thermoluminescence dating of a stillbay howiesons poort sequence at diepkloof rock shelter western cape south africa new excavations have been undertaken at diepkloof rock shelter drs south africa since 1999 it is one of the very few sites where howiesons poort and stillbay assemblages can be collected from the same archaeological sequence these middle stone age techno complexes are particularly interesting for their af nities with the much younger later stone age facies and their association with evidence for symbolic behaviour establishing their chronology is therefore particularly important for the understanding of the apparition and the evolution of the so called modern behaviours data already available suggest ages ranging from 55 to 80 ka for the howiesons poort and from 70 to 80 ka for the stillbay techno complexes in several south african sites the thermoluminescence dating undertaken at drs on 22 stone samples originating from the entire stratigraphic record indicates intervals starting 10 50 ka earlier for these techno complexes in this site possible caveats in the dating process are examined but to the best of our current knowledge must be rejected

a coal depositional model for the durham coal measures of ne england the upper carboniferous westphalian coal measures of the durham coalfield were deposited on a broad flat deltaic plain in early westphalian a times a lower delta plain setting prevailed evolving through southward deltaic progradation into an upper delta plain by mid westphalian a detailed facies analysis of large opencast exposures supported by extensive subsurface data has shown that a hierarchy of depositional controls operated across the durham area during westphalian times i on the large scale depositional geometry was controlled by patterns of major delta progradation and switching ii on the medium scale by a combination of structurally and compactionally induced subsidence and iii on the small scale by local sedimentary processes and subsidence patterns these observations form the basis of a coal depositional model for the durham coal measures which predicts that the thickest coals are to be found in upper delta plain domains controlled by compactional subsidence and not underlain by substantial channel sandstones this model may also be applicable to other coalfields of northern england and to ancient delta plain sequences elsewhere in the world

geologic and geomorphic controls of coal development in some tertiary rocky mountain basins usa abstract previous investigations have not well defined the controls on the development of minable coals in fluvial environments this study was undertaken to provide a clearer understanding of these controls particularly in of the lower tertiary coal bearing deposits of the raton and powder river basins in the rocky mountain region of the united states in this region large amounts of coals accumulated in swamps formed in the flow through fluvial systems that infilled these intermontane basins extrabasinal and intrabasinal tectonism partly controlled the stratigraphic and facies distributions of minable coal deposits the regional accumulation of coals was favored by the rapid basin subsidence coupled with minimal uplift of the source area during these events coals developed in swamps associated with anastomosed and meandering fluvial systems and alluvial fans the extensive and high rate of sediment input from these fluvial systems promoted the formation of ombrotrophic raised swamps which produced low ash and anomalously thick coals the petrology and palynology of these coals and the paleobotany of the associated sediments suggest that ombrotrophic raised swamps were common in the powder river basin where the climate during the early tertiary was paratropical the paleoecology of these swamps is identical to that of the modern ombrotrophic raised swamps of the baram and mahakam rivers of borneo

effects of overbank deposition on the quality and maceral composition of the herrin no 6 coal pennsylvanian of southern illinois abstract a detailed study of the effects of overbank deposition on the quality and maceral composition of the herrin no 6 coal member carbondale fm middle pennsylvanian in southern illinois was done using proximate total sulfur and maceral analyses channel samples were taken of the herrin no 6 coal and descriptions of the rocks overlying the coal were made at nine locations the herrin no 6 coal in the study area is known to 3ave a high ash content toward the walshville channel a channel sandstone possibly representing a distributary channel that existed during herrin peat deposition sulfur content is knwon to in crease markedly where marine or marginal marine rocks directly overlie the coal and decrease where overlain by thick non marine shale three types of overbank deposits are found in the study area accounting for the changes in coal quality and composition overbank flooding as sheet flow off the levee of the walshville channel introduced suspended material into the peat swamp the suspended material either produced numerous shale laminae or intermixed with the peat producing an increased ash content of the resultant coal close to the walshville channel contemporaneous with the introduction of clastic material by overbank flooding partial oxidation of the peat occurred oxygenated flood water was able to oxidize the peat increasing the pseudovitrinite content of the resultant coal fire splay deposits forming the partings occurred when the swamp was flooded after a dry period or a swamp fire the build up of crevasse splay deposits forming the energy shale helped decrease sulfur content of the herrin no 6 coal in portions of the study area the non marine shaly distal crevasse splay facies formed an impermeable barrier to downward movement of sulfate ion bearing marine water during deposition of the marine units above the energy shale high sulfur coal is associated with the sandy crevasse distributary channel fill facies and bay fill facies of the energy shale or where the energy shale is not present the crevasse distributary channel fill facies allowed marine water to permeate through it reaching the peat and resulting in high sulfur coal high sulfur coal found where the bay fill facies or other marine units directly overlie the coal is a result of marine water being able to permeate the peat directly

luminescence dating at diepkloof rock shelter new dates from single grain quartz diepkloof rock shelter in south africa s western cape has been the subject of two different luminescence dating projects in recent years jacobs et al 2008 tribolo et al 2013 with somewhat divergent results this paper presents dating analysis of three additional samples from diepkloof as well as one sample each from kathu pan 6 and hollow rock shelter also in south africa these samples were collected in 1995 prior to the other two projects analysis of single grain quartz shows that the samples are near saturation conventional rejection criteria when applied to dose recovery data result in an underestimation of dose for high administered doses applying the fast ratio durcan and duller 2011 duller 2012 as a rejection criterion removes this underestimation and preferentially rejects grains from the samples with low equivalent dose values this makes the ages older than they would have been without this criterion age results are older than those presented by jacobs et al 2008 and slightly older or equivalent to those provided by tribolo et al 2013

episodes with reefal formations during the aptian late cretaceous in the gulf of hammamet northeastern tunisia insights from seismic reflection and wells data in tunisia the aptian maastrichtian period is characterized by the development of rudist bearing carbonate platform through aptian late cretaceous period rudist build ups are associated with ramp systems paleohighs and tilted blocks the platform growth was controlled either by the morphology of the antecedent substrate or by sea level variation or by regional tectonic factors in fact eustasy accustomed the initial pattern of the rudist bearing platform while tectonics guided the geometry and the spatial distribution of platform facies and rudist build ups in the gulf of hammamet a seismic interpretation and wells analyses helped us identify reef buildups and reconstruct the episodes of their development five episodes of aptian upper cretaceous platform units are distinguished by changes in platform geometry that are marked by facies variation these episodes are characterized by a succession of distally steepened carbonate ramps from the aptian to the albian cenomanian period during the late turonian the carbonate platform has evolved into homoclinal ramp geometry this morphology was reinforced by the campanian compressive phase furthermore ramps and their associated deposits and build ups form prolific petroleum source and reservoir systems they offer a range of subtle stratigraphic play types and lateral facies variations reservoirs can be found in mid or outer ramp isolated build ups

delineation of saltwater intrusion zones using the time domain electromagnetic method the nabeul hammamet coastal aquifer case study ne tunisia the time domain electromagnetic method tdem is applied to monitor to delineate and to map the saltwater intrusion zones in the mediterranean plio quaternary aquifer forty two tdem soundings were carried out in the coastal plain of nabeul hammamet region ne tunisia tdem resistivity data were correlated with the existing borehole logging data to assign them to a particular lithology and to provide information about the position of the freshwater seawater transition zone the geoelectric sections showing the vertical configuration of seawater intrusion with the brackish salty saturated zones have a resistivity ranging from 0 1 to 5 m and are detected at a depth lower than 1 5 m the salinized zones are located at nabeul sidi moussa sidi el mahrsi al gasba and mrazgua and at hammamet touristic zone of hammamet north and south baraket essahel and reached a distance of 4 km from the coastline indicating a severe state for the aquifer in these zones these tdem results are confirmed by the increase of chloride concentration content in the analysed water samples of monitoring wells moreover in the northeastern part the presence of a saltwater front located far from the coast and along the nw se major surface fault can be explained by two hypothesis i this fault seems to provide a conduit for seawater to move readily towards the water wells and ii the clay and gypsum infiltration of marine messinian deposits through the fault plane leads to low resistivities finally it comes out from this study that tdem survey has successfully depicted salinized zones of this coastal aquifer copyright 2012 john wiley sons ltd

petrographical and organic geochemical study of the kovin lignite deposit serbia abstract the origin of the organic matter om and the characteristics of the depositional environment of lignites from the upper miocene kovin deposit hosting three coal seams of serbia were evaluated based on petrographic data bulk organic geochemical parameters biomarker analysis and stable isotope geochemistry 13c of individual biomarkers samples were collected from four boreholes gd 601 and gd 603 the a field and kb 79 and kb 91 the b field representing different parts of coal seams i ii and iii investigated lignites are typical humic coals the om of lignites is derived from woody vegetation and herbaceous peat forming plants with prevalence of the former in most samples peat forming vegetation is characterized by abundant decay resistant gymnosperm coniferous plants followed by a low amount of angiosperms lignite forming plants mostly belonged to the gymnosperm families cupressaceae taxodiaceae phyllocladaceae and pinaceae slight input of ferns fungi and aquatic macrophyta to lignite om is also evident distributions of hopanoids and isotopic compositions of these biomarkers reflect the activity of various microbial populations represented by methanotrophic chemoautotrophic and heterotrophic bacteria during diagenesis prominent c28 28 30 bisnorneohop 13 18 ene was observed for the first time in the lignite extracts according to the 13c value it was probably derived from chemoautotrophic bacteria c28 28 30 bisnorneohop 13 18 ene could be one of the possible precursors of a series of orphan aromatic hopanoids bearing an ethyl group at c 21 via progressive aromatization peatification proceeded in a fresh water environment under variable redox conditions from anoxic to slightly oxic all three coal seams are heterogeneous the lower parts of the coal seams represent a topogenous fresh water peat mire with open water areas which was subjected to inundations the upper parts of coal seams represent a wet forest swamp with relatively stable conditions despite the observed variations in all three coal seams the mean values of petrographic and organic geochemical parameters suggest general increasing of wetness and establishment of more stable conditions from seam iii to seam i maceral and biomarker data indicate that rapid flooding of the bogs stopped peat growth in all three coal seams relatively frequent variations in all three coal seams followed by repetition of lignite characteristics depict well the pronounced seasonality e g short term cycles of the climate during late miocene in investigated area

a depositional model for the taylor coal bed martin and johnson counties eastern kentucky abstract this study investigated the taylor coal bed in johnson and martin counties eastern kentucky using field and petrographic techniques to develop a depositional model of the coal bed petrography and chemistry of the coal bed were examined multiple benches of the taylor coal bed were correlated over a 10 km distance three sites were studied in detail the coal at the western and eastern sites were relatively thin and split by thick clastic partings the coal at the central site was the thickest and unsplit two major clastic partings are included in the coal bed each represents a separate and distinct fluvial splay the taylor is interpreted to have developed on a coastal plain with periodic flooding from nearby structurally controlled fluvial systems doming is unlikely due to the petrographic and chemical trends which are inconsistent with modern indonesian models the depositional history and structural and stratigraphic setting suggest contemporaneous structural influence on thickness and quality of the taylor coal bed in this area

an appalachian isochron a kaolinized carboniferous air fall volcanic ash deposit tonstein the fire clay tonstein is a kaolinized airfall volcanic ash bed that was deposited in a widespread late carboniferous peat forming mire eleven samples from kentucky and west virginia spanning a distance of 200 km and two samples from tennessee and virginia indicate a characteristic mineralogical signature as compared with other appalachian tonsteins consisting of well crystallized kaolinite beta quartz crystal paramorphs sanidine ilmenite zircon and brookite detrital illite and quartz are rarely present or are in very small amounts which indicates rapid deposition in a mire several normal graded cycles in this tonstein suggest repeated episodes of pyroclastic activity that produced a composite ash layer a high silica alkalic rhyolitic source is suggested by the geochemistry of immobile elements and by electron probe analyses of glass inclusions in volcanic quartz from the fire clay tonstein the rare earth element plots chondrite normalized of the tonstein show a pronounced negative eu anomaly and relatively high concentrations of zr and th which are both indicative of a rhyolitic source probe analyses of the fire clay glass inclusions from four states indicate a chemically identical high silica rhyolite with peraluminous affinities 40 ar 39 ar sanidine plateau dating indicates an age of 312 1 ma for the fire clay tonstein which is consistent with previous 40 ar 39 ar dates for this tonstein this age is in agreement with a late westphalian b age in the european carboniferous chronostratigraphy on the basis of an age of 311 ma for the westphalian b c boundary a new isopachous map of the fire clay ash fall deposit indicates an area of 37 000 km 2 and a probable source to the present day southwest the deposit has a minimum preserved compacted volume of 2 8 km 3 which corresponds to an original uncompacted volume of about 20 km 3 this preserved volume indicates an ultraplinian volcanic explosion pindell and dewey 1982 proposed an andean type arc in this block during the late carboniferous prior to south american north american plate collision we hypothesize an associated back arc caldera system in the yucatan block to explain the high silica potassic rhyolitic ash that gave rise to the fire clay tonstein

petroleum geology of tunisia recent discoveries and important oil shows have proven the existence of hydrocarbons in newly identified depocenters and reservoirs in general except for some areas around the producing fields tunisia is largely underdrilled the national company etap has decided to release data and to publish a synthesis on the petroleum geology of tunisia the geology of tunisia provides a fine example of the contrast between alpine folding which typifies northern tunisia and the african craton area of the saharan part eastern tunisia corresponds to an unstable platform forming plains or low hills and extending eastwards to the shallow pelagian sea there are a wide variety of basins central and northern tunisia represents a front basin the saharan ghadames basin or the chott trough are sag basins the gulf of gabes was formed as a distension margin the gulf of hammamet is a composite basin and several transversal grabens cut across the country including offshore and are rift type basins all these features are known to be oil prolific throughout the world two large fields and many modest size pools are known in tunisia oil and gas fields in the surrounding countries namely the saharan fields of algeria and libya the large bouri fieldmore offshore tripolitania and discoveries in the italian part of the straits of sicily suggest a corresponding potential in tunisia exposed paleogeographic and structural maps balanced sections and examples of fields and traps will support an optimistic evaluation of the future oil exploration in tunisia less

stratigraphic and biofacies patterns in the middle pennsylvanian magoffin marine unit in the appalachian basin u s a abstract the magoffin marine unit is a middle pennsylvanian age interval of marine strata that directly overlies the taylor copeland and correlative coal zones in the appalachian basin for this study the magoffin was measured described and sampled at 17 localities along a northeast to southwest transect in the center of the middle pennsylvanian outcrop belt in eastern kentucky and west virginia throughout the study area the base of the magoffin is characterized by a thin dark highly fossiliferous limestone with a brachiopod dominated fossil assemblage the limestone base is usually overlain by a fining upward sequence consisting of fossiliferous dark shales or mudstones with mollusk dominated assemblages these dark mudstones include a fissile black shale with a distinctive posidonia fauna deposited over part of the study area the lower fining sequence is overlain by a thicker coarsening sequence bearing brachiopod dominated fossil assemblages the lower beds of the magoffin particularly the basal limestone are persistent and relatively uniform throughout the study area in contrast strata in the upper part of the magoffin sequence show a high degree of geographic variability with localities in the southwestern half of the study area showing two successive thick coarsening upward sequences of strata while those to the northeast record a single thinner coarsening upward sequence the widespread uniform nature of the basal magoffin limestone appears to indicate rapid transgressive flooding of the coal swamp and associated environments accompanied by a hiatus in clastic influx into the magoffin seaway nearshore brachiopod faunas were replaced by deeper water possibly dysaerobic adapted mollusk faunas as transgression progressed culminating in the fissile black shales and monotaxic posidonia fauna deposited beneath a localized pycnocline during maximum transgression the onset of regression is indicated by the reverse of the stratigraphic sequence of faunas observed during transgression and by the return of rapid clastic influx into the basin

recent spatial and temporal changes in the stress regime along the southern tunisian atlas front and the gulf of gabes new insights from fault kinematics analysis and seismic profiles tectonic deformations in the southern atlassic front of tunisia saft and the gulf of gabes result from the nubia eurasia convergence this study based on the inversion of geologically determined fault slip vectors presents evidences for spatial and temporal changes in the stress state fault kinematics analyses reveal a temporal change in states of stress during the late cenozoic a paleostress miocene pliocene state is characterized by a regional compressional tectonic regime with a mean n134 09 e trending horizontal maximum stress axis 1 a modern quaternary to present day state of stress also corresponds to compressional tectonic regime with a regionally mean n05 10 e trending horizontal 1 the saft corresponds to two distinct domains a far foreland atlassic front related to contractional deformation associated with southward propagate thrusting and eastward the gulf of gabes characterized by normal component nw to wnw trending faults at the crustal margin scale probably related with a transtensional tectonic regime we propose that the spatial and temporal changes in the stress during the miocene pliocene and quaternary may result from the geodynamic evolution of the tunisian atlas in relation to the rotation of corsica sardinia blocks and the separation of the sicilian continental lithosphere from the ionian oceanic lithosphere these temporal and spatial stress changes along the saft and the gulf of gabes are probably the engine behind the moderate seismicity leading at the same time to a reactivation of the inherited major structures created during the evolution of the southern tethyan margin

paleoecology of the fire clay coal bed in a portion of the eastern kentucky coal field vertically continuous increment samples of the fire clay coal bed mid middle pennsylvanian late westphalian b collected from a portion of the central appalachian basin were studied palynologically petrographically and geochemically in order to partially reconstruct the paleoecology and processes associated with peat formation in the ancient fire clay paleomire results indicate that four compositional groups can be identified they are 1 a lycospora vitrinite dominant group characterized by high percentages of lycospora and vitrinite macerals and generally low but variable ash yields and sulfur contents 2 a mixed palynoflora high vitrinite group that petrographically is similar to group 1 except that it contains a more diverse palynoflora 3 a mixed palynoflora moderate low vitrinite group characterized by various admixtures of lycopsid fern and calamite miospores increased percentages of liptinite and inertinite macerals and low ash yields and sulfur contents and 4 a mixed palynoflora high ash yield group characterized by high percentages of small lycopsid fern and occasionally calamite and cordaite miospores high liptinite and inertinite contents high ash yields and moderate to high sulfur contents the fire clay coal bed contains a distinctive flint clay parting of probable volcanic origin that naturally divides the bed into two benches these two benches upper and lower are highly disparte in occurrence appearance and composition in the study area the lower bench generally is thin 0 5 m laterally discontinuous and mainly composed of dull mainly durain coal lithotypes ash yields typically are high sulfur contents generally are moderate to high compositional group 4 the mixed palynoflora high ash yield group defines all of the increments examined from the lower bench in contrast the upper bench is thick 0 75 m laterally continous and mainly comprised of bright mainly clarain coal lithotypes overall ash yields and sulfur contents for this bench are generally low although vertical variation is apparent all of the compositional groups occur in the upper bench in some columns notably those that are thick and uninterrupted by clastic partings groups 1 and 4 often occupy basal coal layers and groups 2 and 3 occur in higher layers other columns especially those taken in areas of thin 0 5 m fire clay coal are dominated by groups 1 and 4

sequence stratigraphy basin dynamics and petroleum geology of the miocene from eastern tunisia on the eastern margin of tunisia miocene limestones marl and siliciclastic deposits crop out poorly and are lacking in age diagnostic faunal content the biostratigraphic and lithostratigraphic subdivisions of these series are not clearly defined a regional study of subsurface sequences of this margin cap bon gulf of hammamet and sahel by means of sequence stratigraphy and subsurface structural analyses permits the identification of seven third order sedimentary sequences of inferred langhian to messinian age the boundaries of which are characterized by downlap and onlap toplap relationships these sequences include turbidites sands and sandstones deposited in connection with eustatic sea level changes and tectonic movements of east west and south north deep se ted faults due to the alpine and atlassic paroxysm stratal sequences are organized around miocene syndepositional grabens half grabens platforms and folds occurring inside and outside of regional tectonic corridors the geodynamic evolution of miocene basins has led to the deposition of turbiditic black argillaceous source rocks and sandstone and carbonate reservoirs that present new miocene petroleum targets the basin subsidence in response to the alpine atlassic orogeny has permitted the maturation of miocene source rocks oil generation and the formation of oil traps stratigraphic pinch outs and structural enclosures on the flanks of folds and on the borders of grabens

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

gis based subsurface databases and 3 d geological modeling as a tool for the set up of hydrogeological framework nabeul hammamet coastal aquifer case study northeast tunisia the subsurface data are a basic requirement for the set up of hydrogeological framework geographic information systems gis tools have proved their usefulness in hydrogeology over the years which allow for management synthesis and analysis of a great variety of subsurface data however standard multi layered systems are quite limited for modeling visualizing and editing subsurface data and geologic objects and their attributes this paper presents a methodology to support the implementation of hydrogeological framework of the multi layered aquifer system in nabeul hammamet nh coastal region ne tunisia the methodology consists of 1 the development of a complete and generally accepted hydrogeological classification system for nh aquifer system 2 the development of relational databases and subsequent gis based on geological geophysical and hydrogeological data and 3 the development of meaningful three dimensional geological and aquifer models using gis subsurface software rockworks 2002 the generated 3 d geological models define the lithostratigraphy and the geometry of each depositional formation of the region and delineate major aquifers and aquitards where results of the lithologic model revealed that there is a wide range of hydraulic conductivities in the modeled area which vary spatially and control the groundwater flow regime as well 17 texturally distinct stratigraphic units were identified and visualized in the stratigraphic model while the developed aquifer model indicates that the nh aquifer system is composed of multi reservoir aquifers subdivided in aquifers units and separated by sandy clay aquitards finally this study provides information on the storing management and modeling of subsurface spatial database gis has become a useful tool for hydrogeological conceptualization and groundwater management purposes and will provide necessary input databases within different groundwater numerical models

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

structural and stratigraphic perspectives on the uplift and erosional history of djebel cherichira and oued grigema a segment of the tunisian atlas thrust front

the western edge of the mediterranean pelagian platform a messinian mixed siliciclastic carbonate ramp in northern tunisia the marine messinian deposits of tunisia cover a narrow littoral strip some 300 km long between the northern bizerte and cap bon areas and the central eastern sahel region litho and biofacies analysis of six stratigraphic sections reveals the distinctive features of these deposits the lower messinian deposits are characterized by ubiquitous siliciclastics and abundant oolitic bioclastic limestones organized in an eastward facing ramp westward landward this ramp changes into coastal lagoons sometimes containing evaporites eastward the ramp passes to the reefal pelagian platform extending as far as lampedusa two main sedimentary cycles are distinguished 1 an early messinian siliciclastic retrogradational then oolitic bioclastic progradational cycle beni khiar formation and lower oued bel khedim formation 2 a late messinian brackish to continental cycle that probably accumulated in rapidly subsiding lagoons cued el bir formation and upper oued bel khedim formation the tunisian early messinian cycle is partly eustatically controlled but the late messinian cycle cannot be confidently correlated to other well known messinian series because of tectonic movements the lower messinian deposits of tunisia are also characterized by abundant suspension feeding organisms molluscs and bryozoans and rare corals calcareous algae echinoids and larger benthic foraminifers the proposed palaeoenvironmental model shows that the lower messinian ramp of tunisia was located on a current protected margin and subjected to continent derived sediment and nutrient supply eastward nutrient influx diminished and a shallow water isolated carbonate platform with coralgal facies developed between the western and the eastern mediterranean basins the main hydrological connection between these two basins occurred through a narrow seaway situated to the northeast of the pelagian platform south of sicily and malta

the post triassic sedimentary cover of tunisia seismic sequences and structure abstract a series of geological cross sections based on data from the new geological map of tunisia coupled with stratigraphic and structural studies indicate that a folded post triassic sedimentary cover was separated from the basement by a decollement zone located in triassic evaporitic deposits four depositional basins were formed during the triassic and liassic in an extensional regime on a presumably thinned continental crust geological fieldwork studies of metamorphic grade and gravimetric and magnetic surveys indicate that their depocentres shifted with time from basin to basin finally resulting in today s tellian and tunisian troughs to the north gafsa trough to the west of gabes and the tuniso libyan trough to the east subsidence in the latter trough commenced at the end of the cretaceous and is still continuing today there are four well defined seismic stratigraphic sequences comprising mesozoic and cenozoic sedimentary rocks each with distinctive lithoseismic characteristics we display the distribution and structure of these seismic sequences in a series of cross sections in addition we note that the regional tectonic style of tunisia has been greatly influenced by a conjugate strike slip fault system the role of wrench faulting has been well documented in the kasserine and other areas by detailed structural studies

geoarchaeological investigation of occupation deposits in blombos cave in south africa indicate changes in site use and settlement dynamics in the southern cape during mis 5b 4

relationships between coal quality and organic geochemical parameters a case study of the hafik coal deposits sivas basin turkey abstract this study provides coal quality organic petrographic and organic geochemical data on tertiary subbituminous coal of the hafik area northwestern part of the sivas basin turkey coal petrological studies along with proximate and ultimate analyses were undertaken to determine the organic petrographic characteristics of the hafik coals huminite reflectances were found to be between 0 38 and 0 48 corresponding to an organic material rich and coal layers values characteristic of low maturity this parameter shows a good correlation with calorific values average 21 060 kj kg and average t max 422 c mineral matter diagenesis indicating immaturity the studied coals and organic material underwent only low grade transformation a consequence of low lithostatic pressure therefore the hafik coals are actually subbituminous in rank rock eval analysis results show types ii iii and iii kerogens the organic fraction of the coals is mostly comprised of humic group macerals gelinites with small percentages derived from the inertinite and liptinite groups in this study organic petrographic organic geochemical and coal quality data were compared the hafik deposit is a high ash high sulfur coal the mineral matter of the coals is comprised mainly of calcite and clay minerals

a test for the analogy of tropical domed peat deposits to dulling up sequences in coal beds preliminary results abstract megascopic and microscopic characteristics of a domed peat deposit in sarawak malaysia were examined to test their analogy to dulling up sequences in low ash coal beds preliminary petrographic results show high concentrations 95 of vitrinite precursor material for all peat types but that fibrous peats in the upper central portion of the deposit contain more preserved plant material than peats toward the base and margins which although more decomposed contain large fragments 5 150 cm of wood these results present contradictory evidence in support of a dulling up model and suggests that modern tropical peat domes are perhaps poor petrographic analogues for dulling up sequences this deposit would produce an all bright coal seam with bright vitrain bands of variable thickness and amount set in bright high vitrinite matrix

sur l evolution des paleo environnements marins paleogenes des bordures occidentales du detroit siculo tunisien et leurs rapports avec les fluctuations du paleo ocean mondial abstract the study of benthic and planktonic foraminifera along five sections distributed over the jebel abderrahman anticlinal limits has made it possible to reexamine and precise the biostratigraphy of the palaeogene series which are visible on outcrops in the heart of the cap bon anticline we show that the studied series starts with the souar clay in the middle eocene at the level of the globigerinatheka subconglobata subconglobata zone bolli 1972 and ends with the mahmoud clay in the middle miocene at the level of orbulina suturalis zone cati et al 1968 thus we confirm that the lumachellic bar called burdigalian bar ain grab formation is in fact langhian the paleo ecological interpretation of the results allows us to precise the position of the cap bon marine environments within the framework of palaeogene paleo oceanography known up to now the eocene series of jebel abderrahman are sedimented just below the hinge line of the halk el menzel platform defined by bismuth and bonnefous 1981 within a transition area between temperate zones and tropical zones this area was inundated more often and more abundantly by tropical waters than the possagno italy and the prerif regions this fact reflects the determining influence of the palaeogene tethyan paleo currents along the southwestern borders of the sicilian channel securing the transfers of indian ocean waters towards the atlantic basin the importance of some clay formations embedded in the souar clays can be interpreted by the thermic variations and fluctuations of the paleogeoide which affected the world paleo ocean during the middle and late eocene in general the development of carbonates is correlated with a period of high sea level which separates two rapid falls of eustatic origin thus the reineche calcareous clay is associated with the beginning of the period of high sea level occurring between the rapid falls at the base of the globorotalia lehneri zone and at the top of the truncorotaloides rohri zone the sedimentary cycles of the jebel abderrahman reflect the eustatic cycles and supercycles the fortuna sandtones built up of detritic material with a complex history contain a microfauna which shows that this classic formation is an example of rhexistatic resumption which is synchronous with the world ocean cooling and took place after the rapid sea level lowering marking the top of the eocene we show that the fall of the base level of rivers due to this paleogeoid variation increased the resumption of erosion which had started under the influence of climatic and or tectonic evolution this leads us to reflect on 1 the significance of the complete oligocene detritic series in the sicilian channel and on all the borders of the western mediterranean basin and 2 the geodynamic evolution of the pantelleria rift during the oligocene thermal doming the cap bon peninsula and surrounding areas are favorable zones to analyse the eustatic fluctuations of the paleogeoid in the tethys during the cenozoic

time represented by coal seams in the coal measures of england abstract the relationship between interseam sediment thickness and features of coal seams such as seam splits and partings are examined with respect to possible controls of sedimentation during the upper carboniferous in the lancashire coalfield england the coal seams are characterised by lateral changes mostly seam splits which take place across more or less straight boundaries with a northeast southwest trend explained as due to contemporary movement on buried faults during the time of peat formation some of the seam splits develop and thicken to the northwest others to the southeast interseam sediments generally reveal a patchy development in terms of thickness distribution and show little evidence of synsedimentary tectonism the apparent restriction of fault control to coal formation is explained by relatively slow accumulation rates of peat and therefore maximum exposure to the possibility of contemporary movement on underlying faults interseam sediments on the other hand represent relatively short episodes of deposition and so involved minimum exposure to control by contemporary fault movement

geoarchaeological investigations at diepkloof rock shelter western cape south africa abstract the sedimentary sequence at diepkloof rock shelter formed through a complex interaction of depositional and post depositional processes and was variously influenced by biogenic geogenic and anthropogenic agents here we present the results of a micromorphological study of the sediments at diepkloof focusing in particular on the numerous anthropogenic inputs and modifications recorded within the sequence by applying the microfacies concept we were able to identify hearth burning and maintenance bedding construction and burning and surface modification by trampling as major processes that contributed to the formation of the site the human activities recorded within the sediments show a marked change throughout the sequence implying a shift in the use of the site over time the present study also provides a context for evaluating other classes of artifacts and data collected from the site

sedimentology of fraser river delta peat deposits a modern analogue for some deltaic coals abstract on the recent lobe of the fraser river delta peat accumulation has actively occurred on the distal lower dilta plain the transition between upper and lower delta plains and the alluvial plain distal lower delta plain peats developed from widespread salt and brackish marshes and were not influenced appreciably by fluvial activity lateral development of the marsh facies were controlled by compaction and eustatic sea level rise the resulting thin discontinuous peat network contains numerous silty clay partings and high concentrations of sulphur freshwater marsh facies formed but were later in part eroded and altered by transgressing marine waters the peats overlie a thin fluvial fining upward sequence which in turn overlies a thick coarsening upward prodelta delta front succession lower delta plain upper delta plain peats initially developed from interdistributary brackish marshes and were later fluvially influenced as the delta prograded the thickest peats occur in areas where distributary channels were abandoned earliest sphagnum biofacies replace sedge grass dominated communities except along active channel margins where the sedge grass facies is intercalated with overbank and splay deposits the peats are underlain by a relatively thin sequence of fluvial deposits which in turn is underlain by a major coarsening upward delta front and pro delta sequence alluvial plain peats accumulated in back swamp environments of the flood plain earliest sedge clay and gyttjae peats developed over thin fining upward fluvial cycles or are interlaminated with fine grained flood deposits thickest accumulations occur where peat fills small avulsed flood channels overlying sedge grass and sphagnum biofacies are horizontally stratified and commonly have sharp boundaries with fine grained flood sediments at active channel margins however sedge grass peats are intercalated with natural levee deposits consisting of silty clay these levees reduce both the number and size of crevasse splay deposits coal originating from peats of the different environments of the fraser delta would vary markedly in character peats of the lower delta plain will form thin lenticular coal seams with numerous splits and have a high ash and sulphur content peats from the lower to upper delta plain will be laterally extensive and of variable thickness and quality basal portions of the seams will contain numerous splits and have a high sulphur content whereas upper portions will be of higher quality peats from the upper delta plain alluvial plain will form thick isolated and laterally restricted coal seams characterized by low ash and sulphur contents

relationship between petrographic and chemical properties and coal seam geometry hance seam breathitt formation southeastern kentucky the upper hance coal seam in southeastern kentucy was used as a template to examine the spatial distribution of ash yield sulfur content and petrographic constituents relative to the geometry of the deposit geometric characteristics include thinning and splitting of the two main benches leaders and riders analytical data showed the thick non split portions of the coal body to be low in ash and sulfur as well as vitrinite content whereas the thinned and split margins were higher in ash sulfur and vitrinite content these relationships suggest that thick non split portions of the upper hance peat accumulated in areas isolated from detrital influx while thinner marginal peat was subject to intermittent flooding from adjacent channels marginal peat was derived from larger trees which flourished at the mire s edge in the presence of adequate nutrients whereas only stunted vegetation subsisting in the nutrient depleted center contributed to interior peat accumulation ponds formed on the sparsely vegetated mature surface of the bog s interior the petrographic and chemical character of the hance coal body is analogous to ombrogenous domed peats which characteristically contain higher concentrations of inorganics at the periphery of the deposit

subsurface geodynamics and petroleum geology of transform margin basins in the sahel of mahdia and el jem eastern tunisia 1 geophysical structural and seismic stratigraphic analysis of the mahdia sahel of tunisia based on seismic data and sedimentologic and microtectonic field measurements reveals a dynamic basin formation from the aptian to the quaternary seismic structural and isopach mapping of seismic horizons of cretaceous and cenozoic megasequences shows the partition of the mobile graben depocenter and carbonate and siliciclastic platform basins these basins are limited by synsedimentary restrictions along strike slip faults oriented east west and north south the interplay of these wrench faults in regional transtension and transpression during the cretaceous and cenozoic induced the synchroneous opening and closing of the graben and platform basins producing large accumulatio s of black shales and turbidites and reef oolite and carbonate platform deposits this was associated with the dragging rotation and blocking of dekakilometer size blocks assimilated to lithospheric microplates these movements were accompanied by volcanism and triassic salt intrusions along the bordering active faults in the east west trending and north south trending corridors in these basins sequential inversion of basin subsidence and the superposition of rhombic basins and wrench depocenters created migrating depocenters and provided the conditions in rapidly subsiding areas for source rock maturation and later hydrocarbon migration into stratigraphic and tectonic traps the tunisian sahel domain at the northern border of the african plate is characterized by tectonic mecha isms which provide a model for tectono sedimentary basin evolution in a wrench context

paleobotanical and paleoecological constraints on models of peat formation in the late carboniferous of euramerica abstract the dominant plants of the late carboniferous lowland tropics were taxonomically and structurally distinct from those of any later time periods dominance was distributed among lycopsids ferns sphenopsids pteridosperms and cordaites and each of these groups had distinctive and different ecological preferences and amplitudes peat forming habitats were dominated by lycopsids throughout the westphalian with a significant cordaitean element in the middle westphalian during the stephanian tree ferns were dominant following major extinctions near the westphalian stephanian transition each of the major plant groups had distinctive architectures and tissue composition trees contributed up to 95 of the peat biomass and tree forms of lycopsids psaronius and medullosa lack good modern analogues the cordaites were the only woody plant group to contribute significantly to peat and then only during the mid westphalian structurally wood like lycopsid bark is the major woody tissue encountered in most westphalian coals tree ferns and pteridosperms were largely parenchymatous in construction the stigmarian root systems of lycopsids also were largely parenchymatous the tissue structure of these dominant plant suggests the need for extreme caution in the inference of mire ecological conditions or vegetational structure from coal petrographic data peat formed under arborescent ferns or pteridosperms or peat repeatedly exposed to decay and rerooting by stigmarian root systems of lycopsids would have a distinctly non woody signature and yet would have formed in a forested environment a summary is presented of the autecology and synecology of mire plants emphazing the structural framework provided by lycopsids during the westphalian certain constraints in the links between peat biomass and miospore palynology are discussed in terms of over representation under representation and non representation the formulation of smith s four phase hydroseral model is discussed and compared with more recent data available from plant paleoecology the current debate over an ombrotrophic vs rheotrophic origin of late carboniferous peats relies in large part on paleobotanical data almost entirely palynological in combination with petrographic analyses ecological studies of miospores and of coal ball and compression macrofossils and the linkage of miospores to source plants permit the re evaluation of mire successional models evidence for tree lycopsids sphenopsids pteridosperms and cordaites suggests growth mainly in rheotrophic mires tree ferns are likely candidates for growth in domed mires although evidence is ambiguous and some tree ferns clearly grew under rheotrophic conditions densospores produced by at least sporangiostrobus lycopsid subtrees have been considered diagnostic of ombrotrophic conditions abundant evidence refutes this simplistic interpretation and suggests broad ecological amplitudes for densospore producers including growth under rheotrophic conditions although plant fossils alone can not resolve most of the major debates in modern coal geology paleobotany does contribute significantly to our understanding of ancient mires an approach combining paleobotanical data with petrography sedimentology and geochemistry on a case by case basis is most likely to produce a clear picture

analog modeling of pull apart basins scaled sandbox models have successfully simulated the geometries and progressive evolution of pull apart basins developed in a weak sedimentary cover above right stepping releasing dextral strike slip fault systems in rigid basement synkinematic basin infill was added progressively as the models were deformed vertical and horizontal sectioning of the completed models has allowed the full three dimensional architecture of the pull apart system to be analyzed we present three representative end member experiments 30 underlapping releasing sidestep 90 sharp nonoverlapping releasing sidestep and 150 overlapping releasing sidestep the pull apart basin geometries are typically sigmoidal to rhombic grabens the geometries of which are dependent upon the architecture of the underlying basement fault systems underlapping releasing sidestepping faults offset angles of 30 75 typically form elongate rhomboidal grabens 90 releasing offset sidesteps produce shorter squat rhomboid pull apart basins and overlapping releasing sidesteps 115 150 produce box like grabens with highly kinked basin sidewalls the pull apart basins are bounded by terraced oblique slip extensional sidewall fault systems that link the laterally offset principal displacement zones pdz of the main dextral strike slip faults the sidewall faults show changes in kinematics from dominantly dip slip extension in copyright 1997 the american association of petroleum geologists all rights reserved 1manuscript received june 24 1996 revised manuscript received november 20 1996 final acceptance june 10 1997 2fault dynamics project geology department royal holloway university of london egham surrey tw20 oex united kingdom supported by the fault dynamics project sponsored by arco british limited petrobras u k ltd bp exploration conoco u k limited mobil north sea limited and sun oil britain we also acknowledge additional funding from sun oil britain landsat thematic mapper data courtesy of rtz mining and exploration limited south american division jurrian reijs is thanked for field data relating to the salina del fraile pull apart basin chris elders is thanked for reviewing earlier versions of this manuscript and j crowell c morley and k biddle are thanked for constructive reviews of the manuscript the contents of this paper have been

coal facies in a cenozoic paralic lignite bed krabi basin southern thailand changing peat forming conditions related to relative sea level controlled watertable variations abstract the cenozoic krabi basin in the southern part of peninsular thailand contains about 112 million tons proven coal reserves at present coal is only produced from the bang mark mine located in the southern part of the basin where the main lignite bed is 7 20 m thick the lignite bed occurs in an overall paralic succession the present paper investigates the depositional conditions of an approximately 8 m thick lignite bed main seam in the bang mark mine using organic petrography including maceral ratios and geochemistry the results are further interpreted in a sequence stratigraphic context the lignite is of low rank and is completely dominated by huminite indicating generally oxygen deficient conditions in the precursor mire very low inertinite contents suggest rare occurrences of wildfires the lower part of the lignite bed represents a topogenous fresh water peat mire with open water areas that in few cases may have experienced influx of saline water the peat mire was subjected to periodic inundations and deposition of siliciclastics tissue preservation was relatively poor the upper part of the lignite bed represents a slightly domed fresh water ombrogenous peat mire with a stable watertable and a balance between peat accumulation and accommodation space creation that favoured preservation of plant tissues in general the mire vegetation changed from less woody in the topogenous mire to more arborescent in the ombrogenous mire where plants with suberinised wood cell walls also were more frequent decompacted the lignite bed corresponds to a minimum 11 m thick peat deposit that records from 22 000 to 55 000 years of peat accumulation watertable rise in the peat mire was controlled overall by relative sea level rise in a sequence stratigraphic context the lignite bed overlies a terrestrialisation surface tes sensu diessel 2007 and the lowermost part records peat formation during a falling watertable and a decreasing accommodation peat accumulation ratio terrestrialisation an accommodation reversal surface ars sensu diessel 2007 indicates a change to paludification style of peat formation characterised by rising watertable and a high accommodation peat accumulation ratio another ars marks a gradual change to a situation with a balanced accommodation peat accumulation ratio the overall watertable rise throughout peat formation but at a gradually slower rate from base to top suggests that the lignite bed could be located in the late transgressive systems tract tst

depositional response to foreland deformation in the carboniferous of eastern kentucky the appalachian basin is a typical foreland basin that has subsided episodically under the loads of successive thrust sheets the dynamics of basin subsidence and upwarping of basin margin arch systems reflects the flexural properties of the lithosphere quantitative models of the lithosphere depend on assumed rheological properties this study attempts to test these geodynamic models in a part of the appalachian basin mississippian deposition is correlated with waning acadian tectonism orogenic quiescence coincided with basin overdeepening and uplift of the cincinnati arch or forebulge although the foreland basin was mudstone dominated shoaling along the crest of the basin margin arch system resulted in reworking and wedges of unconformities in contrast the onset of alleghenian orogenesis during the pennsylvanian is reflected in a thick wedge of terrigenous clastic sediments the pennsylvanian basin fluctuated between underfilled restricted marine and overfilled nonmarine conditions rapid response of the basin to thrust sheet loading is inferred these characteristics of mississippian and pennsylvanian deposition support a viscoelastic model of the lithosphere

origin of large scale crossbeds in the late permian coal measures of the sydney and bowen basins eastern australia abstract theories proposed for the origin of large scale crossbeds may be generalised into two main categories the first suggests the large sigmoidal shape of the sediment layers results from variable differential compaction during and after deposition whereas the second infers that the high angle of the crossbeds is the result of primary depositional processes britten 1983 has proposed that large scale inclined strata may be produced according to his cide model whilst mallett 1983 has suggested that such structures are produced by channel automigration parbury 1976 and conaghan 1981 both proponents of the primary depositional model interpret the large scale inclined strata as foreset beds of a gilbert type delta prograding into deep 50 m water depth lakes within which floating islands produce allochthonous deposits from hydroponic vegetation marchioni 1976 1982 however envisages that the large scale inclined strata are epsilon crossbeds which have tilted during differential subsidence of peat swamps over which active channel systems have encroached nine kilometers of almost continuous high wall exposures have been studied in the moura kianga coal mine of the southeastern bowen basin and it is concluded that none of the above mentioned processes can explain the present configuration of sedimentary layering observed in these high walls at the moura kianga coal mine it is proposed that there the high angle large scale inclined strata have originated as primary features associated with a crevasse sub delta subsidence in excess of vegetation accumulation within the peat swamp provides the mechanism whereby a shallow lake developed and into which a crevasse sub delta was deposited similar processes have been described by coleman and prior 1980 from the mississippi delta

a late stephanian forest swamp with sporangiostrobus fossilized by volcanic ash fall in the puertollano basin central spain abstract about 600 m of coal measures and oil shales in the puertollano basin of castilla la mancha contain late stephanian floras an ash fall now a tuff band intercalated in the lower part of coal seam iii fossilized a swamp forest floor with abundant mature sporangiostrobus remains that are associated with vegetative bodeodendron the same lycophyte the pecopterid fern scolecopteris and the sphenophytes asterophyllites and annularia sphenophylloides the floral composition of this tuff band was analyzed and the various stages of the disarticulation process of sporangiostrobus were determined the fertile apices of these lycophyte trees fell onto the forest floor where flattening occurred as the result of decay of the wide cortical area and the central part of the siphonostele subsequently the long distal laminae of sporophylls were removed and afterwards the sporangia leaving only the short stubby horizontal proximal parts of the sporophylls attached to the hulk of these fertile apices of stems or major branches disarticulation was the means of dissemination of the sporangia of this heterosporous lycophyte that produced cristatisporites densosporites cingulizonates microspores and zonalesporites megaspores sporangiostrobus was an extremely prolific producer of densospores and there is a direct correlation between sporangiostrobus and the high densospore count and durite content of seam iii the stratigraphic succession associated with seam iii is described environmental conditions are discussed in relation to the numerous well over a thousand specimens large almost complete remains of sporangiostrobus found in the lower tuff band the detached fertile apices were lying on the forest floor when the volcanic ash fall took place and were preserved in situ where they were shed from the bodeodendron tree this implies an absence of water currents although the general environment must have been humid in view of the overall lacustrine setting it is noted that this is one of the rare examples in europe and north america palaeoequatorial belt where lycophytes continued to be the dominant peat forming element in late stephanian time the systematic position of sporangiostrobus is briefly discussed this lycophyte belonged to a conservative group that was widely distributed throughout the world its important role in latest carboniferous peat forming environments has not been realized until now because of the rarity of richly preserved sporangiostrobus remains

coal facies studies in the eastern united states coals in the eastern united states east of the mississippi river have been the subject of a number of coal facies studies going back to the 19th century such studies would not necessarily fall within a strict modern classification of coal facies studies but if a study encompassed some aspects of paleobotany palynology petrology geochemistry or sedimentology we assumed that some data and interpretations may be of use in evaluations of the facies references are presented as a guide for further research with annotation in the tables

botanical control on banding character in two new zealand coal beds abstract two new zealand coal beds were examined using a palaeobotanical approach to determine controls on banding characteristics the morley cretaceous coal is thickly 5 to 1 or 32 to 2 mm and well 25 banded whereas the brunner eocene coal is essentially non banded palynological analyses indicate that the morley was formed from a gymnosperm dominated vegetation with a secondary component of angiosperms in contrast the brunner was dominated by angiosperm vegetation with only a minor component of gymnosperms however it was found that any xylite vitrain bands 1 mm in either coal bed were comprised exclusively of secondary xylem of probable gymnosperm origin the presence of gymnosperm wood i e secondary xylem forming the larger bands in both coals can be related to the relative resistance of this material to chemical and physical decay as compared to all other plant tissues an absence of angiosperm wood in either the morley or brunner coal beds may be the result of the relative chemical degradability of angiosperm wood as compared to gymnosperm wood alternatively angiosperms in either of the two palaeo mires may have been shrubby and thus did not produce abundant woody tissue in either case the banded nature of the morley coal bed is the result of the presence of gymnosperm wood and the non banded nature of the brunner is the result of being dominated by a flora angiosperm which is easily degraded

cordaiteans in paleotropical wetlands an ecological re evaluation abstract cordaiteans in cordaite dominated permineralized peat from pennsylvanian coals in iowa have been reconstructed as mangroves using root anatomy peat taphonomy and geochemical data macrofloral palynofloral and conodont biostratigraphy indicate that these peats come from the latest atokan blackoak coal and earliest desmoinesian cliffland coal mid moscovian both in the kalo formation thus their depositional setting can be used to evaluate the mangrove hypothesis in recent mires thick mangrove peats have accumulated in tropical to subtropical carbonate systems in contrast thick tropical freshwater peats have accumulated in siliclastic systems kalo formation coals which we interpret as freshwater deposits formed in siliciclastic depositional settings similar to those of modern tropical freshwater peat and to other pennsylvanian coals in north america interpreted as freshwater deposits in the late atokan and earliest desmoinesian mid moscovian cordaiteans and tree ferns predominated in the western interior and illinois basins lycopsids and cordaiteans predominated in the appalachian and donets basins the scarcity of lycopsid only mires in north america during the late atokan earliest desmoinesian mid moscovian suggests drier climates than during the mid to late desmoinesian late moscovian rather than indicating mangrove swamps cordaite dominated peat may indicate climates with a low rain season although most plants in cordaite dominated peat probably grew in freshwater coastal mires in climate zones with seasons of low rain may harbor mangrove taxa the changuinola swamp of panama a modern peat accumulating wetland that has a low rain season is a possible analog of ancient cordaite dominated mires in changuinola most plants require freshwater however mangroves sustained by salt water influx into the swamp grow along the seaward edge and along blackwater creeks the low rain season hypothesis has implications for understanding rainfall amount and continuity during pennsylvanian cyclothem deposition the floral succession in diverse cordaite coals from cordaiteans to tree ferns to lycopsids suggests increasingly wet climate during coal accumulation the position of these coals immediately above the sequence boundary suggests humid climate during early glacial melting for these cyclothems

the effects of clastic sedimentation on organic facies development within a tertiary subbituminous coal bed powder river basin montana u s a abstract the anderson dietz coal is a 25 m thick bed that splits eastward into three benches the anderson dietz 1 and dietz 2 each separated from the other by as much as 45 m of detrital sedimentary rocks petrographic and chemical analyses of the anderson and dietz 1 coal benches suggest that detrital sediments now lithified between the benches were introduced after the peat surface had subsided as a result of either fire or differential compaction of underlying sediments sediments associated with this event had a limited effect upon the quality of the anderson and dietz 1 coal benches ash yields and sulfur contents are elevated only at the very top and bottom of the benches in areas where the benches are not split sulfur content and maceral types indicating degradation increase only in a thin zone 1 m thick that is laterally equivalent to the split sediments however ash yields in this interval increase only slightly 2 5 this indicates that while little sedimentation occurred the peat which formed the coal was inundated by higher ph surface and ground water causing the degradation of plant material

petrographic characteristics of the wyodak anderson coal bed paleocene powder river basin wyoming u s a abstract six lithofacies of the thick 30 m wyodak anderson subbituminous coal bed of the fort union formation paleocene powder river basin wyoming can be delimited using megascopic and petrographic data previous lithofacies analysis of the rock types associated with the wyodak anderson bed suggested that raised peat accumulated in restricted parts of an inland flood plain the peat bodies were separated by deposits of contemporaneous possibly anastomosed channels in this study megascopic descriptions from four mine highwalls of the wyodak anderson coal bed were found to be similar to facies defined by microscopic data from core and highwall samples the data indicate that the upper and lower parts of the coal bed are rich in preserved wood remains for instance humotelinite whereas the middle part of the bed contains comparatively larger amounts of material that resulted from degradation and comminution of the peat e g eugelinite the facies are interpreted to be the result of different chemical and biological environments at the time of peat formation

technological successions in the middle stone age sequence of diepkloof rock shelter western cape south africa the southern african msa comprises a series of phases of unique technological innovations that fuel current models on the evolutionary processes of anatomically modern humans however the nature and variability of these technological phases remain poorly documented this study reports on the previously unpublished sequence of diepkloof rock shelter south africa and investigates the main technological changes therein particularly emphasizing the emergence succession and disappearance of the still bay sb and the howiesons poort hp we argue for technological change that occurred at different rates and under the influence of variable driving factors our model implies that the sb and the hp are not related to the influx of new populations but have regionally specific origins unlike the other techno complexes the hp at diepkloof is subdivided into different phases early intermediate and late but only the upper phases resemble the so called classic hp finally the technological sequence of diepkloof questions the homogeneous picture which has been so far assumed for the southern african msa and places emphasis on the importance of exploring long regional sequences

the conundrum of coal bed thickness a theory for stacked mire sequences maximum thicknesses for modern peats have been documented only up to about 20 m whereas coal beds can often be as much as 90 m thick since peat is expected to compact appreciably during burial there appears to be no modern analogue for the processes which formed thick coal beds and this seems to challenge the law of uniformitarianism however the conundrum of coal bed thickness can be resolved by identification of discontinuities in coal beds coal beds are generally treated as single entities created by a continuous process of peat deposition it is more likely however that most thick coal beds are composed of multiple paleo peat bodies stacked one upon another rather than a single paleo peat body it is suggested that there are three types of bounding surfaces seen in modern peat bodies that can be used to distinguish individual paleo peats in coal beds these bounding surfaces can be recognized both in the field and microscopically each of these surfaces represents cessation or at least ext

maceral and palynomorph facies from two tertiary peat forming environments in the powder river basin u s a abstract the differences between the depositional settings of the smith and anderson subbituminous coal beds paleocene central powder river basin u s a are interpreted on the basis of their petrographic composition and palynologic assemblages the smith coal bed is relatively thin m and has a high degree of thickness variation 0 5 m over short distances km the result of deposition in an anastomosed fluvial environment where numerous lakes and small channels limited the extent of peat deposits although plants related to the living genus glyptostrobus dominated the swamp peat forming plant communities contained mixes of ancestral species of platanus and ulmus as well as vegetation of lower stature such as spagnum some intervals within the coal bed contain anomalously high concentrations of cell walls humotelinite and cell fillings corpohuminite some of which came from locally abundant decay resistant pinaceae or pinaceous vegetation raised areas of the peat swamp characterized by sphagnum were also favorable for the accumulation of carbonized plant components inertinites because the peat of the anderson coal bed formed on top of thick 50 m sandstone bodies of an abandoned meander belt complex the coal bed is generally thicker 7 m and more widespread 15 km in extent than the smith coal bed the sands provided a relatively stable poorly compactable platform that was favorable to the growth of large arborescent vegetation such as the dominant ancestral glyptostrobus as well as ancestral nyssa carya and betulaceae in a well drained but moist swamp environment the stability of the peat forming environment resulted in a raised peat deposit of relatively uniform paleoflora and peat composition in the thicker areas of the anderson coal bed the upward increase in carbonized plant components indicates a progressively drier or better drained swamp environment intervals within the coal bed that overlie or are lateral to crevasse splay deposits contain a high concentration of pollen attributable to pterocarya and an absence of carbonized plant remains an indication that ancestral pterocarya preferred a water saturated environment close to the edge of the swamp where detrial influx occurred

the influence of depositional environments on coal petrographic composition of the lower kittaning seam western pennsylvania abstract lateral variations in maceral composition of the lower kittanning seam can be explained in terms of differential preservation of plant materials which is influenced by the ph eh of water within the peat swamp and by the rate of subsidence within the central part of the basin high telocollinite contents are observed this type of vitrinite represents large well preserved pieces of woody tissue whose preservation was favored by rapid burial towards the margins of the basin high desmocollinite contents are seen slower burial combined with the influx of neutral oxygenated fresh water permitted decomposition of the precursor materials producing this highly degraded type of vitrinite vertical variations in telocollinite and desmocollinite content can also be related to burial rates and ph eh conditions within the swamp throughout the basin high telocollinate contents observed in the lower part of the seam resulted from rapid burial under relatively low ph conditions continued high rates of subsidence led to an influx of neutral ph oxidizing waters associated with the encroaching marine environment under these new conditions more degradation of plant tissues occurred producing the high desmocollinite contents observed in the upper part of the seam this effect was most pronounced in the center of the basin an alternative explanation would be a change in vegetation type in response to the changing conditions the high desmocollinite content would then reflect a shift to a community dominated by smaller possibly herbaceous plants in addition to a change in vitrinite type towards the top of the seam a decrease in total vitrinite content and increases in total liptinite and inertinite contents are observed the increase in liptinite content is due to either 1 the higher resistance to decomposition of liptinite precursor materials when compared to vitrinite precursors in the more neutral conditions or 2 a change from a dominantly arborescent vegetation to a more herbaceous one the increase in inertinite results from an increase in transported material inertodetrinite and or an increase in the formation of inertinite macerals such as degrado fusinite possibly in response to the encroaching marine conditions an additional control on maceral composition is the level of metamorphism of the coal total liptinite content decreases towards the southeast in this area the coal has attained a sufficiently high rank that the reflectance of liptinite macerals approaches that of vitrinite thus making their identification difficult

osl and tl dating of the middle stone age sequence at diepkloof rock shelter south africa a clarification diepkloof rock shelter offers an exceptional opportunity to study the onset and evolution of both still bay sb and howiesons poort hp techno complexes however previous age estimates based on luminescence dating of burnt quartzites tribolo et al 2009 and of sediments jacobs et al 2008 were not in agreement here we present new luminescence ages for 17 rock samples equivalent dose estimated with a sar itl protocol instead of classical maad tl as well as for 5 sediment samples equivalent dose estimated with sar single grain osl protocol and an update of the 22 previous age estimates for burnt lithics modified calibration and beta dose estimates while a good agreement between the rock and sediment ages is obtained these estimates are still significantly older than those reported by jacobs et al 2008 after our own analyses of the sediment from diepkloof it is suspected that these authors did not correctly chose the parameters for the equivalent dose determination leading to an underestimate of the equivalent doses and thus of the ages from bottom to top the mean ages are 100 10 ka for stratigraphic unit su noel and 107 11 ka for su mark uncharacterized lower msa 100 10 ka for su lynn leo pre sb type lynn 109 10 ka for sus kim larry sb 105 10 ka for sus kerry kate and 109 10 ka for su jess early hp 89 8 ka for su jude msa type jack 77 8 ka for su john 85 9 ka for su fox 83 8 ka for su fred and 65 8 ka for su ob5 intermediate hp 52 5 ka for sus ob2 4 late hp this chronology together with the technological analyses greatly modifies the current chrono cultural model regarding the sb and the hp and has important archaeological implications indeed sb and hp no longer appear as short lived techno complexes with synchronous appearances for each and restricted to oxygen isotopic stage ois 4 across south africa as suggested by jacobs et al 2008 2012 rather the sequence of diepkloof supports a long chronology model with an early appearance of both sb and hp in the first half of ois 5 and a long duration of the hp into ois 3 these new dates imply that different technological traditions coexisted during ois 5 and 4 in southern africa and that sb and hp can no longer be considered as horizon markers

petrographic analysis of the rosebud seam at the absaloka big sky and rosebud mines powder river basin montana abstract analysis of maceral and mineral content and huminite reflectance for the rosebud coal at the absaloka big sky and rosebud mines provides information on the variation of coal composition and rank probably caused by variation in depositional environments and coalification humanite reflectance indicates that rank is gradational from lignite at the absaloka and rosebud mines to subbituminous c at the big sky mine amounts of minerals and huminite inertinite and liptinite group macerals vary vertically at absaloka and big sky defining lithologic layers and suggesting changes in type and style of peat accumulation direct correlation of huminite reflectance with huminite abundance and inverse correlation with inertinite abundance suggests a possible relationship with coalification depositional environment and or original floral characters depositional environment is initially interpreted as a swamp with mixed vegetation or a swamp alternating from arboreal to herbaceous vegetation

multiple bench architecture and interpretations of original mire phases examples from the middle pennsylvanian of the central appalachian basin usa abstract coal seams often exhibit lateral and vertical variability in composition when sampled as a whole seam this variability is masked but if a seam is subdivided into correlateable components this variability can be tested and better understood herein an architectural approach is used to divide seams into intra seam components clastic splits and mineral partings as well as persistent fusain and durain layers can be used as intra seam bounding units to subdivide a seam into subdivisions called benches regional examination of lower and middle pennsylvanian age coal seams shows that many contain laterally persistent bounding surfaces that can be used to define multiple benches of coal within each seam inter bench analyses from some of the most extensively mined seams in the central appalachian basin show that individual benches often have different spatial and quality trends hence some component of whole seam variability is a function of changes in the relative contribution of these different benches to the seam as a whole many coal benches also exhibit intra bench variation in coal parameters intra bench variation can be analyzed in terms of parameters such as sulfur content and ash yield in order to address changes in coal quality for regional resource evaluation intra bench variation can also be analyzed in terms of a combination of palynologic petrographic and geochemical parameters termed compositional groups in order to better understand the development of the original mire systems compositional groups are defined by ranges of multiple criteria which are inferred to owe their origin to the mire type in which they formed vertical changes in compositional groups within coal benches can be used to infer paleo edaphic conditions during peat accumulation if seam thickness is a product of bench configuration and trends in compositional groups occur in benches then trends in quality can be marginally predicted based upon seam thickness and inferred bench architecture additionally changes in inter bench and intra bench thickness and compositional profiles can be used to infer original depositional controls such as paleotopography syndepositional structural movement and syndepositional clastic influx for more accurate reserve estimates

investigation of organic matter and biomarkers from diepkloof rock shelter south africa insights into middle stone age site usage and palaeoclimate the file associated with this record is under embargo until 36 months after publication in accordance with the publisher s self archiving policy the full text may be available through the publisher links provided above

palaeoenvironmental reconstruction of kathu pan south africa based on sedimentological data abstract several studies have highlighted the importance of collecting well dated records of palaeoenvironmental changes on desert margins particularly in the semi arid interior of southern africa here we describe sediments at three sites in kathu pan a pan complex overlying karstic bedrock at the southern edge of the kalahari basin sinkholes have exposed sedimentary sequences dating back to the pleistocene making it possible to document multiple palaeoenvironmental regimes in this landscape using a multi analytical sedimentological approach including micromorphology energy dispersive x ray spectrometry electron microprobe loss on ignition laser diffractometry and luminescence dating we demonstrate that the sediments at kathu pan represent an environment fluctuating among a number of thresholds for accumulation of different kinds of transported and authigenic sediments within the pleistocene sands at the base of our studied sedimentary sequence the presence of palygorskite indicative of less extreme evaporative control represents a semi arid environment from 156 11 ka to 32 2 ka marine isotope stages 6 3 increased moisture availability at 84 4 ka and at 96 5 ka possibly during marine isotope stages 5a and 5c respectively is reflected in the sands by the formation of palygorskite in concert with the deposition and oxidation of organic material as the climate became increasingly arid possibly in response to global cooling during the last glacial maximum 21 2 ka kathu pan crossed a threshold and deposition of caco3 dominated over that of palygorskite in the holocene beds within our studied unit alternating caco3 and organic dominated deposits sometimes in very fine laminae reflect an increase in the amplitude of either seasonal or annual changes in water availability

new radiometric ages for the fauresmith industry from kathu pan southern africa implications for the earlier to middle stone age transition abstract the fauresmith lithic industry of south africa has been described as transitional between the earlier and middle stone age however radiometric ages for this industry are inadequate here we present a minimum osl age of 464 47 kyr and a combined u series esr age of 542 107 140 kyr for an in situ fauresmith assemblage and three osl ages for overlying middle and later stone age strata from the site of kathu pan 1 northern cape province south africa these ages are discussed in relation to the available lithostratigraphy faunal and lithic assemblages from this site the results indicate that the kathu pan 1 fauresmith assemblage predates transitional industries from other parts of africa e g sangoan as well as the end of the acheulean in southern africa the presence of blades in the dated fauresmith assemblages from kathu pan 1 generally considered a feature of modern human behaviour mcbrearty and brooks 2000 the revolution that wasn t a new interpretation of the origin of modern human behavior j human evolution 39 453 563 provides evidence supporting the position that blade production in southern africa predated the middle stone age and the advent of modern homo sapiens

an improved osl chronology for the still bay layers at blombos cave south africa further tests of single grain dating procedures and a re evaluation of the timing of the still bay industry across southern africa this paper presents a series of new single grain optically stimulated luminescence osl ages for the still bay at blombos cave south africa and compares them to previously published osl thermoluminescence tl and electron spin resonance esr ages for this site details are provided about the measurement and analytical procedures including a discussion of the characteristics of the osl signals of individual quartz grains this forms the basis for further investigations into the sensitivity of the equivalent dose de estimates to a range of different analytical approaches including changes in the size of the test dose the choice of signal integration interval the subtraction of an appropriate background and isolation of the most light sensitive fast component of quartz osl we also report the results of an inter operator test of de determination using seven new samples from blombos cave and demonstrate the reproducibility of results obtained for two samples that had been dated previously at another laboratory and were measured and analysed again in this study together these tests validate the robustness of the blombos cave single grain osl age estimates to a variety of alternative osl dating procedures we have incorporated for the first time these ages for blombos cave into a data set of all single grain osl ages for still bay and howieson s poort sites across southern africa and have used a statistical model to re evaluate the timing and duration of the still bay industry we calculate the most plausible start and end dates of the still bay as 72 2 ka and 71 3 ka respectively amounting to a duration of 0 9 ka and estimate with conventional 95 confidence that this industry began no earlier than 75 5 ka ended no later than 67 8 ka and lasted no longer than 6 6 ka

paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks climate is a primary control on sediment flux from continental sources into sedimentary systems in warm climates siliciclastic input is greatest under highly seasonal rainfall nonseasonal conditions favor formation of end member chemical rocks perennially wet climates are conducive to coal formation whereas dry climates produce carbonates and or evaporites stratigraphic repetition of siliciclastic and chemical rocks therefore appears to be related to paleoclimate cycles as well as to transgressive regressive events and tectonics

blade production 500 thousand years ago at kathu pan 1 south africa support for a multiple origins hypothesis for early middle pleistocene blade technologies abstract the 500 thousand year old stratum 4a lithic assemblage from kathu pan 1 northern cape south africa is one of the earliest occurrences of blade technology and is the oldest dated assemblage attributed to the fauresmith industry a technological analysis of the kathu pan 1 stratum 4a assemblage reveals that blades were systematically removed using direct hard hammer percussion from organized blade cores that were extensively prepared via centripetal flaking some of these blades were retouched into points comparisons with published descriptions of the roughly contemporary blade assemblages from the kapthurin formation kenya and qesem cave israel demonstrate that diverse blade production strategies were employed during the earlier half of the middle pleistocene the diversity best supports a scenario in which laminar technology was invented in multiple places and times

a transition from carbonate shelf to pelagic basin environments of deposition rifting and depositional systems in the jurassic of northeastern tunisia jurassic deposition in the maghrebian tethys was governed by eustasy and rifting two periods were delineated 1 a carbonate shelf rhaetian early pliensbachian and 2 a platform basin complex early pliensbachian callovian the carbonate shelf evolved in four stages generating three sedimentary sequences j1 to j3 separated by boundary sea level falls drawdown exposure and local erosion sediment facies bear evidence of sea level rises and falls lateral changes in lithofacies indicate shoaling and deepening upward during the sinemurian a major pulse of rifting with an abrupt transition from carbonate shelf to pelagic basin environments of deposition marks the upper boundary of the lower pliensbachian carbonate shelf deposits this rifting episode with brittle fractures broke up the rhaetian early pliensbachian carbonate shelf and has created a network of grabens half grabens horsts and stacked ramps following this episode a relative sea level rise led to pelagic sedimentation in the rift basins with local anoxic environments that also received debris shed from uplifted ramp crests another major episode spanning the whole early pliensbachian bajocian is suggested by early brecciation mass flows slumps olistolites erosion pinch outs and sedimentary prisms a later increase in the rates of drifting marked a progress toward rift cessation during the late jurassic these jurassic carbonates with detrital deposits and black shales as the source rocks in northeastern tunisia may define interesting petroleum plays pinch out flanking ramps onlaps and structurally upraised blocks sealed inside grabens source rock maturation and hydrocarbon migration began early in the cretaceous and reached a maximum during the late tortonian pliocene atlassic orogeny