Core-log-seismic integration in metamorphic rocks and its implication for the regional geology: A case study for the ICDP drilling project COSC-1, Sweden

Continental collision causes deformation in the crust along shear zones. However, the physical and chemical conditions at which these zones operate and the deformation processes that enable up to hundreds of km of tectonic transport are still unclear because of the depth at which they occur and the challenges in imaging them. Ancient exhumed collision zones allow us to investigate these processes much better, for example at the COSC‐1 borehole in the central Scandinavian Caledonides. This study combines data from the COSC‐1 borehole with different seismic measurements to provide constraints on the spatial lithological and textural configuration of the Seve Nappe Complex. This is one of the few studies that shows that core‐log‐seismic integration in metamorphic rocks allows to identify the spatial distribution of major lithological units. Especially gamma ray logs in combination with density data are powerful tools to distinguish between mafic and felsic lithologies in log‐core correlation. Our results indicate that reflections along the borehole are primarily caused by compositional rather than textural changes. Reflections in the Seve Nappe Complex are not as distinct as in greater depths but continuous and several of them can be linked to magmatic intrusions, which have been metamorphically overprinted. Their setting indicates that the Seve Nappe Complex consists of the remnants of a volcanic continental margin. Our results suggest that ductile‐deformed middle crustal reflectivity is primarily a function of pre‐orogenic lithological variations which has to be considered when deciphering mountain building processes

Brittle basement deformation during the Caledonian Orogeny observed by K‐Ar geochronology of illite‐bearing fault gouge in west‐central Sweden

This study presents K-Ar ages of illite from fault gouges in crystalline basement in centralwestern Sweden. Samples were taken from two faults that localized brittle deformation marginal to and within mafic dikes that intruded Paleoproterozoic granitoids. K-Ar ages from ten separated grain fractions span from 823 to 392 Ma. Older ages obtained (823 to 477 Ma) were influenced by a mixture of illite and K-feldspar; the latter likely formed during a hydrothermal event prior to faulting. The remaining ages (442.1±9.7 to 391.7±6.1 Ma) were obtained from fractions from both faults hosting only authigenic illite, and show that illite crystallized during the Scandian Caledonian orogeny. These results indicate that previously presumed autochthonous Caledonian basement was involved in continental contraction and subsequent collapse of the Caledonian orogen, influencing both the mode and depth of penetration of deformation into Baltica

Preface: Interdisciplinary contributions from the Division on Energy, Resources and the Environment at the EGU General Assembly 2019

Since 2004, the European Geosciences Union (EGU) brings together experts from all over the world at its annual General Assembly, covering all disciplines of the earth, planetary and space sciences. With this special issue in Advances in Geosciences, we are pleased to present a collection of contributions from the Division on Energy, Resources and the Environment (ERE) which were presented at the EGU General Assembly 2019 in Vienna

Emplacement and 3D geometry of crustal-scale saucer-shaped intrusions in the Fennoscandian Shield

Saucer-shaped intrusions of tens of meters to tens of kilometres across have been observed both from surface geological mapping and geophysical observations. However, there is only one location where they have been reported to extend c. 100 km laterally, and emplaced both in a sedimentary basin and the crystalline basement down to 12 km depth. The legacy BABEL offshore seismic data, acquired over the central Fennoscandian Shield in 1989, have been recovered and reprocessed with the main goal of focusing on this series of globally unique crustal-scale saucer-shaped intrusions present onshore and offshore below the Bothnian Sea. The intrusions (c. 1.25 Ga), emplaced in an extensional setting, are observed within both sedimentary rocks (1.5 Ga). They have oval shapes with diameters ranging 30-100 km. The reprocessed seismic data provide evidence of up-doming of the lower crust (representing the melt reservoir) below the intrusions that, in turn, are observed at different depths in addition to a steep seismically transparent zone interpreted to be a discordant feeder dyke system. Relative age constraints and correlation with onshore saucer-shaped intrusions of different size suggest that they are internally connected and fed by each other from deeper to shallower levels. We argue for a nested emplacement mechanism and against a controlling role by the overlying sedimentary basin as the saucer-shaped intrusions are emplaced in both the sedimentary rocks as well as in the underlying crystalline basement. The interplay between magma pressure and overburden pressure, as well as the, at the time, ambient stress regime, are responsible for their extensive extent and rather constant thicknesses (c. 100-300 m). Saucer-shaped intrusions may therefore be present elsewhere in the crystalline basement to the same extent as observed in this study some of which are a significant source of raw materials.Peer reviewe

Reflexionsseismiska mätningar över Burträsk-förkastningen: Migrated cross-dip stack

In 2008, a 22 km long high resolution reflection seismic profile was acquired over the Burträsk fault in Northern Sweden. The Burträsk fault formed at the end of the last glacial, triggered by the rapid melting of the Scandinavian ice sheet and the following crustal rebound. The aim of the survey was to image the structure of the fault with depth. The profile followed existing roads resulting in a very crooked acquisition geometry. A list of the key acquisition parameters is given below. The dataset was first processed and published in 2011. In 2018, the dataset was reprocessed using an additional cross-dip correction step to improve the imaging of reflection with a dip component in the cross-profile direction. The following data files are available for downloading: 1) raw shot gathers (decoded and quality controlled, with geometry information in the headers) 2) original stacked section from Juhlin and Lund (2011) 3) cross-dip corrected stacked section from Beckel and Juhlin (2019) 4) cross-dip corrected migrated section from Beckel and Juhlin (2019) A short summary of the main processing steps for each dataset is given below. For a complete description, please refer to the above mentioned publications. Key acquisition parameters: Number of channels: 280 Near offset: 0 m Geophone spacing: 20 m Geophone type : 28 Hz single Nominal source spacing : 20 m Source type : VIBSIST Hit interval between hammer blows : 100-200 ms Sweeps per source point :3-4 Nominal fold : 140 Recording instrument : SERCEL 408L Sample rate : 1ms Field low cut : Out Field high cut : 400 Hz Record length : 23 s Profile length : 22 km Source points : 799 Dates acquired: 2008/08/05-2008/08/16 Short summary of the main processing steps: 1) BUR_shots_geom.sgy The raw shot records are pre-processed with VIBSIST decoding, quality control. Information about the shot and receiver geometry has been added to the trace headers. 2) BUR_original_stack.sgy The processing flow of the original data stack includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering (for a complete description see Juhlin & Lund, 2011) 3) BUR_crossdip_stack.sgy The main processing steps of the crossdip stack are very similar to those of the original stack, including trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering. Before DMO correction, an additional cross-dip correction step has been added. For a complete description see Beckel & Juhlin, 2019. 4) BUR_crossdip_mig.sgy The processing flow of the migrated section includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, cross-dip correction, DMO correction, stacking, coherency filtering and migration (for a complete description see Beckel & Juhlin, 2019). This dataset contains the migrated and depth converted crossdip stack of the Burträsk profile (Beckel & Juhlin, 2019). Processing steps for this data set: 1. Read decoded VIBSIST data 2. Bulk static shift to zero time 3. Apply geometry 4. Manual first-break picking 5. Trace balance: 0–3000 ms 6. Ground-roll and first-break muting in local time– frequency domain: 25 % threshold 7. Spectral equalization: 30 Hz window, 25–40–120–150 Hz bandpass 8. Time-variant bandpass filtering: 0–200 ms: 35–60–120–180 Hz 250–500 ms: 30–50–120–180 Hz 600–900 ms: 25–40–110–165 Hz 1100–3000 ms: 20–35–100–150 Hz 9. Refraction statics: floating datum, replacement velocity from model 10. Trace editing 11. Horizontal median filter: 11 traces, 5300 m s-1 and 3000 m s-1 12. Butterworth filter: 20–40–90–120 Hz 13. Spherical divergence correction: 0.8 tpower, 2.0 vpower 14. Velocity analysis 15. NMO correction: 40 % stretch mute 16. Residual statics 17. Cross-dip correction: 5400 m s-1 , 20 % taper; Velocity analysis 18. DMO correction; Velocity analysis 19. Stacking 20. FX deconvolution: 19 trace window 21. Trace balance 22. Stolt migration: 5400 m s-1 , 0.6 stretch factor 23. Zero mute 24. Approximate depth conversion: 5400 m s-1 Processed seismic data stored as one file for the entire seismic profile, according to SEG technical standard SEG-Y revision 1 (SEG-Y_r1.0, 2002); https://seg.org/Publications/SEG-Technical-StandardsReflexionsseismiska mätningar över Burträsk-förkastningen I norra Sverige År 2008 gjordes en reflexionsseismiska undersökning över Burträsk-förkastningen I norra Sverige. Förkastningen formades vid slutet av sista istiden när glaciärerna nedsmältade snabbt. Ändamålen av undersökningen var att avbilda förkastningens djupa strukturerna. Seismisk profilen följde befintliga vägar, vilket resulterade I en ganska slingrig geometri av profilen. Datasetet bearbetades och publicerades först av Juhlin & Lund (2011). I 2018 gjordes ett nytt bearbetning av som omfattade en ytterligare steg för att korrigera effekten av 3D profilgeometrin (Beckel & Juhlin, 2019). En mer detaljerad beskrivning av datasetet som inkluderar alla viktiga parametrar är tillgängligt på den engelska katalogsidan:https://snd.gu.se/en/catalogue/study/SND1099 Utförlig beskrivning av datasetet finns på den engelska katalogsidan: https://snd.gu.se/en/catalogue/study/SND109

Reflexionsseismiska mätningar över Burträsk-förkastningen: Cross-dip stack

In 2008, a 22 km long high resolution reflection seismic profile was acquired over the Burträsk fault in Northern Sweden. The Burträsk fault formed at the end of the last glacial, triggered by the rapid melting of the Scandinavian ice sheet and the following crustal rebound. The aim of the survey was to image the structure of the fault with depth. The profile followed existing roads resulting in a very crooked acquisition geometry. A list of the key acquisition parameters is given below. The dataset was first processed and published in 2011. In 2018, the dataset was reprocessed using an additional cross-dip correction step to improve the imaging of reflection with a dip component in the cross-profile direction. The following data files are available for downloading: 1) raw shot gathers (decoded and quality controlled, with geometry information in the headers) 2) original stacked section from Juhlin and Lund (2011) 3) cross-dip corrected stacked section from Beckel and Juhlin (2019) 4) cross-dip corrected migrated section from Beckel and Juhlin (2019) A short summary of the main processing steps for each dataset is given below. For a complete description, please refer to the above mentioned publications. Key acquisition parameters: Number of channels: 280 Near offset: 0 m Geophone spacing: 20 m Geophone type : 28 Hz single Nominal source spacing : 20 m Source type : VIBSIST Hit interval between hammer blows : 100-200 ms Sweeps per source point :3-4 Nominal fold : 140 Recording instrument : SERCEL 408L Sample rate : 1ms Field low cut : Out Field high cut : 400 Hz Record length : 23 s Profile length : 22 km Source points : 799 Dates acquired: 2008/08/05-2008/08/16 Short summary of the main processing steps: 1) BUR_shots_geom.sgy The raw shot records are pre-processed with VIBSIST decoding, quality control. Information about the shot and receiver geometry has been added to the trace headers. 2) BUR_original_stack.sgy The processing flow of the original data stack includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering (for a complete description see Juhlin & Lund, 2011) 3) BUR_crossdip_stack.sgy The main processing steps of the crossdip stack are very similar to those of the original stack, including trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering. Before DMO correction, an additional cross-dip correction step has been added. For a complete description see Beckel & Juhlin, 2019. 4) BUR_crossdip_mig.sgy The processing flow of the migrated section includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, cross-dip correction, DMO correction, stacking, coherency filtering and migration (for a complete description see Beckel & Juhlin, 2019). This dataset contains the cross-dip stack of the Burträsk profile (Beckel & Juhlin, 2019). Processing steps for this data set: 1. Read decoded VIBSIST data 2. Bulk static shift to zero time 3. Apply geometry 4. Manual first-break picking 5. Trace balance: 0-3000 ms 6. Ground-roll and first-break muting in local time- frequency domain: 25 % threshold 7. Spectral equalization: 30 Hz window, 25-40-120-150 Hz bandpass 8. Time-variant bandpass filtering: 0-200 ms: 35-60-120-180 Hz 250-500 ms: 30-50-120-180 Hz 600-900 ms: 25-40-110-165 Hz 1100-3000 ms: 20-35-100-150 Hz 9. Refraction statics: floating datum, replacement velocity from model 10. Trace editing 11. Horizontal median filter: 11 traces, 5300 m s-1 and 3000 m s-1 12. Butterworth filter: 20-40-90-120 Hz 13. Spherical divergence correction: 0.8 tpower, 2.0 vpower 14. Velocity analysis 15. NMO correction: 40 % stretch mute 16. Residual statics 17. Cross-dip correction: 5400 m s-1 , 20 % taper; Velocity analysis 18. DMO correction; Velocity analysis 19. Stacking 20. FX deconvolution: 19 trace window 21. Trace balance Processed seismic data stored as one file for the entire seismic profile, according to SEG technical standard SEG-Y revision 1 (SEG-Y_r1.0, 2002); https://seg.org/Publications/SEG-Technical-StandardsReflexionsseismiska mätningar över Burträsk-förkastningen I norra Sverige År 2008 gjordes en reflexionsseismiska undersökning över Burträsk-förkastningen I norra Sverige. Förkastningen formades vid slutet av sista istiden när glaciärerna nedsmältade snabbt. Ändamålen av undersökningen var att avbilda förkastningens djupa strukturerna. Seismisk profilen följde befintliga vägar, vilket resulterade I en ganska slingrig geometri av profilen. Datasetet bearbetades och publicerades först av Juhlin & Lund (2011). I 2018 gjordes ett nytt bearbetning av som omfattade en ytterligare steg för att korrigera effekten av 3D profilgeometrin (Beckel & Juhlin, 2019). En mer detaljerad beskrivning av datasetet som inkluderar alla viktiga parametrar är tillgängligt på den engelska katalogsidan:https://snd.gu.se/en/catalogue/study/SND1099 Utförlig beskrivning av datasetet finns på den engelska katalogsidan: https://snd.gu.se/en/catalogue/study/SND109

Reflexionsseismiska mätningar över Burträsk-förkastningen: Shot gathers med geometri

In 2008, a 22 km long high resolution reflection seismic profile was acquired over the Burträsk fault in Northern Sweden. The Burträsk fault formed at the end of the last glacial, triggered by the rapid melting of the Scandinavian ice sheet and the following crustal rebound. The aim of the survey was to image the structure of the fault with depth. The profile followed existing roads resulting in a very crooked acquisition geometry. A list of the key acquisition parameters is given below. The dataset was first processed and published in 2011. In 2018, the dataset was reprocessed using an additional cross-dip correction step to improve the imaging of reflection with a dip component in the cross-profile direction. The following data files are available for downloading: 1) raw shot gathers (decoded and quality controlled, with geometry information in the headers) 2) original stacked section from Juhlin and Lund (2011) 3) cross-dip corrected stacked section from Beckel and Juhlin (2019) 4) cross-dip corrected migrated section from Beckel and Juhlin (2019) A short summary of the main processing steps for each dataset is given below. For a complete description, please refer to the above mentioned publications. Key acquisition parameters: Number of channels: 280 Near offset: 0 m Geophone spacing: 20 m Geophone type : 28 Hz single Nominal source spacing : 20 m Source type : VIBSIST Hit interval between hammer blows : 100-200 ms Sweeps per source point :3-4 Nominal fold : 140 Recording instrument : SERCEL 408L Sample rate : 1ms Field low cut : Out Field high cut : 400 Hz Record length : 23 s Profile length : 22 km Source points : 799 Dates acquired: 2008/08/05-2008/08/16 Short summary of the main processing steps: 1) BUR_shots_geom.sgy The raw shot records are pre-processed with VIBSIST decoding, quality control. Information about the shot and receiver geometry has been added to the trace headers. 2) BUR_original_stack.sgy The processing flow of the original data stack includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering (for a complete description see Juhlin & Lund, 2011) 3) BUR_crossdip_stack.sgy The main processing steps of the crossdip stack are very similar to those of the original stack, including trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering. Before DMO correction, an additional cross-dip correction step has been added. For a complete description see Beckel & Juhlin, 2019. 4) BUR_crossdip_mig.sgy The processing flow of the migrated section includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, cross-dip correction, DMO correction, stacking, coherency filtering and migration (for a complete description see Beckel & Juhlin, 2019). This dataset contains the pre-processed shot gathers of the Burträsk profile. Processing steps for this data set: 1: Read decoded VIBSIST data 2: Bulk static shift to zero time 3: Apply geometry Processed seismic data stored as one file for the entire seismic profile, according to SEG technical standard SEG-Y revision 1 (SEG-Y_r1.0, 2002); https://seg.org/Publications/SEG-Technical-Standards Access data by contacting [email protected] or by using the web form.Reflexionsseismiska mätningar över Burträsk-förkastningen I norra Sverige År 2008 gjordes en reflexionsseismiska undersökning över Burträsk-förkastningen I norra Sverige. Förkastningen formades vid slutet av sista istiden när glaciärerna nedsmältade snabbt. Ändamålen av undersökningen var att avbilda förkastningens djupa strukturerna. Seismisk profilen följde befintliga vägar, vilket resulterade I en ganska slingrig geometri av profilen. Datasetet bearbetades och publicerades först av Juhlin & Lund (2011). I 2018 gjordes ett nytt bearbetning av som omfattade en ytterligare steg för att korrigera effekten av 3D profilgeometrin (Beckel & Juhlin, 2019). En mer detaljerad beskrivning av datasetet som inkluderar alla viktiga parametrar är tillgängligt på den engelska katalogsidan:https://snd.gu.se/en/catalogue/study/SND1099 Utförlig beskrivning av datasetet finns på den engelska katalogsidan: https://snd.gu.se/en/catalogue/study/SND1099 För tillgång till data kontakta [email protected] eller använd beställningsformuläret i katalogen

Reflexionsseismiska mätningar över Burträsk-förkastningen: Original stack

In 2008, a 22 km long high resolution reflection seismic profile was acquired over the Burträsk fault in Northern Sweden. The Burträsk fault formed at the end of the last glacial, triggered by the rapid melting of the Scandinavian ice sheet and the following crustal rebound. The aim of the survey was to image the structure of the fault with depth. The profile followed existing roads resulting in a very crooked acquisition geometry. A list of the key acquisition parameters is given below. The dataset was first processed and published in 2011. In 2018, the dataset was reprocessed using an additional cross-dip correction step to improve the imaging of reflection with a dip component in the cross-profile direction. The following data files are available for downloading: 1) raw shot gathers (decoded and quality controlled, with geometry information in the headers) 2) original stacked section from Juhlin and Lund (2011) 3) cross-dip corrected stacked section from Beckel and Juhlin (2019) 4) cross-dip corrected migrated section from Beckel and Juhlin (2019) A short summary of the main processing steps for each dataset is given below. For a complete description, please refer to the above mentioned publications. Key acquisition parameters: Number of channels: 280 Near offset: 0 m Geophone spacing: 20 m Geophone type : 28 Hz single Nominal source spacing : 20 m Source type : VIBSIST Hit interval between hammer blows : 100-200 ms Sweeps per source point :3-4 Nominal fold : 140 Recording instrument : SERCEL 408L Sample rate : 1ms Field low cut : Out Field high cut : 400 Hz Record length : 23 s Profile length : 22 km Source points : 799 Dates acquired: 2008/08/05-2008/08/16 Short summary of the main processing steps: 1) BUR_shots_geom.sgy The raw shot records are pre-processed with VIBSIST decoding, quality control. Information about the shot and receiver geometry has been added to the trace headers. 2) BUR_original_stack.sgy The processing flow of the original data stack includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering (for a complete description see Juhlin & Lund, 2011) 3) BUR_crossdip_stack.sgy The main processing steps of the crossdip stack are very similar to those of the original stack, including trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, DMO correction, stacking and coherency filtering. Before DMO correction, an additional cross-dip correction step has been added. For a complete description see Beckel & Juhlin, 2019. 4) BUR_crossdip_mig.sgy The processing flow of the migrated section includes trace editing and balancing, spectral equalization, time-variant bandpass filtering, refraction and residual statics, horizontal median filtering, NMO correction, cross-dip correction, DMO correction, stacking, coherency filtering and migration (for a complete description see Beckel & Juhlin, 2019). This dataset contains the original stack of the Burträsk profile (Juhlin & Lund, 2011). Processing steps for this data set: 1. Read decoded VIBSIST data 2. Bulk static shift to zero time 3. Apply geometry 4. Pick first breaks 5. Resample: 2 ms, 1501 samples 6. Trace editing 7. Trace balance: 0-3000 ms 8. Spectral equalization: 25-40-120-150 Hz 9. Time variant bandpass filter: 0-200 ms: 35-70-200-300 Hz 250-500 ms: 30-60-180-270 Hz 600-900 ms: 22-45-135-200 Hz 1100-3000 ms: 20-40-120-180 Hz 10. Refraction statics: datum 200 m, replacement velocity 5500 m s-1, overburden velocity 1600 m s -1 11. Residual statics 12. AGC: 100 ms window 13. Median filter: 11 traces, 3 samples, 5300 m s-1 , subtract 14. Butterworth filter: 20-40-200-300 15. Residual statics 16. Velocity analysis 17. NMO correction: 40% stretch mute 18. DMO 19. Stack 20. Trace balance 21. FX Decon: 19 trace window Processed seismic data stored as one file for the entire seismic profile, according to SEG technical standard SEG-Y revision 1 (SEG-Y_r1.0, 2002); https://seg.org/Publications/SEG-Technical-StandardsReflexionsseismiska mätningar över Burträsk-förkastningen I norra Sverige År 2008 gjordes en reflexionsseismiska undersökning över Burträsk-förkastningen I norra Sverige. Förkastningen formades vid slutet av sista istiden när glaciärerna nedsmältade snabbt. Ändamålen av undersökningen var att avbilda förkastningens djupa strukturerna. Seismisk profilen följde befintliga vägar, vilket resulterade I en ganska slingrig geometri av profilen. Datasetet bearbetades och publicerades först av Juhlin & Lund (2011). I 2018 gjordes ett nytt bearbetning av som omfattade en ytterligare steg för att korrigera effekten av 3D profilgeometrin (Beckel & Juhlin, 2019). En mer detaljerad beskrivning av datasetet som inkluderar alla viktiga parametrar är tillgängligt på den engelska katalogsidan:https://snd.gu.se/en/catalogue/study/SND1099 Utförlig beskrivning av datasetet finns på den engelska katalogsidan: https://snd.gu.se/en/catalogue/study/SND109