correlations of earthquake focal mechanisms summary we performed a statistical analysis of the harvard catalogue of seismic moment tensor solutions we investigated the distribution of hypocentres on focal spheres of earthquakes the hypocentres are concentrated along fault planes the hypocentre distribution does not significantly differ for earthquakes in different depth ranges to study the rotation of focal mechanisms we have solved an inverse problem of a 3 d rotation of double couple earthquake sources i e for each pair of focal mechanisms we find all four 3 d rotations which rotate one mechanism into another the stochastic disorientation of focal mechanisms is well approximated by the rotational cauchy distribution which has previously been identified through theoretical arguments and simulations as the result of stress perturbations caused by random defects in the medium the cauchy distribution is characterized by one parameter k k 0 means no rotations and k 0 5 corresponds to approximately random rotation for earthquake focal mechanisms the value of k is between 0 05 and 0 1 in a fault zone and it increases with distance between pairs of events in directions other than a fault plane k reaches the value 0 5 the cauchy distribution is then close to completely random rotations although k increases slowly with depth in general disorientations of focal mechanisms in various depth ranges display the same dependence therefore we can conclude that deep earthquakes are controlled by the same stress interaction regime as shallow events the results of these measurements made us question the suitability of some terms and models that are commonly used in the theory of an earthquake source for example we argued that tectonic earthquakes rupture rock material which has large scale defects or faults comparable in size with tectonic blocks in which they originate properties of the rocks should be significantly different from those of regular materials where the size of defects is typically much smaller than the scale of interest these properties should strongly depend on the geometry location and orientation of major defects

stress strain paradox plate coupling and forearc seismicity at the cascadia and nankai subduction zones abstract in the continental forearcs of the cascadia and nankai subduction zones geodetic strain measurements indicate crustal contraction in the direction of plate convergence nearly margin normal but earthquake focal mechanisms and other stress indicators show maximum compression along strike margin parallel it is evident that the geodetic strain signals reflect the temporal fluctuations of elastic stress associated with subduction earthquake cycles not the absolute stresses the absolute margin normal stress is not only much less than the margin parallel stress but also no greater than the lithostatic value indicating a very weak subduction thrust fault weak subduction faults are also consistent with geothermal data which require very low frictional heating along the faults great subduction earthquakes occur at very low shear stresses and cause small perturbations to the forearc stress regime because these small elastic stress perturbations are relatively fast they give large strain rates that are detected by geodetic measurements the present nearly margin normal contraction in both places is due to the locking of the subduction fault and the consequent increase in elastic stress in the direction of plate convergence with the margin parallel compression being dominant the small increase in margin normal stress may change the forearc seismicity in cascadia from a mixture of thrust and strike slip types into mainly thrust before the next great subduction earthquake in nankai the change should be from strike slip to quiescence as observed in the nankai forearc prior to the 1944 1946 great subduction earthquakes

mechanics of low stress forearcs nankai and cascadia the nankai and cascadia subduction zones have low stress forearcs where the margin normal horizontal compressive stress is similar to or less than the vertical stress except in the accretionary prisms in the absence of active back arc spreading the forearc margin normal stress is controlled mainly by the total shear force along the subduction fault or the plate coupling force and the gravitational force the plate coupling force creates compression and the gravitational force in the presence of margin topography creates lateral tension we give a simple expression that relates the forearc stress to topography and average fault strength with the latter represented by an effective coefficient of friction we also use a finite element model of two converging plates in frictional contact to model the forearc stresses the analyses indicate that a low stress forearc requires not only the subduction fault to be very weak but also the mechanically coupled fault area to be narrow in the downdip direction and shallow in depth for nankai and cascadia where the coupled fault areas are narrow and shallow because of the young and hot subducting plates is about 0 05 or less and in any case less than 0 09 the low fault strength is probably not a unique property of low stress forearcs since the same low values combined with wider and deeper coupled areas can be shown to create large margin normal compression in addition there does not seem to be any relation between subduction earthquake magnitudes and plate coupling forces great earthquakes occur at subduction zones having low stress forearcs such as nankai and cascadia

integrated computer aided basin modeling applied to analysis of hydrocarbon generation history in a northern italian oil field abstract the application of reaction kinetics to the analysis of hydrocarbon hc generation processes requires a detailed temperature history of potential source rocks in order to obtain optimum results the necessary accuracy can be obtained by employing integrated computer aided basin modeling techniques to simulate the depositional history resulting in a continuous record of temperatures throughout the study area the technique has been applied to the analysis of an on off structure hc generation problem in a northern italian oil field the simulation of the geologic processes shows that low sedimentation rates and more importantly the high thermal conductivities of the carbonate rocks resulted in low temperatures throughout most of the geologic history of the study area which were followed by a sudden rapid temperature increase in the off structure area during the last 6 5 ma the calculated temperature history enables an accurate determination of the hc generation history using a kinetic approach which shows how hc generation is closely controlled by the sedimentation history and structural development and which also describes its relation to trap formation it also shows why hcs are generated at very low vitrinite reflectance levels i e peak oil generation at approximately 0 6 r o determination of the hc generation rate gives additional critical information as even source rocks located in apparently good potential zones at present i e in the on structure area can be of minor importance for a trap due to slow generation rates and consequent low expulsion efficiencies

late cretaceous exhumation history of an extensional extruding wedge graz paleozoic nappe complex austria late cretaceous structures within the eastern graz paleozoic nappe complex define an extruding wedge with north eastward directed thrusting in eastern portions and strike slip shear along the margins stacking structures are overprinted by south westward directed extension with low grade metamorphic rocks in the hangingwall and high grade basement rocks in the footwall pressure temperature and structural data are obtained from successively opening quartz veins that record various stages of progressive deformation and metamorphism fluid inclusion data and related structures show that during extension isothermal decompression from ca 550 c and 8 kbar down to ca 450 c and 2 kbar was related to exhumation of rocks from deep crustal levels the data point to a high geothermal gradient and explain condensed paleo isotherms due to ductile normal faulting in the eastern areas of the graz paleozoic nappe complex the investigated late cretaceous structural elements suggest that the graz paleozoic nappe complex decoupled from the surrounding basement units and operated as a large scale extension extrusion corridor that evolved prior to miocene extrusion tectonics in the eastern alps

organic metamorphism as a key for reconstructing tectonic processes a case study from the austroalpine unit eastern alps at the northwestern margin of the gurktal alps eastern alps eoalpine cretaceous thrusting of carbonaceous material cm bearing metasediments formed a very low to low grade metamorphic nappe stack above higher grade metamorphic basement nappes sedimentary burial as well as progressive metamorphism transformed the enclosed cm to anthracite metaanthracite and semigraphite in a kinematically well constrained section at the northwestern frontal margin of the nappe stack this transformation has been investigated by vitrinite reflectance measurements and raman spectroscopy of carbonaceous materials rscm automated interactive fitting of raman spectra estimates the metamorphic peak temperatures in a complete section through the upper part of the upper austroalpine unit a rscm trend indicates a temperature profile of ca 250 600 c the top part of the gradient is reconstructed by one dimensional thermal modeling the certainty of ca 25 c at a confidence level of 0 9 resembles the data variability within a sample location due to the large calibration range the method is able to reconstruct a thermal crustal profile in space and time the study highlights the versatility of rscm which characterizes almost 250 ma of a complex and polyphase tectonic history rscm data characterize the variscan metamorphic grade in nappes now imbricated in the eoalpine nappe stack they additionally constrain a numerical model which emphasizes the significance of an increased thermal gradient in a continental margin towards the western neotethyan ocean during permo triassic lithospheric extension it finally characterizes the eoalpine metamorphic gradient during nappe stacking and a significant metamorphic jump related to exhumation and normal faulting

thermal effects of normal faulting during rifted basin formation 2 the lugano val grande normal fault and the role of pre existing thermal anomalies abstract we investigate the thermal consequences of rift related normal faulting and compare the results with a well studied natural example the lugano val grande normal fault southern alps only limited heating of the crust is caused by lithospheric thinning in the simple but realistic situation where heat conduction is substantially faster than heat advection no major thermal disturbance is associated with the downward movement of the hanging wall radiometric ages and fault rocks associated with the lugano val grande normal fault demonstrate that cooling rather than heating affected the crust during normal faulting this pattern is not compatible with such a simple numerical model and is explained by a waning thermal anomaly induced by a magmatic intrusion immediately preceding or overlapping with the first stages of normal faulting the magmatic body must have been emplaced at depths greater than 15 18 km and probably started to cool in the carnian i e few million years before the onset of normal faulting along the lugano val grande fault

the thermal history of the bowen basin queensland australia vitrinite reflectance and clay mineralogy of late permian coal measures abstract the thermal history of the bowen basin queensland australia has been investigated using vitrinite reflectance data and clay mineralogy vitrinite reflectance data combined with a study of clay mineral reactions indicates that the maximum temperatures which induced organic maturation of the bowen basin coals and extensive clay mineralisation are not related to deep burial metamorphism during the latest middle triassic earliest late triassic as previously believed the results of the present study indicate that the development of a zone of high heat flow in the latest late triassic had a major control on the thermal history of the bowen basin high palaeogeothermal gradients estimated in the northern bowen basin are interpreted to result from convective heat transfer during a hydrothermal event variable heat distributions due to localised fracture enhanced permeable zones acting as hot reservoirs in the deeper part of the basin may have been responsible for some significant local thermal anomalies in the lower coal measures the estimated palaeogeothermal gradients in the southern bowen basin also indicate high heat flow in the lower sections of the stratigraphy sections in the southern bowen basin however are believed to reflect a rock dominated semi closed system with low water rock ratio where rocks are impervious to circulating fluids and thus heat transfer may have occurred by conduction the correlation between vitrinite reflectance and clay mineralogy shows a delay in illitisation reaction relative to organic maturity for many illite smectite i s mixed layer clays in the northern bowen basin this phenomenon can be explained as a result of insufficient time for the completion of mineral reactions and a variable potassium supply in relatively impermeable rocks the relationship between i s expandability and vitrinite reflectance for the bowen basin data compared to basins with known tectonic regimes suggests a thermal history in a rift setting for the bowen basin the effect of thin igneous intrusions on clay mineral reactions is very limited intensive illitisation due to heating of intrusions can only be observed in narrow zones immediately adjacent to intrusive bodies this further demonstrates that mineral reactions are too slow to record the effect of extremely short heating duration in contrast to organic maturity indicators these differences between mineral and organic parameters aid in the identification of local contact metamorphic effects

a viscoelastic coupling model for the cyclic deformation due to periodically repeated earthquakes at subduction zones vertical displacements due to periodic reverse faulting events in an elastic plate overlying a viscoelastic maxwell half space are obtained and compared with the observed deformation cycle coseismic strain release postseismic transients interseismic strain accumulation from japan the viscoelastic effects including the influence of buoyant restoring forces are obtained using the method developed by rundle and plate convergence and strain accumulation are incorporated following the procedure suggested by savage the resulting deformation cycle is compared with that of an analogous elastic half space dislocation model in which postearthquake effects are due to transient aseismic slip below the coseismic fault cyclic deformation is similar but not identical for the two models and observations from southwest japan suggest the superiority of the viscoelastic coupling model in particular inclusion of the effects of steady state flow in the asthenosphere overcomes a defect of the elastic half space model and results in agreement with the observed interseismic movement pattern several aspects of the postseismic deformation its landward migration and its transition to the interseismic phase of the cycle are explained as well but the short duration of near trench transients relative to those observed farther inland is not matched the success of a buried slip model in explaining early postseismic near trench movements and asthenospheric flow in accounting for cumulative postearthquake transient motions suggests the existence of a transition zone between lithosphere and asthenosphere whose behavior is brittle elastic in the short term and ductile for longer term deformation and such a modification may reconcile remaining discordant observations however reasonable variations in coupling model parameters cannot account for observed differences in the deformation cycle in other parts of japan and these regional differences remain unexplained

some thermal and mechanical consequences of rapid uplift an example from the southern alps new zealand abstract the thermal evolution of continental crust during active collision is modeled through numerical solutions of the two dimensional heat conduction equation for a rapidly moving medium the boundary conditions used in the modeling are derived from geological and geophysical observations from the active collision zone in the south island of new zealand the problem domain over which the solutions are obtained consists of a 40 km horizontal by 25 km vertical spatial plane with a vertical discontinuity at 10 km from the western boundary to the east of this discontinuity vertical uplift rates of up to 10 mm a occur over a timespan of up to 4 ma temperature distributions are calculated at 10 ka intervals over the 4 ma duration a two dimensional high temperature region is established upon initiation of uplift of the eastern block due to the advective component carrying heat upwards more rapidly than it can be dissipated laterally from the problem domain temperatures within the upper 5 km are greater than 400 c after 2 25 ma with geothermal gradients of up to 200 c km attained within the upper 3 km at times greater than 2 5 ma the vertical temperature distribution changes little while the anomalously high temperatures spread laterally into the stationary crust using rheological equations to describe the brittle behaviour of a water saturated upper crust and the ductile behaviour of a quartz dominated lower crust together with the thermal distribution of the conduction models the mechanical evolution of a collision zone is investigated in addition to high crustal temperatures and associated high heat flow rapid uplift produces a weakening of the crust by raising of the depth of transition from brittle to ductile behaviour within the zone of most rapid uplift the brittle ductile transition rises from 13 km to less than 5 km after 1 5 ma of uplift further uplift reduces the brittle layer to 3 km thickness and causes lateral spreading of the low strength zone the reductions in crustal strength caused by the thermal weakening produce a high strain zone within the region of maximum uplift which is incapable of sustaining large differential stresses this causes horizontal and vertical stress transfer and results in shallow seismicity increases in the adjacent crust as well as in intermediate depth seismicity within the high strength upper mantle because the thermal and mechanical anomalies discussed are a function of rapid uplift all regions of active continental collision may be expected to exhibit similar behaviour some mechanical and thermal characteristics of the himalayan collision zone are briefly examined in light of the numerical modeling

a physical mechanism for temporal variation in seismicity in southwest japan related to the great interplate earthquakes along the nankai trough abstract a significant correlation has been reported between the intraplate inland and the great interplate earthquakes in southwest japan based on historical earthquake data since 868 the frequency of intraplate earthquakes is high for several decades before and up to a decade after great interplate earthquakes to explain the correlation we treated two types of interaction between the inland faults and the plate boundary a in which the stress changes caused by great interplate earthquakes affect the occurrence of intraplate earthquakes and b in which the stress changes caused by intraplate earthquakes trigger other intraplate earthquakes and great interplate earthquakes to simulate the sequences of these earthquakes we calculated the static stress changes resulting from large intraplate and great interplate earthquakes and also estimate the rate of increase in tectonic stress on the faults and the plate boundary the estimated rates of increase here are smaller than those used in previous studies thus in our models stress changes could more strongly affect the seismicity than previously considered we simulated the earthquake sequences for our models in four cases i with no interaction among the inland faults in southwest japan and the plate boundary along the nankai trough ii with stress changes on the inland faults caused only by great interplate earthquakes iii with stress changes on the plate boundary caused only by large intraplate earthquakes and iv with stress changes both on the inland faults and on the plate boundary caused by large intraplate earthquakes the simulated time series in case i of course shows no correlation between intraplate and great interplate earthquakes those in cases iii and iv also show no significant correlation only the time series of intraplate earthquakes in case ii shows a temporal variation similar to that of the real intraplate earthquakes before and after the great interplate earthquakes we examined statistically the similarity between the simulated time series and the real earthquake data about 40 of the time series in case ii are significantly similar although in the other three cases less than 5 of the time series are understanding of the effects of stress changes on the inland faults caused by the great interplate earthquakes along the nankai trough is essential to explain the temporal variation in seismicity in southwest japan before and after the great interplate earthquakes

the schneeberg normal fault zone normal faulting associated with cretaceous se directed extrusion in the eastern alps italy austria abstract the cretaceous eo alpine collisional event in the european eastern alps is generally accepted to induce w nw directed thrusting both in basement and in sedimentary cover units this study presents the first evidence of eo alpine w nw directed normal kinematics along the schneeberg normal fault zone which separates eo alpine high pressure rocks in a footwall position from pre alpine basement rocks in a hanging wall position new garnet sm nd data indicate that exhumation of the high pressure rocks along the normal fault zone started around 95 ma ago and continued up to low greenschist brittle conditions at 76 ma as indicated by a rb sr age from a low temperature mylonite the occurrence of pre alpine basement rocks both in the hanging wall and the footwall of eo alpine high pressure rocks suggests exhumation by extrusion processes despite the displacement or removal of parts of the lower portion of the high pressure unit by tertiary strike slip faults eo alpine top to ese thrusting as expected for the structurally lower part of an extruding wedge was found at and below the base of the eo alpine high pressure rocks a rb sr age of 77 ma from a greenschist facies mylonite in this thrust shear zone shows the contemporaneity of deformation at the base and the top of the wedge the tectonic transport direction within the extruding wedge was e se opposite to the w nw direction so far reported for the eo alpine event in the eastern alps the contemporaneity of opposite tectonic transport directions during continental subduction may be explained by a double vergent wedge model with a narrow zone of ductile flow where the high pressure rocks were exhumed

quantitative description of induced seismic activity before and after the 2011 tohoku oki earthquake by nonstationary etas models 1 the epidemic type aftershock sequence etas model is extended for application to nonstationary seismic activity including transient swarm activity or seismicity anomalies in a seismogenic region the time dependent rates of both background seismicity and aftershock productivity in the etas model are optimally estimated from hypocenter data these rates can provide quantitative evidence for abrupt or gradual changes in shear stress and or fault strength due to aseismic transient causes such as triggering by remote earthquakes slow slips or fluid intrusions within the region this extended model is applied to data sets from several seismic events including swarms that were induced by the m9 0 tohoku oki earthquake of 2011

correlation between optical chemical and micro structural parameters of high rank coals and graphite abstract in order to identify the parameters that best characterize the chemical and structural evolution of organic matter during coalification the relationships between optical chemical and micro structural parameters in high rank coals and natural graphite were studied the samples include anthracites from penarroya belmez espiel basin spain douro basin portugal and alto chicama basin peru and natural graphite from canada mozambique and austria correlations between the following optical parameters were assessed vitrinite random reflectance rr reflectance indicating surfaces ris axis rmax rint and rmin and ris parameters ram rev and rst as well as bw and ai anisotropy parameters furthermore the chemical parameters used were chosen according to their significant variation in coals namely volatile matter carbon and hydrogen contents calculated in dry ash free basis vmdaf cdaf hdaf as well as the h c atomic ratio structural organization was characterized by micro raman spectroscopy and xrd raman parameters used were the full width at half maximum fwhm and position of g and d1 bands on the first order raman spectrum and the id1 ig intensity area ratio the selected xrd parameters were interlayer spacing d002 and crystallite sizes la and lc results show that i rmax ris axis seems to correlate best with chemical and micro structural parameters ii for the majority of studied samples hdaf and h c atomic ratio are the only chemical parameters with significant correlations with rmax iii the fwhm of the g band of raman spectrum shows good linear correlation with the xrd parameter d002 and iv structural organization of carbon materials as measured by trends in their optical and crystalline parameters is influenced by their hydrogen content daf basis and therefore by the h c atomic ratio

eastern alpine tectono metamorphic evolution constraints from two dimensional p t t modeling we use two dimensional 2 d p t t modeling to constrain the thermal and rheological aspects of different scenarios for the late mesozoic and cenozoic tectonic evolution of the eastern alps inferred from excellent data sets from the tauern window tw models invoking subduction of the south penninic sp oceanic lithosphere during thrusting and subsequent erosion of the austro alpine aa upper plate nappe stack are inconsistent with the observed thermal evolution within the aa and penninic units in these models predictions for the aa peak thermal conditions are lower than observed after exhumation and cooling to midcrustal levels and subduction of the continental middle penninic mp block the aa undergoes a phase of renewed heating to almost the previous peak temperatures simultaneously the penninic units experience a phase of heating upon subduction followed by cooling after onset of subduction of the north penninic np basin the model predictions are inconsistent with the observed nearly isothermal uplift path of the sp after subduction and cannot explain observed inverted metamorphic peak conditions in the deeper aa amphibolite facies down to the higher penninic unit greenschist facies a model with the beginning of subduction of the sp occurring after crustal thickening of the aa and subsequent return to normal crustal thicknesses is compatible with the p t t data in this model peak temperature conditions are higher in the aa followed by a phase of strong cooling in the aa upper plate with the onset of underthrusting this model also explains successfully nearly isothermal exhumation of the mp and inverted metamorphic peak conditions in the deeper aa material accreted to the hanging wall from the oceanic crust sp experiences a phase of cooling during ongoing subduction of oceanic lithosphere and begins to heat up to its thermal climax after the subduction of trailing continental lithosphere the subsequent pt path of the penninic units strongly depends on the timing and rates of underthrusting by the foreland observed pt paths in the mp within the tw require continuous subduction of the np and the trailing european foreland under the exhuming mp block documented rapid cooling in the final uplift phase of the penninic units in the tw requires exhumation rates up to approximately 4 mm yr predictions of slightly elevated present day geothermal gradients in the tw area are consistent with available heat flow data as a result of mesozoic rifting followed by late mesozoic crustal thickening of the aa paleorheological reconstructions are characterized by a contrast between relatively strong oceanic lithosphere and adjacent weak continental lithosphere predicted decoupling of weak continental and oceanic lithosphere during subsequent subduction of the penninic units can explain observed late cretaceous crustal extension in the aa units in terms of gravitational spreading ongoing subduction leads to an overall strength increase due to underthrusting of cool oceanic lithosphere whereas subduction of continental lithosphere causes a strength decrease in the upper levels of the lithosphere continuous crustal thickening and relaxation of the depressed isotherms reduce the strength of the lower lithospheric mantle beneath the central orogen further enhanced by rapid late stage uplift predictions for the present day rheological structure of the eastern alps support the existence of a strong upper crustal layer two wedge shaped strong upper mantle layers to the north and the south of the orogen and a weak upper mantle underlying the central orogen

extension in compressional orogenic belts the eastern alps extension in the eastern alps encompasses the following 1 extension accompanying simple shear crustal stacking subhorizontal stretching occurs along flat lying foliations and regionally consistent stretching lineations with associated high strains on a local scale stretching results from extrusion of ductile sediments squeezed between rigid basement blocks basement blocks during thrust sheet imbrication the overall geometric effect is crustal thickening 2 classical extensional tectonics extension first occurs as a consequence of accretion and underthrusting of continental and oceanic material and represents gravitational adjustment of an unstable orogenic wedge extension then occurs as a consequence of terminal continental collision and is accommodated by lateral extrusion of crustal of crustal blocks the overall geometric effect is crustal thinning extension is generally oriented subparallel to the strike of the orogen

cretaceous to neogene cooling and exhumation history of the oetztal stubai basement complex eastern alps a structural and fission track study the central austroalpine oetztal stubai basement complex osk of the eastern alps together with its overlying sedimentary brenner mesozoic bmz and tectonic units upper austroalpine nappes underwent extension and exhumation during the cretaceous before its incorporation into the hanging wall of the neogene brenner normal fault during this late cretaceous to early tertiary deformation the brenner mesozoic and the immediately underlying uppermost part of the osk developed a strong stretching lineation within a near horizontal and often mylonitic foliation related to consistent top to ese directed transport quartz and calcite behaved ductilely throughout the area whereas dolomite shows a transition from brittle fracture in the north to plastic flow in the south consistent with the known cretaceous metamorphic temperature gradient the transition to crystal plastic flow of dolomite occurs at 480 c quartz textures indicate an increase in the contribution of prism glide together with a decrease in basal glide toward the south also consistent with the temperature gradient in the osk and bmz fission track analysis of both zircon and apatite along a n s profile in combination with existing data from the literature allows a continuous cooling path to be constructed for the osk cooling of the eastern osk started at 90 ma the thermal peak of metamorphism and ended some 30 myr later at near surface temperatures at 60 ma the northern region had already cooled below the upper limit of the apatite partial annealing zone whereas in the south cooling related to this exhumation phase stopped at temperatures between 100 and 200 c the ese directed shearing is interpreted as late cretaceous to early tertiary normal faulting that exhumed the osk and brought the upper austroalpine blaser and steinacher nappes into contact with the underlying brenner mesozoic the pattern of alpine metamorphic isograds established in the osk directly reflects the geometry and kinematics of this late cretaceous early tertiary exhumation due to low angle normal faulting

thermotectonic evolution of an extensional dome the cenozoic osogovo lisets core complex kraishte zone western bulgaria the kraishte region of bulgaria is located at the junction of the balkanides and hellenides dinarides tectonic belts fission track analysis on both apatites and zircons documents the cenozoic exhumation of a precambrian basement bounded by low angle detachments late eocene oligocene extension began prior to 47 ma and was dominantly in a top to the southwest direction confirmed by the sense of younging of apatite and zircon ages this crustal extension controlled the formation of half graben sedimentary basins on the hanging walls of the detachments thermal modelling of these hanging wall units provides evidence for heat transfer across the detachments from a relatively warm rising footwall from 32 to 29 ma pervasive magmatic activity resulted in the emplacement of rhyolitic to dacitic subvolcanic bodies and dykes along with intrusion of the osogovo granite the results give evidence for extension in the southern balkan older than and separated from the miocene to quaternary aegean extension this might reflect transtension during northeastward extrusion and rotation of continental fragments around the western boundary of moesia eocene oligocene extension seems to have been controlled by the distribution of earlier thickening all around the carpatho balkanic orocline which is reflected by the cretaceous emplacement of the morava nappe in the kraishte

geology of offshore new ireland basin in northern papua new guinea abstract the 62 mi 100 km wide new ireland basin extends north westward from southwest of bougainville to north of the admiralty islands we have studied some 5 000 mi 8 000 km of geophysical data from the basin north of bougainville to west of manus island the data were gathered by ccop sopac the australian bureau of mineral resources gulf oil co and a french consortium the part of the new ireland basin studied here is a fore arc basin which contains neogene sediments and lies between two ridges formed as part of an old north facing arc trench system in the oligocene and miocene the southern ridge is the old volcanic axis and consists of volcanic rocks forming new ireland new hannover and the admiralty islands the northern ridge appears to be an accretionary prism which forms the southern flank of the west melanesian trench uplifted during its active phase in oligocene miocene times the central new ireland basin is generally a simple little deformed synclinal basin with as much as 3 mi 5 km of well stratified sediment along its axis the basin fill contains several seismic discontinuities and unconformities and probably consists of miocene pliocene quaternary volcaniclastic and carbonate sediments the older sequences are lateral equivalents of sediments outcropping on new ireland and other islands but younger flat lying carbonate oozes and turbidites are ponded in the basin north of new ireland a number of volcanic islands consisting largely of pyroclastic rocks and lavas have cut through the basin northeast of manus island folding and faulting in the basin increase markedly with faults forming large scarps on the sea floor volcanism may have had a more active role in sedimentation reducing seismic penetration in the sediments in areas of extensive flows north of manus island young deformation and volcanism have replaced the flat lying strata common to the central basins area obliterating further traces of the deeper basin if it exists the thickness of the sedimentary sequence and the possible presence of some carbonate buildups at depth in the central basin indicates that the basin may have some petroleum potential major unknowns are source rock potential and the thermal gradient history in the basin carbonate buildups are the most likely reservoir rocks for any petroleum generated in the basin end of article last page 966

the stress field induced from the occurrence of the 1944 tonankai and the 1946 nankaido earthquakes and their relation to impending earthquakes abstract we investigate the changes of tectonic stress in the crust and upper mantle beneath southwest japan associated with the occurrence of the 1944 tonankai and the 1946 nankaido earthquakes and their possible relation to impending earthquakes by using a three dimensional finite element method we construct a three dimensional model incorporating the assumed fault planes of these earthquakes the calculated results indicate that the temporal changes in the direction of the compressive stress from n s to e w beneath the kii channel and the eastern part of shikoku observed after the two earthquakes may be attributed only to the seaward rebound of the hanging wall side of the assumed faults for these earthquakes the temporal change appears to have returned to the original stage after 20 yr indicating that the coseismic disturbance of the stress field could persist for several years the two earthquakes may have caused a local stress drop of

exhumation in a convergent orogen the western tauern window unroofing of the western tauern window involved both low angle detachment faulting brenner fault and enhanced footwall erosion contemporaneous with upright antiformal folding this combination reflects orogen parallel e w extension during continued n s alpine convergence new fission track ages establish the relative chronology of folding and faulting and demonstrate that displacement was not always accommodated on the same surface during exhumation some units migrated from the footwall to the hanging wall of the main detachment fault due to the interplay between folding and faulting the region can effectively be divided into 3 distinct domains 1 the penninic units of the western tauern window were always in the footwall to the fault with maximum exhumation in the core of the dome due to folding and erosion 2 the lower austroalpine unit north of the tauern window was first part of the hanging wall to the brenner fault at a later stage this unit was exhumed by a further 4 5 km as part of the footwall to a more discrete through going fault the silltal fault 3 the middle and upper austroalpine units west of the tauern window were always within the hanging wall exhumation of the footwall from an initial depth of 25 km led to a transition in mechanical behaviour the curviplanar folded ductile shear zone marking the boundary to the tauern window was eventually transected by a more planar discrete brittle fault silltal fault with unit 2 now in the footwall along which the pre existing mylonites were passively exhumed to the surface

raman spectra of carbonaceous material in metasediments a new geothermometer metasedimentary rocks generally contain carbonaceous material cm deriving from the evolution of organic matter originally present in the host sedimentary rock during metamorphic processes this organic matter is progressively transformed into graphite s s and the degree of organisation of cm is known as a reliable indicator of metamorphic grade in this study the degree of organisation of cm was systematically characterised by raman microspectroscopy across several mesozoic and cenozoic reference metamorphic belts this degree of organisation including within sample heterogeneity was quantified by the relative area of the defect band r2 ratio the results from the schistes lustres western alps and sanbagawa japan cross sections show that 1 even through simple visual inspection changes in the cm raman spectrum appear sensitive to variations of metamorphic grade 2 there is an excellent agreement between the r2 values calculated for the two sections when considering samples with an equivalent metamorphic grade and 3 the evolution of the r2 ratio with metamorphic grade is controlled by temperature t along the tinos cross section greece which is characterised by a strong gradient of greenschist facies overprint on eclogite facies rocks the r2 ratio is nearly constant consequently the degree of organisation of cm is not affected by the retrogression and records peak metamorphic conditions more generally analysis of 54 samples representative of high temperature low pressure to high pressure low temperature metamorphic gradients shows that there is a linear correlation between the r2 ratio and the peak temperature t c 445 r2 641 whatever the metamorphic gradient and probably the organic precursor the raman spectrum of cm can therefore be used as a geothermometer of the maximum temperature conditions reached during regional metamorphism temperature can be estimated to 50 c in the range 330 650 c a few technical indications are given for optimal application

a new evaluation of palaeo heat flows and eroded thicknesses for the carboniferous ruhr basin western germany palaeo heat flows and thicknesses of eroded carboniferous overburden in the coal bearing ruhr basin western germany were estimated using one dimensional basin modelling techniques thermal and burial histories for 11 localities were calibrated by comparing measured and calculated vitrinite reflectance data based on the assumption of pre tectonic maturation in contrast to former studies the kinetic easy r0 approach applied for the calculation of vitrinite reflectance lopatin s tti algorithm was used in addition for one well in order to demonstrate the impact of the selection of the algorithm for vitrinite reflectance calculation on the simulation results simulated palaeo heat flows for the time of maximum burial most probably in the stephanian range from 64 to 83 mw m2 and decrease towards the south these heat flows are lower than values computed during earlier studies but are still relatively high in comparison to recent foreland basins the regional distribution of palaeo heat flows indicates that the crust beneath the ruhr basin was relatively thin and thickened towards the south at the end of the carboniferous after the stephanian 2200 3500 m of carboniferous overburden were eroded an observed southward increase in eroded thicknesses is caused by an uplift of the area studied which decreased towards the north at the end of the variscan folding large thicknesses of deposited and later eroded carboniferous sediments have to be postulated to explain the maturity data even along the present southern margin of the ruhr basin this indicates that the late carboniferous sediments originally extended far to the south geological arguments suggest that the deposition of carboniferous sediments in the entire ruhr basin continued until the stephanian

calcite textures examples from nappes with strain path partitioning abstract strain path partitioning partitioning of deformation into components of pure and simple shear in two alpine nappes is qualitatively indicated by a variation in orientation of foliation microkinematic criteria quartz textures and a comparison with strain path partitioning in theoretical nappe models the degree of non coaxial deformation relative to the total deformation is quantified by using the asymmetry of textures in calcite tectonites the texture interpretation is based on both polycrystal plasticity models and experimental data calcite tectonites in the graz paleozoic thrust sheet austria and the morcles nappe switzerland were deformed in a strain path with both pure and simple shear components texture asymmetry supports the strain path derived from geological observations as an exception a high strain ultramylonite deformed nearly exclusively in pure shear it is suggested that this represents a softening instability since deformation in pure shear is energetically more favorable than in simple shear the incompatibilities caused by heterogeneous pure shear are accommodated by detachments and heterogeneous simple shear adjacent to the pure shear zone

a fault model of the 1946 nankaido earthquake derived from tsunami data abstract a fault model of the 1946 nankaido earthquake m 8 2 is determined by the use of tsunami records of uwajima shimotsu and hososhima which were located within or near the area of major coseismic crustal deformation synthetic tsunamis computed for various fault models are matched with the observed tsunamis to determine the fault parameters a low angle thrust model slightly revised from a previous model by ando is consistent with the observed tsunamis the duration of faulting is constrained as less than 10 min based upon the tsunami the fault is divided into an eastern and a western segment corresponding to areas associated with and without aftershocks respectively the fault area and dislocation for the western segment are 150 70 km2 and 6 m and those for the eastern segment are 150 70 km2 and 3 m respectively the total seismic moment is 4 7 1028 dyn cm significantly smaller than that obtained from a geodetic model by fitch and scholz but still larger than that of the seismic model by kanamori the discrepancy in seismic moment between the seismic and the present models ran2 could be interpreted in terms of a slow dislocation on the fault but this interpretation does not match the seismic intensity distribution and damage pattern and the slow slip model for the nankaido earthquake is rejected the discrepancy between the two seismic moments is considered insignificant within error involved in data and modeling assumptions if the revised geodetic model ran2 is modified the seismic moment required to explain the observed tsunamis would be reduced further by 30 if we consider the uncertainties involved in the fault model of kanamori and the fault finiteness effect affecting the amplitude of seismic waves the seismic moment required to interpret the seismic wave data could be increased possibly being more than twice that of kanamori thus the two seismic moments from the different data sets could be close to each other within allowable tolerance this implies that the rise time of the nankaido earthquake was short enough to generate short period seismic waves from both the western and the eastern fault segments

tectonometamorphic evolution of the koralm complex eastern alps constraints from microstructures and textures of the plattengneis shear zone abstract lattice preferred orientations lpo of quartz have been investigated along a south north oriented section across the plattengneis of the koralm complex eastern alps the plattengneis forms an important shear zone within the austroalpine nappe complex of the eastern alps which has developed during the cretaceous evolution of the alpine orogen the quartz c axes form small circle distributions in the southernmost parts of the koralm complex which represent the uppermost structural level of the plattengneis further to the north two maxima between the y and z directions of the finite strain can be interpreted in terms of preferred slip on the rhomb planes these fabrics continuously grade into type i and type ii crossed girdle distributions in a northward direction a strong maximum near the y axis with the tendency to be distributed along a single girdle with three corresponding maxima of a axes near the margin of the pole figure can be observed in the central and northern parts such lpo are characteristic for both high grade metamorphic conditions and high finite strain the microstructures display that the deformation within the plattengneis shear zone was synmetamorphic a continuous increase of peak temperatures and pressure from approximately 550 c to approximately 750 c from the south to the central parts can be inferred from geothermometric calculations the temperatures then decrease to approximately 650 c from the central parts to the north the related pressures increase from 8 to 16 kbar and then decrease to 10 kbar the lpo changes that have been observed in the study area are best interpreted in terms of temperature dependence of the activation of glide systems within quartz aggregates the temperature and pressure evolution may indicate that the central parts of the koralm complex have been exhumed by larger amounts than the northern and southern parts this is also documented by the lpo evolution therefore we assume that the plattengneis shear zone formed during the exhumation of the koralm complex and is related to the exhumation of high pressure units in the footwall of this shear zone accordingly the kinematics of the plattengneis shear zone is rather extensional than thrust related the implications for the structural evolution of the eastern alps are shortly discussed

thermal evolution of an extensional detachment as constrained by organic metamorphic data and thermal modeling graz paleozoic nappe complex eastern alps abstract following early cretaceous nappe stacking the eastern alps were affected by late orogenic extension during the late cretaceous in the eastern segment of this range a late cretaceous detachment separates a very low to low grade metamorphic cover graz paleozoic nappe complex gpnc above a low to high grade metamorphic basement synchronously the kainach gosau basin kgb collapsed and subsided on top of the section metamorphism of organic material within this section has been investigated using vitrinite reflectance data and raman spectra of extracted carbonaceous material in the southern part of the gpnc vitrinite reflectance indicates a decrease in organic maturity towards the stratigraphic youngest unit the remaining part of the gpnc is characterized by an aureole of elevated vitrinite reflectance values and raman r2 ratios that parallels the margins of the gpnc vitrinite reflectance in the kgb shows a steep coalification gradient and increases significantly towards the western basin margin the observed stratigraphic trend in the southern gpnc is a result of deep paleozoic to early cretaceous burial this maturity pattern was overprinted along the margins by advective heat and convective fluids during late cretaceous to paleogene exhumation of basement rocks during shearing the fault zone was heated up to ca 500 c this overprint is explained by a two dimensional thermal model with a ramp flat fault geometry and a slip rate of 1 to 1 5 cm year during 5 ma fault movement the collapse basin above the detachment subsided in a thermal regime which was characterized by relaxing isotherms

late cretaceous exhumation of the metamorphic gleinalm dome eastern alps kinematics cooling history and sedimentary response in a sinistral wrench corridor abstract the metamorphic gleinalm dome eastern alps was uplifted and exhumed within a releasing structure in a sinistral wrench corridor during the late cretaceous the dome is confined by a system of ductile shear zones including low angle normal faults and steep sinistral tear faults which define a large releasing structure with the metamorphic dome in its center the fabrics developed within all ductile shear zones record processes which were operating during decreasing temperatures from initial epidote amphibolite upper greenschist facies conditions with crystal plastic fabrics in quartz to temperatures below ca 300 c with predominantly cataclastic fabrics a cooling path based on 40ar 39ar amphibole 95 4 1 2 ma and muscovite ages 87 6 0 6 84 3 0 7 ma together with sphene zircon and apatite fission track data indicate cooling through ca 500 c at ca 94 ma to below ca 250 200 c at 65 ma subsidence of the adjacent late cretaceous kainach gosau basin occurred synchronously with cooling and uplift of the gleinalm dome internal depositional patterns record rapid subsidence at the time of cooling with internal synsedimentary block rotation above an intra crustal ductile normal fault the sinistral wrench corridor of the eastern alps developed by sinistral displacement of the austroalpine units against a relatively stable europe during the late cretaceous

new insight into the south tibetan detachment system not a single progressive deformation 1 low angle normal faults lanf typically regarded as accommodating crustal or lithospheric extension may also form during lithospheric shortening the best studied system of syn contractional lanfs is the south tibetan detachment system a network of low angle normal sense faults and shear zones that formed coevally with and parallel to south vergent thrusts during lithospheric shortening accompanying development of the himalayan orogen in the eastern himalaya there are several across strike exposures of the south tibetan detachment system we present new structural and thermometry data from the eastern himalaya that demonstrate that the south tibetan detachment system cannot have formed as a single progressive structure we characterize and distinguish two distinct structural and tectonic components within the currently recognized system 1 an extensive diffuse sheared layer that formed the boundary between strong upper crust and weak southward flowing middle crust and 2 a network of brittle ductile lanfs that locally exhume partly excise and overprint the earlier mylonite zone at the topographic break between the himalayan orogen and the tibetan plateau the sheared layer not a lanf formed the boundary between upper and middle crust during ductile flow of the middle crust and is extensively exposed in the himalaya at the base of klippen of upper crustal rocks preserved in bhutan along the crest of the himalaya where it has been excised and exhumed by the brittle ductile extrusion lanfs and bounding the cores of the north himalayan gneiss domes citation kellett d a and d grujic 2012 new insight into the south tibetan detachment system not a single progressive deformation tectonics 31 tc2007 doi 10 1029 2011tc002957

late cretaceous synorogenic low angle normal faulting along the schlinig fault switzerland italy austria and its significance for the tectonics of the eastern alps abstract the schlinig fault at the western border of theotztal nappe eastern alps previously interpreted as a west directed thrust actually represents a late cretaceous top se to ese normal fault as indicated by sense of shear criteria found within cataclasites and greenschist facies mylonites normal faulting postdated and offset an earlier cretaceous age west directed thrust at the base of theotztal nappe shape fabric and crystallographic preferred orientation in completely recrystallized quartz layers in a mylonite from the schlinig fault record a combination of 1 top east southeast simple shear during late cretaceous normal faulting and 2 later north northeast directed shortening during the early tertiary also recorded by open folds on the outcrop and map scale offset of the basal thrust of theotztal nappe across the schlinig fault indicates a normal displacement of 17 km the fault was initiated with a dip angle of 10 to 15 low angle normal fault domino style extension of the competent late triassic hauptdolomit in the footwall was kinematically linked to normal faulting the schlinig fault belongs to a system of east to southeast dipping normal faults which accommodated severe stretching of the alpine orogen during the late cretaceous the slip direction of extensional faults often parallels the direction of earlier thrusting top w to top nw only the slip sense is reversed and the normal faults are slightly steeper than the thrusts in the western austroalpine nappes extension started at about 80 ma and was coeval with subduction of piemont ligurian oceanic lithosphere and continental fragments farther west the extensional episode led to the formation of austroalpine gosau basins with fluviatile to deep marine sediments west directed rollback of an east dipping piemont ligurian subduction zone is proposed to have caused this stretching in the upper plate

thermal constraints on the seismogenic portion of the southwestern japan subduction thrust for coastal cities an important factor in earthquake hazard from subduction zone earthquakes is the landward extent of the seismogenic portion of the subduction thrust fault in this study we test the hypothesis that the maximum downdip extent is defined by a critical temperature we have developed a transient thermal model for the nankai subduction zone of southwest japan to allow comparison of the thermally estimated downdip extent of the seismogenic zone with that from 1 seismicity and tsunami data for two great subduction earthquakes 2 the coseismic faulting extent of these events estimated from geodetic deformation data and 3 the interseismic locked zone determined from interseismic geodetic data the nankai margin has extensive heat flow and heat production data to control thermal models and thus crustal temperatures it has earthquake tsunami and geodetic data that constrain the coseismic rupture portion of the subduction thrust fault for past great earthquakes and the portion of the thrust fault that is locked and storing interseismic elastic strain on the nankaido margin off shikoku island the thermal model indicates that a temperature of 350 c taken to be the limit for seismic initiation from laboratory and field data is reached on the subduction thrust fault 150 km from the trench a transition zone into which rupture may extend with decreasing offset taken to be 450 c extends an additional 45 km downdip the thermal model results are in excellent agreement with the maximum downdip extent of coseismic displacement for the 1946 nankaido ms 8 2 earthquake off shikoku island and with the downdip extent of the present locked zone in the region of the 1944 tonankai ms 8 2 earthquake to the northeast the subduction angle is much steeper and the thermal models indicate a narrower downdip seismogenic extent the seismogenic locked zone from earthquake and geodetic data is also narrower thus our analysis of the southwest japan margin indicates that all three constraints on the downdip extent of the seismogenic zone thermal coseismic and interseismic geodetic data are in general agreement the study also supports the hypothesis that the seismogenic portion of subduction thrust faults is limited primarily by temperature the thermal control implies that subduction thrust faults with shallow dip have wider seismogenic zones compared to those with steep dip the subducting plate age and thus heat flow and the thickness of the insulating sediments on the incoming plate are also very important to the thermal regime and thus to the seismogenic width the relation of the maximum seismic rupture area to the interseismic locked zone is particularly important for earthquake hazard estimation on subduction margins such as cascadia where there have been no great historical events

displacement fields due to the 1946 nankaido earthquake in a laterally inhomogeneous structure with the subducting philippine sea plate a three dimensional finite element approach abstract the displacement fields associated with the 1946 nankaido earthquake have been investigated in detail taking into account the configuration of the philippine sea plate subducting beneath southwest japan we used a three dimensional finite element method for the elastic problem to examine the effects of three dimensionally inhomogeneous structure some differences in the displacement patterns between homogeneous and inhomogeneous media have been identified the amounts of displacements are large in low rigidity portions such as in the crust and mantle wedge and are small in a high rigidity portion composed of the subducting plate the inhomogeneity affects horizontal displacements at the earth s surface more than vertical displacements if the rigidity and the poisson ratio given here to southwest japan are appropriate the fault parameters of the earthquake which have been estimated from simple dislocation models in a homogeneous semi infinite medium need to be modified somewhat the present computations indicate that larger dip angles and smaller fault slips are more appropriate fault parameters when structural inhomogeneity is taken into account this suggests that the discrepancy in the obtained total seismic moment between the geodetic and seismic models of the nankaido earthquake could be reduced

two dimensional thermal modelling of normal faulting the simplon fault zone central alps switzerland abstract two dimensional finite difference thermal modelling of the major extensional simplon fault zone in the central alps establishes that the shape of cooling curves for samples from the footwall and hanging wall at various distances from the detachment are very sensitive to the actual displacement history if the displacement had occurred within a very limited time span 18 15 ma samples from the hanging wall close to the detachment should have significantly increased in temperature with a peak around 14 ma this is not discernible in the cooling curves interpreted from the mineral ages if the rate of normal fault displacement had been lower but constant from 18 ma to present the cooling curves for the footwall should show a correspondingly steady decrease in temperature the interpreted cooling curves from mineral ages are steep after 18 ma becoming shallower in more recent times this shape can be reproduced by the thermal modelling for a variable rate of fault displacement initially rapid total relative displacement 10 mm a across the fault zone between 18 and 15 ma but reducing to a more steady 0 4 mm a between 15 ma and 3 ma the corresponding exhumation rate of the footwall was 4 6 mm a from 18 to 15 ma and 0 6 mm a from 15 to 3 ma whereas the hanging wall was exhumed at a constant rate of 0 4 mm a the difference in cooling curves for samples with increasing horizontal distance into the footwall reflects a distributed ductile shear with the sample at 20 km distance initially at 25 km depth at 25 ma whereas that at 70 m distance was only at 19 km depth at the same time samples in the hanging wall were at 10 km depth total relative displacement parallel to the fault plane was around 36 km the thermal modelling demonstrates that during rapid fault displacement the apparent exhumation rate calculated assuming a constant geothermal gradient is too low whereas the apparent rate calculated for the subsequent period of slower displacement is too high

exhumation of the rechnitz window at the border of the eastern alps and pannonian basin during neogene extension abstract the rechnitz window is the easternmost penninic window of the alps and the only one that is partly covered by neogene sediments zircon and apatite fission track ages have been measured on the penninic metasediments of the rechnitz series to better understand the exhumation of the window at the alpine pannonian border the zircon ft ages range from 21 9 to 13 4 ma similar to the white mica k ar ages 19 and 23 ma the exhumation rate during the early miocene extension was high 40 c ma apatite samples display ft ages of 7 3 and 9 7 ma thus the cooling rate was significantly less 7 11 c ma during the post rift uplift uplift in late miocene pliocene than in the early miocene escape period zircon ft ages decrease eastward due to the gradual southeastward slide of the austroalpine cover along low angle normal faults the exhumation of the rechnitz metamorphic core complex is younger than the unroofing of the eastern tauern window morphology of detrital zircon crystals of the penninic metasediments was used for the differentiation of tectonic subunits and to trace the internal structure of the window one population was probably derived from undifferentiated calc alkaline granitoids and tholeiitic granitoid sources while the other derived from evolved calc alkaline granitoids and alkaline granitoids of anorogenic complexes the areal distribution of zircon populations is in harmony with the eastward shift of zircon cooling ages these data indicate the exhumation of deep levels of penninic metasediments in the centre of the window

thermal effects of exhumation of a metamorphic core complex on hanging wall syn rift sediments an example from the rechnitz window eastern alps the removal of overburden by tectonic processes displaces the rock masses and their temperature with respect to the surface consequently high cooling rates and increased heat flow have been reported from rapidly exhuming terrains previous studies were mainly focused on the greenschist and amphibolite facies tectono thermal evolution of the footwall a two dimensional numerical thermal model presented in this study concentrates on the thermal history of the hanging wall and the footwall blocks and evaluates the variation of the near surface heat flow above an evolving metamorphic core complex based on structural thermobarometric and geochronological constraints from the rechnitz core complex of the eastern alps the modelling suggests that rapid movement along the extensional fault took place between 22 and 17 ma during this period the heat flow reached values of 140 150 mw m 2 in the hanging wall in a 10 15 km wide zone parallel to the fault trace the increased heat flow caused the high coal rank in the miocene syn rift sediments deposited on the hanging wall apatite fission track geochronology of the thermally overprinted sedimentary deposits gives the time at which the bottom of the syn rift sediment pile passed through 110oc 13 6 0 9 ma the vitrinite reflectance data rr 0 67 1 04 suggest significant burial of the margin of the hanging wall at the time of core complex formation considering the coal rank data and the thermal conductivity of the sedimentary deposits by modelling of the organic maturation we calculate syn rift early middle miocene burial of the hanging wall margin of the rechnitz core complex to be 1100 1600 m this value shows the importance of the post middle miocene erosion of the region which was related to the inversion of the pannonian basin 1998 elsevier science b v all rights reserved

large scale strike slip displacement of the drauzug and the transdanubian mountains in early alpine history evidence from permo mesozoic facies belts abstract both the drauzug italy austria and the transdanubian mountains hungary show great differences in facies compared to the geological units that presently surround them i e proximal facies contrast with distal facies in the permo triassic lower liassic strata in the drauzug and the transdanubian mountains indicate an extensional regime causing typical structural features such as tilted blocks fault scarps and drowned carbonate platforms the permo mesozoic facies zones provide markers for the paleogeographic fitting of the drauzug and the transdanubian mountains with areas today lying some 300 400 km to the west the drauzug corresponds to the lombardian basin and the westernmost part of the northern calcareous alps while the transdanubian mountains correspond to the westernmost part of the lombardian basin the trento platform and the belluno trough the drauzug and the transdanubian mountains together with the south alpine realm were displaced to the east along strike slip faults during the middle jurassic to early cretaceous opening of the central atlantic and ligurian piemont oceans and the simultaneous subduction of the vardar ocean at the eastern margin of apulia finally in late oligocene and miocene times the southern alps were displaced back to the west along the dextral periadriatic fault system

kinematics of cretaceous nappe tectonics in the austroalpine basement of the koralpe region eastern austria krohe a 1987 kinematics of cretaceous nappe tectonics in the austroalpine basement of the koralpe region eastern austria tectonophysicz 136 171 196 the austroalpine basement of the koralpe area austria was affected by penetrative ductile deformation in the cretaceous three metamorphic events have been established ht lp metamorphism of unknown age a hercynian mt mp metamorphism and a cretaceous eo alpine mt mp metamorphism in the koralpe area cretaceous rb sr cooling ages of muscovite indicate temperatures of at least 500 o c during the eo alpine event the most intense deformation occurred along intracrustal shear zones plattengneis north to northeast directed thrusting is indicated by an inverted metamorphic gradient regional transposition of an older foliation s c fabrics and oblique quartz fabrics after development of high temperature mylonites low angle normal shear zones low temperature mylonites cut the uppermost parts of the austroalpine basement and indicate an extensional tectonic setting at about 85 to 90 ma s c and quartz fabrics indicate downdip movements of the hanging wall towards the northeast intracrystalline a slip in quartz caused strong preferred lattice orientation in high and low temperature mylonites during the e alpine deformation the basal a slip system is more pronounced at lower temperatures whereas a prism a system predominates at higher temperatures the overall kinematic history of the austroalpine nappe complex in the study area suggests a model in which an intracrustal south over north imbrication took place in an early stage of eo alpine collision these movements were outlasted by sinistral strike slip movement possibly due to oblique collision along irregular margins of the austroalpine and brianpnnais complexes the collision imbrication process resulted in crustal thickening isostatic uplift and thus extension of the higher parts of the crust low angle normal faulting initiated sedimentation in the intramontane c tic gosau basins of late cretaceous age

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

deformation and stress change associated with plate interaction at subduction zones a kinematic modelling summary the interseismic deformation associated with plate coupling at a subduction zone is commonly simulated by the steady slip model in which a reverse dip slip is imposed on the down dip extension of the locked plate interface or by the backslip model in which a normal slip is imposed on the locked plate interface it is found that these two models although totally dierent in principle produce similar patterns for the vertical deformation at a subduction zone this suggests that it is almost impossible to distinguish between these two models by analysing only the interseismic vertical deformation observed at a subduction zone the steady slip model cannot correctly predict the horizontal deformation associated with plate coupling at a subduction zone a fact that is proved by both the numerical modelling in this study and the gps global positioning system observations near the nankai trough southwest japan it is therefore inadequate to simulate the eect of the plate coupling at a subduction zone by the steady slip model it is also revealed that the unphysical assumption inherent in the backslip model of imposing a normal slip on the locked plate interface makes it impossible to predict correctly the horizontal motion of the subducted plate and the stress change within the overthrust zone associated with the plate coupling during interseismic stages if the analysis made in this work is proved to be correct some of the previous studies on interpreting the interseismic deformation observed at several subduction zones based on these two models might need substantial revision on the basis of the investigations on plate interaction at subduction zones made using the finite element method and the kinematic mechanical conditions of the plate coupling implied by the present plate tectonics a synthesized model is proposed to simulate the kinematic eect of the plate interaction during interseismic stages a numerical analysis shows that the proposed model designed to simulate the motion of a subducted slab can correctly produce the deformation and the main pattern of stress concentration associated with plate coupling at a subduction zone the validity of the synthesized model is examined and partially verified by analysing the horizontal deformation observed by gps near the nankai trough southwest japan

sm nd dating of hydrothermal carbonate formation an example from the breitenau magnesite deposit styria austria abstract the geochemical evolution and chronology of the breitenau sparry magnesite deposit has been investigated by means of major and trace element abundances stable c o isotope and sm nd isotope analysis chemically separated magnesite fractions leachates show consistent light ree depleted rey patterns marine carbonate normalized and nearly constant normalized values for the middle and heavy ree without significant ce eu or y anomalies non carbonate residues composed of dark matrix material are high in al 2 o 3 and show variably light to middle ree enriched rey patterns similar to shales leachates of limestone from nearby country rocks have normalized rey patterns similar to marine carbonates only ce and y are slightly fractionated based on their trace element chemistry and normalized rey patterns leachates of dolomite from the margin of the deposit closely resemble either limestone type a or magnesite type b with one exception 18 o vpdb for both dolomite types is within the range of the respective magnesite values 18 o vpdb c 14 2 to 15 7 leachates of dolomite from druses within the deposit type c show low rey abundances with normalized patterns similar to those of magnesite sm nd isotope data for magnesite leachates yield a well defined isochron age of 222 5 9 8 ma mswd 3 1 isochron calculations for leachate s and residue s from individual magnesite samples internal isochrons yield ages between 236 16 ma and 193 5 8 6 ma with a low degree of scatter mswd 18 o vpdb c 15 2 37 9 5 4 ma 18 o vpdb c 12 5 and 3 1 7 6 8 ma 18 o vpdb c 11 type c dolomite data indicate that druses were formed by open system fluid flow throughout the deposit

graphitization in a high pressure low temperature metamorphic gradient a raman microspectroscopy and hrtem study the graphitization of carbonaceous material cm in a high pressure metamorphic gradient is characterized along a cross section in the schistes lustres formation western alps along this 25 km cross section both the cm precursor and the host rock lithology are homogeneous and the prograde evolution of the pressure temperature metamorphic conditions from the lower blueschist facies 13 kbar 330 c to the eclogite facies 20 kbar 500 c is tightly constrained by literature data raman microspectroscopy shows that at the micrometre scale this process is progressive and continuous with increasing metamorphic grade and that the structure of cm is very sensitive to temperature variations at the nanometre scale hrtem the cm is composed of a mixture of a microporous phase and an onion ring like phase both known as non graphitizing under the effect of temperature at ambient pressure the hp lt graphitization produces structurally and microtexturally heterogeneous cm with increasing metamorphic grade the graphitization of the two types of cm proceeds up to the triperiodic graphite stage because of microtextural and structural changes that are specific to each type of cm the microporous material is progressively transformed into graphite through a macroporous transitional stage in this case graphitization mainly occurs on the pore walls as a result of pore growth in the case of concentric onion ring like material graphitization occurs in the regions with the largest radius of curvature i e on the outer part of the ring in comparison with 1 bar experiments pressure seems to induce microtextural changes which allows the subsequent structural modifications of the starting material

internal structural geometry of the paleozoic of graz the paleozoic of graz is an isolated nappe complex of about 1 500 km2 size and belongs to the austroalpine units of the eastern european alps despite more than 500 publications on stratigraphy paleontology and local structure many aspects of the internal geometry of this complex as a whole remained unclear in this contribution we present integrated geological profiles through the entire nappe complex based on these profiles we present 1 a simplified lithological subdivision into 13 rock associations 2 a modified tectonostratigraphy where we consider only two major tectonic units an upper and a lower nappe system and in which we abandon the traditionally used facies nappe concept and 3 a modified paleogeography for the whole complex finally we discuss whether the internal deformation of the paleozoic of graz is of variscan or eo alpine age and which of the published models best explain the tectonic evolution of the paleozoic of graz

cold spots during the cenozoic evolution of the eastern alps thermochronological interpretation of apatite fission track data abstract the tectonical and morphological evolution of the eastern alps during the cenozoic is discussed in the light of sedimentary record and thermochronological data of crystalline basement rocks the regional distribution of apatite fission track data in the central eastern alps reveals the differential cenozoic exhumation in contrast to the penninic of the tauern window which has been strongly uplifted and eroded since the early miocene the amount of neogene denudation was much smaller in most areas east of the hohe tauern a sudden change in the regional cooling behaviour is observed at the katschberg fault system which must have been active in post oligocene times within the austroalpine only the schladming tauern have experienced a rather strong denudation the seckau core complex east of the pols line and the area of the northern koralpe cooled to below 100 c at the end of the cretaceous and in the early eocene respectively and have never been heated again during the cenozoic these parts of the austroalpine nappe pile were always near to the surface and therefore may be summarized under the term cold spots a major post cretaceous thickening of the austroalpine can be excluded because it would have produced more uplift and erosion any remnants of miocene or older landforms are certainly not preserved in the area of the tauern window the uppermost planation surfaces in the crystalline basement at the western border of the styrian basin koralpe probably developed in the late miocene

crustal thermal regime prior to during and after rifting a geochronological and modeling study of the mesozoic south alpine rifted margin an approximately 15 km thick segment of the mesozoic passive continental margin of adria was involved in alpine shortening and is now exposed in the lake como lake lugano area southern alps northern italy and southern swit zerland the segment comprises the monte generoso basin a deep 9 km extensional basin controlled by the activity of the lugano val grande normal fault the paleosurface and mesozoic geometric relations are well preserved so that the kinematics of fault blocks prior to during and after extension are well constrained rb sr 4oar 39ar and zircon fission track data from basement rocks underlying at various the generoso basin depths provide independent estimates on the thermal evolution of the crustal segment during and after rifting most rb sr and 4oar 39ar ages are contemporaneous with the initial stages of rifting late triassic to early jurassic documenting 1 strongly altered thermal conditions before the onset of ex tension and 2 cooling throughout rifting thermal gradients decreased from 60oc km at the onset of extension to 20oc km 4 shortly after breakup zircon fission track ages are juras sic to early cretaceous providing evidence for continued cooling until the beginning of alpine shortening thermoki nematic numerical modeling of the considered crustal segment provides a full two dimensional description of synrift and postrift evolution synthetic time versus temperature curves are extracted from the model and compared with those derived from absolute ages

a quantitative interpretation on possible correlations between intraplate seismic activity and interplate great earthquakes along the nankai trough abstract the tonankai earthquake occurred in 1944 along the nankai trough between the continental eurasian plate and the subducting philippine sea plate we investigated spatial and temporal correlations between the occurrence of this event and intraplate seismic activities in the inland region of southwest japan in order to elucidate the possible relationship and dynamic coupling between the 1944 tonankai and the 1946 nankaido earthquakes we calculated stress changes due to the tonankai earthquake by applying a three dimensional finite element method and compared them with post seismic activity agreement between them appears quite well at a depth of 10 km indicating that stress release in an e w direction associated with the tonankai earthquake may have reduced the seismic activity in the inland region particularly the observed drastic decrease of seismicity in the wakayama region just after this event can be explained by significant decrease of compressive stresses in the e w direction extensive seismicity quiescence preceding the 1946 nankaido earthquake which occurred adjacent to the source region of the tonankai event may be related to the enhancement of n s oriented compressive stress due to accelerating northward movement of the philippine sea plate therefore in addition to the decrease of stresses in the e w direction the increase of the n s oriented compressive stresses might play an important role to yield low seismic activity just after the tonankai event the calculated results show that the post seismic shear stress increased and the normal stress decreased near the hypocentral area of the 1946 nankaido earthquakes while the shear stress decreased and normal stress increased in its surrounding area on the fault this indicates that the tonankai earthquake made it easier for the rupture of the nankaido earthquake to originate at the observed hypocenter this triggering mechanism may explain the synchronous pattern of historical great interplate earthquakes along the nankai trough a great earthquake occurs in the western region within a few years after the first breakage in the eastern block

late cretaceous extension overprinting a steep belt in the northern calcareous alps schesaplana ratikon switzerland and austria the triassic to cretaceous sediment succession of the lechtal nappe in the western part of the northern calcareous alps nca has been deformed into large scale folds and crosscut by thrust and extensional faults during late cretaceous eoalpine and tertiary orogenic processes the following sequence of deformation is developed from overprinting relations in the field d1 nw vergent folds related to thrusting d2 n s shortening leading to east west trending folds and to the formation of a steep belt arlberg steep zone along the southern border of the nca d3 e w to ne sw extension and vertical shortening leading to low angle normal faulting and recumbent collapse folds like the wildberg syncline d1 and d2 are cretaceous in age and predate the eocene emplacement of the austroalpine on the penninic nappes along the austroalpine basal thrust the same is probably true for d3 finally the basal thrust was deformed by folds related to out of sequence thrusting these results suggest that the nca were at least partly in a state of extension during the sedimentation of the gosau group in the late cretaceous

oil and gas developments in new zealand and southwest pacific islands in 1981 new zealand has experienced a strong increase in exploration activity offshore license holdings are up to 164 015 km2 an increase of 53 onshore licences are 20 467 km2 an increase of 77 four offshore wells were drilled to a total depth of 13 690 m they were all dry onshore drilling amounted to 8 548 m and was concentrated around last year s oil discovery of mckee 2a the field was confirmed by 1 extension well mckee 3a whereas 2 other wells were dry and a fourth extension well still drilling by year end onland seismic surveys covered 484 line km while marine seismic work amounted to 6 561 km because of increased re injection of gas in the kapuni field the saleable production slightly went down but condensate production rose by nearly 50 000 m3 i e 21 more than last year with the strongly increased output from the offshore maui field total gas production for sale was 1 286 106 m3 up 20 2 while the total production of condensate was 550 101 m3 up 31 3 lpg production rose to 41 179 m3 up 50 8 tonga has experienced a virtual standstill in exploration but ccop sopac has completed and prepared for publication its interpretation of a single channel seismic survey over the southern tongan platform conducted the year before in fiji license areas remained unchanged but a new company bennett petroleum corp acquired a 75 interest in block d extensive geochemical sampling and minor geophysical surveys were undertaken in several blocks and a shallow stratigraphic hole was drilled to 307 m in vanuatu which still lacks petroleum legislation no exploration licenses were granted a ccop sopac sponsored study of all existing marine seismic surveys has been completed and a summary of results has been prepared for publication the solomon islands too has no petroleum legislation as yet ccop sopac ran single channel seismic surveys to a total of 1 115 line km mainly near rennell island but also some in the central solomons trough in papua new guinea the total concession areas increased to 72 600 km2 oil companies recorded 550 km of seismic lines onshore and 1 716 km offshore aeromagnetic surveys covered 9 779 line km outside concession areas ccop sopac conducted single channel seismic surveys in the new ireland basin between bougainville and manus island for a total length of 4 964 km interpretation of these surveys has been completed and prepared for publication an appraisal well barikewa 2 was spudded shortly before year end initial reserve estimates for this large anticline had run as high as 10 tcf of gas in place drilling depth will be about 2 120 m

3 d assessment of peak metamorphic conditions by raman spectroscopy of carbonaceous material an example from the margin of the lepontine dome swiss central alps this study monitors regional changes in the crystallinity of carbonaceous matter cm by applying micro raman spectroscopy to a total of 214 metasediment samples largely so called bundnerschiefer dominantly metamorphosed under blueschist to amphibolite facies conditions they were collected within the northeastern margin of the lepontine dome and easterly adjacent areas of the swiss central alps three dimensional mapping of isotemperature contours in map and profile views shows that the isotemperature contours associated with the miocene barrow type lepontine metamorphic event cut across refolded nappe contacts both along and across strike within the northeastern margin of the lepontine dome and adjacent areas further to the northeast the isotemperature contours reflect temperatures reached during the late eocene subduction related blueschist facies event and or during subsequent near isothermal decompression these contours appear folded by younger large scale post nappe stacking folds a substantial jump in the recorded maximum temperatures across the tectonic contact between the frontal adula nappe complex and surrounding metasediments indicates that this contact accommodated differential tectonic movement of the adula nappe with respect to the enveloping bundnerschiefer after maximum temperatures were reached within the northern adula nappe i e after late eocene time

oil and gas developments in new zealand and southwest pacific islands in 1984 new zealand had an increase in petroleum production while exploration drilling continued at 1983 s high level although there was an overall drop in licensed acreage the amount of seismic exploration increased markedly with 1 100 km of acquisition onshore and 4 300 km offshore a new oil discovery toetoe 1a was made near mckee field combined production from kapuni maut mckee and kaimiro fields was 2 978 56 106 million m3 of gas up 25 and 962 323 m3 of condensate up 14 the combined mckee and pouri fields which came on line in november are producing oil at about 5 200 b d 830 m3 day all licenses in tonga have been relinquished and all company data are on open file new petroleum legislation will be in force in 1985 fiji had no exploration activities three license blocks have been renewed at reduced acreage vanuatu and the solomon islands are still awaiting legislation for petroleum exploration a second stage of a ccop sopac sponsored tripartite project s p lee cruise was carried out in both countries and also in tonga and the new ireland basin of papua new guinea on the mainland of papua new guinea 5 wells were drilled to a combined depth of 10 158 m up 10 9 an were dry concession areas comprise 11 petroleum prospecting licences with a total of 1 062 blocks at 5 min graticules

thermal modeling of carboniferous to triassic sediments of the karawanken range southern alps as a tool for paleogeographic reconstructions in the alpine dinaridic pannonian realm vitrinite reflectance was measured in late carboniferous to triassic shales siltstones and marls of the karawanken range thermal models of the central south karawanken range were calibrated on the basis of these data they suggest an eroded overburden of more than 3 200 m of jurassic to cretaceous sediments and a heat flow in the range of 42 to 60 mw m 2 during the time of maximum subsidence because the reconstructed thermal history of the south karawanken range is very similar to the thermal history of the generoso basin western southern alps these data provide strong evidence for a deep basinal position of the southern karawanken range during jurassic to cretaceous times a vitrinite reflectance anomaly at the northern margin of the south karawanken range is explained by advective heat transport during the oligocene the heat source for the anomalies at the western margin of the seeberg rise and in the area between the periadriatic lineament and the donat fault zone is unknown vitrinite reflectance in late triassic sediments indicates the south karawanken range and the south zala unit of the pannonian basement as exotic blocks in the sava composite unit this is explained by miocene displacement of structural units which were derived from different paleogeographical segments of the permo mesozoic western tethyan margin

subsidence and sedimentation on jurassic passive continental margin southern alps italy the southern alps of italy preserve a tectonically intact array of jurassic facies that record the evolution of a part of the margin of the apulian plate from its ancestral beginnings in a complex of permian and triassic rifted continental basins through the initial stages of breakup and stepwise foundering of a carbonate platform breakup was accompanied first by the rapid accumulation of thick prisms of carbonate turbidites in newly formed fault troughs then as the new ligurian oceanic basin began to open farther west and as subsidence gradually slowed accumulation of a succession of slowly deposited biogenous pelagic sediments recorded not only the increasing depths of the seafloor but also fluctuations in oceanographic conditions of fertility carbonate dissolutio levels and the strength of bottom currents estimates of the history of seafloor depths based on a simple subsidence law of the form subsidence k age 12 provide a basis for the construction of a set of curves showing the changing depths of significant carbonate dissolution surfaces during the jurassic in this region the rapid 1 km deepening of the compensation depth for calcite during the late jurassic may be due to a change in regional oceanic vertical circulation patterns from upwelling fertile silica rich carbonate dissolving to downwelling less fertile silica poor carbonate preserving

an andean model of interplate coupling and strain partitioning applied to the flat subduction zone of sw japan nankai trough abstract transcurrent motion is commonly observed in cases of oblique subduction yet the causes remain controversial a model of increased interplate coupling linked to flat subduction is proposed as a mechanism for producing strain partitioning at a great distance several hundred km from the trench the model originally developed for the north andean margin is applied to the geodynamics of sw japan here along the nankai trough and below adjacent sw honshu flat subduction occurs due to the relatively young age m 7 and nine additional m 6 earthquakes in the past 300 years dextral strike slip focal mechanisms for 15 modern and historical events indicate a significant degree of subduction related strain partitioning manifested by right lateral strike slip faulting along the adakitic volcanic arc some 400 km from the nankai trough

conversion of carbonaceous material to graphite within the greywacke zone of the eastern alps morphology and reflectance of carbonaceous material cm in late carboniferous metasediments of the eastern greywacke zone eastern alps indicate a mixture of vitrinite grainy textured and lamellar shaped particles as imaged by high resolution atomic force microscopy vitrinite and the grainy textured particles show mesophase structures which can be described as facetted nanocrystals within the carbon matrix high resolution transmission electron microscopy has revealed two types of microtextures representing different degrees of graphitization the first type is characterized by elongated ring shaped microtextures whereas the second type is characterized by graphite lamellae and polygonal flakes with long range ordered aromatic layers in spite of the heterogeneity of the cms the geographical distribution of quantitative metamorphic parameter raman spectra parameter x ray diffraction pattern microscopic reflectance suggests a graphitization process which is promoted by advective heat transport during post collisional processes in a tentative pressure time path late cretaceous thrusting results in a turbostratic ordering of the aromatic layer ordering to long range ordered aromatic layers was achieved during the late cretaceous paleogene exhumation of mid crustal rocks beneath the eastern greywacke zone

oil and gas developments in new zealand and southwest pacific islands in 1983 new zealand had an increase in exploration activity particularly drilling 30 876 m were drilled onshore up 62 and 14 034 m offshore concession holdings slightly increased offshore to 230 665 km2 but dropped to nearly half onshore to 34 353 km2 seismic surveys decreased to 477 5 line km onshore and 1 128 km offshore down 56 and 93 respectively oil gas and condensate were found in several wells on small structures close to the recently discovered mckee field regular production from mckee began in april 1984 at an initial rate of 1 000 bopd production from kapuni and maui fields combined was 2 381 313 106 m3 of gas up 9 4 and 845 286 m3 of condensate down 2 3 construction of a 1 200 mt day methanol plant which uses natural gas from these fields was completed no exploration was carried out in tonga fiji vanuatu and the solomon islands in fiji all prospecting licenses expired but renewal terms on areas reduced by 50 were agreed on in principle papua new guinea had 4 wells drilled to a combined depth of 9 158 m up 23 2 the juha 2x appraisal well confirmed the discovery of gas and condensate in the juha anticline in the gulf of papua the offshore appraisal well pasca a3 blew out and was abandoned the total area of petroleum prospecting licenses slightly increased to 74 715 km2

oil and gas developments in new zealand and southwest pacific islands in 1982 new zealand experienced a marked increase in activity concession holdings went up 205 onshore to 62 429 km2 and 31 offshore to 215 439 km2 seismic coverage more than doubled both onshore and offshore to 1 075 and 15 321 line km respectively several new targets have been delineated offshore and 2 drillships are scheduled to arrive in the country and start drilling during 1983 onshore the total depth drilled more than doubled to 18 993 m drilling was concentrated in the recently discovered mckee field where 2 additional oil producers were completed and on 3 other structures nearby where 1 well tested gas and condensate production of gas and condensate from the kapuni and maui fields combined was 2 177 122 106 m3 up up 69 3 and 865 454 m3 up 57 3 respectively expansion of the only refinery in new zealand and the realization of large petrochemical projects using natural gas are well under way these projects include an ammonia urea plant which was completed by year end a methanol plant and a methanol to synthetic petrol plant now under construction fiji also saw increased exploration activity there were no changes in the license holdings but marine and land seismic surveys covered 242 58 and 42 04 line km respectively four wells were drilled to a total depth of 5 697 m all were dry papua new guinea had active exploration carried out in nearly all of its 11 petroleum prospecting licenses a total of 2 750 line km of marine seismic data was acquired whereas onshore 654 line km were obtained the appraisal well barikewa 2 was drilled to a total depth of 1 820 m and plugged and abandoned in the western highlands 2 wildcat wells were drilled lavani 1 which was dry plugged and abandoned and juha 1 which was drilling ahead at 2 625 m at year end total depth drilled was 7 433 m in the gulf of papua an appraisal well pasca a3 was spudded in january 1983 a reservoir engineering study of the pasca field which is being considered for commercial development has been completed for the papua new guinea government no exploration activities took place in tonga vanuatu or the solomon islands but a ccop sopac sponsored project funded by a tripartite agreement between the governments of australia new zealand and the united states did comprehensive geophysical studies in some offshore areas of these 3 countries

the interplate coupling and stress accumulation process of large earthquakes along the nankai trough southwest japan derived from geodetic and seismic data abstract the interplate coupling and stress accumulation process associated with the subduction of the philippine sea plate beneath the eurasian plate along the nankai trough where large earthquakes have occurred periodically have been investigated in detail taking into account the three dimensional complicated structure of the philippine sea plate and its motion relative to the eurasian plate for this purpose we mainly used extensive geodetic data in southwest japan such as levelling tide gauge and trilateration which presumably are effective means of revealing coupling properties and applied a three dimensional finite element method here two seismic periods associated with the 1944 tonankai and 1946 nankaido earthquakes were considered interseismic and pre seismic stages comparing the coupled regions obtained for the two cases a possible explanation of its temporal change was proposed it might gradually spread from a shallower to deeper portion with transition from the interseismic to pre seismic stage a comparison of the coupling properties between southwest japan and northeast japan reveals the following properties in southwest japan the coupling is generally strong and its region is limited in a relatively shallow portion the pre seismic coupled regions coincide with the co seismic and post seismic fault zone suggesting that the accumulated stress is released at the time of a large earthquake in northeast japan on the other hand the coupling is weak and its extent appears to reach a depth of about 100 km and the co seismic and post seismic regions are limited to the upper half of the coupled region the weakly coupled region in southwest japan seems to correspond well to the region with high seismic activity a high dip angle subducting slab and the possible existence of seamounts in contrast to the strongly coupled region correlated with low seismicity low dip angle subduction and no seamounts on the western coupled region off shikoku an anomalously strongly coupled region corresponding to a convergence rate of 7 8 cm year 1 was identified this may be caused by geomorphological properties such as the low dip angle of the subducting plate and smooth plate boundary resulting in a large amount of stress concentration there the stress field associated with the interplate coupling was also calculated there is fair agreement between the observations and calculations near the plate boundary beneath the southern kii peninsula and shikoku although the effects of the interplate coupling may have some influence on strike slip faulting with the n s compressive axes beneath shikoku other earthquake generating stress such as a two layered double buckling would be dominant there

correlation of very low grade data to calibrate a thermal maturity model in a nappe tectonic setting a case study from the alps abstract vitrinite and bituminite reflectance data xrd studies on clay minerals radiometric data and geochemical data have been used to investigate metamorphism of very low and low grade sediments from the lower austroalpine and south penninic nappes in the oberhalbstein valley central alps numerical maturity modelling methods are calibrated with petrological structural and new geochronological data to reconstruct temperature histories even in nappe tectonic settings the combination of low grade data and maturity modelling shows that the duration of peak temperature metamorphism plays an important role in the alteration of organic matter vitrinite reflectance vr often does not correlate with other low grade parameters but in the oberhalbstein equilibrium between the different parameters is evident because heating near the peak conditions for more than 20 ma took place it is proposed to use the comparison to evaluate equilibrium conditions for the temperature parameters in general in addition from petrological work and vr modelling the pressure conditions are estimated the results yield an eroded overburden of 6 1 km and a temperature gradient of 30 2 c km 1 at the base of the nappe stack pressure conditions of 4 1 kbar are determined and therefore no evidences for a high pressure event the main heating is dated between 90 and 70 5 ma and is attributed to nappe stacking in the upper crust

petroleum potential of southern part of tonga platform abstract the tonga platform is roughly outlined by the 2 000 m isobath with an average width of about 60 to 75 mi 100 to 120 km surrounding the tongan islands of vava u ha apal and tongatapu single channel seismic profiles across the platform were acquired between 1977 and 1979 by scientific expeditions sponsored by ccop sopac committee for cooperation of joint prospecting for mineral resources in south pacific offshore areas and orstom office de la recherche scientific et technique outre mer this survey and a five well drilling program on tongatapu were inspired by the discovery of seeps of weathered crude oil from vuggy coralline limestone reef buildups and normal fault structures are interpreted from seismic data and the wells penetrated miocene and eocene limestone volcanogenic clastics and some reached volcanic basement few oil and gas fields are found in fore arc basins of which the tonga platform is typical but the reefs offer prospects and the seeps suggest that the requirements of source rock and maturation may be satisfied end of article last page 986

temperatures heat flux and frictional stress near major thrust faults we examine the two dimensional advective and conductive transport of heat in a region of thrust faulting both simple theoretical considerations and numerical experiments show that the steady state temperatures near the fault are reduced by a divisor s 1 b z vsin below what they would be with the same heat sources but in the absence of advection in this expression z is the depth to the fault v is the slip rate is the component of the dip of the fault in the direction of underthrusting is thermal diffusivity and b is a dimensionless factor that is essentially equal to one for most forms of heating initial changes in temperatures near the fault are given by t z t t z 0 12vsin t z 0 z these simple formulae are successful because of the neglible influence of lateral conduction of heat at least for slip rates of a few mm yr or more two time constants govern the transition from the initial change in temperature to steady state t1 u v where u is the distance along the fault in the direction of underthrusting from the surface to the depth in question and t2 z 2 2 where z is the depth to the fault when elapsed times exceed the sum of these two time constants temperatures differ from their steady state values by only about 10 percent the numerical experiments indicate that the simple formulae are sufficiently accurate that sophisticiated numerical modeling of temperatures in specific regions is unwarranted putain an application of these simple formulae to measurements of conductive heat flow at island arcs implies that shear stresses at island arcs approach 100 mpa and are greater than 30 mpa calculations of temperatures appropriate for the himalaya suggest that shear stresses of 100 mpa on the main central thrust probably are required to account for the tertiary granites of the region if melting took place after slip began on the thrust similarly the cut off in seismicity at a depth of about 15 km in the himalaya if due to temperatures exceeding 350 to 450 c implies a deviatoric stress close to 100 mpa

significance of late permian triassic facies zones in terrane reconstructions in the alpine north pannonian domain abstract the present day setting of the tectonic units terranes making up the pre neogene basement of the pannonian basin and the west carpathians is the result of large scale displacements during the alpine collisional phases to explain this setting based on various concepts a number of models have been proposed in the last decade most of them agree in an eastward escape of the north pannonian terrane from the alpine domain towards the pannonian during the palaeogene early miocene period in the present paper a reconstruction of the pre escape setting of the displaced terranes is presented based on facies zones in selected time slices from the late permian to the late triassic according to our reconstruction the inner west carpathian units were located east of the austroalpine units forming the northern shelf of the euhallstatt meliatic basin of the vardar oceanic branch the drauzug should have been located in a position much more external than its present day setting the transdanubian range was situated in the northern neighbourhood of the southern alps whereas the bukk may have been located adjacent to the nw dinarides the mid transdanubian zone is a major shear zone containing elements of the julian alps and sava folds nappe system and the inner dinaric ophiolitic melange although the nappe tectonism may have played an important role in the structural evolution of the north pannonian terrane this mechanism alone can hardly produce hundreds of kilometres of facies offset on the opposite sides of strike slip zones

thermal metamorphism in the lesser himalaya of nepal determined from raman spectroscopy of carbonaceous material the determination of metamorphic conditions is critical to the understanding of the formation of mountain belts however all collisional mountain belts contain large volumes of accreted sediments generally lacking metamorphic index minerals and are therefore not amenable to conventional petrologic investigations by contrast these units are often rich in carbonaceous material making it possible to determine thermal metamorphism through raman spectroscopy of carbonaceous material rscm method a technique that has been recently calibrated beyssac et al j metamorph geol 20 2002 859 871 the lesser himalaya lh is one of these problematic cases with a very poor mineralogy but a key structural position within the himalayan system that makes lh considered as diagnostic of the overall thermal behaviour of the orogen this work demonstrates the performance of the rscm technique and shows that this technique might thus be used to detect inter sample variations as small as 10 15 c but absolute temperatures can only be determined to 50 c due to the uncertainty on the calibration this study reveals that the lh has undergone a large scale thermal metamorphism with temperature decreasing progressively from about 540 c at the top to less than 330 c within the deepest exhumed structural levels

thermomechanical consequences of cretaceous continent continent collision in the eastern alps austria insights from two dimensional modeling we use two dimensional numerical modeling techniques to investigate the thermomechanical consequences of closure of the meliata hallstatt ocean and consequent cretaceous continent continent collision in the eastern alps austria in the modeling a lower plate position of the austro alpine aa continental block is adopted during collision with the upper juvavic silice block the thermal structure of the lithosphere was calculated for major aa tectonic units upper middle and lower austro alpine by integration of the transient heat flow equation along an approximately nw se cross section east of the tauern window indications of the rheological evolution of the aa were determined by calculating strength profiles at key stages of the cretaceous orogeny making use of the thermal modeling predictions combined with rock mechanics data cooling in the upper plate and lower greenschist facies metamorphism within footwall parts of the lower upper austro alpine ua plate related to se directed underthrusting of the ua beneath the upper juvavic silice block at circa 100 ma were predicted by the numerical model the observed pressure temperature path for deeply buried middle austro alpine ma upper crustal units and their subsequent isothermal exhumation are best reproduced assuming a pressure peak at 95 ma and exhumation rates ranging between 4 and 7 5 mm yr 1 from the modeling results we deduce that the temperature evolution during eclogite exhumation is primarily dependent on rates of tectonic movements and largely independent of the mode of exhumation thrusting versus erosion furthermore very rapid postmetamorphic exhumation of southern lower austro alpine la units is predicted in order to account for subsequent cooling this is constrained by 40ar 39ar data the cooling paths of ma and la rocks appear to be primarily controlled by their near surface positions at the end of the cretaceous rather than by other processes such as concurrent underthrusting upward advection of heat by rapid exhumation induced thermal weakening of the thickened crust the inferred weakness of the central parts of the orogenic system may play an important role during detachment related tectonic unroofing orogenic collapse and concomitant basin formation central alpine gosau basins

evolution of veins and sub economic ore at strassegg paleozoic of graz eastern alps austria evidence for local fluid transport during metamorphism the north eastern part of the graz paleozoic thrust sheet at strassegg austria is characterised by metamorphic assemblages that reflect increasing temperature conditions from 3008c in hangingwall to around 5508c in footwall units the main quartz andror carbonate vein generation cuts the schistosity at moderate to low angles is folded with the schistosity and is commonly boudinaged there is a correlation between vein and the host rock mineralogy additionally the d 18 o and 13 d c signatures of vein minerals quartz andror carbonates vary systematically with the isotopic signature of the host rock and its minerals within individual units d 18 o of vein quartz has a narrow range of values in contrast with a larger variation in both with d 18 o and d 13 c of carbonates at strassegg the greenschist unit hosts an as au mineralisation arsenopyrite

thermal history of the carnic alps southern alps austria and its palaeogeographic implications abstract the thermal history of the carnic alps southern alps austria has been investigated by means of organic petrology clay mineralogy and microthermometry in the tectonic framework of the carnic alps the metamorphic overprint from the lower anchizone up to the epizone is exposed in a continuous n s trending metamorphic section the metamorphic zonation is disturbed by shear zones related to the strike slip movement of the periadriatic lineament all obtained data a methodical correlation and a numeric 1d simulation of the burial history result in the model of a multistage thermal history 1 a variscan tectonothermal event caused a syntectonic anchi to epizonal metamorphism with the development of local overpressured zones characterized by convective heat transfer 2 major strike slip faults operating during the sedimentation of the late carboniferous molasse are related to enhance the heat flow 3 the alpine metamorphic overprint shows the same intensity as the variscan event 4 high temperature fluid inclusion phases are related to oligocene plutonic activity along the periadriatic lineament these data from the carnic alps are discussed in a general framework of the non to low grade metamorphic units of the internal alps and carpathians in the uppermost tectonic units of the eastern and southern alps a spatial and temporal shift of the alpine very low grade metamorphic overprint from north to south is observed this zonation indicates the pannonian transdanubian range which suffered no alpine metamorphism as an exotic block inside an alpine heated domain the gailtal line as a segment of the periadriatic lineament separates two terrains with the same alpine overprint

coupling of tectonic loading and earthquake fault slips at subduction zones because of the viscoelastic behaviour of the earth accumulation of elastic strain energy by tectonic loading and release of such energy by earthquake fault slips at subduction zones may take place on different spatial scales if the lithospheric plate is acted upon by distant tectonic forces strain accumulation must occur in a broad region however an earthquake releases strain only in a region comparable to the size of the rupture area a two dimensional finite element model of a subduction zone with viscoelastic rheology has been used to investigate the coupling of tectonic loading and earthquake fault slips a fault lock and unlock technique is employed so that the amount of fault slip in an earthquake is not prescribed but determined by the accumulated stress the amount of earthquake fault slip as a fraction of the total relative plate motion depends on the relative sizes of the earthquake rupture area and the region of tectonic strain accumulation as well as the rheology of the rock material the larger the region of strain accumulation is compared to the earthquake rupture the smaller is the earthquake fault slip the reason for the limited earthquake fault slip is that the elastic shear stress in the asthenosphere induced by the earthquake resists the elastic rebound of the overlying plate since rapid permanent plate shortening is not observed at subduction zones there must be either strain release over a large region or strain accumulation over a small region over earthquake cycles the former can be achieved only by significant aseismic fault slip between large subduction earthquakes the most likely mechanism for the latter is the accumulation of elastic strain around isolated locked asperities of the fault which requires significant aseismic fault slip between asperities

southwest pacific island arcs sedimentary basins and petroleum prospects in new hebrides and solomons abstract several thousand meters of miocene pliocene sediments are predominantly fine to coarse grained volcaniclastics deposited in shelf to deep marine environments commonly as turbidites coralgal reef limestones and fore reef calcarenites formed locally original basins in both the solomons and new hebrides measured 375 to 435 mi 600 to 700 km by 62 to 125 mi 100 to 200 km but parts of their margins are strongly deformed uplifted and eroded cross faulting and holocene volcanism caused segmentation and further reduction of basinal areas in both island arcs the sediments are little deformed along a median structural basin which was downfaulted in pleistocene to recent time in the solomons and from pliocene onward in the central new hebrides no downfaulting occurred i the northern new hebrides little is known of hydrocarbon source potential and degree of maturation back reef or rapidly buried fore reef environments may be the principal areas for source rock formation reefal limestones are the main potential reservoir rocks they have however lost porosity locally because of recrystallization turbidite sandstones may form additional reservoirs but volcanic derivation keeps permeability generally low the main structural traps are fault controlled near basin margins but limited folding also occurs the pre pliocene unconformity in the northern new hebrides could generate stratigraphic traps water depth in the main prospective areas is several hundred to 5 000 ft 1 500 m in the solomons and up to 10 000 ft 3 000 m in the new hebrides nearshore and onland prospect are extremely limited in both island arcs end of article last page 972

age resetting of hanging wall rocks above a low angle detachment fault tinos island aegean sea the central aegean region has been affected by extensional tectonics since at least the oligo miocene on tinos island cyclades greece a low angle normal fault places low grade metamorphic rocks the upper unit above high pressure rocks the cycladic blueschist unit k ar and 40ar 39ar ages were obtained by us on white micas amphiboles and whole rock samples separated from various metamorphic rocks representing different structural levels of the hanging wall the hanging wall upper unit is commonly thought to have resided at shallow crustal levels since late cretaceous times but our geochronological data supported by previously published rb sr dating brocker m franz l 1998 rb sr isotope studies on tinos island cyclades greece additional time constraints for metamorphism extent of infiltration controlled overprinting and deformational activity geol mag 135 3 369 382 indicate severe age resetting of the base of the hanging wall during tertiary times amphiboles from the top of the hanging wall section yielded late cretaceous ages which correlate well with other cretaceous upper unit rocks in the cyclades their preservation implies that tertiary age resetting was mainly confined to the lower part of the upper unit while upper parts retained older ages the base of the hanging wall section where age resetting and ductile deformation are most pronounced is taken to represent a part of a thick extensional shear zone that operated in low greenschist facies conditions during tertiary time the results of one dimensional thermal modeling suggest that warm footwall rocks emerging from great depth subsequently to hp lt metamorphism may have supplied the heat required for the metamorphism and ductile deformation at the base of the hanging wall the model also indicates that only minor cooling of the footwall during decompression is allowed if the footwall is to warm up the hanging wall this is a priori consistent with the isothermal decompression path of footwall blueschists and eclogites deduced from previous petrological studies on tinos