Possible effects of pre-existing basement topography on thrust fault ramping

Schedl, Andrew; Wiltschko, David V.

doi:10.1016/0191-8141(87)90011-3

Cited by 43 publications

(18 citation statements)

References 24 publications

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“…Because the fold-and-thrust belt has been evolving on a rifted continental margin, pre-existing normal faults would have been reactivated to form inversion structures of various types on different scales, depending on the angle between the strike of normal faults and the direction of maximum compressive stress field (Etheridge, 1986;Welbon and Butler, 1992;Sassi et al, 1993). Pre-existing normal faults also would have altered the local maximum compressive stress field and trajectory of evolving thrust, and would have strongly affected the features of the low-angle thrusts (Wiltschko and Eastman, 1983;Kraig et al, 1987;Schedl and Wiltschko, 1987;Thomas, 1990). This paper proposes possible mechanisms through which pre-existing normal faults might have affected the evolving thrust tectonics in the foreland areas of western Taiwan.…”

Section: Review and New Insights On Foreland Tectonics In Western Taiwanmentioning

confidence: 97%

Review and New Insights on Foreland Tectonics in Western Taiwan

Yang¹,

Huang²,

Wu³

et al. 2006

International Geology Review

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Taiwan is located on the boundary between the Eurasian and Philippine Sea plates. As a result, foreland tectonics in western Taiwan can be divided into two domains: pre-orogenic extensional structures and those of the outer part of the fold-and-thrust belt that mingled with syn-orogenic normal fault reactivation. This paper proposes a synthetic model for foreland tectonics in western Taiwan, and advances possible mechanisms by which pre-existing normal faults might have affected the evolving thrust tectonics in foreland areas of western Taiwan.The sedimentary basins of pre-orogenic extensional tectonics are of two types-Paleogene and Neogene-which reflect two stages of continental rifting. Results from several studies have been synthesized to provide a tectonic map displaying the regional distribution of tectonic settings at different stages and the trends of normal faults in the basins. The similarity of the en echelon patterns of arrangement for both the Neogene and Paleogene tectonic and structural settings, as shown by the tectonic map, strongly suggests that the entire foreland area was influenced by regional dextral shear. We also provide a detailed description of structures in each tectonic setting, and propose a tectonic evolution model for Cenozoic basin architecture in western Taiwan.Among the pre-orogenic sedimentary basins, the Neogene ones, in which normal faults extend to the frontal areas of the fold-and-thrust belt in western Taiwan, open northeastward. Structural analysis of the thrust fault geometry indicates that, during development of the fold-and-thrust belt on the rifted continental margin in western Taiwan, the pre-existing normal faults in northwestern Taiwan were reactivated to form inversion structures of various types on different scales, depending on the angle between the strike of the normal faults and the direction of maximum compressive stress field. In southwestern Taiwan, where normal fault reactivation is absent from the eastern part of the foreland areas, pre-existing normal faults interacted with developing low-angle thrusts in the inner part of the fold-and-thrust belt. Normal fault reactivation, regardless of how it occurs, thus plays an important role in forming the deformation front of the fold-and-thrust belt. Based on this view, we propose that the orocline or tectonic arc of the island has been influenced more by normal fault reactivation than by the morphology of basement highs.

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Section: Review and New Insights On Foreland Tectonics In Western Taiwanmentioning

confidence: 97%

Review and New Insights on Foreland Tectonics in Western Taiwan

Yang¹,

Huang²,

Wu³

et al. 2006

International Geology Review

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“…According to some authors, thrust ramps develop in portions of deforming sequences where critical pore fluid pressure conditions are locally exceded (Hubbert and Rubey 1959;Gretener 1981;Cello and Nur 1988). Other authors suggest that thrust ramps occur at, or in the vicinities of mechanical heterogeneities (Knipe 1985;Ferguson and Lloyd 1982), which can originate by either buckle and décollement folding typically active ahead of developing thrusts (McNaught and Mitra 1993;Morley 1994), or by pre-existing, fault-controlled steps within the deforming strata (Schedl and Wiltschko 1987). The latter interpretation appears particularly adequate for fold-and-thrust belts which originate at the expense of previously thinned, Atlantic-type passive continental margins.…”

Section: Introductionmentioning

confidence: 94%

The effects of pre-existing normal faults on thrust ramp development: An example from the northern Apennines, Italy

Tavarnelli

1996

Geol Rundsch

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The Umbria-Marche foreland fold-andthrust belt in the northern Apennines of Italy provides excellent evidence to test the hypothesis of synsedimentary-structural control on thrust ramp development. This orogenic belt consists of platform and pelagic carbonates, Late Triassic to Miocene in age, whose deposition was controlled by significant synsedimentary extension. Normal faulting, mainly active from Jurassic through Late Cretaceous-Paleogene time, resulted in significant lateral thickness variability within the related stratigraphic sequences. By Late Miocene time the sedimentary cover was detached from the underlying basement and was deformed by east-verging folds and west-dipping thrusts. Two restored balanced cross sections through the southernmost part of the belt show a coincidence between the early synsedimentary normal faults and the late thrust fault ramps. These evidences suggest that synsedimentary tectonic structures, such as faults and the related lithological lateral changes, can be regarded as mechanically important controlling factors in the process of thrust ramp development during positive tectonic inversion processes.

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“…The magnitude and orientation of stresses in a layer subject to horizontal compression have been calculated by, among others, for example; HmNER (1951), MANDL &SHIPPAM (1981), andSCHEDL &WILTSCm:O (1987). These analyses require assumptions about the elastic properties of the rock, and the boundary conditions in terms of applied stresses or displacements.…”

Section: Failure Of a Layer In Horizontal Compressionmentioning

confidence: 99%

The mechanics of frontal imbrication: a first-order analysis

Platt

1988

Geol Rundsch

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ZusammenfassungDie Abscherung und Anstapelung von Schuppen an die Stirn eines Schuppenkeils stellt eine der wichtigsten Wachstumsarten yon Schuppenkeilen dar. Der Verbruch einer frontalen Rampe wird durch die yon ihr getragene longitudinale Normalspannung hervorgerufen. Die Entstehung nener gleichf6rmiger Schuppen mit begrenzter Liinge I~if~t sich durch diesen Verbruch nicht erkl~iren, ohne daf~ man Heterogenit~iten in gleichm~igen Abst~inden in der liegenden Schicht oder dem Unterbau annimmt. Dennoch steigert der Vortrieb tiber die frontale Rampe eines Schuppenkeils sowohi die vertikale Last auf der Rampe als auch die Geschiebelast auf dem oberen der Schichtung paralMen Tell der Llberschiebung (upper fiat). Infolgedessen ist es wahrscheinlich, daf~ der Spannungsdeviator im Liegenden unter der Vorderkante des Schuppenkeils ein Maximum erreicht. Ein Bruch entsteht dann, wenn die Schubweite des Schuppenkeils einen Wert L erreicht hat, von dem ab der Spannungsdeviator im Liegenden gr6i~er ist als dessen Bruchfestigkeit. List yon folgenden Variablen abMngig: (a) der Gesteinsdichte (b) dem Rampenwinkel (c) dem Geschiebewiderstand auf der basalen Abscherungsbahn, der Rampe und dem oberen der Schichtung parallelen Tell der [lberschiebung (d) AbstractThe detachment and imbrication' of thrust slices at the front of a thrust wedge is one of the principle modes by which such wedges grow. Collapse of the frontal ramp under longitudinai compressionai stress cannot explain the regular formation of new slices of finite length, unless there are regularly spaced heterogeneities in the footwall layer or the underlying basement surface. Advance of the thrust wedge over the frontal ramp, however, increases both the vertical load on the ramp and the traction on the upper flat. This will in general produce a peak deviatoric stress in the footwall layer below the leading edge of the thrust wedge. Failure will occur at this point when the thrust wedge has advanced a distance L such that the deviatoric stress in the footwall layer exceeds its strength. L is a function of (a) rock densit~ (b) ramp angle, (c) the resistances to motion on the basal detachment, the ramp, and the upper flat, and (d) the strength and thickness of the footwall layer. These me&an-ical parameters can therefore control the formation of new thrust slices of regular length in the absence of footwall heterogeneities.Continued accretion of thrust slices at the front of the wedge progressively diminishes its overall taper until it becomes mechanically unstable. Reactivation of previously formed thrusts is a likely response, and will alternate with or occur concurrently with frontal imbrication. Thrust reactivation occurs at a diminishing rate back from the wedge front and is the main cause of back-rotation of older thrust slices. Further back in the wedge, reactivation is not possible, because the thrusts are too steep and have strongly curved trajectories. Thickening of the wedge in this area must occur by out-of-sequence thrusting, backthrusting, or ductile deform...

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Possible effects of pre-existing basement topography on thrust fault ramping

Cited by 43 publications

References 24 publications

Review and New Insights on Foreland Tectonics in Western Taiwan

Review and New Insights on Foreland Tectonics in Western Taiwan

The effects of pre-existing normal faults on thrust ramp development: An example from the northern Apennines, Italy

The mechanics of frontal imbrication: a first-order analysis

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