aftershock decay productivity and stress rates in hawaii indicators of temperature and stress from magma sources 1 we examined dozens of aftershock sequences in hawaii in terms of gutenberg richter and modified omori law parameters we studied p the rate of aftershock decay ap the aftershock productivity defined as the observed divided by the expected number of aftershocks and c the time delay when aftershock rates begin to fall we found that for earthquakes shallower than 20 km p values 1 2 are near active magma centers we associate this high decay rate with higher temperatures and faster stress relaxation near magma reservoirs deep earthquakes near kilauea s inferred magma transport path show a range of p values suggesting the absence of a large deep magma reservoir aftershock productivity is 4 0 for flank earthquakes known to be triggered by intrusions but is normal 0 25 to 4 0 for isolated main shocks we infer that continuing post main shock stress from the intrusion adds to the main shock s stress step and causes higher ap high ap in other zones suggests less obvious intrusions and pulsing magma pressure near kilauea s feeding conduit we calculate stress rates and stress rate changes from pre main shock and aftershock rates stress rate increased after many intrusions but decreased after large m7 8 earthquakes stress rates are highest in the seismically active volcano flanks and lowest in areas far from volcanic centers we found sequences triggered by intrusions tend to have high ap high 0 10 day c values a stress rate increase and sometimes a peak in aftershock rate hours after the main shock we interpret these values as indicating continuing intrusive stress after the main shock

upper mantle structure of the northern cascadia subduction zone previous knowledge of the structure of the cascadia subduction zone north of the canada united states border has been derived from a variety of geophysical studies that accurately delineated the downgoing juan de fuca plate from the offshore deformation front to depths of 50 60 km beneath south central vancouver island and the georgia strait little is known however of the structure of the cascadia subduction zone farther westward and to greater depths in the upper mantle we have assembled a set of some 1100 teleseismic traveltimes from events recorded on the western canadian telemetered network to augment a previously existing data set recorded on the washington regional seismograph network the composite data set is inverted for upper mantle structure below washington oregon and southwestern british columbia we analyze the new northern portion of the model between 48 5 50 n and 118 127 w which provides the first images of the deep slab structure in this region the model is parameterized using s

deep magma body beneath the summit and rift zones of kilauea volcano hawaii a magnitude 7 2 earthquake in 1975 caused the south flank of kilauea volcano hawaii to move seaward in response to slippage along a deep fault since then a large part of the volcano s edifice has been adjusting to this perturbation the summit of kilauea extended at a rate of 0 26 meter per year until 1983 the south flank uplifted more than 0 5 meter and the axes of both the volcano s rift zones extended and subsided the summit continues to subside these ground surface motions have been remarkably steady and much more widespread than those caused by either recurrent inflation and deflation of the summit magma chamber or the episodic propagation of dikes into the rift zones kilauea s magmatic system is therefore probably deeper and more extensive than previously thought the summit and both rift zones may be underlain by a thick near vertical dike like magma system at a depth of 3 to 9 kilometers

palaeoenvironmental significance of palustrine carbonates and calcretes in the geological record interest in palustrine carbonates and calcretes has increased over the last 20 years since they contain significant environmental information much of the work performed in this area has focused on either of two types of terrestrial carbonate palustrine carbonates or calcretes pedogenic and groundwater yet their simultaneous study shows there may be a gradual transition from one form to the other revealing the interplay between pedogenic sedimentary and diagenetic processes three main factors control the formation of these carbonates the position of the water table the host rock and the period of sub aerial exposure in pedogenic calcretes precipitation of carbonate takes places mostly in the vadose zone above the water table and within a previous host rock or sediment in groundwater calcretes the precipitation of carbonate also occurs within a previous host rock and around the groundwater table in palustrine carbonates however the precipitation of lime mud occurs in a lacustrine water body palustrine carbonates necessarily form on previous lacustrine mud whereas both types of calcretes may form on any type of sediment or soil the sub aerial exposure time needed to form palustrine carbonates may by relatively short even a season whereas pedogenic calcretes need more time several years to millions of years groundwater calcretes do not form on the topographic surfaces so there is no need of sub aerial exposure however stable surfaces favour the development of thick groundwater calcretes small fluctuations in the water table cause gradual transitions of these three types of terrestrial carbonates and the subsequent mixture of their characteristic features causing difficulties in the interpretation of these carbonates the formation of these carbonates is controlled by palaeoenvironmental factors both commonly form in semi arid climates arid climates are also suitable for calcretes but sub humid conditions are more suitable for palustrine carbonates more indications of climatic conditions may be obtained through the analysis of the d18o content of both calcretes and palustrine carbonates and from the depth of the horizon containing carbonate nodules in pedogenic calcretes vegetation is also important in the formation of these types of carbonates data on the prevailing vegetation can be obtained from the analysis of the micro and macrofabric as well as from the d13c signal of the primary carbonates which in pedogenic carbonates has also been used to estimate atmospheric pco2 during the phanerozoic these terrestrial carbonates are widely distributed on floodplains and distal areas of alluvial basins their presence and characteristics can be used as indicators of aggradation subsidence or accommodation rates and therefore as indicators of different tectonic regimes even though the study of these carbonates has notably increased in recent years much less is known about them than about marine carbonates presently there is much emphasis on obtaining a general model for sequence stratigraphy in terrestrial basins with a need to include the carbonates analysed in this paper

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

inversion of body wave delay times for mantle structure beneath the hawaiian islands results from the pelenet experiment abstract as an experiment to assess the nature of resolvable seismic velocity anomalies in the mantle surrounding the hawaiian islands we operated a temporary network known as pelenet consisting of seven broadband portable seismometers on the islands of kauai molokai maui and hawaii during 1995 1999 here we report the inversion of body wave delay times across the network including arrivals at the global seismic network station kip on oahu and the ocean seismic network pilot experiment south of oahu to determine the three dimensional seismic velocity structure of the upper mantle of the region the consistent feature observed in both p and s wave inversions is a low velocity anomaly beneath maui and molokai which we suggest may reflect a zone of secondary melting in the asthenosphere downstream from the hotspot locus the inversions do not resolve a cylindrical low velocity plume in the upper mantle beneath the island of hawaii but resolution tests indicate that this outcome could be the result of the sparse and nearly linear distribution of stations combined with the incomplete azimuthal coverage of earthquake sources a determination of the detailed three dimensional structure of the upper mantle beneath the hawaiian hotspot will require a simultaneous deployment of both ocean bottom and land seismometers

high temperature elasticity of iron bearing olivines the first high temperature data on the nine adiabatic elastic moduli for iron bearing olivine are reported these measurements are on two single crystal specimens of natural olivine at ambient pressure and from room temperature to a maximum of 1500 k the two specimens contain 8 and 9 modal percent fayalite which required the oxygen fugacity be controlled at high temperature to preserve their chemical stability the rectangular parallelepiped resonance apparatus was adapted to buffer the specimens from the atmosphere with a mixture of co and co2 gas a small increase 1 2 gpa in the adiabatic bulk modulus of each specimen over that of end member forsterite was found the data are high quality to extreme temperatures with good agreement found when comparing the temperature derivatives of the elastic moduli of the two specimens neither specimen exhibits measurable nonlinear temperature dependence in the computed isotropic bulk and shear moduli which is in contrast to published forsterite data the temperature derivatives of the isotropic bulk modulus ks are 1 69 1 80 10 2 gpa k 1 for the two olivine specimens and the shear modulus g derivatives are 1 38 1 36 10 2 gpa k 1 these derivatives are only slightly larger in magnitude than ks t p 1 56 10 2 and g t p 1 30 10 2 gpa k 1 found previously for iron bearing olivine over a very small temperature range there are also no significant differences between the temperature derivatives found here and the average derivatives of end member forsterite from data retrieved over a slightly larger temperature range several dimensionless parameters have been calculated from these results and are discussed in view of systematics which bear on high pressure phases in earth s transition zone one result from these systematics related to the seismic velocities in the earth and especially the shear wave velocities is that an olivine content of less than 50 is implied at the 400 km discontinuity if earth s upper mantle is isochemical furthermore the substitution of almost 10 iron for magnesium at the forsterite end of the olivine solid solution series has little effect on the dimensionless parameters or on the temperature derivatives of the elastic moduli at high temperature

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part ii integrating geomorphology climate and glacioeustasy abstract distinct lateral and stratigraphic trends in paleosol morphology and clay mineralogy in conjunction with the stable isotope composition of sub millimeter scale spherulitic siderite sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian cyclic coal bearing strata of the illinois basin ib presented herein provide proxy records of middle late pennsylvanian equatorial terrestrial environments collectively these data provide a better understanding of the polygenetic history of ancient soils preserved in cyclic strata and indicate that low latitude pennsylvanian ib soil profiles were influenced by a combination of autogenic and allogenic controls lateral variations in paleosol morphology from the interior of the basin to the northern margin indicate that soil development was dominantly influenced by autogenic controls such as differences in local paleohydrology i e groundwater fluctuations and subsidence rates across the basin conversely allogenic controls i e glacioeustasy and climate are interpreted to be principally responsible for the preservation of features in gleyed protosols gleyed vertisols and gleyed calcic vertisols that occur in the interior of the ib these paleosols are characterized by a polygenetic development history that includes 1 an initial period of soil formation in well drained environments with seasonal wetting and drying of the profile followed by 2 a subsequent period of waterlogging and development of reducing conditions paleosols that lack evidence for extensive periods of waterlogging are restricted with the exception of two examples to the northern margin of the basin and they become abundant in the stratigraphic record near the middle upper pennsylvanian boundary uppermost desmoinesian the stratigraphic distribution of these paleosols in conjunction with a decrease in the relative abundance of kaolinite in the 2 m size fraction of ib paleosols near the desmoinesian missourian d m boundary is interpreted to reflect a shift in the overall low latitude regional climate to drier conditions the stable isotope compositions of sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian strata of the ib provide an additional proxy record of past equatorial terrestrial environments and are used to constrain the magnitude of paleoclimate change across the d m moscovian kasimovian boundary sphaerosiderite 18ov pdb and 13cv pdb values range from 3 6 to 0 5 and 12 8 to 3 2 respectively in particular sphaerosiderite 18o values from the b horizons of paleosols display an approximate 1 5 shift across the d m boundary this stratigraphically short isotopic shift occurs across the d m boundary on the order of one cyclothem 400 kyr and is followed by a subsequent shift on the order of one cyclothem back to more positive siderite 18o values the average 18ov smow and dv smow values of kaolinite isolated from the 0 2 m size fraction of a latest desmoinesian flint clay breccia are 21 0 and 46 5 these values correspond to a latest desmoinesian crystallization temperature of 27 2 c and a meteoric water 18ov smow value of 3 1 combination of sphaerosiderite 18o values and co occurring flint clay kaolinite d and 18o values suggest a possible warming of up to 6 c across the d m boundary corresponding to an approximate temperature change of siderite crystallization from 27 to 33 c this temperature increase in conjunction with distinct stratigraphic trends in the clay mineralogy and morphology of ib paleosols is consistent with previous paleoclimate interpretations and it suggests that low latitude pennsylvanian paleoclimate became drier and warmer across the d m boundary

shear wave structure of the lithosphere above the hawaiian hot spot from two station rayleigh wave phase velocity measurements we have measured fundamental mode rayleigh wave phase velocity dispersion from seismograms of five earthquakes recorded at stations on the islands of hawaii and oahu and inverted these data for upper mantle velocity structure the seismic lithosphere of the velocity model is 88 7 km thick which is similar to that of 80 90 myr oceanic lithosphere indicating that no significant lithospheric thinning takes place above the mantle plume below the lithosphere the shear wave velocity decreases to 4 0 km s 1 the seismic model is consistent with the structure of the hawaiian plume model of watson and mckenzie 1991 which has a 72 km thick mechanical boundary layer with the shallowest melting occurring at 82 km depth the difference between the dispersion measured on the hawaii oahu path and that observed by woods and okal 1996 on the oahu midway path can be explained by the cooling of the injected hot plume material

monitoring velocity variations in the crust using earthquake doublets an application to the calaveras fault california we present a technique that greatly improves the precision in measuring temporal variations of crustal velocities using an earthquake doublet or pair of microearthquakes that have nearly identical waveforms and the same hypocenter and magnitude but occur on different dates we compute differences in arrival times between seismograms recorded at the same station in the freqency domain by cross correlation of short windows of signal a moving window analysis of the entire seismograms including the coda gives t the difference in arrival times versus running time along the seismogram the time resolution of the method is an order of magnitude better than the digitization interval the t technique is illustrated with a pair of microearthquakes m 1 7 and 2 0 that occurred before and after the coyote lake california earthquake m 5 9 of august 6 1979 and on the same segment of the calaveras fault that ruptured during the earthquake the coda wave arrivals for some stations are progressively delayed for the second earthquake in the doublet so that its seismogram appears as a stretched version of the earlier event we interpret this systematic variation in t along the coda as a change in the average s velocity in the upper crust in the time interval between the two doublets s wave velocities appear to have decreased by 0 2 in an oblong region 5 10 km in radius at the south end of the aftershock zone

teleseismic tomography of the mantle in the carpathian pannonian region of central europe summary subducted slab roll back lithospheric instability and asthenospheric extrusion have all been proposed as mechanisms that explain the evolution of the extensional pannonian basin within the convergent arc of the alpine carpathian mountain system in central europe we determine the p and s wave velocity structure of the mantle to depths of 850 km beneath this region using tomographic inversion of relative arrival time residuals from 225 p waves and 124 s waves teleseismic earthquakes recorded by 56 stations of the carpathian basins project cbp temporary seismic network 16 month duration and 44 permanent seismic stations the observed median p wave relative arrival time residuals vary between 1 13 s early in the alps and 1 12 s late at the western end of the carpathians s wave relative arrival time residuals are about twice as large 2 13 s and 3 39 s we tested the effect of deterministic corrections on our relative arrival time residuals using crustal velocity models from controlled source experiments but show that the use of station terms in the inversion provides a robust method of correcting for near surface crustal variation our tomographic models reduce the p wave rms residual by 71 per cent to 0 130 s and our s wave rms residual by 59 per cent to 0 624 s at shallow sublithospheric depths we image several localized lower velocity regions correlated with higher heat flow and interpreted as upwelling asthenosphere we image a high velocity structure down to depths of about 350 km beneath the eastern alps further east beneath the pannonian basin a deeper continuation of the eastern alps fast anomaly is imaged trending e w from 300 km depth and extending into the mantle transition zone mtz in the mtz we image a fast anomaly extending outwards as far as the carpathians the dinarides and the eastern alps this higher velocity mantle material is interpreted as being produced by a mantle downwelling whose detachment from the lithosphere above may have triggered the extension of the pannonian basin

genesis of crystal rich volcaniclastic facies in the permian red beds of the central pyrenees ne spain abstract the permo carboniferous volcanism of the central pyrenees developed in subaerial conditions and is mainly represented by the products of explosive eruptions of calc alkaline silicic magmas occasionally associated with calderaforming events the sedimentological record of the permo carboniferous basins of the central pyrenees is characterized by the abundance of crystal rich volcaniclastic deposits reflecting a high crystal content in the erupting magmas 18 40 vol sedimentation during the early permian was dominated by massflows stream floods and braided channels organised in poorly developed alluvial fans at basin margins a wide spectrum of crystal rich deposits can be identified in the permian terrigenous red beds the grouping of these deposits into facies and facies associations allows the recognition of several volcaniclastic marker horizons extending through the central pyrenees these can be used to establish stratigraphical correlations between the different permo carboniferous basins the study of these crystal rich volcaniclastic deposits has revealed that the lower permian crystal rich voleaniclastic deposits of the central pyrenees originated from pyroclastic and reworking processes that sometimes acted simultaneously pyroclastic deposits derived from high intensity explosive magmatic eruptions of rhyodacitic and rhyolitic crystal rich magmas these eruptions generated high eruption columns that occasionally collapsed giving rise to the formation of widespread pyroclastic flows and associated pyroclastic surges the entrance of the eruption columns into the atmosphere had a significant effect on the local weather provoking sporadic storms that led to reworking of pyroclasts by rainfall run off during eruption different crystal concentration processes acted in the eruption columns and in the subsequent pyroclastic flows and overriding ash clouds producing the accumulation of a high volume of crystals in the resulting deposits reworking and redeposition of pyroclastic deposits by fluvial processes further enhanced crystal concentration

chronostratigraphy and paleoclimatology of the lodeve basin france evidence for a pan tropical aridification event across the carboniferous permian boundary abstract paleosols preserved within the carboniferous permian succession of the lodeve basin massif central france change stratigraphically from histosols to calcic vertisols and calcisols to gypsic vertisols and ultimately back to calcic vertisols and calcisols new high precision u pb zircon ages ca idtims for tuff beds within the lodeve and adjacent graissessac basins significantly revise the chronostratigraphy of these and correlated permian terrestrial basins of eastern euramerica under the newly revised chronostratigraphy presented here these stratigraphic changes in morphology indicate a substantial drying of paleoenvironments across the carboniferous permian boundary with a trend toward progressively more arid and seasonal climates through most of the early permian this newly realized chronology provides a paleoenvironmental and paleoclimatic timeline for eastern tropical pangea that is contemporaneous with similar records in western pangea and suggests pan tropical progressive climate change toward aridity and seasonality occurred from the late carboniferous through early permian

compressional wave velocity structure of the upper 350 km under the eastern snake river plain near rexburg idaho relative travel time residuals for teleseismic p and pkikp are used to determine the compressional velocity structure under the eastern snake river plain at rexburg idaho damped least squares inversion of travel time residuals modified from the method of aki indicates a large body of 3 5 2 5 low relative velocity material centered under the northwest edge of the snake river plain less well resolved are high relative velocity bodies one deep under the idaho wyoming border the other 300 km below the idaho batholith comparison with similar velocity mappings of the yellowstone region indicates that the snake river plain low velocity anomaly is an aged extension of the low velocity body under the yellowstone caldera the upper half of the body has vanished in the eastern snake river plain and the lower half is less anomalous than at yellowstone the strong dependence of mantle velocity structure on position under the yellowstone snake river plain volcanic system indicates loss of heat to the surface primarily by advective heat movement by mass movement mechanisms not by conduction no discrimination between propagating rift and upper mantle heat anomaly models of this northeast progressing volcanic system is possible because velocity structures associated with these hot spot models have not been predicted quantitatively upper mantle heat anomaly models thermal plumes chemical plumes gravity anchors explain the observed structure with fewer ad hoc assumptions but propagating rift models cannot be eliminated

controls on permo carboniferous precipitation over tropical pangaea a gcm sensitivity study abstract a series of late paleozoic climate model simulations was developed using the genesis atmospheric general circulation model to investigate the independent roles of gondwanan deglaciation atmospheric co 2 rise and regional tectonism on the long term 10 6 yr evolution of continental precipitation over tropical pangaea the model results indicate that either deglaciation or a co 2 increase from 1 to 8 present atmospheric levels could have caused substantial drying and warming at low latitudes a result that is consistent with late paleozoic proxy records yet the atmospheric processes that led to drying differ between these cases the deglaciation of gondwana reduces low latitude temperature gradients in the southern hemisphere decreasing by as much as 60 the meridional overturning in the southern hemisphere winter cell of the hadley circulation the decline in overturning reduces convective precipitation over equatorial pangaea in contrast high levels of co 2 have little effect on the large scale meridional overturning circulation but increase continental temperatures leading to high evaporation rates and reduced available soil moisture the source of convective precipitation on land in comparison to deglaciation and p co 2 regional uplift erosion of the central pangaean mountains cpms has a secondary effect on tropical precipitation in genesis and cannot explain the long term aridification and warming of western pangaea we suggest that the deglaciation of gondwana and a concomitant rise in atmospheric p co 2 could explain much of the late paleozoic climate change over low latitude pangaea

morphology and distribution of fossil soils in the permo pennsylvanian wichita and bowie groups north central texas usa implications for western equatorial pangean palaeoclimate during icehouse greenhouse transition analysis of stacked permo pennsylvanian palaeosols from north central texas documents the influence of palaeolandscape position on pedogenesis in aggradational depositional settings palaeosols of the eastern shelf of the midland basin exhibit stratigraphic trends in the distribution of soil horizons structure rooting density clay mineralogy and colour that record long term changes in soil forming conditions driven by both local processes and regional climate palaeosols similar to modern histosols ultisols vertisols inceptisols and entisols all bearing morphological mineralogical and chemical characteristics consistent with a tropical humid climate represent the late pennsylvanian suite of palaeosol orders palaeosols similar to modern alfisols vertisols inceptisols aridisols and entisols preserve characteristics indicative of a drier and seasonal tropical climate throughout the lower permian strata the changes in palaeosol morphology are interpreted as being a result of an overall climatic trend from relatively humid and tropical moist conditions characterized by high rainfall in the late pennsylvanian to progressively drier semi arid to arid tropical climate characterized by seasonal rainfall in early permian time based on known late palaeozoic palaeogeography and current hypotheses for atmospheric circulation over western equatorial pangea the pennsylvanian palaeosols in this study may be recording a climate that is the result of an orographic control over regionalscale atmospheric circulation the trend towards a drier climate interpreted from the permian palaeosols may be recording the breakdown of this preexisting orographic effect and the onset of a monsoonal atmospheric circulation system over this region

intensifying aeolian activity following the end permian mass extinction evidence from the late permian early triassic terrestrial sedimentary record of the ordos basin north china

anatomy of a strike slip fault controlled sedimentary basin permian of the southern pyrenees spain this study is mainly concerned with a 55 km long east west oriented strike section through a thick succession of dominantly clastic post variscan deposits in the spanish pyrenees south of andorra a subdivision into three formations can be made two formations of stephanian age composed of volcanic rocks and fluviatile sediments respectively and one of probable permian age which has been studied in detail and is entirely composed of terrestrial redbeds these three formations are characterised by large variations in thickness along strike thicknesses vary from 0 to 800 m in the volcanics from 0 to 300 m in the stephanian fluviatile sediments and from 0 to 1500 m in the permian redbeds the geometry of the sedimentary bodies in all three formations suggests deposition in an east west oriented graben like depression a conclusion which is confirmed by detailed sedimentological analysis of the permian rocks the vertical succession of permian sediments can be subdivided in six major basinfill sequences which unconformably overlie each other internally the basinfill sequences are built up of one or more coarsening upward fining upward cycles the genesis of these cycles is directly related to dip slip movement along the basin boundary faults whereas the unconformities between the basinfill sequences indicate that periods of basin subsidence and sedimentation were followed by periods of deformation and erosion these changes in tectonic regime as reflected in the sedimentary sequences are interpreted to indicate alternating phases of transtension and transpression in a strike slip zone other sedimentological observations substantiate this interpretation the basin depocentre shifted in space and time which resulted in the observed large variations in sediment thickness along strike together with eastward paleocurrent directions along the basin axis transtension was accompanied by outpouring of andesitic lavas and drape folding on a large scale during transpressional phases normal faults changed character to reverse faults while folding uplift and subsequent erosion resulted in the formation of intrabasinal unconformities alternation of transpressive and transtensive conditions should be the result of movement along non planar fault surfaces in a major strike slip zone a separate structural study of the variscan basement of the studied basin revealed the existence of a dextral simple shear deformation generation of probable stephano permian age simple shear in the basement on the one hand and brittle superficial strike slip faulting involving transtension and transpression on the other are considered to be expressions of the same regional stress field at different levels in the earth s crust

sequence stratigraphy and onlap history of the donets basin ukraine insight into carboniferous icehouse dynamics abstract the degree to which permo carboniferous cyclothemic successions archive evidence for long term variations in ice volume during the late paleozoic ice age is insufficiently resolved here we develop the sequence stratigraphy and onlap offlap history for a 33 my interval of the carboniferous using the u pb calibrated succession of the donets basin ukraine in order to assess the relationship between sea level high latitude changes in glacial extent and climate integrated subsurface and outcrop data permit meter scale correlation of 242 biostratigraphically constrained limestones and coals and in turn individual cyclothems across 250 km of the donets basin rapid uniform subsidence and basinwide continuity of marker beds indicate pennsylvanian deposition under relatively stable tectonic conditions three scales of sequences avg durations of 140 ky 480 ky and 1 6 my are recognized on the basis of stratigraphic stacking patterns and basinwide architecture of marine to terrestrial facies assemblages the hierarchy of sequences and the geographic and stratigraphic positions of shifts in base level sensitive facies across the donets ramp permit the construction of an onlap offlap history at a sub 400 ky scale major sea level lowstands occur across the mid carboniferous boundary and during the early moscovian these lowstands coincide with glacial maxima inferred from high latitude glacigenic deposits the middle to late pennsylvanian is characterized by a stepwise onlap culminating in an earliest gzhelian highstand suggesting contraction of carboniferous ice sheets prior to the initiation of early permian glaciation the stratigraphic position of climate sensitive facies within individual donets cyclothems indicates a turnover from seasonal sub humid or semi arid climate to everwet conditions during the late lowstand and maximum ice sheet accumulation comparison of the stratigraphic and aerial distribution of coals and evaporites in the donets basin with the onlap offlap history further indicates everwet conditions during lowstands and inferred glacial maxima and drier climate during onlap and inferred ice sheet contraction at the intermediate 0 8 to 1 6 my and long 106 yr time scales taken together the relationship between inferred climate and glacioeustasy suggests a likely teleconnection between high latitude ice sheet behavior and low latitude atmospheric dynamics

inversion of small basins effects on structural variations at the leading edge of the axial zone antiformal stack southern pyrenees spain the southern axial zone of the pyrenees consists of a foreland dipping system of thrusts and backthrusts forming the leading edge of a basement involved antiformal stack several small stephanian permian extensional basins were strongly inverted during the pyrenean cainozoic orogeny and controlled thrust geometry and kinematics causing lateral structural variation palinspastic restoration reveals three main grabens erill castell estac and gramos basins capped by undeformed triassic strata in the lower orri and erta thrust sheets the overlying nogueres thrust sheet partitioned into several slices contains smaller basins northern basins the erill castell half graben with a steeply dipping sedimentary infill was inverted along its border fault and extruded by bedding parallel backthrusts the narrow thick estac basin which was less deformed internally was a heterogeneity causing major lateral variation in the system the gramos basin originally wide and covered by a gentle unconformity angle was also inverted along its border fault but caused less lateral variation in the thrust system the northern basins appear only in the western part of the present day nogueres thrust sheet where minor units are strongly stacked and rotated in the east thrust slices are large and shallow dipping the study case is a good example of complex 3d thrust development influenced by the initial geometry of a heterogeneous basin system

a review of crust and upper mantle structure studies of the snake river plain yellowstone volcanic system a major lithospheric anomaly in the western u s a abstract the snake river plain yellowstone volcanic system is one of the largest basaltic volcanic field in the world here there is clear evidence for northeasterly progression of rhyolitic volcanism with its present position in yellowstone many theories have been advanced for the origin of the snake river plain yellowstone system yellowstone and eastern snake river plain have been studied intensively using various geophysical techniques some sparse geophysical data are available for the western snake river plain as well teleseismic data show the presence of a large anomalous body with low p and s wave velocities in the crust and upper mantle under the yellowstone caldera a similar body in which compressional wave velocity is lower than in the surrounding rock is present under the eastern snake river plain no data on upper mantle anomalies are available for the western snake river plain detailed seismic refraction data for the eastern snake river plain show strong lateral heterogeneities and suggest thinning of the granitic crust from below by mafic intrusion available data for the western snake river plain also show similar thinning of the upper crust and its replacement by mafic material the seismic refraction results in yellowstone show no evidence of the low velocity anomalies in the lower crust suggested by teleseismic p delay data and interpreted as due to extensive partial melting however the seismic refraction models indicate lower than normal velocities and strong lateral inhomogeneities in the upper crust particularly obvious in the refraction data are two regions of very low seismic velocities near the mallard eake and sour creek resurgent domes in the yellowstone caldera the low velocity body near the sour creek resurgent dome is intepreted as partially molten rock together with other geophysical and thermal data the seismic results indicate that a sub lithospheric thermal anomaly is responsible for the time progressive volcanism along the eastern snake river plain however the exact mechanism responsible for the volcanism and details of magma storage and migration are not yet fully understood

asymmetric shallow mantle structure beneath the hawaiian swell evidence from rayleigh waves recorded by the plume network author posting the author s 2011 this article is posted here by permission of john wiley sons for personal use not for redistribution the definitive version was published in geophysical journal international 187 2011 1725 1742 doi 10 1111 j 1365 246x 2011 05238 x

a deep low velocity body under the yellowstone caldera wyoming delineation using teleseismic p wave residuals and tectonic interpretation in previously published papers iyer 1975 iyer and stewart 1977 iyer 1979 evidence was presented for the presence of a large body of anomalous material with compressional velocities considerably lower than normal from the surrounding rock in the crust and upper mantle under yellowstone national park wyoming in this paper we give a detailed analysis of p residual data from the 26 element telemetered seismic array and three groups of portable stations operated by the u s geological survey in the yellowstone region using a variety of analytical techniques we delineate the shape of the low velocity body determine the velocity structure inside the body and interpret the nature of the material that constitutes the body we will also outline some tectonic implications of our model the spectacular surface geothermal phenomena for which yellowstone is famous result from deep seated volcanism the volcanic evolution of yellowstone is discussed by christiansen and blank 1972 and summarized by eaton and others 1975 briefly the geothermal manifestations in yellowstone are results of three cycles of quaternary volcanism each culminating in a devastating pyroclastic eruption and resulting in large collapse calderas and predominantly rhyolitic flows the oldest cycle ended about 1 9 m y ago forming a caldera from island park to perhaps the central part of the present yellowstone caldera the second cycle climaxed about 1 2 m y ago and was confined to the island park caldera the third cycle began soon after the second and is responsible for the 75 by 45 km yellowstone caldera as it is outlined today this caldera is the result of a catastrophic eruption approximately 600 000 yr ago the most recent episode of volcanism probably began about 150 000 yr ago in the western half of the caldera near old faithful geyser and the youngest flows in yellowstone about 70 000 yr old are probably associated with this episode

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

on ach or how reliable is regional teleseismic delay time tomography abstract ach named after aki et al 1976 bull seismol soc am 66 501 524 aki et al 1977 j geophys res 82 277 296 is a standard widely used method for three dimensional seismic imaging of the earth the fundamental hypothesis which underlies the method is that the time residuals generated outside the given target volume from the seismic source to the bottom of the modelled zone are approximately constant across the seismic array the main purpose of this study is to check this assumption we computed travel times for a given station and event distribution using a three dimensional global earth model taken from seismic tomography we found that the relative residuals generated outside the target volume are not negligible and that the fundamental hypothesis underlying ach is thus not verified these deviations are generated in the lower and or upper mantle and the corresponding proportions are entirely dependent on the raypaths the bias in the inverted model is statistically similar to the input model outside the target volume we thus recommend caution in any interpretations involving ach generated models a secondary somewhat independent outcome of this study is that fermat s principle used to linearise the inverse problem in ray theory based tomography seems to be valid without any restrictions given our input model is representative for the true earth for rays with turning points in the lower mantle for rays with turning points in the upper mantle the constant raypath approximation is probably not true this applies to global tomography as well

p wave velocity structure of the uppermost mantle beneath hawaii from traveltime tomography summary we examine the p wave velocity structure beneath the island of hawaii using p wave residuals from teleseismic earthquakes recorded by the hawaiian volcano observatory seismic network the station geometry and distribution of events makes it possible to image the velocity structure between y40 and 100 km depth with a lateral resolution of y15 km and a vertical resolution of y30 km for depths between 40 and 80 km p wave velocities are up to 5 per cent slower in a broad elongated region trending se nw that underlies the island between the two lines defined by the volcanic loci no direct correlation between the magnitude of the lithospheric anomaly and the current level of volcanic activity is apparent but the slow region is broadened at y19 8un and narrow beneath kilauea in the case of the oceanic lithosphere beneath hawaii slow seismic velocities are likely to be related to magma transport from the top of the melting zone at the base of the lithosphere to the surface thermal modelling shows that the broad elongated low velocity zone cannot be explained in terms of conductive heating by one primary conduit per volcano but that more complicated melt pathways must exist

permian tetrapod footprints from the spanish pyrenees abstract paleozoic tetrapod footprints are a common and well known phenomenon in almost all large european countries except for spain here we report on hitherto unpublished vertebrate tracks from permian red beds of the south central pyrenees that with regard to their relative abundance diversity and quality of preservation are suitable to fill this gap of knowledge the described tracks come from two localities in muddy to fine grained sandy alluvial plain deposits in the lower third of the peranera formation of the erill castell basin near les iglesies northern catalonia the tracks can be assigned to five ichnogenera i e batrachichnus woodworth 1900 limnopus marsh 1894 varanopus moodie 1929 hyloidichnus gilmore 1927 and dromopus marsh 1894 that we interpret as footprints of temnospondyls captorhinomorphs and araeoscelids or similarly sized sauropsids with a lacertoid foot pattern this ichnofossil assemblage is most similar to ichnofaunas from the hermit formation of the grand canyon arizona the upper abo and robledo mountains formations of new mexico and the main trace fossil site of the tiddas basin morocco suggesting a late early permian artinskian age for this stratigraphic level of the peranera formation considering the relative abundance and diversity of captorhinomorph footprints the new spanish tracefossil localities may cover the onset of the early permian radiation of non diapsid eureptiles the thick late paleozoic red bed successions of the south central pyrenees have the potential to also bear footprints of otherwise unknown early therapsids so systematic fossil prospecting of this area is strongly recommended

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

climatic and biotic changes around the carboniferous permian boundary recorded in the continental basins of the czech republic abstract the paper provides an overview of a several decades long study of transitional carboniferous permian stephanian c autunian sedimentary successions in continental basins of the czech part of the bohemian massif these predominantly monotonous fluvial red beds intercalate with laterally widespread grey to variegated sediments of dominantly lacustrine origin both fossil and climatic records show that apart from a generally known long term climatic shift to drier conditions in early permian the climate oscillated on several time scales throughout the study interval climatic indicators in the red beds part of the succession include palaeosols ranging between red vertisols and vertic calcisols suggesting strongly seasonal dry sub humid climate this is in agreement with the rarity of plant remains which were mostly completely oxidised and only rarely preserved as plant impression in red mudstones or as silicified mostly gymnosperm woods in sandy channel fills silicification instead of coalification was the dominant fossilisation process during red beds deposition even drier possibly semi arid climate may be indicated by spatially and temporarily restricted bimodal sandstones dominated by well rounded quartz grains and interpreted as eolian in origin periods of moist sub humid or even humid climate were accompanied by formation of perennial lakes containing grey laminated mudstones dark grey bituminous mudstones or limestones muddy limestones chert layers or even spatially restricted coals some of them however of economic importance shorter climatic oscillations operating on a scale of tens to possibly hundreds of thousands of years are represented by transgressive regressive lacustrine cycles followed by significant changes in lake water salinity reflected by boron content the fossil record indicates the presence of dryland and wetland biomes in basinal lowlands although their proportions varied significantly as the climate changed during deposition of red beds the alluvial plain was vegetated dominantly by dryland biome assemblages the composition of these assemblages is indicated by fairly common silicified gymnosperm cordaitalean and coniferous woods in sandstone conglomerate fluvial channel bedforms and by poorly preserved impressions of walchian conifer shoots and cordaitalean leaves in associated mudstone intercalations this is in agreement with sub vertical root rhizolites and haloes in calcic vertisols occurrence of wet spots colonised by wetland assemblages is indicated by rather exceptional findings of silicified calamite stems in fluvial red beds associated with gymnospermous woods during the humid intervals parts of the basinal lowlands were occupied by lakes surrounded by broad belts of wetland biome floras during the stephanian c most of these floras were dominated by tree ferns calamites and sub dominant pteridosperms local peat swamps were colonised by lycopsids including sigillaria brardii asolanus camptotaenia and even some lepidodendrid lycopsids in contrast the fossil record of stephanian c dryland floras is rarely preserved in lacustrine sediments the fossil record of autunian lakes however suggests increasing proportions of dryland elements including conifers and peltasperms the response of lacustrine faunas to climatic oscillations around the carboniferous permian transition is less prominent than that of plants the origin of the transition between the local elonichthys sphaerolepis and acanthodes gracilis bio ecozones around the carboniferous permian boundary is impossible to deduce from the existing fossil record

constraining the permian triassic transition in continental environments stratigraphic and paleontological record from the catalan pyrenees ne iberian peninsula abstract the continental permian triassic transition in southern europe presents little paleontological evidence of the permian mass extinction and the subsequent faunal recovery during the early stages of the triassic new stratigraphic sedimentological and paleontological analyses from middle upper permian to lower middle triassic deposits of the catalan pyrenees ne iberian peninsula allow to better constrain the permian triassic succession in the western tethys basins and provide new bio chronologic data for the first time a large vertebra attributed to a caseid synapsid from the middle permian is reported from the iberian peninsula one of the few reported from western europe osteological and ichnological records from the triassic buntsandstein facies reveal a great tetrapod ichnodiversity dominated by small to medium archosauromorphs and lepidosauromorphs rhynchosauroides cf schochardti r isp 1 and 2 prorotodactylus rotodactylus an undetermined morphotype a and to a lesser degree large archosaurians chirotheriids overall suggesting a late early triassic early middle triassic age this is in agreement with recent palynological analyses in the buntsandstein basal beds that identify different lycopod spores and other bisaccate and taeniate pollen types of late olenekian age early triassic the permian caseid vertebra was found in a playa lake setting with a low influence of fluvial water channels and related to the distal parts of alluvial fans in contrast the triassic buntsandstein facies correspond to complex alluvial fan systems dominated by high energy channels and crevasse splay deposits hence a faunal and environmental turnover is observed the pyrenean biostratigraphical data show similarities with those of the nearby western tethys basins and can be tentatively correlated with north african and european basins the triassic pyrenean fossil remains might rank among the oldest continental records of the western tethys providing new keys to decipher the triassic faunal biogeography and recovery

geodetic analysis of dike intrusion and motion of the magma reservoir beneath the summit of kilauea volcano hawaii 1970 1985 we use leveling and trilateration data collected on kilauea volcano to constrain the location of deformation sources caused by magma accumulation intrusion and eruption for the 13 inflationary epochs examined combinations of an expanding point source and one or two opening rectangular dislocations mimic inflation of the summit reservoir and formation of dike s respectively the combined model adequately accounts for the deformation data and is consistent with the seismicity observed during each epoch for 10 deflationary epochs however the data require only a contracting point source confidence in these results is gained by noting that locations of the sources of both inflation and deflation are coincident within the observed uncertainties of the data the function of network geometry and the inversion procedure it appears therefore that magma accumulation at kilauea volcano may be characterized by the growth of dikes during inflation of the summit reservoir drainage of the reservoir on the other hand is not accompanied by significant closure of dikes in contrast to previous studies e g fiske and kinoshita 1969 dvorak et al 1983 that do not include the dislocation or dike growth component of summit magma accumulation and concluded that the source of inflation migrates over a 5 km2 area we find that a single magmatic reservoir source accounts for data collected during all inflationary and deflationary epochs results which compare favorably with those obtained from the point ellipsoid model can be used to estimate the distribution of stresses within the volcano in the near field of the source

co2 forced climate and vegetation instability during late paleozoic deglaciation the late paleozoic deglaciation is the vegetated earth9s only recorded icehouse to greenhouse transition yet the climate dynamics remain enigmatic by using the stable isotopic compositions of soil formed minerals fossil plant matter and shallow water brachiopods we estimated atmospheric partial pressure of carbon dioxide pco2 and tropical marine surface temperatures during this climate transition comparison to southern gondwanan glacial records documents covariance between inferred shifts in pco2 temperature and ice volume consistent with greenhouse gas forcing of climate major restructuring of paleotropical flora in western euramerica occurred in step with climate and pco2 shifts illustrating the biotic impact associated with past co2 forced turnover to a permanent ice free world

a dynamic balance between magma supply and eruption rate at kilauea volcano hawaii the dynamic balance between magma supply and vent output at kilauea volcano is used to estimate both the volume of magma stored within kilauea volcano and its magma supply rate throughout most of 1991 a linear decline in volume flux from the kupaianaha vent on kilauea s east rift zone was associated with a parabolic variation in the elevation of kilauea s summit as vent output initially exceeded then lagged behind the magma supply to the volcano the correspondence between summit elevation and tilt established with over 30 years of data provided daily estimates of summit elevation in terms of summit tilt the minimum in the parabolic variation in summit tilt and elevation or zero elevation change occurs when the magma supply to the reservoir from below the volcano equals the magma output from the reservoir to the surface so that the magma supply rate is given by vent flux on that day the measurements of vent flux and tilt establish that the magma supply rate to kilauea volcano on june 19 1991 was 217 000 10 000 m3 d or 0 079 0 004 km3 yr this is close to the average eruptive rate of 0 08 km3 yr between 1958 and 1984 in addition the predictable response of summit elevation and tilt to each east rift zone eruption near puu oo since 1983 shows that summit deformation is also a measure of magma reservoir pressure given this the correlation between the elevation of the puu oo lava lake 4 km uprift of kupaianaha and 18 km from the summit and summit tilt provides an estimate for magma pressure changes corresponding to summit tilt changes the ratio of the change in volume to the change in reservoir pressure dv dp during vent activity may be determined by dividing the ratio of volume erupted to change in summit tilt dv dtilt by the ratio of pressure change to change in summit tilt dp dtilt this measure of dv dp when combined with laboratory measurements of the bulk modulus of tholeitic melt provides an estimate of 240 50 km3 for the volume of kilauea s magma reservoir this estimate is much larger than traditional estimates but consistent with seismic tomographic imaging and geophysical modeling of kilauea s magma system

shifts in late paleozoic atmospheric circulation over western equatorial pangea insights from pedogenic mineral δ18o compositions the d 18 o values of pedogenic calcites phyllosilicates and iron oxyhydr oxides from fossil soils throughout the southwestern united states show systematic paleolatitudinal and temporal trends that indicate a significant change in soil moisture conditions and atmospheric circulation patterns over southwestern euramerica throughout latest pennsylvanian and early permian time a progressive depletion of as much as 6 in mineral 18 o values with increasing distance northward to 108 of the paleoequator indicates a weakening or disruption of zonal easterly flow over the study area by latest pennsylvanian time furthermore elevated d 18 o values suggest a proximal source of paleoprecipitation over the study area perhaps due to initiation of reversed equatorial flow over tropical southwestern euramerica coupling of the geographic and temporal trends defined by pedogenic mineral d 18 o values with those defined by climatically sensitive paleosol pedotypes in the study area along with overall elevated mineral d 18 o values provides some of the strongest evidence that northern hemisphere monsoonal circulation was well established over pangea by early permian time

anomalous heat flow and geoid across the cape verde rise evidence for dynamic support from a thermal plume in the mantle summary we describe results from 200 heat flow measurements across the cape verde rise in the north atlantic they show that the heat flow through normal 125 myr old crust is 45 5 3 4mwm 2 close to the prediction for a lithospheric plate model heat flow increases towards the centre of the rise reaching a maximum of 16 4 mw m 2 above the normal oceanic value the concommitant geoid anomaly at the centre of the rise is 7 6 0 3 m and the depth anomaly is 1900 200 m the anomalous heat flow geoid and bathymetric values are used to constrain a variety of theoretical models of hot spot mechanisms lithospheric reheating models alone whether involving transient or sustained thinning of the lithosphere fail to model the broad heat flow anomaly and the long duration of uplift and volcanism observed on the cape verde rise axisymmetric convection models provide a better fit to the observed data and suggest that the swell is a consequence primarily of dynamic uplift generated by an ascending thermal plume in the underlying mantle uplift caused by expansion of the solid lithosphere is of smaller importance the observed geoid bathymetry and heat flow anomalies are reproduced well using convection models with upper mantle viscosities of 2 4 times 1020 pa s and a coefficient of thermal expansion in the range 2 0 2 5 times 10 5 k 1 the effect of melting in the ascending plume is to buffer the heat flow anomalies in the case of the cape verde rise partial melting is minimal but its effect on other hotspots will be to limit observed heat flow anomalies at the surface to less than 20 25 mw m 2

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

permo carboniferous climate early pennsylvanian to late permian climate development of central europe in a regional and global context a well justified stratigraphical correlation of continental successions and new palaeogeographic reconstruction of pangaea reveal new insights into the northern pangaean climate development influenced by palaeogeography palaeotopography glacio eustatic sealevel changes and ocean currents the overall permo carboniferous aridization trend was interrupted by five wet phases these are linked to the gondwana icecap the aridization and weakening of wet phases over time were not only caused by the drift of northern pangaea to the arid climatic belt but also by the successive closure of the rheic ocean which caused the expansion of arid semi arid environments in the lower middle permian the end of the gondwana glaciation rearranged ocean circulation leading to a cold coast parallel ocean current west of northern pangaea blocking moisture coming with westerly winds the maximum of aridity was reached during the roadian wordian the trans pangaean mountain belt was non existent its single diachronous parts never exceeded an average elevation of 2000 m the maximum elevation shifted during time from east to west the hercynian orogen never acted as an orographic east west barrier and the inter tropical convergence zone was widely displaced causing four seasons dry summer winter wet spring autumn at the equator and a strong monsoon system the climate history of the european realm during the late carboniferous pennsylvanian and permian is stored in many solitary basins fig 1 within the hercynian orogen and the foreland basin the story of westphalian climate is well known because of the numerous investigations of the coal bearing variscan foredeep the younger westphalian is characterized by a slight aridization abbink van kronijnenburgvan cittert 2003 oplustil 2004 which was accompanied by an increase of seasonality nevertheless the environment was strongly influenced by the ocean and epi continental seas with multiple transgression events the last extensive marine ingression was the aegir mansfield band westphalian b c the post westphalian climate development is more differentiated and

three dimensional velocity structure of the kilauea caldera hawaii high resolution velocity models 0 5 km resolution of the kilauea caldera region are obtained by the tomographic inversion of both p and s wave arrival times data are from the permanent hawaiian volcano observatory hvo seismic network a broadband seismic network and a temporary array of stations centered on the southern boundary of the caldera a low velocity p wave anomaly is imaged centered on the southeastern edge of the caldera with a velocity contrast of about 10 and a volume of 27 km the vp vs model mimics the spatial extent of the p wave anomaly but is partitioned into two discrete anomalous volumes centered on the southern boundary of the caldera and on the upper east rift of the volcano the corresponding poisson s ratio in these zones is high 0 25 0 32 which is consistent with a densely cracked hot volume which may contain partial melt the large scale features of the models are consistent with results obtained from an earlier larger scale 2 km resolution tomographic image of kilauea volcano based on hvo network data

p and s wave upper mantle seismic velocity structure beneath the northern apennines new evidence for the end of subduction orogeny in the geologically young northern apennines is explained by the eastward retreat of a convergence zone in which adriatic lithosphere subducts to the west it is unclear however whether all of the lithosphere or only the lower portion has subducted since 15 ma when the convergence zone lay near corsica we combine teleseismic p and s wave arrival time data from the retreat seismic network 2003 2006 and surrounding permanent stations to estimate tomographic images of the upper mantle structure beneath the northern apennines we image a vertically oriented slab that that extends to only 300 km depth our slab termination is shallower than previous studies but is confirmed by resolution tests furthermore our images resolve the southern edge of the northern apennines slab at 43 n with no deep continuity with any slab segment to the south as earlier proposed our results suggest that only a 300 400 km strip of lithosphere has subducted since 15 ma beneath the northern tyrrhenian sea a length roughly equivalent to the distance from the present day west coast of corsica to the crest of the northern apennines although not a definitive indicator the largely aseismic vertical slab configuration and its limited extent coupled with other volcanic and geophysical indicators suggests the delamination scenario of bird 1979 in which only the lower portion of the continental lithosphere subducts

cumulate xenolith in oahu hawaii implications for deep magma chambers and hawaiian volcanism the maximum depth at which large 1000 km3 terrestrial mafic magma chambers can form has generally been thought to be the moho which occurs at a mean depth of about 35 kilometers beneath the continents and 8 kilometers beneath ocean basins however the presence of layers of cumulus magnesium rich spinel and olivine and intercumulus garnet in an unusual mantle xenolith from oahu hawaii suggests that this rock is a fragment of a large magma chamber that formed at a depth of about 90 kilometers hawaiian shield building magmas may pond and fractionate in such magma chambers before continuing their ascent this depth is at or near the base of the 90 million year old lithosphere beneath oahu thus rejuvenated stage alkalic magmas containing mantle xenoliths evidently also originate below the lithosphere

late paleozoic continental warming of a cold tropical basin and floristic change in western pangea abstract an increase in mineral crystallization temperatures of 13 3 c is preserved in paleosol profiles ancient soils within a stratigraphic interval of cooler than soil temperatures observed in the modern lowland tropics to permian age soil mineral crystallization temperatures which are equivalent to or slightly exceed soil temperatures observed in modern lowland tropics this record of mineral crystallization temperatures occurs at a time when some sources indicate the onset of the largest single glaciation of the late paleozoic ice age the temperature change indicated by these paleosol minerals is accompanied by a unidirectional irreversible change in the composition of tropical lowland vegetation this transition delineates the magnitude and characteristics of vegetational changes in the modern tropics that might accompany continued atmospheric warming times of low surface temperatures coincide with a typical late pennsylvanian tropical pangean wet biome dominated by sigillaria macroneuropteris other pteridosperms and marattialean ferns this plant assemblage is replaced spatially by a xeromorphic biome dominated by conifers callipterids and other seed plants characteristic of the tropical permian across western and central pangea the fully xeromorphic flora appears initially in sub meter scale beds within outcrops otherwise characterized by wet flora and becomes predominant once peak surface temperatures were reached in the earliest permian a narrow stratigraphic interval 20 m separates these two biomes in the region marking what was to be a permanent floristic change in western pangea the lower diversity floras of seasonally dry habitats apparently migrated from drier extrabasinal areas into increasingly dry landscapes formerly dominated by the wet biome this study documents the regional disappearance of an entire tropical biome with a net reduction of biodiversity accompanying rapid environmental warming

pennsylvanian coniferopsid forests in sabkha facies reveal the nature of seasonal tropical biome pennsylvanian fossil forests are known from hundreds of sites across tropical pangea but nearly all comprise remains of humid coal forests here we report a unique occurrence of seasonally dry vegetation preserved in growth position along 5 km of strike in the pennsylvanian early kasimovian missourian of new mexico united states analyses of stump anatomy diameter and spatial density coupled with observations of vascular traces and associated megaflora show that this was a deciduous mixed age coniferopsid woodland 100 trees per hectare with an open canopy the coniferopsids colonized coastal sabkha facies and show tree rings confirming growth under seasonally dry conditions such woodlands probably served as the source of coniferopsids that replaced coal forests farther east in central pangea during drier climate phases thus the newly discovered woodland helps unravel biome scale vegetation dynamics and allows calibration of climate models

aridification across the carboniferous permian transition in central equatorial pangea the catalan pyrenean succession ne iberian peninsula abstract the carboniferous permian terrestrial successions record a global climatic shift from icehouse to hothouse conditions our multidisciplinary study documents an aridification trend throughout the 1000 m thick composite terrestrial succession of the western catalan pyrenees ne iberian peninsula representing this time period the detailed stratigraphic framework integrates sedimentology paleopedology biochronology plant fossils and tetrapod footprints and geochronology paleomagnetism additional absolute age correlation is also carried out the new and reviewed data show that the late carboniferous wet environments with short drought periods progressively changed to a strong seasonal semi arid and arid climate with short humid periods through the early permian this paleoclimatic trend supports the previously suggested aridification of the pangean pan tropical belt and supports the hypothesis of the influence of the recurrent climatic fluctuations in central pangea being tentatively correlated to the southern gondwanan glaciation deglaciation periods therefore the carboniferous permian terrestrial succession from the catalan pyrenees emerges as a continuous record that can help to constrain late paleozoic paleoenvironmental events

imaging the crustal magma sources beneath mauna loa and kilauea volcanoes hawaii three dimensional seismic p wave traveltime tomography is used to image the magma sources beneath mauna loa and kilauea volcanoes hawaii high velocity bodies 6 4 km s in the upper 9 km of the crust beneath the summits and rift zones of the volcanoes correlate with zones of high magnetic intensities and are interpreted as solidified gabbro ultramafic cumulates from which the surface volcanism is derived the proximity of these high velocity features to the rift zones is consistent with a ridge spreading model of the volcanic flank southeast of the hilina fault zone along the south flank of kilauea low velocity material

variations in magma supply rate at kilauea volcano hawaii when an eruption of kilauea lasts more than 4 months so that a well defined conduit has time to develop magma moves freely through the volcano from a deep source to the eruptive site at a constant rate of 0 09 km3 yr at other times the magma supply rate to kilauea estimated from geodetic measurements of surface displacements may be different for example after a large withdrawal of magma from the summit reservoir such as during a rift zone eruption the magma supply rate is high initially but then lessens and exponentially decays as the reservoir refills different episodes of refilling may have different average rates of magma supply during four year long episodes in the 1960s the annual rate of refilling varied from 0 02 to 0 18 km3 yr bracketing the sustained eruptive rate of 0 09 km3 yr for decade long or longer periods our estimate of magma supply rate is based on long term changes in eruptive rate we use eruptive rate because after a few dozen eruptions the volume of magma that passes through the summit reservoir is much larger than the net change of volume of magma stored within kilauea the low eruptive rate of 0 009 km3 yr between 1840 and 1950 compared to an average eruptive rate of 0 05 km3 yr since 1950 suggests that the magma supply rate was lower between 1840 and 1950 than it has been since 1950 an obvious difference in activity before and since 1950 was the frequency of rift zone eruptions eight rift zone eruptions occurred between 1840 and 1950 but more than 20 rift zone eruptions have occurred since 1950 the frequency of rift zone eruptions influences magma supply rate by suddenly lowering pressure of the summit magma reservoir which feeds magma to rift zone eruptions a temporary drop of reservoir pressure means a larger than normal pressure difference between the reservoir and a deeper source so magma is forced to move upward into kilauea at a faster rate

comparisons of dynamic triggering near beijing china following recent large earthquakes in sumatra 1 dynamic triggering around the fangshan pluton near beijing is repeatedly identified here we report clear triggered events in this region during the surface waves of the 2012 mw8 6 sumatra earthquake however we do not find any triggered events during the g2 waves of the mw8 6 event and the surface waves of the mw8 2 sumatra earthquake that occurred two hours later the peak ground velocities of the 2012 mw8 2 event are around the apparent triggering threshold of 0 1 0 2 cm s in this region hence the fact that this event did not trigger does not require an influence of elapsed time since last trigger the mw8 6 mainshock but is consistent with it the lack of triggering during the g2 wave of the 2012 mw8 6 mainshock may be caused by relatively weak surface wave signals in the intermediate period of 100 10 s

a geomagnetic polarity timescale for the permian calibrated to stage boundaries the reverse polarity kiaman superchron has strong evidence for at least three or prob ably four normal magnetochrons during the early permian normal magnetochrons are during the early asselian base ci1r 1n at 297 94 0 33 ma late artinskian ci2n at 281 24 2 3 ma mid kungurian ci3n at 275 86 2 0 ma and roadian ci3r an at 269 54 1 6 ma the mixed polarity illawarra superchron begins in the early wordian at 266 66 0 76 ma the wordian capitanian interval is biased to normal polarity but the basal wuchiapingian begins the beginning of a significant reverse polarity magnetochron lp0r with an overlying mixed polarity interval through the later lopingian no significant magnetostratigraphic data gaps exist in the permian geomagnetic polarity record the early cisuralian magnetochrons are calibrated to a succession of fusulinid zones the later cisuralian and guadalupian to a conodont and fusulinid biostratigraphy and lopingian magnetochrons to conodont zonations age calibration of the magnetochrons is obtained through a bayesian approach using 35 radiometric dates and 95 confidence intervals on the ages and chron durations are obtained the dating control points are most numerous in the gzhelian asselian wordian and changhsingian intervals this significant advance should provide a framework for better correlation and dating of the marine and non marine permian

deep magma transport at kilauea volcano hawaii the shallow part of kilauea s magma system is conceptually well understood long period and short period brittle failure earthquake swarms outline a near vertical magma transport path beneath kilauea s summit to 20 km depth a gravity high centered above the magma transport path demonstrates that kilauea s shallow magma system established early in the volcano s history has remained fixed in place low seismicity at 4 7 km outlines a storage region from which magma is supplied for eruptions and intrusions brittle failure earthquake swarms shallower than 5 km beneath the rift zones accompany dike emplacement sparse earthquakes extend to a decollement at 10 12 km along which the south flank of kilauea is sliding seaward this zone below 5 km can sustain aseismic magma transport consistent with recent tomographic studies long period earthquake clusters deeper than 40 km occur parallel to and offshore of kilauea s south coast defining the deepest seismic response to magma transport from the hawaiian hot spot a path connecting the shallow and deep long period earthquakes is defined by mainshock aftershock locations of brittle failure earthquakes unique to kilauea whose hypocenters are deeper than 25 km with magnitudes from 4 4 to 5 2 separation of deep and shallow long period clusters occurs as the shallow plumbing moves with the volcanic edifice while the deep plumbing is centered over the hotspot recent gps data agrees with the volcano propagation vector from kauai to maui suggesting that pacific plate motion azimuth 293 58 and rate of 7 4 cm yr has been constant over kilauea s lifetime however volcano propagation on the island of hawaii azimuth 3258 rate 13 cm yr requires southwesterly migration of the locus of melting within the broad hotspot deep long period earthquakes lie west of the extrapolated position of kilauea backward in time along a plate motion vector requiring southwesterly migration of kilauea s magma source assumed ages of 0 4 my for kilauea and 0 8 my for mauna loa are consistent with this model younger ages would apply if kilauea began its growth south of the locus of maximum melting as is true for loihi seamount we conclude that kilauea is fed from below the eastern end of the zone of deep long period earthquakes magma transport is vertical below 30 km then sub horizontal following the oceanic mantle boundary separating plagioclase and spinel peridotite then near vertical beneath kilauea s summit the migration of the melting region within the hotspot and kilauea s sampling of different sources within the melting region can explain 1 the long term geochemical separation of

lacustrine deposition and related volcanism in a transtensional tectonic setting upper stephanian lower autunian in the aragon bearn basin western pyrenees spain france abstract stephanian to early autunian lacustrine series are exposed in the aragon bearn basin western pyrenees and comprise two main lithostratigraphic units that represent the unfilling of a closed lake located in a transtensional setting accompanied by extensive pyroclastic deposition the lower lacustrine unit overlies epiclastic conglomerates sandstones and siltstones and it is mainly formed of massive and laminated grey limestones laminated carbonates and grey organic rich tuffaceous siltstones a freshwater probably stratified lake with frequent depth fluctuations is proposed for this first stage limestones show very light 18 o values 10 to 14 pdb believed torepresent a primary isotopic signal which is consistent with an intracontinental setting of the basin and the influx of 18 o depleted meteoric waters derived from the adjacent hercynian mountains a wide spread pyroclastic flow deposit marks the limit with the upper lacustrine unit which comprises the following lithofacies pisolitic dolostones stromatolites massive and laminated dolostones and limestones and variegated siltstones this final stage of the lake infilling is interpreted as a shallow brackish environment the transition between both units is marked by nodular limestones and dolomitization of some limestone layers but the stable isotopic composition remains similar to the lower unit strong evaporative concentration shallow well mixed waters and re equilibration with the atmospheric reservoir are suggested by the heavier 18 o 2to 10 and 13 c 0 to 4 values in the dolomites and the heavier 13 c values in the limestones 1 5 to 2 the lacustrine episode ended with the progradation of an alluvial plain because many documented lacustrine deposits in volcanic settings are poor in carbonates the stephanian autunian series provide a case study for concomitant carbonate and pyroclastic deposition high volcanic inputs are implied by the tuffaceous facies the ubiquitous presence of volcanic and pyroclastic components in both detrital and carbonatic facies and by the numerous intercalated pyroclastic layers several criteria are applied to discriminate subaerial and sublacustrine pyroclastic fall out and flow deposits similar lake sequences are found in other stephanian autunian basins in western europe suggesting that sedimentation in the variscan continental basins reflects the dominant climate of the time

palaeoenvironmental reconstruction and early permian ichnoassemblage from the ne iberian peninsula pyrenean basin this work was supported by the synthesys project e m de taf 2560 at mfn and fr taf 3621 and fr taf 4808 at mnhn http www synthesys info and secretaria d universitats i de recerca del departament d economia i coneixement de la generalitat de catalunya e m expedient number 2013 ctp 00013 at ise m for visits to collections e m received financial support from the pif grant of the geology department at uab field works have been developed on the project vertebrats del permia i el triasic de catalunya i el seu context geologic and evolucio dels ecosistemes amb faunes de vertebrats del permia i el triasic de catalunya ref 2014 100606 based at institut catala de paleontologia and we acknowledge the financial support of the departament de cultura generalitat de catalunya

climate pco2 and terrestrial carbon cycle linkages during late palaeozoic glacial interglacial cycles the late palaeozoic was marked by a series of glacial interglacial cycles geochemical and fossil data suggest a role for terrestrial vegetation carbon cycle feedbacks in the climate response to orbital forcing

lithospheric flexure under the hawaiian volcanic load internal stresses and a broken plate revealed by earthquakes several lines of earthquake evidence indicate that the lithospheric plate is broken under the load of the island of hawai i where the geometry of the lithosphere is circular with a central depression the plate bends concave downward surrounding a stress free hole rather than bending concave upward as with past assumptions earthquake focal mechanisms show that the center of load stress and the weak hole is between the summits of mauna loa and mauna kea where the load is greatest the earthquake gap at 21 km depth coincides with the predicted neutral plane of flexure where horizontal stress changes sign focal mechanism p axes below the neutral plane display a striking radial pattern pointing to the stress center earthquakes above the neutral plane in the north part of the island have opposite stress patterns t axes tend to be radial the m6 2 honomu and m6 7 kiholo main shocks both at 39 km depth are below the neutral plane and show radial compression and the m6 0 kiholo aftershock above the neutral plane has tangential compression earthquakes deeper than 20 km define a donut of seismicity around the stress center where flexural bending is a maximum the hole is interpreted as the soft center where the lithospheric plate is broken kilauea s deep conduit is seismically active because it is in the ring of maximum bending a simplified two dimensional stress model for a bending slab with a load at one end yields stress orientations that agree with earthquake stress axes and radial p axes below the neutral plane a previous inversion of deep hawaiian focal mechanisms found a circular solution around the stress center that agrees with the model for horizontal faults the shear stress within the bending slab matches the slip in the deep kilauea seismic zone and enhances outward slip of active flanks

chronological link between deep seated processes in magma chambers and eruptions permo carboniferous magmatism in the core of pangaea southern pyrenees abstract in the southern pyrenees there are upper carboniferous lower permian sedimentary basins with a significant volume of volcanic material derived from explosive eruptions rhyolitic ignimbrites and andesitic flows these basins are spatially associated with granodiorites and dacitic dykes emplaced in variscan basement rocks u pb shrimp dating of zircons extracted from three granodiorites an andesitic flow a dacitic dyke and six ignimbrites revealed that magmatism occurred over an extended period of thirty eight million years from ca 304 ma to ca 266 ma upper carboniferous middle permian a scattering of zircon ages in each sample shows that the history of melt crystallization was complex with more than one zircon forming event in each magma chamber the prolonged crystallization history was transferred to the product of the eruptions a chronological link between the deep seated magma chambers and processes in eruptions was identified on the basis of four overlapping intervals at ca 309 307 ma upper carboniferous ca 304 296 ma upper carboniferous lower permian ca 294 282 ma lower permian and ca 276 ma lower permian the variation of zircon u th ratios exposes a tendency for an increase in mafic sources as crystallization advances in the permian zircons probably crystallized from melt phases related to both a felsic intermediate metaluminous source from ca 310 293 ma mostly 0 1

a two dimensional seismic investigation of crustal structure under the hawaiian islands near oahu and kauai two expanding spread profiles esps were analyzed in detail to investigate the deep structure of the volcanoes and the underlying oceanic crust near oahu one esp was located on the southeastern submarine flank of kauai esp 10 and the other was located directly over the ridge axis between oahu and molokai esp 5 two dimensional models of the entire crust were obtained by iterative comparison of both travel times and relative amplitudes of arrivals on the ray theoretical synthetic seismograms with those in the data a 2 4 km vertical offset in the preexisting crust inferred to be a large fault zone was found near the midpoint of esp 10 this fault may form the southern wall of a graben or half graben in which kauai sits the layering and seismic velocities of the preexisting oceanic crust near kauai have remained unmodified by the load of the volcanic pile esp 5 is located over a shallow 4 km thick basin filled with volcaniclastics and possibly volcanic flows bordered by the islands of oahu and molokai penguin bank and two buried rift zones under this basin the main volcanic edifice is 4 to 5 km thick the top of the preexisting oceanic crust is 8 to 9 km below sea level and is 3 to 4 km lower than the crust away from the islands the underlying oceanic crust is 6 to 7 km thick excluding the moho transition zone which is of normal thickness and at a depth from 15 to 16 km the existence of a large subcrustal plutonic body is refuted

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

the late palaeozoic early mesozoic from the catalan pyrenees spain 60 myr of environmental evolution in the frame of the western peri tethyan palaeogeography the eastern catalan pyrenees form the southernmost segment of the pyrenean axial zone they experienced complex multistage process as the result of both the variscan and the pyrenean orogenic cycles after the late palaeozoic several small extensional sub basins were filled by continental successions as a response to the changing tectonic setting within the frame of the southwestern europe this stratigraphic record perfectly exposed in the studied eastern pyrenean areas preserves the signatures of the late palaeozoic pangea break up during the progressive dismantling of the variscan chain up to the triassic diffused extension despite structural network being severely affected by cenozoic reworking the stratigraphic framework can be unravelled by the detailed sedimentological and stratigraphical analysis of the well exposed sequences in short this paper addresses facies patterns and architectural elements of late carboniferous permian triassic continental sections studied in the catalan pyrenees and aims to use these signatures for correlation not only at a regional scale but also within the broader picture of the southwestern europe our stratigraphical reconstruction clearly demonstrates that the thick studied succession consists of fluvial lacustrine basal units affected by intense volcanic activity and overlaying predominantly fluvial fining upwards units for each unit several lithofacies architectural elements and bounding surfaces of different order have been identified and their lateral and vertical staking characterized deposition and erosion processes are controlled by alternating periods of tectonic activity producing different stages of high and low subsidence the uplift of the sub basin margins and subsequent extended erosive events marked by angular unconformities on the strength of the major rank bounding surfaces analysis the studied sedimentary packages have been grouped into different tectono stratigraphic units and then correlated they have been contextualized within the latest palaeogeographic reconstructions of the studied sector contributing to detail the role of the study area within the frame of the s european palaeogeography

pedogenic record of climate change across the pennsylvanian permian boundary in red bed strata of the cutler group northern new mexico usa abstract the upper pennsylvanian to lowermost permian el cobre canyon and arroyo del agua formations are well exposed in a 250 m section in the chama basin in northern new mexico this is one of the few known successions of fossiliferous red bed siliciclastic sediments encompassing the pennsylvanian permian boundary in the american southwest and thus may inform questions regarding changing paleoclimate in tropical pangea across the pennsylvanian permian boundary the section consists mainly of silty mudstones and sandstones with sheet like to ribbon geometry and very minor limestones and records an upward transition from mainly braided stream deposition in the el cobre canyon formation to anastomosing stream deposition in the arroyo del agua formation we recognized multiple paleosol types within these strata including calcic protosols calcic argillisols argillic calcisols and calcisols all generally consistent with the interpretation of a seasonal sub humid to semi arid climate the calcretes in these paleosols occur primarily as truncated profiles although calcisols occur in both formations we note that protosols are more common in the el cobre canyon formation and argillisols dominate in the arroyo del agua formation also we find that the calcretes in the arroyo del agua formation are generally thicker than those in the underlying el cobre canyon formation the difference in calcrete maturity could be explained by changes in source area relief and sedimentation rate however stable isotope analyses of pedogenic carbonate indicate that a significant enrichment of 18o occurs near the transition between the two formations which approximates the virgilian wolfcampian equals gzhelian asselian boundary although the 13c data suggest that pco2 remained stable during the interval of deposition the 18o data are consistent with the interpretation of climate aridification across the pennsylvanian permian transition potentially related to the onset of gondwanan glaciation in the earliest permian

new upper carboniferous palynofloras from southern pyrenees ne spain implications for palynological zonation of western europe abstract in the western european basins the paleoflora of late pennsylvanian early permian transition is still a matter of discussion in terms of its age determination and biostratigraphic ranges this study represents a review of the upper carboniferous and permian stratigraphy of the central and eastern pyrenees from continental successions with interbedded volcanic volcaniclastic rocks coupling new palynological data and known palynological assemblages to calibrate them with recent shrimp u pb zircon ages dates obtained in previous works in this light the first continental unit overlying the variscan basement bears a gzhelian palynological association which fits perfectly with the isotopic shrimp u pb zircon dating of the associated pyroclastic rocks 304 6 1 5 ma and 300 4 1 4 ma in order to provide a solid base to characterize the carboniferous permian microflora evolution in the western tethys sub basins we have compared radiometrically dated palynological assemblages of the euramerican province such as spain southern france the alps and sardinia italy the new biostratigraphic and chronostratigraphic information presented here confirms the validity of the classical carboniferous palynological zonation of western europe

volcanic and tectonic controls of lacustrine and alluvial sedimentation in the stephanian coal bearing sequence of the malpas sort basin catalonian pyrenees the infill of a small variscan basin shows a complex succession of lacustrine and alluvial sediments whose pattern of distribution through time appears to have changed in response to contemporaneous volcanism following initial deposition of pyroclastic breccias and extrusion of lavas small lakes were established on the floor of the basin their infills were probably locally controlled by relief on top of the lavas but the pattern was disrupted by phases of mass movement from the basin margin which emplaced debris flows and a sedimentary melange containing large blocks of limestone and led to extensive soft sediment deformation this complex sequence of events culminated in the emplacement of a widespread ash flow bed an alluvial plain established during a period of rather uniform subsidence was rapidly drowned to give an extensive lake whose progradational infill led to re establishment of an alluvial plain the deposition of a widespread airfall tuff coincided with the onset of differential subsidence during which major channel sandstones were stacked in association with poorly drained palaeosols in the east of the area whilst a mudstone dominated sequence characterized by well drained palaeosols developed in the west a return to more uniform subsidence appears to have coincided with the cessation of volcanic activity

rayleigh wave dispersion along the hawaiian swell a test of lithospheric thinning by thermal rejuvenation at a hotspot summary in this paper we present a seismological test of the thermal rejuvenation model for the formation of the hawaiian swell the archetype of a midplate hotspot swell twostation measurements of rayleigh wave group and phase velocities between midway atoll and o ahu provide the basis for the test comparison of the observed dispersion curves with age dependent regionalized dispersion curves suggests that the swell has the seismic velocity structure of 50 110 myr old lithosphere rather than that of 20 50 myr old lithosphere as suggested by the rejuvenation model joint inversion of the group and phase velocity curves for isotropic velocity models yields an estimate of 100 km for the seismic lithosphere s thickness along the swell this value is difficult to reconcile with the 40 50 km thickness demanded by the rejuvenation model preliminary measurements of the coefficients of anelastic attenuation are also presented although the accuracy of these values is difficult to assess they too appear to be consistent with thick lithosphere

permian climate development in the northern peri tethys area the lodeve basin french massif central compared in a european and global context abstract the lodeve basin which contains an exceptional long and nearly uninterrupted profile of early to late permian continental red beds is well correlated to the other european permocarboniferous basins together they cover the time span from the late pennsylvanian to the permian triassic boundary although these basins were placed within the equatorial belt for the whole permian several climatic changes are recorded in the sediments terrestrial sedimentation is governed by the interaction of climate and tectonics as well as by volcanism to a variable degree therefore small scale climatic variations of the milankovitch band are hardly discernable and if so they could not be correlated between different basins indeed larger scale climatic shifts could be identified it is shown that the shift from the carboniferous icehouse to the mesozoic warmhouse was a multi stage process this global warming resulted in a general aridisation of northern pangea indicated by outspreading playa and sabkha red beds aeolianites and evaporites several short phases of increased humidity interrupted this trend indicated by wet red beds lake sediments and coal deposits in central and southern europe these wet periods are traceable within the late stephanian lower rotliegend gzhelian asselian topmost lower rotliegend asselian sakmarian upper rotliegend i late artinskian early kungurian and upper rotliegend ii zechstein wuchiapingian the aridisation of the northern pangea which accelerated near the sakmarian artinskian transition is attributed to a reorganisation of the major ocean currents cold water currents along the western flank of the pangea indicated by the permian chert event blocks moisture transport from west onto the continent during roadian and wordian the onset of an additional cold water current along the cimmerian continents blocks moisture transport from the east both phenomena together are responsible for the maximum of aridity at the early to middle permian transition additionally the equatorial climate has been affected by an increasing seasonality within the late pennsylvanian and permian caused by the wide shifting of the zone of inter tropical convergence itc over the equator based on a new reconstruction of the pangean assembly in this paper climatic changes in the permian are interpreted and causes of the arid humid arid shifts are examined phases of higher humidity are often related to events of global impact like the waxing and waning of the gondwanan glaciation obtained in the south african karoo basin dwyka group but also regional events had strong climatic influence the zechstein transgression in the northern and southern permian basin as well as the bellerophon transgression of the southern alps caused the wet phase in the wuchiapingian

an abandoned channel fill with exquisitely preserved plants in redbeds of the clear fork formation texas usa an early permian water dependent habitat on the arid plains of pangea abstract a well preserved plant assemblage at the colwell creek pond locality of leonardian kungurian age provides an opportunity to evaluate taphonomic conditions in a dryland alluvial setting a narrow channel body incised to 5 m depth through red paleo vertisols contains 2 m of varicolored laminated mudstone with graded layers and plant material x ray diffraction analysis of individual laminae indicates the presence of chlorite illite kaolinite and mixed layer clay with hematite in red and gray layers and goethite in yellow brown laminae no carbonate was identified and the total organic carbon content is minimal the fine sediment accumulated in a shallow abandoned channel from suspension and gentle underflows probably linked to seasonal inflow and analysis of lamina thickness suggests that standing water may have persisted for up to a few millennia the preservation of lamination is attributed to a lack of bioturbation possibly linked to a paucity of subsurface oxygen low productivity elevated salinity rapid deposition or a combination of these factors minimal bioturbation may also reflect the limited use of freshwater ecospace during the early permian clay rich paleo vertisols complete the fill with drab root traces that indicate growth of vegetation in a strongly seasonal setting abundant plant material in the laminated beds includes branches of walchian conifers the possible cycadophyte taeniopteris spp and the comioid possible peltasperm auritifolia waggoneri they were derived from an adjacent riparian zone and preserved as 3d goethite petrifactions much of the foliage shows evidence of arthropod herbivory although a humid climatic episode cannot be ruled out the exceptional abundance and preservation of the plants probably reflects the persistence of an oxbow lake on a relatively arid alluvial plain where riparian plants experienced periodic moisture stress but had access to groundwater nearly year round rapid burial in standing water the lack of bioturbation in the laminated sediments and early biomineralization probably explain the exceptional preservation of the plant remains

paleosols as indicators of paleoenvironment and paleoclimate paleosols are ancient soils that have been incorporated into the geological record soils form in response to interactions among the lithosphere hydrosphere biosphere and atmosphere so paleosols potentially record physical biological and chemical information about past conditions near earth s surface as a result paleosols are an important resource for terrestrial environmental and climatic reconstructions long standing paleosol research topics include morphology classification and clay mineralogy all of which provide information about pedogenic processes and local paleoenvironments paleosols are also used to infer processes involved in the development of stratigraphic architecture and basin evolution recent paleosol research has introduced semiquantitative and quantitative measures for environmental and chronometric reconstructions that provide insight into major regional to global changes in temperature precipitation and atmospheric pco2 these new proxies focus on morphological and chemi

revisional notes on the permian tetrapod ichnofauna from the tiddas basin central morocco during the mid 1980s structural geological field work in the up to 300 m thick red bed sequence of the permian tiddas basin central morocco revealed the first occurrence of palaeozoic tetrapod footprints in nw africa preservational ambiguity of part of the few published trace fossils and resulting taxonomic inconsistency necessitate a long needed reanalysis of the type locality based on 110 recently collected specimens the revised tetrapod ichnofauna of the study area comprises tracks of batrachichnus woodworth 1900 limnopus marsh 1894 amphisauropus haubold 1970 dimetropus romer and price 1940 varanopus moodie 1929 hyloidichnus gilmore 1927 and dromopus marsh 1894 which can be referred to small and medium sized temnospondyl seymouriamorph basal synapsid pelycosaur captorhinomorph and araeoscelid trackmakers this assemblage is interpreted to represent a late early permian artinskian kungurian tetrapod ichnofauna due to the relative abundance of footprints assigned to semiaquatic tetrapods and sedimentological evidence for pronounced humid palaeoclimatic conditions we propose correlation of the track bearing strata with the late artinskian early kungurian wet phase regarding the quality quantity and peculiar diversity of its fossils including the earliest record of seymouriamorph and advanced captorhinomorph tracks from the african continent the tiddas basin could be of great importance for the reconstruction of late early permian terrestrial ecosystems in proximity to the interface of euramerican and gondwanan biotic provinces

the three dimensional structure of kilauea volcano hawaii from travel time tomography a linear travel time tomography study of the most active shield volcano of the world kilauea volcano hawaii was undertaken to determine the lateral heterogeneities produced by its intricate magmatic and tectonic environment kilauea provides an ideal setting to do tomography because of its dense seismograph array and many local earthquakes that allow excellent ray coverage of complex subsurface features local p wave data from 12 295 events were inverted using a one dimensional layered velocity model inversions were done for two cell sizes 5 5 5 km and 1 1 1 km to resolve structural regions on different length scales this study provided a view of the average velocity variations relative to a one dimensional velocity model analysis and interpretation of the tomographic images allowed us to infer the following model the main shallow magma reservoir is delineated by a slow velocity region southeast of the summit from 0 to 2 km depth there is a distinct high velocity region centered northwest of the summit from 0 to 2 km depth that represents a cap of dense intrusive dikes surrounding the magma chamber we suggest that the shallow reservoir is a narrow compartmentalized region of sills and dikes centered just south southeast of halemaumau caldera below the main reservoir the summit is imaged as a slightly fast region from 5 to 10 km in the coarse model indicating that the main conduit is structurally defined by an intrusive dike complex until about 10 km the rift zones of kilauea are imaged as major high velocity entities widening to the south with depth until 6 km these fast anomalies are related to the sheeted dike complexes along the rifts on a finer scale slow anomalies suggest the presence of magma pockets centered at 0 2 km depth beneath mauna ulu makaopuhi and puu oo along the east rift zone erz two significant high velocity regions along the lower erz near kalalua and kaliu are inferred to represent intrusive barriers to magma injection along the shallow 0 4 km erz conduit the southwest rift zone may have an intrusive barrier related to a high velocity region just southwest of mauna iki the hilina and kaoiki fault zones are imaged as slow features at shallow depths 5 km related to the open fractures and scarps along the normal faults the koae fault system is imaged as a slightly fast shallow structure 6 km possibly related to intrusive diking from the adjacent rift zones that fill and may even induce the extensional structures associated with this complex fault zone continued inversions with the immense amount of seismic data collected for hawaiian events will allow the detailed development of a three dimensional structural model for kilauea such a model will be extremely useful to seismologists and petrologists alike for understanding the tectonic growth and magmatic evolution of this dynamic shield volcano

wasp waisted hysteresis loops mineral magnetic characteristics and discrimination of components in mixed magnetic systems rock magnetic studies of complex systems that contain mixtures of magnetic minerals or mixed grain size distributions have demonstrated the need for a better method of distinguishing between different magnetic components in geological materials hysteresis loops that are constricted in the middle section but are wider above and below the middle section are commonly observed in mixed magnetic assemblages such wasp waisted hysteresis loops have been widely documented particularly with respect to rare earth permanent magnets basaltic lava flows remagnetized paleozoic carbonate rocks and an increasingly wide range of other rocks our modelling combined with a review of previous work indicates that there are several conditions that give rise to as well as magnetic properties that are characteristic of wasp waisted hysteresis loops first at least two magnetic components with strongly contrasting coercivities must coexist this condition can arise from either mixtures of grain sizes of a single magnetic mineral or a combination of magnetic minerals with contrasting cocrcivities or a combination of these two situations second materials that give rise to wasp waisted hysteresis loops will have relatively high ratios of the coercivity of remanence to coercive force b cr b c because b0 is controlled by the soft low coercivity component whereas bcris controlled by the hard high coercivity component third values of b cr b c 10 usually only occur for strongly wasp waisted loops when the low coercivity component comprises an overwhelmingly large fraction of the total volume of magnetic grains fourth a given mixture of superparamagnetic and single domain sd grains is more likely to give rise to wasp waisted hysteresis loops than an equivalent mixture of sd and multidomain grains fifth our results provide empirical confirmation that the total magnetization of a material is the sum of the weighted contributions of each component in the absence of significant magnetic interaction between particles thus to contribute significantly to wasp waisted behavior a mineral magnetic component must give rise to a significant portion of the total magnetization of the rock as a result minerals with weak magnetic moments such as hematite need to occur in large concentrations to cause wasp waistedness in materials that also contain ferrimagnetic minerals we outline a method for determining the magnetic components that can give rise to wasp waisted hysteresis loops this method is based on high and low temperature magnetic measurements that are used to identify the dominant remanence bearing mineral s and on mineral magnetic techniques that are used to discriminate between different magnetic domain states the method is illustrated with several examples from archaeological geological and synthetic materials

three dimensional modeling of plume lithosphere interaction in order to understand better the dynamics of hot spots such as hawaii we present a three dimensional numerical model for the interaction of a thermal plume with a moving lithosphere the model domain is a rectangular box filled with fluid whose viscosity depends upon temperature and pressure the lithosphere is represented by a layer of cold highly viscous fluid moving with an imposed horizontal velocity u in the x direction and a thermal plume is generated by a circular temperature anomaly on the bottom of the box the steady flow is determined numerically using a hybrid spectral finite difference technique the flow is characterized by a stagnation streamline of width y x1 5 that represents the edge of the spreading plume material we illustrate the detailed behavior of the model using the example of the hawaiian plume our best fitting hawaiian model is obtained by adjusting the plume buoyancy flux b until the predicted topography anomaly matches the observed hawaiian swell topography we find b 4100 kg s 1 which implies a plume radius of 90 km for an assumed plume mantle temperature contrast of 300 c the predicted topography is supported primarily by density anomalies beneath the lithosphere and cannot be explained by lithospheric erosion we therefore conclude that the classical lithospheric reheating model is unable to account for hotspot swells the horizontal flux of buoyancy associated with the swell exceeds b by up to 80 suggesting that current estimates of b for mantle plumes are too high empirically derived scaling laws for the width of the stagnation streamline and for the topography anomaly exhibit power law dependencies on b and u that agree well with those predicted by the refracted plume model of olson 1990 the principal weakness of the model is that the predicted geoid topography ratio of 0 010 for the hawaiian swell is about twice the observed value of 0 004 0 006

the pennsylvanian tropical biome reconstructed from the joggins formation of nova scotia canada the pennsylvanian langsettian joggins formation contains a diverse fossil assemblage first made famous by lyell and dawson in the mid 19th century collector curves based on c 150 years of observation suggest that the joggins fossil record is relatively complete a key feature of the site is that fossils occur in par autochthonous assemblages within a narrow time interval

tetrapod footprint ichno associations from french permian basins comparisons with other euramerican ichnofaunas in order to take into account the studies of the european and american usa collections carried out by one of the authors and of the recent nomenclatural revisions from new footprint discoveries which have occurred during the last decade the authors present a critical review of the french permian palichnofauna the distribution of the ichnospecies in the stratigraphy of the lodeve basin taken as a reference is outlined the ichno associations are then compared with those of other french provence european italy germany and usa basins based on the ages of different ichnofossiliferous formations three successive ichnofaunal units can be distinguished in the permian of europe the first developed in the cisuralian asselian to kungurian the second is found in the south of france in kazanian to lower tatarian strata equivalent to the roadian wordian the third and youngest dated as lopingian is only found in italy in the bolzano basin because of sedimentary gaps limited observations sometimes erroneous determinations and ichnospecies with great vertical distribution it currently appears that footprints have a low utility for biochronological resolution nevertheless they allow us to discriminate three time intervals in the permian as is also the case for skeletal remains