the paleohydrology of lower cretaceous seasonal wetlands isle of wight southern england abstract the floodplain deposits of the wealden group lower cretaceous of the isle of wight southern england were formed in a seasonal wetland setting a type of environment widespread today along higher order tropical and subtropical river systems but rarely identified in the geological record the unit consists of four main lithofacies sheet sandstones with dinosaur footprint casts green gray mudstones with vertebrate remains abundant lignite pyrite and siderite spectacularly color mottled mudstones with goethite and locally pseudo anticlines and red mudstones with pseudo anticlines hematite and carbonate nodules the sheet sandstones are interpreted as crevasse deposits the green gray mudstones were deposited in shallow ponds on the floodplain which acted as sinks for debris released by local floods following wildfires the mottled mudstones represent surface water gley soils formed in seasonally waterlogged areas and the red mudstones resemble present day vertisols that formed on topographically elevated areas only intermittently flooded these mudstones show vertical transitions from one to another and although they could be interpreted as components of simple catenas the absence of associated facies changes implies that topographic differences were not the only control it is proposed that these three mudstone types formed as seasonal wetland catenas in which differences in soil drainage conditions resulted from variations in the flooding hydroperiod affecting areas with minor relief differences rather than drainage variability simply reflecting static topographic differences such seasonal wetland systems are rarely documented in the stratigraphic record despite being a widespread environment in present day tropical regions and the wealden deposits are used to identify criteria for the recognition of this important environment in the rock record these southern english wetlands are compared with other lower cretaceous wetlands from northern spain enabling hydrological factors which controlled deposition to be recognized

pedogenic carbonate proxies for amount and seasonality of precipitation in paleosols the depth to carbonate nodular bk horizon in soils d in cm is correlated with mean annual precipitation p in mm so that bk horizons are deep in subhumid regions but shallow in semiarid regions previous quantifications of this relationship are unchanged by this new compilation of 807 soils p 137 24 6 45 d 0 013 d 2 where r 2 0 52 and standard error s e 147 mm in most north american postglacial soils the bk horizon is thin and well defined whereas in monsoonal tropical soils of pakistan and kenya the bk horizon is thick and diffuse data from 675 modern soils define the relationship between the thickness of soil with nodules t in cm and mean annual range of precipitation m in mm difference between monthly means of wettest and driest months m 0 79 t 13 71 where r 2 0 58 and s e 22 mm the relationship between carbonate nodule size s in cm and soil age a in ka is quantified by 9 radiocarbon dated soils from las cruces new mexico a 3 92 s 0 34 where r 2 0 57 and s e 1 8 k y these transfer functions are applied to reconstructing paleoclimatic change from paleocene eocene paleosols of the north horn formation and flagstaff limestone of axhandle canyon utah the terminal paleocene spike of warmth recorded by fossil plants in nearby wyoming was coincident with a brief peak in both mean annual precipitation and mean annual range of precipitation in utah

thermal genesis of dissolution caves in the black hills south dakota jewel cave 118 km of mapped passages beneath an area of 2 7 km 2 and wind cave 70 km beneath 1 8 km 2 are respectively the fourth and tenth longest known cave systems and the world9s foremost examples of three dimensional rectilinear networks of solutional passages other caves in the black hills are similar they occur in 90 140 m of well bedded mississippian limestone and dolomite walls throughout jewel cave are lined with euhedral calcite spar as much as 15 cm thick wind cave displays lesser encrustations and remarkable calcite boxwork since 1938 opinion has favored cave excavation by slowly circulating meteoric waters in artesian confinement similar to that surrounding the black hills we believe that the caves were developed by regional thermal waters focusing on paleospring outlets in outlying sandstones four sets of criteria are evaluated 1 morphological the three dimensional one phase maze form having convectional features is similar to known and supposed thermal caves in europe 2 petrographic and mineralogical study of the chief precipitates shows a record of carbonate solution calcite precipitation consonant with a model of cooling then degassing waters 3 a thermal anomaly at regional hot springs is shown to extend beneath wind cave where basal lake water samples show chemical and isotopic affinities with the thermal waters and 4 13 c and 18 o measurements place all suspected paleothermal water precipitates in the domain of thermal calcites reported by others and being deposited at the modern hot springs finally u series dates show that the wind cave deposits are quaternary and that the cave is still draining jewel cave is truly relict and divorced from the modern thermal ground water system its great calcite spar sheets are probably older than 1 25 1 50 ma

origin and morphology of limestone caves limestone caves form along ground water paths of greatest discharge and solutional aggressiveness flow routes that acquire increasing discharge accelerate in growth while others languish with negligible growth as discharge increases a maximum rate of wall retreat is approached typically about 0 01 0 1 cm yr determined by chemical kinetics but nearly unaffected by further increase in discharge the time required to reach the maximum rate is nearly independent of kinetics and varies directly with flow distance and temperature and inversely with initial fracture width discharge gradient and pco2 most caves require 104 105 yr to reach traversable size their patterns depend on the mode of ground water recharge sinkhole recharge forms branching caves with tributaries that join downstream as higher order passages maze caves form where 1 steep gradients and great undersaturation allow many alternate paths to enlarge at similar rates or 2 discharge or renewal of undersaturation is uniform along many alternate routes flood water can form angular networks in fractured rock anastomotic mazes along low angle partings or sponge work where intergranular pores are dominant diffuse recharge also forms networks and spongework often aided by mixing of chemically different waters ramiform caves with sequential outward branches are formed mainly by rising thermal or h2s rich water dissolution rates in cooling water increase with discharge co2 content temperature and thermal gradient but only at thermal gradients of more than 0 01 c m can normal ground water co2 form caves without the aid of hypogenic acids or mixing artesian flow has no inherent tendency to form maze caves geologic structure and stratigraphy influence cave orientation and extent but alone they do not determine branch work versus maze character

response of late carboniferous and early permian plant communities to climate change abstract late carboniferous and early permian strata record the transition from a cold interval in earth history characterized by the repeated periods of glaciation and deglaciation of the south

bacteria fungi and biokarst in lechuguilla cave carlsbad caverns national park new mexico lechuguilla cave is a deep extensive gypsumand sulfur bearing hypogenic cave in carlsbad caverns national park new mexico most of which 90 lies more than 300 m beneath the entrance located in the arid guadalupe mountains lechuguilla s remarkable state of preservation is partially due to the locally continuous yates formation siltstone that has effectively diverted most vadose water away from the cave allocthonous organic input to the cave is therefore very limited but bacterial and fungal colonization is relatively extensive 1 aspergillus sp fungi and unidentified bacteria are associated with iron manganese and sulfur rich encrustations on calcitic folia near the suspected water table 466 m below the entrance 2 92 species of fungi in 19 genera have been identified throughout the cave in oligotrophic nutrient poor soils and pools 3 cave air condensate contains unidentified microbes 4 indigenous chemoheterotrophicseliberius andcaulobacter bacteria are known from remote pool sites and 5 at least four genera of heterotrophic bacteria with population densities near 5 105 colony forming units cfu per gram are present in ceiling bound deposits of supposedly abiogenic condensation corrosion residues various lines of evidence suggest that autotrophic bacteria are present in the ceiling bound residues and could act as primary producers in a unique subterranean microbial food chain the suspected autotrophic bacteria are probably chemolithoautotrophic cla utilizing trace iron manganese or sulfur in the limestone and dolomitic bedrock to mechanically and possibly biochemically erode the substrate to produce residual floor deposits because other major sources of organic matter have not been detected we suggest that these cla bacteria are providing requisite organic matter to the known heterotrophic bacteria and fungi in the residues the cavewide bacterial and fungal distribution the large volumes of corrosion residues and the presence of ancient bacterial filaments in unusual calcite speleothems biothems attest to the apparent longevity of microbial occupation in this cave

speleogenesis of an exhumed hydrothermal sulphuric acid karst in cambrian carbonates mount san giovanni sardinia in the past few years the systematic study of caves intercepted by mine workings in southwest sardinia has permitted us to observe morphologies due to rare speleogenetic and minerogenetic processes related to ancient hydrothermal activity these relic morphologies are slowly being overprinted by recent speleogenetic processes that tend to obscure the hypogene origin of these caves a combined geomorphological and mineralogical investigation has permitted a fairly detailed reconstruction of the various phases of evolution of these caves cave formation had already started in cambrian times but culminated in the carboniferous when most of the large voids still accessible today were formed a key role in carbonate dissolution was played by sulphuric acid formed by the oxidation of the polymetallic ores present in the rocks since the cambrian during the quaternary a variety of minerals formed inside the caves calcite and aragonite that yielded sequences of palaeo environmental interest and also barite phosgenite hydrozincite hemimorphite and many others these minerals are in part due to a phreatic thermal hypogenic cave forming phase and in part to later epigene overprinting in an oxidizing environment rich in polymetallic ores massive gypsum deposits elsewhere typical of this kind of caves are entirely absent due to dissolution during both the phreatic cave formation and the later epigenic stage copyright 2013 john wiley sons ltd

do red beds indicate paleoclimatic conditions a permian case study abstract terrestrial red beds have long been interpreted as desert deposits by comparison with modern red deserts more recently red beds have been interpreted as evidence of seasonally dry conditions and a permo triassic pangean monsoon red beds of cala viola sardinia are identified as paleosols and used to reconstruct late permian paleoclimatic conditions reconstruction of paleoenvironmental conditions based on the paleosols of the cala viola indicates warm humid conditions with no evidence of dry conditions as in a desert or of extreme seasonality as in a monsoon instead it is suggested that the red color of the paleosols is a result of former good drainage and that red color in general does not indicate specific paleoclimatic conditions

calcic paleosols of the plio pleistocene camp rice and palomas formations southern rio grande rift usa abstract seventy four separate paleosols are recognized in the plio pleistocene camp rice and palomas formations of the southern rio grande rift seven types of profiles are present a bw bk c a bt bk c bw bk c bt bk c bt k c bk c and ak calcic and petrocalcic horizons bk and k commonly overlain by argillic horizons bt dominate most paleosol profiles greater pore size and enhanced permeability typical of sandy and silty parent material favored the development of argillic horizons however micrite is the dominant form of calcium carbonate in bk and k horizons regardless of parent material grain size non calcified a horizons are typically lighter in color than adjacent subsurface pedogenic intervals due to their oxidized nature or lower clay content they are only rarely preserved probably due to erosion prior to final burial calcified root mats ak are not directly associated with other pedogenic horizons abundant horizontal roots suggest root mats formed under high water table conditions restriction of ak horizons to the distal piedmont lithofacies supports their development as spring or pond deposits near the toes of alluvial fans individual pedogenic horizons can often be traced hundreds of meters to kilometers normal and parallel to a basin s axis paleosol maturity and preservation potential are greatest for symmetrical basins especially where pedogenesis was far removed from active channels within the axial fluvial system or within distal piedmont settings of asymmetrical basins

a paleopedological and ichnological approach to interpreting spatial and temporal variability in early permian fluvial deposits of the lower dunkard group west virginia u s a abstract lower permian asselian deposits of the washington formation dunkard group in west virginia u s a represent proximal to distal expressions of a migrating anastomosing river and associated floodplain environments these deposits are part of the upper fluvial plain province of the dunkard basin characterized by thick to thin sandstone bodies shales and paleosols the paleosols and associated ichnofossils record a wealth of paleoenvironmental paleoecological and paleoclimatic data which improve our understanding of the autogenic and allogenic processes that result in the spatial and temporal variability of ancient fluvial systems this study integrates field and laboratory analysis of paleosols and ichnofossils including macro to micromorphology bulk geochemistry and clay mineralogy to better understand variations in soil forming processes across this early permian floodplain nine different pedotypes were identified including proximal poorly developed entisols and inceptisols poorly drained histosols and thick moderately to well drained inceptisols and vertisols lateral differences in paleosol properties were minor compared to the diversity of paleosols present in the vertical exposure and were largely a result of localized variations in drainage and topography differences in the properties of the paleosols in the vertical succession could not be explained by variable drainage due to position on the floodplain cyclicity was largely controlled by avulsion but was overprinted by changes in climate while climatic drying during the early permian as a general trend is well established smaller scale fluctuations between wet and dry intervals contributed significantly to observed paleosol properties dominance by calcareous vertisols in the upper fluvial plain facies province and their representation of strongly seasonal conditions are consistent with previous research however thorough investigation of the paleosols suggests that more humid conditions existed than the arid to semiarid climate that has been suggested

the gruta de las maravillas aracena south west iberia setting and origin of a cave in marbles from dissolution of pyrite abstract the gruta de las maravillas cave is located at the wnw side of the cerro del castillo hill in aracena huelva sw spain the cavity is hosted within marbles included in a strip of high grade metamorphic rocks belonging to the so called aracena massif in the southernmost ossa morena zone the hill is made up of granodiorites marbles quartzites and gneisses with the foliation trending n110 e and dipping roughly 60 80 towards ne the marbles appear highly deformed in ductile conditions with isoclinal folds of different sizes boudins porphyroblasts with sigmoidal morphology and left lateral s c shear fabrics close to the granodiorite contact the marbles include a thin band of disseminated and massive pyrite partially transformed to fe oxides analysis of the brittle deformation and the associated paleostresses indicates a ne sw oriented maximum compression probably related to the latest variscan collisional tectonics 300 ma late carboniferous the gruta de las maravillas is divided into three main levels located at 650 665 and 685 m a s l the dissolution having progressed from top to bottom in different stages of stability of the water table the initial dissolution phases were probably favoured by the presence of pyrite in the host rock which in turn would have caused acidification of the circulating water favouring this hypothesis a thin layer of fe oxides locally including gypsum covers some parts of the cave walls the morphology and structure of the cavity result from interaction between the general nne dipping foliation with sub perpendicular joints the pyrite bearing band in the host marbles and the descending water table

speleogenetic history of the hungarian hydrothermal karst the hydrothermal karst of hungary displays at least two principal stages of development in two differing environments caves of an early stage were formed within a deep zone of low thermal gradient these caves vugs are small tens of centimeters and lined with scalenohedral crystals of calcite that are often in association with barite calcite yields fluid inclusion temperatures of 55 95 c and is depleted in18o 11 2 to 17 6 per mil pdb the caves were formed by ascending thermal waters charged with co2 solubility of caco3 in such a system gradually increases with the ascent of the fluid solutional zone but drops sharply at a depth of 250 m to 500 m below the water surface depositional zone caves formed in the solutional zone may be shifted into the depositional zone due to tectonic uplift and calcite lines their walls large caves tens to thousands of cubic meters of a late stage were formed within a shallow zone of high thermal gradient immediately below and above the thermal water table the calcite of the phreatic crusts has a rhombohedral habit displays lower fluid inclusion temperatures 35 55 c and less and a depletion in18o of 9 5 to 14 6 per mil pdb several powerful cave forming processes may operate there including convection mixing cooling corrosion and condensation corrosion due to differences in the rate of tectonic uplift rate of hydrothermal system decay and hydrogeologic pattern these caves were either filled with water for a long period of time phreatic calcite crusts are formed or partly dewatered early in their history waterline and subaerial speleothems are formed the zones of thermal cave formation recognized in hungary may have a universal character very similar features are found in other hydrothermal karst areas of the world kirghizia algeria south dakota

cyclic sedimentation in brazilian caves mechanisms and palaeoenvironmental significance abstract caves associated with doline slopes in the tectonically stable area of eastern brazil display remarkable sequences of clastic sediment intercalated with calcite layers sediment erosion has also occurred allowing access to formerly sediment filled passages the palaeoenvironmental meaning and chronology of these three processes i e clastic sediment input clastic sediment erosion and speleothem precipitation were studied in both semi arid campo formoso and sub humid lagoa santa areas through 230 th dating and stratigraphical analyses the dry climate of the campo formoso area prevents speleothem deposition at present but soil erosion results in valley aggradation and cave infilling growth periods of speleothems and travertines in this area have allowed the recognition of recurrent past phases of increased humidity correlated with wet conditions recorded in southeastern brazil speleothem calcite at the lagoa santa area there is limited speleothem precipitation and sediment input at present however sediment entrainment is actively exhuming speleothems and exposing cave passages sediment erosion inside caves in the area is interpreted as being due to intermediate climatic conditions not wet enough to favour speleothem deposition and not too dry to allow doline slope erosion and sediment transport into caves due to the low rates of denudation and isostatic rebound inherent to tectonically stable areas cave passages will remain within the range of sediment infill and erosion for a much longer time than in tectonically active areas spanning in average at least three full glacial interglacial cycles as uplift proceeds cave passages will be decoupled from the doline bottom and no longer will be affected by erosion or infilling episodes sediment filled passages in many caves in the lagoa santa region are relict features that display ancient clastic and chemical precipitation the three processes described above have occurred throughout the life history of the caves resulting in complex sediment assemblages that can however show significant intra and inter site variations

paleo watertable definition using cave ferromanganese stromatolites and associated cave wall notches sierra de arnero spain abstract the steeply dipping dolostone hosted caves of the sierra de arnero n spain contain low gradient relict canyons with up to ten mapped levels of ferromanganese stromatolites and associated wall notches over a vertical range of 85 m the highest occurring 460 m above base level despite a plausible speleogenetic contribution by pyrite oxidation and the irregular cave wall mesomorphologies suggestive of hypogenic speleogenesis the arnero relict caves are dominantly epigenic as indicated by the conduit pattern and the abundant allogenic sediments allogenic input declined over time due to a piracy related decrease in the drainage area of allogenic streams explaining the large size of the relict arnero caves relative to the limited present day outcrop area of the karstified carbonates allogenic sediment input also explains the observed change from watertable canyons to phreatic conduits in the paleo downstream direction stromatolites and notches arguably formed in cave stream passages at the watertable the best defined paleo watertables show an overall slope of 1 7 consistent with the present day relief of the watertable with higher slope segments caused by barriers related to sulfide mineralization the formation of watertable stromatolites favored wall notching by the combined effect of enhanced acidity by mn fe oxidation and shielding of cave floors against erosion abrasive bedload further contributed to notch formation by promoting lateral mechanical erosion and protecting passage floors the irregular wallrock erosional forms of arnero caves are related partly to paragenesis and partly to the porous nature of the host dolostones which favored irregular dissolution near passage walls generating friable halos subsequent mechanical erosion contributed to generate spongework patterns the dolostone porosity also contributes to explain the paradox that virtually all arnero caves are developed in dolostone despite being less soluble than adjacent limestone u series dating of carbonate speleothems and paleomagnetic data from ferromanganese stromatolites and clastic sediments indicate that the paleo watertables recorded 320 m above the present day watertable formed during the matuyama chron but prior to 1 5 ma implying long term base level lowering rates from 125 to 213 m ma to our knowledge this is the first attempt of paleomagnetic dating of cave ferromanganese stromatolites these deposits are excellent geomagnetic recorders and offer a direct way to delineate and date paleo watertables especially in caves developed in dolostone

paleoenvironmental and paleoclimatic interpretations of the late paleocene goler formation southern california u s a based on paleosol geochemistry the paleocene was characterized by high global temperatures and elevated concentrations of atmospheric co2 paleoclimate records of this epoch are of particular interest to understanding the effects of anthropogenic climate forcing as well as linkages between the paleocene climate and major tectonic and evolutionary events however terrestrial paleoclimatic records of the paleocene are limited in their spatial extent and few such records are known from western north america in this study paleosols from two members in the late paleocene goler formation of southern california were used to investigate local paleoclimatic conditions the paleosols were described in detail and analyzed for morphology clay mineralogy and bulk geochemistry carbonate nodules present in paleosols from the upper member member 4a were characterized using petrographic and cathodoluminescence microscopy and were analyzed for carbon and oxygen stable isotope composition enrichment and retention of soluble elements ca mg and na and the mobilization of fe and mn in the paleosol profiles suggest a climate with strongly seasonal precipitation this interpretation is further supported by the presence of pedogenic slickensides and the clay minerals smectite and illite the appearance of pedogenic carbonate nodules in paleosols from the upper member is suggestive of a shift to more arid or more seasonal conditions that is coincident with a prominent change in sediment provenance and an inferred increase in sedimentation rate uplift of the ancestral sierra nevada during the late paleocene was likely an important control on regional paleoclimate due to the effects of elevated topography on mean annual precipitation and seasonal distribution of precipitation the correlation of a shift in pedogenic processes with changes in provenance and sedimentation rate suggests that the evolution of regional tectonic activity was an important control on these processes during the deposition of the goler formation

sulfuric acid speleogenesis sas close to the water table examples from southern france austria and sicily caves formed by rising sulfuric waters have been described from all over the world in a wide variety of climate settings from arid regions to mid latitude and alpine areas h2s is generally formed at depth by reduction of sulfates in the presence of hydrocarbons and is transported in solution through the deep aquifers in tectonically disturbed areas major fractures eventually allow these h2s bearing fluids to rise to the surface where oxidation processes can become active producing sulfuric acid this extremely strong acid reacts with the carbonate bedrock creating caves some of which are among the largest and most spectacular in the world production of sulfuric acid mostly occurs at or close to the water table but also in subaerial conditions in moisture films and droplets in the cave environment these caves are generated at or immediately above the water table where condensation corrosion processes are dominant creating a set of characteristic meso and micromorphologies due to their close connection to the base level these caves can also precisely record past hydrological and geomorphological settings certain authigenic cave minerals produced during the sulfuric acid speleogenesis sas phase allow determination of the exact timing of speleogenesis this paper deals with the morphological geochemical and mineralogical description of four very typical sulfuric acid water table caves in europe the grotte du chat in the southern french alps the acqua fitusa cave in sicily italy and the bad deutsch altenburg and kraushohle caves in austria

trace fossils from carboniferous floodplain deposits in western argentina implications for ichnofacies models of continental environments abstract floodplain deposits from the carboniferous tupe formation of western argentina contain a low diversity ichnofauna of invertebrates and plants the assemblage consists of archaeonassa fossulata didymaulichnus lyelli helminthoidichnites tenuis palaeophycus tubularis planolites isp and root traces this ichnofauna is characterized by the dominance of very simple forms superficial or very shallow trace fossils combination of locomotion grazing and dwelling structures and production by arthropods and vermiform organisms primary sedimentary fabrics are disturbed only by plant trace fossils while animal trace fossils are mostly restricted to bedding surfaces resulting in the virtual absence of bioturbation the poorly defined morphology of the ichnofossils and the absence of backfilled striated trace fossils and structures indicative of subaerial exposure suggest subaqueous production the envisaged depositional environment is a freshwater body developed in a floodplain and overfilled by overbank deposits a review of floodplain ichnofaunas documented from the stratigraphic record indicates that two recurrent assemblages may be recognized the first assemblage is characterized by low to rarely moderate diversity of invertebrate trace fossils moderate to high diversity of vertebrate structures and common presence of meniscate backfilled structures bilobate trace fossils with scratch marks arthropod trackways and tetrapod trackways it is regarded as an example of the scoyenia ichnofacies developed in desiccated floodplains the second type of floodplain assemblage illustrated by the example documented in this paper is characterized by grazing trails locomotion trails and dwelling burrows low to rarely moderate ichnodiversity simple trace fossils and superficial to very shallow structures although formed in floodplain environments also this type of assemblage is remarkably different from the scoyenia ichnofacies it is here regarded as an example of the mermia ichnofacies basic features of these ichnofaunas reflect subaqueous production of the assemblage the lower ichnodiversity of these floodplain assemblages in comparison with their equivalents from lacustrine basins is probably an expression of the less stable conditions and temporary nature of floodplain water bodies our study supports the view that ichnofacies are not indicators of sedimentary environments but reflect sets of environmental factors

late pennsylvanian early permian vegetational transition in oklahoma palynological record abstract the wabunsee carboniferous virgilian through sumner permian leonardian groups of oklahoma preserve a record of terrestrial and nearshore marine environments during glacio eustatic fluctuations caused by southern hemisphere glaciation this section with the pennsylvanian permian boundary firmly established in the red eagle formation on the basis of conodonts permitted study of vegetational change across the boundary interval the palynology of 43 productive samples from five cores in kay and osage counties in oklahoma was investigated palynomorphs were assigned to eight morphologic groups that also reflect climate preferences four distinct palynofloras are recognized the three transitions between them in the lower council grove middle chase and lower sumner groups are abrupt and in succession consistent with an interpretation of increasing seasonality aridity from latest pennsylvanian into the early permian none of these floristic transitions align with the conodont based boundary or with any lithostratigraphic group boundary these palynological data from oklahoma are in accord with previous data from kansas that also demonstrated no palynological shift at the boundary and increased seasonality aridity through this period comparison of the palynofloras from oklahoma kansas and the boundary interval of the pennsylvanian permian boundary type section in aidaralash creek in kazakhstan reveals differences in composition that suggest local to regional including climatically induced heterogeneities that may present an obstacle to confident palynologically based global correlations in fully terrestrial sections

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part i characterization of paleosol types and interpretation of pedogenic processes abstract the morphology mineralogy and stratigraphic and lateral distribution of paleosols in pennsylvanian moscovian gzhelian atokan virgilian mixed marine and terrestrial coal bearing strata i e cyclothems in the illinois basin ib are presented in order to determine the dominant pedogenic processes within a cyclic sedimentary depositional framework paleosol morphologies range from weakly developed horizons with evidence of rooting and little to no pedogenic structure to horizons with well developed pedogenic slickensides angular blocky structure and carbonate nodules and tubules the majority of paleosols in strata from the basin interior preserve 1 low chroma gley colors 2 identifiable fossil plant organic matter that increases in abundance upward in the profiles toward the interpreted paleo surface and 3 calcite sphaerosiderite and pyrite cements and nodules in contrast paleosols in strata from the northern margin of the basin display high chroma colors and calcite cements and less fossil organic matter sphaerosiderite and pyrite cements these observations indicate that paleosols from the basin interior underwent a multi phase pedogenic and shallow burial history characterized by an initial better drained oxygenated stage under seasonal precipitation followed by a poorly drained reducing stage while paleosols from the northern margin of the basin experienced overall more oxygenated conditions throughout their pedogenic development x ray diffraction analysis of the 2 m size fraction of paleosol matrix in ib paleosols indicates a mineralogical composition dominated by kaolinite randomly interstratified r0 and ordered r1 illite smectite i s and subordinate amounts of chlorite these combined observational and mineralogical datasets indicate that significant changes in paleohydrology were largely responsible for the development of pennsylvanian soil profiles in the ib

from cyclothems to sequences the record of eustasy and climate on an icehouse epeiric platform pennsylvanian permian north american midcontinent the stratigraphic succession of the north american midcontinent contains a high resolution 100 000 year record of sea level and climate change spanning the pennsylvanian permian boundary outcrop based sequence stratigraphic analysis on the upper wabaunsee admire and lower council grove groups in kansas and nebraska reveals a hierarchy of fifty one fifth order meter scale cycles grouped into five fourth order composite sequences fifth order cycles are bounded by subaerial unconformities in nearshore settings and correlative conformities in offshore settings and are therefore very thin depositional sequences lowstand systems tracts observed only in nearshore deposits are expressed as sandy incised valley fills in these meter scale cycles transgressive systems tracts which are dominated by carbonate deposition include coastal evaporites indicating arid climatic conditions highstand systems tracts which are dominated by siliciclastic deposition include thin but persistent coals in muddy coastal successions indicating humid climatic conditions paleosols at sequence boundaries evolve from vertic to calcic indicating climate change from relatively humid to relatively arid conditions during subaerial exposure this indicates that relatively arid climate coincided with eustatic lows while relatively humid climate coincided with eustatic highs on this low latitude platform composite sequences are bounded by subaerial angular unconformities and display a transgressive regressive stacking pattern of meter scale cycles the high resolution stratigraphic record of the midcontinent helps constrain the rate and magnitude of environmental change in ancient icehouse conditions and can serve as a baseline of environmental change for comparison with other coeval successions

large camborygma isp in fluvial deposits of the lower permian asselian dunkard group southeastern ohio u s a abstract the lower washington formation of the lower permian asselian dunkard group in southeastern ohio contains large burrows exposed in cross section in a laterally discontinuous sandstone bed this study examined the morphology of the burrows and their associated lithofacies to interpret the environmental conditions under which they were produced as well as the behavior and identity of the trace maker mudstone facies below and above the burrow bearing sandstone consist of reddish brown to variegated paleosols containing rhizohaloes argillans and large scale slickensides as well as thinly laminated organic rich shales containing plant fossils the sandstone facies is 94 147 cm thick thinly bedded to massive and fine to medium grained the lithofacies are interpreted as deposits of crevasse splays abandoned channels and proximal to distal floodplains sixty burrows consist of vertical subvertical j shaped y shaped and complex networks of branching shafts and tunnels the burrows range from 5 to 180 cm in length and 0 8 3 6 cm in width the main shaft s angles are typically 90 although are rarely 30 70 branching angles of subvertical and y shaped burrows vary from 0 to 90 many burrows extend to the top of the sandstone bed but others turn into or out of the bed the morphology of the burrows is most similar to camborygma known from continental deposits of the permian to recent while camborygma has been previously reported from the permian this is the first occurrence in the late paleozoic appalachian basin extending its geographic range the dunkard burrows are similar to those of modern freshwater decapods particularly crayfish decapod body fossils are not known from the dunkard group yet these burrows are highly suggestive of their presence therefore these fossil burrows contribute to the paleoecological interpretation of the dunkard group helping to fill in gaps of the terrestrial fauna not otherwise preserved in the fossil record decapod burrow morphologies are highly variable depending on burrow function and environment the dunkard burrows are similar to secondary dwellings with few open water attachments multiple branches and shafts likely extending to the water table

sulfuric acid speleogenesis of carlsbad cavern and its relationship to hydrocarbons delaware basin new mexico and texas sulfur isotope data and ph dependence of the mineral endellite support the hypothesis that carlsbad cavern and other caves in the guadalupe mountains were dissolved primarily by sulfuric acid rather than by carbonic acid floor gypsum deposits up to 10 m thick and native sulfur in the caves are significantly enriched in 32 s isotope 34 s values as low as 25 8 per mil cdt indicate that the cave sulfur and gypsum are the end products of microbial reactions associated with hydrocarbons a model for a genetic connection between hydrocarbons in the basin and caves in the guadalupe mountains is proposed as the guadalupe mountains were uplifted during the late pliocene pleistocene oil and gas moved updip in the basin the gas reacted with sulfate anions derived from dissolution of the castile anhydrite to form h 2 s co 2 and castile limestone the hydrogen sulfide rose into the capitan reef along joints forereef carbonate beds or bell canyon siliciclastic beds and there reacted with oxygenated groundwater to form sulfuric acid and carlsbad cavern a sulfuric acid mode of dissolution may be responsible for large scale porosity of some delaware basin reservoirs and for oil field karst reservoirs in other petroleum basins of the world

sulfuric acid caves of italy a review abstract in italy especially along the apennine chain numerous active and inactive sulfuric acid speleogenetic sas caves have been documented in the last two decades here we present an overview of these peculiar hypogene systems illustrating their main geomorphological and mineralogical features and the microbial signatures observed in the active underground environment sas caves are widely distributed in the northern and central apennines whereas they are less abundant in the southern apennines in the apulian foreland in sicily and in sardinia their location is significantly influenced by lithological and structural rock properties as they occur in carbonate areas where acidic fluids deriving from the interactions with deep seated sulfates and or sulfides rise through deeply rooted geological structures geomorphological observations demonstrated sub horizontal maze passages to be one of the most favorite arrangements for sas caves whereas gypsum sulfur and alunite supergroup minerals are the most typical sulfuric acid by products the 34 s results demonstrated the deep seated h2s sources to be mainly related to the interaction between triassic evaporites and hydrocarbons

dunkard group coal beds palynology coal petrography and geochemistry abstract coal beds that occur in the dunkard group are typically thin avg 0 3 m and are high in ash yield avg 27 8 and total sulfur content avg 5 1 petrographically dunkard coals are high in vitrinite avg 83 1 mmf with correspondingly low to moderate amounts of liptinite avg 2 1 mmf and inertinite avg 13 8 mmf palynologically dunkard coal beds are all dominated by tree fern spore taxa avg 96 3 especially punctatisporites minutus avg 82 8 calamite spores are the second most abundant plant group avg 2 4 with others lycopods small ferns cordaites and other gymnosperms having very minor representation overall the coal palynofloras are strongly dominated by lowland plants ferns and calamites with only rare occurrences of bisaccate striate conifer pollen coal beds of the underlying monongahela group pittsburgh redstone sewickley and waynesburg are thicker avg 1 6 m and are lower in ash avg 13 4 and sulfur avg 3 3 than their dunkard counterparts petrographically monongahela group coals are very similar to dunkard group coals when compared on a mineral matter free basis coal beds that occur in both groups are strongly dominated by vitrinite macerals monongahela group coals are also palynologically very similar to dunkard group coals with tree fern spore taxa dominating a coal bed of early permian age from west central texas is also similar petrographically and palynologically to dunkard and monongahela coals being vitrinite and tree fern spore dominant the almost complete lack of coniferous pollen in dunkard coals led earlier workers to conclude that the dunkard was entirely late pennsylvanian and not permian in age however it is now known that late pennsylvania lowland floras persisted into the dunkard especially during wet intervals as earlier interpretations were based primarily on spore and pollen floras from coal beds the lack of conifer pollen in dunkard coals is probably the result of a sampling bias because of this ecological bias coal palynology is a poor proxy for age dating dunkard group coals collectively dunkard swamps were all planar and topogenous their formation being controlled by topography and moisture availability a progressive decrease in wet intervals both in terms of frequency and duration during the dunkard was the major control on peat accumulation and preservation collectively moisture limitation appears to be the principle factor that controlled the formation of dunkard group coals

occurrence of hypogenic caves in a karst region examples from central italy the caves of the umbria and marche regions in central italy are made up of three dimensional maze systems that display different general morphologies due to the various geological and structural contexts at the same time the internal morphologies of the passages galleries and shafts present some similarity with solutional galleries characterized by cupolas and blind pits anastamotic passages roof pendants and phreatic passages situated at different levels some of these caves are still active as is the case for frassassi gorge parrano gorge and acquasanta terme with galleries that reach the phreatic zone where there is a rising of highly mineralized water rich in hydrosulfydric acid and with erosion of limestone walls and the formation of gypsum elsewhere there are fossil caves such as monte cucco and pozzi della piana where large speleothems of gypsum are present 500 m or more above the regional water table in all of these important karst systems it is possible to recognize basal input points through fracture and intergranular porosity networks at the base of the oxidizing zone in the core of the anticline where mineralized water rises up from the triassic evaporitic layers in small hydrogeological circuits different underground morphologies can derive from the presence of a water table related to an external stream or from the confined setting of the carbonate rocks underlying low permeable sedimentary cover where artesian conditions can occur

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

alluvial paleosols and pedofacies sequences in the permian lower beaufort of the southwestern karoo basin south africa abstract three types of paleosol profiles are described as representative of the range of soil types that developed on the ancient alluvial plains of the southwestern karoo basin during the late permian continuous 3 dimensional exposures of the lower beaufort adelaide subgroup strata allow detailed sedimentological taphonomic and paleopedological observation of thick floodplain sequences that contain numerous stacked paleosol profiles various floodplain strata contain characteristic paleosol profiles that are regulated by the periodicity and competence of overbank flooding both of which decrease with increasing distance from the contributing channel paleosols developed in levee or channel bank deposits are immature calcic entisols displaying evidence of early carbonate translocation but without well developed horizonation proximal floodbasin paleosols at the foot of the meanderbelt slope are mature calcic vertisols with more fully developed profiles containing zones of both carbonate and clay illuviation as well as some groundwater calcretes slickensided stress argillans in the b horizons are indicative of multiple cycles of wetting and drying distal floodbasin paleosols are dominated by hydromorphic and evaporitic processes as a result of their axial position in the floodbasin sheet like networks of mudcrack casts composed of calcretized aeolian sand and silt suggest that dust was a major source of calcium carbonate to the e soils the paleosols are interpreted as having formed under warm to hot semi arid climatic conditions with a strongly seasonal rainfall of 500 to 800 mm per annum and a mean annual moisture deficiency the geomorphic setting was similar to the holocene indo gangetic alluvial plain vertebrate burrow casts in the proximal floodbasin facies indicate a minimum depth to watertable of 150 cm the distribution of rooted horizons reflects dense vegetation flanking major drainage channels and sparse cover in the distal floodbasin a simple stratigraphic sequence of once laterally continuous paleosols is termed a pedofacies stacked sequences of pedofacies within approximately 20 50 m thick and 100 250 m thick stratigraphic successions reflect second and first order sedimentary cycles respectively both scales of cyclicity are attributed to autocyclically controlled avulsions of differentially aggrading channels in the first instance and of complete drainage networks in the second

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

paleopedologic and paleohydrologic records of precipitation seasonality from early pennsylvanian underclay paleosols u s a underclays in the crooked fork group lower pennsylvanian atokan langsettian in eastern tennessee u s a are paleosols associated with fourth order depositional sequences that record changing paleohydrologic conditions during their formation climate changes possibly milankovitch driven resulted in evolution of soil landscapes from well drained seasonally wet floodplains and delta plains dominated by vertic vertisol like paleosols to very poorly drained everwet swamps dominated by sideritic gley paleosols coals paleohistosols cap most underclays and record peat swamp development during everwet conditions followed by marine submergence pedogenic slickensides and angular blocky ped structures in conjunction with illuviated clay pore fillings and sepic plasmic microfabric indicate an initial better drained phase of paleosol development stage i gley overprinting characterized by drab low chroma paleosol colors fe reduction in upper portions of paleosols sideritic rhizocretions sphaerosiderite and pyrite nodules extensive leaching and translocation of alkali and alkaline earth elements and kaolinitization of smectites and hydroxy interlayer vermiculite hiv indicate a later poorly drained stage of paleosol development characterized by saturated conditions moderate to low eh and low ph stage ii as well as peat swamp development lastly burial and juxtaposition of marine facies on top of terrestrial deposits terminated paleosol and peat development stage iii paleosols likely formed under conditions of marked seasonality of rainfall judging from both modern analog systems in sumatra and pennsylvanian paleoclimate models the chemical index of alteration without potash cia k was used as a proxy for atokan paleoprecipitation estimated as 1300 mm yr this estimate is comparable with mean annual precipitation map in modern tropical to subtropical rainy environments

microbiology and geochemistry in a hydrogen sulphide rich karst environment abstract cueva de villa luz a hypogenic cave in tabasco mexico offers a remarkable opportunity to observe chemotrophic microbial interactions within a karst environment the cave water and atmosphere are both rich in hydrogen sulphide measured h 2 s levels in the cave atmosphere reach 210 ppm and so 2 commonly exceeds 35 ppm these gases plus oxygen from the cave air are absorbed by freshwater that accumulates on cave walls from infiltration and condensation oxidation of sulphur and hydrogen sulphide forms concentrated sulphuric acid drip waters contain mean ph values of 1 4 with minimum values as low as 0 1 the cave is fed by at least 26 groundwater inlets with a combined flow of 200 300 l s inlet waters fall into two categories those with high h 2 s content 300 500 mg l mean p co 2 0 03 0 1 atm and no measurable o 2 and those with less than 0 1 mg l h 2 s mean p co 2 0 02 atm and modest o 2 content up to 4 3 mg l both water types have a similar source as shown by their dissolved solid content however the oxygenated water has been exposed to aerated conditions upstream from the inlets so that original h 2 s has been largely lost due to outgassing and oxidation to sulphate increasing the sulphate concentration by about 4 chemical modelling of the water shows that it can be produced by the dissolution of common sulphate carbonate and chloride minerals redox reactions in the cave appear to be microbially mediated sequence analysis of small subunit 16 s ribosomal rna genes of 19 bacterial clones from microbial colonies associated with water drips revealed that 18 were most similar to three thiobacilli spp a genus that often obtains its energy from the oxidation of sulphur compounds the other clone was most similar to acidimicrobium ferrooxidans a moderately thermophilic mineral sulphide oxidizing bacterium oxidation of hydrogen sulphide to sulphuric acid and hence the cave enlargement is probably enhanced by these bacteria two cave enlarging processes were identified 1 sulphuric acid derived from oxidation of the hydrogen sulphide converts subaerial limestone surfaces to gypsum the gypsum falls into the cave stream and is dissolved 2 strongly acidic droplets form on the gypsum and on microbial filaments dissolving limestone where they drip onto the cave floors the source of the h 2 s in the spring waters has not been positively identified the villahermosa petroleum basin within 50 km to the northwest or the el chichon volcano 50 km to the west may serve as source areas for the rising water depletion of 34 s values 11 7 for sulphur stabilized from h 2 s in the cave atmosphere along with the hydrochemistry of the spring waters favour a basinal source

hypogene sulfuric acid speleogenesis and rare sulfate minerals in baume galiniere cave alpes de haute provence france record of uplift correlative cover retreat and valley dissection the oxidation of hydrocarbons and sulfide sources h2s pyrite produces sulfuric acid that strongly reacts with bedrock causing limestone dissolution and complex interactions with other minerals from the bedrock or from cave fillings mainly clays this type of cave development known as sulfuric acid speleogenesis sas is a subcategory of hypogene speleogenesis where aggressive water rises from depth it also produces uncommon minerals mainly sulfates the typical byproducts of sas baume galiniere is located in southern france in the vaucluse spring watershed this small maze cave displays characteristic sas features such as corrosion notches calcite geodes iron crusts and various sulfate minerals sulfur isotopes of sas byproducts jarosite and gypsum clearly show they derive from pyrite oxidation using xrd and micro raman spectroscopy thirteen minerals were identified including elemental sulfur calcite quartz pyrite goethite gypsum and fibroferrite plus all of the six members of the jarosite subgroup jarosite argentojarosite ammoniojarosite hydroniumjarosite natrojarosite plumbojarosite the baume galiniere deposits are the first documented cave occurrence of argentojarosite and the second known occurrence of plumbojarosite hydronium jarosite ammoniojarosite and fibroferrite in the vaucluse watershed there were numerous upwellings of deep water along major faults located at the contact of the karstic aquifer and the overlying impervious covers the mixing of deep and meteoric waters at shallow depths caused pyrite depositions in numerous caves including baume galiniere sulfuric acid speleogenesis occurred later after base level drop when the cave was under shallow phreatic conditions then in the vadose zone with oxidation of pyrites generating sulfuric acid attenuated oxidation is still occurring through condensation of moisture from incoming air baume galiniere cave records the position of the semi impervious paleo cover and documents its retreat in relationship to valley incision caused by uplift and tilting of the vaucluse block during the neogene

superposed folding and associated fracturing influence hypogene karst development in neoproterozoic carbonates sao francisco craton brazil abstract porosity and permeability along fractured zones in carbonates could be significantly enhanced by ascending fluid flow resulting in hypogene karst development this work presents a detailed structural analysis of the longest cave system in south america to investigate the relationship between patterns of karst conduits and regional deformation our study area encompasses the toca da boa vista tbv and toca da barriguda tbr caves which are ca 107 km and 34 km long respectively this cave system occurs in neoproterozoic carbonates of the salitre formation in the northern part of the sao francisco craton brazil the fold belts that are around and at the craton edges were deformed in a compressive setting during the brasiliano orogeny between 750 and 540 ma based on the integrated analysis of the folds and brittle deformation in the caves and in outcrops of the surrounding region we show the following 1 the caves occur in a tectonic transpressive corridor along a regional thrust belt 2 major cave passages at the middle storey of the system considering both length and frequency developed laterally along mainly a ne sw to e w and b n to s oriented anticline hinges 3 conduits were formed by dissolutional enlargement of subvertical joints which present a high concentration along anticline hinges due to folding of competent grainstone layers 4 the first folding event f1 was previously documented in the region and corresponds with nw se to n s trending compression whereas the second event f2 documented for the first time in the present study is related to e w compression and 5 both folding events occurred during the brasiliano orogeny we conclude that fluid flow and related dissolution pathways have a close relationship with regional deformation events thus enhancing our ability to predict karst patterns in layered carbonates

influence of fracture stratigraphy on hypogene cave development and fluid flow anisotropy in layered carbonates ne brazil abstract fractured and karstified carbonates are often major aquifers and hydrocarbon reservoirs the toca da boa vista tbv and toca da barriguda tbr caves in ne brazil which form the longest cave system in south america developed in a gently folded layered and fractured neoproterozoic carbonate sequence made of different lithological units limestones versus siliciclastic rocks and marls with variable bed properties bed thickness surface roughness of bed to bed interlayers and fracture attributes spacing height the functional organization of the hypogenic cave system has been recently revealed with subdivision in three speleo stratigraphic storeys which from bottom to top acted as recharge lateral redistribution and outflow components of the rising fluid flow system respectively structural analysis and new fracture data from tbv and tbr indicate that the stratigraphic setting controlled the fracture pattern development during two tectonic phases which determined the fluid flow anisotropy during speleogenesis we found that mechanical and fracture stratigraphy in conjunction with bed thickness and bed to bed interlayer characteristics controlled the spacing and height of fractures and as a result strongly influenced the fluid flow pattern and functional organization of the cave system in particular bed normal rising fluids localized along m to tens of m spaced throughgoing fractures developed in the lower and upper storeys whereas horizontal and bed parallel fluid flow was focused in a package of thin carbonates siliciclastics and marls with cm spaced strata bound fractures this fluid flow anisotropy is attained also due to the presence of rough walled bedding parallel interlayers i e burial stylolites in the lower massive grainstone which hampered bed parallel flow and smooth planar bedding parallel interlayers which enhanced lateral fluid movements in the well layered and fractured middle storey units therefore we conclude that in heterolithic layered carbonate packages the intricate hypogenic karst pattern is related to heterogeneous fluid flow behaviour associated with the structural complexity imparted by the mechanical versus fracture stratigraphy

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

cenozoic paleoclimate on land in north america abstract paleotemperature and paleoprecipitation over the past 40 m yr can be inferred from the degree of chemical weathering and depth of carbonate nodules in paleosols of oregon montana and nebraska paleosol records show that late eocene 35 ma middle miocene 16 ma late miocene 7 ma and early pliocene 4 ma warm climatic episodes were also times of a wet climate in oregon montana and nebraska oregon and nebraska were humid during warm wet times but montana was no wetter than subhumid within the rain shadow of intermontane basins global warm wet paleoclimatic spikes steepened rather than flattened geographic gradients of rocky mountain rain shadows long lived mountain barriers created dusty dry basins with sedimentation rates high enough to preserve milankovitch scale 100 41 kyr global paleoclimatic variation in some sequences of paleosols greenhouse warm wet climates indicated by paleosols were also peaks of diversity for north american plants and animals and coincided with advance

the influence of bedrock derived acidity in the development of surface and underground karst evidence from the precambrian carbonates of semi arid northeastern brazil very extensive cave systems are developed in precambrian una group carbonates in the campo formoso area eastern brazil in contrast the area is largely devoid of significant surface karst landforms as would be expected given its semi arid climate the caves in the area display many morphological features characteristic of deep seated hypogenic caves such as lack of relationship with the surface ramiform network pattern abrupt variations of passage cross sections and absence of fluvial sediments but do not show evidence of vertical passages marking the ascending path of acidic water nor present extensive gypsum or acid clay mineral deposits hydrochemical analyses of present day ground water indicate that oxidation of bedrock sulphide is an active process and sulphuric acid may be the main agent driving carbonate dissolution in the area a shallow mode of speleogenesis is thus proposed in which sulphuric acid produced through the oxidation of sulphide beds within the carbonates controls cave initiation and development moreover the geological situation of the area in an ancient stable passive margin precludes the possibility of deep seated sources of acidity under dry climate due to the absence of recharge solutional landforms will be largely subdued in the surface hypogenic processes if present are likely to predominate producing a landscape characterized by a marked disparity in the comparative degree of development between surface and underground landforms rates of karst landform development have traditionally been analysed through a climatic perspective runoff being the main controlling factor in promoting karst development this view needs to be reassessed in the light of the growing awareness of the importance of climate independent processes related to hypogenic sources of acidity copyright 2003 john wiley sons ltd

sulfur redox reactions hydrocarbons native sulfur mississippi valley type deposits and sulfuric acid karst in the delaware basin new mexico and texas hydrocarbons native sulfur mississippi valley type mvt deposits and sulfuric acid karst in the delaware basin southeastern new mexico and west texas usa are all genetically related through a series of sulfur redox reactions the relationship began with hydrocarbons in the basin that reacted with sulfate ions from evaporite rock to produce isotopically light 34s 22 to 12 h2s and bioepigenetic limestone castiles this light h2s was then oxidized at the redox interface to produce economic native sulfur deposits 34s 15 to 9 in the castiles paleokarst and along graben boundary faults this isotopically light h2s also migrated from the basin into its margins to accumulate in structural anticlinal and stratigraphic yates siltstone traps where it formed mvt deposits within the zone of reduction 34s 15 to 7 later in time in th zone of oxidation this h2s reacted with oxygenated water to produce sulfuric acid which dissolved the caves e g carlsbad cavern and lechuguilla cave guadalupe mountains massive gypsum blocks on the floors of the caves 34s 25 to 4 were formed as a result of this reaction the h2s also produced istopically light cave sulfur 34s 24 to 15 which is now slowly oxidizing to gypsum in the presence of vadose drip water

soil structure and nutrient contents in underground fissures in a rock mantled slope in the karst rocky desertification area near surface karst fissures are filled with soils these soils are often derived from the erosion and transport of surface soil but have different properties than the surface soil in karst rocky desertification regions this study was undertaken to determine the soil structure and nutrient contents in underground fissures with different grades of rocky desertification no potential mild moderate and severe based on field surveys near surface karst fissures were selected in a typical karst plateau area soil particle compositions particularly nutrient characteristics were determined through field sampling and laboratory experiments the results indicated that the higher the rock desertification grade was the higher the soil sand 0 02 2 mm content and the lower the clay 0 002 mm content the soil in both limestone and dolomite fissures was basically neutral to weakly alkaline the surface soil in dolomite fissures presented a higher soil organic matter content than that in limestone fissures but the opposite was true for the subsurface soil from the surface to the lower layer the total nitrogen content generally decreased and the total phosphorus content generally decreased in dolomite fissures but exhibited a more complex pattern in limestone fissures the total phosphorus content of the surface soil was higher than that of the subsurface soil but the total potassium content was lower there was no significant difference among different soil layers near surface fissures are a good place to promote vegetation restoration projects because they provide good soil structure and nutritional conditions for plant growth

vertebrate biostratigraphy and biochronology of the upper paleozoic dunkard group pennsylvania west virginia ohio usa abstract the dunkard group is 343 m of mostly clastic rocks exposed in pennsylvania ohio and west virginia usa correlation of the dunkard group to the pennsylvanian permian boundary has long been debated fossil vertebrates from the dunkard group include paleoniscoids dipnoans a rhipidistian crossopterygian selachians lepospondyl and temnospondyl amphibians diadectomorphs primitive amniotes eureptiles and eupelycosaurs these vertebrates represent two biostratigraphically distinct assemblages one from the waynesburg and washington formations and the other from the overlying greene formation comparison of the dunkard vertebrate biostratigraphy to a vertebrate biostratigraphy and biochronology developed in new mexico texas allows correlation to the coyotean latest virgilian middle wolfcampian and seymouran late wolfcampian early leonardian land vertebrate faunachrons tetrapod taxa from the waynesburg and washington formations include edops and protorothyris coyotean index taxa as well as the characteristic coyotean taxa trimerorhachis diadectes edaphosaurus and dimetrodon significantly these dunkard taxa are best known from the archer city formation in texas which is late coyotean middle wolfcampian the greene formation contains the eupelycosaur ctenospondylus an index taxon of the seymouran land vertebrate faunachron dunkard xenacanth selachians support the tetrapod based correlations vertebrate biochronology thus indicates that the waynesburg and washington formations are late coyotean whereas the greene formation is seymouran therefore vertebrate biostratigraphy and biochronology indicate that the entire dunkard group is early permian and likely straddles the wolfcampian leonardian boundary

cyclic changes in pennsylvanian paleoclimate and effects on floristic dynamics in tropical pangaea abstract wetland floras narrowly define perceptions of pennsylvanian tropical ecosystems the so called coal age such wetlands reflect humid to perhumid climate leading to characterizations of pennsylvanian tropics as everwet swampy these views are biased by the high preservation potential of wetlands sedimentation patterns paleosols and fossil floras indicate the presence of vegetation tolerant of subhumid to dry subhumid perhaps semi arid climate in basins between peat formation times understanding the significance of this seasonally dry vegetation has suffered from conceptual and terminological confusion a clearer view has emerged as models for framing the data have improved basinal floras typical of seasonally dry conditions relatively low soil moisture regimes are well documented but mainly from isolated deposits some of the earliest dominated by primitive pteridosperms flozfern floras occur in clastic rocks between european early pennsylvanian coal beds later early pennsylvanian fern cordaitalean vegetation different from coal floras is preserved in marine goniatite bullions conifers are first suggested by late mississippian potoniesporites pollen about the same time in north america broadleaf foliage lesleya and megalopteris occur in basin margin settings on drought prone limestone substrates the best known xeromorphic floras found between coal beds appear in the middle through late pennsylvanian containing conifers cordaitaleans and pteridosperms the middle pennsylvanian appearances of this flora are mainly allochthonous though parautochthonous occurrences have been reported parautochthonous assemblages are mostly late pennsylvanian the conifer flora became dominant in western and central pangaean equatorial lowlands in earliest permian location of the humid perhumid wetland flora during periods of relative dryness though rarely discussed is as or more perplexing than the spatial location of seasonally dry floras through time wetland plants had few migratory options and possibly survived in small refugia within and outside of basins coupled oscillations in climate sea level and vegetation were driven most likely by glacial interglacial fluctuations perhaps controlled by orbital cyclicity

porosity estimation and geometric characterization of fractured and karstified carbonate rocks using gpr data in the salitre formation brazil three dimensional distribution of karstic zones and estimated porosity were obtained in fractured carbonate units of the salitre formation brazil from gpr data low amplitude shadow gpr zones could be associated with mineral dissolution halos that developed around fractures and bedding planes gpr volumes show a 3d mazelike geometry of the vertical karstified carbonate zones similar to the set of passages controlled by n s and e w oriented fracture systems observed on the surface in unmanned aerial vehicle images measurements in plug samples indicate that the mineral dissolution caused bulk density and dielectric permittivity decline and incipient increase in porosity from 0 95 to 1 01 these changes in the rock properties affect the em impedance contrasts between carbonate bedding causing loss of the reflected gpr signal the correlation between dielectric permittivity and porosity could be analyzed using the complex refractive index model crim which is used to convert the relative dielectric permittivity into porosity the crim porosities are somewhat lower than plug sample porosities due to different estimation methodologies and measurement scales however the fact that porosity is slightly higher in the dissolved carbonates was maintained in addition gpr amplitude and frequency instantaneous attributes were used to estimate spatial variability in porosity throughout the whole gpr data volume the crossplot of these two gpr attributes show that altered zones generally cluster in narrow ranges of instantaneous gpr amplitude and in broad range of instantaneous gpr frequency assuming empirical correlation between physical properties and gpr attributes two predicted porosity volumes were established for the karstified carbonates in the studied area

holocene flood plain soil formation in the southern lower mississippi valley implications for interpreting alluvial paleosols holocene mississippi river flood plain soils in central louisiana provide important insights on alluvial pedogenesis in an aggradational setting insights that are useful for interpreting alluvial paleosols the flood plain soils are younger than ca 5400 yr b p and are grouped into two categories 1 meander belt and 2 backswamp soils meander belt soils are entisols inceptisols and alfisols developed on point bar ridges and natural levee crests they consist of 3 5 m thick brown silty and sandy moderately well drained profiles with multiple parent materials common yellow brown and gray mottles and a few iron and calcite nodules backswamp soils are vertisols formed in flood plain depressions away from active and abandoned mississippi river channels and consist of up to 10 m thick gray clayey poorly drained profiles that have abundant yellow brown mottles iron and calcite nodules gypsum accumulations and slickensides the thickness of the soils and the presence of multiple parent materials show that as the flood plain aggrades concurrent or alternating episodes of sedimentation and pedogenesis produce cumulative profiles profile thickness is more closely related to sediment accumulation rates than to the depth of chemical weathering and the cumulative nature of the soils explains the difficulty of recognizing discrete paleosol profiles in many ancient alluvial deposits comparisons of soils formed on the three youngest holocene mississippi river meander belts saucier and snead 1989 show that the soils record episodes of meander belt growth abandonment and relocation meander belt 1 soils form as the active meander belt develops and consist of either vertically stacked entisols or a single inceptisol the soils contain few calcite nodules and form over intervals of a few hundred years meander belt 2 soils are alfisols lack free carbonates and form over intervals of a few thousand years following meander belt abandonment and soil leaching meander belt 3 soils are alfisols or vertisols that contain common calcite nodules and the profiles are developed in 1 to 2 m of backswamp mud that overlies meander belt silt and sand the mud inhibits profile leaching and leads to poor drainage and calcite precipitation this change in soil hydrology complicates interpretations of the effects of time on meander belt soil development backswamp soils are strongly influenced by seasonal episodes of soil wetting and drying as demonstrated by the gray colors and the abundance of mottles nodules and slickensides in the soils the distribution of calcite nodules in the backswamp and meander belt soils is more closely related to seasonal water table position than to mean annual precipitation which suggests that not all calcic paleosols in ancient alluvial deposits represent semiarid or arid climates slickensides attest to seasonal rainfall but the composition of the backswamp soils primarily reflects source area lithology and depositional influences rather than the effects of chemical weathering in general these soils provide an incomplete record of the humid subtropical climate of louisiana although short term sediment accumulation rates decrease away from mississippi river channels the backswamp soils are not better developed i e more mature than the meander belt soils because poor drainage and slow but continuous sedimentation inhibits weathering collectively these observations suggest that flood plain soils that developed in aggradational settings such as that of the mississippi river flood plain are best suited for interpreting depositional and hydrologic histories of ancient alluvial deposits rather than paleoclimates

high sulfate concentrations in limestone springs an important factor in conduit initiation major ion concentrations in 404 springs in carbonate strata were found to exhibit a wide range in sulfate values sulfate concentrations are often much larger than would be expected from the analysis of samples from surface outcrops springs in the sierra madre oriental mexico the rocky mountains front range canada and the peak district england show similarities in sulfate concentration and in spatial distribution springs with high sulfate concentrations are found close to base level and are thermal springs with low sulfate concentration are found at higher elevations above base level and are not thermal there is a direct relationship between sulfate concentration and spring temperature and an inverse relationship with discharge the results from the three areas described support a model of local and regional flow patterns with deep regional flow providing the warm sulfate rich water the initial fracture porosity development in these aquifers may owe as much to the removal of sulfur minerals as to the removal of carbonate minerals high sulfate values are frequently found in carbonate aquifers so this model may be of widespread applicability

new weathering index improves paleorainfall estimates from vertisols vertisols are clayey shrink swell soils that are widely recognized in the rock record thus generating the need to better understand the dynamics of elemental concentrations on the development of weathering indexes for climate interpretations we assessed the weathering performance of the four major base forming oxides cao mgo na 2 o k 2 o along a modern vertisol climosequence spanning a strong precipitation gradient and discovered that the concentration of bulk soil cao and mgo yields the strongest correlation to mean annual precipitation map based on this fi nding we introduce the calmag weathering index defi ned as al 2 o 3 al 2 o 3 cao mgo 100 which improves rainfall estimates for vertisols relative to the wellestablished cia k chemical index of alteration minus potassium weathering index rather than documenting the hydrolysis of weatherable minerals common in many other soil orders in vertisols calmag principally tracks the fl ux of calcium and magnesium sourced from calcium carbonate detrital clay and exchangeable ca 2 and mg 2 application to two mesozoic paleosols reveals that in drier climates cia k yields higher map estimates than calmag but that the reverse is true in wetter climates this work improves paleorainfall estimates from vertisols and suggests that a family of weathering indexes is needed for different paleosol types

geology and tectonic evolution of the palaeoproterozoic bryah padbury and yerrida basins formerly glengarry basin western australia implications for the history of the south central capricorn orogen abstract the palaeoproterozoic bryah padbury and yerrida basins are situated along the northwestern margin of the archaean yilgarn craton central western australia these basins form part of the capricorn orogen which developed between 2 0 and 1 8 ga as a result of the collision between the archaean pilbara and yilgarn cratons the bryah padbury and yerrida basins which at the present day cover a total area of ca 20 000 km2 were formerly considered as one geological entity the glengarry basin these three basins are characterized by distinct stratigraphy igneous activity structural and metamorphic history and mineral deposit types igneous activity only affected the bryah and yerrida basins with voluminous eruptions of tholeiitic magma in the bryah basin tholeiitic volcanic rocks are mg rich and have mixed morb to oceanic island chemical signatures but with a boninitic subduction related component in the yerrida basin tholeiites are fe rich and have chemical signatures that suggest a mixed tectonic environment ranging from oceanic to continental it is considered possible that this tholeiitic magmatism is related to a mantle plume two models for the tectonic evolution of the bryah padbury and yerrida basins are proposed 1 the bryah and yerrida basins were formed in a back arc setting whilst the padbury basin developed as a retro arc foreland basin over the bryah basin and or 2 strike slip transtension during and following the pilbara yilgarn collision created the bryah and yerrida strike slip pull apart basins a change in regional stress regime resulted in the inversion of the basins and the development of a foreland basin in the northwest padbury basin

a review of the stratigraphy and stratigraphic nomenclature of the dunkard group in west virginia and pennsylvania usa abstract dunkard group strata the youngest paleozoic rocks in the appalachian basin extend from the base or top of the waynesburg coal varying among neighboring state geological surveys to the highest exposures geologic investigation and mapping of the dunkard group began with the first pennsylvania geological survey in the 1830s but poor exposure exposure of only limited stratigraphic intervals and lack of significant economic commodities have hampered stratigraphic studies maximum thicknesses in excess of 335 m 1100 ft are found beneath the highest ridges along the synclinorium axis near wileyville west virginia and windy gap pennsylvania and the stratigraphic correlation of these sites is shown with composite sections constructed from core records and measured sections distinct facies provinces are documented in the dunkard group from south to north interpreted as 1 upper fluvial plain 2 lower fluvial plain and 3 fluvial lacustrine deltaic plain this spatial array of facies provinces is illustrated by a cross section through dunkard group and underlying monongahela group strata based on drillers and geologists core logs strata in the upper fluvial plain are cyclic sequences of red green and gray nonfissile mudstone and claystone paleosols exhibiting vertic features red green and gray fissile shale and gray and green sandstone coal and limestone are rare although abundant calcareous material is present as nodules and cement in contrast the fluvial lacustrine deltaic plain cycles are comprised of coal and nonmarine limestone fewer fluvial shale and sandstone units and only rare redbeds the lower fluvial plain cycles exhibit a transition between the other two provinces containing coal and nonmarine limestone as well as significant fluvial units and redbeds coal beds in the dunkard group are best developed in the fluvial lacustrine deltaic plain but are generally thin and low in quality stratigraphically extensive laterally continuous road cuts and numerous subsurface exploration records particularly long continuous cores targeting coal beds beneath the dunkard group now aid in better understanding the stratigraphy of the dunkard group and will aid in future investigations of these rocks

the conduit seal system of hypogene karst in neoproterozoic carbonates in northeastern brazil abstract karst processes are of primary importance for the generation of secondary porosity and permeability in carbonate reservoirs and aquifers the topic investigated in this study are the effects of the facies and stratigraphy of different layers on the vertical distribution of solution cavities formed by hypogenic fluids in a carbonate sequence this work uses the toca da boa vista tbv and toca da barriguda tbr caves as analogues of carbonate reservoirs that are affected by karst processes these are two different caves that are 400 m apart but exhibit the same geological characteristics and occur in the neoproterozoic salitre formation 700 560 ma sao francisco craton brazil these caves form the longest cave system in south america with conduits of lengths 107 km tbv and 34 km tbr previous studies of these caves indicated their hypogene origins these caves developed by an ascending fluid flow mainly along fractures the fluid then flowed laterally and was influenced by the following five stratigraphic units from the bottom to the top 1 cross bedded oolitic grainstone 2 fine grainstone with chert nodules 3 microbial carbonate 4 interbedded fine siliciclastics and marls and 5 crystalline grainstone interfingered with chert layers units 4 and 5 formed a stratigraphic seal units 1 2 and 3 below the seal supported the lateral redistribution of flow and respective conduit development therefore these units exhibit a high degree of karstification veins related to the first fluid phases that compose a hydrothermal mineral assemblage cut across these units we conclude that stratigraphic control is important for determining the architecture of the hypogenic cave system at the local scale

shrimp u pb geochronology of magmatism and thermal events in the archaean marymia inlier central western australia zircons from porphyry and granitoid samples collected in and around the marymia gold mine in the marymia inlier western australia record a complex history the results of u pb studies confirm that the plutonic well greenstone belt and the surrounding granitoid envelope including a 2 721 6 ma intrusion represent an archaean terrain which was intruded by high level felsic to intermediate porphyries at 2 694 7 ma and potentially also at 2 660 4 ma zircon xenocrysts ca 3 35 2 93 and 2 74 ga indicate that there was older crust within or below the greenstone belt at the time of porphyry emplacement zircons from the granitoid envelope and intrusions within the greenstone belt record subsequent metamorphism and or hydrothermal activity coeval with magmatism in the late archaean ca 2 66 2 63 ga and peak metamorphism magmatism and gold mineralisation in the yilgarn block a later period of metamorphism and hydrothermal activity at ca 1 72 ga is coeval with orogenesis in the southern capricorn orogen both the late archaean and palaeoproterozoic thermal events have altered zircons redistributed trace elements and caused zircon recrystallisation which is distinctive in its isotope chemistry in particular th u ratios 1 and morphology e g homogeneous in transmitted light and back scattered electron images but sector zoned in cathodoluminescence

age and origin of granitic rocks in the kalgoorlie norseman region of western australia implications for the origin of archaean crust three granites from the norseman area at stennet rocks buldania rocks and east of lake johnston have u pb zircon ages of 2691 8 95 c l 2689 22 and 2661 8 ma respectively one stennet rocks contains 3100 3200 ma cores providing support for oversby s 1975 argument that all three plutons were derived by anatexis of much older basement common leads within the zircons show evidence of having been derived from within the rock and represent mixtures of initial rock leads and radiogenic leads the unusually 208pb rich compositions of the common leads suggest the breakdown of a th rich phase perhaps uranothorite as a major contributor to the radiogenic component available zircon geochemical and isotopic data are used to develop a two stage model for archaean crustal development in this region with formation of primitive crust of broadly andesitic composition from depleted mantle or basalt beginning at 3400 ma followed by extensive thermal reworking and possibly continued growth over the period 3000 3300 ma in the second stage at 2700 ma anatexis resulted in large scale intra crustal differentiation giving a thick upper granitic layer and a lower crust residual from anatexis it is this second major thermal event that is recorded by most geochronometers implicit in the andesitic crustal growth model is that because the sm nd and rb sr ratios of newly formed archaean crust are close to mantle values this process is transparent to the sm nd and rb sr isotope systems until recycling of incompatible element rich sediment becomes important following the late archaean production of a wide spread differentiated upper crust

an overview and interpretation of autocyclic and allocyclic processes and the accumulation of strata during the pennsylvanian permian transition in the central appalachian basin usa abstract autocyclic and allocyclic processes controlled the lithostratigraphy of strata that accumulated in the central appalachian foreland basin during the pennsylvanian and the transition to the permian the transition strata from bottom to top include the late pennsylvanian pittsburgh and uniontown formations of the monongahela group the waynesburg and washington formations of the dunkard group and the permian greene formation of the dunkard variations in the amount of precipitation were the predominant allocyclic control on stratigraphic variations in terrestrial organic productivity lacustrine base levels basin scale weathering water table and pedogenesis sediment supply and sedimentary geochemistry tectonic subsidence controlled accommodation space and basin configuration eustasy had little or no effect on the stratigraphy of strata deposited in this continental basin during the pennsylvanian permian transition autocyclic processes were the predominant spatial control on architecture of alluvial plain aggradation paleosols delineating regional unconformities show a gradual upward transition from kaolinitic underclay paleosols indicative of a humid climate in the late pennsylvanian monongahela group to petrocalcic paleosols indicative of a dry subhumid to semiarid climate during deposition of dunkard strata as in the monongahela group the dunkard group waynesburg and washington formations contain multi bedded nonmarine lacustrine limestones with subareal exposure features these limestones grade laterally into petrocalcic paleo vertisols in the up dip alluvial plain subareal exposure features are uncommon in centimeter scale micritic limestones in the permian greene formation equivalent up dip paleosols have been lost to erosion coal bed continuity thickness and quality also decrease up section from the very thick m and laterally continuous pittsburgh coal at the base of the monongahela group to thin cm scale and laterally discontinuous coal beds that unconformably overlie the paleosol underclay limestone complexes in the greene formation lacustrine shales and impure wacke fluvio lacustrine sandstones commonly with a weak pedogenic overprint generally overlie coal beds during accumulation of monongahela and dunkard mdg strata within the basin center unconformities at the tops of regional paleosols overlain by lacustrine strata suggest allocyclic induced repeated rise and fall of lacustrine conditions in a lacustrine fan delta complex analogous to the okavango basin and fan in namibia southern africa and or the pantanal in southern brazil during maximum lake levels progradation of fluvio deltaic systems resulted in laminated shale conformably overlain by dark shale and flat bottomed distributary mouth bar siltstones and sandstones prograding distributaries and or fluvial channels subsequently incised the flat bottom mouth bar sands where basin margin strata are preserved south of the basin center depositional environments consist of aggrading alluvial plain sequences with paleosols fluvial channel sands and flood plain deposits anastomosing fluvial systems prograded across a low gradient 1 ft mile 20 cm km alluvial plain into the basin center a weak pedogenic overprint marked by ubiquitous root penetrations occurs throughout most basin centered fluvial deposits the subtle but continuous decline in the repetition of cyclic lithostratigraphy up section in the mdg particularly in the greene formation appears to be the result of a 10 myr climate transition from the humid to dry subhumid climate cycles of the late pennsylvanian to the equable semiarid to arid climate of the middle permian in north america cyclothems common in pennsylvanian strata become less distinct up section in the dunkard because of decreasing development of underclays coal and limestone this 30 myr period of transition from the humid pennsylvanian to the arid permian has been referred to as the dyassic period

role of rock dip angle in runoff and soil erosion processes on dip anti dip slopes in a karst trough valley abstract due to the great difficulty of monitoring surface and underground runoff and sediment yield directly the surface and underground hydrological processes associated with soil leakage loss in karst trough valleys remain unknown the objective of this study was to analyse the role of the rock dip angle in the water and soil leakage loss processes to assess the characteristics of surface and underground runoff and soil erosion and to investigate their conversion relationships using rainfall experiments the results showed the following i at a steep rock dip angle 60 the underground runoff yield had a shorter stabilization time than the surface runoff yield and that the underground runoff coefficient of the dip slope exceeded 0 5 ii the surface sediment yield could be divided into the suspended load and the bed load and the underground sediment yield included only the suspended load on the anti dip slope the surface erosion modulus was 0 83 2 50 times the underground erosion modulus iii the surface and underground cumulative runoff was linearly correlated with the cumulative sediment yield the rock dip angle had a significant quadratic relationship with the surface and underground runoff and sediment yield these results improve the understanding of the surface underground runoff and soil erosion processes and have significance for preventing water and soil leakage loss on the slopes of karst trough valleys

a paleopedologic and ichnologic perspective of the terrestrial pennsylvanian landscape in the distal appalachian basin u s a abstract the conemaugh group of southeastern ohio contains numerous ichnofossil bearing paleosols in both the lower glenshaw and upper casselman formations which were deposited during the kasimovian and gzhelian 305 301 ma along the distal edge of the appalachian basin this study examined the small scale twenty four stratigraphic sections were measured from ten sites in athens county ohio from which thirty paleosols were identified and described detailed field descriptions allowed differentiation of four distinct pedotypes one in the glenshaw formation and three in the casselman formation the glenshaw pedotype gpt is a vertisol that formed on a proximal to distal floodplain the three casselman pedotypes represent entisols inceptisols cpti alfisols cptii and vertisols cptiii all four types contain evidence of alteration by post pedogenic processes such as drowning by migrating river channels or rising sea level or a gradual transition from one alluvial subenvironment to another as a result of channel migration eight morphologically distinct ichnofossils were observed in the conemaugh group paleosols including three types of rhizoliths lined and unlined vertical to subhorizontal shafts chambers sinuous burrows with and without bioglyphs and general burrow mottling these ichnofossils occur in distinct assemblages that form unique ichnocoenoses within each of the four pedotypes they were produced by various plants arthropod detritivores carnivores and herbivores as well as amphibians and early reptiles as temporary to permanent members of complex soil ecosystems pedogenic properties combined with ichnofossil diversity abundance and distribution increase the understanding of the complexity of late pennsylvanian soil ecosystems and provide details on the small scale variations in paleosols due to short term autogenic changes in alluvial environments although broad regional studies across 10 2 10 3 of kilometers are important small scale variations over less than 1 km are needed to understand the effects of localized changes in hydrology topography organisms and sedimentary processes on soil formation and soil biodiversity consideration of these types of localized studies is also vital when attempting to interpret regional to global scale aspects of environment such as climate from paleosols

significance of different modes of rhizolith preservation to interpreting paleoenvironmental and paleohydrologic settings examples from paleogene paleosols bighorn basin wyoming u s a abstract different modes of preservation of root traces rhizoliths provide information on soil moisture regimes in alluvial paleosols in the paleogene fort union and willwood formations of the bighorn basin wyoming u s a this paper links different styles of rhizolith preservation to paleosols whose other pedogenic attributes provide information on ancient soil drainage consequently the paleodrainage significance of different rhizolith preservation patterns is established more confidently rhizoliths consisting of elongate gray mottles rhizohaloes with red rims are common in relatively well drained red paleosols the gray zones are depleted of iron fe whereas the color of the rims indicates hematite accumulation these features are typical of surface water gley processes that caused fe and manganese mn to move from the root channel outward to the soil matrix calcareous rhizocretions either calcareous tubular concretions or micro accumulations of carbonate within gray rhizotubules are also common in moderately well drained red paleosols more poorly drained purple paleosols also have rhizoliths consisting of fe depletion zones however the rhizohaloes are surrounded by yellow brown goethite rims rather than red hematitic rims in many paleosols the red and yellow brown accumulation rims were partly removed by continued depletion producing abundant irregular shaped mottles the nature of the rhizohalo and the color of the fe oxide rim provide information about the intensity of gleying that a paleosol underwent the poorly drained paleosols also show rhizoliths preserved as goethite accumulations contained within gray depletion zones indicating movement of reduced fe from the matrix towards the root channel probably as a result of groundwater gley processes the goethite accumulations are intermingled locally with lignite representing preservation of the root organic material some rhizoliths are preserved as tube shaped concentrations of small 0 1 0 2 mm diameter black spheres whose color indicates a mix of mn and fe oxides these are most common in paleosols with low chroma gray matrix colors indicating very poor drainage the very poorly drained paleosols also show rhizoliths preserved in jarosite which is an oxidation product of pyrite careful observational and geochemical analysis of rhizoliths which are common in continental deposits can help produce a clearer and more thorough interpretation of ancient drainage conditions information about degree of ancient soil wetness or moisture is important for understanding past climatic conditions and for reconstructing terrestrial paleolandscapes

callipterid peltasperms of the dunkard group central appalachian basin abstract the dunkard group is the youngest late paleozoic rock unit in the central appalachian basin its age however remains controversial in its southern and western two thirds the dunkard is comprised largely of red beds sandstone and siltstone channel deposits and paleosols in its thickest most northerly exposures in southwestern pennsylvania northern west virginia and east central ohio much of the lower part of the unit is composed of coals non marine limestones and gray often calcareous paleosols age dating is confounded by the non marine nature of the deposit and by the lack of dateable volcanic ash beds dunkard fossils include plants vertebrates and both aquatic and terrestrial invertebrates most of the fossil groups point to an age very close to if not including the pennsylvanian permian boundary though the exact position of that boundary is uncertain callipterids make their first appearance in the dunkard flora in the middle of the washington formation and continue into the greene formation but in different beds from those containing wetland floral elements publication of these plants in the permian flora of fontaine and white 1880 created an immediate controversy about the age of the unit because callipteris conferta now autunia conferta was at the time considered to be an index fossil for the base of the permian subsequent collecting has revealed these callipterds to comprise four species a conferta autunia naumannii lodevia oxydata and rhachiphyllum schenkii callipterids and the conifers with which they are sometimes associated are typically found in seasonally dry equatorial environments and most likely constitute an environmentally controlled biofacies this biofacies is not well known resulting in limited biostratigraphic utility

the narryer gneiss complex of the yilgarn block western australia a segment of archaean lower crust uplifted during proterozoic orogeny the narryer gneiss complex of the yilgarn block is a key segment of the western australian precambrian shield it is a regional granulite facies terrain comprised of predominantly quartzo feldspathic gneisses derived from granitic intrusions c 3 6 3 4 ga old granulite facies metamorphism occurred c 3 3 ga ago and conditions of 750 850 c and 7 10 kbar are estimated for the mukalo creek area mca near errabiddy in the north the p t path of the mca has been derived from metamorphic assemblages in younger rocks that intruded the gneisses during at least three subsequent events and this path is supported by reaction coronas in the older gneisses there is no evidence for uplift immediately following peak metamorphism of the mca and a period of isobaric cooling is inferred from the pressures recorded in younger rocks pressures and temperatures estimated from metadolerites which intruded the older gneisses during granite greenstone tectonism at about 2 6 ga and during early proterozoic thrusting show that the errabiddy area remained in the lower crust although it was probably reheated during the younger events isothermal uplift to upper crustal levels occurred at c 1 6 ga ago and was followed by further deformation and patchy retrogression of high grade assemblages the effects of younger deformation cooling and reheating can be discerned in the older gneisses but as there has been no pervasive deformation or rehydration the minerals and microstructures formed during early archaean granulite facies metamorphism for the most part are retained the mca remained in the lower crust for about 1700 ma following peak metamorphism and some event unrelated to the original metamorphism was required to exhume it uplift occurred during development of the capricorn orogen when some 30 35 km were added to the crust beneath the errabiddy area the recognition of early proterozoic thrusting plus crustal thickening suggests that the capricorn orogen is a belt of regional compression which resulted from convergence of the yilgarn and pilbara cratons

hypogenic contribution to speleogenesis in a predominant epigenic karst system a case study from the venetian alps italy abstract buso della rana and buso della pisatela are two karstic caves located in north east italy they are part of the same karst system and are developed in the castelgomberto calcarenitic marine sediments which were deposited in a shallow caribbean type sea during the eocene the buso della rana pisatela system developed mostly at the contact between the castelgomberto calcarenite and underlying volcanic rocks the system of caves is 37 km long and has only three entrances two of which are semi artificial the overlying karst plateau is not directly connected to the buso della rana pisatela system and with the exception of one deep abyss exhibits a rather poorly developed karst this is unexpected considering the presence at depth of such a large and long cave gypsum caso 4 2h 2 o has locally been observed on the walls of the buso della pisatela cave energy dispersive x ray spectroscopy eds performed with a scanning electron microscope sem reveals the presence of sulfur bearing minerals within the host rock gypsum was formed by oxidation of these minerals as indicated by negative 34 s values the oxidation of sulfide minerals forms a sulfuric acid solution that dissolves the castelgomberto calcarenite and once it is oversaturated in calcium precipitates as gypsum the lack of well developed karst on top of the plateau and the analyses suggest that the formation mechanisms for the buso della rana pisatela system differ from classical epigenic speleogenesis the pyrite effect has been recognized in other caves and described in literature in our case pyrite is responsible of two hypo speleogenetic processes i the dissolution of a portion of the host rock and ii the enlargement of the karst voids as a consequence of the haloclastic effect

the early permian age of the dunkard group appalachian basin u s a based on spiloblattinid insect biostratigraphy abstract the dunkard group of the appalachian basin ohio pennsylvania west virginia is a 340 m thick sequence of primarily fluvial and lacustrine deposits that contain a diverse fossil record including a blattoid insect forewing identified as sysciophlebia balteata scudder this wing originates from the cassville shale in the waynesburg formation at the very base of the dunkard group s balteata is a zone species of a late paleozoic spiloblattinid insect zonation that is calibrated by the co occurrence of spiloblattinid zone species with conodont and fusulinid zone species in kasimovian to early asselian mixed marine continental profiles of new mexico usa and the donets basin in the ukraine as well as by the isotopic ages of volcanic intrusions into the late stephanian gzhelian strata of the saale basin in germany the base of the zone underlying the s balteata zone is defined by the fad of sysciophlebia ilfeldensis in the late gzhelian and has an upper limit lad of early to middle asselian an early or middle asselian to earliest sakmarian range of both the subzones of the s balteata zone can be inferred given that the mean duration of a spiloblattinid insect zone is about 1 5 to 2 ma the upper limit of the s balteata zone is early sakmarian hence the base of the dunkard group should be maximally of early asselian or minimally of earliest sakmarian age

hypogenic origin geologic controls and functional organization of a giant cave system in precambrian carbonates brazil abstract this study is focused on speleogenesis of the toca da boa vista tbv and toca da barriguda tbr the longest caves in south america occurring in the neoproterozoic salitre formation in the sao francisco craton ne brazil we employ a multidisciplinary approach integrating detailed speleomorphogenetic lithostratigraphic and geological structure studies in order to reveal the origin of the caves their functional organization and geologic controls on their development the caves developed in deep seated confined conditions by rising flow the overall fields of passages of tbv and tbr caves represent a speleogenetically exploited large ne sw trending fracture corridor associated with a major thrust this corridor vertically extends across the salitre formation allowing the rise of deep fluids in the overall ascending flow system the formation of the cave pattern was controlled by a system of sub parallel anticlines and troughs with nne ssw dominant orientation and by vertical and lateral heterogeneities in fracture distribution three cave stratigraphic stories reflect the actual hydrostratigraphy during the main phase of speleogenesis cavities at different stories are distinct in morphology and functioning the gross tree dimensional pattern of the system is effectively organized to conduct rising flow in deep seated confined conditions cavities in the lower story developed as recharge components to the system a laterally extensive conduit network in the middle story formed because the vertical flow from numerous recharge points has been redirected laterally along the highly conductive unit occurring below the major seal a scarcely fractured unit rift like and shaft like conduits in the upper story developed along fracture controlled outflow paths breaching the integrity of the major seal and served as outlets for the cave system the cave system represents a series of vertically organized functionally largely independent clusters of cavities developed within individual ascending flow cells lateral integration of clusters occurred due to hydrodynamic interaction between the flow cells in course of speleogenetic evolution and change of boundary conditions the main speleogenetic phase during which the gross cave pattern has been established and the caves acquired most of their volume was likely related to rise of deep fluids at about 520 ma or associated with rifting and the pangea break up in triassic cretaceous this study highlights the importance of speleogenetic studies for interpreting porosity and permeability features in carbonate reservoirs

upper proterozoic carbonate stratigraphy diagenesis and stromatolitic phosphorite formation irece basin bahia brazil abstract carbonate strata of the una group represent late proterozoic platform sedimentation in the irece basin of east central brazil the irece basin contains a basal siliciclastic sequence the bebedouro formation composed of diamictites dominantly of glacial origin that is overlain by lacustrine carbonate sediments these are succeeded by the una group a marine carbonate sequence that totals several hundred meters thick the marine units consist of a basal laminated limestone and dolomitic limestone sequence that grades upward into dolostone and cherty dolostone a middle sequence dominated by gray argillaceous limestones shales and siltstones and an upper sequence of black organic rich lime grainstones stratabound phosphate and sulfide rich units are present within a 50 m thick tid l flat sequence of dolomitic limestone and cherty dolostone in the lower una group shallow water sedimentary structures include stromatolitic laminae columnar stromatolites mudcracks teepee structures collapse breccias length slow quartz nodules and other pseudomorphs after evaporitic sulfates conventional petrography supported by cathodoluminescence and scanning electron microscopy of the carbonate strata reveals a complex diagenetic history representing four major diagenetic environments marine reflux meteoric and burial carbon and oxygen isotope analyses of diagenetic carbonate generations yield distinct populations that support the environmental interpretations concentrations of fine grained carbonate fluorapatite are present in stromatolitic carbonate units in the irece lapao area three types of primary phosphate concentrations have been defined columnar stromatolitic laminar stromatolitic and intraclastic the presence of resedimented phosphatic clasts and of phosphatic units interbedded with barren dolostones suggest that the formation of stromatolitic phosphorite was an early diagenetic process carbon and oxygen isotope data for calcite dolomite and carbonate fluorapatite as well as sulfur isotope data from sulfates and sulfides suggest the presence of an anoxic environment during the formation of the irece phosphorites postglacial enrichment of the basin waters in phosphate is considered to be a critical aspect of phosphatizat on bacterial degradation of organic matter in the stromatolites probably was responsible for local phosphate enrichment of pore waters and resulted in concentration of carbonate fluorapatite by direct precipitation or by replacement of calcium carbonate

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

terrestrial evidence for the lilliput effect across the cretaceous paleogene k pg boundary abstract recent research has demonstrated that the lilliput effect reduction of body size in biota associated with the aftermath of mass extinctions affected all trophic levels in the marine realm following the cretaceous paleogene k pg event however it is unclear if this size change was strictly a marine signal or a global phenomenon that also affected continental ecosystems herein we present the results of an ichnological proxy for body size of soil dwelling insects across the k pg boundary in big bend national park texas u s a quantitative efforts focused on naktodemasis bowni which are characterized as unbranching burrows composed of ellipsoidal packets of backfill menisci these traces were likely produced by beetle larvae or cicada nymphs based on previous comparison with structures generated in modern soils and laboratory experiments as an approximation for the body size of the subterranean insects this dataset indicates that a smaller n bowni diameter dn is statistically correlated

controls on the genesis sedimentary architecture and preservation potential of dryland alluvial successions in stable continental interiors insights from the incising modder river south africa abstract interpretations of the allogenic and autogenic controls on dryland alluvial successions are commonly hampered by incomplete knowledge of the sedimentology of modern dryland river floodplains in part because of the limited subsurface sediment exposures available in typically stable or aggrading riverine settings along many valleys in the south african interior however river incision and associated formation of dongas gullies and badland type settings provides extensive exposures of cenozoic alluvial successions which enable assessment of the controls on their genesis sedimentary architecture and preservation potential this paper focuses on the incised modder river at erfkroon free state located 1480 km river distance inland from the atlantic ocean at erfkroon numerous dongas have formed in an 15 m thick alluvial succession deposited within a narrow 500 m valley carved predominantly in erodible fine grained sedimentary rocks shales facies associations include channel deposits that vary in texture from sandy gravel to silty sand and overbank deposits consisting predominantly of sandy mud to muddy sand that have varying degrees of pedogenic overprinting younger deposits are stacked upon crosscut or onlap older deposits indicating a complex history of cut and fill changing assemblages of associated fossil fauna and archaeological artifacts luminescence ages and paleosol characteristics demonstrate net sediment accumulation over at least the last 42 ka under humid to arid climatic conditions by contrast the present day situation of deep channel and donga incision into bedrock appears to represent a new phase of sediment evacuation and valley deepening comparison with other incising dryland rivers in the south african interior suggests that 1 while phases of cut and fill are driven largely by climatic fluctuations major phases of incision into bedrock are controlled by breaching of downstream resistant rock barriers 2 long term sediment preservation is limited in narrow valleys that are subject to extended periods of base level stability followed by episodic major incisional phases but is greater along broader valleys where rivers are undergoing lateral migration and more progressive long term incision study of incising rivers such as the modder can yield important insights into the controls on alluvial successions in stable continental interiors beyond the range of sea level changes which may help with the interpretation of inland alluvial valleys preserved in the geological record