Significance of composite lineations in the mid- to deep crust: a case study from the North Cascades, Washington

Miller, Robert B.; Paterson, Scott R.; Lebit, Hermann; Alsleben, Helge; Luneburg, Catalina

doi:10.1016/j.jsg.2005.11.003

Cited by 26 publications

(32 citation statements)

References 40 publications

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“…Gently dipping foliations and the Dinkelman décollement are folded into a ≥10 km wavelength, gently northwest-plunging antiform. Lineation plunges gently to the north to north-northeast Miller et al, 2006). Mesoscopic fold hinge lines are more scattered, ranging from northwest to north-south, to south-southwest.…”

Section: Basin Deposition and Deformationmentioning

confidence: 97%

Linking deep and shallow crustal processes during regional transtension in an exhumed continental arc, North Cascades, northwestern Cordillera (USA)

et al. 2016

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Section: Basin Deposition and Deformationmentioning

confidence: 97%

Linking deep and shallow crustal processes during regional transtension in an exhumed continental arc, North Cascades, northwestern Cordillera (USA)

et al. 2016

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“… (a) Simplified geological map of the North Cascades showing the location of the map in (b) and the cross‐section A–A′ (Fig. 3a; modified after Miller et al. , 2006).…”

Section: Introductionmentioning

confidence: 99%

Metamorphism and deformation at different structural levels in a strike‐slip fault zone, Ross Lake fault, North Cascades, USA

Gordon

Whitney

Miller

et al. 2010

Journal Metamorphic Geology

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Continental crust is displaced in strike-slip fault zones through lateral and vertical movement that together drive burial and exhumation. Pressure-temperature-deformation (P-T-d) histories of orogenic crust exhumed in transcurrent zones record the mechanisms and conditions of these processes. The Skagit Gneiss Complex, a migmatitic unit of the North Cascades, Washington (USA), was metamorphosed at depths of 25-30 km in a continental arc under contraction, and is bounded on its eastern side by the long-lived transcurrent Ross Lake fault zone (RLFZ). The P-T-d conditions recorded by rocks on either side of the RLFZ vary along the length of the fault zone, but most typically the fault separates high-grade gneiss and plutons from lower-grade rocks. The Ruby Mt-Elijah Ridge area at the eastern margin of the Skagit Gneiss exposes tectonic contacts between gneiss and overlying rocks; the latter rocks, including slivers of Methow basin deposits, are metamorphosed and record higher-grade metamorphism than in correlative rocks along strike along the RLFZ. In this area, the Skagit Gneiss and overlying units all yield maximum P-T conditions of 8-10 kbar at >650°C, indicating that slices of basin rocks were buried to similar mid-crustal depths as the gneiss. After exhumation of fault zone rocks to <15 km depth, intrusion of granitoid plutons drove contact metamorphism, resulting in texturally late andalusite-cordierite in garnet schist. In the Elijah Ridge area of the RLFZ, an overlapping step-over or series of step-overs that evolved through time may have facilitated burial and exhumation of a deep slice of the Methow basin, indicating that strike-slip faults can have major vertical displacement (tens of kilometres) that is significant during the crustal thickening and exhumation stages of orogeny.

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“…It has been shown that in areas of superposed heterogeneous deformations, the designation of foliations (e.g., S 1 , S 2 ,…,S n ) to a particular succession of deformation phases (e.g., D 1 , D 2 ,…,D n ) may be meaningless (e.g., Park 1969;Williams 1985;Tobisch and Paterson 1988;Lüneburg and Lebit 1998;Burg 1999;Potts and Reddy 1999;Miller et al 2006;Passchier and Trouw 2005, pp. 3-5;Forster and Lister 2008).…”

Section: Mesoscopic Structuresmentioning

confidence: 99%

Deciphering the Variscan tectonothermal overprint and deformation partitioning in the Cadomian basement of the Teplá–Barrandian unit, Bohemian Massif

Hajná

Žák

Kachlík

et al. 2012

Int J Earth Sci (Geol Rundsch)

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The Teplá-Barrandian unit (TBU) has long been considered as a simply bivergent supracrustal 'median massif' above the Saxothuringian subduction zone in the Variscan orogenic belt. This contribution reveals a much more complex style of the Variscan tectonometamorphic overprint and resulting architecture of the Neoproterozoic basement of the TBU. For the first time, we describe the crustal-scale NE-SW-trending dextral transpressional Krakovec shear zone (KSZ) that intersects the TBU and thrusts its higher grade northwestern portion severely reworked by Variscan deformation over a southeastern very low grade portion with well-preserved Cadomian structures and only brittle Variscan deformation. The age of movements along the KSZ is inferred as Late Devonian (*380-370 Ma). On the basis of structural, microstructural, and anisotropy of magnetic susceptibility data from the KSZ, we propose a new synthetic model for the deformation partitioning in the Teplá-Barrandian upper crust in response to the Late Devonian to early Carboniferous subduction and underthrusting of the Saxothuringan lithosphere. We conclude that the Saxothuringian/Teplá-Barrandian convergence was nearly frontal during *380-346 Ma and was partitioned into pure shear dominated domains that accommodated orogen-perpendicular shortening alternating with orogen-parallel high-strain domains that accommodated dextral transpression or bilateral extrusion. The synconvergent shortening of the TBU was terminated by a rapid gravity-driven collapse of the thickened lithosphere at *346-337 Ma followed by, or partly simultaneous with, dextral strike-slip along the Baltica margin-parallel zones, driven by the westward movement of Gondwana from approximately 345 Ma onwards.

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Significance of composite lineations in the mid- to deep crust: a case study from the North Cascades, Washington

Cited by 26 publications

References 40 publications

Linking deep and shallow crustal processes during regional transtension in an exhumed continental arc, North Cascades, northwestern Cordillera (USA)

Linking deep and shallow crustal processes during regional transtension in an exhumed continental arc, North Cascades, northwestern Cordillera (USA)

Metamorphism and deformation at different structural levels in a strike‐slip fault zone, Ross Lake fault, North Cascades, USA

Deciphering the Variscan tectonothermal overprint and deformation partitioning in the Cadomian basement of the Teplá–Barrandian unit, Bohemian Massif

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