visualization and modelling software and subsequently used for building two dimensional surface models and three dimensional volumetric models numerical data on geometry and shape were extracted from these models and used to quantitatively assess the retrogradation motif of patch reef development the development of the patch reefs comprises three stages during stages 1 and 2 the patch reefs exhibited an overall retrogradational escarpment type configuration displayed by on average 60 steep reef margin walls that lacked the support of coeval slope deposits the subdivision between stages 1 and 2 is based on minor backstepping reducing less than 10 of the platform top area the onset of stage 3 is recognized by stromatolite development fringing reef margin walls during stage 3 an aggrading accretionary reef margin developed comprising allochthonous and autochthonous slope deposits both types of slope deposit onlap the previous stages and are distributed unevenly with allochthonous slope deposits being noticeably absent around the smaller and more elongate patch reefs the variation in distribution of slope sediment type can be explained by the amount linked to platform size of platform top shedding small patch reefs were unable to fill the available accommodation adjacent to escarpments with allochthonous slope sediments and were thus encroached by autochthonous slope sediments the variation which cannot be explained by the size difference in the platform top factory has been related to the difference in perimeter length for patch reefs with similar platform top production areas a more elongate patch reef inherits a longer perimeter and a proportionally smaller volume of allochthonous slope sediment per margin length will be transported to the flanks thus the more elongate patch reef intrinsically contained more sites within which autochthonous slope sediments developed digital outcrop modelling and numerical evaluation of the evolution of the patch reefs revealed the major differences in retrogradation motif the quantified variations in progressive decline of platform top area with height were confirmed by hypothetical decline curves for ellipse shaped carbonate systems for which aspect ratio ratio between length and width varied this mathematical model demonstrates that the progressive decline of the production area is highly sensitive to shape and can be used to numerically assess and predict the relative timing of drowning i e when the platform top production area becomes nil of retrogradational isolated carbonate platforms that are controlled by high accommodation wider implications can be surmised for highstand systems tracts and prograding carbonate systems for example for equally sized platforms with hypothetically similar carbonate factories and identical external forces the potential to prograde by platform top shedding is higher with a smaller aspect ratio because the shorter perimeter implies less accommodation space needing to be filled up to commence slope progradation clearly there are intrinsic effects of shape on the development of carbonate platform systems

a basin modeling and organic geochemistry study in the vallecitos syncline san joaquin basin california abstract the vallecitos syncline is a westerly structural extension of the san joaquin basin the vallecitos oil field comprised of eight separate areas that produce from cretaceous and paleogene reservoirs accounted for 5 4 mmb of oil and 5 6 bcf associated of gas through 2010 however exploration for oil and gas in the vallecitos area is challenging due to structural complexity and limited data the purpose of this study is to evaluate whether source rocks are actively generating petroleum in the vallecitos syncline and to improve our understanding of burial history and timing of hydrocarbon generation we conducted biomarker analysis on twenty two oil samples from the vallecitos syncline source related biomarkers show two genetic groups of oil which originated from two different source rocks these results differ from earlier published interpretations in which the kreyenhagen formation is the only source rock in the vallecitos syncline and suggest that the cretaceous moreno formation in the syncline also is an active source rock stratigraphic evidence and modeling suggest that late cenozoic episodes of erosion due to folding and uplift removed significant overburden on the flanks of the syncline to better understand the petroleum systems and clarify the total active source rocks in the area 2d burial histories were generated through the vallecitos syncline a published cross section through the deepest part of the syncline was selected to conduct thermal history basin evolution and migration analyses the 2d model results indicate that the lower kreyenhagen formation has various maturities within the formation at different locations in the present day syncline the basal part of the kreyenhagen formation is in the dry gas window and maturity decreases away from the central part to the flanks it remains immature along shallow portions of the present day flanks in contrast the basal part of the moreno formation achieved extremely high maturity past the gas generation zone but is in the oil generation zone on the flanks of the syncline at shallow depth all of our geochemical and 2d model results suggest that there are two active source rocks in the vallecitos syncline accordingly we propose that there are two active petroleum systems in the vallecitos syncline

assessment on tight oil resources in major basins in china abstract large scale commercial development of shale gas and tight oil resources in north american and continuous discoveries of tight oil in china lead to the recognition of the importance of assessment on tight oil resources based on the characteristics of china s tight oil reservoirs and exploration status this paper discusses a workflow focusing on in place resource evaluation in the workflow a resource richness analogy approach rr aa is proposed for assessment of tight oil resources in less explored areas a genesis statistics assessment approach gs aa for lacustrine tight oil resources with strong heterogeneity and regions where more delicate assessment is required and an eur analogy approach eur aa for assessment on recoverable tight oil by fully using available eur data of production wells after analyzing the geological characteristics of the formation of tight oil in the ordos bohai bay songliao junggar sichuan and other major basins the distributions of essential parameters such as reservoir thickness area and porosity have been defined and the parameter evaluation criteria have been established finally the tight oil resource potentials in the major basins in china have been evaluated using one of the three methods and the prospective areas of high resource abundance are outlined in each of basins the results from this study show that china s tight oil resources have a large potential and good exploration future the estimated in place tight oil resources are 12 580 109 tons mainly distributed in the ordos songliao bohai bay and junggar basins 15 most favorable zones are proposed having in place resources of 5 296 109 tons

integrated 3 d reservoir modeling based on 3 d seismic the tertiary malampaya and camago buildups offshore palawan philippines three dimensional 3 d seismic interpretation and drilling results indicate complex sedimentary geometries of the malampaya and camago build ups offshore palawan philippines with localized progradation due to unidirectional offbank transport alternating with vertical aggradation successive reduction of size during buildup growth and backstepping of the protected landward margin in response to transgression ultimately appear to have triggered the demise of carbonate production and platform drowning the shallow water platform top sediments repeatedly show signs of subaerial exposure before reflooding a modeling functionality was developed to allow development of multiple scenario 3 d reservoir models in an exploration or appraisal stage the model enables merging of seismic scale observations based on 3 d volume and horizon analyses with subseismic scale information from well data however inherent noise within the seismic data introduced by the complex buildup morphology has resulted in inconsistent attribute distribution and fault dimming these difficulties are compounded by erratic velocity distribution within the limestone nonhyperbolic move out and a narrow relatively low frequency spectrum all of which prevent the use of the 3 d seismic volume as hard data but rather allow its use as a soft constraint for guiding the geological interpretation and ultimately the modeling process seismic data quality in such complex morphologic settings and scarcity of well data hamper greatly the use of geostatistically driven modeling approaches therefore a new functionality was developed within shell s proprietary integrated 3 d modeling suite geocap which allows deterministic model reservoirs using seismic horizon and volume interpretation sequence and cyclo stratigraphic architecture and the concept of reservoir rock type seismic velocity in clean carbonate formations is predominantly a function of porosity distribution to assess time to depth conversion uncertainty the reservoir rock type based models were first produced in the time domain only after differential 3 d depth conversion of these models could the scenarios be reconstructed in the depth domain the depth models subsequently were used to derive permeability and saturation 3 d distortions and thus hydrocarbon volumes for each deterministic scenario the models were then used for simulation purposes

the origin of closed depressions in northeastern france a new assessment over 10 000 closed depressions cds are found in the silty plains of northeastern france these small wetlands support the growth of rare plant species although their origins which could be anthropogenic or geologic due to salt gypsum lens dissolution have been debated for 150 years they have not yet been the focus of an integrated study in 39 geological borings along a 15 km strip no salt gypsum lenses and more than 260 cds were recorded using lidar all of the investigated cds have a bathtub form with a flat bottom complete excavations clearly showed a cut contact between the sediment and the horizontal marl substratum at the bottom and a cut at the edges of the upper marl layers radiocarbon dating of sediment bottoms showed that sedimentation began between the second iron age and the roman period the frequencies of pollen and sporormiella type depict an open landscape with grassland pasture and cropland these convergent findings challenge the hypothesis that cds formed naturally and suggest that they area instead anthropogenic because no soil deposits were found around the cds digging may have been intended to marl the surrounding acidic silty soils the high density and small size of cds will allow the detailed reconstruction of landscape and biodiversity modifications in the region for the two last millennia

the impact of natural and anthropogenic processes on the evolution of closed depressions in loess areas a multi proxy case study from naleczow plateau eastern poland abstract closed depressions are reported in loess landscapes in various parts of europe the anthropogenic and natural origin of closed depressions is highly debated in literature closed depressions are an important component of the landscape in loess areas of the lublin upland furthermore they perform the role of local closed sediment basins creating unique conditions for the preservation of soils and colluvial sediments along with the record of the evolution of the holocene landscape occurring under the influence of climate changes and human activity the study objective was to evaluate the contribution of natural and anthropogenic processes influencing the origin and evolution of closed depressions the naleczow plateau is composed of loess whose thickness varies from a few meters to 30 m 1761 closed depressions have been documented within the naleczow plateau 493 km 2 a detailed investigation was conducted within selected closed depression dissected by a deep and long road trench the studied form was 40 m long 26 m wide and 0 7 m deep the analyzed exposure 20 m long and 7 m high presents a cross section of the closed depression fieldwork and subsequent laboratory analyses were conducted morphological micromorphological microstructural geochemical physico chemical osl and 14 c dating archaeological and historical correlations were also performed the primary bottom and slopes of the studied depression are composed of loess in situ overlain by late glacial holocene fossil soil periglacial structures such as deformed ice wedge pseudomorphs cracks and lenses macro structures were documented in the loess and palaeosol at the bottom of the closed depression the depression is filled with neoholocene soil sediment sequences consisting of 2 layers of colluvial sediments separated by neoholocene subfossil soil they constitute a record of the two stages of cd infillings in the holocene connected with human agricultural activity lasting from the neolithic up to modern times a detailed analysis of the loess late glacial holocene fossil soil and holocene colluvial sediments made it possible to distinguish the stages of evolution of closed depression influenced by changing environmental conditions and human activity during the late glacial and holocene