Collisional Orogeny in the Scandinavian Caledonides (COSC)

Gee, David G.; Juhlin, Christopher; Pascal, Christophe; Robinson, Peter

doi:10.1080/11035891003759188

Cited by 99 publications

(100 citation statements)

References 72 publications

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“…In the present summary, we focus on the area from Are toÖstersund in western Jämtland (yellow square in Figs 1 and 2), where we collected MT data. The detailed geology of this area has been previously described by Gee et al (2010), Hedin et al (2012Hedin et al ( , 2014 and Juhlin et al (2016).…”

Section: Geological Settingmentioning

confidence: 99%

“…This is overlain by theÅreskutan Nappe (and comparable units), which consists of gneisses, granulites and migmatites with evidence for ultra-high pressure metamorphism (Majka et al 2014;Klonowska et al 2015). The upper unit is dominated by garnet micaschists and amphibolites (Gee et al , 2010.…”

Section: Geological Settingmentioning

confidence: 99%

“…Korja et al (2008) deployed 60 broadband magnetotelluric (MT) stations along the CCT reflection seismic profile in western Jämtland (note that Figure 1. Geological map of Scandinavian Orogeny and cross-section through the Central Scandes between points W and E (modified after Gee et al 2010). Our measurement area atÅre is marked with a yellow rectangle.…”

Section: Previous Geophysical Studiesmentioning

confidence: 99%

“…The Collisional Orogeny in the Scandinavian Caledonides (COSC) scientific continental drilling project was designed to focus on Mid-Palaeozoic mountain building processes in western Scandinavia (Lorenz et al 2011(Lorenz et al , 2015a. With two fully cored boreholes (COSC-1, drilled in 2014 May-August; COSC-2, in the planning phase), each to ∼2.5 km depth, the COSC project aims to investigate both the Caledonian nappes and the underlying basement to further our current understanding of orogenic processes (Gee et al 2010). Additionally, various geophysical investigations have been included within the COSC project.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A magnetotelluric investigation of the Scandinavian Caledonides in western Jämtland, Sweden, using the COSC borehole logs as prior information

Yan¹,

Juanatey²,

Kalscheuer³

et al. 2016

Geophys. J. Int.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Previous Geophysical Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A magnetotelluric investigation of the Scandinavian Caledonides in western Jämtland, Sweden, using the COSC borehole logs as prior information

Yan¹,

Juanatey²,

Kalscheuer³

et al. 2016

Geophys. J. Int.

Self Cite

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“…Further, an EC/Temp probe, a downhole pump, and a pressure sensor are standard equipment, either already available on a drill site or easily obtainable; thus, FFEC logging can be done in the 1-day breaks with minimum Tsang et al 2016) spaceextra trouble and with no impact on drilling schedule, which provides a new approach to hydraulic testing during drilling. Tsang et al (2016) demonstrated that this can be done by applying the method to the drilling of the 2,500-m COSC-1 borehole at Åre, Sweden as part of the Swedish Deep Drilling Program (Gee et al 2010;Lorenz et al 2015). The COSC-1 borehole was drilled though the Seve Nappe, which contains low permeability, high grade metamorphic rocks (mostly felsic gneisses) indicative of deep (100 km) crustal levels.…”

Section: Introductionmentioning

confidence: 99%

Flowing fluid electrical conductivity logging of a deep borehole during and following drilling: estimation of transmissivity, water salinity and hydraulic head of conductive zones

et al. 2016

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Flowing fluid electrical conductivity (FFEC) logging is a hydrogeologic testing method that is usually conducted in an existing borehole. However, for the 2,500-m deep COSC-1 borehole, drilled at Åre, central Sweden, it was done within the drilling period during a scheduled 1-day break, thus having a negligible impact on the drilling schedule, yet providing important information on depths of hydraulically conductive zones and their transmissivities and salinities. This paper presents a reanalysis of this set of data together with a new FFEC logging data set obtained soon after drilling was completed, also over a period of 1 day, but with a different pumping rate and water-level drawdown. Their joint analysis not only results in better estimates of transmissivity and salinity in the conducting fractures intercepted by the borehole, but also yields the hydraulic head values of these fractures, an important piece of infor-mation for the understanding of hydraulic structure of the subsurface. Two additional FFEC logging tests were done about 1 year later, and are used to confirm and refine this analysis. Results show that from 250 to 2,000 m depths, there are seven distinct hydraulically conductive zones with different hydraulic heads and low transmissivity values. For the final test, conducted with a much smaller water-level drawdown, inflow ceased from some of the conductive zones, confirming that their hydraulic heads are below the hydraulic head measured in the wellbore under non-pumped spaceconditions. The challenges accompanying 1-day FFEC log-ging are summarized, along with lessons learned in address-ing them.

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Plate rotation during continental collision and its relationship with the exhumation of UHP metamorphic terranes: Application to the Norwegian Caledonides

Bottrill

Hunen

Cuthbert

et al. 2014

Geochem Geophys Geosyst

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Lateral variation and asynchronous onset of collision during the convergence of continents can significantly affect the burial and exhumation of subducted continental crust. Here we use 3-D numerical models for continental collision to discuss how deep burial and exhumation of high and ultrahigh pressure metamorphic (HP/UHP) rocks are enhanced by diachronous collision and the resulting rotation of the colliding plates. Rotation during collision locally favors eduction, the inversion of the subduction, and may explain the discontinuous distribution of ultra-high pressure (UHP) terranes along collision zones. For example, the terminal (Scandian) collision of Baltica and Laurentia, which formed the Scandinavian Caledonides, resulted in the exhumation of only one large HP/UHP terrane, the Western Gneiss Complex (WGC), near the southern end of the collision zone. Rotation of the subducting Baltica plate during collision may provide an explanation for this distribution. We explore this hypothesis by comparing orthogonal and diachronous collision models and conclude that a diachronous collision can transport continental material up to 60 km deeper, and heat material up to 300 C hotter, than an orthogonal collision. Our diachronous collision model predicts that subducted continental margin material returns to the surface only in the region where collision initiated. The diachronous collision model is consistent with petrological and geochonological observations from the WGC and makes predictions for the general evolution of the Scandinavian Caledonides. We propose the collision between Laurentia and Baltica started at the southern end of the collisional zone, and propagated northward. This asymmetric geometry resulted in the counter clockwise rotation of Baltica with respect to Laurentia, consistent with paleomagnetic data from other studies. Our model may have applications to other orogens with regional UHP terranes, such as the Dabie Shan and Papua New Guinea cases, where block rotation during exhumation has also been recorded.

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Collisional Orogeny in the Scandinavian Caledonides (COSC)

Cited by 99 publications

References 72 publications

A magnetotelluric investigation of the Scandinavian Caledonides in western Jämtland, Sweden, using the COSC borehole logs as prior information

A magnetotelluric investigation of the Scandinavian Caledonides in western Jämtland, Sweden, using the COSC borehole logs as prior information

Flowing fluid electrical conductivity logging of a deep borehole during and following drilling: estimation of transmissivity, water salinity and hydraulic head of conductive zones

Plate rotation during continental collision and its relationship with the exhumation of UHP metamorphic terranes: Application to the Norwegian Caledonides

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