iberian micromammals show local extent of vallesian crisis abstract once perceived as a continent wide extinction event doubts have been raised as to the severity and extent of the vallesian crisis in this paper we use the high resolution late aragonian to middle turolian micromammal record from both the coastal valles penedes basin and inland calatayud teruel complex to determine geographic extent of this late miocene turnover event and its effects within the reaches of the iberian peninsula differences in faunal composition between the two regions confirm that the event was much less severe than previously thought surprisingly the diversity peaks in the two regions do not coincide whereas at the coast highest diversity is found in the early vallesian just before the turnover in the inland it peaks in the late vallesian several taxa never made it inland as reflected by the low similarity between both regions during the early vallesian suggesting that the valles penedes was indeed unique and consistently showed higher affinities with northern regions the large differences even at relatively short distances support the idea that the vallesian crisis was a local event

ground penetrating radar detection of small scale channels joints and faults in the unconsolidated sediments of the atlantic coastal plain the geological characterization of the shallow subsurface in the unconsolidated sediments of the atlantic coastal plain and other unconsolidated sediment regimes may involve jointing faulting and channeling not readily detectable by conventional drilling and mapping a knowledge of these features is required in environmental geotechnical and geomorphological studies ground penetrating radar gpr may be used to routinely map these structures three principal shallow subsurface features are readily detectable using gpr paleochannels joints or fractures and faults the detection of paleochannels is dependent on the scale of the gpr survey and the attitude of the channel within the survey area channel morphological features such as scour surfaces point bars and thalwegs are observable joints and fractures are more difficult to detect depending upon size patterns orientation and fill material vertical joints may not be visible to radar unless they are wider than the sampling interval or are filled with radar opaque materials such as limonite angled joints or fractures may be distinguished by an apparent continuous reflector on the radar profile faulting on radar profiles may be observed by the offset of reflectors the image of the fault plane or the coherent interpretation of a fault system

stratigraphic correlation of the neogene basins in southwestern anatolia regional palaeogeographical palaeoclimatic and tectonic implications abstract the extensional intramontane grabens that formed in southwestern anatolia in the late cenozoic bear the unique tectono sedimentary palaeontological and palynological record of a region that underwent rapid transition from the last compressional pulses of the alpine orogeny to the tectonic phase of orogen collapse and the onset of neotectonic regime the change in tectonic regime was accompanied by regional climatic changes recorded by the sedimentary environments of the basins and evidenced by palaeontological and palynological data the late early to mid middle miocene was characterized by a warm and humid subtropical climate with densely forested wetlands the late middle to late miocene witnessed a change to arid climatic conditions with grass dominated steppe ecosystems the pliocene climate was warm and humid with savannah type open habitats in terms of their stratigraphic development the southwestern anatolian basins form two distinct groups one group is represented by the denizli soke and yatagan basins which commenced their development in the early burdigalian and underwent similar phases of environmental change 1 the burdigalian phase of alluvial environment and redbed deposition 2 the late burdigalian langhian phase of alluvial sedimentation accompanied by the formation of terminal lakes 3 the serravallian middle tortonian phase of the formation of shallow perennial lakes 4 the middle tortonian messinian phase of lake expansion and deepening followed by shrinking and shallowing 5 the pliocene phase of lake expansion and deepening and 6 the erosional quaternary phase of two stage alluvial sedimentation separated by a high relief erosional unconformity the other younger group of tectonic grabens is represented by the karacasu bozdogan cameli and esen basins which commenced their development in the earliest tortonian and underwent common environmental changes 1 the tortonian phase of alluvial environment and redbed deposition coeval with the phase of lake drying in the denizli soke and yatagan basins 2 the messinian phase of the formation of terminal lakes coeval with the re establishment of shallow lakes in the three other basins 3 the zanclean phase of shallow perennial lakes coeval with the expansion and deepening of lakes in the other basins 4 the piacenzian phase of deep lacustrine environments 5 the gelasian phase of shallow lacustrine environments and 6 the erosional quaternary phase of two stage alluvial sedimentation similar as in the other basins in spite of the time offset in their development the two basin groups have been strongly modulated by climate and hence show correlative responses to regional climatic changes despite the time offset in their tectonic development the two basin groups showed correlative environmental changes imposed by regional climatic conditions the basins were environmentally unified by the quaternary alluvial phase of their development in the late cenozoic anatolia was at the crossroads of fauna migration routes between africa asia and europe and the palaeontological data from the southwestern anatolian basins shed more light on this phenomenon the study as a whole contributes to a better understanding of the late cenozoic environmental climatical and biogeographical changes in the eastern mediterranean

three dimensional modelling of a holocene tufa system in the lathkill valley north derbyshire using ground penetrating radar unlithified and partly lithified carbonate sequences are ideally suited to the application of ground penetrating radar gpr augmented by percussion augering and shallow seismic techniques all tied to present day topography using global positioning system gps methods this methodology provides the first clear information on the distribution and geometry of lithofacies within buried tufa complexes the approach has been applied to a thick succession of holocene tufas filling a gorge site along a 3 5 km length of the river lathkill north derbyshire earlier studies have demonstrated the presence of up to 16 m of tufas and sapropels associated with two transverse tufa dams barrages these strata have been accumulating throughout the holocene although tufa developments at present are of minor extent internal tufa morphologies are recorded by gpr as bright laterally continuous reflections for lithified concretionary and lithoclast rich horizons the brightest reflectors occur within well cemented barrages and delineate core areas and prograding buttress zones in contrast unlithified lime muds and sapropels produce low contrast reflections lithostratigraphic control and depth calibration of the gpr profiles was provided by percussion augering at selected sites six distinct lithofacies and four secondary barrages are identified in the study constructional and destructional events can be identified and correlated within the gpr profile network and the internal growth morphologies of the barrages are apparent gpr profiles also clearly define the evolution of the facies geometries three phases of tufa development can be recognized within the gpr data and greatly extend our understanding of holocene tufa forming processes in valley sites a early holocene barrage build ups but with limited paludal deposition b middle holocene ponding and sapropel accumulation under warm conditions and c late holocene barrage termination and valley levelling probably coincidental with anthropogenic activity this type of multidisciplinary approach should be considered as an essential prerequisite to all biostratigraphic and geochemical studies of holocene freshwater carbonate sites

investigating peatland stratigraphy and hydrogeology using integrated electrical geophysics hydrology has been suggested as the mechanism controlling vegetation and related surficial pore water chemistry in large peatlands peatland hydrology influences the carbon dynamics within these large carbon reservoirs and will influence their response to global warming a geophysical survey was completed in caribou bog a large peatland in maine to evaluate peatland stratigraphy and hydrology geophysical measurements were integrated with direct measurements of peat stratigraphy from probing fluid chemistry and vegetation patterns in the peatland consistent with previous field studies ground penetrating radar gpr was an excellent method for delineating peatland stratigraphy prominent reflectors from the peat lake sediment and lake sediment mineral soil contacts were precisely recorded up to 8 m deep two dimensional resistivity and induced polarization imaging were used to investigate stratigraphy beneath the mineral soil beyond the range of gpr we observe that the peat is chargeable and that ip imaging is an alternative method for defining peat thickness the chargeability of peat is attributed to the high surface charge density on partially decomposed organic matter the electrical conductivity imaging resolved glaciomarine sediment thickness a confining layer and its variability across the basin comparison of the bulk conductivity images with peatland vegetation revealed a correlation between confining layer thickness and dominant vegetation type suggesting that stratigraphy exerts a control on hydrogeology and vegetation distribution within this peatland terrain conductivity measured with a geonics em31 meter correlated with confining glaciomarine sediment thickness and was an effective method for estimating variability in glaciomarine sediment thickness over approximately 18 km 2 our understanding of the hydrogeology stratigraphy and controls on vegetation growth in this peatland was much enhanced from the geophysical study

review of paleo humidity parameters in fossil rodents mammalia isotopic vs tooth morphology approach paleoecology of fossil rodents is frequently inferred from the dental pattern of the teeth attributing the habitat conditions of extant rodents to fossil species with similar dental pattern this technique is common practice and has been in use for several decades a relatively new technique is based on the carbon and oxygen isotope composition of the incisor enamel of fossil rodents to reconstruct paleoenvironmental scenarios we combine these two methods studying material from two early miocene spanish sections one in the mediterranean coastal area and one in northcentral inland spain comparison of the humidity values obtained by means of these two proxies reveals discrepancies therefore we analyzed the habitat preferences especially humidity of extant rodents and found that dental pattern is not very reliable to reconstruct the humidity preferences of fossil rodents and this kind of interpretation has to be taken with caution we conclude that the isotopic composition of enamel of fossil teeth is a more reliable proxy in the studied sections

the sedimentary structure of linear sand dunes linear sand dunes dunes that extend parallel to each other rather than in star like or crescentic forms are the most abundant type of desert sand dune1 but because their development and their internal structure are poorly understood they are rarely recognized in the rock record2 models of linear dune development2 3 4 5 6 have not been able to take into account the sub surface structure of existing dunes but have relied instead either on the extrapolation of short term measurements of winds and sediment transport or on observations of near surface internal sedimentary structures from such studies it has not been clear if linear dunes can migrate laterally2 7 8 here we present images produced by ground penetrating radar showing the three dimensional sedimentary structure of a linear dune in the namib sand sea where some of the world s largest linear dunes are situated these profiles show clear evidence for lateral migration in a linear dune moreover the migration of a sinuous crest line along the dune produces divergent sets of cross stratification which can become stacked as the dune height increases and large linear dunes can support superimposed dunes that produce stacked sets of trough cross stratification these clear structural signatures of linear dunes should facilitate their recognition in geological records

investigations regarding alpine talus slopes using ground penetrating radar gpr in the bavarian alps germany the applicability of ground penetrating radar gpr for the investigation of loose debris was tested at two sites viererkar and zugspitzplatt a pulseekko 100 gpr system equipped with 25 mhz antennae was utilized the aim of the investigation was to record the base of the debris layer and thereby acquire an estimation of the backweathering rates of the adjacent rockwalls the study areas are situated in the northern alps near the german austrian border the sites are characterized by steep limestone rockwalls and extensive talus accumulations a total of six profiles was surveyed the method is suitable and effective for a quick survey in this dry high ohmic substrate the gpr system was able to deliver information about the subsurface stratigraphy to c 70 m depth the boundary line to the bedrock was discovered depending upon the profile surveyed 5 to 25 m below the surface the base of the debris material sometimes shows no distinct reflection buried features v shaped furrows zones overdeepened by ice action geological structures could be detected arched structures well below the talus bedrock interface can be interpreted as drainage systems in the karstic bedrock a thick scree layer of late glacial age was separated from a thinner layer on the talus surface which was related to the holocene the backweathering rates were fixed by a calculation of talus volume to c 100 mm 103 a during the holocene viererkar and 150 300 mm 103 a zugspitzplatt the detrital formation in north exposed sites is twice as intense as in south exposed sites these results match the rates of recent rockfall in the same area of investigation the calculated backweathering for the late glacial period is 150 730 mm 103 a the magnitude of the calculated rockwall retreat lies well within the range of previous measurements the discrepancy between some weathering rates highlights the fact that recent and past relief formation must be differentiated otherwise recent removal rates may be overestimated copyright 2001 john wiley sons ltd

spatial and temporal variation in european neogene large mammals diversity abstract large mammals diversity i e ungulates or hoofed mammals is investigated over the whole european geographic area and through a period extending from the late oligocene around 27 ma ago to the early pliocene around 3 ma ago qualitative and quantitative spatial and temporal patterns are discussed thanks to the analysis of a large dataset of localities 695 that yielded large mammals and distributed over this period and area we show that the miocene is a key period in the installation of modern faunas in europe modern ruminants mainly cervids and bovids largely develop during the period considered and replace the oligocene inherited dominant faunas these replacements are triggered by different factors often extrinsic and constitute the roots of the present situation indeed a complex interplay between geographic palaeogeographic reorganisations and climatic factors warming and cooling events can be invoked to understand how faunas change geography seems to play a crucial role in the early miocene when it allows migration routes to open between europe asia and africa and in turn leads to a drastic increase of ungulate diversity that seems to be maintained in the middle miocene under the warm equable climates of the miocene climatic optimum the late miocene sees a global climatic deterioration leading to a decline in large mammals diversity and represents the root of the extant depleted situation regional comparisons indicate that endemism was already strong in the miocene especially in south eastern europe and that strong climatic belts already seem to have an impact on mammal communities since the late miocene the roots of the extant situation endemism and low diversity are therefore more complex and probably older than previously thought they are to be looked for before the quaternary climatic cycles and are the by product of deep time geographic and climatic events

ground penetrating radar and its use in sedimentology principles problems and progress abstract ground penetrating radar gpr also referred to as ground probing radar surface penetrating radar subsurface radar georadar or impulse radar is a noninvasive geophysical technique that detects electrical discontinuities in the shallow subsurface

towards realistic aquifer models three dimensional georadar surveys of quaternary gravel deltas singen basin sw germany abstract understanding sedimentary heterogeneities has nowadays become crucial for sophisticated aquifer management the methods used so far for aquifer characterization e g pump test coring analysis cannot provide the needed resolution for a sufficient prediction of the subsurface properties e g sudicky 1986 this calls for the application of the outcrop analogue approach to aquifers e g macfarlan et al 1994 aigner 1995 in this project we used georadar ground penetrating radar or gpr to acquire the subsurface information for high resolution three dimensional images and radar facies mapping of glaciolacustrine delta sediments in the singen basin sw germany a three dimensional reconstruction of sedimentary heterogeneities for a detailed aquifer characterisation becomes possible by combining gpr profiling and outcrop information a case study is presented showing a complex three dimensional architecture of a quaternary gravel body consisting of the following three types of architectural elements 1 glaciolacustrine delta foresets 2 erosional surfaces with scour pool fills and 3 horizontal glaciofluvial gravel sheets although this seems a relatively simple architectural inventory the three dimensional georadar profiling shows considerable internal heterogeneities the radar data are interpreted following the seismic stratigraphic approach i e the delineation of radar facies types and of radar sequences the three dimensional heterogeneities are visualized by means of time slices 3 d block or chair diagrams or series of radar facies maps

a new chronology for the middle to late miocene continental record in spain abstract the first detailed chronology for the middle to late miocene continental record in spain is presented based on high resolution magnetostratigraphic data of mammal bearing sections which were studied in several basins calatayud daroca teruel valles penedes duero and jucar cabriel our results indicate that these sections compose an almost complete magnetostratigraphic succession from the lower aragonian mn4 to the middle turolian mn12 seven successive mammal neogene mn zone boundaries are directly dated in these sections which often contain faunas of two successive zones in superposition the three oldest boundaries are dated in the aragonian type area calatayud daroca basin the mn4 mn5 boundary vargas section occurs in chron c5cr o with a corresponding age of 17 26 0 01 ma the mn5 mn6 boundary aragon section in chron c5acn 0 8 with an age of 13 75 0 03 ma and the mn6 mn7 8 boundary aragon section in the interval c5ar 1n c5ar 3r with an age of 12 75 0 25 ma the mn7 8 mn9 aragonian vallesian boundary occurring in chron c5r 1n at 11 1 ma and the mn9 mn10 boundary in chron c4ar 3r at 9 7 0 1 ma are recorded in the valles penedes basin vallesian type area and are supported by the results from the duero basin torremormojon section in the turolian type area teruel basin the mn10 mn11 vallesian turolian boundary la gloria section occurs in chron c4an y at 8 7 0 1 ma taking into account the pre existing data from the jucar cabriel basin the mn11 mn12 boundary cabriel valley section is recalibrated to c4n 1n at an age of 7 5 0 1 ma

petrogenesis of calc alkaline shoshonitic and associated ultrapotassic oligocene volcanic rocks from the northwestern alps italy along the western alps there is geological evidence of late alpine oligocene magmatic activity which clearly postdates the lepontine eocene early oligocene metamorphism and related deformation of the alpine nappe pile this magmatic activity was notably delayed in relation to the most important convergent processes and may be related to buoyancy of lithosphere tensional tectonics and thermal updoming subsequent to the collision between the eurasian and african plates the geochemical features of the rocks and the geophysical characteristics of the alpine chain suggest that a shoshonitic and calcalkaline melts may have been generated by partial melting of metasomatized peridotitic material and subsequent fractional crystallization and crustal contamination silicic andesites and latites however could have been also derived from metasomatized eclogite or deep continental crust material b the ultrapotassic lamprophyres with high k p lree th zr u and high 87sr 86sr ratios were generated by partial melting of strongly metasomatized mantle the varied sr isotopic ratios may partially also reflect additional radiogenic component from the continental crust following magma segregation from the source

the internal structure of scrolled floodplain deposits based on ground penetrating radar north thompson river british columbia abstract a study of floodplain deposits using ground penetrating radar gpr was conducted on a confined meander of the north thompson river near kamloops british columbia a survey grid consisting of 20 individual gpr profiles from 200 m to 900 m in length was constructed on a 0 9 km2 section of the floodplain all gpr profiles were collected using a pulse ekkotm iv gpr system with 100 or 200 mhz antennae dependent on the thickness of floodplain sediments floodplain sediments consist of sand and gravel deposits approximately 7 to 14 m thick that overlie silts and clays interpreted to be glaciolacustrine in origin vibracore and auger data obtained at nine locations in the gpr survey grid show that changes from medium sand to gravel do not produce distinct radar reflections in gpr profiles but that the water table may locally produce a distinct high amplitude radar reflection area well log data show that rapid signal attenuation at depth in all gpr profiles coincides with underlying silt and clay sediments gpr profiles were therefore useful in mapping 3 d variability in the thickness of floodplain deposits all gpr profiles were divided into macroscale 150 m2 in 2 d cross section radar facies delineated on the basis of the nature and orientation of reflections relative to surface scroll topography radar stratigraphy suggests that the floodplain is composed of a single complex lateral accretion deposit with periodic channel fills located between surface scroll ridges dip direction profiles normal to surface scroll ridges exhibit mainly inclined stratification is and or preserved ridge and swale ras deposits dipping in the direction of floodplain accretion well developed ras architecture in 200 mhz gpr profiles displays mainly wavy reflections conforming with surface topography and little inclined stratification these reflectors are interpreted to be the result of processes of vertical accretion associated with floodplain formation preserved scroll ridge deposits exhibit asymmetry at depth dipping more steeply in the direction of floodplain accretion profiles of strike direction parallel to surface scroll ridges show either parallel or slightly inclined 1 2 reflections dipping in the downstream direction

influence of relative sea level change and tidal inlet development on barrier spit stratigraphy sandy neck massachusetts abstract sandy neck is a 10 km long sheltered mesotidal barrier spit along the southeastern new england coast bordering cape cod bay its stratigraphy contains evidence of relative sea level rsl rise and tidal inlet development and enables reconstruction of accretion and progradation of this barrier through time core trench and ground penetrating radar gpr data show that the lower boundary of the uppermost eolian facies climbs about 9 m from the proximal to the distal part of the spit away from the mainland anchor point this change is thought to be related primarily to a comparable rise in rsl the same boundary also shows a shallowing trend in a seaward direction indicating net spit progradation through time the absence of inlet channel facies in the stratigraphy of the proxima part of the barrier spit in contrast to the presence of inlet facies in more distal parts of the spit indicates that some time elapsed after barrier initiation before an inlet thalweg developed in its earliest stages this thalweg was poorly defined wide and shallow but its characteristics changed as the barrier spit lengthened in the central part of sandy neck the assemblage of inlet channel facies becomes markedly thicker reflecting thalweg deepening in response to paleotopographic and substrate lithologic factors the stratigraphy of the distal part of the spit shows the effects of continued but more gradual inlet deepening that may be tied directly to increasing barrier length the process controlled stratigraphy presented here differs from current facies models because i accounts for temporal changes in coastal environmental processes and parameters it suggests a high preservation potential for proximal eolian facies in the spit sequence underneath a cover of fine grained and organic back barrier sediment once reliably dated the new stratigraphic data will help to improve the regional rsl curve for the southern cape cod bay area

ground penetrating radar a near face experience from washington county arkansas digital ground penetrating radar gpr is an emerging technology for detecting locating and or mapping features in the shallow subsurface it has application to geology civil engineering environmental science engineering soil science and many other fields this case history describes a high quality gpr survey performed in very close proximity to a vertical limestone rock face at a roadcut site in northwest arkansas the configuration allowed interpretation of the gpr results with the maximum of amount of geologic control the rock face itself our experience suggests that gpr has significant potential as a high resolution tool for mapping shallow structure and stratigraphy in carbonate rocks

regional o sr and pb isotope relationships in late cenozoic calc alkaline lavas of the andean cordillera quaternary recent volcanism in the andes has occurred in three regions 45 33 s 28 16 s and 2 s 5 n each of which has a distinct plate tectonic setting and contains volcanic suites with different chemical and isotopic characteristics isotope ratios of o and sr are lowest and those of pb least variable in the southern volcanic zone svz where medium k lavas have isotopic characteristics equivalent to volcanics from intraoceanic arcs where continental crust is absent the svz lavas were probably derived from an asthenospheric mantle source above a shallow benioff zone parental basaltic magmas rose largely unmodified through thin continental crust where differentiation occurred by low pressure crystal fractionation without concurrent modification of isotopic composition the slight enrichment of 206 pb in the northern volcanic zone nvz where the crust is thin and the benioff zone deep suggests a greater subduction zone component for parental medium k magmas the slight 18 o enrichment suggests a small amount of lower crustal interaction isotope ratios of o and sr are highest and those of pb most variable in the central volcanic zone cvz parental magmas in the cvz were probably generated within the same mantle source region as those in the svz and nvz subsequently during transit through the exceptionally thick continental crust of the central andes high k magmas were produced by a combination of bulk contamination in the lower crust and later low pressure fractional crystallization assimilation processes in the upper crust which altered both chemical and isotopic compositions

the effect of drainage reorganization and climate on the sedimentologic evolution of intermontane lake systems the final fill stage of the tertiary ebro basin spain abstract stratigraphic and sedimentologic analyses and geochemical data from the middle and late miocene record in the southwestern central sector of the ebro basin have allowed the evolution of its neogene final fill stage to be characterized and its controlling factors to be discerned the focus of these analyses was the distinct depositional environments that occurred over time tecto sedimentary units t6 t7 and t8 twelve main associations of lacustrine palustrine fluvial and alluvial facies revealed that the sedimentary processes leading to the formation of the units occurred in different environments in units t6 and t7 middle and late aragonian i e langhian serravallian and in unit t8 vallesian turolian i e tortonian the depositional environments of units t6 and t7 encompassed a closed shallow carbonate lake system with wide palustrine fringes the lake was fed by small sandy and gravelly channels flowing from the southwest iberian range and a sandy fluvial system from the north pyrenees inputs were also received from a southeastward flowing axial fluvial system as the mouths of these systems commonly formed small deltaic sandy lobes on the northern lake margins the evolution of unit t6 and in particular that of unit t7 was greatly influenced by pyrenean tectonics the depositional environments of unit t8 included the occurrence of the as but this system was soon replaced by an open shallow carbonate lake surrounded by wide and shallow oncoid bearing channels and palustrine tufaceous areas on its west southwest margin distinct depositional events from the south and west which involved intra t8 erosion resulted in minor coarse alluvial deposits the carbonate system of unit t8 occurred in an open depression created after local erosion of the pre t8 deposits and subsequent northward shifting of the as since early deposition of unit t8 the origin of which was related to late contractile deformation in the northwestern iberian range bicarbonate and calcium rich water from the mesozoic carbonate rocks in the iberian range fed the t8 system sedimentologic 13c 18o and trace element data support the change from closed to open drainage and strongly suggest a general climate trend toward wetter and cooler conditions which is consistent with the middle late miocene climate evolution of other european regions despite the general timing coincidence between unit t8 deposition and the opening process of the ebro basin the attributes of the t8 deposits are inconclusive to support the previous hypothesis that the fluvial lacustrine palustrine system could be directly connected to the emptying drainage of the basin into the mediterranean sea instead the results of this study demonstrate the combined influence of tectonics and climate on the evolution of the final fill stage of this part of the ebro basin these results may be useful for assessing the influence of such allocyclic factors on the sedimentologic hydrologic and geochemical evolution of other intermontane lake basins

going south latitudinal change in mammalian biodiversity in miocene eurasia for palaeontologists the challenge is to reconstruct biodiversity patterns of the past mammal richness in grids is used to assess the stability of biodiversity hotspots and document changes over time in europe for mammal neogene units 3 to 11 19 5 to 7 6 ma early to late miocene the maps clearly show the patchiness of the fossil record as the miocene was an eventful epoch with severe environmental changes europe slowly became drier and more seasonal both in temperature and precipitation from the early to middle miocene an area of high biodiversity moved from higher to lower latitudes culminating in one of the most remarkable hotspots in the history of mammals the early late miocene vallesian mammal stage faunas from the valles penedes catalonia spain remarkably the surrounding areas did not exhibit similar richness during the subsequent vallesian turnover event 9 7 ma the large and small mammal distribution became more equitable and the hotspots less prominent the richest area was found in the periphery of the humid miocene ecosystem which experienced species influx from the drier south the southward shift was a result of the expansion of the humid area with subsequent closed environments and related mixing of ecosystems coming to a halt in the late miocene when all of europe became equally open

ground penetrating radar used to assess aggregate in catastrophic flood deposits northeast alberta canada coarse grained aggregate deposited by a catastrophic flood located north of fort mcmurray alberta was examined using ground penetrating radar gpr and lithostratigraphic logging techniques gpr transects were acquired from an upper scoured zone of flood deposits sedimentary structures cross beds and plane beds within the coarse sand and gravel and determinations of depth to bedrock sediment thickness of the aggregate were recognized in the gpr profiles by their varying dielectric properties fine grained conductive underlying oil sand till or glaciolacustrine sediment silt and clay attenuated the radar signal the sedimentary structures mapped from the gpr transects were confirmed in adjacent trench exposures we suggest that gpr is an efficient methodology for determining volumes of aggregate reserves thicknesses of aggregate deposits and mapping sedimentary structures of high energy fluvial sediments key words aggregate ground penetrating radar alberta spillway

the influence of crustal structure on compositions of subduction related magmas abstract a survey of sr isotopic ratios and other compositional features of subduction related magma suites reveals significant correlations between these averaged parameters and characteristics of the underlying crust i e thickness composition and age these observations lead to the conclusion that crust and or mantle rocks in the hanging walls of subduction zones are involved in modification of primary mafic magmas typically basalt or basaltic andesite it is proposed that mafic magmas will stagnate within the crust or uppermost mantle where they may differentiate and react with wall rocks the extent to which such processes manifest themselves will depend upon details of the local crustal structure in particular the composition and age of the crust will strongly influence such parameters as sr nd and pb isotopic compositions such data strongly indicate the involvement of crustal rocks in locales underlain by old sialic crust e g central andes depending upon the level of magma stagnation and evolution within the crust different trends in isotopic composition may result these isotopic trends may be enhanced by partial melting of the wall rocks to produce relatively silicic anatectic magmas and locally they may reflect subduction of continental sediments interpretation of the isotopic data may be more ambiguous in locales underlain by younger and more mafic continental crust cascades e eleutians and those underlain by oceanic crust owing to the similarity in isotopic composition of primary magmas and the latter crustal materials yet some degree of crustal involvement in magmatic evolution seems highly probable even in these more primitive terranes consequently most island arc magmas and especially those more evolved than basalt are probably not primary in the sense that they do not represent direct melts of the upper mantle studies of arc volcanic rocks may yield misleading conclusions concerning processes of magma generation related to subduction unless evolutionary processes are defined and their effects considered it appears that modern volcanic arcs provide a poor analog for models of early crustal development because the modern mantle derived magmatic components are more mafic in composition than average continental crust

evolution and geodynamic significance of the tertiary orogenic volcanism in northeastern greece the tertiary volcanism of eastern macedonia and western thrace greece developed in association with the sedimentary basin which formed from eocene to oligocene along the southern margin of the rhodope massif the volcanic products ranging in composition from basaltic andesites to rhyolites show an overall calc alkaline orogenic affinity while chemical characteristics identify different groups of rocks probably reflecting minor differences among parent magmas the observed evolution within any group of rocks is compatible with fractional crystallization processes acting on relatively shallow magma bodies the sr isotopic composition of rhyolitic member shows an initial87sr 86sr ratio comparable with that of basaltic andesites reinforcing the hypothesis of a crystal liquid line of descent geochemical and petrographic evidence on the whole suggests that the investigated orogenic association developed on an active continental margin characterized by a relatively thick crust acting as a density filter for the basic magmas and facilitating their storage and fractionation within the crust itself minor contamination by interaction with host materials may also have occurred stratigraphic and k ar geochronological data indicate that the volcanic activity started in upper eocene and reached its maximum development in upper oligocene from lower miocene the volcanism shifted southward in the central aegean area and in part of western anatolia coming to an end by middle miocene the southward migration of the volcanic front has been interpreted as a consequence of the increase in the dipping of the benioff zone due to the decrease of penetrative strength after the main phase of continental collision

spatial variability of active layer thickness detected by ground penetrating radar in the qilian mountains western china the active layer plays a key role in geomorphic hydrologic and biogeochemical processes in permafrost regions we conducted a systematic investigation of active layer thickness alt in northeastern qinghai tibetan plateau by using ground penetrating radar gpr with 100 and 200 mhz antennas we used mechanical probing pit and soil temperature profiles for evaluating alt derived from gpr the results showed that gpr is competent for detecting alt and the error was 0 08 m at common midpoint co located sites considerable spatial variability of alt owing to variation in elevation peat thickness and slope aspect was found the mean alt was 1 32 0 29 m with a range from 0 81 to 2 1 m in eboling mountain in yeniu gou mean alt was 2 72 0 88 m and varied from 1 07m on the north facing slope to 4 86 m around the area near the lower boundary of permafrost alt in peat decreased with increasing elevation at rates of 1 31 m km eboling mountain and 2 1 m km yeniu gou and in mineral soil in yeniu gou the rate changed to 4 18 m km at the same elevation alt on the south facing slope was about 0 8m thicker than that on the north facing slopes while the difference was only 0 18 m in peat covered area within a 100 m 2 area with a local elevation difference of 0 8 m alt varied from 0 68 m to 1 25 m both field monitoring and modeling studies on spatial alt variations require rethinking of the current strategy and comprehensive design

a new approximation in determination of zonation boundaries of ignimbrite by ground penetrating radar kayseri central anatolia turkey ground penetrating radar gpr method is used as a tool to identify the zonation boundaries in ignimbrite series through their columnar section ignimbrites can be classified in terms of welding degree colour texture and mineralogical compositions the research area comprises a part of incesu kayseri ignimbrite at central anatolia turkey this ignimbrite is divided into three levels and each level has clear differences in terms of macroscopic and microscopic views this paper presents the results of an application of gpr for the determination of zonation boundary within the ignimbrite flow unit in the view of their textural and petrological features ramac cu ii equipment was used with 250 mhz shielded antenna on parallel ten profiles to observe the physical difference among the ignimbrite levels of the study area two levels out of three have been defined at the incesu ignimbrite and supported by field geology and petrographical studies the first level which is extremely fractured structure is about 1 5 m thick and matches with middle level of the incesu ignimbrite the second level has an average 50 75 cm thickness and matches with lower level of the ignimbrite in this manner vertical lithological variations should be taken into consideration during petrological investigation of the ignimbrites

late miocene early pliocene climatic evolution of the granada basin southern spain deduced from the paleoecology of the micromammal associations this paper analyses the relationship between the evolution of the late miocene and early pliocene rodent and insectivore assemblages from the granada basin southern spain and climate changes these climatic changes in terms of humidity and temperature fluctuations are inferred from variations of the relative abundances of taxons with definite ecological preferences there is a general tendency towards a temperature increase from the latest tortonian middle turolian to the messinian late turolian and towards a decrease from the mio pliocene boundary latest turolian earliest ruscinian to the end of the zanclean late ruscinian dry conditions predominate in the latest tortonian middle turolian at the beginning of the messinian late turolian there was a significant increase in humidity followed by an aridification throughout the end of the messinian and zanclean late turolian and ruscinian these climatic variations are in accordance with the sedimentary evolution of the basin and agree with the climatic interpretations inferred from the shallow marine carbonate sediments temperate tropical deposited in the marine basins of southeastern spain during the studied time interval

ground penetrating radar reflection profiling of groundwater and bedrock in an area of discontinuous permafrost we have used ground penetrating radar to profile the depth of permafrost to groundwater beneath permafrost and to bedrock within permafrost in alluvial sediments of interior alaska we used well log data to aid the interpretations and to calculate dielectric permittivities for frozen and unfrozen materials interfaces between unfrozen and frozen sediments above permafrost were best resolved with wavelet bandwidths centered at and above 100 mhz the resolution also required consideration of antenna configuration season and surface conditions depths to subpermafrost groundwater were profiled where it was in continuous contact with the bottom of the permafrost except near transitions to unfrozen zones where the contact appeared to dip steeply the complexity of the responses to intrapermafrost bedrock detected at a maximum depth of 47 m appears to distinguish these events from those of subpermafrost saturated sediments the relative dielectric permittivity ranged between 4 4 and 8 3 for the permafro

distortion of isochronous layers in ice revealed by ground penetrating radar in addition to measuring ice sheet thickness ground penetrating radar can be used to delineate reflections in ice sheets1 2 3 these reflections are generally accepted to result from layers of isochronous deposition of snow and can reveal much about the dynamics of the ice flow here we present ground penetrating radar data from fletcher promontory antarctica which show arches and troughs in isochronous ice layers to a depth of 100 m we demonstrate that the origin of these features can be determined by their growth with depth and many features result from local anomalies in accumulation rate which can be correlated with the ice surface slope one arch appears to be the result of a local anomaly in vertical strain rate its proximity to the ice divide width and growth with depth indicate that this arch is one of a class of features postulated by raymond4 but not previously shown to exist in the field such a feature is an indication of the nonlinear rheology of ice and requires that palaeoclimate records from ice cores extracted from the vicinity of ice divides underlain by similar features should be specifically corrected for such effects on ice flow

environmental magnetism a practical guide j walden f oldfield j and smith eds technical guide no 6 quaternary research association london 1999 243 pp price 17 00 9 00 to qra members isbn 0 907780 42 3

a calibrated mammal scale for the neogene of western europe state of the art abstract a magnetobiostratigraphically calibrated mammal scale for the neogene of western europe is presented in this paper the mammal neogene mn units originally proposed by mein report on activity rcmns working groups 1975 have been re defined here on the basis of first appearances of selected small and large mammal taxa the chronology of the lower boundaries of each unit had been established mostly after the significant magnetobiostratigraphic framework developed in the last decade in a number of spanish basins ebro calatayud daroca valles penedes teruel fortuna cabriel and guadix baza in the case of the early and middle miocene particularly mn 1 mn 2 and mn 3 the authors have also taken into account the magnetobiostratigraphic framework developed in the north alpine foreland basin some alternative correlations of the magnetostratigraphic data from this last basin are proposed in order to achieve a higher degree of consistence with the data from the iberian basins a quite well established magnetostratigraphic calibration of the mn boundaries can be proposed for most of the neogene from middle miocene to late pliocene on the other hand the chronological boundaries of the early miocene mn units are still poorly constrained due to 1 scarcity of well studied continuous thick magnetostratigraphic sections 2 the difficulty in defining the boundaries of the mn zones for this time span due to the relative homogeneity and persistence of the fossil rodent faunas and the absence of significant large mammal dispersal events some of the troubles which arise with the application of the mn units strengthen the need to take into account the palaeobiogeographical meaning of these units and their real suitability to date and correlate through extensive geographic areas

new constraints on the evolution of carolina bays from ground penetrating radar ground penetrating radar gpr data for the savannah river site srs in the upper coastal plain of south carolina combined with geological archaeological and ecological data place new constraints on the evolution of carolina bays extant srs bay morphology formed mainly during the holocene and did not involve migration of bays across the landscape multiple periods of bay rim accretion with intervening intervals of erosion may characterize the longer term evolution of the bays bay evolution however did not involve significant modification of the upland unit underlying the region during fluctuating but generally open water conditions breaking waves along bay shorelines eroded and transported sediment which was subsequently exposed for deflation during periods of low water deflation and transport of sand into standing vegetation along the margin of the bay depression created a rim in the form of a parabolic dune lacking obvious internal stratification simultaneously infilling occurred by shoreline erosion and transport from adjacent elevated surfaces this coupled with growth of emergent vegetation resulted in decreased hydroperiod wave energy shoreline modification and rim accretion transport of some rim sediments back into the bays via alluvial and colluvial activity created wedges of infilling sediment during waning stages of evolution the apparent contradiction of bay orientation with respect to prevailing winds might reflect seasonal changes in water level and wind direction southwesterly winds during spring high water causes nw se elongation of the bays whereas northwesterly winds during lower water in the fall and winter account for nearshore deflation and rim accretion along the east southeastern bay margins

quaternary sediment architecture in the orkhon valley central mongolia inferred from capacitive coupled resistivity and georadar measurements abstract detailed information on shallow sediment distribution in basins is required to achieve solutions for problems in quaternary geology geomorphology neotectonics geo archaeology and climatology usually detailed information is obtained by studying outcrops and shallow drillings unfortunately such data are often sparsely distributed and thus cannot characterise entire basins in detail therefore they are frequently combined with remote sensing methods to overcome this limitation remote sensing can cover entire basins but provides information of the land surface only geophysical methods can close the gap between detailed sequences of the shallow sediment inventory from drillings at a few spots and continuous surface information from remote sensing however their interpretation in terms of sediment types is often challenging especially if permafrost conditions complicate their interpretation here we present an approach for the joint interpretation of the geophysical methods ground penetrating radar gpr and capacitive coupled resistivity ccr drill core and remote sensing data the methods gpr and ccr were chosen because they allow relatively fast surveying and provide complementary information we apply the approach to the middle orkhon valley in central mongolia where fluvial alluvial and aeolian processes led to complex sediment architecture the gpr and ccr data measured on profiles with a total length of about 60 km indicate the presence of two distinct layers over the complete surveying area i a thawed layer at the surface and ii a frozen layer below in a first interpretation step we establish a geophysical classification by considering the geophysical signatures of both layers we use sedimentological information from core logs to relate the geophysical classes to sediment types this analysis reveals internal structures of orkhon river sediments such as channels and floodplain sediments we also distinguish alluvial fan deposits and aeolian sediments by their distinct geophysical signature with this procedure we map aeolian sediments debris flow sediments floodplains and channel sediments along the measured profiles in the entire basin we show that the joint interpretation of drillings and geophysical profile measurements matches the information from remote sensing data i e the sediment architecture of vast areas can be characterised by combining these techniques the method presented here proves powerful for characterising large areas with minimal effort and can be applied to similar settings

prediction of 3 d fluid permeability and mudstone distributions from ground penetrating radar gpr attributes example from the cretaceous ferron sandstone member east central utah a 3 d fluid permeability distribution is estimated inside a channel sandstone reservoir analog in the cretaceous ferron sandstone fluvio deltaic complex in east central utah from ground penetrating radar gpr attributes fluid permeability measurements at 5 cm spacing along four boreholes and one pseudohole section at the adjacent cliff face are used together with instantaneous amplitude and frequency attributes of gpr data to predict fluid permeabilities away from the measured vertical transects and to delineate the distribution and geometry of mudstone layers inside the reservoir analog statistically significant relationships are determined between the well data fluid permeability and mudstone content and the gpr attributes these calibrations are applied to the entire gpr volume to estimate the 3 d fluid permeability variation and the lateral development of mudstone units measured and predicted fluid permeabilities range from 0 1 to 290 md one of the five units considered contained no mudstone lay

magnetostratigraphy of the vallesian late miocene in the valles penedes basin northeast spain the magnetostratigraphic analysis of the late miocene continental deposits from the valles penedes basin combined with its well documented fossil mammal record has provided a well resolved chronology for the upper basin infill the study is based on the biostratigraphic and magnetostratigraphic cross correlation of 12 sections throughout the alluvial sequences in the western valles area the biostratigraphic framework consists of 21 mammal localities corresponding to the mammal neogene mn9 and mn10 units the composite magnetic polarity sequence is based on 400 paleomagnetic sites correlation with the geomagnetic polarity time scale gpts has led to an absolute dating of the faunal events and a precise chronostratigraphy of the vallesian mammal stage in its type area the hipparion first appearance datum fad at the mn8mn9 boundary is dated at 11 1 ma in the valles penedes basin this age compared to other radiometrically dated localities in europe north africa and turkey is consistent with an isochronous dispersal of this equid through the mediterranean region a possible isochrony at a larger geographical scale old world mesogea must await more reliable ages of the hipparion fad in asia and africa the cricetulodon fad mn9amn9b boundary is dated to 10 4 ma in chron c5n the progonomys fad mn9mn10 boundary corresponding to the intra vallesian faunal crisis is dated at 9 7 ma c4ar 3r the vallesian spans 2 4 myr from 11 1 ma c5r 1n to 8 7 ma c4an and correlates to the early tortonian

the vallesian mammal succession in the valles penedes basin northeast spain paleomagnetic calibration and correlation with global events abstract the integrated lithostratigraphic biostratigraphic and magnetostratigraphic study of new and classical alluvial fan sequences in the valles penedes basin northeast spain western mediterranean enabled a considerable refinement of the vallesian mammalian succession in this basin and its correlation with the magnetic polarity time scale up to 12 new sections were logged and sampled in a search of mammal remains and a paleomagnetic analysis was carried out the correlation among these sections was based on the small mammal content and the succession of magnetozones enabling the establishment of four main composite sections les fonts montagut terrassa and viladecavalls as a result the vallesian in the valles penedes basin appears punctuated by four main mammalian events which coincide with the appearance of the genera hipparion cricetulodon progonomys and rotundomys the hipparion event did not coincide with any further change in the associations of small and large mammals the dispersal of the cricetid cricetulodon in its turn involved the first set of extinctions in the vallesian affecting the rodent and carnivore and artiodactyl associations the main break during the vallesian coincided with the dispersal of the murids of the genus progonomys and implied a sudden drop in the diversity of the rodent and artiodactyl species of warm wet forested affinities this phase is characterized by the association of the murid progonomys and the cricetid cricetulodon and includes the last record of hominoids in the basin the replacement of cricetulodon by the sigmodont cricetid rotundomys was associated with the entry of some typical early turolian species according to the correlation established it is concluded that the fad of hipparion in the valles penedes basin is dated at 11 1 ma at the base of chron c5r 1n this data is congruent with other datings in northern africa and eastern europe suggesting the isochrony of this event in the mediterranean regions the cricetulodon fad is dated to 10 4 ma in chron c5n the progonomys dispersal coincident with the late vallesian crisis is dated at 9 7 ma in chron c4ar 3r the rotundomys fad is dated at 9 2 9 3 ma in the upper part of chron c4ar 1n the vallesian mammal bioevents affected the peri mediterranean zones including northern africa and other regions in northern and western eurasia these paleofaunistic changes were caused by temperature descent from subtropical to warm temperate conditions as well as by changes in the aridity balance and seasonality this climatic evolution was the result of the interplay of diverse global events cooling of the high latitude regions growing of the antarctica ice sheet and enhancement of the thermohaline oceanic circulation and of large scale tectonic and paleogeographic processes surface uplift of the himalayas the tibetan plateau and other tectonic reliefs closing of gateways between the mediterranean marine regions and the world ocean the magnetobiochronology resulting from the study of the western valles sequences suggests a close chronological correlation between some of these global and regional processes and the vallesian bioevents recorded

early and middle miocene stable isotopes implications for deepwater circulation and climate the middle miocene 18o increase represents a fundamental change in the ocean atmosphere system which like late pleistocene climates may be related to deepwater circulation patterns there has been some debate concerning the early to early middle miocene deepwater circulation patterns specifically recent discussions have focused on the relative roles of northern component water ncw production and warm saline deep water originating in the eastern tethys our time series and time slice reconstructions indicate that ncw and tethyan outflow water two relatively warm deepwater masses were produced from 20 to 16 ma ncw was produced again from 12 5 to 10 5 ma another feature of the early and middle miocene oceans was the presence of a high 13c intermediate water mass in the southern hemisphere which apparently originated in the southern ocean miocene climates appear to be related directly to deepwater circulation changes deep waters warmed in the early miocene by 3 c 20 to 16 ma and cooled by a similar amount during the middle miocene 18o increase 14 8 to 12 6 ma corresponding to the increase 20 ma and subsequent decrease 16 ma in the production of ncw and tethyan outflow water large 0 6 relatively rapid 0 5 m y 18o increases in both benthic and planktonic foraminifera i e the mi zones of miller et al 1991a and wright and miller 1992a were superimposed in the long term deepwater temperature changes they are interpreted as reflecting continental ice growth events seven of these m y glacial interglacial cycles have been recognized in the early to middle miocene two of these glacial interglacial cycles mi3 and mi4 combined with a 2 to 3 c decrease in deepwater temperatures to produce the middle miocene 18o shift

old world first appearance datum of hipparion horses late miocene large mammal dispersal and global events the magnetobiochronological dating of the late miocene hipparionine horses hipparion in the western mediterranean places its first appearance datum fad in the circum mediterranean region at the chron c5r at a minimum age of 11 1 ma this date challenges some of the widely accepted datings of this bioevent in western eurasia and is relevant to the discussion of the mode and tempo of hipparion dispersal the migration of the hipparion north american ancestor is related to the glacioeustatic sea level lowstand of the supercycle tb3 1 early tortonian and to the concurrent deep sea hiatus nh4 and oceanic 18 o isotopic event mi5 the hipparion dispersal was a conspicuous worldwide on land bioevent that was coeval with major late miocene oceanic and high latitude paleoclimatic global changes

evidence for eight great earthquake subsidence events detected with ground penetrating radar willapa barrier washington a new approach to detect holocene subduction zone earthquakes combines the results from ground penetrating radar gpr vibracores and accelerator mass spectrometry ams dates from a barrier spit located west of willapa bay southwest washington gpr data show a 10 m thick facies of beach sand within which we identify and vibracores confirm beach parallel wave eroded buried scarps mantled with multiple beds of magnetite the eight gpr detected buried scarps are interpreted to be eroded by minor transgressions caused by instantaneous barrier subsidence during earthquakes associated with the juan de fuca plate subducting under the north american plate of these scarps four have been ams dated at 300 1110 2540 and 4250 radiocarbon yr b p no datable material has yet been found for the other four radar detected scarps but we interpolate and extrapolate dates of 1800 3400 5000 and 5800 yr b p

the role of permafrost and seasonal frost in the hydrology of northern wetlands in north america abstract wetlands are a common landscape feature in the arctic subarctic and north temperate zones of north america in all three zones the occurrnce of seasonal frost results in similar surface water processes in the early spring for example surface ice and snow generally melt before the soil frost thaws causing melt water to flow into depressions over the land surface and at times across low topographic divides however evapotranspiration and ground water movement differ among the three climatic zones because they are more affected by permafrost than seasonal frost the water source for plants in the arctic is restricted to the small volume of subsurface water lying above the permafrost although this is also true in the subarctic where permafrost exists where it does not plants may receive and possibly reflect more regional ground water sources where permafrost exists the interaction of wetlands with subsurface water is largely restricted to shallow local flow systems but where permafrost is absent in parts of the subarctic and all of the temperature zone wetlands may have a complex interaction with ground water flow systems of all magnitudes

palaeoecological and biostratigraphical implications of the microvertebrates of qesem cave in israel abstract microvertebrates are generally well suited for drawing inferences on past environmental conditions because they are closely bound to the areas in which they lived in this paper we discuss palaeoecological implications of two microvertebrate concentrations in the middle pleistocene site qesem cave in israel the ecological preferences of the nearest living relatives of the microvertebrate taxa recorded in concentration 1 squares l n 13 15 and 2 squares g h 16 17 at qesem cave allow us to infer a mosaic of open palaeoenvironment with sparse vegetation shrubland mediterranean forest rocky areas and riverbanks additionally we infer palaeoclimate from the bioclimatic distribution of extant species using the coexistence approach to our knowledge this is the first time the approach has been applied to microfaunal assemblages these data suggest cooler and slightly drier winters and somewhat lower seasonality than at present around qesem cave the differences are more pronounced for the time covered by concentration 2 than concentration 1 among microvertebrates micromammals are most suitable for biostratigraphic purposes with the exception of rattus cf haasi and the myomimus judaicus setzeri group the small mammal fauna of qesem cave comprises only taxa that live today in the levant r haasi and m judaicus have been found in israel in the early and middle pleistocene and their latest known record was from the acheulian site of oumm qatafa their presence in qesem cave extends the previously known stratigraphic range of these species the absence of r haasi in mousterian sites is thus consistent with the pre mousterian age of qesem cave morphometric data on molars of guenther s vole show that the lineage segment preserved in concentration 2 is more primitive than in concentration 1 indicating that the former concentration is older the evolutionary level of the sample from qesem concentration 1 is similar to tabun d boundary of acheulo yabrudian cultural complex and mousterian and that from qesem concentration 2 similar to tabun eb acheulo yabrudian

exploration of subsurface strata conditions for a limestone mining area in india with ground penetrating radar a study has been conducted for the exploration of underground voids and strata conditions at shallow depth in a limestone mine of manikgarh cement at maharashtra in india the manikgarh cement is surrounded with high quality limestone having platy formations with excessive fractures and fissures a perennial river the amal nala is flowing across the middle of limestone mining lease of the manikgarh cement captive mine the impact of this water body on the mining is the central theme of this study excavation of limestone is in progress in different blocks on both sides of the amal nala for the purpose of planning it was necessary to know the ground conditions of the area surrounding the amal nala so that seepage of the water can be checked if there is no adverse impact due to deepening of mining activity the minerals lying at depth can be safely exploited a ground penetrating radar gpr survey was carried out in the mining lease area to investigate the condition of the strata status of fractures cracks cavities etc through which seepage or water percolation takes place the results of this survey reveal that solid compact layers exist from the surface to depths varying from 2 to 5 m only along the three sections g1g1 g2g2 and g3g3 lying in the mining area of the manikgarh limestone along both sides of the amal nala fractured weathered rocks and solution cavities exist from the surface to depths varying from 4 to 16 5 m therefore extraction of limestone is possible only to depths of 2 to 5 m from the surface in this mining area if extraction continues below this depth the seepage of water from the amal nala will start due to the presence of enormous fractures and cavities solution holes in the underlying limestone strata in addition the water of the amal nala will be disturbed which is the main water reservoir of this area

mapping vertical profile of discontinuous permafrost with ground penetrating radar at nalaikh depression mongolia ground penetrating radar gpr has become an important geophysical tool which can provide a wealth of interpretive information about the vertical profile of discontinuous permafrost a gpr investigation was conducted in october 2006 at the nalaikh site at the southern boundary of the siberian discontinuous permafrost region in mongolia gpr data were collected along four 100 m long profiles to identify the location of the permafrost body which included an in situ drilling borehole and analysis of temperature observations and soil water content measurements from boreholes the gpr interpretation results indicated that the thickness of discontinuous permafrost at the study site was only 1 9 3 0 m and the permafrost is vulnerable to climate change the soil temperature and soil water content data demonstrate the precision of gpr image interpretation this case demonstrated that gpr is well suited for mapping the internal structure of discontinuous permafrost with relatively low soil water content

reconstruction of the late miocene climate of spain using rodent palaeocommunity successions an application of end member modelling abstract end member modelling is applied to a data set of relative abundances of 67 upper miocene rodent associations 11 6 ma from spain france austria and greece the analysis results in the robust estimation of relative levels of four climatic parameters humidity temperature seasonality type and predictability in the preparatory stage species are aggregated into nine groups on the basis of ecological criteria humidity preferences and adaptations are based on actualistic and functional morphological interpretations of dentition and locomotion temperature preferences are inferred from palaeobiogeographic distributions levels of adaptation to seasonality type wet dry or cool warm seasonality are assigned on the basis of diversities in present day climate vegetation zones and the ability of extant relatives to hibernate demographic data are used to formulate adaptations to climatic un predictability in the modelling stage the compositions are unmixed into the contributions of four end members these four extreme theoretical rodent compositions are interpreted in climatic terms and their contributions to the samples are used for the estimation of climatic parameters the subset of 44 well dated rodent compositions from the calatayud daroca and teruel basins ne spain is used to construct detailed climatic curves for the late miocene while the geographical dimension in the data set is used to calculate inter basinal differences the model results for spain indicate more humid and cooler conditions between 10 5 and 8 5 ma around 7 and around 6 ma and more arid and warmer conditions before 10 5 between 8 6 and 7 5 ma and around 6 5 ma superimposed on this pattern is a shift from a more predictable cool warm seasonal climate towards a more unpredictable wet dry seasonal climate between 9 4 and 8 2 ma inter basinal comparisons per time slice show that the climate in southern europe was dryer warmer more wet dry seasonal and more unpredictable than in central europe and that the climatic and vegetational boundaries between the two regions were sharp the occurrences of more humid and cooler episodes in spain during the late miocene might be explained by southward migrations of the boundary between a temperate and subtropical dry climatic belt and their associated vegetation types various positive correlations are observed between the rodent based climatic curves for spain and other palaeoclimatic records from the mediterranean and ne atlantic region clay minerals marine fauna stable isotopes the two cooling maxima at 9 4 and 7 ma closely correspond to clusters of marine events which are generally considered to reflect maxima of global ice volume

ecogeographical stability and climate forcing in the late miocene vallesian rodent record of spain abstract the composition and structure of rodent taxocenosis from three iberian basins with a reasonably complete record calatayud teruel duero and valles penedes for the latest aragonian and vallesian middle late miocene is explored using correspondence analysis ca ca classifies the assemblages in four great groups that are interpreted as rodent paleocommunity types rpts on the basis of paleobotanical and paleomastological data available for some of the sites considered or time equivalent localities each rpt is considered to be characteristic of certain environmental conditions taxonomic membership and relative abundance patterns in the recognized rpts are quite stable throughout relatively long time intervals in each basin suggesting the existence of coordinated stasis however the predictions of coordinated stasis are only partly achieved and important differences are shown to occur within certain rpts rpts with a low species richness and dominated by one or two genera characterize the record of the duero basin in the case of the valles penedes and calatayud teruel more equitative rpts with a high species richness are present during the early vallesian and also during the latest aragonian in the valles penedes the late vallesian sites appear as clearly differentiated of the remaining ones and grouping is strongly influenced by geographic position the environment seems to have been more open and wet dry seasonal in the late vallesian sites of the calatayud teruel and duero basins instead in the valles penedes basin it appears to have been more humid and cool warm seasonal this fact points to the existence of a zonation of the iberian climate during the late vallesian that closely matches the pattern observed today

rodent palaeoecology of the continental upper miocene of crevillente alicante se spain abstract the upper miocene succession of crevillente presents an alternation of continental and marine beds the marine fossils have been studied in order to obtain a reliable correlation with other marine sections on the basis of these data the entire section can be dated as upper tortonian messinian the alternation of continental and marine beds fits the known eustatic sea level and climatic curves these correlations are used to assign ecological preferences to the components of the micromammal faunas at species level it becomes clear that working at the genus level does not provide valid results with the assignments it is possible to demonstrate consistent climatic differences between the coastal plain of crevillente and the area of teruel on the meseta of central spain

statistical testing for paleocommunity recurrence are similar fossil assemblages ever the same abstract observations of the recurrence of similar fossil assemblages through long intervals of geologic time punctuated by rapid changes in both the composition and structure of fossil assemblages has recently resulted in the concept of coordinated stasis to describe this pattern in the behavior of paleocommunities through time coordinated stasis may imply the existence of ecological mechanisms that actively maintain particular community structures and thus have a significant impact on the process of macroevolution however before such mechanisms can be invoked it must be shown that ecological stasis as observed in the fossil record is more significant than the persistence of similar community types due to the repeated reinvasion of recurring habitats from a persistent species pool the null hypothesis for paleocommunity recurrence analysis of the relationship between communities and paleocommunities and an expansion of the ecological hierarchy at the community paleocommunity level allows the creation of a rigorous definition of the entities composing the local paleocommunity the samples collected within a stratigraphic horizon at a single locality paleocommunity groups of samples shown to be statistically identical and paleocommunity type groups of samples that are similar but can be shown to be statistically different these definitions permit the development of the null model for paleocommunity recurrence and establish a base level of variability within a local paleocommunity that permits rigorous statistical comparisons to be made between paleoecological samples at larger temporal and geographic scales paleoecological samples from four marine tongues in the middle pennsylvanian breathitt formation are used to analyze species abundance variability at several spatial and temporal scales and to test for paleocommunity recurrence although recurrence of statistically identical local paleocommunities occurs at single localities and between localities within individual marine units it is usually not detectable between marine tongues suggesting that paleocommunity recurrence in the marine strata of the breathitt formation is the recurrence of paleocommunity types and does not falsify the null hypothesis

paleogene collision related basalts and basaltic andesites in the eastern rhodopes bulgaria yanev y mavroudchiev b and nedyalkov r 1989 paleogene collision related basalts and basaltic andesites in the eastern rhodopes bulgaria j volcanol geotherm res 37 187 202 high k calc alkaline and shoshonitic basalts basaltic andesites sior 49 53 wt represented by a total of 10 specimens and one absarokite sample are studied petrologically and geochemically trace elements and ree basalt phenocrysts include clinopyroxene an ore mineral and plagioclase olivine biotite sanidine and absarokite phenocrysts are represented by olivine clinopyroxene and orthopyroxene collisional basalts basaltic andesites differ from those in the active continental margin settingin their increasedabundances of some lll elements rb cs ba as well as th and u in the high kl ti klp k sr rb sr and ba sr ratios negative nb anomaly and low abundances of most fe mg elements ti y yb sc ni co cr their ree patterns are moderately fractionated and the rocks show a negative eu anomaly higher p and cr abundances lower yb content and a positive eu anomaly however are characteristic ofthe absarokite the basalts basaltic andesites represent highly crust contaminated melts formed at moderate s and high p11 6 whereas the absarokite shows some features indicative of mantle derived melts

integrating surface georadar and crosshole radar tomography a validation experiment in braided stream deposits we have used a combination of surface ground penetrating radar gpr profiling crosshole radar tomography and natural gamma ray logging to characterize a gravelly braided stream deposit in a gravel pit we conducted a survey using 300 mhz surface gpr 250 mhz crosshole radar and densely sampled gamma ray logging at single borehole locations after excavation we validated the geophysical results by comparison with the sedimentological and hydrogeological information obtained from the corresponding outcrop wall we found the visual lithofacies boundaries agreed very well with the images provided by applied geophysical techniques our results illustrate how gpr reflector images are improved using tomographic velocity information in addition the structural interpretation of tomographic velocity fields is guided by the gpr reflector images in combination with natural gamma ray logging results groundwater flow and transport modeling was also performed on different subsurface models the hydrogeological r

evolution of early middle miocene rodent faunas in relation to long term palaeoenvironmental changes abstract cluster and principal components analyses have been applied to the composite sequence of 59 rodent assemblages from ramblian to lower vallesian deposits in the daroca calamocha area in the calatayud teruel basin north central spain the studied record is thought to represent the interval from the late aquitanian to the end of the serravallian i e early to middle miocene from ca 22 10 5 ma ago the quantitative results are interpreted by using individual rodent taxa as environmental indicators and by extrapolating the predominant adaptive strategies of recent taxonomic groups which also seem to form natural groups on a demographic scheme french et al 1975 a general warming trend starts in the rambian early miocene and continues into the middle aragonisn early middle miocene the cooling in the middle to late aragonian boundary interval is correlated to the middle miocene cooling phase another cooling occurred around the aragonian vallesian boundary late middle miocene we relate a major increase of aridity in the beginning of the middle aragonian ca 16 5 ma to the spread of low biomass vegetation due to intensification of the subtropical belt wolfe 1985 a notable feature around the early middle aragonian boundary indicating a major shift of climatic belts is the reversal of the relationship between our relative temperature and humidity curves before the reversal we find a positive correlation after it a negative correlation around the middle to late aragonian boundary humidity increased again and a further increase of humidity is indicated by the earliest vallesian faunas our data suggest that the nature of favoured adaptive strategy amongst rodents is related in the end to the degree of climatic humidity

application of gpr to a site investigation involving shallow faults a series of ground penetrating radar gpr lines were acquired on a proposed multistory building site in fayetteville arkansas because engineering work implied the existence of a shallow fault building a heavy structure in the vicinity of this fault would involve risk due to differential settlement solution cavities and fault reactivation in this case the new radar surveys combined with pre existing borehole data and regional geological knowledge verified and mapped the fault

predictable structure of miocene insectivore lipotyphla faunas in western europe along a latitudinal gradient abstract the insectivores grandorder lipotyphla have been seldom used in mammal based paleoenvironmental inferences because this group is generally considered insufficiently represented or studied nevertheless a recent compilation on the insectivore record of western europe has shown that this is not the case from the insectivore occurrences themselves a major paleobiogeographical pattern seems to be present the faunas of the mediterranean regions of western europe are poorer and seem to be a subset of those occurring at higher latitudes this kind of pattern where smaller assemblages seem to be a nested subset of the richer ones is known as nestedness in this work we analyze the prevalence of nestedness in the miocene insectivore record of western europe the calculations are carried separately for each mn mammal neogene zone and a measure of nestedness or order is given the probability that a similarly nested pattern could be obtained at random for each mn is assessed by permutation our results show the prevalence of nestedness in all the mn zones except the mn 1 in the second step we study the causes of nestedness a significant correlation of the nested structure with latitude is found in 8 out of 12 matrices thus confirming that the southern assemblages are a subset of the northern ones this must be related to some underlying latitudinal gradient that already existed during the miocene latitudinal gradients in temperature seem to have been unimportant until the late miocene yet the nested pattern existed as early as the early miocene a precipitation gradient which was already present by the early miocene seems to be the most important structuring factor independent evidence has confirmed that the central european regions were more humid than the mediterranean ones thus explaining the higher diversity of insectivores in that area as this group is more diverse in humid climates the structure of the southern assemblages is a highly predictable subset of that of the northern ones in the south the species that seem to have required higher levels of environmental moisture are missing this applies for instance to many talpids and dimylids which never reached the iberian peninsula

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

le volcanisme quaternaire d anatolie centrale turquie association de magmatismes calco alcalin et alcalin en domaine de convergence collision volcanism in central anatolia cappadocia began at least in the late miocene because of the north south arabian eurasian convergence since this period the anatolian block is displaced towards the west along the north and east anatolian strike slip faults kinematic reconstructions show that the east anatolian fault is both sinistral and convergent as a consequence the anatolian block is currently being deformed quaternary volcanism in central anatolia is represented by several hundreds of monogenetic scoria cones lava flows maars and domes as well as two strato volcanoes hasan dag and erciyes dag the monogenetic volcanism is bimodal basalts and rhyolites whereas the stratovolcanoes exhibit a complete calc alkaline suite from basalts to rhyolites most of the igneous products are calc alkaline basalts erupted mainly from the monogenetic cones lava flows and maars andesites are encountered in the strato volcanoes as lava flows domes and nuees ardentes deposits dacites and rhy

permafrost dynamics in the 20th and 21st centuries along the east siberian transect 1 the east siberian transect which has been designated by the international geosphere biosphere program igbp as its far east transect has unique permafrost conditions not only does permafrost underlie the entire transect but also about one third of the region is underlain by an ice complex consisting of extremely ice rich late pleistocene sediments given the possibility of a predicted future increase in global temperatures an evaluation of the magnitude of changes in the ground thermal regime becomes desirable for assessments of possible ecosystem responses and impacts on infrastructure a soil model developed at the geophysical institute permafrost laboratory was used to simulate the dynamics of the active layer thickness and ground temperature in this transect both retrospectively and prognostically using climate forcing from six global climate models gcms analysis of future permafrost dynamics showed that within the southwestern part of the transect widespread permafrost thawing from the surface can begin as early as 2050 the spatial extent and temporal dynamics of the zone with thawing permafrost vary significantly among the different gcms according to all the gcms the mean annual ground temperatures could rise by 2 6 c and the active layer thickness could increase by 0 5 2 m everywhere within the transect by 2099 however the increases in mean annual ground temperature and active layer thickness are not uniform in time relatively cold and warm periods associated with natural fluctuations in air temperature and precipitation are superimposed on the background warming trend the most significant increases in mean annual ground temperatures and in the active layer thickness are projected to occur in the southwestern part of the transect and in areas with coarse grained sediments characterized by low water content and high thermal conductivity

late quaternary stratigraphy and sea level history of the northern delaware bay margin southern new jersey usa a ground penetrating radar analysis of composite quaternary coastal terraces abstract ground penetrating radar gpr and lithologic data reveal six pleistocene sea level highstand sequences forming two composite terraces along the northern margin of delaware bay in southern new jersey usa the upper terrace 18 to 9 m msl is underlain by four estuarine marine sequences of middle pleistocene age while the lower terrace 6 m msl contains 2 middle to late pleistocene sequences separating the 2 terraces is a variably sloping escarpment cedarville created by erosion during at least 2 high sea level events intensive radar imaging and boring of these 6 unconformity bounded units allows for their interpretation in a sequence stratigraphic context identifying transgressive highstand and regressive phases higher than present sea levels of 14 12 6 and 16 m during the middle pleistocene and 5 m during the middle and or late pleistocene are indicated by these sedimentary sequences suggesting relative stability of this section of the atlantic coastal plain during the past 500 ka gpr analysis of coastal drainage modification reveals a contrasting lowstand sequence of incised paleovalleys supporting the interpretation that these bay margin deposits contain one of the most complete sections of late quaternary highstand stratigraphy in the mid atlantic region for appendix see http www elsevier nl locate quascirev

investigating internal structure of permafrost using conventional methods and ground penetrating radar at honhor basin mongolia a ground penetrating radar gpr survey was conducted at the end of august 2009 in the suburb region of ulaanbaatar honhor basin mongolia in combination with conventional methods such as borehole drilling and measurement of ground temperatures the interface of frozen and unfrozen sediment was distinctly resolved in the interpreted gpr images verified by the borehole drilling records and 6 month measurement of ground temperatures the location of the permafrost table was assessed to be at the depth of 2 4 m in the study region a conspicuous ice saturated soil layer massive ground ice was detected in the interpreted gpr images with a thickness of 2 5 m the gpr investigation results were consistent with the borehole drilling records and ground temperatures observation the borehole logs and ground temperatures profile in the borehole indicates that permafrost at honhor basin is characterized by high ground temperature and high ice content which implies that ongoing climatic warming would have great influence on permafrost dynamics the research results are of great importance to further assess permafrost dynamics to climatic change in the boundary of discontinuous and sporadic permafrost regions in mongolia in the future

detection of welding in pyroclastic flows with ground penetrating radar insights from field and forward modeling data abstract we investigate the potential of ground penetrating radar gpr as a tool to delineate welded portions of pyroclastic flows by testing interpretations of field gpr data with numerical modeling specifically we test the hypothesis that regions of changing porosity with depth and regions of constant porosity are characterized by distinct signals in radargrams we model the propagation of electromagnetic waves through pyroclastic flow deposits with vertical variations in porosity the actual profiles are gradational but are represented in our models by a series of 1 cm thick homogeneous layers each layered porosity profile is converted into a layered k profile using an empirical law relating k to of dry volcanic rocks that is based on laboratory measurements the resulting synthetic traces indicate that moderate gradational changes in welding produce multiple low amplitude crests and troughs rather than strong individual reflections the lower the peak frequency of the source wavelet the greater the amplitude of the signal generated and thus the greater the potential signal to noise ratio extremely high rates of change in porosity with depth produce distinct strong reflections densely welded or unwelded portions where porosity is relatively constant produce sections of zero amplitude these preliminary results suggest that gpr can be used to map the effects of welding in pyroclastic flows specifically characteristic radar signals can be used to identify zones of changing degree of welding and zones of relatively constant degree of welding

the portland hills fault uncovering a hidden fault in portland oregon using high resolution geophysical methods abstract the portland metropolitan area historically is the most seismically active region in oregon at least three potentially active faults are located in the immediate vicinity of downtown portland with the portland hills fault phf extending directly beneath downtown portland the faults are poorly understood and the surface geologic record does not provide the information required to assess the seismic hazards associated with them the limited geologic information stems from a surface topography that has not maintained a cumulative geologic record of faulting in part due to rapid erosion and deposition from late pleistocene catastrophic flood events and a possible strike slip component of the faults we integrated multiple high resolution geophysical techniques including seismic reflection ground penetrating radar gpr and magnetic methods with regional geological and geophysical surveys to determine that the portland hills fault is presently active with a zone of deformation that extends at least 400 m the style of deformation is consistent with at least two major earthquakes in the last 12 15 ka as confirmed by a sidehill excavation trench high resolution geophysical methods provide detailed images of the upper 100 m across the active fault zone the geophysical images are critical to characterizing the structural style within the zone of deformation and when integrated with a paleoseismic trench can accurately record the seismic history of a region with little surface geologic exposure

interpretation of drill core and georadar data of coarse gravel deposits abstract pollution in the shallow subsurface has led to an increasing need of understanding how to quantitatively characterize both the heterogeneity of gravel aquifers and the influence of heterogeneity on groundwater flow and solute transport models play an important role in decision making processes especially in the context of better characterizing and in forecasting the behavior of a given geological system the objective of the present paper is the derivation of a gradual lithofacies based interpretation of outcrop drill core and ground penetrating radar gpr or georadar data of different quality the presented method allows a probability estimation of drill core layer descriptions and radarfacies types representing defined sedimentary structure types the method includes a determination of initial structure type probabilities for grain size categories and combinations thereof described in drill core layer descriptions as well as a subsequent differentiation of these structure type probabilities in an iterative process considering additional information like main constituent quantity fraction and sorting of single grain size categories color chemical precipitation layer thickness and adjacent layer the radarfacies types are calibrated with drill cores located in the vicinity of georadar sections the calibration process consists of the assignment of the calculated structure type probabilities from the drill core layer descriptions to the corresponding radarfacies types considering the proportion in thickness between drill core layers and georadar structures the structure type probabilities can be given for points along boreholes and a grid with arbitrary mesh size along georadar sections the method is applied to field examples from the rhine wiese aquifer near basel in switzerland the resulting structure type probabilities can be used for conditioning stochastic simulations of geological models however the conditioned stochastic simulation of the rhine wiese aquifer is the topic of another paper the results show the importance of a detailed sedimentological analysis of outcrops and drill cores as well as its significance on the distinction of sedimentary structure types

measuring thaw depth beneath peat lined arctic streams using ground penetrating radar in arctic streams depth of thaw beneath the stream channel is likely a significant parameter controlling hyporheic zone hydrology and biogeochemical cycling as part of an interdisciplinary study of this system we conducted a field investigation to test the effectiveness of imaging substream permafrost using ground penetrating radar gpr we investigated three sites characterized by low energy water flow organic material lining the streambeds and water depths ranging from 0 2 to 2 m we acquired data using a 200 mhz pulsed radar system with the antennas mounted in the bottom of a small rubber boat that was pulled across the stream while triggering the radar at a constant rate we achieved excellent results at all three sites with a clear continuous image of the permafrost boundary both peripheral to and beneath the stream our results demonstrate that gpr can be an effective tool for measuring substream thaw depth copyright 2005 john wiley sons ltd

imaging the subsurface stratigraphy in the ubehebe hydrovolcanic field death valley california using ground penetrating radar abstract ground penetrating radar gpr surveys were carried out to collect subsurface images of the basaltic base surge deposits in the ubehebe hydrovolcanic field death valley national park california antennae with frequencies of 50 100 and 200 mhz were used this technique allowed the collection of useful geologic data for example the lower stratigraphic boundary of the pyroclastic deposits can be imaged and their thickness can be estimated different radar responses were also obtained from base surge deposits and underlying sedimentary rocks which enable their recognition where no outcrops are available furthermore gpr data confirmed the presence of small eroded craters which are partially filled by alluvium in this case an unconformity between the overlying horizontally bedded alluvium and the underlying bowl shaped base surge deposits can be recognized within the crater and the thickness of the alluvium estimated common mid point cmp surveys suggested subsurface velocities of the electromagnetic waves in the upper part of these deposits between 0 095 0 1 m ns

2 hydrothermal ore deposits related to post orogenic extensional magmatism and core complex formation the rhodope massif of bulgaria and greece abstract the rhodope massif in southern bulgaria and northern greece hosts a range of pb zn ag cu mo and au ag deposits in high grade metamorphic continental sedimentary and igneous rocks following a protracted thrusting history as part of the alpine himalayan collision major late orogenic extension led to the formation of metamorphic core complexes block faulting sedimentary basin formation acid to basic magmatism and hydrothermal activity within a relatively short period of time during the early tertiary large vein and carbonate replacement pb zn deposits hosted by high grade metamorphic rocks in the central rhodopean dome e g the madan ore field are spatially associated with low angle detachment faults as well as local silicic dyke swarms and or ignimbrites ore formation is essentially synchronous with post extensional dome uplift and magmatism which has a dominant crustal magma component according to pb and sr isotope data intermediate and high sulphidation pb zn ag au deposits and minor porphyry cu mo mineralization in the eastern rhodopes are predominantly hosted by veins in shoshonitic to high k calc alkaline volcanic rocks of closely similar age base metal poor high grade gold deposits of low sulphidation character occurring in continental sedimentary rocks of synextensional basins e g ada tepe show a close spatial and temporal relation to detachment faulting prior and during metamorphic core complex formation their formation predates local magmatism but may involve fluids from deep mantle magmas the change in geochemical signatures of palaeogene magmatic rocks from predominantly silicic types in the central rhodopes to strongly fractionated shoshonitic bulgaria to calc alkaline and high k calc alkaline greece magmas in the eastern rhodopes coincides with the enrichment in cu and au relative to pb and zn of the associated ore deposits this trend also correlates with a decrease in the radiogenic pb and sr isotope components of the magmatic rocks from west to east reflecting a reduced crustal contamination of mantle magmas which in turn correlates with a decreasing crustal thickness that can be observed today hydrogen and oxygen isotopic compositions of the related hydrothermal systems show a concomitant increase of magmatic relative to meteoric fluids from the pb zn ag deposits of the central rhodopes to the magmatic rock hosted polymetallic gold deposits of the eastern rhodopes

middle miocene latitudinal climatic gradient in western europe evidence from pollen records abstract pollen analysis of sections spanning the middle miocene langhian and serravallian from southern spain to switzerland has been carried out with the aim of reconstructing the existing latitudinal environmental gradient floral assemblages indicate a tropical subtropical to warm temperate climate for the entire area during the middle miocene the presence in all pollen spectra of taxa with high temperature requirements demonstrates that the latitudinal gradient in temperature was relatively low the development of a diverse subarid flora in southern spain including neurada lygeum prosopis calligonum nitraria caesalpiniaceae etc points to a very dry climate with a marked seasonality these features clearly indicate that a very warm and dry climate i e a steppe environment was already present during the langhian in the northwestern mediterranean area on the other hand milder conditions are progressively inferred towards the north as subdesertic elements gradually disappeared and taxa with higher water requirements increased the latter dominates the pollen assemblages in the eastern central part of france and switzerland thus precipitations would have been evenly distributed throughout the year we interpret this gradient from subdesertic vegetation in the south to humidity adapted plant environments in the north as the result of a latitudinal gradient in precipitation

internal structure of mixed sand and gravel beach deposits revealed using ground penetrating radar mixed sand and gravel beaches are a distinctive type of coarse clastic beach ground penetrating radar gpr and photographic records of previous excavations are used to investigate the stratigraphy and internal sedimentary structure of mixed beach deposits at aldeburgh in suffolk south east england the principles of radar stratigraphy are used to describe and interpret migrated radar reflection profiles obtained from the study site the application of radar stratigraphy allows the delineation of both bounding surfaces radar surfaces and the intervening beds or bed sets radar facies the deposits of the main backshore berm ridge consist of seaward dipping bounding surfaces that are gently onlapped by seaward dipping bed sets good correspondence is observed between a sequence of beach profiles which record development of the berm ridge on the backshore and the berm ridge s internal structure the beach profile data also indicate that backshore berm ridges at aldeburgh owe their origin to discrete depositional episodes related to storm wave activity beach ridge plain deposits at the study site consist of a complex progradational sequence of foreshore berm ridge overtop and overwash deposits relict berm ridge deposits separated by seaward dipping bounding surfaces form the main depositional element beneath the beach ridge plain however the beach ridges themselves are formed predominantly of vertically stacked overtop overwash units which lie above the berm ridge deposits consequently beach ridge development in this progradational mixed beach setting must have occurred when conditions favoured overtopping and overwashing of the upper beachface interannual to decadal variations in wave climate antecedent beach morphology shoreline progradation rate and sea level are identified as the likely controlling factors in the development of such suitable conditions

the pb isotope geochemistry of granitoids from the himalaya tibet collision zone implications for crustal evolution abstract pb isotopic data on 80 k feldspars from six individual granitoid belts of the himalaya tibet collision zone are reported the isotopic trends observed in the trans himalayan complex which outcrops along the indus zangpo suture zone are best explained by a mixture of mantle derived pb component s with crustal derived pb these confirm that the batholith was built upon sialic continental crust as a result of the northward subduction of mesozoic oceanic crust beneath southern tibet the pb isotopic compositions of k feldspars from the three granitoid belts located within the lhasa block to the north of the indus zangpo suture zone are all radiogenic and indistinguishable from those of k feldspars extracted from basement rocks no pristine mantle derived component was identified and the granitoids are interpreted as being wholly derived from the partial melting of the continental crust furthermore the isotopic compositions of the granitoids are remarkably similar over the entire lhasa block implying that they were equilibrated by fluid remobilization during granulite facies metamorphism in the lower crust to the south of the indus zangpo suture zone and within the indian shield the lead isotopic composition of k feldspars from two granitoid belts although significantly more radiogenic than those of the lhasa block are identical to that of the basement gneisses indicating also that the granitic melts are the products of the anatexis of the continental crust in both the lhasa block and the indian shield the generation of granitic melts occurred as a consequence of large scale intracontinental thrusting events that created crustal repetition and induced the development of thermal anomalies at depths due to the burial of meta sedimentary rocks rich in water and radioactive heat producing elements the lhasa block and the indian shield define two distinct pb isotopic provinces which have undergone complex episodes of u th pb fractionation and are largely composed of precambrian material furthermore the correspondence between distinct pb isotopic provinces and discrete continental segments might indicate that the blocks originated from different sectors of the gondwanian continent