Energy balance and deformation mechanisms of duplexes

Mitra, Gautam; Boyer, Steven E.

doi:10.1016/0191-8141(86)90050-7

Cited by 91 publications

(53 citation statements)

References 13 publications

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“…3e, f) (Boyer and Elliott, 1982;Mitra and Boyer, 1986). In addition, since the individual imbricate faults transfer displacement from the floor to the roof thrust (Boyer, 1978), increase in displacement on individual imbricates increases the total displacement on the roof thrust (Mitra and Boyer, 1986). Thus, other factors being equal, a foreland dipping duplex results in the largest translation of the roof thrust sheet.…”

Section: Regional Geologymentioning

confidence: 96%

“…The duplex consists of three northern hinterland-dipping horses making up a hinterland-dipping component, three horses in the middle constituting an antiformal stack, and three small southern horses making up a foreland-dipping component of the duplex. Although duplexes often show transition from one type to another in the transport direction (Mitra and Boyer, 1986), to our knowledge this is the first description of a duplex that contains all three different duplex types within a single duplex. Because the top of the duplex has been eroded the fault-branching and -rejoining patterns can be interpreted in slightly different ways that are discussed in detail elsewhere (Bhattacharyya and Mitra, 2009).…”

Section: Structure Of the Rangit Windowmentioning

confidence: 98%

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The lesser Himalayan Duplex in Sikkim: Implications for variations in Himalayan shortening

2010

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Thrust duplexes account for large fractions of the total shortening in most fold-thrust belts (FTBs). They also provide an efficient mechanism for transferring slip upward from the basal decollement and for transporting roof thrust sheets over long distances. The Lesser Himalayan duplex (LHD) plays a prominent role in the overall evolution of the Himalayan FTB and has been described from Garhwal-Kumaon to Bhutan. In Sikkim the LHD shows unique structural geometry and has been responsible for transporting crystalline thrust sheets (MCT 1 and MCT 2) farther southward than other parts of the Himalaya. Such lateral variations in LHD geometry imply variations in the kinematic history of the Lesser Himalaya and variations in shortening and shortening history along the length of the Himalayan arc, and these are reflected in observable large scale structural patterns.

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Section: Regional Geologymentioning

confidence: 96%

Section: Structure Of the Rangit Windowmentioning

confidence: 98%

The lesser Himalayan Duplex in Sikkim: Implications for variations in Himalayan shortening

2010

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“…Figure 4 shows the proposed evolution of the Vila de Cruces-Belmil duplex. It includes horses for which displacement is less than (hinterland-dipping duplexes), equals (antiformal stacks), or exceeds (foreland-dipping duplexes) fault spacing (Mitra and Boyer 1986). If length of the greenschist/metapelite contact (38 km) is compared with its sectional length (30 km), a shortening of 8 km due to imbrication can be estimated only for the upper thrust sheet.…”

Section: Geological Settingmentioning

confidence: 99%

The Vila de Cruces Ophiolite: A Remnant of the Early Rheic Ocean in the Variscan Suture of Galicia (Northwest Iberian Massif)

Arenas¹,

Catalán²,

Martı́nez³

et al. 2007

The Journal of Geology

119

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. A B S T R A C TThe Vila de Cruces ophiolite is one of the ophiolitic units involved in the Variscan suture of the northwest Iberian Massif. This ophiolite consists of a tectonically repeated succession of greenschist facies volcanic rocks, common alternations of metasediments of pelitic or siliceous character, and scarce orthogneisses, metagabbros, and serpentinites. The protolith age of a granitic orthogneiss that intruded the mafic rocks is dated at Ma (U-Pb in 497 ‫ע‬ 4 zircons). This age can be considered a reference for the generation of the ophiolite. According to their contents of some of the most immobile trace elements, the greenschist and the metagabbros are derived from basaltic magmas with compositions similar to those of island-arc tholeiites. The influence of a subduction zone in the generation of the original basaltic magmas can be deduced from the marked negative Nb anomaly observed in all the metabasic rocks of this ophiolite. The granitic orthogneisses can also be genetically related to the basic rocks because they are similar to granitic rocks generated in volcanic arcs. The Vila de Cruces ophiolite is interpreted as a suprasubduction zone ophiolite generated in Late Cambrian times, during the early stages of the opening of the Rheic Ocean. The ophiolite was probably generated in a back-arc basin developed during the first stages of the pulling apart and later drift of one or more peri-Gondwanan terranes, one of them represented by the upper allochthon of the northwest Iberian Massif.

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“…The effect of basal friction persists with continued deformation and expresses itself also on a larger scale in the geometry of the thrust belt (Mitra, 1986;Mitra & Boyer, 1986;Moore 1989). Consider the effect of increasing basal friction on thrust-sheet length.…”

Section: The Effect Of Basal Friction In the Overthrust Phasementioning

confidence: 99%

Wedge equilibrium in fold-and-thrust belts: prediction of out-of-sequence thrusting based on sandbox experiments and natural examples

Nieuwland

Leutscher

Gast

2000

Netherlands Journal of Geosciences

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Thrust tectonics are dealt with on the basis of primarily experiments focusing on the dynamics of a developing thrust belt and on understanding and predicting normal-sequence and out-of-sequence thrusting. Field examples are presented in addition to the examples of sandbox-model experiments. The results have improved the insight into thrust-belt-forming mechanisms; the validity of the conclusions is supported by natural examples.The experimental program was aimed at examining the effect of changes in a selection of key parameters in thrust tectonics on the geometry and the successive phases in the development of thrust sheets. Sandbox experiments were used to analyse the effects of basal friction, detachment lithology, basement relief and syntectonic sedimentation. Multilayer experiments were performed to simulate the effects of ductile detachment lithologies.It was found that a thrust belt's cross-sectional geometry is formed in a dynamic process during which the wedge may develop from subcritical through critical to supercritical and back to critical again.The process is illustrated with sandbox experiments, analysed by time-lapse computed tomography scans and in-situ stress measurements. On the basis of the sandboxmodel results and the natural examples, we conclude that a critical examination of the boundary conditions of a fold-andthrust belt and of changes in these conditions during the deformation process enables predictions about the geometry and kinematics of the thrust belt.

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Energy balance and deformation mechanisms of duplexes

Cited by 91 publications

References 13 publications

The lesser Himalayan Duplex in Sikkim: Implications for variations in Himalayan shortening

The lesser Himalayan Duplex in Sikkim: Implications for variations in Himalayan shortening

The Vila de Cruces Ophiolite: A Remnant of the Early Rheic Ocean in the Variscan Suture of Galicia (Northwest Iberian Massif)

Wedge equilibrium in fold-and-thrust belts: prediction of out-of-sequence thrusting based on sandbox experiments and natural examples

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