Sample records for abakaliki fold belt

  1. Numerical modeling of fold-and-thrust belts: Applications to Kuqa foreland fold belt, China

    NASA Astrophysics Data System (ADS)

    Yin, H.; Morgan, J. K.; Zhang, J.; Wang, Z.

    2009-12-01

    We constructed discrete element models to simulate the evolution of fold-and-thrust belts. The impact of rock competence and decollement strength on the geometric pattern and deformation mechanics of fold-and-thrust belts has been investigated. The models reproduced some characteristic features of fold-and-thrust belts, such as faulted detachment folds, pop-ups, far-traveled thrust sheets, passive-roof duplexes, and back thrusts. In general, deformation propagates farther above a weak decollement than above a strong decollement. Our model results confirm that fold-and-thrust belts with strong frictional decollements develop relatively steep and narrow wedges formed by closely spaced imbricate thrust slices, whereas fold belts with weak decollements form wide low-taper wedges composed of faulted detachment folds, pop-ups, and back thrusts. Far-traveled thrust sheets and passive-roof duplexes are observed in the model with a strong lower decollement and a weak upper detachment. Model results also indicate that the thickness of the weak layer is critical. If it is thick enough, it acts as a ductile layer that is able to flow under differential stress, which helps to partition deformation above and below it. The discrete element modeling results were used to interpret the evolution of Kuqa Cenozoic fold-and-thrust belt along northern Tarim basin, China. Seismic and well data show that the widely distributed Paleogene rock salt has a significant impact on the deformation in this area. Structures beneath salt are closely spaced imbricate thrust and passive-roof duplex systems. Deformation above salt propagates much farther than below the salt. Faults above salt are relatively wide spaced. A huge controversy over the Kuqa fold-and-thrust belt is whether it is thin-skinned or thick-skinned. With the insights from DEM results, we suggest that Kuqa structures are mostly thin-skinned with Paleogene salt as decollement, except for the rear part near the backstop, where the

  2. Folding kinematics expressed in fracture patterns: An example from the Anti-Atlas fold belt, Morocco

    NASA Astrophysics Data System (ADS)

    Ismat, Zeshan

    2008-11-01

    The Anti-Atlas fold belt, Morocco, formed during the same Variscan collisional event that produced the Valley-and-Ridge fold-thrust belt of the Appalachian mountains. Both are external belts of the Appalachian-Ouachita-Mauritanides chain and at the map scale have very similar topographic expressions. The Anti-Atlas, however, consists of map-scale folds that are buckle-related, detachment folds, whereas the Valley-and-Ridge folds developed in response to imbricate thrusting. For this reason, the Anti-Atlas is referred to as a fold belt rather than a fold-thrust belt. This paper examines Variscan folding processes in the Anti-Atlas Mountains. Folding in some layers occurred by sliding along a penetrative network of mesoscale fractures, i.e. cataclastic flow, during buckling. Layer-parallel shortening fractures were reactivated in the later stages of folding to accommodate limb rotation. Although 'boutonnieres', i.e. basement uplifts, punctuate the fold belt, the fracture patterns indicate that the uplifts failed to provide any 'bending' component. Folding is also interpreted to occur under low to moderate confining pressures because the fracture network includes conjugate shear fractures with very small (˜20°) dihedral angles.

  3. Deformation and kinematics of the central Kirthar Fold Belt, Pakistan

    NASA Astrophysics Data System (ADS)

    Hinsch, Ralph; Hagedorn, Peter; Asmar, Chloé; Nasim, Muhammad; Aamir Rasheed, Muhammad; Kiely, James M.

    2017-04-01

    The Kirthar Fold Belt is part of the lateral mountain belts in Pakistan linking the Himalaya orogeny with the Makran accretionary wedge. This region is deforming very oblique/nearly parallel to the regional plate motion vector. The study area is situated between the prominent Chaman strike-slip fault in the West and the un-deformed foreland (Kirthar Foredeep/Middle Indus Basin) in the East. The Kirthar Fold Belt is subdivided into several crustal blocks/units based on structural orientation and deformation style (e.g. Kallat, Khuzdar, frontal Kirthar). This study uses newly acquired and depth-migrated 2D seismic lines, surface geology observations and Google Earth assessments to construct three balanced cross sections for the frontal part of the fold belt. Further work was done in order to insure the coherency of the built cross-sections by taking a closer look at the regional context inferred from published data, simple analogue modelling, and constructed regional sketch sections. The Khuzdar area and the frontal Kirthar Fold Belt are dominated by folding. Large thrusts with major stratigraphic repetitions are not observed. Furthermore, strike-slip faults in the Khuzdar area are scarce and not observed in the frontal Kirthar Fold Belt. The regional structural elevation rises from the foreland across the Kirthar Fold Belt towards the hinterland (Khuzdar area). These observations indicate that basement-involved deformation is present at depth. The domination of folding indicates a weak decollement below the folds (soft-linked deformation). The fold pattern in the Khuzdar area is complex, whereas the large folds of the central Kirthar Fold Belt trend SSW-NNE to N-S and are best described as large detachment folds that have been slightly uplifted by basement involved transpressive deformation underneath. Towards the foreland, the deformation is apparently more hard-linked and involves fault-propagation folding and a small triangle zone in Cretaceous sediments

  4. Fault-related fold styles and progressions in fold-thrust belts: Insights from sandbox modeling

    NASA Astrophysics Data System (ADS)

    Yan, Dan-Ping; Xu, Yan-Bo; Dong, Zhou-Bin; Qiu, Liang; Zhang, Sen; Wells, Michael

    2016-03-01

    Fault-related folds of variable structural styles and assemblages commonly coexist in orogenic belts with competent-incompetent interlayered sequences. Despite their commonality, the kinematic evolution of these structural styles and assemblages are often loosely constrained because multiple solutions exist in their structural progression during tectonic restoration. We use a sandbox modeling instrument with a particle image velocimetry monitor to test four designed sandbox models with multilayer competent-incompetent materials. Test results reveal that decollement folds initiate along selected incompetent layers with decreasing velocity difference and constant vorticity difference between the hanging wall and footwall of the initial fault tips. The decollement folds are progressively converted to fault-propagation folds and fault-bend folds through development of fault ramps breaking across competent layers and are followed by propagation into fault flats within an upper incompetent layer. Thick-skinned thrust is produced by initiating a decollement fault within the metamorphic basement. Progressive thrusting and uplifting of the thick-skinned thrust trigger initiation of the uppermost incompetent decollement with formation of a decollement fold and subsequent converting to fault-propagation and fault-bend folds, which combine together to form imbricate thrust. Breakouts at the base of the early formed fault ramps along the lowest incompetent layers, which may correspond to basement-cover contacts, domes the upmost decollement and imbricate thrusts to form passive roof duplexes and constitute the thin-skinned thrust belt. Structural styles and assemblages in each of tectonic stages are similar to that in the representative orogenic belts in the South China, Southern Appalachians, and Alpine orogenic belts.

  5. Modelling of lateral fold growth and fold linkage: Applications to fold-and-thrust belt tectonics

    NASA Astrophysics Data System (ADS)

    Grasemann, Bernhard; Schmalholz, Stefan

    2013-04-01

    We use a finite element model to investigate the three-dimensional fold growth and interference of two initially isolated fold segments. The most critical parameter, which controls the fold linkage mode, is the phase difference between the laterally growing fold hinge lines: 1) "Linear-linkage" yields a sub-cylindrical fold with a saddle at the location where the two initial folds linked. 2) "Oblique-linkage" produces a curved fold resembling a Type II refold structure. 3) "Oblique-no-linkage" results in two curved folds with fold axes plunging in opposite directions. 4) "Linear-no-linkage" yields a fold train of two separate sub-cylindrical folds with fold axes plunging in opposite directions. The transition from linkage to no-linkage occurs when the fold separation between the initially isolated folds is slightly larger than one half of the low-amplitude fold wavelength. The model results compare well with previously published plasticine analogue models and can be directly applied to the investigation of fold growth history in fold-and-thust belts. An excellent natural example of lateral fold linkage is described from the Zagros fold-and-thrust belt in the Kurdistan Region of Iraq. The fold growth in this region is not controlled by major thrust faults but the shortening of the Paleozoic to Cenozoic passive margin sediments of the Arabian plate occurred mainly by detachment folding. The sub-cylindrical anticlines with hinge-parallel lengths of more than 50 km have not developed from single sub-cylindrical embryonic folds but they have merged from different fold segments that joined laterally during fold amplification and lateral fold growth. Linkage points are marked by geomorphological saddle points which are structurally the lowermost points of antiforms and points of principal curvatures with opposite sign. Linkage points can significantly influence the migration of mineral-rich fluids and hydrocarbons and are therefore of great economic importance.

  6. Origin of the Uinta recess, Sevier fold thrust belt, Utah: influence of basin architecture on fold thrust belt geometry

    NASA Astrophysics Data System (ADS)

    Paulsen, Timothy; Marshak, Stephen

    1999-11-01

    Structural trends in the Sevier fold-thrust belt define a pronounced concave-to-the-foreland map-view curve, the Uinta recess, in north-central Utah. This recess separates two convex-to-the-foreland curves, the Provo salient on the south and the Wyoming salient on the north. The two limbs of the recess comprise transverse zones (fault zones at a high-angle to the regional trend of the orogen) that border the flanks of the east-west-trending Uinta/Cottonwood arch. Our structural analysis indicates that the transverse zones formed during the Sevier orogeny, and that they differ markedly from each other in structural style. The Charleston transverse zone (CTZ), on the south side of the arch, initiated as a complex sinistral strike-slip fault system that defines the abrupt northern boundary of the Provo salient. The Mount Raymond transverse zone (MRTZ), on the north side of the arch, represents the region in which the southeast-verging southern limb of the gently curving Wyoming salient was tilted northwards during the Laramide phase of uplift of the Uinta/Cottonwood arch. In effect, the MRTZ represents an oblique cross section through a thrust belt. The contrasting architecture of these transverse zones demonstrates how pre-deformation basin geometry influences the geometry of a fold-thrust belt. Analysis of isopach maps indicates that, at the time the Sevier fold-thrust belt formed, the area just north of the present site of the Uinta/Cottonwood arch was a basement high, with a gently dipping north flank, and a steeply dipping south flank. Thus, predeformational sediment thickened abruptly to the south of the high and thickened gradually to the north of the high. As illustrated by sandbox models, the distance that a fold-thrust belt propagates into the foreland depends on the thickness of the sedimentary layer being deformed, so the shape of the salient mimics the longitudinal cross-sectional shape of the sedimentary basin. Where basins taper gradually along strike

  7. Non-cylindrical fold growth in the Zagros fold and thrust belt (Kurdistan, NE-Iraq)

    NASA Astrophysics Data System (ADS)

    Bartl, Nikolaus; Bretis, Bernhard; Grasemann, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros mountains extends over 1800 km from Kurdistan in N-Iraq to the Strait of Hormuz in Iran and is one of the world most promising regions for the future hydrocarbon exploration. The Zagros Mountains started to form as a result of the collision between the Eurasian and Arabian Plates, whose convergence began in the Late Cretaceous as part of the Alpine-Himalayan orogenic system. Geodetic and seismological data document that both plates are still converging and that the fold and thrust belt of the Zagros is actively growing. Extensive hydrocarbon exploration mainly focuses on the antiforms of this fold and thrust belt and therefore the growth history of the folds is of great importance. This work investigates by means of structural field work and quantitative geomorphological techniques the progressive fold growth of the Permam, Bana Bawi- and Safeen- Anticlines located in the NE of the city of Erbil in the Kurdistan region of Northern Iraq. This part of the Zagros fold and thrust belt belongs to the so-called Simply Folded Belt, which is dominated by gentle to open folding. Faults or fault related folds have only minor importance. The mechanical anisotropy of the formations consisting of a succession of relatively competent (massive dolomite and limestone) and incompetent (claystone and siltstone) sediments essentially controls the deformation pattern with open to gentle parallel folding of the competent layers and flexural flow folding of the incompetent layers. The characteristic wavelength of the fold trains is around 10 km. Due to faster erosion of the softer rock layers in the folded sequence, the more competent lithologies form sharp ridges with steeply sloping sides along the eroded flanks of the anticlines. Using an ASTER digital elevation model in combination with geological field data we quantified 250 drainage basins along the different limbs of the subcylindrical Permam, Bana Bawi- and Safeen- Anticlines. Geomorphological indices of the drainage

  8. Kink-style detachment folding in Bachu fold belt of central Tarim Basin, China: geometry and seismic interpretation

    NASA Astrophysics Data System (ADS)

    Bo, Zhang; Jinjiang, Zhang; Shuyu, Yan; Jiang, Liu; Jinhai, Zhang; Zhongpei, Zhang

    2010-05-01

    The phenomenon of Kink banding is well known throughout the engineering and geophysical sciences. Associated with layered structures compressed in a layer-parallel direction, it arises for example in stratified geological systems under tectonic compression. Our work documented it is also possible to develop super large-scale kink-bands in sedimentary sequences. We interpret the Bachu fold uplift belt of the central Tarim basin in western China to be composed of detachment folds flanked by megascopic-scale kink-bands. Those previous principal fold models for the Bachu uplift belt incorporated components of large-scale thrust faulting, such as the imbricate fault-related fold model and the high-angle, reverse-faulted detachment fold model. Based on our observations in the outcrops and on the two-dimension seismic profiles, we interpret that first-order structures in the region are kink-band style detachment folds to accommodate regional shortening, and thrust faulting can be a second-order deformation style occurring on the limb of the detachment folds or at the cores of some folds to accommodate the further strain of these folds. The belt mainly consists of detachment folds overlying a ductile decollement layer. The crests of the detachment folds are bounded by large-scale kink-bands, which are zones of angularly folded strata. These low-signal-tonoise, low-reflectivity zones observed on seismic profiles across the Bachu belt are poorly imaged sections, which resulted from steeply dipping bedding in the kink-bands. The substantial width (beyond 200m) of these low-reflectivity zones, their sub-parallel edges in cross section, and their orientations at a high angle to layering between 50 and 60 degrees, as well as their conjugate geometry, support a kink-band interpretation. The kink-band interpretation model is based on the Maximum Effective Moment Criteria for continuous deformation, rather than Mohr-Column Criteria for brittle fracture. Seismic modeling is done to

  9. The Zagros hinterland fold-and-thrust belt in-sequence thrusting, Iran

    NASA Astrophysics Data System (ADS)

    Sarkarinejad, Khalil; Ghanbarian, Mohammad Ali

    2014-05-01

    The collision of the Iranian microcontinent with the Afro-Arabian continent resulted in the deformation of the Zagros orogenic belt. The foreland of this belt in the Persian Gulf and Arabian platform has been investigated for its petroleum and gas resource potentials, but the Zagros hinterland is poorly investigated and our knowledge about its deformation is much less than other parts of this orogen. Therefore, this work presents a new geological map, stratigraphic column and two detailed geological cross sections. This study indicates the presence of a hinterland fold-and-thrust belt on northeastern side of the Zagros orogenic core that consists of in-sequence thrusting and basement involvement in this important part of the Zagros hinterland. The in-sequence thrusting resulted in first- and second-order duplex systems, Mode I fault-bend folding, fault-propagation folding and asymmetric detachment folding which indicate close relationships between folding and thrusting. Study of fault-bend folds shows that layer-parallel simple shear has the same role in the southeastern and northwestern parts of the study area (αe = 23.4 ± 9.1°). A major lateral ramp in the basement beneath the Talaee plain with about one kilometer of vertical offset formed parallel to the SW movement direction and perpendicular to the major folding and thrusting.

  10. Comparison of fault-related folding algorithms to restore a fold-and-thrust-belt

    NASA Astrophysics Data System (ADS)

    Brandes, Christian; Tanner, David

    2017-04-01

    Fault-related folding means the contemporaneous evolution of folds as a consequence of fault movement. It is a common deformation process in the upper crust that occurs worldwide in accretionary wedges, fold-and-thrust belts, and intra-plate settings, in either strike-slip, compressional, or extensional regimes. Over the last 30 years different algorithms have been developed to simulate the kinematic evolution of fault-related folds. All these models of fault-related folding include similar simplifications and limitations and use the same kinematic behaviour throughout the model (Brandes & Tanner, 2014). We used a natural example of fault-related folding from the Limón fold-and-thrust belt in eastern Costa Rica to test two different algorithms and to compare the resulting geometries. A thrust fault and its hanging-wall anticline were restored using both the trishear method (Allmendinger, 1998; Zehnder & Allmendinger, 2000) and the fault-parallel flow approach (Ziesch et al. 2014); both methods are widely used in academia and industry. The resulting hanging-wall folds above the thrust fault are restored in substantially different fashions. This is largely a function of the propagation-to-slip ratio of the thrust, which controls the geometry of the related anticline. Understanding the controlling factors for anticline evolution is important for the evaluation of potential hydrocarbon reservoirs and the characterization of fault processes. References: Allmendinger, R.W., 1998. Inverse and forward numerical modeling of trishear fault propagation folds. Tectonics, 17, 640-656. Brandes, C., Tanner, D.C. 2014. Fault-related folding: a review of kinematic models and their application. Earth Science Reviews, 138, 352-370. Zehnder, A.T., Allmendinger, R.W., 2000. Velocity field for the trishear model. Journal of Structural Geology, 22, 1009-1014. Ziesch, J., Tanner, D.C., Krawczyk, C.M. 2014. Strain associated with the fault-parallel flow algorithm during kinematic fault

  11. Kink detachment fold in the southwest Montana fold and thrust belt

    NASA Astrophysics Data System (ADS)

    Mitchell, Michael M.; Woodward, Nicholas B.

    1988-02-01

    The Hossfeldt anticline in the southwest Montana thrust belt is characterized by a kink geometry and probably overlies a thrust detachment at depth. The mesofabric distribution in the limbs documents that the eastern overturned limb has undergone most of the rotation and internal deformation during folding, leaving the gently dipping western limb virtually undeformed. The anticline exhibits unique mesofabrics in its hinge region that require a pinned anticlinal hinge during its evolution. The half-wavelength of the Hossfeldt anticline-Eustis syncline pair coincides with that predicted from buckling theory, if one considers the massive carbonates of the Paleozoic section as a competent beam. Although the geometry and mesofabric distribution of the Hossfeldt anticline satisfy the geometric requirements of either a fault-propagation fold or a detachment kink fold, the buckling wavelength strongly suggests that its origin was as a kink-buckle fold above a flat detachment rather than as a fault-propagation fold above a thrust ramp.

  12. Detachments in Shale: Controlling Characteristics on Fold-Thrust Belt Style

    NASA Astrophysics Data System (ADS)

    Hansberry, Rowan; King, Ros; Collins, Alan; Morley, Chris

    2013-04-01

    Fold-thrust belts occur across multiple tectonic settings where thin-skinned deformation is accommodated by one or more detachment zones, both basal and within the fold-thrust belt. These fold-thrust belts exhibit considerable variation in structural style and vergence depending on the characteristics (e.g. strength, thickness, and lithology) and number of detachment zones. Shale as a detachment lithology is intrinsically weaker than more competent silts and sands; however, it can be further weakened by high pore pressures, reducing resistance to sliding and; high temperatures, altering the rheology of the detachment. Despite the implications for petroleum exploration and natural hazard assessment the precise nature by which detachments in shale control and are involved in deformation in fold-thrust belts is poorly understood. Present-day active basal detachment zones are usually located in inaccessible submarine regions. Therefore, this project employs field observations and sample analysis of ancient, exhumed analogues to document the nature of shale detachments (e.g. thickness, lithology, dip and dip direction, deformational temperature and thrust propagation rates) at field sites in Thailand, Norway and New Zealand. X-ray diffraction analysis of illite crystallinity and oxygen stable isotopes analysis are used as a proxy for deformational temperature whilst electron-backscatter diffraction analysis is used to constrain microstructural deformational patterns. K-Ar dating of synkinematic clay fault gouges is being applied to date the final stages of activity on individual faults with a view to constraining thrust activation sequences. It is not possible to directly measure palaeo-data for some key detachment parameters, such as pore pressure and coefficients of friction. However, the use of critical taper wedge theory has been used to successfully infer internal and basal coefficients of friction and depth-normalized pore pressure within a wedge and at its base

  13. Generation of buckle folds in Naga fold thrust belt, north-east India

    NASA Astrophysics Data System (ADS)

    Saha, B.; Dietl, C.

    2009-04-01

    Naga fold thrust belt (NFTB), India, formed as a result of northward migration of the Indian plate initiated in Eocene and its subsequent collision with the Burmese plate during Oligocene. The NW-SE oriented compression generated a spectrum of structures; among them, we intend to focus on the folds- varying from gentle to tight asymmetric in geometry. Large recumbent folds are often associated with thrusting. Buckle folds forming under shallow crustal conditions are frequently reported from NFTB. Buckle folding occurs mainly within sandstones with intercalated shale layers which are in the study area typical for the Barail, Surma and Tipam Groups. We have tried to explain the controlling factors behind the variation of the buckle fold shapes and their varying wavelengths throughout the fold thrust belt with the aid of analogue (sand box) modelling. It is undoubted that competence contrast along with the layer parallel compressive stress are the major influencing factors in generation of buckle folds. Schmalholz and Podladchikov (1999) and Jeng et al. (2002) have shown that when low strain rate and low temperature are applicable, not only the viscosity contrast, but also the elasticity contrast govern the geometry of the developing buckle folds. Rocks deforming under high temperature and high pressure deform in pure viscous manner, whereas, rocks undergoing less confining stress and less temperature, are subjected to pure elastic deformation. However, they are the end members, and most of the deformations are a combination of these two end members, i.e. of viscoelastic nature. Our models are made up of sieved sand (0.5 mm grain size) and mica layers (1-5 mm) This interlayering imparts a mechanical anisotropy in the model. Mica is not a pure viscous material, rather it displays more elastic behaviour. The mica layers in the model produce bedding parallel slip during shortening through internal reorganization of the individual mica crystals leading to the thickening

  14. Formation of fold-and-thrust belts on Venus by thick-skinned deformation

    NASA Astrophysics Data System (ADS)

    Zuber, M. T.; Parmentier, E. M.

    1995-10-01

    ON Venus, fold-and-thrust belts—which accommodate large-scale horizontal crustal convergence—are often located at the margins of kilometre-high plateaux1-5. Such mountain belts, typically hundreds of kilometres long and tens to hundreds of kilometres wide, surround the Lakshmi Planum plateau in the Ishtar Terra highland (Fig. 1). In explaining the origin of fold-and-thrust belts, it is important to understand the relative importance of thick-skinned deformation of the whole lithosphere and thin-skinned, large-scale overthrusting of near-surface layers. Previous quantitative analyses of mountain belts on Venus have been restricted to thin-skinned models6-8, but this style of deformation does not account for the pronounced topographic highs at the plateau edge. We propose that the long-wavelength topography of these venusian fold-and-thrust belts is more readily explained by horizontal shortening of a laterally heterogeneous lithosphere. In this thick-skinned model, deformation within the mechanically strong outer layer of Venus controls mountain building. Our results suggest that lateral variations in either the thermal or mechanical structure of the interior provide a mechanism for focusing deformation due to convergent, global-scale forces on Venus.

  15. Cenozoic structural evolution, thermal history, and erosion of the Ukrainian Carpathians fold-thrust belt

    NASA Astrophysics Data System (ADS)

    Nakapelyukh, Mykhaylo; Bubniak, Ihor; Bubniak, Andriy; Jonckheere, Raymond; Ratschbacher, Lothar

    2018-01-01

    The Carpathians are part of the Alpine-Carpathian-Dinaridic orogen surrounding the Pannonian basin. Their Ukrainian part constitutes an ancient subduction-accretion complex that evolved into a foreland fold-thrust belt with a shortening history that was perpendicular to the orogenic strike. Herein, we constrain the evolution of the Ukrainian part of the Carpathian fold-thrust belt by apatite fission-track dating of sedimentary and volcanic samples and cross-section balancing and restoration. The apatite fission-track ages are uniform in the inner―southwestern part of the fold-thrust belt, implying post-shortening erosion since 12-10 Ma. The ages in the leading and trailing edges record provenance, i.e., sources in the Trans-European suture zone and the Inner Carpathians, respectively, and show that these parts of the fold-thrust were not heated to more than 100 °C. Syn-orogenic strata show sediment recycling: in the interior of the fold-thrust belt―the most thickened and most deeply eroded nappes―the apatite ages were reset, eroded, and redeposited in the syn-orogenic strata closer to the fore- and hinterland; the lag times are only a few million years. Two balanced cross sections, one constructed for this study and based on field and subsurface data, reveal an architecture characterized by nappe stacks separated by high-displacement thrusts; they record 340-390 km shortening. A kinematic forward model highlights the fold-thrust belt evolution from the pre-contractional configuration over the intermediate geometries during folding and thrusting and the post-shortening, erosional-unloading configuration at 12-10 Ma to the present-day geometry. Average shortening rates between 32-20 Ma and 20-12 Ma amounted to 13 and 21 km/Ma, respectively, implying a two-phased deformation of the Ukrainian fold-thrust belt.

  16. Critical taper wedge mechanics of fold-and-thrust belts on Venus - Initial results from Magellan

    NASA Technical Reports Server (NTRS)

    Suppe, John; Connors, Chris

    1992-01-01

    Examples of fold-and-thrust belts from a variety of tectonic settings on Venus are introduced. Predictions for the mechanics of fold-and-thrust belts on Venus are examined on the basis of wedge theory, rock mechanics data, and currently known conditions on Venus. The theoretical predictions are then compared with new Magellan data.

  17. Shear zones of the Verkhoyansk fold-and-thrust belt, Northeast Russia

    NASA Astrophysics Data System (ADS)

    Fridovsky, Valery; Polufuntikova, Lena

    2017-04-01

    The Verkhoyansk fold-and-thrust belt is situated on the submerged eastern margin of the North Asian craton, and is largely composed of the Ediacaran - Middle Paleozoic carbonate and the Upper Paleozoic-Mesozoic terrigenous rocks. The Upper Carboniferous - Jurassic sediments constitute the Verkhoyansk terrigenous complex containing economically viable orogenic gold deposits. The structure of the belt is mainly controlled by thrusts and associated diagonal strike slips. Linear concentric folds are common all over the area of the belt. Shear zones with associated similar folds are confined to long narrow areas. Shear zones were formed during the early stages of the Oxfordian-Kimmeridgian collisional and accretionary events prior to the emplacement of large orogenic granitoid plutons. The main ore-controlling structures are shear zones associated with slaty cleavage, shear folds, mullion- and boudinage-structures, and transposition features. The shear zones are listric-type, and represent branches of a detachment structure, which is assumed to be present at the base of the Verkhoyansk fold-and-thrust belt. A vertical zonation of shear zones is correlated with the distance to the detachment. Changes in the dip angle of the shear zones (as indicated mainly by cleavage), structural paragenesis, the degree of microdeformation of the host rocks, and the type of ore-controlling structures can be clearly observed in the direction away from the detachment. Structural zoning is evidenced, among other things, by changing morphologic types of microstructures and by strain-indicators of the degree of rock metamorphism. Four morphologic types of microstructures are identified. The first platy-shear type is characterized by aggregate cleavage and the coefficient of deformation (Cd) of single grains from 1.0 to 2.0. Irregular angular fragments of variously oriented grains can be observed in thin sections. The second shear-cataclastic morphologic type (Cd from 2.0 to 3.0) exhibits

  18. Geometry and Kinematics of the Lamu Basin Deep-Water Fold-and-Thrust Belt (East Africa)

    NASA Astrophysics Data System (ADS)

    Barchi, Massimiliano R.; Cruciani, Francesco; Porreca, Massimiliano

    2016-04-01

    Even if most thin-skinned fold-and-thrust belt are generated at convergent plate boundaries, in the last decades advances in seismic exploration and acquisition of large datasets have shown that they are also notably widespread along continental passive margins, driven by gravity processes in deep-water areas. In this study a composite set of modern and vintage reprocessed seismic reflection profiles is used to investigate the internal structure and kinematic evolution of the Lamu Basin Deep-Water Fold-and-Trust Belt (DW-FTB). The Lamu Basin is an example of giant-scale, gravity driven compressional belt developed in Late Cretaceous-Early Tertiary along a still poorly explored sector of the East-African continental margin, at the Kenya-Somalia border. The compressional domain extends longitudinally for more than 450 km, is up to 180 km wide and shows remarkable structural complexity both along strike and along dip. The external part is dominated by ocean-verging imbricate thrusts, above a gently landward-dipping basal detachment. The internal part is characterised by almost symmetrical detachment folds and double verging structures, sustaining bowl-shaped syn-tectonic basins. Here the basal detachment surface is almost flat. The mean fold wavelength displays a progressive landward increase, from 2.5 km, at the toe of the belt, to about 10 km. This structural variability is thought to be related to the lateral variation of the section under shortening and particularly to the different thickness of the Early Cretaceous shaly unit involved in the deformations, increasing landward from about 400 m to more than 1 km. Through the sequential restoration of regional cross-sections, we evaluated that the northern portion of the thrust belt experienced a shortening of almost 50 km (corresponding to 20%), with a shortening rate (during the Late Cretaceous-Paleocene main event) of about 3.5 mm/yr. Under many respects, the dimensions and internal structure of this thrust belt

  19. Modeling of wind gap formation and development of sedimentary basins during fold growth: application to the Zagros Fold Belt, Iran.

    NASA Astrophysics Data System (ADS)

    Collignon, Marine; Yamato, Philippe; Castelltort, Sébastien; Kaus, Boris

    2016-04-01

    Mountain building and landscape evolution are controlled by the interactions between river dynamics and tectonic forces. Such interactions have been largely studied but a quantitative evaluation of tectonic/geomorphic feedbacks remains required for understanding sediments routing within orogens and fold-and-thrust belts. Here, we employ numerical simulations to assess the conditions of uplift and river incision necessary to deflect an antecedent drainage network during the growth of one or several folds. We propose that a partitioning of the river network into internal (endorheic) and longitudinal drainage arises as a result of lithological differences within the deforming crustal sedimentary cover. We show with examples from the Zagros Fold Belt (ZFB) that drainage patterns can be linked to the incision ratio R between successive lithological layers, corresponding to the ratio between their relative erodibilities or incision coefficients. Transverse drainage networks develop for uplift rates smaller than 0.8 mm.yr-1 and -10 < R < 10. Intermediate drainage network are obtained for uplift rates up to 2 mm.yr-1 and incision ratios of 20. Parallel drainage networks and formation of sedimentary basins occur for large values of incision ratio (R >20) and uplift rates between 1 and 2 mm.yr-1. These results have implications for predicting the distribution of sediment depocenters in fold-and-thrust belts, which can be of direct economic interest for hydrocarbon exploration.

  20. Quantification of fold growth of frontal antiforms in the Zagros fold and thrust belt (Kurdistan, NE Iraq)

    NASA Astrophysics Data System (ADS)

    Bretis, Bernhard; Bartl, Nikolaus; Graseman, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros fold and thrust belt is a seismically active orogen, where actual kinematic models based on GPS networks suggest a north-south shortening between Arabian and Eurasian in the order of 1.5-2.5 cm/yr. Most of this deformation is partitioned in south-southwest oriented folding and thrusting with northwest-southeast to north-south trending dextral strike slip faults. The Zagros fold and thrust belt is of great economic interest because it has been estimated that this area contains about 15% of the global recoverable hydrocarbons. Whereas the SE parts of the Zagros have been investigated by detailed geological studies, the NW extent being part of the Republic of Iraq have experienced considerably less attention. In this study we combine field work and remote sensing techniques in order to investigate the interaction of erosion and fold growth in the area NE of Erbil (Kurdistan, Iraq). In particular we focus on the interaction of the transient development of drainage patterns along growing antiforms, which directly reflects the kinematics of progressive fold growth. Detailed geomorphological studies of the Bana Bawi-, Permam- and Safeen fold trains show that these anticlines have not developed from subcylindrical embryonic folds but they have merged from different fold segments that joined laterally during fold amplification. This fold segments with length between 5 and 25 km have been detected by mapping ancient and modern river courses that initially cut the nose of growing folds and eventually got defeated leaving behind a wind gap. Fold segments, propagating in different directions force rivers to join resulting in steep gorges, which dissect the merging fold noses. Along rapidly lateral growing folds (e.g. at the SE end of the Bana Bawi Anticline) we observed "curved wind gaps", a new type of abandoned river course, where form of the wind gap mimics a formed nose of a growing antiform. The inherited curved segments of uplifted curved river courses strongly

  1. Regional magnetic anomalies, crustal strength, and the location of the northern Cordilleran fold-and-thrust belt

    USGS Publications Warehouse

    Saltus, R.W.; Hudson, T.L.

    2007-01-01

    The northern Cordilleran fold-and-thrust belt in Canada and Alaska is at the boundary between the broad continental margin mobile belt and the stable North American craton. The fold-and-thrust belt is marked by several significant changes in geometry: cratonward extensions in the central Yukon Territory and northeastern Alaska are separated by marginward re-entrants. These geometric features of the Cordilleran mobile belt are controlled by relations between lithospheric strength and compressional tectonic forces developed along the continental margin. Regional magnetic anomalies indicate deep thermal and compositional characteristics that contribute to variations in crustal strength. Our detailed analysis of one such anomaly, the North Slope deep magnetic high, helps to explain the geometry of the fold-and-thrust front in northern Alaska. This large magnetic anomaly is inferred to reflect voluminous mafic magmatism in an old (Devonian?) extensional domain. The presence of massive amounts of malic material in the lower crust implies geochemical depletion of the underlying upper mantle, which serves to strengthen the lithosphere against thermal erosion by upper mantle convection. We infer that deep-source magnetic highs are an important indicator of strong lower crust and upper mantle. This stronger lithosphere forms buttresses that play an important role in the structural development of the northern Cordilleran fold-and-thrust belt. ?? 2007 The Geological Society of America.

  2. The Port Isabel Fold Belt: Salt enhanced Neogene Gravitational Spreading in the East Breaks, Western Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Lebit, Hermann; Clavaud, Marie; Whitehead, Sam; Opdyke, Scott; Luneburg, Catalina

    2017-04-01

    The Port Isabel fold belt is situated at the northwestern corner of the deep water Gulf of Mexico where the regional E-W trending Texas-Louisiana shelf bends into the NNE-SSW trend of the East Mexico Shelf. The fold belt forms an allochthonous wedge that ramps up from West to East with its front occupied by shallow salt complexes (local canopies). It is assumed that the belt predominantly comprises Oligocene siliciclastic sequences which reveal eastward facing folds and thrusts with a NE-SW regional trend. The structural architecture of the fold belt is very well imaged on recently processed 3D seismic volumes. Crystal III is a wide-azimuth survey acquired in 2011 and reprocessed in 2016 leveraging newly developed state-of-the-art technology. 3D deghosting, directional designature and multi-model 3D SRME resulted in broader frequency spectrum. The new image benefits from unique implementation of FWI, combined with classic tomographic updates. Seismically transparent zones indicating over-pressured shales are limited to the core of anticlines or to the footwall of internal thrust. Mobile shales associated with diapirs are absent in the study area. In contrast, salt is mobile and apparently forms the major decollement of the PIFB as indicated by remnant salt preferentially located in triangles along the major thrusts and fault intersections or at the core of anticlines. Shallow salt diapirs seam to root in the fold belt, while lacking evidence for salt feeders being connected to the deep salt underlying the Mesozoic to Paleogene substratum of the fold belt. Towards the WNW the fold belt is transient into a extensional regime, characterized by roll-over structures associated with deep reaching normal faults which form ultra-deep mini basins filled with Neogene deposits. Kinematic restorations confirm the simultaneous evolution of the deep mini basins and the outboard fold belt. This resembles a gravitational spreading system with the extensional tectonics of the deep

  3. Fold and thrust partitioning in a contracting fold belt: Insights from the 1931 Mach earthquake in Baluchistan

    NASA Astrophysics Data System (ADS)

    Szeliga, Walter; Bilham, Roger; Schelling, Daniel; Kakar, Din Mohamed; Lodi, Sarosh

    2009-10-01

    Surface deformation associated with the 27 August 1931 earthquake near Mach in Baluchistan is quantified from spirit-leveling data and from detailed structural sections of the region interpreted from seismic reflection data constrained by numerous well logs. Mean slip on the west dipping Dezghat/Bannh fault system amounted to 1.2 m on a 42 km × 72 km thrust plane with slip locally attaining 3.2 m up dip of an inferred locking line at ˜9 km depth. Slip also occurred at depths below the interseismic locking line. In contrast, negligible slip occurred in the 4 km near the interseismic locking line. The absence of slip here in the 4 years following the earthquake suggests that elastic energy there must either dissipate slowly in the interseismic cycle, or that a slip deficit remains, pending its release in a large future earthquake. Elastic models of the earthquake cycle in this fold and thrust belt suggest that slip on the frontal thrust fault is reduced by a factor of 2 to 8 compared to that anticipated from convergence of the hinterland, a partitioning process that is presumably responsible for thickening of the fold and thrust belt at the expense of slip on the frontal thrust. Near the latitude of Quetta, GPS measurements indicate that convergence is ˜5 mm/yr. Hence the minimum renewal time between earthquakes with 1.2-m mean displacement should be as little as 240 years. However, when the partitioning of fold belt convergence to frontal thrust slip is taken into account the minimum renewal time may exceed 2000 years.

  4. Permian paleomagnetism of the Tien Shan fold belt, Central Asia: post-collisional rotations and deformation

    NASA Astrophysics Data System (ADS)

    Bazhenov, Mikhail L.; S. Burtman, Valentin; Dvorova, Ariadna V.

    1999-11-01

    Permian volcanic and sedimentary rocks were sampled from eight localities in the western and central parts of the Tien Shan fold belt. High-temperature, sometimes intermediate-temperature components isolated from these rocks at seven localities after stepwise thermal demagnetization are shown either to predate folding or be acquired during deformation; the conglomerate test at some localities is positive. The observed inclinations fit rather well with the Eurasian reference data, whereas the declinations are strongly deflected westward; westerly declinations have already been observed from the other parts of the Tien Shan (from the Turan plate in the west to the northern rim of Tarim and the Urumque area in the east). Our analysis shows that a considerable counterclockwise rotation of the Tien Shan fold belt as a rigid body is geologically improbable. We hypothesize that a sinistral shear zone existed over the fold belt thus accounting for systematically westerly declinations. This zone is about 300 km wide and is traced along the Tien Shan fold belt for 2500 km. A large area of Permian alkali magmatism in the West and Central Tien Shan is interpreted as an extensional domain conjugated with the shear zone. This shear zone can be accounted for by translation of the Kara Kum and Tarim blocks along the Eurasian boundary after their oblique collision in the Late Carboniferous. Two phases of rotation are recognized in the Tien Shan. The earlier rotation took place under shear strain during the D3 stage of deformation in the Artinskian-Ufimian. The later rotation is connected with transpression (D4 stage of deformation) and could occur from the Late Permian to Early Jurassic.

  5. Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

    NASA Astrophysics Data System (ADS)

    Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar

    2016-04-01

    The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters

  6. Deepwater Fold-and-Thrust Belt Along New Caledonia's Western Margin: Relation to Post-obduction Vertical Motions

    NASA Astrophysics Data System (ADS)

    Collot, J.; Patriat, M.; Etienne, S.; Rouillard, P.; Soetaert, F.; Juan, C.; Marcaillou, B.; Palazzin, G.; Clerc, C.; Maurizot, P.; Pattier, F.; Tournadour, E.; Sevin, B.; Privat, A.

    2017-10-01

    Classically, deepwater fold-and-thrust belts are classified in two main types, depending if they result from near- or far-field stresses and the understanding of their driving and triggering mechanism is poorly known. We present a geophysical data set off the western margin of New Caledonia (SW Pacific) that reveals deformed structures of a deepwater fold-and-thrust belt that we interpret as a near-field gravity-driven system, which is not located at a rifted passive margin. The main factor triggering deformation is inferred to be oversteepening of the margin slope by postobduction isostatic rebound. Onshore erosion of abnormally dense obducted material, combined with sediment loading in the adjacent basin, has induced vertical motions that have caused oversteepening of the margin. Detailed morphobathymetric, seismic stratigraphic, and structural analysis reveals that the fold-and-thrust belt extends 200 km along the margin, and 50 km into the New Caledonia Trough. Deformation is rooted at depths greater than 5 km beneath the seafloor, affects an area of 3,500 km2, and involves a sediment volume of approximately 13,000 km3. This deformed belt is organized into an imbricate fan system of faults, and one out-of-sequence thrust fault affects the seabed. The thrust faults are deeply rooted in the basin along a low-angle floor thrust and connected to New Caledonia Island along a major detachment. This study not only provides a better knowledge of the New Caledonia margin but also provides new insight into the mechanisms that trigger deepwater fold-and-thrust belts.

  7. Folding pattern in the Fars province, Zagros folded belt: case study on the Karbasi and Khaftar anticlines, interior Fars, Iran

    NASA Astrophysics Data System (ADS)

    Maleki, Z.; Arian, M.; Solgi, A.

    2015-08-01

    The anticlines in Fars region, which are located in Zagros fold-thrust belt, are valuable because they possess several hydrocarbons and this area is easily recognized by the NW-SE trending parallel anticlines that verge to the SW. According to the geological classification, the study area is located in Interior Fars region. Due to increasing complication of structural geometry in Fars region and necessity to explore activities for deeper horizons especially the Paleozoic ones, the analysis of fold style elements, which is known as one of the main parts in structural studies, seems necessary. The Karbasi and Khaftar anticlines are case study anticlines in the interior Fars sub-basin (Fassa area). These anticlines have an asymmetric structure and some faults with large strike separation are observed in these structures. Due to increasing complication of structural geometry in Fars region and necessity to explore activities for deeper horizons especially the Paleozoic ones, the analysis of fold style elements, which is known as one of the main parts in structural studies, seems necessary. Description of fold geometry is important because it allows comparisons within and between folds and also allows us to recognize patterns in the occurrence and distribution of fold systems. The main aim of this paper is to determine fold style elements and folding pattern in the study area. This paper presents a part of the results of a regional study of Fars province in the Zagros Simply folded belt, based on satellite images, geological maps, and well data. In the Interior Fars area, it seems that folding pattern is controlled by structural elements such as the Nezamabad basement fault and Dashtak formation. In fact, as a middle detachment unit, Dashtak formation plays an important role regarding folding geometry and fold in style in the study area.

  8. Variable deep structure of a midcontinent fault and fold zone from seismic reflection: La Salle deformation belt, Illinois basin

    USGS Publications Warehouse

    McBride, J.H.

    1997-01-01

    Deformation within the United States mid-continent is frequently expressed as quasilinear zones of faulting and folding, such as the La Salle deformation belt, a northwest-trending series of folds cutting through the center of the Illinois basin. Seismic reflection profiles over the southern La Salle deformation belt reveal the three-dimensional structural style of deformation in the lower Paleozoic section and uppermost Precambrian(?) basement. Individual profiles and structural contour maps show for the first time that the folds of the La Salle deformation belt are underlain at depth by reverse faults that disrupt and offset intrabasement structure, offset the top of interpreted Precambrian basement, and accommodate folding of overlying Paleozoic strata. The folds do not represent development of initial dips by strata deposited over a preexisting basement high. Rather, the structures resemble subdued "Laramide-style" forced folds, in that Paleozoic stratal reflectors appear to be flexed over a fault-bounded basement uplift with the basement-cover contact folded concordantly with overlying strata. For about 40 km along strike, the dominant faults reverse their dip direction, alternating between east and west. Less well expressed antithetic or back thrusts appear to be associated with the dominant faults and could together describe a positive flower structure. The overall trend of this part of the La Salle deformation belt is disrupted by along-strike discontinuities that separate distinct fold culminations. Observations of dual vergence and along-strike discontinuities suggest an original deformation regime possibly involving limited transpression associated with distant late Paleozoic Appalachian-Ouachita mountain building. Moderate-magnitude earthquakes located west of the western flank of the La Salle deformation belt have reverse and strike-slip mechanisms at upper trustai depths, which might be reactivating deep basement faults such as observed in this study

  9. Episodic growth of fold-thrust belts: Insights from Finite Element Modelling

    NASA Astrophysics Data System (ADS)

    Yang, Xiaodong; Peel, Frank J.; Sanderson, David J.; McNeill, Lisa C.

    2017-09-01

    The sequential development of a fold-thrust belt was investigated using 2D Finite Element Modelling (FEM). The new model results show that a thrust system is typically composed of three distinct regions: the thrust wedge, pre-wedge, and undeformed region. The thrust wedge involves growth that repeats episodically and cyclically. A cycle of wedge building starts as frontal accretion occurs, which is accompanied by a rapid increase in wedge width reducing the taper angle below critical. In response to this, the wedge interior (tracked here by the 50 m displacement position) rapidly propagates forwards into a region of incipient folding. The taper angle progressively increases until it obtains a constant apparent critical value (∼10°). During this period, the wedge experiences significant shortening after a new thrust initiates at the failure front, leading to a decrease in wedge width. Successive widening of the wedge and subsequent shortening and thrusting maintain a reasonably constant taper angle. The fold-thrust belt evolves cyclically, through a combination of rapid advancement of the wedge and subsequent gradual, slow wedge growth. The new model results also highlights that there is clear, although minor, deformation (0-10 m horizontal displacement) in front of the thrust wedge.

  10. Lateral ramps in the folded Appalachians and in overthrust belts worldwide; a fundamental element of thrust-belt architecture

    USGS Publications Warehouse

    Pohn, Howard A.

    2000-01-01

    Lateral ramps are zones where decollements change stratigraphic level along strike; they differ from frontal ramps, which are zones where decollements change stratigraphic level perpendicular to strike. In the Appalachian Mountains, the surface criteria for recognizing the subsurface presence of lateral ramps include (1) an abrupt change in wavelength or a termination of folds along strike, (2) a conspicuous change in the frequency of mapped faults or disturbed zones (extremely disrupted duplexes) at the surface, (3) long, straight river trends emerging onto the coastal plain or into the Appalachian Plateaus province, (4) major geomorphic discontinuities in the trend of the Blue Ridge province, (5) interruption of Mesozoic basins by cross-strike border faults, and (6) zones of modern and probable ancient seismic activity. Additional features related to lateral ramps include tectonic windows, cross-strike igneous intrusions, areas of giant landslides, and abrupt changes in Paleozoic sedimentation along strike. Proprietary strike-line seismic-reflection profiles cross three of the lateral ramps that were identified by using the surface criteria. The profiles confirm their presence and show their detailed nature in the subsurface. Like frontal ramps, lateral ramps are one of two possible consequences of fold-and-thrust-belt tectonics and are common elements in the Appalachian fold-and-thrust belt. A survey of other thrust belts in the United States and elsewhere strongly suggests that lateral ramps at depth can be identified by their surface effects. Lateral ramps probably are the result of thrust sheet motion caused by continued activation of ancient cratonic fracture systems. Such fractures localized the transform faults along which the continental segments adjusted during episodes of sea-floor spreading.

  11. The paradox of vertical σ2 in foreland fold and thrust belts

    NASA Astrophysics Data System (ADS)

    Tavani, Stefano

    2014-05-01

    Occurrence of aesthetically appealing thrust systems and associated large scale anticlines, in both active and fossil foreland fold and thrust belts, is commonly interpreted as an evidence for Andersonian compressional framework. Indeed, these structures would testify for a roughly vertical σ3. Such a correlation between thrusts occurrence and stress field orientation, however, frequently fails to explain denser observations at a smaller scale. The syn-orogenic deformation meso-structures hosted in exposed km-scale thrust-related folds, in fact, frequently and paradoxically witness for a syn-thrusting strike-slip stress configuration, with a near-vertical σ2 and a sub-horizontal σ3. This apparent widespread inconsistency between syn-orogenic meso-structures and stress field orientation is here named "the σ2 paradox". A possible explanation for such a paradox is provided by inherited extensional deformation structures commonly developed prior to thrusting, in the flexural foreland basins located ahead of fold and thrust belts. Thrust nucleation and propagation is facilitated and driven by the positive inversion of the extensional inheritances, and their subsequent linkage. This process eventually leads to the development of large reverse fault zones and can occur both in compressive and strike-slip stress configurations.

  12. Yakataga fold-and-thrust belt: Structural geometry and tectonic implications of a small continental collision zone

    NASA Astrophysics Data System (ADS)

    Wallace, Wesley K.

    Collision of the Yakutat terrane with southern Alaska created a collisional fold-and-thrust belt along the Pacific-North America plate boundary. This southerner fold-and-thrust belt formed within continental sedimentary rocks but with the seaward vergence and tectonic position typical of an accretionary wedge. Northward exposure of progressively older rocks reflects that the fold-and-thrust belt forms a southward-tapered orogenic wedge that increases northward in structural relief and depth of erosion. Narrow, sharp anticlines separate wider, flat-bottomed synclines. Relatively steep thrust faults commonly cut the forelimbs of anticlines. Fold shortening and fault displacement both generally increase northward, whereas fault dip generally decreases northward. The coal-bearing lower part of the sedimentary section serves as a detachment for both folds and thrust faults. The folded and faulted sedimentary section defines a regional south dip of about 8°. The structural relief combined with the low magnitude of shortening of the sedimentary section suggest that the underlying basement is structurally thickened. I propose a new interpretation in which this thickening was accommodated by a passive-roof duplex with basement horses that are separated from the overlying folded and thrust-faulted sedimentary cover by a roof thrust with a backthrust sense of motion. Basement horses are ˜7 km thick, based on the thickness between the inferred roof thrust and the top of the basement in offshore seismic reflection data. This thickness is consistent with the depth of the zone of seismicity onshore. The inferred zone of detachment and imbrication of basement corresponds with the area of surface exposure of the fold-and-thrust belt within the Yakutat terrane and with the Wrangell subduction zone and arc farther landward. By contrast, to the west, the crust of the Yakutat terrane has been carried down a subduction zone that extends far landward with a gentle dip, corresponding

  13. Kinematic evolution of a regional-scale gravity-driven deepwater fold-and-thrust belt: The Lamu Basin case-history (East Africa)

    NASA Astrophysics Data System (ADS)

    Cruciani, F.; Barchi, M. R.; Koyi, H. A.; Porreca, M.

    2017-08-01

    The deepwater fold-and-thrust belts (DWFTBs) are geological structures recently explored thanks to advances in offshore seismic imaging by oil industry. In this study we present a kinematic analysis based on three balanced cross-sections of depth-converted, 2-D seismic profiles along the offshore Lamu Basin (East African passive margin). This margin is characterized by a regional-scale DWFTB (> 450 km long), which is the product of gravity-driven contraction on the shelf that exhibits complex structural styles and differing amount of shortening along strike. Net shortening is up to 48 km in the northern wider part of the fold-and-thrust belt (≈ 180 km), diminishing to < 15 km toward the south, where the belt is markedly narrower (≈ 50 km). The three balanced profiles show a shortening percentage around 20% (comparable with the maximum values documented in other gravity-driven DWFTBs), with a significant variability along dip: higher values are achieved in the outer (i.e. down-dip) portion of the system, dominated by basinward-verging, imbricate thrust sheets. Fold wavelength increases landward, where doubly-verging structures and symmetric detachment folds accommodate a lower amount of shortening. Similar to other cases, a linear and systematic relationship between sedimentary thickness and fold wavelength is observed. Reconstruction of the rate of shortening through time within a fold-and-thrust belt shows that after an early phase of slow activation (Late Cretaceous), > 95% of net shortening was produced in < 10 Myr (during Paleocene). During this acme phase, which followed a period of high sedimentation rate, thrusts were largely synchronous and the shortening rate reached a maximum value of 5 mm/yr. The kinematic evolution reconstructed in this study suggests that the structural evolution of gravity-driven fold-and-thrust belts differs from the accretionary wedges and the collisional fold-and-thrust belts, where thrusts propagate in-sequence and shortening

  14. Assessment of undiscovered conventional oil and gas resources of the Arabian Peninsula and Zagros Fold Belt, 2012

    USGS Publications Warehouse

    Pitman, Janet K.; Schenk, Christopher J.; Brownfield, Michael E.; Charpentier, Ronald R.; Cook, Troy A.; Klett, Timothy R.; Pollastro, Richard M.

    2012-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 86 billion barrels of oil and 336 trillion cubic feet of undiscovered natural gas resources in the Arabian Peninsula and Zagros Fold Belt. The USGS assessed the potential for undiscovered conventional oil and gas accumulations within the Arabian Peninsula and Zagros Fold Belt as part of the USGS World Petroleum Resources Project. Twenty-three assessment units within seven petroleum systems were quantitatively assessed in this study, which represents a reassessment of this area last published in 2000.

  15. Late Permian rivers draining the uplifted Cape Fold Belt: magnetostratigraphy and detrital thermochronology of Karoo Basin sediments

    NASA Astrophysics Data System (ADS)

    Tohver, E.; Schmieder, M.; Arosio, R.; Lanci, L.; Jourdan, F.; Wilson, A.; Ratcliffe, K.; Payenberg, T.; Flint, S.

    2017-12-01

    The Cape Fold Belt and Karoo Basin of southern Africa formed during the Permian orogeny that affected the 13,000 km southern margin of the Gondwanan continent. In this report, we synthesize new and recent magnetostratigraphic and geochronologic data to establish a chronostratigraphic framework for Karoo Basin sedimentation for comparison with the thermal/exhumation history of the Cape Fold Belt. The source-sink model is evaluated using new data from detrital muscovite and zircon from 2 km composite section of fluvial sandstone and mudstones deposited at ca.275 - 260 Ma. Coherent age populations of detrital zircon grains indicate rapid incorporation of contemporary volcanic ashbeds into the sedimentary record. In contrast, cooling age distributions of detrital muscovite are typically ca. 5 - 10 Ma older than the age of deposition; similar lag times are observed from modern sediments in active mountain belts. Trace element geochemical signatures demonstrate a clear shift towards crustal recycling via headland erosion in the Beaufort Group relative to the underlying Ecca Group. These observations pinpoint the age of uplift for the Cape Fold Belt, which began to function as the major sediment source for the foreland Karoo Basin with the deposition of the uppermost Ecca Group and basal Beaufort Group.

  16. Modelling the Deformation Front of a Fold-Thrust Belt: the Effect of an Upper Detachment Horizon

    NASA Astrophysics Data System (ADS)

    Burberry, C. M.; Koyi, H.; Nilfouroushan, F.; Cosgrove, J. W.

    2008-12-01

    Structures found at the deformation fronts of fold-thrust belts are variable in type, geometry and spatial organisation, as can be demonstrated from comparisons between structures in the Zagros Fold-Thrust Belt, Iran and the Sawtooth Range, Montana. A range of influencing factors has been suggested to account for this variation, including the mechanical properties and distribution of any detachment horizons within the cover rock succession. A series of analogue models was designed to test this hypothesis, under conditions scaled to represent the Sawtooth Range, Montana. A brittle sand pack, containing an upper ductile layer with variable geometry, was shortened above a ductile base and the evolution of the deformation front was monitored throughout the deformation using a high-accuracy laser scanner. In none of the experiments did the upper detachment horizon cover the entire model. In experiments where it pinched out perpendicular to the shortening direction, a triangle zone was formed when the deformation front reached the pinch out. This situation is analogous to the Teton Canyon region structures in the Sawtooth Range, Montana, where the Cretaceous Colorado Shale unit pinches out at the deformation front, favouring the development of a triangle zone in this region. When the pinch out was oblique to the shortening direction, a more complex series of structures was formed. However, when shortening stopped before the detachment pinch out was reached, the deformation front structures were foreland-propagating and no triangle zone was observed. This situation is analogous to foreland-propagating thrust structures developed at the deformation front in the Swift Dam region of the Sawtooth Range, Montana and to the development of fault-bend folds at the deformation front of the Zagros Fold-Thrust Belt, Iran. We suggest that the presence of a suitable intermediate detachment horizon within a sediment pile can be invoked as a valid explanation for the development of

  17. Influence of pre-existing basement faults on the structural evolution of the Zagros Simply Folded belt: 3D numerical modelling

    NASA Astrophysics Data System (ADS)

    Ruh, Jonas B.; Gerya, Taras

    2015-04-01

    The Simply Folded Belt of the Zagros orogen is characterized by elongated fold trains symptomatically defining the geomorphology along this mountain range. The Zagros orogen results from the collision of the Arabian and the Eurasian plates. The Simply Folded Belt is located southwest of the Zagros suture zone. An up to 2 km thick salt horizon below the sedimentary sequence enables mechanical and structural detachment from the underlying Arabian basement. Nevertheless, deformation within the basement influences the structural evolution of the Simply Folded Belt. It has been shown that thrusts in form of reactivated normal faults can trigger out-of-sequence deformation within the sedimentary stratigraphy. Furthermore, deeply rooted strike-slip faults, such as the Kazerun faults between the Fars zone in the southeast and the Dezful embayment and the Izeh zone, are largely dispersing into the overlying stratigraphy, strongly influencing the tectonic evolution and mechanical behaviour. The aim of this study is to reveal the influence of basement thrusts and strike-slip faults on the structural evolution of the Simply Folded Belt depending on the occurrence of intercrustal weak horizons (Hormuz salt) and the rheology and thermal structure of the basement. Therefore, we present high-resolution 3D thermo-mechnical models with pre-existing, inversively reactivated normal faults or strike-slip faults within the basement. Numerical models are based on finite difference, marker-in-cell technique with (power-law) visco-plastic rheology accounting for brittle deformation. Preliminary results show that deep tectonic structures present in the basement may have crucial effects on the morphology and evolution of a fold-and-thrust belt above a major detachment horizon.

  18. Structural model of the eastern Achara-Trialeti fold and thrust belt using seismic reflection profiles

    NASA Astrophysics Data System (ADS)

    Alania, Victor; Chabukiani, Alexander; Enukidze, Onise; Razmadze, Alexander; Sosson, Marc; Tsereteli, Nino; Varazanashvili, Otar

    2017-04-01

    Our study focused on the structural geometry at the eastern Achara-Trialeti fold and thrust belt (ATFTB) located at the retro-wedge of the Lesser Caucasus orogen (Alania et al., 2016a). Our interpretation has integrated seismic reflection profiles, several oil-wells, and the surface geology data to reveal structural characteristics of the eastern ATFTB. Fault-related folding theories were used to seismic interpretation (Shaw et al., 2004). Seismic reflection data reveal the presence of basement structural wedge, south-vergent backthrust, north-vergent forethrust and some structural wedges (or duplex). The rocks are involved in the deformation range from Paleozoic basement rocks to Tertiary strata. Building of thick-skinned structures of eastern Achara-Trialeti was formed by basement wedges propagated from south to north along detachment horizons within the cover generating thin-skinned structures. The kinematic evolution of the south-vergent backthrust zone with respect to the northward propagating structural wedge (or duplexes). The main style of deformation within the backthrust belt is a series of fault-propagation folds. Frontal part of eastern ATFTB are represent by triangle zone (Alania et al., 2016b; Sosson et al., 2016). A detailed study was done for Tbilisi area: seismic refection profiles, serial balanced cross-sections, and earthquakes reveal the presence of an active blind thrust fault beneath Tbilisi. 2 & 3-D structural models show that 2002 Mw 4.5 Tbilisi earthquake related to a north-vergent blind thrust. Empirical relations between blind fault rupture area and magnitude suggest that these fault segments could generate earthquakes of Mw 6.5. The growth fault-propagation fold has been observed near Tbilisi in the frontal part of eastern ATFTB. Seismic reflection profile through Ormoiani syncline shows that south-vergent growth fault-propagation fold related to out-of-the-syncline thrust. The outcrop of fault-propagation fold shown the geometry of the

  19. Tectonomorphic evolution of the Eastern Cordillera fold-thrust belt, Colombia: New insights based on apatite and zircon (U-Th)/He thermochronometers

    NASA Astrophysics Data System (ADS)

    Ghorbal, B.; Stockli, D. F.; Mora, A.; Horton, B. K.; Blanco, V.; Sanchez, N.

    2010-12-01

    The Eastern Cordillera (EC) of Colombia marks the eastern boundary of Cenozoic fold-thrust deformation in the northern Andes. It is a classic example of an inversion belt formed in the retro-arc region, in this case superimposed on a Triassic/Jurassic to Cretaceous intracontinental rift system of northern South America. Ongoing thrust reactivation (inversion) in this contractional orogen provides an excellent opportunity to study the patterns of deformation and influence of preexisting anisotropies (Mora et al., 2006). The objective of this detailed (U-Th)/He study is to unravel the tectonic and thermal evolution of the EC from the Magdalena Valley basin in the west to the Llanos foreland basin in the east and reconstruct the temporal and spatial progression of deformation in the EC fold-thrust belt. Furthermore, the Subandean or foothills zone of Colombia is key for understanding the petroleum systems in the complex frontal zone of the inverted fold-thrust belt. We present detailed apatite and zircon (U-Th)/He thermochronometric data from surface samples along a ~220 km WNW-ESE transect across the EC from the frontal fold-thrust belt at the edge of the Llanos basin to the western edge of the EC, the Magdalena basin. Surface and borehole zircon and apatite (U-Th)/He data, integrated with structural data, show that the EC fold-thrust belt propagated foreland-ward from the axial zone to the modern edges of the fold-thrust belt from at least the early Oligocene to the early Miocene. Detailed apatite and zircon (U-Th)/He data from surface samples and borehole samples in the foothills-Llanos transition zone and the Middle Magdalena Valley basin, between the large-displacement Guaicaramo and Pajarito-Chámeza thrusts in the east and the La Salina fault system in the west show a temporally complex evolution. The frontal fold-thrust belt was characterized by continued progressive foreland-ward migration of deformation and an apparent phase of major out-of-sequence motion

  20. Dynamics of thin-skinned fold and thrust belts with a tilted detachment

    NASA Astrophysics Data System (ADS)

    Fernandez, Naiara; Kaus, Boris J. P.; Epard, Jean-Luc

    2014-05-01

    The formation of the Jura fold and thrust belt is linked to the Alpine orogeny. However, it is still a matter of debate why the Jura was formed tens of kilometres far away from the active deformation front while the Molasse basin that lies in between remained mostly undeformed. Progressive thickening of the Molasse basin due to its infill with sediments, and the existence of a tilted potential detachment level at the Triassic evaporitic units, have been pushed forward as the main causes for the detachment of the Molasse basin and the consequent jump of the deformation front from the Alpine front to the position of the Jura at around 22 Ma or later (e.g Willett and Schlunegger, 2010). In order to better understand the dynamics of a thin-skinned fold and thrust belt with a tilted detachment we have performed systematic forward numerical simulations with the 2D thermo-mechanical finite element code MILAMIN_VEP. The modelled setup consists of a tilted detachment, overlain by a sedimentary cover of constant thickness and a wedge shaped basin infill that makes the initial surface slope of the system to be zero. In this study we have tested the importance of the following factors in the dynamics of such a fold and thrust belt evolution: 1) the applied boundary conditions 2) the angle of a uniformly tilted detachment 3) the end displacement of a curved detachment with a flexural foreland basin profile. The implications of the studied factors are discussed for the case of the Jura-Molasse system. Acknowledgements Funding was provided by the European Research Council under the European Community's Seventh Framework program (FP7/2007-2013) ERC Grant agreement #258830. References Willett, S.D. and Schlunegger, F. 2010, The last phase of deposition in the Swiss Molasse Basin: from foredeep to negative-alpha basin. Basin Research 22, 623-639, doi: 10.1111/j.1365-2117.2009.00435.x

  1. A viscoelastic strain energy principle expressed in fold thrust belts and other compressional regimes

    NASA Astrophysics Data System (ADS)

    Patton, Regan L.; Watkinson, A. John

    2005-07-01

    A mathematical folding theory for stratified viscoelastic media in layer parallel compression is presented. The second order fluid, in slow flow, is used to model rock rheological behavior because it is the simplest nonlinear constitutive equation exhibiting viscoelastic effects. Scaling and non-dimensionalization of the model system reveals the presence of Weissenberg number ( Wi), defined as a ratio of time scales τ*/( H*/ V*). V*/ H* is the strain rate (s -1) imposed by an assumed far field velocity V* acting on a layer of thickness H*, while τ* (s) is related to the relaxation of normal stresses. Our most significant finding is a transitional behavior as Wi→½, which is independent of the viscosity contrast. A change of variables shows that lengths associated with this transition are scaled by a parameter α=[(1-2 Wi)/(1+2 Wi)] 1/2, which is inversely proportional to local strain energy. On this basis a scaling law representing a distribution of non-dimensional wavelengths (wavelength/layer thickness) is derived. Geologically this is consistent with a transition from folding to faulting, as observed in fold-thrust belts. Folding, a distributed deformation scaling as Wi-1, is found to be energetically favored at non-dimensional wavelengths ranging from about three to seven. Furthermore, the transition from folding to faulting, a localized deformation scaling as ( αWi) -1, is predicted at a non-dimensional wavelength of about seven. These findings are consistent with measurements of thrust sheets in the Sawtooth Mountains of western Montana, USA and other fold-thrust belts. A review of the literature reveals a similar distribution of non-dimensional wavelengths spanning a wide range of observational scales in compressional deformation. Specific examples include lithospheric scale folding in the central Indian Basin and microscopic scale failure of ice columns between splay microcracks in laboratory studies.

  2. Role of the Kazerun fault system in active deformation of the Zagros fold-and-thrust belt (Iran)

    NASA Astrophysics Data System (ADS)

    Authemayou, Christine; Bellier, Olivier; Chardon, Dominique; Malekzade, Zaman; Abassi, Mohammad

    2005-04-01

    Field structural and SPOT image analyses document the kinematic framework enhancing transfer of strike-slip partitioned motion from along the backstop to the interior of the Zagros fold-and-thrust belt in a context of plate convergence slight obliquity. Transfer occurs by slip on the north-trending right-lateral Kazerun Fault System (KFS) that connects to the Main Recent Fault, a major northwest-trending dextral fault partitioning oblique convergence at the rear of the belt. The KFS formed by three fault zones ended by bent orogen-parallel thrusts allows slip from along the Main Recent Fault to become distributed by transfer to longitudinal thrusts and folds. To cite this article: C. Authemayou et al., C. R. Geoscience 337 (2005).

  3. Complex fold and thrust belt structural styles: Examples from the Greater Juha area of the Papuan Fold and Thrust Belt, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Mahoney, Luke; Hill, Kevin; McLaren, Sandra; Hanani, Amanda

    2017-07-01

    The remote and inhospitable Papuan Fold Belt in Papua New Guinea is one of the youngest yet least well-documented fold and thrust belts on Earth. Within the frontal Greater Juha area we have carried out >100 km of geological traverses and associated analyses that have added significantly to the contemporary geological and geophysical dataset. Our structural analysis provides evidence of major inversion, detachment and triangle zone faults within the uplifted Eastern Muller Ranges. We have used the dataset to develop a quasi-3D model for the Greater Juha area, with associated cross-sections revealing that the exposed Cenozoic Darai Limestone is well-constrained with very low shortening of 12.6-21.4% yet structures are elevated up to 7 km above regional. We suggest the inversion of pre-existing rift architecture is the primary influence on the evolution of the area and that structures link to the surface via triangle zones and detachment faults within the incompetent Mesozoic passive-margin sedimentary sequence underlying competent Darai Limestone. Arc-normal oriented structures, dominantly oblique dextral, up-to-the-southeast, are pervasive across a range of scales and are here interpreted to relate at depth to weakened pre-existing basement cross-structures. It is proposed that Palaeozoic basement fabric controlled the structural framework of the basin during Early Mesozoic rifting forming regional-scale accommodation zones and related local-scale transfer structures that are now expressed as regional-scale arc-normal lineaments and local-scale arc-normal structures, respectively. Transfer structures, including complexly breached relay ramps, utilise northeast-southwest striking weaknesses associated with the basement fabric, as a mechanism for accommodating displacement along major northwest-southeast striking normal faults. These structures have subsequently been inverted to form arc-normal oriented zones of tear faulting that accommodate laterally variable

  4. Do mesoscale faults in a young fold belt indicate regional or local stress?

    NASA Astrophysics Data System (ADS)

    Kokado, Akihiro; Yamaji, Atsushi; Sato, Katsushi

    2017-04-01

    The result of paleostress analyses of mesoscale faults is usually thought of as evidence of a regional stress. On the other hand, the recent advancement of the trishear modeling has enabled us to predict the deformation field around fault-propagation folds without the difficulty of assuming paleo mechanical properties of rocks and sediments. We combined the analysis of observed mesoscale faults and the trishear modeling to understand the significance of regional and local stresses for the formation of mesoscale faults. To this end, we conducted the 2D trishear inverse modeling with a curved thrust fault to predict the subsurface structure and strain field of an anticline, which has a more or less horizontal axis and shows a map-scale plane strain perpendicular to the axis, in the active fold belt of Niigata region, central Japan. The anticline is thought to have been formed by fault-propagation folding under WNW-ESE regional compression. Based on the attitudes of strata and the positions of key tephra beds in Lower Pleistocene soft sediments cropping out at the surface, we obtained (1) a fault-propagation fold with the fault tip at a depth of ca. 4 km as the optimal subsurface structure, and (2) the temporal variation of deformation field during the folding. We assumed that mesoscale faults were activated along the direction of maximum shear strain on the faults to test whether the fault-slip data collected at the surface were consistent with the deformation in some stage(s) of folding. The Wallace-Bott hypothesis was used to estimate the consistence of faults with the regional stress. As a result, the folding and the regional stress explained 27 and 33 of 45 observed faults, respectively, with the 11 faults being consistent with the both. Both the folding and regional one were inconsistent with the remaining 17 faults, which could be explained by transfer faulting and/or the gravitational spreading of the growing anticline. The lesson we learnt from this work was

  5. Aseismic deformation of a fold-and-thrust belt imaged by SAR interferometry near Shahdad, southeast Iran

    NASA Technical Reports Server (NTRS)

    Fielding, Eric J.; Wright, Tim J.; Muller, Jordan; Parsons, Barry E.; Walker, Richard

    2004-01-01

    At depth, many fold-and-thrust belts are composed of a gently dipping, basal thrust fault and steeply dipping, shallower splay faults that terminate beneath folds at the surface. Movement on these buried faults is difficult to observe, but synthetic aperture radar (SAR) interferometry has imaged slip on at least 600 square kilometers of the Shahdad basal-thrust and splay-fault network in southeast Iran.

  6. Mid-Late Miocene deformation of the northern Kuqa fold-and-thrust belt (southern Chinese Tian Shan): An apatite (U-Th-Sm)/He study

    NASA Astrophysics Data System (ADS)

    Chang, Jian; Tian, Yuntao; Qiu, Nansheng

    2017-01-01

    The Kuqa fold-and-thrust belt developed in response to Cenozoic southward shortening between the Chinese Tian Shan and the Tarim Basin. This study aims to constrain the timing of the Late Cenozoic deformation by determining the onset time of enhanced rock cooling using apatite (U-Th-Sm)/He thermochronometry. Eight sedimentary samples were collected from Triassic to Cretaceous strata exposed along a 17 km N-S transect, cross-cutting the northern Kuqa fold-and-thrust belt. Single-grain AHe ages from these samples mostly cluster around 8-16 Ma and are younger than their depositional ages. Older AHe ages show a positive relationship with [eU], a proxy for radiation damage. Modelling of the observed age-eU relationships suggest a phase of enhanced cooling and erosion initiated at Mid-Late Miocene time (10-20 Ma) in the northern Kuqa fold-and-thrust belt. This result is consistent with a coeval abrupt increase of sedimentation rate in the foreland Kuqa depression, south of the study area, indicating a Mid-Late Miocene phase of shortening in the northern Kuqa fold-and-thrust belt.

  7. Formation of fold and thrust belts on Venus due to horizontal shortening of a laterally heterogeneous lithosphere

    NASA Technical Reports Server (NTRS)

    Zuber, M. T.; Parmentier, E. M.; Neumann, G. A.

    1994-01-01

    An outstanding question relevant to understanding the tectonics of Venus is the mechanism of formation of fold and thrust belts, such as the mountain belts that surround Lakshmi Planum in western Ishtar Terra. These structures are typically long (hundreds of km) and narrow (many tens of km), and are often located at the margins of relatively high (km-scale) topographic rises. Previous studies have attempted to explain fold and thrust belts in various areas of Venus in the context of viscous and brittle wedge theory. However, while wedge theory can explain the change in elevation from the rise to the adjacent lowland, it fails to account for a fundamental aspect of the deformation, i.e., the topographic high at the edge of the rise. In this study we quantitatively explore the hypothesis that fold and thrust belt morphology on Venus can alternatively be explained by horizontal shortening of a lithosphere that is laterally heterogeneous, due either to a change in thickness of the lithosphere or the crust. Lateral heterogeneities in lithosphere structure may arise in response to thermal thinning or extensive faulting, while variations in crustal thickness may arise due to either spatially variable melting of mantle material or by horizontal shortening of the crust. In a variable thickness lithosphere or crust that is horizontally shortened, deformation will tend to localize in the vicinity of thickness heterogeneity, resulting in a higher component of dynamic topography there as compared to elsewhere in the shortening lithosphere. This mechanism may thus provide a simple explanation for the topographic high at the edge of the rise.

  8. Formation of fold and thrust belts on Venus due to horizontal shortening of a laterally heterogeneous lithosphere

    NASA Astrophysics Data System (ADS)

    Zuber, M. T.; Parmentier, E. M.; Neumann, G. A.

    1994-03-01

    An outstanding question relevant to understanding the tectonics of Venus is the mechanism of formation of fold and thrust belts, such as the mountain belts that surround Lakshmi Planum in western Ishtar Terra. These structures are typically long (hundreds of km) and narrow (many tens of km), and are often located at the margins of relatively high (km-scale) topographic rises. Previous studies have attempted to explain fold and thrust belts in various areas of Venus in the context of viscous and brittle wedge theory. However, while wedge theory can explain the change in elevation from the rise to the adjacent lowland, it fails to account for a fundamental aspect of the deformation, i.e., the topographic high at the edge of the rise. In this study we quantitatively explore the hypothesis that fold and thrust belt morphology on Venus can alternatively be explained by horizontal shortening of a lithosphere that is laterally heterogeneous, due either to a change in thickness of the lithosphere or the crust. Lateral heterogeneities in lithosphere structure may arise in response to thermal thinning or extensive faulting, while variations in crustal thickness may arise due to either spatially variable melting of mantle material or by horizontal shortening of the crust. In a variable thickness lithosphere or crust that is horizontally shortened, deformation will tend to localize in the vicinity of thickness heterogeneity, resulting in a higher component of dynamic topography there as compared to elsewhere in the shortening lithosphere. This mechanism may thus provide a simple explanation for the topographic high at the edge of the rise.

  9. Structural evolution of the J-fold; a multi-scalar approach to modeling kinematic fold evolution in the Cordilleran fold-thrust belt, southwestern Montana

    NASA Astrophysics Data System (ADS)

    Wallace, James W.

    The Highway 2 structural complex (HW2SC) is part of the North American western Cordilleran fold-and-thrust belt that extends from northern Wyoming into northwestern Canada. More precisely, the HW2SC is located on the southeastern margin of the Helena salient in what is known as the southwest Montana transverse zone. Based on the location of the HW2SC it appears to have formed as footwall deformation associated with displacement along the southwestern Montana transverse zone. The most prominent structural feature in the HW2SC is the Late-Cretaceous "J-fold", a east-west trending, muliti-hinged, northeast plunging anticline with an associated northeast plunging syncline. The purpose of this study is to provide insight into whether the geometries of thrust-related folds correlate to particular mechanical responses taking place within the folded sedimentary sequences. This is accomplished by conducting a multifaceted examination of the J-fold using high-resolution terrestrial laser scanning combined with detailed field measurements of kinematic indicators, and petrographic analysis of microstructures in thin section. Based on the findings of this study four specific conclusions about the kinematic and mechanical evolution of the J-fold can be made: 1) the J-fold kinematically behaves as a fault-bend fold throughout its structural evolution; 2) the J-fold enjoyed two stages of fault-bend folding deformation that produced its present day geometry; 3) the J-fold has been tectonically thinned by >50% in the Permian Phosphoria and Jurassic Ellis-Rierdon formations located in the Overturned forelimb; and finally 4) the J-fold is mechanically accommodating the thinning in the Overturned forelimb by pressure solution and dissolution of chert grains in the Permian Phosphoria formation and by faulting and shearing in the Jurassic Ellis-Rierdon formation.

  10. Oak Ridge fault, Ventura fold belt, and the Sisar decollement, Ventura basin, California

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yeats, R.S.; Huftile, G.J.; Grigsby, F.B.

    1988-12-01

    The rootless Ventura Avenue, San Miguelito, and Rincon anticlines (Ventura fold belt) in Pliocene -Pleistocene turbidites are fault-propagation folds related to south-dipping reverse faults rising from a decollement in Miocene shale. To the east, the Sulfur Mountain anticlinorium overlies and is cut by the Sisar, Big Canyon, and Lion south-dipping thrusts that merge downward into the Sisar decollement in lower Miocene shale. Shortening of the Miocene and younger sequence is {approximately} 3 km greater than that of underlying competent Paleogens strata in the Ventura fold belt and {approximately} 7 km greater farther east at Sulfur Mountain. Cross-section balancing requires thatmore » this difference be taken up by the Paleogene sequence at the Oak Ridge fault to the south. Convergence is northeast to north-northeast on the base of earthquake focal mechanisms, borehole breakouts, and piercing-point offest of the South Mountain seaknoll by the Oak Ridge fault. A northeast-trending line connecting the west end of Oak Ridge and the east end of Sisar fault separates an eastern domain where late Quaternary displacement is taken up entirely on the Oak Ridge fault and a western domain where displacement is transferred to the Sisar decollement and its overlying rootless folds. This implies that (1) the Oak Ridge fault near the coast presents as much seismic risk as it does farther east, despite negligible near-surface late Quaternary movement; (2) ground-rupture hazard is high for the Sisar fault set in the upper Ojai Valley; and (3) the decollement itself could produce an earthquake analogous to the 1987 Whittier Narrows event in Low Angeles.« less

  11. Mechanical restoration of large-scale folded multilayers using the finite element method: Application to the Zagros Simply Folded Belt, N-Iraq

    NASA Astrophysics Data System (ADS)

    Frehner, Marcel; Reif, Daniel; Grasemann, Bernhard

    2010-05-01

    There are a large number of numerical finite element studies concerned with modeling the evolution of folded geological layers through time. This body of research includes many aspects of folding and many different approaches, such as two- and three-dimensional studies, single-layer folding, detachment folding, development of chevron folds, Newtonian, power-law viscous and more complex rheologies, influence of anisotropy, pure-shear, simple-shear and other boundary conditions and so forth. In recent years, studies of multilayer folding emerged, thanks to more advanced mesh generator software and increased computational power. Common to all of these studies is the fact that they consider a forward directed time evolution, as in nature. Very few studies use the finite element method for reverse-time simulations. In such studies, folded geological layers are taken as initial conditions for the numerical simulation. The folding process is reversed by changing the signs of the boundary conditions that supposedly drove the folding process. In such studies, the geometry of the geological layers before the folding process is searched and the amount of shortening necessary for the final folded geometry can be calculated. In contrast to a kinematic or geometric fold restoration procedure, the described approach takes the mechanical behavior of the geological layers into account, such as rheology and the relative strength of the individual layers. This approach is therefore called mechanical restoration of folds. In this study, the concept of mechanical restoration is applied to a two-dimensional 50km long NE-SW-cross-section through the Zagros Simply Folded Belt in Iraqi Kurdistan, NE from the city of Erbil. The Simply Folded Belt is dominated by gentle to open folding and faults are either absent or record only minor offset. Therefore, this region is ideal for testing the concept of mechanical restoration. The profile used is constructed from structural field measurements

  12. Stress states in the Zagros fold-and-thrust belt from passive margin to collisional tectonic setting

    NASA Astrophysics Data System (ADS)

    Navabpour, Payman; Barrier, Eric

    2012-12-01

    The present-day Zagros fold-and-thrust belt of SW-Iran corresponds to the former Arabian passive continental margin of the southern Neo-Tethyan basin since the Permian-Triassic rifting, undergoing later collisional deformation in mid-late Cenozoic times. In this paper an overview of brittle tectonics and palaeostress reconstructions of the Zagros fold-and-thrust belt is presented, based on direct stress tensor inversion of fault slip data. The results indicate that, during the Neo-Tethyan oceanic opening, an extensional tectonic regime affectedthe sedimentary cover in Triassic-Jurassic times with an approximately N-S trend of the σ3 axis, oblique to the margin, which was followed by some local changes to a NE-SW trend during Jurassic-Cretaceous times. The stress state significantly changed to thrust setting, with a NE-SW trend of the σ1 axis, and a compressional tectonic regime prevailed during the continental collision and folding of the sedimentary cover in Oligocene-Miocene times. This compression was then followed by a strike-slip stress state with an approximately N-S trend of the σ1 axis, oblique to the belt, during inversion of the inherited extensional basement structures in Pliocene-Recent times. The brittle tectonic reconstructions, therefore, highlighted major changes of the stress state in conjunction with transitions between thin- and thick-skinned structures during different extensional and compressional stages of continental deformation within the oblique divergent and convergent settings, respectively.

  13. Profile and microbiological isolates of asymptomatic bacteriuria among pregnant women in Abakaliki, Nigeria

    PubMed Central

    Onu, Fidelis Agwu; Ajah, Leonard Ogbonna; Ezeonu, Paul Olisaemeka; Umeora, Odidika Ugochukwu Joannes; Ibekwe, Perpetus Chudi; Ajah, Monique Iheoma

    2015-01-01

    Background Detecting and treating asymptomatic bacteriuria (ASB) prevents urinary tract infection and its consequences. The cost-effectiveness of routine screening for ASB in pregnancy is controversial. In populations with high prevalence, however, it is worthwhile and justifiable. Aim To determine the profile, prevalence, microbiological isolates, and risk factors of ASB among booking antenatal clinic attendees in Abakaliki, Nigeria. Materials and methods This was a cross-sectional study involving booking antenatal clinic attendees at the Federal Teaching Hospital, Abakaliki, who met the inclusion criteria. This study occurred between January and December, 2012. The midstream urine samples of these women were subjected to microscopy, culture, and sensitivity. Results A total of 300 randomly selected booking antenatal clinic attendees participated in the study; 74 of them had ASB, giving a prevalence of 24.7%. With the exception of rural residence, sociodemographic and obstetric characteristics did not influence the risk of ASB among the participants in this study. Staphylococcus aureus was the commonest organism isolated. The majority of the organisms were sensitive to ofloxacin and ceftriaxone. Conclusion There is a high prevalence of ASB among pregnant women in Abakaliki. With the exception of rural dwelling, sociodemographic and obstetric characteristics did not significantly influence the risk of ASB among these pregnant women. Therefore, routine ASB screening of pregnant women is recommended in our environment. PMID:26244027

  14. Mechanics of fold-and-thrust belts and accretionary wedges Cohesive Coulomb theory

    NASA Technical Reports Server (NTRS)

    Dahlen, F. A.; Suppe, J.; Davis, D.

    1984-01-01

    A self-consistent theory for the mechanics of thin-skinned accretionary Coulomb wedges is developed and applied to the active fold-and-thrust belt of western Taiwan. The state of stress everywhere within a critical wedge is determined by solving the static equilibrium equations subject to the appropriate boundary conditions. The influence of wedge cohesion, which gives rise to a concave curvature of the critical topographic surface and affects the orientation of the principal stresses and Coulomb fracture within the wedge, is considered. The shape of the topographic surface and the angles at which thrust faults step up from the basal decollement in the Taiwanese belt is analyzed taking into account the extensive structural and fluid-pressure data available there. It is concluded that the gross geometry and structure of the Taiwan wedge are consistent with normal laboratory frictional and fracture strengths of sedimentary rocks.

  15. Deepwater fold and thrust belt classification, tectonics, structure and hydrocarbon prospectivity: A review

    NASA Astrophysics Data System (ADS)

    Morley, C. K.; King, R.; Hillis, R.; Tingay, M.; Backe, G.

    2011-01-01

    Deepwater fold and thrust belts (DWFTBs) are classified into near-field stress-driven Type 1 systems confined to the sedimentary section, and Type 2 systems deformed by either far-field stresses alone, or mixed near- and far-field stresses. DWFTBs can occur at all stages of the Wilson cycle up to early stage continent continent collision. Type 1 systems have either weak shale or salt detachments, they occur predominantly on passive margins but can also be found in convergent-related areas such as the Mediterranean and N. Borneo. Examples include the Niger and Nile deltas, the west coast of Africa, and the Gulf of Mexico. Type 2 systems are subdivided on a tectonic setting basis into continent convergence zones and active margin DWFTBs. Continent convergence zones cover DWFTBs developed during continent-arc or continent-continent collision, and those in a deepwater intracontinental setting (e.g. W. Sulawesi, Makassar Straits). Active margins include accretionary prisms and transform margins. The greatest variability in DWFTB structural style occurs between salt and shale detachments, and not between tectonic settings. Changes in fold amplitude and wavelength appear to be more related to thickness of the sedimentary section than to DWFTB type. In comparison with shale, salt detachment DWFTBS display a lower critical wedge taper, more detachment folds, long and episodic duration of deformation and more variation in vergence. Structures unique to salt include canopies and nappes. Accretionary prisms also standout from other DWFTBs due to their relatively long, continuous duration, rapid offshore propagation of the thrust front, and large amount of shortening. In terms of petroleum systems, many similar issues affect all DWFTBs, these include: the oceanward decrease in heat flow, offshore increase in age of mature source rock, and causes of trap failure (e.g. leaky oblique and frontal thrust faults, breach of top seal by fluid pipes). One major difference between Type 1

  16. Fold interference pattern in thick-skinned tectonics; a case study from the external Variscan belt of Eastern Anti-Atlas, Morocco

    NASA Astrophysics Data System (ADS)

    Baidder, L.; Michard, A.; Soulaimani, A.; Fekkak, A.; Eddebbi, A.; Rjimati, E.-C.; Raddi, Y.

    2016-07-01

    Conflicting views are expressed in literature concerning fold interference patterns in thick-skinned tectonic context (e.g. Central Anti-Atlas and Rocky Mountains-Colorado areas). Such patterns are referred to superimposed events with distinct orientation of compression or to the inversion of paleofaults with distinct strike during a single compressional event. The present work presents a case study where both types of control on fold interference are likely to be combined. The studied folds occur in the Tafilalt-Maider area of eastern Anti-Atlas, i.e. in the E-trending foreland fold belt of the Meseta Variscan Orogen in the area where it connects with the SE-trending, intracontinental Ougarta Variscan belt. Detail mapping documents unusual fold geometries such as sigmoidal and croissant- or boomerang-shaped folds associated with a complex major fault pattern. The folded rock material corresponds to a 6-8 km-thick Cambrian-Serpukhovian sedimentary pile that includes alternating competent and incompetent formations. The basement of the Paleozoic succession is made up of rhomboedric tilted blocks that formed during the Cambrian rifting of north-western Gondwana and the Devonian dislocation of the Sahara platform. The latter event is responsible for an array of paleofaults bounding the Maider and South Tafilalt Devonian-Early Carboniferous basins with respect to the adjoining high axes. The Variscan Orogeny began during the Bashkirian-Westphalian with a N-S direction of shortening that converted the NW-trending Ougnat-Ouzina paleogeographic high into a mega dextral shear zone. Folds developed on top of a moving mosaic of basement blocks, being oriented en echelon on the inverted paleofaults or above intensely sheared fault zones. However, a dominantly NE-SW compression responsible for the building of the Ougarta belt also affected the studied area, presumably during the latest Carboniferous-Early Permian. The resulting fold interference pattern and peculiar geometries

  17. Episodic Growth of Fold-Thrust Belts: Insights from Finite Element Modelling

    NASA Astrophysics Data System (ADS)

    Yang, X.; Peel, F.; Sanderson, D. J.; McNeill, L. C.

    2016-12-01

    The sequential development of an imbricate thrust system was investigated using a set of 2D FEM models. This study provides new insights on how the style and location of thrust activity changes through cycles of thrust accretion by making refined measurements of the thrust system parameters through time and tracking these parameters through each cycle. In addition to conventional wedge parameters (i.e. surface slope, wedge width and height), the overall taper angle is used to determine how the critical taper angle is reached; a particular focus is on the region of outboard minor horizontal displacement provides insights into the forward propagation of material within, and in front of, the thrust wedge; tracking the position of the failure front (where the frontal thrust roots into the basal detachment) reveals the sequence and advancement of the imbricate thrusts. The model results show that a thrust system is generally composed of three deformation components: thrust wedge, pre-wedge and wedge front. A thrust belt involves growth that repeats episodically and cyclically. When a wedge reaches critical taper ( 10°), thrust movement within the wedge slows while the taper angle and wedge width gradually increase. In contrast, the displacement front (tracked here by the location of 0 m displacement) rapidly propagates forward along whilst the wedge height is fast growing. During this period, the wedge experiences a significant shortening after a new thrust initiates at the failure front, leading to an obvious decrease in wedge width. As soon as the critical taper is achieved, wedge interior (tracked here by the location of 50 m displacement) accelerates forward reducing the taper angle below critical. This is accompanied by a sudden increase in wedge width, slow advancement of displacement front, and slow uplift of the fold-thrust belt. The rapid movements within and in front of the wedge occur alternately. The model results also show that there is clear, although

  18. Evolution of fracture and fault-controlled fluid pathways in carbonates of the Albanides fold-thrust belt

    USGS Publications Warehouse

    Graham, Wall B.R.; Girbacea, R.; Mesonjesi, A.; Aydin, A.

    2006-01-01

    The process of fracture and fault formation in carbonates of the Albanides fold-thrust belt has been systematically documented using hierarchical development of structural elements from hand sample, outcrop, and geologic-map scales. The function of fractures and faults in fluid migration was elucidated using calcite cement and bitumen in these structures as a paleoflow indicator. Two prefolding pressure-solution and vein assemblages were identified: an overburden assemblage and a remote tectonic stress assemblage. Sheared layer-parallel pressure-solution surfaces of the overburden assemblage define mechanical layers. Shearing of mechanical layers associated with folding resulted in the formation of a series of folding assemblage fractures at different orientations, depending on the slip direction of individual mechanical layers. Prefolding- and folding-related fracture assemblages together formed fragmentation zones in mechanical layers and are the sites of incipient fault localization. Further deformation along these sites was accommodated by rotation and translation of fragmented rock, which formed breccia and facilitated fault offset across multiple mechanical layers. Strike-slip faults formed by this process are organized in two sets in an apparent conjugate pattern. Calcite cement and bitumen that accumulated along fractures and faults are evidence of localized fluid flow along fault zones. By systematic identification of fractures and faults, their evolution, and their fluid and bitumen contents, along with subsurface core and well-log data, we identify northeast-southwest-trending strike-slip faults and the associated structures as dominant fluid pathways in the Albanides fold-thrust belt. Copyright ?? 2006. The American Association of Petroleum Geologists. All rights reserved.

  19. Orogenic plateau growth: Expansion of the Turkish-Iranian Plateau across the Zagros fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Allen, M. B.; Saville, C.; Blanc, E. J.-P.; Talebian, M.; Nissen, E.

    2013-03-01

    This paper shows how the Turkish-Iranian Plateau grows laterally by incrementally incorporating adjacent parts of the Zagros fold-and-thrust belt. The limit of significant, seismogenic, thrusting in the Zagros (Mw > 5) occurs close to the regional 1250 m elevation contour. The seismicity cutoff is not a significant bedrock geology boundary. Elevations increase northward, toward regional plateau elevations of 2 km, implying that another process produced the extra elevation. Between the seismogenic limit of thrusting and the suture, this process is a plausibly ductile thickening of the basement, suggesting depth-dependent strain during compression. Similar depth-dependant crustal strain may explain why the Tibetan plateau has regional elevations 1500 m greater than the elevation limit of seismogenic thrusting at its margins. We estimate 68 km shortening across the Zagros Simply Folded Belt in the Fars region, and 120 km total shortening of the Arabian plate. The Dezful Embayment is a low strain zone in the western Zagros. Deformation is more intense to its northeast, in the Bakhtyari Culmination. The orogenic taper (across strike topographic gradient) across the Dezful Embayment is 0.0004, and across the Bakhtyari Culmination, 0.022. Lateral plateau growth is more pronounced farther east (Fars), where a more uniform structure has a taper of 0.010 up to elevations of 1750 m. A >100 km wide region of the Zagros further northeast has a taper of 0.002 and is effectively part of the Turkish-Iranian Plateau. Internal drainage enhances plateau development but is not a pre-requisite. Aspects of the seismicity, structure, and geomorphology of the Zagros do not support critical taper models for fold-and-thrust belts.

  20. Mesozoic intracontinental underthrust in the SE margin of the North China Block: Insights from the Xu-Huai thrust-and-fold belt

    NASA Astrophysics Data System (ADS)

    Shu, Liangshu; Yin, Hongwei; Faure, Michel; Chen, Yan

    2017-06-01

    The Xu-Huai thrust-and-fold belt, located in the southeastern margin of the North China Block, consists mainly of thrust and folded pre-Mesozoic strata. Its geodynamic evolution and tectonic setting are topics of long debate. This paper provides new evidence from geological mapping, structural analysis, and making balance cross-sections, with restoration of cross-sections. Results suggest that this belt was subjected to two-phase deformation, including an early-phase regional-scale NW-ward thrust and fold, and a late-phase extension followed by the emplacement of dioritic, monzodioritic porphyrites dated at 131-135 Ma and locally strike-slip shearing. According to the mapping, field observations and drill-hole data, three structural units were distinguished, namely, (1) the pre-Neoproterozoic crystalline basement in the eastern segment, (2) the nappe unit or the thrust-and-fold zone in the central segment, which is composed of Neoproterozoic to Ordovician carbonate rocks and Carboniferous-Permian coal-bearing rocks, about 2600 m thick, and (3) the western frontal zone. A major decollement fault has also been identified in the base of the nappe unit, on which dozen-meter to km-scale thrust-and-fold bodies were commonly developed. All pre-Mesozoic depositional sequences were involved into a widespread thrust and fold event. Six uncompetent-rock layers with biostratigraphic ages (Nanjing University, 1996) have been recognized, and each uncompetent-rock layer occurred mainly in the top of the footwall, playing an important role in the development of the Xu-Huai thrust-and-fold belt. Geometry of the major decollement fault suggests that the nappe unit of this belt was rooted in its eastern side, near the Tan-Lu Fault Zone. Two geological cross-sections were chosen for structural balancing and restoration. From the balanced cross-sections, ramp-flat and imbricated faults as well as fault-related folds were identified. A shortening of 20.6-29.6 km was obtained from

  1. Along-strike structural variation and thermokinematic development of the Cenozoic Bitlis-Zagros fold-thrust belt, Turkey and Iraqi Kurdistan

    NASA Astrophysics Data System (ADS)

    Barber, Douglas E.; Stockli, Daniel F.; Koshnaw, Renas I.; Tamar-Agha, Mazin Y.; Yilmaz, Ismail O.

    2016-04-01

    The Bitlis-Zagros orogen in northern Iraq is a principal element of the Arabia-Eurasia continent collision and is characterized by the lateral intersection of two structural domains: the NW-SE trending Zagros proper system of Iran and the E-W trending Bitlis fold-thrust belt of Turkey and Syria. While these components in northern Iraq share a similar stratigraphic framework, they exhibit along-strike variations in the width and style of tectonic zones, fold morphology and trends, and structural inheritance. However, the distinctions of the Bitlis and Zagros segments remains poorly understood in terms of timing and deformation kinematics as well as first-order controls on fold-thrust development. Structural and stratigraphic study and seismic data combined with low-T thermochronometry provide the basis for reconstructions of the Bitlis-Zagros fold-thrust belt in southeastern Turkey and northern Iraq to elucidate the kinematic and temporal relationship of these two systems. Balanced cross-sections were constructed and incrementally restored to quantify the deformational evolution and use as input for thermokinematic models (FETKIN) to generate thermochronometric ages along the topographic surface of each cross-section line. The forward modeled thermochronometric ages from were then compared to new and previously published apatite and zircon (U-Th)/He and fission-track ages from southeastern Turkey and northern Iraq to test the validity of the timing, rate, and fault-motion geometry associated with each reconstruction. The results of these balanced theromokinematic restorations integrated with constraints from syn-tectonic sedimentation suggest that the Zagros belt between Erbil and Suleimaniyah was affected by an initial phase of Late Cretaceous exhumation related to the Proto-Zagros collision. During the main Zagros phase, deformation advanced rapidly and in-sequence from the Main Zagros Fault to the thin-skinned frontal thrusts (Kirkuk, Shakal, Qamar) from middle

  2. Balancing cross-sections combining field work and remote sensing data using LithoTect software in the Zagros fold-and-thrust belt, N Iraq.

    NASA Astrophysics Data System (ADS)

    Reif, Daniel; Grasemann, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros fold-and-thrust belt has formed in detached Phanerozoic sedimentary cover rocks above a shortened crystalline Precambrian basement and evolved through the Late Cretaceous to Miocene collision between the Arabian and Eurasian plate, during which the Neotethys oceanic basin was closed. Deformation is partitioned in SW directed folding and thrusting of the sediments and NW-SE to N-S trending dextral strike slip faults. The sub-cylindrical doubly-plunging fold trains with wavelengths of 5 - 10 km host more than half of the world's hydrocarbon reserves in mostly anticlinal traps. Generally the Zagros is divided into three NW-SE striking tectonic units: the Zagros Imbricate Zone, the Zagros Simply Folded Belt and the Zagros Foredeep. This work presents a balanced cross-section through the Simply Folded Belt, NE of the city of Erbil (Kurdistan, Iraq). The regional stratigraphy comprises mainly Cretaceous to Cenozoic folded sediments consisting of massive, carbonate rocks (limestones, dolomites), reacting as competent layers during folding compared to the incompetent behavior of interlayered siltstones, claystones and marls. Although the overall security situation in Kurdistan is much better than in the rest of Iraq, structural field mapping was restricted to asphalt streets, mainly because of the contamination of the area with landmines and unexploded ordnance. In order to extend the structural measurements statistically over the investigated area, we used a newly developed software tool (www.terramath.com) for interactive structural mapping of spatial orientations (i.e. dip direction and dip angles) of the sedimentary beddings from digital elevation models. Structural field data and computed measurements where integrated and projected in NE-SW striking balanced cross-sections perpendicular to the regional trend of the fold axes. We used the software LithoTect (www.geologicsystems.com) for the restoration of the cross-sections. Depending on the interpretation

  3. The kinematic evolution of the Serra Central Salient, Eastern Brazil: A Neoproterozoic progressive arc in northern Espinhaço fold-thrust belt

    NASA Astrophysics Data System (ADS)

    Bersan, Samuel Moreira; Danderfer, André; Lagoeiro, Leonardo; Costa, Alice Fernanda de Oliveira

    2017-12-01

    Convex-to-the-foreland map-view curves are common features in fold-thrust belts around cratonic areas. These features are easily identifiable in belts composed of supracrustal rocks but have been rarely described in rocks from relatively deeper crustal levels where plastic deformation mechanisms stand out. Several local salients have been described in Neoproterozoic marginal fold-thrust belts around the São Francisco craton. In the northern part of the Espinhaço fold-thrust belt, which borders the eastern portion of the São Francisco craton, both Archean-Paleoproterozoic basement rocks and Proterozoic cover rocks are involved in the so-called Serra Central salient. A combination of conventional structural analysis and microstructural and paleostress studies were conducted to characterize the kinematic and the overall architecture and processes involved in the generation of this salient. The results allowed us to determine that the deformation along the Serra Central salient occur under low-grade metamorphic conditions and was related to a gently oblique convergence with westward mass transport that developed in a confined flow, controlled by two transverse bounding shear zones. We propose that the Serra Central salient nucleates as a basin-controlled primary arc that evolves to a progressive arc with secondary vertical axis rotation. This secondary rotation, well-illustrated by the presence of two almost orthogonal families of folds, was dominantly controlled by buttress effect exert by a basement high located in the foreland of the Serra Central salient.

  4. Structural modeling of the Zagros fold-and-thrust belt (Iraq) combining field work and remote sensing techniques

    NASA Astrophysics Data System (ADS)

    Reif, D.; Grasemann, B.; Faber, R.; Lockhart, D.

    2009-04-01

    The Zagros fold-and-thrust belt is known for its spectacular fold trains, which have formed in detached Phanerozoic sedimentary cover rocks above a shortened crystalline Precambrian basement. Orogeny evolved through the Late Cretaceous to Miocene collision between the Arabian and Eurasian plate, during which the Neotethys oceanic basin was closed. Still active deformation shortening in the order of 2-2.5 cm/yr is partitioned in S-SW directed folding and thrusting of the Zagros fold-and-thrust belt and NW-SE to N-S trending dextral strike slip faults. The sub-cylindrical doubly-plunging fold trains with wavelengths of 5 - 10 km host more than half of the world's hydrocarbon reserves in mostly anticlinal traps. In this work we investigate the three dimensional structure of the Zagros fold-and-thrust belt in the Kurdistan region of Iraq. The mapped region is situated NE from the city of Erbil and comprises mainly Cretaceous to Cenozoic folded sediments consisting of mainly limestones, dolomites, sandstones, siltstones, claystones and conglomerates. Although the overall security situation in Kurdistan is much better than in the rest of Iraq, structural field mapping was restricted to sections along the main roads perpendicular to the strike of the fold trains, mainly because of the contamination of the area with landmines and unexploded ordnance, a problem that dates back to the end of World War Two. Landmines were also used by the central government in the 1960s and 1970s in order to subdue Kurdish groups. During the 1980-1988 Iran-Iraq War, the north was mined again. In order to extend the structural measurements statistically over the investigated area resulting in a three-dimensional model of the fold trains, we used the Fault Trace module of the WinGeol software (www.terramath.com). This package allows the interactive mapping and visualization of the spatial orientations (i.e. dip and strike) of geological finite planar structures (e.g. faults, lithological

  5. Geodetic Insights into the Earthquake Cycle in a Fold and Thrust Belt

    NASA Astrophysics Data System (ADS)

    Ingleby, T. F.; Wright, T. J.; Butterworth, V.; Weiss, J. R.; Elliott, J.

    2017-12-01

    Geodetic measurements are often sparse in time (e.g. individual interferograms) and/or space (e.g. GNSS stations), adversely affecting our ability to capture the spatiotemporal detail required to study the earthquake cycle in complex tectonic systems such as subaerial fold and thrust belts. In an effort to overcome these limitations we combine 3 generations of SAR satellite data (ERS 1/2, Envisat & Sentinel-1a/b) to obtain a 25 year, high-resolution surface displacement time series over the frontal portion of an active fold and thrust belt near Quetta, Pakistan where a Mw 7.1 earthquake doublet occurred in 1997. With these data we capture a significant portion of the seismic cycle including the interseismic, coseismic and postseismic phases. Each satellite time series has been referenced to the first ERS-1 SAR epoch by fitting a ground deformation model to the data. This allows us to separate deformation associated with each phase and to examine their relative roles in accommodating strain and creating topography, and to explore the relationship between the earthquake cycle and critical taper wedge mechanics. Modeling of the coseismic deformation suggests a long, thin rupture with rupture length 7 times greater than rupture width. Rupture was confined to a 20-30 degree north-northeast dipping reverse fault or ramp at depth, which may be connecting two weak decollements at approximately 8 km and 13 km depth. Alternatively, intersections between the coseismic fault plane and pre-existing steeper splay faults underlying folds may have played a significant role in inhibiting rupture, as evidenced by intersection points bordering the rupture. These fault intersections effectively partition the fault system down-dip and enable long, thin ruptures. Postseismic deformation is manifest as uplift across short-wavelength folds at the thrust front, with displacement rates decreasing with time since the earthquake. Broader patterns of postseismic uplift are also observed

  6. Fracture patterns in the Zagros fold-and-thrust belt, Kurdistan Region of Iraq

    NASA Astrophysics Data System (ADS)

    Reif, Daniel; Decker, Kurt; Grasemann, Bernhard; Peresson, Herwig

    2012-11-01

    Fracture data have been collected in the Kurdistan Region of Iraq, which is a poorly accessible and unexplored area of the Zagros. Pre to early folding NE-SW striking extensional fractures and NW-SE striking contractive elements represent the older set affecting the exposed multilayer of the area. These latter structures are early syn-folding and followed by folding-related mesostructural assemblages, which include elements striking parallel to the axial trend of major folds (longitudinal fractures). Bedding perpendicular joints and veins, and extensional faults belonging to this second fracture set are located in the outer arc of exposed anticlines, whilst longitudinal reverse faults locate in the inner arcs. Consistently, these elements are associated with syn-folding tangential longitudinal strain. The younger two sets are related to E-W extension and NNE-SSW to N-S shortening, frequently displaying reactivation of the older sets. The last shortening event, which is described along the entire Zagros Belt, probably relates with the onset of N-S compression induced by the northward movement of the Arabian plate relative to the Eurasian Plate. In comparison between the inferred palaeostrain directions and the kinematics of recent GPS measurements, we conclude that the N-S compression and the partitioning into NW-SE trending folds and NW to N trending strike-slip faults likely remained unchanged throughout the Neogene tectonic history of the investigated area.

  7. Middle Pennsylvanian recurrent uplift of the Ouachita fold belt and basin subsidence in the Arkoma basin, Oklahoma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Elmore, R.D.; Sutherland, P.K.; White, P.B.

    1990-09-01

    Recurrent uplift of the Ouachita fold belt in Oklahoma coincided with the disruption of the Arkoma basin following the deposition of the Boggy Formation (early Desmoinesian time). The Boggy, composed of sandstone-shale sequences that record southerly progradation of coal-bearing, fluvially dominated deltaic complexes into the Arkoma basin, was folded at the time of uplift of the Ouachita fold belt. The uplift ended the progressive subsidence of the Arkoma basin and shifted the depocenter to the northwest. Subsequently, the Thurman Formation (middle Desmoinesian), which had a source in the southeast, was deposited in the smaller resurgent foreland basin over the foldedmore » and eroded surface of the Boggy. Chert-pebble conglomerates in the Thurman were derived from the erosion of newly elevated Ordovician and Devonian cherts in the core of the Ouachita foldbelt. Sandstone-shale packages are found in both formations. The origin of the coal-bearing cycles in the Boggy are enigmatic, but they probably were controlled by a combination of factors such as glacio-eustatic changes in sea level and delta-lobe abandonment. In contrast, cycles in the Thurman probably were strongly influenced by episodic thrust faulting and uplift in the Ouachitas.« less

  8. Structural analysis of sheath folds in the Sylacauga Marble Group, Talladega slate belt, southern Appalachians

    USGS Publications Warehouse

    Mies, J.W.

    1993-01-01

    Remnant blocks of marble from the Moretti-Harrah dimension-stone quarry provide excellent exposure of meter-scale sheath folds. Tubular structures with elliptical cross-sections (4 ???Ryz ??? 5) are the most common expression of the folds. The tubes are elongate subparallel to stretching lineation and are defined by centimeter-scale layers of schist. Eccentrically nested elliptical patterns and opposing asymmetry of folds ('S' and 'Z') are consistent with the sheath-fold interpretation. Sheath folds are locally numerous in the Moretti-Harrah quarry but are not widely distributed in the Sylacauga Marble Group; reconnaissance in neighboring quarries provided no additional observations. The presence of sheath folds in part of the Talladega slate belt indicates a local history of plastic, non-coaxial deformation. Such a history of deformation is substantiated by petrographic study of an extracted hinge from the Moretti-Harrah quarry. The sheath folds are modeled as due to passive amplification of initial structures during simple shear, using both analytic geometry and graphic simulation. As indicated by these models, relatively large shear strains (y ??? 9) and longitudinal initial structures are required. The shear strain presumably relates to NW-directed displacement of overlying crystalline rocks during late Paleozoic orogeny. ?? 1993.

  9. Formation and inversion of transtensional basins in the western part of the Lachlan Fold Belt, Australia, with emphasis on the Cobar Basin

    NASA Astrophysics Data System (ADS)

    Glen, R. A.

    The Palaeozoic history of the western part of the Lachlan Fold Belt in New South Wales was dominated by strike-slip tectonics. In the latest Silurian to late Early Devonian, an area of crust >25,000 km 2 lying west of the Gilmore Suture underwent regional sinistral transtension, leading to the development of intracratonic successor basins, troughs and flanking shelves. The volcaniclastic deep-water Mount Hope Trough and Rast Trough, the siliciclastic Cobar Basin and the volcanic-rich Canbelego-Mineral Hill Belt of the Kopyje Shelf all were initiated around the Siluro-Devonian boundary. They all show clear evidence of having evolved by both active syn-rift processes and passive later post-rift (sag-phase) processes. Active syn-rift faulting is best documented for the Cobar Basin and Mount Hope Trough. In the former case, the synchronous activity on several fault sets suggests that the basin formed by sinistral transtension in response to a direction of maximum extension oriented NE-SW. Structures formed during inversion of the Cobar Basin and Canbelego-Mineral Hill Belt indicate closure under a dextral transpressive strain regime, with a far-field direction of maximum shortening oriented NE-SW. In the Cobar Basin, shortening was partitioned into two structural zones. A high-strain zone in the east was developed into a positive half-flower structure by re-activation of early faults and by formation of short-cut thrusts, some with strike-slip movement, above an inferred steep strike-slip fault. Intense subvertical cleavage, a steep extension lineation and variably plunging folds are also present. A lower-strain zone to the west developed by syn-depositional faults being activated as thrusts soling into a gently dipping detachment. A subvertical cleavage and steep extension lineation are locally present, and variably plunging folds are common. Whereas Siluro-Devonian basin-opening appeared to be synchronous in the western part of the fold belt, the different period of

  10. The Cenozoic fold-and-thrust belt of Eastern Sardinia: Evidences from the integration of field data with numerically balanced geological cross section

    NASA Astrophysics Data System (ADS)

    Arragoni, S.; Maggi, M.; Cianfarra, P.; Salvini, F.

    2016-06-01

    Newly collected structural data in Eastern Sardinia (Italy) integrated with numerical techniques led to the reconstruction of a 2-D admissible and balanced model revealing the presence of a widespread Cenozoic fold-and-thrust belt. The model was achieved with the FORC software, obtaining a 3-D (2-D + time) numerical reconstruction of the continuous evolution of the structure through time. The Mesozoic carbonate units of Eastern Sardinia and their basement present a fold-and-thrust tectonic setting, with a westward direction of tectonic transport (referred to the present-day coordinates). The tectonic style of the upper levels is thin skinned, with flat sectors prevailing over ramps and younger-on-older thrusts. Three regional tectonic units are present, bounded by two regional thrusts. Strike-slip faults overprint the fold-and-thrust belt and developed during the Sardinia-Corsica Block rotation along the strike of the preexisting fault ramps, not affecting the numerical section balancing. This fold-and-thrust belt represents the southward prosecution of the Alpine Corsica collisional chain and the missing link between the Alpine Chain and the Calabria-Peloritani Block. Relative ages relate its evolution to the meso-Alpine event (Eocene-Oligocene times), prior to the opening of the Tyrrhenian Sea (Tortonian). Results fill a gap of information about the geodynamic evolution of the European margin in Central Mediterranean, between Corsica and the Calabria-Peloritani Block, and imply the presence of remnants of this double-verging belt, missing in the Southern Tyrrhenian basin, within the Southern Apennine chain. The used methodology proved effective for constraining balanced cross sections also for areas lacking exposures of the large-scale structures, as the case of Eastern Sardinia.

  11. Limited fluid in carbonate-shale hosted thrust faults of the Rocky Mountain Fold-and-Thrust Belt (Sun River Canyon, Montana)

    NASA Astrophysics Data System (ADS)

    OBrien, V. J.; Kirschner, D. L.

    2001-12-01

    It is widely accepted that fluids play a fundamental role in the movement of thrust faults in foreland fold-and-thrust belts. We have begun a combined structure-geochemistry study of faults in the Rocky Mountain fold-and-thrust belt in order to provide more insight into the occurrence and role(s) of fluid in the deformation of thrust faults. We focus on faults exposed in the Sun River Canyon of Montana, an area that contains some of the best exposures of the Rocky Mountain fold-and-thrust belt in the U.S. Samples were collected from two well exposed thrusts in the Canyon -- the Diversion and French thrusts. Both faults have thrust Mississippian dolostones over Cretaceous shales. Displacement exceeds several kilometers. Numerous small-displacement, subsidiary faults characterize the deformation in the hanging wall carbonates. The footwall shales accommodated more penetrative deformation, resulting in well developed foliation and small-scale folds. Stable isotope data have been obtained from host rock samples and veins from these faults. The data delimit an arcuate trend in oxygen-carbon isotope space. Approximately 50 host rock carbonate samples from the hanging walls have carbon and oxygen isotope values ranging from +3 to 0 and 28 to 19 per mil, respectively. There is no apparent correlation between isotopic values and distance from thrust fault at either locality. Fifteen samples of fibrous slickensides on small-displacement faults in the hanging walls have similar carbon and lower oxygen isotope values (down to 16 per mil). And 15 veins that either post-date thrusting or are of indeterminate origin have carbon and oxygen isotope values down to -3 and12 per mil, respectively. The isotopic data collected during the initial stages of this project are similar to some results obtained several hundred kilometers north in the Front Ranges of the Canadian Rockies (Kirschner and Kennedy, JGR 2000) and in carbonate fold-thrust belts of the Swiss Helvetic Alps and Italian

  12. Fold-and-thrust belt curvature in the Fars region, eastern Zagros, achieved by variable thrust slip vectors and fault block rotations

    NASA Astrophysics Data System (ADS)

    Edey, Alex; Allen, Mark B.

    2017-04-01

    Many fold-and-thrust belts are curved in plan view, but the origins of this curvature are debated. Understanding which mechanism(s) is appropriate is important to constrain the behaviour of the lithosphere during compressional deformation. Here we analyse the active deformation of the Fars Arc region in the eastern part of the Zagros, Iran, including slip vectors of 92 earthquakes, published GPS and palaeomagnetism data, and the distributions of young and/or active folds. The fold-and-thrust belt in the Fars Arc shows pronounced curvature, convex southwards. Folds trends vary from NW-SE in the west to ENE-WSW in the east. The GPS-derived velocity field shows NNE to SSW convergence, towards the foreland on the Arabian Plate, without dispersion. Earthquake slip vectors are highly variable, spanning a range of azimuths from SW to SSE in an Arabian Plate reference frame. The full variation of azimuths occurs within small (10s of km) sub-regions, but this variation is superimposed on a radial pattern, whereby slip vectors tend to be parallel to the regional topographic gradient. Given the lack of variation in the GPS vectors, we conclude that the Fars Arc is not curved as a result of gravitational spreading over the adjacent foreland, but as a result of deformation being restricted at tectonic boundaries at the eastern and western margins of the Arc. Fault blocks and folds within the Fars Arc, each 20-40 km long, rotate about vertical axes to achieve the overall curvature, predominantly clockwise in the west and counter-clockwise in the east. Active folds of different orientations may intersect and produce dome-and-basin interference patterns, without the need for a series of separate deformation phases of different stress orientations. The Fars Arc clearly contrasts with the Himalayas, where both GPS and earthquake slip vectors display radial patterns towards the foreland, and gravitational spreading is a viable mechanism for producing fold-and-thrust belt curvature.

  13. Rock magnetism and magnetic fabric of the Triassic rocks from the West Spitsbergen Fold-and-Thrust Belt and its foreland

    NASA Astrophysics Data System (ADS)

    Dudzisz, Katarzyna; Szaniawski, Rafał; Michalski, Krzysztof; Chadima, Martin

    2018-03-01

    Magnetic fabric and magnetomineralogy of the Early Triassic sedimentary rocks, collected along the length of the West Spitsbergen Fold-and-Thrust Belt (WSFTB) and from subhorizontal beds on its foreland, is presented with the aim to compare magnetic mineralogy of these areas, determine the carriers of magnetic fabric and identify tectonic deformation reflected in the magnetic fabric. Magnetic mineralogy varies and only in part depends on the lithology. The magnetic fabric at all sampling sites is controlled by paramagnetic minerals (phyllosilicates and Fe-carbonates). In the fold belt, it reflects the low degree of deformation in a compressional setting with magnetic lineation parallel to fold axis (NW-SE). This is consistent with pure orthogonal compression model of the WSFTB formation, but it also agrees with decoupling model. Inverse fabric, observed in few sites, is carried by Fe-rich carbonates. In the WSFTB foreland, magnetic lineation reflects the Triassic paleocurrent direction (NE-SW). The alternation between normal and inverse magnetic fabric within the stratigraphic profile could be related to sedimentary cycles.

  14. Kinematics of the active West Andean fold-and-thrust belt (central Chile): Structure and long-term shortening rate

    NASA Astrophysics Data System (ADS)

    Riesner, M.; Lacassin, R.; Simoes, M.; Armijo, R.; Rauld, R.; Vargas, G.

    2017-02-01

    West verging thrusts, synthetic with the Nazca-South America subduction interface, have been recently discovered at the western front of the Andes. At 33°30'S, the active San Ramón fault stands as the most frontal of these west verging structures and represents a major earthquake threat for Santiago, capital city of Chile. Here we elaborate a detailed 3-D structural map and a precise cross section of the West Andean fold-and-thrust belt based on field observations, satellite imagery, and previous structural data, together with digital topography. We then reconstruct the evolution of this frontal belt using a trishear kinematic approach. Our reconstruction implies westward propagation of deformation with a total shortening of 9-15 km accumulated over the last 25 Myr. An overall long-term shortening rate of 0.1-0.5 mm/yr is deduced. The maximum value of this shortening rate compares well with the rate that may be inferred from recent trench data across the San Ramón fault and the slip associated with the past two Mw > 7 earthquakes. This suggests that the San Ramón fault is most probably the only presently active fault of the West Andean fold-and-thrust-belt and that most—if not all—the deformation is to be released seismically.

  15. Orogen-transverse tectonic window in the Eastern Himalayan fold belt: A superposed buckling model

    NASA Astrophysics Data System (ADS)

    Bose, Santanu; Mandal, Nibir; Acharyya, S. K.; Ghosh, Subhajit; Saha, Puspendu

    2014-09-01

    The Eastern Lesser Himalayan fold-thrust belt is punctuated by a row of orogen-transverse domal tectonic windows. To evaluate their origin, a variety of thrust-stack models have been proposed, assuming that the crustal shortening occurred dominantly by brittle deformations. However, the Rangit Window (RW) in the Darjeeling-Sikkim Himalaya (DSH) shows unequivocal structural imprints of ductile deformations of multiple episodes. Based on new structural maps, coupled with outcrop-scale field observations, we recognize at least four major episodes of folding in the litho-tectonic units of DSH. The last episode has produced regionally orogen-transverse upright folds (F4), the interference of which with the third-generation (F3) orogen-parallel folds has shaped the large-scale structural patterns in DSH. We propose a new genetic model for the RW, invoking the mechanics of superposed buckling in the mechanically stratified litho-tectonic systems. We substantiate this superposed buckling model with results obtained from analogue experiments. The model explains contrasting F3-F4 interferences in the Lesser Himalayan Sequence (LHS). The lower-order (terrain-scale) folds have undergone superposed buckling in Mode 1, producing large-scale domes and basins, whereas the RW occurs as a relatively higher-order dome nested in the first-order Tista Dome. The Gondwana and the Proterozoic rocks within the RW underwent superposed buckling in Modes 3 and 4, leading to Type 2 fold interferences, as evident from their structural patterns.

  16. Rapid Intradeformational Emplacement of the Big Hole Canyon Pluton Into the Sevier Fold-Thrust Belt, Southwest Montana.

    NASA Astrophysics Data System (ADS)

    Hespenheide, M. A.

    2002-12-01

    The Big Hole Canyon pluton (BHCp) is a Late Cretaceous pluton emplaced within the Sevier fold-and-thrust belt of the western North American Cordillera. The pluton is exposed over 60km2 and a thickness of ~1400m. Combined anisotropy of magnetic susceptibility (AMS), structural, and field studies document a clear pattern of magmatic flow radiating from at least three subvertical conduits <100m wide and ~300 to ~800m long. Interpreted flow plunges change rapidly to subhorizontal fabrics across the rest of the pluton, matching the expected pattern for laccolithic emplacement. Ascent conduits within the Big Hole Canyon pluton are coincident with the fold axis of an anticline above a thrust ramp, suggesting that the magma ascended up the fault of the fault-bend-fold. Geobarometry and stratigraphic reconstructions indicate an emplacement depth of approximately ~3km. Preliminary thermal modeling indicates that the BHCp was emplaced in 250,000 years, likely between periods of regional shortening deformation. Rapid magma ascent rates calculated by dike flow modeling and implied by entrained wall-rock xenoliths may indicate sequential magma injection into the pluton; an absence of chill margins between phases within the pluton indicates that sequential injections must have taken place quickly enough that the magmas did not have time to cool below the solidus temperature. The geometry and location of the BHCp suggest that magma used a pre-existing fault as a mechanical discontinuity for both ascent and emplacement. Continued intrusion of magma had a sufficient amount of driving pressure to stretch, shear, and lift the roof of the pluton. Detailed field mapping, structural studies, AMS, and thermobarometry indicate that the Late Cretaceous Big Hole Canyon pluton was emplaced as a laccolith at the top of a pre-existing fault-bend-fold in the frontal portion of the Sevier fold-thrust belt.

  17. First thermochronological constraints on the Cenozoic extension along the Balkan fold-thrust belt (Central Stara Planina Mountains, Bulgaria)

    NASA Astrophysics Data System (ADS)

    Kounov, Alexandre; Gerdjikov, Ianko; Vangelov, Dian; Balkanska, Eleonora; Lazarova, Anna; Georgiev, Stoyan; Blunt, Edward; Stockli, Daniel

    2017-11-01

    The Balkan fold-thrust belt, exposed in Bulgaria and north-east Serbia, is part of the north-east vergent segment of the bi-vergent Eastern Mediterranean Alpine orogen. It was formed during two distinct compressional stages; the first one lasted from the Middle Jurassic to the Early Cretaceous and the second from Late Cretaceous to the Paleogene. Although the compressional tectonic evolution of the Balkan fold-thrust belt since the Middle Jurassic and during most of the Mesozoic is relatively well studied, the final exhumation of the rocks of the belt during the Cenozoic has remained poorly understood. Here, we present the first thermochronological constraints, based on fission-track and [U-Th-(Sm)]/He analysis, showing that along the central part of the belt syn- to post-orogenic extension could have started as early as the middle Eocene. Low-temperature thermochronological analysis of samples collected from three areas reveals at least two phases of increased cooling and exhumation during the Cenozoic. The first exhumation phase took place between 44 and 30 Ma and appears to be related to the syn- to post-orogenic collapse coeval with the earliest Cenozoic extensional stage observed across the southern Balkan Peninsula. A period of relative quiescence (between 30 and 25 Ma) is followed by the next cooling stage, between 25 and 20 Ma, which appears to be related to late Oligocene to early Miocene crustal extension across the Balkan Peninsula. Extension accommodated by the late Miocene to Recent age Sub-Balkan Graben System does not appear to have produced exhumation of rocks from beneath 2-4 km depth, as it was not detected by the low-temperature thermochronological methods applied in this study.

  18. Stratigraphy and Folding in the Cenozoic Cover of a Fold-Thrust Belt in the Nallıhan Region (Ankara, Central Turkey)

    NASA Astrophysics Data System (ADS)

    Karaaǧaç, Serdal; Koral, Hayrettin

    2017-04-01

    This study investigates stratigraphy and structural features in the Cenozoic sedimentary sequence of the fold-thrust belt of the Nallıhan-Ankara region, located to the north of the İzmir-Ankara-Erzincan Suture Zone. Permian-Triassic age marble intercalated with schist-phyllites, the upper Jurassic-lower Cretaceous age limestone and the upper Cretaceous age sandstone-shale alternation compose the basement in the study area. These rocks are unconformably overlain by the Cenozoic age terrestrial sedimentary and volcanic units. The Cenozoic stratigraphy begins with the Paleocene-Eocene age coal-bearing, at times, volcanic intercalated conglomerate-sandstone-mudstone alternation of alluvial-fluvial origins (Aksaklar Formation) and the tuff intercalated with lacustrine limestone, bituminous limestone (Kabalar Formation). These units are conformably overlain by the Eocene age basalt-andesite and pyroclastic rocks (Meyildere volcanics). The Paleocene-Eocene aged units are unconformably overlain by the conglomerate-sandstone-mudstone-marl of a lower-middle Miocene lacustrine environment (Hançili Formation). The terrestrial conglomerate-sandstone alternation (Örencik Formation) is the youngest unit in the Cenozoic stratigraphy, and is assumed to be of Pliocene age based its stratigraphic position on older units. Field study shows existence of both folds and faults in the sedimentary cover. Stereographic projections of bedding measured in the field shows N25W/45NW and N60W/4SE-oriented fold axes in the Paleocene-Eocene age units. There are also N76W/12SE and N88E/8NE-oriented folds. The difference in fold-axis orientations suggests that some folds may have been rotated in blocks bound by faults during the post-Paleocene/Eocene period. Whereas, the lower-middle Miocene units manifest N88W/13SE-oriented fold axes. It is thus proposed that the observed difference in the azimuth of fold axes represent two different folding phases, one with NE-SW and the other with N

  19. Evidence for synchronous thin-skinned and basement deformation in the Cordilleran fold-thrust belt: the Tendoy Mountains, southwestern Montana

    NASA Astrophysics Data System (ADS)

    McDowell, Robin John

    1997-01-01

    The Tendoy Mountains contain the easternmost thin-skinned thrust sheets in the Cordilleran fold-thrust belt of southwestern Montana, and are in the zone of tectonic overlap between the Rocky Mountain foreland and the Cordilleran fold-thrust belt. The three frontal thrust sheets of the Tendoy Mountains are from north to south, the Armstead, McKenzie, and Tendoy sheets. Near the southeastern terminus of the Tendoy thrust sheet is a lateral ramp in which the Tendoy thrust climbs along strike from the Upper Mississippian Lombard Limestone to lower Cretaceous rocks. This ramp coincides with the southeastern side of the Paleozoic Snowcrest trough and projection of the range-flanking basement thrust of the Blacktail-Snowcrest uplift, suggesting either basement or stratigraphic control on location of the lateral ramp. Axes of major folds on the southern part of the Tendoy thrust sheet are parallel to the direction of thrust transport and to the trend of the Snowcrest Range. They are a result of: (1) Pre-thrust folding above basement faults; (2) Passive transportation of the folds from a down-plunge position; (3) Minor reactivation of basement faults; and (4) Emplacement of blind, sub-Tendoy, thin-skinned thrust faults. The Tendoy sheet also contains a major out-of-sequence thrust fault that formed in thick Upper Mississippian shales and created large, overturned, foreland-verging folds in Upper Mississippian to Triassic rocks. The out-of-sequence fault can be identified where stratigraphic section is omitted, and by a stratigraphic separation diagram that shows it cutting down section in the direction of transport. The prominent lateral ramp at the southern terminus of the Tendoy thrust sheet is a result of fault propagation through strata folded over the edge of the Blacktail-Snowcrest uplift.

  20. Development of an arcuate fold-thrust belt as a result of basement configuration: an example from the Rocky Mountain Front Range, Montana

    NASA Astrophysics Data System (ADS)

    Burberry, C. M.; Cannon, D. L.; Engelder, T.; Cosgrove, J. W.

    2010-12-01

    The Sawtooth Range forms part of the Montana Disturbed Belt in the Front Ranges of the Rocky Mountains, along strike from the Alberta Syncline in the Canadian Rockies. The belt developed in the footwall to the Lewis Thrust during the Sevier orogeny and is similar in deformation style to the Canadian Foothills, with a series of stacked thrust sheets carrying Palaeozoic carbonates. The Sawtooth Range can be divided into an inner and outer deformed belt, separated by exposed fold structures in the overlying clastic sequence. Structures in the deformed belts plunge into the culmination of the NE-trending Scapegoat-Bannatyne trend, part of the Great Falls Tectonic Zone (GFTZ). Other mapped faults, including the Pendroy fault zone to the north, parallel this trend. A number of mechanisms have been proposed for the development of primary arcs in fold-thrust belts, including linkage of two thrust belts with different strikes, differential transport of segments of the belt, the geometry of the indentor, local plate heterogeneity and pre-existing basement configuration. Arcuate belts may also develop as a result of later bending of an initially straight orogen. In the Swift Dam area, part of the outer belt of the Sawtooth Range, the strike of the belt changes from 165 to 150. This apparent change in strike is accommodated by a sinistral lateral ramp in the Swift Dam Thrust. In addition, this outer belt becomes broader to the north in the Swift Dam region. However, the outer belt becomes extremely narrow in the Teton Canyon region to the south, and the deformation front is characterised by an intercutaneous wedge structure, rather than the trailing-edge imbricate fan seen to the north. A similar imbricate fan structure is seen to the south, in the Sun River Canyon region, corresponding well to the classic model of a deformation belt governed by a dominant thrust sheet, after Boyer & Elliot. The Sawtooth Range can be described as an active-roof duplex in the footwall to the

  1. Distinguishing thrust sequences in gravity-driven fold and thrust belts

    NASA Astrophysics Data System (ADS)

    Alsop, G. I.; Weinberger, R.; Marco, S.

    2018-04-01

    Piggyback or foreland-propagating thrust sequences, where younger thrusts develop in the footwalls of existing thrusts, are generally assumed to be the typical order of thrust development in most orogenic settings. However, overstep or 'break-back' sequences, where later thrusts develop above and in the hangingwalls of earlier thrusts, may potentially form during cessation of movement in gravity-driven mass transport deposits (MTDs). In this study, we provide a detailed outcrop-based analysis of such an overstep thrust sequence developed in an MTD in the southern Dead Sea Basin. Evidence that may be used to discriminate overstep thrusting from piggyback thrust sequences within the gravity-driven fold and thrust belt includes upright folds and forethrusts that are cut by younger overlying thrusts. Backthrusts form ideal markers that are also clearly offset and cut by overlying younger forethrusts. Portions of the basal detachment to the thrust system are folded and locally imbricated in footwall synclines below forethrust ramps, and these geometries also support an overstep sequence. However, new 'short-cut' basal detachments develop below these synclines, indicating that movement continued on the basal detachment rather than it being abandoned as in classic overstep sequences. Further evidence for 'synchronous thrusting', where movement on more than one thrust occurs at the same time, is provided by displacement patterns on sequences of thrust ramp imbricates that systematically increases downslope towards the toe of the MTD. Older thrusts that initiate downslope in the broadly overstep sequence continue to move and therefore accrue greater displacements during synchronous thrusting. Our study provides a template to help distinguish different thrust sequences in both orogenic settings and gravity-driven surficial systems, with displacement patterns potentially being imaged in seismic sections across offshore MTDs.

  2. Folding of a detachment and fault - Modified detachment folding along a lateral ramp, southwestern Montana, USA

    NASA Astrophysics Data System (ADS)

    Schmidt, Christopher; Whisner, S. Christopher; Whisner, Jennifer B.

    2014-12-01

    The inversion of the Middle Proterozoic Belt sedimentary basin during Late Cretaceous thrusting in Montana produced a large eastwardly-convex salient, the southern boundary of which is a 200 km-long oblique to lateral ramp subtended by a detachment between the Belt rocks and Archean basement. A 10 km-long lateral ramp segment exposes the upper levels of the detachment where hanging wall Belt rocks have moved out over the Paleozoic and Mesozoic section. The hanging wall structure consists of a train of high amplitude, faulted, asymmetrical detachment folds. Initial west-east shortening produced layer parallel shortening fabrics and dominantly strike slip faulting followed by symmetrical detachment folding. 'Lock-up' of movement on the detachment surface produced regional simple shear and caused the detachment folds to become asymmetrical and faulted. Folding of the detachment surface after lock-up modified the easternmost detachment folds further into a southeast-verging, overturned fold pair with a ramp-related fault along the base of the stretched mutual limb.

  3. Transpressional deformation, strain partitioning and fold superimposition in the southern Chinese Altai, Central Asian Orogenic Belt

    NASA Astrophysics Data System (ADS)

    Li, Pengfei; Sun, Min; Rosenbaum, Gideon; Cai, Keda; Chen, Ming; He, Yulin

    2016-06-01

    Transpressional deformation has played an important role in the late Paleozoic evolution of the western Central Asian Orogenic Belt (CAOB), and understanding the structural evolution of such transpressional zones is crucial for tectonic reconstructions. Here we focus on the transpressional Irtysh Shear Zone with an aim at understanding amalgamation processes between the Chinese Altai and the West/East Junggar. We mapped macroscopic fold structures in the southern Chinese Altai and analyzed their relationships with the development of the adjacent Irtysh Shear Zone. Structural observations from these macroscopic folds show evidence for four generations of folding and associated fabrics. The earlier fabric (S1), is locally recognized in low strain areas, and is commonly isoclinally folded by F2 folds that have an axial plane orientation parallel to the dominant fabric (S2). S2 is associated with a shallowly plunging stretching lineation (L2), and defines ∼NW-SE tight-close upright macroscopic folds (F3) with the doubly plunging geometry. F3 folds are superimposed by ∼NNW-SSE gentle F4 folds. The F3 and F4 folds are kinematically compatible with sinistral transpressional deformation along the Irtysh Shear Zone and may represent strain partitioning during deformation. The sub-parallelism of F3 fold axis with the Irtysh Shear Zone may have resulted from strain partitioning associated with simple shear deformation along narrow mylonite zones and pure shear-dominant deformation (F3) in fold zones. The strain partitioning may have become less efficient in the later stage of transpressional deformation, so that a fraction of transcurrent components was partitioned into F4 folds.

  4. Numerical modelling of the role of salt in continental collision: An application to the southeast Zagros fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Ghazian, Reza Khabbaz; Buiter, Susanne J. H.

    2014-09-01

    The Zagros fold-and-thrust belt formed in the collision of Arabia with Central Iran. Its sedimentary sequence is characterised by the presence of several weak layers that may control the style of folding and thrusting. We use 2-D thermo-mechanical models to investigate the role of salt in the southeast Zagros fold-and-thrust belt. We constrain the crustal and lithospheric thickness, sedimentary stratification, convergence velocity, and thermal structure of the models from available geological and geophysical data. We find that the thick basal layer of Hormuz salt in models on the scale of the upper-mantle decouples the overlying sediments from the basement and localises deformation in the sediments by trench-verging shear bands. In the collision stage of the models, basement dips with + 1° towards the trench. Including the basal Hormuz salt improves the fit of predicted topography to observed topography. We use the kinematic results and thermal structure of this large-scale model as the initial conditions of a series of upper-crustal-scale models. These models aim to investigate the effects of basal and intervening weak layers, salt strength, basal dip, and lateral salt distribution on deformation style of the simply folded Zagros. Our results show that in addition to the Hormuz salt at the base of the sedimentary cover, at least one intervening weak layer is required to initiate fold-dominated deformation in the southeast Zagros. We find that an upper-crustal-scale model, with a basal and three internal weak layers with viscosities between 5 × 1018 and 1019 Pa s, and a basement that dips + 1° towards the trench, best reproduces present-day topography and the regular folding of the sedimentary layers of the simply folded Zagros.

  5. Tectonics and kinematics of a foreland folded belt influenced by salt, arctic Canada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harrison, J.C.

    1996-12-31

    The Ordovician (upper Arenig-Llanvirn) Bay Fiord Formation is one of three widespread evaporite units known to have profoundly influenced the style of contractional tectonics within the Innuitian orogen of Arctic Canada. In the western Arctic Islands, the salt-bearing Bay Fiord Formation has accommodated buckling and mostly subsurface thrusting in the west-trending Parry Islands foldbelt. A characteristic feature of this belt is a stratigraphic succession more than 10 km thick featuring three rigid and widespread sedimentary layers and two intervening ductile layers (lower salt and upper shale). The ductile strata have migrated to anticlinal welts during buckling. Other features of themore » foldbelt include (1) an extreme length of individual upright folds (up to 330 km), (2) extreme foldbelt width (up to 11%), (5) a shallow dipping salt decollement system (0.1{degrees}-0.6{degrees}) that has also been folded in the hinterland and later extended, and (6) a complete absence of halokinetic piercing diapirs. The progression from simple thrust-fold structure on the foldbelt periphery to complex in the interior provides a viable kinematic model for this and other contractional salt provinces. One feature of this model is a single massive triangle zone structure (passive roof duplex) that may envelop the entire 200-km width of the foldbelt and underlie an area exceeding 52,000 km{sup 2}.« less

  6. Neotectonics and seismicity of a slowly deforming segment of the Adria-Europe convergence zone - the northern Dinarides fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Ustaszewski, Kamil; Herak, Marijan; Tomljenović, Bruno; Herak, Davorka; Matej, Srebrenka

    2014-05-01

    With GPS-derived shortening rates of c. 3-5 mm/a, the Adria-Europe convergence zone across the fold-and-thrust belt of the Dinarides (Balkan Peninsula) is a slowly deforming plate boundary by global standards. We have analysed the active tectonics and instrumental seismicity of the northernmost segment of this fold-and-thrust belt at its border to the Pannonian Basin. This area hosts a Maastrichtian collisional suture formed by closure of Mesozoic fragments of the Neotethys, overprinted by Miocene back-arc extension, which led to the exhumation of greenschist- to amphibolite-grade rocks in several core complexes. Geological, geomorphological and reflection seismic data provide evidence for a compressive or transpressive reactivation of extensional faults after about 5 Ma. The study area represents the seismically most active region of the Dinarides apart from the Adriatic Sea coast and the area around Zagreb. The strongest instrumentally recorded earthquake (27 October 1969) affected the city of Banja Luka (northern Bosnia and Herzegovina). Fault plane solutions for the main shock (ML 6.4) and its largest foreshock (ML 6.0) indicate reverse faulting along ESE-WNW-striking nodal planes and generally N-S trending pressure axes. The spatial distribution of epicentres and focal depths, analyses of the macroseismic field and fault-plane solutions for several smaller events suggest on-going shortening in the internal Dinarides. Our results therefore imply that current Adria-Europe convergence is widely distributed across c. 300 km, rendering the entire Dinarides fold-and-thrust belt a slowly deforming plate boundary.

  7. Duplex thrusting in the South Dabashan arcuate belt, central China

    NASA Astrophysics Data System (ADS)

    Li, Wangpeng; Liu, Shaofeng; Wang, Yi; Qian, Tao; Gao, Tangjun

    2017-10-01

    Due to later tectonic superpositioning and reworking, the South Dabashan arcuate belt extending NW to SE has experienced several episodes of deformation. The earlier deformational style and formation mechanism of this belt remain controversial. Seismic interpretations and fieldwork show that the curved orogen can be divided into three sub-belts perpendicular to the strike of the orogen, the imbricate thrust fault belt, the detachment fold belt and the frontal belt from NE to SW. The imbricate thrust fault belt is characterized by a series of SW-directed thrust faults and nappes. Two regional detachment layers at different depths have been recognized in the detachment fold and frontal belts, and these detachment layers divide the sub-belts into three structural layers: the lower, middle, and upper structural layers. The middle structural layer is characterized by a passive roof duplex structure, which is composed of a roof thrust at the top of the Sinian units, a floor thrust in the upper Lower Triassic units, and horses in between. Apatite fission track dating results and regional structural analyses indicate that the imbricate thrust fault belt may have formed during the latest Early Cretaceous to earliest Paleogene and that the detachment fold belt may have formed during the latest Late Cretaceous to earliest Neogene. Our findings provide important reference values for researching intra-continental orogenic and deformation mechanisms in foreland fold-thrust belts.

  8. Radiometric Dating of Folds: A new approach to determine the timing of deformation at shallow-crustal conditions, with examples from the Mexican Fold-Thrust Belt

    NASA Astrophysics Data System (ADS)

    Fitz Diaz, E.; van der Pluijm, B. A.

    2012-12-01

    We are developing a robust method to obtain absolute ages of folds that were formed at shallow crustal conditions. The method takes advantage of illite neocrystallization in folded, clay-bearing layers and the ability to obtain accurate retention and total gas ages from small size fractions using encapsulated Ar analysis, analogous to prior work on fault gouge dating. We illustrate our approach in folded Cretaceous shale-bentonitic layers that are interbedded with carbonates of the Zimapán and the Tampico-Misantla cretaceous basins in central-eastern Mexico. Basinal carbonates were buried by syntectonic turbidites and inverted during the formation of the Mexican Fold-Thrust in the Late Cretaceous. Results were obtained from four chevron folds that are representative of different stages of deformation, burial/temperature conditions and location within this thin-skinned orogenic wedge: two from the Zimapán Basin (Folds 1 and 2) in the west and two from the Tampico-Misantla Basin (Folds 3 and 4) in the east. Mineralogic compositions and variations in illite-polytypes, crystallite-size (CS) and Ar/Ar ages were obtained from size fractions in limbs and hinges of folded layers. Ar retention ages produce a folding age of ~81 Ma for Fold 1 and ~69 Ma for Fold 2, which are fully consistent with stratigraphic limits from syn-orogenic turbidities and observed overprinting events in the Mexican Fold-Thrust Belt. The total gas age of Fold 3, on the easternmost margin of the Tampico-Misantla Basin is similar to that of Fold 2, indicating that the second event is regional in scale. In addition to presenting a new, reliable method to constrain the timing of local deformation, we interpret folding and associated clay neo-mineralization in terms of the regional burial history, and localization and propagation of deformation within a heterogeneous orogenic wedge involving progressive deformation of two basins separated by a platform block.

  9. Subsurface structural interpretation by applying trishear algorithm: An example from the Lenghu5 fold-and-thrust belt, Qaidam Basin, Northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Pei, Yangwen; Paton, Douglas A.; Wu, Kongyou; Xie, Liujuan

    2017-08-01

    The application of trishear algorithm, in which deformation occurs in a triangle zone in front of a propagating fault tip, is often used to understand fault related folding. In comparison to kink-band methods, a key characteristic of trishear algorithm is that non-uniform deformation within the triangle zone allows the layer thickness and horizon length to change during deformation, which is commonly observed in natural structures. An example from the Lenghu5 fold-and-thrust belt (Qaidam Basin, Northern Tibetan Plateau) is interpreted to help understand how to employ trishear forward modelling to improve the accuracy of seismic interpretation. High resolution fieldwork data, including high-angle dips, 'dragging structures', thinning hanging-wall and thickening footwall, are used to determined best-fit trishear model to explain the deformation happened to the Lenghu5 fold-and-thrust belt. We also consider the factors that increase the complexity of trishear models, including: (a) fault-dip changes and (b) pre-existing faults. We integrate fault dip change and pre-existing faults to predict subsurface structures that are apparently under seismic resolution. The analogue analysis by trishear models indicates that the Lenghu5 fold-and-thrust belt is controlled by an upward-steepening reverse fault above a pre-existing opposite-thrusting fault in deeper subsurface. The validity of the trishear model is confirmed by the high accordance between the model and the high-resolution fieldwork. The validated trishear forward model provides geometric constraints to the faults and horizons in the seismic section, e.g., fault cutoffs and fault tip position, faults' intersecting relationship and horizon/fault cross-cutting relationship. The subsurface prediction using trishear algorithm can significantly increase the accuracy of seismic interpretation, particularly in seismic sections with low signal/noise ratio.

  10. Comments on "The Cenozoic fold-and-thrust belt of Eastern Sardinia: Evidences from the integration of field data with numerically balanced geological cross section" by Arragoni et al., 2016

    NASA Astrophysics Data System (ADS)

    Berra, F.; Lanfranchi, A.; Jadoul, F.

    2017-02-01

    Arragoni et al. (2016) suggest in their paper published on tectonics that the carbonate succession of Eastern Sardinia represents a Cenozoic fold-and-thrust belt, related to the Alpine orogenesis. According to these authors, this supposed fold-and-thrust belt represents the southward continuation of the Alpine Corsica collisional chain and the missing link between the Alpine Chain and the Calabria-Peloritani domain. Field evidence and the published literature document instead that all the surfaces that Arragoni et al. interpret as thrust are actually stratigraphic contacts. The balanced geological section of Arragoni represents thus a geometric exercise missing the basic data needed to nurse the proposed model, and it does not reflect the geology of Eastern Sardinia. The data provided by Arragoni et al. (2016) do not support the presence of an Alpine thrust-and-fold belt in Eastern Sardinia, and this paper may suggest to the geological community a misleading interpretation of the geodynamic evolution of the Alpine and Mediterranean area.

  11. The occurrence and origin of celestite in the Abolfares region, Iran: Implications for Sr-mineralization in Zagros fold belt (ZFB)

    NASA Astrophysics Data System (ADS)

    Pourkaseb, Houshang; Zarasvandi, Alireza; Rezaei, Mohsen; Mahdavi, Reyhaneh; Ghanavati, Fatemeh

    2017-10-01

    The major celestite deposits in Zagros Fold belt are associated with coastal marine carbonate and evaporate sediments of Oligo-Miocene Asmari and Lower Miocene Ghachsaran Formations. In the Abolfares region, celestite mineralization is extended in the western limb of Bangestan anticline in the carbonates of Early Miocene (middle part of Asmari Formation), underlying by dolomitic carbonates of Burdigalian. From bottom to top three main types of mineralization can be distinguished in the study area: (1) layer texture resulting from replacement of algal limestone by celestite minerals with some parts showing idiomorphic crystals (geodes) along the walls of the cavities, (2) celestite occurrence as irregular massive shape interconnected small crystals and nodules, and (3) celestite mineralization associated with steeply dipping veins and open space fracture fillings, resulting from late-stage epigenetic processes. Highlightly, the ore-hosting carbonate rocks were deposited in an intertidal - supratidal protected setting with hypersaline conditions, in accordance with other celestite deposits of the Zagros Fold belt. The abundance of diagenetic crystallization rhythmites, carbonate and anhydrite inclusions as confirmed by Laser Raman spectroscopy analysis, high Sr/Ba values (average; 8726.1) and strong negative correlations between SO3 vs CaO (R2 = 0.98), SrO vs CaO (R2 = 0.96) with positive correlations between Ba vs SrO (R2 = 0.54) and SO3 vs SrO (R2 = 0.98) highlight the role of high Sr late-diagenetic brines in replacement of carbonates with celestite minerals. It seems that the inception of compressional folding during or soon after the deposition of the Asmari Formation in the carbonate platform at the margin of NW-trending basin in the foreland of the Zagros orogenic belt lead to the upward refluxing of penetrated high-Sr diagenetic brines and celestite mineralization.

  12. Pre-folding fracture development in the Lurestan region of the Zagros Fold and Thrust Belt: constraints from early fracture sets in the Shabazan and Asmari Formations

    NASA Astrophysics Data System (ADS)

    Corradetti, Amerigo; Tavani, Stefano; D'Assisi Tramparulo, Francesco; Prinzi, Ernesto Paolo; Vitale, Stefano; Parente, Mariano; Morsalnejad, Davoud; Mazzoli, Stefano

    2017-04-01

    In the Zagros Fold and Thrust Belt (FTB), the timing of fracture development with respect to folding is debated. Multiple fracture systems occur in the area. These include "typical" fracture systems that are oriented parallel and orthogonal to the NW-SE strike of the belt, as well as sets oriented N-S and E-W. The interpretation of the N-S and E-W sets is controversial. Despite the general consensus about the first-order relationship between these fractures and inherited N-S striking basement faults, their timing and kinematic significance is not yet fully understood. The ambiguous crosscutting/abutting relationships with the NE-SW and NW-SE sets, together with the difficulty of framing them into the classical scenario of fracturing in foreland basin systems, has led to the development of different hypotheses about the timing of N-S and E-W sets. For the generation of these structures, both pre- and syn-thrusting interpretations have been proposed. In this work, we report on the occurrence of bed-perpendicular fracture sets in the upper part of the Shabazan (Eocene) and in the Asmari (Oligo-Miocene) Formations of the Zagros FTB. These fractures have the peculiarity of being filled with karst material. Such filled fractures are preserved in beds showing variable angles of dip, ranging from horizontal to vertical. Their homogeneous distribution in variably dipping beds around folds undoubtedly point to an origin of these fracture sets predating the tilting of the strata in which they are contained. Therefore, fracture development and related infilling occurred at an early stage, in still flat lying strata, following the deposition of the top Shabazan and Asmari Formations. Such a deposition took place within the general framework of ongoing shortening in the Zagros. This process, occurring since the Late Cretaceous, progressively led to folding of the syn-orogenic Shabazan and Asmari Formations subsequently to the development of the studied filled fractures.

  13. How the structural architecture of the Eurasian continental margin affects the structure, seismicity, and topography of the south central Taiwan fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Brown, Dennis; Alvarez-Marron, Joaquina; Biete, Cristina; Kuo-Chen, Hao; Camanni, Giovanni; Ho, Chun-Wei

    2017-07-01

    Studies of mountain belts worldwide show that along-strike changes are common in their foreland fold-and-thrust belts. These are typically caused by processes related to fault reactivation and/or fault focusing along changes in sedimentary sequences. The study of active orogens, like Taiwan, can also provide insights into how these processes influence transient features such as seismicity and topography. In this paper, we trace regional-scale features from the Eurasian continental margin in the Taiwan Strait into the south central Taiwan fold-and-thrust belt. We then present newly mapped surface geology, P wave velocity maps and sections, seismicity, and topography data to test the hypothesis of whether or not these regional-scale features of the margin are contributing to along-strike changes in structural style, and the distribution of seismicity and topography in this part of the Taiwan fold-and-thrust belt. These data show that the most important along-strike change takes place at the eastward prolongation of the upper part of the margin necking zone, where there is a causal link between fault reactivation, involvement of basement in the thrusting, concentration of seismicity, and the formation of high topography. On the area correlated with the necking zone, the strike-slip reactivation of east northeast striking extensional faults is causing sigmoidal offset of structures and topography along two main zones. Here basement is not involved in the thrusting; there is weak focusing of seismicity and localized development of topography. We also show that there are important differences in structure, seismicity, and topography between the margin shelf and its necking zone.

  14. Evolution of the Chos Malal and Agrio fold and thrust belts, Andes of Neuquén: Insights from structural analysis and apatite fission track dating

    NASA Astrophysics Data System (ADS)

    Rojas Vera, E. A.; Mescua, J.; Folguera, A.; Becker, T. P.; Sagripanti, L.; Fennell, L.; Orts, D.; Ramos, V. A.

    2015-12-01

    The Chos Malal and Agrio fold and thrust belts are located in the western part of the Neuquén basin, an Andean retroarc basin of central-western Argentina. Both belts show evidence of tectonic inversion at the western part during Late Cretaceous times. The eastern part is dominated by late Miocene deformation which also partially reactivated the western structures. This work focuses on the study of the regional structure and the deformational event that shaped the relief of this part of the Andes. Based on new field work and structural data and previously published works a detailed map of the central part of the Neuquén basin is presented. Three regional structural cross sections were surveyed and balanced using the 2d Move™ software. In order to define a more accurate uplift history, new apatite fission track analyses were carried on selected structures. These data was used for new thermal history modeling of the inner part of the Agrio and Chos Malal fold and thrust belts. The results of the fission track analyses improve the knowledge of how these fold and thrust belts have grown trough time. Two main deformational events are defined in Late Cretaceous to Paleocene and Late Miocene times. Based on this regional structural analysis and the fission track data the precise location of the orogenic front for the Late Cretaceous-Paleocene times is reconstructed and it is proposed a structural evolution of this segment of the Andes. This new exhumation data show how the Late Cretaceous to Paleocene event was a continuous and uninterrupted deformational event.

  15. Characterization of orogenic remagnetizations within various fold geometries in Carboniferous carbonates from thin skinned fold and thrust belts, SW Alberta and NW Montana

    NASA Astrophysics Data System (ADS)

    Zechmeister, M. S.; Elmore, R. D.; Ferre, E. C.; Pannalal, S. J.; Hamilton, E. M.

    2007-12-01

    Paleomagnetic and rock magnetic analysis was conducted on a complex fault propagation fold train in Kananaskis Country, Alberta to compliment an ongoing study of orogenic remagnetiztions in the thin-skinned, fold and thrust belt (NW Montana and SW Alberta). The complex structure is composed of an asymmetrical anticline to the west and chevron syncline to the east, with both folds plunging ~15° to the south. The fold train contains a magnetization with two stable ancient components. The characteristic remanent magnetization (ChRM) with northerly declinations and steep down inclinations is removed between ~350°C and the maximum unblocking temperature of 540°C. Tilt tests on the preliminary data reveal that the ChRM is early syntilting in the anticline and syntilting in the syncline. These results from this fold train are similar to a previous study in the Sawtooths (NW MT) which reported that fault propagation folds have a syntilting ChRM whereas fault bend folds contain a pretilting ChRM. An intermediate temperature reversed component is unblocked by 340°C and is late syntilting to post-tilting. Preliminary high-field rock magnetic data from folds in Montana and Alberta show that saturation is reached before 0.3T and the majority of the samples have wasp-waisted hysteresis loops. On a log plot of Mrs/Ms versus Hcr/Hc, the data has a power law distribution that is similar to trends reported by other authors. Interestingly though, samples from a fault bend fold have higher Mrs/Ms ratios than those measured in fault propagation folds, suggesting that strain induced by the various folding styles may influence the rock magnetic properties. Additional studies are underway to test these preliminary results and determine if the differences in the hysteresis ratios are significant. Petrographic analysis shows magnetite replacing pyrite in some samples suggesting an authigenic origin for the ChRM. The intensity of the ChRM as well as the strongest rock magnetic signal is

  16. A Method for Estimating 2D Horizontal Shortening at Wrinkle Ridges from Remote Sensing Data: Results from the Yakima Fold Belt (Columbia Plateau)

    NASA Astrophysics Data System (ADS)

    Mege, D.

    1999-03-01

    Field data and length/displacement scaling laws applied to the Yakima fold belt on the Columbia Plateau are used to demonstrate a method for estimating surface shortening of wrinkle ridge areas. Application to martian wrinkle ridges is given in another abstract.

  17. Geometry and kinematics of Majiatan Fold-and-thrust Belt, Western Ordos Basin: implication for Tectonic Evolution of North-South Tectonic Belt

    NASA Astrophysics Data System (ADS)

    He, D.

    2017-12-01

    The Helan-Chuandian North-South Tectonic Belt crossed the central Chinese mainland. It is a boundary of geological, geophysical, and geographic system of Chinese continent tectonics from shallow to deep, and a key zone for tectonic and geomorphologic inversion during Mesozoic to Cenozoic. It is superimposed by the southeastward and northeastward propagation of Qinghai-Tibet Plateau in late Cenozoic. It is thus the critical division for West and East China since Mesozoic. The Majiatan fold-and-thrust belt (MFTB), locating at the central part of HCNSTB and the western margin of Ordos Basin, is formed by the tectonic evolution of the Helan-Liupanshan Mountains. Based on the newly-acquired high-resolution seismic profiles, deep boreholes, and surface geology, the paper discusses the geometry, kinematics, and geodynamic evolution of MFTB. With the Upper Carboniferous coal measures and the pre-Sinian ductile zone as the detachments, MFTB is a multi-level detached thrust system. The thrusting was mainly during latest Jurassic to Late Cretaceous, breaking-forward in the foreland, and resulting in a shortening rate of 25-29%. By structural restoration, this area underwent extension in Middle Proterozoic to Paleozoic, which can be divided into three phases of rifting such as Middle to Late Proterozoic, Cambiran to Ordovician, and Caboniferous to early Permian. It underwent compression since Late Triassic, including such periods as Latest Triassic, Late Jurassic to early Cretaceous, Late Cretaceous to early Paleogene, and Pliocene to Quaternary, with the largest shortening around Late Jurassic to early Cretaceous period (i.e. the mid-Yanshanian movement by the local name). However, trans-extension since Eocene around the Ordos Basin got rise to the formation the Yingchuan, Hetao, and Weihe grabens. It is concluded that MFTB is the leading edge of the intra-continental Helan orogenic belt, and formed by multi-phase breaking-forward thrusting during Late Jurassic to Cretaceous

  18. The structural geometry and development of the central Appalachian fold-and thrust belt across the Pennsylvania salient: The effects of syntectonic loading

    NASA Astrophysics Data System (ADS)

    Evans, Mark

    2017-04-01

    The Pennsylvania salient is a classic arcuate fold-and-thrust belt that was deformed during the Late Paleozoic Alleghenian orogeny. 38 regional cross-sections with an along-strike spacing of 5 to 10 km were constructed, and show that the structural geometry varies significantly from the 030°-striking southwestern segment to 060°-striking northeastern segment. The primary competent lithotectonic unit is the 2 to 3 km thick Cambro-Ordovician carbonate sequence which is detached along a Cambrian clastic unit. The 5 to 7 km thick preserved Upper Paleozoic sequence is less homogeneous, and locally exhibits significant internal deformation. In the southwest part of the salient, the hinterland part of the fold belt is defined by a series of imbricated Cambro-Ordovician carbonate horses with leading-edge fault-propagation style folds that have a structural amplitude of 5 to 7 km. In the central part of the fold belt, the Broadtop synclinorium exhibits little to no imbrication of the Cambro-Ordovician unit, while in the western part of the belt toward the foreland, two additional carbonate horses with leading-edge fault-propagation style folds comprise the Wills Mt. anticlinorium. In the central and eastern parts of the salient, the structural geometry toward the foreland is defined by a duplex with 4 -5 imbricate horses of Cambro-Ordovician carbonates that transitions to an antiformal stack of two to three carbonate thrust sheets comprising the Nittany anticlinorium. Toward the hinterland, the Cambro-Ordovician carbonate sequence is faulted into broadly-spaced fault-related folds, and includes the regionally continuous (>160 km) Jacks Mt. - Berwick anticline that spans both limbs of the salient. Upon retrodeformation of the cross sections, the 060°-striking northeastern segment restoration path curves 25°-30° to the east, while the 030°-striking southwestern segment curves 20°-25° to the south. The major fault underlying the presently curved Jacks Mt. - Berwick

  19. The evolution of a Late Cretaceous-Cenozoic intraplate basin (Duaringa Basin), eastern Australia: evidence for the negative inversion of a pre-existing fold-thrust belt

    NASA Astrophysics Data System (ADS)

    Babaahmadi, Abbas; Sliwa, Renate; Esterle, Joan; Rosenbaum, Gideon

    2017-12-01

    The Duaringa Basin in eastern Australia is a Late Cretaceous?-early Cenozoic sedimentary basin that developed simultaneously with the opening of the Tasman and Coral Seas. The basin occurs on the top of an earlier (Permian-Triassic) fold-thrust belt, but the negative inversion of this fold-thrust belt, and its contribution to the development of the Duaringa Basin, are not well understood. Here, we present geophysical datasets, including recently surveyed 2D seismic reflection lines, aeromagnetic and Bouguer gravity data. These data provide new insights into the structural style in the Duaringa Basin, showing that the NNW-striking, NE-dipping, deep-seated Duaringa Fault is the main boundary fault that controlled sedimentation in the Duaringa Basin. The major activity of the Duaringa Fault is observed in the southern part of the basin, where it has undergone the highest amount of displacement, resulting in the deepest and oldest depocentre. The results reveal that the Duaringa Basin developed in response to the partial negative inversion of the pre-existing Permian-Triassic fold-thrust belt, which has similar orientation to the extensional faults. The Duaringa Fault is the negative inverted part of a single Triassic thrust, known as the Banana Thrust. Furthermore, small syn-depositional normal faults at the base of the basin likely developed due to the reactivation of pre-existing foliations, accommodation faults, and joints associated with Permian-Triassic folds. In contrast to equivalent offshore basins, the Duaringa Basin lacks a complex structural style and thick syn-rift sediments, possibly because of the weakening of extensional stresses away from the developing Tasman Sea.

  20. Neotectonic reactivation of the western section of the Malargüe fold and thrust belt (Tromen volcanic plateau, Southern Central Andes)

    NASA Astrophysics Data System (ADS)

    Sagripanti, Lucía; Rojas Vera, Emilio A.; Gianni, Guido M.; Folguera, Andrés; Harvey, Jonathan E.; Farías, Marcelo; Ramos, Victor A.

    2015-03-01

    This study examines the neotectonic deformation and development of the Tromen massif, a Quaternary retroarc volcanic field located in the western section of the Malargüe fold and thrust belt in the Southern Central Andes. The linkages between neotectonic deformation in the intra-arc zone and the recent retroarc structures of the Tromen volcanic plateau are not clearly understood. These retroarc deformations affect the mid-section of the fold and thrust belt, leaving to the east a 200 km-wide deformed zone that can be considered inactive over the last 12-10 Ma. This out-of-sequence deformation west of the orogenic front area has not been previously addressed in detail. In this study, exhaustive mapping is used to describe and discriminate structures with a neotectonic component from those fossilized by Pleistocene strata. Two balanced cross-sections are constructed showing the distribution of the youngest deformations and their relation to pre-Miocene structures. An important means for evaluating this is the morphometric and morphological analyses that allowed identification of perturbations in the fluvial network associated with active structures. In a broader perspective, neotectonic activity in the fold and thrust belt is discussed and inferred to be caused by local mechanical weakening of the retroarc zone, due to injection of asthenospheric material evidenced by magnetotelluric surveys. Thus, deformation imposed by the oblique convergence between South American and Nazca plates, while to the south being limited to the Liquiñe-Ofqui fault system that runs through the arc zone, in the retroarc area is located at the site of magmatic emplacement, presumably in association with a thermally weakened-upper crust. This control exemplifies the relationship that exists between surficial processes, magmatic emplacement and upper asthenospheric dynamics in the Southern Central Andes.

  1. Structural, micro-structural and kinematic analyses of channel flow in the Karmostaj salt diapir in the Zagros foreland folded belt, Fars province, Iran

    NASA Astrophysics Data System (ADS)

    Sarkarinejad, Khalil; Sarshar, Maryam Asadi; Adineh, Sadegh

    2018-02-01

    One of the main characteristic of the Zagros foreland fold-and-thrust belt and the Zagros foreland folded belt are wide distributions of surface extrusion from the Hormuz salt diapirs. This study examines the structure and kinematic of channel flow in the Karmostaj salt diapir in the southwestern part of the Zagros foreland folded belt. This diapir has reached the surface as a result of the channel flow mechanism and has extruded in the southern limb of the Kuh-Gach anticline which is an asymmetric décollement fold with convergence to the south. Structural and microstructural studies and quantitative finite strain (Rs) and kinematic vorticity number (Wk) analyses were carried out within this salt diapir and its namakier. This was in order to investigate the structural evolution in the salt diapiric system, the characteristics and mechanism of the salt flow and the distribution of flow regimes within the salt diapir and interaction of regional tectonics and salt diaprism. The extruded salt has developed a flow foliation sub-parallel to the remnant bedding recorded by different colors, a variety of internal folds including symmetrical and asymmetrical folds and interference fold patterns, shear zones, and boudins. These structures were used to analyze mechanisms and history of diapiric flow and extrusion. The microstructures, reveal various deformation mechanisms in various parts of salt diapir. The measurements of finite strain show that Rs values in the margin of salt diapir are higher than within its namakier which is consistent with the results of structural studies. Mean kinematic vorticity number (Wm) measured in steady state deformation of diapir and namakier is Wm = 0.45-0.48 ± 0.13. The estimated mean finite deformation (Wm) values indicate that 67.8% pure shear and 32.2% simple shear deformation were involved; the implications of which are discussed. The vorticity of flow indicates that in the early stage of growth, Poiseuille flow was the dominate

  2. Deformation evolution of Eastern Sichuan-Xuefeng fold-thrust belt in South China: Insights from analogue modelling

    NASA Astrophysics Data System (ADS)

    He, Wengang; Zhou, Jianxun; Yuan, Kang

    2018-04-01

    The Eastern Sichuan-Xuefeng fold-thrust belt (CXFTB) located in South China has received wide attention due to its distinctive deformation styles and close relationships with natural gas preservation, but its deformation evolution still remains controversial. In order to study further this issue, we designed three sets of analogue models. Based on the results of the models, we suggest that: 1) the deformation in the CXFTB may simultaneously initiate along two zones nearby the Dayong and Qiyueshan faults at ∼190 Ma, and then progressively propagate into the interiors of the Western Hunan-Hubei and Eastern Sichuan domains at ∼140-150 Ma, and finally reach the front of the Huayingshan fault at ∼120 Ma; 2) the difference in décollement depth is the main factor determining the patterns of folds in different domains of the CXFTB; and 3) the Eastern Sichuan domain may have a basement significantly different from those of the Western Sichuan and Western Hunan-Hubei domains.

  3. Deformation and kinematic evolution of the subsurface structures: Zagros foreland fold-and-thrust belt, northern Dezful Embayment, Iran

    NASA Astrophysics Data System (ADS)

    Sarkarinejad, Khalil; Pash, Raana Razavi; Motamedi, Hossein; Yazdani, Mohammad

    2018-06-01

    The Dezful Embayment is located in the foreland part of the Zagros fold-and-thrust belt. Structural style of folding and thrusting vary in the Dezful Embayment. In this study, balanced cross sections and subsurface data including 2D seismic profiles and wells data decoded structural style of the subsurface structures in the northern Dezful Embayment. Presence of the multiple décollement horizons is the main controlling factor of the structural style in this area. The subsurface anticlines have been formed between two main décollement horizons, which include the Miocene Gachsaran Formation as upper decollement and Permian Dashtak evaporites and Lower Cretaceous Garau shales as the middle décollement horizons. Geometry of the subsurface anticlines differs much vertically and horizontally. Growth strata indicate folding is started in Middle Miocene time in this region. Anticlines formed as open, wide and disharmonic structures. Active processes in the evolution of anticlines are limb rotation and hinge migration, which was resulted in increase of inhomogeneous shortening rate. More shortening rate indicates more structural relief in anticlines. These anticlines are formed as a detachment folds in initiation and then during their evolution converted to fault propagation fold and fault-bend fold. Final geometric shape of these anticlines depends on the geometry of thrusts propagation that formed in the forelimb.

  4. Quaternary Deformation Constrained by River Terraces across the Longmen Shan Fold-and-Thrust Belt, Eastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Jiang, D., Sr.; Ding, R.; Li, W.; Gomez, F. G.

    2017-12-01

    The Longmen Shan is known for both the steep topography and the absence of Cenozoic foreland deposition. The 2008 Wenchuan Mw 7.9 earthquake, which ruptured the thrust faults along the range front, inspires vigorous debates about topography origin and seismic hazard. Two end-member models, crustal shortening and lower crustal flow, have been proposed. However, both of them need further verification. The Minjiang river and the Qingyijiang river run through the middle and the southern Longmen Shan respectively, which make it possible to study the strain distribution by relict river terraces. Longitudinal profiles of river terraces were restored by detailed field survey, high-precision measurement, sediment dating and chemical analyses. Deformed fluvial terraces shows that most thrust faults are active in the late Quaternary, and crust shortening dominates the fold-and-thrust belt, but the strain distributions are quite different between the south and north segments. In the north, thrust slips are mainly accommodated along the range front, the crustal shortening rate is 1.4 to 2.0 mm/yr, and only 25% of crust shortening are absorbed by the foreland. In the south, thrust slips are distributed among the thrust belt, the crustal shortening rate is 2.9 to 4.6mm/yr, and up to 83% of crustal shortening are absorbed by the foreland. Compared with other margins of the Tibetan Plateau, the Longmen Shan has much narrower thrust belt and nappe. The Himalayas, the Karakoram and the Qilian Shan thrust nappes are about 3 to 5 times wider than the Longmen Shan. However, all of these belts have comparable elevations above their foreland, respectively. Comparable altitude difference distributed across a narrow belt makes a greater topographic relief in the Longmen Shan, where narrow thrust nappe exerts less tectonic loading on the footwall which doesn't favor the formation of foreland basin. Our research results favor the model of crustal shortening, and reveal that all basement

  5. Effect of decollement rheology and deformation rate on the structural development of fold thrust belts in sand box models and their implications for the Naga fold thrust belt (NE India)

    NASA Astrophysics Data System (ADS)

    Saha, B.; Dietl, C.

    2009-04-01

    Previous studies on decollement kinematics have shed light on the differing structures of fold thrust belt forming above lithologically different decollements, such as shales, carbonates and evaporites. Factors, affecting the decollement kinematics most are (1) rock rheology and (2) deformation rate. This study is intended to explain the deformation style of the Naga fold thrust belt (NFTB, NE India) with the aid of sand box modelling performed at a basal temperature of 50C and deformed at varying strain rates from 3*10-6 s-1 to 4*10-3 s-1. The models are made up (from bottom to top) of a 0.25 cm thick layer of temperature-sensitive PDMS (polydimethylsiloxane), overlain by 1.75 cm of alternating black and yellow sand. The basal PDMS layer simulates a shale decollement. Decollements in the NFTB are generally developed in the Barail Shale of Oligocene age at 50C (the depth of the Barail Shale is about 2 km and the prevailing geothermal gradient is 25C/km). The sand layers simulate the brittlely behaving sandstones which prevail in the NFTB. All of the models were subjected to 35% compression, as the NFTB experienced similar shortening. The varying deformation velocities were chosen to model differing decollement rheologies. PDMS simulates shale decollement, which is mobile when overpressured and undergoes compression. The rheology of PDMS changes considerably with the applied temperature and strain rate. PDMS, although generally regarded as Newtonian, does behave non-Newtonian at strain rates of 10-3 s-1. The relation between decollement pore fluid overpressure with that of model strain rate, the material rheology, scaled body forces, density of the decollement in nature can be expressed as: λ = 1- [ V ηmodel / f Hmodel ρnatureg Hnature σ*] where λ = coeifficient of pore fluid overpressure in the decollement, V = the deformation velocity with which the models are deforming, ηmodel= viscosity of the decollement material, f = the co efficient of overpressure, and

  6. Structure, paleogeographic inheritance, and deformation history of the southern Atlas foreland fold and thrust belt of Tunisia

    NASA Astrophysics Data System (ADS)

    SaïD, Aymen; Baby, Patrice; Chardon, Dominique; Ouali, Jamel

    2011-12-01

    Structural analysis of the southern Tunisian Atlas was carried out using field observation, seismic interpretation, and cross section balancing. It shows a mix of thick-skinned and thin-skinned tectonics with lateral variations in regional structural geometry and amounts of shortening controlled by NW-SE oblique ramps and tear faults. It confirms the role of the Late Triassic-Early Jurassic rifting inheritance in the structuring of the active foreland fold and thrust belt of the southern Tunisian Atlas, in particular in the development of NW-SE oblique structures such as the Gafsa fault. The Late Triassic-Early Jurassic structural pattern is characterized by a family of first-order NW-SE trending normal faults dipping to the east and by second-order E-W trending normal faults limiting a complex system of grabens and horsts. These faults have been inverted during two contractional tectonic events. The first event occurred between the middle Turonian and the late Maastrichtian and can be correlated with the onset of the convergence between Africa and Eurasia. The second event corresponding to the principal shortening tectonic event in the southern Atlas started in the Serravalian-Tortonian and is still active. During the Neogene, the southern Atlas foreland fold and thrust belt propagated on the evaporitic décollement level infilling the Late Triassic-Early Jurassic rift. The major Eocene "Atlas event," described in hinterland domains and in eastern Tunisia, did not deform significantly the southern Tunisian Atlas, which corresponded in this period to a backbulge broad depozone.

  7. Effect of Cohesion Uncertainty of Granular Materials on the Kinematics of Scaled Models of Fold-and-Thrust Belts

    NASA Astrophysics Data System (ADS)

    Nilfouroushan, F.; Pysklywec, R.; Cruden, S.

    2009-05-01

    Cohesionless or very low cohesion granular materials are widely used in analogue/physical models to simulate brittle rocks in the upper crust. Selection of materials with appropriate cohesion values in such models is important for the simulation of the dynamics of brittle rock deformation in nature. Uncertainties in the magnitude of cohesion (due to measurement errors, extrapolations at low normal stresses, or model setup) in laboratory experiments can possibly result in misinterpretation of the styles and mechanisms of deformation in natural fold-and thrust belts. We ran a series of 2-D numerical models to investigate systematically the effect of cohesion uncertainties on the evolution of models of fold-and-thrust belts. The analyses employ SOPALE, a geodynamic code based on the arbitrary Lagrangian-Eulerian (ALE) finite element method. Similar to analogue models, the material properties of sand and transparent silicone (PDMS) are used to simulate brittle and viscous behaviors of upper crustal rocks. The suite of scaled brittle and brittle-viscous numerical experiments have the same initial geometry but the cohesion value of the brittle layers is increased systematically from 0 to 100 Pa. The stress and strain distribution in different sets of models with different cohesion values are compared and analyzed. The kinematics and geometry of thrust wedges including the location and number of foreland- and hinterland- verging thrust faults, pop-up structures, tapers and topography are also explored and their sensitivity to cohesion value is discussed.

  8. Influence of pre-tectonic carbonate facies architecture on deformation patterns of syntectonic turbidites, an example from the central Mexican fold-thrust belt

    NASA Astrophysics Data System (ADS)

    Vásquez Serrano, Alberto; Tolson, Gustavo; Fitz Diaz, Elisa; Chávez Cabello, Gabriel

    2018-04-01

    The Mexican fold-thrust belt in central México excellently exposes relatively well preserved syntectonic deposits that overlay rocks with lateral lithostratigraphic changes across the belt. We consider the deformational effects of these changes by investigating the geometry, kinematics and strain distribution within syntectonic turbidites, which are deposited on top of Albian-Cenomanian shallow and deep water carbonate layers. Field observations and detailed structural analysis at different stratigraphic and structural levels of the Late Cretaceous syntectonic formation are compared with the deformation as a function of lithological and structural variations in the underlying carbonate units, to better understand the effect of these lithostratigraphic variations on deformation, kinematics, strain distribution and propagation of deformation. From our kinematic analyses, we conclude that the syntectonic strata are pervasively affected by folding in all areas and that deformation partitioning localized shear zones at the boundaries of this unit, particularly along the contact with massive carbonates. At the boundaries with massive platformal carbonates, the turbidites are strongly deformed by isoclinal folding with a pervasive sub-horizontal axial plane cleavage and 70-60% shortening. In contrast, contacts with thinly-bedded carbonate layers (basinal facies), do not show strain localization, and have horizontal shortening of 50-40% that is accommodated by buckle folds with a less pervasive, steeply dipping cleavage. The mechanical properties variations in the underlying pre-tectonic units as a function of changes in lithostratigraphy fundamentally control the deformation in the overlying syntectonic strata, which is an effect that could be expected to occur in any deformed sedimentary sequence with such variations.

  9. Frontal belt curvature and oblique ramp development at an obliquely collided irregular margin: Geometry and kinematics of the NW Taiwan fold-thrust belt

    NASA Astrophysics Data System (ADS)

    Lacombe, Olivier; Mouthereau, FréDéRic; Angelier, Jacques; Chu, Hao-Tsu; Lee, Jian-Cheng

    2003-06-01

    Combined structural and tectonic analyses demonstrate that the NW Foothills of the Taiwan collision belt constitute mainly an asymmetric "primary arc" type fold-thrust belt. The arcuate belt developed as a basin-controlled salient in the portion of the foreland basin that was initially thicker, due to the presence of a precollisional depocenter (the Taihsi basin). Additional but limited buttress effects at end points related to interaction with foreland basement highs (Kuanyin and Peikang highs) may have also slightly enhanced curvature. The complex structural pattern results from the interaction between low-angle thrusting related to shallow decollement tectonics and oblique inversion of extensional structures of the margin on the southern edge of the Kuanyin basement high. The tectonic regimes and mechanisms revealed by the pattern of paleostress indicators such as striated outcrop-scale faults are combined with the orientation and geometry of offshore and onshore regional faults in order to accurately define the Quaternary kinematics of the propagating units. The kinematics of this curved range is mainly controlled by distributed transpressional wrenching along the southern edge of the Kuanyin high, leading to the development of a regional-scale oblique ramp, the Kuanyin transfer fault zone, which is conjugate of the NW trending Pakua transfer fault zone north of the Peikang basement high. The divergence between the N120° regional transport direction and the maximum compressive trend that evolved from N120° to N150° (and even to N-S) in the northern part of the arc effectively supports distributed wrench deformation along its northern limb during the Pleistocene. The geometry and kinematics of the western Taiwan Foothills therefore appear to be highly influenced by both the preorogenic structural pattern of the irregularly shaped Chinese passive margin and the obliquity of its Plio-Quaternary collision with the Philippine Sea plate.

  10. 2-D traveltime and waveform inversion for improved seismic imaging: Naga Thrust and Fold Belt, India

    NASA Astrophysics Data System (ADS)

    Jaiswal, Priyank; Zelt, Colin A.; Bally, Albert W.; Dasgupta, Rahul

    2008-05-01

    Exploration along the Naga Thrust and Fold Belt in the Assam province of Northeast India encounters geological as well as logistic challenges. Drilling for hydrocarbons, traditionally guided by surface manifestations of the Naga thrust fault, faces additional challenges in the northeast where the thrust fault gradually deepens leaving subtle surface expressions. In such an area, multichannel 2-D seismic data were collected along a line perpendicular to the trend of the thrust belt. The data have a moderate signal-to-noise ratio and suffer from ground roll and other acquisition-related noise. In addition to data quality, the complex geology of the thrust belt limits the ability of conventional seismic processing to yield a reliable velocity model which in turn leads to poor subsurface image. In this paper, we demonstrate the application of traveltime and waveform inversion as supplements to conventional seismic imaging and interpretation processes. Both traveltime and waveform inversion utilize the first arrivals that are typically discarded during conventional seismic processing. As a first step, a smooth velocity model with long wavelength characteristics of the subsurface is estimated through inversion of the first-arrival traveltimes. This velocity model is then used to obtain a Kirchhoff pre-stack depth-migrated image which in turn is used for the interpretation of the fault. Waveform inversion is applied to the central part of the seismic line to a depth of ~1 km where the quality of the migrated image is poor. Waveform inversion is performed in the frequency domain over a series of iterations, proceeding from low to high frequency (11-19 Hz) using the velocity model from traveltime inversion as the starting model. In the end, the pre-stack depth-migrated image and the waveform inversion model are jointly interpreted. This study demonstrates that a combination of traveltime and waveform inversion with Kirchhoff pre-stack depth migration is a promising approach

  11. The thrust belt in Southwest Montana and east-central Idaho

    USGS Publications Warehouse

    Ruppel, Edward T.; Lopez, David A.

    1984-01-01

    The leading edge of the Cordilleran fold and thrust in southwest Montana appears to be a continuation of the edge of the Wyoming thrust belt, projected northward beneath the Snake River Plain. Trces of the thrust faults that form the leading edge of the thrust belts are mostly concealed, but stratigraphic and structural evidence suggests that the belt enters Montana near the middle of the Centennial Mountains, continues west along the Red Rock River valley, and swings north into the Highland Mountains near Butte. The thrust belt in southwest Montana and east-central Idaho includes at least two major plates -- the Medicine Lodge and Grasshopper thrust plates -- each of which contains a distinctive sequence of rocks, different in facies and structural style from those of the cratonic region east of the thrust belt. The thrust plates are characterized by persuasive, open to tight and locally overturned folds, and imbricate thrust faults, structural styles unusual in Phanerozoic cratonic rocks. The basal decollement zones of the plates are composed of intensely sheared, crushed, brecciated, and mylonitized rocks, the decollement at the base of the Medicine Lodge plate is as much as 300 meters thick. The Medicine Lodge and Grasshopper thrust plates are fringed on the east by a 10- to 50-kilometer-wide zone of tightly folded rocks cut by imbricate thrust fauls, a zone that forms the eastern margin of the thrust belt in southwest Montana. The frontal fold and thrust zone includes rocks that are similar to those of the craton, even though they differ in details of thickness, composition, or stratigraphic sequence. The zone is interpreted to be one of terminal folding and thrusting in cratonic rocks overridden by the major thrust plates from farther west. The cratonic rocks were drape-folded over rising basement blocks that formed a foreland bulge in front of the thrust belt. The basement blocks are bounded by steep faults of Proterozoic ancestry, which also moved as tear

  12. Tok-Algoma magmatic complex of the Selenga-Stanovoi Superterrain in the Central Asian fold belt: Age and tectonic setting

    NASA Astrophysics Data System (ADS)

    Kotov, A. B.; Larin, A. M.; Salnikova, E. B.; Velikoslavinskii, S. D.; Sorokin, A. A.; Sorokin, A. P.; Yakovleva, S. Z.; Anisimova, I. V.; Tolmacheva, E. V.

    2012-05-01

    According to the results of U-Pb geochronological investigations, the hornblende subalkali diorite rocks making up the Tok-Algoma Complex in the eastern part of the Selenga-Stanovoi Superterrain of the Central Asian fold belt were formed in the Middle Jurassic rather than in the Middle Archean as was suggested previously. Thus, the age of the regional amphibolite facies metamorphism manifested itself in the Ust'-Gilyui rock sequence of the Stanovoi Complex and that superimposed on granitoids of the Tok-Algoma Complex is Mesozoic rather than Early Precambrian. The geochemical features of the Tok-Algoma granitoids are indicative of the fact that they were formed in the geodynamic setting of the active continental margin or a mature island arc. Hence, it is possible to suggest that the subduction processes along the southern boundary between the Selenga-Stanovoi Superterrain and the Mongolian-Okhotsk ocean basin in the Middle Jurassic resulted in the formation of a magmatic belt of over 500 km in length.

  13. Petroleum generation and migration in the Mesopotamian Basin and Zagros fold belt of Iraq: Results from a basin-modeling study

    USGS Publications Warehouse

    Pitman, Janet K.; Steinshouer, D.; Lewan, M.D.

    2004-01-01

    A regional 3-D total petroleum-system model was developed to evaluate petroleum generation and migration histories in the Mesopotamian Basin and Zagros fold belt in Iraq. The modeling was undertaken in conjunction with Middle East petroleum assessment studies conducted by the USGS. Regional structure maps, isopach and facies maps, and thermal maturity data were used as input to the model. The oil-generation potential of Jurassic source-rocks, the principal known source of the petroleum in Jurassic, Cretaceous, and Tertiary reservoirs in these regions, was modeled using hydrous pyrolysis (Type II-S) kerogen kinetics. Results showed that oil generation in source rocks commenced in the Late Cretaceous in intrashelf basins, peak expulsion took place in the late Miocene and Pliocene when these depocenters had expanded along the Zagros foredeep trend, and generation ended in the Holocene when deposition in the foredeep ceased. The model indicates that, at present, the majority of Jurassic source rocks in Iraq have reached or exceeded peak oil generation and most rocks have completed oil generation and expulsion. Flow-path simulations demonstrate that virtually all oil and gas fields in the Mesopotamian Basin and Zagros fold belt overlie mature Jurassic source rocks (vertical migration dominated) and are situated on, or close to, modeled migration pathways. Fields closest to modeled pathways associated with source rocks in local intrashelf basins were charged earliest from Late Cretaceous through the middle Miocene, and other fields filled later when compression-related traps were being formed. Model results confirm petroleum migration along major, northwest-trending folds and faults, and oil migration loss at the surface.

  14. Role of tectonic inheritance in the instauration of Tunisian Atlassic fold-and-thrust belt: Case of Bouhedma - Boudouaou structures

    NASA Astrophysics Data System (ADS)

    Ghanmi, Mohamed Abdelhamid; Ghanmi, Mohamed; Aridhi, Sabri; Ben Salem, Mohamed Sadok; Zargouni, Fouad

    2016-07-01

    Tectonic inversion in the Bouhedma-Boudouaou Mountains was investigated through recent field work and seismic lines interpretation calibrated with petroleum well data. Located to the Central-Southern Atlas of Tunisia, this area signed shortened intra-continental fold-and-thrust belts. Two dissymmetric anticlines characterize Bouhedma - Boudouaou major fold. These structures show a strong virgation respectively from E-W to NNE-SSW as a response to the interference between both tectonic inversion and tectonic inheritance. This complex geometry is driven by Mesozoic rifting, which marked an extensional inherited regime. A set of late Triassic-Early Jurassic E-W and NW-SE normal faults dipping respectively to the North and to the East seems to widely affect the overall geodynamic evolution of this domain. They result in major thickness changes across the hanging wall and the footwall blocks in response with the rifting activity. Tectonic inversion is inferred from convergence between African and European plates since late Cretaceous. During Serravalian - Tortonian event, NW-SE trending paroxysm led to: 1) folding of pre-inversion and syn-inversion strata, 2) reactivation of pre-existing normal faults to reverse ones and 3) orogeny of the main structures with NE-SW and E-W trending. The compressional feature still remains active during Quaternary event (Post-Villafranchian) with N-S trending compression. Contraction during inversion generates folding and internal deformation as well as Fault-Propagation-Fold and folding related strike.

  15. Health concepts, issues, and experience in the Abakaliki area, Nigeria.

    PubMed Central

    Chukwuma, C

    1994-01-01

    Environmental health problems are increasingly receiving global attention. The health of entire nations may not only be affected by adverse environmental conditions, but by nutritional deficiencies that lead to morbidity and mortality. The type and extent of adverse health effects in a population depend on the potential for exposure to some environmental factors and pathogens as well as other environmental variables like industrialization, sanitation conditions, and urbanization. National and international comparisons between health status indicators can reveal the extent of any differences that exist, including dynamic changes in prevailing environmental conditions which may be helpful in characterizing the role of specific risk factors. Improvements in collection of environmental data related to health can help to identify, control, and eliminate many of the factors that are associated with environmental risk in the Abakaliki area of eastern Nigeria. PMID:9644193

  16. The Ross Orogen and Lachlan Fold Belt in Marie Byrd Land, Northern Victoria Land and New Zealand: implication for the tectonic setting of the Lachlan Fold Belt in Antarctica

    USGS Publications Warehouse

    Bradshaw, J.D.

    2007-01-01

    Correlation of the Cambrian Delamerian Orogen of Australia and Ross Orogen of the Transantarctic Mountains widely accepted but the extension of the adjacent Lachlan Orogen into Antarctica is controversial. Outside the main Ross-Delamerian belt, evidence of this orogeny is preserved at Mt Murphy in Marie Byrd Land and the in Takaka Terrane of New Zealand. In all pre-break- configurations of the SW Pacific, these two areas are far removed from the Ross-Delamerian belt. Evidence from conglomerates in the Takaka Terrane, however, shows that in Late Cambrian times it was adjacent to the Ross Orogen. This indicates major tectonic displacements within Gondwana after the Cambrian and before break-up. The Lachlan Orogen formed in an extensional belt in a supra-subduction zone setting and the Cambrian rocks of Marie Byrd Land and New Zealand are interpreted as parts of a rifted continental ribbon on the outboard side of the Lachlan belt.

  17. Connecting the Yakima fold and thrust belt to active faults in the Puget Lowland, Washington

    USGS Publications Warehouse

    Blakely, R.J.; Sherrod, B.L.; Weaver, C.S.; Wells, R.E.; Rohay, A.C.; Barnett, E.A.; Knepprath, N.E.

    2011-01-01

    High-resolution aeromagnetic surveys of the Cascade Range and Yakima fold and thrust belt (YFTB), Washington, provide insights on tectonic connections between forearc and back-arc regions of the Cascadia convergent margin. Magnetic surveys were measured at a nominal altitude of 250 m above terrain and along flight lines spaced 400 m apart. Upper crustal rocks in this region have diverse magnetic properties, ranging from highly magnetic rocks of the Miocene Columbia River Basalt Group to weakly magnetic sedimentary rocks of various ages. These distinctive magnetic properties permit mapping of important faults and folds from exposures to covered areas. Magnetic lineaments correspond with mapped Quaternary faults and with scarps identified in lidar (light detection and ranging) topographic data and aerial photography. A two-dimensional model of the northwest striking Umtanum Ridge fault zone, based on magnetic and gravity data and constrained by geologic mapping and three deep wells, suggests that thrust faults extend through the Tertiary section and into underlying pre-Tertiary basement. Excavation of two trenches across a prominent scarp at the base of Umtanum Ridge uncovered evidence for bending moment faulting possibly caused by a blind thrust. Using aeromagnetic, gravity, and paleoseismic evidence, we postulate possible tectonic connections between the YFTB in eastern Washington and active faults of the Puget Lowland. We suggest that faults and folds of Umtanum Ridge extend northwestward through the Cascade Range and merge with the Southern Whidbey Island and Seattle faults near Snoqualmie Pass 35 km east of Seattle. Recent earthquakes (MW ≤ 5.3) suggest that this confluence of faults may be seismically active today.

  18. Fault-controlled pluton emplacement in the Sevier fold-and-thrust belt of southwest Montana, USA

    NASA Astrophysics Data System (ADS)

    Kalakay, Thomas J.; John, Barbara E.; Lageson, David R.

    2001-06-01

    Problems associated with syncompressional pluton emplacement center on the need to make room for magma in environments where crustal shortening, not extension, occurs on a regional scale. New structural data from the Pioneer and Boulder batholiths of southwest Montana, USA, suggest emplacement at the top of frontal thrust ramps as composite tabular bodies at crustal depths between 1 and 10 km. Frontal thrust facilitated pluton emplacement was accommodated by: (1) a magma feeder zone created along the ramp interface; (2) providing 'releasing steps' at ramp tops that serve as initial points of emplacement and subsequent pluton growth; and (3) localizing antithetic back-thrusts that assist in pluton ascent. A model of magma emplacement is proposed that involves these elements. This model for syntectonic ramp-top emplacement of plutons helps explain how space is made for plutons within fold-and-thrust belts.

  19. Prevalence of malaria parasitaemia and malaria related anaemia among pregnant women in Abakaliki, South East Nigeria.

    PubMed

    Nwonwu, E U; Ibekwe, P C; Ugwu, J I; Obarezi, H C; Nwagbara, O C

    2009-06-01

    Malaria currently is regarded as the most common and potentially the most serious infection occurring in pregnancy in many sub Saharan African countries. This study was undertaken to evaluate the prevalence of malaria parasitaemia and malaria related anaemia among pregnant women in Abakaliki, South East, Nigeria. This is a cross sectional, descriptive study conducted in two tertiary health institutions in Abakaliki, South East, Nigeria (Ebonyi State University Teaching Hospital And Federal Medical Centre). Using systematic sampling method, 193 pregnant women were selected from the health institutions for the study. Their blood were analysed for haemoglobin status and malaria parasite. Data were also collected using an interviewer administered questionnaire. All the data were analysed using Epi info version 6 statistical software. Response rate was 100%. Twenty nine percent prevalence of malaria parasitaemia was detected, more common among primigravidae. Women with higher parity had higher frequency of anaemia in pregnancy. More than half of the pregnant women (51%) were in their second trimester at the time of booking. There was no case of severe anaemia requiring blood transfusion. Our pregnant women register late for antenatal care. Prevalence of malaria parasitaemia is high in our environment as well as anaemia in pregnancy, using the standard WHO definition. It is suggested that effort should be intensified to make our women register early for antenatal care in order to identify complications early. Intermittent preventive treatment for malaria should be incorporated into routine drugs for antenatal women.

  20. Structural analysis of hanging wall and footwall blocks within the Río Guanajibo fold-and-thrust belt in Southwest Puerto Rico

    NASA Astrophysics Data System (ADS)

    Laó-Dávila, Daniel A.; Llerandi-Román, Pablo A.

    2017-01-01

    The Río Guanajibo fold-and-thrust belt (RGFT), composed of Cretaceous serpentinite and volcano-sedimentary rocks, represents the deformation front of a contractional event in SW Puerto Rico during the Paleogene. Previous studies inferred structural and stratigraphic relationships from poorly exposed outcrops. New road cuts exposed the Yauco (YF) and El Rayo Formations (ERF) providing insights on the deformation of the hanging wall and footwall. We described the nature and orientation of faults and folds and analyzed the kinematic indicators to characterize the deformation. The YF occurs in the hanging wall and shows a sequence of folded, medium-bedded mudstone and thinly bedded shale and sandstone. Major folds strike NW-SE and are gentle with steeply inclined axial planes and sub-horizontal fold axes. Minor folds are open with moderately inclined axial planes and gently to moderately inclined SE-plunging fold axes. NW-SE striking reverse and thrust faults cut layers and show movement to the SW. Steep left-lateral faults strike NW-SE and NE-SW, and smaller right-lateral strike-slip faults strike NNE-SSW. At the footwall, the ERF consists of bioclastic limestone and polymictic orthoconglomerates and paraconglomerates. Reverse and strike-slip faults cut along lithological contacts. Results suggest that the hanging wall and footwall accommodated strain along preexisting weaknesses, which are dependent on lithology and sedimentary structures. The kinematic analysis suggests that shortening in the NE-SW direction was partitioned between folding and interlayer shortening, accommodated by flexural slip, and reverse and left-lateral faults that resulted from contraction. The RGFT represents the Paleogene back arc deformation of a bivergent thrust system.

  1. Modelling the role of basement block rotation and strike-slip faulting on structural pattern in the cover units of fold-and-thrust belts

    NASA Astrophysics Data System (ADS)

    Koyi, Hemin; Nilfouroushan, Faramarz; Hessami, Khaled

    2015-04-01

    A series of scaled analogue models are run to study the degree of coupling between basement block kinematics and cover deformation. In these models, rigid basal blocks were rotated about vertical axis in a "bookshelf" fashion, which caused strike-slip faulting along the blocks and, to some degrees, in the overlying cover units of loose sand. Three different combinations of cover basement deformations are modeled; cover shortening prior to basement fault movement; basement fault movement prior to shortening of cover units; and simultaneous cover shortening with basement fault movement. Model results show that the effect of basement strike-slip faults depends on the timing of their reactivation during the orogenic process. Pre- and syn-orogen basement strike-slip faults have a significant impact on the structural pattern of the cover units, whereas post-orogenic basement strike-slip faults have less influence on the thickened hinterland of the overlying fold-and-thrust belt. The interaction of basement faulting and cover shortening results in formation of rhomb features. In models with pre- and syn-orogen basement strike-slip faults, rhomb-shaped cover blocks develop as a result of shortening of the overlying cover during basement strike-slip faulting. These rhombic blocks, which have resemblance to flower structures, differ in kinematics, genesis and structural extent. They are bounded by strike-slip faults on two opposite sides and thrusts on the other two sides. In the models, rhomb-shaped cover blocks develop as a result of shortening of the overlying cover during basement strke-slip faulting. Such rhomb features are recognized in the Alborz and Zagros fold-and-thrust belts where cover units are shortened simultaneously with strike-slip faulting in the basement. Model results are also compared with geodetic results obtained from combination of all available GPS velocities in the Zagros and Alborz FTBs. Geodetic results indicate domains of clockwise and

  2. Contemporary deformation in the Yakima fold and thrust belt estimated with GPS

    NASA Astrophysics Data System (ADS)

    McCaffrey, Robert; King, Robert W.; Wells, Ray E.; Lancaster, Matthew; Miller, M. Meghan

    2016-10-01

    Geodetic, geologic and palaeomagnetic data reveal that Oregon (western USA) rotates clockwise at 0.3 to 1.0° Ma-1 (relative to North America) about an axis near the Idaho-Oregon-Washington border, while northeast Washington is relatively fixed. This rotation has been going on for at least 15 Ma. The Yakima fold and thrust belt (YFTB) forms the boundary between northern Oregon and central Washington where convergence of the clockwise-rotating Oregon block is apparently accommodated. North-south shortening across the YFTB has been thought to occur in a fan-like manner, increasing in rate to the west. We obtained high-accuracy, high-density geodetic GPS measurements in 2012-2014 that are used with earlier GPS measurements from the 1990s to characterize YFTB kinematics. The new results show that the deformation associated with the YFTB starts at the Blue Mountains Anticline in northern Oregon and extends north beyond the Frenchman Hills in Washington, past the epicentre of the 1872 Mw 7.0 Entiat earthquake to 49°N. The north-south strain rate across the region is 2 to 3 × 10-9 yr-1 between the volcanic arc and the eastern edge of the YFTB (241.0°E); east of there it drops to about 10-9 yr-1. At the eastern boundary of the YFTB, faults and earthquake activity are truncated by a north-trending, narrow zone of deformation that runs along the Pasco Basin and Moses Lake regions near 240.9°E. This zone, abutting the Department of Energy Hanford Nuclear Reservation, accommodates about 0.5 mm yr-1 of east to northeast shortening. A similar zone of N-trending transpression is seen along 239.9°E where there is a change in the strike of the Yakima folds. The modern deformation of the YFTB is about 600 km wide from south to north and internally may be controlled by pre-existing crustal structure.

  3. Contemporary deformation in the Yakima fold and thrust belt estimated with GPS

    USGS Publications Warehouse

    McCaffrey, Robert; King, Robert W.; Wells, Ray; Lancaster, Matthew; Miller, M. Meghan

    2016-01-01

    Geodetic, geologic and palaeomagnetic data reveal that Oregon (western USA) rotates clockwise at 0.3 to 1.0° Ma−1 (relative to North America) about an axis near the Idaho–Oregon–Washington border, while northeast Washington is relatively fixed. This rotation has been going on for at least 15 Ma. The Yakima fold and thrust belt (YFTB) forms the boundary between northern Oregon and central Washington where convergence of the clockwise-rotating Oregon block is apparently accommodated. North–south shortening across the YFTB has been thought to occur in a fan-like manner, increasing in rate to the west. We obtained high-accuracy, high-density geodetic GPS measurements in 2012–2014 that are used with earlier GPS measurements from the 1990s to characterize YFTB kinematics. The new results show that the deformation associated with the YFTB starts at the Blue Mountains Anticline in northern Oregon and extends north beyond the Frenchman Hills in Washington, past the epicentre of the 1872 Mw 7.0 Entiat earthquake to 49°N. The north–south strain rate across the region is 2 to 3 × 10−9 yr−1 between the volcanic arc and the eastern edge of the YFTB (241.0°E); east of there it drops to about 10−9 yr−1. At the eastern boundary of the YFTB, faults and earthquake activity are truncated by a north-trending, narrow zone of deformation that runs along the Pasco Basin and Moses Lake regions near 240.9°E. This zone, abutting the Department of Energy Hanford Nuclear Reservation, accommodates about 0.5 mm yr−1 of east to northeast shortening. A similar zone of N-trending transpression is seen along 239.9°E where there is a change in the strike of the Yakima folds. The modern deformation of the YFTB is about 600 km wide from south to north and internally may be controlled by pre-existing crustal structure.

  4. Earthquakes, geodesy, and the structure of mountain belts

    NASA Astrophysics Data System (ADS)

    Allen, Mark; Walters, Richard; Nissen, Ed

    2015-04-01

    Most terrestrial mountain belts are the topographic expression of thrust faulting and folding, which are how the continents deform in compression. Fold-and-thrust belts are therefore a global phenomenon, in existence since at least the onset of plate tectonics. They are typically described as wedge-shaped zones of deformation, overlying a basal low-angle thrust fault (≤10o dip). Here we use earthquake focal mechanisms and geodetic data from active continental fold-and-thrust belts worldwide, to test these concepts. We find that widespread, seismogenic, low-angle thrusting at the base of a wedge occurs only in the Himalayas, New Guinea, Talesh and far-eastern Zagros, which are plausibly underthrust by strong plates. In other ranges there is no focal mechanism evidence for a basal low-angle thrust, and well-constrained hypocentre depths are typically <20 km. Available geodetic data show that active deformation is focussed on a single, low-angle thrust in the Himalayas and New Guinea, but distributed in other ranges for which there are sufficient observations. We suggest that the more common style of deformation approximates to pure shear, with a brittle lid overlying the rest of the plate, where ductile or plastic deformation predominates. Interpretations of both active and ancient mountain belts will need re-evaluation in the light of these results.

  5. Eocene Total Petroleum System -- North and East of the Eocene West Side Fold Belt Assessment Unit of the San Joaquin Basin Province: Chapter 19 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

    USGS Publications Warehouse

    Gautier, Donald L.; Hosford Scheirer, Allegra

    2009-01-01

    The North and East of Eocene West Side Fold Belt Assessment Unit (AU) of the Eocene Total Petroleum System of the San Joaquin Basin Province comprises all hydrocarbon accumulations within the geographic and stratigraphic limits of this confirmed AU. Oil and associated gas accumulations occur in Paleocene through early middle Miocene marine to nonmarine sandstones found on the comparatively stable northeast shelf of the basin. The assessment unit is located north and east of the thickest accumulation of Neogene sediments and the west side fold belt. The area enclosed by the AU has been affected by only mild deformation since Eocene time. Traps containing known accumulations are mostly low-relief domes, anticlines, and up-dip basin margin traps with faulting and stratigraphic components. Map boundaries of the assessment unit are shown in figures 19.1 and 19.2; this assessment unit replaces the Northeast Shelf of Neogene Basin play 1006, the East Central Basin and Slope North of Bakersfield Arch play 1010, and part of the West Side Fold Belt Sourced by Pre-middle Miocene Rocks play 1005 considered by the U.S. Geological Survey (USGS) in their 1995 National Assessment (Beyer, 1996). Stratigraphically, the AU includes rocks from the uppermost crystalline basement to the topographic surface. In the region of overlap with the Central Basin Monterey Diagenetic Traps Assessment Unit, the North and East of Eocene West Side Fold Belt AU extends from basement rocks to the top of the Temblor Formation (figs. 19.3 and 19.4). In map view, the northern boundary of the assessment unit corresponds to the northernmost extent of Eocene-age Kreyenhagen Formation. The northeast boundary is the eastern limit of possible oil reservoir rocks near the eastern edge of the basin. The southeast boundary corresponds to the pinch-out of Stevens sand of Eckis (1940) to the south, which approximately coincides with the northern flank of the Bakersfield Arch (fig. 19.1). The AU is bounded on the

  6. Neogene shortening and exhumation of the Zagros fold-thrust belt and foreland basin in the Kurdistan region of northern Iraq

    NASA Astrophysics Data System (ADS)

    Koshnaw, Renas I.; Horton, Brian K.; Stockli, Daniel F.; Barber, Douglas E.; Tamar-Agha, Mazin Y.; Kendall, Jerome J.

    2017-01-01

    The Zagros fold-thrust belt in the Kurdistan region of Iraq encroached southward toward a rapidly subsiding Neogene foreland basin and was later partitioned by out-of-sequence shortening focused along the Mountain Front Flexure (MFF), as defined by new low-temperature thermochronologic, stratigraphic, and provenance results. Apatite (U-Th)/He ages document rapid deformation advance from the Main Zagros Fault to southern frontal structures (Kirkuk, Shakal, and Qamar thrusts) at 10-8 Ma, followed by potential basement-involved out-of-sequence development of the MFF (Qaradagh anticline) by 5 Ma. Distinct shifts in detrital zircon U-Pb provenance signatures for Neogene foreland basin fill provide evidence for drainage reorganization during fold-thrust belt advance. U-Pb age spectra and petrologic data from the Injana (Upper Fars) Formation indicate derivation from a variety of Eurasian, Pan-African, ophiolitic and Mesozoic-Cenozoic volcanic terranes, whereas the Mukdadiya (Lower Bakhtiari) and Bai-Hasan (Upper Bakhtiari) Formations show nearly exclusive derivation from the Paleogene Walash-Naopurdan volcanic complex near the Iraq-Iran border. Such a sharp cutoff in Eurasian, Pan-African, and ophiolitic sources is likely associated with drainage reorganization and tectonic development of the geomorphic barrier formed by the MFF. As a result of Zagros crustal shortening, thickening and loading, the Neogene foreland basin developed and accommodated an abrupt influx of fluvial clastic sediment that contains growth stratal evidence of synkinematic accumulation. The apparent out-of-sequence pattern of upper crustal shortening in the hinterland to foreland zone of Iraqi Kurdistan suggests that structural inheritance and the effects of synorogenic erosion and accumulation are important factors influencing the irregular and episodic nature of orogenic growth in the Zagros.

  7. Application of High Resolution Topography and Remote Sensing: Imagery to the Kinematics of Fold-and-Thrust Belts

    NASA Technical Reports Server (NTRS)

    Rubin, Charles

    1997-01-01

    This report summarizes one year of funding for NASA contract NAGW-3691, Application of High Resolution Topography and Remote Sensing: Imagery to the Kinematics of Fold-and-Thrust Belts. I never received year three from NASA. The funds were to support on going tectonic and topographic studies along the front of the central Transverse Ranges and expand the topographic studies to the north. Below are results from the first two years of actual funds that I received from NASA (see attached Federal Cash Transaction Reports). The main focus of this contract was to define and understand the major tectonic processes affecting the formation and evolution of the topography in convergent tectonic settings. The results will be used to test ongoing space-based geodetic measurements and will be compared with present-day seismicity in the central Transverse Ranges and adjacent basins. Two major factors that controls topography in active regions are (1) tectonic uplift due to fault-normal compression and (2) subsequent erosion. The central Transverse and Temblor Ranges are excellent regions for these focused topographic studies. The tectonic processes leading to the mountain building are relatively straightforward and thus are easy to model. Available evidence suggests that the topography in this region is relatively young, - 3.5 Ma or less. In addition,, erosional processes may be relatively easier to model compared to larger and more ancient mountain belts. For example, in larger mountain belts, topographic relief may cause significant orographic effects and high elevation may result in part of the topography located above snowline. Both factors complicate interpretation of erosional processes that may be controlled by elevation. Mountain ranges that are significantly older may have experienced a much wider variety of erosional or climatic conditions over their lifetime. While erosion rates have certainly not been consistent in the Transverse or Temblor ranges over its 3.5 Ma

  8. Effect of basement structure and salt tectonics on deformation styles along strike: An example from the Kuqa fold-thrust belt, West China

    NASA Astrophysics Data System (ADS)

    Neng, Yuan; Xie, Huiwen; Yin, Hongwei; Li, Yong; Wang, Wei

    2018-04-01

    The Kuqa fold-thrust belt (KFTB) has a complex thrust-system geometry and comprises basement-involved thrusts, décollement thrusts, triangle zones, strike-slip faults, transpressional faults, and pop-up structures. These structures, combined with the effects of Paleogene salt tectonics and Paleozoic basement uplift form a complex structural zone trending E-W. Interpretation and comprehensive analysis of recent high-quality seismic data, field observations, boreholes, and gravity data covering the KFTB has been performed to understand the characteristics and mechanisms of the deformation styles along strike. Regional sections, fold-thrust system maps of the surface and the sub-salt layer, salt and basement structure distribution maps have been created, and a comprehensive analysis of thrust systems performed. The results indicate that the thrust-fold system in Paleogene salt range can be divided into five segments from east to west: the Kela-3, Keshen, Dabei, Bozi, and Awate segments. In the easternmost and westernmost parts of the Paleogene salt range, strike-slip faulting and basement-involved thrusting are the dominant deformation styles, as basement uplift and the limits of the Cenozoic evaporite deposit are the main controls on deformation. Salt-core detachment fold-thrust systems coincide with areas of salt tectonics, and pop-up, imbricate, and duplex structures are associated with the main thrust faults in the sub-salt layer. Distribution maps of thrust systems, basement structures, and salt tectonics show that Paleozoic basement uplift controlled the Paleozoic foreland basin morphology and the distribution of Cenozoic salt in the KFTB, and thus had a strong influence on the segmented structural deformation and evolution of the fold-thrust belt. Three types of transfer zone are identified, based on the characteristics of the salt layer and basement uplift, and the effects of these zones on the fault systems are evaluated. Basement uplift and the boundary of

  9. The Lamu Basin deepwater fold-and-thrust belt: An example of a margin-scale, gravity-driven thrust belt along the continental passive margin of East Africa

    NASA Astrophysics Data System (ADS)

    Cruciani, Francesco; Barchi, Massimiliano R.

    2016-03-01

    In recent decades, advances in seismic processing and acquisition of new data sets have revealed the presence of many deepwater fold-and-thrust belts (DW-FTBs), often developing along continental passive margins. These kinds of tectonic features have been intensively studied, due to their substantial interest. This work presents a regional-scale study of the poorly explored Lamu Basin DW-FTB, a margin-scale, gravity-driven system extending for more than 450 km along the continental passive margin of Kenya and southern Somalia (East Africa). A 2-D seismic data set was analyzed, consisting of both recently acquired high-quality data and old reprocessed seismic profiles, for the first detailed structural and stratigraphic interpretation of this DW-FTB. The system originated over an Early to mid-Cretaceous shale detachment due to a mainly gravity-spreading mechanism. Analysis of synkinematic strata indicates that the DW-FTB was active from the Late Cretaceous to the Early Miocene, but almost all of the deformation occurred before the Late Paleocene. The fold-and-thrust system displays a marked N-S variation in width, the northern portion being more than 150 km wide and the southern portion only a few dozen kilometers wide; this along-strike variation is thought to be related to the complex tectonosedimentary evolution of the continental margin at the Somalia-Kenya boundary, also reflected in the present-day bathymetry. Locally, a series of volcanic edifices stopped the basinward propagation of the DW-FTB. A landward change in the dominant structural style, from asymmetric imbricate thrust sheets to pseudo-symmetric detachment folds, is generally observed, related to the landward thickening of the detached shales.

  10. Impact of an interbedded viscous décollement on the structural and kinematic coupling in fold-and-thrust belts: Insights from analogue modeling

    NASA Astrophysics Data System (ADS)

    Borderie, Sandra; Graveleau, Fabien; Witt, César; Vendeville, Bruno C.

    2018-01-01

    Fold-and-thrust belts (FTBs) can be segmented both across and along strike because of various factors including tectonic and stratigraphic inheritance. In this study, we investigated along/across-strike structural interactions in a FTB propagating toward a foreland which displays contrasted lithological sequences. A set of analogue models was performed in a compressional box where a single viscous level of varying width was interbedded within a frictional series. The tectonic interaction between the viscous and the frictional provinces was tested both along and across strike. Results indicate that a frictional province influences the along-strike tectonic evolution of an adjacent viscous province. This influence decreases when the width of the viscous province increases. The frictional provinces control the taper, structural style, obliquity of the structures' trend and kinematics of the shallow deformation front of the viscous province. Results evidence how far a frictional province can impact the deformation of an adjacent viscous province. For frictional-viscous wedges, it appears that the critical taper theory, which is generally applied in 2-D, should be likely considered in terms of 3-D. Moreover, the kinematics of the deep deformation front shows mutual influences between the adjacent viscous and frictional provinces. Experimental results are compared to natural examples in the Kuqa Basin (Southern Tian Shan, China) and the Salt Range (Pakistan), and give an insight to a better understanding of the dynamics of fold-and-thrust belts bearing a viscous décollement, such as salt.

  11. Geochemistry and field geology of shoshonitic magmas in the Late Cretaceous foreland fold and thrust belt of southwestern Montana: Results from the North Doherty Mountain Intrusive Complex

    NASA Astrophysics Data System (ADS)

    Beranek, L. P.; Burton, B. R.; Ihinger, P. D.

    2002-12-01

    The North Doherty Mountain Intrusive Complex (NDMIC) is one of several satellite plutons related to the areally extensive Boulder batholith of southwestern Montana. The Boulder batholith comprises multiple plutons and intrusive phases, and the magmatism has long been thought to be the result of subduction due to its calc-alkaline granodioritic composition. The batholith is situated in the Helena salient, which differs from other parts of the North American Cordilleran foreland because there, magmatism spatially and temporally overlaps with deformation in the foreland fold and thrust belt. The North Doherty Mountain Intrusive Complex (NDMIC) is one of several satellite plutons related to the Boulder batholith and represents an ideal microcosm of the batholith for petrogenetic and structural studies because it exposes both mafic and felsic units and was emplaced in the limb of a major thrust related fold. We present new geologic mapping and detailed trace element geochemical analyses to show that the entire mafic-to-felsic suite of rocks in the NDMIC are cogenetic and shoshonitic in character. Shoshonites are unusual magmas that are distinguished by their high concentrations of K, Rb, Sr, Ba, Zr, and Th contents, and are thought to represent partial melting at great depths within the mantle wedge above a subducting slab. The presence of shoshonitic magma in the Cordilleran foreland fold and thrust belt provides important clues into the nature of the formation of this unusual magma type and can provide insights into our understanding of magmatism in foreland structural settings.

  12. Plains tectonism on Venus: The deformation belts of Lavinia Planitia

    NASA Technical Reports Server (NTRS)

    Squyres, Steven W.; Jankowski, David G.; Simons, Mark; Solomon, Sean C.; Hager, Bradford H.; Mcgill, George E.

    1993-01-01

    High-resolution radar images from the Magellan spacecraft have revealed the first details of the morphology of the Lavinia Planitia region of Venus. A number of geologic units can be distinguished, including volcanic plains units with a range of ages. Transecting these plains over much of the Lavinia region are two types of generally orthogonal features that we interpret to be compressional wrinkle ridges and extensional grooves. The dominant tectonic features of Lavinia are broad elevated belts of intense deformation that transect the plains with complex geometry. They are many tens to a few hundred kilometers wide, as much as 1000 km long, and elevated hundreds of meters above the surrounding plains. Two classes of deformation belts are seen in the Lavinia region. 'Ridge belts' are composed of parallel ridges, each a few hundred meters in elevation, that we interpret to be folds. Typical fold spacings are 5-10 km. 'Fracture belts' are dominated instead by intense faulting, with faults in some instances paired to form narrow grabens. There is also some evidence for modest amounts of horizontal shear distributed across both ridge and fracture belts. Crosscutting relationships among the belts show there to be a range in belt ages. In western Lavinia, in particular, many ridge and fracture belts appear to bear a relationship to the much smaller wrinkle ridges and grooves on the surrounding plains: ridge morphology tends to dominate belts that lie more nearly parallel to local plains wrinkle ridges, and fracture morphology tends to dominate belts that lie more nearly parallel to local plains grooves. We use simple models to explore the formation of ridge and fracture belts. We show that convective motions in the mantle can couple to the crust to cause horizontal stresses of a magnitude sufficient to induce the formation of deformation belts like those observed in Lavinia. We also use the small-scale wavelengths of deformation observed within individual ridge belts to

  13. Orogenic front propagation in the basement involved Malargüe fold and thrust belt, Neuquén Basin, (Argentina)

    NASA Astrophysics Data System (ADS)

    Branellec, Matthieu; Nivière, Bertrand; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2015-04-01

    The Malargüe fold and thrust belt (MFTB) and the San Rafael Block (SRB) are located in the northern termination of the Neuquén basin in Argentina. This basin is a wide inverted intracratonic sag basin with polyphased evolution controlled at large scale by the dynamic of the Pacific subduction. By late Triassic times, narrow rift basins developed and evolved toward a sag basin from middle Jurassic to late Cretaceous. From that time on, compression at the trench resulted in various shortening pulses in the back-arc area. Here we aim to analyze the Andean system at 35°S by comparing the Miocene structuration in the MFTB and the current deformation along the oriental border or the San Rafael Block. The main structuration stage in the MFTB occurred by Miocene times (15 to 10 Ma) producing the principal uplift of the Andean Cordillera. As shown by new structural cross sections, Triassic-early Jurassic rift border faults localized the Miocene compressive tectonics. Deformation is compartmentalized and does not exhibit a classical propagation of homogeneous deformation sequence expected from the critical taper theory. Several intramontane basins in the hangingwall of the main thrusts progressively disconnected from the foreland. In addition, active tectonics has been described in the front of the MFTB attesting for the on-going compression in this area. 100 km farther to the east, The San Rafael Block, is separated from the MFTB by the Rio Grande basin. The SRB is mostly composed of Paleozoic terranes and Triassic rift-related rocks, overlain by late Miocene synorogenic deposits. The SRB is currently uplifted along its oriental border along several active faults. These faults have clear morphologic signatures in Quaternary alluvial terraces and folded Pleistocene lavas. As in the MFTB, the active deformation localization remains localized by structural inheritance. The Andean system is thus evolving as an atypical orogenic wedge partly by frontal accretion at the front

  14. An improved evaluation of the seismic/geodetic deformation-rate ratio for the Zagros Fold-and-Thrust collisional belt

    NASA Astrophysics Data System (ADS)

    Palano, Mimmo; Imprescia, Paola; Agnon, Amotz; Gresta, Stefano

    2018-04-01

    We present an improved picture of the ongoing crustal deformation field for the Zagros Fold-and-Thrust Belt continental collision zone by using an extensive combination of both novel and published GPS observations. The main results define the significant amount of oblique Arabia-Eurasia convergence currently being absorbed within the Zagros: right-lateral shear along the NW trending Main Recent fault in NW Zagros and accommodated between fold-and-thrust structures and NS right-lateral strike-slip faults on Southern Zagros. In addition, taking into account the 1909-2016 instrumental seismic catalogue, we provide a statistical evaluation of the seismic/geodetic deformation-rate ratio for the area. On Northern Zagros and on the Turkish-Iranian Plateau, a moderate to large fraction (˜49 and >60 per cent, respectively) of the crustal deformation occurs seismically. On the Sanandaj-Sirjan zone, the seismic/geodetic deformation-rate ratio suggests that a small to moderate fraction (<40 per cent) of crustal deformation occurs seismically; locally, the occurrence of large historic earthquakes (M ≥ 6) coupled with the high geodetic deformation, could indicate overdue M ≥ 6 earthquakes. On Southern Zagros, aseismic strain dominates crustal deformation (the ratio ranges in the 15-33 per cent interval). Such aseismic deformation is probably related to the presence of the weak evaporitic Hormuz Formation which allows the occurrence of large aseismic motion on both subhorizontal faults and surfaces of décollement. These results, framed into the seismotectonic framework of the investigated region, confirm that the fold-and-thrust-dominated deformation is driven by buoyancy forces; by contrast, the shear-dominated deformation is primary driven by plate stresses.

  15. Triple junction orogeny: tectonic evolution of the Pan-African Northern Damara Belt, Namibia

    NASA Astrophysics Data System (ADS)

    Lehmann, Jérémie; Saalmann, Kerstin; Naydenov, Kalin V.; Milani, Lorenzo; Charlesworth, Eugene G.; Kinnaird, Judith A.; Frei, Dirk; Kramers, Jan D.; Zwingmann, Horst

    2014-05-01

    Trench-trench-trench triple junctions are generally geometrically and kinematically unstable and therefore can result at the latest stages in complicated collisional orogenic belts. In such geodynamic sites, mechanism and timescale of deformations that accommodate convergence and final assembly of the three colliding continental plates are poorly studied. In western Namibia, Pan-African convergence of three cratonic blocks led to pene-contemporaneous closure of two highly oblique oceanic domains and formation of the triple junction Damara Orogen where the NE-striking Damara Belt abuts to the west against the NNW-striking Kaoko-Gariep Belt. Detailed description of structures and microstructures associated with remote sensing analysis, and dating of individual deformation events by means of K-Ar, Ar-Ar (micas) and U-Pb (zircon) isotopic studies from the Northern Damara Belt provide robust constraints on the tectonic evolution of this palaeo-triple junction orogeny. There, passive margin sequences of the Neoproterozoic ocean were polydeformed and polymetamorphosed to the biotite zone of the greenschist facies to up to granulite facies and anatexis towards the southern migmatitic core of the Central Damara Belt. Subtle relict structures and fold pattern analyses reveal the existence of an early D1 N-S shortening event, tentatively dated between ~635 Ma and ~580 Ma using published data. D1 structures were almost obliterated by pervasive and major D2 E-W coaxial shortening, related to the closure of the Kaoko-Gariep oceanic domain and subsequent formation of the NNW-striking Kaoko-Gariep Belt to the west of the study area. Early, km-scale D1 E-W trending steep folds were refolded during this D2 event, producing either Type I or Type II fold interference patterns visible from space. The D2 E-W convergence could have lasted until ~533 Ma based on published and new U-Pb ages. The final D3 NW-SE convergence in the northernmost Damara Belt produced a NE-striking deformation

  16. Control of preexisting faults and near-surface diapirs on geometry and kinematics of fold-and-thrust belts (Internal Prebetic, Eastern Betic Cordillera)

    NASA Astrophysics Data System (ADS)

    Pedrera, Antonio; Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; García-Lobón, José Luis

    2014-07-01

    We have determined, for the first time, the 3D geometry of a sector of the eastern Internal Prebetic comprised between Parcent and Altea diapirs, combining structural, borehole and multichannel seismic reflection data. The tectonic structure of the Jurassic-Cretaceous carbonate series is characterized by regional ENE-WSW fold-and-thrusts that interact with oblique N-S and WNW-ESE folds, detached over Triassic evaporites and clays. The structural style comprises box-shape anticlines, and N-vergent anticlines with vertical to overturned limbs frequently bordered by reverse and strike-slip faults. The anticlines surround a triangular broad synclinal structure, the Tárbena basin, filled by a late Oligocene to Tortonian sedimentary sequence that recorded folding and thrusting history. The location and geometrical characteristics of fold-and-thrusts may be controlled by the positive inversion of pre-existing Mesozoic normal faults, and by the position and shape of near-surface diapirs composed of Triassic rocks. Therefore, we propose an initial near-surface diapir emplacement of Triassic evaporitic rocks driven by late Jurassic to early Cretaceous rifting of the southern Iberian paleomargin. Thrusting and folding started during the latest Oligocene (∼28-23 Ma) roughly orthogonal to the NW-directed shortening. Deformation migrated to the south during Aquitanian (∼23-20 Ma), when tectonic inversion implied the left-lateral transpressive reactivation of N-S striking former normal faults and right-lateral/reverse reactivation of inherited WNW-ESE faults. We show two mechanisms driving the extrusion of the diapirs during contraction: lateral migration of a pre-existing near-surface diapir associated with dextral transpression; and squeezing of a previous near-surface diapir at the front of an anticline. Our study underlines the value of 3D geological modeling to characterize geometry and kinematics of complex fold-and-thrust belts influenced by preexisting faults and

  17. Out-of-pocket payment for health services: constraints and implications for government employees in Abakaliki, Ebonyi State, south east Nigeria.

    PubMed

    Oyibo, P G

    2011-09-01

    Each year, 100 million people are impoverished globally as a result of expenditure on health. To assess the constraints and implications of out-of-pocket payment for health services among government employees in Abakaliki, Ebonyi State, south east Nigeria. This was a cross-sectional descriptive study. The study instrument was a pre-tested, semi-structured self administered questionnaire. Over half of the respondents (62.8 %) reported a history of illness in their household in the preceding four weeks before the study. Sixty-nine percent of these respondents relied on out-of-pocket payment in order to pay for health services at the moment of seeking medical treatment for themselves or their dependants; while 28.4 % and 2.6 % relied on a pre-payment package (National Health Insurance Scheme) and borrowed money respectively to pay for health services at the moment of seeking medical treatment for themselves or their dependants. The vast majority of respondents (63.6 %) who relied on out-of-pocket payment reported their difficulties in accessing quality health care services as a result of financial hardship at the moment of seeking medical treatment. Most of them (47.7 %) resolved to self medication, while 28.4 %, 17.1 % and 6.8 % of them delayed seeking health care, patronized herbalists and ignored their illness respectively. This study brings to the fore the fact that most government employees and their dependants in Abakaliki have difficulties in accessing quality health care services via paying for them out-of-pocket.

  18. Dillon cutoff-Basement-involved tectonic link between the disturbed belt of west-central Montana and the overthrust belt of extreme southwestern Montana

    NASA Astrophysics Data System (ADS)

    O'Neill, J. Michael; Schmidt, Christopher J.; Genovese, Paul W.

    1990-11-01

    The front of the Cordilleran fold and thrust belt in western Montana follows the disturbed belt in the north, merges with the southwest Montana transverse zone in the west-central part of the region, and in southwestern Montana is marked by a broad zone characterized by complex interaction between thrust belt structures and basement uplifts. The front margin of the thrust belt in Montana reflects mainly thin-skinned tectonic features in the north, an east-trending lateral ramp that curves southwest in the central part into the Dillon cutoff, an oblique-slip, thick-skinned displacement transfer zone that cuts through basement rocks of the Lima recess, and a zone of overlap between thin- and thick-skinned thrusts in extreme southwestern Montana. The transverse ramp and basement-involved thrust faults are controlled by Proterozoic structures.

  19. Sedimentation of Jurassic fan-delta wedges in the Xiahuayuan basin reflecting thrust-fault movements of the western Yanshan fold-and-thrust belt, China

    NASA Astrophysics Data System (ADS)

    Lin, Chengfa; Liu, Shaofeng; Zhuang, Qitian; Steel, Ronald J.

    2018-06-01

    Mesozoic thrusting within the Yanshan fold-and-thrust belt of North China resulted in a series of fault-bounded intramontane basins whose infill and evolution remain poorly understood. In particular, the bounding faults and adjacent sediment accumulations along the western segments of the belt are almost unstudied. A sedimentological and provenance analysis of the Lower Jurassic Xiahuayuan Formation and the Upper Jurassic Jiulongshan Formation have been mapped to show two distinctive clastic wedges: an early Jurassic wedge representing a mass-flow-dominated, Gilbert-type fan delta with a classic tripartite architecture, and an late Jurassic shoal-water fan delta without steeply inclined strata. The basinward migration of the fan-delta wedges, together with the analysis of their conglomerate clast compositions, paleocurrent data and detrital zircon U-Pb age spectra, strongly suggest that the northern-bounding Xuanhuan thrust fault controlled their growth during accumulation of the Jiulongshan Formation. Previous studies have suggested that the fan-delta wedge of the Xiahuayuan Formation was also syntectonic, related to movement on the Xuanhua thrust fault. Two stages of thrusting therefore exerted an influence on the formation and evolution of the Xiahuayuan basin during the early-late Jurassic.

  20. A Computerized Tomography Study of Vocal Tract Setting in Hyperfunctional Dysphonia and in Belting.

    PubMed

    Saldias, Marcelo; Guzman, Marco; Miranda, Gonzalo; Laukkanen, Anne-Maria

    2018-04-03

    Vocal tract setting in hyperfunctional patients is characterized by a high larynx and narrowing of the epilaryngeal and pharyngeal region. Similar observations have been made for various singing styles, eg, belting. The voice quality in belting has been described to be loud, speech like, and high pitched. It is also often described as sounding "pressed" or "tense". The above mentioned has led to the hypothesis that belting may be strenuous to the vocal folds. However, singers and teachers of belting do not regard belting as particularly strenuous. This study investigates possible similarities and differences between hyperfunctional voice production and belting. This study concerns vocal tract setting. Four male patients with hyperfunctional dysphonia and one male contemporary commercial music singer were registered with computerized tomography while phonating on [a:] in their habitual speaking pitch. Additionally, the singer used the pitch G4 in belting. The scannings were studied in sagittal and transversal dimensions by measuring lengths, widths, and areas. Various similarities were found between belting and hyperfunction: high vertical larynx position, small hypopharyngeal width, and epilaryngeal outlet. On the other hand, belting differed from dysphonia (in addition to higher pitch) by a wider lip and jaw opening, and larger volumes of the oral cavity. Belting takes advantage of "megaphone shape" of the vocal tract. Future studies should focus on modeling and simulation to address sound energy transfer. Also, they should consider aerodynamic variables and vocal fold vibration to evaluate the "price of decibels" in these phonation types. Copyright © 2018. Published by Elsevier Inc.

  1. Trapped belt variations and their effects on human space flights

    NASA Technical Reports Server (NTRS)

    Robbins, Donald E.; Badhwar, Gautam D.

    1993-01-01

    Variations in the Earth's trapped (Van Allen) belts produced by solar flare particle events are not well understood. This paper reports the existence of a second proton belt and its subsequent decay as measured by a tissue-equivalent proportional counter and a particle spectrometer on five Space Shuttle flights covering an 18-month period. The creation of this second belt is attributed to the injection of particles from a solar particle event which occurred at 2246 UT, March 22, 1991. Comparisons with observations onboard the Russian Mir space station and other unmanned satellites are made. Shuttle measurements and data from other spacecraft are used to determine that the e-folding time of the peak of the second proton belt was ten months. Proton populations in the second belt returned to values of quiescent times within 18 months. The increase in absorbed dose attributed to protons in the second belt was approximately 20 percent. Passive dosimeter measurements were in good agreement with this value.

  2. Evolution of the stress fields in the Zagros Foreland Folded Belt using focal mechanisms and kinematic analyses: the case of the Fars salient, Iran

    NASA Astrophysics Data System (ADS)

    Sarkarinejad, Khalil; Zafarmand, Bahareh; Oveisi, Behnam

    2018-03-01

    The NW-SE trending Zagros orogenic belt was initiated during the convergence of the Afro-Arabian continent and the Iranian microcontinent in the Late Cretaceous. Ongoing convergence is confirmed by intense seismicity related to compressional stresses collision-related in the Zagros orogenic belt by reactivation of an early extensional faulting to latter compressional segmented strike-slip and dip-slip faulting. These activities are strongly related either to the deep-seated basement fault activities (deep-seated earthquakes) underlies the sedimentary cover or gently dipping shallow-seated décollement horizon of the rheological weak rocks of the infra-Cambrian Hormuz salt. The compressional stress regimes in the different units play an important role in controlling the stress conditions between the different units within the sedimentary cover and basement. A significant set of nearly N-S trending right-lateral strike-slip faults exists throughout the study area in the Fars area in the Zagros Foreland Folded Belt. Fault-slip and focal mechanism data were analyzed using the stress inversion method to reconstruct the paleo and recent stress conditions. The results suggest that the current direction of maximum principal stress averages N19°E, with N38°E that for the past from Cretaceous to Tertiary (although a few sites on the Kar-e-Bass fault yield a different direction). The results are consistent with the collision of the Afro-Arabian continent and the Iranian microcontinent. The difference between the current and paleo-stress directions indicates an anticlockwise rotation in the maximum principle stress direction over time. This difference resulted from changes in the continental convergence path, but was also influenced by the local structural evolution, including the lateral propagation of folds and the presence of several local décollement horizons that facilitated decoupling of the deformation between the basement and the sedimentary cover. The obliquity of

  3. Nature and time of emplacement of a pegmatoidal granite within the Delhi Fold Belt near Bayalan, Rajasthan, India

    NASA Astrophysics Data System (ADS)

    Dasgupta, N.; Sen, J.; Pal, T.; Ghosh, T.

    2009-04-01

    The study area is situated about 70 km south east of Ajmer, in Rajasthan, India around the village Bayala (26o 02' 19 N''; 74o 21' 01'') within the Ajmer district of Central Rajasthan. The area is along the eastern flank of the central portion of the Precambrian South Delhi Fold Belt (SDFB) and it stratigraphically belongs to the Bhim Group of rocks. Basement rocks of Archaean age, commonly known as the Banded gneissic Complex (BGC), is exposed to the east, where the rocks of the Bhim Group rests unconformably over BGC. To the west gneissic basement rocks of mid-Proterozoic times underlie the Bhim Group and have been referred to as the Beawar gneiss (BG). The Bhim Group of rocks comprises of metamorphosed marls and calc-silicate gneisses with minor amounts of quartzites and pelitic schists, indicative of its shallow marine origin. Within the Bhim Group, a pegmatoidal granite has intruded the calc silicate gneisses of the area. The pegmatoidal granite body is elliptical in outline with the long dimension(20 km) trending N-S and covers an area of 300 sq. km. approximately. This granite have so far been mapped as basement rocks (BG) surrounding the Beawar town (26o 06' 05'' N; 74o 19' 03'' E), 50 km south east of Ajmer. Rafts of calc-silicate gneisses, belonging to the Bhim Group, are seen to be entrapped within granite. Fragments of BG and its equivalents have also been found as caught up blocks within this pegmatoidal granite body near Andheri Devari, a small hamlet east of Beawar. The objective of the study was to map this pegmatoidal body, and decipher the mechanism and time of emplacement of this granite. A detailed structural mapping of the area in a 1:20000 scale spread over a 30 sq. km area in the vicinity of Bayala was carried out to analyse the geometry and the time of emplacement of the pegmatitic granite. The ridges of calc silicates and marbles adjoining the area were studied for the structural analyses of the Delhi fold belt rocks of the area. The calc

  4. Structural Evolution and Fracture Development of Chinshui Anticline in a Fold-and-Thrust Belt, Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, T. W.; Hu, J. C.; Huang, S. T.

    2016-12-01

    Hsinchu-Miaoli area is the major hydrocarbon producing fields in the fold-and-thrust belt of Taiwan. To understand the nature and the geometry of the reservoirs in this area, 82 wells were drilled in the Chinshui Field, which is one of the important gas fields in the Hsinchu-Miaoli area. However, the subsurface structures and fracture distribution of these fields are still unclear, and the reason for long time producing is also unknown. Fractures in the oil-bearing reservoir might be one of the important factors of long time gas producing, but the fracture reservoirs attaining hydrocarbons associated with fault-related folding need to be further clarified. In this study, we first represent a new structural interpretation of Chinshui anticlines and adjacent structures by a geological cross section across from Miaoli offshore to inner western foothills. After conducting 2D restoration with 2DMove, we could test whether our structural interpretation is reasonable and clarify the evolution history of Chinshui anticline and adjacent structures. We further construct a 3D structural model of Chinshui anticline by GOCAD. By using surface restoration, the location with higher fracture density could be inferred and be taken into account for reproduction. According to the restoration, we conclude that Chinshui anticline is mainly formed by the movement of the deep detachment. The old strata between two detachments develop a thrust wedge and deform upper strata to form Chinshui anticline. Furthermore, we obtain strain fields and the extension areas of Talu shale, Tungkeng, Chuhaungkeng, Mushan and Wuchihshan Formation of Chinshui anticline during the deformation. The results reveal that the highest fracture density lies in the hinge of A and C blocks in Mushan Formation as well as the hinge of B block in Wuchihshan Formation. After comparing the curvature and strain fields of these surfaces, we also find out that the strain field is highly relevant to the curvature of Chinshui

  5. First-order control of syntectonic sedimentation on crustal-scale structure of mountain belts

    NASA Astrophysics Data System (ADS)

    Erdős, Zoltán.; Huismans, Ritske S.; van der Beek, Peter

    2015-07-01

    The first-order characteristics of collisional mountain belts and the potential feedback with surface processes are predicted by critical taper theory. While the feedback between erosion and mountain belt structure has been fairly extensively studied, less attention has been given to the potential role of synorogenic deposition. For thin-skinned fold-and-thrust belts, recent studies indicate a strong control of syntectonic deposition on structure, as sedimentation tends to stabilize the thin-skinned wedge. However, the factors controlling basement deformation below fold-and-thrust belts, as evident, for example, in the Zagros Mountains or in the Swiss Alps, remain largely unknown. Previous work has suggested that such variations in orogenic structure may be explained by the thermotectonic "age" of the deforming lithosphere and hence its rheology. Here we demonstrate that sediment loading of the foreland basin area provides an additional control and may explain the variable basement involvement in orogenic belts. When examining the role of sedimentation, we identify two end-members: (1) sediment-starved orogenic systems with thick-skinned basement deformation in an axial orogenic core and thin-skinned deformation in the bordering forelands and (2) sediment-loaded orogens with thick packages of synorogenic deposits, derived from the axial basement zone, deposited on the surrounding foreland fold-and-thrust belts, and characterized by basement deformation below the foreland. Using high-resolution thermomechanical models, we demonstrate a strong feedback between deposition and crustal-scale thick-skinned deformation. Our results show that the loading effects of syntectonic sediments lead to long crustal-scale thrust sheets beneath the orogenic foreland and explain the contrasting characteristics of sediment-starved and sediment-loaded orogens, showing for the first time how both thin- and thick-skinned crustal deformations are linked to sediment deposition in these

  6. Tectonic and thermal history of the western Serrania del Interior foreland fold and thrust belt and Guarico Basin, north central Venezuela: Implications of new apatite fission track analysis and seismic interpretation

    NASA Astrophysics Data System (ADS)

    Perez de Armas, Jaime Gonzalo

    Structural analysis, interpretation of seismic reflection lines, and apatite fission-track analysis in the Western Serrania del Interior fold and thrust belt and in the Guarico basin of north-central Venezuela indicate that the area underwent Mesozoic and Tertiary-to-Recent deformation. Mesozoic deformation, related to the breakup of Pangea, resulted in the formation of the Espino graben in the southernmost portion of the Guarico basin and in the formation of the Proto-Caribbean lithosphere between the diverging North and South American plates. The northern margin of Venezuela became a northward facing passive margin. Minor normal faults formed in the Guarico basin. The most intense deformation took place in the Neogene when the Leeward Antilles volcanic island arc collided obliquely with South America. The inception of the basal foredeep unconformity in the Late Eocene-Early Oligocene marks the formation of a perisutural basin on top of a buried graben system. It is coeval with minor extension and possible reactivation of Cretaceous normal faults in the Guarico basin. It marks the deepening of the foredeep. Cooling ages derived from apatite fission-tracks suggest that the obduction of the fold and thrust belt in the study area occurred in the Late Oligocene through the Middle Miocene. Field data and seismic interpretations suggest also that contractional deformation began during the Neogene, and specifically during the Miocene. The most surprising results of the detrital apatite fission-track study are the ages acquired in the sedimentary rocks of the easternmost part of the study area in the foreland fold and thrust belt. They indicate an Eocene thermal event. This event may be related to the Eocene NW-SE convergence of the North and South American plates that must have caused the Proto-Caribbean lithosphere to be shortened. This event is not related to the collision of the arc with South America, as the arc was far to the west during the Eocene.

  7. Late Mesozoic deformations of the Verkhoyansk-Kolyma orogenic belt, Northeast Russia

    NASA Astrophysics Data System (ADS)

    Fridovsky, Valery

    2016-04-01

    The Verkhoyansk-Kolyma orogenic belt marks the boundary between the Kolyma-Omolon superterrane (microcontinent) and the submerged eastern margin of the North Asian craton. The orogenic system is remark able for its large number of economically viable gold deposits (Natalka, Pavlik, Rodionovskoe, Drazhnoe, Bazovskoe, Badran, Malo-Tarynskoe, etc.). The Verkhoyansk - Kolyma orogenic belt is subdivided into Kular-Nera and the Polousny-Debin terranes. The Kular-Nera terrane is mainly composed of the Upper Permian, Triassic, and Lower Jurassic black shales that are metamorphosed at lower greenschist facies conditions. The Charky-Indigirka and the Chai-Yureya faults separate the Kular-Nera from the Polousny-Debin terrane that is predominantly composed of the Jurassic flyschoi dturbidites. The deformation structure of the region evolved in association with several late Mesozoic tectonic events that took place in the north-eastern part ofthe Paleo-Pacific. In Late Jurassic-Early Cretaceous several generations of fold and thrust systems were formed due to frontal accretion of the Kolyma-Omolon superterrane to the eastern margin of the North Asian craton.Thrusting and folding was accompanied by granitic magmatism, metamorphic reworking of the Late Paleozoic and the Early Mesozoic sedimentary rocks, and formation of Au-Sn-W mineralization. Three stages of deformation related to frontal accretion can be distinguished. First stage D1 has developed in the north-eastern part of the Verkhoyansk - Kolyma orogenic belt. Early tight and isoclinal folds F1 and assosiated thrusts are characteristic of D1. Major thrusts, linear concentric folds F2 and cleavage were formed during D2. The main ore-controlling structures are thrust faults forming imbricate fan systems. Frontal and oblique ramps and systems of bedding and cross thrusts forming duplexes are common. It is notable that mineralized tectonized zones commonly develop along thrusts at the contacts of rocks of contrasting competence

  8. Why style matters - uncertainty and structural interpretation in thrust belts.

    NASA Astrophysics Data System (ADS)

    Butler, Rob; Bond, Clare; Watkins, Hannah

    2016-04-01

    Structural complexity together with challenging seismic imaging make for significant uncertainty in developing geometric interpretations of fold and thrust belts. Here we examine these issues and develop more realistic approaches to building interpretations. At all scales, the best tests of the internal consistency of individual interpretations come from structural restoration (section balancing), provided allowance is made for heterogeneity in stratigraphy and strain. However, many existing balancing approaches give misleading perceptions of interpretational risk - both on the scale of individual fold-thrust (trap) structures and in regional cross-sections. At the trap-scale, idealised models are widely cited - fault-bend-fold, fault-propagation folding and trishear. These make entirely arbitrary choices for fault localisation and layer-by-layer deformation: precise relationships between faults and fold geometry are generally invalidated by real-world conditions of stratigraphic variation and distributed strain. Furthermore, subsurface predictions made using these idealisations for hydrocarbon exploration commonly fail the test of drilling. Rarely acknowledged, the geometric reliability of seismic images depends on the assigned seismic velocity model, which in turn relies on geological interpretation. Thus iterative approaches are required between geology and geophysics. The portfolio of commonly cited outcrop analogues is strongly biased to examples that simply conform to idealised models - apparently abnormal structures are rarely described - or even photographed! Insight can come from gravity-driven deep-water fold-belts where part of the spectrum of fold-thrust complexity is resolved through seismic imaging. This imagery shows deformation complexity in fold forelimbs and backlimbs. However, the applicability of these, weakly lithified systems to well-lithified successions (e.g. carbonates) of many foreland thrust belts remains conjectural. Examples of

  9. Age and evolution of thin-skinned deformation in Zacatecas, Mexico: Sevier orogeny evidence in the Mexican Fold-Thrust Belt

    NASA Astrophysics Data System (ADS)

    Ramírez-Peña, César Francisco; Chávez-Cabello, Gabriel

    2017-07-01

    Integrating U-Pb ages from zircons of syn- and postectonic intrusives emplaced in folded pre- and synorogenic marine sedimentary rocks, it is proposed that thin-skinned deformation in the Concepción del Oro salient of the Mexican Fold Thrust Belt in northern Zacatecas, Mexico, was active between 92 and 71.6 Ma. The intrusives Pico de Teyra and El Peñuelo (U-Pb zircon ages: 76.9 and 72.5 Ma) show internal tectonic foliations and horizontal shear zones that cut off aplitic veins, which apparently developed syntectonically to thin-skinned deformation. Other intrusives like Saltillito (71.6 Ma) and Concepción del Oro are clearly postectonic because they are undeformed internally, cut regional structures and are younger than syntectonic plutons. Biostratigraphic ages reported for synorogenic sediments (Concepción del Oro and Parras formations) indicate that regional thin-skinned deformation was active between Early Turonian and Late Campanian, which is in agreement with syn and postectonic intrusive emplacement ages in the area. Nevertheless, the thin-skinned structures are disrupted by a younger NNW-SSE high angle reverse and normal faults that uplifts the San Julián Block in the west and truncate the Concepción del Oro salient, suggesting a post-Paleocene thick-skinned stage of deformation. In this work, we propose that style and age of thin-skinned deformation is similar to the Sevier orogeny in the Rocky Mountains.

  10. Crustal structure of central Syria: The intracontinental Palmyride mountain belt

    NASA Astrophysics Data System (ADS)

    Al-Saad, Damen; Sawaf, Tarif; Gebran, Ali; Barazangi, Muawia; Best, John A.; Chaimov, Thomas A.

    1992-07-01

    Along a 450-km transect across central Syria seismic reflection data, borehole information, potential field data and surface geologic mapping have been combined to examine the crustal structure of the northern Arabian platform beneath Syria. The transect is surrounded by the major plate boundaries of the Middle East, including the Dead Sea transform fault system along the Levantine margin to the west, the Bitlis suture and East Anatolian fault to the north, and the Zagros collisional belt to the northeast and east. Three main tectonic provinces of the northern Arabian platform in Syria are crossed by this transect from south to north: the Rutbah uplift, the Palmyra fold-thrust belt, and the Aleppo plateau. The Rutbah uplift in southern Syria is a broad, domal basement-cored structure with a thick Phanerozoic (mostly Paleozoic) cover of 6-7 km. Isopachs based on well and seismic reflection data indicate that this region was an early Paleozoic depocenter. The Palmyra fold-thrust belt, the northeastern arm of the Syrian Arc, is a northeast-southwest-trending intracontinental mountain belt that acts as a mobile tectonic zone between the relatively stable Rutbah uplift to the south and the less stable Aleppo plateau to the north. Short-wavelength en-echelon folds characterized by relatively steep, faulted southeast flanks dominate in the southwest, most strongly deformed segment of the belt, while a complex system of deeply rooted faults and broad folds characterize the northeastern region, described in this study. The Aleppo plateau lies immediately north of the Palmyride belt, with a combined Paleozoic and Mesozoic sedimentary section that averages 4-5 km in thickness. Although this region appears relatively undeformed on seismic reflection data when compared to Palmyride deformation, a system of near-vertical, probable strike-slip faults crosscut the region in a dominantly northeasterly direction. Gravity and magnetic modeling constrains the deep crustal structure

  11. Structural profile reconstructions and thermal metamorphic evolution in the slate belt of southern Hsuehshan Range in the active Taiwan mountain belt

    NASA Astrophysics Data System (ADS)

    Wu, Yu; Chen, Chih-Tung; Lee, Jian-Cheng; Shyu, J. Bruce H.

    2017-04-01

    The fate of passive continental margin in collisional orogens is crucial in understanding tectonic evolution of mountain belts. The active arc-continent collision of Taiwan is considered as a model case in studying mountain building processes, and largely consists of deformed margin basement and cover series. Among the whole orogeny belt, the slate belt of the Hsuehshan Range (HR) is a prominent large-scale pop-up structural on the prowedge part of the orogen, and is composed of metamorphosed Eocene to Miocene sediments which experienced only the Neogene Taiwan orogeny after diagenesis in margin graben. Characterizing the metamorphic history of the HR is essential for reconstructing its geological evolution during the mountain building processes. However, previous studies were mostly focused on northern and central HR, structural investigation coupled with metamorphic documentation in the southern part of HR, which is the most active part of the orogeny belt, is therefore targeted in this work. Since carbonaceous material is common in pelitic protolith of HR slates, the Raman spectrum of carbonaceous material (RSCM) measuring the rock peak temperature is chosen for quantitative thermal metamorphic documentation. In this study, we reconstruct a geological structural profile in western central Taiwan across the prowedge part of the mountain belt containing the southern HR by combining the surface geological data, well log records and published seismic reflection profiles. Although most of the existing data are concentrated in the fold-and-thrust belt, they are now reinforced by new field structural measurements and RSCM samples in the southern HR. In total 27 RSCM samples were collected along 2 transects perpendicular to the average strike with a dense interval about 2 km. The results allow us to map peak temperature distribution across southern HR, and provide new constraints for structural profile reconstruction and reappraisal of the structural evolution of the HR

  12. Earthquakes, gravity, and the origin of the Bali Basin: An example of a Nascent Continental Fold-and-Thrust Belt

    NASA Astrophysics Data System (ADS)

    McCaffrey, Robert; Nabelek, John

    1987-01-01

    We infer from the bathymetry and gravity field and from the source mechanisms and depths of the eight largest earthquakes in the Bali region that the Bali Basin is a downwarp in the crust of the Sunda Shelf produced and maintained by thrusting along the Flores back arc thrust zone. Earthquake source mechanisms and focal depths are inferred from the inversion of long-period P and SH waves for all events and short-period P waves for two of the events. Centroidal depths that give the best fit to the seismograms range from 10 to 18 km, but uncertainties in depth allow a range from 7 to 24 km. The P wave nodal planes that dip south at 13° to 35° (±7°) strike roughly parallel to the volcanic arc and are consistent with thrusting of crust of the Bali Basin beneath it. The positions of the earthquakes with respect to crustal features inferred from seismic and gravity data suggest that the earthquakes occur in the basement along the western end of the Flores thrust zone. The slip direction for the back arc thrust zone inferred from the orientation of the earthquake slip vectors indicates that the thrusting in the Bali Basin is probably part of the overall plate convergence, as it roughly coincides with the convergence direction between the Sunda arc and the Indian Ocean plate. Summation of seismic moments of earthquakes between 1960 and 1985 suggests a minimum rate of convergence across the thrust zone of 4 ± 2 mm/a. The presence of back arc thrusting suggests that some coupling between the Indian Ocean plate and the Sunda arc occurs but mechanisms such as continental collision or a shallow subduction of the Indian Ocean plate probably can be ruled out. The present tectonic setting and structure of the Bali Basin is comparable to the early forelands of the Andes or western North America in that a fold-and-thrust belt is forming on the continental side of an arc-trench system at which oceanic lithosphere is being subducted. The Bali Basin is flanked by the Tertiary Java

  13. Geochemical constraints on the petrogenesis of the pyroclastic rocks in Abakaliki basin (Lower Benue Rift), Southeastern Nigeria

    NASA Astrophysics Data System (ADS)

    Chukwu, Anthony; Obiora, Smart C.

    2018-05-01

    The pyroclastic rocks in the Cretaceous Abakaliki basin occur mostly as oval-shaped bodies, consisting of lithic/lava and vitric fragments. They are commonly characterized by parallel and cross laminations, as well contain xenoliths of shale, mudstone and siltstones from the older Asu River Group of Albian age. The rocks are basic to ultrabasic in composition, comprising altered alkali basalts, altered tuffs, minor lapillistones and agglomerates. The mineral compositions are characterized mainly by laths of calcic plagioclase, pyroxene (altered), altered olivines and opaques. Calcite, zeolite and quartz represent the secondary mineral constituents. Geochemically, two groups of volcaniclastic rocks, are distinguished: alkaline and tholeiitic rocks, both represented by fresh and altered rock samples. The older alkali basalts occur within the core of the Abakaliki anticlinorium while the younger tholeiites occur towards the periphery. Though most of the rocks are moderate to highly altered [Loss on ignition (LOI, 3.43-22.07 wt. %)], the use of immobile trace element such as Nb, Zr, Y, Hf, Ti, Ta and REEs reflect asthenospheric mantle source compositions. The rocks are enriched in incompatible elements and REEs (∑REE = 87.98-281.0 ppm for alkaline and 69.45-287.99 ppm for tholeiites). The ratios of La/Ybn are higher in the alkaline rocks ranging from 7.69 to 31.55 compared to the tholeiitic rocks which range from 4.4 to 16.89 and indicating the presence of garnet-bearing lherzolite in the source mantle. The spidergrams and REEs patterns along with Zr/Nb, Ba/Nb, Rb/Nb ratios suggest that the rocks were generated by a mantle plume from partial melting of mixed enriched mantle sources (HIMU, EMI and EMII) similar to the rocks of the south Atlantic Ocean such as St. Helena (alkaline rocks) and Ascension rocks (tholeiitic rocks). The rocks were formed in a within-plate setting of the intra-continental rift type similar to other igneous rocks in the Benue Rift and are not

  14. Structure and kinematics of a major tectonic contact, Michipicoten greenstone belt, Ontario

    NASA Technical Reports Server (NTRS)

    Mcgill, George E.

    1992-01-01

    The Michipicoten greenstone belt, Ontario, experienced a complex history of folding, faulting, and fabric development. Near Wawa, a major east-west contact, here named the Steep Hill Falls (SHF) contact, extends entirely across the belt. The SHF contact is both an angular unconformity and a fault and is interpreted to be a regionally significant tectonic contact separating distinct northern and southern terranes, both of which include volcanic rocks of probable island-arc origin. The amount of horizontal transport involved in bringing the two terranes together along the SHF contact is not known. Mapping and structural analysis suggest that regionally significant horizontal displacements took place, with movement vectors that changed with time. Early faults, folds, and fabrics imply north-south to northeast-southwest (with respect to present directions) convergence, with a vergence reversal occurring during this complex event. The most likely models infer early south vergence and later north vergence. Transecting the earliest structures are younger (but still Archean) northeast-striking steep cleavages with associated upright folds that may relate to northwest-southeast assembly of the Superior Province craton. The craton assembly event thus involved a transport direction at a high angle to that inferred for the earlier assembly of the Michipicoten greenstone belt.

  15. Distributed deformation in the Zagros fold-and-thrust belt: insights from geomorphology

    NASA Astrophysics Data System (ADS)

    Obaid, Ahmed; Allen, Mark

    2017-04-01

    The Zagros fold-and-thrust belt is part of the active Arabia-Eurasia collision zone, and is an excellent region to study the interactions of tectonics and landscape. In this work we present results of a geomorphic analysis covering the entire range, coupled with more detailed analysis of the Kirkuk Embayment, Iraq. This particular region is a low elevation, low relief region of the Zagros, important for the enormous oil and gas reserves held in late Cenozoic anticlinal traps. Constraints from published earthquake focal mechanisms and hydrocarbon industry sub-surface data are combined with original fieldwork observations in northern Iraq, to produce a new regional cross-section and structural interpretation for the Kirkuk Embayment. We find that overall late Cenozoic shortening across the Embayment is on the order of 5%, representing only a few km. This deformation takes place on a series of anticlines, which are interpreted as overlying steep, planar, basement thrusts. These thrusts are further interpreted as reactivated normal faults, on the basis of (rare) published seismic data. The regional earthquake record confirms the basement involvement, although detachments within the sedimentary succession are also important, especially within the Middle Miocene Fat'ha Formation. Overall, the Zagros is sometimes represented as having a few major thrusts each persistent for 100s of km along the strike of the range. However, these faults are very rarely associated with major structural relief and/or surface fault ruptures during earthquakes. We have analysed the hypsometry of the range and find only gradational changes in the hypsometric integral of drainage basins across strike. This contrasts with regions such as the eastern Tibetan Plateau, where published analysis has revealed abrupt changes, correlating with the surface traces of active thrusts. Our interpretation is that the hypsometry of the Zagros reflects distributed deformation on numerous smaller faults, rather

  16. Greenstone belts: Their components and structure

    NASA Technical Reports Server (NTRS)

    Vearncombe, J. R.; Barton, J. M., Jr.; Vanreenen, D. D.; Phillips, G. N.; Wilson, A. H.

    1986-01-01

    Greenstone sucessions are defined as the nongranitoid component of granitoid-greenstone terrain and are linear to irregular in shape and where linear are termed belts. The chemical composition of greenstones is described. Also discussed are the continental environments of greenstone successions. The effects of contact with granitoids, geophysical properties, recumbent folds and late formation structures upon greenstones are examined. Large stratigraphy thicknesses are explained.

  17. Cenozoic intracontinental deformation of the Kopeh Dagh Belt, Northeastern Iran

    NASA Astrophysics Data System (ADS)

    Chu, Yang; Wan, Bo; Chen, Ling; Talebian, Morteza

    2016-04-01

    Compressional intracontinental orogens represent large tectonic zones far from plate boundaries. Since intracontinental mountain belts cannot be framed in the conventional plate tectonics theory, several hypotheses have been proposed to account for the formations of these mountain belts. The far-field effect of collision/subduction at plate margins is now well accepted for the origin and evolution of the intracontinental crust thickening, as exemplified by the Miocene tectonics of central Asia. In northern Iran, the Binalud-Alborz mountain belt witnessed the Triassic tectonothermal events (Cimmerian orogeny), which are interpreted as the result of the Paleotethys Ocean closure between the Eurasia and Central Iran blocks. The Kopeh Dagh Belt, located to the north of the Binalud-Alborz Belt, has experienced two significant tectonic phases: (1) Jurassic to Eocene rifting with more than 7 km of sediments; and (2) Late Eocene-Early Oligocene to Quaternary continuous compression. Due to the high seismicity, deformation associated with earthquakes has received more and more attention; however, the deformation pattern and architecture of this range remain poorly understood. Detailed field observations on the Cenozoic deformation indicate that the Kopeh Dagh Belt can be divided into a western zone and an eastern zone, separated by a series of dextral strike-slip faults, i.e. the Bakharden-Quchan Fault System. The eastern zone characterized by km-scale box-fold structures, associated with southwest-dipping reverse faults and top-to-the NE kinematics. In contrast, the western zone shows top-to-the SW kinematics, and the deformation intensifies from NE to SW. In the northern part of this zone, large-scale asymmetrical anticlines exhibit SW-directed vergence with subordinate thrusts and folds, whereas symmetrical anticlines are observed in the southern part. In regard to its tectonic feature, the Kopeh Dagh Belt is a typical Cenozoic intracontinental belt without ophiolites or

  18. Paleoseismology of a newly discovered scarp in the Yakima fold-and-thrust belt, Kittitas County, Washington

    USGS Publications Warehouse

    Barnett, Elizabeth A.; Sherrod, Brian L.; Norris, Robert; Gibbons, Douglas

    2013-01-01

    The Boylston Mountains anticlinal ridge is one of several that are cored by rocks of the Columbia River Basalt Group and, with the interceding synclinal valleys, constitute the Yakima fold-and-thrust belt of central Washington. Lidar data acquired from the U.S. Army's Yakima Training Center reveal a prominent, northwest-side-up, 65°- to 70°-trending, 3- to 4-meter-high scarp that cuts across the western end of the Boylston Mountains, perpendicular to the mapped anticline. The scarp continues to the northeast from the ridge on the southern side of Park Creek and across the low ridges for a total length of about 3 kilometers. A small stream deeply incises its flood plain where it projects across Johnson Canyon. The scarp is inferred to be late Quaternary in age based on its presence on the modern landscape and the incised flood-plain sediments in Johnson Canyon. Two trenches were excavated across this scarp. The most informative of the two, the Horned Lizard trench, exposed shallow, 15.5-Ma Grande Ronde Basalt, which is split by a deep, wide crack that is coincident with the base of the scarp and filled with wedges of silty gravels that are interpreted to represent at least two generations of fault colluvium that offset a buried soil.

  19. Thick-skinned tectonics in a Late Cretaceous-Neogene intracontinental belt (High Atlas Mountains, Morocco): The flat-ramp fault control on basement shortening and cover folding

    NASA Astrophysics Data System (ADS)

    Fekkak, A.; Ouanaimi, H.; Michard, A.; Soulaimani, A.; Ettachfini, E. M.; Berrada, I.; El Arabi, H.; Lagnaoui, A.; Saddiqi, O.

    2018-04-01

    Most of the structural studies of the intracontinental High Atlas belt of Morocco have dealt with the central part of the belt, whose basement does not crop out. Here we study the Alpine deformation of the North Subatlas Zone, which is the part of the Western High Atlas (WHA) Paleozoic Massif that involves both Paleozoic basement units and remnants of their Mesozoic-Cenozoic cover formations. Our aim is to better constrain the geometry and kinematics of the basement faults during the Alpine shortening. Based on detail mapping, satellite imagery and field observations, we describe an array of sub-equatorial, transverse and oblique faults between the WHA Axial Zone and the Haouz Neogene basin. They define a mosaic of basement blocks pushed upon one another and upon the Haouz basement along the North Atlas Fault (NAF). The Axial Zone makes up the hanging-wall of the Adassil-Medinet Fault (AMF) south of this mosaic. The faults generally presents flat-ramp-flat geometry linked to the activation of multiple décollement levels, either within the basement where its foliation is subhorizontal or within favourable cover formations (Jurassic evaporites, Lower Cretaceous silty red beds, Upper Cretaceous evaporitic marls, Neogene basal argillites). The occurrence of the North Atlas detachment (NAD) allowed folded pop-up units to develop in front of the propagating NAF. Shortening began as early as the Campanian-Maastrichtian along the AMF. The direction of the maximum horizontal stress rotated from NNE-SSW to NNW-SSE from the Maastrichtian-Paleocene to the Neogene. The amount of shortening reaches 20% in the Azegour transect. This compares with the shortening amount published for the central-eastern High Atlas, suggesting that similar structures characterize the Paleozoic basement all along the belt. The WHA thick-skinned tectonics evokes that of the frontal Sevier belt and of the external Western Alps, although with a much minor pre-inversion burial.

  20. Early paleozoic gabbro-amphibolites in the structure of the Bureya Terrane (eastern part of the Central Asian Fold Belt): First geochronological data and tectonic position

    NASA Astrophysics Data System (ADS)

    Smirnov, Yu. V.; Sorokin, A. A.; Kudryashov, N. M.

    2012-07-01

    Resulting from U-Pb geochronological study, it has been found that the gabbro-amphibolites composing the Bureya (Turan) Terrane in the eastern part of the Central Asian Fold Belt are Early Paleozoic (Early Ordovician; 455 ± 1.5 Ma) in age rather than Late Proterozoic as was believed earlier. The gabbro-amphibolites and associated metabasalts are close to tholeiites of the intraoceanic island arcs in terms of the geochemical properties. It is suggested that the tectonic block composed of these rocks was initially a seafloor fragment that divided the Bureya and Argun terranes in the Early Paleozoic and was later tectonically incorporated into the modern structure of the Bureya Terrane as a result of Late Paleozoic and Mesozoic events.

  1. Control of syntectonic erosion and sedimentation on kinematic evolution of a multidecollement fold and thrust zone: Analogue modeling of folding in the southern subandean of Bolivia

    NASA Astrophysics Data System (ADS)

    Darnault, Romain; Callot, Jean-Paul; Ballard, Jean-François; Fraisse, Guillaume; Mengus, Jean-Marie; Ringenbach, Jean-Claude

    2016-08-01

    Several analogue modeling studies have been conducted during the past fifteen years with the aim to discuss the effects of sedimentation and erosion on Foreland Fold and Thrust Belt, among which a few have analyzed these processes at kilometric scale (Malavieille et al., 1993; Nalpas et al., 1999; Barrier et al., 2002; Pichot and Nalpas, 2009). The influence of syn-deformation sedimentation and erosion on the structural evolution of FFTB has been clearly demonstrated. Here, we propose to go further in this approach by the study of a more complex system with a double decollement level. The natural study case is the Bolivian sub-Andean thrust and fold belt, which present all the required criteria, such as the double decollement level. A set of analogue models performed under a CT-scan have been used to test the influence of several parameters on a fold and thrust belt system, among which: (i) the spatial variation of the sediment input, (ii) the spatial variation of the erosion rate, (iii) the relative distribution of sedimentation between foreland and hinterland. These experiments led to the following observations: 1. The upper decollement level acts as a decoupling level in case of increased sedimentation rate: it results in the verticalization of the shallower part (above the upper decollement level), while the deeper parts are not impacted. 2. Similarly, the increase of the erosion rate involves the uplift of the deeper part (below the upper decollement level), whereas the shallower parts are not impacted. 3. A high sedimentation rate in the foreland involves a fault and fold vergence reversal, followed by a back-thrusting of the shallower part. 4. A high sedimentation rate in the hinterland favours thrust development toward the foreland in the shallower parts.

  2. Synfolding magnetization in the Jurassic Preuss Sandstone, Wyoming- Idaho-Utah thrust belt

    USGS Publications Warehouse

    Hudson, M.R.; Reynolds, R.L.; Fishman, N.S.

    1989-01-01

    The Jurassic Preuss Sandstone, exposed in five thrust plates of the Wyoming-Idaho-Utah thrust belt, carried directions of remanent magnetization that group most tightly after only partial unfolding. Field, petrographic, and rock magnetic evidence indicates that the carrier of this magnetization is detrital, low-Ti titanomagnetite. The detrital titanomagnetite was remagnetized at low temperatures (75??-150??C) probably completely during folding. Anisotropy of magnetic susceptibility and petrographic observations indicate that the detrital titanomagnetite has been affected by tectonic strain. The locus of acquisition of synfolding magnetization in the Preuss migrated in conjunction with deformation in the thrust belt. A model is presented in which synfolding magnetization was acquired during cooling and folding as strata moved up thrust ramps. A lack of reverse-polarity directions remains a puzzling feature of the remanence. -from Authors

  3. Biomechanics of 4-point seat belt systems in frontal impacts.

    PubMed

    Rouhana, Stephen W; Bedewi, Paul G; Kankanala, Sundeep V; Prasad, Priya; Zwolinski, Joseph J; Meduvsky, Alex G; Rupp, Jonathan D; Jeffreys, Thomas A; Schneider, Lawrence W

    2003-01-01

    The biomechanical behavior of 4-point seat belt systems was investigated through MADYMO modeling, dummy tests and post mortem human subject tests. This study was conducted to assess the effect of 4-point seat belts on the risk of thoracic injury in frontal impacts, to evaluate the ability to prevent submarining under the lap belt using 4-point seat belts, and to examine whether 4-point belts may induce injuries not typically observed with 3-point seat belts. The performance of two types of 4-point seat belts was compared with that of a pretensioned, load-limited, 3-point seat belt. A 3-point belt with an extra shoulder belt that "crisscrossed" the chest (X4) appeared to add constraint to the torso and increased chest deflection and injury risk. Harness style shoulder belts (V4) loaded the body in a different biomechanical manner than 3-point and X4 belts. The V4 belt appeared to shift load to the clavicles and pelvis and to reduce traction of the shoulder belt across the chest, resulting in a reduction in chest deflection by a factor of two. This is associated with a 5 to 500-fold reduction in thoracic injury risk, depending on whether one assumes 4-point belts apply concentrated or distributed load. In four of six post mortem human subjects restrained by V4 belts during 40 km/h sled tests, chest compression was zero or negative and rib fractures were nearly eliminated. Submarining was not observed in any test with post mortem human subjects. Though lumbar, sacral and pelvic injuries were noted, they are believed to be due to the artificial restraint environment (no knee bolsters, instrument panels, steering systems or airbags). While they show significant potential to reduce thoracic injury risk, there are still many issues to be resolved before 4-point belts can be considered for production vehicles. These issues include, among others, potential effects on hard and soft neck tissues, of interaction with inboard shoulder belts in farside impacts and potential

  4. Overdrive and Edge as Refiners of "Belting"?: An Empirical Study Qualifying and Categorizing "Belting" Based on Audio Perception, Laryngostroboscopic Imaging, Acoustics, LTAS, and EGG.

    PubMed

    McGlashan, Julian; Thuesen, Mathias Aaen; Sadolin, Cathrine

    2017-05-01

    We aimed to study the categorizations "Overdrive" and "Edge" from the pedagogical method Complete Vocal Technique as refiners of the often ill-defined concept of "belting" by means of audio perception, laryngostroboscopic imaging, acoustics, long-term average spectrum (LTAS), and electroglottography (EGG). This is a case-control study. Twenty singers were recorded singing sustained vowels in a "belting" quality refined by audio perception as "Overdrive" and "Edge." Two studies were performed: (1) a laryngostroboscopic examination using a videonasoendoscopic camera system (Olympus) and the Laryngostrobe program (Laryngograph); (2) a simultaneous recording of the EGG and acoustic signals using Speech Studio (Laryngograph). The images were analyzed based on consensus agreement. Statistical analysis of the acoustic, LTAS, and EGG parameters was undertaken using the Student paired t test. The two modes of singing determined by audio perception have visibly different laryngeal gestures: Edge has a more constricted setting than that of Overdrive, where the ventricular folds seem to cover more of the vocal folds, the aryepiglottic folds show a sharper edge in Edge, and the cuneiform cartilages are rolled in anteromedially. LTAS analysis shows a statistical difference, particularly after the ninth harmonic, with a coinciding first formant. The combined group showed statistical differences in shimmer, harmonics-to-noise ratio, normalized noise energy, and mean sound pressure level (P ≤ 0.05). "Belting" sounds can be categorized using audio perception into two modes of singing: "Overdrive" and "Edge." This study demonstrates consistent visibly different laryngeal gestures between these modes and with some correspondingly significant differences in LTAS, EGG, and acoustic measures. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  5. Seismic Expression of Fault Related Folding in Southeastern Turkey

    NASA Astrophysics Data System (ADS)

    Beauchamp, W.; McDonald, D.

    2009-12-01

    Weldon Beauchamp, and David McDonald,TransAtlantic Petroleum Corp. 5910 N. Central Expressway, Suite 1755, Dallas, TX 75206 weldon@tapcor.com, 214-395-7125 The Zagros fold belt extends northwest from Iran and Iraq into southeastern Turkey. Large scale fault related folds control the topography of this region and the path of the Tigris river. Large surface anticlines in the Zagros Mountains provide traps for giant oil and gas fields in Iran and Iraq. Similar scale folds extend into southeast Turkey. These southward verging fault related folds are believed to detach in the Paleozoic. Borehole data, surface geological maps, satellite data and digital topographic models were used to create models to constrain structure at depth. Structural modeling of these folds was used to design, acquire and process seismic reflection data in the region. The seismic reflection data confirmed the presence of asymmetrical, south verging complex fault related folding. Faults related to these folds detach in the Lower Ordovician to Cambrian age shales. These folds are believed to form doubly plunging structures that fold Tertiary through Paleozoic age rocks forming multiple levels of possible hydrocarbon entrapment.

  6. Audit of mammography requests in Abakaliki, South-East Nigeria.

    PubMed

    Eni, U E; Ekwedigwe, K C; Sunday-Adeoye, I; Daniyan, Abc; Isikhuemen, M E

    2017-03-07

    Breast cancer is the leading cancer in women in both developed and developing countries. Screening mammography detects breast cancer even before a lump can be palpated, with better prognosis. The introduction of mammographic technique for screening breast cancer, despite its importance, has been slow to adopt and virtually non-existent in many parts of Sub-Saharan Africa including Nigeria. For this reason, the indications of mammography have not been well defined in our setting. The aim of this study was to audit our mammography requests, with a view to improving its application in our setting. This is a descriptive study carried out on 69 female patients who had mammography at the National Obstetric Fistula Centre, Abakaliki, from January 2014 to December 2015. Findings on clinical examination were entered in a proforma. Mammography was performed in craniocaudal and mediolateral views using the Lorad M-IV (film-screen) mammography machine. Data was analysed using the Statistical Package for Social Sciences (SPSS) version 21. All 69 patients were females. Their mean age was 42.1 ± 11 years. Majority of the patients (69.6%) were between 30 and 49 years. The commonest indication for mammography was breast lump which was found in 46 patients (66.7%). Breast pain was present in 36 (52.2%) of patients. The different Breast Imaging Reporting and Data System (BIRADS) categories were BIRADS 0: 20 (28.99%), BIRADS 1: 8 (11.59%), BIRADS 2: 9 (13.04%), BIRADS 3: 4 (5.8%), BIRADS 4: 19 (27.54%) and BIRADS 5: 9 (13.04%). Diagnostic mammography remains the commonest indication for mammography in our setting. Public awareness, poverty reduction and ready availability of mammography facilities are required to improve screening mammography in our setting.

  7. Neotectonics and structure of the Himalayan deformation front in the Kashmir Himalaya, India: Implication in defining what controls a blind thrust front in an active fold-thrust belt

    NASA Astrophysics Data System (ADS)

    Gavillot, Y. G.; Meigs, A.; Yule, J. D.; Rittenour, T. M.; Malik, M. O. A.

    2014-12-01

    Active tectonics of a deformation front constrains the kinematic evolution and structural interaction between the fold-thrust belt and most-recently accreted foreland basin. In Kashmir, the Himalayan Frontal thrust (HFT) is blind, characterized by a broad fold, the Suruin-Mastargh anticline (SMA), and displays no emergent faults cutting either limb. A lack of knowledge of the rate of shortening and structural framework of the SMA hampers quantifying the earthquake potential for the deformation front. Our study utilized the geomorphic expression of dated deformed terraces on the Ujh River in Kashmir. Six terraces are recognized, and three yield OSL ages of 53 ka, 33 ka, and 0.4 ka. Vector fold restoration of long terrace profiles indicates a deformation pattern characterized by regional uplift across the anticlinal axis and back-limb, and by fold limb rotation on the forelimb. Differential uplift across the fold trace suggests localized deformation. Dip data and stratigraphic thicknesses suggest that a duplex structure is emplaced at depth along the basal décollement, folding the overlying roof thrust and Siwalik-Muree strata into a detachment-like fold. Localized faulting at the fold axis explains the asymmetrical fold geometry. Folding of the oldest dated terrace, suggest that rock uplift rates across the SMA range between 2.0-1.8 mm/yr. Assuming a 25° dipping ramp for the blind structure on the basis of dip data constraints, the shortening rate across the SMA ranges between 4.4-3.8 mm/yr since ~53 ka. Of that rate, ~1 mm/yr is likely absorbed by minor faulting in the near field of the fold axis. Given that Himalaya-India convergence is ~18.8-11 mm/yr, internal faults north of the deformation front, such as the Riasi thrust absorbs more of the Himalayan shortening than does the HFT in Kashmir. We attribute a non-emergent thrust at the deformation front to reflect deformation controlled by pre-existing basin architecture in Kashmir, in which the thick succession

  8. Evidence for a complex archean deformational history; southwestern Michipicoten Greenstone Belt, Ontario

    NASA Technical Reports Server (NTRS)

    Mcgill, George E.; Shrady, Catherine H.

    1986-01-01

    The Michipicoten Greenstone Belt extends for about 150 km ENE from the northeastern angle of Lake Superior. In common with many other Archean greenstone belts, it is characterized by generally steep bedding dips and a distribution of major lithologic types suggesting a crudely synclinal structure for the belt as a whole. Detailed mapping and determination of structural sequence demonstrates that the structure is much more complex. The Archean history of the belt includes formation of at least three regionally significant cleavages, kilometer-scale overturning, extensive shearing, and diabase intrusion. Most well defined, mappable 'packages' of sedimentary rocks appear to be bounded by faults. These faults were active relatively early in the structural history of the belt, when extensive overturning also occurred. Steepening of dips, NW-SE shortening, development of steep NE cleavage, and pervasive shearing all postdate the early faulting and the regional overturning, obscuring much of the detail needed to define the geometry of the earlier structures. The results obtained so far suggest, however, that the Michipicoten Greenstone Belt underwent an early stage of thrusting and associated isoclinal folding, probably in a convergent tectonic environment.

  9. Architecture of orogenic belts and convergent zones in Western Ishtar Terra, Venus

    NASA Technical Reports Server (NTRS)

    Head, James W.; Vorderbruegge, R. W.; Crumpler, L. S.

    1989-01-01

    Linear mountain belts in Ishtar Terra were recognized from Pioneer-Venus topography, and later Arecibo images showed banded terrain interpreted to represent folds. Subsequent analyses showed that the mountains represented orogenic belts, and that each had somewhat different features and characteristics. Orogenic belts are regions of focused shortening and compressional deformation and thus provide evidence for the nature of such deformation, processes of crustal thickening (brittle, ductile), and processes of crustal loss. Such information is important in understanding the nature of convergent zones on Venus (underthrusting, imbrication, subduction), the implications for rates of crustal recycling, and the nature of environments of melting and petrogenesis. The basic elements of four convergent zones and orogenic belts in western Ishtar Terra are identified and examined, and then assess the architecture of these zones (the manner in which the elements are arrayed), and their relationships. The basic nomenclature of the convergent zones is shown.

  10. Influence of tectonic folding on rockfall susceptibility, American Fork Canyon, Utah, USA

    USGS Publications Warehouse

    Coe, J.A.; Harp, E.L.

    2007-01-01

    We examine rockfall susceptibility of folded strata in the Sevier fold-thrust belt exposed in American Fork Canyon in north-central Utah. Large-scale geologic mapping, talus production data, rock-mass-quality measurements, and historical rockfall data indicate that rockfall susceptibility is correlated with limb dip and curvature of the folded, cliff-forming Mississippian limestones. On fold limbs, rockfall susceptibility increases as dip increases. This relation is controlled by several factors, including an increase in adverse dip conditions and apertures of discontinuities, and shearing by flexural slip during folding that has reduced the friction angles of discontinuities by smoothing surface asperities. Susceptibility is greater in fold hinge zones than on adjacent limbs primarily because there are greater numbers of discontinuities in hinge zones. We speculate that susceptibility increases in hinge zones as fold curvature becomes tighter.

  11. Lithostratigraphy and structure of the early Archaean Doolena Gap Greenstone Belt, East Pilbara Terrane (EPT), Western Australia

    NASA Astrophysics Data System (ADS)

    Wiemer, D.; Schrank, C. E.; Murphy, D. T.

    2014-12-01

    We present a detailed lithostratigraphic and structural analysis of the Archean Doolena Gap greenstone belt to shed light on the tectonic evolution of the EPT. The study area is divided into four structural domains: i) marginal orthogneisses of the MGC (Muccan Granitoid Complex), ii) a dominantly mafic mylonitic shear zone (South Muccan Shear Zone, SMSZ) enveloping the MGC, iii) a Central Fold Belt of dominantly mafic greenschists (CFB), and iv) a lower greenschist- to sub-greenschist southern domain. Toward the dome margin, abrupt increases in deformation intensity occur across domain boundaries. Domain boundaries and intra-domain shear zones are marked by significant carbonate +/- quartz alteration and high-strain non-coaxial deformation with dome-up kinematics. The southern domain comprises pillow basalts of the Mount Ada Formation (MAF), conformably overlain by clastic sediments and minor pillow basalts of the Duffer Formation (DF). The MAF and DF are overlain by an up to 1km thick package of quartzite (Strelley Pool Formation) across an angular unconformity. Isoclinal folds (F2) within the CFB to the North deform an early foliation (S1) within dominantly mafic schists and associated carbonate veins. F2 folds are preserved within lozenges that are parallel to the axial planes of F2 folds in a regional E-W trending foliation (S2) and to the SMSZ. Lozenges are often bound by zones of significant carbonate alteration. The lozenges are folded recumbently (F3), with sub-vertical fold axes pointing towards the dome. The F3 axes are parallel to mineral stretching lineations on S2 indicating dome-up movement. The entire belt is cut by late NE-SW-striking faults that exhibit dominantly brittle deformation in the southern domain but ductile drag folding (F4) in the CFB. Therefore, the southern domain must have overlain the CFB during this D4 event. We propose a protracted structural history of the greenstone belt where successive deformation events relate to the episodic

  12. Geometry and kinematics of the fold-thrust belt and structural evolution of the major Himalayan fault zones in the Darjeeling -- Sikkim Himalaya, India

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Kathakali

    The Darjeeling-Sikkim Himalaya lies in the eastern part of the Himalayan fold-thrust belt (FTB) in a zone of high arc-perpendicular convergence between the Indian and Eurasian plates. In this region two distinct faults form the Main Central thrust (MCT), the structurally higher MCT1 and the lower MCT2; both these faults have translated the Greater Himalayan hanging wall rocks farther towards the foreland than in the western Himalaya. The width of the sub-MCT Lesser Himalayan rocks progressively decreases from the western Himalaya to this part of the eastern Himalaya, and as a result, the width of the FTB is narrower in this region compared to the western Himalaya. Our structural analysis shows that in the Darjeeling-Sikkim Himalaya the sub-MCT Lesser Himalayan duplex is composed of two duplex systems and has a more complex geometry than in the rest of the Himalayan fold-thrust belt. The structurally higher Dating duplex is a hinterland-dipping duplex; the structurally lower Rangit duplex varies in geometry from a hinterland-dipping duplex in the north to an antiformal stack in the middle and a foreland-dipping duplex in the south. The MCT2 is the roof thrust of the Daling duplex and the Ramgarh thrust is the roof thrust of the Rangit duplex. In this region, the Ramgarh thrust has a complex structural history with continued reactivation during footwall imbrication. The foreland-dipping component of the Rangit duplex, along with the large displacement associated with the reactivation of the Ramgarh thrust accounts for the large translation of the MCT sheets in the Darjeeling-Sikkim Himalaya. The growth of the Lesser Himalayan duplex modified the final geometry of the overlying MCT sheets, resulting in a plunge culmination that manifests itself as a broad N-S trending "anticline" in the Darjeeling-Sikkim Himalaya. This is not a "river anticline" as its trace lies west of the Teesta river. A transport parallel balanced cross section across this region has accommodated

  13. Andean Basin Evolution Associated with Hybrid Thick- and Thin-Skinned Deformation in the Malargüe Fold-Thrust Belt, Western Argentina

    NASA Astrophysics Data System (ADS)

    Horton, B. K.; Fuentes, F.

    2015-12-01

    Andean deformation and basin evolution in the Malargüe fold-thrust belt of western Argentina (34-36°S) has been dominated by basement faults influenced by pre-existing Mesozoic rift structures of the hydrocarbon-rich Neuquen basin. However, the basement structures diverge from classic inversion structures, and the associated retroarc basin system shows a complex Mesozoic-Cenozoic history of mixed extension and contraction, along with an enigmatic early Cenozoic stratigraphic hiatus. New results from balanced structural cross sections (supported by industry seismic, well data, and surface maps), U-Pb geochronology, and foreland deposystem analyses provide improved resolution to examine the duration and kinematic evolution of Andean mixed-mode deformation. The basement structures form large anticlines with steep forelimbs and up to >5 km of structural relief. Once the propagating tips of the deeper basement faults reached cover strata, they fed slip to shallow thrust systems that were transported in piggyback fashion by newly formed basement structures, producing complex structural relationships. Detrital zircon U-Pb ages for the 5-7 km-thick basin fill succession reveal shifts in sedimentation pathways and accumulation rates consistent with (1) local basement sources during Early-Middle Jurassic back-arc extension, (2) variable cratonic and magmatic arc sources during Late Jurassic-Cretaceous postrift thermal subsidence, and (3) Andean arc and thrust-belt sources during irregular Late Cretaceous-Cenozoic shortening. Although pulses of flexural subsidence can be attributed to periods of fault reactivation (inversion) and geometrically linked thin-skinned thrusting, fully developed foreland basin conditions were only achieved in Late Cretaceous and Neogene time. Separating these two contractional episodes is an Eocene-lower Miocene (roughly 40-20 Ma) depositional hiatus within the Cenozoic succession, potentially signifying forebulge passage or neutral to

  14. Strain analysis in the Sanandaj-Sirjan HP-LT Metamorphic Belt, SW Iran: Insights from small-scale faults and associated drag folds

    NASA Astrophysics Data System (ADS)

    Sarkarinejad, Khalil; Keshavarz, Saeede; Faghih, Ali

    2015-05-01

    This study is aimed at quantifying the kinematics of deformation using a population of drag fold structures associated with small-scale faults in deformed quartzites from Seh-Ghalatoun area within the HP-LT Sanandaj-Sirjan Metamorphic Belt, SW Iran. A total 30 small-scale faults in the quartzite layers were examined to determine the deformation characteristics. Obtained data revealed α0 (initial fault angle) and ω (angle between flow apophyses) are equal to 83° and 32°, respectively. These data yield mean kinematic vorticity number (Wm) equal to 0.79 and mean finite strain (Rs) of 2.32. These results confirm the relative contribution of ∼43% pure shear and ∼57% simple shear components, respectively. The strain partitioning inferred from this quantitative analysis is consistent with a sub-simple or general shear deformation pattern associated with a transpressional flow regime in the study area as a part of the Zagros Orogen. This type of deformation resulted from oblique convergence between the Afro-Arabian and Central-Iranian plates.

  15. Controls on size and occurrence of the largest sub-aerial landslide on Earth: Seymareh (Saidmarreh) landslide, Zagros fold-thrust belt, Iran

    NASA Astrophysics Data System (ADS)

    Roberts, N. J.; Evans, S. G.

    2009-12-01

    Gigantic (> 1 Gm3) landslides are high-magnitude, low-frequency extremes of mass movements. They are important factors in topographic evolution and hazard in mountain regions due to their magnitude. However, few examples exist for study because of their infrequency. Consequently, controls on the location and size gigantic landslides remain poorly understood. Re-examination of the Seymareh (Saidmarreh) rock avalanche, Zagros fold-thrust belt, shows it to be the largest sub-aerial landslide on Earth (initial failure volume 38 Gm3), thus representing the upper magnitude limit for terrestrial landslides. Detailed examination of the source area (including orbital remote sensing, geotechnical investigation and structural mapping) provides new insights into controls on the size and mobility of gigantic landslides. The gigantic Early Holocene rockslide initiated on the northeast limb of Kabir Kuh, the largest anticline in the Zagros fold-thrust belt, and involved the simultaneous failure of a rock mass measuring 15 km along strike. The rockslide transformed into a rock avalanche that ran-out 19.0 km, filling two adjacent valleys and overtopping an intervening low mountain ridge. The failure involved 220 m of competent jointed limestone (Asmari Formation) underlain by 580 m of weaker mudrock-dominated units. Geologic structure, geomechanical strength and topography of the source slope strongly controlled failure initiation. Extreme landslide dimensions resulted in part from extensive uniform pre-failure stability, produced by structural and topographic features related to the large scale of the Kabir Kuh anticline. High continuity bedding planes determined the large lateral extent along strike. Bedding normal joints, the breached nature of the anticline and fluvial undercutting at the slope toe accommodated expansive lateral, headscarp and toe release, respectively, necessary for extensive failure. Geomechanically weak units at depth aided the penetration of the failure

  16. Seismic images of the Brooks Range fold and thrust belt, Arctic Alaska, from an integrated seismic reflection/refraction experiment

    USGS Publications Warehouse

    Levander, A.; Fuis, G.S.; Wissinger, E.S.; Lutter, W.J.; Oldow, J.S.; Moore, Thomas E.

    1994-01-01

    We describe results of an integrated seismic reflection/refraction experiment across the Brooks Range and flanking geologic provinces in Arctic Alaska. The seismic acquisition was unusual in that reflection and refraction data were collected simultaneously with a 700 channel seismograph system deployed numerous times along a 315 km profile. Shot records show continuous Moho reflections from 0-180 km offset, as well as numerous upper- and mid-crustal wide-angle events. Single and low-fold near-vertical incidence common midpoint (CMP) reflection images show complex upper- and middle-crustal structure across the range from the unmetamorphosed Endicott Mountains allochthon (EMA) in the north, to the metamorphic belts in the south. Lower-crustal and Moho reflections are visible across the entire reflection profile. Travel-time inversion of PmP arrivals shows that the Moho, at 33 km depth beneath the North Slope foothills, deepens abruptly beneath the EMA to a maximum of 46 km, and then shallows southward to 35 km at the southern edge of the range. Two zones of upper- and middle-crustal reflections underlie the northern Brooks Range above ~ 12-15 km depth. The upper zone, interpreted as the base of the EMA, lies at a maximum depth of 6 km and extends over 50 km from the range front to the north central Brooks Range where the base of the EMA outcrops above the metasedimentary rocks exposed in the Doonerak window. We interpret the base of the lower zone, at ~ 12 km depth, to be from carbonate rocks above the master detachment upon which the Brooks Range formed. The seismic data suggest that the master detachment is connected to the faults in the EMA by several ramps. In the highly metamorphosed terranes south of the Doonerak window, the CMP section shows numerous south-dipping events which we interpret as a crustal scale duplex involving the Doonerak window rocks. The basal detachment reflections can be traced approximately 100 km, and dip southward from about 10-12 km

  17. Tectono-sedimentary evolution of salt controlled minibasin in a fold-an-thrust belt setting Example from the Sivas Basin Turkey and physical model.

    NASA Astrophysics Data System (ADS)

    Kergaravat, Charlie; Ribes, Charlotte; Darnault, Romain; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2017-04-01

    The aim of this study is to present the influence of regional shortening on the evolution of a minibasin province and the associated foldbelt geometry based on a natural example, the Sivas Basin, then compared to a physical experiment. The Sivas Basin in the Central Anatolian Plateau (Turkey) is a foreland fold-and-thrust belt, displaying in the central part a typical wall and basin province characterized by spectacularly exposed minibasins, separated by continuous steep-flanked walls and diapirs over a large area (45x25 km). The advance of the orogenic wedge is expressed within the second generation of minibasins by a shortening-induced squeezing of diapirs. Network of walls and diapirs evolve form polygonal to linear pattern probably induced by the squeezing of pre-existing evaporite walls and diapirs, separating linear primary minibasins. From base to top of secondary minibasins, halokinetic structures seem to evolve from small-scale objects along diapir flanks, showing hook and wedges halokinetic sequences, to large stratigraphic wedging, megaflap and salt sheets. Minibasins show progressively more linear shape at right angle to the regional shortening and present angular unconformities along salt structures related to the rejuvenation of pre-existing salt diapirs and walls probably encouraged by the shortening tectonic regime. The advance of the fold-and-thrust belts during the minibasins emplacement is mainly expressed during the late stage of minibasins development by a complex polygonal network of small- and intermediate-scale tectonic objects: (1) squeezed evaporite walls and diapirs, sometimes thrusted forming oblique or vertical welds, (2) allochthonous evaporite sheets, (3) thrusts and strike-slip faults recording translation and rotation of minibasins about vertical axis. Some minibasins are also tilted, with up to vertical position, associated with both the salt expulsion during minibasins sinking, recorded by large stratigraphic wedge, and the late

  18. The mechanics of fault-bend folding and tear-fault systems in the Niger Delta

    NASA Astrophysics Data System (ADS)

    Benesh, Nathan Philip

    This dissertation investigates the mechanics of fault-bend folding using the discrete element method (DEM) and explores the nature of tear-fault systems in the deep-water Niger Delta fold-and-thrust belt. In Chapter 1, we employ the DEM to investigate the development of growth structures in anticlinal fault-bend folds. This work was inspired by observations that growth strata in active folds show a pronounced upward decrease in bed dip, in contrast to traditional kinematic fault-bend fold models. Our analysis shows that the modeled folds grow largely by parallel folding as specified by the kinematic theory; however, the process of folding over a broad axial surface zone yields a component of fold growth by limb rotation that is consistent with the patterns observed in natural folds. This result has important implications for how growth structures can he used to constrain slip and paleo-earthquake ages on active blind-thrust faults. In Chapter 2, we expand our DEM study to investigate the development of a wider range of fault-bend folds. We examine the influence of mechanical stratigraphy and quantitatively compare our models with the relationships between fold and fault shape prescribed by the kinematic theory. While the synclinal fault-bend models closely match the kinematic theory, the modeled anticlinal fault-bend folds show robust behavior that is distinct from the kinematic theory. Specifically, we observe that modeled structures maintain a linear relationship between fold shape (gamma) and fault-horizon cutoff angle (theta), rather than expressing the non-linear relationship with two distinct modes of anticlinal folding that is prescribed by the kinematic theory. These observations lead to a revised quantitative relationship for fault-bend folds that can serve as a useful interpretation tool. Finally, in Chapter 3, we examine the 3D relationships of tear- and thrust-fault systems in the western, deep-water Niger Delta. Using 3D seismic reflection data and new

  19. Beginning of foreland subsidence in the Columbian-Sevier belts, southern Canada and northwest Montana

    NASA Astrophysics Data System (ADS)

    Gillespie, Janice M.; Heller, Paul L.

    1995-08-01

    Subsidence analysis and geometry of Jurassic-Cretaceous foreland strata in northwestern Montana and southern Alberta and British Columbia suggest that loading by the fold-thrust belt in Canada began as much as 40 m.y. earlier than in Montana. In Canada, early foreland basin deposits are Late Jurassic age, thicken rapidly westward, and are restricted to a narrow belt within 30 km of the thrust belt. In western Montana, contemporaneous deposits are widespread and do not increase markedly in thickness toward the thrust belt. The unconformity overlying these deposits also changes from Canada, where it is angular, to a disconformity in western Montana near Great Falls. Between these two areas, foreland geometry is transitional over a distance of <250 km. Beyond the transition zone, early foreland basin geometries are broadly consistent, showing Late Jurassic foreland subsidence in southern Canada and Early Cretaceous initial subsidence in the United States.

  20. Laterally bendable belt conveyor

    DOEpatents

    Peterson, William J.

    1985-01-01

    An endless, laterally flexible and bendable belt conveyor particularly adapted for coal mining applications in facilitating the transport of the extracted coal up- or downslope and around corners in a continuous manner is disclosed. The conveying means includes a flat rubber belt reinforced along the middle portion thereof along which the major portion of the belt tension is directed so as to cause rotation of the tubular shaped belt when trammed around lateral turns thus preventing excessive belt bulging distortion between adjacent belt supports which would inhibit belt transport. Pretension induced into the fabric reinforced flat rubber belt by conventional belt take-up means supports the load conveyed when the belt conveyor is making lateral turns. The carrying and return portions of the belt are supported and formed into a tubular shape by a plurality of shapers positioned along its length. Each shaper is supported from above by a monorail and includes clusters of idler rollers which support the belt. Additional cluster rollers in each shaper permit the belt supporting roller clusters to rotate in response to the belt's operating tension imposed upon the cluster rollers by induced lateral belt friction forces. The freely rotating roller clusters thus permit the belt to twist on lateral curves without damage to itself while precluding escape of the conveyed material by effectively enclosing it in the tube-shaped, inner belt transport length.

  1. Pervasive Palaeogene remagnetization of the central Taurides fold-and-thrust belt (southern Turkey) and implications for rotations in the Isparta Angle

    NASA Astrophysics Data System (ADS)

    Meijers, Maud J. M.; van Hinsbergen, Douwe J. J.; Dekkers, Mark J.; Altıner, Demir; Kaymakcı, Nuretdin; Langereis, Cor G.

    2011-03-01

    The Turkish Anatolide-Tauride block rifted away from the northern margin of Gondwana in the Triassic, which gave way to the opening of the southern Neo-Tethys. By the late Palaeocene to Eocene, it collided with the southern Eurasian margin, leading to the closure of the northern Neo-Tethys ocean. To determine the position of the Anatolide-Tauride block with respect to the African and Eurasian margin we carried out a palaeomagnetic study in the central Taurides belt, which constitutes the eastern limb of the Isparta Angle. The sampled sections comprise Carboniferous to Palaeocene rocks (mainly limestones). Our data suggest that all sampled rocks are remagnetized during the late Palaeocene to Eocene phase of folding and thrusting event, related to the collision of the Anatolide-Tauride block with Eurasia. To further test the possibility of remagnetization, we use a novel end-member modelling approach on 174 acquired isothermal remanent magnetization (IRM) curves. We argue that the preferred three end-member model confirms the proposed remagnetization of the rocks. Comparing our data to the post-Eocene declination pattern in the central Tauride belt, we conclude that our clockwise rotations are in agreement with data from other studies. After combining our results with previously published data from the Isparta Angle (that includes our study area), we have reasons to cast doubt on the spatial and temporal extent of an earlier reported early to middle Miocene remagnetization event. We argue that the earlier reported remagnetized directions from Triassic rocks—in tilt corrected coordinates—from the southwestern Antalya Nappes (western Taurides), are in good agreement with other studies from the area that show a primary origin of their characteristic remanent magnetization. This implies that we document a clockwise rotation for the southwestern Antalya Nappes since the Triassic that is remarkably similar to the post-Eocene (˜40°) rotation of the central Taurides

  2. Analogue modeling of 3-D structural segmentation in fold-and-thrust belts: interactions between frictional and viscous provinces in foreland basins

    NASA Astrophysics Data System (ADS)

    Borderie, Sandra; Graveleau, Fabien; Witt, César; Vendeville, Bruno C.

    2016-04-01

    Accretionary wedges are generally segmented both across and along strike because of diverse factors including tectonic and stratigraphic inheritance. In fold-and-thrust belts, along-strike stratigraphic changes in the foreland sequence are classically observed and cause a curvature of the deformation front. Although the parameters controlling this curvature are well documented, the structural interactions and mutual influences between adjacent provinces are much less analyzed. To investigate this question, we deformed analogue models in a compressional box equipped with digital cameras and a topographic measurement apparatus. Models where shortened above a basal frictional detachment (glass microbeads) and segmentation was tested by having a region in which we added an interbedded viscous level (silicone polymer) within the sedimentary cover (dry sand). By changing the number (2 or 3) and the relative width of the purely frictional and viscous provinces, our goal was to characterize geometrically and kinematically the interactions between the viscous and the purely frictional provinces. We used a commercial geomodeller to generate 3-D geometrical models. The results indicate that regardless of the relative width of the purely frictional vs. viscous provinces, the deformation style in the frictional province is not influenced by the presence of the adjacent viscous province. On the contrary, the structural style and the deformation kinematics in the viscous province is significantly impacted by the presence or absence of an adjacent purely frictional province. At first order, the deformation style in the viscous province depends on its width, and three structural styles can be defined along strike. Far from the frictional area, structures are primarily of salt-massif type, and they do not seem to be influenced by the frictional wedge province. Towards the frictional province, deformation changes gradually to a zone of purely forethrusts (foreland verging), and

  3. Structural development and stress evolution of an arcuate fold-and-thrust system, southwestern Greater Caucasus, Republic of Georgia

    NASA Astrophysics Data System (ADS)

    Tibaldi, A.; Bonali, F. L.; Russo, E.; Pasquarè Mariotto, F. A.

    2018-05-01

    The southern front of the Greater Caucasus is quite rectilinear in plan view, with the exception of part of the Rioni Basin, where marine and continental deposits of Cretaceous-Neogene age were locally folded and uplifted; this resulted in the formation of an arcuate fold-and-thrust system that extends 45 km into the foreland. Although previous studies suggested that this system has developed only since Miocene times, our new detailed and systematic field measurements of brittle and ductile structures show a very complex history, consisting in four main phases of brittle deformation and folding, dated from Eocene to Quaternary times. We collected microtectonic data at 248 faults, and calculated the related paleostress tensors. The first two phases which we document here, predated folding and were characterised by dominant transcurrent faulting and subordinate reverse motions; the greatest principal stress σ1 was perpendicular and later parallel to the mountain belt. Afterwards, NW-SE, E-W and NE-SW trending, south-vergent asymmetrical folds started to form. In the western sector of the study area, folds are sinuous in plan view, whereas to the east they show a left-stepping, en-échelon geometry. Another two, brittle deformation phases took place after the folding, due to the activity of a set of right-lateral, strike-slip faults that strike NW-SE and NE-SW, respectively, as well as by left-lateral strike-slip faults, mostly striking NW-SE, NE-SW and NNE-SSW. These two additional phases were produced by a NE-SW to N-S trending σ1. The arcuate belt is marked by along-strike variations in the tectonic regime and deformation geometry, plus belt-parallel stretching. Based on our field data, integrated with published analogue models, we suggest a possible explanation for the Rioni structure, in terms of the oblique, asymmetric indentation of an upper crustal blocks moving to the SSW.

  4. Tectonic insight based on anisotropy of magnetic susceptibility and compaction studies in the Sierras Australes thrust and fold belt (southwest Gondwana boundary, Argentina)

    NASA Astrophysics Data System (ADS)

    Arzadún, Guadalupe; Tomezzoli, Renata N.; Cesaretti, Nora N.

    2016-04-01

    The Sierras Australes fold and thrust belt (Buenos Aires Province, Argentina) was in the southwestern Gondwanaland margin during the Paleozoic. The Tunas Formation (Permian) is exposed along the eastern part of it and continues eastward beneath the Claromecó Basin. Anisotropy of magnetic susceptibility (AMS) and compaction studies are described and compared with previous paleomagnetic studies with the aim of determining direction and magnitude of the main stresses acting during the sedimentation of the Tunas Formation. The anisotropy ellipsoids are triaxial with oblate or prolate shapes, reflecting different stages of layer parallel shortening during the evolution of the basin. Kmax axes trend NW-SE, parallel to the fold axes, while Kmin move from a horizontal (base) to a vertical orientation at the top of the succession, showing a change from a tectonic to almost a sedimentary fabric. The magnitude of anisotropy and compaction degree decreases toward the top of the succession. The AMS results are consistent with the outcrop structural observations and the compaction and paleomagnetic data. Regional pattern indicates a compression from the SW along this part of Gondwana, with a migration of the orogenic front and attenuation toward the NE in the foreland basin during the Upper Paleozoic. This deformation, locally assigned to the San Rafael noncollisional orogenic phase, is the result of the latitudinal movements toward the Equator of Gondwana (southern plates) and Laurentia (northern plates) during the Permian. This movement is the result of a rearrangement of the microplates that collided with Gondwana during the Late Devonian, to configure Pangea during the Triassic.

  5. Morphotectonics of the central Muertos thrust belt and Muertos Trough (northeastern Caribbean)

    USGS Publications Warehouse

    Granja, Bruna J.L.; ten Brink, Uri S.; Carbó-Gorosabel, Andrés; Muñoz-Martín, A.; Gomez, Ballesteros M.

    2009-01-01

    Multibeam bathymetry data acquired during the 2005 Spanish R/V Hesp??rides cruise and reprocessed multichannel seismic profiles provide the basis for the analysis of the morphology and deformation in the central Muertos Trough and Muertos thrust belt. The Muertos Trough is an elongated basin developed where the Venezuelan Basin crust is thrusted under the Muertos fold-and-thrust belt. Structural variations along the Muertos Trough are suggested to be a consequence of the overburden of the asymmetrical thrust belt and by the variable nature of the Venezuelan Basin crust along the margin. The insular slope can be divided into three east-west trending slope provinces with high lateral variability which correspond to different accretion stages: 1) The lower slope is composed of an active sequence of imbricate thrust slices and closed fold axes, which form short and narrow accretionary ridges and elongated slope basins; 2) The middle slope shows a less active imbricate structure resulting in lower superficial deformation and bigger slope basins; 3) The upper slope comprises the talus region and extended terraces burying an island arc basement and an inactive imbricate structure. The talus region is characterized by a dense drainage network that transports turbidite flows from the islands and their surrounding carbonate platform areas to the slope basins and sometimes to the trough. In the survey area the accommodation of the ongoing east-west differential motion between the Hispaniola and the Puerto Rico-Virgin Islands blocks takes place by means of diffuse deformation. The asymmetrical development of the thrust belt is not related to the geological conditions in the foreland, but rather may be caused by variations in the geometry and movement of the backstop. The map-view curves of the thrust belt and the symmetry of the recesses suggest a main north-south convergence along the Muertos margin. The western end of the Investigator Fault Zone comprises a broad band of

  6. 30 CFR 75.1731 - Maintenance of belt conveyors and belt conveyor entries.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Maintenance of belt conveyors and belt conveyor....1731 Maintenance of belt conveyors and belt conveyor entries. (a) Damaged rollers, or other damaged belt conveyor components, which pose a fire hazard must be immediately repaired or replaced. All other...

  7. Effectiveness of Ford's belt reminder system in increasing seat belt use

    PubMed Central

    Williams, A; Wells, J; Farmer, C

    2002-01-01

    Objectives: The study investigated the effectiveness in increasing seat belt use of Ford's belt reminder system, a supplementary system that provides intermittent flashing lights and chimes for five minutes if drivers are not belted. Methods: Seat belt use of drivers in relatively new cars with and without the reminder system was unobtrusively observed as vehicles were brought to dealerships for service. Results: Overall use rates were estimated at 71% for drivers in vehicles without the reminder system and 76% for drivers in vehicles with belt reminders (p<0.01). Conclusions: Seat belt use is relatively low in the United States. The present study showed that vehicle based reminder systems can be at least modestly effective in increasing belt use, which may encourage further development of such systems. PMID:12460965

  8. Thin‐ or thick‐skinned faulting in the Yakima fold and thrust belt (WA)? Constraints from kinematic modeling of the saddle mountains anticline

    USGS Publications Warehouse

    Casale, Gabriele; Pratt, Thomas L.

    2015-01-01

    The Yakima fold and thrust belt (YFTB) deforms the Columbia River Basalt Group flows of Washington State. The YFTB fault geometries and slip rates are crucial parameters for seismic‐hazard assessments of nearby dams and nuclear facilities, yet there are competing models for the subsurface fault geometry involving shallowly rooted versus deeply rooted fault systems. The YFTB is also thought to be analogous to the evenly spaced wrinkle ridges found on other terrestrial planets. Using seismic reflection data, borehole logs, and surface geologic data, we tested two proposed kinematic end‐member thick‐ and thin‐skinned fault models beneath the Saddle Mountains anticline of the YFTB. Observed subsurface geometry can be produced by 600–800 m of heave along a single listric‐reverse fault or ∼3.5  km of slip along two superposed low‐angle thrust faults. Both models require decollement slip between 7 and 9 km depth, resulting in greater fault areas than sometimes assumed in hazard assessments. Both models require initial slip much earlier than previously thought and may provide insight into the subsurface geometry of analogous comparisons to wrinkle ridges observed on other planets.

  9. Pattern and Outcome of Induced Abortion in Abakaliki, Southeast of Nigeria

    PubMed Central

    Ikeako, LC; Onoh, R; Ezegwui, HU; Ezeonu, PO

    2014-01-01

    Background: Unsafe abortion accounts for a greater proportion of maternal deaths, yet it is often not adequately considered in discussions around reducing maternal mortality. Aim: The aim of this study is to determine the pattern of unsafe abortion and the extent to which unsafe abortion contributes to maternal morbidity and mortality in our setting as well as assess the impact of post-abortion care. Subjects and Methods: A descriptive study of patients who were admitted for complications following induced abortions between January 1, 2001 and December 31, 2008 at the Federal Medical Center, Abakaliki South East of Nigeria with data obtained from case records. Results: Out of the 1,562 gynecogical admissions, a total of 83 patients presented with the complications arising from induced abortion. The age group 20-24 years was mostly affected and adolescents constituted 32.5% (27/83). Nearly 15.7% (13/83) of these patients died while the remaining 84.3% (70/83) had various complications, which were mainly septicemia 59.0% (49/83), anemia 47.0% (39/83), peritonitis 41.0% (34/83), hemorrhages 34.9% (29/83) and uterine perforation 30.1% (25/83). During the study, there were 38 gynecological deaths and abortion related death accounted for 34.2% (13/38) of these gynecological deaths. 84.3% (70/83) of the patients had no documented evidence of counseling on family planning and 59.0% (49/83) were not aware of the different methods of contraception. Conclusion: Unsafe abortion remains one of the most neglected sexual and reproductive health problems in developing countries today despite its significant contribution to maternal mortality and morbidity. Solutions and remedies include prevention of unplanned and unwanted pregnancies by sex education and access to safe and sustainable family planning methods. PMID:24971223

  10. Condition-Based Conveyor Belt Replacement Strategy in Lignite Mines with Random Belt Deterioration

    NASA Astrophysics Data System (ADS)

    Blazej, Ryszard; Jurdziak, Leszek

    2017-12-01

    In Polish lignite surface mines, condition-based belt replacement strategies are applied in order to assure profitable refurbishment of worn out belts performed by external firms specializing in belt maintenance. In two of three lignite mines, staff asses belt condition subjectively during visual inspections. Only one mine applies specialized diagnostic device (HRDS) allowing objective magnetic evaluation of belt core condition in order to choose the most profitable moment for the dismantling of worn out belt segments from conveyors and sending them to the maintenance firm which provides their refurbishment. This article describes the advantages of a new diagnostic device called DiagBelt. It was developed at the Faculty of Geoengineering, Mining and Geology, Wroclaw University of Science and Technology. Economic gains from its application are calculated for the lignite mine and for the belt maintenance firm, taking into account random life (durability) of new and reconditioned belts (after the 1st and the 2nd refurbishment). Recursive calculations for following years allow the estimation of the length and costs of replaced, reconditioned and purchased belts on an annual basis, while the use of the Monte Carlo method allows the estimation of their variability caused by random deterioration of belts. Savings are obtained due to better selection of moments (times) for the replacement of belt segments and die to the possibility to qualify worn out belts for refurbishment without the need to remove their covers. In effect, increased belt durability and lowered share of waste belts (which were not qualified for reconditioning) create savings which can quickly cover expenditures on new diagnostic tools and regular belt inspections in the mine.

  11. Succession of structural events in the Goren greenstone belt (Burkina Faso): Implications for West African tectonics

    NASA Astrophysics Data System (ADS)

    Hein, Kim A. A.

    2010-02-01

    Ten years after field investigations in the SE Goren greenstone belt (GGB) of Burkina Faso by the Sanmatenga J.V., sponsored field studies conducted in 2007 have significantly enhanced structural datasets. The studies in 2007 were conducted across an expanded area of the GGB that included both southwestern and northeastern domains, and portions of the Pissila batholith to the west of the GGB. A revision of tectonic models proposed by Hein et al. [Hein, K.A.A., Morel, V., Kagoné, O., Kiemde, F., Mayes, K., 2004. Birimian lithological succession and structural evolution in the Goren Segment of the Boromo-Goren Greenstone Belt, Burkina Faso. Journal of African Earth Sciences 39, 1-23] is now possible. Three deformation events characterise the Goren greenstone belt. The deformation, D1 (previously D3) resulted in the formation of NW to NNW-trending steeply-dipping dextral-reverse shear zones folds and a penetrative S1-C schistosity that formed during a period of NE-SW shortening. The event is termed the Tangaean Event because it can be correlated across NE Burkina Faso in the Boromo, Bouroum, Yalago and Oudalan-Gorouol greenstone belts. The deformation, D2 (previously D2) resulted in the progressive development of NNE to NE-trending macroscopic to mesoscopic folds and a penetrative axial planar cleavage (S2), which was followed by the formation of dextral- and sinistral-reverse shears and a pervasive schistosity (S2-C). The first-order crustal-scale Sabce Shear Zone, which traverses the northern portion of the study area, is associated with macroscopic anticlockwise drag rotation of NW to NNW-trending D1 shears and folds: (the macroscopic fold was previously classified as D1). D2 in the GGB corresponds with the Eburnean Orogeny at 2130-1980 Ma, as described by [Feybesse, J.-L., Billa, M., Guerrot, C., Duguey, E., Lescuyer, J.-L, Milesi, J.-P., Bouchot, V., 2006, The paleoproterozoic Ghanian province: geodynamic model and ore controls, including regional stress

  12. Thrust Belt Architecture of the Central and Southern Western Foothills of Taiwan

    NASA Astrophysics Data System (ADS)

    Rodriguez, F.; Wiltschko, D.

    2006-12-01

    A structural model of the central and southern Western Foothills Fold and Thrust Belt (WFFTB) was constructed from serial balanced cross sections using available surface, drill, seismic and thermochronologic data. The WFFTB is composed of four main thrust sheets with minor splays. On the east, the Tulungwan fault, which separates the sedimentary rocks of the WFFTB from the low grade meta-sediments of the Slate Belt, evolves from a basement cored fold in the north (around 24°10' N) where the conformable contact between foothills sediments and meta-sediments from the Slate Belt on its western flank is present. At this point the tip of the fault is below the unconformity and the displacement amount is small. To the south this fault breaks the back limb of the fold and gains displacement, and continues gaining displacement to the south. The next thrust sheet to the west includes the Schuantung, Fenghuangchan, Luku, Tatou, Hopiya, and Pingchi faults. This fault system is interpreted as characterized by a long flat with small ramps along a Miocene detachment, not a series of imbricates, as it has been interpreted before. The next thrust sheet to the west is the Chulungupu-Chukou-Lunhou, this system appears to gain displacement to the south as the Schuantung fault system decreases in amount of displacement. The Chulungpu-Chukou-Lunhou fault system contains a wide monocline in the central foothills related with the Chulungpu fault and two wide synclines in the southern part, the Yuching and Tinpligling synclines. Modeling of these two last structures shows that both are uplifted with respect to the regional level above a wide and flat feature; the footwall of the Lunhou fault is a monocline. A geometric solution to lift the Lunhou system involves a major fault-bend-fold anticline with a long ramp and a detachment at ~13 km of depth. It explains, 1) the frontal monocline, which is the from limb of this fault-bend- fold, 2) the minor structures associated with minor back

  13. Patterns of folding and fold interference in oblique contraction of layered rocks of the inverted Cobar Basin, Australia

    NASA Astrophysics Data System (ADS)

    Smith, J. V.; Marshall, B.

    1992-12-01

    The inverted Cobar Basin, within the Lachlan Fold Belt of New South Wales, Australia, comprises a mid-Palaeozoic cover sequence, originally deposited in a NNW-trending basin. The pattern of F 1 folding in the layered cover rocks changes from east to west; from tight well-cleaved folds parallel to the NNW-trending basin margin on the east, to open poorly cleaved en echelon folds at about 35° to the margin, further to the west. The change in fold trend and strain intensity has been repeatedly ascribed to the differing behaviour of discrete zones, decoupled across a north-trending strike-slip fault boundary. New field data show that the changes in orientation and strain intensity of F 1 structures are progressively developed, that an abrupt boundary between discrete zones cannot be substantiated, and that interpretations involving decoupled blocks are not supported by the evidence. Conversely, the data require coherent behaviour across the basin, such that the overall pattern of F 1 folding must be explained by strain compatible processes. This new interpretation of the F 1 deformation pattern has been modelled and quantitatively analysed. Theoretical predictions of the orientation of structures in unlayered isotropic material undergoing oblique contraction are inapplicable to layered anisotropic material. The style of deformation in layered material will reflect the interaction of the bulk strain pattern due to convergence together with the influence of the layering anisotropy. The orientations of the finite strain axes inferred from the folding need not match those of the bulk deformation; the amount of strain recorded by folding may be unrepresentative of that developed in the deformed tract. Oblique contraction at a range of convergence angles was simulated by models employing layers of wet tissue paper. Quantitative analysis of the strain patterns in this layered anisotropic material showed consistent departures from the theoretical predictions for isotropic

  14. Valemount strain zone: A dextral oblique-slip thrust system linking the Rocky Mountain and Omineca belts of the southeastern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    McDonough, Michael R.; Simony, Philip S.

    1989-03-01

    The Valemount strain zone (VSZ), a narrow zone of high orogen-parallel (OP) strain in pebble conglomerate of the Late Proterozoic Miette Group, is the footwall expression of a thrust fault on the western edge of the Rocky Mountain belt, marking the eastern limit of a wide zone of OP fabrics distributed through the Omineca crystalline and western Rocky Mountain belts of the southeastern Canadian Cordillera. Kinematic indicators from the VSZ and the adjacent Bear Foot thrust zone show that both thrust and dextral displacement are associated with folding and thrust motion in the Rocky Mountains, thereby linking the southern Rocky Mountain belt to the Omineca belt by an oblique-slip thrust regime that is tectonically unrelated to the Southern Rocky Mountain Trench. Transverse shortening of thrust sheets and subsequent distribution of OP shear are invoked to explain the parallelism of stretching lineations and fold axes. Strain and kinematic data and the thrust-belt geometry of the VSZ suggest that OP lineations are a product of a large amount of transverse shortening during slightly oblique A-type subduction. Thus, OP lineations are not representative of relative plate motions between North America and accreted terranes, but probably are a function of footwall buttressing of thrust sheets, a mechanism that may be widely applicable to the internal zones of collisional orogens.

  15. Crustal shortening and thickening in Neoarchean granite-greenstone belts: A case study from the link between the ∼2.7 Ga Elu and Hope Bay belts, northeast Slave craton, Canada

    NASA Astrophysics Data System (ADS)

    Mvondo, Hubert; Lentz, Dave; Bardoux, Marc

    2017-11-01

    The Elu Link between the ∼2.7 Ga Hope Bay and Elu belts in the northeast Bathurst Block of the Slave craton comprises supracrustal and intrusive rocks variably deformed by three tectono-metamorphic events (D1-D3). The geometry of D1 structures formed during prograde metamorphism is uncertain, because of subsequent overprint. D2 occurred in two stages predating (D2a) and postdating (D2b) peak metamorphism. D1 and D2a were thrusting events inferred from peak metamorphic pressures of ∼6.7 kbar (670 MPa) retained by a garnet orthogneiss. The latter is diagnostic of thrust tectonism in Archean granite-greenstone belts with no characteristic thrust faults. Unlike D2a, D2b was a vertical general flattening event prevailing during the formation of magmatic domes and interdomal folds that form the main strain patterns of the belts. This was followed by the formation of buckled F3 folds associated with D3 vertical constriction. The switch from thrust to vertical tectonics during peak metamorphism and subsequent deformation resulted in intense recrystallization that explains the poor preservation and scarcity of early-formed shears, including thrust zones. A tectonic process, combining D1+D2a thrust stacking, sagduction, and vertical stretching during D2b and D3, is suggested to explain crustal thickening in the Elu Link and terrains of similar ages.

  16. Rotation of the Pacific Northwest and Deformation Across the Yakima Fold and Thrust Belt Estimated with GPS

    NASA Astrophysics Data System (ADS)

    McCaffrey, R.; King, R. W.; Lancaster, M.; Miller, M. M.; Wells, R. E.

    2015-12-01

    Geodetic, geologic and paleomagnetic data reveal that Oregon and parts of California, Nevada and Idaho rotate clockwise at 0.3 to 1.0 deg/Ma (relative to North America) about an axis near the Idaho-Oregon-Washington border, while northeast Washington is relatively fixed to North America. This rotation has been going on for at least 15 Ma. The spatial termination of the rotation requires shortening between Oregon and Washington. The Yakima fold and thrust belt (YFTB) lies along the boundary between northern Oregon and central Washington where convergence of the clockwise-rotating Oregon block is apparently accommodated. Shortening across the YFTB is thought to occur in a fan-like manner, increasing to the west. We obtained high-accuracy, high-density geodetic GPS measurements in 2012 and 2013 that are used with earlier measurements to characterize YFTB kinematics. Deformation associated with the YFTB starts in the south at the Blue Mountains Anticline in northern Oregon and extends northward to Frenchman Hills in Washington. To the east, the faulting and earthquake activity of the YFTB are truncated by a NNW-trending, narrow zone of deformation that runs along the Pasco Basin and Moses Lake region. It accommodates about 0.5 to 1.0 mm/yr of east to northeast shortening along the eastern boundary of the Department of Energy Hanford Site. The deforming zone aligns with recent seismicity in the Ice Harbor dike swarm, a relatively young ~ 8.5 Ma vent complex. West of the Cascade arc, shortening is accommodated by a series of east-trending faults, starting at the Doty fault in central coastal Washington and extending through Seattle up to the Canadian border. South of the Doty fault, other faults may take up some motion but may be too slow to resolve with GPS.

  17. Association of deformation and fluid events in the central Brooks Range fold-and-thrust belt, Northern Alaska

    USGS Publications Warehouse

    Moore, Thomas E.; Potter, Christopher J.; O'Sullivan, Paul B.; Shelton, Kevin L.; Underwood, Michael B.

    2003-01-01

    Ocentral Brooks Range consists of two superposed north-directed contractional orogens, one formed between 140-120 Ma and the other at ~60-45 Ma. The older orogen was an arc-continent collisional zone characterized by far-traveled allochthons and relatively low structural relief. The younger orogen is a retroarc thrust belt with relatively low amounts of shortening and high structural relief. Folding and thrusting of the younger episode is superimposed on the thin-skinned deformational wedge of the earlier orogen and also produced a frontal triangle zone in a thick sequence of mid-Cretaceous foreland basin sediments to the north. Stable isotope compositions of calcite and quartz veins indicate two fluid events including: (1) an earlier, higher-temperature (~250-300° C) event that produced veins in deformed Devonian clastic rocks, and (2) a younger, lower-temperature (~150° C) event that deposited veins in deformed Mississippian through Albian strata. The fluids in the first event had variable d18O values, but nearly constant d13C values buffered by limestone lithologies. The vein-forming fluids in the second event had similarly variable d18O values, but with distinctly lower d13C values as a result of oxidation of organic matter and/or methane. Zircon fission track ages demonstrate cooling to temperatures below 200° C between 140-120 Ma for the Devonian rocks, whereas zircon and apatite fission track ages show that Mississippian to Albian rocks were never heated above 200° C and cooled below 110-90° C at ~60-45 Ma. These data are interpreted as indicating that the older, high-temperature fluid event was active during thrusting at 120-140 Ma, and the younger fluid event during deformation at ~60-45 Ma. The data and results presented in this poster will be published in early 2004 in Moore and others (in press).

  18. Deformation sequences of the Day Nui Con Voi metamorphic belt, northern Vietnam

    NASA Astrophysics Data System (ADS)

    Yeh, M. W.; Lee, T. Y.; Lo, C. H.; Chung, S. L.; Lan, C. Y.; Lee, J. C.; Lin, T. S.; Lin, Y. J.

    2003-04-01

    The correlation of structure, microstructure and metamorphic assemblages is of fundamental importance to the understanding of the complex tectonic history and kinematics of the Day Nui Con Voi (DNCV) metamorphic belt in Vietnam along the Ailao Shan-Red River (ASRR) shear zone as it provides constraints on the relative timing of the deformation, kinematics and metamorphism. High-grade metamorphic rocks of amphibolite faces showed consistent deformation sequences of three folding events followed by one brittle deformation through all four cross sections from Lao Cai to Viet Tri indicated the DNCV belt experienced similar deformation condition throughout its length. The first deformation event, D1, produced up-right folds (locally preserved) with sub-vertical, NE-SW striking axial planes with dextral sense of shear probably formed during the early phase of the lowermost Triassic Indosinian orogeny. Followed by this compressional event is a gravitational collapsing event, D2, which is the major deformation and metamorphic event characterized by kyanite grade metamorphism and large scale horizontal folds with NW-SE (320) striking sub-horizontal axial pane showing sinsistral sense of shear most likely formed during the Oligocene-Miocene SE extrusion of Indochina peninsula. The 3rd folding event, D3, is a post-metamorphism doming event with NW-SE (310) striking sub-vertical axial plane that folded/tilted the once sub-horizontal D2 axial planes into shallowly (<30 degrees) NE dipping on the NE limb, and SW dipping on the SW limb possibly due to left-lateral movement of the N-S trending Xian Shui He fault system in Mid-Miocene. The outward decreasing of the metamorphic grade from kyanite to garnet then biotite indicated the D3 occurred post metamorphism. Reactivation of the sub-horizontal D2 fold axial planes showed dextral sense of shear possibly due to Late Miocene-Pliocene right-lateral movement of the ASRR shear zone. This right lateral movement continuously deformed

  19. Geological mapping of the Schuppen belt of north-east India using geospatial technology

    NASA Astrophysics Data System (ADS)

    Ghosh, Tanaya; Basu, Surajit; Hazra, Sugata

    2014-01-01

    A revised geologic map of the Schuppen belt of northeast India has been prepared based on interpretation of digitally enhanced satellite images. The satellite image interpretation is supported by limited field work and existing geologic maps. Available geological maps of this fold thrust belt are discontinuous and multi-scaled. The authors are of multiple opinions regarding the trajectory of formation boundaries and fault contacts. Digital image processing of satellite images and limited field surveys have been used to reinterpret and modify the existing geological maps of this fold thrust belt. Optical data of Landsat Thematic Mapper, Enhanced Thematic Mapper and elevation data of ASTER have been used to prepare this revised geological map. The study area extends from Hajadisa in south to Digboi oilfield in north, bounded by Naga thrust in the west and Disang thrust in the east. PCA, Image fusion, Linear Contrast stretch, Histogram Equalization and Painted relief algorithms have been used for the delineation of major geological lineaments like lithological boundary, thrust and strike slip faults. Digital elevation maps have enabled in the discrimination between thrust contacts and lithological boundaries, with the former being located mostly in the valleys. Textural enhancements of PCA, colour composites and Painted relief algorithm have been used to discriminate between different rock types. Few geological concepts about the terrain have been revisited and modified. It is assumed that this revised map should be of practical use as this terrain promises unexploited hydrocarbon reserves.

  20. Storm-time radiation belt electron dynamics: Repeatability in the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Murphy, K. R.; Mann, I. R.; Rae, J.; Watt, C.; Boyd, A. J.; Turner, D. L.; Claudepierre, S. G.; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Fennell, J. F.

    2017-12-01

    During intervals of enhanced solar wind driving the outer radiation belt becomes extremely dynamic leading to geomagnetic storms. During these storms the flux of energetic electrons can vary by over 4 orders of magnitude. Despite recent advances in understanding the nature of competing storm-time electron loss and acceleration processes the dynamic behavior of the outer radiation belt remains poorly understood; the outer radiation belt can exhibit either no change, an enhancement, or depletion in radiation belt electrons. Using a new analysis of the total radiation belt electron content, calculated from the Van Allen probes phase space density (PSD), we statistically analyze the time-dependent and global response of the outer radiation belt during storms. We demonstrate that by removing adiabatic effects there is a clear and repeatable sequence of events in storm-time radiation belt electron dynamics. Namely, the relativistic (μ=1000 MeV/G) and ultra-relativistic (μ=4000 MeV/G) electron populations can be separated into two phases; an initial phase dominated by loss followed by a second phase dominated by acceleration. At lower energies, the radiation belt seed population of electrons (μ=150 MeV/G) shows no evidence of loss but rather a net enhancement during storms. Further, we investigate the dependence of electron dynamics as a function of the second adiabatic invariant, K. These results demonstrate a global coherency in the dynamics of the source, relativistic and ultra-relativistic electron populations as function of the second adiabatic invariant K. This analysis demonstrates two key aspects of storm-time radiation belt electron dynamics. First, the radiation belt responds repeatably to solar wind driving during geomagnetic storms. Second, the response of the radiation belt is energy dependent, relativistic electrons behaving differently than lower energy seed electrons. These results have important implications in radiation belt research. In particular

  1. Belt attachment and system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schneider, Abraham D.; Davidson, Erick M.

    Disclosed herein is a belt assembly including a flexible belt with an improved belt attachment. The belt attachment includes two crossbars spaced along the length of the belt. The crossbars retain bearings that allow predetermined movement in six degrees of freedom. The crossbars are connected by a rigid body that attaches to the bearings. Implements that are attached to the rigid body are simply supported but restrained in pitching rotation.

  2. Belt attachment and system

    DOEpatents

    Schneider, Abraham D.; Davidson, Erick M.

    2016-02-02

    Disclosed herein is a belt assembly including a flexible belt with an improved belt attachment. The belt attachment includes two crossbars spaced along the length of the belt. The crossbars retain bearings that allow predetermined movement in six degrees of freedom. The crossbars are connected by a rigid body that attaches to the bearings. Implements that are attached to the rigid body are simply supported but restrained in pitching rotation.

  3. Preliminary structural model for the southwestern part of the Michipicoten greenstone belt, Ontario

    NASA Technical Reports Server (NTRS)

    Mcgill, G. E.; Shrady, C. H.

    1986-01-01

    The southwestern part of the Michipicoten Greenstone Belt includes a 100 sq km fume kill extending northeastwards from the twon of Wawa, Ontario. Except for a strip along the Magpie River that is covered by Pleistocene gravels, outcrop in the fume kill averages about 30-50%. Within this area are all the major lithologic belts characteristic of the southwestern fourth of the Michipicoten Greenstone Belt. All of the area mapped to date lies within Chabenel Township, recently mapped at 4" = 1 mile. Following a brief reconnaissance in 1983, mapping at a scale of 1" = 400' was begun within and adjacent to the fume kill in 1984. Two objectives are sought (1) determinaion of the geometry and sequence of folding, faulting, cleavage development, and intrusion; and (2) defining and tracing lithologic packages, and evaluating the nature of the contacts between these packages. Results for objective (1) are discussed in a companion abstract; this abstract will present tentative results for objective.

  4. 49 CFR 393.93 - Seats, seat belt assemblies, and seat belt assembly anchorages.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Seats, seat belt assemblies, and seat belt assembly anchorages. 393.93 Section 393.93 Transportation Other Regulations Relating to Transportation... § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses—(1) Buses...

  5. 49 CFR 393.93 - Seats, seat belt assemblies, and seat belt assembly anchorages.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Seats, seat belt assemblies, and seat belt assembly anchorages. 393.93 Section 393.93 Transportation Other Regulations Relating to Transportation... § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses—(1) Buses...

  6. 49 CFR 393.93 - Seats, seat belt assemblies, and seat belt assembly anchorages.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Seats, seat belt assemblies, and seat belt assembly anchorages. 393.93 Section 393.93 Transportation Other Regulations Relating to Transportation... § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses—(1) Buses...

  7. 49 CFR 393.93 - Seats, seat belt assemblies, and seat belt assembly anchorages.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Seats, seat belt assemblies, and seat belt assembly anchorages. 393.93 Section 393.93 Transportation Other Regulations Relating to Transportation... § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses—(1) Buses...

  8. 49 CFR 393.93 - Seats, seat belt assemblies, and seat belt assembly anchorages.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Seats, seat belt assemblies, and seat belt assembly anchorages. 393.93 Section 393.93 Transportation Other Regulations Relating to Transportation... § 393.93 Seats, seat belt assemblies, and seat belt assembly anchorages. (a) Buses—(1) Buses...

  9. High-resolution geological mapping at 3D Environments: A case study from the fold-and-thrust belt in northern Taiwan

    NASA Astrophysics Data System (ADS)

    Chan, Y. C.; Shih, N. C.; Hsieh, Y. C.

    2016-12-01

    Geologic maps have provided fundamental information for many scientific and engineering applications in human societies. Geologic maps directly influence the reliability of research results or the robustness of engineering projects. In the past, geologic maps were mainly produced by field geologists through direct field investigations and 2D topographic maps. However, the quality of traditional geologic maps was significantly compromised by field conditions, particularly, when the map area is covered by heavy forest canopies. Recent developments in airborne LiDAR technology may virtually remove trees or buildings, thus, providing a useful data set for improving geological mapping. Because high-quality topographic information still needs to be interpreted in terms of geology, there are many fundamental questions regarding how to best apply the data set for high-resolution geological mapping. In this study, we aim to test the quality and reliability of high-resolution geologic maps produced by recent technological methods through an example from the fold-and-thrust belt in northern Taiwan. We performed the geological mapping by applying the LiDAR-derived DEM, self-developed program tools and many layers of relevant information at interactive 3D environments. Our mapping results indicate that the proposed methods will considerably improve the quality and consistency of the geologic maps. The study also shows that in order to gain consistent mapping results, future high-resolution geologic maps should be produced at interactive 3D environments on the basis of existing geologic maps.

  10. Soro West: A non-seismically defined, fault cut-off prospect in the Papuan Fold and Thrust Belt, Papua New Guinea

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Robinson, W.F.; Swift, C.M. Jr.

    Soro West is a fault cut-off prospect located in the frontal portion of the Papuan Fold and Thrust Belt. Prospective Toro and Imburu sandstones are interpreted to be in the hanging wall of the Soro Thrust. Truncation against the thrust, both updip and through lateral ramps, provides the trapping mechanism. The Soro West Prospect was defined using geological, geochemical, remote sensing, and geophysical data. The definition and location of the trap is a primary risk and work was focused on this aspect. Surface geological data (lithology, strikes, and dips) topography and synthetic aperture radar imagery were incorporated into the evaluation.more » Statistical curvature analysis techniques helped define the shape of the structure and the locations of the lateral ramps. Strontium isotope analyses of Darai Limestone surface samples refined erosional levels using a locally-derived reference curve. Severe karst precludes the acquisition of coherent surface seismic data, so the primary geophysical tool used was magnetotellurics (MT). A detailed, pre-survey feasibility study defined expected responses from alternative structural models. The MT data demonstrated that the limestone at surface is underlain by thick conductive clastics and not another Darai Limestone sheet. The data also constrained the range of fault cut-off positions significantly. Multiple, three-dimensionally consistent, restorable alternative structural models were created using results from all analyses. These led to a positive assessment of the prospect and an exploratory test is to be drilled in 1996.« less

  11. Synaptic ribbon. Conveyor belt or safety belt?

    PubMed

    Parsons, T D; Sterling, P

    2003-02-06

    The synaptic ribbon in neurons that release transmitter via graded potentials has been considered as a conveyor belt that actively moves vesicles toward their release sites. But evidence has accumulated to the contrary, and it now seems plausible that the ribbon serves instead as a safety belt to tether vesicles stably in mutual contact and thus facilitate multivesicular release by compound exocytosis.

  12. Partitioning N2O emissions within the US Corn Belt using an inverse modeling approach

    USDA-ARS?s Scientific Manuscript database

    Nitrous oxide (N2O) emissions within the US Corn Belt have been estimated to be 2- to 9-11 fold larger than predictions from emission inventories, implying that one or more source 12 categories in bottom-up approaches are underestimated. Here we interpret hourly N2O 13 mixing ratios measured during ...

  13. Litho-structural analysis of eastern part of Ilesha schist belt, Southwestern Nigeria

    NASA Astrophysics Data System (ADS)

    Fagbohun, Babatunde Joseph; Adeoti, Blessing; Aladejana, Olabanji Odunayo

    2017-09-01

    The Ilesha schist belt is an excellent example of high strain shear belt within basement complex of southwestern Nigeria which is part of the larger West African Shield. The Ilesha schist belt is characterised by metasediment-metavolcanic, migmatite-gneiss and older granite rocks and the occurrence of a Shear zone which has been traced to and correlated with the central Hoggar Neoproterozoic shear zone as part of the Trans-Saharan Belt. Although the area is interesting in terms of geologic-tectonic setting, however, detailed geological assessment and structural interpretation of features in this area is lacking due accessibility problem. For these reasons we applied principal component analysis (PCA) and band ratio (BR) techniques on Landsat 8 OLI data for lithological discrimination while for structural interpretation, filtering techniques of edge enhancement and edge detection was applied on digital elevation model (DEM) acquired by shuttle radar topographic mission (SRTM) sensor. The PCA outperform BR for discrimination between quartzite and granite which are the most exposed rock units in the area. For structural interpretation, DEM was used to generate shaded relief model and edge maps which enable detailed structural interpretation. Geologic fieldwork was further conducted to validate structures and units identified from image processing. Based image interpretation, three deformation events were identified. The first event (D1) which is majorly a ductile deformation produced foliations and folds whose axial planes trend in NNE-SSW. The second event (D2) resulted in reactivation and rotation of the D1 structures particularly the folds in the NE-SW. The third event (D3) produced a transgressive deformation starting with the ductile deformation resulting in the development of sigmoidal structures oriented in NE-SW to E-W direction and the brittle deformation occurring at later stages producing fractures oriented in the E-W to NE-SW directions. These results have

  14. Comfort and convenience specifications for safety belts : shoulder belt fit, pressure and pullout forces

    DOT National Transportation Integrated Search

    1980-04-30

    A three-part study was conducted to further define comfort requirements for seat belt systems with respect to shoulder belt fit, shoulder belt contact pressure, and 3-point restraint system pullout forces. Objective of the belt-fit portion of the stu...

  15. Kinematic reconstruction of a thin-skinned, deep-water fold and thrust belt: the case of the Outer Tuscan Nappe (Umbria, Italy)

    NASA Astrophysics Data System (ADS)

    Carboni, Filippo; Barchi, Massimiliano; Brozzetti, Francesco; Cruciani, Francesco; Ercoli, Maurizio; Mirabella, Francesco; Porreca, Massimiliano

    2017-04-01

    Fold-and-Thrust Belts occur worldwide in a variety of tectonic settings. Most of them develop in a deepwater environment (Deep Water Fold-and-Thrust Belts, DWFTBs), at both continental passive and active margins, driven by gravity (near-field stresses) and tectonic forces (far-field stresses) respectively. Here we present a multidisciplinary geological study of the Outer Tuscan Nappe (OTN), an imbricate thrust system in the Northern Apennines of Italy, emplaced in Early Miocene times in deep water environment. Despite the wide scientific literature, the geometry and the kinematic evolution of the OTN were never reconstructed in detail. Furthermore, its total amount of shortening and then its shortening rate, were never measured and calculated through proper restoration techniques. The OTN involves a 2000 m thick, Late Cretaceous-Tertiary "Tuscan" succession, consisting of arenaceous turbidites (Macigno Fm.), overlying a thick level of marls and calcarenites (Scaglia Toscana Fm.), which form the major basal décollement of the imbricate system. Along this basal décollement, the OTN overthrusts eastward younger turbidite units (Mt. Rentella and Marnoso-Arenacea successions). In this study we interpreted a set of 2D seismic reflection profiles calibrated with a deep borehole, crossing transversally (WSW-ENE) and longitudinally (NNW-SSE) the OTN. To better constrain the interpretation, selected controls of key outcrops was performed, mainly aimed at reconstructing: i) the actual transport direction during the OTN emplacement; ii) the position of the subsequent, NNW-SSE trending, extensional faults dissecting the tectonic wedge; iii) the role of transversal faults, longitudinally segmenting the thrust system. Combining the aforesaid data, we drew an integrated 20 km long geological cross section showing the internal geometry of the imbricate thrust system, down to the main basal décollement. The integrated section was successively restored in 2D using the software

  16. The empty primordial asteroid belt.

    PubMed

    Raymond, Sean N; Izidoro, Andre

    2017-09-01

    The asteroid belt contains less than a thousandth of Earth's mass and is radially segregated, with S-types dominating the inner belt and C-types the outer belt. It is generally assumed that the belt formed with far more mass and was later strongly depleted. We show that the present-day asteroid belt is consistent with having formed empty, without any planetesimals between Mars and Jupiter's present-day orbits. This is consistent with models in which drifting dust is concentrated into an isolated annulus of terrestrial planetesimals. Gravitational scattering during terrestrial planet formation causes radial spreading, transporting planetesimals from inside 1 to 1.5 astronomical units out to the belt. Several times the total current mass in S-types is implanted, with a preference for the inner main belt. C-types are implanted from the outside, as the giant planets' gas accretion destabilizes nearby planetesimals and injects a fraction into the asteroid belt, preferentially in the outer main belt. These implantation mechanisms are simple by-products of terrestrial and giant planet formation. The asteroid belt may thus represent a repository for planetary leftovers that accreted across the solar system but not in the belt itself.

  17. The empty primordial asteroid belt

    PubMed Central

    Raymond, Sean N.; Izidoro, Andre

    2017-01-01

    The asteroid belt contains less than a thousandth of Earth’s mass and is radially segregated, with S-types dominating the inner belt and C-types the outer belt. It is generally assumed that the belt formed with far more mass and was later strongly depleted. We show that the present-day asteroid belt is consistent with having formed empty, without any planetesimals between Mars and Jupiter’s present-day orbits. This is consistent with models in which drifting dust is concentrated into an isolated annulus of terrestrial planetesimals. Gravitational scattering during terrestrial planet formation causes radial spreading, transporting planetesimals from inside 1 to 1.5 astronomical units out to the belt. Several times the total current mass in S-types is implanted, with a preference for the inner main belt. C-types are implanted from the outside, as the giant planets’ gas accretion destabilizes nearby planetesimals and injects a fraction into the asteroid belt, preferentially in the outer main belt. These implantation mechanisms are simple by-products of terrestrial and giant planet formation. The asteroid belt may thus represent a repository for planetary leftovers that accreted across the solar system but not in the belt itself. PMID:28924609

  18. Safety belt laws and disparities in safety belt use among US high-school drivers.

    PubMed

    García-España, J Felipe; Winston, Flaura K; Durbin, Dennis R

    2012-06-01

    We compared reported safety belt use, for both drivers and passengers, among teenagers with learner's permits, provisional licenses, and unrestricted licenses in states with primary or secondary enforcement of safety belt laws. Our data source was the 2006 National Young Driver Survey, which included a national representative sample of 3126 high-school drivers. We used multivariate, log-linear regression analyses to assess associations between safety belt laws and belt use. Teenaged drivers were 12% less likely to wear a safety belt as drivers and 15% less likely to wear one as passengers in states with a secondary safety belt law than in states with a primary law. The apparent reduction in belt use among teenagers as they progressed from learner to unrestricted license holder occurred in only secondary enforcement states. Groups reporting particularly low use included African American drivers, rural residents, academically challenged students, and those driving pickup trucks. The results provided further evidence for enactment of primary enforcement provisions in safety belt laws because primary laws are associated with higher safety belt use rates and lower crash-related injuries and mortality.

  19. Antimicrobial susceptibility pattern of Klebsiella species from Ebonyi State University Teaching Hospital Abakaliki, Nigeria.

    PubMed

    Akujobi, C N

    2005-12-01

    Klesiella specie isolated from clinical specimens from Ebonyi State University Teaching Hospital (EBSUTH). Abakakliki were studied to determine the antimicrobial susceptibility pattern. Between January, 2003 and September 2004 a total of 3.600 specimens processed in the routine Medical Microbiology laboratory of EBSUTH, of which 245(6.8%) yielded Klebsiella species, with 84 from out - patients and 161 from in - patients. The number of isolates from various samples were: Urine 126, Sputum 37 Endocervical swab 13, Aspirates 8, High Vaginal Swab 7, Blood 3, Eye Swab, Ear Swab and Cerebrospinal fluid were 2 samples each. Organisms were identified by conventional methods. Antimicrobial susceptibility was done by the disk diffusion methods. The antimicrobial disk used include: Ceftazidime, Cefuroxime, Cefotaxine, Augmentin, Pefloxacin (30ug), Doxycyline (25ug) Genticin (10 ug) Ciprofloacin and Ofloxacin (5ug) each and Erythromycin (15ug). All were Oxoid products. Results were interpreted according to NCCLS criteria. Klebsilla species were isolated mostly from urine specimens (51.4%) followed by wound swabs (18.4%). Antimicrobial susceptibility to various groups drugs used was generally poor. The most sensitive antimicrobial was Ciprofloxacin with 121(49.4%) isolates susceptible to it, followed by Gentamicin with 95 (38.8%) and Ceftazidime with 90(36.7%). Seventeen isolates were multiresistant to all the antimicrobial agents used. The result of this study will help in the empiric therapy of infection caused by Klebsiella species in Ebonyi State University Teaching Hospital, Abakaliki, Nigeria but continuous surverillance of antimicrobial resistance of the organnisn is very necessary in the formulation of a sound antibiotic policy in the hospital.

  20. belt law

    DOT National Transportation Integrated Search

    2007-03-01

    A 2003 study estimated that if all States had primary seat belt laws from 1995 to 2002, over 12,000 lives would have been saved. Failure to implement a primary seat belt law creates a real cost to a States budget for Medicaid and other State medic...

  1. A Discrete Element Modeling Approach to Exploring the Transition Between Fault-related Folding Styles

    NASA Astrophysics Data System (ADS)

    Hughes, A. N.; Benesh, N. P.; Alt, R. C., II; Shaw, J. H.

    2011-12-01

    Contractional fault-related folds form as stratigraphic layers of rock are deformed due to displacement on an underlying fault. Specifically, fault-bend folds form as rock strata are displaced over non-planar faults, and fault-propagation folds form at the tips of faults as they propagate upward through sedimentary layers. Both types of structures are commonly observed in fold and thrust belts and passive margin settings throughout the world. Fault-bend and fault-propagation folds are often seen in close proximity to each other, and kinematic analysis of some fault-related folds suggests that they have undergone a transition in structural style from fault-bend to fault-propagation folding during their deformational history. Because of the similarity in conditions in which both fault-bend and fault-propagation folds are found, the circumstances that promote the formation of one of these structural styles over the other is not immediately evident. In an effort to better understand this issue, we have investigated the role of mechanical and geometric factors in the transition between fault-bend folding and fault-propagation folding using a series of models developed with the discrete element method (DEM). The DEM models employ an aggregate of circular, frictional disks that incorporate bonding at particle contacts to represent the numerical stratigraphy. A vertical wall moving at a fixed velocity drives displacement of the hanging-wall section along a pre-defined fault ramp and detachment. We utilize this setup to study the transition between fault-bend and fault-propagation folding by varying mechanical strength, stratigraphic layering, fault geometries, and boundary conditions of the model. In most circumstances, displacement of the hanging-wall leads to the development of an emergent fold as the hanging-wall material passes across the fault bend. However, in other cases, an emergent fault propagates upward through the sedimentary section, associated with the

  2. Safety Belt Laws and Disparities in Safety Belt Use Among US High-School Drivers

    PubMed Central

    Winston, Flaura K.; Durbin, Dennis R.

    2012-01-01

    Objectives. We compared reported safety belt use, for both drivers and passengers, among teenagers with learner’s permits, provisional licenses, and unrestricted licenses in states with primary or secondary enforcement of safety belt laws. Methods. Our data source was the 2006 National Young Driver Survey, which included a national representative sample of 3126 high-school drivers. We used multivariate, log-linear regression analyses to assess associations between safety belt laws and belt use. Results. Teenaged drivers were 12% less likely to wear a safety belt as drivers and 15% less likely to wear one as passengers in states with a secondary safety belt law than in states with a primary law. The apparent reduction in belt use among teenagers as they progressed from learner to unrestricted license holder occurred in only secondary enforcement states. Groups reporting particularly low use included African American drivers, rural residents, academically challenged students, and those driving pickup trucks. Conclusions. The results provided further evidence for enactment of primary enforcement provisions in safety belt laws because primary laws are associated with higher safety belt use rates and lower crash-related injuries and mortality. PMID:22515851

  3. Structure sismique du socle paléozoïque du bassin des Doukkala, Môle côtier, Maroc occidental. Indication en faveur de l'existence d'une phase éo-varisqueSeismic structure of the Doukkala basin, Palaeozoic basement, western Morocco: a hint for an Eovariscan fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Echarfaoui, Hassan; Hafid, Mohamed; Salem, Abdallah Aı̈t

    2002-01-01

    Seismic profiles and well data from the Doukkala basin unravel the structure of the Palaeozoic basement and suggest that this coastal zone of western Morocco was affected by a compressive phase during the Frasnian. This resulted in the formation of upright, plurikilometric folds associated with reverse faults (North Doukkala), and of asymmetrical folds associated with mostly west verging ramps (South Doukkala). Folding involved all pre-Upper Frasnian formations and caused partial or total hiatus of Upper Frasnian-Strunian strata. This event can be correlated with the orogenic phase reported from more internal domains of the Morocco Hercynian belt, where it is referred to as the 'Bretonne' or 'Eovariscan' phase. To cite this article: H. Echarfaoui et al., C. R. Geoscience 334 (2002) 13-20

  4. Previously unrecognized regional structure of the Coastal Belt of the Franciscan Complex, northern California, revealed by magnetic data

    USGS Publications Warehouse

    Langenheim, Victoria; Jachens, Robert C.; Wentworth, Carl M.; McLaughlin, Robert J.

    2013-01-01

    Magnetic anomalies provide surprising structural detail within the previously undivided Coastal Belt, the westernmost, youngest, and least-metamorphosed part of the Franciscan Complex of northern California. Although the Coastal Belt consists almost entirely of arkosic graywacke and shale of mainly Eocene age, new detailed aeromagnetic data show that it is pervasively marked by long, narrow, and regularly spaced anomalies. These anomalies arise from relatively simple tabular bodies composed principally of magnetic basalt or graywacke confi ned mainly to the top couple of kilometers, even though metamorphic grade indicates that these rocks have been more deeply buried, at depths of 5–8 km. If true, this implies surprisingly uniform uplift of these rocks. The basalt (and associated Cretaceous limestone) occurs largely in the northern part of the Coastal Belt; the graywacke is recognized only in the southern Coastal Belt and is magnetic because it contains andesitic grains. The magnetic grains were not derived from the basalt, and thus require a separate source. The anomalies defi ne simple patterns that can be related to folding and faulting within the Coastal Belt. This apparent simplicity belies complex structure mapped at outcrop scale, which can be explained if the relatively simple tabular bodies are internally deformed, fault-bounded slabs. One mechanism that can explain the widespread lateral extent of the thin layers of basalt is peeling up of the uppermost part of the oceanic crust into the accretionary prism, controlled by porosity and permeability contrasts caused by alteration in the upper part of the subducting slab. It is not clear, however, how this mechanism might generate fault-bounded layers containing magnetic graywacke. We propose that structural domains defined by anomaly trend, wavelength, and source reflect imbrication and folding during the accretion process and local plate interactions as the Mendocino triple junction migrated north, a

  5. Previously unrecognized regional structure of the Coastal Belt of the Franciscan Complex, northern California, revealed by magnetic data

    USGS Publications Warehouse

    Langenheim, V.E.; Jachens, R.C.; Wentworth, C.M.; McLaughlin, R.J.

    2013-01-01

    Magnetic anomalies provide surprising structural detail within the previously undivided Coastal Belt, the westernmost, youngest, and least-metamorphosed part of the Franciscan Complex of northern California. Although the Coastal Belt consists almost entirely of arkosic graywacke and shale of mainly Eocene age, new detailed aeromagnetic data show that it is pervasively marked by long, narrow, and regularly spaced anomalies. These anomalies arise from relatively simple tabular bodies composed principally of magnetic basalt or graywacke confined mainly to the top couple of kilometers, even though metamorphic grade indicates that these rocks have been more deeply buried, at depths of 5–8 km. If true, this implies surprisingly uniform uplift of these rocks. The basalt (and associated Cretaceous limestone) occurs largely in the northern part of the Coastal Belt; the graywacke is recognized only in the southern Coastal Belt and is magnetic because it contains andesitic grains. The magnetic grains were not derived from the basalt, and thus require a separate source. The anomalies define simple patterns that can be related to folding and faulting within the Coastal Belt. This apparent simplicity belies complex structure mapped at outcrop scale, which can be explained if the relatively simple tabular bodies are internally deformed, fault-bounded slabs. One mechanism that can explain the widespread lateral extent of the thin layers of basalt is peeling up of the uppermost part of the oceanic crust into the accretionary prism, controlled by porosity and permeability contrasts caused by alteration in the upper part of the subducting slab. It is not clear, however, how this mechanism might generate fault-bounded layers containing magnetic graywacke. We propose that structural domains defined by anomaly trend, wavelength, and source reflect imbrication and folding during the accretion process and local plate interactions as the Mendocino triple junction migrated north, a

  6. Belt conveyor apparatus

    DOEpatents

    Oakley, David J.; Bogart, Rex L.

    1987-01-01

    A belt conveyor apparatus according to this invention defines a conveyance path including a first pulley and at least a second pulley. An endless belt member is adapted for continuous travel about the pulleys and comprises a lower portion which engages the pulleys and an integral upper portion adapted to receive objects therein at a first location on said conveyance path and transport the objects to a second location for discharge. The upper belt portion includes an opposed pair of longitudinally disposed crest-like members, biased towards each other in a substantially abutting relationship. The crest-like members define therebetween a continuous, normally biased closed, channel along the upper belt portion. Means are disposed at the first and second locations and operatively associated with the belt member for urging the normally biased together crest-like members apart in order to provide access to the continuous channel whereby objects can be received into, or discharged from the channel. Motors are in communication with the conveyance path for effecting the travel of the endless belt member about the conveyance path. The conveyance path can be configured to include travel through two or more elevations and one or more directional changes in order to convey objects above, below and/or around existing structures.

  7. Early Jurassic extensional inheritance in the Lurestan region of the Zagros fold-and-thrust belt, Iran.

    NASA Astrophysics Data System (ADS)

    Tavani, Stefano; Parente, Mariano; Vitale, Stefano; Puzone, Francesco; Erba, Elisabetta; Bottini, Cinzia; Morsalnejad, Davoud; Mazzoli, Stefano

    2017-04-01

    It has long been recognized that the tectonic architecture of the Zagros mountain belt was strongly controlled by inherited structures previously formed within the Arabian plate. These preexisting features span in age from the pre-Cambrian to the Mesozoic, showing different trends and deformation styles. Yet, these structures are currently not fully understood. This uncertainty is partly related with the paucity of exposures, which rarely allows a direct observation of these important deformation features. The Lurestan Province of Iran provides a remarkable exception, since it is one of the few places of the Zagros mountain belt where exposures of Triassic and Jurassic rocks are widespread. In this area we carried out structural observations on Mesozoic extensional structures developed at the southern margin of the Neo-Tethyan basin. Syn-sedimentary extensional faults are hosted within the Triassic-Cretaceous succession, being particularly abundant in the Jurassic portion of the stratigraphy. Early to Middle Jurassic syn-sedimentary faults are observed in different paleogeographic domains of the area, and their occurrence is coherent with the subsequent transition from shallow-water to deep-sea basin environments, observed in a wide portion of the area. Most of the thrusts exposed in the area may indeed be interpreted as reactivated Jurassic extensional faults, or as reverse faults whose nucleation was controlled by the location of preexisting normal faults, as a result of positive inversion during crustal shortening and mountain building.

  8. Moving belt radiator development status

    NASA Technical Reports Server (NTRS)

    White, K. Alan

    1988-01-01

    Development of the Moving Belt Radiator (MBR) as an advanced space radiator concept is discussed. The ralative merits of Solid Belt (SBR), Liquid Belt (LBR), and Hybrid Belt (HBR) Radiators are described. Analytical and experimental efforts related to the dynamics of a rotating belt in microgravity are reviewed. The development of methods for transferring heat to the moving belt is discussed, and the results from several experimental investigations are summarized. Limited efforts related to the belt deployment and stowage, and to fabrication of a hybrid belt, are also discussed. Life limiting factors such as seal wear and micrometeroid resistance are identified. The results from various MBR point design studies for several power levels are compared with advanced Heat Pipe Radiator technology. MBR designs are shown to compare favorable at both 300 and 1000 K temperature levels. However, additional effort will be required to resolve critical technology issues and to demonstrate the advantage of MBR systems.

  9. Landscape maturity, fold growth sequence and structural style in the Kirkuk Embayment of the Zagros, northern Iraq

    NASA Astrophysics Data System (ADS)

    Obaid, Ahmed K.; Allen, Mark B.

    2017-10-01

    The Kirkuk Embayment is located in the southwest of the Zagros fold-and-thrust belt of Iraq. Like fold-and-thrust belts worldwide, the Zagros is conventionally understood to have grown sequentially towards the foreland. Here we use landscape maturity analysis to understand anticline growth in the embayment. Digital Elevation Model (DEM)-based geomorphic indices Hypsometric Integral (HI), Surface Roughness (SR) and their combination Surface Index (SI) have been applied to quantify landscape maturity. The results inform new ideas for the sequence of anticline growth. Maturity indices are highest for the QaraChauq Anticline in the center of the Embayment, then Makhool/Himreen to the south and lastly, the Kirkuk Anticline to the north. The pattern suggests the growth sequence is not classical 'piggy back' thrusting. This result fits the exhumation record, which is loosely constrained by the stratigraphic exposure level. Favored hypotheses for fold growth order are either i) the folds have grown at different times and out of sequence (QaraChauq first, then Makhool/Himreen, and Kirkuk last), or, ii) the growth occurred with different rates of exhumation but at broadly the same time. There are few constraints from available data on syn-tectonic sedimentation patterns. Fold growth across much of the Embayment might have begun within a limited timeframe in the late Miocene-Pliocene, during the deposition of the Mukdadiyah Formation. Another hypothesis is that folds grew in sequence towards the foreland with different rates of exhumation, but we consider this less likely. We also construct a new cross-section for the Embayment, which indicates limited Cenozoic strain: 5% shortening. Analysis of topography and drainage patterns shows two previously-undescribed anticlines with hydrocarbon trap potential, between the Makhool and QaraChauq anticlines.

  10. Tectono-stratigraphic evolution of salt-controlled minibasins in a fold and thrust belt, the Oligo-Miocene central Sivas Basin

    NASA Astrophysics Data System (ADS)

    Kergaravat, Charlie; Ribes, Charlotte; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2017-09-01

    The Central Sivas Basin (Turkey) provides an outcrop example of a minibasin province developed above a salt canopy within a foreland-fold and thrust belt. Several minibasins are examined to assess the influence of regional Oligo-Miocene shortening during the development of a minibasin province. The results are based on extensive field work, including regional and detailed outcrop mapping of at least 15 minibasin margins and analysis of the structural elements at all scales. This reveals a progressive increase in shortening and a decrease in salt tectonics during evolution of the province. The initiation of minibasins is driven mostly by the salt-induced accommodation forming a polygonal network of salt structures with mainly local halokinetic sequences (i.e. hooks and wedges). The initiation of shortening is marked by an abrupt increase in sedimentation rate within the flexural foreland basin causing burial of the preexisting salt structures. Subsequently, orogenic compression encourages the rejuvenation of linear salt structures oriented at right angle to the regional shortening direction. The influence of orogenic shortening during the last steps of the minibasin province evolution is clearly shown by: (i) the squeezing of salt structures to form welds which are developed both at right angle and oblique to the regional shortening direction, (ii) the emergence of thrust faults, (iii) the tilting and rotation of minibasins about vertical axis associated with the formation of strike-slip fault zones, and (iv) the extrusion of salt sheets. The pre-shortening geometry of the salt structures pattern, polygonal network of walls and diapirs versus linear and sub-parallel walls, influence the resultant structural style of the minibasin province subjected to shortening. Preexisting linear depocenter limited by sub-parallel walls accommodate preferentially the shortening compare to the preexisting sub-circular depocenter limited by polygonal network of salt walls and

  11. Linkages between orogenic plateau build-up, fold-thrust shortening, and foreland basin evolution in the Zagros (NW Iran)

    NASA Astrophysics Data System (ADS)

    Barber, D. E.; Stockli, D. F.

    2017-12-01

    The Iranian Plateau (IP) is a thickened, low-relief morphotectonic province of diffuse deformation that formed due to Arabia-Eurasia collision and may serve as a younger analogue for the Tibetan Plateau. Despite detailed geophysical characterization of the IP, its deformation history and relationship to the Zagros fold-thrust belt and its foreland basin evolution remains unresolved. Low-temperature thermochronometry and provenance data from a transect across the internal and external Zagros track growth of the IP and delineate multiphase interaction between upper- and lower-plate processes during closure of the Neotethys and Arabia-Eurasia suturing. Inversion of zircon (U-Th)/He and fission-track data from plutonic and metamorphic basement rocks in the Sanandaj-Sirjan Zone (SSZ) of the IP reveals an initial stage of low-rate exhumation from 36-25 Ma, simultaneous with the onset of tectonic subsidence and marine incursion in the Zagros foreland basin. Overlapping apatite fission-track and (U-Th)/He ages indicate sharp acceleration in SSZ exhumation rates between 20-15 Ma, coincident with rejuvenation of foreland basin subsidence and an influx of Eurasian-derived sediments into the Zagros foreland deposited above an Oligocene unconformity. The mid-Miocene marks a transition in focused exhumation from the SSZ to Arabian lower-plate. Apatite (U-Th)/He ages suggest in-sequence fold-thrust propagation from the High Zagros to simply folded belt from 10 Ma to recent, which is reflected in the foreland by a shift in provenance to dominantly recycled Arabian-derived detritus and clastic facies progradation. Integrated thermochronometric and provenance data document a two-phase outward expansion of the Iranian Plateau and Zagros fold-thrust belt, tightly coupled to distinct phases of basin evolution and provenance shifts in the Zagros foreland. We associate multiple deformation and basin episodes with protracted collisional processes, from subduction of attenuated Arabian

  12. Use of integrated analogue and numerical modelling to predict tridimensional fracture intensity in fault-related-folds.

    NASA Astrophysics Data System (ADS)

    Pizzati, Mattia; Cavozzi, Cristian; Magistroni, Corrado; Storti, Fabrizio

    2016-04-01

    Fracture density pattern predictions with low uncertainty is a fundamental issue for constraining fluid flow pathways in thrust-related anticlines in the frontal parts of thrust-and-fold belts and accretionary prisms, which can also provide plays for hydrocarbon exploration and development. Among the drivers that concur to determine the distribution of fractures in fold-and-thrust-belts, the complex kinematic pathways of folded structures play a key role. In areas with scarce and not reliable underground information, analogue modelling can provide effective support for developing and validating reliable hypotheses on structural architectures and their evolution. In this contribution, we propose a working method that combines analogue and numerical modelling. We deformed a sand-silicone multilayer to eventually produce a non-cylindrical thrust-related anticline at the wedge toe, which was our test geological structure at the reservoir scale. We cut 60 serial cross-sections through the central part of the deformed model to analyze faults and folds geometry using dedicated software (3D Move). The cross-sections were also used to reconstruct the 3D geometry of reference surfaces that compose the mechanical stratigraphy thanks to the use of the software GoCad. From the 3D model of the experimental anticline, by using 3D Move it was possible to calculate the cumulative stress and strain underwent by the deformed reference layers at the end of the deformation and also in incremental steps of fold growth. Based on these model outputs it was also possible to predict the orientation of three main fractures sets (joints and conjugate shear fractures) and their occurrence and density on model surfaces. The next step was the upscaling of the fracture network to the entire digital model volume, to create DFNs.

  13. Along-dip variations of structural style in the Somali Basin deep-water fold and thrust belt (East Africa)

    NASA Astrophysics Data System (ADS)

    Cruciani, Francesco; Rinaldo Barchi, Massimiliano

    2014-05-01

    Continental passive margins are place of extended slope-failure phenomena, which can lead to the formation of gravity-driven deep-water fold and thrust belts (DW-FTBs), in regions where no far-field compressional stress is active. These giant geological features, which are confined to the sedimentary section, consist of extensional-compressional linked systems detached over a common décollement, generally salt or shales. The continental passive margin of northern Kenya and southern Somalia is an excellent and relatively unexplored site for recognizing and understanding the DW-FTBs originated over a regional shale décollement. In this study we have interpreted a 2D seismic data-set of the 1980s, hosted by Marine Geoscience Data System at Lamont-Doherty Earth Observatory of Columbia University (http://www.marine-geo.org), and recently reprocessed by ENI, in order to investigate the structural style of a DW-FTB developed offshore of northern Kenya and southern Somalia (Somali Basin). This region records the oldest sedimentary section of the Indian Ocean since the breakup of Gondwana began in the Middle-Lower Jurassic separating Madagascar from Africa. From the Upper Cretaceous to at least the Lower Miocene, the margin has been characterized by gravitational collapse leading to the formation of a DW-FTB extending more than 400 km along-strike. The northern portion of the DW-FTB is about 150 km wide, whilst in the southern portion is few tens of km wide. We analysed the northern portion along a regional seismic section. Our study represents the first detailed structural interpretation of this DW-FTB since its discovery in the 1980s. The good quality of the available reprocessed seismic data has allowed us to identify remarkable along-dip variations in the structural style. The basal detachment constantly deepens landward, in agreement with a prevailing gravity-spreading deformation process (as in the case of the Niger Delta). On the seismic data are not visible, as

  14. Oroclines - a century of discourse about curved mountain belts (Petrus Peregrinus Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Van der Voo, Rob

    2014-05-01

    generally carried out in fold- and trust-belts, the allochthony of the rotated limbs of the thin-skinned belts implied transport above a basal décollement plane located in the upper crust. Some examples of these thin-skinned oroclines will be given. However, in recent years oroclines have also been proposed as resulting from buckling of ribbon continents (e.g., Panama; D'Entrecasteaux) with the noteworthy Great Alaskan Terrane Wreck, as discussed by Stephen Johnston of the University of Victoria, as prime example. And oroclines of truly continental dimensions have been presented on the basis of paleomagnetic and structural data in Hercynian Europe and Asia (the Kazakhstan and Mongol-Okhotsk oroclines). Because most of the fold- and trust-belt oroclines contain thick carbonate formations; paleomagnetists frequently find that these have been remagnetized in geological episodes that are coeval with mountain building nearby in time and space. A connection between remagnetization and clay diagenesis is a possibility that is currently being investigated. If this is shown to be the case, the last word on oroclines will not have been printed.

  15. Epsilon Eridani Inner Asteroid Belt

    NASA Image and Video Library

    2017-09-14

    SCI2017_0004: Artist's illustration of the Epsilon Eridani system showing Epsilon Eridani b, right foreground, a Jupiter-mass planet orbiting its parent star at the outside edge of an asteroid belt. In the background can be seen another narrow asteroid or comet belt plus an outermost belt similar in size to our solar system's Kuiper Belt. The similarity of the structure of the Epsilon Eridani system to our solar system is remarkable, although Epsilon Eridani is much younger than our sun. SOFIA observations confirmed the existence of the asteroid belt adjacent to the orbit of the Jovian planet. Credit: NASA/SOFIA/Lynette Cook

  16. Continuous Mass Measurement on Conveyor Belt

    NASA Astrophysics Data System (ADS)

    Tomobe, Yuki; Tasaki, Ryosuke; Yamazaki, Takanori; Ohnishi, Hideo; Kobayashi, Masaaki; Kurosu, Shigeru

    The continuous mass measurement of packages on a conveyor belt will become greatly important. In the mass measurement, the sequence of products is generally random. An interesting possibility of raising throughput of the conveyor line without increasing the conveyor belt speed is offered by the use of two or three conveyor belt scales (called a multi-stage conveyor belt scale). The multi-stage conveyor belt scale can be created which will adjust the conveyor belt length to the product length. The conveyor belt scale usually has maximum capacities of less than 80kg and 140cm, and achieves measuring rates of more than 150 packages per minute and more. The output signals from the conveyor belt scale are always contaminated with noises due to vibrations of the conveyor and the product to be measured in motion. In this paper an employed digital filter is of Finite Impulse Response (FIR) type designed under the consideration on the dynamics of the conveyor system. The experimental results on the conveyor belt scale suggest that the filtering algorithms are effective enough to practical applications to some extent.

  17. Safety Belt Use: Traffic Safety Tips

    DOT National Transportation Integrated Search

    1996-01-01

    This fact sheet, NHTSA Facts: Summer 1996, discusses traffic safety tips for wearing seat belts. It describes the correct way to wear a seat belt, how to sit, and differentiates between lap belts and shoulder belts. It points out that air bags provid...

  18. Detrital zircon age distribution from Devonian and Carboniferous sandstone in the Southern Variscan Fold-and-Thrust belt (Montagne Noire, French Massif Central), and their bearings on the Variscan belt evolution

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Faure, Michel; Li, Xian-hua; Chu, Yang; Ji, Wenbin; Xue, Zhenhua

    2016-05-01

    In the Southern French Massif Central, the Late Paleozoic sedimentary sequences of the Montagne Noire area provide clues to decipher the successive tectonic events that occurred during the evolution of the Variscan belt. Previous sedimentological studies already demonstrated that the siliciclastic deposits were supplied from the northern part of the Massif Central. In this study, detrital zircon provenance analysis has been investigated in Early Devonian (Lochkovian) conglomerate and sandstone, and in Carboniferous (Visean to Early Serpukhovian) sandstone from the recumbent folds and the foreland basin of the Variscan Southern Massif Central in Montagne Noire. The zircon grains from all of the samples yielded U-Pb age spectra ranging from Neoarchean to Late Paleozoic with several age population peaks at 2700 Ma, 2000 Ma, 980 Ma, 750 Ma, 620 Ma, 590 Ma, 560 Ma, 480 Ma, 450 Ma, and 350 Ma. The dominant age populations concentrate on the Neoproterozoic and Paleozoic. The dominant concordant detrital zircon age populations in the Lochkovian samples, the 480-445 Ma with a statistical peak around 450 Ma, are interpreted as reflecting the rifting event that separated several continental stripes, such as Armorica, Mid-German Crystalline Rise, and Avalonia from the northern part of Gondwana. However, Ediacaran and Cambrian secondary peaks are also observed. The detrital zircons with ages at 352 - 340 Ma, with a statistical peak around 350 Ma, came from the Early Carboniferous volcanic and plutonic rocks similar to those exposed in the NE part of the French Massif Central. Moreover, some Precambrian grains recorded a more complex itinerary and may have experienced a multi-recycling history: the Archean and Proterozoic grains have been firstly deposited in Cambrian or Ordovician terrigenous rocks, and secondly re-sedimented in Devonian and/or Carboniferous formations. Another possibility is that ancient grains would be inherited grains, scavenged from an underlying but not

  19. Use of seatbelts in cars with automatic belts.

    PubMed Central

    Williams, A F; Wells, J K; Lund, A K; Teed, N J

    1992-01-01

    Use of seatbelts in late model cars with automatic or manual belt systems was observed in suburban Washington, DC, Chicago, Los Angeles, and Philadelphia. In cars with automatic two-point belt systems, the use of shoulder belts by drivers was substantially higher than in the same model cars with manual three-point belts. This finding was true in varying degrees whatever the type of automatic belt, including cars with detachable nonmotorized belts, cars with detachable motorized belts, and especially cars with nondetachable motorized belts. Most of these automatic shoulder belts systems include manual lap belts. Use of lap belts was lower in cars with automatic two-point belt systems than in the same model cars with manual three-point belts; precisely how much lower could not be reliably estimated in this survey. Use of shoulder and lap belts was slightly higher in General Motors cars with detachable automatic three-point belts compared with the same model cars with manual three-point belts; in Hondas there was no difference in the rates of use of manual three-point belts and the rates of use of automatic three-point belts. PMID:1561301

  20. Deformation of Fold-and-Thrust Belts above a Viscous Detachment: New Insights from Analogue Modelling Experiments

    NASA Astrophysics Data System (ADS)

    Nogueira, Carlos R.; Marques, Fernando O.

    2015-04-01

    Theoretical and experimental studies on fold-and-thrusts belts (FTB) have shown that, under Coulomb conditions, deformation of brittle thrust wedges above a dry frictional basal contact is characterized by dominant frontward vergent thrusts (forethrusts) with thrust spacing and taper angle being directly influenced by the basal strength (increase in basal strength leading to narrower thrust spacing and higher taper angles); whereas thrust wedges deformed above a weak viscous detachment, such as salt, show a more symmetric thrust style (no prevailing vergence of thrusting) with wider thrust spacing and shallower wedges. However, different deformation patterns can be found on this last group of thrust wedges both in nature and experimentally. Therefore we focused on the strength (friction) of the wedge basal contact, the basal detachment. We used a parallelepiped box with four fixed walls and one mobile that worked as a vertical piston drove by a computer controlled stepping motor. Fine dry sand was used as the analogue of brittle rocks and silicone putty (PDMS) with Newtonian behaviour as analogue of the weak viscous detachment. To investigate the strength of basal contact on thrust wedge deformation, two configurations were used: 1) a horizontal sand pack with a dry frictional basal contact; and 2) a horizontal sand pack above a horizontal PDMS layer, acting as a basal weak viscous contact. Results of the experiments show that: the model with a dry frictional basal detachment support the predictions for the Coulomb wedges, showing a narrow wedge with dominant frontward vergence of thrusting, close spacing between FTs and high taper angle. The model with a weak viscous frictional basal detachment show that: 1) forethrusts (FT) are dominant showing clearly an imbricate asymmetric geometry, with wider spaced thrusts than the dry frictional basal model; 2) after FT initiation, the movement on the thrust can last up to 15% model shortening, leading to great amount of

  1. Archaean greenstone belts of Sierra Leone with comments on the stratigraphy and metallogeny

    NASA Astrophysics Data System (ADS)

    Umeji, A. C.

    Four belts of weakly metamorphosed volcano-sedimentary material, of about 2700 Ma, are enclosed by older granulites, gneisses and migmatites in the eastern part, and (i) a basal ultramafic unit followed by (ii) mafic to feldspathic differentiate and then (iii) a terminal sedimentary formation has been recognized in all the four belts and their average ratio is ultramafic: mafic (greenstone): sedimentary unit (2:5:3). The belts are linear and tightly folded along N-S to NE-SW axis which is also the regional grain of the structures in the older basement complex that engulfs them. Structural and geochronological evidences suggest that the deformation of these volcano-sedimentary supracrustals began during the Liberian tectonism ( c. 2700 Ma) and culminated at the beginning of the Eburnean (2200 Ma). Diapiric rise of K-rich younger Aechaean granites which sharphy trangressed all the earlier rocks and their structural trends, marked the last geotectonic event in the Archaean of this part of West Africa. Chromite cumulate and asbestiform deposits characterize the layered ultramafic unit. whilst gold and associated base metal sulphides which were derived from the volcanic units became hydrothermally concentrated close to the contact between the volcanic units and the overlying sediments, and also in the fault zones. Iron ore deposits are restricted to the sedimentary units where they occur as banded iron formation. It is only in the huge metasedimetary piles of the Sula-Kangari belt that deposits of iron ore occur in commercially viable quantities. The patterns of distribution, deformation and mineralization in these greenstone belts appear to fit closely into island arc model of plate tectonic theory.

  2. The "seat belt mark" sign: a call for increased vigilance among physicians treating victims of motor vehicle accidents.

    PubMed

    Velmahos, G C; Tatevossian, R; Demetriades, D

    1999-02-01

    The use of seat belts is shown to cause a specific pattern of internal injuries. Skin bruise corresponding to the site of the seat belt is known as the "seat belt mark" (SBM) sign and is associated with a high incidence of significant organ injuries. No study has yet defined the exact incidence of injuries requiring intervention at the presence of this sign. The objective of this study was to find the incidence of surgically correctable injuries in belted car occupants with a SBM sign and to define strategies of early detection and treatment of such injuries. The prospective study included consecutive patients involved in road traffic accidents who were admitted at an academic Level I trauma center. Of 650 car occupants, 410 (63%) were restrained and 77 (12%) had a SBM across the abdomen, chest or neck. The injuries of these 77 patients were compared with the injuries of belted patients without an SBM sign. Of patients with SBMs, 9 per cent had neck bruises, 32 per cent had chest bruises, 40 per cent had abdominal bruises, and 19 per cent had bruises in multiple sites. No significant neck injuries were detected. Three patients were found to have myocardial contusion, and 10 patients had intra-abdominal injuries (predominantly bowel and mesenteric lacerations) requiring laparotomy. There was a near 4-fold increase in thoracic trauma (22.5% versus 6%; P=0.01) and a near 8-fold increase in intra-abdominal trauma (23% versus 3%; P < 0.0001) between the groups of patients with and without SBMs. The presence of the SBM sign should alert the physician to the high likelihood of specific internal injuries. Routine laparotomy or mandatory evaluation by specific diagnostic tests is not justified; rather, a high index of suspicion with a low threshold for appropriate diagnostic evaluation and/or surgical exploration should be maintained for the optimal management of such patients.

  3. Belt separation system under slat in fattening pig housing: effect of belt type and extraction frequency.

    PubMed

    Alonso, F; Vázquez, J; Ovejero, I; Garcimartín, M A; Mateos, A; Sánchez, E

    2010-08-01

    The efficiency of manure separation by a conveyor belt under a partially slatted floor for fattening pigs was determined for two types of belts, a flat belt with an incline of up to 6 degrees transversely and a concave belt with an incline of up to 1 degrees longitudinally. A 31.20% and 23.75% dry matter content of the solid fraction was obtained for the flat and concave belt, respectively. The flat belt was more efficient at 6 degrees than other slope angles. The residence time of the manure on the two belt types influenced the separation efficiency from a live weight of 63.00 kg upwards. The quantity of residue produced with this system was reduced to 25-40% with respect to a pit system under slat. This could mean a remarkable reduction in costs of storage, transport and application of manure. (c) 2010 Elsevier Ltd. All rights reserved.

  4. Seat belt use on interstate highways.

    PubMed Central

    Wells, J K; Williams, A F; Lund, A K

    1990-01-01

    More than 5,000 miles of limited-access highways in the eastern United States and Canada were traveled to observe seat belt use. Overall belt use was 58 percent in the United States and 79 percent in Canada. The data indicate that belt use in the United States follows a different pattern on interstate highways than on other streets and roads, with relatively high belt use rates (over 50 percent) appearing to be somewhat independent of belt use law provisions. PMID:2343969

  5. Tectonics of some Amazonian greenstone belts

    NASA Technical Reports Server (NTRS)

    Gibbs, A. K.

    1986-01-01

    Greenstone belts exposed amid gneisses, granitoid rocks, and less abundant granulites along the northern and eastern margins of the Amazonian Craton yield Trans-Amazonican metamorphic ages of 2.0-2.1 Ga. Early proterozoic belts in the northern region probably originated as ensimatic island arc complexes. The Archean Carajas belt in the southeastern craton probably formed in an extensional basin on older continental basement. That basement contains older Archean belts with pillow basalts and komatiites. Belts of ultramafic rocks warrant investigatijon as possible ophiolites. A discussion follows.

  6. Drivers' assessment of Ford's belt reminder system.

    PubMed

    Williams, Allan F; Wells, Joann K

    2003-12-01

    In recent model years, Ford vehicles have been equipped with a supplementary seat belt reminder system that flashes and chimes intermittently for up to 5 min if the driver is unbelted. Sound- and light-based belt reminder systems of various types are beginning to appear in the market place, and it is important to learn about their acceptance and ability to increase belt use. The present study was designed to ascertain consumer reaction and reported belt use regarding the Ford system. Personal interviews were conducted with 405 drivers of vehicles with the reminder system. Among the drivers, 67% said they had activated the belt reminder one or more times, 73% said that the last time this happened they fastened their belts, 46% said their belt use had increased since driving this vehicle, 78% said they liked the reminder system, and 79% said they wanted a reminder system like this in their next vehicle. Five percent had disabled the system. Part-time users were responsive to the reminder, for example, of those who said they currently used belts usually but not on some occasions, 70% said they fastened their seat belts the last time the reminder was activated and 76% said their belt use had increased. Five percent spontaneously mentioned the belt reminder as an especially disliked feature of their new vehicles, and 2% said their belt use had decreased since having it. The 7% of respondents who reported they used belts never or very occasionally were least responsive to the system. Overall, the Ford belt reminder system is being favorably received.

  7. The design of RFID convey or belt gate systems using an antenna control unit.

    PubMed

    Park, Chong Ryol; Lee, Seung Joon; Eom, Ki Hwan

    2011-01-01

    This paper proposes an efficient management system utilizing a Radio Frequency Identification (RFID) antenna control unit which is moving along with the path of boxes of materials on the conveyor belt by manipulating a motor. The proposed antenna control unit, which is driven by a motor and is located on top of the gate, has an array structure of two antennas with parallel connection. The array structure helps improve the directivity of antenna beam pattern and the readable RFID distance due to its configuration. In the experiments, as the control unit follows moving materials, the reading time has been improved by almost three-fold compared to an RFID system employing conventional fixed antennas. The proposed system also has a recognition rate of over 99% without additional antennas for detecting the sides of a box of materials. The recognition rate meets the conditions recommended by the Electronic Product Code glbal network (EPC)global for commercializing the system, with three antennas at a 20 dBm power of reader and a conveyor belt speed of 3.17 m/s. This will enable a host of new RFID conveyor belt gate systems with increased performance.

  8. The Design of RFID Convey or Belt Gate Systems Using an Antenna Control Unit

    PubMed Central

    Park, Chong Ryol; Lee, Seung Joon; Eom, Ki Hwan

    2011-01-01

    This paper proposes an efficient management system utilizing a Radio Frequency Identification (RFID) antenna control unit which is moving along with the path of boxes of materials on the conveyor belt by manipulating a motor. The proposed antenna control unit, which is driven by a motor and is located on top of the gate, has an array structure of two antennas with parallel connection. The array structure helps improve the directivity of antenna beam pattern and the readable RFID distance due to its configuration. In the experiments, as the control unit follows moving materials, the reading time has been improved by almost three-fold compared to an RFID system employing conventional fixed antennas. The proposed system also has a recognition rate of over 99% without additional antennas for detecting the sides of a box of materials. The recognition rate meets the conditions recommended by the Electronic Product Code glbal network (EPC)global for commercializing the system, with three antennas at a 20 dBm power of reader and a conveyor belt speed of 3.17 m/s. This will enable a host of new RFID conveyor belt gate systems with increased performance. PMID:22164119

  9. Linking Late Cretaceous to Eocene Tectonostratigraphy of the San Jacinto Fold Belt of NW Colombia With Caribbean Plateau Collision and Flat Subduction

    NASA Astrophysics Data System (ADS)

    Mora, J. Alejandro; Oncken, Onno; Le Breton, Eline; Ibánez-Mejia, Mauricio; Faccenna, Claudio; Veloza, Gabriel; Vélez, Vickye; de Freitas, Mario; Mesa, Andrés.

    2017-11-01

    Collision with and subduction of an oceanic plateau is a rare and transient process that usually leaves an indirect imprint only. Through a tectonostratigraphic analysis of pre-Oligocene sequences in the San Jacinto fold belt of northern Colombia, we show the Late Cretaceous to Eocene tectonic evolution of northwestern South America upon collision and ongoing subduction with the Caribbean Plate. We linked the deposition of four fore-arc basin sequences to specific collision/subduction stages and related their bounding unconformities to major tectonic episodes. The Upper Cretaceous Cansona sequence was deposited in a marine fore-arc setting in which the Caribbean Plate was being subducted beneath northwestern South America, producing contemporaneous magmatism in the present-day Lower Magdalena Valley basin. Coeval strike-slip faulting by the Romeral wrench fault system accommodated right-lateral displacement due to oblique convergence. In latest Cretaceous times, the Caribbean Plateau collided with South America marking a change to more terrestrially influenced marine environments characteristic of the upper Paleocene to lower Eocene San Cayetano sequence, also deposited in a fore-arc setting with an active volcanic arc. A lower to middle Eocene angular unconformity at the top of the San Cayetano sequence, the termination of the activity of the Romeral Fault System, and the cessation of arc magmatism are interpreted to indicate the onset of low-angle subduction of the thick and buoyant Caribbean Plateau beneath South America, which occurred between 56 and 43 Ma. Flat subduction of the plateau has continued to the present and would be the main cause of amagmatic post-Eocene deposition.

  10. Geometry and Kinematics of Fault-Propagation Folds with Variable Interlimb Angles

    NASA Astrophysics Data System (ADS)

    Dhont, D.; Jabbour, M.; Hervouet, Y.; Deroin, J.

    2009-12-01

    Fault-propagation folds are common features in foreland basins and fold-and-thrust belts. Several conceptual models have been proposed to account for their geometry and kinematics. It is generally accepted that the shape of fault-propagation folds depends directly from both the amount of displacement along the basal decollement level and the dip angle of the ramp. Among these, the variable interlimb angle model proposed by Mitra (1990) is based on a folding kinematics that is able to explain open and close natural folds. However, the application of this model is limited because the geometric evolution and thickness variation of the fold directly depend on imposed parameters such as the maximal value of the ramp height. Here, we use the ramp and the interlimb angles as input data to develop a forward fold modelling accounting for thickness variations in the forelimb. The relationship between the fold amplitude and fold wavelength are subsequently applied to build balanced geologic cross-sections from surface parameters only, and to propose a kinematic restoration of the folding through time. We considered three natural examples to validate the variable interlimb angle model. Observed thickness variations in the forelimb of the Turner Valley anticline in the Alberta foothills of Canada precisely correspond to the theoretical values proposed by our model. Deep reconstruction of the Alima anticline in the southern Tunisian Atlas implies that the decollement level is localized in the Triassic-Liassic series, as highlighted by seismic imaging. Our kinematic reconstruction of the Ucero anticline in the Spanish Castilian mountains is also in agreement with the anticline geometry derived from two cross-sections. The variable interlimb angle model implies that the fault-propagation fold can be symmetric, normal asymmetric (with a greater dip value in the forelimb than in the backlimb), or reversely asymmetric (with greater dip in the backlimb) depending on the shortening

  11. Pilot tests of a seat belt gearshift delay on the belt use of commercial fleet drivers.

    DOT National Transportation Integrated Search

    2009-12-01

    the seat belt was buckled. Participants, commercial drivers from the United States and Canada who did not consistently wear their seat belts, could avoid the delay by fastening their seat belts. Unbelted participants experienced a delay of either a c...

  12. Normative Misperceptions of Peer Seat Belt Use Among High School Students and Their Relationship to Personal Seat Belt Use

    PubMed Central

    LITT, DANA M.; LEWIS, MELISSA A.; LINKENBACH, JEFFREY W.; LANDE, GARY; NEIGHBORS, CLAYTON

    2016-01-01

    Objectives This research examined gender-specific perceptions of peer seat belt use norms among high school students and their relationship with one’s own seat belt use. We expected that students would underestimate the seat belt use of their peers and that these perceptions would be positively associated with their own seat belt use. Methods High school students from 4 schools (N = 3348; 52% male) completed measures assessing perceived seat belt use and personal seat belt use. Results Findings demonstrated that students perceived that others engaged in less seat belt use than they do and that perceived norms were positively associated with one’s own seat belt use. Conclusions Peer influences are a strong predictor of behavior, especially among adolescents. Ironically, adolescents’ behaviors are often influenced by inaccurate perceptions of their peers. This research establishes the presence of a misperception related to seat belt use and suggests that misperception is associated with own behaviors. This research provides a foundation for social norms–based interventions designed to increase seat belt use by correcting normative misperceptions among adolescents. PMID:24628560

  13. Seat Belt Sign and Its Significance

    PubMed Central

    Agrawal, Amit; Inamadar, Praveenkumar Ishwarappa; Subrahmanyam, Bhattara Vishweswar

    2013-01-01

    Safety belts are the most important safety system in motor vehicles and when worn intend to prevent serious injuries. However, in unusual circumstances (high velocity motor vehicle collisions) these safety measures (seat belts) can be the source and cause of serious injuries. The seat belt syndrome was first described as early by Garrett and Braunste in but the term “seat belt sign” was discussed by Doersch and Dozier. Medical personnel's involved in emergency care of trauma patients should be aware of seat belt sign and there should a higher index of suspicion to rule out underlying organ injuries. PMID:24479100

  14. The Gogebic Iron Range - A Sample of the Northern Margin of the Penokean Fold and Thrust Belt

    USGS Publications Warehouse

    Cannon, William F.; LaBerge, Gene L.; Klasner, John S.; Schulz, Klaus J.

    2008-01-01

    The Gogebic iron range is an elongate belt of Paleoproterozoic strata extending from the west shore of Lake Gogebic in the upper peninsula of Michigan for about 125 km westward into northern Wisconsin. It is one of six major informally named iron ranges in the Lake Superior region and produced about 325 million tons of direct-shipping ore between 1887 and 1967. A significant resource of concentrating-grade ore remains in the western and eastern parts of the range. The iron range forms a broad, gently southward-opening arc where the central part of the range exposes rocks that were deposited somewhat north of the eastern and western parts. A fundamental boundary marking both the tectonic setting of deposition and the later deformation within the Penokean orogen lies fortuitously in an east-west direction along the range so that the central part of the range preserves sediments deposited north of that boundary, whereas the eastern and western parts of the range were deposited south of the boundary. Thus, the central part of the range provides a record of sedimentation and very mild deformation in a part of the Penokean orogen farthest from the interior of the orogen to the south. The eastern and western parts of the range, in contrast, exhibit a depositional and deformational style typical of parts closer to the interior of the orogen. A second fortuitous feature of the iron range is that the entire area was tilted from 40° to 90° northward by Mesoproterozoic deformation so that the map view offers an oblique cross section of the Paleoproterozoic sedimentary sequence and structures. Together, these features make the Gogebic iron range a unique area in which to observe (1) the lateral transition from deposition on a stable platform to deposition in a tectonically and volcanically active region, and (2) the transition from essentially undeformed Paleoproterozoic strata to their folded and faulted equivalents.Paleoproterozoic strata in the Gogebic iron range are part

  15. Kinematics and strain distribution of a thrust-related fold system in the Lewis thrust plate, northwestern Montana (U.S.A.)

    NASA Astrophysics Data System (ADS)

    Yin, An; Oertel, Gerhard

    1993-06-01

    In order to understand interactions between motion along thrusts and the associated style of deformation and strain distribution in their hangingwalls, geologic mapping and strain measurements were conducted in an excellently exposed thrust-related fold system in the Lewis thrust plate, northwestern Montana. This system consists of: (1) an E-directed basal thrust (the Gunsight thrust) that has a flat-ramp geometry and a slip of about 3.6 km; (2) an E-verging asymmetric anticline with its nearly vertical forelimb truncated by the basal thrust from below; (3) a 4-km wide fold belt, the frontal fold complex, that lies directly in front of the E-verging anticline; (4) a W-directed bedding-parallel fault (the Mount Thompson fault) that bounds the top of the frontal fold belt and separates it from the undeformed to broadly folded strata above; and (5) regionally developed, W-dipping spaced cleavage. Although the overall geometry of the thrust-related fold system differs from any previously documented fault-related folds, the E-verging anticline itself resembles geometrically a Rich-type fault-bend fold. The observed initial cut-off and fold interlimb angles of this anticline, however, cannot be explained by cross-section balancing models for the development of either a fault-bend fold or a fault propagation fold. Possible origins for the E-verging anticline include (1) the fold initiated as an open fault-bend fold and tightened only later during its emplacement along the basal thrust and (2) the fold started as either a fault-bend or a fault-propagation fold, but simultaneous or subsequent volume change incompatible with any balanced cross-section models altered its shape. Strain in the thrust-related fold system was determined by the preferred orientation of mica and chlorite grains. The direction and magnitude of the post-compaction strain varies from place to place. Strains in the foreclimb of the hangingwall anticline imply bedding-parallel thinning at some

  16. The immature thrust belt of the northern front of the Tianshan

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Gumiaux, Charles; Augier, Romain; Chen, Yan; Wang, Qingchen

    2010-05-01

    The modern Tianshan (central Asia), which extends east-west on about 2500 km long with an average of more than 2000 m in altitude, is considered as a direct consequence of the reactivation of a Paleozoic belt due to the India - Asia collision. At first order, the finite structure of this range obviously displays a significant uprising of Paleozoic "basement" rocks - as a crustal-scale ‘pop-up' - surrounded by two Cenozoic foreland basins. In order to characterize the coupling history of this Cenozoic orogeny with its northern foreland basin (Junggar basin), a detailed structural field work has been carried out on the northern piedmont of Tianshan. From Wusu to Urumqi, on about 250 km long, the thrusting of the Paleozoic basement on the Mesozoic or Cenozoic sedimentary series of the basin is remarkably exposed along several river valleys. In contrast, in other sections, the Triassic to Jurassic sedimentary series can be followed from the basin to the range where they unconformably overlie on the Carboniferous basement. These series are only gently folded along the "range front". These features imply that, at regional-scale, the Cenozoic reactivation of the Tianshan has not produced important deformation along its contact with the juxtaposed Junggar basin. The shortening ascribed to the Cenozoic intra-continental collision would either be localized in the range, mostly accommodated by reactivated Paleozoic structures or faults in the basement units, or in the distal parts of the Junggar basin, by folds and faults within the Cenozoic sedimentary series. Alternative hypothesis would be that the Tianshan uplift and the movements associated with along its northern front structures, which are traditionally assigned to its Cenozoic reactivation, might be reduced. Such characteristic significantly differs from other well-known orogenic ranges, such as the Canadian Rocky Mountains, the Appalachians, the Pyrenees which display highly folded foreland basins and thrust belts

  17. Deformation of the Eastern Franciscan Belt, northern California

    USGS Publications Warehouse

    Jayko, A.S.; Blake, M.C.

    1989-01-01

    The late Jurassic and Cretaceous Eastern Franciscan belt of the northern California Coast Range consists of two multiply deformed, blueschist-facies terranes; the Pickett Peak and Yolla Bolly terranes. Four deformations have been recognized in the Pickett Peak terrane, and three in the Yolla Bolly terrane. The earliest recognized penetrative fabric, D1, occurs only in the Pickett Peak terrane. The later penetrative fabrics, D2 and D3, occur in both the Yolla Bolly and Pickett Peak terranes. D1 and D2 apparently represent fabrics that formed during subduction and accretion of the terranes. Fabrics from both D1 and D2 are consistent with SW-NE movement directions with respect to their present geographic positions. D3 postdates blueschist-facies metamorphism of the terranes and may be related to emplacement of the terranes to higher structural levels. A broad regional warping, D4, is evident from the map pattern and folding of large metamorphosed thrust sheets. D4 folds may be related to deformation associated with oblique convergence along the continental margin in late Cretaceous and (or) early Tertiary time. ?? 1989.

  18. Investigation of neotectonic deformation in the eastern part of the Caucasus Intermountain Area, Kura Fold-Thrust Belt, Georgia

    NASA Astrophysics Data System (ADS)

    Sukhishvili, L.; Javakhishvili, Z.; Forte, A. M.; Boichenko, G.; Merebashvili, G.

    2016-12-01

    The Kura Fold-Thrust Belt (KFTB), located in the eastern Caucasus, is a young first-order structural system within the Arabia-Eurasia collision zone and absorbs greater than 50% of total convergence between the Greater and Lesser Caucasus at this longitude. The structure, activity, and initiation age of the KFTB is well constrained in Azerbaijan, but less so within Georgia. Based on regional stratigraphic relationships, it is suggested that deformation of the Georgian portion of the KFTB initiated before or during Akchagyl time (3.4-1.6 Ma), but field data verifying this hypothesis is lacking. The Gombori Range represents the western extent of the KFTB, rises to elevations > 1900 m, and currently is a topographic barrier to south-directed rivers flowing from the Greater Caucasus, with the first river crossing the KFTB >100 km to the east. The Gombori Range also contains exposures of deformed Pliocene to Quaternary fluvial sediments that likely record a drainage network reorganization in response to the growth of the KFTB and a shift from through-going south-flowing rivers to the current network. To test this hypothesis, we focus on 1 km exposure of continuous Plio-Quaternary section along the Turdo river, which flows northwards from the Gombori range. The exposures are a >40 m vertical cliff, so we first use photogrammetry to construct a digital outcrop model and analyze it in a virtual reality environment to select strategic locations for detailed paleocurrent analysis in attempt to bracket the timing of KFTB development. Understanding the history and current location of active deformation in this region is essential for seismic hazard assessment for the nearby major cities of Telavi and Tbilisi. From previous active fault studies, the maximum earthquake magnitude in this region is Mw=7.0 and the strongest recorded earthquake was a Mw=5.3 in 1997. Observed seismicity is sparse and it's difficult to delineate active faults by earthquakes hypocenters. To determine

  19. Geochronology and thermochronology of Cretaceous plutons and metamorphic country rocks, Anyui-Chukotka fold belt, North East Arctic Russia

    NASA Astrophysics Data System (ADS)

    Miller, E. L.; Katkov, S. M.; Strickland, A.; Toro, J.; Akinin, V. V.; Dumitru, T. A.

    2009-09-01

    U-Pb isotopic dating of seven granitoid plutons and associated intrusions from the Bilibino region (Arctic Chukotka, Russia) was carried out using the SHRIMP-RG. The crystallization ages of these granitoids, which range from approximately 116.9±2.5 to 108.5±2.7 Ma, bracket two regionally significant deformational events. The plutons cut folds, steep foliations and thrust-related structures related to sub-horizontal shortening at lower greenschist facies conditions (D1), believed to be the result of the collision of the Arctic Alaska-Chukotka microplate with Eurasia along the South Anyui Zone (SAZ). Deformation began in the Late Jurassic, based on fossil ages of syn-orogenic clastic strata, and involves strata as young as early Cretaceous (Valanginian) north of Bilibino and as young as Hauterivian-Barremian, in the SAZ. The second phase of deformation (D2) is developed across a broad region around and to the east of the Lupveem batholith of the Alarmaut massif and is interpreted to be coeval with magmatism. D2 formed gently-dipping, high-strain foliations (S2). Growth of biotite, muscovite and actinolite define S2 adjacent to the batholith, while chlorite and white mica define S2 away from the batholith. Sillimanite (± andalusite) at the southeastern edge the Lupveem batholith represent the highest grade metamorphic minerals associated with D2. D2 is interpreted to have developed during regional extension and crustal thinning. Extension directions as measured by stretching lineations, quartz veins, boudinaged quartz veins is NE-SW to NW-SE. Mapped dikes associated with the plutons trend mostly NW-SE and indicate NE-SW directed extension. 40Ar/39Ar ages from S2 micas range from 109.3±1.2 to 103.0±1.8 Ma and are interpreted as post-crystallization cooling ages following a protracted period of magmatism and high heat flow. Regional uplift and erosion of many kilometers of cover produced a subdued erosional surface prior to the eruption of volcanic rocks of the

  20. Pelvic belt effects on sacroiliac joint ligaments: a computational approach to understand therapeutic effects of pelvic belts.

    PubMed

    Sichting, Freddy; Rossol, Jerome; Soisson, Odette; Klima, Stefan; Milani, Thomas; Hammer, Niels

    2014-01-01

    The sacroiliac joint is a widely described source of low back pain. Therapeutic approaches to relieve pain include the application of pelvic belts. However, the effects of pelvic belts on sacroiliac joint ligaments as potential pain generators are mostly unknown. The aim of our study was to analyze the influence of pelvic belts on ligament load by means of a computer model. Experimental computer study using a finite element method. A computer model of the human pelvis was created, comprising bones, ligaments, and cartilage. Detailed geometries, material properties of ligaments, and in-vivo pressure distribution patterns of a pelvic belt were implemented. The effects of pelvic belts on ligament strain were computed in the double-leg stance. Pelvic belts increase sacroiliac joint motion around the sagittal axis but decrease motion around the transverse axis. With pelvic belt application, most of the strained sacroiliac joint ligaments were relieved, especially the sacrospinous, sacrotuberous, and the interosseous sacroiliac ligaments. Sacroiliac joint motion and ligament strains were minute. These results agree with validation data from other studies. Assigning homogenous and linear material properties and excluding muscle forces are clear simplifications of the complex reality. Pelvic belts alter sacroiliac joint motion and provide partial relief of ligament strain that is subjectively marked, although minimal in absolute terms. These findings confirm theories that besides being mechanical stabilizers, the sacroiliac joint ligaments are likely involved in neuromuscular feedback mechanisms. The results from our computer model help with unraveling the therapeutic mechanisms of pelvic belts.

  1. Seismic profile analysis of the Kangra and Dehradun re-entrant of NW Himalayan Foreland thrust belt, India: A new approach to delineate subsurface geometry

    NASA Astrophysics Data System (ADS)

    Dey, Joyjit; Perumal, R. Jayangonda; Sarkar, Subham; Bhowmik, Anamitra

    2017-08-01

    In the NW Sub-Himalayan frontal thrust belt in India, seismic interpretation of subsurface geometry of the Kangra and Dehradun re-entrant mismatch with the previously proposed models. These procedures lack direct quantitative measurement on the seismic profile required for subsurface structural architecture. Here we use a predictive angular function for establishing quantitative geometric relationships between fault and fold shapes with `Distance-displacement method' (D-d method). It is a prognostic straightforward mechanism to probe the possible structural network from a seismic profile. Two seismic profiles Kangra-2 and Kangra-4 of Kangra re-entrant, Himachal Pradesh (India), are investigated for the fault-related folds associated with the Balh and Paror anticlines. For Paror anticline, the final cut-off angle β =35{°} was obtained by transforming the seismic time profile into depth profile to corroborate the interpreted structures. Also, the estimated shortening along the Jawalamukhi Thrust and Jhor Fault, lying between the Himalayan Frontal Thrust (HFT) and the Main Boundary Thrust (MBT) in the frontal fold-thrust belt, were found to be 6.06 and 0.25 km, respectively. Lastly, the geometric method of fold-fault relationship has been exercised to document the existence of a fault-bend fold above the Himalayan Frontal Thrust (HFT). Measurement of shortening along the fault plane is employed as an ancillary tool to prove the multi-bending geometry of the blind thrust of the Dehradun re-entrant.

  2. Seat belt use-inducing system effectiveness

    DOT National Transportation Integrated Search

    1975-04-01

    Seat belt use inducing system effectiveness was measured in fleet automobiles of a private business and in rental automobiles at a large airport. There were three parts to the activity: 1. Seat belt use inducing systems and seat belt use counting sys...

  3. Small Main-Belt Asteroid Lightcurve Survey

    NASA Technical Reports Server (NTRS)

    Binzel, Richard P.; Xu, Shui; Bus, Schelte J.; Bowell, Edward

    1992-01-01

    The Small Main-Belt Asteroid Lightcurve Survey is the first to measure main-belt asteroid lightcurve properties for bodies with diameters smaller than 5 km. Attention is given to CCD lightcurves for 32 small main-belt asteroids. The objects of this sample have a mean rotational frequency which is faster than that of larger main-belt asteroids. All lightcurves were investigated for nonperiodic variations ascribable to free precession; no conclusive detection of this phenomenon has been made, however.

  4. Microfractures in bed-parallel veins (beef) as predictors of vertical macrofractures in shale: Vaca Muerta Formation, Agrio Fold-and-Thrust Belt, Argentina

    NASA Astrophysics Data System (ADS)

    Ukar, Estibalitz; Lopez, Ramiro G.; Laubach, Stephen E.; Gale, Julia F. W.; Manceda, René; Marrett, Randall

    2017-11-01

    Shales of the Upper Jurassic-Lower Cretaceous Vaca Muerta Formation are the main source rock for petroleum in the Neuquén Basin, Argentina and an important unconventional exploration target. Folded Vaca Muerta Formation is well exposed in the Agrio Fold-and-Thrust belt where an arid climate and rapid erosion reveal relatively unweathered shale strata accessible along creek beds at Arroyo Mulichinco and in 10+ m-tall cliffs at Puesto. Widespread within these organic-rich shales are several cm-thick, prominent bed-parallel veins (BPVs) of fibrous calcite (beef) that are cut by multiple sets of vertical calcite lined or filled fractures having apertures unaffected by near-surface stress release. Similar, and probably contemporaneous fractures are present within horizons of interbedded dolomitic rock. Evidence that vertical fractures in BPVs and dolomitic horizons continue into shale beds suggests that in-depth analysis of vertical fractures within BPVs and dolomitic horizons allows fracture set and orientation identification and size population measurements-primarily aperture distributions-that circumvent some of the limitations of shale outcrops. At Arroyo Mulichinco, four main fracture sets are present separable by orientation and crosscutting relations. An E-W set is oldest, followed by successively younger NE-SW, NW-SE, and N-S sets. At Puesto, the E-W and N-S sets are the most prominent and show opposite cross-cutting relationships (E-W set is youngest) indicating a possible episode of younger E-W fractures. The E-W set shows the highest micro-and macrofracture intensity at both localities. The intensity of N-S micro- and macrofractures is similar at both outcrops away from faults, but macrofracture intensity increases closer to faults. While macrofracture abundance is similar in BPVs and in shale, microfractures having apertures smaller than ∼0.1 mm are mostly absent in shale and dolomitic layers but are abundant cutting BPVs. Thus, microfractures are BPV

  5. Morphotectonic aspects of active folding in Zagros Mountains (Fin, SE of Iran)

    NASA Astrophysics Data System (ADS)

    Roustaei, M.; Abbasi, M.

    2008-05-01

    Active deformation in Iran, structural province of Zagros is a result of the convergence between the Arabian & Eurasian plates. The Zagros Mountains in southern Iran are one of the seismically active region & is introduced as fold-thrust belt trending NW-SE within the Arabian plate. Fin lies in Hormozgan province; the south of Iran. The vastness is surrounded by central Iran in the north, High Zagros in the North West and west, Folded Zagros in the east, Makran in the south east and Persian Gulf in the south. The study area is determined by complex structures, alternation of folding, salt diapers and faulting. The surface geology mainly comprises Neogene; Marls, Conglomerate, Sandstones (Mishan, Aghajari, Bakhtiyari formations), old fans and alluvium as syncline that Shur River cuts its north limb and passes from the middle of core .The older formations( Ghachsaran, Rzak and Guri member) folded into prominent anticlines. The fold axes mostly follow the parallel trends .Folds trending are NW-SE (Tashkend anticline), NE-SW (Khur anticline), E-W (Guniz & Handun anticline) and the trend of axes Baz fold in the main part is E-W. Hormoz salt also outcrops in the cores of many whaleback anticlines. Thus, anticlines may be cored with evaporates, even though no salt is currently exposed at the surface. Reason of selecting this area as an example referred to active seismcity. Release of energy is gradually in every events, this seismic character cusses that there was not earthquake with high magnitude in the area but it can not be a role. Answer to the question concerning relationship between folding of the crust layer and faulting at depth is more difficult. There is 2 terms to describe this relationship; "detachment folds" and" forced folds". In this paper, we try to analysis of different satellite imagery; Aster, spot and digital elevation model with high resolution (10 m) in order to detect geomorphic indicators which can help us to find a relationship between faulting

  6. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Safety belts. 27.1413 Section 27.1413 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety belt...

  7. 14 CFR 27.1413 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Safety belts. 27.1413 Section 27.1413 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1413 Safety belts. Each safety belt...

  8. Persistence of Salmonella on egg conveyor belts is dependent on the belt type but not on the rdar morphotype.

    PubMed

    Stocki, S L; Annett, C B; Sibley, C D; McLaws, M; Checkley, S L; Singh, N; Surette, M G; White, A P

    2007-11-01

    Commercial caged layer flocks in Alberta, Canada, are commonly monitored for Salmonella enterica serovar Enteritidis (SE) and S. enterica serovar Typhimurium (ST) by environmental sampling. In one recent case, a SE strain isolated from the egg conveyor belt was a source of persistent infection for the flock. This study was undertaken to examine Salmonella colonization on egg conveyor belts and to determine whether the rdar morphotype, a conserved physiology associated with aggregation and long-term survival, contributed to persistence. Four woven belts constructed of natural or nonnatural fibers and a 1-piece belt made of vinyl were tested with rdar-positive ST and SE strains and a rdar-negative ST DeltaagfD reference strain. The type of egg belt was the most important factor influencing Salmonella colonization and persistence. The vinyl belt, with the least surface area available for colonization, had the fewest Salmonella remaining after washing and disinfection, whereas the hemp-plastic belt, with the greatest surface area, had the most Salmonella remaining. Real-time gene expression indicated that the rdar morphotype was involved in colonizing the egg belt pieces; however, it was not essential for persistence. In addition, rdar-positive and rdar-negative strains were equally similarly to disinfection on the egg belt pieces. The results indicate that Salmonella can persist on a variety of egg belts by mechanisms other than the rdar morphotype, and that using egg conveyer belts with reduced surface area for bacterial colonization can lessen contamination problems.

  9. Geodynamic processes and deformation in orogenic belts

    NASA Astrophysics Data System (ADS)

    Dennis, John G.; Jacoby, Wolfgang R.

    1980-03-01

    The development of geosynclines and orogenic belts is related to lithosphere convergence. Initial sediment accumulation implying subsidence, and volcanic activity implying extension and rise of geotherms, are in most cases followed by folding and thrusting suggesting compression and by uplift. In terms of recent analogs, sediment accumulation and crustal extension are characteristic of back-arc spreading; subsequent compression would indicate continent—continent collision; and rise of geotherms most likely requires localized thermal flow (convection) in the asthenosphere. These events are here shown to agree with Andrews and Sleep's (1974) numerical model of asthenosphere flow at converging plate margins. Orthogeosynclinal subsidence appears to be a consequence of subcrustal ablation and lithosphere extension and thinning in active marginal basins. Arc and Andean type magmatism mark the reappearance of ablated and transported, relatively low-density subcrustal material. Collision slows and eventually stops the local convection cell, resulting in local heat accumulation and hence high- T, low- P metamorphism and granitization while marginal basin (orthogeosynclinal) deposits are being compressed into Alpine style orogenic structures. Moreover, closing of the marginal basin leads to subsidiary subduction, which in turn may be responsible for some Alpine style structures. Oceanic trench deposits may become incorporated in orogenic zones, as high- P, low- T metamorphic belts (thalassogeosynclines). Dynamic uplift is a fundamental characteristic of orogeny. Most rising and sinking in orogenic zones can be linked to those asthenosphere processes which are a consequence of Andrews-Sleep convection.

  10. Granulite belts of Central India with special reference to the Bhopalpatnam Granulite Belt: Significance in crustal evolution and implications for Columbia supercontinent

    NASA Astrophysics Data System (ADS)

    Vansutre, Sandeep; Hari, K. R.

    2010-11-01

    The Central Indian collage incorporates the following major granulite belts: (1) the Balaghat-Bhandara Granulite Belt (BBG), (2) the Ramakona-Katangi Granulite Belt (RKG), (3) the Chhatuabhavna Granulite (CBG) of Bilaspur-Raigarh Belt, (4) the Makrohar Granulite Belt (MGB) of Mahakoshal supracrustals, (5) the Kondagaon Granulite Belt (KGGB), (6) the Bhopalpatnam Granulite Belt (BGB), (7) the Konta Granulite Belt (KTGB) and (8) the Karimnagar Granulite Belt (KNGB) of the East Dharwar Craton (EDC). We briefly synthesize the general geologic, petrologic and geochronologic features of these belts and explain the Precambrian crustal evolution in Central India. On the basis of the available data, a collisional relationship between Bastar craton and the EDC during the Paleo-Mesoproterozoic is reiterated as proposed by the earlier workers. The tectonic evolution of only few of the orogenic belts (BGB in particular) of Central India is related to Columbia.

  11. Structure, metamorphism, and geochronology of the Cosmos Hills and Ruby Ridge, Brooks Range schist belt, Alaska

    USGS Publications Warehouse

    Christiansen, Peter B.; Snee, Lawrence W.

    1994-01-01

    The boundary of the internal zones of the Brooks Range orogenic belt (the schist belt) is a fault contact that dips toward the hinterland (the Yukon-Koyukuk province). This fault, here referred to as the Cosmos Hills fault zone, juxtaposes oceanic rocks and unmetamorphosed sedimentary rocks structurally above blueschist-to-greenschist facies metamorphic rocks of the schist belt. Near the fault contact, schist belt rocks are increasingly affected by a prominent, subhorizontal transposition foliation that is locally mylonitic in the fault zone. Structural and petrologic observations combined with 40Ar/39Ar incremental-release geochronology give evidence for a polyphase metamorphic and deformational history beginning in the Middle Jurassic and continuing until the Late Cretaceous. Our 40Ar/39Ar cooling age for Jurassic metamorphism is consistent with stratigraphic and other evidence for the onset of Brooks Range orogenesis. Jurassic metamorphism is nearly everywhere overprinted by a regional greenschist-facies event dated at 130–125 Ma. Near the contact with the Cosmos Hills fault zone, the schist belt is increasingly affected by a younger greenschist metamorphism that is texturally related to a prominent foliation that folds and transposes an older fabric. The 40Ar/39Ar results on phengite and fuchsite that define this younger fabric give recrystallization ages ranging from 103 to less than 90 Ma. We conclude that metamorphism that formed the transposition fabric peaked around 100 Ma and may have continued until well after 90 Ma. This age for greenschist metamorphism is broadly synchronous with the depositional age of locally derived, shallow-marine clastic sedimentary strata in the hanging wall of the fault zone and thus substantiates the interpretation that the fault zone accommodated extension in the Late Cretaceous. This extension unroofed and exhumed the schist belt during relative subsidence of the Yukon-Koyukuk province.

  12. Reduced fatalities related to rear seat shoulder belts

    PubMed Central

    Robertson, L.

    1999-01-01

    Methods—During 1988–96, fatalities to rear outboard seat occupants of passenger cars, classified by age of occupant and vehicle curb weight were matched to data on model year in which shoulder belts became standard equipment. The same data were obtained from the same years on back seat occupants in crashes from the Crashworthiness Data System. Weighted regression was performed on death rates per occupants in crashes by belt equipment, occupant age, and vehicle weight for all occupants and occupants who claimed to be restrained. Results—The risk of death is significantly lower in vehicles equipped with shoulder belts, midsized to larger cars, and among children. Claimed child restraint use is higher in cars with shoulder belts and claimed use of shoulder belts is higher among adolescents and young adults but lower among those 35 and older. However, older occupants have lower death rates in shoulder belt equipped cars. Conclusions—Shoulder belts substantially reduce risk of death relative to lap belts at prevalent use rates in each age group. Belt effectiveness when used cannot be estimated precisely because of invalid claimed use, but the lowered rates among vehicles with shoulder belts indicates that effectiveness given prevalent use is far more efficacious than lap belts without shoulder belts. PMID:10323573

  13. Observed use of automatic seat belts in 1987 cars.

    PubMed

    Williams, A F; Wells, J K; Lund, A K; Teed, N

    1989-10-01

    Usage of the automatic belt systems supplied by six large-volume automobile manufacturers to meet the federal requirements for automatic restraints were observed in suburban Washington, D.C., Chicago, Los Angeles, and Philadelphia. The different belt systems studied were: Ford and Toyota (motorized, nondetachable automatic shoulder belt), Nissan (motorized, detachable shoulder belt), VW and Chrysler (nonmotorized, detachable shoulder belt), and GM (nonmotorized detachable lap and shoulder belt). Use of automatic belts was significantly greater than manual belt use in otherwise comparable late-model cars for all manufacturers except Chrysler; in Chrysler cars, automatic belt use was significantly lower than manual belt use. The automatic shoulder belts provided by Ford, Nissan, Toyota, and VW increased use rates to about 90%. Because use rates were lower in Ford cars with manual belts, their increase was greater. GM cars had the smallest increase in use rates; however, lap belt use was highest in GM cars. The other manufacturers supply knee bolsters to supplement shoulder belt protection; all--except VW--also provide manual lap belts, which were used by about half of those who used the automatic shoulder belt. The results indicate that some manufacturers have been more successful than others in providing automatic belt systems that result in high use that, in turn, will mean fewer deaths and injuries in those cars.

  14. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Safety belts. 31.63 Section 31.63 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Design Construction § 31.63 Safety belts. (a) There must be a safety belt...

  15. 14 CFR 31.63 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Safety belts. 31.63 Section 31.63 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Design Construction § 31.63 Safety belts. (a) There must be a safety belt...

  16. Mandatory seat belt use.

    DOT National Transportation Integrated Search

    1984-01-01

    The purposes of this study were to review mandatory seat belt use laws as they have been used around the world, to forecast the impact of such a law in Virginia, and, if appropriate, to propose a mandatory seat belt law for inclusion in the Code of V...

  17. Destruction of the North China Craton: Lithosphere folding-induced removal of lithospheric mantle?

    NASA Astrophysics Data System (ADS)

    Zhang, Kai-Jun

    2012-01-01

    High heat flow, high surface topography, and widespread volcanism indicate that the lithospheric mantle of typical cratonic character of the North China Craton has been seriously destroyed in its eastern half. However, the mechanism of this process remains open to intense debate. Here lithosphere folding-induced lithospheric mantle removal is proposed as a new mechanism for the destruction of the craton. Four main NNE-SSW-striking lithospheric-scale anticlines and synclines are recognized within North China east of the Helan fold-and-thrust belt. The lithosphere folding occurred possibly during the Late Triassic through Jurassic when the Yangzi Craton collided with the North China Craton. It was accompanied or followed by lithospheric dripping, and could have possibly induced the lithosphere foundering of the North China Craton. The lithosphere folding would have modified the lithosphere morphology, creating significant undulation in the lithospheric base and thus causing variations of the patterns of the small-scale convection. It also could have provoked the formation of new shear zones liable to impregnation of magma, producing linear incisions at the cratonic base and resulting in foundering of lithospheric mantle blocks. Furthermore, it generated thickening of the lithosphere or the lower crust and initiated the destabilization and subsequent removal of the lithospheric mantle.

  18. 46 CFR 169.723 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Safety belts. 169.723 Section 169.723 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.723 Safety belts. Each vessel must carry a harness type safety belt conforming to Offshore Racing Council (ORC) standards for each person on watch or...

  19. 46 CFR 169.723 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Safety belts. 169.723 Section 169.723 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.723 Safety belts. Each vessel must carry a harness type safety belt conforming to Offshore Racing Council (ORC) standards for each person on watch or...

  20. 30 CFR 77.1107 - Belt conveyors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Belt conveyors. 77.1107 Section 77.1107 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... § 77.1107 Belt conveyors. Belt conveyors in locations where fire would create a hazard to personnel...

  1. Seat belt use in cars with air bags.

    PubMed Central

    Williams, A F; Wells, J K; Lund, A K

    1990-01-01

    Seat belt use was observed in 1,628 cars with air bags and manual belts and 34,223 cars with manual seat belts only. Sixty-six percent of drivers in cars with air bags wore seat belts compared to 63 percent of drivers in cars with manual belts only. The study found no evidence for the speculation that drivers with air bags will reduce their seat belt use because they believe an air bag alone provides sufficient protection. PMID:2240346

  2. Crustal shortening followed by extensional collapse of the Cordilleran orogenic belt in northwestern Montana: Evidence from vintage seismic reflection profiles acquired in the Swan Range and Swan Valley

    NASA Astrophysics Data System (ADS)

    Rutherford, B. S.; Speece, M. A.; Stickney, M. C.; Mosolf, J. G.

    2013-12-01

    Reprocessing of one 24-fold (96 channel) and four 30-fold (120 channel) 2D seismic reflection profiles have revealed crustal scale reflections in the Swan Range and adjacent Swan River Valley of northwestern Montana. The five reprocessed profiles constitute 142.6 of the 303.3 linear km acquired in 1983-84 by Techo of Denver, Colorado. The four 30-fold profiles used helicopter-assisted dynamite shooting (Poulter method) and the 24-fold profile used the Vibroseis method. Acquisition parameters were state of the art for the time. The Swan Range lies east of the Rocky Mountain Trench and is part of the Cordilleran foreland thrust belt where the Lewis thrust system emplaced a thick slab of Proterozoic Belt Supergroup strata eastward and over Paleozoic and Mesozoic rocks during the Late Cretaceous to early Paleocene Laramide orogeny. Deeply drilled borehole data are absent within the study area; however, we generated a synthetic seismogram from the Arco-Marathon 1 Paul Gibbs well (total depth=5418 m), located approximately 70 km west of the reprocessed profiles, and correlated the well data to surface seismic profiles. Large impedance contrasts in the log data are interpreted to be tholeiitic Moyie sills within the Prichard Formation argillite (Lower Belt), which produce strong reflection events in regional seismic sections and result in highly reflective, east-dipping events in the reprocessed profiles. We estimate a depth of 10 km (3 to 3.5 seconds) to the basal detachment of the Lewis thrust sheet. The décollement lies within Belt Supergroup strata to the west of the Swan River Valley before contacting unreflective, west-dipping crystalline basement beneath the Swan Range--a geometry that results in a wedge of eastward-thinning, autochthonous Belt rocks. Distinct fault-plane signatures from the west-dipping, range-bounding Swan fault--produced by extensional collapse of the over-thickened Cordillera--are not successfully imaged. However, reflections from Cenozoic

  3. Evaluation of clinical breast examination and breast ultrasonography among pregnant women in Abakaliki, Nigeria

    PubMed Central

    Ezeonu, Paul Olisaemeka; Ajah, Leonard Ogbonna; Onoh, Robinson Chukwudi; Lawani, Lucky Osaheni; Enemuo, Vincent Chidi; Agwu, Uzoma MaryRose

    2015-01-01

    Background Breast cancer in pregnancy accounts for 2%–3% of all breast cancers. The increased vascularity and lymphatic drainage from the breast during pregnancy potentiate the metastatic spread of the cancer to the regional lymph nodes. However, the increased breast density in pregnancy makes it difficult to detect breast lesions early. Aim To evaluate and compare the detection rate of breast lesions using clinical breast examination (CBE) and breast ultrasonography among pregnant women. Methodology A cross-sectional comparative study involving antenatal clinic attendees at the Federal Teaching Hospital, Abakaliki, was conducted between March 3, 2014, and December 31, 2014. CBE and breast ultrasonography were done in the participants at booking and repeated at 6 weeks postpartum. Fine-needle aspiration cytology and histology were done in women with suspicious breast lesions on CBE or breast ultrasonography or both. Data analysis was both descriptive and inferential at the 95% confidence level using the Statistical Package for the Social Sciences (SPSS) software version 17.0. Test of significance was done using chi-square test. A P-value of less than or equal to 0.05 was considered statistically significant. Results A total of 320 pregnant women participated in the study. Of these, 267 (83.4%) were aware of breast cancer. Although more lesions were detected with breast ultrasonography than by CBE, there was no statistically significant difference between them (25 versus 17; P=0.26). The histology of the lesions revealed 21 benign lesions and 4 normal breast tissues. The sensitivity of breast ultrasonography was 95.2%, while that of CBE was 66.7%. The specificity, positive predictive value, and negative predictive value were similar between CBE and breast ultrasonography. Conclusion The detection rates of breast lesions by both CBE and breast ultrasonography were equivalent during pregnancy and 6 weeks postpartum, making CBE a convenient and very cost

  4. Investigation of Moving Belt Radiator Technology Issues

    NASA Technical Reports Server (NTRS)

    Teagan, W. Peter; Aguilar, Jerry L.

    1994-01-01

    The development of an advanced spacecraft radiator technology is reported. The moving belt radiator is a thermal radiator concept with the promise of lower specific mass (per kW rejected) than that afforded by existing technologies. The results of a parametric study to estimate radiator mass for future space power systems is presented. It is shown that this technology can be scaled up to 200 MW for higher rejection temperatures. Several aspects of the design concept are discussed, including the dynamics of a large rotating belt in microgravity. The results of a computer code developed to model the belt dynamics are presented. A series of one-g experiments to investigate the dynamics of small belts is described. A comprehensive test program to investigate belt dynamics in microgravity aboard the NASA KC-135 aircraft is discussed. It was found that the desired circular shape can readily be achieved in microgravity. It is also shown that a rotating belt is stable when subjected to simulated attitude control maneuvers. Heat exchanger design is also investigated. Several sealing concepts were examined experimentally, and are discussed. Overall heat transfer coefficients to the rotating belt are presented. Material properties for various belt materials, including screen meshes, are also presented. The results presented in this report indicate that the moving belt radiator concept is technically feasible.

  5. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Safety belts. 4.15 Section 4... TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger occupying any seating position of a motor vehicle in a park area will have the safety belt or child restraint system properly fastened at...

  6. 36 CFR 4.15 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Safety belts. 4.15 Section 4... TRAFFIC SAFETY § 4.15 Safety belts. (a) Each operator and passenger occupying any seating position of a motor vehicle in a park area will have the safety belt or child restraint system properly fastened at...

  7. Klippen Belt, Flysch Belt and Inner Western Carpathian Paleogene Basin Relations in the Northern Slovakia by Magnetotelluric Imaging

    NASA Astrophysics Data System (ADS)

    Majcin, Dušan; Bezák, Vladimír; Klanica, Radek; Vozár, Ján; Pek, Josef; Bilčík, Dušan; Telecký, Josef

    2018-05-01

    The paper presents the interpretation of magnetotelluric measurements along the SW-NE profile near Stará Ľubovňa (Northern Slovakia). The profile passes through the Outer Carpathian Flysch Belt, Klippen Belt and ends in the Inner Western Carpathians Paleogene NW from Ružbachy horst structure. The interpretation of the older measurements from profile Mt4 was utilized and, moreover, the 3-D geoelectrical model of studied region was constructed. The magnetotelluric data interpretations verified the northern inclination of Flysch belt structures and their smaller thickness out of Klippen Belt in direction to the Carpathian electrical conductivity zone axis. We consider this as a consequence of the flower structure—more precisely the southern branch of the suture zone related to mentioned conductivity zone. Northerly from this zone the thickness of the Outer Carpathian Flysch Belt increases and the structures have inclination to the south, i.e. to the subduction zone. The contact of Flysch Belt with Klippen Belt has a fault character and it is subvertical, slightly inclined to the North. The southern boundary between Klippen Belt and Inner Western Carpathians has also fault character and is very steep. We detect the continuation of the Ružbachy horst to the NE in the basement of Inner Western Carpathian Paleogene. The structural discordance between this horst and Klippen Belt direction is a result of younger tectonic processes. According to our results the depth distribution of the pre-Tertiary basement below the Inner Western Carpathian units is non-uniform; the basement is broken to a number of partial blocks—horsts and grabens.

  8. Inner Radiation Belt Dynamics and Climatology

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, P. P.; Looper, M. D.

    2012-12-01

    We present preliminary results of inner belt proton data assimilation using an augmented version of the Selesnick et al. Inner Zone Model (SIZM). By varying modeled physics parameters and solar particle injection parameters to generate many ensembles of the inner belt, then optimizing the ensemble weights according to inner belt observations from SAMPEX/PET at LEO and HEO/DOS at high altitude, we obtain the best-fit state of the inner belt. We need to fully sample the range of solar proton injection sources among the ensemble members to ensure reasonable agreement between the model ensembles and observations. Once this is accomplished, we find the method is fairly robust. We will demonstrate the data assimilation by presenting an extended interval of solar proton injections and losses, illustrating how these short-term dynamics dominate long-term inner belt climatology.

  9. Seat belt injuries in impact.

    DOT National Transportation Integrated Search

    1969-03-01

    Although the seat belt has been demonstrated to provide effective reduction of injuries and fatalities in automobile accidents by preventing ejection, a pattern of injuries directly attributable to impingement on the belt itself is becoming evident. ...

  10. The Western Carpathians fold and thrust belt and its relationships with the inner zone of the orogen: constraints from sequentially restored, balanced cross-sections integrated with low-temperature thermochronometry

    NASA Astrophysics Data System (ADS)

    Mazzoli, Stefano; Castelluccio, Ada; Andreucci, Benedetta; Jankowski, Leszek; Ketcham, Richard A.; Szaniawski, Rafal; Zattin, Massimiliano

    2017-04-01

    The Western Carpathians are the northernmost, W-E-trending branch of a more than 1500 km long, curved orogen. Traditionally, the Western Carpathians have been divided into two distinct parts, namely the Inner Carpathians (including basement nappes) and the Outer Carpathians fold and thrust belt. These two major domains are separated by the so-called 'Pieniny Klippen Belt', a narrow zone of intensely deformed and sheared Mesozoic to Palaeogene rocks. In this contribution, a new interpretation for the tectonic evolution of the Western Carpathians is provided based on: (i) the analysis of the stratigraphy of the Mesozoic-Tertiary successions across the different orogenic domains; (ii) the construction of a series of balanced and restored cross-sections, validated by 2D forward modeling; and (iii) the integration of a large thermochronometric dataset (apatite fission tracks and apatite and zircon (U-Th-(Sm))/He ages). The latter work included thermo-kinematic modeling using FetKin, a finite element solver that takes as input a series of balanced cross-sections. The software solves the heat flow equations in 2D together with the predicted thermochronometric ages, which can be compared with the measured data. Moreover, the spatial distribution of burial depths, cooling ages and the rate of exhumation were correlated with heat flow, topographic relief, crustal and lithospheric thickness. This process allowed us to obtain the cooling history along each section and test the response of low-temperature thermochronometers to the changes in the thrust belt geometry produced by fault activity and topography evolution. Our sequentially restored, balanced cross-sections, showing a mix of thin-skinned thrusting and thick-skinned tectonic inversion involving the reactivation of pre-existing basement normal faults, effectively unravel the tectonic evolution of the thrust belt-foreland basin system. Our analysis provides a robust correlation of the stratigraphy from the Outer to the

  11. Chaos on the conveyor belt.

    PubMed

    Sándor, Bulcsú; Járai-Szabó, Ferenc; Tél, Tamás; Néda, Zoltán

    2013-04-01

    The dynamics of a spring-block train placed on a moving conveyor belt is investigated both by simple experiments and computer simulations. The first block is connected by a spring to an external static point and, due to the dragging effect of the belt, the blocks undergo complex stick-slip dynamics. A qualitative agreement with the experimental results can be achieved only by taking into account the spatial inhomogeneity of the friction force on the belt's surface, modeled as noise. As a function of the velocity of the conveyor belt and the noise strength, the system exhibits complex, self-organized critical, sometimes chaotic, dynamics and phase transition-like behavior. Noise-induced chaos and intermittency is also observed. Simulations suggest that the maximum complexity of the dynamical states is achieved for a relatively small number of blocks (around five).

  12. The constitutionality of mandatory seat belt laws.

    DOT National Transportation Integrated Search

    1986-01-01

    Low seat belt usage rates have persisted for years despite efforts to educate people about belts' benefits. There is ample documentation of the contribution of seat belts to saving lives and reducing injury. The emotional and pecuniary toll of the fa...

  13. Depositional and tectonic setting of the Archean Moodies Group, Barberton Greenstone Belt, South Africa

    NASA Technical Reports Server (NTRS)

    Heubeck, C.; Lowe, D. R.

    1994-01-01

    The 3.22-3.10 Ga old Moodies Group, uppermost unit of the Swaziland Supergroup in the Barberton Greenstone Belt (BGB), is the oldest exposed, well-preserved quartz-rich sedimentary sequence on earth. It is preserved in structurally separate blocks in a heavily deformed fold-and-thrust belt. North of the Inyoka Fault, Moodies strata reach up to 3700 m in thickness. Detailed mapping, correlation of measured sections, and systematic analysis of paleocurrents show that the lower Moodies Group north of the Inyoka Fault forms a deepening- and fining-upward sequence from a basal alluvial conglomerate through braided fluvial, tidal, and deltaic sandstones to offshore sandy shelf deposits. The basal conglomerate and overlying fluvial facies were derived from the north and include abundant detritus eroded from underlying Fig Tree Group dacitic volcanic rocks. Shoreline-parallel transport and extensive reworking dominate overlying deltaic, tidal, and marine facies. The lithologies and arrangement of Moodies Group facies, sandstone petrology, the unconformable relationship between Moodies strata and older deformed rocks, presence of at least one syndepositional normal fault, and presence of basaltic flow rocks and airfall fall tuffs interbedded with the terrestrial strata collectively suggest that the lower Moodies Group was deposited in one or more intramontane basins in an extensional setting. Thinner Moodies sections south of the Inyoka Fault, generally less than 1000 m thick, may be correlative with the basal Moodies Group north of the Inyoka Fault and were probably deposited in separate basins. A northerly derived, southward-thinning fan-delta conglomerate in the upper part of the Moodies Group in the central BGB overlies lower strata with an angular unconformity. This and associated upper Moodies conglomerates mark the beginning of basin shortening by south- to southeast-directed thrust faulting along the northern margin of the BGB and suggest that the upper Moodies

  14. Uniquely Acquired Vintage Seismic Reflection Data Reveal the Stratigraphic and Tectonic History of the Montana Disturbed Belt, USA

    NASA Astrophysics Data System (ADS)

    Speece, M. A.; Link, C. A.; Stickney, M.

    2011-12-01

    In 1983 and 1984 Techco of Denver, Colorado, acquired approximately 302 linear kilometers of two-dimensional (2D) seismic reflection data in Flathead and Lake Counties, Montana, USA, as part of an initiative to identify potential drilling targets beneath the Swan and Whitefish Mountain Ranges and adjacent basins of northwestern Montana. These seismic lines were collected in the Montana Disturbed Belt (MDB) or Montana thrust belt along the western edge of Glacier National Park in mountainous terrain with complicated subsurface structures including thrust faults and folds. These structures formed during the Laramide Orogeny as sedimentary rocks of the Precambrian Belt Supergroup were thrust eastward. Later, during the Cenozoic, high-angle normal faults produced prominent west-facing mountain scarps of the Mission, Swan and Whitefish mountains. The 1983 data set consisted of two profiles of 24-fold (96-channels) Vibroseis data and four profiles of 24-fold (96-channels) helicopter-assisted dynamite data. The dynamite data were collected using the Poulter Method in which explosives were placed on poles and air shots were recorded. The 1983 dynamite profiles extend from southwest to northeast across the Whitefish Mountain Range to the edge of Glacier National Park and the Vibroseis data were collected along nearby roadways. The 1984 data set consists of four profiles of 30-fold (120-channels) helicopter-assisted dynamite data that were also collected using the Poulter Method. The 1984 profiles cross the Swan Mountain Range between Flathead Lake and Glacier National Park. All of these data sets were recently donated to Montana Tech and subsequently recovered from nine-track tape. Conventionally processed seismic stacked sections from the 1980s of these data show evidence of a basement decollement that separates relatively undeformed basement from overlying structures of the MDB. Unfortunately, these data sets have not been processed using modern seismic processing

  15. Safety belt promotion: theory and practice.

    PubMed

    Nelson, G D; Moffit, P B

    1988-02-01

    The purpose of this paper is to provide practitioners a rationale and description of selected theoretically based approaches to safety belt promotion. Theory failure is a threat to the integrity and effectiveness of safety belt promotion. The absence of theory driven programs designed to promote safety belt use is a concern of this paper. Six theoretical models from the social and behavioral sciences are reviewed with suggestions for application to promoting safety belt use and include Theory of Reasoned Action, the Health Belief Model, Fear Arousal, Operant Learning, Social Learning Theory, and Diffusion of Innovations. Guidelines for the selection and utilization of theory are discussed.

  16. 2003 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2003-08-01

    The objective of this study was to establish 2003 safety belt and child safety seat usage rates in Kentucky. The 2003 survey continues to document the results after enactment of a statewide mandatory safety belt law in 1994 and safety belt enforcemen...

  17. 2004 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2004-08-01

    The objective of this study was to establish 2004 safety belt and child safety seat usage rates in Kentucky. The 2004 survey continues to document the results after enactment of a statewide mandatory safety belt law in 1994 and safety belt enforcemen...

  18. Teens and seat belt use: What makes them click?

    PubMed

    Shults, Ruth A; Haegerich, Tamara M; Bhat, Geeta; Zhang, Xinjian

    2016-06-01

    Motor vehicle crashes kill more adolescents in the United States than any other cause, and often the teen is not wearing a seat belt. Using data from the 2011 Youth Risk Behavior Surveys from 38 states, we examined teens' self-reported seat belt use while riding as a passenger and identified individual characteristics and environmental factors associated with always wearing a seat belt. Only 51% of high school students living in 38 states reported always wearing a seat belt when riding as a passenger; prevalence varied from 32% in South Dakota to 65% in Delaware. Seat belt use was 11 percentage points lower in states with secondary enforcement seat belt laws compared to states with primary enforcement laws. Racial/ethnic minorities, teens living in states with secondary enforcement seat belt laws, and those engaged in substance use were least likely to always wear their seat belts. The likelihood of always being belted declined steadily as the number of substance use behaviors increased. Seat belt use among teens in the United States remains unacceptably low. Results suggest that environmental influences can compound individual risk factors, contributing to even lower seat belt use among some subgroups. This study provides the most comprehensive state-level estimates to date of seat belt use among U.S. teens. This information can be useful when considering policy options to increase seat belt use and for targeting injury prevention interventions to high-risk teens. States can best increase teen seat belt use by making evidence-informed decisions about state policy options and prevention strategies. Published by Elsevier Ltd.

  19. The Complexity of Folding Self-Folding Origami

    NASA Astrophysics Data System (ADS)

    Stern, Menachem; Pinson, Matthew B.; Murugan, Arvind

    2017-10-01

    Why is it difficult to refold a previously folded sheet of paper? We show that even crease patterns with only one designed folding motion inevitably contain an exponential number of "distractor" folding branches accessible from a bifurcation at the flat state. Consequently, refolding a sheet requires finding the ground state in a glassy energy landscape with an exponential number of other attractors of higher energy, much like in models of protein folding (Levinthal's paradox) and other NP-hard satisfiability (SAT) problems. As in these problems, we find that refolding a sheet requires actuation at multiple carefully chosen creases. We show that seeding successful folding in this way can be understood in terms of subpatterns that fold when cut out ("folding islands"). Besides providing guidelines for the placement of active hinges in origami applications, our results point to fundamental limits on the programmability of energy landscapes in sheets.

  20. Effects of safety belt laws on safety belt use by American High School Seniors, 1986-2000.

    PubMed

    O'Malley, Patrick M; Wagenaar, Alexander C

    2004-01-01

    This manuscript evaluates the effects of enactment of state laws that required safety belt use in various U.S. states between 1986 and 2000. Safety belt use was assessed using nationally representative cross-sectional samples of high school seniors; evaluation of the effects of laws used data from over 2,000 high school seniors before and about 3,300 after the laws took effect in 20 states. Belt use was found to increase significantly between 1986 and 2000, and the laws contributed significantly to that increase. Increases were similar for students differing by gender, race/ethnicity, parent education, grades, truancy, evenings out per week, miles driven per week, and an index of illicit drug use. The data show that although the laws have increased belt use, use is not universal and continued efforts are needed. This study shows that many teenagers fail to use belts when there is a secondary use law; an implication is that primary laws would be more efficacious in increasing use among this vulnerable population.

  1. Mechanical versus kinematical shortening reconstructions of the Zagros High Folded Zone (Kurdistan region of Iraq)

    NASA Astrophysics Data System (ADS)

    Frehner, Marcel; Reif, Daniel; Grasemann, Bernhard

    2012-06-01

    This paper compares kinematical and mechanical techniques for the palinspastic reconstruction of folded cross sections in collision orogens. The studied area and the reconstructed NE-SW trending, 55.5 km long cross section is located in the High Folded Zone of the Zagros fold-and-thrust belt in the Kurdistan region of Iraq. The present-day geometry of the cross section has been constructed from field as well as remote sensing data. In a first step, the structures and the stratigraphy are simplified and summarized in eight units trying to identify the main geometric and mechanical parameters. In a second step, the shortening is kinematically estimated using the dip domain method to 11%-15%. Then the same cross section is used in a numerical finite element model to perform dynamical unfolding simulations taking various rheological parameters into account. The main factor allowing for an efficient dynamic unfolding is the presence of interfacial slip conditions between the mechanically strong units. Other factors, such as Newtonian versus power law viscous rheology or the presence of a basement, affect the numerical simulations much less strongly. If interfacial slip is accounted for, fold amplitudes are reduced efficiently during the dynamical unfolding simulations, while welded layer interfaces lead to unrealistic shortening estimates. It is suggested that interfacial slip and decoupling of the deformation along detachment horizons is an important mechanical parameter that controlled the folding processes in the Zagros High Folded Zone.

  2. Mechanical versus kinematical shortening reconstructions of the Zagros High Folded Zone (Kurdistan Region of Iraq)

    NASA Astrophysics Data System (ADS)

    Frehner, M.; Reif, D.; Grasemann, B.

    2012-04-01

    Our study compares kinematical and mechanical techniques for the palinspastic reconstruction of folded cross-sections in collision orogens. The studied area and the reconstructed NE-SW-trending, 55.5 km long cross-section is located in the High Folded Zone of the Zagros fold-and-thrust belt in the Kurdistan Region of Iraq. The present-day geometry of the cross-section has been constructed from field, as well as remote sensing data. In a first step, the structures and the stratigraphy are simplified and summarized in eight units trying to identify the main geometric and mechanical parameters. In a second step, the shortening is kinematically estimated using the dip-domain method to 11%-15%. Then the same cross-section is used in a numerical finite-element model to perform dynamical unfolding simulations taking various rheological parameters into account. The main factor allowing for an efficient dynamic unfolding is the presence of interfacial slip conditions between the mechanically strong units. Other factors, such as Newtonian vs. power-law viscous rheology or the presence of a basement affect the numerical simulations much less strongly. If interfacial slip is accounted for, fold amplitudes are reduced efficiently during the dynamical unfolding simulations, while welded layer interfaces lead to unrealistic shortening estimates. It is suggested that interfacial slip and decoupling of the deformation along detachment horizons is an important mechanical parameter that controlled the folding processes in the Zagros High Folded Zone.

  3. Transpression as the main deformational event in an Archaean greenstone belt, northeastern Minnesota

    NASA Technical Reports Server (NTRS)

    Hudleston, P. J.; Schultz-Ela, D.; Bauer, R. L.; Southwick, D. L.

    1986-01-01

    Deformed and metamorphosed sedimentary and volcanic rocks of the Vermilion district constitute an Archean greenstone belt trending east-west between higher grade rocks of the Vermilion Granitic Complex to the north and the Giants Range batholith to the south. Metamorphic grade is low throughout, being lowest in the center of the belt (chlorite zone of the greenschist facies). All the measured strain, a cleavage or schistosity, and a mineral lineation in this belt are attributed to the main phase of deformation D sub 2 that followed an earlier nappe-forming event D sub 1, which left little evidence of penetrative fabric. Previous work assumed that the D sub 2 deformation resulted from north-south compression across the district. It is now believed that a significant component of this deformation resulted from dextral shear across the whole region. Thus the Vermilion fault, a late-state largely strike-slip structure that bounds the Vermilion district to the north, may simply be the latest, most brittle expression of a shear regime that was much more widespread in space and time. Features that are indicative of shear include ductile shear zones with sigmoidal foliation patterns, highly schistose zones with the development of shear bands, feldspar clasts or pyrite cubes with asymmetric pressure shadows, and the fact that the asymmetry of the F sub 2 folds is predominantly Z for at least 15 km south of the Vermilion fault.

  4. Contemporary seismicity in and around the Yakima Fold and Thrust Belt in eastern Washington

    USGS Publications Warehouse

    Gomberg, J.; Sherrod, B.; Trautman, M.; Burns, E.; Snyder, Diane

    2012-01-01

    We examined characteristics of routinely cataloged seismicity from 1970 to the present in and around the Yakima fold‐and‐thrust belt (YFTB) in eastern Washington to determine if the characteristics of contemporary seismicity provide clues about regional‐scale active tectonics or about more localized, near‐surface processes. We employed new structural and hydrologic models of the Columbia River basalts (CRB) and found that one‐third to one‐half of the cataloged earthquakes occur within the CRB and that these CRB earthquakes exhibit significantly more clustered, and swarmlike, behavior than those outside. These results and inferences from published studies led us to hypothesize that clustered seismicity is likely associated with hydrologic changes in the CRB, which hosts the regional aquifer system. While some general features of the regional groundwater system support this hypothesis, seismicity patterns and mapped long‐term changes in groundwater levels and present‐day irrigation neither support nor refute it. Regional tectonic processes and crustal‐scale structures likely influence the distribution of earthquakes both outside and within the CRB as well. We based this inference on qualitatively assessed alignments between the dominant northwest trends in the geologic structure and the seismicity generally and between specific faults and characteristics of the 2009 Wooded Island swarm and aseismic slip, which is the only cluster studied in detail and the most vigorous since regional monitoring began.

  5. Effectiveness of media and enforcement campaigns in increasing seat belt usage rates in a state with a secondary seat belt law.

    PubMed

    Vasudevan, Vinod; Nambisan, Shashi S; Singh, Ashok K; Pearl, Traci

    2009-08-01

    In 2005, in terms of seat belt usage rates, Nevada ranked third nationally and first among states with secondary seat belt use enforcement laws in the United States. An effective combination of a media-based education and enforcement campaign helped in this regard. The objective of this article is to document the effectiveness of enforcement and media-based education and outreach campaigns on the seat belt usage rates in Nevada, a state with a secondary seat belt usage law. Observational data on seat belt usage and passenger fatality data are used to evaluate the effectiveness of enforcement campaigns and media-based education and outreach campaigns. Data based on observations of about 40,000 vehicles in each of the years 2003 to 2005 were analyzed. Statistical analyses show that a significant increase in seat belt usage rates among both drivers and passengers for both genders resulted from the accompanying the media and enforcement campaigns. The results from this study indicate that effective and well-planned media/enforcement campaigns can have a significant impact on seat belt usage rates even in a state where the enforcement of seat belt laws can only be as a secondary violation. They validate and expand on findings from other efforts documented in the literature. These results demonstrate that, if coordinated properly, media and enforcement campaigns work very effectively in increasing seat belt usage rates even in states with secondary seat belt laws.

  6. Mandatory seat belt use laws.

    DOT National Transportation Integrated Search

    1985-01-01

    The purposes of this study were to review mandatory seat belt use laws as they have been used around the world, to forecast the impact of such a law in Virginia, and, if appropriate, to propose a mandatory seat belt law for inclusion in the Code of V...

  7. Antibiotic sensitivity pattern of uropathogens from pregnant women with urinary tract infection in Abakaliki, Nigeria.

    PubMed

    Onoh, Rc; Umeora, Ouj; Egwuatu, Ve; Ezeonu, Po; Onoh, Tjp

    2013-01-01

    Urinary tract infection (UTI) is a common bacterial infection during pregnancy and a significant cause of perinatal and maternal morbidity and mortality. The causative bacteria have remained virtually the same although with variations in individual prevalence. There has been an increasing resistance by these bacteria to the commonly available antibiotics. To determine the prevalence of UTI, the common causative bacteria, and their antibiotic sensitivity pattern among pregnant women with UTI. This is a descriptive study that was carried out at the Obstetrics Department of two tertiary institutions in Abakaliki, Ebonyi State, Nigeria (Federal Medical Center and Ebonyi State University Teaching Hospital) over a period of 12 months. Midstream urine specimens from selected pregnant women with clinical features of UTI were collected for microscopy, culture, and sensitivity. The results were analyzed with the 2008 Epi Info™ software. A total of 542 pregnant women presented with symptoms of UTI and were recruited for the study over the study period. Of the 542 pregnant women, 252 (46.5%) had significant bacteriuria with positive urine culture and varying antibiotic sensitivity pattern. The prevalence of symptomatic UTI was 3%. Escherichia coli was the most common bacteria isolated with a percentage of 50.8%. Other isolated micro organisms included Stapylococcus aereus (52 cultures, 20.6%), Proteus mirabilis (24 cultures, 9.5%), S. saprophyticus (18 cultures, 7.1%), Streptococcus spp. (14 cultures, 5.6%), Citrobacter spp. (5 cultures, 2.0%), Klebsiella spp. (4 cultures, 1.6%), Enterobacter spp. (4 cultures, 1.6%), and Pseudomonas spp. (3 cultures, 1.2%). Levofloxacin had the highest overall antibiotic sensitivity of 92.5%. Others with overall antibiotic sensitivity pattern greater than 50% included cefpodoxime (87.3%), ofloxacin (77.4%), ciprofloxacin (66.7%), ceftriaxone (66.7%), and gentamicin (50.8%). E. coli was the most common etiological agent of UTI in pregnancy

  8. Pattern of seat belt wearing in Nanjing, China

    PubMed Central

    Routley, V; Ozanne‐Smith, J; Li, D; Hu, X; Wang, P; Qin, Y

    2007-01-01

    Objective To describe the patterns of seat belt wearing in Nanjing, China for drivers, front seat passengers, and rear occupants of motor vehicles. Design Roadside observational study. Setting Four sites in central and northern Nanjing during daylight hours over 1 week in April 2005. Subjects Drivers and passengers of 17 147 cars, taxis, goods vans, and pickups, which traveled in the inside traffic lane. Main outcome measures Percentage seat belt wearing for each of seating position, age/sex, time of day, vehicle type, day of week. Results The rate of seat belt wearing was significantly higher in drivers (67.3%, 95% CI 66.6 to 68.0) than front seat passengers (18.9%, 95% CI, 18.0 to 19.8). It was negligible for second front seat passengers (2.6%, 95% CI 0.3 to 4.9) and rear seat passengers (0.5%, 95% CI 0.3 to 0.7). Belt tampering, such that protection would be reduced in the event of a crash, was observed for 18.5% of taxi drivers. Drivers were most likely to wear seat belts in cars and vans and at a city roundabout; front seat passengers were most likely to wear seat belts in non‐taxi vehicles, during the evening rush hour, if the driver was wearing a belt, and on the local north road. Drivers were least likely to wear a belt in the early morning, in pickups and taxis, on Tuesday (or the following week), and on the local north road; front seat passengers were least likely to wear a belt in taxis and if the driver was not wearing a belt. Conclusions Rates of seat belt wearing by passengers were low despite national legislation and provincial regulations coming into effect several months before the survey. Combined education and enforcement are necessary accompaniments to legislation. PMID:18056315

  9. Intrusive rocks and plutonic belts of southeastern Alaska, U.S.A.

    USGS Publications Warehouse

    Brew, David A.; Morrell, Robert P.; Roddick, J.A.

    1983-01-01

    About 30 percent of the 175,000-km2 area of southeastern Alaska is underlain by intrusive igneous rocks. Compilation of available information on the distribution, composition, and ages of these rocks indicates the presence of six major and six minor plutonic belts. From west to east, the major belts are: the Fairweather-Baranof belt of early to mid-Tertiary granodiorite; the Muir-Chichagof belt of mid-Cretaceous tonalite and granodiorite; the Admiralty-Revillagigedo belt of porphyritic granodiorite, quartz diorite, and diorite of probable Cretaceous age; the Klukwan-Duke belt of concentrically zoned or Alaskan-type ultramafic-mafic plutons of mid-Cretaceous age within the Admiralty-Revillagigedo belt; the Coast Plutonic Complex sill belt of tonalite of unknown, but perhaps mid-Cretaceous, age; and the Coast Plutonic Complex belt I of early to mid-Tertiary granodiorite and quartz monzonite. The minor belts are distributed as follows: the Glacier Bay belt of Cretaceous and(or) Tertiary granodiorite, tonalite, and quartz diorite lies within the Fair-weather-Baranof belt; layered gabbro complexes of inferred mid-Tertiary age lie within and are probably related to the Fairweather-Baranof belt; the Chilkat-Chichagof belt of Jurassic granodiorite and tonalite lies within the Muir-Chichagof belt; the Sitkoh Bay alkaline, the Kendrick Bay pyroxenite to quartz monzonite, and the Annette and Cape Fox trondhjemite plutons, all interpreted to be of Ordovician(?) age, together form the crude southern southeastern Alaska belt within the Muir-Chichagof belt; the Kuiu-Etolin mid-Tertiary belt of volcanic and plutonic rocks extends from the Muir-Chichagof belt eastward into the Admiralty-Revillagigedo belt; and the Behm Canal belt of mid- to late Tertiary granite lies within and next to Coast Plutonic Complex belt II. In addition, scattered mafic-ultramafic bodies occur within the Fairweather-Baranof, Muir-Chichagof, and Coast Plutonic Complex belts I and II. Palinspastic

  10. Fault fluid evolution at the outermost edges of the southern Apennines fold-and-thrust belt, Italy

    NASA Astrophysics Data System (ADS)

    Agosta, Fabrizio; Belviso, Claudia; Cavalcante, Francesco; Vita Petrullo, Angela

    2017-04-01

    This work focuses on the structural architecture and mineralization of a high-angle, extensional fault zone that crosscuts the Middle Pleistocene tuffs and pyroclastites of the Vulture Volcano, southern Italy. This fault zone is topped by a few m-thick travertine deposit formed by precipitation, in a typical lacustrine depositional environment, from a fault fluid that included a mixed, biogenic- and mantle-derived CO2. The detailed analysis of its different mineralization can shed new lights into the shallow crustal fluid flow that took place during deformation of the outer edge of the southern Apennines fold-and-thrust belt. In fact, the study fault zone is interpreted as a shallow-seated, tear fault associated with a shallow thrust fault displacing the most inner portion of the Bradano foredeep basin infill, and was thus active during the latest stages of contractional deformation. Far from the fault zone, the fracture network is made up of three high-angle joint sets striking N-S, E-W and NW-SE, respectively. The former two sets can be interpreted as the older structural elements that pre-dated the latter one, which is likely due to the current stress state that affects the whole Italian peninsula. In the vicinity of the fault zone, a fourth joint high-angle set striking NE-SW is also present, which becomes the most dominant fracture set within the study footwall fault damage zone. Detailed X-ray diffraction analysis of the powder obtained from hand specimens representative of the multiple mineralization present within the fault zone, and in the surrounding volcanites, are consistent with circulation of a fault fluid that modified its composition with time during the latest stages of volcanic activity and contractional deformation. Specifically, veins infilled with and slickenside coated by jarosite, Opal A and/or goethite are found in the footwall fault damage zone. Based upon the relative timing of formation of the aforementioned joint sets, deciphered after

  11. The development of an electronic system to continually monitor, indicate and control, 'belt slippage' in industrial friction 'V' belt drive transmission systems

    NASA Astrophysics Data System (ADS)

    Brown, R. E.

    2012-05-01

    Belts have been used for centuries as a mechanism to transfer power from some form of drive system to a variety of load systems. Within industry today, many designs of belts but particularly friction, trapezoidal shaped 'V' belts are used and generally transfer power generated by electrical motors to numerous forms of driven load systems. It is suggested that belt systems, through their simplicity are sadly neglected by maintenance functions and generally are left unattended until high degrees of 'belt slippage' through loss of friction or 'belt breakage' provokes maintenance attention. These circumstances are most often identified through the reduced or loss of manufacturing production or the occurrence of catastrophic circumstances such as fire caused through excessive friction/ high belt slippage conditions. Obviously, these situations incur financial losses to companies and in some cases the near loss of the company's main manufacturing plant. Consequently, a satisfactory, viable solution is currently sought by industry to improve on current labour intensive maintenance practices. This paper will present an account of the development of an industrially robust, accurate and repeatable electronic system which continually monitors and indicates the degree of 'slippage' in a 'V' belt drive transmission system and in the circumstance of belt breakage or high belt slippage will enable and control the switching off the drive motor.

  12. Grinding Glass Disks On A Belt Sander

    NASA Technical Reports Server (NTRS)

    Lyons, James J., III

    1995-01-01

    Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.

  13. Teaching Science: Seat Belt Science.

    ERIC Educational Resources Information Center

    Leyden, Michael B.

    1994-01-01

    Describes activities that will help students understand how car seat belts work, the limited reaction time available to passengers in an automobile accident, and the force of impact in a car collision. These activities will provide students with hands-on experiences that demonstrate the importance of always wearing seat belts while in an…

  14. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the...

  15. Long-distance longitudinal transport of gravel across the Cordilleran thrust belt of Montana and Idaho

    NASA Astrophysics Data System (ADS)

    Janecke, Susanne U.; Vandenburg, Colby J.; Blankenau, James J.; M'gonigle, John W.

    2000-05-01

    Two newly identified middle Eocene paleovalleys (≥ 100 km long) preserved on top of the southwest Montana reentrant of the Cordilleran fold-and-thrust belt indicate long-lived longitudinal flow across the thrust belt and resolve a long-standing debate about the source of the voluminous quartzite debris in the Upper Cretaceous to lower Tertiary Divide, Harebell, and Pinyon conglomerates of Montana, Idaho, and Wyoming. Geologic mapping, stratigraphic, provenance, and geochronologic studies revealed that Eocene volcanic and sedimentary rocks in the paleovalleys are as thick as 2 km, onlap preexisting bedrock, and interfinger with well-rounded conglomerate derived from formations exposed only to the west. The middle Eocene paleovalleys are the youngest expression of a major paleoriver system that transported sediment toward the foreland during the Sevier orogeny. An Eocene subcrop map shows that the headwaters of the Eocene paleovalleys coincided with structural culminations in the thrust belt that supplied sediment to the Divide conglomerate of the Upper Cretaceous to lower Tertiary Beaverhead Group. Ultimately, the Lemhi Pass and Hawley Creek paleovalleys provided several thousand cubic kilometers of quartzite debris to the Pinyon and Harebell conglomerates of northwest Wyoming 200 350 km away, and formed the northwest half of a giant longitudinal drainage system. Sevier contraction, not the rising Idaho batholith, first uplifted vast culminations beneath the headwaters of this river system.

  16. Effect of a weightlifting belt on spinal shrinkage.

    PubMed

    Bourne, N D; Reilly, T

    1991-12-01

    Spinal loading during weightlifting results in a loss of stature which has been attributed to a decrease in height of the intervertebral discs--so-called 'spinal shrinkage'. Belts are often used during the lifting of heavy weights, purportedly to support, stabilize and thereby attenuate the load on the spine. The purpose of this study was to examine the effects of a standard weightlifting belt in attenuating spinal shrinkage. Eight male subjects with a mean age of 24.8 years performed two sequences of circuit weight-training, one without a belt and on a separate occasion with a belt. The circuit training regimen consisted of six common weight-training exercises. These were performed in three sets of ten with a change of exercise after each set of ten repetitions. A stadiometer sensitive to within 0.01 mm was used to record alterations in stature. Measurements of stature were taken before and after completion of the circuit. The absolute visual analogue scale (AVAS) was used to measure the discomfort and pain intensity resulting from each of the two conditions. The circuit weight-training caused stature losses of 3.59mm without the belt and 2.87 mm with the belt (P greater than 0.05). The subjects complained of significantly less discomfort when the belt was worn (P less than 0.05). The degree of shrinkage was significantly correlated (r = 0.752, P less than 0.05) with perceived discomfort but only when the belt was not worn. These results suggest the potential benefits of wearing a weightlifting belt and support the hypothesis that the belt can help in stabilizing the trunk.

  17. Effect of a weightlifting belt on spinal shrinkage.

    PubMed Central

    Bourne, N D; Reilly, T

    1991-01-01

    Spinal loading during weightlifting results in a loss of stature which has been attributed to a decrease in height of the intervertebral discs--so-called 'spinal shrinkage'. Belts are often used during the lifting of heavy weights, purportedly to support, stabilize and thereby attenuate the load on the spine. The purpose of this study was to examine the effects of a standard weightlifting belt in attenuating spinal shrinkage. Eight male subjects with a mean age of 24.8 years performed two sequences of circuit weight-training, one without a belt and on a separate occasion with a belt. The circuit training regimen consisted of six common weight-training exercises. These were performed in three sets of ten with a change of exercise after each set of ten repetitions. A stadiometer sensitive to within 0.01 mm was used to record alterations in stature. Measurements of stature were taken before and after completion of the circuit. The absolute visual analogue scale (AVAS) was used to measure the discomfort and pain intensity resulting from each of the two conditions. The circuit weight-training caused stature losses of 3.59mm without the belt and 2.87 mm with the belt (P greater than 0.05). The subjects complained of significantly less discomfort when the belt was worn (P less than 0.05). The degree of shrinkage was significantly correlated (r = 0.752, P less than 0.05) with perceived discomfort but only when the belt was not worn. These results suggest the potential benefits of wearing a weightlifting belt and support the hypothesis that the belt can help in stabilizing the trunk. Images Figure 1 PMID:1810615

  18. Colors of Inner Disk Classical Kuiper Belt Objects

    NASA Astrophysics Data System (ADS)

    Romanishin, W.; Tegler, S. C.; Consolmagno, G. J.

    2010-07-01

    We present new optical broadband colors, obtained with the Keck 1 and Vatican Advanced Technology telescopes, for six objects in the inner classical Kuiper Belt. Objects in the inner classical Kuiper Belt are of interest as they may represent the surviving members of the primordial Kuiper Belt that formed interior to the current position of the 3:2 resonance with Neptune, the current position of the plutinos, or, alternatively, they may be objects formed at a different heliocentric distance that were then moved to their present locations. The six new colors, combined with four previously published, show that the ten inner belt objects with known colors form a neutral clump and a reddish clump in B-R color. Nonparametric statistical tests show no significant difference between the B-R color distribution of the inner disk objects compared to the color distributions of Centaurs, plutinos, or scattered disk objects. However, the B-R color distribution of the inner classical Kuiper Belt Objects does differ significantly from the distribution of colors in the cold (low inclination) main classical Kuiper Belt. The cold main classical objects are predominately red, while the inner classical belt objects are a mixture of neutral and red. The color difference may reveal the existence of a gradient in the composition and/or surface processing history in the primordial Kuiper Belt, or indicate that the inner disk objects are not dynamically analogous to the cold main classical belt objects.

  19. COLORS OF INNER DISK CLASSICAL KUIPER BELT OBJECTS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Romanishin, W.; Tegler, S. C.; Consolmagno, G. J., E-mail: wromanishin@ou.ed, E-mail: Stephen.Tegler@nau.ed, E-mail: gjc@specola.v

    2010-07-15

    We present new optical broadband colors, obtained with the Keck 1 and Vatican Advanced Technology telescopes, for six objects in the inner classical Kuiper Belt. Objects in the inner classical Kuiper Belt are of interest as they may represent the surviving members of the primordial Kuiper Belt that formed interior to the current position of the 3:2 resonance with Neptune, the current position of the plutinos, or, alternatively, they may be objects formed at a different heliocentric distance that were then moved to their present locations. The six new colors, combined with four previously published, show that the ten innermore » belt objects with known colors form a neutral clump and a reddish clump in B-R color. Nonparametric statistical tests show no significant difference between the B-R color distribution of the inner disk objects compared to the color distributions of Centaurs, plutinos, or scattered disk objects. However, the B-R color distribution of the inner classical Kuiper Belt Objects does differ significantly from the distribution of colors in the cold (low inclination) main classical Kuiper Belt. The cold main classical objects are predominately red, while the inner classical belt objects are a mixture of neutral and red. The color difference may reveal the existence of a gradient in the composition and/or surface processing history in the primordial Kuiper Belt, or indicate that the inner disk objects are not dynamically analogous to the cold main classical belt objects.« less

  20. Igneous and tectonic evolution of the Batchawana Greenstone Belt, Superior Province: a U-Pb zircon and titanite study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Corfu, F.; Grunsky, E.C.

    1987-01-01

    U-Pb isotopic dating of zircon and titanite from all the major litho-tectonic units of the Batchawana belt, an Archean greenstone belt of the Abitibi Subprovince of the Superior Province in Canada, shows that the belt evolved during a period of about 60 Ma between about 2730 and 2670 Ma ago. Subsequent deformation of the supracrustal sequences produced isoclinal folding and culminated in metamorphism ranging from lower greenschist to amphibolite facies and anatexis related to the intrusion of syn- to late-tectonic plutons, four phases of which have ages of 2678 +4/-2 Ma, 2677 +/- 2 Ma, 2677 +/- 3 Ma, andmore » 2676 +/- 2 Ma. Two post-tectonic granitoid plutons in the center of the belt were intruded 2674 +/- 3 Ma and 2673 +/- 5 Ma ago and were followed by the emplacement of a composite mafic to felsic intrusion; a monzonite and a hornblendite from this intrusion yield identical ages of 2668 +/- 2 Ma. Titanite ages are identical or younger than the ages of coexisting zircons and reflect regional metamorphism and post-tectonic plutonism, but in a few cases they are younger and may record increased fluid activity along faults and the intrusion of mafic dikes. U-Pb zircon systematics, together with age and lithological relationships, suggests that the greenstone belt formed in an oceanic environment from material derived initially mainly from the mantle. Subsequent melting at the base of the thickening volcanic succession produced intermediate to felsic volcanic rocks, tonalites, and later granodioritic to granitic plutons leading to the final consolidation of the granite-greenstone terrain. 47 references.« less

  1. OUTER RADIATION BELT AND AURORAS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gorchakov, E.V.

    1961-01-01

    Data obtained from Sputnik IH were used to determine the high-latitude boundary of the outer radiation belt and to interpret the nature of auroras. At the heights at which the auroras were observed, the outer boundary of the belt (69 deg north geomagnetic latitude) practically coincides with the auroral zone maximum (70 deg north geomagnetic latitude), while the maximum intensity of the outer belt near the earth lies at about 55 deg north geomagnetic latitude, i.e., at latitudes 15 deg below the auroral maximum. Consequently, auroras near the zone of maximum cannot be caused by the penetration into the atmospheremore » of electrons from the outer belt with energies on the order of 0.1 Mev (the mean energy of electrons in the outer belt). Other investigators have reported the detection of lowenergy streams at 55,000 to 75,000 km from the center of the earth in the equatorial plane. Moving toward the surface of the earth along the force lines of the magnetic field, electron streams of this type will reach the earth precisely in the region of the auroral zone maximum. It is considered possible that the electron streams are trapped at these distances from the earth and are at least partially responsible for auroras in the region of maximum. The existence of two maxima in the latitudinal distribution of auroral frequency, which attests to differert mechanisms of aurora formation, favors this hypothesis. In the region of the basic auroral maximum (70 deg north geomagnetic latitude) the auroras are the result of the invasion of belt particles, while in the region of the additional maximum (about 80 deg north geomagnetic latitude) they are caused by the direct penetration of corpuscular streams into the atmosphere. (OTS)« less

  2. ScienceCast 76: The Radiation Belt Storm Probes

    NASA Image and Video Library

    2012-08-30

    This morning NASA launched two heavily-shielded spacecraft directly into the Van Allen Belts. The Radiation Belt Storm Probes are on a two-year mission to study the Van Allen Belts and to unravel the mystery of their unpredictability.

  3. Effectiveness of safety belt warning and interlock systems

    DOT National Transportation Integrated Search

    1973-04-01

    Rental cars in Fayetteville, N.C., were equipped with four seat belt and warning systems: (Phase I) detachable shoulder and lap belt, no warning system; (Phase II) detachable shoulder and lap belt, warning system (January 1, 1972 standard); (Phase II...

  4. Electric filter with movable belt electrode

    DOEpatents

    Bergman, W.

    1983-09-20

    A method and apparatus for removing airborne contaminants entrained in a gas or airstream includes an electric filter characterized by a movable endless belt electrode, a grounded electrode, and a filter medium sandwiched there between. Inclusion of the movable, endless belt electrode provides the driving force for advancing the filter medium through the filter, and reduces frictional drag on the filter medium, thereby permitting a wide choice of filter medium materials. Additionally, the belt electrode includes a plurality of pleats in order to provide maximum surface area on which to collect airborne contaminants. 4 figs.

  5. Electric filter with movable belt electrode

    DOEpatents

    Bergman, Werner

    1983-01-01

    A method and apparatus for removing airborne contaminants entrained in a gas or airstream includes an electric filter characterized by a movable endless belt electrode, a grounded electrode, and a filter medium sandwiched therebetween. Inclusion of the movable, endless belt electrode provides the driving force for advancing the filter medium through the filter, and reduces frictional drag on the filter medium, thereby permitting a wide choice of filter medium materials. Additionally, the belt electrode includes a plurality of pleats in order to provide maximum surface area on which to collect airborne contaminants.

  6. The effect of a gearshift interlock on seat belt use by drivers who do not always use a belt and its acceptance among those who do.

    PubMed

    Kidd, David G; Singer, Jeremiah; Huey, Richard; Kerfoot, Laura

    2018-06-01

    Seat belts reduce the risk of fatal injury in a crash, yet in 2015, nearly 10,000 people killed in passenger vehicles were unrestrained. Enhanced seat belt reminders increase belt use, but a gearshift interlock that prevents the vehicle from being placed into gear unless the seat belt is used may prove more effective. Thirty-two people with a recent seat belt citation and who admitted to not always using a seat belt as a driver were recruited as part-time belt users and asked to evaluate two new vehicles. Sixteen drove two vehicles with an enhanced reminder for one week each, and 16 drove a vehicle with an enhanced reminder for one week and a vehicle with a gearshift interlock the following week. Sixteen full-time belt users who reported always using a seat belt drove a vehicle with a gearshift interlock for one week to evaluate acceptance. Relative to the enhanced reminder, the gearshift interlock significantly increased the likelihood that a part-time belt user used a belt during travel time in a trip by 21%, and increased the rate of belt use by 16%; this effect approached significance. Although every full-time belt user experienced the gearshift interlock, their acceptance of the technology reported in a post-study survey was fairly positive and not significantly different from part-time belt users. Six part-time belt users circumvented the gearshift interlock by sitting on a seat belt, waiting for the system to deactivate, or unbuckling during travel. The gearshift interlock increased the likelihood that part-time belt users buckled up and the rate of belt use during travel relative to the enhanced reminder but could be more effective if it prevented circumvention. An estimated 718-942 lives could be saved annually if the belt use of unbuckled drivers and front passengers increased 16-21%. Copyright © 2018 National Safety Council and Elsevier Ltd. All rights reserved.

  7. Deformational sequence of a portion of the Michipicoten greenstone belt, Chabanel Township, Ontario

    NASA Technical Reports Server (NTRS)

    Shrady, C. H.; Mcgill, G. E.

    1986-01-01

    Detailed mapping at a scale of one inch = 400 feet is being carried out within a fume kill, having excellent exposure, located in the southwestern portion of the Michipicoten Greenstone Belt near Wawa, Ontario. The rocks are metasediments and metavolcanics of lower greenschist facies. U-Pb geochronology indicates that they are at least 2698 + or - 11 Ma old. The lithologic packages strike northeast to northwest, but the dominant strike is approximately east-west. Sedimentary structures and graded bedding are well preserved, aiding in the structural interpretation of this multiply deformed area. At least six phases of deformation within a relatively small area of the Michipicoten Greenstone Belt have been tentatively identified. These include the following structural features in approximate order of occurrence: (0) soft-sediment structures; (1) regionally overturned rocks, flattened pebbles, bedding parallel cleavage, and early, approximately bedding parallel faults; (2) northwest to north striking cleavage; (3) northeast striking cleavage and associated folds, and at least some late movement on approximately bedding parallel faults; (4) north-northwest and northeast trending faults; and (5) diabase dikes and associated fracture cleavages. Minor displacement of the diabase dikes occurs on faults that appear to be reactivated older structures.

  8. Mechanical study of the Chartreuse Fold-and-Thrust Belt: relationships between fluids overpressure and decollement within the Toarcian source-rock

    NASA Astrophysics Data System (ADS)

    Berthelon, Josselin; Sassi, William; Burov, Evgueni

    2016-04-01

    Many source-rocks are shale and constitute potential detachment levels in Fold-and-Thrust Belts (FTB): the toarcian Schistes-Cartons in the French Chartreuse FTB for example. Their mechanical properties can change during their burial and thermal maturation, as for example when large amount of hydrocarbon fluids are generated. A structural reconstruction of the Chartreuse FTB geo-history places the Toarcian Formation as the major decollement horizon. In this work, a mechanical analysis integrating the fluids overpressuring development is proposed to discuss on the validity of the structural interpretation. At first, an analogue of the Chartreuse Toarcian Fm, the albanian Posidonia Schist, is documented as it can provide insights on its initial properties and composition of its kerogen content. Laboratory characterisation documents the vertical evolution of the mineralogical, geochemical and mechanical parameters of this potential decollement layer. These physical parameters (i.e. Total Organic Carbon (TOC), porosity/permeability relationship, friction coefficient) are used to address overpressure buildup in the frontal part of the Chartreuse FTB with TEMISFlow Arctem Basin modelling approach (Faille et al, 2014) and the structural emplacement of the Chartreuse thrust units using the FLAMAR thermo-mechanical model (Burov et al, 2014). The hydro-mechanical modeling results highlight the calendar, distribution and magnitude of the overpressure that developed within the source-rock in the footwall of a simple fault-bend fold structure localized in the frontal part of the Chartreuse FTB. Several key geological conditions are required to create an overpressure able to fracture the shale-rocks and induce a significant change in the rheological behaviour: high TOC, low permeability, favourable structural evolution. These models highlight the importance of modeling the impact of a diffuse natural hydraulic fracturing to explain fluids propagation toward the foreland within

  9. Biomechanical considerations for abdominal loading by seat belt pretensioners.

    PubMed

    Rouhana, Stephen W; El-Jawahri, Raed E; Laituri, Tony R

    2010-11-01

    While seat belts are the most effective safety technology in vehicles today, there are continual efforts in the industry to improve their ability to reduce the risk of injury. In this paper, seat belt pretensioners and current trends towards more powerful systems were reviewed and analyzed. These more powerful systems may be, among other things, systems that develop higher belt forces, systems that remove slack from belt webbing at higher retraction speeds, or both. The analysis started with validation of the Ford Human Body Finite Element Model for use in evaluation of abdominal belt loading by pretensioners. The model was then used to show that those studies, done with lap-only belts, can be used to establish injury metrics for tests done with lap-shoulder belts. Then, previously-performed PMHS studies were used to develop AIS 2+ and AIS 3+ injury risk curves for abdominal interaction with seat belts via logistic regression and reliability analysis with interval censoring. Finally, some considerations were developed for a possible laboratory test to evaluate higher-powered pretensioners.

  10. A population of comets in the main asteroid belt.

    PubMed

    Hsieh, Henry H; Jewitt, David

    2006-04-28

    Comets are icy bodies that sublimate and become active when close to the Sun. They are believed to originate in two cold reservoirs beyond the orbit of Neptune: the Kuiper Belt (equilibrium temperatures of approximately 40 kelvin) and the Oort Cloud (approximately 10 kelvin). We present optical data showing the existence of a population of comets originating in a third reservoir: the main asteroid belt. The main-belt comets are unlike the Kuiper Belt and Oort Cloud comets in that they likely formed where they currently reside and may be collisionally activated. The existence of the main-belt comets lends new support to the idea that main-belt objects could be a major source of terrestrial water.

  11. Tensioning of a belt around a drum using membrane element

    NASA Technical Reports Server (NTRS)

    Chen, C. H. S.

    1980-01-01

    An application of the membrane element to the problem of the tensioning of a conveyer belt which wraps around a drum is presented. Two cases were investigated: (1) belt tension increase due to drum edge wear; and (2) material trapped between the drum and the belt. In both cases it was found that the increase in belt tension was due to the additional stretching of the belt resulting from the drum radius change rather than from the transverse deflection of the belt.

  12. Depletion of the Outer Asteroid Belt

    PubMed

    Liou; Malhotra

    1997-01-17

    During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time. The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides an explanation for the observed depletion of asteroids in that region.

  13. Depletion of the Outer Asteroid Belt

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Malhotra, Renu

    1997-01-01

    During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time. The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides an explanation for the observed depletion of asteroids in that region.

  14. Geography of the asteroid belt

    NASA Technical Reports Server (NTRS)

    Zellner, B. H.

    1978-01-01

    The CSM classification serves as the starting point on the geography of the asteroid belt. Raw data on asteroid types are corrected for observational biases (against dark objects, for instance) to derive the distribution of types throughout the belt. Recent work on family members indicates that dynamical families have a true physical relationship, presumably indicating common origin in the breakup of a parent asteroid.

  15. Phyllosilicate absorption features in main-belt and outer-belt asteroid reflectance spectra.

    PubMed

    Vilas, F; Gaffey, M J

    1989-11-10

    Absorption features having depths up to 5% are identified in high-quality, high-resolution reflectance spectra of 16 dark asteroids in the main belt and in the Cybele and Hilda groups. Analogs among the CM2 carbonaceous chondrite meteorites exist for some of these asteroids, suggesting that these absorptions are due to iron oxides in phyllosilicates formed on the asteroidal surfaces by aqueous alteration processes. Spectra of ten additional asteroids, located beyond the outer edge of the main belt, show no discernible absorption features, suggesting that aqueous alteration did not always operate at these heliocentric distances.

  16. Phyllosilicate absorption features in main-belt and outer-belt asteroid reflectance spectra

    NASA Technical Reports Server (NTRS)

    Vilas, Faith; Gaffey, Michael J.

    1989-01-01

    Absorption features having depths up to 5 percent are identified in high-quality, high-resolution reflectance spectra of 16 dark asteroids in the main belt and in the Cybele and Hilda groups. Analogs among the CM2 carbonaceous chondrite meteorites exist for some of these asteroids, suggesting that these absorptions are due to iron oxides in phyllosilicates formed on the asteroidal surfaces by aqueous alteration processes. Spectra of ten additional asteroids, located beyond the outer edge of the main belt, show no discernible absorption features, suggesting that aqueous alteration did not always operate at these heliocentric distances.

  17. 30 CFR 57.15020 - Life jackets and belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Life jackets and belts. 57.15020 Section 57.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Protection Surface Only § 57.15020 Life jackets and belts. Life jackets or belts shall be worn where there is...

  18. 30 CFR 56.15020 - Life jackets and belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Life jackets and belts. 56.15020 Section 56.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... § 56.15020 Life jackets and belts. Life jackets or belts shall be worn where there is danger from...

  19. 30 CFR 57.15020 - Life jackets and belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Life jackets and belts. 57.15020 Section 57.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Protection Surface Only § 57.15020 Life jackets and belts. Life jackets or belts shall be worn where there is...

  20. 30 CFR 56.15020 - Life jackets and belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Life jackets and belts. 56.15020 Section 56.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... § 56.15020 Life jackets and belts. Life jackets or belts shall be worn where there is danger from...

  1. 30 CFR 57.15020 - Life jackets and belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Life jackets and belts. 57.15020 Section 57.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Protection Surface Only § 57.15020 Life jackets and belts. Life jackets or belts shall be worn where there is...

  2. 30 CFR 56.15020 - Life jackets and belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Life jackets and belts. 56.15020 Section 56.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... § 56.15020 Life jackets and belts. Life jackets or belts shall be worn where there is danger from...

  3. 30 CFR 57.15020 - Life jackets and belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Life jackets and belts. 57.15020 Section 57.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Protection Surface Only § 57.15020 Life jackets and belts. Life jackets or belts shall be worn where there is...

  4. 30 CFR 56.15020 - Life jackets and belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Life jackets and belts. 56.15020 Section 56.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... § 56.15020 Life jackets and belts. Life jackets or belts shall be worn where there is danger from...

  5. 30 CFR 57.15020 - Life jackets and belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Life jackets and belts. 57.15020 Section 57.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Protection Surface Only § 57.15020 Life jackets and belts. Life jackets or belts shall be worn where there is...

  6. 30 CFR 56.15020 - Life jackets and belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Life jackets and belts. 56.15020 Section 56.15020 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... § 56.15020 Life jackets and belts. Life jackets or belts shall be worn where there is danger from...

  7. Early Clearing of the Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Ward, Wm. R.

    2005-03-01

    The ensemble of embryos destined to become the Jovian core may have excited the primordial asteroid belt and initiated a fragmentation cascade there. Thus, the majority of the belt mass may have drifted via gas drag into the terrestrial zone prior to the formation of Jupiter.

  8. The Idaho cobalt belt

    USGS Publications Warehouse

    Bookstrom, Arthur A.

    2013-01-01

    The Idaho cobalt belt (ICB) is a northwest-trending belt of cobalt (Co) +/- copper (Cu)-bearing deposits and prospects in the Salmon River Mountains of east-central Idaho, U.S.A. The ICB is about 55 km long and 10 km long in its central part, which contains multiple strata-bound ore zones in the Blackbird mine area. The Black Pine and Iron Creek Co-Cu prospects are southeast of Blackbird, and the Tinkers Pride, Bonanza Copper, Elk Creek, and Salmon Canyon Copper prospects are northwest of Blackbird.

  9. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Belt air course ventilation. 75.350 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.350 Belt air course ventilation. (a) The belt air course must not be used as a return air course; and except as provided in paragraph...

  10. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Belt air course ventilation. 75.350 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.350 Belt air course ventilation. (a) The belt air course must not be used as a return air course; and except as provided in paragraph...

  11. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Belt air course ventilation. 75.350 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.350 Belt air course ventilation. (a) The belt air course must not be used as a return air course; and except as provided in paragraph...

  12. 30 CFR 75.350 - Belt air course ventilation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Belt air course ventilation. 75.350 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.350 Belt air course ventilation. (a) The belt air course must not be used as a return air course; and except as provided in paragraph...

  13. Metamorphic belts of Anatolia

    NASA Astrophysics Data System (ADS)

    Oberhänsli, Roland; Prouteau, Amaury; Candan, Osman; Bousquet, Romain

    2015-04-01

    Investigating metamorphic rocks from high-pressure/low-temperature (HP/LT) belts that formed during the closure of several oceanic branches, building up the present Anatolia continental micro-plate gives insight to the palaeogeography of the Neotethys Ocean in Anatolia. Two coherent HP/LT metamorphic belts, the Tavşanlı Zone (distal Gondwana margin) and the Ören-Afyon-Bolkardağ Zone (proximal Gondwana margin), parallel their non-metamorphosed equivalent (the Tauride Carbonate Platform) from the Aegean coast in NW Anatolia to southern Central Anatolia. P-T conditions and timing of metamorphism in the Ören-Afyon-Bolkardağ Zone (>70?-65 Ma; 0.8-1.2 GPa/330-420°C) contrast those published for the overlying Tavşanlı Zone (88-78 Ma; 2.4 GPa/500 °C). These belts trace the southern Neotethys suture connecting the Vardar suture in the Hellenides to the Inner Tauride suture along the southern border of the Kirşehir Complex in Central Anatolia. Eastwards, these belts are capped by the Oligo-Miocene Sivas Basin. Another HP/LT metamorphic belt, in the Alanya and Bitlis regions, outlines the southern flank of the Tauride Carbonate Platform. In the Alanya Nappes, south of the Taurides, eclogites and blueschists yielded metamorphic ages around 82-80 Ma (zircon U-Pb and phengite Ar-Ar data). The Alanya-Bitlis HP belt testifies an additional suture not comparable to the northerly Tavşanlı and Ören-Afyon belts, thus implying an additional oceanic branch of the Neotethys. The most likely eastern lateral continuation of this HP belt is the Bitlis Massif, in SE Turkey. There, eclogites (1.9-2.4 GPa/480-540°C) occur within calc-arenitic meta-sediments and in gneisses of the metamorphic (Barrovian-type) basement. Zircon U-Pb ages revealed 84.4-82.4 Ma for peak metamorphism. Carpholite-bearing HP/LT metasediments representing the stratigraphic cover of the Bitlis Massif underwent 0.8-1.2 GPa/340-400°C at 79-74 Ma (Ar-Ar on white mica). These conditions compares to the Tav

  14. Folding superfunnel to describe cooperative folding of interacting proteins.

    PubMed

    Smeller, László

    2016-07-01

    This paper proposes a generalization of the well-known folding funnel concept of proteins. In the funnel model the polypeptide chain is treated as an individual object not interacting with other proteins. Since biological systems are considerably crowded, protein-protein interaction is a fundamental feature during the life cycle of proteins. The folding superfunnel proposed here describes the folding process of interacting proteins in various situations. The first example discussed is the folding of the freshly synthesized protein with the aid of chaperones. Another important aspect of protein-protein interactions is the folding of the recently characterized intrinsically disordered proteins, where binding to target proteins plays a crucial role in the completion of the folding process. The third scenario where the folding superfunnel is used is the formation of aggregates from destabilized proteins, which is an important factor in case of several conformational diseases. The folding superfunnel constructed here with the minimal assumption about the interaction potential explains all three cases mentioned above. Proteins 2016; 84:1009-1016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  15. 14 CFR 125.211 - Seat and safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Seat and safety belts. 125.211 Section 125... Requirements § 125.211 Seat and safety belts. (a) No person may operate an airplane unless there are available... the airplane who is at least 2 years old; and (2) An approved safety belt for separate use by each...

  16. Overrepresentation of seat belt non-users in traffic crashes

    DOT National Transportation Integrated Search

    1988-04-01

    This study used observations of driver belt use linked with driver history information to conclude that non-users of belts are overrepresented in traffic crashes. Examining average numbers of accidents and violations per observed belted and unbelted ...

  17. Jupiter's Colorful Cloud Belts

    NASA Image and Video Library

    2018-01-12

    Colorful swirling cloud belts dominate Jupiter's southern hemisphere in this image captured by NASA's Juno spacecraft. Jupiter appears in this color-enhanced image as a tapestry of vibrant cloud bands and storms. The dark region in the far left is called the South Temperate Belt. Intersecting the belt is a ghost-like feature of slithering white clouds. This is the largest feature in Jupiter's low latitudes that's a cyclone (rotating with clockwise motion). This image was taken on Dec. 16, 2017 at 10:12 PST (1:12 p.m. EST), as Juno performed its tenth close flyby of Jupiter. At the time the image was taken, the spacecraft was about 8,453 miles (13,604 kilometers) from the tops of the clouds of the planet at a latitude of 27.9 degrees south. The spatial scale in this image is 5.6 miles/pixel (9.1 kilometers/pixel). Citizen scientist Kevin M. Gill processed this image using data from the JunoCam imager. https://photojournal.jpl.nasa.gov/catalog/PIA21974

  18. Extreme Folding

    NASA Astrophysics Data System (ADS)

    Demaine, Erik

    2012-02-01

    Our understanding of the mathematics and algorithms behind paper folding, and geometric folding in general, has increased dramatically over the past several years. These developments have found a surprisingly broad range of applications. In the art of origami, it has helped spur the technical origami revolution. In engineering and science, it has helped solve problems in areas such as manufacturing, robotics, graphics, and protein folding. On the recreational side, it has led to new kinds of folding puzzles and magic. I will give an overview of the mathematics and algorithms of folding, with a focus on new mathematics and sculpture.

  19. Scenarios for the Evolution of Asteroid Belts

    NASA Image and Video Library

    2012-11-01

    This illustration shows three possible scenarios for the evolution of asteroid belts. At the top, a Jupiter-size planet migrates through the asteroid belt, scattering material and inhibiting the formation of life on planets.

  20. Space Weather Effects in the Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Baker, D. N.; Erickson, P. J.; Fennell, J. F.; Foster, J. C.; Jaynes, A. N.; Verronen, P. T.

    2018-02-01

    The first major scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or belts, of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. Recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed many novel properties of the radiation belts, especially for electrons at highly relativistic and ultra-relativistic kinetic energies. In this review we summarize the space weather impacts of the radiation belts. We demonstrate that many remarkable features of energetic particle changes are driven by strong solar and solar wind forcings. Recent comprehensive data show broadly and in many ways how high energy particles are accelerated, transported, and lost in the magnetosphere due to interplanetary shock wave interactions, coronal mass ejection impacts, and high-speed solar wind streams. We also discuss how radiation belt particles are intimately tied to other parts of the geospace system through atmosphere, ionosphere, and plasmasphere coupling. The new data have in many ways rewritten the textbooks about the radiation belts as a key space weather threat to human technological systems.

  1. Factors related to nonuse of seat belts in Michigan.

    DOT National Transportation Integrated Search

    1987-09-01

    This study combined direct observation of seat belt use with interview methods to : identify factors related to seat belt use in a state with a mandatory seat belt use law. Trained : observers recorded restraint use for a probability sample of motori...

  2. A study of nighttime seat belt use in Indiana

    DOT National Transportation Integrated Search

    2007-05-01

    Overall belt use rates observed during the daytime and nighttime survey waves are presented in Table 2. Belt use observed during the daytime and nighttime pre-mobilization waves was very similar. During the post-mobilization waves, daytime belt use w...

  3. Effectiveness of high school safety belt instruction

    DOT National Transportation Integrated Search

    1982-12-01

    The Effectiveness of High School Safety Belt Instruction was developed during a two-phased project. In Phase I, Focus Group Activities were conducted to determine whether audiovisual safety belt instructional materials assembled by the National Highw...

  4. Pilot tests of a seat belt gearshift delay on the belt use of commercial fleet drivers : traffic tech.

    DOT National Transportation Integrated Search

    2010-04-01

    Wearing a seat belt has been shown effective in avoiding : or reducing serious injury due to traffic crashes. While : belt use rates in the United States increased from under : 60% in 1994 to 83% in 2008, a substantial number of drivers : still drive...

  5. Coseismic fault-related fold model, growth structure, and the historic multisegment blind thrust earthquake on the basement-involved Yoro thrust, central Japan

    NASA Astrophysics Data System (ADS)

    Ishiyama, Tatsuya; Mueller, Karl; Sato, Hiroshi; Togo, Masami

    2007-03-01

    We use high-resolution seismic reflection profiles, boring transects, and mapping of fold scarps that deform late Quaternary and Holocene sediments to define the kinematic evolution, subsurface geometry, coseismic behavior, and fault slip rates for an active, basement-involved blind thrust system in central Japan. Coseismic fold scarps on the Yoro basement-involved fold are defined by narrow fold limbs and angular hinges on seismic profiles, suggesting that at least 3.9 km of fault slip is consumed by wedge thrust folding in the upper 10 km of the crust. The close coincidence and kinematic link between folded horizons and the underlying thrust geometry indicate that the Yoro basement-involved fold has accommodated slip at an average rate of 3.2 ± 0.1 mm/yr on a shallowly west dipping thrust fault since early Pleistocene time. Past large-magnitude earthquakes, including an historic M˜7.7 event in A.D. 1586 that occurred on the Yoro blind thrust, are shown to have produced discrete folding by curved hinge kink band migration above the eastward propagating tip of the wedge thrust. Coseismic fold scarps formed during the A.D. 1586 earthquake can be traced along the en echelon active folds that extend for at least 60 km, in spite of different styles of folding along the apparently hard-linked Nobi-Ise blind thrust system. We thus emphasize the importance of this multisegment earthquake rupture across these structures and the potential risk for similar future events in en echelon active fold and thrust belts.

  6. The Collisional Evolution of the Main Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Brož, M.; O'Brien, D. P.; Campo Bagatin, A.; Morbidelli, A.; Marchi, S.

    Collisional and dynamical models of the main asteroid belt allow us to glean insights into planetesimal- and planet-formation scenarios as well as how the main belt reached its current state. Here we discuss many of the processes affecting asteroidal evolution and the constraints that can be used to test collisional model results. We argue the main belt's wavy size-frequency distribution for diameter D < 100-km asteroids is increasingly a byproduct of comminution as one goes to smaller sizes, with its shape a fossil-like remnant of a violent early epoch. Most D > 100-km asteroids, however, are primordial, with their physical properties set by planetesimal formation and accretion processes. The main-belt size distribution as a whole has evolved into a collisional steady state, and it has possibly been in that state for billions of years. Asteroid families provide a critical historical record of main-belt collisions. The heavily depleted and largely dispersed "ghost families," however, may hold the key to understanding what happened in the primordial days of the main belt. New asteroidal fragments are steadily created by both collisions and mass shedding events via YORP spinup processes. A fraction of this population, in the form of D < 30 km fragments, go on to escape the main belt via the Yarkovsky/YORP effects and gravitational resonances, thereby creating a quasi-steady-state population of planet-crossing and near-Earth asteroids. These populations go on to bombard all inner solar system worlds. By carefully interpreting the cratering records they produce, it is possible to constrain how portions of the main-belt population have evolved with time.

  7. An Empirical Planetesimal Belt Radius–Stellar Luminosity Relation

    NASA Astrophysics Data System (ADS)

    Matrà, L.; Marino, S.; Kennedy, G. M.; Wyatt, M. C.; Öberg, K. I.; Wilner, D. J.

    2018-05-01

    Resolved observations of millimeter-sized dust, tracing larger planetesimals, have pinpointed the location of 26 Edgeworth–Kuiper Belt analogs. We report that a belt’s distance R to its host star correlates with the star’s luminosity L ⋆, following R\\propto {L}\\star 0.19 with a low intrinsic scatter of ∼17%. Remarkably, our Edgeworth–Kuiper Belt in the solar system and the two CO snow lines imaged in protoplanetary disks lie close to this R–L ⋆ relation, suggestive of an intrinsic relationship between protoplanetary disk structures and belt locations. To test the effect of bias on the relation, we use a Monte Carlo approach and simulate uncorrelated model populations of belts. We find that observational bias could produce the slope and intercept of the R–L ⋆ relation but is unable to reproduce its low scatter. We then repeat the simulation taking into account the collisional evolution of belts, following the steady-state model that fits the belt population as observed through infrared excesses. This significantly improves the fit by lowering the scatter of the simulated R–L ⋆ relation; however, this scatter remains only marginally consistent with the one observed. The inability of observational bias and collisional evolution alone to reproduce the tight relationship between belt radius and stellar luminosity could indicate that planetesimal belts form at preferential locations within protoplanetary disks. The similar trend for CO snow line locations would then indicate that the formation of planetesimals or planets in the outer regions of planetary systems is linked to the volatility of their building blocks, as postulated by planet formation models.

  8. RNA folding: structure prediction, folding kinetics and ion electrostatics.

    PubMed

    Tan, Zhijie; Zhang, Wenbing; Shi, Yazhou; Wang, Fenghua

    2015-01-01

    Beyond the "traditional" functions such as gene storage, transport and protein synthesis, recent discoveries reveal that RNAs have important "new" biological functions including the RNA silence and gene regulation of riboswitch. Such functions of noncoding RNAs are strongly coupled to the RNA structures and proper structure change, which naturally leads to the RNA folding problem including structure prediction and folding kinetics. Due to the polyanionic nature of RNAs, RNA folding structure, stability and kinetics are strongly coupled to the ion condition of solution. The main focus of this chapter is to review the recent progress in the three major aspects in RNA folding problem: structure prediction, folding kinetics and ion electrostatics. This chapter will introduce both the recent experimental and theoretical progress, while emphasize the theoretical modelling on the three aspects in RNA folding.

  9. Active Flexural-Slip Faulting: Controls Exerted by Stratigraphy, Geometry, and Fold Kinematics

    NASA Astrophysics Data System (ADS)

    Li, Tao; Chen, Jie; Thompson Jobe, Jessica A.; Burbank, Douglas W.

    2017-10-01

    Flexural slip plays an important role in accommodating fold growth, and its topographic expression, flexural-slip fault (FSF) scarps, may be one of the most commonly occurring secondary structures in areas dominated by active thrusts and folds. Where FSF scarps are present and what factors control their occurrence, however, are typically poorly known. Through an investigation of clearly expressed FSF scarps, well-preserved fluvial terraces, and well-exposed bedrock at eight sites in the Pamir-Tian Shan convergent zone and Kuche fold belt, NW China, we summarize the most favorable conditions for active flexural-slip faulting. Our study yields six key results. First, flexural slip operates commonly in well-layered beds, although uncommonly can occur in massive, poorly layered beds as well. Second, in well-layered beds, the slip surface is commonly located either (a) close to the contact of competent and incompetent beds or (b) within thin incompetent beds. Third, FSF scarps are always found overlying steep beds with dips of 30-100°. Fourth, slip surfaces are typically spaced between 10 and 440 m but can reach up to 600 m. Fifth, FSF scarps at most sites can be observed far away from the hinge-migrated fold scarps, suggesting that compared to hinge migration, limb rotation is generally required to accumulate flexural slip and produce associated topographic scarps. Finally, a higher regional convergent rate seems to facilitate the creation of FSF scarps more often than lower rates, whereas well-preserved, old terraces capped by thin deposits are more likely to record FSF scarps than unevenly preserved, young terraces with thick sedimentary caps.

  10. 36 CFR 1004.15 - Safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Safety belts. 1004.15 Section 1004.15 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.15 Safety... administered by the Presidio Trust will have the safety belt or child restraint system properly fastened at all...

  11. 36 CFR 1004.15 - Safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Safety belts. 1004.15 Section 1004.15 Parks, Forests, and Public Property PRESIDIO TRUST VEHICLES AND TRAFFIC SAFETY § 1004.15 Safety... administered by the Presidio Trust will have the safety belt or child restraint system properly fastened at all...

  12. Neptune's Eccentricity and the Nature of the Kuiper Belt

    NASA Technical Reports Server (NTRS)

    Ward, William R.; Hahn, Joseph M.

    1998-01-01

    The small eccentricity of Neptune may be a direct consequence of apsidal wave interaction with the trans-Neptune population of debris called the Kuiper belt. The Kuiper belt is subject to resonant perturbations from Neptune, so that the transport of angular momentum by density waves can result in orbital evolution of Neptune as well as changes in the structure of the Kuiper belt. In particular, for a belt eroded out to the vicinity of Neptune's 2:1 resonance at about 48 astronomical units, Neptune's eccentricity can damp to its current value over the age of the solar system if the belt contains slightly more than an earth mass of material out to about 75 astronomical units.

  13. 2009 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2009-07-01

    The objective of this study was to establish 2009 safety belt and child safety seat usage rates in Kentucky. The 2009 survey continues to document the results after enactment of original "secondary enforcement" statewide mandatory safety belt law in ...

  14. 2002 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2002-07-01

    The objective of this study was to establish 2002 safety belt and child safety seat usage rates in Kentucky. The 2002 survey continues to document the results after enactment of original "secondary enforcement" statewide mandatory safety belt law in ...

  15. 2001 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2001-08-01

    The objective of this study was to establish 2001 safety belt and child safety seat usage rates in Kentucky. The 2001 survey continues to document the results after enactment of original "secondary enforcement" statewide mandatory safety belt law in ...

  16. How Does Your Protein Fold? Elucidating the Apomyoglobin Folding Pathway

    PubMed Central

    Dyson, H. Jane; Wright, Peter E.

    2017-01-01

    Conspectus Although each type of protein fold and in some cases individual proteins within a fold classification can have very different mechanisms of folding, the underlying biophysical and biochemical principles that operate to cause a linear polypeptide chain to fold into a globular structure must be the same. In an aqueous solution, the protein takes up the thermodynamically most stable structure, but the pathway along which the polypeptide proceeds in order to reach that structure is a function of the amino acid sequence, which must be the final determining factor, not only in shaping the final folded structure, but in dictating the folding pathway. A number of groups have focused on a single protein or group of proteins, to determine in detail the factors that influence the rate and mechanism of folding in a defined system, with the hope that hypothesis-driven experiments can elucidate the underlying principles governing the folding process. Our research group has focused on the folding of the globin family of proteins, and in particular on the monomeric protein apomyoglobin. Apomyoglobin (apoMb) folds relatively slowly (~2 seconds) via an ensemble of obligatory intermediates that form rapidly after the initiation of folding. The folding pathway can be dissected using rapid-mixing techniques, which can probe processes in the millisecond time range. Stopped-flow measurements detected by circular dichroism (CD) or fluorescence spectroscopy give information on the rates of folding events. Quench-flow experiments utilize the differential rates of hydrogen-deuterium exchange of amide protons protected in parts of the structure that are folded early; protection of amides can be detected by mass spectrometry or proton nuclear magnetic resonance spectroscopy (NMR). In addition, apoMb forms an intermediate at equilibrium at pH ~ 4, which is sufficiently stable for it to be structurally characterized by solution methods such as CD, fluorescence and NMR spectroscopies

  17. 2010 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2010-07-01

    The objective of this study was to establish 2010 safety belt and child safety seat usage rates in Kentucky. The 2010 survey continues to document the results after enactment of the original "second enforcement" statewide mandatory safety belt law in...

  18. 2007 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2007-08-01

    The objective of this study was to establish 2007 safety belt and child safety seat usage rates in Kentucky. The 2007 survey continues to document the results after enactment of the initial "second enforcement" statewide mandatory safety belt law in ...

  19. 2006 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2006-08-01

    The objective of this study was to establish 2006 safety belt and child safety seat usage rates in Kentucky. The 2006 survey continues to document the results after enactment of the initial "second enforcement" statewide mandatory safety belt law in ...

  20. 2008 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2008-08-01

    The objective of this study was to establish 2008 safety belt and child safety seat usage rates in Kentucky. The 2008 survey continues to document the results after enactment of the initial "second enforcement" statewide mandatory safety belt law in ...

  1. 2005 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2005-08-01

    The objective of this study was to establish 2005 safety belt and child safety seat usage rates in Kentucky. The 2005 survey continues to document the results after enactment of the initial "second enforcement" statewide mandatory safety belt law in ...

  2. Wearing an abdominal belt increases diastolic blood pressure.

    PubMed

    Rafacz, W; McGill, S M

    1996-09-01

    The purpose of this study was to determine the effect of wearing an abdominal belt on blood pressure (systolic and diastolic) and heart rate during a variety of tasks. The belt was typical of the elastic type with suspenders and Velcro tabs for cinching the belt snug. The tasks performed included sitting at rest, sitting with the torso inclined forward at 45 degrees, standing with the torso inclined forward at 45 degrees (with and without holding an 11-kg weight), a trunk axial rotation task, and squat lifting. Blood pressure was monitored noninvasively with a FINAPRES blood pressure monitor. Twenty healthy men performed each task with and without the abdominal belt. Although no significant increases in mean systolic blood pressure or heart rate were found, there was a significant increase in diastolic blood pressure in all conditions. All people considering wearing an abdominal belt should also consider the risks and liability associated with the additional cardiovascular load, particularly heart attack and stroke.

  3. Survey of current situation in radiation belt modeling

    NASA Technical Reports Server (NTRS)

    Fung, Shing F.

    2004-01-01

    The study of Earth's radiation belts is one of the oldest subjects in space physics. Despite the tremendous progress made in the last four decades, we still lack a complete understanding of the radiation belts in terms of their configurations, dynamics, and detailed physical accounts of their sources and sinks. The static nature of early empirical trapped radiation models, for examples, the NASA AP-8 and AE-8 models, renders those models inappropriate for predicting short-term radiation belt behaviors associated with geomagnetic storms and substorms. Due to incomplete data coverage, these models are also inaccurate at low altitudes (e.g., <1000 km) where many robotic and human space flights occur. The availability of radiation data from modern space missions and advancement in physical modeling and data management techniques have now allowed the development of new empirical and physical radiation belt models. In this paper, we will review the status of modern radiation belt modeling. Published by Elsevier Ltd on behalf of COSPAR.

  4. Xenotime-(Y) formation from zircon dissolution-precipitation and HREE fractionation: an example from a metamorphosed phosphatic sandstone, Espinhaço fold belt (Brazil)

    NASA Astrophysics Data System (ADS)

    Franz, Gerhard; Morteani, Giulio; Rhede, Dieter

    2015-10-01

    We present an example where xenotime-(Y) together with metamorphic zircon replaces detrital zircon in a phosphatic sandstone from the Mesoproterozoic Espinhaço fold belt, Brazil, in a dissolution-precipitation reaction: {{zircon}}1 ( {{relict}} ) + {{P-}}{{bearing fluid}} = {{zircon}}2 ( {{metamorphic}} ) + {{xenotime}}. During the Brasiliano orogeny at 634 ± 19 Ma, the rocks experienced amphibolite facies metamorphism at ≥0.6 GPa/ 550 ± 37 °C (Southern Espinhaço) and ≥0.6 GPa/ 570 ± 35 °C (Northern Espinhaço), constrained by Zr-in-rutile and Ti-in-quartz thermometry and the presence of kyanite + muscovite + quartz. Many of the rocks show unusual rare earth element (REE) patterns with a hump at Gd-Tb-Dy and depletion in light REE. Detrital zircons (with relict ages between 1.5 and 3.3 Ga) show varying degrees of replacement as indicated by the presence of xenotime and associated porosity, from almost pristine to complete alteration. Textural evidence indicates local mobility of Zr and REE at the scale of the thin section. Xenotime-(Y) occurs together with other phosphates, mainly augelite, lazulite, and minerals of the svanbergite-crandallite-goyacite-florencite group. Xenotime-(Y) is very heterogeneous and reaches unusually high contents of up to 14 wt% Gd2O3, 13 wt% Dy2O3, and 3 wt% Tb2O3, corresponding to ≤0.36 REE atoms per formula unit due to the exchange Y = REE. The heavy REE patterns of xenotime-(Y) therefore show variable enrichment in individual elements, which explains the characteristic hump at Gd-Tb-Dy in the REE patterns of the whole rock. Although the rocks reached amphibolite facies conditions, textures indicate that formation of xenotime likely occurred during the early stages of diagenesis—metamorphism. Comparison with REE concentrations in xenotime-(Y) from the literature shows that selective REE incorporation into xenotime-(Y) is controlled by interaction with P-bearing hydrous fluids.

  5. An Effective Belt Conveyor for Underground Ore Transportation Systems

    NASA Astrophysics Data System (ADS)

    Krol, Robert; Kawalec, Witold; Gladysiewicz, Lech

    2017-12-01

    Raw material transportation generates a substantial share of costs in the mining industry. Mining companies are therefore determined to improve the effectiveness of their transportation system, focusing on solutions that increase both its energy efficiency and reliability while keeping maintenance costs low. In the underground copper ore operations in Poland’s KGHM mines vast and complex belt conveyor systems have been used for horizontal haulage of the run-of-mine ore from mining departments to shafts. Basing upon a long-time experience in the field of analysing, testing, designing and computing of belt conveyor equipment with regard to specific operational conditions, the improvements to the standard design of an underground belt conveyor for ore transportation have been proposed. As the key elements of a belt conveyor, the energy-efficient conveyor belt and optimised carrying idlers have been developed for the new generation of underground conveyors. The proposed solutions were tested individually on the specially constructed test stands in the laboratory and in the experimental belt conveyor that was built up with the use of prototype parts and commissioned for the regular ore haulage in a mining department in the KGHM underground mine “Lubin”. Its work was monitored and the recorded operational parameters (loadings, stresses and strains, energy dissipation, belt tracking) were compared with those previously collected on a reference (standard) conveyor. These in-situ measurements have proved that the proposed solutions will return with significant energy savings and lower maintenance costs. Calculations made on the basis of measurement results in the specialized belt conveyor designing software allow to estimate the possible savings if the modernized conveyors supersede the standard ones in a large belt conveying system.

  6. Factors Influencing Occupant-To-Seat Belt Interaction in Far-Side Crashes

    PubMed Central

    Douglas, C.A.; Fildes, B.N.; Gibson, T.J.; Boström, O.; Pintar, F.A.

    2007-01-01

    Seat belt interaction with a far-side occupant’s shoulder and thorax is critical to governing excursion towards the struck-side of the vehicle in side impact. In this study, occupant-to-belt interaction was simulated using a modified MADYMO human model and finite element belts. Quasi-static tests with volunteers and dynamic sled tests with PMHS and WorldSID were used for model validation and comparison. Parameter studies were then undertaken to quantify the effect of impact direction, seat belt geometry and pretension on occupant-to-seat belt interaction. Results suggest that lowering the D-ring and increasing pretension reduces the likelihood of the belt slipping off the shoulder. Anthropometry was also shown to influence restraint provided by the shoulder belt. Furthermore, the belt may slip off the occupant’s shoulder at impact angles greater than 40 degrees from frontal when no pretension is used. However, the addition of pretension allowed the shoulder to engage the belt in all impacts from 30 to 90 degrees. PMID:18184500

  7. Estimating seat belt effectiveness using matched-pair cohort methods.

    PubMed

    Cummings, Peter; Wells, James D; Rivara, Frederick P

    2003-01-01

    Using US data for 1986-1998 fatal crashes, we employed matched-pair analysis methods to estimate that the relative risk of death among belted compared with unbelted occupants was 0.39 (95% confidence interval (CI) 0.37-0.41). This differs from relative risk estimates of about 0.55 in studies that used crash data collected prior to 1986. Using 1975-1998 data, we examined and rejected three theories that might explain the difference between our estimate and older estimates: (1) differences in the analysis methods; (2) changes related to car model year; (3) changes in crash characteristics over time. A fourth theory, that the introduction of seat belt laws would induce some survivors to claim belt use when they were not restrained, could explain part of the difference in our estimate and older estimates; but even in states without seat belt laws, from 1986 through 1998, the relative risk estimate was 0.45 (95% CI 0.39-0.52). All of the difference between our estimate and older estimates could be explained by some misclassification of seat belt use. Relative risk estimates would move away from 1, toward their true value, if misclassification of both the belted and unbelted decreased over time, or if the degree of misclassification remained constant, as the prevalence of belt use increased. We conclude that estimates of seat belt effects based upon data prior to 1986 may be biased toward 1 by misclassification.

  8. 2017 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2017-08-01

    The use of safety belts and child safety seats is a proven means of reducing injuries to motor vehicle occupants involved in traffic crashes. There have been various methods used in efforts to increase safety belt and safety seat usage. Past efforts ...

  9. 2016 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2016-08-01

    The use of safety belts and child safety seats is a proven means of reducing injuries to motor vehicle occupants involved in traffic crashes. There have been various methods used in efforts to increase safety belt and safety seat usage. Past efforts ...

  10. 2015 safety belt usage survey in Kentucky.

    DOT National Transportation Integrated Search

    2015-08-01

    The use of safety belts and child safety seats has been shown to be an effective means of : reducing injuries to motor-vehicle occupants involved in traffic crashes. There have been various : methods used in efforts to increase safety belt and safety...

  11. 2001 Safety belt usage survey in Kentucky

    DOT National Transportation Integrated Search

    2001-08-01

    The objective of this study was to establish 2001 safety belt and child safety seat usage rates in Kentucky. The 2001 survey continues to document the results after enactment of a statewide mandatory safety belt law in 1994. It also documented the lo...

  12. 2002 safety belt usage survey in Kentucky

    DOT National Transportation Integrated Search

    2002-07-01

    The objective of this study was to establish 2002 safety belt and child safety seat usage rates in Kentucky. The 2002 survey continues to document the results after enactment of a statewide mandatory safety belt law in 1994. Data were collected at 20...

  13. 2000 Safety belt usage survey in Kentucky

    DOT National Transportation Integrated Search

    2000-08-01

    The objective of this study was to establish 2000 safety belt and child safety seat usage rates in Kentucky. The 2000 survey continues to document the results after enactment of a statewide mandatory safety belt law in 1994. Data were collected at 20...

  14. Seat belt use, especially among low-use drivers, increases as Florida upgrades to primary seat belt enforcement : traffic tech.

    DOT National Transportation Integrated Search

    2012-08-01

    As a secondary seat belt law State, Florida had worked : for many years to encourage more drivers to wear : their seat belts by participating in annual Click It or : Ticket (CIOT) mobilizations, and by conducting special : programs in rural areas of ...

  15. Use of safety restraints by law enforcement officers following safety belt training and passage of a statewide belt law

    DOT National Transportation Integrated Search

    1988-04-01

    The report describes work performed in 1984-1985 to develop and evaluate a safety belt program designed for the Maryland State Police - Belt Use Campaign for Law Enforcement (BUCLE), and an evaluation conducted in 1987 to determine the impact of the ...

  16. "Abomination"--life as a Bible belt gay.

    PubMed

    Barton, Bernadette

    2010-01-01

    Drawing on observation, autoethnography, and audio-taped interviews, this article explores the religious backgrounds and experiences of Bible Belt gays. In the Bible Belt, Christianity is not confined to Sunday worship. Christian crosses, messages, paraphernalia, music, news, and attitudes permeate everyday settings. Consequently, Christian fundamentalist dogma about homosexuality-that homosexuals are bad, diseased, perverse, sinful, other, and inferior-is cumulatively bolstered within a variety of other social institutions and environments in the Bible Belt. Of the 46 lesbians and gay men interviewed for this study (age 18-74 years), most describe living through spirit-crushing experiences of isolation, abuse, and self-loathing. This article argues that the geographic region of the Bible Belt intersects with religious-based homophobia. Informants explained that negative social attitudes about homosexuality caused a range of harmful consequences in their lives including the fear of going to hell, depression, low self-esteem, and feelings of worthlessness.

  17. 47. INTERIOR VIEW, DETAIL OF CONVEYOR BELT SYSTEM SYSTEM WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    47. INTERIOR VIEW, DETAIL OF CONVEYOR BELT SYSTEM SYSTEM WITH BACK BELT DROPPING HARDENED NAILS ON THE FRONT BELT TO BE TEMPERED; MOTION STOPPED - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

  18. Using haptic feedback to increase seat belt use : traffic tech.

    DOT National Transportation Integrated Search

    2011-07-01

    The legacy of research on increasing seat belt use has : focused on enactment of seat belt legislation, public education, : high-visibility police enforcement, and seat belt : reminder systems. Several behavioral programs have : produced large, susta...

  19. Factors related to increasing safety belt use in states with safety belt use laws : second annual report to Congress

    DOT National Transportation Integrated Search

    1989-01-01

    This report is the second in a series of four annual reports to the Congress on provisions of state safety belt use laws and other programmatic factors related to increasing safety belt use levels. The first Congressional Report reviewed what was kno...

  20. Restoring paleomagnetic data in complex superposed folding settings: The Boltaña anticline (Southern Pyrenees)

    NASA Astrophysics Data System (ADS)

    Mochales, T.; Pueyo, E. L.; Casas, A. M.; Barnolas, A.

    2016-03-01

    Complex kinematic scenarios in fold-and-thrust belts often produce superposed and non-coaxial folding. Interpretation of primary linear indicators must be based on a careful restoration to the undeformed stage following the reverse order of the deformation events. Therefore, sequential restoration to the ancient coordinate system is of key importance to obtain reliable kinematic interpretations using paleomagnetic data. In this paper, a new paleomagnetic study in the western flank of the Boltaña anticline (Southern Pyrenees) illustrates a case study of a complex tectonic setting having superposed, non-coaxial folds. The first stage of NW-SE folding linked to the oblique Boltaña anticline took place during Lutetian times. The second stage was linked to the vertical axis rotation and placed the Boltaña anticline in its present-day N-S configuration. Our data support a long-lasting Lutetian to Priabonian period with main rotational activity during the Bartonian-Priabonian; other authors support a VAR coeval with anticlinal growth. The third stage resulted in southwards tilting related to the emplacement of the N120E striking Guarga basement thrust (Oligocene-Early Miocene). Based on this deformational history, a sequential restoration was applied and compared with the classic bedding correction. At the site scale, single bedding correction gives errors ranging between 31° and - 31° in the estimation of vertical axis rotations. At the locality scale, in sites grouped in three folds (from W to E Arbella, Planillo and San Felizes), the bedding corrected data display rotation values in accordance with those found in the Ainsa Basin by other authors. Sequential restoration (based on the afore-mentioned evolution in three-steps) improves both some locality-means and the internal consistency of the data. Therefore, reasonably-constrained sequential restoration becomes essential to reconstruct the actual history of superposed folding areas.

  1. Association of Blood and Seminal Plasma Cadmium and Lead Levels With Semen Quality in Non-Occupationally Exposed Infertile Men in Abakaliki, South East Nigeria

    PubMed Central

    Famurewa, Ademola C.; Ugwuja, Emmanuel I.

    2017-01-01

    Objective: To evaluate association of blood and seminal plasma lead and cadmium with sperm quality of non-occupationally exposed male partners of couples with infertility. Materials and methods: A cross-sectional study was conducted on 75 men aged 20-45 years (mean = 37.1 ± 7.0 yrs.) with infertility recruited from the Fertility Clinic of a hospital in Abakaliki. Sperm count done in accordance with the WHO guidelines was used to classify the participants as normospamia, oligospermia and azospermia. Atomic absorption spectrophotometer was used to determine lead and cadmium levels in plasma from blood and semen. Results: There were 15 azospermics, 22 oligospermics and 36 normospermics. Seminal and blood plasma cadmium as well as blood plasma lead were significantly (p < 0.01) higher in azospermic and oligospermic men compared to normospermic men. However, while seminal plasma lead was significantly (p < 0.05) higher in oligospermic and normospernic men than in azospermic men, the seminal plasma lead was comparable between oligospermic and normospermic men. Significant inverse associations (p < 0.01) were found between blood and seminal cadmium levels and sperm count, motility and morphology; blood lead was inversely correlated with sperm count only. Conclusion: The study suggests that environmental exposure to cadmium and lead may contribute to development of poor sperm quality and infertility in men of reproductive age in Nigeria. PMID:29282417

  2. Structure of possible long-lived asteroid belts

    NASA Astrophysics Data System (ADS)

    Evans, N. W.; Tabachnik, S. A.

    2002-06-01

    High-resolution simulations are used to map out the detailed structure of two long-lived stable belts of asteroid orbits in the inner Solar system. The Vulcanoid belt extends from 0.09 to 0.20au, though with a gaps at 0.15 and 0.18au corresponding to de-stabilizing mean motion resonances with Mercury and Venus. As collisional evolution proceeds slower at larger heliocentric distances, km-sized or larger Vulcanoids are most likely to be found in the region between 0.16 and 0.18au. The optimum location to search is at geocentric ecliptic longitudes 9°<=|lg|<=10° and latitudes |βg|<1°. Dynamically speaking, the Earth-Mars belt between 1.08 and 1.28au is a stable repository for asteroids on nearly circular orbits. It is interrupted at 1.21au owing to the 3:4 commensurability with the Earth, while secular resonances with Saturn are troublesome beyond 1.17au. These detailed maps of the fine structure of the belts can be used to plan search methodologies. Strategies for detecting members of the belts are discussed, including the use of infrared wide-field imaging with VISTA, and forthcoming European Space Agency satellite missions such as GAIA and BepiColombo.

  3. Exploring the collisional evolution of the asteroid belt

    NASA Astrophysics Data System (ADS)

    Bottke, W.; Broz, M.; O'Brien, D.; Campo Bagatin, A.; Morbidelli, A.

    2014-07-01

    The asteroid belt is a remnant of planet-formation processes. By modeling its collisional and dynamical history, and linking the results to constraints, we can probe how the planets and small bodies formed and evolved. Some key model constraints are: (i) The wavy shape of the main-belt size distribution (SFD), with inflection points near 100-km, 10--20-km, 1 to a few km, and ˜0.1-km diameter; (ii) The number of asteroid families created by the catastrophic breakup of large asteroid bodies over the last ˜ 4 Gy, with the number of disrupted D > 100 km bodies as small as ˜20 or as large as 60; (iii) the flux of small asteroids derived from the main belt that have struck the Moon over the last 3.5 Ga --- crater SFDs on lunar terrains with known ages suggest the D < 0.1 km projectile population has not varied appreciably over this interval; (iv) Vesta has an intact basaltic crust with two very large basins, but only two, on its surface. Fits to these parameters allow us to predict the shape of the initial main-belt SFD after accretion and the approximate asteroid disruption scaling law, with the latter consistent with numerical hydrocode simulations. Overall, we find that the asteroid belt probably experienced the equivalent of ˜6--10 Gy of comminution over its history. This value may seem strange, considering the solar system is only 4.56 Gy old. One way to interpret it is that the main belt once had more mass that was eliminated by early dynamical processes between 4--4.56 Ga. This would allow for more early grinding, and it would suggest the main belt's wavy-shaped SFD is a ''fossil'' from a more violent early epoch. Simulations suggest that most D > 100 km bodies have been significantly battered, but only a fraction have been catastrophically disrupted. Conversely, most small asteroids today are byproducts of fragmentation events. These results are consistent with growing evidence that most of the prominent meteorite classes were produced by young asteroid

  4. Review of GEM Radiation Belt Dropout and Buildup Challenges

    NASA Astrophysics Data System (ADS)

    Tu, Weichao; Li, Wen; Morley, Steve; Albert, Jay

    2017-04-01

    In Summer 2015 the US NSF GEM (Geospace Environment Modeling) focus group named "Quantitative Assessment of Radiation Belt Modeling" started the "RB dropout" and "RB buildup" challenges, focused on quantitative modeling of the radiation belt buildups and dropouts. This is a community effort which includes selecting challenge events, gathering model inputs that are required to model the radiation belt dynamics during these events (e.g., various magnetospheric waves, plasmapause and density models, electron phase space density data), simulating the challenge events using different types of radiation belt models, and validating the model results by comparison to in situ observations of radiation belt electrons (from Van Allen Probes, THEMIS, GOES, LANL/GEO, etc). The goal is to quantitatively assess the relative importance of various acceleration, transport, and loss processes in the observed radiation belt dropouts and buildups. Since 2015, the community has selected four "challenge" events under four different categories: "storm-time enhancements", "non-storm enhancements", "storm-time dropouts", and "non-storm dropouts". Model inputs and data for each selected event have been coordinated and shared within the community to establish a common basis for simulations and testing. Modelers within and outside US with different types of radiation belt models (diffusion-type, diffusion-convection-type, test particle codes, etc.) have participated in our challenge and shared their simulation results and comparison with spacecraft measurements. Significant progress has been made in quantitative modeling of the radiation belt buildups and dropouts as well as accessing the modeling with new measures of model performance. In this presentation, I will review the activities from our "RB dropout" and "RB buildup" challenges and the progresses achieved in understanding radiation belt physics and improving model validation and verification.

  5. A comparison of muscle activation between back squats and belt squats.

    PubMed

    Evans, Thomas W; McLester, Cherilyn N; Howard, Jonathan H; McLester, John R; Calloway, Jimmy P

    2017-06-08

    A machine belt squat is a piece of equipment designed to allow the performance of squats while loading weight on the lifter's hips using a belt. The purpose of this investigation was to determine if belt squats differ from back squats in activation of the primary movers, and to determine the predictive capabilities of back squat load, training status, and anthropometric data on belt squat load. Thirty-one participants (16 males and 15 females) completed anthropometric measurements, a demographic questionnaire, a familiarization visit, and two testing visits, completing a 5 repetition maximum test for back squat and belt squat. Surface electromyography was used to measure muscle activation for the left and right vastus medialis (VMO), vastus lateralis (VLO), rectus femoris (RF), and gluteus maximus (GM). Comparison of muscle activation between the two exercises showed significant differences in the left GM (back squat: 0.84 ± 0.45, belt squat: 0.69 ± 0.22, p=0.015) and right GM (back squat: 0.86 ± 0.45, belt squat: 0.71 ± 0.29, p=0.004). Regression analysis computed significant prediction equations for belt squat load for general population, males, females, and advanced lifters. Overall, results indicate that belt squats may significantly differ in GM activation from back squats. Back squat load, as well as other variables, may be effective in accurately estimating appropriate belt squat load. These findings may help to more appropriately program for training with machine belt squats as a back squat alternative.

  6. States upgrade to primary enforcement seat belt laws : traffic tech.

    DOT National Transportation Integrated Search

    2011-09-01

    States with primary seat belt enforcement laws consistently : have higher observed daytime seat belt use rates than secondary : law States. Secondary belt law States, on the other : hand, consistently have more motor vehicle fatalities who : were not...

  7. Documenting How States Recently Upgraded to Primary Seat Belt Laws

    DOT National Transportation Integrated Search

    2011-09-01

    States with primary seat belt enforcement laws consistently have higher observed daytime belt use rates than : secondary law States. Secondary belt law States, on the other hand, consistently have more occupant fatalities who : were not restrained th...

  8. Asteroid Family Associations of Main-Belt Comets

    NASA Astrophysics Data System (ADS)

    Hsieh, Henry H.; Novakovic, Bojan; Kim, Yoonyoung; Brasser, Ramon

    2016-10-01

    We present a population-level analysis of the asteroid family associations of known main-belt comets or main-belt comet candidates (which, to date, have largely just been analyzed on individual bases as they have been discovered). In addition to family associations that have already been reported in the literature, we have identified dynamical relationships between 324P/La Sagra and the Alauda family, P/2015 X6 (PANSTARRS) and the Aeolia family, and P/2016 G1 (PANSTARRS) and the Adeona family. We will discuss the overall implications of these family associations, particularly as they pertain to the hypothesis that members of primitive asteroid family members may be more susceptible to producing observable sublimation-driven dust emission activity, and thus becoming main-belt comets. We will also discuss the significance of other dynamical and physical properties of a family or sub-family as they relate to the likelihood of that family containing one or more currently active main-belt comets.

  9. Tectono-metamorphic evolution of high-P/T and low-P/T metamorphic rocks in the Tia Complex, southern New England Fold Belt, eastern Australia: Insights from K-Ar chronology

    NASA Astrophysics Data System (ADS)

    Fukui, Shiro; Tsujimori, Tatsuki; Watanabe, Teruo; Itaya, Tetsumaru

    2012-10-01

    The Tia Complex in the southern New England Fold Belt is a poly-metamorphosed Late Paleozoic accretionary complex. It consists mainly of high-P/low-T type pumpellyite-actinolite facies (rare blueschist facies) schists, phyllite and serpentinite (T = 300 °C and P = 5 kbar), and low-P/high-T type amphibolite facies schist and gneiss (T = 600 °C and P < 5 kbar) associated with granodioritic plutons (Tia granodiorite). White mica and biotite K-Ar ages distinguish Carboniferous subduction zone metamorphism and Permian granitic intrusions, respectively. The systematic K-Ar age mapping along a N-S traverse of the Tia Complex exhibits a gradual change. The white mica ages become younger from the lowest-grade zone (339 Ma) to the highest-grade zone (259 Ma). In contrast, Si content of muscovite changes drastically only in the highest-grade zone. The regional changes of white mica K-Ar ages and chemical compositions of micas indicate argon depletion from precursor high-P/low-T type phengitic white mica during the thermal overprinting and recrystallization by granitoids intrusions. Our new K-Ar ages and available geological data postulate a model of the eastward rollback of a subduction zone in Early Permian. The eastward shift of a subduction zone system and subsequent magmatic activities of high-Mg andesite and adakite might explain formation of S-type granitoids (Hillgrove suite) and coeval low-P/high-T type metamorphism in the Tia Complex.

  10. 49 CFR 571.210 - Standard No. 210; Seat belt assembly anchorages.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... reference point, shall extend forward from that contact point at an angle with the horizontal of not less... torso belt first contacts the uppermost torso belt anchorage.Seat belt anchorage means any component... line from the seating reference point to the nearest contact point of the belt with the anchorage shall...

  11. Steady growth or fits and starts: observing the style of and controls on carbonate crystallization in an Alpine fold and thrust belt

    NASA Astrophysics Data System (ADS)

    Lloyd, M. K.; Akker, V.; Herwegh, M.; Eiler, J. M.

    2017-12-01

    temperatures in flysch units where peak conditions exceeded 200 °C. Barring a late addition of cold, retrograde dolomite, these discrepancies indicate that carbonate recrystallization is also phase-specific, and that dolomite is uniquely resistant to recrystallization during low-grade metamorphism in major fold-and-thrust belts.

  12. The Role of the Dynamic Plasmapause on Outer Radiation Belt Electron Flux Enhancement and Three-Belt Structure Formation

    NASA Astrophysics Data System (ADS)

    Bruff, M.; Jaynes, A. N.; Zhao, H.; Malaspina, D.

    2017-12-01

    The plasmasphere is a highly dynamic toroidal region of cold, dense plasma around Earth. Plasma waves exist both inside and outside this region and can contribute to the loss and acceleration of high energy outer radiation belt electrons. Early observational studies found an apparent correlation on long time scales between the observed inner edge of the outer radiation belt and the simulated innermost plasmapause location. More recent work using high resolution Van Allen Probe satellite data has found a more complex relationship. The aim of this project was to provide a systematic study of the location and dynamics of the plasmapause compared to the MeV electrons in the outer radiation belt. We used spin-averaged electron flux data from the Relativistic Electron Proton Telescope (REPT) and density data derived from the EFW instrument on the Van Allen Probe satellites. We analyzed these data to determine the standoff distance of the location of peak electron flux of the outer belt MeV electrons from the plasmapause. We found that the location of peak flux was consistently outside but within ΔL=2.5 from the innermost location of the plasmapause at enhancement times, with an average standoff distance ΔL=1.0 +/- 0.5. This is consistent with the current model of chorus enhancement and previous observations of chorus activity. Finally, we identified "three-belt" structure events where a second outer belt formed and found a repeated pattern of plasmapause dynamics associated with specific changes in electron flux required to generate and sustain these structures. This study is significant to improving our understanding of how the plasmasphere under differing conditions can both shield Earth from or worsen the impacts of geomagnetic activity.

  13. The Southeast Asian Tin Belt

    NASA Astrophysics Data System (ADS)

    Schwartz, M. O.; Rajah, S. S.; Askury, A. K.; Putthapiban, P.; Djaswadi, S.

    1995-07-01

    The Southeast Asian Tin Belt is a north-south elongate zone 2800 km long and 400 km wide, extending from Burma (Myanmar) and Thailand to Peninsular Malaysia and the Indonesian Tin Islands. Altogether 9.6 million tonnes of tin, equivalent to 54% of the world's tin production is derived from this region. Most of the granitoids in the region can be grouped geographically into elongate provinces or belts, based on petrographic and geochronological features. - The Main Range Granitoid Province in western Peninsular Malaysia, southern Peninsular Thailand and central Thailand is almost entirely made up of biotite granite (184-230 Ma). Tin deposits associated with these granites contributed 55% of the historic tin production of Southeast Asia. - The Northern Granitoid Province in northern Thailand (0.1% of tin production) also has dominant biotite granite (200-269 Ma) but it is distinguished by abundant post-intrusion deformation. - The Eastern Granitoid Province extends from eastern Peninsular Malaysia to eastern Thailand. The Malaysian part is subdivided into the East Coast Belt (220-263 Ma), Boundary Range Belt (197-257 Ma) and Central Belt (79-219 Ma). The granitoids cover a wide compositional range from biotite granite to hornblende-biotite granite/granodiorite and diorite-gabbro. Tin deposits are associated with biotite granite in the East Coast Belt (3% of tin production). The granitoids in the other areas of the Eastern Granitoid Province are barren. - The Western Granitoid Province (22-149 Ma) in northern Peninsular Thailand, western Thailand and Burma has biotite granite and hornblende-biotite granite/granodiorite. Tin deposits are associated with biotite granite, which probably is the dominant phase (14% of tin production). The granitoids of the Indonesian Tin Islands (193-251 Ma) do not permit grouping into geographically distinct units. Main Range-type and Eastern Province-type plutons occur next to each other. Most of the tin deposits are associated with Main

  14. Seat belts and shoulder harnesses : smart protection in small airplanes.

    DOT National Transportation Integrated Search

    2004-05-01

    Seat belts alone will protect you only in minor impacts. : Using shoulder belts in small aircraft would reduce major injuries by 88% and fatalities by 20%. Shoulder belt kits are now available for most airplanes. : Proper use and installation of chil...

  15. Fold growth and drainage evolution of the Perman - Bana Bawi Anticline (Northern Iraq)

    NASA Astrophysics Data System (ADS)

    Bretis, B.; Grasemann, B.; Faber, R.; Lockhart, D.

    2009-04-01

    The Zagros fold- and thrust belt is a seismically active orogen, which is the result of the Cenozoic collision between the Eurasian and the Arabian plates. Kinematic models based on GPS networks suggest a north-south shortening between Arabia and Eurasia in the order of 2-2.5 cm/a. Most of this deformation is partitioned within the Zagros mountains in S-SW directed folding and thrusting as well as in NW-SE to N-S trending dextral strike slip faults. We investigate in this work the growth of the Perman - Bana Bawi anticlines (northeast of Erbil in Kurdistan region) by means of structural field work and tectonic geomorphology based on a geological map and ASTER remote sensing data (digital elevation model and satellite images). The Perman - Bana Bawi anticline forms a slightly S-shaped NW-SE striking fold chain over an exposed distance of more than 80 km. The dominant wavelength of the fold train is about 8 km. The backlimb dips with about 35° to the NE and the forelimb has a mean dip of about 45° towards SW. Hydrologically, there are few rivers with all-year flow conditions and therefore the dominant fluviatile erosion mainly takes place in the months with periodical precipitation, which varies between 700 and 3,000 mm/a (i.e. during the winter months). The presence of wind gaps and the pattern of deflected rivers suggest that the Perman and the Bana Bawi anticline initially developed as individual structures. The lateral growth directions are constrained by fanned drainage, which are especially in the cylindrical parts of the fold strongly overprinted by transverse rivers perpendicular to the fold axis. Although incising the same stratigraphic strata, the erosion pattern on backlimbs clearly differs from the tributary pattern on the forelimbs. The backlimbs are characterized by drainage parallel to the fold crest and asymmetric forked networks. Forelimbs are more strongly dissected by rivers with higher sinuosities with an older generation partly oblique to the

  16. Factors related to increasing safety belt use in states with safety belt use laws : second annual report to Congress, 1988.

    DOT National Transportation Integrated Search

    1989-01-01

    This report. is the second in a series of four annual reports to the : Congress on provisions of state safety belt use laws and other : programmatic factors related to increasing safety belt use levels. : The first Congressional Report reviewed what ...

  17. Interference of lithospheric folding in western Central Asia by simultaneous Indian and Arabian plate indentation

    NASA Astrophysics Data System (ADS)

    Smit, J. H. W.; Cloetingh, S. A. P. L.; Burov, E.; Tesauro, M.; Sokoutis, D.; Kaban, M.

    2013-08-01

    Large-scale intraplate deformation of the crust and the lithosphere in Central Asia as a result of the indentation of India has been extensively documented. In contrast, the impact of continental collision between Arabia and Eurasia on lithosphere tectonics in front of the main suture zone, has received much less attention. The resulting Neogene shortening and uplift of the external Zagros, Alborz, Kopeh Dagh and Caucasus Mountain belts in Iran and surrounding areas is characterised by a simultaneous onset of major topography growth at ca. 5 Ma. At the same time, subsidence accelerated in the adjacent Caspian, Turan and Amu Darya basins. We present evidence for interference of lithospheric folding patterns induced by the Arabian and Indian collision with Eurasia. Wavelengths and spatial patterns are inferred from satellite-derived topography and gravity models. The observed interference of the patterns of folding appears to be primarily the result of spatial orientation of the two indenters, differences in their convergence velocities and the thermo-mechanical structure of the lithosphere west and east of the Kugitang-Tunka Line.

  18. Geology and geochemistry of the Middle Proterozoic Eastern Ghat mobile belt and its comparison with the lower crust of the Southern Peninsular shield

    NASA Technical Reports Server (NTRS)

    Rao, M. V. Subba

    1988-01-01

    Two prominent rock suites constitute the lithology of the Eastern Ghat mobile belt: (1) the khondalite suite - the metapelites, and (2) the charnockite suite. Later intrusives include ultramafic sequences, anorthosites and granitic gneisses. The chief structural element in the rocks of the Eastern Ghats is a planar fabric (gneissosity), defined by the alignment of platy minerals like flattened quartz, garnet, sillimanite, graphite, etc. The parallelism between the foliation and the lithological layering is related to isoclinal folding. The major structural trend (axial plane foliation trend) observed in the belt is NE-SW. Five major tectonic events have been delineated in the belt. A boundary fault along the western margin of the Eastern Ghats, bordering the low grade terrain has been substantiated by recent gravity and the deep seismic sounding studies. Field evidence shows that the pyroxene granulites (basic granulites) post-date the khondalite suite, but are older than the charnockites as well as the granitic gneisses. Polyphase metamorphism, probably correlatable with different periods of deformation is recorded. The field relations in the Eastern Ghats point to the intense deformation of the terrain, apparently both before, during and after metamorphism.

  19. Evaluation of safety belt education program for employees

    DOT National Transportation Integrated Search

    1980-06-01

    This research was designed to determine the effectiveness of a nine-month safety belt educational program, utilizing various informational materials developed by NHTSA, in increasing safety belt usage among corporate employees. The materials used inc...

  20. Imaging of 2-D multichannel land seismic data using an iterative inversion-migration scheme, Naga Thrust and Fold Belt, Assam, India

    NASA Astrophysics Data System (ADS)

    Jaiswal, Priyank; Dasgupta, Rahul

    2010-05-01

    seismic data from the Naga Thrust and Fold Belt (NTFB), India, were several exploratory wells in the last decade targeting sub-thrust leads in the footwall have failed. This failure is speculatively due to incorrect depth images which are in turn attributed to incorrect velocity models that are developed using conventional methods. The 2-D seismic data in this study is acquired perpendicular to the trend of the NTFB where the outcropping hanging wall has a topographic culmination. The acquisition style is split-spread with 30 m shot and receiver spacing and a nominal fold of 90. The data are recorded with a sample interval of 2 ms. Overall the data have a moderate signal-to-noise ratio and a broad frequency bandwidth of 8-80 Hz. The seismic line contains the failed exploratory well in the central part. The final results from unified imaging (both the depth image and the corresponding velocity model) suggest presence of a triangle zone, which was previously undiscovered. Conventional imaging had falsely portrayed the triangle zone as structural high which was interpreted as an anticline. As a result, the exploratory well, meant to target the anticline, met with pressure changes which were neither expected nor explained. The unified imaging results not only explain the observations in the well but also reveal new leads in the region. The velocity model from unified imaging was also found to be adequate for frequency-domain full-waveform imaging of the hanging wall. Results from waveform inversion are further corroborated by the geological interpretation of the exploratory well.

  1. The relationship between the plasmapause and outer belt electrons

    NASA Astrophysics Data System (ADS)

    Goldstein, J.; Baker, D. N.; Blake, J. B.; De Pascuale, S.; Funsten, H. O.; Jaynes, A. N.; Jahn, J.-M.; Kletzing, C. A.; Kurth, W. S.; Li, W.; Reeves, G. D.; Spence, H. E.

    2016-09-01

    We quantify the spatial relationship between the plasmapause and outer belt electrons for a 5 day period, 15-20 January 2013, by comparing locations of relativistic electron flux peaks to the plasmapause. A peak-finding algorithm is applied to 1.8-7.7 MeV relativistic electron flux data. A plasmapause gradient finder is applied to wave-derived electron number densities >10 cm-3. We identify two outer belts. Outer belt 1 is a stable zone of >3 MeV electrons located 1-2 RE inside the plasmapause. Outer belt 2 is a dynamic zone of <3 MeV electrons within 0.5 RE of the moving plasmapause. Electron fluxes earthward of each belt's peak are anticorrelated with cold plasma density. Belt 1 decayed on hiss timescales prior to a disturbance on 17 January and suffered only a modest dropout, perhaps owing to shielding by the plasmasphere. Afterward, the partially depleted belt 1 continued to decay at the initial rate. Belt 2 was emptied out by strong disturbance-time losses but restored within 24 h. For global context we use a plasmapause test particle simulation and derive a new plasmaspheric index Fp, the fraction of a circular drift orbit inside the plasmapause. We find that the locally measured plasmapause is (for this event) a good proxy for the globally integrated opportunity for losses in cold plasma. Our analysis of the 15-20 January 2013 time interval confirms that high-energy electron storage rings can persist for weeks or even months if prolonged quiet conditions prevail. This case study must be followed up by more general study (not limited to a 5 day period).

  2. An investigation of safety belt usage and effectiveness

    DOT National Transportation Integrated Search

    1975-03-01

    This interim report contains primarily a theoretical discussion of problems of inference in studies on seat belt utilization and effectiveness. Seat belt effectiveness in accidents is initially discussed from a population paramenter point of, view. T...

  3. A new interpretation for the interference zone between the southern Brasília belt and the central Ribeira belt, SE Brazil

    NASA Astrophysics Data System (ADS)

    Trouw, Rudolph A. J.; Peternel, Rodrigo; Ribeiro, Andre; Heilbron, Mônica; Vinagre, Rodrigo; Duffles, Patrícia; Trouw, Camilo C.; Fontainha, Marcos; Kussama, Hugo H.

    2013-12-01

    In southeastern Brazil, the Neoproterozoic NNW-SSE trending southern Brasília belt is apparently truncated by the ENE-WSW central Ribeira belt. Different interpretations in the literature of the transition between these two belts motivated detailed mapping and additional age dating along the contact zone. The result is a new interpretation presented in this paper. The southern Brasília belt resulted from E-W collision between the active margin of the Paranapanema paleocontinent, on the western side, now forming the Socorro-Guaxupé Nappe, with the passive margin of the São Francisco paleocontinent on the eastern side. The collision produced an east vergent nappe stack, the Andrelândia Nappe System, along the suture. At its southern extreme the Brasília belt was thought to be cut off by a shear zone, the "Rio Jaguari mylonites", at the contact with the Embu terrane, pertaining to the Central Ribeira belt. Our detailed mapping revealed that the transition between the Socorro-Guaxupé Nappe (Brasília belt) and the Embu terrane (Ribeira belt) is not a fault but rather a gradational transition that does not strictly coincide with the Rio Jaguari mylonites. A typical Cordilleran type magmatic arc batholith of the Socorro-Guaxupé Nappe with an age of ca. 640 Ma intrudes biotite schists of the Embu terrane and the age of zircon grains from three samples of metasedimentary rocks, one to the south, one to the north and one along the mylonite zone, show a similar pattern of derivation from a Rhyacian source area with rims of 670-600 Ma interpreted as metamorphic overgrowth. We dated by LA-MC-ICPMS laser ablation (U-Pb) zircon grains from a calc-alkaline granite, the Serra do Quebra-Cangalha Batholith, located within the Embu terrane at a distance of about 40 km south of the contact with the Socorro Nappe, yielding an age of 680 ± 13 Ma. This age indicates that the Embu terrane was part of the upper plate (Socorro-Guaxupé Nappe) by this time. Detailed mapping

  4. 30 CFR 75.1108 - Approved conveyor belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Approved conveyor belts. 75.1108 Section 75.1108 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND... December 31, 2018 all conveyor belts used in underground coal mines shall be approved under Part 14. [73 FR...

  5. Radiation Belts Throughout the Solar System

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.

    2008-12-01

    The several preceding decades of deep space missions have demonstrated that the generation of planetary radiation belts is a universal phenomenon. All strongly magnetized planets show well developed radiation regions, specifically Earth, Jupiter, Saturn, Uranus, and Neptune. The similarities occur despite the tremendous differences between the planets in size, levels of magnetization, external environments, and most importantly, in the fundamental processes that power them. Some planets like Jupiter are powered overwhelmingly by planetary rotation, much like astrophysical pulsars, whereas others, like Earth and probably Uranus, are powered externally by the interplanetary environment. Uranus is a particularly interesting case in that despite the peculiarities engendered by its ecliptic equatorial spin axis orientation, its magnetosphere shows dynamical behavior similar to that of Earth as well as radiation belt populations and associated wave emissions that are perhaps more intense than expected based on Earth-derived theories. Here I review the similarities and differences between the radiation regions of radiation belts throughout the solar system. I discuss the value of the comparative approach to radiation belt physics as one that allows critical factors to be evaluated in environments that are divorced from the special complex conditions that prevail in any one environment, such as those at Earth.

  6. The Fossilized Size Distribution of the Main Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Durda, D.; Nesvorny, D.; Jedicke, R.; Morbidelli, A.

    2003-05-01

    At present, we do not understand how the main asteroid belt evolved into its current state. During the planet formation epoch, the primordial main belt (PMB) contained several Earth masses of material, enough to allow the asteroids to accrete on relatively short timescales (e.g., Weidenschilling 1977). The present-day main belt, however, only contains 5e-4 Earth masses of material (Petit et al. 2002). Constraints on this evolution come from (i) the observed fragments of differentiated asteroids, (ii) meteorites collected from numerous differentiated parent bodies, (iii) the presence of ˜ 10 prominent asteroid families, (iv) the "wavy" size-frequency distribution of the main belt, which has been shown to be a by-product of substantial collisional evolution (e.g., Durda et al. 1997), and (v) the still-intact crust of (4) Vesta. To explain the contradictions in the above constraints, we suggest the PMB evolved in this fashion: Planetesimals and planetary embryos accreted (and differentiated) in the PMB during the first few Myr of the solar system. Gravitational perturbations from these embryos dynamically stirred the main belt, enough to initiate fragmentation. When Jupiter reached its full size, some 10 Myr after the solar system's birth, its perturbations, together with those of the embryos, dynamically depleted the main belt region of ˜ 99% of its bodies. Much of this material was sent to high (e,i) orbits, where it continued to pummel the surviving main belt bodies at high impact velocities for more than 100 Myr. While some differentiated bodies in the PMB were disrupted, most were instead scattered; only small fragments from this population remain. This period of comminution and dynamical evolution in the PMB created, among other things, the main belt's wavy size distribution, such that it can be considered a "fossil" from this violent early epoch. From this time forward, however, relatively little collisional evolution has taken place in the main belt

  7. The Fossilized Size Distribution of the Main Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Durda, D.; Nesvorny, D.; Jedicke, R.; Morbidelli, A.

    2004-05-01

    The main asteroid belt evolved into its current state via two processes: dynamical depletion and collisional evolution. During the planet formation epoch, the primordial main belt (PMB) contained several Earth masses of material, enough to allow the asteroids to accrete on relatively short timescales (e.g., Weidenschilling 1977). The present-day main belt, however, only contains 5e-4 Earth masses of material (Petit et al. 2002). To explain this mass loss, we suggest the PMB evolved in the following manner: Planetesimals and planetary embryos accreted (and differentiated) in the PMB during the first few Myr of the solar system. Gravitational perturbations from these embryos dynamically stirred the main belt, enough to initiate fragmentation. When Jupiter reached its full size, some 10 Myr after the solar system's birth, its perturbations, together with those of the embryos, dynamically depleted the main belt region of > 99% of its bodies. Much of this material was sent to high (e,i) orbits, where it continued to pummel the surviving main belt bodies at high impact velocities for more than 100 Myr. While some differentiated bodies in the PMB were disrupted, most were instead scattered; only small fragments from this population remain. This period of comminution and dynamical evolution in the PMB created, among other things, the main belt's wavy size-frequency distribution, such that it can be considered a "fossil" from this violent early epoch. From this time forward, however, relatively little collisional evolution has taken place in the main belt, consistent with the surprising paucity of prominent asteroid families. We will show that the constraints provided by asteroid families and the shape of the main belt size distribution are essential to obtaining a unique solution from our model's initial conditions. We also use our model results to solve for the asteroid disruption scaling law Q*D, a critical function needed in all planet formation codes that include

  8. Belt-MRF for large aperture mirrors.

    PubMed

    Ren, Kai; Luo, Xiao; Zheng, Ligong; Bai, Yang; Li, Longxiang; Hu, Haixiang; Zhang, Xuejun

    2014-08-11

    With high-determinacy and no subsurface damage, Magnetorheological Finishing (MRF) has become an important tool in fabricating high-precision optics. But for large mirrors, the application of MRF is restricted by its small removal function and low material removal rate. In order to improve the material removal rate, shorten the processing cycle, we proposed a new MRF concept, named Belt-MRF to expand the application of MRF to large mirrors and made a prototype with a large remove function, using a belt instead of a very large polishing wheel to expand the polishing length. A series of experimental results on Silicon carbide (SiC) and BK 7 specimens and fabrication simulation verified that the Belt-MRF has high material removal rates, stable removal function and high convergence efficiency which makes it a promising technology for processing large aperture optical elements.

  9. Preventive Effects of Seat Belt on Clinical Outcomes for Road Traffic Injuries

    PubMed Central

    2015-01-01

    Proper seat belt use saves lives; however, the use rate decreased in Korea. This study aimed to measure the magnitude of the preventive effect of seat belt on case-fatality across drivers and passengers. We used the Emergency Department based Injury In-depth Surveillance (EDIIS) database from 17 EDs between 2011 and 2012. All of adult injured patients from road traffic injuries (RTI) in-vehicle of less than 10-seat van were eligible, excluding cases with unknown seat belt use and outcomes. Primary and secondary endpoints were in-hospital mortality and intracranial injury. We calculated adjusted odds ratios (AORs) of seat belt use and driving status for study outcomes adjusting for potential confounders. Among 23,698 eligible patients, 15,304 (64.6%) wore seat belts. Driver, middle aged (30-44 yr), male, daytime injured patients were more likely to use seat belts (all P < 0.001). In terms of clinical outcome, no seat belt group had higher proportions of case-fatality and intracranial injury compared to seat belt group (both P < 0.001). Compared to seat belt group, AORs (95% CIs) of no seat belt group were 10.43 (7.75-14.04) for case-fatality and 2.68 (2.25-3.19) for intracranial injury respectively. In the interaction model, AORs (95% CIs) of no seat belt use for case-fatality were 11.71 (8.45-16.22) in drivers and 5.52 (2.83-14.76) in non-driving passengers, respectively. Wearing seat belt has significantly preventive effects on case-fatality and intracranial injury. Public health efforts to increase seat belt use are needed to reduce health burden from RTIs. PMID:26713066

  10. Liquid belt radiator design study

    NASA Technical Reports Server (NTRS)

    Teagan, W. P.; Fitzgerald, K. F.

    1986-01-01

    The Liquid Belt Radiator (LBR) is an advanced concept developed to meet the needs of anticipated future space missions. A previous study documented the advantages of this concept as a lightweight, easily deployable alternative to present day space heat rejection systems. The technical efforts associated with this study concentrate on refining the concept of the LBR as well as examining the issues of belt dynamics and potential application of the LBR to intermediate and high temperature heat rejection applications. A low temperature point design developed in previous work is updated assuming the use of diffusion pump oil, Santovac-6, as the heat transfer media. Additional analytical and design effort is directed toward determining the impact of interface heat exchanger, fluid bath sealing, and belt drive mechanism designs on system performance and mass. The updated design supports the earlier result by indicating a significant reduction in system specific system mass as compared to heat pipe or pumped fluid radiator concepts currently under consideration (1.3 kg/sq m versus 5 kg/sq m).

  11. Conveyor belt care.

    PubMed

    1989-07-08

    Nurses, doctors, politicians and public have reacted to the prospect of high-volume hospital bed usage - conveyor belt care - by warning of a future-shock scenario of 'pro[Illegible Word] pea' patients whipped through dehumanising hospital treatment and promptly dumped crutchless into the community.

  12. The binary Kuiper-belt object 1998 WW31.

    PubMed

    Veillet, Christian; Parker, Joel Wm; Griffin, Ian; Marsden, Brian; Doressoundiram, Alain; Buie, Marc; Tholen, David J; Connelley, Michael; Holman, Matthew J

    2002-04-18

    The recent discovery of a binary asteroid during a spacecraft fly-by generated keen interest, because the orbital parameters of binaries can provide measures of the masses, and mutual eclipses could allow us to determine individual sizes and bulk densities. Several binary near-Earth, main-belt and Trojan asteroids have subsequently been discovered. The Kuiper belt-the region of space extending from Neptune (at 30 astronomical units) to well over 100 AU and believed to be the source of new short-period comets-has become a fascinating new window onto the formation of our Solar System since the first member object, not counting Pluto, was discovered in 1992 (ref. 13). Here we report that the Kuiper-belt object 1998 WW31 is binary with a highly eccentric orbit (eccentricity e approximately 0.8) and a long period (about 570 days), very different from the Pluto/Charon system, which was hitherto the only previously known binary in the Kuiper belt. Assuming a density in the range of 1 to 2 g cm-3, the albedo of the binary components is between 0.05 and 0.08, close to the value of 0.04 generally assumed for Kuiper-belt objects.

  13. Research on an Active Seat Belt System

    NASA Astrophysics Data System (ADS)

    Kawashima, Takeshi

    In a car crash, permanent injury can be avoided if deformation of an occupant's rib cage is maintained within the allowable value. In order to realize this condition, the occupant's seat belt tension must be instantaneously adjusted by a feedback control system. In this study, a seat belt tension control system based on the active shock control system is proposed. The semi-active control law used is derived from the sliding mode control method. One advantage of this proposed system is that it does not require a large power actuator because the seat belt tension is controlled by a brake mechanism. The effectiveness is confirmed by numerical simulation using general parameters of a human thorax and a passenger car in a collision scenario with a wall at a velocity of 100 km/h. The feasibility is then confirmed with a control experiment using a scale model of about 1/10 scale. The relative displacement of the thorax model approaches the allowable value smoothly along the control reference and settles near this value. Thus, the proposed seat belt tension control system design is established.

  14. Is the Cameron River greenstone belt allochthonous?

    NASA Technical Reports Server (NTRS)

    Kusky, T. M.

    1986-01-01

    Many tectonic models for the Slave Province, N.W.T., Canada, and for Archean granite - greenstone terranes in general, are implicitly dependent on the assumption that greenstone belt lithologies rest unconformably upon older gneissic basement. Other models require originally large separations between gneissic terranes and greenstone belts. A key question relating to the tectonics of greenstone belts is therefore the original spatial relationship between the volcanic assemblages and presumed-basement gneisses, and how this relationship has been modified by subsequent deformation. What remains unclear in these examples is the significance of the so-called later faulting of the greenstone - gneiss contacts. Where unconformities between gneisses and overlying sediments are indisputable, such as at Point Lake, the significance of faults which occur below the base of the volcanic succession also needs to be evaluated. As part of an on-going investigation aimed at answering these and other questions, the extremely well-exposed Cameron River Greenstone Belt and the Sleepy Dragon Metamorphic Complex in the vicinity of Webb Lake and Sleepy Dragon Lake was mapped.

  15. Bayesian inference of radiation belt loss timescales.

    NASA Astrophysics Data System (ADS)

    Camporeale, E.; Chandorkar, M.

    2017-12-01

    Electron fluxes in the Earth's radiation belts are routinely studied using the classical quasi-linear radial diffusion model. Although this simplified linear equation has proven to be an indispensable tool in understanding the dynamics of the radiation belt, it requires specification of quantities such as the diffusion coefficient and electron loss timescales that are never directly measured. Researchers have so far assumed a-priori parameterisations for radiation belt quantities and derived the best fit using satellite data. The state of the art in this domain lacks a coherent formulation of this problem in a probabilistic framework. We present some recent progress that we have made in performing Bayesian inference of radial diffusion parameters. We achieve this by making extensive use of the theory connecting Gaussian Processes and linear partial differential equations, and performing Markov Chain Monte Carlo sampling of radial diffusion parameters. These results are important for understanding the role and the propagation of uncertainties in radiation belt simulations and, eventually, for providing a probabilistic forecast of energetic electron fluxes in a Space Weather context.

  16. Implications of heterogeneous fracture distribution on reservoir quality; an analogue from the Torridon Group sandstone, Moine Thrust Belt, NW Scotland

    NASA Astrophysics Data System (ADS)

    Watkins, Hannah; Healy, David; Bond, Clare E.; Butler, Robert W. H.

    2018-03-01

    Understanding fracture network variation is fundamental in characterising fractured reservoirs. Simple relationships between fractures, stress and strain are commonly assumed in fold-thrust structures, inferring relatively homogeneous fracture patterns. In reality fractures are more complex, commonly appearing as heterogeneous networks at outcrop. We use the Achnashellach Culmination (NW Scotland) as an outcrop analogue to a folded tight sandstone reservoir in a thrust belt. We present fracture data is collected from four fold-thrust structures to determine how fracture connectivity, orientation, permeability anisotropy and fill vary at different structural positions. We use a 3D model of the field area, constructed using field observations and bedding data, and geomechanically restored using Move software, to determine how factors such as fold curvature and strain influence fracture variation. Fracture patterns in the Torridon Group are consistent and predictable in high strain forelimbs, however in low strain backlimbs fracture patterns are inconsistent. Heterogeneities in fracture connectivity and orientation in low strain regions do not correspond to fluctuations in strain or fold curvature. We infer that where strain is low, other factors such as lithology have a greater control on fracture formation. Despite unpredictable fracture attributes in low strain regions, fractured reservoir quality would be highest here because fractures in high strain forelimbs are infilled with quartz. Heterogeneities in fracture attribute data on fold backlimbs mean that fractured reservoir quality and reservoir potential is difficult to predict.

  17. Into the Kuiper Belt: New Horizons Post-Pluto

    NASA Astrophysics Data System (ADS)

    Harrison Parker, Alex; Spencer, John; Benecchi, Susan; Binzel, Richard; Borncamp, David; Buie, Marc; Fuentes, Cesar; Gwyn, Stephen; Kavelaars, JJ; Noll, Keith; Petit, Jean-Marc; Porter, Simon; Showalter, Mark; Stern, S. Alan; Sterner, Ray; Tholen, David; Verbiscer, Anne; Weaver, Hal; Zangari, Amanda

    2015-11-01

    New Horizons is now beyond Pluto and flying deeper into the Kuiper Belt. In the summer of 2014, a Hubble Space Telescope Large Program identified two candidate Cold Classical Kuiper Belt Objects (KBOs) that were within reach of New Horizons' remaining fuel budget. Here we present the selection of the Kuiper Belt flyby target for New Horizons' post-Pluto mission, our state of knowledge regarding this target and the potential 2019 flyby, the status of New Horizons' targeting maneuver, and prospects for near-future long-range observations of other KBOs.

  18. The small numbers of large Kuiper Belt objects

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schwamb, Megan E.; Brown, Michael E.; Fraser, Wesley C., E-mail: mschwamb@asiaa.sinica.edu.tw

    2014-01-01

    We explore the brightness distribution of the largest and brightest (m(R) < 22) Kuiper Belt Objects (KBOs). We construct a luminosity function of the dynamically excited or hot Kuiper Belt (orbits with inclinations >5°) from the very brightest to m(R) = 23. We find for m(R) ≲ 23, a single slope appears to describe the luminosity function. We estimate that ∼12 KBOs brighter than m(R) ∼ 19.5 are present in the Kuiper Belt today. With nine bodies already discovered this suggests that the inventory of bright KBOs is nearly complete.

  19. Interference of lithospheric folding in Central Asia by simultaneous Indian and Arabian plate indentation

    NASA Astrophysics Data System (ADS)

    Smit, J. H. W.; Cloetingh, S. A. P. L.; Burov, E.; Sokoutis, D.; Kaban, M.; Tesauro, M.; Burg, J.-P.

    2012-04-01

    Although large-scale folding of the crust and the lithosphere in Central Asia as a result of the indentation of India has been extensively documented, the impact of continental collision between Arabia and Eurasia has been largely overlooked. The resulting Neogene shortening and uplift of the Zagros, Albors, Kopet Dagh and Kaukasus mountain belts in Iran and surrounding areas is characterised by a simultaneous onset of major topography growth at ca. 5 Ma. At the same time, the adjacent Caspian, Turan and Amu Darya basins underwent an acceleration in subsidence. It is common knowledge that waves with different orientations will interfere with each other. Folding, by its nature similar to a standing wave, is not likely to be an exception. We demonstrate that collision of the Eurasian plate with the Arabian and Indian plates generates folding of the Eurasian lithosphere in two different directions and that interaction between both generates characteristic interference patterns that can be recognised from the regional gravity signal. We present evidence for interference of lithospheric folding patterns induced by Arabian and Indian collision with Eurasia. Wavelengths (from 50 to 250 km) and spatial patterns are inferred from satellite-derived topography and gravity models and attest for rheologically stratified lithosphere with relatively strong mantle rheology (thickness of strong mechanical core on the order of 40-50 km) and less competent crust (thickness of the mechanical core on the order of 10-15 km). The observations are compared with inferences from numerical and analogue tectonic experiments for a quantitative assessment of factors such as lithosphere rheology and stratification, lateral variations in lithosphere strength, thermo-mechanical age and distance to the plate boundary on the activity of folding as a mechanism of intra-plate deformation in this area. The observed interference of the patterns of folding appears to be primarily the result of spatial

  20. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Technical Reports Server (NTRS)

    Dewit, M. J.

    1986-01-01

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  1. Predicting repeat protein folding kinetics from an experimentally determined folding energy landscape

    PubMed Central

    Street, Timothy O; Barrick, Doug

    2009-01-01

    The Notch ankyrin domain is a repeat protein whose folding has been characterized through equilibrium and kinetic measurements. In previous work, equilibrium folding free energies of truncated constructs were used to generate an experimentally determined folding energy landscape (Mello and Barrick, Proc Natl Acad Sci USA 2004;101:14102–14107). Here, this folding energy landscape is used to parameterize a kinetic model in which local transition probabilities between partly folded states are based on energy values from the landscape. The landscape-based model correctly predicts highly diverse experimentally determined folding kinetics of the Notch ankyrin domain and sequence variants. These predictions include monophasic folding and biphasic unfolding, curvature in the unfolding limb of the chevron plot, population of a transient unfolding intermediate, relative folding rates of 19 variants spanning three orders of magnitude, and a change in the folding pathway that results from C-terminal stabilization. These findings indicate that the folding pathway(s) of the Notch ankyrin domain are thermodynamically selected: the primary determinants of kinetic behavior can be simply deduced from the local stability of individual repeats. PMID:19177351

  2. Greenstone belts: Their boundaries, surrounding rock terrains and interrelationships

    NASA Technical Reports Server (NTRS)

    Percival, J. A.; Card, K. D.

    1986-01-01

    Greenstone belts are an important part of the fragmented record of crustal evolution, representing samples of the magmatic activity that formed much of the Earth's crust. Most belts developed rapidly, in less than 100 Ma, leaving large gaps in the geological record. Surrounding terrains provide information on the context of greenstone belts. The effects of tectonic setting, structural geometry and evolution, associated plutonic activity and sedimentation are discussed.

  3. The relationship between the plasmapause and outer belt electrons

    DOE PAGES

    Goldstein, J.; Baker, D. N.; Blake, J. B.; ...

    2016-09-01

    Here, we quantify the spatial relationship between the plasmapause and outer belt electrons for a 5 day period, 15–20 January 2013, by comparing locations of relativistic electron flux peaks to the plasmapause. A peak-finding algorithm is applied to 1.8–7.7 MeV relativistic electron flux data. A plasmapause gradient finder is applied to wave-derived electron number densities >10 cm –3. We identify two outer belts. Outer belt 1 is a stable zone of >3 MeV electrons located 1–2 R E inside the plasmapause. Outer belt 2 is a dynamic zone of <3 MeV electrons within 0.5 R E of the moving plasmapause.more » Electron fluxes earthward of each belt's peak are anticorrelated with cold plasma density. Belt 1 decayed on hiss timescales prior to a disturbance on 17 January and suffered only a modest dropout, perhaps owing to shielding by the plasmasphere. Afterward, the partially depleted belt 1 continued to decay at the initial rate. Belt 2 was emptied out by strong disturbance-time losses but restored within 24 h. For global context we use a plasmapause test particle simulation and derive a new plasmaspheric index F p, the fraction of a circular drift orbit inside the plasmapause. We find that the locally measured plasmapause is (for this event) a good proxy for the globally integrated opportunity for losses in cold plasma. Our analysis of the 15–20 January 2013 time interval confirms that high-energy electron storage rings can persist for weeks or even months if prolonged quiet conditions prevail. This case study must be followed up by more general study (not limited to a 5 day period).« less

  4. Compliance with seat belt use in Benin City, Nigeria.

    PubMed

    Iribhogbe, Pius Ehiawaguan; Osime, Clement Odigie

    2008-01-01

    Trauma is a major cause of death and disability worldwide. A quarter of all fatalities due to injury occur due to road traffic crashes with 90% of the fatalities occurring in low- and medium-income countries. Poor compliance with the use of seat belts is a problem in many developing countries. The aim of this study was to evaluate the level of seatbelt compliance in motor vehicles in Benin City, Nigeria. A five-day, observational study was conducted in strategic locations in Benin City. The compliance rates of drivers, front seat passengers, and rear seat passengers in the various categories of vehicles were evaluated, and the data were subjected to statistical processing using the Program for Epidemiology. A total of 369 vehicles were observed. This consisted of 172 private cars, 64 taxis, 114 buses, 15 trucks, and four other vehicles. The seat belt compliance rate for drivers was 52.3%, front seat passengers 18.4%, and rear seat passengers 6.1%. Drivers of all categories of vehicles were more likely to use the seat belt compared to front seat passengers (p = 0.000) and rear seat passengers (p = 0.000). Drivers of private cars were more likely to use seat belts compared to taxi drivers (p = 0.000) and bus drivers (p = 0.000). Front seat passengers in private cars were more likely to use the seat belt compared to front seat passengers in taxis (p = 0.000) and buses (p = 0.000). Rear seat passengers in private cars also were more likely to use seat belts compared to rear seat passengers in taxis (p = 0.000) and buses (p = 0.000). Compliance with seat belt use in Benin City is low. Legislation, educational campaigns, and enforcement of seat belt use are needed.

  5. Deconstructing the conveyor belt.

    PubMed

    Lozier, M Susan

    2010-06-18

    For the past several decades, oceanographers have embraced the dominant paradigm that the ocean's meridional overturning circulation operates like a conveyor belt, transporting cold waters equatorward at depth and warm waters poleward at the surface. Within this paradigm, the conveyor, driven by changes in deepwater production at high latitudes, moves deep waters and their attendant properties continuously along western boundary currents and returns surface waters unimpeded to deepwater formation sites. A number of studies conducted over the past few years have challenged this paradigm by revealing the vital role of the ocean's eddy and wind fields in establishing the structure and variability of the ocean's overturning. Here, we review those studies and discuss how they have collectively changed our view of the simple conveyor-belt model.

  6. The levantine amber belt

    NASA Astrophysics Data System (ADS)

    Nissenbaum, A.; Horowitz, A.

    1992-02-01

    Amber, a fossil resin, is found in Early Cretaceous sanstones and fine clastics in Lebanon, Jordan, and Israel. The term "Levantine amber belt" is coined for this amber-containing sediment belt. The amber occurs as small nodules of various colors and frequently contains inclusions of macro- and microorganisms. The Lebanese amber contains Lepidoptera and the amber from southern Israel is rich in fungal remains. The source of the amber, based on geochemical and palynological evidence, is assumed to be from a conifer belonging to the Araucariaceae. The resins were produced by trees growing in a tropical near shore environment. The amber was transported into small swamps and was preserved there together with lignite. Later reworking of those deposits resulted in redeposition of the amber in oxidized sandstones.

  7. Papers on adult seat belts : effectiveness and use

    DOT National Transportation Integrated Search

    1988-06-01

    The eight papers in this volume describe analyses of the : effectiveness and use of adult seat belts, based on traffic : accident data. All eight were written between January 1984 and : May 1988. The topics addressed include front seat belt : effecti...

  8. Papers on adult seat belts--effectiveness and use

    DOT National Transportation Integrated Search

    1988-06-01

    The eight papers in the volume describe analyses of the effectiveness and use of adult seat belts, based on traffic accident data. All eight were written between January 1984 and May 1988. The topics addressed include front seat belt effectiveness (e...

  9. Understanding Quaternions and the Dirac Belt Trick

    ERIC Educational Resources Information Center

    Staley, Mark

    2010-01-01

    The Dirac belt trick is often employed in physics classrooms to show that a 2n rotation is not topologically equivalent to the absence of rotation whereas a 4n rotation is, mirroring a key property of quaternions and their isomorphic cousins, spinors. The belt trick can leave the student wondering if a real understanding of quaternions and spinors…

  10. Driver hand-held mobile phone use and safety belt use.

    PubMed

    Eby, David W; Vivoda, Jonathon M

    2003-11-01

    The purposes of the study were to identify hand-held mobile phone use trends for Michigan and to compare safety belt use between users and nonusers. Mobile phone and safety belt use was investigated by a direct observation survey of drivers at intersections in Michigan. Data were weighted to calculate mobile phone use and safety belt use rates statewide. The study showed 2.7% of Michigan drivers were using a mobile phone at any given daylight time. Safety belt use of current mobile phone users was significantly lower than those not using mobile phones.

  11. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Seats, safety belts, and shoulder harnesses... § 121.311 Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane unless... belt and shoulder harness that meets the applicable requirements specified in § 25.785 of this chapter...

  12. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Seats, safety belts, and shoulder harnesses... § 121.311 Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane unless... belt and shoulder harness that meets the applicable requirements specified in § 25.785 of this chapter...

  13. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Seats, safety belts, and shoulder harnesses... § 121.311 Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane unless... belt and shoulder harness that meets the applicable requirements specified in § 25.785 of this chapter...

  14. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Seats, safety belts, and shoulder harnesses... § 121.311 Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane unless... belt and shoulder harness that meets the applicable requirements specified in § 25.785 of this chapter...

  15. 14 CFR 121.311 - Seats, safety belts, and shoulder harnesses.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Seats, safety belts, and shoulder harnesses... § 121.311 Seats, safety belts, and shoulder harnesses. (a) No person may operate an airplane unless... belt and shoulder harness that meets the applicable requirements specified in § 25.785 of this chapter...

  16. Characteristics and conditions of teenage safety belt use

    DOT National Transportation Integrated Search

    1997-07-01

    Safety belt use was observed for 7,384 vehicle occupants estimated as 15-19 years old in four states - Texas, Virginia, Idaho, and Mississippi. Age and other pertinent information was obtained from 2,330 teen occupants. Belt use ranged from 19.5% in ...

  17. Quaternary Expression of Northern Great Valley Faults and Folds: Accommodating North-South Contraction between the Sierran Microplate and Oregon Block

    NASA Astrophysics Data System (ADS)

    Angster, S.; Sawyer, T. L.; Wesnousky, S. G.

    2015-12-01

    The Northern California Shear Zone accommodates North American intraplate right-lateral transpressional shear driven by the relative motion of the northwest translating Sierran microplate. Within this zone, between the latitudes of 400 and 420, 1 - 4 mm/yr of north-south geodetic contraction is observed and for the most part remains geologically unaccounted for. We are investigating the Quaternary expression of transpressional shear localized at the northern end of the Sierra Nevada and Great Valley to evaluate both the recency and rates of deformation across structures that may be accommodating the contractional deformation suggested in geodetic studies. The northeast trending Inks Creek fold belt north of Red Bluff, CA consists of anticline-syncline pairs and dome structures that appear optimally oriented to accommodate northwest crustal shortening. The folds plunge to the southwest where they are incised and deflect the course of the Sacramento River. We will present preliminary geomorphic maps of fluvial terraces and drainage patterns associated with the folds constructed with standard field mapping techniques and aided by airborne LiDAR. It is anticipated that dating of deformed terrace strandlines with radiocarbon and OSL techniques holds the potential to quantify the lateral and vertical propagation rates of fold growth, as well as, constrain rates of regional contractional deformation.

  18. Participative education for children: an effective approach to increase safety belt use.

    PubMed Central

    Lehman, G R; Geller, E S

    1990-01-01

    Vehicle license plate numbers and the shoulder belt use of front-seat occupants were recorded unobtrusively when parents delivered and picked up their children at a Montessori school during 5-day baseline, intervention, and follow-up phases. Practicing and presenting a 15-min safety belt skit increased the safety belt use of those 6 kindergarten children who were not consistent belt users 82% above their preintervention baseline belt use mean of 47%. The belt use of these children's parents (who watched the skit) increased to 56% above their baseline mean of 36%. Also, mean safety belt use of 11 primary school children who watched the skit increased to 70% above their baseline of 28%. Mean safety belt use of the older children's parents (who didn't watch the skit) remained at approximately 31% for each phase, regardless of whether children were vehicle occupants. The follow-up observations, taken 3 months after the intervention, revealed 60% belt use for the kindergartners, 48% for the primary school children, and 71% for the kindergartners' parents when the children were vehicle occupants but only 30% when the parents were driving alone. PMID:2373658

  19. Radiation belt seed population and its association with the relativistic electron dynamics: A statistical study: Radiation Belt Seed Population

    DOE PAGES

    Tang, C. L.; Wang, Y. X.; Ni, B.; ...

    2017-05-19

    Using the Van Allen Probes data, we study the radiation belt seed population and it associated with the relativistic electron dynamics during 74 geomagnetic storm events. Based on the flux changes of 1 MeV electrons before and after the storm peak, these storm events are divided into two groups of “non-preconditioned” and “preconditioned”. The statistical study shows that the storm intensity is of significant importance for the distribution of the seed population (336 keV electrons) in the outer radiation belt. However, substorm intensity can also be important to the evolution of the seed population for some geomagnetic storm events. Formore » non-preconditioned storm events, the correlation between the peak fluxes and their L-shell locations of the seed population and relativistic electrons (592 keV, 1.0 MeV, 1.8 MeV, and 2.1 MeV) is consistent with the energy-dependent dynamic processes in the outer radiation belt. For preconditioned storm events, the correlation between the features of the seed population and relativistic electrons is not fully consistent with the energy-dependent processes. It is suggested that the good correlation between the radiation belt seed population and ≤1.0 MeV electrons contributes to the prediction of the evolution of ≤1.0 MeV electrons in the Earth’s outer radiation belt during periods of geomagnetic storms.« less

  20. Radiation belt seed population and its association with the relativistic electron dynamics: A statistical study: Radiation Belt Seed Population

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tang, C. L.; Wang, Y. X.; Ni, B.

    Using the Van Allen Probes data, we study the radiation belt seed population and it associated with the relativistic electron dynamics during 74 geomagnetic storm events. Based on the flux changes of 1 MeV electrons before and after the storm peak, these storm events are divided into two groups of “non-preconditioned” and “preconditioned”. The statistical study shows that the storm intensity is of significant importance for the distribution of the seed population (336 keV electrons) in the outer radiation belt. However, substorm intensity can also be important to the evolution of the seed population for some geomagnetic storm events. Formore » non-preconditioned storm events, the correlation between the peak fluxes and their L-shell locations of the seed population and relativistic electrons (592 keV, 1.0 MeV, 1.8 MeV, and 2.1 MeV) is consistent with the energy-dependent dynamic processes in the outer radiation belt. For preconditioned storm events, the correlation between the features of the seed population and relativistic electrons is not fully consistent with the energy-dependent processes. It is suggested that the good correlation between the radiation belt seed population and ≤1.0 MeV electrons contributes to the prediction of the evolution of ≤1.0 MeV electrons in the Earth’s outer radiation belt during periods of geomagnetic storms.« less

  1. Vega: Two Belts and the Possibility of Planets

    NASA Image and Video Library

    2013-01-08

    In this diagram, the Vega system, which was already known to have a cooler outer belt of comets orange, is compared to our solar system with its asteroid and Kuiper belts. The ring of warm, rocky debris was detected using NASA Spitzer Space Telescope,

  2. Prioritizing Safety with Seat Belts: The Unanswered Question.

    ERIC Educational Resources Information Center

    Farrell, Elaine

    1987-01-01

    Reviews conflicting federal and state developments (including liability lawsuits) involving seat belt installation on school buses. The National Highway Traffic Safety Administration and the National Transportation Safety Board differ on this issue, and several states are considering seat belt legislation or crashworthiness studies. Hints are…

  3. Increasing safety belt use by high risk drivers

    DOT National Transportation Integrated Search

    1991-04-01

    The objectives of this study were to: 1) identify groups of non-belt users who are most likely to become involved in highway crashes and 2) develop and test communication programs designed to increase safety belt use by one or more of these groups. T...

  4. Angle stations in or for endless conveyor belts

    DOEpatents

    Steel, Alan

    1987-04-07

    In an angle station for an endless conveyor belt, there are presented to each incoming run of the belt stationary curved guide members (18, 19) of the shape of a major segment of a right-circular cylinder and having in the part-cylindrical portion (16 or 17) thereof rectangular openings (15) arranged in parallel and helical paths and through which project small freely-rotatable rollers (14), the continuously-changing segments of the curved surfaces of which projecting through said openings (15) are in attitude to change the direction of travel of the belt (13) through 90.degree. during passage of the belt about the part-cylindrical portion (16 or 17) of the guide member (18 or 19). The rectangular openings (15) are arranged with their longer edges lengthwise of the diagonals representing the mean of the helix but with those of a plurality of the rows nearest to each end of the part-cylindrical portion (16 or 17) slightly out of axial symmetry with said diagonals, being slightly inclined in a direction about the intersections (40) of the diagonals of the main portion of the openings, to provide a "toe-in" attitude in relation to the line of run of the endless conveyor belt.

  5. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-12-01

    Trapped by Earth's magnetic field far above the planet's surface, the energetic particles that fill the radiation belts are a sign of the Sun's influence and a threat to our technological future. In the AGU monograph Dynamics of the Earth's Radiation Belts and Inner Magnetosphere, editors Danny Summers, Ian R. Mann, Daniel N. Baker, and Michael Schulz explore the inner workings of the magnetosphere. The book reviews current knowledge of the magnetosphere and recent research results and sets the stage for the work currently being done by NASA's Van Allen Probes (formerly known as the Radiation Belt Storm Probes). In this interview, Eos talks to Summers about magnetospheric research, whistler mode waves, solar storms, and the effects of the radiation belts on Earth.

  6. The fossilized size distribution of the main asteroid belt

    NASA Astrophysics Data System (ADS)

    Bottke, William F.; Durda, Daniel D.; Nesvorný, David; Jedicke, Robert; Morbidelli, Alessandro; Vokrouhlický, David; Levison, Hal

    2005-05-01

    Planet formation models suggest the primordial main belt experienced a short but intense period of collisional evolution shortly after the formation of planetary embryos. This period is believed to have lasted until Jupiter reached its full size, when dynamical processes (e.g., sweeping resonances, excitation via planetary embryos) ejected most planetesimals from the main belt zone. The few planetesimals left behind continued to undergo comminution at a reduced rate until the present day. We investigated how this scenario affects the main belt size distribution over Solar System history using a collisional evolution model (CoEM) that accounts for these events. CoEM does not explicitly include results from dynamical models, but instead treats the unknown size of the primordial main belt and the nature/timing of its dynamical depletion using innovative but approximate methods. Model constraints were provided by the observed size frequency distribution of the asteroid belt, the observed population of asteroid families, the cratered surface of differentiated Asteroid (4) Vesta, and the relatively constant crater production rate of the Earth and Moon over the last 3 Gyr. Using CoEM, we solved for both the shape of the initial main belt size distribution after accretion and the asteroid disruption scaling law QD∗. In contrast to previous efforts, we find our derived QD∗ function is very similar to results produced by numerical hydrocode simulations of asteroid impacts. Our best fit results suggest the asteroid belt experienced as much comminution over its early history as it has since it reached its low-mass state approximately 3.9-4.5 Ga. These results suggest the main belt's wavy-shaped size-frequency distribution is a "fossil" from this violent early epoch. We find that most diameter D≳120 km asteroids are primordial, with their physical properties likely determined during the accretion epoch. Conversely, most smaller asteroids are byproducts of fragmentation

  7. Seat-belt message and the law?

    PubMed

    Sengupta, S K; Patil, N G; Law, G

    1989-09-01

    This paper attempts to draw together available information on the use of seat belts, one of the most important safety devices for a person in a car. Considering the high rate of mortality and morbidity due to road traffic accidents in Papua New Guinea the authors strongly feel that seat-belt usage should be made compulsory. When one looks at the history of the implementation of such a successful countermeasure in other countries it seems that legislation is the only answer.

  8. 3D Reconstruction of geological structures based on remote sensing data: example from Anaran anticline, Lurestan province, Zagros folds and thrust belt, Iran.

    NASA Astrophysics Data System (ADS)

    Snidero, M.; Amilibia, A.; Gratacos, O.; Muñoz, J. A.

    2009-04-01

    This work presents a methodological workflow for the 3D reconstruction of geological surfaces at regional scale, based on remote sensing data and geological maps. This workflow has been tested on the reconstruction of the Anaran anticline, located in the Zagros Fold and Thrust belt mountain front. The used remote sensing data-set is a combination of Aster and Spot images as well as a high resolution digital elevation model. A consistent spatial positioning of the complete data-set in a 3D environment is necessary to obtain satisfactory results during the reconstruction. The Aster images have been processed by the Optimum Index Factor (OIF) technique, in order to facilitate the geological mapping. By pansharpening of the resulting Aster image with the SPOT panchromatic one we obtain the final high-resolution image used during the 3D mapping. Structural data (dip data) has been acquired through the analysis of the 3D mapped geological traces. Structural analysis of the resulting data-set allows us to divide the structure in different cylindrical domains. Related plunge lines orientation has been used to project data along the structure, covering areas with little or no information. Once a satisfactory dataset has been acquired, we reconstruct a selected horizon following the dip-domain concept. By manual editing, the obtained surfaces have been adjusted to the mapped geological limits as well as to the modeled faults. With the implementation of the Discrete Smooth Interpolation (DSI) algorithm, the final surfaces have been reconstructed along the anticline. Up to date the results demonstrate that the proposed methodology is a powerful tool for 3D reconstruction of geological surfaces when working with remote sensing data, in very inaccessible areas (eg. Iran, China, Africa). It is especially useful in semiarid regions where the structure strongly controls the topography. The reconstructed surfaces clearly show the geometry in the different sectors of the structure

  9. Magnetic refrigeration apparatus with belt of ferro or paramagnetic material

    DOEpatents

    Barclay, John A.; Stewart, Walter F.; Henke, Michael D.; Kalash, Kenneth E.

    1987-01-01

    A magnetic refrigerator operating in the 12 to 77K range utilizes a belt which carries ferromagnetic or paramagnetic material and which is disposed in a loop which passes through the center of a solenoidal magnet to achieve cooling. The magnetic material carried by the belt, which can be blocks in frames of a linked belt, can be a mixture of substances with different Curie temperatures arranged such that the Curie temperatures progressively increase from one edge of the belt to the other. This magnetic refrigerator can be used to cool and liquefy hydrogen or other fluids.

  10. Magnetic refrigeration apparatus with belt of ferro or paramagnetic material

    DOEpatents

    Barclay, J.A.; Stewart, W.F.; Henke, M.D.; Kalash, K.E.

    1986-04-03

    A magnetic refrigerator operating in the 12 to 77 K range utilizes a belt which carries ferromagnetic or paramagnetic material and which is disposed in a loop which passes through the center of a solenoidal magnet to achieve cooling. The magnetic material carried by the belt, which can be blocks in frames of a linked belt, can be a mixture of substances with different Curie temperatures arranged such that the Curie temperatures progressively increase from one edge of the belt to the other. This magnetic refrigerator can be used to cool and liquefy hydrogen or other fluids.

  11. The crustal structure of Ellesmere Island, Arctic Canada—teleseismic mapping across a remote intraplate orogenic belt

    NASA Astrophysics Data System (ADS)

    Schiffer, Christian; Stephenson, Randell; Oakey, Gordon N.; Jacobsen, Bo H.

    2016-03-01

    Ellesmere Island in Arctic Canada displays a complex geological evolution. The region was affected by two distinct orogenies, the Palaeozoic Ellesmerian orogeny (the Caledonian equivalent in Arctic Canada and Northern Greenland) and the Palaeogene Eurekan orogeny, related to the opening of Baffin Bay and the consequent convergence of the Greenland plate. The details of this complex evolution and the present-day deep structure are poorly constrained in this remote area and deep geophysical data are sparse. Receiver function analysis of seven temporary broad-band seismometers of the Ellesmere Island Lithosphere Experiment complemented by two permanent stations provides important data on the crustal velocity structure of Ellesmere Island. The crustal expression of the northernmost tectonic block of Ellesmere Island (˜82°-83°N), Pearya, which was accreted during the Ellesmerian orogeny, is similar to that at the southernmost part, which is part of the Precambrian Laurentian (North America-Greenland) craton. Both segments have thick crystalline crust (˜35-36 km) and comparable velocity-depth profiles. In contrast, crustal thickness in central Ellesmere Island decreases from ˜24-30 km in the Eurekan fold and thrust belt (˜79.7°-80.6°N) to ˜16-20 km in the Hazen Stable Block (HSB; ˜80.6°-81.4°N) and is covered by a thick succession of metasediments. A deep crustal root (˜48 km) at ˜79.6°N is interpreted as cratonic crust flexed beneath the Eurekan fold and thrust belt. The Carboniferous to Palaeogene sedimentary succession of the Sverdrup Basin is inferred to be up to 1-4 km thick, comparable to geologically-based estimates, near the western margin of the HSB.

  12. The Lewis thrust fault and related structures in the Disturbed Belt, northwestern Montana

    USGS Publications Warehouse

    Mudge, Melville Rhodes; Earhart, Robert L.

    1980-01-01

    The classical Lewis thrust fault in Glacier National Park has now been mapped 125 km south of the park to Steamboat Mountain, where the trace dies out in folded middle Paleozoic rocks. The known length of the fault is 452 km, extending northward from Steamboat Mountain to a point 225 km into Canada, where the fault also dies out in Paleozoic rocks. At the south end, the surface expression of the Lewis thrust begins in a shear zone in folded Mississippian rocks. To the north, the thrust progressively cuts downsection into Proterozoic Y (Belt) rocks near Glacier National Park. Displacement on the Lewis plate increases northward from approximately 3 km on an easterly trending hinge line at the West Fork of the Sun River to a postulated 65 km at the southern edge of the park, where the stratigraphic throw is about 6,500 m. Present data indicate the thrust formed during very late Paleocene to very early Eocene time. The Lewis thrust and related structures, the Hoadley thrust and the Continental Divide syncline, probably formed concurrently under the same stress field. The northern limit of the trace of the Hoadley thrust is within the lower portion of the Lewis plate, about 28 km north of where the Lewis thrust develops, and the Hoadley extends for at least 125 km to the south. Displacement of the Hoadley increases southward from about 1 km at the hinge line to an inferred 70 km near its known southern extent. If our inference is correct, the Hoadley is nearly the southern mirror image of the Lewis to the north. The Continental Divide syncline, a doubly plunging, broad, northerly trending open fold that is about 120 km long, is a major fold within the Lewis plate.

  13. Folding Beauties

    ERIC Educational Resources Information Center

    Berman, Leah Wrenn

    2006-01-01

    This article has its genesis in an MAA mini-course on origami, where a way to get a parabola by folding paper was presented. This article discusses the methods and mathematics of other curves obtained by paper-folding.

  14. 45. July 1974. BLACKSMITH SHOP, VIEW LOOKING NORTHEAST, SHOWING BELT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    45. July 1974. BLACKSMITH SHOP, VIEW LOOKING NORTHEAST, SHOWING BELT CHASE FOR TWO BELTS FROM THE BASEMENT, THE W. E. & J. BARNES CO. DRILL PRESS, AND THE DRILL PRESS USED FOR REAMING. THE BELT PASSING THROUGH THE WALL POWERS THE SANDER IN THE WOOD SHOP. - Gruber Wagon Works, Pennsylvania Route 183 & State Hill Road at Red Bridge Park, Bernville, Berks County, PA

  15. New Quality Standards of Testing Idlers for Highly Effective Belt Conveyors

    NASA Astrophysics Data System (ADS)

    Król, Robert; Gladysiewicz, Lech; Kaszuba, Damian; Kisielewski, Waldemar

    2017-12-01

    The paper presents result of research and analyses carried out into the belt conveyors idlers’ rotational resistance which is one of the key factor indicating the quality of idlers. Moreover, idlers’ rotational resistance is important factor in total resistance to motion of belt conveyor. The evaluation of the technical condition of belt conveyor idlers is carried out in accordance with actual national and international standards which determine the methodology of measurements and acceptable values of measured idlers’ parameters. Requirements defined by the standards, which determine the suitability of idlers to a specific application, despite the development of knowledge on idlers and quality of presently manufactured idlers maintain the same level of parameters values over long periods of time. Nowadays the need to implement new, efficient and economically justified solution for belt conveyor transportation systems characterized by long routes and energy-efficiency is often discussed as one of goals in belt conveyors’ future. One of the basic conditions for achieving this goal is to use only carefully selected idlers with low rotational resistance under the full range of operational loads and high durability. Due to this it is necessary to develop new guidelines for evaluation of the technical condition of belt conveyor idlers in accordance with actual standards and perfecting of existing and development of new methods of idlers testing. The changes in particular should concern updating of values of parameters used for evaluation of the technical condition of belt conveyor idlers in relation to belt conveyors’ operational challenges and growing demands in terms of belt conveyors’ energy efficiency.

  16. The Harang discontinuity in auroral belt ionospheric currents.

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1972-01-01

    Discussion of the nature of a discontinuity in the ionospheric current of the auroral belt whose existence was suggested by Harang in 1946. Convection characteristics, time variability, and current continuity in the auroral belt are considered in a context of observations and arguments supporting the reality of Harang's discontinuity.

  17. Distribution of Dust from Kuiper Belt Objects

    NASA Technical Reports Server (NTRS)

    Gorkavyi, Nick N.; Ozernoy, Leonid; Taidakova, Tanya; Mather, John C.; Fisher, Richard (Technical Monitor)

    2000-01-01

    Using an efficient computational approach, we have reconstructed the structure of the dust cloud in the Solar system between 0.5 and 100 AU produced by the Kuiper belt objects. Our simulations offer a 3-D physical model of the 'kuiperoidal' dust cloud based on the distribution of 280 dust particle trajectories produced by 100 known Kuiper belt objects; the resulting 3-D grid consists of 1.9 x 10' cells containing 1.2 x 10" particle positions. The following processes that influence the dust particle dynamics are taken into account: 1) gravitational scattering on the eight planets (neglecting Pluto); 2) planetary resonances; 3) radiation pressure; and 4) the Poynting-Robertson (P-R) and solar wind drags. We find the dust distribution highly non-uniform: there is a minimum in the kuiperoidal dust between Mars and Jupiter, after which both the column and number densities of kuiperoidal dust sharply increase with heliocentric distance between 5 and 10 AU, and then form a plateau between 10 and 50 AU. Between 25 and 45 AU, there is an appreciable concentration of kuiperoidal dust in the form of a broad belt of mostly resonant particles associated with Neptune. In fact, each giant planet possesses its own circumsolar dust belt consisting of both resonant and gravitationally scattered particles. As with the cometary belts simulated in our related papers, we reveal a rich and sophisticated resonant structure of the dust belts containing families of resonant peaks and gaps. An important result is that both the column and number dust density are more or less flat between 10 and 50 AU, which might explain the surprising data obtained by Pioneers 10 & 11 and Voyager that the dust number density remains approximately distance-independent in this region. The simulated kuiperoidal dust, in addition to asteroidal and cometary dust, might represent a third possible source of the zodiacal light in the Solar system.

  18. Design and implementation of an intelligent belt system using accelerometer.

    PubMed

    Liu, Botong; Wang, Duo; Li, Sha; Nie, Xuhui; Xu, Shan; Jiao, Bingli; Duan, Xiaohui; Huang, Anpeng

    2015-01-01

    Activity monitor systems are increasing used recently. They are important for athletes and casual users to manage physical activity during daily exercises. In this paper, we use a triaxial accelerometer to design and implement an intelligent belt system, which can detect the user's step and flapping motion. In our system, a wearable intelligent belt is worn on the user's waist to collect activity acceleration signals. We present a step detection algorithm to detect real-time human step, which has high accuracy and low complexity. In our system, an Android App is developed to manage the intelligent belt. We also propose a protocol, which can guarantee data transmission between smartphones and wearable belt effectively and efficiently. In addition, when users flap the belt in emergency, the smartphone will receive alarm signal sending by the belt, and then notifies the emergency contact person, which can be really helpful for users in danger. Our experiment results show our system can detect physical activities with high accuracy (overall accuracy of our algorithm is above 95%) and has an effective alarm subsystem, which is significant for the practical use.

  19. Cost-benefit analysis of safety belts in Texas school buses.

    PubMed

    Begley, C E; Biddle, A K

    1988-01-01

    Although safety belts have been shown to reduce the risk of serious injury or death in automobile crashes, evidence of their effectiveness in school buses is uncertain. In this paper, the potential costs and benefits of mandatory safety belts in Texas school buses are estimated, based on the assumption that their effectiveness is less than or equal to rear seatbelt effectiveness in autos. Costs are based on both retrofitting old buses with belts and installing them in new buses. Benefits include the direct and indirect (forgone earnings) cost-savings from preventable injuries and fatalities. Results indicate that a law mandating safety belts in Texas school buses would not be cost-beneficial. Annual benefits would exceed the annual costs of installing belts in new school buses. However, the benefits would not be large enough to compensate for the five-year costs associated with retrofitting old buses.

  20. Cost-benefit analysis of safety belts in Texas school buses.

    PubMed Central

    Begley, C E; Biddle, A K

    1988-01-01

    Although safety belts have been shown to reduce the risk of serious injury or death in automobile crashes, evidence of their effectiveness in school buses is uncertain. In this paper, the potential costs and benefits of mandatory safety belts in Texas school buses are estimated, based on the assumption that their effectiveness is less than or equal to rear seatbelt effectiveness in autos. Costs are based on both retrofitting old buses with belts and installing them in new buses. Benefits include the direct and indirect (forgone earnings) cost-savings from preventable injuries and fatalities. Results indicate that a law mandating safety belts in Texas school buses would not be cost-beneficial. Annual benefits would exceed the annual costs of installing belts in new school buses. However, the benefits would not be large enough to compensate for the five-year costs associated with retrofitting old buses. PMID:3140273

  1. Kuiper Belt Objects Along the Pluto-Express Path

    NASA Technical Reports Server (NTRS)

    Jewitt, David (Principal Investigator)

    1997-01-01

    The science objective of this work is to identify objects in the Kuiper Belt which will, in the 5 years following Pluto encounter, be close to the flight path of NASA's Pluto Express. Our hope is that we will find a Kuiper Belt object or objects close enough that a spacecraft flyby will be possible. If we find a suitable object, the science yield of Pluto Express will be substantially enhanced. The density of objects in the Kuiper Belt is such that we are reasonably likely to find an object close enough to the flight path that on-board gas thrusters can effect a close encounter.

  2. Seat belt and child seat use in Lipetskaya Oblast, Russia: frequencies, attitudes, and perceptions.

    PubMed

    Ma, Sai; Tran, Nhan; Klyavin, Vladimir E; Zambon, Francesco; Hatcher, Kristin W; Hyder, Adnan A

    2012-01-01

    Despite the importance of understanding seat belt use patterns among drivers and passengers for the purpose of direct interventions or monitoring improvements, no study has described wearing rates for all seat positions in Russia. This study describes observed seat belt use and knowledge, attitudes, and perceptions of seat belt use in Lipetskaya Oblast, Russia. An observational study on the use of seat belts and child restraints in the Lipetskaya region conducted during October 2010 collected data in 6 districts and on 3 different road types. A roadside survey gathered information on knowledge, attitudes, and perceptions toward the use of seat belts from randomly selected drivers. Frequencies of seat belt use by seat position, gender, and road type were calculated. A multivariable logit model disclosed the associations between seat belt use and sociodemographic factors. The study design permitted comparison of observed seat belt use to self-reported seat belt use. A total of 25,795 vehicles and 39,833 drivers and passengers contributed observations. Overall, 55 percent of drivers were observed to be using seat belts. More than half (58%) of front seat passengers wore seat belts and only 9 percent of back seat passengers were observed to be wearing seat belts; 11 percent of cars with children had any type of child safety measure. Drivers on urban roads were less likely to wear seat belts compared to those on main highways and rural roads. Nearly 60 percent of survey respondents mentioned "seat belts save lives," and more than half mentioned law requirements and fines. Although the observed seat belt use in Lipetskaya Oblast is much higher than previous estimates in Russia, overall wearing rates remain far from universal. Rear seat passengers and children are particularly at risk. Because combined education and enforcement has proven to be effective elsewhere, such interventions are needed to improve seat belt use.

  3. Implications of meso- to micro-scale deformation for fault sealing capacity: Insights from the Lenghu5 fold-and-thrust belt, Qaidam Basin, NE Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Xie, Liujuan; Pei, Yangwen; Li, Anren; Wu, Kongyou

    2018-06-01

    As faults can be barriers to or conduits for fluid flow, it is critical to understand fault seal processes and their effects on the sealing capacity of a fault zone. Apart from the stratigraphic juxtaposition between the hanging wall and footwall, the development of fault rocks is of great importance in changing the sealing capacity of a fault zone. Therefore, field-based structural analysis has been employed to identify the meso-scale and micro-scale deformation features and to understand their effects on modifying the porosity of fault rocks. In this study, the Lenghu5 fold-and-thrust belt (northern Qaidam Basin, NE Tibetan Plateau), with well-exposed outcrops, was selected as an example for meso-scale outcrop mapping and SEM (Scanning Electron Microscope) micro-scale structural analysis. The detailed outcrop maps enabled us to link the samples with meso-scale fault architecture. The representative rock samples, collected in both the fault zones and the undeformed hanging walls/footwalls, were studied by SEM micro-structural analysis to identify the deformation features at the micro-scale and evaluate their influences on the fluid flow properties of the fault rocks. Based on the multi-scale structural analyses, the deformation mechanisms accounting for porosity reduction in the fault rocks have been identified, which are clay smearing, phyllosilicate-framework networking and cataclasis. The sealing capacity is highly dependent on the clay content: high concentrations of clay minerals in fault rocks are likely to form continuous clay smears or micro- clay smears between framework silicates, which can significantly decrease the porosity of the fault rocks. However, there is no direct link between the fault rocks and host rocks. Similar stratigraphic juxtapositions can generate fault rocks with very different magnitudes of porosity reduction. The resultant fault rocks can only be predicted only when the fault throw is smaller than the thickness of a faulted bed, in

  4. Deformation behavior of migmatites: insights from microstructural analysis of a garnet-sillimanite-mullite-quartz-feldspar-bearing anatectic migmatite at Rampura-Agucha, Aravalli-Delhi Fold Belt, NW India

    NASA Astrophysics Data System (ADS)

    Prakash, Abhishek; Piazolo, Sandra; Saha, Lopamudra; Bhattacharya, Abhijit; Pal, Durgesh Kumar; Sarkar, Saheli

    2018-03-01

    In the present study we investigate the microstructural development in mullite, quartz and garnet in an anatectic migmatite hosted within a Grenvillian-age shear zone in the Aravalli-Delhi Fold Belt. The migmatite exhibits three main deformation structures and fabrics (S1, S2, S3). Elongated garnet porphyroblasts are aligned parallel to the metatexite S2 layers and contain crenulation hinges defined by biotite-sillimanite-mullite-quartz (with S1 axial planar foliation). Microstructural evidence and phase equilibrium relations establish the garnet as a peritectic phase of incongruent melting by breakdown of biotite, sillimanite ± mullite and quartz at peak P-T of 8 kbar, 730 °C along a tight-loop, clockwise P-T path. Monazite dating establishes that the partial melting occurred between 1000 and 870 Ma. The absence of subgrains and systematic crystal lattice distortions in these garnets despite their elongation suggests growth pseudomorphing pre-existing 3-D networks of S1 biotite aggregates rather than high-temperature crystal plastic deformation which is noted in the S1 quartz grains that exhibit strong crystallographic preferred orientation (CPO), undulatory extinction and subgrains. Mode-I fractures in these garnet porphyroblasts induced by high melt pressure during late stage of partial melt crystallization are filled by retrograde biotite-sillimanite. Weak CPO and non-systematic crystal lattice distortions in the coarse quartz grains within the S2 leucosome domains indicate these crystallized during melt solidification without later crystal plastic deformation overprint. In the later stages of deformation (D3), strain was mostly accommodated in the mullite-biotite-sillimanite-rich restite domains forming S3 which warps around garnet and leucosome domains; consequently, fine-grained S3 quartz does not exhibit strong CPOs.

  5. 46 CFR 169.825 - Wearing of safety belts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Wearing of safety belts. 169.825 Section 169.825 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Operations § 169.825 Wearing of safety belts. The master of each vessel shall ensure that each person wears...

  6. 46 CFR 169.825 - Wearing of safety belts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Wearing of safety belts. 169.825 Section 169.825 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Operations § 169.825 Wearing of safety belts. The master of each vessel shall ensure that each person wears...

  7. Pattern of seat belt use by drivers in Trinidad and Tobago, West Indies

    PubMed Central

    2011-01-01

    Background In Trinidad and Tobago, the law on the mandatory use of seat belts was passed in 1995, but this law is hardly enforced. The objective of this study was to determine the frequency and predictors of seat belt use by motor vehicle drivers in the country. Findings A cross-sectional study of 959 motor vehicle drivers using a self-administered questionnaire. Data analysis included Pearson Chi square test and multinomial logistic regression analysis in order to determine the possible predictors of seat belt use by the drivers in Trinidad and Tobago. A majority of the drivers sometimes (51.8%) or always (31.6%) use a seat belt. About 16.7%, 29% and 54.2% of the drivers perceived that the other drivers use their seat belts more frequently, with the same frequency and less frequently respectively compared to themselves. The main reason for not using seat belt by the drivers was given as frequent stops (40.7%) and the main motivation to use seat belt by the drivers was given as stiffer penalties for non-compliance with the seat belt law (44.5%). The predictors of seat belt use were male driver, no formal or lower level of education, driving for less than 10 years, and the perception that the other drivers use seat belts with the same or higher frequency compared to the respondents. Conclusion Only a small proportion of the drivers in Trinidad and Tobago always use a seat belt when driving. There is the need to enforce the seat belt legislation in the country. PMID:21679410

  8. Planetary Migration and Kuiper Belt Dynamics

    NASA Astrophysics Data System (ADS)

    Malhotra, Renu

    The Kuiper belt holds memory of the dynamical processes that shaped the architecture of the solar system, including the orbital migration history of the giant planets. We propose studies of the orbital dynamics of the Kuiper Belt in order to understand the origin of its complex dynamical structure and its link to the orbital migration history of the giant planets. By means of numerical simulations, statistical tests, as well as analytical calculations we will (1) investigate the origin of resonant Kuiper belt objects to test alternative scenarios of Neptune's migration history, (2) investigate the long term dynamical evolution of the Haumea family of Kuiper Belt objects in order to improve the age estimate of this family, and (3) investigate resonance-sticking behavior and the Kozai-Lidov mechanism and its role in the origin of the extended scattered disk. These studies directly support the goals of the NASA-OSS program by improving our understanding of the origin of the solar system's architecture. Our results will provide constraints on the nature and timing of the dynamical excitation event that is thought to have occurred in early solar system history and to have determined the architecture of the present-day solar system; our results will also provide deeper theoretical understanding of sticky mean motion resonances which contribute greatly to the longevity of many small bodies, improve our understanding of dynamical transport of planetesimals in planetary systems, and help interpret observations of other planetary systems.

  9. Potential Jupiter-Family comet contamination of the main asteroid belt

    NASA Astrophysics Data System (ADS)

    Hsieh, Henry H.; Haghighipour, Nader

    2016-10-01

    We present the results of "snapshot" numerical integrations of test particles representing comet-like and asteroid-like objects in the inner Solar System aimed at investigating the short-term dynamical evolution of objects close to the dynamical boundary between asteroids and comets as defined by the Tisserand parameter with respect to Jupiter, TJ (i.e., TJ = 3). As expected, we find that TJ for individual test particles is not always a reliable indicator of initial orbit types. Furthermore, we find that a few percent of test particles with comet-like starting elements (i.e., similar to those of Jupiter-family comets) reach main-belt-like orbits (at least temporarily) during our 2 Myr integrations, even without the inclusion of non-gravitational forces, apparently via a combination of gravitational interactions with the terrestrial planets and temporary trapping by mean-motion resonances with Jupiter. We estimate that the fraction of real Jupiter-family comets occasionally reaching main-belt-like orbits on Myr timescales could be on the order of ∼ 0.1-1%, although the fraction that remain on such orbits for appreciable lengths of time is certainly far lower. For this reason, the number of JFC-like interlopers in the main-belt population at any given time is likely to be small, but still non-zero, a finding with significant implications for efforts to use apparently icy yet dynamically asteroidal main-belt comets as tracers of the primordial distribution of volatile material in the inner Solar System. The test particles with comet-like starting orbital elements that transition onto main-belt-like orbits in our integrations appear to be largely prevented from reaching low eccentricity, low inclination orbits, suggesting that the real-world population of main-belt objects with both low eccentricities and inclinations may be largely free of this potential occasional Jupiter-family comet contamination. We therefore find that low-eccentricity, low-inclination main-belt

  10. New features in the structure of the classical Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Gladman, Brett; Bannister, Michele T.; Alexandersen, Mike; Chen, Ying-Tung; Gwyn, Stephen; Kavelaars, J. J.; Petit, Jean-Marc; Volk, Kathryn; OSSOS Collaboration

    2016-10-01

    We report fascinating new dynamical structures emerging from a higher precision view of the classical Kuiper belt (the plentiful non-resonant orbits with semimajor axes in roughly the a=35-60 au range). The classical Kuiper Belt divides into multiple sub-populations: an 'inner' classical belt (a small group of non-resonant objects with a<39.4 au where the 3:2 resonance is located), an abundant 'main' classical belt (between the 3:2 and the 2:1 at a=47.4 au), and a difficult to study outer classical belt beyond the 2:1. We examine the dynamical structure, as precisely revealed in the detections from OSSOS (the Outer Solar System Origin's Survey); the data set is of superb quality in terms of orbital element and numbers of detections (Kavelaars et al, this meeting).The previous CFEPS survey showed that the main classical belt requires a complex dynamical substructure that goes beyond a simple 'hot versus cold' division based primarily on orbital inclination; the 'cold' inclination component requires two sub-components in the semimajor axis and perihelion distance q space (Petit et al 2011). CFEPS modelled this as a 'stirred' component present at all a=40-47 AU semimajor axes, with a dense superposed 'kernel' near a=44 AU at low eccentricity; the first OSSOS data release remained consistent with this (Bannister et al 2016). As with the main asteroid belt, as statistics and orbital quality improve we see additional significant substructure emerging in the classical belt's orbital distribution.OSSOS continues to add evidence that the cold stirred component extends smoothly beyond the 2:1 (Bannister et al 2016). Unexpectedly, the data also reveal the clear existence of a paucity of orbits just beyond the outer edge of the kernel; there are significantly fewer TNOs in the narrow semimajor axis band from a=44.5-45.0 AU. This may be related to the kernel population's creation, or it may be an independent feature created by planet migration as resonances moved in the

  11. 49 CFR 571.210 - Standard No. 210; Seat belt assembly anchorages.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 6 2013-10-01 2013-10-01 false Standard No. 210; Seat belt assembly anchorages... STANDARDS Federal Motor Vehicle Safety Standards § 571.210 Standard No. 210; Seat belt assembly anchorages. S1. Purpose and scope. This standard establishes requirements for seat belt assembly anchorages to...

  12. 49 CFR 571.210 - Standard No. 210; Seat belt assembly anchorages.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 6 2011-10-01 2011-10-01 false Standard No. 210; Seat belt assembly anchorages... STANDARDS Federal Motor Vehicle Safety Standards § 571.210 Standard No. 210; Seat belt assembly anchorages. S1. Purpose and scope. This standard establishes requirements for seat belt assembly anchorages to...

  13. 49 CFR 571.210 - Standard No. 210; Seat belt assembly anchorages.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 6 2014-10-01 2014-10-01 false Standard No. 210; Seat belt assembly anchorages... STANDARDS Federal Motor Vehicle Safety Standards § 571.210 Standard No. 210; Seat belt assembly anchorages. S1. Purpose and scope. This standard establishes requirements for seat belt assembly anchorages to...

  14. 49 CFR 571.210 - Standard No. 210; Seat belt assembly anchorages.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 6 2012-10-01 2012-10-01 false Standard No. 210; Seat belt assembly anchorages... STANDARDS Federal Motor Vehicle Safety Standards § 571.210 Standard No. 210; Seat belt assembly anchorages. S1. Purpose and scope. This standard establishes requirements for seat belt assembly anchorages to...

  15. The rock components and structures of Archean greenstone belts: An overview

    NASA Technical Reports Server (NTRS)

    Lowe, D. R.; Byerly, G. R.

    1986-01-01

    Knowledge of the character and evolution of the Earth's early crust is derived from the studies of the rocks and structures in Archean greenstone belts. Ability to resolve the petrologic, sedimentological and structural histories of greenstone belts, however, hinges first on an ability to apply the concepts and procedures of classical stratigraphy. Unfortunately, early Precambrian greenstone terrains present particular problems to stratigraphic analysis. Many current controversies of greenstone belt petrogenesis, sedimentology, tectonics and evolution arise more from an inability to develop a clear stratigraphic picture of the belts than from ambiguities in interpretation. Four particular stratigraphic problems that afflict studies of Archean greenstone belts are considered: determination of facing directions, correlation of lithologic units, identification of primary lithologies and discrimination of stratigraphic versus structural contacts.

  16. Compliance with Seat Belt Use in Makurdi, Nigeria: An Observational Study

    PubMed Central

    Popoola, SO; Oluwadiya, KS; Kortor, JN; Denen-Akaa, P; Onyemaechi, NOC

    2013-01-01

    Background: Seat belts are designed to reduce injuries due to road crash among vehicle occupants. Aims: This study aims to determine the availability of seat belt in vehicles and compliance with seat belt use among vehicle occupants. Materials and methods: This was a 24-h direct observational study of seat belt usage among vehicle occupants in Makurdi, Benue State, Nigeria. By direct surveillance and using a datasheet, we observed 500 vehicles and their occupants for seat belt availability and compliance with its use. Chi-square test was used for test of significance between variables. Results: Twenty-five (5.0%) of the observed 500 vehicles had no seat belt at all. Overall, compliance was 277/486 (57.0%). Use of seat belt was highest in the afternoon with 124/194 (64.4%), followed by 111/188 (59.0%) in the morning and 42/95 (44.2%) at night. Compliance was highest among car occupants [209/308 (67.9%)] and private vehicles, and lowest among commercial vehicle occupants. Compliance among female drivers was 77.1% compared with 51.4% among male drivers. Among drivers, the mean age of seat belt users was 38.4 (7.7) years, which was significantly younger than the 41.3 (8.7) years mean age of non-users. Similar figures were obtained among other vehicle occupants. Conclusions: Compared with previous studies, seat belt usage has improved among Nigerian road users, but there is still room for improvement, especially early in the mornings and at nights. Since these were times when law enforcement agencies were not likely to be on the roads, we advocate for improved coverage by enforcement agents to enforce better compliance. PMID:24116327

  17. An Evaluation of the Seat Belt Education Campaign.

    ERIC Educational Resources Information Center

    Rochon, James

    A seat belt education campaign conducted in Canada to dispel myths surrounding seat belts and promote a better understanding of their functions was evaluated. Two telephone surveys, each comprised of 4,000 respondents, were conducted. The first was done immediately before the campaign and the second immediately succeeding the campaign. Also, a…

  18. Seat belt use among rear passengers: validity of self-reported versus observational measures

    PubMed Central

    Zambon, Francesco; Fedeli, Ugo; Marchesan, Maria; Schievano, Elena; Ferro, Antonio; Spolaore, Paolo

    2008-01-01

    Background The effects of seat belt laws and public education campaigns on seat belt use are assessed on the basis of observational or self-reported data on seat belt use. Previous studies focusing on front seat occupants have shown that self-reports indicate a greater seat belt usage than observational findings. Whether this over-reporting in self reports applies to rear seat belt usage, and to what extent, have yet to be investigated. We aimed to evaluate the over-reporting factor for rear seat passengers and whether this varies by gender and under different compulsory seat belt use conditions. Methods The study was conducted in the Veneto Region, an area in the North-East of Italy with a population of 4.7 million. The prevalence of seat belt use among rear seat passengers was determined by means of a cross-sectional self-report survey and an observational study. Both investigations were performed in two time periods: in 2003, when rear seat belt use was not enforced by primary legislation, and in 2005, after rear seat belt use had become compulsory (June 2003). Overall, 8138 observations and 7902 interviews were recorded. Gender differences in the prevalence of rear seat belt use were examined using the chi-square test. The over-reporting factor, defined as the ratio of the self-reported to the observed prevalence of rear seat belt use, was calculated by gender before and after the rear seat belt legislation came into effect. Results Among rear seat passengers, self-reported rates were always higher than the observational findings, with an overall over-reporting factor of 1.4. We registered no statistically significant changes over time in the over-reporting factor, nor any major differences between genders. Conclusion Self-reported seat belt usage by rear passengers represents an efficient alternative to observational studies for tracking changes in actual behavior, although the reported figures need to be adjusted using an appropriate over-reporting factor in

  19. Paper Folding Fractions

    ERIC Educational Resources Information Center

    Pagni, David

    2007-01-01

    In this article, the author presents a paper folding activity that can be used for teaching fractions. This activity can be used to describe areas of folded polygons in terms of a standard unit of measure. A paper folding fractions worksheet and its corresponding solutions are also presented in this article. (Contains 2 figures.)

  20. Fold-and-thrust belt evolution influenced by along and across strike thickness variations: new insights from brittle-ductile centrifuge analogue models

    NASA Astrophysics Data System (ADS)

    Santolaria Otin, Pablo; Harris, Lyal; Casas, Antonio; Soto, Ruth

    2014-05-01

    Using a new centrifuge analogue modelling approach, 38 models were performed to study the influence of along and across strike thickness variations of a ductile-brittle layered sequence on the kinematics and deformation style of fold-and-thrust belts. Four different series, changing the brittle-ductile thickness ratio in models with i) constant thickness, ii) across strike varying thickness, iii) along strike varying thickness and iv) along and across-strike varying thickness, were performed. The brittle sedimentary cover was simulated by "Moon Sand™", regular fine-grained quartz sand coated by polymer and synthetic rubber binders, allowing layers to be placed vertically in the centrifuge (impossible with normal sand). The ductile décollement (evaporites) was simulated by silicone putty (Crazy Aaron Enterprise's Thinking Putty™). Models were run step by step in a high-acceleration centrifuge attaining 900 g, what allows to drastically reduce the experimental time. In addition to surface observation and serial cross-sections at the end of the models, CT scans portray the progressive 3- and 4-dimensional evolution of several models. With constant thickness, the increase of the brittle-ductile ratio results in the decrease of the number of structures where shortening is accommodated and the development of structures does not follow a linear sequence. Across-strike thickness variations trigger the location of deformation towards the wedge front, precluding the emplacement of structures in the hinterland. Along-strike thickness changes result in the lateral variation of the number of structure and a differential displacement of the deformation front. The occurrence of oblique structures is enhanced in wedges with across and along strike thickness variations where, in addition, rotational domains are observed. Comparison with the South Pyrenean Central Unit, in the Southern Pyrenees, characterized by a west- and southward thinning of the pretectonic Mesozoic series