miocene rotations in the eastern alps palaeomagnetic results from intramontane basin sediments a palaeomagnetic study of late early miocene to late middle miocene sediments from the eastern alpine intramontane basins revealed counterclockwise rotations in the ennstal in the western part of the noric and in the lavanttal depressions for the basal strata of the basins declinations are between 273 and 315 while for the younger strata they are between 321 and 333 in perfect agreement with observations from the klagenfurt basin the results suggest synsedimentary rotation during the lateral tectonic extrusion of the eastern alps ca 17 13 ma which was also responsible for the formation of the mostly transtensional basins we propose a model in which domino shaped blocks separated by nnw sse trending dextral faults rotated counterclockwise due to faster eastward motion in the south relative to areas further north the protrusion of the bohemian spur inhibited eastward motion in the northern part of the study area thus creating a sinistral wrench corridor after lateral extrusion had ceased the counterclockwise rotation continued probably as en bloc rotation of ca 30 clockwise rotation was observed in the eastern part of the noric depression which appears to belong to a limited area with complex rotation pattern near the eastern margin of the alps this area is wedged between the counterclockwise rotated eastern alps and the similarly rotated north pannonian area in hungary 2000 elsevier science b v all rights reserved

reappraisal of the palaeomagnetism of the miocene intramontane pag and drnis sinj basins external dinarides croatia abstract this paper presents palaeomagnetic results from the miocene offshore pag and the twin onshore drnis sinj basins earlier magnetostratigraphic results were published from both basins which documented that the lake sediments were good targets for palaeomagnetism from the pag basin we sampled the oldest and youngest segments of the 1200 m long crnika section and obtained statistically different palaeomagnetic directions from the two parts during a repeated visit to the section it was revealed that modern gravity driven creeping can account for this i e the results from the pag basin should be rejected from regional tectonic interpretation the overall mean palaeomagnetic direction for the drnis sinj basin has excellent statistical parameters its high quality is further supported by positive regional fold tilt and reversal tests based on seven geographically distributed localities the results suggests 13 20 ccw rotation with respect to africa and 21 27 with respect to stable europe during the last 15 million years as the external dinarides are the loci of a complicated network of miocene and even younger tectonic zones we cannot export the observed rotation for the whole unit but consider our results as one step in obtaining robust kinematic constraints for the post oligocene tectonic history of the external dinarides

assessing the risk of saltwater intrusion in coastal aquifers in coastal regions the quality of groundwater can be compromised due to saltwater intrusion swi caused by natural sea level rise slr and storm surge and anthropogenic pumping hazards the goal of this research was to develop and test an approach for assessing the risk of swi in coastal aquifers the gulf islands in british columbia bc was the case study area the vulnerability of the bedrock aquifers to swi was assessed spatially by mapping hazards in combination with the aquifer susceptibility climate change related hazards including slr and storm surge overwash were integrated into floodplain maps for each island using projected slr data for 2100 in combination with estimated storm surge levels based on data collected over a forty year period when combined with maps showing the density of pumping wells coastal zones that may be at higher risk of swi were identified for this particular coastal area of bc hazards due to pumping have the greatest influence on the vulnerability risk was evaluated spatially using an economic valuation of loss here replacement of a water supply the combination of chemical indicators of swi and risk assessment maps are potentially useful tools for identifying areas vulnerable to swi and these tools can be used to improve decision making related to monitoring and community development for coastal areas thereby increasing resilience

neotectonics of the somogy hills part ii evidence from seismic sections abstract the somogy hills are located in the pannonian basin south of lake balaton hungary above several important tectonic zones analysis of industrial seismic lines shows that the pre late miocene substratum is deformed by several thrust faults and a transpressive flower structure basement is composed of slices of various palaeo mesozoic rocks overlain by sometimes preserved paleogene thick early miocene deposits middle miocene partly overlying a post thrusting unconformity partly affected by the thrusts is also present late miocene thick basin fill forms onlapping strata above a gentle paleo topography and it is also folded into broad anticlines and synclines these folds are thought to be born of blind fault reactivation of older thrusts topography follows the reactivated fold pattern especially in the central western part of the study area the map pattern of basement structures shows an eastern area where ne sw striking thrusts folds and steep normal faults dominate and a western one where e w striking thrusts and folds dominate folds in late neogene are also parallel to these directions a ne sw striking linear normal fault and associated n s faults cut the highest reflectors the ne sw fault is probably a left lateral master fault acting during after late miocene gravity anomaly and pleistocene surface uplift maps show a very good correlation to the mapped structures all these observations suggest that the main early miocene shortening was renewed during the middle and late miocene and may still persist two types of deformational pattern may explain the structural and topographic features a nw se shortening creates right lateral slip along e w faults and overthrusts on ne sw striking ones another nne ssw shortening creates thrusting and uplift along e w striking faults and transtensive left lateral slip along ne sw striking ones traces of both deformation patterns can be found in quaternary exposures and they seem to be consistent with the present day stress orientations of the pannonian basin too the alternation of stress fields and multiple reactivation of the older fault sets is thought to be caused by the northwards translation and counter clockwise rotation of adria and the continental extrusion generated by this convergence

new insights into the cenozoic lateral extrusion of crustal blocks on the southeastern edge of tibetan plateau evidence from paleomagnetic results from paleogene sedimentary strata of the baoshan terrane in order to characterize the lateral extrusion of crustal material during the cenozoic we conducted a paleomagnetic study of the eocene oligocene zhushan formation and paleocene muguahe formation in the central part of the baoshan terrane bst on the southeastern edge of tibetan plateau a primary magnetic component and a remagentized component with the miocene acquisition age were isolated from the muguahe formation and zhushan formation respectively these data indicate that the bst did not commence clockwise rotation in the period of the paleocene and the oligocene and that the bst experienced 80 clockwise rotation relative to east asia since the miocene combining with the documented history of crustal boundary strike slip faults on the southeastern edge of the tibetan plateau shows that the bst and tengchong terrane tct firstly underwent latitudinal crustal shortening in the oligocene and the eastward extension was the main type of motion of the crustal material during this period which induced the initial strike slip movement of their boundary faults since the miocene the main form of crustal motion of bst tct and simao terrane was gradually transformed into clockwise rotation which possibly indicates that the fold and thrusting fault systems induced crustal shortening and thickening in the southeastern edge of the tibetan plateau have reached extremity and the southeastern part of the tibetan plateau have already been uplifted to the similar elevation with today s elevation in the miocene

directional spectral analysis and filtering of geophysical maps the detection of linear anomalies in map data is facilitated by studying the two dimensional power spectrum because the directivity of the energy in the map is preserved in the fourier transform the lineaments associated with individual peaks in the spectrum are then separated from the map data by directional filtering and studied independently of other map features gravity and magnetic maps from an active rift area in southwestern iceland are analyzed in this manner the agreement between the filtered maps is good and they fit the observed tectonic features quite well

miocene pliocene tectonic evolution of the slovenian periadriatic fault implications for alpine carpathian extrusion models the periadriatic line pal is a remarkable several hundred kilometer long fault system of the alpine orogen its dextral character was documented by several authors using diverse criteria but detailed kinematics and timing of movements had not been investigated along its whole length structural and paleomagnetic measurements mapping and stratigraphic and sedimentological studies have helped to unravel the miocene pliocene evolution of the slovenian segment of the pal brittle deformation was characterized by nw se to n s compression and perpendicular tension deformation has resulted in dextral strike slip faulting folding and tilting of beds the first transpressional event corresponds to the first phase of lateral extrusion of the east alpine western carpathian northern pannonian block in the early miocene 24 17 5 ma after a short period of transtension during the karpatian 17 5 16 5 ma dextral transpression reoccurred during the middle miocene to pliocene and lasted up to the quaternary middle miocene dextral slip can be connected to the second phase of extrusion the highly deformed rocks within the dextral shear zones show variable clockwise sometimes counterclockwise rotations the mechanism of rotation seems to be complex ranging from regional rotation to local folding due to pure or simple shear domino type rotation

lithostratigraphy and deep water setting of the upper nanaimo group upper cretaceous outer gulf islands of southwestern british columbia the upper cretaceous nanaimo group consists of extensive shaly units and lenticular bodies of sandstone and conglomerate deposited in neritic to bathyal marine paleoenvironments single sandstone and conglomerate lenses cannot be traced throughout the basin but instead tend to concentrate at particular stratigraphic levels defining crudely sheet like composite units of coarse grained rocks many of the lenticular coarse grained units rest in major channels as deep as about 550 m sand and gravel were generally transported to the west and northwest by sediment gravity flows through these channels into the basin centre recognition of widespread channeling is critical to the definition of formal lithostratigraphic units four formations and two informal members are defined here for the upper nanaimo group the top of the nanaimo group is probably truncated by a major unconformity with local relief of at least 2 km the effect of the unconformity can only be seen by mapping the orientation of offshore rid

geodynamic evolution of the northern dinarides and the southern part of the pannonian basin abstract most of the recent geodynamic interpretations of the pannonian basin focus on its relation to the formation of the carpathians and the alpine orogeny however also the dinarides were severely affected by neogene tectonics related to the formation of the pannonian basin especially in the northernmost dinarides neogene deformation played a very important role in the evolution of this mountain chain geological records clearly show evidence of two phases of plate convergence along the northern and eastern margins of the present day dinarides at the end of the jurassic the dinaridic parts of the tethys ophiolites were obducted onto the northeastern margins of the apulian microplate the second phase is documented in the central part of the northernmost dinarides it is genetically related to an ancient volcanic arc as indicated by late cretaceous palaeogene trench sediments with blueschist olistolithes which are interlayered by basalt rhyolites pyroclastics medium pressure metamorphosed trench sediments and associated synkinematic granitoids in the northern part of the dinarides subduction processes terminated with the eocene compressional event which caused the uplift of the dinarides numerous intramontane basins with shallow marine fluviatile and lacustrine deposits were generated during the oligocene penecontemporaneous andesites which are found along the drava and sava depressions of the south pannonian neogene basin can be correlated with the easternmost periadriatic tonalites however observations do not indicate strike slip faulting at that time in this area the neogene rift stage initiated the evolution of the pannonian basin it is marked by extruded submarine trachyandesites of karpathian age badenian basalts andesites dacites and rhyolites and pannonian alkali basalts which are interlayered by coeval sedimentary rocks main evidence for the large scale tectonic transport of large dinaridic blocks into the pannonian basin area are the periadriatic sava and zagreb zemplen fault systems and subparallel faults the late sarmatian global sea level drop which coincided with a compressional phase is regionally marked by an unconformity throughout the pannonian basin as reported by horvath horvath f 1995 phases of compression during the evolution of the pannonian basin and its bearing on hydrocarbon exploration mar pet geol 12 8 837 844 due to thermal subsidence during the pliocene more than 2000 m of lacustrine freshwater sediments were deposited in the south pannonian basin the pliocene compression phase can be observed in the transdanubian zone and also south of the mura and drava rivers by south and southwest dipping reverse fault systems

magnetic fabric of late miocene clay rich sediments from the southern pannonian basin the magnetic fabric of late miocene sediments from the southern pannonian basin was studied on oriented samples collected from 19 geographically distributed localities all of them are characterized by near horizontal magnetic foliation plane after tilt correction indicating weak deformation well developed lineations were observed for 16 localities which are interpreted as due to compressional transpressional deformation except from three localities where the fabric must have been formed in an extensional setting comparison between the orientation of the map scale folds and faults and magnetic lineation directions shows that magnetic lineation is either related to nne ssw directed compression leading to the formation of folds or it can be connected to nw se or nne ssw trending dextral faults

neogene quaternary structures in the border zone between alps dinarides and pannonian basin hrvatsko zagorje and karlovac basins croatia analysis of neogene quaternary structures from seismic lines surface measurements and geological mapping is presented from the border zone between the alps dinarides and pannonian basin first early miocene extension was possibly characterised by ene directed extension it was partly synchronous with nw se shortening second middle miocene extension was possibly characterised by nw se to wnw ese directed extension again this event was followed by a new generation of thrusts related to end sarmatian shortening the last late miocene e w to wnw ese directed extension was followed by a final shortening that created major map scale folds basement pop ups and inverted former basins geometry onlap and thickness patterns of the youngest syn tectonic basin fill indicate that this last n s to nw se directed shortening started in late pontian and continued up to the present time when taking into account the wider surrounding area it seems that the structures related to this latest shortening are arranged in often perpendicular directions centred at the eastern end of the periadriatic lineament to explain this fan like pattern of synchronous shortenings a kinematic model is proposed combining counter clockwise rotation with north or northwestward shift of the dinaridic block with respect to the more stable alpine buttress

formation uplift and tectonic integration of a periadriatic intrusive complex pohorje slovenia as reflected in magnetic parameters and palaeomagnetic directions summary the periadriatic lineament is a 700 km long first order tectonic boundary in the alps along which several tertiary intrusions are located that were emplaced while tectonic processes were active the pohorje pluton is one of the periadriatic magmatic suites and comprises a pluton and a dacite stock that were emplaced at depths of about 10 and 2 km respectively oriented samples were collected from 33 sites in the magmatic and three in the surrounding metamorphic rocks and subjected them to standard palaeomagnetic and magnetic susceptibility anisotropy processing there is extreme variation in susceptibility although the magnetic mineral are always magnetite and in its anisotropy within the pluton lowest values are in the mafic members in the gabbro the oldest and in some lamprophyres the youngest member of the plutonic suite while the tonalite granodiorite exhibits extreme variation far exceeding those observed for other periadriatic plutons the abnormality of the pohorje pluton is attributed to the complex history that involves assimilation fractional crystallization stratification in the magma chamber incorporation of wall rocks variable degree of k metasomatism and hydrothermal alteration despite the above described heterogenities and sometimes very high degree of susceptibility anisotropy much higher that in the metamorphic samples in the acid member the palaeomagnetic directions observed for the pluton define three clear cut groups the directions show no dependence on the degree of magnetic susceptibility anisotropy in the order of crystallization they exhibit decreasing degree of clockwise declination deviation from north the dacite stock is characterized by counter clockwise rotated declinations as the pohorje pluton was uplifted very fast within the right lateral periadriatic shear zone system it is interpreted that the palaeomagnetic directions observed for the pluton are evidence for a clockwise rotation during exhumation the palaeomagnetic directions for the dacite which formed after the climax of the external forces fits the regional pattern of counter clockwise rotation observed in the neogene sediments around the pohorje pluton this shows that by the time of the dacite intrusion the pohorje pluton was already incorporated into the block that was driven by counter clockwise rotated adriatic microplate

seismic signature of the lake mien impact structure southern sweden the eugeno s seismic profile iv in southern sweden crossed lake mien a confirmed heavily eroded 121 ma impact structure the lake mien structure has a pre erosion rim diameter of about 9 km it is

geochemical evolution of groundwater on saturna island british columbia a detailed geochemical study of surface waters spring waters and groundwaters was undertaken to examine the geochemical evolution of groundwater on saturna island british columbia the purpose of the study was to characterize the nature and occurrence of saline waters and to provide insight on chemical processes that lead to salinization in the fractured sedimentary bedrock aquifers of this small island major ion chemistry shows that groundwater is recharged locally but mixes with saline waters that occur at depth or near the coast simple mixing is complicated by cation exchange between calcium rich waters and sodium rich exchange sites offered by mudstone beds and results in a spatially variable hydrochemical composition that is dependent on the island topography and geological framework structural sedimentological and glacial in combination with groundwater use patterns sodium present at exchange sites is speculated to be a remnant of ocean water intrusion during the pleistocene when the

linear and planar structure in ordered multivariate data as applied to progressive demagnetization of palaeomagnetic remanence summary consider a sequence of say 10 to 20 vector observations in threedimensional space it is suspected that a few subsets of consecutive observations are made up of collinear points the purpose of this paper is to construct a statistically based algorithm to find such linear segments and to assess their accuracy a similar assessment is made for coplanar sets of points this algorithm is applied here to palaeomagnetic data and is claimed to be superior to previous methods of palaeomagnetic analysis in terms of completeness and balance of analysis treatment of measurement errors and other sources of scatter criteria for identification of linear and planar sets of points and statistical rigour stability spectra with statistically based confidence limits are obtained as a by product 1 palaeomagnetic analysis background to the geometrical problem the natural remanent magnetization nrm in rocks is known in general to have originated in one or more relatively short time intervals during their formation and subsequent history i e during rock forming or metamorphic events during which nrm is frozen in stabilized by falling temperature grain growth etc the nrm acquired during each such event is a single vector magnetization parallel to the then prevailing geomagnetic field and is called a component of nrm rocks which have suffered more than one event of this kind are therefore liable to carry multi component nrm in the laboratory these components can be identified by demagnetizing the rock step by step usually by thermal alternating field or chemical demagnetization which involves the analysis of the distribution of blocking rzmperature coercivity and chemical leaching respectively resistance to these treatments is called stability of remanence and the range of treatment over which a particular component is removed is called the stability range of the component the various discrete

landscape response to recent tectonic deformation in the sw pannonian basin evidence from dem based morphometric analysis of the bilogora mt area ne croatia abstract bilogora mt area is a transpressional structure located in the ne of croatia linked with the tectonic evolution of the drava depression the structure formed during pliocene and quaternary from the inversion of nw striking drava depression boundary fault which originated as a normal fault and was reactivated as a dextral strike slip fault during pliocene and quaternary time bilogora mt area underwent more than 400 m of differential uplift while still ongoing tectonic deformation is documented by historical and instrumental seismicity 3 5 m l 5 6 in this geomorphic study the recent deformation in the bilogora mt area although obscured by landscape evolution variables was assessed using dem based landscape morphometry and a set of morphometric indexes local relief and slope angle variability distributions were combined with morphometric indexes computed at the scale of the drainage basin we analyzed hypsometric curves with the hypsometric integral hi basin asymmetry af and parameters of longitudinal stream profiles c f c max l l and k sn analyzed morphometric parameters were combined into a cumulative index of relative tectonic activity rta this index summarizes drainage basin response to the possible recent tectonic activity results suggest that most of the tectonic activity is probably located along the ne front of the bilogora mt area in its nw and central part this activity could be likely related to recent tectonic activity along the kalnik mt fault zone and drava depression boundary fault zones respectively a subordinate area characterized by recent tectonic activity could be suggested within the southernmost part of the study area quaternary activity in this area is probably related to ne striking faults in vicinity of the town daruvar that continue towards the northeast into the study area though methodology presented here represents a good identification tool of possible ongoing deformation this study will be followed by detailed fieldwork and paleoseismological investigations at the identified locations

mapping remanent magnetization using the local phase for uniformly magnetized 2 d contacts thin sheets horizontal cylinders and dykes the apparent inclination of the magnetization vector i e the inclination projected into a plane perpendicular to the strike of a 2 d anomaly can be computed from the difference in the anomaly shapes of the total field and the vertical field the calculation can be performed using gridded data resulting in a grid containing estimates of apparent inclination these estimates take into account varying source strike direction this quantity is important for computing source dip wherever the data are likely to be affected by the presence of remanent magnetization as well it is useful for input to forward models computed along profiles perpendicular to strike further without knowledge of source dip the apparent inclination can be used to map the presence of remanent magnetization this is an aid to geologic mapping allowing isolated paleomagnetic measurements to be extrapolated over a broad area knowing the extent o

sedimentology and stratigraphy of the neogene rift type north croatian basin pannonian basin system croatia a review abstract development of the rift type north croatian basin located in the south western neogene pannonian basin system and belonging to the central paratethys realm was controlled by tectonics climate volcanic activity and eustatic fluctuations the extrabasinal controls produced a succession of depositional environments from terrestrial to marine and back to terrestrial and the deposits form a large scale transgressive regressive cycle basin evolution is subdivided into the syn rift phase which lasted from the early miocene ottnangian until the middle miocene middle badenian and in the post rift phase from the middle miocene late badenian to the quaternary these complex controls on deposition generated the opening and closing of connections to the open sea that occasionally resulted in the formation of unfossiliferous continental deposits or generated the radiation of endemic species such that it has been necessary to use regional neogene stages for stratigraphic analysis of the central paratethys history earlier stratigraphic studies of the north croatian basin that had been primarily based on biostratigraphy and superposition were improved by recent results yielded from radiometric dating and integrated biostratigraphy they have been focused mainly on the early middle miocene and the miocene pliocene boundaries that separate intervals of the specific depositional evolution of the basin most important depositional and palaeogeographic differences concern a relatively long period of development of the early continental phase that lasted from the ottnangian to the early badenian in contrast to parts of the pannonian basin system characterized by marine deposition in the early badenian the ncb was characterized by long lived fresh water lacustrine deposition the fresh water lake slavonia that developed from the middle pliocene to the early pleistocene indicates an independent phase of evolution of the south pannonian basin system so the cernikian regional stage was introduced for the lacustrine succession those stratigraphic and palaeogeographic differences additionally support the complexity of the pannonian basin system within the central paratethys realm supporting heterogeneous depositional development of continental rift type basins

complex structural pattern of the alpine dinaridic pannonian triple junction due to the political boundaries between the central european countries on one hand and the thick tertiary cover in the pannonian basin on the other the eastward continuation of the alpine and dinaridic units has been ambiguous and poorly documented based on comparative analyses the aim of the present paper is to define the pre tertiary structural units in the junction area of the alpine dinaridic and pannonian regions in the sw part of the pannonian basin and to draw conclusions on the continuation of the alpine and dinaridic units according to diagnostic characteristics of the periadriatic lineament system the balaton lineament system may be considered as its direct eastern continuation north of the periadriatic balaton lineament system the transdanubian range unit due to its pre tertiary paleogeographic setting shows mainly south alpine facies relations however its present structural position is identical to that of the upper austroalpine nappes between the periadriatic balaton and zagreb zemplin lineament systems heterogeneous structural units are juxtaposed forming the sava composite unit in the northern part of this composite unit non metamorphosed nappes occur which can be considered the eastern continuation of the south alpine units these nappes are overthrust onto internal dinaridic units in the tertiary the zagreb zemplin mid hungarian lineament separates the sava unit from the tisza unit showing close affinity to the tethyan margin of the eurasian plate during the early stage of the alpine evolution

lateral extrusion in the eastern alps revisited refining the model by thermochronological sedimentary and seismic data 1 this study comprises a reassessment of the classical model of lateral extrusion in the eastern alps by using recently published geochronological data sedimentary ages from intramontane basins ages and distribution of magmatic rocks and information from seismic profiles extrusion related faulting continuously propagated from the western toward the central eastern part of the eastern alps during oligocene to middle miocene times this is confined by oblique convergence between the adriatic and european plates during middle miocene times extrusion became not only lateral in terms of parallel to the trend of the eastern alps but was characterized by a displacement vector at a high angle to the strike of the orogen this resulted in the exhumation of the schladming and pohorje blocks that were exhumed within extensional bridges at the northern and southern terminations of the pols lavanttal fault system respectively from middle miocene to recent times extrusion was controlled by overall extension between the dinaric and carpathian subduction zones the influence of north directed compression triggered by the northward moving adriatic plate diminished and the influence of the retreating carpathian subduction zone increased this gave rise to miocene volcanism that is exclusively found east of the dinaric subduction zone we therefore consider that lateral extrusion in the eastern alps can be subdivided into distinct tectonic phases with less pronounced eastward extension related displacement between late oligocene and middle miocene times as soon as the eastern alps passed the dinaric subduction zone the entire domain became highly extensive

a stable chemical remanence in holocene sediments the ferrimagnetic iron sulphide greigite has been extracted from freshwater sediments from loch lomond and llyn geirionydd and identified by x ray diffraction and thermomagnetic analyses the authigenic greigite is probably the dominant carrier of a stable natural remanent magnetization in the freshwater sediments underlying marine sediments in loch lomond and in the lateglacial interstadial sediments from llyn geirionydd mineral magnetic analysis shows that greigite tends to have a higher sirm x ratio approximately 70 kam 1 than many natural magnetite assemblages this magnetic characteristic coupled with greigite s ability to oxidize easily and to change to a less magnetic mineral upon exposure to air may be used to indicate its presence in downcore magnetic profiles alternating field demagnetization cannot be used to distinguish chemical from detrital remanences in loch lomond or llyn geirionydd on account of the similar magnetic stabilities of greigite and magnetite the time lag between the acquisition of the primary detrital remanence and the secondary chemical remanence remains unknown and creates difficulties in understanding the record of paleomagnetic secular variation contained in these lake sediments

tertiary evolution of the intra carpathian area a model abstract the outer carpathian flysch nappes encircle an intra carpathian domain which can be divided into two megatectonic units north pannonian and tisza mostly on the basis of contrasting mesozoic and palaeogene facies development we see two major kinematic problems to be solved 1 1 the present distribution of the mesozoic and palaeogene facies is mosaic like and some belts form exotic bodies within realms of austroalpine affinity 2 2 late eocene palinspastic reconstruction of the outer carpathian flysch nappes suggest that the entire intra carpathian area must have been located several hundreds of kilometres to the south and to the west of its present position neogene extension can account for shortening in the external carpathian nappes but is unable to explain mesozoic facies anomalies and offsets of palaeogene formations we suggest that evolution of the intra carpathian area involved first late palaeogene early miocene juxtaposition of the north pannonian and tisza megatectonic units accompanied by the closure of the external carpathian flysch troughs thereafter extension of this amalgamated unit occurred which was compensated by thrusting of flysch nappes onto the european foreland and formation of molasse foredeeps eastward escape of the north pannonian unit from the alpine collisional belt involved left lateral shear along the pieniny klippen belt and right lateral shear along the mid hungarian zone parts of the late palaeogene basin and an early miocene volcanic edifice were dissected offset and elongated by several 100 kms the driving mechanism of the eastward escape of the intra carpathian area can be related to the collision of apulia and europe and the subduction of the external carpathian crust under the pannonian units the escape ceased gradually in the early miocene when oblique collision between the north pannonian unit and european continent occurred neogene extension of the pannonian region was an areal deformation the extension at locally variable rate resulted in the break up of the heterogenous floor of the neogene basin the driving mechanism of basin extension and contemporaneous compressional deformation of the external carpathians is thought to be related to ongoing subduction involving the marginal part of the attenuated european continental crust tectonic activity in the carpathians and basin subsidence and volcanism shifted in time and in unison from the west toward the east southeast

the tectonic evolution of a critical segment of the dinarides alps connection kinematic and geochronological inferences from the medvednica mountains ne croatia the transition zone between the alps and dinarides is a key area to investigate kinematic interactions of neighboring orogens with different subduction polarities a study combining field kinematic and sedimentary data microstructural observations thermochronological data rb sr and fission track and regional structures in the area of medvednica mountains has revealed a complex polyphase tectonic evolution we document two novel stages of extensional exhumation the first stage of extension took place along a late cretaceous detachment following the late early cretaceous nappe stacking burial and greenschist facies metamorphism two other shortening events that occurred during the latest cretaceous oligocene were followed by a second event of extensional exhumation characterized by asymmetric top ne extension during the miocene top nw thrusting took place subsequently during the pliocene inversion of the pannonian basin the cretaceous nappe burial late cretaceous extension and the oligocene earliest miocene contraction are events driven by the alps evolution in contrast the latest cretaceous eocene deformation reflects phases of dinaridic contraction furthermore the miocene extension and subsequent inversion display kinematics similar with observations elsewhere in the dinarides and eastern alps all these processes demonstrate that the medvednica mountains were affected by alpine phases of deformations to a much higher degree than previously thought similarly with what has been observed in other areas of contractional polarity changes such as the mediterranean black sea or new guinea systems the respective tectonic events are triggered by rheological weak zones which are critical for localizing the deformation created by both orogens

tertiary paleomagnetic results and structural analysis from the transdanubian range hungary rotational disintegration of the alcapa unit abstract we carried out an integrated paleomagnetic and structural study in the transdanubian range western and central hungary as a result the tertiary tectonic history of this area can be characterized by three events of counterclockwise ccw rotation and four or five phases of brittle deformation the change of the orientation of stress axes between phases is mainly apparent and reflects the rotation of the faults predating a particular rotation event the first two rotation events r1 and r2 were probably governed by the rollback mechanism of the subducting european plate we suggest that these rotations were taking place from 18 17 and 16 14 5 ma respectively i e simultaneously with the rotations of the north hungarian paleogene basin and the main part of the western carpathians however the angle of both rotations was less in the transdanubian range due to increasing distance from the subduction front the differential rotation was accommodated by extensional faulting by formation of a graben system on the other hand the youngest rotation event r3 seems to be connected to the renewed rotation of the adriatic plate around 5 ma our combined data set strongly supports earlier conclusions namely that the different subunits of the eastern alpine western carpathian northern pannonian unit alcapa did not form a rigid unit although they moved in similar manner

tectonic activity in the croatian part of the pannonian basin abstract three main stages in structural development of the sw pannonian basin are differentiated the onset of extensional tectonics between the oligocene and the early miocene main extensional processes in the early and middle miocene and prevailing transpression in the pliocene and quaternary the neotectonic phase is given special attention in this paper structural fabrics allow to subdivide the area into three large structural zones corresponding to the western southern and central marginal part of the pannonian basin in croatia these zones are bounded by important faults the periadriatic drava fault the medvednica fault zone and the southern marginal fault of the pannonian basin the recent displacements within the dinarides and the eastern alps form the boundary conditions for active transpressional deformation in the western marginal part of the pannonian basin dextral transcurrent displacement is evident in the zone of the periadriatic drava wrench fault the formation of the new types of structures is observed especially in zones of compression along the faults narrowing of the area between the sava and drava rivers causes structural changes in the marginal parts of the corresponding basins i e in the areas close to the slavonian mts recent tectonic activity is marked by the occurrence of earthquakes which are most common in the northwestern part of croatia the spatial distribution of hypocentres and of seismotectonically active zones is used to reconstruct probable displacements and the structural style of deformation in depth the earthquake sources in the vicinity of the medvednica fault and the periadriatic drava fault are given special attention

mesozoic plate tectonic reconstruction of the carpathian region abstract palaeomagnetic palaeobiogeographic and structural comparisons of different parts of the alpine carpathian region suggest that four terranes comprise this area the alcapa tisza dacia and adria terranes these terranes are composed of different mesozoic continental and oceanic fragments that were each assembled during a complex late jurassic cretaceous palaeogene history palaeomagnetic and tectonic data suggest that the carpathians are built up by two major oroclinal bends the alcapa bend has the meliata oceanic unit correlated with the dinaric vardar ophiolite in its core it is composed of the western carpathians eastern alps and southern alcapa units transdanubian range bukk this terrane finds its continuation in the high karst margin of the dinarides further elements of the alcapa terrane are thought to be derived from collided microcontinents czorsztyn in the n and a carbonate unit tisza in the se the tisza dacia bend has the vardar oceanic unit in its core it is composed of the bihor and getic microcontinents this terrane finds its continuation in the serbo macedonian massif of the balkans the bihor getic microcontinent originally laid east of the western carpathians and filled the present carpathian embayment in the late palaeozoic early mesozoic the vardar ocean occupied an intermediate position between the western carpathian austroalpine transdanubian high karst margin and the bihor getic serbo macedonian microcontinent the vardar and pindos oceans were opened in the heart of the mediterranean adriatic microcontinent in the late permian middle triassic vardar subducted by the end of jurassic causing the bihor getic serbo macedonian microcontinent to collide with the internal dinaric western carpathian margin an external penninic vahic ocean tract began opening in the early jurassic separating the austroalpine western carpathian microcontinent and its fauna from the european shelf further east the severin ceahlau magura also began opening in the early jurassic but final separation of the bihor getic ribbon and its fauna from the european shelf did not take place until the late middle jurassic the alcapa and the tisza dacia were bending during the albian maastrichtian the two oroclinal bends were finally opposed and pushed into the gates of the carpathian embayment during the palaeogene and neogene at that time the main n s shortening in distant alpine and hellenic sectors was linked by a broader right lateral shear zone along the former vardar suture

revised and synthetic apparent polar wander paths of the african eurasian north american and indian plates and true polar wander since 200 ma we have reviewed paleomagnetic data available for the eurasian african north american and indian plates over the last 200 ma selection criteria are those generally accepted with an emphasis on evidence for lack of remagnetization accurate dating and proper structural analysis this results in 23 35 51 and 2 poles for eurasia africa north america and india respectively we believe that this limited set of higher quality data is more likely to reveal key features of apparent polar wander apw paths than averaging of larger data sets involving less stringent selection criteria we propose and describe revised apw paths but more importantly we next use relative motion models to transfer all data in a common reference frame we find good agreement between transferred data when they are averaged separately for each plate in independent 20 ma windows this is a check on consistency of paleomagnetic data kinematic models and of the geocentric dipole hypothesis transferred data from all plates are averaged in 20 ma windows to generate synthetic apw paths for all plates studied these synthetic paths are in agreement with the original revised apw paths that use only data from a single plate moreover both geographic and time resolution are improved spatial confidence intervals are of the order of 5 the synthetic paths display interesting features such as a previously ill recognized apw loop for eurasia paleomagnetic and hotspot apw are next compared and a determination of true polar wander tpw is derived we find significant tpw amounting to over 20 in the last 200 ma tpw appears to be episodic with a standstill between 180 and 110 ma there is general agreement with a previous study of livermore et al 1984 the tpw standstill appears to correlate with a time of decreasing reversal frequency ending with the cretaceous long normal superchron other periods of fast tpw would seem to correspond to increasing reversal frequency however it is suggested that the major tpw hairpin at 50 ma might correspond to the collision of india with eurasia tentative correlations with core or mantle indicators can be understood as a result of couplings between the core mantle and lithosphere we believe primarily related to episodic evolution of the d layer

origin of dissolved solids in groundwaters of mayne island british columbia canada abstract hydrogeological hydrochemical and isotope techniques were applied to determine the origin of saline groundwaters on mayne island in the strait of georgia british columbia the saline groundwater is a sodium chloride type with concentrations of na and cl as high as 4367 and 8008 mgl 1 respectively leach tests on twenty rock samples from boreholes indicate that the shale strata in the cretaceous bedrock have cl concentrations ranging up to 900 ppm by weight and na concentrations up to 2070 ppm the salt probably originated in the shale during periods of post depositional compaction or during periods of immersion in ocean water during episodes of glacial loading and erosion during pleistocene time the present flow regime of active flushing of meteoric water through the surficial sediments and sedimentary bedrock of mayne island began as the island emerged from below sea level during the last deglaciation the salt content of the present day groundwater can be accounted for by the slow release through molecular diffusion of na and cl from the low permeability matrix of the shale to the active paths of groundwater flow in fractures in the shale and in sandstone strata intrusion of ocean water under the present hydrologic regime on the island and upward flow of brine from deep zones within the regional sedimentary basin are believed to be relatively unimportant contributors of salt to the active groundwater flow systems 18 o deuterium and tritium concentrations are rather uniform for both surface waters and groundwaters on mayne island and a meteoric origin is suggested saline spring waters on an adjacent island were found to have high 18 o and d concentrations 18 o 6 5 o 24 suggesting a sedimentary basin brine but there is no evidence that these brines are mixing with mayne island groundwater

phases of compression during the evolution of the pannonian basin and its bearing on hydrocarbon exploration abstract progress in understanding the structural evolution of the pannonian basin is reported this has been driven by the application of seismic stratigraphy constrained by magnetostratigraphic data and the recent release of a great amount of hydrocarbon exploration data this has led to a redefinition and better understanding of the syn rift period and style of rifting in addition a complex structural evolution history during the post rift phase has been recognized two compressive events are defined one in the early stage and another in the late stage of evolution the importance of these findings for hydrocarbon exploration includes an improved knowledge of the timing of trap formations and a possible explanation for remarkably variable reservoir pressures in pools of the great hungarian plain

early miocene european loess a new record of aridity in southern europe the intercalation of silty units and coarse grained units represented by conglomerates and breccia characterizes a lower miocene terrestrial sedimentary sequence in the north croatian basin a part of the southwestern pannonian basin system these sediments were previously interpreted as alluvial sediments where the silty units would reflect deposition on a floodplain however in this study we show new results that support a different interpretation of the genesis of the silty units the units which vary in thickness between 6 and 180 cm are mostly composed of structureless loose silt they are brownish yellow to yellowish brown in color and do not contain fossils scanning electron microscopy indicated that quartz grains show fracture faces conchoidal fractures v shaped percussion marks linear steps and conchoidal crushing features such microtextures together with the macroscopic characteristics of the silt units indicate that they were deposited by wind therefore this study reports the first occurrence of miocene loess outside of china silt sized particles were probably produced by salt weathering processes on salina type lake flats during long arid periods alluvial deposition was controlled by a more humid climate so the intercalation of eolian silty units with alluvial conglomerates and breccias reflects alternation of arid and more humid periods in the early miocene this agrees with regional paleoclimate studies that show cyclicity in the climate with a dry cycle and orbital scale climate variability controlling paleoenvironmental and sedimentary changes in the area during the early miocene

palaeomagnetic evidence for tertiary counterclockwise rotation of adria abstract with the aim of obtaining tertiary palaeomagnetic directions for the adriatic foreland of the dinaric nappe system we carried out a palaeomagnetic study on platform carbonates from stable istria from the northwestern and the central dalmatia segment of imbricated adria despite the weak to very weak natural remanences of these rocks we obtained tectonically useful palaeomagnetic directions for 25 sites from 20 localities all exhibit westerly declinations both before and after tilt correction concerning the age of the magnetizations we conclude that five subhorizontal and magnetite bearing eocene localities from stable istria are likely to carry primary remanence whereas three tilted and hematite bearing ones were remagnetized in the northwestern segment of imbricated adria the cluster of the mean directions improved after tectonic correction indicating pre tilting magnetization in contrast maastrichtian eocene platform carbonates from central dalmatian were remagnetized in connection with the late eocene oligocene deformation or miocene hydrocarbon migration based on the appropriate site locality means we calculate mean palaeomagnetic directions for the above three areas and suggest an alternative interpretation of the data of kissel et al j geophys res 100 1995 14999 for the flysch of central dalmatia the four area mean direction define a regional palaeomagnetic direction of dec 336 inc 52 k 107 95 9 from these data we conclude that stable istria in close coordination with imbricated adria must have rotated by 30 counterclockwise in the tertiary relative to africa and stable europe we suggest that the latest miocene early pliocene counterclockwise rotations observed in northwestern croatia and northeastern slovenia were driven by that of the adriatic foreland i e the rotation of the latter took place between 6 and 4 ma

in the wake of a counterclockwise rotating adriatic microplate neogene paleomagnetic results from northern croatia in northern croatia the neogene sediments cover complicated basement rocks which consist of alpine and dinaridic elements in the zagorje area and variscan alpine formations of the tisia tisza megatectonic unit in the slavonian mountains mts the neogene sediments were deposited in two separate basins before the karpatian but sedimentation became uniform from the karpatian onwards 17 5 ma of the 24 localities that we have studied so far paleomagnetically from northern croatia 16 localities are of karpatian or younger age while the rest are pre karpatian

construction of component maps from aeromagnetic total field anomaly maps1 total field anomalies as defined from normal aeromagnetic surveys give good approximations of the anomalous components along the direction of the main geomagnetic field which is generally much larger than the anomalous field using the relations between vertical and horizontal components of the field the total field anomaly is related to any vertical or horizontal component and the corresponding horizontal and vertical derivatives an example from the siljan impact structure indicates that such directional filters may be applied to extract useful information from magnetic maps

hydrochemical and isotopic characteristics of groundwater in the ndop plain northwest cameroon resilience to seasonal climatic changes shallow groundwater 30 mbgl is an essential source of drinking water to rural communities in the ndop plain northwest cameroon as a contribution to water management the effect of seasonal variation on the groundwater chemistry hydrochemical controls drinking quality and recharge were investigated during the peaks of the dry january and rainy september seasons field measurements of physical parameters were preceded by sampling 58 groundwater samples during both seasons for major ions and stable isotope analyses the groundwater which was barely acidic mean ph of 6 and less mineralised tds ca2 mg2 k and na mg2 ca2 k in the dry and rainy seasons respectively but that of anions text hco 3 text no 3 cl text so 4 2 f was similar in both seasons this suggests a negligible effect of seasonal variations on groundwater chemistry the groundwater which was camghco3 and nahco3 is chemically evolved rainfall camgso4cl in the area silicate mineral dissolution and cation exchange were the main controls on groundwater chemistry while there was little anthropogenic influence the major ions and tds concentrations classified the water as suitable for human consumption as per who guidelines the narrow cluster of 18o and d of same groundwater from both seasons between the 18o and d values of may june precipitation along the ndop meteoric water line indicates meteoric origin rapid recharge after precipitation and timing of recharge between may and june rainfall diffuse groundwater recharge mainly occurs at low altitudes 1 400 m asl within the plain besides major ions and tds the similar 18o and d of groundwater from both seasons indicate a consistent groundwater recharge and flow pattern throughout the year and resilience to present day short term seasonal climatic variations however controlled groundwater abstraction is recommended given the increasing demand

palaeomagnetism and rock magnetism of the permian redbeds from the velebit mt karst dinarides croatia dating of the early alpine tectonics in the western dinarides by a secondary magnetization abstract the studied area of the velebit mt a part of the adria microplate belonged to a ne margin of gondwana during the carboniferous and permian while the carboniferous to the early permian was characterised by deposition of clastic rocks younger sedimentation was dominated by a thick sequence of carbonate rocks the lower permian deposits of the core part of the velebit mt at kosna and crne grede localities were investigated using palaeomagnetic and rock magnetic measurements the main remanence carriers were recognized as haematite with an increasing contribution of sp sd magnetite in younger subsections the ams fabric with low anisotropy ratio 1 3 is strongly oblate at kosna and weakly prolate at crne grede reflecting differences in the contribution of magnetic phases a significant remagnetization of the permian rocks as proved by results of a conglomerate test probably caused by a combination of elevated temperatures and fluid migration may be assigned to burial related processes that affected the rocks before the final uplift of the dinarides characteristic remanent magnetizations recorded in haematite are apparently similar to the permian direction for africa shallow inclination with nnw declination as expected for velebit mt coordinates paradoxically this orientation is observed in situ within the almost vertically dipping beds we explain this relationship assuming a syn folding cretaceous remagnetization of the rocks at their subhorizontal position ca 30 s in which a mean vector of the secondary remanence overlaps with the cretaceous direction expected for africa at the velebit mt geographical coordinates consequently our results indirectly point to the cretaceous time of incipient stages of the dinaric tectonism and suggest african geotectonic affinity of the velebit rocks no important vertical axis rotation is implied by our results in contrast to previously published data the puzzling complete remagnetization carried by haematite at relatively low to moderate temperatures is also discussed

widespread occurrence of greigite in the sediments of lake pannon implications for environment and magnetostratigraphy abstract lake pannon was a large lake at the southern margin of the european plate which separated from the central paratethys at the sarmatian pannonian boundary and was filled completely with sediment during the pliocene the separation produced an endemic fauna that makes classical geological correlation problematic with sediments outside the lake magnetostratigraphic correlation could potentially solve the problem and several long cores from deep drillings have been analysed for polarity information in the course of these studies primary magnetite was assumed to carry the natural remanent magnetization nrm later when outcrops of dark grey clays and marls of lake pannon were sampled for palaeomagnetic investigations of tectonic processes greigite was discovered as the carrier of the nrm at several localities this motivated a systematic study of the fine grained sediments of lake pannon in order to identify the principal carriers of the nrm to relate them to depositional environments and to assess the importance of neoformation of magnetic minerals the concentration of magnetic minerals is low in the fine grained sediments of lake pannon this made extraction of the magnetic minerals impossible so they were identified with magnetic methods magnetic experiments suggest that greigite is the most common magnetic mineral in the lake pannon sediments magnetite when it occurs is often accompanied by pyrite haematite is rare the studied sediments represent three time intervals 11 9 3 ma 8 7 ma and 6 4 ma in the 11 9 3 ma sediments greigite occurs as an original early diagenetic magnetic mineral during this period the climate was warm and humid the lake was fairly deep and stratified high organic productivity resulted in oxygen depleted bottom waters burial was rapid due to intensive erosion from the surrounding carpathian and alpine mountains magnetite bearing sediments deposited during this period do not carry a coherent palaeomagnetic signal which suggests that the magnetite was neoformed the 8 7 ma sediments were deposited in sublittoral upper delta plain and swamp environments in humid conditions they are also greigite bearing during the third investigated time period 6 4 ma the climate was arid the lake was of low salinity and was restricted to the southern part of the pannonian basin these sediments were deposited in a distal environment low sedimentation rate the characteristic magnetic mineral of this period is magnetite which most probably has a detrital origin widespread greigite which is always of diagenetic origin suspected neoformation of magnetite in the older parts of lake pannon and occasionally opposite polarities connected to greigite and magnetite when they occur together in the present study are important for magnetostratigraphic interpretation they imply that detailed magnetic mineralogical investigations and documentation of the consistency of the nrms by working on fully oriented samples are essential in magnetostratigraphic studies of molasse sediments

paleomagnetic evidence for large en bloc rotations in the eastern alps during neogene orogeny abstract we present new paleomagnetic data from the northern calcareous alps and the central alps of austria all new data are overprint magnetizations and can be subdivided into two groups in rocks older than earliest rupelian two remagnetizations reflecting both clockwise and counter clockwise rotation were detected in rocks of late rupelian and younger ages only a counter clockwise rotated remagnetization was found our results together with results from previous paleomagnetic studies from the eastern and southern alps suggest two main phases of vertical axis rotation the first clockwise rotation affecting the northern calcareous alps was active between earliest to late rupelian we propose a model where the northern calcareous alps are segmented into individual blocks within a dextral shear corridor these blocks rotated clockwise due to the counter clockwise rotation of the southern alps and central alps the second counter clockwise rotation occurred in the late oligocene to middle miocene affecting eastern and southern alps in this stage of orogeny the internal massifs of the western alps were already accreted to the upper plate and therefore included in counter clockwise rotation this rotation is contemporaneous with counter clockwise rotation in the apennines and opening of the balearic basin and a genetic relationship is suggested a second step of counter clockwise rotation reconstructed from published data is observed in the sedimentary basins at the southeastern margin of the eastern alps where counter clockwise rotated miocene and pliocene sedimentary rocks are present this rotation is seen in connection to a young counter clockwise rotation of the adriatic plate

tectonic evolution of the northwestern internal dinarides as constrained by structures and rotation of medvednica mountains north croatia this paper attempts to explain the tectonic history and the possible reasons for the change of trend of the northwestern part of internal dinarides in a transitional area between the southern eastern alps central dinarides and tisia north of zagreb structural and palaeomagnetic data collected in pre neogene rocks at medvednica mts combined with palaeomagnetic data available form neogene rocks in the surrounding area point to the following conclusions 1 the reason for dramatic deflection in structural trend of the internal dinarides in the area north of zagreb is a 130o clockwise rotation and eastward escape of a tectonic block comprising medvednica mts and the surrounding inselbergs bounded to the north by the easternmost tip of the periadratic lineament in medvednica mts the main period of tectonic escape and associated clockwise rotation occurred in late palaeogene possibly in oligocene earliest miocene 2 when rotated into the original position the trend of observed pre neogene structures of medvednica mt becomes parallel to the major structural trend of the central dinarides in view of their original orientation these structures are interpreted in the following way a the first d1 deformational event is attributed to the aptian albian nappe stacking in the central northern dinarides that was accommodated by a top to the north directed shearing and northward propagation of already obducted ophiolites of the central dinaridic ophiolite zone this nappe stacking which resulted in a weak regional metamorphism in tectonic units underlying the ophiolites was orogen parallel or at a very acute angle to known structural and possibly palaeogeographic trends this implies a major left lateral shear component along the former adriatic margin and obducted dinaridic ophiolite zone b this was followed by early albian orogen perpendicular shortening d2 that was accommodated by folding and top to the west thrusting this deformation resulted in gradual cooling of the metamorphic stack and also in uplift and erosion of the higher structural units c d3 deformational event was driven by renewed e w shortening that took place after the paleocene most probably during the middle eocene oligocene i e synchronous with the main dinaridic tectonic phase of the external dinarides this shortening was probably triggered by collision and thrusting of tisia over the northern segment of the internal dinarides d this was finally followed by d4 pervasive right lateral n s shearing that is tentatively interpreted as being related to the right lateral shearing of the sava zone during the eocene oligocene e following the main period of tectonic escape and induced clockwise rotation in late palaeogene possibly in oligocene earliest miocene the medvednica mts and the surrounding area were affected by repeated extensions and inversions since the early miocene to recent times palaeomagnetic data suggest that in the early miocene but probably before the karpatian this area was part of a regional block that shifted northwards and rotated in counter clockwise sense a second episode of counter clockwise rotation occurred at the present latitude in post pontian times since ca 5 ma driven by the counter clockwise rotating adriatic plate

the gradient tensor of potential field anomalies some implications on data collection and data processing of maps the full gradient tensor is presently not measured routinely onboard airplanes or on land this paper describes some improvements that can be made in strategies of data collection and in processing of potential field maps if such tensor measurements were available we suggest that in addition to producing for example standard total field anomaly maps the invariants of the tensor be mapped strikes of magnetic or gravimetric structures may be determined from minimizing the power in the first row and column of the tensor invariants can be looked upon as nonlinear filters enhancing sources with big volumes their lateral resolution is superior to that of the field proper and for a given resolution the flight altitude and separation between flight lines can be increased compared with the standard mode of operation in airborne surveys the distance between flight lines is normally much larger than the height above the ground this may introduce severe aliasing effects in the direction perpendicular to the

identifying the influence of geology land use and anthropogenic activities on riverine sulfate on a watershed scale by combining hydrometric chemical and isotopic approaches abstract throughout the last few decades sulfate concentrations in streamwater have received considerable attention due to their dominant role in anthropogenic acidification of surface waters the objectives of this study conducted in the oldman river basin in alberta canada were to determine the influence of geology land use and anthropogenic activities on sources concentrations and fluxes of riverine sulfate on a watershed scale this was achieved by combining hydrological chemical and isotopic techniques surface water samples were collected from the main stem and tributaries of the oldman river on a monthly basis between december 2000 and march 2003 and analyzed for chemical and isotopic compositions at a given sampling site sulfate sources were primarily dependent on geology and did not vary with time or flow condition with increasing flow distance a gradual shift from 34 s values 10 and 18 o values 0 of riverine sulfate indicating evaporite dissolution and soil derived sulfate in the predominantly forested headwaters to negative 34 s and 18 o values suggested that sulfide oxidation was the predominant sulfate source in the agriculturally used downstream part of the watershed significant increases in sulfate concentrations and fluxes with downstream distance were observed and were attributed to anthropogenically enhanced sulfide oxidation due to the presence of an extensive irrigation drainage network with seasonally varying water levels sulfate s exports in an artificially drained subbasin 64 kg s ha yr were found to exceed those in a naturally drained subbasin 4 kg s ha yr by an order of magnitude our dataset suggests that the naturally occurring process of sulfide oxidation has been enhanced in the oldman river basin by the presence of an extensive network of drainage and irrigation canals

paleomagnetic and geochronologic constraints on the geodynamic evolution of the central dinarides the geodynamic evolution of the dinaride mountains of southeastern europe is relatively poorly understood especially in comparison with the neighboring alps and carpathians here we construct a new chronostratigraphy for the post orogenic intra montane basins of the central dinarides based on paleomagnetic and 40ar 39ar age data a first phase of basin formation occurred in the late oligocene a second phase of basin formation took place between 18 and 13 ma concurrent with profound extension in the neighboring pannonian basin our paleomagnetic results further indicate that the dinarides have not experienced any significant tectonic rotation since the late oligocene this implies that the dinarides were decoupled from the adjacent adria and the tisza dacia mega units that both underwent major rotation during the miocene the dinaride orogen must consequently have accommodated significant shortening this is corroborated by our ams data that indicate post middle miocene shortening in the frontal zone wrenching in the central part of the orogen and compression in the hinterland a review of paleomagnetic data from the adria plate which plays a major role in the evolution of the dinarides as well as the alps constrains rotation since the early cretaceous to 48 10 counterclockwise and indicates 20 of this rotation took place since the miocene it also shows that adria behaved as an independent plate from the late jurassic to the eocene from the eocene onwards coupling between adria and africa was stronger than between adria and europe adria continued to behave as an independent plate the amount of rotation within the adria dinarides collision zone increases with age and proximity of the sampled sediments to undeformed adria these results significantly improve our insight in the post orogenic evolution of the dinarides and resolve an apparent controversy between structural geological and paleomagnetic rotation estimates for the dinarides as well as adria

the quaternary stratigraphic record of british columbia evidence for episodic sedimentation and erosion controlled by glaciation the terrestrial quaternary stratigraphic record of british columbia is largely a product of brief depositional events separated by long periods of nondeposition and erosion thick stratified quaternary sediments are present mainly in valleys and coastal lowlands and accumulated during periods of growth and decay of the cordilleran ice sheet at glacial maxima till was deposited over large areas of low and moderate relief however at the same time much of the landscape was eroded by glaciers sedimentation has been more restricted and has occurred at lower rates during nonglacial periods than during glaciations on land the only important sediment accumulation sites during nonglacials have been lakes floodplains and fans however large amounts of sediment have accumulated offshore especially in fjords and basins such as the strait of georgia because of the restricted aspect of sedimentation during nonglacials the stratigraphic record of these periods is meagre in most places true nonglacial uni