Journal articles on the topic 'Contractional system'
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1
Miller, Robert B., and Scott R. Paterson. "Tectonic implications of syn- and post-emplacement deformation of the Mount Stuart batholith for mid-Cretaceous orogenesis in the North Cascades." Canadian Journal of Earth Sciences 29, no. 3 (March 1, 1992): 479–85. http://dx.doi.org/10.1139/e92-041.
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The 93–96 Ma Mount Stuart batholith intruded across the boundary between the Northwest Cascades thrust system and the crystalline core of the North Cascades. Although previously considered posttectonic, the northeast margin of the Mount Stuart batholith and its wall rocks have been involved in syn- to post-emplacement, southwest-directed thrusting and folding, and west-northwest stretching. Contraction ended shortly after emplacement, as indicated by high-temperature recrystallization in thrust-related mylonites of the pluton and by geochronological data, whereas west-northwest stretching continued for an unknown period of time. This is the best documented mid-Cretaceous contractional belt in the main part of the crystalline core. The shortening direction and timing are identical to that of southwest-vergent thrusts in the offset continuation of the core in British Columbia. The contractional belt provides a link between thrusting in the Northwest Cascades thrust system and deformation in the crystalline core.
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Gomes, Caroline J. S., Marcelo A. Martins-Neto, and Valéria E. Ribeiro. "Positive inversion of extensional footwalls in the southern Serra do Espinhaço, Brazil - insights from sandbox laboratory experiments." Anais da Academia Brasileira de Ciências 78, no. 2 (June 2006): 331–44. http://dx.doi.org/10.1590/s0001-37652006000200012.
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Analogue experiments were carried out to get insights into the processes governing positive inversion during the foreland propagating thrust tectonics in the southern Serra do Espinhaço, a Brasiliano/Panafrican foldthrust belt in southeast Brazil. In particular, model listric half-grabens were inverted by applying contractional displacement to the footwall blocks. We investigated two different inversion conditions in listric half-grabens: (i) extensional and contractional detachments at the same level and (ii) at different positions. The models revealed that the development of a forward-breaking thrust system occurs in the basin synrift deposits, by contractional translation of the extensional footwall block when the extensional and contractional master faults do not coincide. Our experiments show the tectonic imbrication between basement and synrift sequences which characterizes the southern Serra do Espinhaço, and support the location in the eastern mountain range domain of the Espinhaço rift master fault system, which is not exposed at the surface.
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Najafi, Mahdi, and Sahar Lajmorak. "Contractional salt-tectonic system in the south Dezful embayment, Zagros." Journal of Structural Geology 141 (December 2020): 104204. http://dx.doi.org/10.1016/j.jsg.2020.104204.
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Krisnabudhi, Alfathony, Benyamin Sapiie, Agus Men Riyanto, Adi Gunawan, and Febriana Fiona Rizky. "Mesozoic-Cenozoic Stratigraphy and Tectonic Development of the Southern Great Tarakan Basin, Northeast Borneo, Indonesia." Rudarsko-geološko-naftni zbornik 37, no. 1 (2022): 123–38. http://dx.doi.org/10.17794/rgn.2022.1.11.
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We analyzed the tectonics and stratigraphy of the Southern Great Tarakan Basin to determine its tectonic evolution during the Mesozoic-Cenozoic Eras, the evolution of basin geometry, and the potential of hydrocarbon using integrated surface and subsurface data. Southern Great Tarakan Basin can be divided into three sub-basins, Berau, Muara, and South Tarakan. They comprise deposits of Jurassic to Quaternary age, which can be assigned five mega sequences based on their lithological characteristics and tectonic development. We divide the tectonic events into four main phases; (1) contractional Jurassic-Cretaceous, (2) extensional Paleogene, (3) subsidence Early Neogene, and (4) contractional Late Neogene. The development of the strike-slip activity influenced the geometric evolution of the two sub-basins. NW-SE transpressional structures formed during the contraction phase caused most of the existing structure in Paleogene reactivated and inverted, followed by basement uplift and erosion. Consequently, the evolution of the transpressional system caused The Great Tarakan Basin to be divided into five sub-basins during the Late Miocene-Pliocene. Moreover, five horizons with hydrocarbon potential exist in the southern part of The Greater Tarakan Basin; three plays in the Berau Sub-basin, and two main plays in the Muara Sub-basin. The Late Neogene structures in the Berau Sub-basin control the accumulation, migration, and trapping mechanism, whereas these structures do not exist in Muara; hence, this sub-basin is dominated by stratigraphic traps.
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Franzese, Juan R., Leandro D’Elia, Andres Bilmes, Martin Muravchik, and Mariano Hernandez. "Superimposition of oligo-miocene extensional and contractional basins in the northpatagonian Andean retroarc: The Alumine Basin, Neuquen, Argentina." Andean Geology 38, no. 2 (August 9, 2011): 319. http://dx.doi.org/10.5027/andgeov38n2-a04.
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The Alumine Basin is a volcano-sedimentary depocentre located in the Andean retroarc at 39°S. It is the southern part of a major depositional system: the Bio Bio-Alumine Basin. Stratigraphical, geochronological, sedimentological and structural analysis allow us to conclude that the basin evolved through two stages: an Oligocene extensional stage filled with basalts and reworked volcaniclastic and pyroclastic deposits (Rancahue Formation) and a Miocene contractional stage, filled with alluvial and pyroclastic deposits covered by basaltic lavas (Chimehuin and Tipilihuque formations). The volcanic-rich (basaltic) infill of the extensional stage has a western provenance and was derived from widespread magmatic activity that took place during the Oligocene in the adjacent cordilleran axis. The contractional stage basin is an intramontane depocentre limited by uplifted blocks generated mainly by the inversion of Mesozoic extensional faults. It is strongly asymmetric and shows eastern provenance. Structural and geomorphological evidence indicate the existence of a non-depositional hiatus between the two stages.
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Favorito, Daniel A., and Eric Seedorff. "Laramide Uplift near the Ray and Resolution Porphyry Copper Deposits, Southeastern Arizona: Insights into Regional Shortening Style, Magnitude of Uplift, and Implications for Exploration." Economic Geology 115, no. 1 (January 1, 2020): 153–75. http://dx.doi.org/10.5382/econgeo.4697.
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Abstract This study integrates new geologic mapping and structural analysis with previous work near Walnut Canyon and Telegraph Canyon to address the style and magnitude of shortening and the relationship between contractional structures and porphyry preservation and localization between the Ray and Resolution porphyry copper deposits. Cenozoic extensional structures were superimposed on earlier contractional structures formed during the Laramide orogeny, which dates from ~80 to 50 Ma. This superposition requires that Cenozoic normal faults be restored prior to analysis of Laramide contractional structures and their relationship to nearby porphyry copper deposits. Five distinct sets of normal faults within the study area progressively tilted the region 65° east. The amount of extension was 10.3 km or 276%. Using key constraints such as offset strata, cutoff angles between faults and various units, and Laramide fault geometries, the study area was structurally reconstructed and verified using 2-D kinematic modeling of reverse fault offset and related folding. Total shortening is 7.2 km or 98%. Laramide reverse faults are interpreted as thick-skinned basement-cored uplifts, because they restore to moderate angles, have related fault-propagation folds, and involve significant crystalline basement rock. The Telegraph Canyon reverse fault has at least 5.3 km of offset, and the Walnut Canyon reverse fault has 3.2 km. The preferred estimate of the total vertical uplift for the fault system is 5.2 km but could be several kilometers greater. The restored strike direction of these faults combined with mid-Cenozoic erosion surfaces throughout the region suggests that this fault system may be responsible for the Laramide uplift of the Tortilla Mountains and Black Hills. In addition, most major porphyry centers appear to have been intruded into the footwall of this large uplift, with local examples including Ray and Resolution, suggesting that topography generated from this uplift may have been critical to preservation of these ore systems. Though definitive crosscutting relationships do not exist in the immediate map area, geologic relationships in a broader area suggest that shortening here began after 74 Ma and, in the Ray area, had ended by ~69 Ma and that porphyry formation postdated reverse faulting by as much as 5 m.y. to as little as <1 m.y.
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Miller, Robert B. "A mid-crustal contractional stepover zone in a major strike-slip system, North Cascades, Washington." Journal of Structural Geology 16, no. 1 (January 1994): 47–60. http://dx.doi.org/10.1016/0191-8141(94)90017-5.
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Mora, Andrés, Wilson Casallas, Richard A. Ketcham, Diego Gomez, Mauricio Parra, Jay Namson, Daniel Stocklie, Ariel Almendral, Wilmer Robles, and Badr Ghorbal. "Kinematic restoration of contractional basement structures using thermokinematic models: A key tool for petroleum system modeling." AAPG Bulletin 99, no. 08 (August 2015): 1575–98. http://dx.doi.org/10.1306/04281411108.
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Brankman, Charles M., and Atilla Aydin. "Uplift and contractional deformation along a segmented strike-slip fault system: the Gargano Promontory, southern Italy." Journal of Structural Geology 26, no. 5 (May 2004): 807–24. http://dx.doi.org/10.1016/j.jsg.2003.08.018.
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Fetrow, Anne C., Kathryn E. Snell, Russell V. Di Fiori, Sean P. Long, and Joshua W. Bonde. "Early Sevier orogenic deformation exerted principal control on changes in depositional environment recorded by the Cretaceous Newark Canyon Formation." Journal of Sedimentary Research 90, no. 9 (September 1, 2020): 1175–97. http://dx.doi.org/10.2110/jsr.2020.52.
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ABSTRACT Terrestrial sedimentary archives record critical information about environment and climate of the past, as well as provide insights into the style, timing, and magnitude of structural deformation in a region. The Cretaceous Newark Canyon Formation, located in central Nevada, USA, was deposited in the hinterland of the Sevier fold–thrust belt during the North American Cordilleran orogeny. While previous research has focused on the coarser-grained, fluvial components of the Newark Canyon Formation, the carbonate and finer-grained facies of this formation remain comparatively understudied. A more complete understanding of the Newark Canyon Formation provides insights into Cretaceous syndeformational deposition in the Central Nevada thrust belt, serves as a useful case study for deconvolving the influence of tectonic and climatic forces on sedimentation in both the North American Cordillera and other contractional orogens, and will provide a critical foundation upon which to build future paleoclimate and paleoaltimetry studies. We combine facies descriptions, stratigraphic measurements, and optical and cathodoluminescence petrography to develop a comprehensive depositional model for the Newark Canyon Formation. We identify six distinct facies that show that the Newark Canyon Formation evolved through four stages of deposition: 1) an anastomosing river system with palustrine interchannel areas, 2) a braided river system, 3) a balance-filled, carbonate-bearing lacustrine system, and 4) a second braided river system. Although climate undoubtedly played a role, we suggest that the deposition and coeval deformation of the synorogenic Newark Canyon Formation was in direct response to the construction of east-vergent contractional structures proximal to the type section. Comparison to other contemporary terrestrial sedimentary basins deposited in a variety of tectonic settings provides helpful insights into the influences of regional tectonics, regional and global climate, catchment characteristics, underlying lithologies, and subcrop geology in the preserved sedimentary record.
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Andrew, Joseph E. "Geologic map of southern Panamint Valley, southern Panamint Range, and central Slate Range, California, USA." Geosphere 18, no. 2 (March 10, 2022): 726–27. http://dx.doi.org/10.1130/ges02342.1.
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Abstract This detailed geologic map and supplemental digital data set1 examine and demonstrate the complex deformational history and reactivation relationships of the southern Panamint Valley area (California, USA), from active transtension of the Walker Lane belt, Miocene extension of the Basin and Range, multiple Mesozoic events related to subduction, and Neoproterozoic extension. This collection of map data focuses on the geometry, kinematics, and relative timing of deformation to understand the deformation history and effects of structural reactivation. Andrew and Walker (2009) used these geologic mapping data to palinspastically restore the Fish Canyon area of the Slate Range to overlapping the western Panamint Range at Goler Wash. Neogene extension and subsequent dextral transtension has created a complex network of faults via partial reactivation of Mesozoic and Neoproterozoic structures and has separated the Slate Range from the Panamint Range. The Neogene fault system changes from south to north from dextral strike-slip along the southern Panamint Valley fault to oblique normal slip along the Emigrant fault at a triple junction with the sinistral-oblique normal Manly Pass fault. The Mesozoic deformation history is different in the two ranges across Panamint Valley. The Slate Range was the hanging wall to Jurassic and Cretaceous contractional deformation; this same deformation in the Panamint Range to the east was localized along the western range flank with the majority of the Panamint Range thus being in the footwall to Mesozoic contraction. The western Panamint Range preserves migmatitic fabrics and deformation due to Jurassic contraction and plutonism. The Goldbug fault, along the western Panamint Range, places Paleoproterozoic to Mesoproterozoic rocks over Neoproterozoic to Cretaceous rocks. Jurassic contraction has top-to-the-northeast relative transport and the more discrete Cretaceous thrust faulting in the Panamint Range has top-to-the-east transport. The Butte Valley fault, previously recognized farther north of the map area in the Panamint Range, cuts Late Jurassic rocks and structures. Neoproterozoic to Cambrian sedimentary rocks with top-to-the-northeast contractional deformation occur as relative down-dropped block exposed east of the Butte Valley fault. The Butte Valley fault continues southward and is then deflected by Late Cretaceous thrust faulting on the Goldbug fault. Neoproterozoic deformation is more difficult to discern but is hypothesized to relate to abundant olistostromes mapped within the Kingston Peak Formation in the Panamint Range (i.e., Prave, 1999). This detailed geologic mapping and collection of structural data for the rocks in the southern Panamint Valley area were created using digital in-the-field geographic information systems software running on a field-hardened laptop computer. This map is a simplification of detailed geologic mapping data collected at 1:6000 scales and reduced to 1:20000 scale. Structural data includes kinematic and relative timing of deformation information.
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Ivanov, D. I., and V. N. Nikitin. "Surgical Treatment of Patients with Dislocation of IOL — Fibrosed Capsule Bag Complexes." Ophthalmology in Russia 19, no. 2 (June 30, 2022): 307–17. http://dx.doi.org/10.18008/1816-5095-2022-2-307-317.
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Violation of the correct location of the complex IOL capsule bag (CICB) in the delayed postoperative period occurs with a frequency of 0.2 to 2.8 %. The basis of the pathogenesis of this complication is the destruction of the zonal ligament due to progressive pseudoexfoliative syndrome, as well as the process of fibrosing the capsule bag. The stage of the flow and the different degree of severity of each mechanisms determines the variety of clinical manifestations. CICB dislocation in combination of these two mechanisms requires a special approach to treatment.Objective: to develop a system of surgical treatment of IOL dislocations in contract capsule syndrome, with varying degrees of severity, combined with the weakness of the ligament apparatus of the lens, and to present the results of its use.Patients and methods. Retrospective analysis of 55 cases of CICB dislocations with the observation period of more than 4 years operated in 2014-2016. Number of dislocations with certain IOL type: Hydrophilic monolithic — 27, Hydrophilic monolithic — 11, Hydrophilic three-part — 10, Hard — 7. The selection criterion was the presence of CICB dislocation in the combination of weakness of the ligament apparatus (II–III st. of severity) and contraction capsule syndrome, with varying degrees of severity. A system is proposed to allow a low-invasive repositioning of intraocular lenses dislocated with a fibrous capsule bag with subsequent suture fixation to the iris. Signs used for choice of surgical technique: localization of capsule bag fibrosis, contract effect of capsule bag fibrosis on IOL position and correct location of haptic elements, size, and severity of equatorial lens masses (Semmering ring). In cases when insufficiency of the ligament apparatus prevails, with insignificant fibrosis of the capsule bag, without contractional influence, fixation of KIKM to iris is carried out without cutting of the capsule bag (method 1). As the fibrous changes of the front or back leaf of the capsule progress without changing the position of IOL inside the capsule bag due to contraction, along with fixation of KIKM, the fibrous front/back capsule is excised (method 2). The variant of complete removal of the fibrous capsule bag is used in faraway stages of CCS with further fixation of IOL to the iris (method 3).Results. The data of BCVA and IOP of patients treated by a certain method (before the operation, early postoperative period (2–5 days), delayed period (more than 4 years)) are presented.Conclusion. Surgical treatment of patients with CICB dislocation combining manifestations of Capsule contraction syndrome and weakness of the lens ligament apparatus can now be standardized using a proper approach and certain methods of treatment, but requires a comprehensive assessment of such parameters as the safety of the ligament apparatus, the localization and degree of fibrous changes of the anterior / posterior capsule, the contractional effect of the capsule bag fibrosis on the front position of the IOL optics and the correct location of the haptic elements, the severity of the ring.
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Ferrer, Oriol, Oscar Gratacós, Eduard Roca, and Josep Anton Muñoz. "Modeling the interaction between presalt seamounts and gravitational failure in salt-bearing passive margins: The Messinian case in the northwestern Mediterranean Basin." Interpretation 5, no. 1 (February 1, 2017): SD99—SD117. http://dx.doi.org/10.1190/int-2016-0096.1.
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The northwest Mediterranean Basin includes a thick Messinian salt sequence composed of three evaporitic units. From these, the intermediate unit, which is dominantly composed of halite, acted as a gravitational detachment favoring the downslope failure of the overlying sediments in a thin-skinned deformation regime. As a result, the structure of the margin is characterized by an upper extensional domain with basinward-dipping listric normal faults and a lower contractional domain that accommodates upslope extension by folding, salt inflation, or diapir squeezing. Lower to middle Miocene volcanic seamounts (presalt reliefs) located at the upper extensional domain locally disrupted the evaporitic units and produced salt flow perturbations. They acted as passive buttresses during the gravitational failure modifying the structural zonation of the margin. Using an experimental approach (sandbox models), we analyze the role played by seamounts during the kinematic evolution of passive margins and how they alter salt flow and suprasalt deformation during gravitational gliding. The experiments found that the seamounts locally interrupt the structural zonation of the margin because they hindered downdip salt flow during early deformation. Seamounts initially compartmentalize the margin architecture, resulting in the development of two gravitational subsystems with two extensional/contractional pairs that are subsequently reconnected when the accumulation of salt analog upslope of the relief is enough to overthrust it. From this point onward, the cover is passively translated downslope as a regional system. The changes in the viscous layer flow velocity related to the dip differences between the flanks and edges of the seamount determine the kinematic evolution of this system. Our experiments also provide geometric constraints to consider during interpretation of these structures, which are commonly poorly imaged in seismic data.
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SUNAL, G., M. SATIR, B. A. NATAL'IN, G. TOPUZ, and O. VONDERSCHMIDT. "Metamorphism and diachronous cooling in a contractional orogen: the Strandja Massif, NW Turkey." Geological Magazine 148, no. 4 (January 19, 2011): 580–96. http://dx.doi.org/10.1017/s0016756810001020.
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AbstractThe southern part of the Strandja Massif, northern Thrace, Turkey, comprises a basement of various gneisses, micaschists and rare amphibolite, and a cover of metaconglomerate and metasandstone, separated from each other by a pre-metamorphic unconformity. Metamorphic grade decreases from the epidote–amphibolite facies in the south to the albite–epidote–amphibolite/greenschist-facies transition in the north. Estimated P–T conditions are 485–530°C and 0.60–0.80 GPa in the epidote–amphibolite facies domain, and decrease towards the transitional domain between greenschist- and epidote–amphibolite facies. Rb–Sr muscovite ages range from 162.9 ± 1.6 Ma to 149.1 ± 2.1 Ma, and are significantly older (279–296 Ma) in the northernmost part of the study area. The Rb–Sr biotite ages decrease from 153.9 ± 1.5 Ma in the south to 134.4 ± 1.3 Ma in the north. These age values in conjunction with the attained temperatures suggest that the peak metamorphism occurred at around 160 Ma and cooling happened diachronously, and Rb–Sr muscovite ages were not reset during the metamorphism in the northernmost part. Structural features such as (i) consistent S-dipping foliation and SW to SE-plunging stretching lineation, (ii) top-to-the-N shear sense, and (iii) N-vergent ductile shear zones and brittle thrusts suggest a N-vergent compressional deformation coupled with exhumation. We tentatively ascribe this metamorphism and subsequent diachronous cooling to the northward propagation of a thrust slice. The compressional events in the Strandja Massif were most probably related to the coeval N-vergent subduction/collision system in the southerly lying Rhodope Massif.
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Brozzetti, Francesco, Daniele Cirillo, and Lucina Luchetti. "Timing of Contractional Tectonics in the Miocene Foreland Basin System of the Umbria Pre-Apennines (Italy): An Updated Overview." Geosciences 11, no. 2 (February 19, 2021): 97. http://dx.doi.org/10.3390/geosciences11020097.
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A large dataset of lithostratigraphic and biostratigraphic data, concerning the Early-Late Miocene turbidite succession of the Umbria pre-Apennines, is presented and analyzed. The data come from the study of 24 sections that are representative of all the main tectonic units cropping out between the front of the Tuscan allochthon and the Umbria-Marche calcareous chain. The sections have been dated using quantitative calcareous nannofossil biostratigraphy and, wherever possible, they were correlated through key-beds recognition. Such a multidisciplinary approach allowed us to reconstruct the evolution of the Umbria foredeep over time and to unveil the chronology of compressive deformations by defining: (i) the onset of the foredeep stage in each structural unit, (ii) the age of depocenter-shifting from a unit to the adjacent one, (iii) the progressive deactivation of the western sector of the foredeep due to the emplacement of allochthon units, and (iv) the internal subdivisions of the basin due to the presence of foreland ramp faults or thrust-related structures. A further original outcome of our study is having brought to light the Late Burdigalian “out-of-sequence” reactivation of the Tuscan allochthon which bounded westward the foredeep, and the subsequent protracted period of tectonic stasis that preceded the deformations of the Umbrian parautochthon.
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Ramos, Adrià, Berta Lopez-Mir, Elisabeth P. Wilson, Pablo Granado, and Josep Anton Muñoz. "3D reconstruction of syn-tectonic strata in a salt-related orogen: learnings from the Llert syncline (South-central Pyrenees)." Geologica Acta 18 (December 11, 2020): 1–19. http://dx.doi.org/10.1344/geologicaacta2020.18.20.
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The Llert syncline is located in the South-central Pyrenees, between the eastern termination of the EW-trending Cotiella Basin and the north-western limb of the NS-trending Turbón-Serrado fold system. The Cotiella Basin is an inverted upper Coniacian-lower Santonian salt-floored post-rift extensional basin developed along the northern Iberian rift system. The Turbón-Serrado fold system consists of upper Santonian – Maastrichtian contractional salt-cored anticlines developed along an inverted transfer zone of the Pyrenean rift system. Based on field research, this paper presents a 3D reconstruction of the Llert syncline in order to further constrain the transition between these oblique salt-related structures. Our results suggest that the evolution of the Llert syncline was mainly controlled by tectonic shortening related to the tectonic inversion of the Cotiella Basin synchronously to the growth of the Turbón-Serrado detachment anticline, and by the pre-compressional structural framework of the Pyrenean rift system. Our contribution provides new insight into the geometric and kinematic relationships of structures developed during the inversion of passive margins involving salt.
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McGroder, Michael F. "Structural geometry and kinematic evolution of the eastern Cascades foldbelt, Washington and British Columbia." Canadian Journal of Earth Sciences 26, no. 8 (August 1, 1989): 1586–602. http://dx.doi.org/10.1139/e89-135.
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The eastern Cascades foldbelt is one of three structural domains lying within the complex collision zone between the Insular and Intermontane composite terranes in northern Washington and southern British Columbia. The foldbelt resides between the high-grade metamorphic backbone of the Cascade orogen on the west and rocks of the composite Intermontane terrane to the east. It encompasses the stratigraphically coherent, basalt-floored Jura–Cretaceous Methow basin as well as more chaotically disposed Permian–Jurassic oceanic rocks of the Hozameen terrane. Methow basin rocks are thought to have been sutured above the oceanic rocks prior to the middle Cretaceous contractional episode described in this report.Based on the analysis presented herein, between ca. 100 and 88 Ma the rocks in the foldbelt underwent shortening in an east-northeast – west-southwest direction by 50 km or more, largely by displacement on the east-vergent Jack Mountain – Chuwanten thrust system. The early stages of contraction occurred by the process of tectonic wedging, whereby rocks of the Hozameen terrane and western Methow basin translated eastward by delaminating eastern Methow basin strata along west-vergent thrusts. In later stages of shortening, the tectonic wedge became inactive and was carried piggyback atop the east-vergent Cascade Crest and Chuwanten faults.Presently available geochronologic data indicate overlap in the time periods during which eastern and western Cascades foldbelts were deforming and the Cascade metamorphic core was undergoing amphibolite-facies regional metamorphism. Therefore, contraction of rocks in the eastern foldbelt was an important product of the middle Cretaceous orogeny in the Cascades and must be considered in any regional tectonic model for orogenesis. The eastern foldbelt clearly accommodated substantially less shortening than the western foldbelt and is herein proposed to be a backthrust system in the rear of the predominantly west-vergent Cascade orogen.
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Li, Pengfei, Min Sun, Gideon Rosenbaum, Keda Cai, Chao Yuan, Fred Jourdan, Xiaoping Xia, Yingde Jiang, and Yunying Zhang. "Tectonic evolution of the Chinese Tianshan Orogen from subduction to arc-continent collision: Insight from polyphase deformation along the Gangou section, Central Asia." GSA Bulletin 132, no. 11-12 (April 8, 2020): 2529–52. http://dx.doi.org/10.1130/b35353.1.
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Abstract The Central Asian Orogenic Belt, as the largest accretionary orogen on Earth, is an ideal candidate to study the geodynamics of convergent plate boundaries through a prolonged period. The evolution of this orogen has been explained by different tectonic models, which incorporated one, or a combination, of the following mechanisms: lateral stacking of arc systems along major shear zones, arc amalgamation, oroclinal bending, and trench migration. Here we elucidate major mechanisms responsible for the tectonic evolution of the Central Asian Orogenic Belt, focusing on the Chinese Tianshan Orogen in the southern Central Asian Orogenic Belt. Structural observations from the ∼50-km-long Gangou section show evidence of polyphase deformation. The earliest episode of orogen-parallel sinistral shearing, constrained to the Early Devonian (ca. 399 Ma) by syn-deformational intrusions, was possibly controlled by oblique subduction. This was followed by an episode of ∼NE–SW contractional deformation, dated at ca. 356 Ma (40Ar/39Ar age of syn-deformational hornblende), and likely associated with an episode of trench advance. The third stages of deformation during the latest Carboniferous and Permian involved ∼NE-SW contraction, orogen-parallel extension, and dextral transpression. Our new geochronological data constrain the timing of orogen-parallel extension to ca. 303–293 Ma, and confirm that dextral activation along shear zones occurred during the Permian. The results highlight the role of trench migration, oblique tectonics, and syn-collisional orogen-parallel extension in the build-up of the Central Asian Orogenic Belt, and contribute to the pre-collisional reconstruction of this orogenic system.
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Bijnaar, Ginny, Manfred J. van Bergen, and Theo E. Wong. "The kyanite quartzite of Bosland (Suriname): evidence for a Precambrian metamorphosed alteration system." Netherlands Journal of Geosciences - Geologie en Mijnbouw 95, no. 4 (November 3, 2016): 447–65. http://dx.doi.org/10.1017/njg.2016.38.
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AbstractThis article investigates the origin of a rare occurrence of kyanite quartzites in the Palaeoproterozoic greenstone belt of Suriname. The rocks form elongated hills in the Bosland area, Brokopondo district, where they are associated with meta-sedimentary, meta-volcanic and granitic lithologies. Their mineral content and unusual Si- and Al-rich chemical composition are inferred to be the result of advanced argillic alteration of felsic volcanic tuffs and a later overprint by regional metamorphism up to lower amphibolite facies during the Trans-Amazonian orogeny. Structurally, the Bosland area seems centred within a contractional strike-slip duplex of a major dextral fault system. The alteration was probably associated with a high-sulphidation environment and involved significant to almost complete removal of alkali and alkaline earth elements. Pseudosection modelling and textures suggest that the precipitation–temperature (P–T) history of the kyanite quartzites started with shallow (<2kbar) hydrothermal alteration of the acidic tuffaceous volcanics, possibly in the andalusite stability field (T>350°C), and ended in peak metamorphic conditions in the kyanite–staurolite stability field (P>4kbar andT=500–650°C). Alteration events that preceded the peak of Trans-Amazonian metamorphism may be more common in the rock record of Suriname's greenstone belt, which lends support to the hypothesis that gold mineralisations in the region can be pre-orogenic.
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HOLDSWORTH, R. E., E. TAVARNELLI, and P. CLEGG. "The nature and regional significance of structures in the Gala Group of the Southern Uplands terrane, Berwickshire coast, southeastern Scotland." Geological Magazine 139, no. 6 (November 2002): 707–17. http://dx.doi.org/10.1017/s0016756802006854.
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Structures deforming Llandovery turbidites of the Gala Group in the Southern Uplands terrane are spectacularly exposed in the Berwickshire coastal section, southeastern Scotland. The upward-facing, upright to NW-vergent folds and associated structures appear to record a single regional phase of subhorizontal NW–SE contractional deformation, with a steeply dipping direction of bulk finite extension. These structures are markedly different from those developed in rocks correlated with the Upper Llandovery Hawick Group exposed some 5 km to the south in the Eyemouth–Burnmouth coastal section. Here a highly domainal system of sinistral transpressional strain occurs, with zones of steeply plunging curvilinear folds, clockwise cleavage transection and bedding-parallel sinistral detachment faults. The markedly different bulk strain patterns in the Berwickshire coastal sections are thought to reflect the regionally diachronous nature of transpressional deformation in the Southern Uplands terrane. There are striking similarities in the structures recognized in the Berwickshire coastal sections and those developed in stratigraphically equivalent units along strike in southwestern Scotland and Northern Ireland. This confirms the lateral structural continuity and correlation of tracts and tract boundaries along the entire length of the Southern Uplands terrane. The regional structure suggests that a phase of top-to-the-NW backthrusting and backfolding associated with the southern margin of the Gala Group outcrop marks the transition from orthogonal contraction to sinistral transpression in the Southern Upland thrust wedge during late Llandovery times.
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Trudel, Claude, and Michel Malo. "Analyses des contraintes par méthodes graphiques dans une zone de coulissage : exemple de la région de Matapédia, Gaspésie, Appalaches du Québec." Canadian Journal of Earth Sciences 30, no. 3 (March 1, 1993): 591–602. http://dx.doi.org/10.1139/e93-045.
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The north-northeast trending Sellarsville and Rafting Ground faults are southeasterly directed Acadian (Devonian) thrusts in the Québec Appalachians. They are located at the western end of the Grand Pabos fault system, a dextral strike-slip fault system that transects Upper Ordovician to Lower Devonian sedimentary rocks in the southern Gaspé Peninsula. The structural analysis of mesoscopic brittle and brittle–ductile shear zones by graphical methods was used to determine the stress field related to these two faults. The attitude of slip lines was calculated when the slickenside striations were not observed on the movement plane. Conjugate faults, Arthaud's method, and Angelier and Mechler's method were used to determine the paleostress. The maximum principal compressive stress σ1, always subhorizontal and striking west-northwest – east-southeast, is perpendicular to the Sellarsville and Rafting Ground faults and was probably the cause of the thrusting motion along the faults. North-northeast-trending regional folds and cleavage could also be related to this same stress. Geological mapping and structural cross sections confirm the southeasterly directed thrust motions, which are well integrated in the Grand Pabos fault system. Sellarsville and Rafting Ground faults with the Restigouche fault may represent a leading contractional imbricate fan in a dextral strike-slip system. [Journal Translation]
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FUENTES, FACUNDO, BRIAN K. HORTON, DANIEL STARCK, and ANDRÉS BOLL. "Structure and tectonic evolution of hybrid thick- and thin-skinned systems in the Malargüe fold–thrust belt, Neuquén basin, Argentina." Geological Magazine 153, no. 5-6 (July 25, 2016): 1066–84. http://dx.doi.org/10.1017/s0016756816000583.
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AbstractAndean Cenozoic shortening within the Malargüe fold–thrust belt of west-central Argentina has been dominated by basement faults largely influenced by pre-existing Mesozoic rift structures of the Neuquén basin system. The basement contractional structures, however, diverge from many classic inversion geometries in that they formed large hanging-wall anticlines with steeply dipping frontal forelimbs and structural relief in the order of several kilometres. During Cenozoic E–W shortening, the reactivated basement faults propagated into cover strata, feeding slip to shallow thrust systems that were later carried in piggyback fashion above newly formed basement structures, yielding complex thick- and thin-skinned structural relationships. In the adjacent foreland, Cenozoic clastic strata recorded the broad kinematic evolution of the fold–thrust belt. We present a set of structural cross-sections supported by regional surface maps and industry seismic and well data, along with new stratigraphic information for associated Neogene synorogenic foreland basin fill. Collectively, these results provide important constraints on the temporal and geometric linkages between the deeper basement faults (including both reactivated and newly formed structures) and shallow thin-skinned thrust systems, which, in turn, offer insights for the understanding of hydrocarbon systems in the actively explored Neuquén region of the Andean orogenic belt.
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Muñoz, Josep-Anton, Elisabet Beamud, Oscar Fernández, Pau Arbués, Jaume Dinarès-Turell, and Josep Poblet. "The Ainsa Fold and thrust oblique zone of the central Pyrenees: Kinematics of a curved contractional system from paleomagnetic and structural data." Tectonics 32, no. 5 (September 2013): 1142–75. http://dx.doi.org/10.1002/tect.20070.
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Pratama, Cecep, Leni Sophia Heliani, Nurrohmat Widjajanti, Endra Gunawan, Ira Mutiara Anjasmara, Suci Tresna Novianti, Tika Widya Sari, Retno Eka Yuni, and Adelia Sekarsari. "Recent GPS-based long wavelength crustal deformation revealed active postseismic deformation due to the 2006 Yogyakarta earthquake." Journal of Applied Geodesy 16, no. 2 (January 26, 2022): 131–41. http://dx.doi.org/10.1515/jag-2020-0053.
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Abstract We analyze the Global Positioning System (GPS)-derived strain rate distribution to investigate active crustal structure in Central Java, Indonesia, using ten years (2010–2019) continuous and permanent observation data. Central Java is the third-most populous province in Indonesia where postseismic deformation of devastating Yogyakarta earthquake in 2006 might influence the GPS data. The postseismic extensional response might overshadow the low contractional process due to active tectonics deformation. A decomposition method of a calculated strain rate shows a long wavelength feature with the extensional region in the vicinity of the 2006 Yogyakarta earthquake may reflect the postseismic process remain active. The short wavelength pattern is sharpening potential active tectonics dominated by oblique Northwest-Southeast dip-slip motion with East-West left-lateral sense. Our result demonstrates essential implications for assessing future seismic hazard potential within a low strain rate such as the Central Java region.
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Grant, Ross J., John R. Underhill, Jaume Hernández-Casado, Rachel J. Jamieson, and Ryan M. Williams. "The evolution of the Dowsing Graben System: implications for petroleum prospectivity in the UK Southern North Sea." Petroleum Geoscience 27, no. 1 (October 29, 2019): petgeo2018–064. http://dx.doi.org/10.1144/petgeo2018-064.
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Upper Permian (Zechstein Supergroup) evaporites have a major control on structural styles and prospectivity in the UK Southern North Sea (SNS). They form the regional super-seal for the main Rotliegend Group (Leman Sandstone Formation) reservoir play fairway immediately beneath. The evaporites have highly variable thicknesses due to the syndepositional basin architecture, differential loading and post-depositional deformation through diapirism and salt withdrawal. The halokinetic activity leads to touchdown (welding) of the supra-salt section onto the sub-salt strata and the development of narrow (up to 15 km-wide) graben systems. The interpretation and depth conversion of well-calibrated, high-quality, 3D post-stack time-migrated (PSTM) seismic data along the southwestern margin of the basin show that a NW–SE-striking elongate extensional Dowsing Graben System transects the area. The graben is defined by a series of large, overlapping, en echelon listric growth faults, with oblique secondary planar faults, which sole-out on two main (deep and shallow) décollement levels in the Zechstein Supergroup and the Middle Triassic Röt Halite Member. Whilst its initial formation was related to Mesozoic extension, the graben system also displays a contractional overprint resulting from regional compression and structural inversion during the Cenozoic. Detailed mapping of the Zechstein Supergroup has revealed that the evolution of the extensional system was influenced by the ESE–WNW-striking anhydrite–carbonate Zechstein shelf-margin. The occurrence of variable-thickness, low-velocity sediments within the graben impacts seismic imaging and depth conversion, leading to prospective structures being overlooked; something that has implications for prospectivity in the SNS and other evaporite basins where similar graben occur.
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Nishimura, T., H. Suito, T. Kobayashi, Q. Dong, and T. Shibayama. "Excess strain in the Echigo Plain sedimentary basin, NE Japan: evidence from coseismic deformation of the 2011 Tohoku-oki earthquake." Geophysical Journal International 205, no. 3 (March 14, 2016): 1613–17. http://dx.doi.org/10.1093/gji/ggw102.
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Abstract Coseismic deformation depends on both the source fault and on the elastic properties of the crust. Large coseismic deformation associated with the 2011 Mw 9.0 Tohoku-oki earthquake enabled us to investigate strain anomalies from crustal inhomogeneity. Concentrated contractional strain was observed in the Echigo Plain (Niigata-Kobe Tectonic Zone) before the Tohoku-oki earthquake, whereas continuous and campaign global navigation satellite system measurements show a widespread distribution of coseismic extensional strain in and around the plain. A 1-D displacement profile shows high strain (7.2 ± 0.7 microstrain) in a 17 km long section across the Echigo Plain and low strain (3.3 ± 0.4 microstrain) along a 15 km long section east of the plain, despite the latter being closer to the megathrust fault source. We performed numerical modelling of coseismic deformation using a heterogeneous subsurface structure and successfully reproduced excess extension in the plain, which is filled by low-rigidity sediments. This study demonstrates the importance of considering heterogeneous crust in deformation modelling.
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Van Staal, Cees, and Alexandre Zagorevski. "Accretion, Soft and Hard Collision: Similarities, Differences and an Application from the Newfoundland Appalachian Orogen." Geoscience Canada 47, no. 3 (September 28, 2020): 103–18. http://dx.doi.org/10.12789/geocanj.2020.47.161.
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We argue there is no distinction between accretion and collision as a process, except when accretion is used in the sense of incorporating small bodies of sedimentary and/or volcanic rocks into an accretionary wedge by off-scraping or underplating. There is also a distinction when these terms are used in classifying mountain belts into accretionary and collisional orogens, although such classifications are commonly based on a qualitative assessment of the scale and nature of the accreted terranes and continents involved in formation of mountain belts. Soft collisions occur when contractional deformation and associated metamorphism are principally concentrated in rocks of the leading edge of the partially pulled-down buoyant plate and the upper plate forearc terrane. Several young arc-continent collisions show evidence for partial or wholesale subduction of the forearc such that the arc is structurally juxtaposed directly against lower plate rocks. This process may explain the poor preservation of forearcs in the geological record. Soft collisions generally change into hard collisions over time, except if the collision is rapidly followed by formation of a new subduction zone due to step-back or polarity reversal. Thickening and metamorphism of the arc's suprastructure and retro-arc part of upper plate due to contractional deformation and burial are the characteristics of a hard collision or an advancing Andean-type margin. Strong rheological coupling of the converging plates and lower and upper crust in the down-going continental margin promotes a hard collision. Application of the soft–hard terminology supports a structural juxtaposition of the Taconic soft collision recorded in the Humber margin of western Newfoundland with a hard collision recorded in the adjacent Dashwoods block. It is postulated that Dashwoods was translated dextrally along the Cabot-Baie Verte fault system from a position to the north of Newfoundland where the Notre Dame arc collided ca. 10 m.y. earlier with a wide promontory in a hyperextended segment of the Laurentian margin.
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Arnous, Ahmad, Martin Zeckra, Agostina Venerdini, Patricia Alvarado, Ramón Arrowsmith, Julien Guillemoteau, Angela Landgraf, Antonio Gutiérrez, and Manfred R. Strecker. "Neotectonic Activity in the Low-Strain Broken Foreland (Santa Bárbara System) of the North-Western Argentinean Andes (26°S)." Lithosphere 2020, no. 1 (October 28, 2020): 1–25. http://dx.doi.org/10.2113/2020/8888588.
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Abstract Uplift in the broken Andean foreland of the Argentine Santa Bárbara System (SBS) is associated with the contractional reactivation of basement anisotropies, similar to those reported from the thick-skinned Cretaceous-Eocene Laramide province of North America. Fault scarps, deformed Quaternary deposits and landforms, disrupted drainage patterns, and medium-sized earthquakes within the SBS suggest that movement along these structures may be a recurring phenomenon, with yet to be defined repeat intervals and rupture lengths. In contrast to the Subandes thrust belt farther north, where eastward-migrating deformation has generated a well-defined thrust front, the SBS records spatiotemporally disparate deformation along structures that are only known to the first order. We present herein the results of geomorphic desktop analyses, structural field observations, and 2D electrical resistivity tomography and seismic-refraction tomography surveys and an interpretation of seismic reflection profiles across suspected fault scarps in the sedimentary basins adjacent to the Candelaria Range (CR) basement uplift, in the south-central part of the SBS. Our analysis in the CR piedmont areas reveals consistency between the results of near-surface electrical resistivity and seismic-refraction tomography surveys, the locations of prominent fault scarps, and structural geometries at greater depth imaged by seismic reflection data. We suggest that this deformation is driven by deep-seated blind thrusting beneath the CR and associated regional warping, while shortening involving Mesozoic and Cenozoic sedimentary strata in the adjacent basins was accommodated by layer-parallel folding and flexural-slip faults that cut through Quaternary landforms and deposits at the surface.
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Konon, Andrzej, Szymon Ostrowski, Barbara Rybak-Ostrowska, Mirosław Ludwiniak, Michał Śmigielski, Michał Wyglądała, Joanna Uroda, Sebastian Kowalczyk, Radosław Mieszkowski, and Agnieszka Kłopotowska. "Mnin restraining stepover – evidence of significant Cretaceous–Cenozoic dextral strike-slip faulting along the Teisseyre-Tornquist Zone?" Acta Geologica Polonica 66, no. 3 (September 1, 2016): 435–55. http://dx.doi.org/10.1515/agp-2016-0019.
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Abstract A newly recognized Mnin restraining stepover is identified in the Permo-Mesozoic cover of the western part of the Late Palaeozoic Holy Cross Mountains Fold Belt (Poland), within a fault pattern consisting of dextral strike-slip faults. The formation of a large contractional structure at the Late Cretaceous – Cenozoic transition displays the significant role of strike-slip faulting along the western border of the Teisseyre-Tornquist Zone, in the foreland of the Polish part of the Carpathian Orogen. Theoretical relationships between the maximum fault offsets/ mean step length, as well as between the maximum fault offsets/mean step width allowed the estimation of the values of possible offsets along the Snochowice and Mieczyn faults forming the Mnin stepover. The estimated values suggest displacements of as much as several tens of kilometres. The observed offset along the Tokarnia Fault and theoretical calculations suggest that the strike-slip faults west of the Late Palaeozoic Holy Cross Mountains Fold Belt belong to a large strike-slip fault system. We postulate that the observed significant refraction of the faults forming the anastomosing fault pattern is related also to the interaction of the NW-SE-striking faults formed along the western border of the Teisseyre- Tornquist Zone and the reactivated WNW-ESE-striking faults belonging to the fault systems of the northern margin of the Tethys Ocean.
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Wu, Guochao, Fausto Ferraccioli, Wenna Zhou, Yuan Yuan, Jinyao Gao, and Gang Tian. "Tectonic Implications for the Gamburtsev Subglacial Mountains, East Antarctica, from Airborne Gravity and Magnetic Data." Remote Sensing 15, no. 2 (January 4, 2023): 306. http://dx.doi.org/10.3390/rs15020306.
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The Gamburtsev Subglacial Mountains (GSMs) in interior East Antarctic Craton are entirely buried under the massive ice sheet, with a ~50–60 km thick crust and ~200 km thick lithosphere, but little is known of the crustal structure and uplift mechanism. Here, we use airborne gravity and aeromagnetic anomalies for characteristic analysis and inverse calculations. The gravity and magnetic images show three distinct geophysical domains. Based on the gravity anomalies, a dense lower crustal root is inferred to underlie the GSMs, which may have been formed by underplating during the continental collision of Antarctica and India. The high frequency linear magnetic characteristics parallel to the suture zone suggest that the upper crustal architecture is dominated by thrusts, consisting of a large transpressional fault system with a trailing contractional imbricate fan. A 2D model along the seismic profile is created to investigate the crustal architecture of the GSMs with the aid of depth to magnetic source estimates. Combined with the calculated crustal geometry and physical properties and the geological background of East Antarctica, a new evolutionary model is proposed, suggesting that the GSMs have been a part of the Pan-African advancing accretionary orogen superimposed on the Precambrian basement.
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Brankman, Charles M., and Atilla Aydin. "Reply to the comments by G. Bertotti and V. Picotti on: “Uplift and contractional deformation along a segmented strike-slip fault system: the Gargano Promontory, southern Italy”." Journal of Structural Geology 26, no. 12 (December 2004): 2327–29. http://dx.doi.org/10.1016/j.jsg.2004.06.007.
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Bartholomew, Timothy D., Timothy A. Little, Kate J. Clark, Russ Van Dissen, and Philip M. Barnes. "Kinematics and paleoseismology of the Vernon Fault, Marlborough Fault System, New Zealand: Implications for contractional fault bend deformation, earthquake triggering, and the record of Hikurangi subduction earthquakes." Tectonics 33, no. 7 (June 30, 2014): 1201–18. http://dx.doi.org/10.1002/2014tc003543.
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Bracken, Kyle. "Mechanical stratigraphy and layer-bound normal faulting in the Upper Cretaceous Niobrara Formation, Wattenberg Field, Colorado." Mountain Geologist 57, no. 2 (April 1, 2020): 67–93. http://dx.doi.org/10.31582/rmag.mg.57.2.67.
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Layer-bound normal faults are pervasive within the very fine-grained rocks of the Upper Cretaceous Niobrara and Carlile formations in the Denver Basin. 3-D seismic and well log interpretation reveal a complex, segmented fault system that is divided into two discrete tiers: an upper tier located in the Pierre Shale, and a lower tier located in the Niobrara Formation. 3-D fault throw analysis shows maximum throw near the top of the Niobrara Formation with steep, asymmetrical throw gradient down section in the lower Niobrara and Carlile formations. Faults are laterally well-connected in the upper Niobrara Formation and commonly form linear arrays of linked graben systems. In contrast, faults deeper in the stratigraphic section that offset the Carlile and Greenhorn formations are more segmented and commonly form half grabens (as opposed to full, fault-bound grabens). In cross-section, fault planes measured from seismic have a general dip of 45°. However, close inspection reveals that faults consistently change dip angle as they pass through the lower Niobrara Formation, refracting from ~55° to ~35° through the Niobrara C Marl, then back up to ~50° in the Carlile and Greenhorn formations. The fault dip refraction produces a contractional step or bend in the fault plane associated with the lower dip segments. This geometry is investigated further with horizontal image logs and other borehole data to reveal a kinematic relationship between fault dip angle and mechanical stratigraphy. Field examples of normal faults that cut mechanically layered rock help better understand these complex fault geometries and provide reasonable inferences to their development and propagation history. In summary, it is argued that the mechanically layered nature of the Niobrara and Carlile formations is responsible for many of the fault characteristics described and provides valuable insight into understanding the fault system
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Burrel, Laura, and Antonio Teixell. "Contractional salt tectonics and role of pre-existing diapiric structures in the Southern Pyrenean foreland fold–thrust belt (Montsec and Serres Marginals)." Journal of the Geological Society 178, no. 4 (February 4, 2021): jgs2020–085. http://dx.doi.org/10.1144/jgs2020-085.
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Triassic Keuper evaporites have long been recognized as the main detachment level for thrusting in the Pyrenean fold–thrust belts. The deformed Late Cretaceous–Eocene foreland basin of the Southern Pyrenees has structures and stratal geometries that can be interpreted as related to salt tectonics (e.g. unconformities, rapid thickness variations, long-lived growth fans and overturned flaps), although they have been overprinted by shortening and thrusting. Based on field observations and published maps, we build new structural cross-sections reinterpreting two classic transects of the Southern Pyrenees (Noguera Ribagorçana and Noguera Pallaresa river transects). The sequential restoration of the sections explores the variations in structural style, addressing the role of halokinesis in the tectonic and sedimentary development. In the Serres Marginals area, we propose that salt pillows and diapirs started developing locally during the Mesozoic pre-orogenic episode, evolving into a system of salt ridges and intervening synclines filled with early synorogenic sediments. Rapid amplification of folds recorded by widespread latest Cretaceous–Paleocene growth strata is taken as marking the onset of contractional folding in the area. During Pyrenean compression, folding mechanisms transitioned from dominantly halokinetic to a combination of buckling and differential sedimentary loading. Squeezing of salt diapirs and thrust welding occurred as salt ridges were unroofed. We provide new field observations that lead to a reinterpretation of the regional structural development and contribute to the debate about the role of salt tectonics in the Pyrenees.Supplementary material: Table S1, giving the thickness of the main stratigraphic units, is available at https://doi.org/10.6084/m9.figshare.c.5287737
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BARREIRA, LUIS, and CLAUDIA VALLS. "Stability of L1 contractions." Mathematical Proceedings of the Cambridge Philosophical Society 159, no. 1 (April 1, 2015): 23–46. http://dx.doi.org/10.1017/s0305004115000158.
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AbstractThe notion of an exponential contraction is only one among many possible rates of contraction of a nonautonomous system, while for an autonomous system all contractions are exponential. We consider the notion of an L1 contraction that includes exponential contractions as a very particular case and that is naturally adapted to the variation-of-parameters formula. Both for discrete and continuous time, we show that under very general assumptions the notion of an L1 contraction persists under sufficiently small linear and nonlinear perturbations, also maintaining the type of stability. As a natural development, we establish a version of the Grobman–Hartman theorem for nonlinear perturbations of an L1 contraction.
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Gray, Keith D., V. Isakson, D. Schwartz, and Jeffrey D. Vervoort. "Orogenic link ∼41°N–46°N: Collisional mountain building and basin closure in the Cordillera of western North America." Geosphere 16, no. 1 (December 5, 2019): 136–81. http://dx.doi.org/10.1130/ges02074.1.
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Abstract Polyphase structural mapping and mineral age dating across the Salmon River suture zone in west-central Idaho (Riggins region; ∼45°30′N, ∼117°W–116°W) support a late Mesozoic history of penetrative deformation, dynamothermal metamorphism, and intermittent magmatism in response to right-oblique oceanic-continental plate convergence (Farallon–North America). High-strain linear-planar tectonite fabrics are recorded along an unbroken ∼48 km west-to-east transect extending from the Snake River (Wallowa intra-oceanic arc terrane; eastern Blue Mountains Province) over the northern Seven Devils Mountains into the lower Salmon River Canyon (ancestral North America; western Laurentia). Given the temporally overlapping nature (ca. 145–90 Ma) of east-west contraction in the Sevier fold-and-thrust belt (northern Utah–southeast Idaho–southwest Montana segment), we propose that long-term terrane accretion and margin-parallel northward translation in the Cordilleran hinterland (∼41°N–46°N latitude; modern coordinates) drove mid- to upper-crustal shortening >250 km eastward into the foreland region (∼115°W–113°W). During accretion and translation, the progressive transfer of arc assemblages from subducting (Farallon) to structurally overriding (North American) plates was accommodated by displacement along a shallow westward-dipping basal décollement system underlying the Cordilleran orogen. In this context, large-magnitude horizontal shortening of passive continental margin strata was balanced by the addition of buoyant oceanic crust—late Paleozoic to Mesozoic Blue Mountains Province—to the leading edge of western Laurentia. Consistent with orogenic float modeling (mass conservation, balance, and displacement compatibility), diffuse dextral-transpressional deformation across the accretionary boundary (Salmon River suture: Cordilleran hinterland) was kinematically linked to eastward-propagating structures on the continental interior (Sevier thrust belt; Cordilleran foreland). As an alternative to noncollisional convergent margin orogenesis, we propose a collision-related tectonic origin and contractional evolution for central portions of the Sevier belt. Our timing of terrane accretion supports correlation of the Wallowa terrane with Wrangellia (composite arc/plateau assemblage) and implies diachronous south-to-north suturing and basin closure between Idaho and Alaska.
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Izquierdo-Llavall, Esther, Eduard Roca, Huiwen Xie, Oriol Pla, Josep Anton Muñoz, Mark G. Rowan, Neng Yuan, and Shaoying Huang. "Influence of Overlapping décollements, Syntectonic Sedimentation, and Structural Inheritance in the Evolution of a Contractional System: The Central Kuqa Fold-and-Thrust Belt (Tian Shan Mountains, NW China)." Tectonics 37, no. 8 (August 2018): 2608–32. http://dx.doi.org/10.1029/2017tc004928.
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Billi, Andrea, Graziella Barberi, Claudio Faccenna, Giancarlo Neri, Fabrizio Pepe, and Attilio Sulli. "Tectonics and seismicity of the Tindari Fault System, southern Italy: Crustal deformations at the transition between ongoing contractional and extensional domains located above the edge of a subducting slab." Tectonics 25, no. 2 (March 30, 2006): n/a. http://dx.doi.org/10.1029/2004tc001763.
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Pincivero, Danny M., and Staci M. Thomas. "The Effects of Knee Joint Angle and Contractor Intensity on Perceived Exertion." Perceptual and Motor Skills 125, no. 6 (September 7, 2018): 1123–39. http://dx.doi.org/10.1177/0031512518797859.
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This study examined knee joint angle and knee muscle contraction intensity effects on perceived exertion during isometric contractions. Fourteen healthy young adults participated in five experimental exercise sessions in which knee angles varied randomly (10°, 30°, 50°, 70°, and 90°), each separated by one week. During each session, subjects performed five isometric maximal voluntary contractions (MVCs) of knee extension, followed by nine, randomly ordered submaximal contractions (10%–90% MVC, 10% increments). The participants repeated the identical procedure for the knee flexor muscles. Immediately following each submaximal contraction, participants rated their perceived exertion using a modified Borg category-ratio scale. We found that the participants’ overall ratings of perceived exertion were significantly ( p < .05) greater at the 90° than at the 70° and 10° positions during the knee extensor contractions. There were also several significant angle by contraction intensity interactions in that perceived exertion was significantly greater across 60% to 70% MVC at 30° than at 50° ( p < .01), while the opposite pattern was observed across 70% to 80% MVC ( p < .01). During knee flexor contractions, perceived exertion was significantly greater ( p < .05) at 90°, when compared with all other knee angles. There were also significant ( p < .05) angle by contraction intensity interactions between the 50° and 70° knee positions across contraction intensities of 30–40%, 40–50%, 50–60%, and 60–70% MVC. We conclude that the higher perceived exertion rating at 90° during knee extension and flexion contractions suggests different peripheral and central contributors between both muscle groups, due to differences in muscle length.
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Dinevari, T., and M. Frigon. "Applications of Multivalued Contractions on Graphs to Graph-Directed Iterated Function Systems." Abstract and Applied Analysis 2015 (2015): 1–16. http://dx.doi.org/10.1155/2015/345856.
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We apply a fixed point result for multivalued contractions on complete metric spaces endowed with a graph to graph-directed iterated function systems. More precisely, we construct a suitable metric space endowed with a graphGand a suitableG-contraction such that its fixed points permit us to obtain more information on the attractor of a graph-directed iterated function system.
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Georgescu, Flavian. "Iterated Function Systems Consisting of Generalized Convex Contractions in the Framework of Complete Strong b-metric Spaces." Annals of West University of Timisoara - Mathematics and Computer Science 55, no. 2 (December 1, 2017): 119–42. http://dx.doi.org/10.1515/awutm-2017-0018.
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AbstractThe concept of generalized convex contraction was introduced and studied by V. Istrăţescu and the notion ofb-metric space was introduced by I. A. Bakhtin and S. Czerwik. In this paper we combine these two elements by studying iterated function systems consisting of generalized convex contractions on the framework ofb-metric spaces. More precisely we prove the existence and uniqueness of the attractor of such a system providing in this way a generalization of Istrăţescu’s convex contractions fixed point theorem in the setting of complete strongb-metric spaces.
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Spriet, L. L., K. Soderlund, M. Bergstrom, and E. Hultman. "Anaerobic energy release in skeletal muscle during electrical stimulation in men." Journal of Applied Physiology 62, no. 2 (February 1, 1987): 611–15. http://dx.doi.org/10.1152/jappl.1987.62.2.611.
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The quadriceps femoris muscles of seven men were electrically stimulated under extended anaerobic conditions to quantitate anaerobic energy release and the contribution of the glycolytic system to total ATP production. Muscles were intermittently stimulated 64 times at 20 Hz while leg blood flow was occluded. Each contraction lasted 1.6 s and was followed by 1.6 s of rest. The total contraction time was 102.4 s. Muscle biopsies were taken at rest and following 16, 32, 48, and 64 contractions. The ATP turnover rates during the four 16-contraction periods were 6.12, 2.56, 2.17, and 0.64 mmol X kg dry muscle-1 X s-1 contraction time. Glycolysis provided 58%, phosphocreatine 40% and a decreased ATP store 2% of the consumed energy during the initial 16 contractions. Glycolysis was responsible for 90% of the total ATP production beyond contraction 16. Absolute glycolytic ATP production decreased to 60, 55, and 17% of the amount in the initial 16 contractions during the final three periods, respectively. In conclusion glycolysis produced approximately 195 mmol ATP/kg dry muscle during the initial 48 contractions (76.8 s) and only approximately 15 mmol ATP/kg dry muscle during the final 16 contractions. Equivalent values for total ATP turnover were 278 and 16.5 mmol/kg dry muscle.
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Korsch, J., C. J. Boreham, J. M. Totterdell, R. D. Shaw, and M. G. Nicoll. "DEVELOPMENT AND PETROLEUM RESOURCE EVALUATION OF THE BOWEN, GUNNEDAH AND SURAT BASINS, EASTERN AUSTRALIA." APPEA Journal 38, no. 1 (1998): 199. http://dx.doi.org/10.1071/aj97011.
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The Early Permian to Middle Triassic Bowen and Gunnedah basins and the Early Jurassic to Early Cretaceous Surat Basin in eastern Australia developed in response to a series of interplate and intraplate tectonic events located to the east of the basin system. The initial event was extensional and stretched the continental crust to form a significant Early Permian East Australian Rift System. The most important of the rift-related features are a series of half graben that form the Denison Trough, now the site of several commercial gas fields. Several contractional events from the mid-Permian to the Middle Triassic are associated with the development of a foreland fold and thrust belt in the New England Orogen. This caused a foreland loading phase of subsidence in the Bowen and Gunnedah basins. Thick coal measures deposited towards the end of the Permian are the most important hydrocarbon source rocks in these basins. The development of the Surat Basin marked a major change in the subsidence and sedimentation patterns. It was only towards the end of this subsidence that sufficient burial was achieved to put the source rocks over much of the basin into the oil window. Based on an evaluation of the undiscovered hydrocarbon resources for the Bowen and Surat basins in southern Queensland, our estimates of the yields of hydrocarbons suggest that significant volumes of hydrocarbons have been produced in the basins. The bulk of the hydrocarbons were generated after 140 Ma and most of the generation occurred in the late Early Cretaceous. Because the estimated volume of the hydrocarbons generated far exceeds the volume of discovered hydrocarbons, preservation of accumulations may be the main risk factor. The yield analysis, by demonstrating the potentially large quantities of hydrocarbons available, should act as a stimulus to exploration initiatives, particularly in the search for stratigraphic traps.
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Szarek, J. L., and B. Spurlock. "Antagonism of cholinergic nerve-mediated contractions by the sensory nerve inhibitory system in rat bronchi." Journal of Applied Physiology 81, no. 1 (July 1, 1996): 260–65. http://dx.doi.org/10.1152/jappl.1996.81.1.260.
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The purpose of this study was to examine the potential functional significance of the sensory nerve inhibitory system in modulating contraction. Tension development in response to electrical field stimulation (EFS) and exogenous acetylcholine was monitored in segments of intrapulmonary bronchi isolated from male Sprague-Dawley rats. Contractile responses to EFS were enhanced by desensitization of sensory nerves with capsaicin, by antagonizing neurokinin NK1 receptors with RP-67580, and by inhibition of cyclooxygenase with meclofenamate. Except for RP-67580, which had a slight inhibitory effect on acetylcholine-induced contractions, these interventions were without effect on contraction to acetylcholine. Incubation of capsaicin-desensitized airway segments with substance P attenuated contractions evoked by a half-maximal frequency of EFS by approximately 92%, whereas contractions elicited by a half-maximal concentration of acetylcholine were not affected. Contractile responses elicited by a lower concentration of acetylcholine were inhibited by approximately 50% by substance P. The inhibitory effect of substance P was blocked by RP-67580, meclofenamate, and epithelial denudation. We conclude that the sensory nerve inhibitory system modulates cholinergic contractions and thus plays a role in the regulation of airway smooth muscle tone.
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George, Reny, and Hemanth Kumar Pathak. "Some New Extensions of Multivalued Contractions in a b-metric Space and Its Applications." Mathematics 9, no. 1 (December 23, 2020): 12. http://dx.doi.org/10.3390/math9010012.
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The Hβ-Hausdorff–Pompeiu b-metric for β∈[0,1] is introduced as a new variant of the Hausdorff–Pompeiu b-metric H. Various types of multi-valued Hβ-contractions are introduced and fixed point theorems are proved for such contractions in a b-metric space. The multi-valued Nadler contraction, Czervik contraction, q-quasi contraction, Hardy Rogers contraction, weak quasi contraction and Ciric contraction existing in literature are all one or the other type of multi-valued Hβ-contraction but the converse is not necessarily true. Proper examples are given in support of our claim. As applications of our results, we have proved the existence of a unique multi-valued fractal of an iterated multifunction system defined on a b-metric space and an existence theorem of Filippov type for an integral inclusion problem by introducing a generalized norm on the space of selections of the multifunction.
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Bertotti, Giovanni, and Vincenzo Picotti. "Comment on: “Uplift and contractional deformation along a segmented strike-slip fault system: the Gargano Promontory, southern Italy” by C.M. Brankman and A. Aydin[Journal of Structural Geology, 26, 807–824]." Journal of Structural Geology 26, no. 12 (December 2004): 2325–26. http://dx.doi.org/10.1016/j.jsg.2004.06.006.
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Morris, Lee G., and Scott L. Hooper. "Mechanisms Underlying Stabilization of Temporally Summated Muscle Contractions in the Lobster (Panulirus) Pyloric System." Journal of Neurophysiology 85, no. 1 (January 1, 2001): 254–68. http://dx.doi.org/10.1152/jn.2001.85.1.254.
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Muscles are the final effectors of behavior. The neural basis of behavior therefore cannot be completely understood without a description of the transfer function between neural output and muscle contraction. To this end, we have been studying muscle contraction in the well-investigated lobster pyloric system. We report here the mechanisms underlying stabilization of temporally summating contractions of the very slow dorsal dilator muscle in response to motor nerve stimulation with trains of rhythmic shock bursts at a physiological intraburst spike frequency (60 Hz), physiological cycle periods (0.5–2 s), and duty cycles from 0.1 to 0.8. For temporal summation to stabilize, the rise and relaxation amplitudes of the phasic contractions each burst induces must equalize as the rhythmic train continues. Stabilization could occur by changes in rise duration, rise slope, plateau duration, and/or relaxation slope. We demonstrate a generally applicable method for quantifying the relative contribution changes in these characteristics make to contraction stabilization. Our data show that all characteristics change as contractions stabilize, but their relative contribution differs depending on stimulation cycle period and duty cycle. The contribution of changes in rise duration did not depend on period or duty cycle for the 1-, 1.5-, and 2-s period regimes, contributing ∼30% in all cases; but for the 0.5-s period regime, changes in rise duration increased from contributing 25% to contributing 50% as duty cycle increased from 0.1 to 0.8. At all cycle periods decreases in rise slope contributed little to stabilization at small duty cycles but increased to contributing ∼80% at high duty cycles. The contribution of changes in plateau duration decreased in all cases as duty cycle increased; but this decrease was greater in long cycle period regimes. The contribution of changes in relaxation slope also decreased in all cases as duty cycle increased; but for this characteristic, the decrease was greatest in fast cycle period regimes, and in these regimes at high duty cycles these changes opposed contraction stabilization. Exponential fits to contraction relaxations showed that relaxation time constant increased with total contraction amplitude; this increase presumably underlies the decreased relaxation slope magnitude seen in high duty cycle, fast cycle period regimes. These data show that changes in no single contraction characteristic can account for contraction stabilization in this muscle and suggest that predicting muscle response in other systems in which slow muscles are driven by rapidly varying neuronal inputs may be similarly complex.
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Virych, P., O. Shelyuk, V. Martynyuk, and S. Chumakov. "The optical registration system for isometric contraction of smooth muscle." Bulletin of Taras Shevchenko National University of Kyiv. Series: Problems of Physiological Functions Regulation 20, no. 1 (2016): 11–14. http://dx.doi.org/10.17721/2616_6410.2016.20.11-14.
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The optical system registration of smooth muscle contraction in isometric mode was developed. Testing of system on smooth muscle strips of rat stomach and caecum was performed. It was tested the possibility of recording optical system spontaneous activity of smooth muscle. The resulting muscle contractions parameters correspond to the literature. Thus designed optical-mechanical method for detecting force and speed can be used for recording isometric contractions of smooth muscles of the stomach and caecum of rats and, therefore, to study the effect of different effectors their mechanokinetic.
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Mullins, Paula D., and Vladimir E. Bondarenko. "Mathematical model for β1-adrenergic regulation of the mouse ventricular myocyte contraction." American Journal of Physiology-Heart and Circulatory Physiology 318, no. 2 (February 1, 2020): H264—H282. http://dx.doi.org/10.1152/ajpheart.00492.2019.
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The β1-adrenergic regulation of cardiac myocyte contraction plays an important role in regulating heart function. Activation of this system leads to an increased heart rate and stronger myocyte contraction. However, chronic stimulation of the β1-adrenergic signaling system can lead to cardiac hypertrophy and heart failure. To understand the mechanisms of action of β1-adrenoceptors, a mathematical model of cardiac myocyte contraction that includes the β1-adrenergic system was developed and studied. The model was able to simulate major experimental protocols for measurements of steady-state force-calcium relationships, cross-bridge release rate and force development rate, force-velocity relationship, and force redevelopment rate. It also reproduced quite well frequency and isoproterenol dependencies for intracellular Ca2+ concentration ([Ca2+]i) transients, total contraction force, and sarcomere shortening. The mathematical model suggested the mechanisms of increased contraction force and myocyte shortening on stimulation of β1-adrenergic receptors is due to phosphorylation of troponin I and myosin-binding protein C and increased [Ca2+]i transient resulting from activation of the β1-adrenergic signaling system. The model was used to simulate work-loop contractions and estimate the power during the cardiac cycle as well as the effects of 4-aminopyridine and tedisamil on the myocyte contraction. The developed mathematical model can be used further for simulations of contraction of ventricular myocytes from genetically modified mice and myocytes from mice with chronic cardiac diseases. NEW & NOTEWORTHY A new mathematical model of mouse ventricular myocyte contraction that includes the β1-adrenergic system was developed. The model simulated major experimental protocols for myocyte contraction and predicted the effects of 4-aminopyridine and tedisamil on the myocyte contraction. The model also allowed for simulations of work-loop contractions and estimation of the power during the cardiac cycle.
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Dumke, C. L., J. Kim, E. B. Arias, and G. D. Cartee. "Role of kallikrein-kininogen system in insulin-stimulated glucose transport after muscle contractions." Journal of Applied Physiology 92, no. 2 (February 1, 2002): 657–64. http://dx.doi.org/10.1152/japplphysiol.00854.2001.
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Serum proteins [molecular weight (MW) > 10,000] are essential for increased insulin-stimulated glucose transport after in vitro muscle contractions. We investigated the role of the kallikrein-kininogen system, including bradykinin, which is derived from kallikrein (MW > 10,000)-catalyzed degradation of serum protein kininogen (MW > 10,000), on this contraction effect. In vitro electrical stimulation of rat epitrochlearis muscles was performed in 1) rat serum ± kallikrein inhibitors; 2) human plasma (normal or kallikrein-deficient); 3) rat serum ± bradykinin receptor-2 inhibitors; or 4) serum-free buffer ± bradykinin. 3- O-methylglucose transport (3-MGT) was measured 3.5 h later. Serum ± kallikrein inhibitors tended ( P = 0.08) to diminish postcontraction insulin-stimulated 3-MGT. Contractions in normal plasma enhanced insulin-stimulated 3-MGT vs. controls, but contractions in kallikrein-deficient plasma did not. Supplementing rat serum with bradykinin receptor antagonist HOE-140 during contraction did not alter insulin-stimulated 3-MGT. Muscles stimulated to contract in serum-free buffer plus bradykinin did not have enhanced insulin-stimulated 3-MGT. Bradykinin was insufficient for postcontraction-enhanced insulin sensitivity. However, results with kallikrein inhibitors and kallikrein-deficient plasma suggest kallikrein plays a role in this improved insulin action.