Thrust zones and shear zones of the margin of the Namaqua and Kheis mobile belts, southern Africa
24
Citation
16
Reference
10
Related Paper
Citation Trend
Keywords:
Thrust fault
The Himalayan thrust belt is often cited as an example of a thrust system that propagated from hinterland to foreland; however, this kinematic sequence is not well documented, and the process of formation of the thrust belt has not been well supported. This study uses forward modeling and timing data to reveal a detailed view of the evolution of the central Himalayan thrust belt from the footwall of the South Tibetan detachment system southward to the Main Frontal thrust. By using a reasonable configuration of undeformed stratigraphy, the surface deformation in western Nepal can be dynamically reproduced, confirming that the cross sections from which the undeformed sections were derived are viable and propagated from hinterland to foreland. In addition, this study yields detailed step-by-step reconstructions of three cross sections and is the first of its kind in any thrust belt system. These detailed views are useful for understanding and bracketing erosion data, the basin sediments, and geodynamic models. Modeling shortening estimates are between 495 and 733 km from the Main Frontal thrust to the South Tibetan detachment system, and are within the range predicted for shortening in western Nepal obtained from balanced cross sections (485–743 km). Thus, the Himalayan thrust belt in western Nepal is essentially a forward-propagating thrust belt from hinterland to foreland, with minor out-of-sequence (<5 km) thrust and normal faults. The data and the forward modeling support a conventional wedge model for the development of the central Himalayan thrust belt.
Main Central Thrust
Cite
Citations (59)
In the Central Pyrenees, the influence of syn- to post- orogenic deposits on the southern foreland may have influenced the late evolution. During middle to late Eocene, thrust deformation in the Pyrenean fold-and-thrust belt migrated to the south with in-sequence piggy-back thrust development. Then from Oligocene to Miocene, conglomerates sourced from the axial zone buried the fold and thrust belt until the Ebro foreland basin. At the same time thrust activity migrated from the front to the internal parts of the orogen reactivating major thrust in the foreland fold and thrust belt and in the south of the Axial zone. The reason for the out of sequence thrust activity is still a matter a debate. Moreover, thermal modeling of thermo-chronometric data and recent (U-Th)/He analysis on apatites in this area indicates conglomerate infill in excess of 2 km thick. Although the effect of changing orogen critical taper through wedge top sedimentation is known from theoretical studies, it has been difficult to demonstrate this behavior for natural system. The main objective of this study is to understand coupling between tectonics and surface processes during formation of the Pyrenean fold and thrust belt, the causes of out of sequence thrust activity, and the possible relationship with conglomeratic wedge top sedimentation. We use an Arbitrary Lagrangian Eulerian (ALE) numerical model called Sopale to model the thin-skinned fold and thrust belt at upper crustal scales (7 km depth and 200 km long). Sopale takes into account the main parameters that influence the development of a fold and thrust belt such as flexure, strain softening of materials, erosion and sedimentation. Main controlling factors in these models include a detachment horizon, strain-softening of strong layers, flexural isostasy and the addition of erosion and sedimentation processes. The modeling is first focusing on the syn-orogenic part with wedge development coupled with syn-orogenic sedimentation. The sedimentation, affecting the taper angle, clearly modifies the behavior of the wedge with the development of long thrust sheets, over the decollement level. Then, a sediment cover that progrades towards the south with time is added to reproduce the syn- to post- orogenic infilling of the conglomerates. The numerical models of FTB formation show a strong sensitivity to syn-tectonic deposition. This presentation was supported by the EUROCORES programme TOPO-EUROPE of the European Science Foundation.
Cite
Citations (0)
The Rioni foreland fold-and-thrust belt is part of the Greater Caucasus pro-wedge and is one of the most important examples of the collision-driven far-field deformation of the Arabia-Eurasia convergence zone. Here we show the deformation structural style of the Rioni foreland fold-and-thrust belt based on seismic reflection profiles and regional balanced cross-section. The main style of deformation within the Rioni foreland fold-and-thrust belt is represented by a set of fault-propagation folds, duplexes, and triangle zone. The regional balanced cross-section shows that fault-propagation folds above the upper detachment level can develop by piggyback and break-back thrust sequences. Formation of fault-bend fold duplex structures above the lower detachment is related to piggyback thrust sequences. A balanced section restoration of compressional structures across the Rioni foreland fold-and-thrust belt provides a minimum estimate of shortening of −40%, equivalent −42.78 km. The synclines within the Rioni foreland fold-and-thrust belt are filled by the Middle Miocene-Pleistocene shallow marine and continental syn-tectonic sediments, forming a series of typical thrust-top basins. Fault-propagation folds and duplex structures formed the main structure of the thrust-top basin. The evolution of the thrust-top basins was mainly controlled by the kinematics of thrust sequences. Using end-member modes of thrust sequences, the thrust-top basins are divided into: 1) Type I-piggyback basin, 2) Type II-break-back basin, and 3) Type III—formation of thrust-top basin characterized by bi-vergent geometry and related to combined, piggyback and piggyback back thrust sequences.
Thrust fault
Syncline
Anticline
Cite
Citations (4)
Early to Middle Eocene radiolarian fossils were newly found from a red shale bed of the uppermost part of the Sarugawa Formation in the Hidaka foreland fold-and-thrust belt, Hokkaido. Considering previous and our results, the age of the Sarugawa Formation was confirmed to range from Turonian-Coniacian to Early-Middle Eocene. This provides fundamental data for the reconstruction of structural settings just before the initiation of growth of the Hidaka foreland fold-and-thrust belt.
Cite
Citations (4)
Cite
Citations (46)
The Rioni foreland fold-and-thrust belt which is part of the western Greater Caucasus pro-wedge is located between the Lesser Caucasus and the Greater Caucasus orogens and is one of the most important examples of the collision-driven far-field deformation of the Arabia-Eurasia convergence zone (Alania et al., 2022). The Rioni foreland fold-and-thrust belt sedimentary infill consists of pre-and syn-orogenic sequences. Moreover, recent GPS and earthquake data indicate that the Rioni foreland fold-and-thrust belt is still tectonically active and the earthquakes’ focal mechanisms are mainly thrust faults (e.g., Tibaldi et al., 2017; Tsereteli et al., 2016).Fault-related folding and wedge thrust folding theories were used to interpret 2D depth-migrated seismic reflection profiles and to construct the regional balanced and restored cross-sections across Rioni foreland fold-and-thrust belt. The balanced cross-section is approximately parallel to the trust transport direction and has a total length of 64 km. On the other hand, the amount of shortening obtained for this part of the regional balanced cross-section is 40% (-42.78km).The main style of the deformation within the thin-skinned Rioni foreland fold-and-thrust belt is represented by a set of growth fault-propagation folds, duplexes, triangle zone, and a series of thrust-top basins. The evolution of the trust-top basins was mainly controlled by the kinematics of thrust sequences and competing growth fault-propagation folds and building compressional structures of the Rioni foreland fold-and-thrust belt was governed by the Greater Caucasus basement crustal-scale duplexes propagation along detachment horizons within the cover-generating thin-skinned structures.Acknowledgment: This work was supported by Shota Rustaveli National Science Foundation (SRNSF) [Structural model of the Rioni foreland fold-and-thrust belt and the Southern Slope of the Greater Caucasus (The Tekhuri river gorge area) Grant #: PHDF-21-087]References:Alania, V., et al. (2022). Deformation structural style of the Rioni foreland fold-and-thrust belt, western Greater Caucasus: Insight from the balanced cross-section. Frontiers in Earth Science, 10:968386.Tibaldi, A., et al. (2017). Active inversion tectonics, simple shear folding and back-thrusting at Rioni Basin, Georgia. Journal of Structural Geology 96, 35-53.Tsereteli, N., et al. (2016). Active tectonics of central-western Caucasus, Georgia. Tectonophysics 691, 328-344.
Thrust fault
Décollement
Wedge (geometry)
Cite
Citations (0)
Syn-orogenic sediments provide fundamental information on the timing and modes of deformation in fold and thrust belts. In this study, biostratigraphic and structural analyses on syn-orogenic deposits have been carried out in a key area of the southern Apennines in order to constrain the evolution of the Miocene thrust front and adjacent foreland basin. Our data indicate that, by middle Miocene times, a thin-skinned fold and thrust belt had developed in the study area. This was characterised by a complex tectonic setting, including: (i) a wide foreland basin area to the NE, ahead of the thrust front, where volcaniclastic and then quartz-rich ("Numidian") sandstones were deposited; and (ii) a series of thrust-top basin depocentres—hosting different siliciclastic and mixed detrital carbonate-siliciclastic successions— SW of the thrust front. Foreland propagation of the deformation produced intense folding of the foredeep succession. Later shortening and refolding around steeply dipping axial surfaces affected all of the tectonic units exposed in the study area. The latter deformation could be associated with Pliocene "en-masse" emplacement of the whole thin-skinned fold and thrust belt — as a major allochthonous detachment sheet—on top of the Apulian foreland sequence which presently underlies the exposed thrust sheets.
Siliciclastic
Imbrication
Cite
Citations (8)
Within the Mediterranean region, Cenozoic deformation of the Western Alps and the West to East Carpathians has resulted in two different styles of foreland fold and thrust belt. The most prominent difference between the two belts is the presence (Carpathians) or absence (Western Alps) of contemporaneous back‐arc extension, but other important differences in structure, topography and metamorphism also exist. These differences in thrust belt style developed mainly during the final stages of thrust belt evolution and appear to reflect fundamental differences in the tectonic settings of the Western Alps and the Carpathians in middle and late Cenozoic time. In particular, they appear to be the result of convergence that is in the first case driven primarily by major plate motions and in the second case only by local motions of small lithospheric flakes or fragments. We suggest that the structural styles developed in these two mountain belts may be useful in identifying mountain belts that have evolved in similar tectonic settings elsewhere in the world. In this respect, the Western Alps and the Carpathians can be regarded as typical examples of two different styles of foreland fold and thrust belt (or more properly as end‐member examples within a broad spectrum of foreland fold and thrust belt styles). We propose that continental subduction zones and orogenic belts can be loosely divided into segments that show no major back‐arc extensional deformation adjacent to the belt (the Western Alps) and segments that exhibit back‐arc extension contemporaneously with thrusting (the Carpathians). The former are found in areas where the rate of overall plate convergence exceeds the rate of subduction, and are commonly typified by extensive involvement of crystalline basement in thrusting, exposure of high grade metamorphic rocks at the surface, high topographic elevation, and large amounts of erosion (tens of kilometers). The latter are found in areas where the rate of subduction exceeds the rate of overall plate convergence and are commonly typified by thrust belts with little to no involvement of crystalline basement in thrusting, low grade to no metamorphism, low topographic elevation, little erosion and, in some instances, an anomalously deep foredeep basin system.
Mountain formation
Back-arc basin
Cite
Citations (184)
In the Oligocene to earliest Miocene the entire southern Pyrenean foreland fold and thrust belt was backfilled and buried in up to 3 km of syntectonic continental conglomerates from the range's own erosional debris. Then, starting in the mid to late Miocene, the Pyrenees were exhumed by erosional excavation to their present relief. A model is proposed for this unusual development whereby late Eocene–Oligocene tectonic uplift of the margins of the Ebro basin raised local base level and blocked normal dispersal of erosional debris to adjacent oceans, thus causing the basin to fill then backfill northwards across the entire southern flank of the Pyrenees. Subsequent Miocene rifting of the Catalan Mediterranean margin, and the Messinian salinity crisis, lowered base level allowing the Ebro River to cut headward, capture the Ebro basin, and re-excavate the Pyrenees.
Cite
Citations (143)