the fluid dynamics of a basaltic magma chamber replenished by influx of hot dense ultrabasic magma this paper describes a fluid dynamical investigation of the influx of hot dense ultrabasic magma into a reservoir containing lighter fractionated basaltic magma this situation is compared with that which develops when hot salty water is introduced under cold fresh water theoretical and empirical models for salt water systems are adapted to develop a model for magmatic systems a feature of the model is that the ultrabasic melt does not immediately mix with the basalt but spreads out over the floor of the chamber forming an independent layer a non turbulent interface forms between this layer and the overlying magma layer across which heat and mass are transferred by the process of molecular diffusion both layers convect vigorously as heat is transferred to the upper layer at a rate which greatly exceeds the heat lost to the surrounding country rock the convection continues until the two layers have almost the same temperature the compositions of the layers remain distinct due to the low diffusivity of mass compared to heat the temperatures of the layers as functions of time and their cooling rate depend on their viscosities their thermal properties the density difference between the layers and their thicknesses for a layer of ultrabasic melt 18 mgo a few tens of metres thick at the base of a basaltic 10 mgo magma chamber a few kilometres thick the temperature of the layers will become nearly identical over a period of between a few months and a few years during this time the turbulent convective velocities in the ultrabasic layer are far larger than the settling velocity of olivines which crystallise within the layer during cooling olivines only settle after the two layers have nearly reached thermal equilibrium at this stage residual basaltic melt segregates as the olivines sediment in the lower layer depending on its density the released basalt can either mix convectively with the overlying basalt layer or can continue as a separate layer the model provides an explanation for large scale cyclic layering in basic and ultrabasic intrusions the model also suggests reasons for the restriction of erupted basaltic liquids to compositions with mgo 10 and the formation of some quench textures in layered igneous rocks

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

shallow seismic reflection study of a glaciated valley shallow seismic reflection data were recorded along two long 1 6 km intersecting profiles in the glaciated suhre valley of northern switzerland appropriate choice of source and receiver parameters resulted in a high fold 36 48 data set with common midpoints every 1 25 m as for many shallow seismic reflection data sets upper portions of the shot gathers were contaminated with high amplitude source generated noise e g direct refracted guided surface and airwaves spectral balancing was effective in significantly increasing the strength of the reflected signals relative to the source generated noise and application of carefully selected top mutes ensured guided phases were not misprocessed and misinterpreted as reflections resultant processed sections were characterized by distributions of distinct seismic reflection patterns or facies that were bounded by quasi continuous reflection zones the uppermost reflection zone at 20 to 50 ms 15 to 40 m depth originated from a boundary between

results of 2 and 3 d high resolution seismic reflection surveying of surficial sediments to investigate the potential of seismic reflection methods for studying surficial sediments 2 and 3 d high resolution surveys have been conducted across a plot of land adjacent to a landfill in northern switzerland results of the reflection profiling demonstrated that closely spaced common reflection points 2 5 m and high fold 12 data were prerequisites for producing clear images at this site for the 3 d survey an area of 115 160 m was covered with common reflection points every 2 5 2 5 m three dimensional migration of the resultant 18 to 70 fold data proved to be a critical step in correctly locating out of plane reflections and collapsing diffractions that were prominent features in the 2 d profile data within the 3 d data volume a conspicuous reflective zone and a marked decrease in reflection amplitudes at 200 m depth delineates the bedrock surface immediately above this level are continuous reflections from flat lying lacustrine sediments these are in turn overlain by regions of strong reflected energy interpreted as either large erratic blocks anomalous compaction zones or gravel channels lenses

effects of near surface waveguides on shallow high resolution seismic refraction and reflection data waveguides formed between the earth s free surface and sharp subsurface velocity discontinuities such as the watertable may have a significant impact on high resolution seismic refraction and reflection data energy trapped in such waveguides may propagate over long distances with little loss due to geometrical spreading the dispersive nature of the guided waves results in pronounced shingling of the first arrivals this narrows the optimum reflection window between the first arrivals and the ground roll and may lead to mispicking of first breaks and difficulties in identifying and processing shallow reflections

a double magmatic heat pump at the core mantle boundary gigantic silicate magma chambers have been postulated to account for seismically inferred ultra low velocity zones at the base of the mantle acting to modulate heat transport out of the core and into plumes in the core rising plumes of liquid metal and light elements pump the latent heat outward from the inner core boundary by compositional convection the outer core thus pumps heat to the core mantle boundary cmb and the giant magma chamber pumps heat into the mantle to act as a plume source magmatic action at the cmb depends critically on the balance between melt composition compressibility and temperature a stably resident magma above the cmb must be denser than the mantle crystals mostly silicate perovskite pv and magnesiowustite mw dense melts should form at the cmb where they must be saturated with fe and feo from the core given normal mg fe partitioning mw will be denser than pv and melts from pv mw iron liq should also be intrinsically dense relative to the bulk crystal assemblage such melts may become superheated to overcome the compositional density and rise upward in the magma chamber assisted by turbulent mixing cooled melt sheds dense metal and metal oxide crystals and growth of these crystals releases light solute that quickly transports heat upward toward the chamber roof where it melts the mantle near the roof dense melt grows from the heat transported upward by compositional convection and sinks excess heat and occasionally some melt escapes to feed plumes in the mantle cmb magmas must be among the most fe rich in the earth

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

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

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

pleistocene stratigraphy of the saskatoon area saskatchewan canada an update pleistocene deposits in the saskatoon area are divided into the sutherland and saskatoon groups the sutherland group is divided into the mennon dundurn and warman formations and the saskatoon group is divided into the floral and battleford formations the floral formation is subdivided into the lower till the riddell member and the upper till each formation is composed of a sequence of deposits including basal proglacial sediment till upper proglacial sediment and nonglacial sediment each formation is defined primarily on the basis of carbonate content and stratigraphic position of its till and commonly it is bounded by weathered zones and or nonglacial sediments the sutherland group is pre illinoian in age and the lower till of the floral formation is illinoian in age the riddell member between the lower and upper tills of the floral formation is late rancholabrean probably sangamon in age radiocarbon ages of sediments lying between the upper till of the floral formation early wis

imaging a shallow aquifer in temperate glacial sediments using seismic reflection profiling with dmo processing we acquired a seismic reflection profile to image a shallow 100 m aquifer system on a small island in puget sound north of seattle washington the aquifer system is comprised of temperate glacial sedimentary strata with the primary aquifer lying approximately 45 m below the surface we chose the site because there are water well boring descriptions available and a sea cliff parallels the profile location providing stratigraphic control a 20 lb 9 kg weight drop was used as an energy source to acquire a 30 fold common midpoint cmp reflection profile along a 400 m line analysis of the recorded wavefield was not straightforward because of complex stratigraphy and the presence of a laterally variable thin bed 5 15 m of high impedance lodgement till within a few meters of the surface we used finite difference modeling to determine that conventional cmp processing would provide a reasonable approximation for imaging strata in the primary target zone roughly 20 m below the high velocity till fo

shallow seismic reflection mapping of the overburden bedrock interface with the engineering seismograph some simple techniques where unconsolidated overburden exceeds 20 m in thickness the reflection method may be efficiently used with a 12 channel engineering seismograph to map topography on the overburden bedrock interface as well as possible structure within the overburden the two techniques we suggest are the simplest forms of reflection profiling which can be applied with a minimum amount of equipment which we suggest is a 12 channel enhancement seismograph a 12 geophone array and a hammer source these techniques require good transmission characteristics of the overburden as well as a sharp velocity discontinuity at the overburden bedrock interface for data processing and display a microcomputer is essential

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

high resolution seismic and resistivity profiling of a buried quaternary subglacial valley northern alberta canada high resolution seismic and resistivity profiles were acquired to assist in the delineation of a buried quaternary subglacial valley the existence of which was first discovered by drilling one aspect of this valley is the glacial sediments that host substantial methane at shallow depths 50 m or less geophysical well logs indicate that the glacial sediments in this area generally have lower compressional wave speeds v p 10 m than adjacent undisturbed cretaceous age rocks which have v p 2200 m s and r 300 m valley the reflection profile reveals a complex series of events consistent with heterogeneous deposition one major reflection dips eastward across the valley the reflection character changes abruptly on either side of this event with dipping clinoform reflections beneath and nearly horizontal reflections above these may be related to changes in deposition processes beneath a retreating ice sheet as has been suggested by earlier workers the buried valley s basal reflections are complex and possibly reflect glaciotectonic deformation or block plucking the near surface methane gas is within but at the edge of the valley the methane gas saturated zone displays anomalously high resistivities both in the well logs and in resistivity tomography

high resolution images of shallow aquifers a challenge in near surface seismology a near surface multifold high resolution seismic reflection experiment was conducted in the vicinity of the waste management area of a potash mine in western canada a buried channel was identified in the data and the stratigraphy of the quaternary infill of this structure was mapped the spatial extent of several prominent gravel sandy aquifers which represent the hydrogeologic framework of the region was outlined by the survey the seismic signatures also established the hydraulic independence of three major aquifers along the survey line the complex heterogeneous lithology of the surface cover limited effective elastic wave generation to surface sources this geologic framework also caused propagation of strong diverse coherent noise patterns which severely degraded reflected signal the suppression of those overhelming interfering events required the design of noise specific filters and their sequential multistep implementations results of forward modeling of background geologic information were c

seismic reflection investigations of sinkholes beneath interstate highway 70 in kansas seismic reflection studies were performed across actively developing sinkholes located astride interstate highway 70 in russell county kansas results indicate that high resolution seismic reflection surveys are useful in the subsurface investigation of some sinkholes in particular we were able to delineate the subsurface vertical and horizontal extent of the sinkholes because of the excellent acoustical marker bed characteristics of the stone corral anhydrite the seismic reflection evidence presented here combined with borehole information from 1967 suggest that the stone corral anhydrite has been down dropped within one of the sinkholes as much as 30 m in 13 years the seismic reflection method is potentially useful in engineering studies of other sinkholes and karst features the seismic data presented here were obtained in the presence of relatively heavy highway traffic i e up to a few dozen vehicles per minute using the minisosie recording technique

vertical resolution of a seismic survey in stratigraphic sequences less than 100 m deep in southeastern kansas a 400 m long 12 fold high resolution common depth point cdp reflection seismic profile was acquired across shallow converging pennsylvanian strata in the independence area of southeastern kansas one of the principal objectives was to determine practical vertical resolution limits in an excellent shallow seismic data area with borehole control the dominant frequency of the cdp stacked data is in excess of 150 hz based on peak to peak measurements interference phenomena observed on stacked seismic data incorporated with models derived from log and drill hole information suggest a practical vertical resolution limit of about 7 m or one third of the dominant wavelength this practical resolution is slightly less than the predicted theoretical resolution limit of 5 m based on the generally accepted one quarter wavelength axiom these data suggest conventional rules of thumb describing resolution potential are not accurate when reflectors on shallow narrow bandwidth data converge rapidly across horizo

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

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

no mushy zones in the earth s core abstract mushy zones assemblages of crystals and their pore space liquids have been invoked for both the upper and lower boundaries of the liquid outer core the timescale of very slow accumulation compared with solidification at either of these interfaces militates against such zones where instead hard ground should be expected to form by solidification at the interface such adcumulus growth involves isothermal isocompositional solidification by successful exchange of evolving solute with fresh melt from an infinite reservoir at both boundaries of the outer core the removal of rejected material is significantly aided by compositional convection the accumulation rates at the outer core boundaries are orders of magnitude slower than required for adcumulus growth as calibrated both by field and experimental evidence in silicate melts a conceptual phase diagram for the core mantle boundary helps to visualize the relevant equilibria capture of core metal into the mantle has been suggested to occur via a mushy zone to explain a high electrical conductivity there as plausibly required by the secular behavior of the earth s nutation one conjecture is that the rejected light elements from the freezing of the inner core might be able to congregate as a porous flotation sediment at the top of the core the idea of porosity in such a mushy zone must be rejected from experience with solidification of cumulates from magmas a high electrical conductivity might instead be caused by solution of core metal by mantle followed by exsolution the hottest part of the mantle lies in contact with the molten outer core where the maximum solubility of fe must occur in the major mantle phases on leaving the core mantle boundary the mantle must cool and may exsolve metal on the metal silicate solvus if the iron rich metal resides chiefly in the rheologically weaker metal oxide phase which coats the deforming perovskite grains it may furnish a short circuit for mantle conductivity in the basal mantle at still cooler and higher levels the mantle encounters more normal mantle redox conditions and any exsolved fe metal should oxidize to feo in the metal oxide and perovskite phases ceasing to be a conductor

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

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

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

adcumulus growth of anorthosite at the base of the lunar crust unzoned plagioclase crystals imply isothermal adcumulus solidification and cannot result from reactive equilibrium crystallization in dry magma extraction of latent heat upward through lunar crust results only in chilled or cotectic mesocumulate rocks not anorthosite or adcumulates adcumulus growth of anorthosite requires exchange of refractory for incompatible components between the site of crystal growth and nearby fresh magma and the extraction of calories from growing crystals to the flowing supercooled magma supercooling can be acquired at remote sites like upwellings and then be carried by convective flow beneath crust which is accreting plagioclase by flotation or in situ nucleation and growth if transport distances are larger than the scale of rockbergs cotectic norites and troctolites may result impact induced upwellings tend to promote growth of buoyant rather than mafic crust hence impacts are not solely destructive

a magmatic heat pump the structures of igneous cumulates can provide valuable clues to inaccessible magmatic processes many mafic layers in the rhum intrusion have finger structures 1 3 that protrude into the overlying felsic rocks these structures are attributable to melting of the overlying olivine feldspar rocks by hot mafic magma emplaced as sills4 the bases of mafic layers contain smooth bottomed olivine cumulates here i show that the heat needed to melt the roof of the layer is carried by rapidly rising light solute released by growth of basal olivine crystals that were deposited by two phase convection compositional convection therefore drives a heat pump transfering heat of fusion from remote growing crystals to those that are melting this action contrasts with cooling under a refractory roof which is conduction limited the heat pumping principle shows why ultramafic magmas may melt their roofs whereas felsic magmas tend to form upper border zones

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

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

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

field comparison of shallow p wave seismic sources near houston texas a shallow p wave seismic source comparison was conducted at a site near houston texas where the depth to the water table was approximately 7 m and near surface materials consisted of clays sands and gravels data from twelve different sources during this november 1991 comparison are displayed and analyzed reflection events are interpretable at about 40 ms on some 220 hz analog low cut filtered field files and at 60 ms on most 110 and 220 hz analog low cut filtered field files calculations and local water well information suggest the 40 ms event is from the top of the water table subsurface explosive sources seem to possess the highest dominant frequency broadest bandwidth and recorded amplitudes and therefore have the greatest resolution potential at this site our previous work and that of our colleagues suggests that given a specific set of site characteristics any source could dominate the comparison categories addressed here

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

integrated geophysical geochemical and hydrogeological investigation of shallow groundwater resources in parts of the ikom mamfe embayment and the adjoining areas in cross river state nigeria information generated from geophysical geochemical and hydrogeological data has been used in assessing the groundwater resource potential quality and usability and in mapping flow directions within the shallow subsurface of the mamfe embayment cross river state nigeria the electrical resistivity technique in which the schlumberger s vertical electrical sounding field procedure has been adopted was the geophysical method employed lithology logs from drilling records discharge rates static water level information were the hydrogeological information utilized while the geochemical techniques involve analyses of water samples apparent resistances were measured using different resistivity meters including oyo mcohm model 2115 abem terrameter sas300b and sas1000 models and igis ssp ats mrp model with maximum current electrode separation reaching 1 km in some communities geological information was used as control in the modelling and interpretation of all geophysical data the physico chemical parameters of the water samples from the different water sources in the area were determined using different analytical techniques and in some cases by in situ direct measurement of some parameters measured values of electrical conductivity static water level available aquifer discharge information and calculated sar and na were integrated into the geophysical and hydrogeological results the shallow subsurface of the area is segmented into four hydrogeological provinces crystalline basement province cbp cross river plain province crpp nkporo afikpo shales province nasp and alluvial buried river province abrp with localized groundwater flow patterns results indicated that the alluvial discharge rate of 3 83 l s fractured sandstone discharge rate of 2 43 l s and basement discharge rate of 1 80 l s aquifers are more yielding than the aquifers in areas covered with deformed shales discharge rate of 0 62 l s and siltstone aquifers discharge rate of 0 97 l s the aquifer horizons are inhomogeneous and anisotropic with topography and lithology exerting significant influence on groundwater flow direction however there appears to be some high yielding aquifers at depths greater than 100 m in the crpp areas although researches on their distribution are still ongoing precipitation is the major source of recharge and the water is enriched with na k ca2 mg2 text hco 3 cl text so 4 2 and text no 3 throughout the year graphical analyses of hydrochemical data using piper and stiff diagrams show that ca mg co3 hco3 is the dominant water facies results from ec sar and na show that the water is fresh and belongs to the good to excellent class and is therefore suitable for domestic agricultural and industrial use

migration of shallow seismic reflection data we present an analysis of migration effects on seismic reflection images of very shallow targets such as those that are common objectives of engineering groundwater and environmental investigations we use an example of seismic reflection data from depths of 5 to 15 m that show negligible effect from migration despite the apparent steep dip on the seismic section our analysis of the question of when to migrate shallow reflection data indicates it is critical to take into account the highly variable near surface velocities and the vertical exaggeration on the seismic section a simple set of calculations is developed as well as a flow chart based on the migrator s equation that can predict whether migration of an arbitrary shallow seismic section is advisable because shallow reflection data are often processed on personal computers unnecessary migration of a large data set can be prohibitively time consuming and wasteful