Microdiamond discovered in the Seve Nappe (Scandinavian Caledonides) and its exhumation by the “vacuum-cleaner” mechanism

Majka, Jarosław; Rosén, Åke; Janák, Marian; Froitzheim, Nikolaus; Klonowska, Iwona; Manecki, Maciej; Sasinková, Vlasta; Yoshida, Kenta

doi:10.1130/g36108.1

Cited by 74 publications

(88 citation statements)

References 35 publications

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“…On top of a Lower Allochthon, the Middle Allochthon comprises the former Baltica passive margin to (Iapetus) ocean-continent transition with major pre-rift volcano-sedimentary successions (Corfu et al, 2014). Its lower to upper greenschist facies nappes are overlain by the Seve nappe complex (SNC) with amphibolite to eclogite facies metamorphism and local evidence for UHP metamorphic conditions Majka et al, 2014a). The roof of the SNC represents the suture between continental Baltica terranes and the oceanic Köli nappe complex (KNC, Upper Allochthon).…”

Section: The Central Scandinavian Caledonidesmentioning

confidence: 99%

Early- to mid-Silurian extrusion wedge tectonics in the central Scandinavian Caledonides

Grimmer

Glodny

Drüppel

et al. 2015

Geology

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We present evidence for an extrusion wedge in the Scandian fold-thrust belt of the central Scandinavian Caledonides (Seve nappe complex). Rb-Sr multimineral geochronology in synkinematic assemblages indicates simultaneous movements at the normal-sense roof shear zone and at the reverse-sense floor shear zone between 434 Ma and 429 Ma. A Sm-Nd age of 462 Ma from a mylonitic garnet mica schist documents prograde garnet growth and possible incipient subduction. Pressure-temperature pseudosection calculations provide evidence for eclogite facies metamorphic conditions and nearly isothermal decompression at ~670 ± 50 °C from 17.5 to 14.5 kbar in garnet-kyanite mica schists during reverse-sense shearing, and from 15 to 11 kbar in garnet mica schists during normal-sense shearing. These data and the presence of decompression-related pegmatites dated at 434 Ma and 429 Ma indicate that the Seve nappes form a large-scale extrusion wedge. This wedge extends along strike for at least 150 km and marks an early stage of ultrahigh-pressure metamorphism, exhumation, and orogenic wedge formation in this part of the Scandinavian Caledonides predating the major, post-415 Ma ultrahigh-pressure exhumation processes in southwestern Norway. INTRODUCTIONExtrusion wedges are increasingly recognized as major, lithosphericscale structural features in collisional orogens that exhumed ultrahigh-pressure (UHP) metamorphic rocks during plate convergence, as for example in the Himalayas, Alps, and Hellenides (see Ring and Glodny, 2010, and references therein). They are characterized by simultaneous movements along their normal-sense roof and reverse-sense floor shear zones. We focus on HP metamorphic rocks of the Seve nappes in the Jämtland-Västerbotten segment of the central Scandinavian Caledonides (Fig. 1A). They are bounded by a normal-sense, hinterland-directed shear zone at the roof and a foreland-directed shear zone at the floor (Greiling et al., 1998). This set of opposed-sense shear zones is a structural feature crucial for understanding Scandian orogenic wedge evolution. Based on this geometry, a Himalayantype extrusion of the Seve nappes was hypothesized (Gee et al., 2010). We studied both shear zones to test for simultaneous ductile shear and for their timing within Scandian orogenic wedge evolution.

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Section: The Central Scandinavian Caledonidesmentioning

confidence: 99%

Early- to mid-Silurian extrusion wedge tectonics in the central Scandinavian Caledonides

Grimmer

Glodny

Drüppel

et al. 2015

Geology

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“…In Jämtland, the Seve Nappe Complex is known to consist of three units, where the Lower Seve Nappe is similar to the underlying Särv Nappe, with psammitic schists and amphibolites, but deformed in amphibolite facies. 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%

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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“…The first discovery is quite recent and occurred in the Kokchetav massif in Kazakhstan (Sobolev and Shatsky, 1990). Several discoveries occurred since, in various parts of the world: in the Rhodope Mountains in Greece (Mposkos and Kostopoulos, 2001) in the Erzgebirge massif (Germany, Massonne, 1999), in the Bohemian Massif (Kotková et al, 2011), the Tromsø Nappe in the Norwegian Caledonides (Janák et al, 2013), in the Seve Nappe from the Scandinavian Caledonides (Majka et al, 2014).…”

Section: Discussionmentioning

confidence: 97%

“…Since then, several localities for metamorphic microdiamond have been described in various orogens: the Dabie Shan mountains in China (Shutong et al, 1992), the Rhodope Mountains in Greece (Mposkos and Kostopoulos, 2001) in the Erzgebirge massif (Germany, Massonne, 1999), in the Bohemian Massif (Kotková et al, 2011), the Tromsø Nappe in the Norwegian Caledonides (Janák et al, 2013), in the Seve Nappe from the Scandinavian Caledonides (Majka et al, 2014). In all cases, high pressure metamorphism was already recognized thanks to typical lithologies (i.e.…”

Section: Introductionmentioning

confidence: 95%

Discovery of metamorphic microdiamonds from the parautochthonous units of the Variscan French Massif Central

et al. 2015

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Microdiamond discovered in the Seve Nappe (Scandinavian Caledonides) and its exhumation by the “vacuum-cleaner” mechanism

Cited by 74 publications

References 35 publications

Early- to mid-Silurian extrusion wedge tectonics in the central Scandinavian Caledonides

Early- to mid-Silurian extrusion wedge tectonics in the central Scandinavian Caledonides

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

Discovery of metamorphic microdiamonds from the parautochthonous units of the Variscan French Massif Central

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