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C K Morley - One of the best experts on this subject based on the ideXlab platform.
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Inversion Tectonics during continental rifting the turkana cenozoic rifted zone northern kenya
Tectonics, 2005Co-Authors: Le B Gall, William Vetel, C K MorleyAbstract:[1] Remote sensing data and revised seismic reflection profiles provide new insights about the origin of inverted deformation within Miocene-Recent basins of the Turkana rift (northern Kenya) in the eastern branch of the East African rift system. Contractional structures are dominated by weakly inverted sets of fault blocks within <3.7 Myr old synrift series. Most of reverse extensional faults involve components of oblique-slip, whereas associated hanging wall folds are characterized by large wavelength upright folding. The area of basin Inversion is restricted to a 40 × 100 km elongated zone overlying a first-order N140°E trending fault zone in the basement, referred to as the N'Doto transverse fault zone (NTFZ). In the proposed kinematic model, Inversion Tectonics is assigned to permutation of principal stress axes (σ1/σ2) in addition to the clockwise rotation of extension (from nearly N90°E to N130°E) during Pliocene. The transition from pure extension (Miocene) to a wrench faulting regime (Pliocene) first results in the development of T-type fault networks within a dextrally reactivated shear zone (NTFZ). Inversion Tectonics occurred later (<3.7 Ma) in response to a still rotated (∼20°) shortening axis (σ1) oriented N40°E that caused the oblique compression of earlier (NS to N20°E) extensional structures within the NTFZ. The origin of basin Inversion and strain concentration in the Turkana rift is thus directly linked to a crustal weakness zone, transverse to the rift axis, and involving steep prerift anisotropies.
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Inversion Tectonics during continental rifting: The Turkana Cenozoic rifted zone, northern Kenya
Tectonics, 2005Co-Authors: B. Le Gall, William Vetel, C K MorleyAbstract:[1] Remote sensing data and revised seismic reflection profiles provide new insights about the origin of inverted deformation within Miocene-Recent basins of the Turkana rift (northern Kenya) in the eastern branch of the East African rift system. Contractional structures are dominated by weakly inverted sets of fault blocks within
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Re-evaluation of mobile shale occurrences on seismic sections of the Champion and Baram deltas, offshore Brunei
Geological Society London Special Publications, 2003Co-Authors: Pieter Van Rensbergen, C K MorleyAbstract:3D seismic data in the Baram and Champion delta provinces offshore Brunei show that regions thought to be occupied entirely by chaotic seismic data and conventionally interpreted as shale diapirs, are regions of dimmed, but coherent reflectivity. Such data indicate shale diapir masses are not present, instead dimming can be attributed to sediment intrusive complexes, overpressured fluids and gas clouds, or processing artefacts. In this way significant delta structures are masked on 2D seismic data, which are important to interpret delta tectonic evolution. The Middle Miocene-Recent Champion and Baram deltaic provinces are characterized by typical gravity Tectonics-related structures. However, being situated on an active margin they are also affected by episodic development of contractional structures, which are located on older reactive shale bulges and result in Inversion of motion on some growth faults. The emplacement of shale pipes, gas clouds and intrusive complexes is generally relatively late (Pliocene) in comparison with the underlying reactive diapirs (Late Miocene) and their emplacement events may be separated in time by several million years. Late overpressured systems may be related to phases of pore fluid pressure increase during or following periods of Inversion Tectonics, which resulted in phases of enhanced fluid migration in the basin, where fluids were either expelled laterally oceanwards, or vertically
A. K. Dubey - One of the best experts on this subject based on the ideXlab platform.
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Role of Inversion Tectonics in structural development of the Himalaya
Journal of Asian Earth Sciences, 2010Co-Authors: A. K. DubeyAbstract:Abstract Analysis of surface and subsurface structures, variation of shortening amounts obtained by restoration of deformed cross-sections, and occurrence of younger hangingwall rocks over the older footwall rocks across the Vaikrita Thrust in the Higher Himalaya suggests reactivation of early normal faults as thrusts. Based on this, an Inversion Tectonics model is proposed for structural development of the Himalaya. The model explains the geometrical shape of the Himalaya as primary arcuation and helps in resolving superimposed deformation in the region.
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younger hanging wall rocks along the vaikrita thrust of the high himalaya a model based on Inversion Tectonics
Himalayan Journal of Sciences, 2008Co-Authors: A. K. Dubey, S S BhakuniAbstract:Nd values from -23 to -28 similar to the Lesser Himalayan rocks occurring in the footwall of the Munsiari Thrust whereas the metasedimentary rocks of the Vaikrita Group show Nd values from -14 to -19. The Sr isotope study revealed that the Vaikrita Group shows partial equilibration at 500 Ma and the Munsiari Group has undergone Sr isotope homogenization at 1800Ma. In absence of marker horizons, displacements along the Munsiari and Vaikrita thrusts are still a matter of speculation. However, the Munsiari rocks occur as klippen in the Lesser Himalaya and the klippe to fenster method reveals that the maximum displacement along the klippen thrust in the Simla klippe is of the order of ~ 40 km (Dubey and Bhat 1991). On the contrary, the trace of the Vaikrita Thrust is linear with occasional curves at oblique thrust ramps. Moreover, the Vaikrita Thrust has a weak geomorphic expression, which does not allow its mapping by satellite imagery. Mylonitization of the Vaikrita rocks can only be seen at the base but kyanite is uniformly distributed throughout the rock. The constituent minerals are coarse grained (size, 1-2 mm). In sharp contrast to these properties the constituent minerals of the Munsiari rocks are fine to medium grained (size, <1mm), kyanite is occasionally present in small pockets, and mylonitization is a common feature throughout the sequence. Class 2 and Class 3 fold patterns are typical of Vaikrita rocks indicating ductile deformation whereas the Munsiari rocks exhibit mostly Class 1C folds characteristic of deformation at comparatively upper levels of the Earth’s crust. Prominent stretching mineral lineation and presence of sheath folds suggest greater shear strain in the Munsiari rocks. The metamorphic episodes in the area can be broadly classified into two: (i) pre-Himalayan metamorphism, and (ii) Tertiary Himalayan metamorphism. The pre-Himalayan metamorphism is now well established in several parts of the Himalaya. For example, a metamorphic event, prior to the emplacement of the early Palaeozoic granitoids was recognized in the SE Zanskar (NW Himalaya) by Pognante et al. (1990). The mineral assemblage indicated high T and high P conditions of crystallization (T = 750 ± 500C; P = 12.0 ± 0.5 kbar). The Vaikrita rocks underwent a higher grade of metamorphism (lower granulite facies) as compared to the Munsiari rocks and the metamorphic reconstitution took place at a depth of ~30 km (Valdiya et al. 1999). The pre-Himalayan metamorphism was higher in metamorphic grade than the younger Himalayan metamorphism (Arita 1983). Different phases of the Himalayan metamorphism are now known (Hodges and Silverberg 1988). The first Himalayan metamorphism was associated with the initial collision between India and Eurasia and the subsequent metamorphism was related to thrusting along the MCT. The second metamorphic event (i.e. Himalayan) occurred at similar or lower T and at lower P. The rocks show a normal metamorphism decreasing upward in metamorphic grade toward the overlying Tethyan sediments (Arita 1983). The present study in the Garhwal-Kumaun High Himalaya help in understanding the occurrence of the younger hanging wall Vaikrita Group above the older footwall Munsiari Formation along the Vaikrita Thrust. The phenomenon is explained by an Inversion Tectonics based model where normal faulting and metamorphism was followed by thrusting characterized by displacement amount less than the displacement during the early normal faulting. The study takes into account the simple shear strains associated with the piggy back sequence of thrusting and pure shear strains associated with folding to explain the present structural set-up of the region.
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Younger hanging wall rocks along the Vaikrita Thrust of the High Himalaya: A model based on Inversion Tectonics
Himalayan Journal of Sciences, 2008Co-Authors: A. K. Dubey, S S BhakuniAbstract:Nd values from -23 to -28 similar to the Lesser Himalayan rocks occurring in the footwall of the Munsiari Thrust whereas the metasedimentary rocks of the Vaikrita Group show Nd values from -14 to -19. The Sr isotope study revealed that the Vaikrita Group shows partial equilibration at 500 Ma and the Munsiari Group has undergone Sr isotope homogenization at 1800Ma. In absence of marker horizons, displacements along the Munsiari and Vaikrita thrusts are still a matter of speculation. However, the Munsiari rocks occur as klippen in the Lesser Himalaya and the klippe to fenster method reveals that the maximum displacement along the klippen thrust in the Simla klippe is of the order of ~ 40 km (Dubey and Bhat 1991). On the contrary, the trace of the Vaikrita Thrust is linear with occasional curves at oblique thrust ramps. Moreover, the Vaikrita Thrust has a weak geomorphic expression, which does not allow its mapping by satellite imagery. Mylonitization of the Vaikrita rocks can only be seen at the base but kyanite is uniformly distributed throughout the rock. The constituent minerals are coarse grained (size, 1-2 mm). In sharp contrast to these properties the constituent minerals of the Munsiari rocks are fine to medium grained (size,
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younger hanging wall rocks along the vaikrita thrust of the high himalaya a model based on Inversion Tectonics
Journal of Asian Earth Sciences, 2007Co-Authors: A. K. Dubey, S S BhakuniAbstract:Abstract In sharp contrast to the common observed characteristic of areas of thrust Tectonics, where older rocks are thrust over younger, along the Vaikrita Thrust in the High Himalaya younger hanging wall rocks (i.e. Vaikrita Group—Late Mesoproterozoic to Early Neoproterozoic) lie above the older footwall rocks (i.e. Munsiari Formation—Paleoproterozoic). The phenomenon is explained by an Inversion Tectonics-based model where normal faulting and metamorphism were followed by thrusting, in which the thrust displacement was less than the displacement during the earlier normal faulting. The present day hanging wall tilt towards north may have been caused by a later thrust, initiated as a piggy back sequence, accompanied by folding and Himalayan metamorphism.
S S Bhakuni - One of the best experts on this subject based on the ideXlab platform.
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Younger hanging wall rocks along the Vaikrita Thrust of the High Himalaya: A model based on Inversion Tectonics
Himalayan Journal of Sciences, 2008Co-Authors: A. K. Dubey, S S BhakuniAbstract:Nd values from -23 to -28 similar to the Lesser Himalayan rocks occurring in the footwall of the Munsiari Thrust whereas the metasedimentary rocks of the Vaikrita Group show Nd values from -14 to -19. The Sr isotope study revealed that the Vaikrita Group shows partial equilibration at 500 Ma and the Munsiari Group has undergone Sr isotope homogenization at 1800Ma. In absence of marker horizons, displacements along the Munsiari and Vaikrita thrusts are still a matter of speculation. However, the Munsiari rocks occur as klippen in the Lesser Himalaya and the klippe to fenster method reveals that the maximum displacement along the klippen thrust in the Simla klippe is of the order of ~ 40 km (Dubey and Bhat 1991). On the contrary, the trace of the Vaikrita Thrust is linear with occasional curves at oblique thrust ramps. Moreover, the Vaikrita Thrust has a weak geomorphic expression, which does not allow its mapping by satellite imagery. Mylonitization of the Vaikrita rocks can only be seen at the base but kyanite is uniformly distributed throughout the rock. The constituent minerals are coarse grained (size, 1-2 mm). In sharp contrast to these properties the constituent minerals of the Munsiari rocks are fine to medium grained (size,
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younger hanging wall rocks along the vaikrita thrust of the high himalaya a model based on Inversion Tectonics
Himalayan Journal of Sciences, 2008Co-Authors: A. K. Dubey, S S BhakuniAbstract:Nd values from -23 to -28 similar to the Lesser Himalayan rocks occurring in the footwall of the Munsiari Thrust whereas the metasedimentary rocks of the Vaikrita Group show Nd values from -14 to -19. The Sr isotope study revealed that the Vaikrita Group shows partial equilibration at 500 Ma and the Munsiari Group has undergone Sr isotope homogenization at 1800Ma. In absence of marker horizons, displacements along the Munsiari and Vaikrita thrusts are still a matter of speculation. However, the Munsiari rocks occur as klippen in the Lesser Himalaya and the klippe to fenster method reveals that the maximum displacement along the klippen thrust in the Simla klippe is of the order of ~ 40 km (Dubey and Bhat 1991). On the contrary, the trace of the Vaikrita Thrust is linear with occasional curves at oblique thrust ramps. Moreover, the Vaikrita Thrust has a weak geomorphic expression, which does not allow its mapping by satellite imagery. Mylonitization of the Vaikrita rocks can only be seen at the base but kyanite is uniformly distributed throughout the rock. The constituent minerals are coarse grained (size, 1-2 mm). In sharp contrast to these properties the constituent minerals of the Munsiari rocks are fine to medium grained (size, <1mm), kyanite is occasionally present in small pockets, and mylonitization is a common feature throughout the sequence. Class 2 and Class 3 fold patterns are typical of Vaikrita rocks indicating ductile deformation whereas the Munsiari rocks exhibit mostly Class 1C folds characteristic of deformation at comparatively upper levels of the Earth’s crust. Prominent stretching mineral lineation and presence of sheath folds suggest greater shear strain in the Munsiari rocks. The metamorphic episodes in the area can be broadly classified into two: (i) pre-Himalayan metamorphism, and (ii) Tertiary Himalayan metamorphism. The pre-Himalayan metamorphism is now well established in several parts of the Himalaya. For example, a metamorphic event, prior to the emplacement of the early Palaeozoic granitoids was recognized in the SE Zanskar (NW Himalaya) by Pognante et al. (1990). The mineral assemblage indicated high T and high P conditions of crystallization (T = 750 ± 500C; P = 12.0 ± 0.5 kbar). The Vaikrita rocks underwent a higher grade of metamorphism (lower granulite facies) as compared to the Munsiari rocks and the metamorphic reconstitution took place at a depth of ~30 km (Valdiya et al. 1999). The pre-Himalayan metamorphism was higher in metamorphic grade than the younger Himalayan metamorphism (Arita 1983). Different phases of the Himalayan metamorphism are now known (Hodges and Silverberg 1988). The first Himalayan metamorphism was associated with the initial collision between India and Eurasia and the subsequent metamorphism was related to thrusting along the MCT. The second metamorphic event (i.e. Himalayan) occurred at similar or lower T and at lower P. The rocks show a normal metamorphism decreasing upward in metamorphic grade toward the overlying Tethyan sediments (Arita 1983). The present study in the Garhwal-Kumaun High Himalaya help in understanding the occurrence of the younger hanging wall Vaikrita Group above the older footwall Munsiari Formation along the Vaikrita Thrust. The phenomenon is explained by an Inversion Tectonics based model where normal faulting and metamorphism was followed by thrusting characterized by displacement amount less than the displacement during the early normal faulting. The study takes into account the simple shear strains associated with the piggy back sequence of thrusting and pure shear strains associated with folding to explain the present structural set-up of the region.
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younger hanging wall rocks along the vaikrita thrust of the high himalaya a model based on Inversion Tectonics
Journal of Asian Earth Sciences, 2007Co-Authors: A. K. Dubey, S S BhakuniAbstract:Abstract In sharp contrast to the common observed characteristic of areas of thrust Tectonics, where older rocks are thrust over younger, along the Vaikrita Thrust in the High Himalaya younger hanging wall rocks (i.e. Vaikrita Group—Late Mesoproterozoic to Early Neoproterozoic) lie above the older footwall rocks (i.e. Munsiari Formation—Paleoproterozoic). The phenomenon is explained by an Inversion Tectonics-based model where normal faulting and metamorphism were followed by thrusting, in which the thrust displacement was less than the displacement during the earlier normal faulting. The present day hanging wall tilt towards north may have been caused by a later thrust, initiated as a piggy back sequence, accompanied by folding and Himalayan metamorphism.
Maurice Pagel - One of the best experts on this subject based on the ideXlab platform.
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Lower Paleogene denudation of Upper Cretaceous cover of the Morvan Massif and southeastern Paris Basin (France) revealed by AFT thermochronology and constrained by stratigraphy and paleosurfaces
Tectonophysics, 2013Co-Authors: Jocelyn Barbarand, Florence Quesnel, Maurice PagelAbstract:Low-temperature thermochronology data have been acquired from outcrop samples from the southeastern edge of the Paris Basin (Morvan). They provide indications about the former sedimentary cover, its denudation and about Inversion Tectonics in the Paris Basin. Apatite fission-track data acquired on Variscan granites and Triassic sandstones reveal that the basement was subjected to temperatures of about 70 ± 10 °C during the Late Cretaceous. We suggest that the peak temperature was generated by an Upper Cretaceous sedimentary cover of low thermal-conductivity chalk. Additional stratigraphic, sedimentological, paleogeographic, paleoweathering, and continental paleosurface data support the reconstruction of this chalk paleocover and of its erosion. This former blanketing sequence was removed during the Early Paleogene regional Inversion episode which affected the southern edge of the Basin intensively and was related to far-field compression between Europe and Africa. This study shows that (i) for the SE border of the intracontinental Paris Basin, kilometer-scale vertical deformation occurred, (ii) the sedimentary sequences of the Paris Basin covered considerably larger areas than the present contours of the sediment fill, (iii) paleoweathering and erosion processes later removed the sedimentary cover rather quickly (< 10 My) due to Inversion Tectonics.
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Lower Paleogene denudation of Upper Cretaceous cover of the Morvan Massif and southeastern Paris Basin (France) revealed by AFT thermochronology and constrained by stratigraphy and paleosurfaces
Tectonophysics, 2013Co-Authors: Jocelyn Barbarand, Florence Quesnel, Maurice PagelAbstract:Abstract Low-temperature thermochronology data have been acquired from outcrop samples from the southeastern edge of the Paris Basin (Morvan). They provide indications about the former sedimentary cover, its denudation and about Inversion Tectonics in the Paris Basin. Apatite fission-track data acquired on Variscan granites and Triassic sandstones reveal that the basement was subjected to temperatures of about 70 ± 10 °C during the Late Cretaceous. We suggest that the peak temperature was generated by an Upper Cretaceous sedimentary cover of low thermal-conductivity chalk. Additional stratigraphic, sedimentological, paleogeographic, paleoweathering, and continental paleosurface data support the reconstruction of this chalk paleocover and of its erosion. This former blanketing sequence was removed during the Early Paleogene regional Inversion episode which affected the southern edge of the Basin intensively and was related to far-field compression between Europe and Africa. This study shows that (i) for the SE border of the intracontinental Paris Basin, kilometer-scale vertical deformation occurred, (ii) the sedimentary sequences of the Paris Basin covered considerably larger areas than the present contours of the sediment fill, (iii) paleoweathering and erosion processes later removed the sedimentary cover rather quickly (
Fernando Calamita - One of the best experts on this subject based on the ideXlab platform.
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Behaviour of minor arcuate shapes hosted in curved fold-and-thrust belts: an example from the Northern Apennines (Italy)S Satolli et al.Minor arcs in curved fold-and-thrust belts
Geological Magazine, 2019Co-Authors: Sara Satolli, Simone Agostini, Fernando CalamitaAbstract:AbstractArcuate fold-and-thrust belts have been extensively studied in the literature. Less attention, however, has been paid to the characteristics of local-scale arcuate structures, meaning 5–10 km long fold or thrust traces that display map-view curvature. Nevertheless, detailed investigation of small arcuate structures hosted in major arcs can contribute to understanding the pervasiveness of deformation mechanisms. We performed a combined geological and palaeomagnetic study on 21 sites from ac. 60 km2area in the Northern Apennines in order to analyse minor arcs at a kilometric scale. As evidenced by the geological and structural analysis performed on the 21 sites, the fold axial trend changes from N–S to NW–SE in the study area. The comparison with palaeomagnetic results shows the lack of correlation between vertical axis rotations and fold axial trends. As a consequence, the minor arcuate shapes of thrusts and related folds are interpreted as mostly primary features inherited from the geometry of the palaeomargin, represented by pre-orogenic faults, according to a context of Inversion Tectonics.
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Lateral variations in tectonic style across cross-strike discontinuities: an example from the Central Apennines belt (Italy)
International Journal of Earth Sciences, 2014Co-Authors: Sara Satolli, Paolo Pace, Mauro Gabriele Viandante, Fernando CalamitaAbstract:In foreland thrust belts, abrupt lateral changes in tectonic style, structural–stratigraphic features, and topography usually occur across cross-strike faults. The Central Apennines of Italy offer an exceptional scenario of lateral variations in tectonic setting. Here, the Sangro Volturno oblique thrust ramp (SVOTR) represents the outer thrust front of the Pliocene–Quaternary foreland thrust system, confining southward the axial culmination of the orogen that occurs in the Central Apennines. We present an interpretation of the Pliocene–Quaternary evolution of this cross-strike fault through an integrated dataset including structural-geological mapping and subsurface onshore seismic reflection profiles. The interpretation of the structural framework is augmented by the analysis of low-temperature thermochronometers from 32 new sites extending across the subsurface transverse structure. As evidenced by seismic line interpretation, the localization and development of the SVOTR have been influenced by inherited extensional faults within a positive Inversion Tectonics context. The regional distribution of the maximum paleotemperature values across the SVOTR constrains the original extent of the allochthonous thrust sheet over all its hanging-wall and footwall blocks. The Pliocene–Quaternary thrusting and Inversion of SVOTR caused the strong hanging-wall uplift, which brought to the complete erosion of the allochthonous units and the exhumation of the Adria units. The integrated analysis of low-temperature thermochronometers and structural evidence as applied in the study case can define the role of major cross-strike discontinuities in foreland thrust belts, by constraining and verifying their Tectonics Inversion significance and the amount of related exhumation.
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Analogue modeling of positive Inversion Tectonics along differently oriented pre-thrusting normal faults: An application to the Central-Northern Apennines of Italy
Geological Society of America Bulletin, 2014Co-Authors: Alessandra Di Domenica, Lorenzo Bonini, Fernando Calamita, Giovanni Toscani, Carla Galuppo, Silvio SenoAbstract:Inversion Tectonics represent a key process in many orogens worldwide. The related mechanisms of fault reactivation and the effects of an articulated preshortening setting on thrust and fold development are still challenging questions. Modes and geometries of Inversion have been the object of several analogue models. In this work, we analyzed the influence of an articulated high-angle preexisting discontinuity in the development of thrusts using sandbox modeling. The model geometry is based on the architecture of the major faults in the Central-Northern Apennines of Italy, where differently oriented Mesozoic–Cenozoic inherited extensional structures are clearly detectable and display contrasting styles of positive Inversion Tectonics. Quartz-sand is the analogue material adopted to model Mesozoic–Cenozoic sedimentary successions, and glass microbeads represent preexisting fault rocks. The geometry of the segmented preexisting structure is composed of two segments with the same dip (∼60°): one oblique and another orthogonal to the shortening direction. Our results show that different styles of positive Inversion Tectonics can coexist and that the obliquity angle between inherited structures and the shortening direction is a leading factor controlling the degree of Inversion: The oblique segment of the discontinuity exhibits a complete reactivation, whereas along the orthogonal segment, shortcut is the prevalent mechanism. The oblique element, moreover, represents a cross-strike discontinuity that guides the localization and curved geometry of the thrusts, compartmentalizing the deformation. Our findings can be applied to fold-and-thrust belts characterized by the presence of cross-strike discontinuities.
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the control of mechanical stratigraphy and Inversion Tectonics on thrust related folding along the curved northern apennines thrust front
RENDICONTI ONLINE DELLA SOCIETÀ GEOLOGICA ITALIANA, 2012Co-Authors: Paolo Pace, Sara Satolli, Fernando CalamitaAbstract:Controllo della stratigrafia meccanica e della tettonica d'Inversione sullo sviluppo delle macropieghe lungo il fronte arcuato dell'Appennino Settentrionale.Nei settori esterni di catena, pieghe legate a diversi meccanismi di faultrelated folding mostrano profili peculiari e sono controllate dalle caratteristiche meccaniche della successione coinvolta e/o da processi di Inversione tettonica. L'analisi geologico-strutturale ha permesso di ricondurre la geometria delle macroanticlinali dell'Appennino Settentrionale a meccanismi di fault-bend e fault-propagation folding, rispettivamente lungo le rampe obliqua e frontale del sovrascorrimento Olevano-Antrodoco-Sibillini. Lo sviluppo di diversi meccanismi di piegamento, che coinvolgono la stessa successione meccanicamente eterogenea, e la loro coesistenza lungo un sovrascorrimento arcuato e controllata da diversi processi di Inversione tettonica quali la riattivazione in compressione di faglie normali preesistenti o la loro decapitazione in shortcut da parte dei sovrascorrimenti.
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relationships between thrusts and normal faults in curved belts new insight in the Inversion Tectonics of the central northern apennines italy
Journal of Structural Geology, 2012Co-Authors: Alessandra Di Domenica, Sara Satolli, Antonio Turtu, Fernando CalamitaAbstract:Abstract The relationships between thrusts and normal faults represent primary constraints in the reconstruction of the modes and timing of pre-, syn- and post-orogenic deformation events in fold-and-thrust belts. Such relationships are well exposed in curved orogenic belts where the thrusts are oblique to the trend of normal faults. We study the NNE–SSW-trending Olevano-Antrodoco-Sibillini oblique thrust and its crosscutting relationships with NW–SE-trending normal faults in order to constrain the Neogene–Quaternary deformation history of the Central-Northern Apennine (Italy). The analysis of structural and geological data allowed us to reconstruct the geometric and kinematic constraints of two Inversion events: 1 – During the Pliocene, positive Inversion reactivated the NNE–SSW-trending pre-existing Ancona-Anzio normal fault as the Olevano-Antrodoco-Sibillini oblique thrust ramp and caused the shortcut of NW–SE-oriented normal faults; 2 – During the Quaternary, negative Inversion reactivated NW–SE-trending pre-thrusting normal faults. The growth of the NW–SE Quaternary normal faults causes seismicity and is responsible of the development of wide Quaternary intramontane basins. Their distribution and the related seismicity have been controlled and compartmentalized by NNE–SSW-trending oblique thrusts. Thus, the crosscutting relationships between thrusts and normal faults are crucial in seismic hazard assessment.
