seismic imaging of the scandinavian caledonides to define icdp drilling sites abstract a 36 kilometer long high resolution 2d seismic reflection profile was acquired in the summer of 2010 to be used in the planning of the cosc collisional orogeny in the scandinavian caledonides deep drilling project two fully cored boreholes each to c 2 5 km depth are planned for the are morsil area of west central sweden in order to increase our understanding of orogenic processes and in particular the tectonic evolution of the scandinavian caledonides besides providing important sub surface structural information in the vicinity of the potential drill sites the seismic profile also provides detailed high resolution images previously not available for the uppermost few kilometers in the region the subsurface is highly reflective and very complex down to at least 9 km depth the limit of decoded data with clear reflections spanning the entire length of the profile correlation with previous regional reflection seismic and magnetotelluric surveys has been achieved by acquisition of a short 7 km connecting profile a clearly defined reflection present in the new profile at depths between c 2 5 km in the east and c 4 5 km in the west and with an average westwards dip of c 3 5 apparently defines the base of the lower allochthon closer to the caledonian front this sole thrust overlies the cambrian alum shale formation which rests unconformably on the autochthonous precambrian crystalline basement the latter is remarkable for its deep internal reflectivity which is probably related to mafic intrusions in a dominantly granitic host rock their deformation may be of both caledonian and older e g sveconorwegian age the new high resolution seismic data provide the basis for locating the first borehole in the seve nappe complex they also demonstrate that the second hole designed to penetrate the caledonian basement will have to be located further east than was originally planned

climate records covering the last deglaciation the oxygen 18 oxygen 16 ratio of molecular oxygen trapped in ice cores provides a time stratigraphic marker for transferring the absolute chronology for the greenland ice sheet project gisp ii ice core to the vostok and byrd ice cores in antarctica comparison of the climate records from these cores suggests that near the beginning of the last deglaciation warming in antarctica began approximately 3000 years before the onset of the warm bolling period in greenland atmospheric carbon dioxide and methane concentrations began to rise 2000 to 3000 years before the warming began in greenland and must have contributed to deglaciation and warming of temperate and boreal regions in the northern hemisphere

3d constraints and finite difference modeling of massive sulfide deposits the kristineberg seismic lines revisited northern sweden the kristineberg mining area in the western part of the skellefte ore district is the largest base metal producer in northern sweden and currently the subject of extensive geophysical and geologic

rapid changes of glacial climate simulated in a coupled climate model abrupt changes in climate termed dansgaard oeschger and heinrich events have punctuated the last glacial period approximately 100 10 kyr ago but not the holocene the past 10 kyr here we use an intermediate complexity climate model to investigate the stability of glacial climate and we find that only one mode of atlantic ocean circulation is stable a cold mode with deep water formation in the atlantic ocean south of iceland however a warm circulation mode similar to the present day atlantic ocean is only marginally unstable and temporary transitions to this warm mode can easily be triggered this leads to abrupt warm events in the model which share many characteristics of the observed dansgaard oeschger events for a large freshwater input such as a large release of icebergs the model s deep water formation is temporarily switched off causing no strong cooling in greenland but warming in antarctica as is observed for heinrich events our stability analysis provides an explanation why glacial climate is much more variable than holocene climate

a new 27 ky high resolution east antarctic climate record the ice core recently drilled at the dome concordia site on the east antarctic plateau provides a new high resolution isotope record covering part of the last glacial the last transition and the holocene the two step shape of the deglaciation is remarkably similar for all the ice cores now available on the east antarctic plateau the first warming trend ends about 14000 years ago and is followed by the well marked antarctic cold reversal acr with a secondary peak common to all records during the deglaciation there are more similarities between the near coastal site of taylor dome and inland east antarctica than between taylor dome and central greenland however the results for epica do appear to confirm the taylor dome timescale after about 14 ka showing cooling into the acr roughly in phase between greenland and antarctica while the overall deglacial pattern is asynchronous this suggests that the now classical picture of a temperature seesaw between antarctica and greenland may be too simplistic

comparison of surface seismic sources at the co2sink site ketzin germany 3d seismic time lapse surveys 4d seismics are an essential tool for large scale reservoir characterization the target reservoir of the ketzin pilot project for co2 storage is a saline aquifer of the heterogeneous stuttgart formation upper triassic in the northeast german basin the focus of this project is on testing and further developing monitoring co2 storage technologies for time lapse seismic monitoring three seismic surface sources were characterized with respect to s n signal to noise ratios signal penetration and frequency content by analysis of raw shot gathers and stacked sections along two lines at the ketzin site differences in reflectivity between these 2d lines reflect the differences in the nature of the sources tested and how they influence the signal bandwidth resolution and signal energy all three sources image the target horizon the weight drop source was recommended as the primary source for 3d surveys based mainly on logistics and cost results of processing including equalization of a 4d 3d time lapse data set from the ketzin site and cross correlation indicate that the injected co2 can be monitored the highly irregular amplitude response on the time lapse data can be attributed to the reservoir heterogeneity time lapse seismic processing petrophysical measurements on core samples and geophysical logging of co2 saturation levels allow for an estimate of the total amount of co2 visible in the seismic data to be made in spite of some uncertainty the close agreement between the injected and observed amount is encouraging for quantitative monitoring of a co2 storage site using seismic methods by integrating seismic modeling and multiphase fluid flow simulations the impact of the reservoir temperature on the 4d seismic data from ketzin was estimated the modeled time lapse seismic differences for two temperature scenarios present in the reservoir are minor regarding the qualitative analysis however the influence of temperature on the volumetric estimation of the co2 using the 4d seismic data is significant future issues to be considered include expanding the temperature range 34 38 c in this study to be investigated and the resulting effects on the seismic response as well as the role of the reservoir heterogeneity in addition it would be important to investigate the impact of temperature on the co2 storage at other sites with favorable p t conditions in the reservoir further seismic modeling using results of petrophysical experiments for estimating the effect of the co2 injection at the ketzin site on the ava avo response on time lapse seismic data was performed two effects were considered the co2 saturation and the pore pressure related effects the results indicate that it is worth investigating if it is possible to discriminate between these effects on future 3d repeat surveys at the ketzin site

high resolution quantitative seismic imaging of a strike slip fault with small vertical offset in clay rocks from underground galleries experimental platform of tournemire france imaging tectonic faults with small vertical offsets in argilittes clay rock using geophysical methods is challenging in the context of deep radioactive waste disposals the presence of such faults has to be assessed since they can modify the rock confining properties in the tournemire experimental platform tep france fault zones with small vertical offsets and complex shape have been identified from underground works however 3d high resolution surface seismic methods have shown limitations in this context that led us to consider the detection and characterization of the faults directly from underground works we investigate here the potential of seismic full waveform inversion fwi applied in a transmission configuration to image the clay rock medium in a horizontal plane between galleries and compare it with first arrival traveltime tomography fatt our objective is to characterize seismic velocities of a block of argilittes crossed by a subvertical fault zone with a small vertical offset the specific measurement configuration allows us to neglect the influence of the galleries on the wave propagation and to simplify the problem by considering a 2d isotropic horizontal imaging domain our fwi scheme relies on a robust adaptation of early arrival waveform tomography the results obtained with fatt and fwi are in accordance and both correlate with the geological observations from the gallery walls and boreholes we show that even though various simplifications are done in the inversion scheme and only a part of the data is used fwi allows to get higher resolution images than fatt and is especially less sensitive to the incomplete illumination as it uses also diffracted energy the results provided in this study highlight the complexity of the fault zone showing a complex interaction of the main fault system with a secondary system composed of decimetric fractures associated with the presence of water

the two step shape and timing of the last deglaciation in antarctica the two step character of the last deglaciation is well recognized in western europe in greenland and in the north atlantic for example in greenland a gradual temperature decrease started at the bolling b around 14 5 ky bp spanned through the allerod a and was followed by the cold younger dryas yd event which terminated abruptly around 11 5 ky bp recent results suggest that this ba yd sequence may have extended throughout all the northern hemisphere but the evidence of a late transition cooling is still poor for the southern hemisphere here we present a detailed isotopic record analyzed in a new ice core drilled at dome b in east antarctica that fully demonstrates the existence of an antarctic cold reversal acr these results suggest that the two step shape of the last deglaciation has a worldwide character but they also point to noticeable interhemispheric differences thus the coldest part of the acr which shows a temperature drop about three times weaker than that recorded during the yd in greenland may have preceded the yd antarctica did not experienced abrupt changes and the two warming periods started there before they started in greenland the links between southern and northern hemisphere climates throughout this period are discussed in the light of additional information derived from the antarctic dust record

3d seismic survey at the millennium uranium deposit saskatchewan canada mapping depth to basement and imaging post athabasca structure near the orebody three dimensional seismic reflection measurements have been used to assist mine planning at the millennium uranium deposit canada the deposit is located within the crystalline basement separated

high resolution reflection seismic imaging of the ullared deformation zone southern sweden the ullared deformation zone udz is one of a few structures worldwide known to contain decompressed eclogite facies rocks of precambrian age given the unique nature of the ullared eclogites a 1

the taylor dome antarctic 18o record and globally synchronous changes in climate abstract the 18 o 16 o profile of a 554 m long ice core through taylor dome antarctica shows the climate variability of the last glacial interglacial cycle in detail and extends at least another full cycle taylor dome shares the main features of the vostok record including the early climatic optimum with later cool phase of the last interglacial period in antarctica taylor dome 18 o fluctuations are more abrupt and larger than those at vostok and byrd station although still less pronounced than those of the greenland gisp2 and grip records the influence of the atlantic thermohaline circulation on regional ocean heat transport explains the partly north atlantic character of this antarctic record under full glacial climate marine isotope stage 4 late stage 3 and stage 2 this marine influence diminished and taylor dome became more like vostok varying degrees of marine influence produce climate heterogeneity within antarctica which may account for conflicting evidence regarding the relative phasing of northern and southern hemisphere climate change

comparison of high frequency seismic sources at the grimsel test site central alps switzerland in august 1995 various high frequency seismic sources were tested at the grimsel test site gts located inside a crystalline rock body in the central swiss alps these source tests were designed to facilitate future tomographic studies of potential radioactive waste disposal sites the principal objective was to identify borehole and tunnel seismic sources capable of generating powerful high frequency signals such that frequencies up to 1000 hz can be observed over distances of 1000 m in crystalline or consolidated sedimentary rocks seismic sources were situated in water filled boreholes sparker two piezoelectric sources explosives and at or near the tunnel wall accelerated weight drop minivibrator bolt gun buffalo gun explosives to evaluate and compare the source characteristics the direct p wave generated by the various seismic sources was investigated for the decay of its s n and dominant frequency with offset and for the maximum distance at which first arrivals could be picked of the

evolution of stable internal boundary layers over a cold sea the situation studied in this paper relates to air flow from a heated land surface out over a water surface with much lower temperature observations from the baltic sea where this kind of situati

why 3d seismic data are an asset for exploration and mine planning velocity tomography of weakness zones in the kevitsa ni cu pge mine northern finland kevitsa is a disseminated ni cu pge platinum group elements ore body in northern finland hosted by an extremely high velocity 6 5 8 5 km s ultramafic intrusion it is currently being mined at

3d baseline seismics at ketzin germany the co2sink project a 3d 25 fold seismic survey with a bin size of 12 by 12 m and about 12 km 2 of subsurface coverage was acquired in 2005 near a former natural gas storage site west of berlin as part of the fiv

timing is everything in a game of two hemispheres what causes ice ages and other episodes of violent climate change one clue comes from a new study of ice cores which unexpectedly seems to show rapid warming events happening first in the southern hemisphere

sudden changes in north atlantic circulation during the last deglaciation sudden changes in the flow of warm atlantic surface waters into the norwegian sea occurred frequently during the last deglaciation typically involving shifts in sea surface temperature of 5 c in fewer than 40 years these led to equally large and rapid changes in atmospheric temperatures and to shifts in atlantic deep thermo haline circulation and ice sheet melting rates

characterization of fractured rock in the vicinity of tunnels by the swept impact seismic technique the diversity of the applications of high resolution seismics requires investigations in the range of hundreds of meters to be performed in very diverse conditions we found the swept impact seismic technique sist to be a viable solution for high resolution surveys in hard rocks sist combines the vibroseis swept frequency and the mini sosie multiimpact ideas several variations of the method have been studied leading to improved resolution and efficiency the development was partly funded by the finnish center for technical development tekes and partly by the french national agency for the management of radioactive waste andra a test programme was carried out at the grimsel test site gts operated by nagra the swiss national cooperative for the disposal of radioactive waste measurements were also carried out with single pulse sources but data of acceptable quality could not be obtained surface and tunnel wall as well borehole sist sources have been developed and tested the ability of the seismic techniques to detect and characterize rock discontinuities was proven by investigating a rock block delimited by two parallel boreholes and a tunnel perpendicular to them involving source detector distances of 100 200m the characterization included the determination of the 3 d positions and orientations of rock features and the tomographic mapping of seismic velocities

crustal geometry of the central skellefte district northern sweden constraints from reflection seismic investigations abstract the palaeoproterozoic skellefte mining district in sweden is one of the most important mining districts in europe as a part of a 4d geologic modeling project three new sub parallel reflection seismic profiles with a total length of about 95 km were acquired in the central part of the district processed seismic data reveal a series of gentle to steeply dipping reflections and a series of diffraction packages the majority of reflections that extend to the surface can be correlated with geological features either observed in the field or interpreted from the aeromagnetic map a set of south dipping reflections represent inferred syn extensional listric extensional faults that were inverted during subsequent crustal shortening cross cutting north dipping reflections are correlated to late compressional break back faults flat lying reflections in the central parts of the study area could represent lithological contacts within the skellefte group or the contact between skellefte group rocks and their unknown basement flat lying reflections occurring further north are inferred to originate from the top of the jorn intrusive complex or an intrusive contact within it so far unknown south and north dipping faults have been identified in the vicinity of the maurliden deposit based on the seismic results a preliminary 3d model has been created in order to visualize the fault pattern and to provide a base for future 3d 4d modeling in the skellefte district

phase relationships between antarctic and greenland climate records comparison of climate records from antarctic and greenland ice cores shows that the two regions respond asynchronously during millennial scale climate changes the apparent out of phase relationship between the records has been described as a climate seesaw in which cooling in the northern hemisphere is balanced by warming in the southern hemisphere the same relationship has also been attributed to the initiation of climate change events in the southern hemisphere rather than the north atlantic as is conventionally assumed a simple statistical approach band pass filtering combined with lag correlation tests used to examine the phase relationships in more detail shows that neither an anti phase nor a phase lag relationship adequately describes the observations whereas antarctic and greenland climate records do exhibit approximate anti phase behavior about 50 of the time they are generally in phase during cooling a phase lead of southern hemisphere climate of 1000 1600 years is statistically indistinguishable from a lag of 400 800 years whether for dansgaard oeschger heinrich or longer duration events the seesaw or southern lead appearance of the data arises from the fundamentally different characteristics of the climate time series most importantly the absence of rapid warming events in antarctica comparable to those in greenland to be consistent with the observations climate models will need to capture these characteristics in addition to reproducing the correct phase relationships

3d reflection seismic imaging at the 2 5 km deep cosc 1 scientific borehole central scandinavian caledonides the 2 5 km deep scientific cosc 1 borehole icdp 5054 1 a was successfully drilled with nearly complete core recovery during spring and summer of 2014 downhole and on core measurements through th

multidisciplinary study of the hanging wall of the kiirunavaara iron ore deposit northern sweden potential weakness zones due to mining related fracture development under the town of kiruna sweden have been investigated by integration of seismic gravity and petrophysical data reflection s

the derivation of an anisotropic velocity model from a combined surface and borehole seismic survey in crystalline environment at the cosc 1 borehole central sweden the scandinavian caledonides provide a well preserved example of a palaeozoic continent continent collision where surface geology in combination with geophysical data provides information about th

cross well seismic waveform tomography for monitoring co2 injection a case study from the ketzin site germany seismic full waveform inversion waveform tomography is a method to reconstruct the underground velocity field in high resolution using seismic data the method was first introduced during the 1980 s and became computationally feasible during the late 1990 s when the method was implemented in the frequency domain this work presents three case studies and one synthetic benchmark of full waveform inversion applications two of the case studies are focused on time lapse cross well and 2d reflection seismic data sets acquired at the ketzin co2 geological storage site these studies are parts of the co2sink and co2man projects the results show that waveform tomography is more effective than traveltime tomography for the co2 injection monitoring at the ketzin site for the cross well geometry for the surface data sets we find it is difficult to recover the true value of the velocity anomaly due to the injection using the waveform inversion method but it is possible to qualitatively locate the distribution of the injected co2 the results agree well with expectations based upon conventional 2d cdp processing methods and more extensive 3d cdp processing methods in the area a further investigation was done to study the feasibility and efficiency of seismic full waveform inversion for time lapse monitoring of onshore co2 geological storage sites using a reflection seismic geometry with synthetic data sets the results show that waveform inversion may be a good complement to standard cdp processing when monitoring co2 injection the choice of method and strategy for waveform inversion is quite dependent on the goals of the time lapse monitoring of the co2 injection the last case study is an application of the full waveform inversion method to two crooked profiles at the forsmark site in eastern central sweden the main goal of this study was to help determine if the observed reflections are mainly due to fluid filled fracture zones or mafic sills one main difficulty here is that the profiles have a crooked line geometry which corresponds to 3d seismic geometry but a 2d based inversion method is being used this is partly handled by a 3d to 2d coordinate projection method from traveltime inversion the results show that these reflections are primarily due to zones of lower velocity consistent with them being generated at water filled fracture zones

mt and reflection seismics in northwestern skellefte ore district sweden a seismic reflection and mt survey was carried out along a 27 km long transect in northwestern skellefte district as part of a bigger 3d modeling project the main motivation for the data acquisit

changes in east atlantic deepwater circulation over the last 30 000 years eight time slice reconstructions using 95 epibenthic 13c records eight time slices were reconstructed to trace the distribution of east atlantic deepwater and intermediate water masses over the last 30 000 years our results show that there have been three distinct modes of deepwater circulation near the stage 3 2 boundary the origin of north atlantic deep water nadw was similar to today mode 1 however after late stage 3 the source region of the nadw end member shifted from the norwegian greenland sea to areas south of iceland mode 2 a reduced nadw flow persisted during the last glacial maximum with constant preformed 13c values the nutrient content of nadw increased markedly near the azores fracture zone from north to south probably because of the mixing of upwelled antarctic bottom water aabw from below which then advected with much higher flux rates into the northeast atlantic later the spread of glacial meltwater over the north atlantic led to a marked short term ventilation minimum below 1800 m about 13 500 14c years ago mode 3 the formation of nadw recommenced abruptly north of iceland 12 800 12 500 years ago and reached a volume approaching that of the holocene in the younger dryas 10 800 10 350 years b p another short term shutdown of deepwater formation followed between 10 200 and 9 600 years b p linked to a further major meltwater pulse into the atlantic each renewal of deepwater formation led to a marked release of fossil co2 from the ocean the likely cause of the contemporaneous 14c plateaus over the last 9000 years deepwater circulation varied little from today apart from a slight increase in aabw about 7000 14c years ago it is also shown that the oxygenated mediterranean outflow varied largely independent of the variations in deepwater circulation over the last 30 000 years

anisotropic kirchhoff pre stack depth migration at the cosc 1 borehole central sweden a remarkably well preserved representation of a deeply eroded palaeozoic orogen is found in the scandinavian caledonides formed by the collision of the two palaeocontinents baltica and laurentia

subtropical north atlantic temperatures 60 000 to 30 000 years ago a reconstruction of sea surface temperature based on alkenone unsaturation ratios in sediments of the bermuda rise provides a detailed record of subtropical climate from 60 000 to 30 000 years ago northern sargasso sea temperatures changed repeatedly by 2 to 5 c covarying with high latitude temperatures that were previously inferred from greenland ice cores the largest temperature increases were comparable in magnitude to the full glacial holocene warming at the site abrupt cold reversals of 3 to 5 c lasting less than 250 years occurred during the onset of two such events greenland interstadials 8 and 12 suggesting that the largest most rapid warmings were especially unstable

application of modern 2 d and 3 d seismic reflection techniques for uranium exploration in the athabasca basinthis article is one of a series of papers published in this special issue on the theme lithoprobe parameters processes and the evolution of a continent seismic reflection techniques have been applied in several studies over the last 20 years as a uranium exploration tool within the athabasca basin and have been utilized to provide the larger structural context for known uranium deposits within the basin at the crustal scale deposits within the eastern athabasca basin are shown to be associated with deep seated shear zones that originated during trans hudson orogeny and have subsequently been reactivated during and subsequent to deposition of the basin fill sandstones seismic properties of the athabasca sandstones and underlying basement have been determined through in situ borehole measurements reflectivity within the sandstones is generally weak seismically recognizable signatures are primarily associated with variations in fracture density porosity and degree of silicification the basement unconformity and regolith a prime target of exploration is widely imaged as it is characterized by variable but generally distinct reflectivity results fr