Kinematic retro-modelling of a cross-section through a thrust-and-fold belt: the Western Irish Namurian Basin

Tanner, David C.; Bense, Frithjof; Ertl, Gabriele

doi:10.1144/sp349.4

Cited by 22 publications

(18 citation statements)

References 52 publications

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“…Therefore, it is not an orocline in the sense of CAREY (1955,1958). Analyzing salients (GRAY and STAMTAKOS 1997;MUKUL andMITRA 1998) andsyntaxes (BUTLER et al 1989;GATES et al 2004) is an important step toward understanding the geodynamics of fold-and-thrust belts (POBLET and LISLE 2011). In many cases curved fold-and-thrust belts are regarded as oroclines, such as the Patagonian-Fuegian Andes (DALZIEL and ELLIOT 1973) and the Cantabrian Arc (GUTIÉRREZ-ALONSO et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Kinematic 3-D Retro-Modeling of an Orogenic Bend in the South Limón Fold-and-Thrust Belt, Eastern Costa Rica: Prediction of the Incremental Internal Strain Distribution

Brandes

Tanner

Winsemann

2016

Pure Appl. Geophys.

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The South Limón fold-and-thrust belt, in the backarc area of southern Costa Rica, is characterized by a 90°curvature of the strike of the thrust planes and is therefore a natural laboratory for the analysis of curved orogens. The analysis of curved foldand-thrust belts is a challenge because of the varying structural orientations within the belt. Based on seismic reflection lines, we created a 3-D subsurface model containing three major thrust faults and three stratigraphic horizons. 3-D kinematic retro-deformation modeling was carried out to analyze the spatial evolution of the fold-and-thrust belt. The maximum amount of displacement on each of the faults is (from hinterland to foreland); thrust 1: 800 m; thrust 2: 600 m; thrust 3: 250 m. The model was restored sequentially to its pre-deformational state. The strain history of the stratigraphic horizons in the model was calculated at every step. This shows that the internal strain pattern has an abrupt change at the orogenic bend. Contractional strain occurs in the forelimbs of the hanging-wall anticlines, while a zone of dilative strain spreads from the anticline crests to the backlimbs. The modeling shows that a NNE-directed transport direction best explains the structural evolution of the bend. This would require a left-lateral strike-slip zone in the North to compensate for the movement and thereby decoupling the South Limón fold-and-thrust belt from northern Costa Rica. Therefore, our modeling supports the presence of the Trans-Isthmic fault system, at least during the Plio-Pleistocene.

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Section: Discussionmentioning

confidence: 99%

Kinematic 3-D Retro-Modeling of an Orogenic Bend in the South Limón Fold-and-Thrust Belt, Eastern Costa Rica: Prediction of the Incremental Internal Strain Distribution

Brandes

Tanner

Winsemann

2016

Pure Appl. Geophys.

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“…The arrival of a large delta system from the west in the Serpukovian marked a switch to clastic deposition and the progressive infill of the basin by a major shallowing-upward succession (over 2200 m thick in the basin axis; Rider, 1974). The basin at this stage was most probably in a post-rift setting and subsiding thermally, although some have inferred an element of flexure and even syn-depositional thrust deformation associated with the onset of Variscan deformation (Tanner et al, 2011). However, supposed unconformities in the clastic infill are more reasonably interpreted as large-scale gravity-driven deformation features (i.e.…”

Section: Geological Settingmentioning

confidence: 99%

Variable character and diverse origin of hybrid event beds in a sandy submarine fan system, Pennsylvanian Ross Sandstone Formation, western Ireland

et al. 2018

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Hybrid event beds comprising both clean and mud‐rich sandstone are important components of many deep‐water systems and reflect the passage of turbulent sediment gravity flows with zones of clay‐damped or suppressed turbulence. ‘Behind‐outcrop’ cores from the Pennsylvanian deep‐water Ross Sandstone Formation reveal hybrid event beds with a wide range of expression in terms of relative abundance, character and inferred origin. Muddy hybrid event beds first appear in the underlying Clare Shale Formation where they are interpreted as the distal run‐out of the wakes to flows which deposited most of their sand up‐dip before transforming to fluid mud. These are overlain by unusually thick (up to 4·4 m), coarse sandy hybrid event beds (89% of the lowermost Ross Formation by thickness) that record deposition from outsized flows in which transformations were driven by both substrate entrainment in the body of the flow and clay fractionation in the wake. A switch to dominantly fine‐grained sand was accompanied initially by the arrest of turbulence‐damped, mud‐rich flows with evidence for transitional flow conditions and thick fluid mud caps. The mid and upper Ross Formation contain metre‐scale bed sets of hybrid event beds (21 to 14%, respectively) in (i) upward‐sandying bed set associations immediately beneath amalgamated sheet or channel elements; (ii) stacked thick‐bedded and thin‐bedded hybrid event bed‐dominated bed sets; (iii) associations of hybrid event bed‐dominated bed sets alternating with conventional turbidites; and (iv) rare outsized hybrid event beds. Hybrid event bed dominance in the lower Ross Formation may reflect significant initial disequilibrium, a bias towards large‐volume flows in distal sectors of the basin, extensive mud‐draped slopes and greater drop heights promoting erosion. Higher in the formation, hybrid event beds record local perturbations related to channel switching, lobe relocations and extension of channels across the fan surface. The Ross Sandstone Formation confirms that hybrid event beds can form in a variety of ways, even in the same system, and that different flow transformation mechanisms may operate even during the passage of a single flow.

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“…Slow extension, as is evidenced by the synsedimentary fault at Diamond Rocks, was likely to be caused by normal gravitational processes (differential loading) on the delta front (Back & Morley, ), but it is also not possible to rule out the potential role of early Variscan tectonics ( cf . Tanner et al ., ). The fact that the diapir only ever had a reactive phase explains its crudely triangular shape (Fig.…”

Section: Interpretation and Comparison With Contemporaneous Mud Diapirsmentioning

confidence: 99%

“…). As at Knockroe, another mechanism of differential loading or seismicity may have induced movement, perhaps related to the Variscan Orogeny (Tanner et al ., ). The George's Head diapir is interpreted herein as having evolved predominantly through downbuilding (Fig.…”

Section: Interpretation and Comparison With Contemporaneous Mud Diapirsmentioning

confidence: 99%

Early burial mud diapirism and its impact on stratigraphic architecture in the Carboniferous of the Shannon Basin, County Clare, Ireland

et al. 2018

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Delta fronts are often characterized by high rates of sediment supply that result in unstable slopes and a wide variety of soft‐sediment deformation, including the formation of overpressured and mobile muds that may flow plastically during early burial, potentially forming mud diapirs. The coastal cliffs of County Clare, western Ireland, expose Pennsylvanian (Namurian) delta‐front deposits of the Shannon Basin at large scale and in three dimensions. These deposits include decametre‐scale, internally chaotic mudstone masses that clearly impact the surrounding sedimentary strata. Evidence indicates that these were true mud (unlithified sediment) diapirs that pierced overlying strata. This study documents a well‐exposed ca 20 m tall mud diapir and its impact on the surrounding mouth‐bar deposits of the Tullig Cyclothem. A synsedimentary fault and associated rollover dome, evident from stratal thicknesses and the dip of the beds, define one edge of the diapir. These features are interpreted as recording the reactive rise of the mud diapir in response to extensional faulting along its margin. Above the diapir, heterolithic sandstones and siltstones contain evidence for the creation of localized accommodation, suggesting synsedimentary filling, tilting and erosion of a shallow sag basin accommodated by the progressive collapse of the diapir. Two other diapirs are investigated using three‐dimensional models built from ‘structure from motion’ drone imagery. Both diapirs are interpreted to have grown predominantly through passive rise (downbuilding). Stratal relationships for all three diapirs indicate that they were uncompacted and fluid‐rich mud beds that became mobilized through soft‐sediment deformation during early burial (i.e. <50 m, likely <10 m depth). Each diapir locally controlled the stratigraphic architecture in the shallow subsurface and potentially influenced local palaeocurrents on the delta. The mud diapirs studied herein are distinct from deeper ‘shale diapirs’ that have been inferred from seismic sections worldwide, now largely disputed.

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Kinematic retro-modelling of a cross-section through a thrust-and-fold belt: the Western Irish Namurian Basin

Cited by 22 publications

References 52 publications

Kinematic 3-D Retro-Modeling of an Orogenic Bend in the South Limón Fold-and-Thrust Belt, Eastern Costa Rica: Prediction of the Incremental Internal Strain Distribution

Kinematic 3-D Retro-Modeling of an Orogenic Bend in the South Limón Fold-and-Thrust Belt, Eastern Costa Rica: Prediction of the Incremental Internal Strain Distribution

Variable character and diverse origin of hybrid event beds in a sandy submarine fan system, Pennsylvanian Ross Sandstone Formation, western Ireland

Early burial mud diapirism and its impact on stratigraphic architecture in the Carboniferous of the Shannon Basin, County Clare, Ireland

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