Regional Caledonian structure within an oblique convergence zone, Dronning Louise Land, NE Greenland

Strachan, R. A.; Holdsworth, R. E.; Friderichsen, J.D; Jepsen, H.F

doi:10.1144/gsjgs.149.3.0359

Cited by 72 publications

(83 citation statements)

References 21 publications

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“…In addition, the N-S ductile-flow (D 2H ) fabrics preserved in the Krummedal Sequence in Forsblad Fjord, which are kinematically similar to features documented further north by Holdsworth and Strachan (1991), Strachan et al (1992), Friderichsen et al (1994), Strachan et al (1995), Vold (1997), and Andresen et al (1998a) are consistent with lateral extrusion of middle-crustal material as predicted by the Bird (1991) model. However, it is important to note that that flow was oriented N-S. Rather than flowing away from the topographic high down the ~E-W maximum gravitational potential energy gradient that we would expect to be perpendicular to a N-Strending orogen, this material flowed parallel to it.…”

Section: Implications For the Role Of Extension In The Development Ofsupporting

confidence: 67%

“…3d, e) provide evidence for both top-to-the-south (dextral) and top-to-the-north (sinistral) non-coaxial shear during N-S, orogen-parallel flow. Additional evidence for N-S flow is suggested by the N-S L 2H stretching lineations that accompany the above-mentioned shear structures Orogen-parallel flow has been reported to the north by Holdsworth and Strachan (1991), Strachan et al (1992), Friderichsen et al (1994), Strachan et al (1995), Vold (1997), and Andresen et al (1998a) and in middle-crustal rocks of the Scandinavian Caledonides by Fossen (2000). Holdsworth and Strachan (1991) proposed that the N-S lineations with top-to-the-N sense of shear that they observed in NE Greenland resulted from an early phase of strike-slip deformation followed by transpression associated with the sinistrally oblique nature of the BalticaLaurentia collision.…”

Section: Structural Geologymentioning

confidence: 81%

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Geologic constraints on middle-crustal behavior during broadly synorogenic extension in the central East Greenland Caledonides

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Hodges

Martin

et al. 2002

International Journal of Earth Sciences

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Structural and U-Pb geochronologic data from the Forsblad Fjord area of East Greenland (72°30′N) indicate close spatial and temporal ties between orogen-parallel shear and extensional deformation during Caledonian orogenesis. This territory is composed of three tectonostratigraphic units separated by two splays of the Fjord Region Detachment System (FRDS), a principal extensional fault system of the East Greenland Caledonides that was active in Silurian time. The oldest Caledonian fabrics in Forsblad Fjord, which developed at upper amphibolite facies metamorphic conditions, indicate that there was north-south, lateral extrusion of ductile middle-crustal material synchronous with approximately east-west shortening. U-Pb dating of synkinematic granitic leucosomes in migmatitic schists and gneisses demonstrates that this process was underway at ca. 425 Ma. Subsequently, east-west extension along the two splays of the FRDS truncated the older fabrics; the structurally highest of these shear zones -the Tindern detachment -was active as early as ca. 424 Ma. This implies either that there was a rapid transition from Caledonian shortening and possible transpressional deformation to post-orogenic collapse, or our preferred interpretation that extension was synorogenic. The FRDS shares many structural characteristics with the South Tibetan Detachment System of the Cenozoic Himalayan orogen but exhibits two important differences. First, while the South Tibetan system developed in the down-going Indian plate during the India-Eurasia collision, the Fjord Region system developed in the overriding Laurentian plate during the collision of Laurentia with Baltica. Second, whereas the exposed extensional structures in the Himalayas developed in the upper crust and are only inferred to have extended to deeper levels, those in the Forsblad Fjord area were demonstrably active at middle-crustal levels. Evidence for broadly coeval extension and contraction at differen t structural levels in both mountain belts emphasizes the general importance of crustal decoupling in the collisional orogenic process, and implies that synorogenic extensional deformation is not strictly an upper crustal phenomenon.

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Section: Implications For the Role Of Extension In The Development Ofsupporting

confidence: 67%

Section: Structural Geologymentioning

confidence: 81%

Geologic constraints on middle-crustal behavior during broadly synorogenic extension in the central East Greenland Caledonides

White

Hodges

Martin

et al. 2002

International Journal of Earth Sciences

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“…Isoclinal folding of the mylonitic fabric is also observed within the SSZ. Similar relationships are described in Dronning Louise Land (Holdsworth and Strachan 1991;Strachan et al 1992). These structures are interpreted as oblique folds related to shearing on the SSZ.…”

Section: The Storstrømmen Shear Zone and Related Mylonite Zonessupporting

confidence: 64%

“…The Storstrømmen shear zone (SSZ) in the Greenland Caledonides has played a prominent role in developing models for sinistral transpression during the Paleozoic collision of Baltica and Laurentia (Holdsworth and Strachan 1991;Strachan et al 1992Strachan et al , 1995Dewey and Strachan 2003). Strike-slip displacement along the SSZ is inferred to have been coeval with thrust displacement in the foreland to the west (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The transpressional model for the SSZ is based on comparison of SSZ strikeslip deformation with thrusting observed in Dronning Louise Land (Holdsworth and Strachan 1991;Strachan et al 1992;Smith et al 2007). There is still no documented simultaneity in the time of thrusting in the foreland and movement on the SSZ.…”

Section: Transpression Due To Sinistral Oblique Collision In the Greementioning

confidence: 99%

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The Timing of Strike-Slip Deformation Along the Storstrømmen Shear Zone, Greenland Caledonides: U–Pb Zircon and Titanite Geochronology

Hallett¹,

McClelland²,

Gilotti³

2014

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The Storstrømmen shear zone (SSZ) in the Greenland Caledonides is widely interpreted to have formed in a transpressional regime during sinistral, oblique collision between Baltica and Laurentia in the Silurian to Devonian. New mapping of the SSZ at Sanddal documents a 100 m thick, greenschistfacies mylonite zone cutting the eclogite to amphibolite-facies gneiss complex. We present U–Pb ion probe geochronology on zircon and titanite from a variety of lithologies that shows the SSZ was active from late Devonian to the Carboniferous (at least until 350 Ma). The age of thrusting in the foreland is not well known, but must be younger than the age of eclogite-facies metamorphism at ~400 Ma. It is, therefore, possible that contraction is the same age as strike-slip motion, and that transpression is a viable model. The timing of the SSZ is synchronous with dextral strike-slip displacement on the Germania Land deformation zone. Simultaneous displacement on sinistral and dextral, conjugate shear zones suggests that the SSZ is part of a strikeslip fault system that led to lateral escape of material northward (present day coordinates) during the waning stages of plate convergence between Laurentia and Baltica.SOMMAIRELa zone de cisaillement de Storstrømmen (SSZ) dans les Calédonides du Groenland est généralement comprise comme ayant été formée durant un régime de transpression sénestre lors de la collision oblique entre Baltica et Laurentie, du Silurien au Dévonien. Une nouvelle cartographie de la SSZ à Sanddal décrit une zone de 100 m d’épaisseur de mylonite au faciès des schistes verts qui recoupe un complexe de gneiss au faciès éclogite à amphibolite. Notre analyse géochronologique par sonde ionique U-Pb sur zircon et titanite sur diverses lithologies, montre que la SSZ a été active de la fin du Dévonien jusqu’au Carbonifère (au moins jusqu’à 350 Ma). L’âge du chevauchement dans l’avant-pays n’est pas bien connue, mais il doit être plus jeune que le métamorphisme au faciès d’éclogite à ~400 Ma. Il est donc possible que la contraction soit du même âge que le mouvement de coulissage, et que la transpression soit un modèle viable. La chronologie de la SSZ est synchrone au mouvement de coulissage dextre de la zone de déformation de Germania Land. Les déplacements simultanés, sénestre et dextre, sur des zones de cisaillement conjuguées permettent de penser que la SSZ fait partie d’un système de décrochement qui a engendré une éjection latérale de matériau vers le nord (selon les coordonnées actuelles) durant les stades de convergence des plaques Laurentie et Baltica.

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An Orogenic Model Consistent with Earth Expansion

Strutinski

1994

Frontiers of Fundamental Physics

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Regional Caledonian structure within an oblique convergence zone, Dronning Louise Land, NE Greenland

Cited by 72 publications

References 21 publications

Geologic constraints on middle-crustal behavior during broadly synorogenic extension in the central East Greenland Caledonides

Geologic constraints on middle-crustal behavior during broadly synorogenic extension in the central East Greenland Caledonides

The Timing of Strike-Slip Deformation Along the Storstrømmen Shear Zone, Greenland Caledonides: U–Pb Zircon and Titanite Geochronology

An Orogenic Model Consistent with Earth Expansion

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