models of rock varnish formation constrained by high resolution transmission electron microscopy nanometre scale transmission electron microscope imagery of manganiferous rock varnishes from death valley california peru antarctica and hawaii confirms prior infrared mineralogy studies the building blocks of rock varnish are clay minerals that are cemented to the rock by oxyhydroxides of manganese and iron rock varnish is layered on the scale of nanometres with the basic structure defined by the subparallel alignment of detrital clay minerals although only a few examples of bacteria were found possible cell wall encrustations are ubiquitous and aligned with the clay minerals mn fe oxides appear to be mobilized from bacterial casts and then reprecipitate on clay minerals that weather into monolayers these observations have implications for varnish dating and palaeoenvironmental techniques k ar and uranium series dating of rock varnish oxides can only yield minimum ages however this small spatial scale of mobilization would not alter the signal from micron scale microchemical laminations

tectonic and paleoclimatic significance of a prominent upper pennsylvanian virgilian stephanian weathering profile iowa and nebraska usa abstract a virgilian stephanian weathering profile up to 4 m deep containing a paleosol basal rakes creek paleosol in the basal mudstone of the rakes creek member and karstified marine sediments in the ost kenosha and avoca members below is restricted to southeastern nebraska specifically the weeping water valley and the missouri river valley bluffs of adjacent easternmost iowa this weathering profile informally referred to as the weeping water weathering profile disappears farther eastward into the shallow forest city basin in southwestern iowa weeping water weathering profile features are prominent in comparison to other midcontinent pennsylvanian subaerial exposure surfaces indicating prolonged subaerial exposure relatively high elevation and a marked drop in water table along the nemaha uplift in southeastern nebraska eastward on the margin of the forest city basin the basal rakes creek paleosol and underlying karst are thinner and relatively poorly developed paleosol characteristics indicate formation on lower landscape positions comparative pedology the contrasting of paleosol variability morphology and micromorphology between different paleosols in the same regional succession provides a basis for interpreting the larger significance of the basal rakes creek paleosol the stratigraphically older upper lawrence and snyderville paleosols in the same area are significantly different in patterns of lateral variability and overall soil characteristics weaker eustatic control and stronger tectonic activity may explain the greater west east variability and eventual eastward disappearance of the basal rakes creek paleosol differences in soil characteristics between the vertisol like upper lawrence and snyderville paleosols and the non vertisol like basal rakes creek paleosol appear to be due to climate change particularly a shift from more seasonal to more uniform rainfall this climate change hypothesis is compatible with overall virgilian stratigraphic trends in the northern midcontinent outcrop area

second round of evaluations of proposed earthquake precursors this review summarizes the result of the second round of nominations for the iaspei preliminary list of significant precursors currently this list contains five cases of precursors 1 foreshocks 2 preshocks 3 seismic quiescence before major aftershocks 4 radon decrease in ground water and 5 ground water level increase a list of four cases that could not be accepted nor rejected by the panels reviewing them contains three on crustal deformations and one on seismic quiescence in the second round 10 nominations were evaluated nine new ones and one which had been considered previously two were accepted for the list two were placed in the category of undecided cases to date a total of 40 nominations have been evaluated by iaspei for 37 of these the nominations the mail reviews the panel opinions and where supplied the author s reply were published this evaluation process remains active throughout the international decade for natural hazards reduction additional nominations are invited

organism substrate interactions and astrobiology potential models and methods abstract organism substrate interactions and their products biogenic structures are important biosignatures on earth this study discusses the application of ichnology the study of organism substrate interactions to the search for present and past life beyond earth three main questions are addressed 1 why to look for biogenic structures i e traces and ichnofabrics beyond earth 2 what biogenic structures to expect on other planets moons and asteroids 3 how to study extraterrestrial biogenic structures review of terrestrial evidence highlights a set of properties that make traces and ichnofabrics important for the search of potential extraterrestrial life trace fossils preserve the activity of soft bodied organisms biogenic structures are resilient to processes that obliterate other biosignatures i e mechanical and chemical degradation diagenesis tectonism and metamorphism traces are very visible biosignatures traces indicate environment and behaviour traces can be universal biosignatures i e biosignatures ideally suited for detecting any type of life a model of organism substrate interactions beyond earth is here proposed expected extraterrestrial traces are those that manifest behaviours that allow to maintain homeostasis excavations meandering traces and biodeposition structures most of the existing rovers and orbiters provide basic instruments for searching these traces it is here suggested that the search for extraterrestrial biogenic structures by rovers would also benefit from artificial adjustable lighting gpr lidar and drilling equipment with optical televiewer in this study open access databases of rover and orbiter imagery have been searched for traces and ichnofabrics but no unquestionable evidence of biogenic structures beyond earth has been found besides those produced by humans this sounds along the lines of the famous fermi paradox if the universe is teeming with aliens where are their traces results of this search show that habitable environments are not the only place to look for biogenic structures non habitable environments such as moons without atmosphere can favour the preservation of shallow tier traces the better preservation potential of traces compared to other biosignatures greatly widens the issue of planetary protection including the interaction between astronauts or vehicles and the substrate may produce disturbances although this study highlights a new direction of study with the tools and concepts of ichnology dialogue between the astrobiological and ichnological communities is needed to use its full potential and possibly answer one of the major questions of science does life exist beyond earth

the role of biological weathering in periglacial areas a study of weathering rinds in south iceland the importance of biogeochemical processes in the morphogenic system of periglacial environments has been underestimated for decades weathering rind studies help to characterise and quantify biogeochemical weathering over time experiments using fungi strains isolated from basaltic boulders allow one to decipher biological weathering a historical approach using heterochronous moraines provides the opportunity to follow the life of weathering rinds and helps to build a chronology of dominant processes of weathering during the first century of exposure it appears that exfoliation of weathering rinds commonly observed on boulders is the result of a combination of both biogeochemical and physical processes

comparative studies of the lichen rock interface of four lichens in vingen western norway abstract sandstone samples from vingen western norway have been analysed to find whether different lichen taxa may explain variations in the degree of weathering at this site the samples were analysed by high performance thin layer chromatography hptlc thin layer chromatography tlc scanning electron microscopy sem x ray diffraction xrd and x ray fluorescence spectroscopy xrf followed by descriptive statistics and principal component analysis pca the study of the weathering rinds beneath four lichens indicates differences in weathering effect between the studied taxa those rinds beneath ophioparma ventosa and to a lesser extend pertusaria corallina are in general deeper and show a higher degree of mineral dissolution and crumbling of the rock surface compared to fuscidea cyathoides and ochrolechia tartarea a very high concentration of fungal hyphae within the weathering rind beneath o ventosa and p corallina compared to the other two taxa may be the cause of the increased biophysical and biochemical weathering o ventosa and f cyathoides contain similar amounts of oxalate which also in general are much higher than for p corallina and o tartarea the studied taxa also contain different lichen compounds differences in content of lichen compounds seem thus to be a more likely explanation for the variations in chemical weathering than differences in oxalic acid production in addition to biological mediated physical and chemical weathering the water holding capacity of lichens may increase the chemical dissolution and frost wedging of rock surfaces the thallus and the endolithic fungal hyphae bind the partly fragmented rock surface and protect it from abrasion and erosion however when the thallus dies loose mineral grains and fragments from the upper lichen mineral interface will be removed and a new surface will be exposed and available for colonization and biodegradation it is thus likely that lichens enhance weathering rates except at locations with extremely high abrasion where they may protect the surface

soil development rates in the transantarctic mountains soil chronosequences were identified at three sites 78 85 s within the transantarctic mountains for determining rates of soil development in cold desert ecosystems more than 175 soils were sampled in xerous and ultraxerous environments on moraines containing sandstone and dolerite and ranging from late holocene ca 6 ka to pre late quaternary ca 250 ka in age based on five linear and nonlinear models highly significant correlations p 0 01 exist between drift age and the following surface boulder weathering features and soil properties percentage of boulders containing desert varnish spalling and pitting depths of staining visible salts ghosts pseudomorphs and coherence in soils electroconductivity in the zone of salt enrichment and total profile salts in the absence of leaching soluble salts readily accumulate in cold desert soils a morphogenetic sequence of soluble salts is presented that relates field observations with laboratory data soil color is highly correlated p 0 01 with dithionite extractable fe within a site the proportion of clasts 15 mm on the surface of the desert pavement increases with time due likely to deflation of fines by strong winds therefore the dominant processes in these cold desert soils are salinization rubification reddening due to oxidation of iron bearing minerals and desert pavement formation

thin widespread pennsylvanian black shales of midcontinent north america a record of a cyclic succession of widespread pycnoclines in a fluctuating epeiric sea

early oligocene paleosols of the dagshai formation india a record of the oldest tropical weathering in the himalayan foreland abstract this study reports paleopedological features of the fossil soils that formed during the earliest phase of continental sedimentation in the himalayan foreland the fluvial sequence of the dagshai formation 31 6 3 9 ma to 30 3 3 9 ma exposed along the koshaliya river nw himalaya contains four pedofacies named pedofacies a d of ferruginous paleosol sequences contained within overbank sediments the dagshai formation unconformably overlies the marine subathu formation pedofacies a consists of 3 4 well developed ferruginous paleosols overlain by gray sandstone beds pedofacies b d are marked by a progressive decrease in pedogenesis these paleosols occur as 0 5 m to 1 5 m thick bw bt btk bk bss horizons that are marked by extensive development of rhizoliths pedogenic carbonate and iron rich clay pedofeatures that correspond to modern entisols inceptisols alfisols and vertisols based on early oligocene paleogeographic position of the northward drifting indian plate it is inferred that these paleosols were formed at 18 n paleolatitude in the dagshai sub basin in the himalayan foreland micromorphology geochemical analyses weathering indices and stable isotope composition of paleosols indicate tropical climate paleoprecipitation of 947 1256 mm and paleotemperature of 25 c with an initial phase of monsoonal conditions during pedogenesis these paleoclimatic conditions favored c3 paleovegetation immediately after the transition from greenhouse to icehouse conditions

low accommodation detrital apron alongside a basement uplift pennsylvanian of midcontinent north america abstract the northern end of the 650 km long nemaha uplift nebraska and kansas usa is an important example of basin margin sedimentation in the north american midcontinent an apron of coarse basal pennsylvanian arkosic clastic sediments bpc was deposited on the flanks of the uplift while marine cyclothems were encroaching from the east small scale fining upward intervals many with demonstrably erosional bases dominate the bpc and are interpreted as overridingly fluvial in origin weak paleosols desiccation cracks and reddened intervals in the bpc record episodic subaerial exposure multiple burrowed horizons and heterolithic strata of probable tidal origin and rare marine fossils also indicate episodic marine influence the bpc appear to have been deposited as a thin apron of coalesced alluvial fans and fan deltas deposition of the bpc occurred during the waning of uplift and subsequent quiescence the comparative thinness and large scale packaging of the bpc are compatible with the controlling effects of relict relief regional subsidence and eustasy rather than ongoing major vertical displacements along active faults a strong autocyclic influence on sedimentation is evidenced by stacked fining upward intervals of poorly sorted conglomerates sandstones and sandy mudstones correlations demonstrate that the accumulation of the bpc took place over more than seven major sea level cycles beginning in cherokee group times middle moscovian middle pennsylvanian and ending only when the eroded uplift was inundated and buried by marine cyclothems on the basis of local correlations with marine cyclothems and using black phosphatic shales so called core shales of heckel p h 1986 sea level surve for pennsylvanian eustatic marine transgressive regressive depositional cycles along midcontinent outcrop belt north america geology 14 330 334 heckel p h 1994 evaluation of evidence for glacio eustatic control over marine pennsylvanian cyclothems in north america and correlation of possible tectonic effects in dennison j m ettensohn f r eds tectonic and eustatic controls on sedimentary cycles sepm concepts in sedimentology and paleontology no 4 pp 5 87 as marker beds we speculate that the bpc exist in backstepping sequences and or parasequences alongside the flanks of the nemaha uplift the bpc are lithologically comparable to contemporaneous deposits alongside the ancestral rockies amarillo wichita uplift and other buried basement highs in north america nonetheless the bpc are an order of magnitude thinner are dominantly retrogradational rather than progradational and their occurrence was not associated with major displacements along basin bounding faults in this manner the bpc are a useful example of low accommodation eustasy dominated coarse grained terrigenous clastic deposition around an uplifted basement block

cryptoendolithic alteration of antarctic sandstones pioneers or opportunists 1 the cryptoendolithic habitat of the antarctic dry valleys has been considered a good analogy for past martian ecosystems if life arose on the planet yet cryptoendoliths are thought to favor the colonization of rocks that have a preexisting porous structure e g sandstones this may weaken their significance as exact analogues of potential rock colonizing organisms on mars given our current understanding of the dominant volcanic nature of martian geology however the production of oxalic acid by these lichen dominated communities and its weathering potential indicate that it could be an aid in rock colonization enabling endoliths to inhabit a wider variety of rock types utilizing icp aes and scanning electron microscope techniques this study investigates elemental and mineralogical compositions within colonized and uncolonized layers in individual sandstone samples this is in order to determine if the weathering of mineral phases within the colonized layers causes an increase in the amount of pore space available for colonization the results show that colonized layers are more weathered than uncolonized deeper portions of the rock substrate layers within uncolonized samples have uniform compositions differences between the colonized and uncolonized layers also occur to varying extents within colonized rocks of different mineralogical maturities the results confirm that cryptoendoliths modify their habitat through the production of oxalic acid and suggest that over time this directly increases the porosity of their inhabited layer potentially increasing the biomass it can support

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

are earthquakes predictable summary the answer to the above question depends on the definition of earthquake prediction we discuss several definitions and possible classifications of earthquake prediction methods we also consider various measures of prediction efficiency review several recent examples of earthquake prediction and describe the methods that can be used to verify prediction schemes we conclude that an empirical search for earthquake precursors that forecast the size of an impending earthquake has been fruitless despite considerable effort in several countries no statistically rigorous validation of proposed precursory phenomena is available therefore reported cases of precursors can be explained by random noise or by chance coincidence we present evidence that earthquakes are non linear chaotic scale invariant phenomena the most probable consequence of earthquake self similarity is a lack of earthquake predictability as popularly defined that is a forecast of a specific individual earthquake many small earthquakes occur throughout any seismic zone demonstrating that the critical conditions for earthquake nucleation are satisfied almost everywhere apparently any small shock can grow into a large event thus it is likely that an earthquake has no preparatory stage this sceptical view of current earthquake prediction efforts should not be interpreted as a statement that any further attempts to mitigate the destructive effects of earthquakes are futile the seismic moment conservation principle when combined with geodetic deformation data offers a new way to evaluate the seismic hazard not only for tectonic plate boundaries but also for areas of low seismicity that is the interiors of continents earthquake clustering with a power law temporal decay omori s law can be used to estimate the rate of future earthquake ocurrence realtime seismology can facilitate relief efforts after large earthquakes and eventually provide an immediate warning of severe shaking a few seconds or tens of seconds before the shaking starts

microbial trace fossil formation biogenous and abiotic weathering in the antarctic cold desert in the antarctic cold desert ross desert the survival of the cryptoendolithic microorganisms that colonize the near surface layer of porous sandstone rocks depends on a precarious equilibrium of biological and geological factors an unfavorable shift of this equilibrium results in death and this may be followed by formation of trace fossils that preserve the characteristic iron leaching pattern caused by microbial activity similar microbial trace fossil may exist in the geological record if life ever arose on early mars similar processes may have occurred there and left recognizable traces

a geochemical traverse across the eastern carpathians romania constraints on the origin and evolution of the mineral water and gas discharges abstract the inner sector of the eastern carpathians displays a large number of na hco 3 co 2 rich meteoric originated cold springs soda springs and bore wells as well as dry mofettes they border the southern part of the pliocene quaternary calimani gurghiu harghita cgh calc alkaline volcanic chain both volcanic rocks and co 2 rich emissions are situated between the eastern part of the transylvanian basin and the main east carpathian range where active compression tectonics caused diapiric intrusions of miocene halite deposits and associated saline co 2 rich waters along active faults the regional patterns of the distribution of co 2 in spring waters as calculated p co 2 and the distribution pattern of the 3 he 4 he ratio in the free gas phases up to 4 5 r m r a show their maximum values in coincidence with both the maximum heat flow measurements and the more recent volcanic edifices moving towards the eastern external foredeep areas where oil fields and associated brines are present natural gas emissions become ch 4 dominated such a change in the composition of gas emissions at surface is also recorded by the 3 he 4 he ratios that in this area assume typical crustal values r m r a 0 02 in spite of the fact that thermal springs are rare in the harghita volcanic area and that equilibrium temperature estimates based on geothermometric techniques on gas and liquid phases at surface do not suggest the presence of shallow active hydrothermal systems a large circulation of fluids gases is likely triggered by the presence of mantle magmas stored inside the crust if total 3 he comes from the mantle or from the degassing of magmas stored in the crust co 2 might be associated to both volcanic degassing and thermometamorphism of recently subducted limestones

examination of surface exposure ages of antarctic moraines using in situ produced 10be and 26al concentrations of 10be t12 1 5 106 y and 26a1 t12 0 72 106 y have been determined by accelerator mass spectrometry ams in a suite of quartz samples taken from sandstone boulders in several moraines in arena valley a dry valley adjacent to the taylor glacier in the quatermain mountains southern victoria land east antarctica these isotopes are produced in surficial quartz by cosmic ray spallation of o and si the concentrations in these samples ranged from 6 1 105 to 3 0 107 at g 1 for 10be and from 9 4 106 to 1 2 108 at g 1 for 26a1 depending upon the extent of exposure at the surface analyses of 10be in several samples from a single moraine at altitudes ranging from 1300 to 1650 m permitted an estimation of the air attenuation pathlength of cosmic ray neutrons the value of 142 96 41 g cm 2 is consistent with other published values production rates of 17 6 4 at g 1 y 1 for 10be and 113 54 16 at g 1 y 1 for 26a1 at 1300 m and 87 s and a 26al 10be production ratio of 6 5 1 3 1 3 were calculated from the data these values correspond to sea level production rates at high geomagnetic latitude of 6 4 at g 1 y 1 and 41 7 at g 1 y 1 for 10be and 26a1 respectively consistent with determinations based on 11 ky glacially polished surfaces in the sierra nevada in california these production rates imply exposure ages for the various moraines ranging from 50 ky to 2 5 my in accordance with other geological evidence the 10be and 26al ages of these rocks compare favorably with those found using a similar dating method based on in situ production of 3he examination of the 3he concentrations in conjunction with the present data set yields an estimate of 3he production of 230 8540 at g 1 y 1 corresponding to 85 31 15 at g 1 y 1 at sea level this is lower than previously reported values of 240 60 at g 1 y 1 and 190 at g 1 y 1 scaled to sea level and high geomagnetic latitude based respectively on volcanic flows less than 2000 years old at low latitude and samples collected from 14 400 year old volcanic flows this discrepancy is likely due to diffusive losses which may become significant up to 50 for surface exposure ages on the order of 2 0 my nevertheless the general correlations among the three isotopes suggest that 3he does not suffer gross losses through diffusion

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

earthquake prediction a critical review summary earthquake prediction research has been conducted for over 100 years with no obvious successes claims of breakthroughs have failed to withstand scrutiny extensive searches have failed to find reliable precursors theoretical work suggests that faulting is a non linear process which is highly sensitive to unmeasurably fine details of the state of the earth in a large volume not just in the immediate vicinity of the hypocentre any small earthquake thus has some probability of cascading into a large event reliable issuing of alarms of imminent large earthquakes appears to be effectively impossible key word earthquake prediction

plausible mechanisms for the boring on carbonates by microbial phototrophs photosynthetic microbes particularly cyanobacteria that bore into carbonates are ancient biological players in various geologic phenomena such as the destruction of biogenic carbonates and coastal limestones the reworking of carbonate sands and the cementation of microbialites their signatures are important tools for paleoenvironmental reconstruction and they play a significant role in marine aquaculture in spite of their geologic environmental and economic importance the mechanism by which they are able to excavate calcareous and calcophosphatic mineral substrates remains unknown excavation by acidulation commonly thought to be a possible mechanism constitutes nothing less than an apparent paradox in that the geochemical consequence of oxygenic photosynthesis should be carbonate precipitation not dissolution three alternative mechanistic models are presented here that may allow cyanobacterial boring to proceed and be still consistent with available evidence as well as microbiological and geologic geochemical principles they are based on either temporal or spatial separation of photosynthesis and respiration and on the active extrusion of calcium ions through an active cellular uptake and transport process from the three models the latter is shown to be most appropriate in describing and explaining the boring phenomenon several experimental approaches are discussed that would be appropriate to elucidate the paradox

uplands lowlands and climate taphonomic megabiases and the apparent rise of a xeromorphic drought tolerant flora during the pennsylvanian permian transition abstract the late mississippian and pennsylvanian have been referred to as the coal age due to enormous paleotropical peat accumulations coal beds numerous fossil floras have been collected from these coals and their associated seat earth paleosols and roof shales over more than two centuries leading to the inference of vast swampy wetlands covering the pangean tropics during the pennsylvanian in contrast the permian tropics are characterized as more arid with sparser and more heterogeneous vegetation than inferred for the pennsylvanian in the tropics the pennsylvanian to permian transition has been described as a changeover from a pteridophyte dominated paleophytic flora to a seed plant dominated mesophytic flora this view notwithstanding floras dominated by xeromorphic seed plants also are well known from the pennsylvanian tropics some authors have characterized these plants as being occupants of uplands subsequently transported into basinal lowland preservational environments in this model uplands are well drained causing areas of drought under otherwise everwet climates in this paper we present an alternative interpretation that the apparent transition in pennsylvanian permian tropical vegetation reflects two types of taphonomic megabias first is a preservational megabias strongly favoring the vegetation of humid climates over that of seasonally dry climates accordingly tropical plant preservational potential fluctuated in concert with late paleozoic ice age glacial interglacial oscillations and contemporaneous sea level and climatic changes second is an analytical megabias strongly favoring the discovery and collection of the wetland biome from pennsylvanian strata overlooking the less frequently and more poorly preserved drought tolerant biome by permian times vast wetlands and their fossil record had largely disappeared from central pangea although continuing in cathaysia making drought tolerant vegetation more visible to searchers without changing its preservational circumstances we demonstrate that the upland model is untenable being inconsistent with the principles of plant biogeography and with geological aspects of the fossil record

eustatic and autocyclic influences on deposition of the lower pennsylvanian mary lee coal zone warrior basin alabama abstract deposition of marine strata associated with the lower pennsylvanian mary lee coal zone pottsville formation was controlled by the allocyclic mechanism of eustatic sea level change the vertical stacking of marine marginal marine and terrestrial facies indicates that this interval was deposited during a single transgression regression transgression cycle ravinement surfaces and associated autochthonous macro invertebrate and trace fossil assemblages record the landward retreat of the shoreline and abrupt deepening due to rapid rise in sea level these horizons are overlain by terrigenous clastic facies either tidal sand bodies or shelf mudstones which indicate shoaling due to progradation during the subsequent filling of the generated accommodation space although marine influence including the effects of tidal currents continued during the more terrestrial phases of deposition autocyclic factors including the control of paleotopography by differential compaction of buried peat bodies were also important in determining facies distribution

slab in the wrong place lower lithospheric mantle delamination in the last stage of the eastern carpathian subduction retreat a model with a new type of delamination of the lower lithospheric mantle is proposed to explain the pliocene to recent tectonic evolution of the eastern carpathians we suggest that after the continental collision in middle miocene time break off of the west dipping subducting slab occurred at a depth of 70 km slab break off propagated horizontally toward the east inducing lithospheric delamination and movement of the vrancea slab into its present position delamination was followed by rapid asthenospheric rise resulting in magma generation and the explosive alkaline basaltic magmatism of the persani mountains contamination of the former subduction related magmatic reservoirs with the alkalic basaltic material and differentiation processes produced the harghita calc alkaline and shoshonitic rocks the asthenospheric rise induced crustal uplift which is the triggering mechanism for extension and formation of the brasov gheorghieni hinterland basins the extension was accommodated by shortening and folding in the foreland the vertical vrancea slab appears in our model as a segment of delaminated lower lithospheric mantle that is seismically active due to the ongoing pull of the eclogitized oceanic crust the model explains the displaced and shallow position of the slab relative to the eastern carpathian suture zone

shear wave splitting and earthquake forecasting seismic shear wave splitting sws monitors the low level deformation of fluid saturated microcracked rock we report evidence of systematic sws changes recorded above small earthquakes monitoring the accumulation of stress before earthquakes that allows the time and magnitude of impending large earthquakes to be stress forecast the effects have been seen with hindsight before some 15 earthquakes ranging in magnitude from an m1 7 seismic swarm event in iceland to the ms7 7 chi chi earthquake in taiwan including a successfully stress forecast of a m5 0 earthquake in sw iceland characteristic increases in sws time delays are observed before large earthquakes which abruptly change to deceases shortly before the earthquake occurs there is a linear relationship between magnitudes and logarithms of durations of both increases and decreases in sws time delays before large impending earthquakes however suitably persistent swarms of small earthquakes are too scarce for routine stress forecasting reliable forecasting requires controlled source cross hole seismics between neighbouring boreholes in stress monitoring sites sms it would be possible to stress forecast damaging earthquakes worldwide by a global network of sms in real time

wind blown particles as weathering agents an antarctic example abstract observations from taylor valley antarctica suggest that the wedging effect of sand particles packed by powerful winds into cracks in rocks may act as a weathering mechanism the strong winds and their accompanying solid material may cause stresses to the rock in three ways the direct pressure of the wind and material the hammering effect of the particles and by preventing the closure of cracks opened by other forces although crude estimations of the forces involved have been calculated actual field measurements are needed this is a process which may operate in other dry environmentson our planet ond possibly on some of the hyper dry inner planets of our solar system

filtration models guilds and biofacies crinoid paleoecology of the stanton formation upper pennsylvanian midcontinent north america abstract filtration models make several predictions concerning the distribution of crinoids among benthic habitats 1 generally higher energy shoreward settings should contain crinoid assemblages dominated by taxa with dense mesh filtration fans 2 generally lower energy offshore settings should be dominated by crinoids with open mesh filtration fans 3 diversity should be highest in nearshore settings which generally contain low energy microhabitats within high energy settings where both dense fan and open fan forms can co occur whereas offshore assemblages should be dominated by open fan taxa thus open fan forms should be more eurytopic than dense fan forms also previous empirical models for crinoid distribution patterns note that nearshore assemblages are dominated by large forms whereas offshore assemblages are dominated by small forms filtration fan morphology and body size interact significantly to determine how and where crinoids feed and thus are used here as criteria for distinguishing late paleozoic crinoid guilds the distribution patterns of crinoid taxa and guilds among the benthic paleoenvironments of the upper pennsylvanian missourian stanton formation were used to test the predictions of the filtration models the results of quantitative analyses show that large dense fan crinoids are significantly more abundant in shoreward assemblages than smaller open fan crinoids which are more abundant in offshore assemblages these results are consistent with the aforementioned models however diversity patterns are not consistent with the filtration models indicating that mid depth and aerobic offshore assemblages are more taxonomically and trophically diverse than nearshore and dysaerobic offshore assemblages ostensibly due to the overlapping ranges of characteristically nearshore and offshore taxa analysis of guild distribution patterns also indicates some contradictions to predicted patterns of stenotopy and eurytopy indicating additional complexities to late paleozoic crinoid paleoecology five recurrent crinoid assemblages or biofacies have been identified from the stanton formation of midcontinent north america the guild structure and diversity of these biofacies are characterized here as 1 a moderate diversity nearshore biofacies dominated by large calyx dense fan guilds 2 a high diversity midshelf biofacies characterized by equitable contributions of many taxa and guilds 3 a moderate diversity offshore biofacies dominated by non pinnulate and small calyx open fan pinnulate guilds 4 a low diversity offshore dysaerobic biofacies dominated by small calyx pinnulate guilds 5 a depauperate offshore biofacies dominated by a unique stalkless species paragassizocrinus tarri except for biofacies 5 the number of guilds appears to increase offshore however the equitability of taxa among and within the guilds generally decreases offshore this pattern indicates that the heterogeneity of resources or the recognition by taxa of different classes of resources as reflected by the variety of functional types increased from nearshore to offshore but that the abundance or accessibility of these resources and or the relaxation of competition within guilds increased from offshore to nearshore

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

application of sequence and genetic stratigraphic concepts to carboniferous coal bearing strata an example from the black warrior basin usa carboniferous strata provide an excellent example on which to test the application of genetic stratigraphic and sequence stratigraphic concepts both approaches are employed in the evaluation of the coal bearing strata of the black warrior basin south eastern usa bounding hiatal surfaces have been recognized in the succession of rock that includes the mary lee coal zone within the framework of genetic stratigraphy one genetic sequence has been identified comprised of offlap progradational and aggradational facies and onlap aggradational and transgressive facies components seven parasequence sets have been delimited according to the concepts of sequence stratigraphy these have been ascribed to transgressive highstand and shelf margin systems tracts the identification of components of these contrasting frameworks provide the basis for evaluating other carboniferous strata

crinoid biofacies in upper carboniferous cyclothems midcontinent north america faunal tracking and the role of regional processes in biofacies recurrence abstract coordinated stasis is a pattern of long term multispecies evolutionary and ecological stability bounded by rapid turnover events one class of models proposed to explain the paleoecological pattern of biofacies stability typified by ecological locking states that biotas within habitats become integrated into ecological units that through population and community level processes rebound and persist through short term disturbances this high frequency community resilience allows the units to persist through geologic time tracking their preferred habitats during transgressions and regressions because species are tightly woven into the fabric of the ecosystem there is little opportunity for speciation this also buffers them against extinction this ecological locking by ecosystem homeostatic processes produces long intervals of regionally stable biofacies in the fossil record in these models the primary structuring mechanisms are at the local community level controlled by species autecology species interactions and local disturbance regime an opposing class of models states that species are fundamentally independent and that species interactions are not strong nor spatio temporally persistent enough to forge communities into integrated units with long term persistence community recurrence would be expected as long as the various habitat types recur in time and space species autecologies remain stable the pool of available species remains intact and the recruitment of species into local habitats is not interrupted the focus of these models is dominantly at the regional level controlled by biogeographic history and dispersal among as well as within communities the results of this study of crinoids from the upper carboniferous lansing group of midcontinent north america show that they are distributed among five recurrent paleocommunity types or biofacies which are generally arrayed along an onshore offshore gradient two of these biofacies are restricted to the offshore dysaerobic horizons of the most extensive cyclothem in the group the other three biofacies recur consistently among the cycles however this repeated pattern includes a regionally distributed offshore biofacies unique to late transgressive deposits that is not found in analogous regressive deposits while the distribution of the two shoreward biofacies is consistent with faunal tracking the recurrence of a biofacies unique to late transgressive horizons is not consistent with an integrated paleocommunity that tracks shifting habitats through transgression and regression these results favor the alternative models namely that biofacies develop in place via dispersal from a persistent species pool in response to prevailing environmental conditions the recurrence of apparently ephemeral biofacies through time underscores the importance of regional processes in controlling local paleocommunity composition the establishment of refuges or source populations during environmental bottlenecks i e lowstands is critical to maintaining the regional species pool through time for continued recruitment into local sink paleocommunities during more amenable times i e highstands metapopulation dynamics among habitats are equally important in maintaining species within a region through time conflicting observations of stochastic individualistic and deterministic integrated behaviors of the same ecological systems probably result from differences in the scales of analyses and therefore the processes being studied

why is earthquake prediction research not progressing faster abstract as a physical phenomenon earthquakes must be predictable to a certain degree however the problem is difficult because the source volume inside the earth is inaccessible to direct observation and because the most important parameter the stress level cannot be measured directly also seismology is such a young science that the cause of earthquakes was discovered in the 1960s only advanced seismograph networks as well as modern techniques to measure crustal deformations such as the global positioning system gps and the synthetic aperture radar interferometry technique insar have come on line only recently and only in japan are they deployed with the densities necessary for significant advances in the understanding of the rupture initiation process in addition no real program for earthquake prediction research exists in the united states largely because funding agencies and peer reviewers shy away from a field in which unprofessional but motivated individuals are active although claims of successful predictions are often not justified a few correct predictions have been made most of these had time windows of years but some were accurate to days and allowed preparatory actions to make significant progress we must learn how to conduct rigorous science in a field where amateurs cannot be discouraged to venture leadership is necessary to raise the funding to an adequate level and to involve the best minds in this promising potentially extremely rewarding but controversial research topic

endolithic microorganisms in the antarctic cold desert in the frigid desert of the antarctic dry valleys there are no visible life forms on the surface of the soil or rocks yet in certain rock types a narrow subsurface zone has a favorable microclimate and is colonized by microorganisms dominant are lichens of unusual organization they survive not by physiological adaptation to lower temperatures but by changing their mode of growth being able to grow between the crystals of porous rocks their activity results in mobilization of iron compounds and in rock weatherning with a characteristic pattern of exfoliation this simple ecosystem lacks both higher consumers and predators

fungal weathering of basaltic rocks in a cold oceanic environment iceland comparison between experimental and field observations this paper presents evidence for strong biochemical weathering of basaltic outcrops induced by fungal communities in a cold environment weathering rind formation is considered to be a consequence of the biological activity comparisons between in vitro experiments and in situ observations allow a characterization of fungi effects on rocks and help to define the place of these microorganisms in the cold environment weathering chain it is concluded that biological weathering is chronologically the first process of weathering probably leading to the subsequent expression of cryogenic processes information presented here suggests the need for reconsideration of the traditional frost driven morphogenetic system normally considered for sub polar areas

paleosols in shallow marine carbonate sequences abstract shallow water carbonate sequences in the geological record commonly exhibit numerous exposure surfaces reflecting emersion of sediment due to progradation processes and sealevel oscillations some ancient platform sequences contain hundreds of such surfaces associated with paleosols fossil soils typically calcretes a wide range of macro and microstructures are associated with these calcretes which are reviewed profile types and stages in profile development can be defined the nature of the exposure surface and associated paleosols can be used to identify the nature of the prevailing climate although hydromorphic effects related to marine flooding of the platforms can modify the paleosols a potentially important use of paleosols is to define the nature of sequence boundaries several studies have identified sets of paleosols with varying maturities reflecting changes in rates of accommodation space creation during sealevel rises and falls

discontinuity bounded alluvial sequences of the southern gangetic plains india aggradation and degradation in response to monsoonal strength abstract discontinuity bounded late quaternary sequences in the southern gangetic plains himalayan foreland basin reflect floodplain aggradation and degradation in response to forcing by the powerful southwest indian monsoon the major himalayan and cratonic rivers in this area occupy narrow incised valleys and do not inundate the adjoining broad interfluves which display soil development small plains fed rivers lakes eolian deposits and badland ravines however these areas formerly experienced active alluviation because thick floodplain muds underlie the interfluve an age model suggests that interfluve areas near the major rivers aggraded periodically between about 27 ka and 90 ka marine oxygen isotope stages 3 5 they subsequently degraded or accumulated sediment only locally probably reflecting decreased monsoonal precipitation around the last glacial maximum marine isotope stage 2 when major river valleys moved to an underfit condition increased precipitation during the 15 to 5 ka period of monsoon recovery probably increased discharge and promoted incision and widespread badland formation discontinuities at deeper levels reflect earlier degradation phases and are marked by reworked gravel lenses thin channel bodies and carbonate cemented surfaces carbonate veins infilled joints that cut strata below but not above one discontinuity suggest some local tectonic influence there is no evidence that sea level fluctuations influenced stratal patterns in this elevated inland region discontinuity bounded sequences linked to climate change may characterize alluvial successions in many continental settings especially along the cratonic margins of foreland basins where subsidence rates are modest

diagenesis of upper carboniferous rocks in the ouachita foreland shelf in mid continent usa an overview of widespread effects of a variscan equivalent orogeny diagenesis of upper carboniferous foreland shelf rocks in southeastern kansas took place at temperatures as high as 100 150 c at a depth of less than 2 km high temperatures are the result of the long distance hundreds of kilometers advection of groundwater related to collisional orogeny in the ouachita tectonic belt to the south orogenic activity in the ouachita area was broadly late carboniferous equivalent to the variscan activity of europe mississippi valley type pb zn deposits and oil and gas fields in the us midcontinent and elsewhere are commonly attributed to regional groundwater flow resulting from such collisional events this paper describes the diagenesis and thermal effects in sandstone and limestone of upper carboniferous siliciclastic and limestone shale cyclothems the purported confining layer of a supposed regional aquifer diagenesis took place in early intermediate and late stages many intermediate and late stage events in the sandstones have equivalents in the limestones suggesting that the causes were regional the sandstone paragenesis includes siderite cement early stage quartz overgrowths intermediate stage dissolution of feldspar and carbonates followed by minor fe calcite pore filling kaolinite and sub poikilotopic ca ankerite late stage the limestone paragenesis includes calcite cement early stage megaquartz chalcedony and fe calcite spar intermediate stage and dissolution ca fe dolomite and kaolinite late stage the r m value of vitrinite shows a regional average of 0 6 0 7 rock eval t max suggests a comparable degree of organic maturity the t h of aqueous fluid inclusions in late stage ca fe mg carbonates ranges from 90 to 160 and t mice indicates very saline water 200000 ppm nacl equivalent 18o suggests that the water is of basinal origin local warm spots have higher r m t max and t h the results constrain numerical models of regional fluid migration which is widely viewed as an artesian flow from recharge areas in the ouachita belt across the foreland basin onto the foreland shelf area such models must account for heating effects that extend at least 500 km from the orogenic front and affect both supposed aquifer beds and the overlying supposed confining layer warm spots indicate either more rapid or more prolonged flow locally t h and t mice data show the highest temperatures coincided with high salinity fluids

surface exposure chronology using in situ cosmogenic 3he in antarctic quartz sandstone boulders abstract in situ produced cosmogenic helium 3 he c provides a new tool for constraining histories of quaternary geomorphic surfaces before general application of the technique however the systematics and production rates of 3 he c must be well understood in a companion study 3 he and 10 be data from sandstone and granite boulders in the dry valleys region of antarctica have been used to constrain the ages of an important moraine sequence formed by the taylor glacier data from these deposits also provide information about the systematics of 3 he in quartz that has important implications for geochronology based on 3 hec in contrast to previous results from olivine and clinopyroxene crushing quartz in vacuo releases helium with high 3 he 4 he ratios up to 148 r a where r a is the atmospheric 3 he 4 he ratio indicating that crushing cannot be used to determine the isotopic composition of trapped i e noncosmogenic helium in quartz analysis of 3 he in different size fractions of the same samples indicates significant 3 he loss not predicted by existing 3 he diffusion data for quartz the origin of the discrepancy is not clear but loss from these samples is not as significant as suggested by the limited data of previous studies

geomorphology of a pennsylvanian land surface pedogenesis in the rock lake shale member southeastern nebraska abstract extensive fresh exposures of reddish brown mudstones in the rock lake shale member in a quarry in southeastern nebraska show pedogenic features calcite glaebules blocky spar crystallaria peds silt and clay or micrite filled pedotubules slickensides mottling and overall horizonation which indicate protracted subaerial exposure under increasingly arid conditions the rock lake paleosol is bounded above and below by marine cyclothem deposits probable events represented by the paleosol are 1 clay and silt illuviation under humid conditions 2 subsequent carbonate precipitation under progressively drier conditions and 3 gleying of the a horizon during a marine transgression the rock lake paleosol developed on a flat and laterally extensive semiarid to arid plain during a low stand of sea level examination of the rock lake at other localities well cores and exposures in nearby counties shows a distinct eastward facies change toward lower topography earlier marine transgression and arrested pedogenesis which is consistent with transect direction from the nemaha uplift to the forest city basin

earthquake prediction using extinct monogenetic volcanoes a possible new research strategy abstract volcanoes are extremely effective transmitters of matter energy and information from the deep earth towards its surface their capacities as information carriers are far to be fully exploited so far volcanic conduits can be viewed in general as rod like or sheet like vertical features with relatively homogenous composition and structure crosscutting geological structures of far more complexity and compositional heterogeneity information carrying signals such as earthquake precursor signals originating deep below the earth surface are transmitted with much less loss of information through homogenous vertically extended structures than through the horizontally segmented heterogeneous lithosphere or crust volcanic conduits can thus be viewed as upside down antennas or waveguides which can be used as privileged pathways of any possible earthquake precursor signal in particular conduits of monogenetic volcanoes are promising transmitters of deep earth information to be received and decoded at surface monitoring stations because the expected more homogenous nature of their rock fill as compared to polygenetic volcanoes among monogenetic volcanoes those with dominantly effusive activity appear as the best candidates for privileged earthquake monitoring sites in more details effusive monogenetic volcanic conduits filled with rocks of primitive parental magma composition indicating direct ascent from sub lithospheric magma generating areas are the most suitable further selection criteria may include age of the volcanism considered and the presence of mantle xenoliths in surface volcanic products indicating direct and straightforward link between the deep lithospheric mantle and surface through the conduit innovative earthquake prediction research strategies can be based and developed on these grounds by considering conduits of selected extinct monogenetic volcanoes and deep trans crustal fractures as privileged emplacement sites of seismic monitoring stations using an assemblage of physical chemical and biological sensors devised to detect precursory signals earthquake prediction systems can be built up based on the concept of a signal emission transmission reception system in which volcanic conduits and or deep fractures play the role of the most effective signal transmission paths through the lithosphere unique precursory fingerprints of individual seismic structures are expected to be pointed out as an outcome of target oriented strategic prediction research intelligent pattern recognition systems are to be included for evaluation of the signal assemblages recorded by complex sensor arrays such strategies are expected however to be limited to intermediate depth and deep seismic structures due to its particular features and geotectonic setting the vrancea seismic structure in romania appears to be an excellent experimental target for prediction research