jurassic and cretaceous rhyncholites cephalopod jaws from the north atlantic ocean deep sea drilling project leg 1 79 and their european counterparts well established species of non nautilid jaws rhynchoteuthis palaeoteuthis andleptocheilus from the european continent and north africa have been found in pliensbachian and oxfordian to barremian beds of the north atlantic ocean deep sea drilling project boreholes 1 547b the rhyncholites from dsdp cores demonstrate stratigraphic condensation redeposition and changing palaeoceanographical conditions during the late jurassic being characteristic tethyan organisms such rhyncholites can also be used as index fossils and indicators for palaeobiogeography palaeobathymetry and palaeoclimate most likely the rhyncholites described here could be calcified upper jaws of phylloceratid or lytoceratid ammonites

calcareous nannofossil zonation of the jurassic cretaceous boundary interval and correlation with the geomagnetic polarity timescale abstract calcareous nannofossil stratigraphy has been investigated in six european land sections and at two deep sea drilling project sites 391c and 534a ranging from the upper kimmeridgian to the lower valanginian most of the sections contain a continuous record of the jurassic cretaceous boundary interval a time of rapid increase in nannofossil abundance and diversity and allow development of a revised nannofossil zonation scheme for this period numerous nannofossil lineages have been studied in detail and the results help to increase potential stratigraphic resolution in this interval the proposed scheme consists of six zones which are units recognizable in all sections regardless of nannofossil preservation and eleven subzones determinable in all but the most poorly preserved material thirty eight additional biohorizons are proposed based on the stratigraphy of the two dsdp sites these can be accurately established only in moderately well preserved material but spotty occurrences of these taxa in other sections may be stratigraphically useful most of the sections studied have been investigated magnetostratigraphically and the results of this study allow correlation between nannofossil zonation and the geomagnetic polarity time scale magnetostratigraphy indicates that many nannofossil events can be quite precisely determined and are not significantly time transgressive finally the magnetostratigraphic definitions of two stage boundaries are refined the kimmeridgian tithonian and berriasian valanginian boundaries are placed within chrons cm22n and cm15n respectively two new genera faviconus and umbria and seven new species are described umbria granulosa rhagodiscus nebulosus cretarhabdus octofenestratus faviconus multicolumnatus nannoconus infans nannoconus compressus and nannoconus wintereri eight subspecies and three taxonomic emendations are also described

investigation of groundwater contamination using electric and electromagnetic methods at an open waste disposal site a case study from isparta turkey geophysical methods when integrated with soil chemical and hydrogeological methods can be used to investigate groundwater contamination direct current dc resistivity geo electrical sounding and very low frequency electromagnetic vlf em data were collected at an open waste site used by the municipality of the city of isparta turkey the groundwater at shallow depths in alluvium which is composed of gravel sand and clay were expected to be hazardously contaminated under and around the open waste disposal site in which both household and industrial wastes are known to be disposed of improperly in this study we mapped the spread of groundwater contamination using a vlf em method which allows fast and inexpensive data collection the method complements the results of geo electrical sounding there is a good correlation between the results of the vlf em and the dc resistivity methods employed for the investigation of subsurface structure of the site where soil chemical and previous hydrogeological surveys have indicated high levels of chemical concentrations

linear filtering of vlf dip angle measurements the suggested interpretation technique is based on discrete linear filtering of vlf data the output of the described filtering results is expressed in terms of an equivalent current density at a specified depth that would cause the measured magnetic field the most practical six point filter gives an accuracy of 8 the filter is an extension of the commonly used fraser filter to process vlf dip angle data filtering the same data set for various depths gives an idea about the change of current density with depth areas with high current density correspond to good conductors the conductor dip can also be determined the use of the technique is illustrated on theoretical and field examples in all cases a good correlation with original models and other types of geophysical measurements was obtained as shown in the last example the filtering technique is also applicable in interpretation of other electromagnetic methods

induced polarization detection and mapping of contaminant plumes several laboratory and scaled model investigations suggest that organic contaminants affect the surface electrical properties of exposed soils rocks and therefore produce measurable induced polarization ip signatures however there is little field evidence of an ip methodology for contaminant mapping a2d time domain ip method is developed for mapping the fs12 contaminant plume at the massachusetts military reservation mmr located in cape cod massachusetts the fs 12 plume consists of approximately 265 m 3 of fuel that erupted from a broken underground pipeline in the early 1970s benzene and ethylene dibromide edb are the primary contaminants at fs 12 with concentrations exceeding the allowed maximum concentration levels mcl while other constituents of the plume did not exceed their mcl therefore the contaminants of interest are benzene and edb partly because of their health risk and partly because they present the highest concentrations 2400 and 1000 g l respectively among the plume constituents and are therefore more likely to be related to the polarization source ip data were acquired along a survey line that partially transects the plume extending over contaminated and uncontaminated zones and were inverted to give 2d resistivity and chargeability plots to 100 m depth and a horizontal extent of 400 m by separately inverting ip data derived from time windows located at short and long decay times a timedomain gross spectral chargeability difference is produced both the chargeability and gross spectral chargeability difference show good agreement with the known location of the plume from monitoring wells with the ip chargeability section suggesting contaminant distribution detail that cannot otherwise be inferred from the sparse borehole distribution

correlations of hauterivian and barremian early cretaceous stage boundaries to polarity chrons recent ammonite finds in italian maiolica limestones allow direct correlation of hauterivian and barremian ammonite zones stage boundaries to polarity chrons at laghetto and alpetto lombardy italy lower aptian ammonites occur just above polarity zone m0 and below the selli level and upper barremian ammonites occur in polarity zone m1n these correlations are consistent with the barremian aptian boundary being close to older boundary of polarity chron cm0 the uppermost hauterivian ammonite faraoni guide level has been correlated to cm4 at bosso umbria marche confirming the recent correlation of the hauterivian barremian boundary to cm4 at monte acuto umbria marche ammonites spanning the valanginian hauterivian boundary interval and the last appearance of the nannofossil t verenae occur close to the cm11 cm11n boundary the valanginian hauterivian boundary has previously been placed between the first appearance of l bollii and the last appearance of t verenae or between cm10 and cm11 the published polaveno lombardy magnetostratigraphy for the cm3 cm11 interval has now extended to cm16 this 260 m section recording the cm3 cm16 interval is the most complete single section record of cretaceous m sequence polarity chrons no diagnostic ammonites have been found in this section however the correlations of nannofossil and calpionellid events to polarity chrons are consistent with previous studies

integrated stratigraphy and palaeoenvironmental interpretation of the upper kimmeridgian to lower berriasian pelagic sequences of the velykyi kamianets section pieniny klippen belt ukraine abstract a continuous sedimentary and stratigraphic record of late kimmeridgian early berriasian age is presented from the pelagic succession from the eastern part of the pieniny klippen belt velykyi kamianets section ukraine the studied section 26 m thick was calibrated using biostratigraphy calpionellids calcareous dinocysts calcareous nannofossils magnetostratigraphy stable isotope stratigraphy 13c and 18o and gamma ray spectrometry magnetic polarity zones from m23r to m18n were identified the magnetostratigraphic calibration of calcareous dinocysts zonation around the kimmeridgian tithonian boundary has been performed for the first time the carpistomiosphaera borzai committosphaera pulla calcareous dinocyst zonal boundary is situated at the bottom of magnetozone m22n slightly lower than first occurrence of calcareous nannofossil conusphaera mexicana minor and higher than the standard kimmeridgian tithonian boundary m22ar m22an hybonoticeras beckeri hybonoticeras hybonotum ammonite zone boundary the position of the tithonian berriasian boundary in the magnetosubzone m19n2n crassicollaria calpionella calpionellid zonal boundary has been confirmed a decrease of terrigenous input and an increase of carbonate productivity correlate with increasing sedimentation rates from 0 7 to 1 1 m myr in the upper kimmeridgian m23r to m22r to 5 7 m myr in the uppermost tithonian and lower berriasian m19n to m18n transition between the saccocoma and calpionellid microfacies occurs in a narrow time interval mostly within polarity subchron m20n1r this event is traceable in similar stratigraphic position in several western tethyan sections and correlates perfectly with nannofossil calcification event of the early late tithonian

mapping oil contaminated sand and till with the spectral induced polarization sip method the laboratory and field results from an environmental application of the spectral induced polarization sip method are presented the phase spectra of the resistivity of uncontaminated glacial till silt sand and gravel were measured in the laboratory the effects of waste oil and motor oil on the phase and amplitude spectra of the resistivity were studied using artificially contaminated sand and till samples and mineral soil samples from real waste sites field ip and sip measurements were also made at the waste sites the laboratory phase spectra of sands and tills were straight or slightly concave upwards in a log log plot the phase angle varies between 0 1 and 20 mrad at 1 hz frequency and increases towards higher frequencies with a slope of 0 15 0 25 in laboratory tests motor oil and waste oil changed the phase and amplitude spectra of sand and till at first the amplitude and phase decreased due to oil contamination later during continued maturation both the amplitude and phase increased after a few days or weeks of maturation some of the contaminated samples showed a convexupwards phase spectrum the features observed in artificially contaminated samples were also detected in the sample material from real waste sites furthermore the in situ results from the waste sites were in agreement with the laboratory results in laboratory tests the phase spectra of clean sand and till remained stable with time whereas the phase spectra of oil contaminated samples changed with increasing maturation time this together with the field results suggests that differences between the spectra of clean and polluted soils and also changes occurring in the phase spectra of contaminated soils with time can be indicative of contamination

a palaeomagnetic study of the upper mesozoic succession in northern tunisia summary the upper mesozoic section from northern tunisia provided an upper jurassic palaeomagnetic pole of 65 2 s 20 3 e ag5 6 1 calculated from the means of normal and reversely magnetized samples from the uppermost callovian oxfordian kimmeridgian and portlandian rocks in general the only cretaceous rocks to yield acceptable results were the few samples collected from fresh outcrops a polarity sequence can be established for the upper jurassic which can be correlated with the oceanic keathley anomaly sequence one consequence of the proposed correlation of the oceanic anomaly with the terrestrial palaeomagnetic sequence is to suggest a slightly different age for the oxfordiankimmeridgian boundary one interpretation of the frequent intermediate directions of magnetization in the cretaceous sequence is that there may be a number of unrecognized short period reversals within the cretaceous and more particularly during the so called cretaceous normal period

paleomagnetic evidence for rotation of the iberian peninsula and the external betic cordillera southern spain abstract paleomagnetic investigations of jurassic cretaceous and tertiary sites in the external betic cordillera indicate that while the observed remanence vectors have inclinations which are conformable with the expected inclinations for stable iberia declinations deviate significantly these results indicate that 1 the mesozoic limestones of the penibetic have been rotated clockwise with respect to stable iberia and 2 there is a differential rotation between the cretaceous sites dec 61 11 and the jurassic sites dec 38 8 the differential rotation of 23 between the late jurassic and late cretaceous is consistent with the cretaceous anticlockwise rotation of the iberian peninsula with respect to eurasia it follows that during this time period this part of the betic mobile belt waspart of the continental margin of the iberian peninsula a study which was confined to a single unbroken stratigraphic section west of ronda indicates that most of the anticlockwise rotation 20 probably occurred between the cenomanian and the campanian the anticlockwise rotation of these rocks must have been followed by a clockwise rotation of at least 60 to account for the observed clockwise declination anomalies

assessing preferential seepage and monitoring mortar injection through an earthen dam settled over a gypsiferous substrate using combined geophysical methods abstract for several decades the sant llorenc de montgai reservoir has experienced different problems that could affect the safety of the engineering structure for this reason several corrective actions have been taken over the years here we present a study involving complementary geophysical methods including electrical resistivity tomography seismic refraction tomography and frequency domain electromagnetic surveys the analysis of the inverted electrical resistivity tomography cross sections combined with the seismic refraction results and land subsidence monitoring data show the likely mechanism of abnormal seepage the areas where mortar injections were applied as a corrective measure are also clearly delineated in addition the evolution of the state of the embankment has been established from two successive electrical resistivity tomography surveys in the last two decades the results show areas where corrective mortar injections have been effective while in other areas new abnormal seepage has been detected the lithological heterogeneity of the bedrock especially the dissolution of gypsum rich rocks induced subsidence effects and caused abnormal seepage in different areas along the embankment our results indicate how corrective solutions can be optimized to reduce the cost of corrective engineering interventions

oxfordian magnetostratigraphy of poland and its correlation to sub mediterranean ammonite zones and marine magnetic anomalies abstract a nearly continuous magnetostratigraphic polarity pattern was compiled from several ammonite zoned carbonate successions of southern poland and from a composite magnetostratigraphy from the iberian range of spain the array of sections spans the middle two thirds of the oxfordian within the sub mediterranean province cordatum through bifurcatus ammonite zones the average paleopole calculated from eight of these polish sections is at 78 5 n 184 9 e p 2 6 m 3 5 the sub mediterranean polarity pattern is consistent with an independent polarity pattern derived from the boreal realm sections of the british isles and improves the inter correlation between these faunal realms cycle stratigraphy published for these ammonite subzones from southern france enabled temporal scaling of the polarity pattern thereby facilitating correlation to marine magnetic anomalies m28 through m33 as modeled from deep tow magnetometer surveys in the western pacific the bases of the middle and upper oxfordian substages as defined in the sub mediterranean zonation in poland correspond approximately to chrons m33 and m29 of that pacific m sequence model

mapping groundwater contamination using dc resistivity and vlf geophysical methods a case study geophysical methods can be helpful in mapping areas of contaminated soil and groundwater electrical resistivity and very low frequency electromagnetic induction vlf surveys were carried out at a site of shallow hydrocarbon contamination in utah county utah previously installed monitoring wells facilitated analysis of water chemistry to enhance interpretation of the geophysical data the electrical resistivity and vlf data correlate well and vertical cross sections and contour maps generated from these data helped map the contaminant plume which was delineated as an area of high interpreted resistivities

magnetostratigraphy of early middle toarcian expanded sections from the iberian range central spain abstract the magnetostratigraphy of the lower middle toarcian has been established in two well dated stratigraphically expanded sections the sierra palomera and the arino sections located in the iberian range in central eastern spain two magnetisation components could be isolated by thermal cleaning a secondary syntectonic component of always normal polarity unblocking at intermediate temperatures up to 450 c 475 c a component and a high temperature unblocking component up to 575 c b component the b component passes fold and reversal tests and is considered the characteristic remanent magnetisation of primary origin the first toarcian palaeomagnetic pole for iberia has been obtained plat 77 4 plon 241 3 e dm 5 4 dp 6 0 five pairs of normal and reversed polarity zones were calibrated to regional ammonite subzones the pattern can be calibrated to other toarcian magnetostratigraphic studies but provides a more detailed biostratigraphic framework a refined magnetic polarity time scale is proposed for the lower middle toarcian

geomagnetic reversal history the history of geomagnetic polarity reversals in the cenozoic and late mesozoic is well known since the late jurassic oxfordian a continuous record of polarity has been derived for this time interval from the interpretation of oceanic magnetic anomalies most of the polarity chrons in this oceanic record have been verified and dated in coordinated magnetostratigraphic and biostratigraphic studies this has led to the generation of progressively refined and improved geomagnetic reversal time scales that provide a framework for absolute dating of palaeontological zonations by serving as a basis for statistical analysis of reversal frequency they provide information relevant to processes in the earth s core the rate of reversals since the late cretaceous shows a steady increase on which a cyclical variation appears to be superposed a stochastic model for reversals predicts a poisson distribution of polarity interval lengths the polarity time scales contain many fewer short 50 kyr polarity chrons than a poisson distribution and it has been suggested that a gamma renewal process with index greater than unity is a more appropriate statistical model the statistical arguments give no convincing reason for abandoning the model and other physical reasons must be sought to explain the incompleteness of the reversal record the discovery and verification of short chrons in the oceanic record may best be investigated by deep tow magnetometer surveys the reversal history before the late jurassic is not well known magnetostratigraphy in coeval early jurassic sections has not given correlatable records and it has not been possible to compile a definitive polarity sequence evaluation of geomagnetic polarity history for the early mesozoic and the palaeozoic will require unambiguous magnetostratigraphy in well dated sections where verification of the polarity pattern is possible at the fossil zone or stage level

carbonate hosted shallow submarine and burial hydrothermal mineralization in the upper mississippian big cove formation port au port peninsula western newfoundland strata bound sulfide zn pb fe and sulfate ba sr mineralization occurs in upper mississippian arundian holkerian limestone primarily bryozoan microbial mounds of the big cove formation on the port au port peninsula western newfoundland stages of host rock petrogenesis and mineralization are compared by integrating structure stratigraphy petrography and geochemistry fluid inclusions and c o s sr and pb isotopes strata bound mineralization is linked to fault controlled fluid flow through ordovician basement carbonate and into porous mississippian host rock with subsequent fluid migration bounded by stratigraphic permeability barriers mineralization is preferentially juxtaposed to deposits of mississippian gypsum the most likely source of sulfate the 87 s 86 sr ratios in calcite associated with mineralization suggest that fluids were most likely generated from or had undergone isotopic exchange with lower paleozoic strata including potentially metalliferous shale the integrated database underscores a potentially rapid mineralizing system of late mississippian 343 330 ma age evidence for isotopic exchange brings a permo pennsylvanian 250 300 ma age derived from lead isotope modeling into question minor syndepositional mineralization is characterized by fe oxide stained omission surfaces within well oxidized hyposaline lithofacies possibly documenting incipient hydrothermal activity and subsequent marcasite mineralization related to introduction of hydrothermal 60 degrees 120 degrees c brines into a very restricted hyposaline or lacustrine setting during faulting prominent zn pb sulfides sphalerite galena and subsequent ba sr sulfates barite celestite with intergrown marcasite and calcite have a shallow burial 30 m origin fluids were variably hot 110 degrees 190 degrees c mg poor brines 20 25 wt nacl equiv pyrite gossans mark a last stage of mineralization the delta 34 s values increase with the general successon of sulfide 4 to 12ppm sulfate 20 32ppm and then pyrite 32ppm mineralization similar to a rayleigh distillation process in a closed mineralizing system mineralization on the port au port peninsula is similar to mississippian hosted irish zn pb deposits there is an association with normal faults prominent epigenetic mineralization and a similar age this commonality may reflect late mississippian tectonic instability within the paleohemispheric fault system that linked eastern canada and ireland

one hundred million years of geomagnetic polarity history since 1968 absolute ages have been assigned to the late cretaceous cenozoic geomagnetic reversal time scale by fixing the ages of two or more calibration points in a composite marine magnetic anomaly profile and interpolating between or extrapolating beyond these points assuming constant spreading rates in each interval previously no more than 4 calibration points were used but it is now possible to specify 11 calibration points in addition to the 0 m y datum this improvement is based on magnetostratigraphic studies in italian pelagic limestones these studies closely tie the geomagnetic reversal sequence to the foraminiferal and coccolith zonations absolute ages of calibration points are provided by the best available dates on stage boundaries which are located from the biostratigraphic zonation the greatest changes from previous scales come in the late paleocene early eocene where the new ages are as much as 3 m y younger than in the 1977 scale of labrecque and others and as much as 1 8 m y younger than in the 1980 scale of ness and others

jurassic magnetostratigraphy 2 middle late oxfordian of aguilon iberian cordillera northern spain abstract a reproducible magnetic polarity pattern has been obtained from four overlapping stratigraphic sequences of ammonite rich gray pelagic limestones spanning part of the middle and late oxfordian g transversarium toe bimammatum ammonite zones progressive thermal demagnetization removed a present field overprint fold tests both between and within outcrops are positive the mean direction of magnetization is 322 45 95 6 which implies a paleolatitude of 26 n frequent changes of polarity were observed the magnetostratigraphic sequence contains the ammonite zones subzones and horizons of the tethyan faunal realm using the reference horizons provided by this detailed ammonite zonation the polarity zones can be readily correlated among all sections the composite polarity pattern is predominantly of reversed polarity punctuated by a number of relatively shorter duration normal polarity intervals in order to compare this sequence to that of the marine magnetic anomalies we have revised the age estimates for the pre m25 marine magnetic normaly pattern according to the most recent time scale based on those ages the sedimentary record at aguilon suggests a much greater frequency of polarity changes than does either model derived from the two sets of marine magnetic anomalies of this time this sedimentary record probably is a truer approximation of the actual geomagnetic polarity history because of the continuity of sedimentation in these sections and the inherent ambiguities involved in determining a polarity pattern from the very low amplitudes that everywhere characterize this part of the marine record

benthonische foraminiferen aus der unterkreide des deep sea drilling project leg 1 79 in den dsdp legs 1 11 13 17 25 27 32 36 41 43 44 50 und 62 wurden die unterkreide foraminiferen biostratigraphisch taxonomisch und palaookologisch bearbeitet eine ubersicht zeigt die in leg 1 80 erbohrte unterkreide und ihre foraminiferen bearbeitungen

magnetic susceptibility and vlf r investigations for determining geothermal blowout contaminated area a case study from alasehir manisa turkey western turkey is one of the most spectacular regions of widespread active continental extension in the world the most prominent structures of this region are e w trending gediz and buyuk menderes grabens geothermal activity around city of manisa in gediz graben has been investigated by many researchers and many geothermal boreholes were drilled in order to produce electricity in the middle of may 2012 a geothermal blowout occurred 150 m away from the deep drilling depth 1 100 m in alkan village of alasehir resort in city of manisa after that four big blowouts took place at the same area and thermal water had been diverted to alkan stream for almost 4 months the boron b and fe levels of thermal water are 87 and 11 2 ppm where the background b and fe values of topsoil vary between 0 2 1 5 ppm and 3 08 5 63 ppm respectively the objective of this study was to utilize joint magnetic susceptibility and vlf r investigations to determine possibly contaminated area with b related to high fe level on the topsoil and thermal water in the subterranean layers it is observed that magnetic susceptibility values vary between 500 and 790 cgs 10 6 in the vicinity of blowouts and 150 340 cgs 10 6 at a distance of 50 m around where the background average value is 20 cgs 10 6 by using the data collected at 346 stations besides the vlf r studies were carried out along 18 profiles at three different frequencies laterally constrained two layer inversion was applied to each station in addition to the inversion of all profiles for each frequency all lines were stacked 2 d resistivity maps were obtained and the contaminated area was determined approximately as 35 000 m2 the results show not only satisfactory agreement between magnetic susceptibility and vlf r data but also provide fast and valued interpretation of geochemical and geophysical properties of the geothermal contaminated area

high resolution geophysical characterization of shallow water wetlands we describe a procedure for rapid characterization of shallow water contaminated wetlands terrain conductivity tc vertical magnetic gradiometry and surface waterchemistry data were obtained from a shallow draft paddleboat operable in as little as 0 3 m of water measurements were taken every 2 s with data acquisition rates exceeding 10 kmofline12 000datapointsper8 hrfieldday we applied this procedure to an urban wetland that is affected by point and nonpoint sources of pollution we used a one dimensional laterally constrained inversion algorithm toinverttheapparent conductivitydatasetobtainedfromthe tcsurveyandtocreateapseudo 2dimageofsedimentconductivity the continuously recorded surface water depth and conductivity values were input as a priori information in theinversion weusedsoilchemistrydeterminedfor28sediment samples collected from the site as well as lithologic logs from across the wetland to constrain interpretation of thegeophysicaldata theinvertedsedimentconductivitydescribes a pattern of contamination probably attributable to leachates from adjacent landfills and or to saltwater ingress from a partial tidal connection that is not obvious in the surface water data magnetic gradiometry values and the inphasecomponentofanem31responsebothreflectprimarily thedistributionofjunkmetalassociatedwithalegacyofillegal dumping historic aerial photographs suggest that this distribution reflects land use history and defines the maximum previous extent of an adjacent landfill and a pattern of dumpingcorrelatedwithhistoricroadways

synfolding magnetization in the jurassic preuss sandstone wyoming idaho utah thrust belt the jurassic preuss sandstone exposed in five thrust plates of the wyoming idaho utah thrust belt carries directions of remanent magnetization that group most tightly after only partial unfolding field petrographic and rock magnetic evidence indicates that the carrier of this magnetization is detrital low ti titanomagnetite the detrital titanomagnetite was remagnetized at low temperatures 75 150 c probably completely during folding anisotropy of magnetic susceptibility and petrographic observations indicate that the detrital titanomagnetite has been affected by tectonic strain we suggest that low temperature remagnetization of the detrital titanomagnetite was either a viscous partial thermoremanent magnetization the acquisition of which was enhanced by stress or a piezoremanent magnetization that involved stress induced movement of domain walls during intracrystalline strain or was a combination of the two mechanisms stress may promote remagnetization at temperatures much lower than predicted by current theoretical models other mechanisms such as acquisition of chemical remanent magnetization during folding deflection of a prefolding magnetization by internal strain or combination of components of magnetization with different direction cannot account for the geometry of magnetization in the preuss the locus of acquisition of synfolding magnetization in the preuss migrated in conjunction with deformation in the thrust belt a model is presented in which synfolding magnetization was acquired during cooling and folding as strata moved up thrust ramps a lack of reverse polarity directions remains a puzzling feature of the remanence the remanent direction is tentatively interpreted to reflect the predominant polarity state during its acquisition over an extended rather than a discrete time period during folding in late cretaceous and early tertiary periods of predominantly normal polarity

biostratigraphic correlation of mesozoic polarity chrons cm1 to cm23 at capriolo and xausa southern alps italy abstract two pelagic limestone sections in the southern alps spanning the kimmeridgian late jurassic to barremian early cretaceous interval yield magnetostratigraphies which can be correlated to oceanic magnetic anomalies m1 m3 and m8 m23 this includes the interval m11 m13 which has not previously been correlated to a sedimentary section detailed investigations of nanofossils and calpionellids in these sequences allow precise correlation of polarity chrons to biostratigraphic events and these results compare favorably to those of previous studies the close correspondence in polarity pattern between that interpreted from the m8 to m15 interval in the hawaiian lineations and that recorded at the capriolo section suggests that sedimentation rates in this sequence and spreading rates in the hawaiian lineations were rather constant during this interval in contrast the sedimentation rate at the xausa section appears to increase up section with the facies transition from the rosso ammonitico to the maiolica formation

jurassic magnetostratigraphy 3 bathonian bajocian of carcabuey sierra harana and campillo de arenas subbetic cordillera southern spain abstract four sections in majocian bathonian middle jurassic pelagic limestone with standard ammonite zonation have yielded magnetic polarity sequences magnetic directions in these red to white limestones were obtained by thermal demagnetization and were stable from about 300 c to in excess of 450 c the polarity patterns indicate that the majority of the bajocian and bathonian is characterized by quite frequent reversals of the magnetic field lengthy periods of constant polarity particularly constant normal polarity were not observed the average frequency of reversals is about 6 per ammonite zone which roughly may be interpreted as a frequency of a reversal every 260 000 years a rate comparable to that of the miocene pliocene paleolatitudes of these sites 25 28 are about 10 south of their present positions variable clockwise block rotations within the subbectic region have rotated these sites relative to stable iberia

contamination indications derived from electrical properties in the low frequency range1 electrical measurements are an important and integrated component of geophysical investigations connected with environmental problems as a result of an analysis of the electrical conductivity basic experiments on sandstones at frequencies below 10 khz show that the complex behavior of conductivity is caused exclusively by a complex interface conductivity its value is determined mainly by the internal rock interface to porosity ratio the composition of the pore fluid and connected matrix water interactions resulting in a specific microstructure of the interface therefore it can be expected that the interface region of a soil or rock material is very sensitive to changes in composition caused by contamination contaminated sandstone and clay samples were investigated using a low frequency measurement system the investigations are directed at the influence of different contaminants and their concentration results show that the complex electrical conductivity real and imaginary parts is influenced by properties of the pore filling contaminant this influence results in a change of the level of both parts and the shape of their frequency dependence the imaginary part in particular seems to provide important secondary information in some cases this part alone allows a differentiation of the various contaminants the different behavior of various rock types showsmore that the effects observed are the result of interactions between pore fluid properties and the internal pore surface structure less

investigation of seawater intrusion in the dibdibba aquifer using 2d resistivity imaging in the area between al zubair and umm qasr southern iraq electrical resistivity surveying for delineating seawater intrusion was performed in the dibdibba aquifer in the area between the cities of al zubair safwan and al zubair umm qasr in the vicinity of khor al zubair channel basrah governorate southern iraq fourteen 2d resistivity profiles with a total length of 14 km were collected in the study area the resistivity sections were compared with lithological data extracted from 11 boreholes thirty nine groundwater samples were collected within the area and analyzed for chemical constituents internal hydrogeological reports and unpublished studies were also evaluated results reveal the existence of three major resistivity layers ranging from 0 1 to 130 m at various depths and locations the first layer has very low electrical resistivity 0 1 5 m representing a layer saturated with saltwater intruded from khor al zubair channel the second layer shows resistivity in the range of 5 130 m attributed to a transition zone and an unaffected zone saturated with brackish groundwater the last resistivity layer 3 m represents coarse grain sediments saturated with saline groundwater furthermore a hard clay bed jojab appears with a resistivity of 3 7 m in all 2d imaging lines within a depth of 20 28 m electrical conductivity ec measurements from seven wells collected in 2014 and 2016 show a positive ec difference increasing landward with an average increase of 1927 s cm in addition six chemical relationships na cl ca mg hco3 so4 so4 hco3 so4 cl mg ca and cl hco3 co3 are used to detect the source of salinity in groundwater this study proves that extensive use of high resolution 2d imaging sections alongside lithological and hydrogeological data can serve as a useful tool to delineate the boundaries between aquifers identify hydraulic boundaries between groundwater with different salinities and allocate hard clay layers between the upper and lower dibdibba aquifer in general the combination of 2d imaging and hydrochemistry enables conceptualization of the hydrogeological situation in the subsurface and characterization of the salinity source here seawater intrusion in the study area there have been no studies published so far on the characteristics of saltwater intrusion in the study area and this study is considered to be important for monitoring and studying the intrusion and regression of seawater

paleomagnetic results from mallorca balearic islands spain we studied the paleomagnetism of jurassic limestones on the island of mallorca balearic archipelago western mediterranean to determine if two thrust sheets exhibiting different structural patterns were rotated relative to one another after correction for tilt the circle of confidence for the mean paleomagnetic direction from sites in areas associated with frontal ramps overlaps with the confidence circle of the mean for those sites associated with oblique lateral ramps this indicates that there has been no differential rotation in spite of the fact that the fold axes in these areas trend almost perpendicular to one another although the age of magnetization is prefolding i e before oligo miocene it is not certain that the paleomagnetic directions reflect jurassic magnetization since they may have been acquired during a period of emersion in the upper cretaceous or paleocene the resulting mean direction for nine sites from both thrust sheets declination 41 inclination 48 95 7 implies significant clockwise rotation of the whole island or at least of the mesozoic cover since acquisition of magnetization if part of this rotation occurred as we believe in the neogene then structural data from pre miocene rocks must be corrected before being used for regional tectonic interpretation the mechanism to produce 40 of clockwise rotation since the oligo miocene could be combined regional extension alpine compression and block rotation

preliminary non intrusive geophysical electrical resistivity tomography surveys of a mock up scale monitoring of an engineered barrier system at url tournemire

lower cretaceous benthic foraminifera from dsdp site 263 micropalaeontological constraints for the early evolution of the indian ocean analysis of 66 samples from dsdp site 263 cores 263 4r 4 to 263 29r 4 reveals a unique faunal composition with a predominance of agglutinated taxa many of them previously unrecorded from any other dsdp and odp indian ocean sites a total of 66 agglutinated and 31 calcareous taxa are documented and five new species are described hippocrepina gracilis n sp textulariopsis elegans n sp aaptotoichus challengeri n sp gaudryinopsis pseudobettenstaedti n sp and gaudryina cuvierensis n sp three assemblages are recognized based on changes in the composition of dominant taxa and occurrences of stratigraphically important species 1 a high diversity valanginian to barremian bulbobaculites recurvoides assemblage cores 263 29r to 18r comprised of numerous elongate agglutinated forms rare nodosariids and variable numbers of tubes and ammodiscids 2 a moderately diverse aptian to albian rhizammina ammodiscus glomospira assemblage cores 26318r to 7r with highly fluctuating numbers of the nominate taxa and haplophragmoides trochammina verneuilinoides spp and vemeuilina howchini 3 a very low diversity albian or younger assemblage cores 263 6r to 4r containing sparse agglutinated foraminifera rare nodosariids and rotaliids we interpret the assemblages as shelf to lower slope and consider them to reflect a deepening palaeobathymetry as the cuvier margin subsided after the initial breakup of east gondwana during the valanginian our interpretation is in sharp contrast with initial palaeodepth estimates of less than 100 m as well as with original chronostratigraphic interpretations based on foraminifera and nannofossils which correlated the base of the recovered interval with the aptian the absence of many cosmoplitan forms despite high diversity suggests strong faunal differentiation in the austral realm or endemisn within the cuvier basin during the early cretaceous

a magnetic polarity time scale for the early cretaceous and late jurassic abstract the ages of polarity chrons in previous m sequence magnetic polarity time scales were interpolated using basal sediment ages in suitably drilled dsdp holes this method is subject to several sources of error including often large paleontological age ranges magnetostratigraphic results have now tied the early cretaceous and late jurassic paleontological stage boundaries to the m sequence of magnetic polarity the numeric ages of most of these boundaries are inadequately known and some have been determined largely by intuition an examination of relevant data suggests that 114 ma 136 ma and 146 ma are optimum estimates for the ages of the aptian barremian cretaceous jurassic and kimmeridgian oxfordian stage boundaries respectively each of these boundaries has a good correlation to the m sequence of magnetic reversals the magnetostratigraphic tie level ages are linearly related to the spreading distance and have been used to calculate a new magnetic polarity time scale for the early cretaceous and late jurassic all stage boundaries in this time interval were correlated by magnetic stratigraphy to the proposed new time scale which was then used to estimate their numeric ages these are with the approximate relative errors of placement within the m sequence aptian barremian 114 ma 0 5ma barremian hauterivian 121 ma 2 0 1 5ma hauterivian valanginian 126 ma 0 5 3 0ma valanginian berriasian 131 ma 0 5 2 5ma berriasian tithonian 136 ma 1 0ma tithonian kimmeridgian 143 ma 0 5ma kimmeridgian oxfordian 146 ma 0 2ma the absolute errors of these interpolated stage boundary ages depend on the accuracy of the tie level ages

waveform tomography at a groundwater contamination site surface reflection data wehaveappliedacoustic waveformtomographyto452d seismic profiles to image the 3d geometry of a buried paleochannel at a groundwater contamination site at hill air force base in utah the paleochannel which is incised into an alluvium covered clay aquitard acts as a trap for dense nonaqueous phase liquids dnapls that contaminate the shallowest groundwater system in the study area the 2d profiles were extracted from a 3d surface reflection data set first arrival traveltime tomography provided initial velocity models for the waveform tomography we inverted for six frequency components in the band 30 90 hz of the direct and refracted waves to produce 45 2d velocity models the flanks and bottom of a channel with a maximum depth of about 15 m were well modeled in most of the 45 parallel 2d slices whichallowedustoconstructa3dimageofthechannel by combining and interpolating between the 45 image slices the 3d model of the channel will be useful for siting extraction wells within the site remediation program the alluvium that fills the channel showed marked vertical and lateral velocity heterogeneity traveltime tomography and waveform tomography can be complementary approaches used together they can provide high resolution images of complicatedshallowstructures

mapping of subsurface contamination zone using 3d electrical resistivity imaging in hilla city iraq electrical resistivity imaging eri method is very useful in mapping subsurface contamination zones in this study 3d eri is used to identify the distribution and depth of subsurface soil contamination zone near al furat state company for chemical and pesticides industries in hilla city iraq a 3d pure image of electrical resistivity distribution is obtained from a perpendicular square grid 80 80 m which consists of three parallel and three perpendicular lines the electrical resistivity values range from 1 to 21 o m and the total root mean square rms after four iterations is about 7 the image gives eight different depth slices for the estimated model with a depth interval of about 1 m the maximum depth of investigation is 13 7 m the results mapped the contamination zone where high electrical resistivity values about 21 o m are observed possibly due to accumulation of alkaline waste disposed from the company the eri results show that the subsurface layers up to a depth of 4 99 m are of moderate to high electrical resistivity values the study reveals that 3d eri is an effective tool for subsurface contamination zone mapping in various depths which extends in this study from the near surface to a depth of about 5 m below the ground level

palaeomagnetic rotations in the eastern betic cordillera southern spain palaeomagnetic declinations from the external zones of the eastern betic cordillera southern spain and an adjacent area of the internal zone indicate variable and locally very large clockwise rotations the rotations occurred after latest oligocene times and probably before the late miocene this overlaps a period of dextrally oblique convergence during the early to middle miocene along the internal external zone boundary and within the external zone rotations in the external zone are recorded by palaeomagnetic results from 27 sites in upper jurassic ammonitico rosso facies limestones from the subbetic zone and one site of a similar age from the prebetic the sites show either two or three component behaviour the low temperature component is coincident with the present field direction the intermediate temperature component was probably acquired during miocene folding the high temperature component passes fold tests miocene age and a conglomerate test eocene early oligocene age palaeomagnetic declinations from individual tectonic blocks in the subbetic are consistent but indicate large differential rotations between blocks these blocks are underlain by low angle thrust faults which probably accommodated much of the rotation the largest rotations occur on relatively small isolated blocks of jurassic carbonates in a highly deformed triassic evaporite sequence the single site in the prebetic has not rotated significantly relative to stable iberia in malaguide rocks of the sierra espun a in the adjacent internal zone stable palaeomagnetic components were measured at one site in upper miocene sedimentary rocks at three sites in upper oligocene lower miocene red marls at one site in oligocene marls at one site in jurassic limestones and at two sites in permo triassic red beds the palaeomagnetic results suggest that about 60 of clockwise rotation occurred in the latest oligocene earliest miocene and a further 140 of clockwise rotation subsequently one site in late miocene sedimentary rocks yields unrotated declinations which if not representing an overprinted direction indicate that the rotation was complete by the end of the miocene

jurassic magnetostratigraphy 1 kimmeridgian tithonian of sierra gorda and carcabuey southern spain abstract two coeval sections of red to white ammonite rich pelagic limestones spanning the complete kimmeridgian and most of the tithonian were sampled in detail all samples were treated by progressive thermal demagnetization to remove a present field overprint characteristic magnetization is carried primarily by magnetite polarity intervals are easily identified and correlate well between the two sections the tithonian polarity sequence can also be correlated to sections in northern italy the similarity between the polarity sequence and the m sequence of marine magnetic anomalies coupled with the precise biostratigraphic control allows assignment of the following ages to the m sequence the late early tithonian boundary is correlated to the end of m 20 the tithonian kimmeridgian boundary to the end of m 23 the late early kimmeridgian boundary to the latter part of m 24 and the kimmeridgian oxfordian boundary within or slightly after m 25 the mean directions of characteristic magnetization have 95 s less than 3 and demonstrate extensive differential block rotation within the subbetic province paleolatitudes during the kimmeridgian tithonian are in the range of 16 24 n

new palaeomagnetic data from the betic cordillera constraints on the timing and the geographical distribution of tectonic rotations in southern spain a palaeomagnetic investigation has been carried out at 14 sites on jurassic red nodular limestones from the central and eastern part of the external zones of the betic cordillera subbetic and prebetic zones progressive thermal demagnetisation of samples from the subbetic zone reveals the presence of two stable magnetic components of the natural remanent magnetisation 1 a secondary neogene syn folding component and 2 the original jurassic magnetisation as similar characteristics have been reported in jurassic limestones from the western subbetic zone a widespread remagnetisation event took place within 106 years in the entire subbetic region during neogene times in contrast in the prebetic region no evidence for a secondary overprint has been detected palaeomagnetic jurassic declinations indicate variable and locally very large clockwise rotations 35 140 but the two sites in the north westernmost part of the investigated region are not rotated the use of both components of magnetisation and the incremental fold test results allowed the timing of block rotations in the subbetic zone to be constrained rotations in the western subbetic occurred after the acquisition of the secondary overprint whereas in the central part of the subbetic zone they were completed by the time of the remagnetisation event

palaeomagnetic rotations in opposite senses in southeastern spain 20 volcanic and 3 sedimentary sites of upper miocene age were sampled in the cabo de gata region in southeastern spain palaeomagnetic and rockmagnetic investigations yielded useful results in 15 volcanic and 1 sedimentary site clockwise and anticlockwise block rotations of adjacent blocks could be observed the age of these rotations is younger than tortonian deformation in the eastern part of the betics seems to follow a different pattern than in the central and western part of the subbetic this behaviour can be related to the crustal structure in the eastern betics

combining geophysical techniques and multi criteria gis based application modeling approach for groundwater potential assessment in southwestern nigeria a new approach of modeling very low frequency electromagnetic vlf em and vertical electrical sounding ves data with a view of evaluating groundwater resources potential via application of gis based multi criteria technique is investigated in this study on eight vlf em traverses established in the site 40 ves locations were combed the acquired geophysical data vlf em and ves were processed applying fraser karous hjelt filter and win resist program geophysical software to determine the area subsurface geophysical parameters five hydrogeologic maps were produced based on the results of the interpreted geophysical parameters the produced hydrogeologic maps were assigned suitable weights and different rankings to the individual classes boundary within the maps using the standard saaty s scale principle in the context of analytical hierarchy process ahp data mining technique a raster based empirical gis model was developed for integrating the hydrogeologic maps to compute the groundwater potential index gwpi values in the range of 1 02 2 82 for the study area based on the estimated gwpi results a final map zoning the area into low 0 0930 1 3922 medium 1 3922 1 9109 and high 1 9109 2 8173 groundwater potential classes was produced in gis environment the prediction accuracy of the produced potential map was established via cross validation and in situ well correlation analysis the results of the study established a new approach of modeling geophysical data for exploring groundwater productivity potential in the study area

magnetostratigraphy of the jurassic cretaceous boundary in the maiolica limestone umbria italy the magnetic stratigraphy of a 110 m section of the early cretaceous maiolica pelagic limestone in the bosso valley umbria italy shows clearly defined magnetozones that are correlated with the geomagnetic polarity record derived from the m sequence marine magnetic anomalies m19 to m14 and possibly m13 using an established paleontological zonation of this section based on calpionellids the position of the jurassic cretaceous boundary is located close to the base of the negative magnetozone corresponding to anomaly m17

case study a 3d resistivity and induced polarization imaging from downstream a waste disposal site in brazil a contaminated site from a downstream municipal solid waste disposal site in brazil was investigated by using a 3d resistivity and induced polarization ip imaging technique this investigation purpose was to detect and delineate contamination plume produced by wastes the area was selected based on previous geophysical investigations and chemical analyses carried out in the site indicating the presence of a contamination plume in the area resistivity model has successfully imaged waste presence 31 mv v water table depth and groundwater flow direction a higher chargeability zone m 31 mv v outside wastes placement and following conductive anomaly was interpreted as a contamination plume normalized chargeability mn m confirmed polarizable zone which could be an effect of a salinity increase contamination plume and the clay presence in the environment

atlantic paleobathymetry paleoproductivity and paleocirculation in the late albian the benthic foraminiferal record spatial distribution patterns of benthic foraminifers in upper albian sediments from 25 dsdp odp sites and 31 onshore sections of the north and south atlantic ocean are used to generate paleobathymetric reconstructions and to identify areas of high primary production such as coastal and equatorial upwelling zones new paleobathymetric estimates are provided for dsdp odp sites and onshore locations that are not situated on oceanic crust paleobathymetric reconstructions indicate shallow water exchange between the north and south atlantic but show the existence of a deep water connection between the western and eastern tethys 2500 m through the gibraltar gateway strikingly there is no evidence for a strong latitudinal gradient in deep water benthic foraminiferal distribution during the late albian south atlantic assemblages show close affinity to north atlantic and tethyan assemblages exhibiting only a minor degree of provincialism biogeographic patterns reveal a distinct asymmetry in late albian paleoproductivity for the north atlantic as for the present day the eastern margins of the atlantic were generally more productive than the western margins and a belt of enhanced carbon aux export to the seafloor can be traced around the north african coast which probably corresponded to a zone of vigorous coastal upwelling by contrast assemblage composition in the south atlantic generally reflects mesotrophic to oligotrophic conditions benthic foraminiferal distribution patterns thus provide robust proxy data to test predictions from paleocirculation and paleobathymetric models for the mid cretaceous atlantic ocean and adjacent margins c 2001 elsevier science b v all rights reserved

study of a permafrost area in the northern part of siberia using controlled source radiomagnetotellurics controlled source radiomagnetotelluric csrmt measurements with a horizontal electrical dipole were carried out for the planned construction of a railway bridge in the northern part of siberia the yamalo nenets region the aim of this survey was the delineation of horizons of loams which are mostly thixotropic and the estimation of the depth of solid sands serving as a basement for bridge piles the remote area of the investigation is characterized by a few number of broadcasting radio transmitters therefore the possibilities of the conventional radiomagnetotelluric rmt method to study the geological structure are quite limited because of swamps the construction area is only accessible in winter or early spring periods our csrmt survey was carried out by using ungrounded capacitive electric lines the measurements were conducted in the broadside configuration using a 580 m long grounded electrical line at a distance of about 640 m from the transmitter at the first stage of the csrmt data inversion we used the 1d controlled source inversion code considering the geometry of the source and the effect of the transition zone in addition we selected frequencies associated with the far field response of the electromagnetic field to demonstrate the advantages of the controlled source we compared the responses and inversion results obtained from both csrmt and rmt data the geoelectrical section obtained from csrmt data is more detailed in the shallow part and allows to resolve the deep structures because of an extended frequency range and an increased depth of investigation the conductivity model derived from the 2d inversion of the csrmt data showed a good correlation with the borehole data the csrmt results were very useful for the construction of the railway bridge because of the reliable delineation of loams and sands horizons in the subsurface

magnetostratigraphy in pursuit of missing links since the last quadrennial report magneto stratigraphy has continued to flourish the primary issues have been 1 refinements to the geomagnetic reversal time scale grts including recalibrations correlation of biostratigraphic data to the crts and revision of the terminology 2 use of magnetostratigraphic data for estimating rates of such processes as sediment accumulation evolution and faunal migration and 3 magnetic mineralogy and the origin of remanence for convenience we have divided the publications into studies of continental and marine sediments and highlight the most exciting issues within each of these sub headings in the first section of this review we will concentrate on the development of the geomagnetic reversal time scale grts with particular emphasis on refinements from the last few years we then turn our attention to applications of magnetostratigraphy in marine and continental sequences

temporal geophysical signatures from contaminant mass remediation we have previously documented changes in bulk electrical conductivity self potential sp and ground penetrating radar gpr reflections in a field setting caused by biogeochemical transformations of hydrocarbon contaminated media these transformations are associated with hydrocarbon biodegradation the results of surface geophysical surveys acquired in 1996 2003 and 2007 document changes in geophysical signatures associated with removing hydrocarbon mass in the contaminated zone initial investigations in 1996 showed that relative to background the contaminated area was characterized by higher bulk electrical conductivity positive sp anomaly and attenuated gpr reflections repeated surveys in 2003 and 2007 over the contaminated area showed that in 2007 the bulk electrical conductivityhad reverted to near background conditions the positive sp anomaly became more negative and the zone of attenuated gpr reflections showed increased signal strength removal of hydrocarbon mass in the vadose zone o

electrical properties of partially saturated sandstones novel computational approach with hydrogeophysical applications 1 electric and electromagnetic geophysical tools are suitable methods for investigating moisture content transport and storage properties of the subsoil with noninvasive surveys interpretation of field data is still based on empirical or semiempirical equations which must be calibrated with complex time consuming laboratory measurements in this paper we develop pore scale models suitable for computing the effective electric conductivity and the effective permittivity of partially saturated porous media on the basis of simple structural parameters grain size distribution and porosity we compute the electrical conductivity with three approaches that model the conductivity of the shell of coating clay around solid grains of shaly sandstones using different assumptions we compare the simulated results with experimental data from sherwood sandstone uk and discuss the effect of these assumptions on the effective conductivity simulations performed using a modeling approach that accounts for interaction between volume and surface conduction show an excellent agreement with experimental data we also model the effective permittivity of the same porous medium at several saturation values and obtain a good match with laboratory measurements

3d behaviour of contamination in landfill sites using 2d resistivity ip imaging case studies in portugal aiming at defining a valid spatial contamination model resistivity and induced polarization ip measurements were used to investigate contamination plumes in the vicinity of two municipal landfills ovar and ilhavo previous geophysical surveys and underground water samples confirmed the contamination however 2d resistivity ip surveys enabled in obtaining a more accurate spatial model the ovar survey consisted of two profiles with nine wenner soundings each the ilhavo survey was carried out along two individual lines using a wenner standard pseudo section in both situations negative ip values were found associated with positive ip values which can be explained mainly by 2d or 3d geometric effects caused by the presence of the conductive plumes the data were modelled using a 2d inversion program res2dinv and the resulting resistivity and chargeability distributions were displayed as pseudo sections the resistivity and chargeability pseudo sections define the contamination plumes and the sedimentary structure these case studies illustrate the advantages of 2d resistivity ip surveys for the mapping of shape and dimension of contamination associated with landfills

waveform tomography at a groundwater contamination site vsp surface data set application of 2d frequency domain waveform tomography to a data set from a high resolution vertical seismic profiling vsp experiment at a groundwater contamination site in hill air force base hafb utah reveals a surprisingly complicated shallow substructure with a resolution of approximately 1 5 m variance in the waveform misfit function is reduced 69 4 by using an initial velocity model from first arrival traveltime tomography the waveform tomography model suggests 1 a low velocity layer at 1 to 4 m depth 2 a high vertical velocity gradient of 80 m s m on average and 3 severe lateral variations velocity contrasts as large as about 200 m s occur in a distance as short as 1 5 m the model is well correlated with lithologic logs and is interpreted geologically a q value of 20 is estimated for the target area the extreme lateral and vertical variations of the subsurface compromise many standard seismic processing methods

integrated geophysical approach in assessing karst presence and sinkhole susceptibility along flood protection dykes of the loire river orleans france abstract non invasive geophysical methods are often used for detecting near surface defects and monitoring seepage in river dykes or dams between 2008 and 2009 a series of geophysical experiments was conducted to detect karst features below the dykes of the loire river orleans france multi channel analysis of seismic surface waves masw was used to obtain the shear wave velocity vs profile of the subsurface below the dykes as an effective approach to investigating the structure of the dykes multi channel resistivity surveys were also used to evaluate the electrical properties of material inside and under the dykes this study discusses the exploration strategy and results for several sections of the dyke system based on the experimental data vs contours are used to geometrically and qualitatively describe the subsurface under the dykes and identify areas of mechanical weakness corresponding to karst features while resistivity contours allow distinguishing interactions between the karst and the dykes through the identification of areas of downward material movement known and unknown anomalies are identified a practical approach that combines seismic and electric resistivity results is proposed to assess karst presence and sinkhole hazards along the investigated dykes using a susceptibility index referring to the likelihood level of the events as a validation method areas of strong karst susceptibility index along the dykes are compared to known collapse event sinkholes dyke breaches etc locations available in databases

effects of longitudinal variability of soil on a continuous spread footing abstract a simple model describing the soil foundation interaction for continuous wall footing and which takes longitudinal variations in soil s properties into account is presented in this paper this model has been developed using a finite element representation in which a 1d structure continuous spread footing rests on a spatially variable soil described by winkler type springs characterized by the subgrade reaction coefficient geotechnical pressuremeter tests and geophysical vlf r very low frequency resistivity mode surveys performed over a selected study area resting on an alluvial terrace were used to provide information on the soil s variability and to reveal the presence of clayey soil three kinds of natural variability are considered natural soil variations rapid variations in the soil s properties and shrinkage of clayey soil a relationship between the coefficient of subgrade reaction and the resistivity was observed the spatial variability of the coefficient of subgrade reaction was analyzed using geostatistics and then used in the model to derive differential settlements and bending moment values of a continuous spread footing which cannot be predicted if the soil is assumed to be homogeneous or if shrinkage under the continuous wall footing is not taken into account results show that as is often the case in practice when the longitudinal soil variability is not taken into account the design may be unsafe

dielectric spectroscopy of sedimentary rocks a physiochemical model for the complex dielectric response of sedimentary rocks is used to invert broadband dielectric spectra for effective grain size distributions the complex dielectric response of each grain within the water wet granular matrix is obtained by superimposing the polarization of the electrochemical double layer which is assumed to surround each grain with the complex dielectric response of the dry mineral grain the effective complex dielectric response of the water wet matrix grains and surface phase is obtained by volume averaging over the entire distribution of particle sizes the complex dielectric response of the total mixture water wet matrix and bulk pore solution is obtained using the bruggeman hanai sen effective medium theory studies of berea sandstone show that the grain size distribution obtained by inverting the real part of the complex dielectric spectra is similar to the grain size distribution obtained from optical images of the sample in thin section the current model however does not account for surface roughness effects or the polarization of counterions over multiple grain lengths therefore the grain size distribution obtained by dielectric spectroscopy is broader than the image derived distribution the dielectric derived grain size distribution can be fit with two separate power laws that crossover at r 1 m which corresponds to a relaxation frequency of 2 khz the low frequency dielectric response f 2 khz is primarily controlled by the clay size grains and surface roughness which has a fractal dimension of d 2 48 0 07 at very low frequencies f 0 1 hz the dielectric response appears to be controlled by the electrochemical polarization of counterions over multiple grain lengths a more general model should account for the effects of surface roughness and grain interactions on the dielectric response it would also be useful to develop a simplified version of this model perhaps similar in form to the empirically derived cole cole response which could be more easily used to model and interpret electrical geophysical field surveys e g induced polarization ground penetrating radar and time domain reflectometery measurements

palaeomagnetic rotations and fault kinematics in the rif arc of morocco palaeomagnetic and structural investigations in the rif arc of morocco indicate that there have been large rotations associated with a pattern of outwardly directed thrusting rock magnetic experiments in conjunction with thermal and alternating field demagnetization demonstrate that eight sites in jurassic and cretaceous limestones along the internal external boundary have a stable remanent magnetization this is in most cases rotated anticlockwise by as much as 100 from the expected mesozoic declination but in the tetuan area there are large clockwise rotations kinematic indicators from fault surfaces indicate the following 1 in the eastern rif there has been predominantly south directed thrusting partly overprinted by extensional and sinistral strike slip faults 2 at the eastern end of the n 70 e striking jebha fault zone there is a pattern of dominant sinistral ne trending and subsidiary dextral se trending strike slip faults overprinted by normal faults while at the western end deformation consists largely of south directed thrusting 3 in the northern section of the chain where the structural trends are dominantly n s thrusting is directed w to nw it is suggested that the data are best explained by differential motion and rotation of thrust sheets during outwardly directed thrusting around the arc

3d geostatistical inversion of induced polarization data and its application to coal seam fires we applied the principal component geostatistical approach pcga to the inversion of time domain induced polarization data in terms of resistivity and chargeability distributions the pcga presents two major advantages over standard methods 1 it avoids the storage of the usually large covariance matrix which contains the geostatistical information by factorizing it in a product of low rank matrices 2 it does not assemble the jaco bian matrix per se we determine the robustness of this approach with three examples we first reconstruct the electrical conductivity and chargeability fields of two synthetic models generated using the geostatistical software stanford geostatistical modeling software the pcga approach performs better than the tikho nov based regularization approach when the true fields are very heterogeneous and the amount of data is limited the third example is devoted to a field study over the former lewis coal mine in colorado usa we perform a 3d localization of the burning front of this coal seam fire by applying our geostatistical inverse methodology to a time domain induced polarization data set in this case the horizontal components of the semivariogram are determined from a self potential map and the correlation length scale for the vertical component is determined from the known thickness of the coal bed the tomogram presents a high normalized chargeability associated with the burning front we evaluate the high normalized chargeability of the burning front in terms of the physical mechanism associated with the cation exchange capacity of the coal and the effect of temperature this demonstrates the potential of the geostatistical inversion and its suitabil ity for inverting geophysical data especially when the data density is sparse in the case of coal seam fires we determine the suitability of the induced polarization method to localize the burning front and the effect of temperature on the normalized chargeability

paleomagnetic constraints on the tectonic evolution of the sakarya continent northwestern anatolia comment abstract thirteen sites were sampled in northwestern anatolia in order to gather paleomagnetic information concerning the tectonic evolution of this region through jurassic to early tertiary time an interval encompassing much of the history of the neo tethys in this area specifically information concerning the history and behaviour of a crustal block the sakarya continent was sought in order to place some constraints on geologic models that have been proposed for the region four jurassic sites are believed to exhibit early magnetization signatures that yield similar paleolatitudes for all sites these results when compared with paleolatitude information for eurasia suggest that sakarya lay in close proximity to the southern eurasian margin at least during the jurassic part of its history significantly different declinations from the same four sites are interpreted to reflect the deformation of sakarya when it docked with eurasia during the early tertiary these rotations are not attributed to motions of the north anatolian fault since results from three paleocene sites in the same area show no evidence of significant rotation with respect to eurasia

a very low frequency electromagnetic study of the geo environmental hazardous areas in taiwan this study utilized the very low frequency electromagnetic vlf em technique a passive electromagnetic prospecting method working in the very low frequency range 15 30 khz to investigate the geo environmental problems of shallow low conductivity sedimentary layers in taiwan field examples successfully demonstrate the advantages of using this method in locating non mineralized shallow fault zones the zero crossings of in phase and quadrature measurements in 2 d contour maps clearly locate the position of subsurface anomalous source bodies further analysis of the measured vlf single profile peaks reveals that this method is useful in determining subsurface structures and conductivity the advantages of nondestructive noninvasive and low consumption of power make this method extremely friendly to the environment the authors anticipate this method will have more profound impacts on the interactions between prospecting technology and the earth

analyzing geophysical signature of a hydrocarbon contaminated soil using geoelectrical surveys in february 1994 a major oil blow out occurred as a consequence of an accident at an exploration drill hole at trecate north west italy more than 15 years after the incident a series of geophysical and hydrogeological surveys were conducted for investigating the hydrocarbon contaminated soil the hydrocarbon is still spatially distributed as residual phase in the unsaturated zone a free phase exists between the transition zone and the vadose zone in what is defined as a smear zone geoelectrical methods have shown their potential in contaminant detection and are increasingly used for contaminated sites characterization we carried out geoelectrical surveys over the most contaminated area of the site in order to analyze the changes in geophysical signature due to the presence of contaminants and furthermore to understand the role of biomass activity in degrading the hydrocarbon and altering petrophysical properties of the soil acquisition of time and frequency domain resistivity data allowed us to approach the same features with different methods providing a better understanding of the problem we further analyzed the role of soil properties on electrical resistivity porosity pore water specific resistivity and the influence of cation exchange capacity on the bulk resistivity at the site the electrical resistivity observed at the site shows a clear relationship with water saturation porosity and soil texture as well as with resistive hydrocarbon species we also monitored soil polarizability in the same frequency range of electrical resistivity measures allowing better delineation of the degrading processes underway in the contaminant which constitutes an additional substrate for the proliferation of anaerobic degraders

benthonische schelf foraminiferen aus dem valanginium hauterivium unterkreide des indischen ozeans sudwestlich madagaskar deep sea drilling project leg 25 site 249 aus 12 radiolarien reichen tonstein proben aus site 249 dsdp leg 25 im westlichen indischen ozean sudwestlich madagaskar werden 4 arten agglutinierter und 38 arten benthonischer foraminiferen beschrieben davon 13 in offener nomenklatur durch das vorkommen zahlreicher valanginium arten und vongavelinella barremiana werden die faunen hier als valanginium hauterivium datiert sie enthalten leitformen der norddeutschen unterkreide und ebenso arten aus dem benachbarten madagaskar die nodosariiden dominieren mit 36 arten vor allem die gattungenastacolus citharina lenticulina lingulina marginulinopsis nodosaria saracenaria undvaginulina wichtige neokomium arten die in anderen dsdp sites vorkommen namentlichpraedorothia ouachensis sigal und planktonische foraminiferen fehlen die faunen aus site 249 werden dem schelfbereich zugeordnet

some paleomagnetic constraints on the tectonic evolution of the coastal cordillera of central chile paleomagnetic samples collected from 19 sites in radioisotopically dated jurassic mafic dykes and plutons in the coastal cordillera of chile between latitude 32 15 and 33 30 s yield paleomagnetic poles calculated by averaging the virtual geomagnetic poles from approximately coeval sites at latitude 85 9 s longitude 36 7 e n 8 a95 11 9 for sites dated at close to 170 ma and at latitude 80 3 s longitude 207 8 e n 10 a95 9 5 for sites dated at close to 145 ma these paleomagnetic poles from the coast of chile coincide with poles from coeval sequences within the south american craton some of the igneous rocks that constitute these sampling sites crosscut a high grade metamorphic complex that is distinct from other segments of the coastal cordillera in age structural style and metamorphic grade this complex cannot be correlated with metamorphic rocks anywhere else in central western south america and could be considered a potentially exotic allochthonous terrane if this terrane has been added to the western south american margin then accretion occurred prior to 170 ma paleomagnetic results presented here indicate that no major rotation or large scale latitudinal translation of crustal blocks has taken place in this part of central chile since middle jurassic time

magnetic stratigraphy of kimmeridgian aptian sections from umbria marche italy new details on the m polarity sequence 1 the magnetic stratigraphy of the maiolica and calcari ad aptici pelagic limestones is documented from four umbro marchean land sections italy the overall biostratigraphic age of the sampled strata encompasses the whole kimmeridgian lower aptian the data were gathered from two new sections arcevia contessa and by resampling more densely than in the past two additional classical sections bosso gorgo a cerbara a detailed record of the polarity chrons m21n m14 and m9 m0 was derived and no difference was observed with respect to the sequence of m polarity chrons inferred from oceanic magnetic anomalies barely measurable remanent magnetization from chron m14 to m10n at contessa concurred with previous evidence from bosso indicating that the maiolica from umbria marche is characterized by a recording gap during chrons m14n to m11 possibly due to diagenetic magnetite dissolution related to the late valanginian carbon isotope event at arcevia and bosso the boundary between maiolica and calcari ad aptici occurs at the top of chron m19n and in the upper part of chron m20n respectively showing that the onset of maiolica sedimentation may be diachronous by 1 5 2 myr along the umbria marche domain arcevia is the most expanded mid upper tithonian land section documented so far here the subchrons m20n 1 and m19n 1 are found to represent 3 2 and 10 1 in time of chrons m20n and m19n respectively evidence is also provided for a reversal excursion occurring within the m20n 1 subchron at bosso an excursion and a reversal excursion were found within chrons m16n and m16 respectively

jurassic magnetostratigraphy 4 early callovian through middle oxfordian of the krakow uplands poland a magnetic polarity pattern has been constructed for the early callovian through middle oxfordian stages of the jurassic from several ammonite rich magnetostratigraphy sections within the krakow czestochowa wielun region of southern poland these overlapping sections encompass portions of every ammonite from the late early callovian through late middle oxfordian however the presence of several hiatuses and condensed intervals within the shallow marine to pelagic sediments preclude reliable identification of the complete polarity pattern the mean callovian oxfordian pole from these sites is at 74 3 n 200 3 e 95 4 7 the callovian through early oxfordian is dominated by reversed polarity with a minimum of five normal polarity zones the early middle oxfordian is predominantly of normal polarity and the late middle oxfordian is characterized by reversed polarity with several relatively brief normal polarity episodes the callovian and oxfordian stages appear to average a minimum of two magnetic polarity reversals per million years this reversal frequency is similar to the average tertiary record but is less than the reported spacing of callovian and oxfordian magnetic anomalies in the pacific

a new fossil vent biota in the ballynoe barite deposit silvermines ireland evidence for intracratonic sea floor hydrothermal activity about 352 ma considerable controversy exists as to the timing of the important mississippian carbonate hosted irish type zn pb ba ag deposits the silvermines deposits have been defined as an end member of this style in that they have been interpreted to display textures indicative of sea floor deposition one of the strongest arguments in favor of this interpretation was the report of a hydrothermal vent field including pyritic chimneys in the ballynoe open pit barite deposit this paper adds to that body of evidence by describing a hydrothermal vent fauna from the same vent field consisting of a delicately pyritized worm tube hosted by massive pyrite and hematized filaments of apparent microbial origin the worm tube is remarkably similar to fossil worm tubes from modern and ancient volcanic hosted massive sulfide deposits and the filamentous microfossils have similarities to modern fe oxidizing bacteria we have found no correlation between the worm tube and normal mississippian fossils such as crinoids whose replacement by pyrite in the immediately underlying ballynoe footwall destroys original morphology the sulfur isotope composition of the worm tube and host pyrite is essentially identical to that of the vent field pyrite and the main sulfide ore stage of silvermines sulfides all having a mean value about 20 per mil indicating an open system bacteriogenic sulfide source these discoveries provide additional evidence for the exhalative nature of parts of the silvermines orebodies and imply that mineralization had begun in the irish ore field by the late tournaisian 352 ma

magnetostratigraphy across the berriasian valanginian stage boundary early cretaceous at cehegin murcia province southern spain abstract the berriasian valanginian stage boundary near the town of cehegin in the eastern subbetic cordillera of spain is documented by a detailed ammonite zonation in pelagic limestones two magnetostratigraphic sections spanning the uppermost ammonite subzone of the berriasian and the lower two zones of the valanginian yielded identical magnetic polarity patterns remanent magnetization is predominantly carried by magnetite and characteristic directions were obtained by thermal demagnetization the mean characteristic directions from both sites have an inclination of 48 however the site declinations are divergent 030 and 074 due to the tectonic disturbance of the region the cehegin polarity pattern can be correlated by means of ammonite and calpionellid zonation to the magnetostratigraphies of the berriasian stratotype and several italian sections thereby enabling a unique correlation to the m sequence magnetic polarity time scale the berriasian valanginian stage boundary is in the middle of normal polarity chron m15n

biostratigraphy and paleoceanography of the cretaceous seaway between norway and greenland abstract the narrow seaway between greenland and norway in cretaceous time was over 1500 km long and 300 km wide and partly of bathyal water depth during aptian through campanian it received a large volume of fine grained siliciclastic sediments with intercalated gravity flow sandstone wedges as a conduit for heat transport between the low latitudes and polar region atlantic watermasses particularly affected the eastern norwegian margin of this seaway despite its high latitude setting calcareous and few siliceous planktonic microfossils thus play an important role in regional stratigraphy and facies analysis and a majority of fossil events correlate to nw european basins the eastern margin sedimentary succession may be subdivided in several broad lithologic units 1 thin multicolored marly sediments of hauterivian barremian age with a shallow marine falsogaudryina nodosariid ostracod assemblage 2 dark mudstones and minor sands aptian early cenomanian in age with an upper bathyal agglutinated assemblage and monotypic hedbergella floods 3 thick mudstone facies with thin slope apron turbidite sands and an impoverished benthic planktonic assemblage of late cenomanian coniacian age deposited in an upper bathyal oxic dysaerobic environment where turonian sedimentation rates are low a planktonic foraminiferal assemblage with whiteinella hedbergella dicarinella and marginotruncana occurs 4 grayish laminated mudstones santonian campanian in age with local sands in the north a low diversity middle to upper bathyal benthic planktonic foraminiferal assemblage and an inoceramus prisms and radiolarian diatom flood a campanian agglutinated foraminiferal bloom also is known from the atlantic oceanic realm 5 more marly sediments of maastrichtian age with a low diversity planktonic benthic foraminiferal assemblage using the distribution of 1755 foraminiferal and dinoflagellate microfossil events in over 30 exploration wells a rasc ranking and scaling probabilistic zonation served as a template to build a cretaceous zonal model with 19 assemblage and interval zones including over 100 events variance analysis ranks 72 events according to reliability in correlation three new index taxa include uvigerinammina una and ammoanita globorotaliaeformis albian and fenestrella bellii campanian widespread planktonic flood events occur in late albian through early cenomanian early mid turonian late santonian earliest campanian and mid maastrichtian the result of northwards shifts of warmer water masses and disruptions in water stratification in the dysaerobic basins an earliest cretaceous hiatus separates jurassic from cretaceous strata ongoing block faulting coupled to thermal subsidence and global sealevel rise increased water depth in aptian albian time from neritic to bathyal and created sand accommodation space in dysaerobic restricted settings in cenomanian coniacian time sedimentation rates in the central basin increased 10 fold whereas paleo waterdepth did not deepen this relatively brief less than 10 m y tectonic episode resulting in deposition of deep water sands is tentatively linked to stress re orientation in the rockall area a widespread upper maastrichtian danian hiatus the result of shoulder uplift reflects break up prior to the onset of paleogene seafloor spreading in the norwegian sea

surface geoelectrics for groundwater pollution and protection studies abstract surface geoelectrical methods are currently used in solving a range of hydrogeological problems involving both quality and quantity issues this is the first of two papers devoted to the use of applied geophysics in solving problems of groundwater protection and pollution detection in this paper attention is focused on the fundamental principles of geophysical surveying for pollution and protection studies geoelectrical methods in particular resistivity methods which are the most widely applicable geophysical method are analysed in detail relations between geoelectrical and hydrogeological parameters are discussed with a view to groundwater pollution as well as methods of measurements and the principles of geophysical and hydrogeological interpretation of results several examples are given to illustrate the principles a future paper will be devoted to presentation of case histories

east west thrusting and anomalous magnetic declinations in the sierra gorda betic cordillera southern spain abstract structural and palaeomagnetic studies in the sierra gorda sierra de loja located in the external zone of the betic cordillera indicate that westward directed thrusting is not associated with significant rotations about a vertical axis detailed mapping and slip vector analysis show that the sierra gorda is a thrust complex composed of three thrust sheets the uppermost thrust places early jurassic pelagic carbonates on top of jurassic to oligocene sediments that form a large doubly plunging footwall syncline the eastern limb of this syncline has been overturned and is tectonically thinned as a result of the overthrusting palaeomagnetic results from mesozoic and tertiary sediments both within and around the perimeter of the sierra gorda indicate that 1 the average remanence vector of the seven late jurassic localities sampled within the sierra gorda has a direction d 328 and i 38 that is not significantly different from the expected declination for the upper jurassic of stable iberia and 2 there is no significant difference between the remanences in the two upper thrust sheets indicating that differential rotation did not occur during the initiation and displacement on the thrusts in contrast the one late jurassic site that was sampled to the west of the sierra gorda is rotated like the rest of the subbetics 60 clockwise of the reference direction the unrotated directions obtained in the sierra suggest either that it has rotated in a clockwise sense concordant with the rest of the subbetic zone and has then been backrotated or that it has never rotated relative to stable iberia in the latter simpler hypothesis the unrotated declinations may be explained in terms of orthogonal convergence along an irregular continental margin

deep tow magnetic anomaly study of the pacific jurassic quiet zone and implications for the geomagnetic polarity reversal timescale and geomagnetic field behavior 1 the jurassic quiet zone jqz is a region of low amplitude magnetic anomalies whose distinctive character may be related to geomagnetic field behavior we collected deep tow magnetic profiles in pigafetta basin western pacific where previous deep tow data partially covered the jqz sequence our goals were to extend the survey through the jqz examine anomaly correlations and refine a preliminary geomagnetic polarity timescale gpts model we collected a series of closely spaced profiles over anomaly m34 and ocean drilling program hole 801c to examine anomaly correlation in detail one profile in between previous profiles and two long profiles extending the survey deeper into the jqz anomaly features can be readily correlated except in a region of low amplitude short wavelength anomalies in the middle of the survey area low amplitude zone or laz the small multiprofile surveys demonstrate anomaly linearity implying that surrounding anomalies are also linear and likely result from crustal recording of geomagnetic field changes we constructed a gpts model assuming that most anomalies result from polarity reversals the polarity timescale is similar to the polarity sequences from previous studies but its global significance is uncertain because of problems correlating anomalies in the laz and the ambiguous nature of the small jqz anomalies overall anomaly amplitude decreases with age into the laz and then increases again implying low geomagnetic field strength perhaps related to a rapidly reversing field other factors that may contribute to the laz are interference of anomalies over narrow crustal polarity zones and poorly understood local tectonic complexities

integrated geophysical studies in the east indian geothermal province integrated geophysical surveys using vertical electrical sounding ves very low frequency vlf em radiation counting total magnetic field and self potential sp measurements are carried out to characterize the geothermal area around a hot spring in the nayagarh district orissa india that lies in the east indian geothermal province the study was performed to delineate the fracture pattern contaminated groundwater movement and possible heating source ves interpretations suggest a three to four layer structure in the area resistivity survey near the hot spring suggests that weathered and fractured formations constitute the main aquifer system and extend to 60 m depth current flow measured at various electrode separations normalized by the applied voltage suggests that fractures extend to a greater depth detailed vlf study shows that fractures extend beyond 70 m depth vlf anomaly has also very good correlation with the total magnetic field measured along the same profiles study results suggest that a gridded pattern of vlf survey could map the underground conductive fracture zones that can identify the movement of contaminated groundwater flow therefore precautionary measures can be taken to check further contamination by delineating subsurface conducting structures self potential sp measured over the hot spring does not show a large anomaly in favor of the presence of a sulphide mineral body a small positive 5 15mv sp anomaly is measured which may be streaming potential due to subsurface fluid flow a high radiation is measured about four kilometers from the hot spring suggesting possible radiogenic heating however the exact nature of the heating source and its depth is not known in the area deep resistivity followed by a magneto telluric survey could reveal the deeper structures

late jurassic early cretaceous magnetic stratigraphy from the sumeg section hungary abstract the pelagic limestones exposed at sumeg appear to represent continuous deposition from kimmeridgian through berriasian detrital magnetite and haematite pigment are the carriers of remanence in the red and non red limestones in the lower part while magnetite becomes predominant in the upper half of the section thermal demagnetization has succesfully removed overprint magnetizations and a well defined magnetic stratigraphy has been obtained the late jurassic early cretaceous mixed polarity interval is correlated with the sequence of geomagnetic reversals derived from oceanic magnetic anomalies

magnetostratigraphy and biostratigraphy of callovian oxfordian limestones from the trento plateau monti lessini northern italy abstract callovian oxfordian ammonitico rosso limestones from the trento plateau carry a characteristic remanent magnetization indicating frequent geomagnetic polarity reversals which can be correlated to callovian oxfordian ammonite zones the characteristic magnetization component has low coercivity and blocking temperatures below 600 c suggesting that magnetite is the carrier the age of the magnetization is not constrained by field tests although sedimentological evidence for early lithification and the close stratigraphic juxtaposition of normal and reversed component directions tend to indicate that acquisition of the magnetization occurred close to the sediment water interface stratigraphic gaps and the condensed nature of the sections inhibit the correlation of polarity reversals between sections the data suggest a reversed polarity bias for the oxfordian and a normal polarity bias for the callovian

soil resistivity a non invasive tool to map soil structure horizonation abstract since geophysical methods are non invasive they can be of great help in soil studies because they disturb neither the structure nor the dynamics of the soil moreover data are acquired with reliable spatial sampling the usual ways of investigation like augering and excavation disturb the soil and are totally incompatible with a spatially dense sampling strategy which would destroy the object of the study both approaches are complementary when excavations have a limited extent and are distributed according to the information conveyed by the geophysical investigation a basic principle of applied geophysics is to measure different physical parameters without direct access to the studied volume horizontal and or vertical variations of the parameter s can be recorded possible soil parameters should be restricted to measurements which do not alter the medium reversible effect to be significant the variations of the parameter s should exhibit a wide dynamic range over different soil types and should be correlated in some way to soil parameters such as particle size or hydraulic conductivity after summarising the soil properties two examples are shown whereby electrical resistivity was used the first example is a specific soil so called hardpan sandy soil in arid area in lagadge north cameroon using resistivity surveys the three dimensional extension of a very coherent horizon was mapped this horizon is delineated by low resistivities 10 ms m because of the disposition of clay particles around the quartz grains in a second example a homogeneous area ought to be found delimit the extent of a surface where a pesticide transfer experiment is to take place accurate mapping of soil horizons was not feasible by augering resistivity data have clearly shown the three dimensional extension of clayey horizons in the complex delta context

integrated geological and geophysical exploration for concealed ores beneath cover in the chaihulanzi goldfield northern china an integrated geological and geophysical investigation was carried out in the near mine areas of the chaihulanzi gold field inner mongolia northern china to determine the south eastern strike extension of the principal mineralized shear system in the search for new resources in this case study surface geophysical surveys played an important role in defining the mineralized structures beneath cover a re investigation of the mine geology by observing the underground exposures of mineralization and its hosting structures coupled with re evaluation and re examination of previous exploration data revealed that the mineralization style at the chaihulanzi gold field is not the skarn type as previously assumed but is structurally controlled by an oblique sinistral shear structure moreover a south eastward shallow plunging mineralized corridor within the principal mineralized shear system was also identified implying that the ore forming fluid flow might move through the mineralizing system from the south east at depth to the north west these new geological findings imply that the mineralized shear system should extend much farther south eastwards along strike beneath cover and thus a conceptual target area was proposed a detailed geophysical survey program involving the application of vlf em stratagem eh4 csamt and gradient ip measurements was carried out to test the validity of the conceptual target orientation surveys on the geologically known line 18 traverse revealed that vlf em and stratagem eh4 were the most effective methods of detecting the unseen mineralized system whereas csamt could only provide low resolution data and ip proved to be unsuitable in this environment due to the ubiquitous presence of graphite bearing schists in and around the mineralized system a follow up systematic vlf em survey highlighted the principal mineralized shear system as a linear conductive belt tracing the principal mineralized system for a further 750 m of strike length beneath cover from the previous exploration limit line 18 stratagem eh4 soundings over six parallel traverses perpendicular to the mineralized trend revealed that the principal mineralized shear structure extends for more than 500 m in the dip direction a strong indication of the presence of potential deep mineralization under the surveyed area detailed modelling of the stratagem eh4 sounding images provided well defined targets for test drilling subsequent test drilling on some of these targets returned encouraging results as several core intercepts of economic gold mineralization were encountered this led to a more extensive drilling and underground prospecting program focusing on deep mineralization south eastwards along the mineralized trend

mapping the flow pathways and contaminants transportation around a coal washing plant using the vlf em geo electrical and ip techniques a case study ne iran coal washing operation is now being carried out in the alborz sharghi plant located in northeast of iran this can in effect create a number of environmental problems in this research different geophysical surveys were conducted to investigate the leachate flow pathways and time dependent transportation of contaminants in downstream of the plant which is situated between a coal waste pile and tailings impoundments the very low frequency survey identified the most likely contamination zones and flow pathways furthermore two dimensional resistivity models obtained by the inversion of geoelectrical data measured with the use of a dipole dipole array incorporating a time laps technique showed the contaminated plumes with low resistivity values 1 m to carry out a time laps technique 2 d geoelectrical surveys were repeated at same profiles by a time interval of 6 months the results distinguished a time dependent movement of the plume in a lateral and longitudinal form as well as its further extension to the deeper layers towards the groundwater table this was also verified by the results obtained by the induced polarization measurements

fast imaging of subsurface conductors using very low frequency electromagnetic data the study presents a fast imaging technique for the very low frequency data interpretation first an analytical expression was derived to compute the vertical component of the magnetic field at any point on the earth s surface for a given current density distribution in a rectangular block on the subsurface current density is considered as exponentially decreasing with depth according to the skin depth rule in a particular block subsequently the vertical component of the magnetic field due to the entire subsurface was computed as the sum of the vertical component of the magnetic field due to an individual block since the vertical component of the magnetic field is proportional to the real part of very low frequency anomaly an inversion program was developed for imaging of the subsurface conductors using the real very low frequency anomaly in terms of apparent current density distribution in the subsurface imaging results from the presented formulation were compared with other imaging techniques in terms of apparent current density and resistivity distribution using a standard numerical forward modelling and inversion technique efficacy of the developed approach was demonstrated for the interpretation of synthetic and field very low frequency data the presented imaging technique shows improvement with respect to the filtering approaches in depicting subsurface conductors further results obtained using the presented approach are closer to the results of rigorous resistivity inversion since the presented approach uses only the real anomaly which is not sensitive to very small isolated near surface conducting features it depicts prominent conducting features in the subsurface

no extinctions during oceanic anoxic event 1b the aptian albian benthic foraminiferal record of odp leg 171

the geochemical record of hydrothermal mineralization and tectonism inboard of the appalachian orogen the ottawa embayment abstract the history of mineralization of the ottawa embayment includes migration of basin brines within the confines of an early paleozoic basin and cross stratal fracture flow linked to structural reactivation of an underlying neoproterozoic failed rift system paleoporosity consists of paleokarst pal in lower ordovician dolostone beekmantown group and fractures now veins that cross cut both lower paleozoic pl and precambrian pc strata a series of contrasting mineral assemblages which define changing fluid compositions fill paleokarst cavities and rare interconnected paleofractures now veins first there is an early pal succession of quartz saddle dolomite then calcite with accessory hydrocarbon as well as sulphide and sulphate minerals the quartz defines migration of saline 20 wt silica brines and hydrocarbon that spans a temperature increase defined by fluid inclusions from 13 c of the dolomite identifies strong sedimentary rock water interaction but a depleted 13 c composition 14 for the calcite illustrates that with cooling paleokarst cavities were sites of bacterially mediated sulphate reduction remaining paleokarst porosity is filled with a late pal mineral assemblage that contains low temperature mostly

inversion of induced polarization data we present an algorithm for inverting induced polarization ip data acquired in a 3 d environment the algorithm is based upon the linearized equation for the ip response and the inverse problem is solved by minimizing an objective function of the chargeability model subject to data and bound constraints the minimization is carried out using an interior point method in which the bounds are incorporated by using a logarithmic barrier and the solution of the linear equations is accelerated using wavelet transforms inversion of ip data requires knowledge of the background conductivity we study the effect of different approximations to the background conductivity by comparing ip inversions performed using different conductivity models including a uniform half space and conductivities recovered from one pass 3 d inversions composite 2 d inversions limited aim updates and full 3 d nonlinear inversions of the dc resistivity data we demonstrate that when the background conductivity is simple reasonable ip results are obtainable without using the best conductivity estimate derived from full 3 d inversion of the dc resistivity data as a final area of investigation we study the joint use of surface and borehole data to improve the resolution of the recovered chargeability models we demonstrate that the joint inversion of surface and crosshole data produces chargeability models superior to those obtained from inversions of individual data sets

a radiomagnetotelluric survey on an oil contaminated area near the brazi refinery romania scalar radiomagnetotelluric measurements were carried out on a contaminated test area close to the brazi refinery in romania in order to detect and to monitor a 1 m thick oil layer expected at 5 m depth radio transmitters broadcasting in a frequency range from 10 khz to 300 khz were selected to observe the apparent resistivity and the phase data associated with the e and b polarizations they were located parallel and perpendicular to the assumed strike direction of the contamination plume the data were interpreted by a 2d inversion technique from which the conductivity structure of the area was derived the 2d inversion models of all profiles on the contaminated area show a poor conductivity zone above the groundwater table which could be associated with the oil contamination a first attempt was also made to monitor the contaminated layer the radiomagnetotelluric measurements were repeated on the same profiles a year later but this time in a dry period not in a rainy one the 2d inversion results of the measurements in the dry period indicate that the high resistivity layer moved closer to the surface additional reference measurements were then carried out on a non contaminated area situated at a distance from the refinery in the opposite direction to the flow of the groundwater these reference measurements were used for the derivation of the unperturbed geology and they were also compared with the measurements of the contaminated test area there is a significant difference in the frequency dependences of the apparent resistivities of the reference and contaminated areas which could indicate a contamination at shallow depth the 2d inversion results show the increase of resistivity at a depth of about 5 m beneath the contaminated area where the oil contamination is expected according to the information from the boreholes

an integrated magnetotelluric and gamma exploration of groundwater in fractured granite for small scale freshwater supply a case study from the boshan region shandong province china exploration and use of groundwater in hard rocks is a difficult but yet a significant issue especially when the local surface water source is polluted in this study integrated geophysical and nuclear methods are used to delineate groundwater bearing zones in a granite terrain in the boshan region shandong province china structural analysis showed that fractures extend in a nw se direction which is the same as the direction of river valley a controlled source audio frequency magnetotelluric survey conducted along the river valley indicated several different low resistivity anomalies or potential water bearing fracture zones they are seated at depth ranges down to 400 m from the surface along the river valley the locations of deep water bearing zones were further confirmed by higher gamma radiation measurements found near the river valley a fault with a nw se strike near the river was deduced as an anomalous water bearing zone two tube wells were drilled targeting at the water bearing zone that has achieved single well water yield greater than 360 m3 day the well water was sampled for water chemistry and stable isotope analyses shallow groundwater samples show similar water chemistry and isotopic feature to river water indicating connection between the two deep groundwater from the water bearing fracture zones is not hydraulically connected with shallow groundwater ensuring safety of the deep groundwater in the granite from being affected by the polluted shallow groundwater or river water integrated geophysical and gamma exploration methods helped to identify two disconnected groundwater systems offering an alternative freshwater source for the region if shallow groundwater or surface water is polluted

magnetostratigraphic correlation of the oxfordian kimmeridgian boundary a magnetic polarity pattern for boreal and sub boreal ammonite zones of the upper oxfordian to lower kimmeridgian was established and confirmed in four british sections including the proposed global boundary stratotype section and point gssp on the isle of skye scotland to define the base of the international kimmeridgian stage a coeval pattern for sub mediterranean ammonite zones was compiled from seven sections in poland one german section and multi section composites from france and spain the mean paleopole for the european craton excluding spain at the oxfordian kimmeridgian boundary is 74 2 n 181 3 e 95 3 8 the common magnetic polarity scale enables inter correlation of ammonite subzones among these three faunal provinces and to the marine magnetic anomaly m sequence the proposed gssp at the base of the pictonia baylei zone is near the base of an extended interval dominated by reversed polarity which is interpreted to be chron m26r this gssp level projects to the lower to middle part of the epipeltoceras bimammatum subzone which is the middle subzone of this e bimammatum zone in the sub mediterranean standard zonation in contrast the traditional placement of the oxfordian kimmeridgian boundary in that sub mediterranean standard zonation base of sutneria platynota zone is at the base of chron m25r or nearly 1 million years younger