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1

Influence of overriding plate geometry and rheology on subduction  

NASA Astrophysics Data System (ADS)

Subduction dynamics is strongly dependent on the geometry and rheology of the subducting slab and adjacent plates, as well as on the induced mantle flow driven by the evolution of tectonic configurations along subduction zones. However, these processes, and the associated plate tectonic driving forces, are difficult to study using time-dependent 3-dimensional computer simulations due to limitations in computing resources. We investigate these phenomena with a novel numerical approach, using BEM-Earth, a Stokes flow solver based on the Boundary Element Method (BEM) with a Fast-Multipole (FM) implementation. The initial BEM-Earth model configurations self-consistently determine the evolution of the entire lithosphere-mantle system without imposing additional constraints in a whole-Earth spherical setting. We find that models without an overriding plate overestimate trench retreat by 65% in a 20 m.y. model run. Also, higher viscosity overriding plates are associated with higher velocity subducting slabs, analogue to faster oceanic plates subducting beneath more rigid continental lithosphere. In our models poloidal flows dominate the coupling between the down-going and overriding plates, with trench-orthogonal length variations in overriding plates inducing flows at least ˜2× stronger than trench-parallel width variations. However, deformation in the overriding plate is related to its length and width, with narrower and longer plates extending more than wider and shorter plates.

Butterworth, N. P.; Quevedo, L.; Morra, G.; Müller, R. D.

2012-06-01

2

Downgoing plate controls on overriding plate deformation in subduction zones  

NASA Astrophysics Data System (ADS)

Although subduction zones are convergent margins, deformation in the upper plate can be extensional or compressional and tends to change through time, sometimes in repeated episodes of strong deformation, e.g, phases of back-arc extension. It is not well understood what factors control this upper plate deformation. We use the code Fluidity, which uses an adaptive mesh and a free-surface formulation, to model a two-plate subduction system in 2-D. The model includes a composite temperature- and stress-dependent rheology, and plates are decoupled by a weak layer, which allows for free trench motion. We investigate the evolution of the state of stress and topography of the overriding plate during the different phases of the subduction process: onset of subduction, free-fall sinking in the upper mantle and interaction of the slab with the transition zone, here represented by a viscosity contrast between upper and lower mantle. We focus on (i) how overriding plate deformation varies with subducting plate age; (ii) how spontaneous and episodic back-arc spreading develops for some subduction settings; (iii) the correlation between overriding plate deformation and slab interaction with the transition zone; (iv) whether these trends resemble observations on Earth.

Garel, Fanny; Davies, Rhodri; Goes, Saskia; Davies, Huw; Kramer, Stephan; Wilson, Cian

2014-05-01

3

Three-dimensional dynamic models of subducting plate-overriding plate-upper mantle interaction  

NASA Astrophysics Data System (ADS)

We present fully dynamic generic three-dimensional laboratory models of progressive subduction with an overriding plate and a weak subduction zone interface. Overriding plate thickness (TOP) is varied systematically (in the range 0-2.5 cm scaling to 0-125 km) to investigate its effect on subduction kinematics and overriding plate deformation. The general pattern of subduction is the same for all models with slab draping on the 670 km discontinuity, comparable slab dip angles, trench retreat, trenchward subducting plate motion, and a concave trench curvature. The narrow slab models only show overriding plate extension. Subduction partitioning (vSP? / (vSP? + vT?)) increases with increasing TOP, where trenchward subducting plate motion (vSP?) increases at the expense of trench retreat (vT?). This results from an increase in trench suction force with increasing TOP, which retards trench retreat. An increase in TOP also corresponds to a decrease in overriding plate extension and curvature because a thicker overriding plate provides more resistance to deform. Overriding plate extension is maximum at a scaled distance of ~200-400 km from the trench, not at the trench, suggesting that basal shear tractions resulting from mantle flow below the overriding plate primarily drive extension rather than deviatoric tensional normal stresses at the subduction zone interface. The force that drives overriding plate extension is 5%-11% of the slab negative buoyancy force. The models show a positive correlation between vT? and overriding plate extension rate, in agreement with observations. The results suggest that slab rollback and associated toroidal mantle flow drive overriding plate extension and backarc basin formation.

Meyer, C.; Schellart, W. P.

2013-02-01

4

Dynamics of 3-D thermo-mechanical subduction with an overriding plate  

NASA Astrophysics Data System (ADS)

Characterizing the role of the upper plate in dynamic subduction models is of paramount importance in understanding the subduction system as a whole. We investigate the effect of the overriding plate on subduction dynamics in a 3D, purely dynamic thermo-mechanical setup of the finite element code, CitcomCU (Moresi & Gurnis, 1996; Zhong, 2006). The reference models are purely Newtonian with a temperature dependent viscosity. Subduction is initiated by an asymmetric notch in the down going plate, and the two plates are decoupled by a weak, 15 km thick crustal layer, along shear is localized. As observed in previous 2D modeling studies the presence of an overriding plate decreases the vertical extent of the poloidal flow, resulting in reduced vertical subduction velocity, reduced trench retreat and a larger dip angle. This increased dip angle results in preferential slab folding, as opposed to flattening, at the 660-km discontinuity when the overriding plate is included. It has recently been suggested that toroidal flow, due to slab rollback, creates trench-perpendicular gradients in basal traction below the overriding lithosphere which can cause back-arc extension (Schellart & Moresi, 2013; Duarte et al., 2013). In our models, we also observe long wavelength back-arc extensional stresses, and more localized forearc compressive stresses. As in Piromallo et al. (2010), we decompose the velocity field into toroidal and poloidal components, in order to attempt to quantify the relationship between toroidal flow and overriding plate stress state for various model set-ups. We focus on how the presence of an overriding plate, and variable upper plate widths and strengths, modifies the partition between toroidal and poloidal flow, as well as overriding plate stress state and subducting plate dynamics (i.e. trench plate and penetration velocities). The presence of an overriding plate reduces the toroidal flow component of the velocity field and so significantly reduces the rate at which trench curvature, previously shown to occur in due to toroidal flow in 3D single plate models (e.g. Stegman et al., 2006), develops. Thus, dynamic modeling studies that neglect the presence of the overriding plate may be significantly overestimating the effect of toroidal flow on trench curvature. Finally, we examine how the presence of a piece of compositionally buoyant lithosphere, both in the subducting and overriding plates, modifies the dynamics of the subducting slab and the stress state of the overriding plate.

Holt, A.; Becker, T. W.

2013-12-01

5

The Continental Plates are Getting Thicker.  

ERIC Educational Resources Information Center

Reviews seismological studies that provide evidence of the existence of continental roots beneath the continents. Suggests, that through the collisions of plate tectonics, continents stabilized part of the mobile mantle rock beneath them to form deep roots. (ML)

Kerr, Richard A.

1986-01-01

6

A regime diagram for subduction dynamics from thermo-mechanical models with a mobile trench and an overriding plate  

NASA Astrophysics Data System (ADS)

The penetration or stagnation of subducted slabs in mantle transition zone and lower mantle influences Earth's thermal, chemical and tectonic evolution. Yet, the mechanisms responsible for the wide range of observed slab morphologies within the transition zone remain debated. Here, we investigate how downgoing and overriding plate ages controls the interaction between subducted slabs and mantle transition zone. We use 2-D thermo-mechanical models of a two-plate subduction system, modeled with the finite-element, adaptative-mesh code Fluidity. We implement a temperature- and stress-dependent rheology, and viscosity increases 30-fold from upper to lower mantle. Trench position evolves freely in response to plate dynamics. Such an approach self-consistently captures feedbacks between temperature, density, flow, strength and deformation. Our results indicate that key controls on subduction dynamics and slab morphology are: (i) the slab's ability to induce trench motion; and (ii) the evolution of slab strength during sinking. We build a regime diagram that distinguishes four subduction styles: (1) a "vertical folding" mode with stationary trench (young subducting plates, comparatively old overriding plates); (2) slabs that are "horizontally deflected" along the 660-km deep viscosity jump (initially young subducting and overriding plates); (3) an inclined slab morphology, resulting from strong trench retreat (old subducting plates, young overriding plates); and (4) a two-stage mode, displaying bent (rolled-over) slabs at the end of upper-mantle descent, that subsequently unbend and achieve inclined morphologies, with late trench retreat (old subducting and overriding plates). We show that all seismically observed slab morphologies can arise from changes in the initial plates ages at the onset of subduction.

Garel, Fanny; Davies, Rhodri; Goes, Saskia; Davies, Huw; Kramer, Stephan; Wilson, Cian

2014-05-01

7

Three-dimensional dynamic laboratory models of subduction with an overriding plate and variable interplate rheology  

NASA Astrophysics Data System (ADS)

Subduction zones are complex 3-D features in which one tectonic plate sinks underneath another into the deep mantle. During subduction the overriding plate (OP) remains in physical contact with the subducting plate and stresses generated at the subduction zone interface and by mantle flow force the OP to deform. We present results of 3-D dynamic laboratory models of subduction that include an OP. We introduce new interplate materials comprising homogeneous mixtures of petrolatum and paraffin oil to achieve progressive subduction. The rheology of these mixtures is characterized by measurements using a strain rate controlled rheometer. The results show that the strength of the mixture increases with petrolatum content, which can be used as a proxy for the degree of mechanical coupling along the subduction interface. Results of subduction experiments are presented with different degrees of mechanical coupling and the influence this has on the dynamics and kinematics of subduction. The modelling results show that variations in the degree of mechanical coupling between the plates have a major impact on subduction velocities, slab geometry and the rate of OP deformation. In all experiments the OP is displaced following trench migration and experiences overall extension localized in the plate interior. This suggests that OP deformation is driven primarily by the toroidal component of subduction-related mantle return flow. The subduction rate is always very slow in experiments with medium mechanical coupling, and subduction stops prematurely in experiments with very high coupling. This implies that the shear forces along the plate interface in natural subduction zone systems must be relatively low and do not vary significantly. Otherwise a higher variability in natural subduction velocities should be observed for mature, non-perturbed subduction zones. The required low shear force is likely controlled by the rheology of highly hydrated sedimentary and basaltic rocks.

Duarte, João C.; Schellart, Wouter P.; Cruden, Alexander R.

2013-10-01

8

Trench-parallel flow in the southern Ryukyu subduction system: Effects of progressive rifting of the overriding plate  

NASA Astrophysics Data System (ADS)

AbstractThe Okinawa trough in the Ryukyu subduction system is one of a few actively extending back arc basins within the <span class="hlt">continental</span> lithosphere. Recent shear-wave splitting measurements show variable fast directions along the trough suggesting a complex three-dimensional mantle flow field. In this study we use numerical subduction models to demonstrate that the thickness variations of the <span class="hlt">continental</span> lithosphere bounding the edge of a subduction zone can result in complicated mantle circulation and regional dynamics. The model results for the southern Ryukyu show a combination of two effects: Along the Okinawa trough, the increasing thickness of the <span class="hlt">overriding</span> Eurasian <span class="hlt">plate</span> toward Taiwan due to a gradually diminishing rifting induces pressure gradients that drive trench-parallel flow to the edge in the shallow portion of the mantle wedge, and the thick Eurasian lithosphere to the west effectively blocks and diverts this along-arc flow and limits the toroidal flow around the slab edge below it. The toroidal flow thus enters the mantle wedge at depths of more than about 100 km, opposite in direction with and largely below the along-arc flow. These combined geometry effects of the Eurasian lithosphere create an intricate three-dimensional flow structure at the southern edge of the Ryukyu subduction zone. Model predictions for lattice preferred orientations of olivine aggregates show rotation patterns that agree with the observed shear-wave splitting patterns. This three-dimensional scenario echoes the geochemical and seismological evidence worldwide that indicates complex, depth-varying mantle circulations in subduction systems.</p> <div class="credits"> <p class="dwt_author">Lin, Shu-Chuan; Kuo, Ban-Yuan</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">9</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009EGUGA..1112186C"> <span id="translatedtitle">Crustal Structure and Deformation of the Incoming and <span class="hlt">Overriding</span> <span class="hlt">Plates</span> of the North Chilean Subduction Zone, 21-23.5°S</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present multichannel seismic (MCS) reflection images of the structure of the subduction zone of northern Chile. We focus on 3 MCS lines from the cruise Sonne 104, collected with a 3-km-long, 120 channel streamer and a 3124 c.i. well-tuned airgun array. Two lines are ~450 km long each, and image the structure of the <span class="hlt">overriding</span> <span class="hlt">plate</span> and some ~350 km of the oceanic incoming <span class="hlt">plate</span> across the outer rise bulge and into the undeformed segment of the incoming <span class="hlt">plate</span>. The third line images the structure of the <span class="hlt">overriding</span> <span class="hlt">plate</span> and under the oceanic trench slope. The seismic images show a well-defined top of the igneous crust and fairly continuous reflections from the base of the crust (Moho), typically 2 seconds (TWT) below the top of the igneous crust, indicating a ~6 km thick crust. Only across the Iquique Ridge segment Moho reflections occur at about 3 seconds (TWT) under the top of the igneous crust indicating a thicker crust (about 9 km thick). The images also show the bending-related deformation of the incoming oceanic crust as it approaches first the outer rise bulge and subsequently bends into the trench. The <span class="hlt">plate</span> bulges at the outer rise, and abruptly dips into the trench. The top of the igneous crust shows the formation of offsets indicating new faulting: Offsets formed by bend-faulting in the outer rise are difficult to distinguish from offsets formed at the spreading center, but abruptly increase into the trench slope. Dipping reflections -possibly indicating faulting-across the crust apparently related to top basement offsets occur along the entire line. Dipping reflections also occur in the mantle under the outer rise (clearly below the Moho reflection), in spite of the limited evidence for large scale faulting during outer-rise deformation. The the large horst-and-graben structures in the trench possibly prevent proper imaging of dipping reflection, but faults offsets continue growing into the trench axis and possibly as the <span class="hlt">plate</span> under-thrusts beneath the margin. The <span class="hlt">overriding</span> <span class="hlt">plate</span> of the <span class="hlt">continental</span> margin is structured in an upper, middle and lower slope containing a frontal prism. The upper slope shows a well-stratified sediment sequence cut by discrete landward dipping normal faults that display tens of km of lateral continuity in multibeam bathymetry maps. Across an abrupt variation in slope dip the middle slope is defined by changes of: normal fault dip changing from landward to seaward, and a poorly defined sediment stratification obscured by pervasive faulting and mass wasting processes. The trench axis is largely devoid of stratified turbidites. But the 3 seismic lines show abundant debris from the <span class="hlt">continental</span> slope accumulating at the slope toe, forming a 5-10 km wide sediment prism. The prism is also observable in multibeam bathymetry maps as a fairly continuos feature for hundres of km. The landward segment of the frontal prism appears to be under-thrusting the <span class="hlt">overriding</span> margin basement, thus providing abundant clastic material to the subduction channel. Thus the amount of fluid-rich sediment in this apparently starved trench seems to be considerable. A bright <span class="hlt">plate</span> boundary reflection, probably fluid-rich, is imaged for ~50 km under the <span class="hlt">continental</span> slope.</p> <div class="credits"> <p class="dwt_author">Calahorrano, A.; Ranero, C. R.; Barckhausen, U.; Reichert, C.; Grevemeyer, I.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">10</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=%22Tectonic+Plates%22&pg=6&id=EJ290392"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics and <span class="hlt">Continental</span> Drift: Classroom Ideas.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Suggests various classroom studies related to <span class="hlt">plate</span> tectonics and <span class="hlt">continental</span> drift, including comments on and sources of resource materials useful in teaching the topics. A complete list of magazine articles on the topics from the Sawyer Marine Resource Collection may be obtained by contacting the author. (JN)</p> <div class="credits"> <p class="dwt_author">Stout, Prentice K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">11</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.T53B2573G"> <span id="translatedtitle">Strain weakening enables <span class="hlt">continental</span> <span class="hlt">plate</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Much debate exists concerning the strength distribution of the <span class="hlt">continental</span> lithosphere, how it controls lithosphere-scale strain localization and hence enables <span class="hlt">plate</span> tectonics. No rheological model proposed to date is comprehensive enough to describe both the weakness of <span class="hlt">plate</span> boundary and rigid-like behaviour of <span class="hlt">plate</span> interiors. Here we show that the duality of strength of the lithosphere corresponds to different stages of microstructural evolution. Geological constraints on lithospheric strength and large strain numerical experiments reveal that the development of layers containing weak minerals and the onset of grain boundary sliding upon grain size reduction in olivine cause strain localisation and reduce strength in the crust and subcontinental mantle, respectively. The positive feedback between weakening and strain localization leads to the progressive development of weak <span class="hlt">plate</span> boundaries while <span class="hlt">plate</span> interiors remain strong.</p> <div class="credits"> <p class="dwt_author">Gueydan, F.; Précigout, J.; Montesi, L. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">12</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1998JGR...10315221B"> <span id="translatedtitle">Analogue models of obliquely convergent <span class="hlt">continental</span> <span class="hlt">plate</span> boundaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Analogue models are used to examine crustal-scale faulting at obliquely convergent <span class="hlt">continental</span> <span class="hlt">plate</span> boundaries. A uniform Coulomb material is deformed with basal kinematic boundary conditions to model two obliquely convergent lithospheric <span class="hlt">plates</span>. The mantle part of one <span class="hlt">plate</span> is assumed to detach from its <span class="hlt">overriding</span> crust and then be subducted beneath the other <span class="hlt">plate</span>. The obliquity of the collision is assumed to remain constant throughout the deformation. Experiments are run with obliquities ranging from pure convergence (low obliquity) to pure strike slip (high obliquity). Reverse faults are observed for all obliquities with a nonzero convergent component. By contrast, only collisions with a large amount of strike slip motion exhibit wrench faulting. In experiments dominated by their convergent component, the strike slip motion is totally accommodated by oblique slip along the reverse faults. Strain partitioning between reverse faults and wrench faults is only observed for experiments run above a certain critical partitioning obliquity. Prom the observed initial faults, we can deduce the change in orientation in the principal stress triad as the obliquity is changed. We propose that the initial direction of maximum compressive stress (?1) rotates horizontally as the obliquity is changed, which in turn affects the geometry of the initial faults formed in the material. In the case of reverse faults, the rotation increases their dip measured along the direction of pure convergence. The relative magnitude of the minimum horizontal stress and the vertical stress determine whether reverse faults or strike slip faults are the first to form. Although long term deformation is more difficult to analyze, a simple relationship for the angle at which strain partitioning occurs is derived.</p> <div class="credits"> <p class="dwt_author">Burbidge, David R.; Braun, Jean</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">13</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AGUFM.T13G..04J"> <span id="translatedtitle">Aegean tectonics, a record of slab-<span class="hlt">overriding</span> <span class="hlt">plate</span> interactions (Invited)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Two opposing visions of the Aegean backarc tectonics implicitly contain contrasting images of the rheological behaviour of the lihosphere, supported by different sets of observations. The propagation of the NAF and extension in the Corinth Rift suggest a strongly localising rheology whereas the formation of MCC in the Cyclades and the Rhodope suggests instead a more viscous behaviour. This paradox was the seminal question addressed by the ANR-EGEO programme (2007-2010) that leads to the following conclusions: (1) The exhumation of the Cycladic MCC’s is accommodated by the N-dipping North Cycladic Detachment System (NCDS) that partly reworks the Vardar suture and at the base by a series of thrusts, including the basal contact of the Cycladic Blueschists (CBS) over the Cycladic Basement (CB). The activity of LANF is due to the reactivation of pre-existing discontinuities such as thrusts or earlier detachments and much less to the interaction with granitic plutons. (2) Exhumation in the Cyclades has proceeded in two stages: (a) Eocene syn-orogenic exhumation within the subduction lower/upperplate interface while the post-orogenic Rhodope MCC formed further north, (b) Oligo-Miocene post-orogenic extension in an MCC mode coeval with syn-orogenic exhumation in Crete and the Peloponnese. (3) Both stages were associated with slab retreat, as early as the Eocene with an acceleration at 30-35 Ma. (4) The localisation of the presently active steeply-dipping normal faults on the southern margin of the Corinth Rift may have been preceded by a partial reworking of thrusts and syn-orogenic detachments by shallow-dipping decollements. (5) The localisation of the NAF in the Marmara Sea region and the Northern Aegean Sea is now accurately dated between 5.3 and 5 Ma Ma using the erosion and deposition surfaces that mark the Messinian salinity Crisis and nannofossils ages. (6) The formation of MCCs in the Cyclades resulted in the draining of the low viscosity lower crust from the northern Aegean Sea and led to an easier coupling between upper mantle and upper crust, easing the localisation and propagation of the NAF. (7) A comparison between crustal and mantle finite strain suggests that mantle flow due to slab retreat controls the stretching of the crust. Our model involves progressive slab retreat and mantle flow below the <span class="hlt">overriding</span> <span class="hlt">plate</span> inducing the observed succession of tectonic episodes with a progressive localisation of extension due to several slab tearing events. There is no paradox in the tectonic history and rheological behaviour of the Aegean lithosphere but an evolution of the kinematic boundary conditions due to slab deformation at depth.</p> <div class="credits"> <p class="dwt_author">Jolivet, L.; Faccenna, C.; Huet, B.; Lecomte, E.; Labrousse, L.; Denèle, Y.; Le Pourhiet, L.; Lacombe, O.; Burov, E. B.; Meyer, B.; Suc, J.; Popescu, S.; Monié, P.; Philippon, M.; Gueydan, F.; Brun, J.; Paul, A.; Salaün, G.; Armijo, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">14</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/14848609"> <span id="translatedtitle"><span class="hlt">Continental</span> tectonics in the aftermath of <span class="hlt">plate</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">It is shown that the basic tenet of <span class="hlt">plate</span> tectonics, rigid-body movements of large <span class="hlt">plates</span> of lithosphere, fails to apply to <span class="hlt">continental</span> interiors. There, buoyant <span class="hlt">continental</span> crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity. The role of crustal blocks and of the detachment of crustal fragments in this process is</p> <div class="credits"> <p class="dwt_author">Peter Molnar</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">15</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19910027226&hterms=indian+navy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dindian%2Bnavy"> <span id="translatedtitle">Current <span class="hlt">plate</span> motions. [<span class="hlt">continental</span> groupings and global modelling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A global <span class="hlt">plate</span> motion model, named NUVEL-1, which describes current <span class="hlt">plate</span> motions between 12 rigid <span class="hlt">plates</span> is described, with special attention given to the method, data, and assumptions used. Tectonic implications of the patterns that emerged from the results are discussed. It is shown that wide <span class="hlt">plate</span> boundary zones can form not only within the <span class="hlt">continental</span> lithosphere but also within the oceanic lithosphere; e.g., between the Indian and Australian <span class="hlt">plates</span> and between the North American and South American <span class="hlt">plates</span>. Results of the model also suggest small but significant diffuse deformation of the oceanic lithosphere, which may be confined to small awkwardly shaped salients of major <span class="hlt">plates</span>.</p> <div class="credits"> <p class="dwt_author">Demets, C.; Gordon, R. G.; Argus, D. F.; Stein, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">16</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.4732R"> <span id="translatedtitle">Numerical modeling of subduction beneath non-uniform <span class="hlt">overriding</span> <span class="hlt">plates</span>: Time-dependent evolution of slab geometry and trench-parallel flow</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Seismic anisotropy measurements show that the fast spreading direction below the slab is aligned parallel to the trench in the central region and perpendicular near the edges. Above the slab it has a complex pattern, often showing abrupt transitions between trench-parallel and trench-perpendicular directions and sharp changes in intensity. The origin of this complex pattern is poorly understood, however, previous models have shown that variations in slab geometry can cause trench-parallel flow above the slab. In turn, <span class="hlt">overriding</span> <span class="hlt">plate</span> thermal state influences the slab dip, which suggests a causal link between <span class="hlt">overriding</span> <span class="hlt">plate</span> structure, slab geometry and mantle flow in subduction zones. We study the effect of along-strike variations in thermal thickness of the <span class="hlt">overriding</span> <span class="hlt">plate</span> on the evolution of slab geometry and induced mantle flow. To perform the study we implement generic 3D time dependent thermo mechanical numerical models of buoyancy driven subduction using CitcomS. We find that increased hydrodynamic suction beneath the colder portion of the <span class="hlt">overriding</span> <span class="hlt">plate</span> causes shallower slab dip. The variation in slab geometry drives strong trench-parallel flow beneath the slab and a complex flow pattern above the slab. The mantle flow pattern responds to the changing geometry of the slab, which makes the process strongly time-dependent. The location and strength of trench-parallel flow vary throughout the simulations, which suggests that the global variability in seismic anisotropy in present-day observations is in part due to the non-steady-state behavior of subduction systems. This new mechanism for driving trench-parallel flow provides a good explanation for seismic anisotropy observations from the Middle and South America subduction zones, where both slab dip and <span class="hlt">overriding</span> <span class="hlt">plate</span> thermal state are strongly variable and correlated.</p> <div class="credits"> <p class="dwt_author">Rodriguez-Gonzalez, Juan; Billen, Magali; Negredo, Ana</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">17</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890036055&hterms=Plate+Tectonics&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2522Plate%2BTectonics%2522"> <span id="translatedtitle"><span class="hlt">Continental</span> tectonics in the aftermath of <span class="hlt">plate</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">It is shown that the basic tenet of <span class="hlt">plate</span> tectonics, rigid-body movements of large <span class="hlt">plates</span> of lithosphere, fails to apply to <span class="hlt">continental</span> interiors. There, buoyant <span class="hlt">continental</span> crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity. The role of crustal blocks and of the detachment of crustal fragments in this process is discussed. Future areas of investigation are addressed.</p> <div class="credits"> <p class="dwt_author">Molnar, Peter</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">18</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004AGUFM.T21B0533S"> <span id="translatedtitle">Finite Element Models of Viscous Flow in the Mantle Wedge Above a Subducting Slab for Different Relative Subducting and <span class="hlt">Overriding</span> <span class="hlt">Plate</span> Motions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A series of models of viscous flow in the mantle wedge above a subducting slab are generated with a two-dimensional finite element code used to solve for time-dependent, viscous deformation of the mantle in response to relative motion of the slab and the <span class="hlt">overriding</span> <span class="hlt">plate</span>. Resultant velocity fields are used to compute finite strain for mantle particles traversing the wedge; these patterns of finite strain may serve as a proxy for mantle fabrics formed through lattice preferred orientation (LPO) of olivine crystals. Boundary conditions applied to the wedge model to represent relative motions of the subducting and <span class="hlt">overriding</span> <span class="hlt">plates</span> have a strong influence on the appearance of mantle wedge flow. In particular, distinctive flow patterns result from an <span class="hlt">overriding</span> <span class="hlt">plate</span> velocity that is either faster or slower than the subducting <span class="hlt">plate</span> velocity. The resulting geometry of mantle flow is further modified in a three-<span class="hlt">plate</span> scenario, where two <span class="hlt">overriding</span> <span class="hlt">plates</span> move at different velocities along the top of the mantle wedge. Flow fields generated from these boundary conditions are computed for both simple, isoviscous and isothermal cases as well as more complex rheologies such as a power-law relationship between stress and strain rate with temperature-dependent viscosity. For the case of isoviscous and isothermal flow fields, migration of the <span class="hlt">overriding</span> <span class="hlt">plate</span> away from the trench results in mantle material being drawn from deeper depths than the case of a stationary <span class="hlt">overriding</span> <span class="hlt">plate</span>. In addition, preliminary results indicate that temperature-dependent viscosity may result in even steeper particle paths from deeper in the mantle into the wedge corner. This distinction may have important implications for the thermal structure of the mantle wedge. Finite strain is computed for particles traversing each of these flow fields, yielding a predicted olivine LPO for each case. Important differences in these LPO fields imply that seismic waves traversing the mantle wedge above a subducting slab may yield waveforms with a distinctive signature reflecting the specific geometry and characteristics of the mantle flow field through its particular pattern of olivine LPO. Combining seismic anisotropy measurements with flow modeling may thus provide important constraints for flow in the mantle wedge above a subducting slab.</p> <div class="credits"> <p class="dwt_author">Sherrington, H. F.; Willett, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">19</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014GGG....15.1739G"> <span id="translatedtitle">Interaction of subducted slabs with the mantle transition-zone: A regime diagram from 2-D thermo-mechanical models with a mobile trench and an <span class="hlt">overriding</span> <span class="hlt">plate</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">zone slab deformation influences Earth's thermal, chemical, and tectonic evolution. However, the mechanisms responsible for the wide range of imaged slab morphologies remain debated. Here we use 2-D thermo-mechanical models with a mobile trench, an <span class="hlt">overriding</span> <span class="hlt">plate</span>, a temperature and stress-dependent rheology, and a 10, 30, or 100-fold increase in lower mantle viscosity, to investigate the effect of initial subducting and <span class="hlt">overriding-plate</span> ages on slab-transition zone interaction. Four subduction styles emerge: (i) a "vertical folding" mode, with a quasi-stationary trench, near-vertical subduction, and buckling/folding at depth (VF); (ii) slabs that induce mild trench retreat, which are flattened/"horizontally deflected" and stagnate at the upper-lower mantle interface (HD); (iii) inclined slabs, which result from rapid sinking and strong trench retreat (ISR); (iv) a two-stage mode, displaying backward-bent and subsequently inclined slabs, with late trench retreat (BIR). Transitions from regime (i) to (iii) occur with increasing subducting <span class="hlt">plate</span> age (i.e., buoyancy and strength). Regime (iv) develops for old (strong) subducting and <span class="hlt">overriding</span> <span class="hlt">plates</span>. We find that the interplay between trench motion and slab deformation at depth dictates the subduction style, both being controlled by slab strength, which is consistent with predictions from previous compositional subduction models. However, due to feedbacks between deformation, sinking rate, temperature, and slab strength, the subducting <span class="hlt">plate</span> buoyancy, <span class="hlt">overriding</span> <span class="hlt">plate</span> strength, and upper-lower mantle viscosity jump are also important controls in thermo-mechanical subduction. For intermediate upper-lower mantle viscosity jumps (×30), our regimes reproduce the diverse range of seismically imaged slab morphologies.</p> <div class="credits"> <p class="dwt_author">Garel, F.; Goes, S.; Davies, D. R.; Davies, J. H.; Kramer, S. C.; Wilson, C. R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">20</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.T43D2696B"> <span id="translatedtitle"><span class="hlt">Plate</span> boundary and major fault system in the <span class="hlt">overriding</span> <span class="hlt">plate</span> within the Shumagin gap at the Alaska-Aleutian subduction zone</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Structure in the <span class="hlt">overriding</span> <span class="hlt">plate</span> is one of the parameters that may increase the tsunamigenic potential of a subduction zone but also influence the seismogenic behavior and segmentation of great earthquake rupture. The Alaska-Aleutian margin is characterized by along-strike changes in <span class="hlt">plate</span> interface coupling over relatively small distances. Here, we present trench normal multichannel seismic (MCS) profiles acquired across the Shumagin gap that has not broken in many decades and appears to be weakly coupled. The high fold, deep penetration (636 channel, 8-km long streamer, 6600 cu.in airgun source) MCS data were acquired as part of the ALEUT project. This dataset gives us critical new constraints on the interplate boundary that can be traced over ~100 km distance beneath the forearc with high variation in its reflection response with depth. These profiles also reveal the detailed upper <span class="hlt">plate</span> fault structure and forearc morphology. Clear reflections in the <span class="hlt">overriding</span> <span class="hlt">plate</span> appear to delineate one or more large faults that cross the shelf and the upper slope. These faults are observed 75 km back from the trench and seem to branch at depth and connect to the <span class="hlt">plate</span> interface within this gap at ~11 s twtt. We compare the reflective structure of these faults to that of the <span class="hlt">plate</span> boundary and examine where it intersects the megathrust with respect of the expected downdip limit of coupling. We also compare this major structure with the seismicity recorded in this sector. The imaged fault system is associated with a large deep basin (~6s twt) that is an inherited structure formed during the pre-Aleutian period. Basins faults appear to have accommodated primarily normal motion, although folding of sediments near the fault and complicated fault geometries in the shallow section may indicate that this fault has accommodated other types of motion during its history that may reflect the stress-state at the megathrust over time. The deformation within the youngest sediment also suggests also that this fault system might be still active. The coincident wide-angle seismic data coincident with one MCS profile allow the addition of more information about the deep P-wave velocity structure whereas the streamer tomography (Michaelson-Rotermund et al., this session) around the fault system add more detailed view into the complex structure in the shallow portions (upper 2km) of these structures showing a low velocity zone along one large fault suggesting that this fault is still active. These large-scale structures imaged in the <span class="hlt">overriding</span> <span class="hlt">plate</span> within the Shumagin gap are probably sufficiently profound to play a major role in the behavior of the megathrust in this area, segmentation of great earthquake rupture area, tsunami generation and may influence the frictional properties of the seismogenic zone at depth.</p> <div class="credits"> <p class="dwt_author">Becel, A.; Shillington, D. J.; Nedimovic, M. R.; Keranen, K. M.; Li, J.; Webb, S. C.; Kuehn, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_1");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a style="font-weight: bold;">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a 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href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_3");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">21</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51742032"> <span id="translatedtitle">Flow Pattern of the Island-Arc Rock-Mass under the Japan Trench Inner-slope <span class="hlt">overriding</span> the Subducting Oceanic <span class="hlt">Plate</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper reports that a flow pattern of the island-arc rock-mass was revealed on the seismic reflection profile under the Japan Trench Inner-slope, off Sanriku, <span class="hlt">overriding</span> the subducting oceanic <span class="hlt">plate</span>. An example of the seismic reflection profile is presented. The flow pattern is featured by the combination of the partial flat slip-planes and the large-scale dipping fault plane. This flow</p> <div class="credits"> <p class="dwt_author">S. Nagumo; T. Tsuru</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">22</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54810463"> <span id="translatedtitle">Crustal Structure and Deformation of the Incoming and <span class="hlt">Overriding</span> <span class="hlt">Plates</span> of the North Chilean Subduction Zone, 21-23.5°S</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We present multichannel seismic (MCS) reflection images of the structure of the subduction zone of northern Chile. We focus on 3 MCS lines from the cruise Sonne 104, collected with a 3-km-long, 120 channel streamer and a 3124 c.i. well-tuned airgun array. Two lines are ~450 km long each, and image the structure of the <span class="hlt">overriding</span> <span class="hlt">plate</span> and some ~350</p> <div class="credits"> <p class="dwt_author">A. Calahorrano; C. R. Ranero; U. Barckhausen; C. Reichert; I. Grevemeyer</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">23</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.8172G"> <span id="translatedtitle">Role of strain weakening on <span class="hlt">continental</span> <span class="hlt">plate</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Much debate exists concerning the strength distribution of the <span class="hlt">continental</span> lithosphere, how it controls lithosphere-scale strain localization and hence enables <span class="hlt">plate</span> tectonics. No rheological model proposed to date is comprehensive enough to describe both the weakness of <span class="hlt">plate</span> boundary and rigid-like behaviour of <span class="hlt">plate</span> interiors. Here we show that the duality of strength of the lithosphere corresponds to different stages of microstructural evolution. Geological constraints on lithospheric strength and large strain numerical experiments reveal that the development of layers containing weak minerals and the onset of grain boundary sliding upon grain size reduction in olivine cause strain localisation and reduce strength in the crust and subcontinental mantle, respectively. The positive feedback between weakening and strain localization leads to the progressive development of weak <span class="hlt">plate</span> boundaries while <span class="hlt">plate</span> interiors remain strong.</p> <div class="credits"> <p class="dwt_author">Gueydan, Frédéric; Precigout, Jacques; Montesi, Laurent</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">24</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2010-title30-vol2/pdf/CFR-2010-title30-vol2-sec281-31.pdf"> <span id="translatedtitle">30 CFR 281.31 - <span class="hlt">Overriding</span> royalties.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p class="result-summary">...INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL, GAS, AND SULPHUR IN THE OUTER <span class="hlt">CONTINENTAL</span> SHELF Financial Considerations § 281.31 <span class="hlt">Overriding</span> royalties. (a) Subject to the approval of the Secretary, an...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2010-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">25</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2009-title30-vol2/pdf/CFR-2009-title30-vol2-sec281-31.pdf"> <span id="translatedtitle">30 CFR 281.31 - <span class="hlt">Overriding</span> royalties.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p class="result-summary">...INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL, GAS, AND SULPHUR IN THE OUTER <span class="hlt">CONTINENTAL</span> SHELF Financial Considerations § 281.31 <span class="hlt">Overriding</span> royalties. (a) Subject to the approval of the Secretary, an...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2009-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">26</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.T43D2695M"> <span id="translatedtitle">Deciphering the mechanics of an imaged fault system in the <span class="hlt">over-riding</span> <span class="hlt">plate</span> at the Shumagin Seismic Gap, Alaska subduction zone using MCS waveform tomography</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The 2011 ALEUT program acquired 3500 km of multichannel seismic (MCS) data along a part of the western Alaska subduction zone, from the freely slipping Shumagin Seismic Gap to the locked regions in the Semidi segment and the western Kodiak asperity. The MCS profiles were acquired on the R/V Langseth using two 8-km-long streamers and span the entire locked zone on the megathrust, including the updip and downdip transitions to stable sliding. The primary goal was to characterize variations in the geometry and properties of the megathrust and the downgoing <span class="hlt">plate</span> and relate them to downdip and along-strike changes in slip behavior and seismogenesis. The images capture the targeted megathrust reflectivity and its spatial variation. Notably, the two westernmost profiles show reflections arising from a major fault in the <span class="hlt">overriding</span> <span class="hlt">plate</span> within the Shumagin Seismic Gap located 75 km from the trench, which can be followed from the seafloor to the megathrust. The imaged normal fault bounds the seaward end of the Sanak forearc Cenozoic basin, formed after the Early Eocene reorganization of the Alaska subduction zone. The new reflection images also show that the seaward pair of the previously interpreted growth faults, thought to indicate deposition contemporaneous with basin subsidence, is a part of the imaged fault system. The unexpected imaging of this major fault system in the <span class="hlt">over-riding</span> <span class="hlt">plate</span> raises important questions: Has this fault been active during the most recent nearby megathrust earthquakes, such as the 1946 and 1948 earthquakes? Was the Sanak basin formed as a result of slip on the imaged normal fault system or is it a result of growth faulting that predates the formation of this fault? The timing and style of deformation on this fault has significant implications for both coupling on the megathrust seaward and landward of where the normal fault roots and tsunamigenesis. To complement constraints on the geometry and reflection characteristics of this structure from MCS [Bécel et al., this session] we have applied full waveform tomography to the prestack MCS data with the goal to form high-resolution velocity profiles for the shallow sections of the normal fault. The starting velocity model for waveform inversion was formed by traveltime tomography on picked refracted arrivals found at offsets from ~5-8 km. The preliminary, phase-only results along one profile show velocities reducing laterally across the shallow end of the normal fault by 200 m/s (from 2200 to 2000 m/s). We interpret this reduction in velocities to indicate that the fault system is active and that fluid flow may be involved. Some authors suggest that low or zero friction is a required mechanical condition to allow slip on such a normal fault system [McKenzie and Jackson, 2012]. Consequently, the obtained results could prove important to re-assessing both the tsunami risk and the <span class="hlt">plate</span> interface coupling in the Shumagin Seismic Gap area.</p> <div class="credits"> <p class="dwt_author">Michaelson, C. A.; Delescluse, M.; Becel, A.; Nedimovic, M. R.; Shillington, D. J.; Louden, K. E.; Webb, S. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">27</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUSM.V51A..06M"> <span id="translatedtitle">Accretion of a Small <span class="hlt">Continental</span> Fragment to a Larger <span class="hlt">Continental</span> <span class="hlt">Plate</span>: Mesozoic Ecuador as a Case-Study Area</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Only a few regions on Earth are appropriate to study processes that have happened in deeper crustal levels during the accretion of a microplate to a larger <span class="hlt">continental</span> <span class="hlt">plate</span>. Ecuador is one of these regions where in middle Mesozoic times a small <span class="hlt">continental</span> fragment collided with the South-American <span class="hlt">plate</span>. Along the suture between both <span class="hlt">plates</span>, which occurs close to the present volcanic belt of Ecuador, high-pressure (HP) metamorphic rocks developed. These rocks, which are metapelites, metabasites, and metagranitoids, record processes during the microcontinent-continent collision (Massonne and Toulkeridis, 2012, Int. Geol. Rev. 54). The pressures, determined for the HP rocks, were as high as 14 kbar at temperatures somewhat above 500°C. The HP stage was followed by slight heating at the early exhumation. Peak temperatures up to 560°C were reached at pressures ?10 kbar. This HP metamorphism was caused by the collision of the microplate with the South-American <span class="hlt">plate</span> resulting in crustal thickening. The ascent of the HP rocks occurred in an exhumation channel. Before the collision, an oceanic basin existed between these <span class="hlt">plates</span>. Probably, it was narrow as eclogite bodies are lacking in the N-S trending HP belt of Ecuador. Such bodies, especially if the eclogites had experienced pressures in excess of 20 kbar, are markers of a collision of major <span class="hlt">continental</span> <span class="hlt">plates</span> in Phanerozoic times with originally extended oceanic basins between these <span class="hlt">plates</span>. In a more global context, the narrow ocean between the microplate and the South American continent is assumed to have been the westernmost portion of the Neo-Tethys which had extended to completely separate the two major fragments of former Pangaea before the opening of the southern Atlantic Ocean. This opening caused the closure of the narrow Neo-Tethys segment between the colliding microplate and the South American <span class="hlt">plate</span>. This segment was bordered by E-W trending transform faults. A fault system (La Palma - El Guayabo fault, Tahuin Dam fault) in southern Ecuador represents the southern termination of the segment and the microplate as well. The northern termination is characterized by faults bordering the Caribbean <span class="hlt">plate</span>. As the Antarctic Ocean also opened in late Mesozoic times, the addressed transform faults became compressional strike-slip faults which caused crustal thickening during their activity. In their environment HP rocks also formed and were exhumed in an exhumation channel. At the end of the Mesozoic, oceanic crust of the Nasca <span class="hlt">plate</span> started to be subducted below the accreted microcontinent. This process, which resulted in the formation of the prominent magmatic arc in Ecuador and Columbia in Tertiary times, is still ongoing.</p> <div class="credits"> <p class="dwt_author">Massonne, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">28</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56479454"> <span id="translatedtitle">The Peruvian <span class="hlt">Continental</span> Margin: Results from wide angle seismic Data</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Within the scope of the GEOPECO (Geophysical Experiments at the Peruvian <span class="hlt">Continental</span> Margin) project, seismic investigations along the Pacific margin of Peru were carried out using ocean bottom hydrophones (OBH) and seismometers (OBS) recording marine airgun shots. The structure and the P- wave velocity of the oblique subducting Nazca and <span class="hlt">overriding</span> South-American <span class="hlt">Plates</span> from 8°S to 15°S were determined by</p> <div class="credits"> <p class="dwt_author">A. Krabbenhoeft; J. Bialas; H. Kopp; N. Kukowski; C. Huebscher</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">29</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19870000159&hterms=push+pull&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2522push%2Bpull%2522"> <span id="translatedtitle"><span class="hlt">Overriding</span> Faulty Circuit Breakers</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Retainer keeps power on in emergency. Simple mechanical device attaches to failed aircraft-type push/pull circuit breaker to restore electrical power temporarily until breaker replaced. Device holds push/pull button in closed position; unnecessary for crewmember to hold button in position by continual finger pressure. Sleeve and plug hold button in, <span class="hlt">overriding</span> mechanical failure in circuit breaker. Windows in sleeve show button position.</p> <div class="credits"> <p class="dwt_author">Robbins, Richard L.; Pierson, Thomas E.</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">30</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1611957C"> <span id="translatedtitle">Large earthquakes in stable <span class="hlt">continental</span> <span class="hlt">plate</span> interiors: the need for a new paradigm</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The occurrence of large earthquakes in stable <span class="hlt">continental</span> <span class="hlt">plate</span> interiors has so far resisted our understanding. Contrary to <span class="hlt">plate</span> boundary settings, where a balance is achieved over <1000 years between the rates at which strain accumulates and is released in large events, intraplate earthquakes occur in regions where no discernable strain is building up today. In the absence of current strain accumulation, their triggering mechanism remains elusive, as well as the mechanism by which faults having already ruptured in large events might be reloaded to permit sequences of large events, such as in the New Madrid, Central-Eastern U.S., sequence. Earthquake activity in such settings does not seem to be persistent at the location of past large historical earthquakes, which appear to be episodic, clustered and spatially migrating through time. The relationship between long-term geological structures and earthquakes is poorly understood and the ability of intraplate current producing M3-4 events to rupture in M6 and larger earthquakes is unknown. Finally, the fact that the steady-state <span class="hlt">plate</span> boundary model -- which forms the basis for seismic hazard estimation -- does not seem to hold in <span class="hlt">continental</span> interiors makes accurate seismic hazard estimation in such setting particularly challenging. We will review these issues and argue that our understanding of earthquakes in <span class="hlt">continental</span> <span class="hlt">plate</span> interiors requires a paradigm shift.</p> <div class="credits"> <p class="dwt_author">Calais, Eric; Camelbeeck, Thierry; Stein, Seth</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">31</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008AGUFM.T31E..03C"> <span id="translatedtitle">Coupling of strain rate, orogen width and <span class="hlt">plate</span> convergence speed in <span class="hlt">continental</span> collisions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Most models that describe the distributed nature of <span class="hlt">continental</span> deformation predict the propagation of strain and high topography away from the <span class="hlt">plate</span> boundary. Yet a growing body of evidence in the Tibetan orogen suggests that deformation occurred early in the orogen's history at the far northern extent of the modern plateau and thus, our current mechanical understanding of orogenic plateau development is incomplete. Regardless of whether or not high topography was built simultaneously as a result of this deformation, early Cenozoic - present deformation in northern Tibet signifies that the modern limit of the orogen has been held fixed since <span class="hlt">continental</span> collision began. Therefore strain has not significantly propagated further away from the <span class="hlt">plate</span> boundary in time and the orogen width has narrowed as convergence continued since collision. Using a uniform average strain rate across the plateau derived from geodetic measurements, I predict changes in <span class="hlt">plate</span> convergence rate through time as the orogen narrows. Observed decreases in <span class="hlt">plate</span> convergence speed of India with respect to Eurasia through the Cenozoic (Molnar and Stock, in press) can be explained by the simple condition of a fixed orogen boundary and constant strain rate. This same relationship can also be derived for the Arabian-Eurasia collision however fewer geologic data and fewer <span class="hlt">plate</span> velocity measurements are available to constrain such a model compared to Tibet.</p> <div class="credits"> <p class="dwt_author">Clark, M. K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">32</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/655513"> <span id="translatedtitle">Role of <span class="hlt">plate</span> kinematics and <span class="hlt">plate</span>-slip-vector partitioning in <span class="hlt">continental</span> magmatic arcs: Evidence from the Cordillera Blanca, Peru</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">New structural and geochronological data from the Cordillera Blanca batholith in the Peruvian Andes, coupled with Nazca-South American <span class="hlt">plate</span>-slip-vector data, indicate that oblique convergence and associated strike-slip partitioning strongly influenced <span class="hlt">continental</span> magmatic arc evolution. Both the strain field and mode of magmatism (plutonism vs. volcanism) in the late Miocene Peruvian Andes were controlled by the degree to which the arc-parallel component of the <span class="hlt">plate</span> slip vector was partitioned into the arc. Strong strike-slip partitioning at ca. 8 Ma produced arc-parallel sinistral shear, strike-slip intercordilleran basins and east-west-oriented tension fractures that facilitated emplacement of the Cordillera Blanca batholith (ca. 8.2 {+-} 0.2 Ma). Periods during which the strike-slip component was not partitioned into the arc (ca. 10 and ca. 7 Ma) were associated with roughly arc-normal contraction and ignimbrite volcanism. The data thus support the contention that contraction within <span class="hlt">continental</span> magmatic arcs favors volcanism, whereas transcurrent shear favors plutonism. The tie between oblique convergence and batholith emplacement in late Miocene Peruvian Andes provides a modern analogue for batholiths emplaced as the result of transcurrent shear in ancient arcs.</p> <div class="credits"> <p class="dwt_author">McNulty, B.A. [California State Univ., Carson, CA (United States). Dept. of Earth Sciences] [California State Univ., Carson, CA (United States). Dept. of Earth Sciences; Farber, D.L. [Lawrence Livermore National Lab., CA (United States). Inst. of Geophysics and Planetary Physics] [Lawrence Livermore National Lab., CA (United States). Inst. of Geophysics and Planetary Physics; Wallace, G.S.; Lopez, R. [Univ. of California, Santa Cruz, CA (United States). Earth Science Dept.] [Univ. of California, Santa Cruz, CA (United States). Earth Science Dept.; Palacios, O. [Inst. de Geologico Minero y Metalurgico, Lima (Peru)] [Inst. de Geologico Minero y Metalurgico, Lima (Peru)</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">33</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6421776"> <span id="translatedtitle">Gulf of Mexico <span class="hlt">plate</span> reconstruction by palinspastic restoration of extended <span class="hlt">continental</span> crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">In this study, total tectonic subsidence analysis was used to estimate the mount of crust extension in the Gulf of Mexico to determine its effects on the proposed <span class="hlt">plate</span> reconstructions. This involves the calculation and mapping of the sediment-unloaded-basement depth from observations of the basement depth, water depth, and sediment compaction properties. The well-known depth-age relation for oceanic crust and a model for the subsidence of extended <span class="hlt">continental</span> crust allowed within the limits of available data the identification and mapping of crust type and the amount of extension of transitional crust. The zone of extended <span class="hlt">continental</span> crust under the northern margin of the Gulf is extraordinarily wide, more than 800 km (500 mi) in a cross section through east Texas. The zone of extended crust to the south is much narrower, about 150 km (90 mi) on the margin of the Yucatan Block. Palinspastic restoration shows that the total 950 km (590 mi) of extended and thinned <span class="hlt">continental</span> crust corresponds to 490 km (300 mi) of <span class="hlt">continental</span> crust of original thickness. Therefore 460 km (280 mi) of crustal extension occurred during rifting and prior to ocean crust formation. The 460 km (280 mi) of extension along this cross section, and the results of similar calculations on the other cross sections, must be accounted for properly when reconstructing the prerift configuration of the Gulf of Mexico.</p> <div class="credits"> <p class="dwt_author">Sawyer, D.S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">34</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005AGUFMIN51A0312S"> <span id="translatedtitle">Introduction to TETHYS - an Interdisciplinary GIS Database for Studying <span class="hlt">Continental</span> <span class="hlt">Plate</span> Collisions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The TETHYS GIS database has been developed to integrate, visualize, and analyze geologic, geophysical, geochemical, geochronologic, and remote sensing data sets bearing on Tethyan <span class="hlt">continental</span> <span class="hlt">plate</span> collisions. The project is predicated on a need for actualistic model 'templates' for interpreting the Earth's geologic record. The Tethyan belt extends from the western Mediterranean through Asia Minor and Central Eurasia, to east and Southeast Asia and marks successive closure of the Tethyan oceans. Because of their time-transgressive character, Tethyan collisions offer natural laboratories for examining features such as <span class="hlt">continental</span> `escape', collision-induced upper mantle flow magmatism, and marginal basin opening, associated with modern convergent <span class="hlt">plate</span> margins. Large integrated geochemical and geophysical databases allow for such models to be tested against the geologic record, leading to a better understanding of <span class="hlt">continental</span> accretion throughout Earth history. The TETHYS database combines digital topographic and geologic information, remote sensing images, sample-based geochemical, geochronologic, and isotopic data (for pre- and post-collision igneous activity), and data for seismic tomography, shear-wave splitting, space geodesy, and information for <span class="hlt">plate</span> tectonics reconstructions. For the GIS, Oracle 9i is being used as a database engine. The database system is integrated with ArcGIS and ArcIMS (ARC Internet Map Server) using ArcSDE (ARC Spatial Database Engine). Analysis of data is aided by a suite of interactive custom tools and graphic objects including pixel ID, stretching, profiles, histograms, focal mechanisms, x-y plots, and 3-D visualization tools. The latter is enabling interactive visualization of seismic tomography data for the solid earth. We are currently working on expanding our database and on adding additional tools for data analysis and visualization. Interim partial access to the data and metadata is available at: http://www.esrs.wmich.edu/tethys/ http://geoinfo.geosc.uh.edu/Tethys/</p> <div class="credits"> <p class="dwt_author">Sultan, M.; Sandvol, E.; Khan, S. D.; Flower, M.; Manocha, N.; Markondiah Jayaprakash, S.; Becker, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">35</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012EGUGA..14.7659J"> <span id="translatedtitle">Changes in <span class="hlt">plate</span> motion and vertical movements along passive <span class="hlt">continental</span> margins</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The origin of the forces that produce elevated, passive <span class="hlt">continental</span> margins (EPCMs) has been a hot topic in geoscience for many years. Studies of individual margins have led to models, which explain high elevations by invoking specific conditions for each margin in question. We have studied the uplift history of several margins and have found some striking coincidences between episodes of uplift and changes in <span class="hlt">plate</span> motion. In the Campanian, Eocene and Miocene, pronounced events of uplift and erosion affected not only SE Brazil (Cobbold et al., 2001), but also NE Brazil and SW Africa (Japsen et al., 2012a). The uplift phases in Brazil also coincided with three main phases of Andean orogeny (Cobbold et al., 2001, 2007). These phases, Peruvian (90-75 Ma), Incaic (50-40 Ma), and Quechuan (25-0 Ma), were also periods of relatively rapid convergence at the Andean margin of South America (Pardo-Casas and Molnar, 1987). Because Campanian uplift in Brazil coincides, not only with rapid convergence at the Andean margin of South America, but also with a decline in Atlantic spreading rate, we suggest that all these uplift events have a common cause, which is lateral resistance to <span class="hlt">plate</span> motion (Japsen et al., 2012a). Because the uplift phases in South America and Africa are common to the margins of two diverging <span class="hlt">plates</span>, we also suggest that the driving forces can transmit across the spreading axis, probably at great depth, e.g. in the asthenosphere (Japsen et al., 2012a). Similarly, a phase of uplift and erosion at the Eocene-Oligocene transition (c. 35 Ma), which affected margins around the North Atlantic, correlates with a major <span class="hlt">plate</span> reorganization there (Japsen et al., 2012b). Passive <span class="hlt">continental</span> margins clearly formed as a result of extension. Despite this, the World Stress Map shows that, where data exist, all EPCMs are today under compression. We maintain that folds, reverse faults, reactivated normal faults and strike-slip faults that are typical of EPCMs are a result of post-rift compression that leads to the formation of EPCMs and that the necessary forces build up during changes in <span class="hlt">plate</span> motion (e.g. Leroy et al., 2004; Cobbold et al., 2010; Japsen et al., 2012a,b).</p> <div class="credits"> <p class="dwt_author">Japsen, P.; Cobbold, P. R.; Chalmers, J. A.; Green, P. F.; Bonow, J. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">36</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFM.T31F..04N"> <span id="translatedtitle">Large vertical motions and basin evolution in the Outer <span class="hlt">Continental</span> Borderland off Southern California associated with <span class="hlt">plate</span> boundary development and <span class="hlt">continental</span> rifting</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">Continental</span> Borderland offshore southern California occupies a strategic position along the <span class="hlt">continental</span> margin. It was the locus of ~75% of Pacific-North America displacement history, it helped accommodate the large-scale (>90°) tectonic rotation of the Western Transverse Ranges province, and is still accommodating potentially 20% of PAC-NAM <span class="hlt">plate</span> motion today. As such, it represents an ideal natural laboratory to investigate <span class="hlt">plate</span> boundary evolution and basin development associated with transform initiation, oblique <span class="hlt">continental</span> rifting, transrotation and transpression. We have been using newly released grids of high-quality industry multichannel seismic (MCS) reflection data, combined with multibeam bathymetry and offshore well data to map and construct digital 3D fault surfaces and stratigraphic reference horizons over large parts of the Outer <span class="hlt">Continental</span> Borderland. These 3D surfaces of structure and stratigraphy can be used to better understand and evaluate regional patterns of uplift, subsidence, fault interaction and other aspects of <span class="hlt">plate</span> boundary deformation. In the northern Outer Borderland, mapping in Santa Cruz basin, and across both Santa Rosa and Santa Cruz-Catalina ridges reveals a pattern of interacting high-and low-angle faults, fault reactivation, basin subsidence, folding, and basin inversion. Subsidence since early-Miocene time is significant (up to 4 km) and is much larger than predicted by simple thermal cooling models of <span class="hlt">continental</span> rifting. This requires additional tectonic components to drive this regional subsidence and subsequent basin inversion. Farther south, a more en echelon pattern of ridges and basins suggests a distributed component of right-lateral shear also contributed to much of the modern Borderland seafloor topography, including major Borderland basins. Vertical motions of uplift and subsidence can be estimated from a prominent early-Miocene unconformity that likely represents a regional, paleo-horizontal, near-paleo-sea-level erosional surface. As such, this paleo-reference datum can be used to reconstruct Borderland forearc basin geometry prior to rifting, subsidence and subsequent basin inversion. Although not well resolved, the age of the regional unconformity appears to be time transgressive, and tends to young to the east and south. This progression may thus correlate with the oblique subduction of the Pacific-Arguello spreading ridge, rather than the onset of later <span class="hlt">continental</span> rifting, as rifting in the Borderland typically progressed to the north and west following each jump in the triple junction farther south. This sequence of: 1) a regional unconformity requiring uplift, 2) followed by subsidence, and 3) later basin inversion to form ridges thus documents an unusual and unexpected pattern of vertical motion reversal associated with the initiation of a predominantly strike-slip PAC-NAM <span class="hlt">plate</span> boundary.</p> <div class="credits"> <p class="dwt_author">Nicholson, C.; Sorlien, C. C.; Schindler, C. S.; De Hoogh, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">37</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6855J"> <span id="translatedtitle">Uplift along passive <span class="hlt">continental</span> margins, changes in <span class="hlt">plate</span> motion and mantle convection</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The origin of the forces that produce elevated, passive <span class="hlt">continental</span> margins (EPCMs) is a hot topic in geoscience. It is, however, a new aspect in the debate that episodes of uplift coincide with changes in <span class="hlt">plate</span> motion. This has been revealed, primarily, by studies of the burial, uplift and exhumation history of EPCMs based on integration on stratigraphic landscape analysis, low-temperature thermochronology and evidence from the geological record (Green et al., 2013). In the Campanian, Eocene and Miocene, uplift and erosion affected the margins of Brazil and Africa (Japsen et al., 2012b). The uplift phases in Brazil coincided with main phases of Andean orogeny which were periods of relatively rapid convergence at the Andean margin of South America (Cobbold et al., 2001). Because Campanian uplift in Brazil coincides, not only with rapid convergence at the Andean margin of South America, but also with a decline in Atlantic spreading rate, Japsen et al. (2012b) suggested that all these uplift events have a common cause, which is lateral resistance to <span class="hlt">plate</span> motion. Because the uplift phases are common to margins of diverging <span class="hlt">plates</span>, it was also suggested that the driving forces can transmit across the spreading axis; probably at great depth, e.g. in the asthenosphere. Late Eocene, Late Miocene and Pliocene uplift and erosion shaped the elevated margin of southern East Greenland (Bonow et al., in review; Japsen et al., in review). These regional uplift phases are synchronous with phases in West Greenland, overlap in time with similar events in North America and Europe and also correlate with changes in <span class="hlt">plate</span> motion. The much higher elevation of East Greenland compared to West Greenland suggests dynamic support in the east from the Iceland plume. Japsen et al. (2012a) pointed out that EPCMs are typically located above thick crust/lithosphere that is closely juxtaposed to thinner crust/lithosphere. The presence of mountains along the Atlantic margin of Brazil and in East and West Greenland, close to where <span class="hlt">continental</span> crust starts to thin towards oceanic crust, illustrates the common association between EPCMs and the edges of cratons. These observations indicate that the elevation of EPCMs may be due to processes operating where there is a rapid change in crustal/lithosphere thickness. Vertical motion of EPCMs may thus be related to lithosphere-scale folding caused by compressive stresses at the edge of a craton (e.g. Cloetingh et al., 2008). The compression may be derived either from orogenies elsewhere on a <span class="hlt">plate</span> or from differential drag at the base of the lithosphere by horizontal asthenospheric flow (Green et al., 2013). Bonow, Japsen, Nielsen. Global Planet. Change in review. Cloetingh, Beekman, Ziegler, van Wees, Sokoutis, 2008. Geol. Soc. Spec. Publ. (London) 306. Cobbold, Meisling, Mount, 2001. AAPG Bull. 85. Green, Lidmar-Bergström, Japsen, Bonow, Chalmers, 2013. GEUS Bull. 2013/30. Japsen, Chalmers, Green, Bonow 2012a, Global Planet. Change 90-91. Japsen, Bonow, Green, Cobbold, Chiossi, Lilletveit, Magnavita, Pedreira, 2012b. GSA Bull. 124. Japsen, Green, Bonow, Nielsen. Global Planet. Change in review.</p> <div class="credits"> <p class="dwt_author">Japsen, Peter; Green, Paul F.; Chalmers, James A.; Bonow, Johan M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">38</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUFM.T13C1891D"> <span id="translatedtitle">Neogene Basin and <span class="hlt">Plate</span> Boundary Development in the Outer <span class="hlt">Continental</span> Borderland Offshore Southern California</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Mapping using recently released industry multichannel seismic reflection data suggests that uplift associated with <span class="hlt">continental</span> rifting has played a major role in the Neogene evolution of the Pacific-North American <span class="hlt">plate</span> boundary in the Outer California <span class="hlt">Continental</span> Borderland. Up to 3-4 km of basin subsidence, followed by basin inversion, has also occurred. These events are associated with oblique crustal rifting and translation of this area away from the Peninsular Ranges located to the east, as the current transform <span class="hlt">plate</span> boundary developed. The lithologies and ages of the horizons mapped in the seismic data were correlated with data from industry exploratory wells and two ODP sites. Bathymetry data were also used to analyze the current seafloor topography. The Nicolas terrane is the inner of two tectonostratigraphic regions that compose the Outer Borderland and represents the forearc basin of the former Farallon-North American subduction zone. Our mapping of the Nicolas terrane extends from San Nicolas Island south to the offshore US-Mexico border, and includes San Nicolas, East and West Cortes, and Velero basins, the intervening highs, and parts of Cortes and Tanner Banks. An unconformity that occurs mostly along the eastern boundary of the Nicolas terrane apparently formed shortly after the widespread deposition of a volcanic sequence of early Miocene age, and cuts down through the pre-Miocene forearc basin strata to acoustic basement. This suggests the boundary is related more to crustal uplift associated with rifting and lower crustal exhumation rather than only to large-scale oblique translation of the Borderland, which has often been previously characterized by either a major strike-slip or normal fault. Faults capable of accommodating large scale strike-slip or other displacement have not been found along much of the heretofore mapped Nicolas terrane boundary. In addition to significant post-uplift basin subsidence, our mapping shows the creation of major fold structures (with anticlines as wide as 50 km and up to 200 km along trend) associated with later basin inversion. A ~3.8 Ma horizon dates the onset of this extensive folding, as well as reverse-fault reactivation, showing that the current basin and ridge topography of the Borderland is relatively young, and not related to earlier tectonic events such as Miocene rifting or ridge subduction. Younger tilted horizons and offset bathymetry suggest that this subsequent folding and faulting has continued through the Quaternary.</p> <div class="credits"> <p class="dwt_author">de Hoogh, G.; Nicholson, C.; Sorlien, C. C.; Francis, R. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">39</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012JGRB..117.8403T"> <span id="translatedtitle">Geodynamic models of terrane accretion: Testing the fate of island arcs, oceanic plateaus, and <span class="hlt">continental</span> fragments in subduction zones</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Crustal growth at convergent margins can occur by the accretion of future allochthonous terranes (FATs), such as island arcs, oceanic plateaus, submarine ridges, and <span class="hlt">continental</span> fragments. Using geodynamic numerical experiments, we demonstrate how crustal properties of FATs impact the amount of FAT crust that is accreted or subducted, the type of accretionary process, and the style of deformation on the <span class="hlt">overriding</span> <span class="hlt">plate</span>. Our results show that (1) accretion of crustal units occurs when there is a weak detachment layer within the FAT, (2) the depth of detachment controls the amount of crust accreted onto the <span class="hlt">overriding</span> <span class="hlt">plate</span>, and (3) lithospheric buoyancy does not prevent FAT subduction during constant convergence. Island arcs, oceanic plateaus, and <span class="hlt">continental</span> fragments will completely subduct, despite having buoyant lithospheric densities, if they have rheologically strong crusts. Weak basal layers, representing pre-existing weaknesses or detachment layers, will either lead to underplating of faulted blocks of FAT crust to the <span class="hlt">overriding</span> <span class="hlt">plate</span> or collision and suturing of an unbroken FAT crust. Our experiments show that the weak, ultramafic layer found at the base of island arcs and oceanic plateaus plays a significant role in terrane accretion. The different types of accretionary processes also affect deformation and uplift patterns in the <span class="hlt">overriding</span> <span class="hlt">plate</span>, trench migration and jumping, and the dip of the <span class="hlt">plate</span> interface. The resulting accreted terranes produced from our numerical experiments resemble observed accreted terranes, such as the Wrangellia Terrane and Klamath Mountain terranes in the North American Cordilleran Belt.</p> <div class="credits"> <p class="dwt_author">Tetreault, J. L.; Buiter, S. J. H.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">40</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.1797B"> <span id="translatedtitle">Shear wave splitting as a tool to understand the interactions between oceanic <span class="hlt">plate</span> tectonics and <span class="hlt">continental</span> dynamics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Subducting slabs are the major actors of oceanic-<span class="hlt">plate</span> domain mantle convection, but their temporally variable pull and interaction with <span class="hlt">continental</span> interiors strongly affect <span class="hlt">continental</span> tectonics. We discuss how seismic anisotropy can be used jointly with global mantle flow models to constrain some of the governing, yet uncertain, parameters controlling such interactions. These include the relative strength of mantle rocks and the degree to which mantle heterogeneity, e.g. as imaged by tomography, actively drives mantle flow. To link geophysical and geological data, it is useful to consider global models with sufficient numerical resolution to allow for testing of regional geodynamic hypotheses, such as to the strength of <span class="hlt">plate</span> boundaries and micro <span class="hlt">plate</span> motions. Recent modeling and imaging results for the southeastern Caribbean, the Alboran/Atlas domain of northwest Africa, and the Middle East Afar/Arabia/Anatolia system show how anisotropy can help track the establishment of whole mantle convection cells, the extent of plume push and spreading, and <span class="hlt">continental</span> keel-related channeling of asthenospheric currents.</p> <div class="credits"> <p class="dwt_author">Becker, Thorsten W.; Miller, Meghan S.; Faccenna, Claudio</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a 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href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_4");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">41</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014Natur.508..245M"> <span id="translatedtitle">Dynamics of <span class="hlt">continental</span> accretion</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Subduction zones become congested when they try to consume buoyant, exotic crust. The accretionary mountain belts (orogens) that form at these convergent <span class="hlt">plate</span> margins have been the principal sites of lateral <span class="hlt">continental</span> growth through Earth's history. Modern examples of accretionary margins are the North American Cordilleras and southwest Pacific subduction zones. The geologic record contains abundant accretionary orogens, such as the Tasmanides, along the eastern margin of the supercontinent Gondwana, and the Altaïdes, which formed on the southern margin of Laurasia. In modern and ancient examples of long-lived accretionary orogens, the <span class="hlt">overriding</span> <span class="hlt">plate</span> is subjected to episodes of crustal extension and back-arc basin development, often related to subduction rollback and transient episodes of orogenesis and crustal shortening, coincident with accretion of exotic crust. Here we present three-dimensional dynamic models that show how accretionary margins evolve from the initial collision, through a period of <span class="hlt">plate</span> margin instability, to re-establishment of a stable convergent margin. The models illustrate how significant curvature of the orogenic system develops, as well as the mechanism for tectonic escape of the back-arc region. The complexity of the morphology and the evolution of the system are caused by lateral rollback of a tightly arcuate trench migrating parallel to the <span class="hlt">plate</span> boundary and orthogonally to the convergence direction. We find geological and geophysical evidence for this process in the Tasmanides of eastern Australia, and infer that this is a recurrent and global phenomenon.</p> <div class="credits"> <p class="dwt_author">Moresi, L.; Betts, P. G.; Miller, M. S.; Cayley, R. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">42</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JVGR..276..152A"> <span id="translatedtitle">Eocene to Quaternary mafic-intermediate volcanism in San Luis Potosí, central Mexico: The transition from Farallon <span class="hlt">plate</span> subduction to intra-<span class="hlt">plate</span> <span class="hlt">continental</span> magmatism</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The San Luis Potosí Volcanic Field (SLPVF) of central Mexico includes volcanic sequences of felsic, intermediate and basic compositions that were erupted as discrete episodes from the Eocene to the Pleistocene. Volcanism was dominated by widespread and voluminous rhyolitic ignimbrites of the mid-Tertiary Ignimbrite Flare-up. However, the complete volcanic history must consider basaltic and andesitic Eocene–Pleistocene volcanic successions that provide key evidence for understanding the geochemical evolution of the volcanism in the SLPVF during this time span. Five sequences are recognized according to their geochemical characteristics, each comprising a volcano-tectonic episode. The first episode comprises basaltic andesites and andesites erupted during three intervals, 45–42 Ma, 36–31 Ma, and 31–30 Ma. The oldest was derived from subduction magmatism, whereas the youngest has an intra-<span class="hlt">plate</span> magmatic signature and this represents the transition from the end of a long lasting subduction regime of the Farallon <span class="hlt">plate</span> to the initiation of intra-<span class="hlt">plate</span> <span class="hlt">continental</span> extension in the North American <span class="hlt">plate</span>. The second episode, at 29.5–28 Ma, comprises a bimodal succession of high-silica rhyolites and alkaline basalts (hawaiites) that are interpreted as magmatism generated in an intra-<span class="hlt">plate</span> <span class="hlt">continental</span> extension regime during the Basin and Range faulting. The third episode, at 21 Ma, is characterized by trachybasalts and trachyandesites that represent mantle basaltic melts that were contaminated through assimilation of the lower crust during advanced stage of intra-<span class="hlt">plate</span> extension that started at Oligocene. The fourth episode includes 12 Ma alkaline basalts and andesites that were erupted from fissures. These mantle derived magmas evolved to andesites by crustal anatexis and crystal fractionation within a continued, extensional, intra-<span class="hlt">plate</span> regime. Lastly, the fifth episode comprises 5.0 to 0.6 Ma alkaline basalts (basanites) containing mantle xenoliths, that were erupted from maars and tuff cones, which are the youngest manifestations of mantle-derived intra-<span class="hlt">plate</span> extensional events. Based upon this volcanic record, the last subduction manifestations of the extinct Farallon <span class="hlt">plate</span> occurred at about 42 Ma, this was followed by a transition to intra-<span class="hlt">plate</span> magmatism between 42 and 31 Ma, and an extensional, intra-<span class="hlt">plate</span> tectonic setting from 31 Ma to almost Present.</p> <div class="credits"> <p class="dwt_author">Aguillón-Robles, Alfredo; Tristán-González, Margarito; de Jesús Aguirre-Díaz, Gerardo; López-Doncel, Rubén A.; Bellon, Hervé; Martínez-Esparza, Gilberto</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">43</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850011189&hterms=Plate+tectonics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DPlate%2Btectonics"> <span id="translatedtitle">Tectonic lineaments in the cenozoic volcanics of southern Guatemala: Evidence for a broad <span class="hlt">continental</span> <span class="hlt">plate</span> boundary zone</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The northern Caribbean <span class="hlt">plate</span> boundary has been undergoing left lateral strike slip motion since middle Tertiary time. The western part of the boundary occurs in a complex tectonic zone in the <span class="hlt">continental</span> crust of Guatemala and southernmost Mexico, along the Chixoy-Polochic, Motogua and possibly Jocotan-Chamelecon faults. Prominent lineaments visible in radar imagery in the Neogene volcanic belt of southern Guatemala and western El Salvador were mapped and interpreted to suggest southwest extensions of this already broad <span class="hlt">plate</span> boundary zone. Because these extensions can be traced beneath Quaternary volcanic cover, it is thought that this newly mapped fault zone is active and is accommodating some of the strain related to motion between the North American and Caribbean <span class="hlt">plates</span>. Onshore exposures of the Motoqua-Polochic fault systems are characterized by abundant, tectonically emplaced ultramafic rocks. A similar mode of emplacement for these off shore ultramafics, is suggested.</p> <div class="credits"> <p class="dwt_author">Baltuck, M.; Dixon, T. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">44</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014GGG....15.1766B"> <span id="translatedtitle"><span class="hlt">Plate</span> rotation during <span class="hlt">continental</span> collision and its relationship with the exhumation of UHP metamorphic terranes: Application to the Norwegian Caledonides</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">variation and asynchronous onset of collision during the convergence of continents can significantly affect the burial and exhumation of subducted <span class="hlt">continental</span> crust. Here we use 3-D numerical models for <span class="hlt">continental</span> collision to discuss how deep burial and exhumation of high and ultrahigh pressure metamorphic (HP/UHP) rocks are enhanced by diachronous collision and the resulting rotation of the colliding <span class="hlt">plates</span>. Rotation during collision locally favors eduction, the inversion of the subduction, and may explain the discontinuous distribution of ultra-high pressure (UHP) terranes along collision zones. For example, the terminal (Scandian) collision of Baltica and Laurentia, which formed the Scandinavian Caledonides, resulted in the exhumation of only one large HP/UHP terrane, the Western Gneiss Complex (WGC), near the southern end of the collision zone. Rotation of the subducting Baltica <span class="hlt">plate</span> during collision may provide an explanation for this distribution. We explore this hypothesis by comparing orthogonal and diachronous collision models and conclude that a diachronous collision can transport <span class="hlt">continental</span> material up to 60 km deeper, and heat material up to 300°C hotter, than an orthogonal collision. Our diachronous collision model predicts that subducted <span class="hlt">continental</span> margin material returns to the surface only in the region where collision initiated. The diachronous collision model is consistent with petrological and geochonological observations from the WGC and makes predictions for the general evolution of the Scandinavian Caledonides. We propose the collision between Laurentia and Baltica started at the southern end of the collisional zone, and propagated northward. This asymmetric geometry resulted in the counter clockwise rotation of Baltica with respect to Laurentia, consistent with paleomagnetic data from other studies. Our model may have applications to other orogens with regional UHP terranes, such as the Dabie Shan and Papua New Guinea cases, where block rotation during exhumation has also been recorded.</p> <div class="credits"> <p class="dwt_author">Bottrill, A. D.; van Hunen, J.; Cuthbert, S. J.; Brueckner, H. K.; Allen, M. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">45</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1984Tecto...3..709A"> <span id="translatedtitle">Archaean <span class="hlt">Plate</span> Tectonics Revisited 2. Paleo-Sea Level Changes, <span class="hlt">Continental</span> Area, Oceanic Heat Loss and the Area-Age Distribution of the Ocean Basins</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In a previous paper, we derived <span class="hlt">plate</span> tectonic models for <span class="hlt">continental</span> accretion from the early Archaean (3800 m.y. B.P.) until the present. The models are dependent upon the number of <span class="hlt">continental</span> masses, the seafloor creation rate and the <span class="hlt">continental</span> surface area. The models can be tested by examining their predictions for three key geological indicators: sea level changes, stable isotopic evolution (e.g., <span class="hlt">continental</span> surface area), and oceanic heat loss. Models of paleo-sea level changes produced by the accretion of the continents reproduce the following features of earth history: (1) greater <span class="hlt">continental</span> emergence (lower sea level) during the Archaean than the Proterozoic; (2) maximum <span class="hlt">continental</span> emergence about 3000 m.y. B.P.; and (3) maximum <span class="hlt">continental</span> submergence (high sea level) from 30 to 125 m.y. B.P. The high sea level stand between 380-525 m.y. B.P. is only weakly reproduced, probably due to the simplified nature of the model. Changes in the number of <span class="hlt">continental</span> masses can result in tectonic erosion or accretion of the continents, with resulting changes in sea level. The two major transgressions in the Phanerozoic, although still requiring some increase in the total terrestrial heat loss, can be sucessfully explained by a combination of increases in <span class="hlt">continental</span> surface area and in seafloor creation rate. Changes in the total heat loss of the ocean basins predicted by our <span class="hlt">plate</span> tectonic models closely parallel the changes in terrestrial heat production predicted by Wasserburg et al. (1964). This result is consistent with thermal history models which assume whole mantle convection. The history of changes in <span class="hlt">continental</span> surface area predicted by our best <span class="hlt">continental</span> accretion models lies within the ranges of estimated <span class="hlt">continental</span> surface area derived from independent geochemical models of isotope evolution.</p> <div class="credits"> <p class="dwt_author">Abbott, Dallas H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">46</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1616304B"> <span id="translatedtitle"><span class="hlt">Plate</span> rotation during <span class="hlt">continental</span> collision and its relationship with the exhumation of UHP metamorphic terranes: application to the Norwegian Caledonides</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Lateral variation and asynchronous onset of collision during the convergence of continents can significantly affect the burial and exhumation of subducting material. We use 3D numerical models for <span class="hlt">continental</span> collision to discuss how deep burial and exhumation of ultra-high pressure metamorphic rocks are enhanced by oblique convergence and resulting rotation of the colliding <span class="hlt">plates</span>. Rotation during collision locally favours eduction, the inversion of the subduction process following ocean slab break-off, and may relate to the discontinuous distribution of ultra-high pressure (UHP) terranes along collision zones. For example the terminal (Scandian) collision of Baltica and Laurentia, which formed the Scandinavian Caledonides resulted in the exhumation of only one large high pressure/ultra-high pressure (HP/UHP) terrane, the Western Gneiss Complex (WGC), near the southern end of the collision zone. Rotation of the subducting Baltica <span class="hlt">plate</span> during collision may provide a likely explanation for this distribution. We explore this hypothesis by comparing orthogonal and oblique collision models and conclude that an oblique collision can transport <span class="hlt">continental</span> material up to 60km deeper, and heat material up to 300°C hotter, than an orthogonal collision. Our oblique collision model predicts that subducted <span class="hlt">continental</span> margin material returns to the surface only in the region where collision initiated. The oblique collision model is consistent with petrological and geochonological observations from the Western Gneiss Complex and makes predictions for the general evolution of the Scandinavian Caledonides. We propose the collision between Laurentia and Baltica started at the southern end of the collisional zone, and propagated northward. This asymmetric geometry resulted in the counter clockwise rotation of Baltica and the northwards movement of Baltica's rotational pole with respect to Laurentia, consistent with paleomagnetic data from other studies. Our model has applications to others orogens with regional UHP terranes, such as the Dabie Shan and Papua New Guinea cases, where block rotation during exhumation has also been recorded.</p> <div class="credits"> <p class="dwt_author">Bottrill, Andrew; van Hunen, Jeroan; Cuthbert, Simon; Allen, Mark; Brueckner, Hannes</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">47</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.T23C2696W"> <span id="translatedtitle">Analog Modeling of <span class="hlt">Continental</span> Lithosphere Subduction</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Lithospheric-scale analog modeling sheds light on the consequences of decoupling within the <span class="hlt">continental</span> lithosphere and along <span class="hlt">plate</span> interfaces during <span class="hlt">continental</span> collision. The model results provide valuable information in terms of strain localization, deformation of the subducting slab and the evolution and architecture of the overlying mountain belt and its topography. A weak layer has been implemented in three-layer models to simulate decoupling along the <span class="hlt">plate</span> interface and at different levels of the lithosphere (brittle-ductile transition, entire lower crust, crust-mantle boundary). Additionally, varying the strength of the mantle lithosphere of both the upper as well as the lower <span class="hlt">plate</span> regulated the degree of <span class="hlt">plate</span> coupling. <span class="hlt">Plate</span> boundaries were orthogonal to the convergence direction. All models emphasize that strong decoupling at the <span class="hlt">plate</span> interface is a pre-requisite for the subduction of <span class="hlt">continental</span> lithosphere. In addition, deformation of the subducting slab was found to be sensitive to the strength contrast between the subduction zone and the mantle lithosphere of the downgoing as well as the upper <span class="hlt">plate</span>. As such, a low strength contrast between the <span class="hlt">plate</span> interface and the lower <span class="hlt">plate</span> leads to deformation of the subducting slab by thickening and the development of a shallow slab. Conversely, when the strength contrast is high, deep slabs evolve which undergo relatively less deformation. Furthermore, the level of decoupling in the downgoing <span class="hlt">plate</span> governs how much <span class="hlt">continental</span> crust is subducted together with the mantle lithosphere. Shallow decoupling, at the brittle-ductile transition, results in subduction of the lower crust whereas small amounts of lower crust are subducted when decoupling occurs at the level of the Moho. Weak <span class="hlt">plate</span> coupling and a weak lower crust of the lower <span class="hlt">plate</span> steer the evolution of mountain belts such that deformation propagates outward, in the direction of the incoming <span class="hlt">plate</span>, by successive imbrication of upper crustal thrust sheets. Such rheological boundary conditions localize deformation along the <span class="hlt">plate</span> interface and within the lower <span class="hlt">plate</span>, subduing the formation of a retro-wedge. The transmission of deformation into the <span class="hlt">overriding</span> <span class="hlt">plate</span> and far away from the <span class="hlt">plate</span> boundary is favored by the presence of a decoupling horizon within the crust of the upper <span class="hlt">plate</span>. The experimental results have implications for collisional zones like the European Alps, the Pyrenees or the Himalayan-Tibetan system, as the well constrained geometry of these mountain belts demands the presence of decoupling horizons at different levels of the crust. In particular, decoupling within the crust of the incoming <span class="hlt">plate</span> resulted in subduction of <span class="hlt">continental</span> lower crust in all of the above-mentioned natural examples. Moreover, the sequence and style of deformation in the upper <span class="hlt">plate</span> is largely determined by the degree of <span class="hlt">plate</span> coupling and the rheology of the upper <span class="hlt">plate</span>. As such, models for the early stages of the formation of the Tibetan plateau far away from the <span class="hlt">plate</span> boundary seem feasible under the conditions of a rheologically decoupled upper <span class="hlt">plate</span>.</p> <div class="credits"> <p class="dwt_author">Willingshofer, E.; Sokoutis, D.; Luth, S.; Beekman, F.; Cloetingh, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">48</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFM.T13I..03M"> <span id="translatedtitle">Relation of <span class="hlt">plate</span> kinematic parameters to deformation along the Andean margin from Late Jurassic to the present</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The geological consequences of temporal and spatial changes in subduction along the Andean margin from 170 Ma to the present were investigated in the context of a recently developed, global <span class="hlt">plate</span> kinematic model. Geological events recorded by the <span class="hlt">overriding</span> <span class="hlt">continental</span> <span class="hlt">plate</span>, including the development of extensional basins, orogeny and crustal growth accompanied by thickening and/or magmatism, were contrasted with the age of the subducting oceanic slab(s), the absolute <span class="hlt">plate</span> velocity of South America both normal and parallel to the trench, and the relative convergence velocity between South America and the subducting slab(s) both normal and parallel to the trench. Preliminary results indicate that the absolute velocity of the <span class="hlt">overriding</span> <span class="hlt">plate</span> is strongly correlated with the extent of crustal extension; the development of marginal basins floored by oceanic crust occurred only when the absolute <span class="hlt">plate</span> velocity of South America was directed away from the trench. This condition did not accompany the development of aborted marginal basins. An abrupt increase in relative convergence rates between the South American continent and the subducting slab also often accompanied the initiation of extension in the <span class="hlt">overriding</span> <span class="hlt">plate</span>. However, high convergence rates primarily accompanied the development of fold and thrust belts, and were linked with plateau uplift. Inter-dependencies between the various parameters are investigated to build a more complete model of conditions necessary for the development of significant geological events along <span class="hlt">continental</span> margins controlled by subduction.</p> <div class="credits"> <p class="dwt_author">Maloney, K. T.; Clarke, G. L.; Quevedo, L. E.; Klepeis, K. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">49</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012DokES.442..220Z"> <span id="translatedtitle">The ancient <span class="hlt">continental</span> margins of the North American and South American <span class="hlt">plates</span> and regularities in the occurrence of oil and gas accumulations in them</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Various stages of the development of sedimentary basins along the ancient margins of the North American and South American <span class="hlt">plates</span> are considered. It is shown that the potential of the oil-and-gas bearing is related to a certain stage of evolution of the basins. For the margins of the North American <span class="hlt">plate</span>, it is the first stage of development in the structure of the ancient Paleozoic <span class="hlt">continental</span> margins that developed under passive tectonic conditions. For the basins along the ancient margins of the South American <span class="hlt">plate</span>, it is the second stage, which is the stage of the formation and development of foredeeps overlaid on the earlier structures. An interesting regularity is displayed: than younger the folding-mountain structures that originated in the distal parts of the <span class="hlt">continental</span> margins, than greater the age range of source rocks in the sedimentary basins preserved there.</p> <div class="credits"> <p class="dwt_author">Zabanbark, A.; Lobkovskii, L. I.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">50</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.T21C..03W"> <span id="translatedtitle">Craton stability and <span class="hlt">continental</span> lithosphere dynamics during plume-<span class="hlt">plate</span> interaction</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Survival of thick cratonic roots in a vigorously convecting mantle system for billions of years has long been studied by the geodynamical community. A high cratonic root strength is generally considered to be the most important factor. We first perform and discuss new numerical models to investigate craton stability in both Newtonian and non-Newtonian rheology in the stagnant lid regime. The results show that only a modest compositional rheological factor of ??=10 with non-Newtonian rheology is required for the survival of cratonic roots in a stagnant lid regime. A larger rheological factor (100 or more) is needed to maintain similar craton longevity in a Newtonian rheology environment. Furthermore, chemical buoyancy plays an important role on craton stability and its evolution, but could only work with suitable compositional rheology. During their long lifespan, cratons experienced a suite of dynamic, tectonothermal events, such as nearby subduction and mantle plume activity. Cratonic nuclei are embedded in shorter-lived, more vulnerable <span class="hlt">continental</span> areas of different thickness, composition and rheology, which would influence the lithosphere dynamic when tectonothermal events happen nearby. South Africa provides a very good example to investigate such dynamic processes as it hosts several cratons and there are many episodic thermal events since the Mesozoic as indicated by a spectrum of magmatic activity. We numerically investigate such an integrated system using the topographic evolution of cratons and surrounding lithosphere as a diagnostic observable. The post-70Ma thinning of pericratonic lithosphere by ~50km around Kaapvaal craton (Mather et al., 2011) is also investigated through our numerical models. The results show that the pericratonic lithosphere cools and grows faster than cratons do, but is also more likely to be effected by episodic thermal events. This leads to surface topography change that is significantly larger around the craton than within the craton itself. Given the considerable debate on the uplift history of southern African plateau (Nyblade and Sleep, 2003), our numerical models that encompass lithospheric heterogeneity within cratons could help to achieve a better understanding of this issue.</p> <div class="credits"> <p class="dwt_author">Wang, H.; Van Hunen, J.; Pearson, D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">51</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUFM.V51H..08H"> <span id="translatedtitle">Cenozoic analogues support a <span class="hlt">plate</span> tectonic origin for the Earth’s earliest <span class="hlt">continental</span> crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Eocene rhyodacite lavas from the Wagwater Basin in eastern Jamaica have adakitic-like major element compositions, low Y and heavy rare Earth element (REE) concentrations and negative Nb and Ta anomalies on a normal mid-ocean ridge basalt normalised multi-element diagram. They also have lower Sr (<400 ppm), MgO (?2.0 wt.%), Ni (mostly ?30 ppm) and Cr (mostly ?40 ppm) concentrations compared to other modern adakites and middle-late Archaean (3.5-2.5 Ga) trondhjemite, tonalite and granodiorite/dacites (TTGs). ?Nd(i) and ?Hf(i) values indicate that the adakites can not been formed by assimilation and fractional crystallisation processes involving any other igneous rock in the area and so the composition of the adakites is the result of the residual mineralogy in the source region. Low Sr and Al2O3 contents indicate a fluid/vapour-absent source with residual plagioclase, and REE systematics point to residual amphibole and garnet in the source region. The plagioclase and garnet residue implies that the Newcastle magmas were derived from partially melting a metabasic protolith at 1.0-1.6 GPa, which would intersect the amphibole dehydration partial melt solidus at ~ 850-900oC. Radiogenic isotopes along with the low MgO, Ni and Cr concentrations in the adakites demonstrate that the garnet amphibolite source region can not be part of (1) the lower Jamaican arc crust, (2) delaminated lower crust or (3) subducted Proto-Caribbean “normal” oceanic crust that may, or may not, have detached. This data, in addition to partial melting models involving a theoretical garnet-amphibolite source region for the Newcastle lavas, shows that the adakites are derived from metamorphosed Caribbean oceanic plateau crust that underthrust Jamaica in the early Tertiary. The underplated oceanic plateau crust partially melted by either (1) influx of basaltic magma during lithospheric extension in the early Tertiary or (2) direct partial melting of the underthrusting (subducting) plateau crust. The Newcastle magmas ascended and erupted without coming into contact with a mantle wedge thus forming the low MgO, Ni and Cr contents. Most Cenozoic adakites have compositions similar to the middle-late Archaean TTG suite of igneous rocks. In contrast, early (>3.5 Ga) Archaean TTG crustal rocks have lower Sr, MgO, Ni and Cr concentrations and prior to this study had no modern adakite analogue. However, the Newcastle adakites have similar compositions to the, early Archaean TTG. The discovery of these rocks has important implications for our understanding of the formation of the Earth’s earliest <span class="hlt">continental</span> crust and so it is proposed that the Newcastle lavas be classified as a unique sub-group of adakites: Jamaican-type adakite.</p> <div class="credits"> <p class="dwt_author">Hastie, A. R.; Kerr, A. C.; Mitchell, S. F.; McDonald, I.; Pearce, J. A.; Millar, I. L.; Wolstencroft, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">52</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ia.usu.edu/viewproject.php?project=ia:15719"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">Students will go over the main points of <span class="hlt">plate</span> tectonics, including the theory of <span class="hlt">continental</span> drift, different types of <span class="hlt">plate</span> boundaries, seafloor spreading, and convection currents. We have been spending time learning about <span class="hlt">plate</span> tectonics. We have discussed the theory of <span class="hlt">continental</span> drift, we have talked about the different types of <span class="hlt">plate</span> boundaries, we have also learned about seafloor spreading and convection currents. <span class="hlt">Plate</span> Boundary Diagram Now is your chance ...</p> <div class="credits"> <p class="dwt_author">Rohlfing, Mrs.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-02-03</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">53</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.1329P"> <span id="translatedtitle">Dynamics of upper mantle rocks decompression melting above hot spots under <span class="hlt">continental</span> <span class="hlt">plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Numeric 2D simulation of the decompression melting above the hot spots (HS) was accomplished under the following conditions: initial temperature within crust mantle section was postulated; thickness of the metasomatized lithospheric mantle is determined by the mantle rheology and position of upper asthenosphere boundary; upper and lower boundaries were postulated to be not permeable and the condition for adhesion and the distribution of temperature (1400-2050°C); lateral boundaries imitated infinity of layer. Sizes and distribution of lateral points, their symmetry, and maximum temperature varied between the thermodynamic condition for existences of perovskite - majorite transition and its excess above transition temperature. Problem was solved numerically a cell-vertex finite volume method for thermo hydrodynamic problems. For increasing convergence of iterative process the method of lower relaxation with different value of relaxation parameter for each equation was used. The method of through calculation was used for the increase in the computing rate for the two-layered upper mantle - lithosphere system. Calculated region was selected as 700 x (2100-4900) km. The time step for the study of the asthenosphere dynamics composed 0.15-0.65 Ma. The following factors controlling the sizes and melting degree of the convective upper mantle, are shown: a) the initial temperature distribution along the section of upper mantleb) sizes and the symmetry of HS, c) temperature excess within the HS above the temperature on the upper and lower mantle border TB=1500-2000oC with 5-15% deviation but not exceed 2350oC. It is found, that appearance of decompression melting with HS presence initiate primitive mantle melting at TB > of 1600oC. Initial upper mantle heating influence on asthenolens dimensions with a constant HS size is controlled mainly by decompression melting degree. Thus, with lateral sizes of HS = 400 km the decompression melting appears at TB > 1600oC and HS temperature (THS) > 1900oC asthenolens size ~700 km. When THS = of 2000oC the maximum melting degree of the primitive mantle is near 40%. An increase in the TB > 1900oC the maximum degree of melting could rich 100% with the same size of decompression melting zone (700 km). We examined decompression melting above the HS having LHS = 100 km - 780 km at a TB 1850- 2100oC with the thickness of lithosphere = 100 km.It is shown that asthenolens size (Lln) does not change substantially: Lln=700 km at LHS = of 100 km; Lln= 800 km at LHS = of 780 km. In presence of asymmetry of large HS the region of advection is developed above the HS maximum with the formation of asymmetrical cell. Influence of lithospheric <span class="hlt">plate</span> thicknesses on appearance and evolution of asthenolens above the HS were investigated for the model stepped profile for the TB ? of 1750oS with Lhs = 100km and maximum of THS =2350oC. With an increase of TB the Lln difference beneath lithospheric steps is leveled with retention of a certain difference to melting degrees and time of the melting appearance a top of the HS. RFBR grant 12-05-00625.</p> <div class="credits"> <p class="dwt_author">Perepechko, Yury; Sorokin, Konstantin; Sharapov, Victor</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">54</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/42008507"> <span id="translatedtitle">GPS constraints on <span class="hlt">continental</span> deformation in the Africa-Arabia-Eurasia <span class="hlt">continental</span> collision zone and implications for the dynamics of <span class="hlt">plate</span> interactions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The GPS-derived velocity field (1988-2005) for the zone of interaction of the Arabian, African (Nubian, Somalian), and Eurasian <span class="hlt">plates</span> indicates counterclockwise rotation of a broad area of the Earth's surface including the Arabian <span class="hlt">plate</span>, adjacent parts of the Zagros and central Iran, Turkey, and the Aegean\\/Peloponnesus relative to Eurasia at rates in the range of 20-30 mm\\/yr. This relatively rapid</p> <div class="credits"> <p class="dwt_author">Robert Reilinger; Simon McClusky; Philippe Vernant; Shawn Lawrence; Semih Ergintav; Rahsan Cakmak; Haluk Ozener; Fakhraddin Kadirov; Ibrahim Guliev; Ruben Stepanyan; Merab Nadariya; Galaktion Hahubia; Salah Mahmoud; K. Sakr; Abdullah ArRajehi; Demitris Paradissis; A. Al-Aydrus; Mikhail Prilepin; Tamara Guseva; Emre Evren; Andriy Dmitrotsa; S. V. Filikov; Francisco Gomez; Riad Al-Ghazzi; Gebran Karam</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">55</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006JSG....28.2049S"> <span id="translatedtitle">Tectonic isolation of the Levant basin offshore Galilee-Lebanon effects of the Dead Sea fault <span class="hlt">plate</span> boundary on the Levant <span class="hlt">continental</span> margin, eastern Mediterranean</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">continental</span> margin of the central Levant, offshore northern Israel and southern Lebanon is characterized by a sharp <span class="hlt">continental</span>-oceanic crustal transition, exhibited on the bathymetry as a steep <span class="hlt">continental</span> slope. At the base of the slope a narrow zone of faulting deforms the upper Messinian-recent sedimentary sequence. Further into the basin no major deformations are observed. However, onland a restraining bend along the Dead Sea fault <span class="hlt">plate</span> boundary results in the formation of the Lebanon and anti-Lebanon mountain ranges, which exhibit a large positive isostatic anomaly not compensated at depth. All these geologic features follow a NNE-SSW trend. A dense network of multi-channel and single-channel seismic profiles, covering 5000 km of ship-track offshore northern Israel and southern Lebanon, was analyzed for the purpose of characterizing the <span class="hlt">continental</span> margin. Additional seismic surveys covering the area between the Levant margin and the Cyprean arc were examined. Data were then incorporated with magnetic, gravity and earthquake measurements to reveal the deep crustal structure of the area and integrated with bathymetry data to describe the behavior of the young sedimentary basin fill. Results indicate that the Levant basin, offshore northern Israel and southern Lebanon (up to Beirut) is more-or-less unaffected by the intense tectonic deformation occurring onland. The transition between the deformed area onland and the undeformed Levant basin occurs along the base of the <span class="hlt">continental</span> slope. Along the base, the upper Messinian-recent sedimentary sequence is cut by two sets of faults: shallow growth faults resulting from salt tectonics and high angle faults, marking the surface expression of a deeper crustal discontinuity - the marine extension of the Carmel fault zone. The central Levant <span class="hlt">continental</span> margin is being reactivated by transpressional faulting of the marine continuation of the Carmel fault, at the base of the <span class="hlt">continental</span> slope. This fault system coincides with the sharp <span class="hlt">continental</span>-oceanic crustal transition, and acts as an isolator between the Levant basin and its land counterpart. To the north, this feature may initiate the formation of a new triple junction, with the Latakia ridge (part of the eastern Cyprean arc) and the East Anatolian fault.</p> <div class="credits"> <p class="dwt_author">Schattner, U.; Ben-Avraham, Z.; Lazar, M.; Hüebscher, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">56</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013Tectp.594..118F"> <span id="translatedtitle">The role that <span class="hlt">plate</span> tectonics, inferred stress changes and stratigraphic unconformities have on the evolution of the West and Central African Rift System and the Atlantic <span class="hlt">continental</span> margins</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Muglad rift basin of Sudan, is a good example of polyphase rifting, with at least three major phases of basin development. Each phase has resulted in the generation of source rock, reservoir and seal geology with structural traps often closely linked to basement highs. In this paper we investigate on a regional scale the tectonic processes that have contributed to rift basin development. On a regional scale, the evolution of the Africa-wide Mesozoic rift system is intimately linked to relative movements of African sub-<span class="hlt">plates</span> and to global <span class="hlt">plate</span> tectonic processes and <span class="hlt">plate</span> interactions. Changes in <span class="hlt">plate</span> interactions are observed in the oceanic crust as azimuth changes of fracture zone geometries and by inference have caused significant modifications to both the orientation and magnitude of the motions of the African sub-<span class="hlt">plates</span>. Such <span class="hlt">plate</span> motion processes have controlled the polyphase development of the West and Central African Rift System. On the basinal scale, changes of sub-<span class="hlt">plate</span> motions have resulted in changes in the stress field which have had a clear impact on the deformation and fault geometries of rift basins and on the resulting stratigraphy. The construction of the first unified stratigraphic chart for the West and Central African Rift System shows a close correlation in the timing of the major unconformities with the timing of changes in relative <span class="hlt">plate</span> motion as observed in the changes of the azimuthal geometry of the oceanic fracture zones in the Central Atlantic. Since similarly timed unconformities exist along the <span class="hlt">continental</span> margins of Africa and South America, we propose that the causative mechanism is change in relative <span class="hlt">plate</span> motion which leads to an increase or decrease in the tension on the <span class="hlt">plate</span> and thus controls the strength or effective elastic thickness, Te, of the crust/<span class="hlt">plate</span> beneath the margins. This results in a focused change in isostatic response of the margin during short-period changes in relative <span class="hlt">plate</span> motion; i.e. more tension will mean that loads are not compensated locally resulting in local uplift of the margin.</p> <div class="credits"> <p class="dwt_author">Fairhead, J. D.; Green, C. M.; Masterton, S. M.; Guiraud, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">57</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/5486426"> <span id="translatedtitle"><span class="hlt">Continental</span> drilling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The Workshop on <span class="hlt">Continental</span> Drilling was convened to prepare a report for submission to the US Geodynamics Committee with respect to the contribution that could be made by land drilling to resolve major problems of geodynamics and consider the mechanisms by which the responsibility for scientific planning, establishment of priorities, administration, and budgeting for a land-drilling program within the framework of the aims of the Geodynamics Project would best be established. A new and extensive program to study the <span class="hlt">continental</span> crust is outlined in this report. The Workshop focused on the following topics: processes in the <span class="hlt">continental</span> crust (mechanism of faulting and earthquakes, hydrothermal systems and active magma chambers); state and structure of the <span class="hlt">continental</span> crust (heat flow and thermal structure of the crust; state of ambient stress in the North American <span class="hlt">plate</span>; extent, regional structure, and evolution of crystalline <span class="hlt">continental</span> crust); short hole investigations; present state and needs of drilling technology; drill hole experimentation and instrumentation; suggestions for organization and operation of drilling project; and suggested level of effort and funding. Four recommendations are set down. 8 figures, 5 tables. (RWR)</p> <div class="credits"> <p class="dwt_author">Shoemaker, E.M. (ed.)</p> <p class="dwt_publisher"></p> <p class="publishDate">1975-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">58</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1996E%26PSL.143..173C"> <span id="translatedtitle"><span class="hlt">Continental</span> subduction and a mechanism for exhumation of high-pressure metamorphic rocks: new modelling and field data from Oman</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The physical model presented reveals two principal regimes of <span class="hlt">continental</span> subduction: a highly compressional (HC) regime and a low compressional (LC) regime characterised by high and low pressure between the <span class="hlt">overriding</span> and subducting <span class="hlt">plates</span>, respectively. The pressure is inversely proportional to the pull force, which depends on the difference between average density of the subducting lithosphere and density of the mantle. The subducting <span class="hlt">continental</span> crust reaches a maximum depth which is proportional to the strength of the crust, inversely proportional to the interplate pressure, and is ca. 200 km on average. The crust then fails, forming a major crustal thrust. The location of failure depends on the regime of subduction (on the interplate pressure): in the HC regime, failure occurs near the front of the subduction (collision) zone, whereas the crust fails at greater depth under the base of the <span class="hlt">overriding</span> <span class="hlt">plate</span> in the LC regime. The failure is followed by buoyancy-driven uplift of the subducted crustal slice, while the lithospheric mantle keeps subducting. The uplift causes a normal sense displacement (formation of a normal fault) along the upper surface of the crustal slice. For the LC regime (failure of the crust near the base of the <span class="hlt">overriding</span> <span class="hlt">plate</span>), a rapid spontaneous crustal uplift (intrusion into the interplate zone) brings the deeply subducted crust to shallow depths. Under the pressure of this crust the frontal part of the <span class="hlt">overriding</span> <span class="hlt">plate</span> undergoes local extension and then fails, forming a tectonic window. The rising material (the high-pressure rocks) is exhumed within this window. In the HC regime, uplift of the subducted crust, after its failure in front of the <span class="hlt">overriding</span> <span class="hlt">plate</span>, is possible only with erosion of the relief, which provides an unloading effect, allowing the subducted crustal slice to rise up. The exhumation depth is generally smaller in this regime but the volume of the exhumed material is larger. The HC subduction regime has been shown earlier to match the Himalayan situation. The LC regime fits the situation in the Oman Mountains considered in this paper.</p> <div class="credits"> <p class="dwt_author">Chemenda, Alexander I.; Mattauer, Maurice; Bokun, Alexander N.</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">59</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.2596B"> <span id="translatedtitle">A review of Wilson Cycle <span class="hlt">plate</span> margins: What is the role of mantle plumes in <span class="hlt">continental</span> break-up along former sutures?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It was Tuzo Wilson (1966) who recognised that the different faunal distributions on both sides of the present-day North Atlantic Ocean required the existence of an earlier proto-Atlantic Ocean. The observation that the present-day Atlantic Ocean mainly opened along a former suture was a crucial step in the formulation of the Wilson Cycle theory. The theory implies that collision zones are structures that are able to localize extensional deformation for long times after the collision has waned. We review margin pairs around the Atlantic and Indian Oceans with the aim to evaluate the extent to which oceanic opening used former sutures and to analyse the role of mantle plumes in <span class="hlt">continental</span> break-up. We aid our analyses with <span class="hlt">plate</span> tectonic reconstructions using GPlates (www.gplates.org). Already Wilson recognized that Atlantic break-up did not always follow the precise line of previous junction. For example, Atlantic opening did not utilize the Iapetus suture in Great Britain and rather than opening along the younger Rheic suture north of Florida, break-up occurred along the older Pan-African structures south of Florida. As others before us, we find no correlation of suture and break-up age. Often <span class="hlt">continental</span> break-up occurs some hundreds of Myrs after collision, but it may also take more than a Gyr, as for example for Australia-Antarctica and Congo-São Francisco. This places serious constraints on potential collision zone weakening mechanisms. Several studies have pointed to a link between <span class="hlt">continental</span> break-up and large-scale mantle upwellings. It is, however, much debated whether plumes use existing rifts as a pathway, or whether plumes play an active role in causing rifting. It is also important to realise that in several cases break-up cannot be related to plume activity. Examples are the Iberia-Newfoundland, Equatorial Atlantic Ocean, and Australia-Antarctica <span class="hlt">plate</span> margins. For margins that are associated with large igneous provinces (LIPs), we find a positive correlation between break-up age and LIP age. We interpret this to indicate that plumes can aid the factual <span class="hlt">continental</span> break-up. However, plumes may have been guided towards the rift for margins that experienced a long rift history (e.g., Norway-Greenland), to then trigger the break-up. This could offer a partial reconciliation in the debate of a passive or active role for mantle plumes in <span class="hlt">continental</span> break-up. (Wilson, J.T., 1966. Did the Atlantic close and then re-open? Nature 211, 676-681)</p> <div class="credits"> <p class="dwt_author">Buiter, Susanne; Torsvik, Trond</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">60</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUSM.T33A..06G"> <span id="translatedtitle">Subduction to <span class="hlt">Continental</span> Delamination: Insights From Laboratory Experiments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The evolution of the lithosphere through subduction-collision and delamination and its surface/crustal response (topography/deformation) is investigated in this work. We present a series of lithosphere scale two dimensional (2-D) and three dimensional (3-D) laboratory experiments to better understand such processes. In these experiments, an idealized viscously deforming crust-mantle lithosphere-mantle system is configured with silicone putty (representing lithospheric mantle and upper crust) and glucose syrup (representing the upper mantle and lower crust). The initial focus was to investigate the physical development of delamination versus <span class="hlt">continental</span> subduction without <span class="hlt">plate</span> convergence. Experiments show that the delamination or <span class="hlt">continental</span> subduction is strongly dependent on the density of the crust (both crust and mantle lithosphere subducts when crust has a higher density, instead of delamination), while in the investigated range, the viscosity of the weak layer does not have much influence on the process. In all the experiments, the topography is asymmetric with subsidence above the delaminating hinge due to the dynamic vertical pulling driven by the delaminating slab, and uplift above the delaminated region due to the buoyancy of asthenosphere. Our investigation on the oceanic subduction with a convergence rate of ~ 3cm/year <span class="hlt">plate</span> velocity suggests that subduction -collision - delamination is well defined and at the end, the delaminating crust from the lithosphere is overthrusted on top of the <span class="hlt">overriding</span> <span class="hlt">plate</span>. Our results provide integrated insights on the Alpine-Himalayan type orogenies, in particular the neotectonic evolution of Eastern Anatolian plateau.</p> <div class="credits"> <p class="dwt_author">Gogus, O. H.; Corbi, F.; Faccenna, C.; Pysklywec, R. N.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-05-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_2");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a style="font-weight: bold;">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">61</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007AGUFM.T11C0726G"> <span id="translatedtitle">Introducing tectonically and thermo-mechanically realistic lithosphere in the models of plume head -lithosphere interactions (PLI) including intra-<span class="hlt">continental</span> <span class="hlt">plate</span> boundaries.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Plume-Lithosphere Interactions (PLI) in continets have complex topographic and magmatic signatures and are often identified near boundaries between younger <span class="hlt">plates</span> (e.g., orogenic) and older stable <span class="hlt">plates</span> (e.g., cratons), which represent important geometrical, thermal and rheological barriers that interact with the emplacement of the plume head (e.g., Archean West Africa, East Africa, Pannonian - Carpathian system). The observable PLI signatures are conditioned by plume dynamics but also by complex rheology and structure of <span class="hlt">continental</span> lithosphere. We address this problem by considering a new free-surface thermo-mechanical numerical model of PLI with two stratified elasto-viscous-plastic (EVP) <span class="hlt">continental</span> <span class="hlt">plates</span> of contrasting age, thickness and structure. The results show that: (1) surface deformation is poly-harmonic and contains smaller wavelengths (50-500 km) than that associated with the plume head (>1000 km). (2) below intra-<span class="hlt">plate</span> boundaries, plume head flattening is asymmetric, it is blocked from one side by the cold vertical boundary of the older <span class="hlt">plate</span>, which leads to mechanical decoupling of crust from mantle lithosphere, and to localized faulting at the cratonic margin; (2) the return flow from the plume head results in sub-vertical down-thrusting (delamination) of the lithosphere at the margin, producing sharp vertical cold boundary down to the 400 km depth; (3) plume head flattening and migration towards the younger <span class="hlt">plate</span> results in concurrent surface extension above the centre of the plume and in compression (pushing), down-thrusting and magmatic events at the cratonic margin (down-thrusting is also produced at the opposite border of the younger <span class="hlt">plate</span>); these processes may result in <span class="hlt">continental</span> growth at the "craton side"; (4) topographic signatures of PLI show basin-scale uplifts and subsidences preferentially located at cratonic margins. Negative Rayleigh-Taylor instabilities in the lithosphere above the plume head provide a mechanism for crustal delamination. In case of several cratonic blocks, the combined effect of subsidence and lithospheric thinning at cratons edges, while plume head material is being stocked in between the cratons, favours major magmatic events at cratonic margins. Numerous field evidence (West Africa, Western Australia) underline the trapping effect of cratonic margins for formation of (e.g.) orogenic gold deposits, which require particular extreme P-T conditions. Location of gemstones deposits is also associated with cratonic margins, as demonstrated by the Tanzanian Ruby belt. Their formation depend on particularly fast isothermal deepening processes, which can be reproduced by slab-like instabilities induced by plume head-cratonic margin interaction. On the other hand, absence of magmatic events should not be interpreted as evidence for the absence of plume: at surface, these events may not necessary have unambiguous deep geochemical signatures, as the hot source plume material stalls below Moho and forms a long-lasting (10 to 100 Myr) sub-Moho reservoir. This should induce strong crustal melting that may overprint deeper signatures since crustal melts are generated at much lower temperatures than mantle, and produce light low-viscous rapidly ascending magmas. Drip-like down- sagging of the lithospheric mantle and metamorphic lower crustal material inside the plume head may contaminate the latter and also alter the geochemical signature of related magmas.</p> <div class="credits"> <p class="dwt_author">Guillou-Frottier, L.; Burov, E.; Cloetingh, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">62</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011Tecto..30.4004V"> <span id="translatedtitle">Vertical tectonics at a <span class="hlt">continental</span> crust-oceanic plateau <span class="hlt">plate</span> boundary zone: Fission track thermochronology of the Sierra Nevada de Santa Marta, Colombia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The topographically prominent Sierra Nevada de Santa Marta forms part of a faulted block of <span class="hlt">continental</span> crust located along the northern boundary of the South American <span class="hlt">Plate</span>, hosts the highest elevation in the world (˜5.75 km) whose local base is at sea level, and juxtaposes oceanic plateau rocks of the Caribbean <span class="hlt">Plate</span>. Quantification of the amount and timing of exhumation constrains interpretations of the history of the <span class="hlt">plate</span> boundary, and the driving forces of rock uplift along the active margin. The Sierra Nevada Province of the southernmost Sierra Nevada de Santa Marta exhumed at elevated rates (?0.2 Km/My) during 65-58 Ma in response to the collision of the Caribbean Plateau with northwestern South America. A second pulse of exhumation (?0.32 Km/My) during 50-40 Ma was driven by underthrusting of the Caribbean <span class="hlt">Plate</span> beneath northern South America. Subsequent exhumation at 40-25 Ma (?0.15 Km/My) is recorded proximal to the Santa Marta-Bucaramanga Fault. More northerly regions of the Sierra Nevada Province exhumed rapidly during 26-29 Ma (˜0.7 Km/My). Further northward, the Santa Marta Province exhumed at elevated rates during 30-25 Ma and 25-16 Ma. The highest exhumation rates within the Sierra Nevada de Santa Marta progressed toward the northwest via the propagation of NW verging thrusts. Exhumation is not recorded after ˜16 Ma, which is unexpected given the high elevation and high erosive power of the climate, implying that rock and surface uplift that gave rise to the current topography was very recent (i.e., ?1 Ma?), and there has been insufficient time to expose the fossil apatite partial annealing zone.</p> <div class="credits"> <p class="dwt_author">Villagómez, Diego; Spikings, Richard; Mora, AndréS.; GuzmáN, Georgina; Ojeda, GermáN.; CortéS, Elizabeth; van der Lelij, Roelant</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">63</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70015232"> <span id="translatedtitle">Petrology and age of volcanic-arc rocks from the <span class="hlt">continental</span> margin of the Bering Sea: implications for Early Eocene relocation of <span class="hlt">plate</span> boundaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Eocene volcanic flow and dike rocks from the Beringian margin have arc characteristics, implying a convergent history for this region during the early Tertiary. Chemical and mineralogical compositions are similar to those of modern Aleutian-arc lavas. They also resemble volcanic-arc compositions from western mainland Alaska, although greater chemical diversity and a stronger <span class="hlt">continental</span> influence are observed in the Alaskan mainland rocks. Early Eocene ages of 54.4-50.2 Ma for the Beringian samples are well constrained by conventional K-Ar ages of nine plagioclase separates and by concordant 40Ar/39Ar incremental heating and total-fusion experiments. A concordant U-Pb zircon age of 53 Ma for the quartz-diorite dike is in good agreement with the K-Ar data. <span class="hlt">Plate</span> motion studies of the North Pacific Ocean indicate more northerly directed subduction prior to the Tertiary and a continuous belt of arc-type volcanism extending from Siberia, along the Beringian margin, into mainland Alaska. Around 56 Ma (chron 25-24), subduction changed to a more westerly direction and subduction-related volcanism ceased for most of mainland Alaska. The increasingly oblique angle of convergence should have ended subduction along the Beringian margin as well. However, consistent ages of 54-50 Ma indicate a final pulse in arc-type magmatism during this period of <span class="hlt">plate</span> adjustment. -from Authors</p> <div class="credits"> <p class="dwt_author">Davis, A. S.; Pickthorn, L. -B. G.; Vallier, T. L.; Marlow, M. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">64</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19990008343&hterms=global+positioning+system&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2522global%2Bpositioning%2Bsystem%2522"> <span id="translatedtitle"><span class="hlt">Plate</span> Motion and Crustal Deformation Estimated with Geodetic Data from the Global Positioning System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We use geodetic data taken over four years with the Global Positioning System (GPS) to estimate: (1) motion between six major <span class="hlt">plates</span> and (2) motion relative to these <span class="hlt">plates</span> of ten sites in <span class="hlt">plate</span> boundary zones. The degree of consistency between geodetic velocities and rigid <span class="hlt">plates</span> requires the (one-dimensional) standard errors in horizontal velocities to be approx. 2 mm/yr. Each of the 15 angular velocities describing motion between <span class="hlt">plate</span> pairs that we estimate with GPS differs insignificantly from the corresponding angular velocity in global <span class="hlt">plate</span> motion model NUVEL-1A, which averages motion over the past 3 m.y. The motion of the Pacific <span class="hlt">plate</span> relative to both the Eurasian and North American <span class="hlt">plates</span> is observed to be faster than predicted by NUVEL-1A, supporting the inference from Very Long B ase- line Interferometry (VLBI) that motion of the Pacific <span class="hlt">plate</span> has speed up over the past few m.y. The Eurasia-North America pole of rotation is estimated to be north of NUVEL-1A, consistent with the independent hypothesis that the pole has recently migrated northward across northeast Asia to near the Lena River delta. Victoria, which lies above the main thrust at the Cascadia subduction zone, moves relative to the interior of the <span class="hlt">overriding</span> <span class="hlt">plate</span> at 30% of the velocity of the subducting <span class="hlt">plate</span>, reinforcing the conclusion that the thrust there is locked beneath the <span class="hlt">continental</span> shelf and slope.</p> <div class="credits"> <p class="dwt_author">Argus, Donald F.; Heflin, Michael B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">65</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2011-title25-vol1/pdf/CFR-2011-title25-vol1-sec227-26.pdf"> <span id="translatedtitle">25 CFR 227.26 - Assignments and <span class="hlt">overriding</span> royalties.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p class="result-summary">...OF THE INTERIOR ENERGY AND MINERALS LEASING OF CERTAIN LANDS IN WIND RIVER INDIAN RESERVATION, WYOMING, FOR OIL AND GAS MINING Operations § 227.26 Assignments and <span class="hlt">overriding</span> royalties. (a) Leases, or any interest therein,...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">66</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2011-title25-vol1/pdf/CFR-2011-title25-vol1-sec213-38.pdf"> <span id="translatedtitle">25 CFR 213.38 - Assignments and <span class="hlt">overriding</span> royalties.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p class="result-summary">...DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEASING OF RESTRICTED LANDS OF MEMBERS OF FIVE CIVILIZED TRIBES, OKLAHOMA, FOR MINING Operations § 213.38 Assignments and <span class="hlt">overriding</span> royalties. (a) Leases or any interest therein, may...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">67</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2013-title25-vol1/pdf/CFR-2013-title25-vol1-sec227-26.pdf"> <span id="translatedtitle">25 CFR 227.26 - Assignments and <span class="hlt">overriding</span> royalties.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p class="result-summary">...227.26 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEASING OF CERTAIN LANDS IN WIND RIVER INDIAN RESERVATION, WYOMING, FOR OIL AND GAS MINING Operations § 227.26 Assignments and <span class="hlt">overriding</span>...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">68</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003AGUFM.S11G..01H"> <span id="translatedtitle">Subduction Drive of <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Don Anderson emphasizes that <span class="hlt">plate</span> tectonics is self-organizing and is driven by subduction, which rights the density inversion generated as oceanic lithosphere forms by cooling of asthenosphere from the top. The following synthesis owes much to many discussions with him. Hinge rollback is the key to kinematics, and, like the rest of actual <span class="hlt">plate</span> behavior, is incompatible with bottom-up convection drive. Subduction hinges (which are under, not in front of, thin leading parts of arcs and <span class="hlt">overriding</span> <span class="hlt">plates</span>) roll back into subducting <span class="hlt">plates</span>. The Pacific shrinks because bounding hinges roll back into it. Colliding arcs, increasing arc curvatures, back-arc spreading, and advance of small arcs into large <span class="hlt">plates</span> also require rollback. Forearcs of <span class="hlt">overriding</span> <span class="hlt">plates</span> commonly bear basins which preclude shortening of thin <span class="hlt">plate</span> fronts throughout periods recorded by basin strata (100 Ma for Cretaceous and Paleogene California). This requires subequal rates of advance and rollback, and control of both by subduction. Convergence rate is equal to rates of rollback and advance in many systems but is greater in others. <span class="hlt">Plate</span>-related circulation probably is closed above 650 km. Despite the popularity of concepts of plumes from, and subduction into, lower mantle, there is no convincing evidence for, and much evidence against, penetration of the 650 in either direction. That barrier not only has a crossing-inhibiting negative Clapeyron slope but also is a compositional boundary between fractionated (not "primitive"), sluggish lower mantle and fertile, mobile upper mantle. Slabs sink more steeply than they dip. Slabs older than about 60 Ma when their subduction began sink to, and lie down on and depress, the 650-km discontinuity, and are overpassed, whereas younger slabs become neutrally buoyant in mid-upper mantle, into which they are mixed as they too are overpassed. Broadside-sinking old slabs push all upper mantle, from base of oceanic lithosphere down to the 650, back under shrinking oceans, forcing rapid Pacific spreading. Slabs suck forward <span class="hlt">overriding</span> arcs and <span class="hlt">continental</span> lithosphere, plus most subjacent mantle above the transition zone. Changes in sizes of oceans result primarily from transfer of oceanic lithosphere, so backarcs and expanding oceans spread only slowly. Lithosphere parked in, or displaced from, the transition zone, or mixed into mid-upper mantle, is ultimately recycled, and regional variations in age of that submerged lithosphere may account for some regional contrasts in MORB. <span class="hlt">Plate</span> motions make no kinematic sense in either the "hotspot" reference frame (HS; the notion of fixed plumes is easily disproved) or the no-net-rotation frame (NNR) In both, for example, many hinges roll forward, impossible with gravity drive. Subduction-drive predictions are fulfilled, and paleomagnetic data are satisfied (as they are not in HS and NNR), in the alternative framework of propulsionless Antarctica fixed relative to sluggish lower mantle. Passive ridges migrate away from Antarctica on all sides, and migration of these and other ridges permits tapping fresh asthenosphere. (HS and NNR tend to fix ridges). Ridge migration and spreading rates accord with subduction drive. All trenches roll back when allowance is made for back-arc spreading and intracontinental deformation. Africa rotates slowly toward subduction systems in the NE, instead of moving rapidly E as in HS and NNR. Stable NW Eurasia is nearly stationary, instead of also moving rapidly, and S and E Eurasian deformation relates to subduction and rollback. The Americas move Pacificward at almost the full spreading rates of passive ridges behind them. Lithosphere has a slow net westward drift. Reference: W.B. Hamilton, An alternative Earth, GSA Today, in press.</p> <div class="credits"> <p class="dwt_author">Hamilton, W. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">69</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..1214496I"> <span id="translatedtitle">Formation and metasomatism of <span class="hlt">continental</span> lithospheric mantle in intra-<span class="hlt">plate</span> and subduction-related tectonic settings</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Our knowledge of the origin and evolution of the <span class="hlt">continental</span> lithospheric mantle (CLM) remains fragmentary and partly controversial in spite of recent advances in petrologic, geochemical and geophysical studies of the deep Earth and experimental work. Debate continues on a number of essential topics, like relative contributions of partial melting, metasomatism and ‘re-fertilisation' as well as the timing, conditions and tectonic settings of those processes. These topics can be addressed by studies of ultramafic xenoliths in volcanic rocks which arguably provide the least altered samples of modern and ancient CLM. The subcontinental lithosphere is thought to be a mantle region from which melts have been extracted, thus making the lithosphere more refractory. Melting degrees can be estimated from Al contents while the depth of melt extraction can be assessed from Al-Fe (Mg#) relations in unmetasomatized melting residues in comparison with experimental data, e.g. [1]. High silica and opx in the residues may indicate melting in water-rich conditions. High-precision Mg# and Mn for olivine may constrain degrees and conditions of partial melting and/or metasomatism, tectonic settings, modal compositions (e.g. presence of garnet) and equilibration conditions of mantle peridotites [2]. These estimates require both adequate sampling and high-quality major element and modal data; sampling and analytical uncertainties in published work may contribute substantially to chemical heterogeneities (and different origins) inferred for CLM domains [3]. Very fertile peridotite xenolith suites are rare worldwide [3]. They were initially viewed as representing mantle domains that experienced only very small degrees of melt extraction but are attributed by some workers to ‘refertilization' of refractory mantle by percolating asthenospheric melts. Such alternative mechanisms might be valid for some rare hybrid and Fe-enriched peridotites but they fail to comprehensively explain modal, major and trace element and isotope compositions of fertile lherzolites and thus cannot provide viable alternatives to the concept of melt extraction from pristine mantle as the major mechanism of CLM formation. Published data on xenoliths from andesitic volcanoes and on supra-subduction oceanic peridotites [4] show that the most common rocks in mantle wedge lithosphere are highly refractory harzburgites characterized by a combination of variable but generally high modal opx (18-30%) with very low modal cpx (1.5-3%). At a given olivine (or MgO) content, they have higher opx and silica, and lower cpx, Al and Ca contents than normal refractory peridotite xenoliths in <span class="hlt">continental</span> basalts; the Mg-Si and Al-Si trends in those rocks resemble those in cratonic peridotites. These features may indicate either fluid fluxing during melting in the mantle wedge or selective post-melting metasomatic enrichments in silica to transform some olivine to opx. High oxygen fugacities and radiogenic Os-isotope compositions in those rocks may be related to enrichments by slab-derived fluids, but these features are not always coupled with trace element enrichments or patterns commonly attributed to "subduction zone metasomatism" deduced from studies of arc volcanic rocks and experiments. The valuable insights provided by experimental work and xenolith case studies are difficult to apply to many natural peridotite series because late-stage processes commonly overlap the evidence for initial melting. References: [1] Herzberg C., J. Petrol. 45: 2507 (2004). [2] Ionov D. & Sobolev A., GCA 72 (S1): A410 (2008). [3] Ionov D., Contrib. Miner. Petrol. (2007) [4] Ionov D., J. Petrol. doi: 10.1093/petrology/egp090 (2010)</p> <div class="credits"> <p class="dwt_author">Ionov, Dmitri</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">70</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/1082907"> <span id="translatedtitle">Self-assembled software and method of <span class="hlt">overriding</span> software execution</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">A computer-implemented software self-assembled system and method for providing an external <span class="hlt">override</span> and monitoring capability to dynamically self-assembling software containing machines that self-assemble execution sequences and data structures. The method provides an external <span class="hlt">override</span> machine that can be introduced into a system of self-assembling machines while the machines are executing such that the functionality of the executing software can be changed or paused without stopping the code execution and modifying the existing code. Additionally, a monitoring machine can be introduced without stopping code execution that can monitor specified code execution functions by designated machines and communicate the status to an output device.</p> <div class="credits"> <p class="dwt_author">Bouchard, Ann M.; Osbourn, Gordon C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-08</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">71</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.enchantedlearning.com/subjects/astronomy/activities/findit/qtectonics.shtml"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics Quiz</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This quiz for younger students asks them 10 questions about <span class="hlt">plate</span> motions, rock types in <span class="hlt">continental</span> and oceanic crust, crustal formation and mountain building, the supercontinent Pangea, and the theory of <span class="hlt">continental</span> drift. A link to a page on <span class="hlt">continental</span> drift provides information to answer the questions.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">72</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002Geo....30..823G"> <span id="translatedtitle">Far-field <span class="hlt">continental</span> backarc setting for the 1.80 1.67 Ga basins of northeastern Australia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The 1.80 1.67 Ga volcano-sedimentary basins of northeastern Australia, preserved in the Mount Isa inlier, McArthur basin, and Georgetown inlier, have been a cornerstone of nonuniformitarian “intracontinental” tectonic models of the Australian Proterozoic. However, geochronological data show that major tectonothermal events within the basins coincided with significant tectonic events that occurred along a complex convergent <span class="hlt">plate</span> boundary that developed on the southern margin of the proto Australian continent. These data imply a paired evolution, whereby thermal events were shared and <span class="hlt">plate</span>-margin stresses were propagated (to 1500 km) into the <span class="hlt">plate</span> interior. We propose a tectonic model in which the 1.80 1.67 Ga northeastern Australian basins occupied a wide region of intermittently extending <span class="hlt">continental</span> crust in the <span class="hlt">overriding</span> <span class="hlt">plate</span> of a long-lived subduction system—effectively a far-field <span class="hlt">continental</span> backarc setting. The combined effects of slab rollback, accretion, and enhanced subcontinental convection produced an environment of episodic extension, transient shortening, elevated heat flow, and magmatism.</p> <div class="credits"> <p class="dwt_author">Giles, David; Betts, Peter; Lister, Gordon</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">73</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://archinte.ama-assn.org/cgi/reprint/163/21/2625.pdf"> <span id="translatedtitle">Physicians' Decisions to <span class="hlt">Override</span> Computerized Drug Alerts in Primary Care</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Background: Although computerized physician order entry reduces medication errors among inpatients, little is known about the use of this system in primary care. Methods: We calculated the <span class="hlt">override</span> rate among 3481 consecutivealertsgeneratedat5adultprimarycareprac- tices that use a common computerized physician order entry system for prescription writing. For detailed re- view, we selected a random sample of 67 alerts in which physicians</p> <div class="credits"> <p class="dwt_author">Saul N. Weingart; Maria Toth; Daniel Z. Sands; Mark D. Aronson; Roger B. Davis; Russell S. Phillips</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">74</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://interruptions.net/literature/Sijs-JAmMedInformAssoc06.pdf"> <span id="translatedtitle"><span class="hlt">Overriding</span> of Drug Safety Alerts in Computerized Physician Order Entry</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Many computerized physician order entry (CPOE) systems have integrated drug safety alerts. The authors reviewed the literature on physician response to drug safety alerts and interpreted the results using Reason's framework of accident causation. In total, 17 papers met the inclusion criteria. Drug safety alerts are overridden by clinicians in 49% to 96% of cases. Alert <span class="hlt">overriding</span> may often be</p> <div class="credits"> <p class="dwt_author">HELEEN VAN DER SIJS; ARNOLD VULTO; MARC BERG</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">75</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1993Tecto..12..303R"> <span id="translatedtitle">The tectonic expression slab pull at <span class="hlt">continental</span> convergent boundaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Examination of five thrust belt systems developed at <span class="hlt">continental</span> subduction boundaries suggests that they comprise two distinct groups that display pronounced and systematic differences in structural style, topographic elevation, denudation, metamorphism, postcollisional convergence, and foredeep basin geometry and facies. The distinctive geological features developed within each thrust belt group appear to be causally linked to the relative rates of subduction and convergence via the magnitude of horizontal compressional stress transmitted across the subduction boundary. At subduction boundaries where the rate of overall <span class="hlt">plate</span> convergence is less than the rate of subduction (termed here retreating subduction boundaries) the transmission of horizontal compressive stress across the <span class="hlt">plate</span> boundary is small, and regional deformation of the <span class="hlt">overriding</span> <span class="hlt">plate</span> is by horizontal extension. The tectonic expression of these retreating subduction boundaries includes topographically low mountains, little erosion or denudation, low-grade to no metamorphism, little to no involvement of crystalline basement in shortening, little to no postcollisional convergence, anomalously deep foredeep basins, and a protracted history of flysch deposition within the adjacent foredeep basin. Analysis of deflection and gravity data across three retreating subduction boundaries (Apennine, Carpathian and Hellenic systems) shows that subduction is driven by gravitational forces acting on dense subducted slabs at depths between about 40 and 80 km (Carpathians), 50 and 150 km (Apennines) and 50 and 250 km (Hellenides). The total mass anomalies represented by the slabs are approximately 3×1012, 6×1012 and 12×1012 N/m, respectively. The slabs are partially supported by flexural stresses transmitted through the subducted lithosphere to the foreland, and partially supported by dynamic (viscous) stresses in the asthenosphere. At subduction boundaries where the rate of overall <span class="hlt">plate</span> convergence is greater than the rate of subduction (termed here advancing subduction boundaries) the transmission of horizontal compressive stress across the <span class="hlt">plate</span> boundary is large, and regional deformation of the <span class="hlt">overriding</span> <span class="hlt">plate</span> is by horizontal shortening. The tectonic expression of these advancing subduction boundaries includes topographically high mountains, antithetic thrust belts, large amounts of erosion and denudation, exposure of high-grade metamorphic rocks at the surface, extensive deformation of crystalline basement to midcrustal depths, protracted postcollisional convergence (tens of millions of years), and a protracted history of molasse deposition within the adjacent foredeep basins. Analysis of gravity and deflection data across two advancing subduction boundaries developed within the <span class="hlt">continental</span> lithosphere (Western to Eastern and Southern Alps and Himalayas) shows that the thrust sheets have been translated for great distances over the foreland lithosphere (relative to the point at which the subduction forces are applied), thus obscuring any flexural and gravity signals from the subducted slab. However, it appears that far-field stresses, presumably related to global <span class="hlt">plate</span> motions, drive most of the convergent motion across these subduction boundaries. The concept that orogenic belts formed above retreating subduction boundaries have recognizable tectonic signatures that differ from those of orogenic belts formed above advancing subduction boundaries suggests that it may be possible to interpret the <span class="hlt">plate</span> boundary settings in which ancient orogenic belts evolved. Appendix B is available with entire article on microfiche.Order from the American Geophysical Union, 2000 FloridaAvenue, N.W., Washington, D.C. 20009. Document T92-004; $2.50. Payment must accompany order.</p> <div class="credits"> <p class="dwt_author">Royden, Leigh H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">76</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=%22Tectonic+Plates%22&pg=5&id=EJ154318"> <span id="translatedtitle">Suggestions for Teaching the Principles of <span class="hlt">Continental</span> Drift in the Elementary School</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Provides a brief overview of current geographic ideas regarding <span class="hlt">continental</span> drift and <span class="hlt">plate</span> tectonics and suggests techniques for illustrating <span class="hlt">continental</span> motions to elementary school pupils. (Author/DB)</p> <div class="credits"> <p class="dwt_author">Glenn, William H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1977-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">77</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://stonewall.uconn.edu/Articles/Grades%203-5/Lesson%204.doc"> <span id="translatedtitle">Primordial Ooze and <span class="hlt">Continental</span> Drift</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">In this lesson, students will learn that <span class="hlt">continental</span> <span class="hlt">plates</span> drift and this affects the layers of the earth. Following a directed reading and discussion, they will perform an experiment in which they use chocolate frosting and graham crackers to simulate tectonic <span class="hlt">plates</span> sliding about on the mantle.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">78</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://library.thinkquest.org/17701/high/tectonics/"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics: A Continuous Process</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This page provides an introduction to <span class="hlt">plate</span> tectonics for secondary students. Topics include <span class="hlt">plate</span> motions, the layers of the Earth and oceanic versus <span class="hlt">continental</span> <span class="hlt">plates</span>. A set of links provides access to material on the processes of <span class="hlt">plate</span> tectonics occuring at <span class="hlt">plate</span> boundaries, zones of movement and instability.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">79</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53331165"> <span id="translatedtitle">2-D tomographic imaging of <span class="hlt">continental</span> crust and relic slab beneath Baja California</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Rifting of Baja California from the margin of North America began as, or sometime before, subduction of the Farallon <span class="hlt">plate</span> ceased (~12 Ma). Many have speculated that increased coupling between the subducted Farallon slab and <span class="hlt">overriding</span> <span class="hlt">plate</span> caused the young upper part of the subducted <span class="hlt">plate</span> to detach from the older, colder, sinking slab. Then as the fragments of the</p> <div class="credits"> <p class="dwt_author">D. S. Brothers; A. J. Harding; G. Kent; N. Driscoll</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">80</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1610343M"> <span id="translatedtitle">Interplate coupling at oblique subduction zones: influence on upper <span class="hlt">plate</span> erosion.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In active subduction zones, when the converging <span class="hlt">plates</span> cannot slip freely past each other, "<span class="hlt">plate</span> coupling" occurs. The moving subducting slab and therefore the coupling/decoupling relationship between <span class="hlt">plates</span> control both short- and long-term deformation of the upper <span class="hlt">plate</span>. Short-term deformation is dominantly elastic, occurs at human timescales and can be directly associated with earthquakes. Long-term deformation is cumulative, permanent and prevails at the geological timescale (Hoffman-Rothe et al., 2006, Springer Berlin Heidelberg). Here we used 3D numerical simulations to test oblique subduction zones and to investigate: 1) how long-term deformation and coupling relationship vary along the trench-axis; 2) how this relationship influences erosion and down-drag of upper <span class="hlt">plate</span> material. Our models are based on thermo-mechanical equations solved with finite differences method and marker-in-cell techniques combined with a multigrid approach (Gerya, 2010, Cambridge Univ. Press). The reference model simulates an intraoceanic subduction close to the <span class="hlt">continental</span> margin (Malatesta et al., 2013, Nature Communications, 4:2456 DOI:10.1038/ncomms3456). The oceanic crust is layered with a 5-km-thick layer of gabbro overlain by a 3-km-thick layer of basalt. The ocean floor is covered by 1-km-thick sediments. <span class="hlt">Plates</span> move with a total velocity of 3.15 cm/yr; the oblique convergence is obtained using velocity vectors that form an angle of 45° with the initial starting point of subduction (weak zone in the lithosphere). After initiation of <span class="hlt">plate</span> convergence, part of sediments on top of the incoming <span class="hlt">plate</span> enters the subduction zone and is buried; another part is suddenly transferred along strike at shallow depths and along the subducting slab according to the direction of the along-trench velocity component of subduction. The lateral migration of sediment causes the evolution of the trench along its strike from sediment-poor to sediment-rich. As soon as subduction starts, where the sedimentary infill of the trench is almost nonexistent, short-term shallow coupling occurs and friction between the frontal sector of the <span class="hlt">overriding</span> <span class="hlt">plate</span> and the downgoing <span class="hlt">plate</span> triggers upper-<span class="hlt">plate</span> bending. In this sector, after the early short-term coupling, the <span class="hlt">overriding</span> <span class="hlt">plate</span> is hereafter decoupled from the subducting slab. Moving along trench-strike, where sediments amount increases, the upper <span class="hlt">plate</span> couples with the subducting <span class="hlt">plate</span> and is dragged coherently downwards. If a large amount of sediments is stored in the trench the <span class="hlt">overriding</span> <span class="hlt">plate</span> is scraped off and incorporated as fragments along the <span class="hlt">plate</span> interface. Our results suggest that a) one main parameter controlling coupling at convergent <span class="hlt">plate</span> margins is the occurrence and the amount of sediment at the trench; b) the upper <span class="hlt">plate</span> margin is dragged to depth or destroyed only where sediments thickness at the trench is large enough to promote interplate coupling, suggesting that a variation of sediment amount along the trench-axis influences the amount and style of transport of upper-<span class="hlt">plate</span> material in the mantle.</p> <div class="credits"> <p class="dwt_author">Malatesta, Cristina; Gerya, Taras; Crispini, Laura; Federico, Laura; Scambelluri, Marco; Capponi, Giovanni</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" 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class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/1467308"> <span id="translatedtitle">Staurosporine <span class="hlt">overrides</span> checkpoints for mitotic onset in BHK cells.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Under normal conditions, mammalian cells will not initiate mitosis in the presence of either unreplicated or damaged DNA. We report here that staurosporine, a tumor promoter and potent protein kinase inhibitor, can uncouple mitosis from the completion of DNA replication and <span class="hlt">override</span> DNA damage-induced G2 delay. Syrian hamster (BHK) fibroblasts that were arrested in S phase underwent premature mitosis at concentrations as low as 1 ng/ml, with maximum activity seen at 50 ng/ml. Histone H1 kinase activity was increased to approximately one-half the level found in normal mitotic cells. Inhibition of protein synthesis during staurosporine treatment blocked premature mitosis and suppressed the increase in histone H1 kinase activity. In asynchronously growing cells, staurosporine transiently increased the mitotic index and histone H1 kinase activity but did not induce S phase cells to undergo premature mitosis, indicating a requirement for S phase arrest. Staurosporine also bypassed the cell cycle checkpoint that prevents the onset of mitosis in the presence of damaged DNA. The delay in mitotic onset resulting from gamma radiation was reduced when irradiation was followed immediately by exposure to 50 ng/ml of staurosporine. These findings indicate that inhibition of protein phosphorylation by staurosporine can <span class="hlt">override</span> two important checkpoints for the initiation of mitosis in BHK cells. PMID:1467308</p> <div class="credits"> <p class="dwt_author">Tam, S W; Schlegel, R</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">82</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009Tectp.468..158G"> <span id="translatedtitle">3D Thermo-mechanical modelling of a stretched <span class="hlt">continental</span> lithosphere containing localized low-viscosity anomalies (the soft-point theory of <span class="hlt">plate</span> break-up)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present numerical models of extensional visco-elasto-plastic 3D <span class="hlt">continental</span> lithosphere containing weaker areas within its mantle section. We aim at understanding the 3D crustal structure of volcanic passive margins that is characterized by both across-strike and along-strike finite strain gradients, with maxima around central igneous complex or their feeding magma reservoirs. It is suggested that localized hot melting zones within the lithosphere act as mechanical soft points and result in the local focusing of extension. To test this hypothesis 3D thermo-mechanical models of extensional <span class="hlt">continental</span> lithosphere containing thermally induced soft points are implemented. Results show that crustal extension initiates and is focused over soft points in the mantle, reproducing the tectonic segmentation and zig-zag pattern of VPMs (volcanic passive margins).</p> <div class="credits"> <p class="dwt_author">Gac, Sébastien; Geoffroy, Laurent</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">83</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012GeoJI.188..879R"> <span id="translatedtitle">Large extensional aftershocks in the <span class="hlt">continental</span> forearc triggered by the 2010 Maule earthquake, Chile</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Mw 8.8 Maule earthquake occurred off the coast of central Chile on 2010 February 27 and was the sixth largest earthquake to be recorded instrumentally. This subduction zone event was followed by thousands of aftershocks both near the <span class="hlt">plate</span> interface and in the <span class="hlt">overriding</span> <span class="hlt">continental</span> crust. Here, we report on a pair of large shallow crustal earthquakes that occurred on 2010 March 11 within 15 min of each other near the town of Pichilemu, on the coast of the O'Higgins Region of Chile. Field and aerial reconnaissance following the events revealed no distinct surface rupture. We infer from geodetic data spanning both events that the ruptures occurred on synthetic SW-dipping normal faults. The first, larger rupture was followed by buried slip on a steeper fault in the hangingwall. The fault locations and geometry of the two events are additionally constrained by locations of aftershock seismicity based on the International Maule Aftershock Data Set. The maximum slip on the main fault is about 3 m and, consistent with field results, the onshore slip is close to zero near the surface. Satellite radar data also reveal that significant aseismic afterslip occurred following the two earthquakes. Coulomb stress modelling indicates that the faults were positively stressed by up to 40 bars as a result of slip on the subduction interface in the preceding megathrust event; in other words, the Pichilemu earthquakes should be considered aftershocks of the Maule earthquake. The occurrence of these extensional events suggests that regional interseismic compressive stresses are small. Several recent large shallow crustal earthquakes in the <span class="hlt">overriding</span> <span class="hlt">plate</span> following the 2011 Mw 9.0 Tohoku-Oki earthquake in Japan may be an analogue for the triggering process at Pichilemu.</p> <div class="credits"> <p class="dwt_author">Ryder, Isabelle; Rietbrock, Andreas; Kelson, Keith; Bürgmann, Roland; Floyd, Michael; Socquet, Anne; Vigny, Christophe; Carrizo, Daniel</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">84</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012EGUGA..14.5640G"> <span id="translatedtitle">Deformation and topography above the lateral transition from <span class="hlt">continental</span> to oceanic subduction in three-dimensional laboratory models: what can we learn on the Hellenic subduction?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We use three-dimensional dynamically self-consistent laboratory models to analyze relationships between surface evolution and deep dynamics at convergent margins. Our models are setup with a viscous <span class="hlt">plate</span> of silicone (lithosphere) subducting under negative buoyancy in a viscous layer of glucose syrup (upper mantle). We focus on the subduction of a laterally heterogeneous lithosphere characterized by an abrupt transition of density using negatively and positively buoyant silicone to reproduce oceanic and <span class="hlt">continental</span> subduction, respectively. We quantify and establish relationships between the subduction dynamics and resulting slab geometry, trench kinematics and pattern of horizontal/vertical deformation for both the <span class="hlt">overriding</span> <span class="hlt">plate</span> and the upper mantle. Assuming that our modeling results can be representative of the natural behavior of subduction zones, we compare them to the Neogene to Quaternary evolution of the Hellenic subduction zone. We more particularly focus on the deformation and topography of the Hellenic upper <span class="hlt">plate</span>, which may have been influenced by the difference in subduction dynamics north and south of the Kephalonia Transform Zone, with a slowly subducting Adriatic <span class="hlt">continental</span> lithosphere in the north and a rapidly subducting Ionian oceanic lithosphere in the south.</p> <div class="credits"> <p class="dwt_author">Guillaume, B.; Funiciello, F.; Faccenna, C.; Husson, L.; Royden, L. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">85</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20050000145&hterms=Tidal+Power&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DTidal%2BPower"> <span id="translatedtitle"><span class="hlt">Override</span> of spontaneous respiratory pattern generator reduces cardiovascular parasympathetic influence</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We investigated the effects of voluntary control of breathing on autonomic function in cardiovascular regulation. Variability in heart rate was compared between 5 min of spontaneous and controlled breathing. During controlled breathing, for 5 min, subjects voluntarily reproduced their own spontaneous breathing pattern (both rate and volume on a breath-by-breath basis). With the use of this experimental design, we could unmask the effects of voluntary <span class="hlt">override</span> of the spontaneous respiratory pattern generator on autonomic function in cardiovascular regulation without the confounding effects of altered respiratory pattern. Results from 10 subjects showed that during voluntary control of breathing, mean values of heart rate and blood pressure increased, whereas fractal and spectral powers in heart rate in the respiratory frequency region decreased. End-tidal PCO2 was similar during spontaneous and controlled breathing. These results indicate that the act of voluntary control of breathing decreases the influence of the vagal component, which is the principal parasympathetic influence in cardiovascular regulation.</p> <div class="credits"> <p class="dwt_author">Patwardhan, A. R.; Vallurupalli, S.; Evans, J. M.; Bruce, E. N.; Knapp, C. F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">86</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFMDI23A2076M"> <span id="translatedtitle">Linking <span class="hlt">plate</span> reconstructions with deforming lithosphere to geodynamic models</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">While global computational models are rapidly advancing in terms of their capabilities, there is an increasing need for assimilating observations into these models and/or ground-truthing model outputs. The open-source and platform independent GPlates software fills this gap. It was originally conceived as a tool to interactively visualize and manipulate classical rigid <span class="hlt">plate</span> reconstructions and represent them as time-dependent topological networks of editable <span class="hlt">plate</span> boundaries. The user can export time-dependent <span class="hlt">plate</span> velocity meshes that can be used either to define initial surface boundary conditions for geodynamic models or alternatively impose <span class="hlt">plate</span> motions throughout a geodynamic model run. However, tectonic <span class="hlt">plates</span> are not rigid, and neglecting <span class="hlt">plate</span> deformation, especially that of the edges of <span class="hlt">overriding</span> <span class="hlt">plates</span>, can result in significant misplacing of <span class="hlt">plate</span> boundaries through time. A new, substantially re-engineered version of GPlates is now being developed that allows an embedding of deforming <span class="hlt">plates</span> into topological <span class="hlt">plate</span> boundary networks. We use geophysical and geological data to define the limit between rigid and deforming areas, and the deformation history of non-rigid blocks. The velocity field predicted by these reconstructions can then be used as a time-dependent surface boundary condition in regional or global 3-D geodynamic models, or alternatively as an initial boundary condition for a particular <span class="hlt">plate</span> configuration at a given time. For time-dependent models with imposed <span class="hlt">plate</span> motions (e.g. using CitcomS) we incorporate the <span class="hlt">continental</span> lithosphere by embedding compositionally distinct crust and <span class="hlt">continental</span> lithosphere within the thermal lithosphere. We define three isostatic columns of different thickness and buoyancy based on the tectonothermal age of the continents: Archean, Proterozoic and Phanerozoic. In the fourth isostatic column, the oceans, the thickness of the thermal lithosphere is assimilated using a half-space cooling model. We also define the thickness of the thermal lithosphere for different <span class="hlt">continental</span> types, with the exception of the deforming areas that are fully dynamic. Finally, we introduce a "slab assimilation" method in which the thermal structure of the slab, derived analytically, is progressively assimilated into the upper mantle through time. This method not only improves the continuity of slabs in forward models with imposed <span class="hlt">plate</span> motions, but it also allows us to model flat slab segments that are particularly relevant for understanding dynamic surface topography. When it comes to post-processing and visualisation, GPlates allows the user to import time-dependent model output image stacks to visualise mantle properties (e.g. temperature) at a given depth through time, with <span class="hlt">plate</span> boundaries and other data attached to <span class="hlt">plates</span> overlain. This approach provides an avenue to simultaneously investigate the contributions of lithospheric deformation and mantle flow to surface topography. Currently GPlates is being used in conjunction with the codes CitcomS, Terra, BEMEarth and the adaptive mesh refinement code Rhea. A GPlates python plugin infrastructure makes it easy to extend interoperability with other geodynamic modelling codes.</p> <div class="credits"> <p class="dwt_author">Müller, R. D.; Gurnis, M.; Flament, N.; Seton, M.; Spasojevic, S.; Williams, S.; Zahirovic, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">87</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6951M"> <span id="translatedtitle">The key role of <span class="hlt">continental</span> collision in the episodic backarc extension behaviour in the Central Mediterranean</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The opening of the Tyrrhenian basin in the Central Mediterranean is a well-documented example of backarc extension, which is characterized by short-lived episodes of spreading. We present results from three-dimensional numerical models of subduction that explain the mechanism of backarc basin opening and its episodic spreading behaviour. We show that the entrance of <span class="hlt">continental</span> <span class="hlt">plates</span> (Africa and Adria) nearby oceanic subduction (Ionian slab) is important to trigger the formation of a backarc basin. Indeed, this lateral variation along-trench produces localised deformation within the <span class="hlt">overriding</span> <span class="hlt">plate</span> and allows the opening of the backarc basin. During this process the trench retreating velocity dramatically increase for few million of years. Afterwards, the slab breaks off forming slab windows at the ocean/continent boundaries and causing a second peak in the trench retreating velocity. This is in very good agreement with what is observed in the Central Mediterranean, where two slab window formed: one in northern Africa around 12-10 Ma, and propagates laterally westward beneath Sicily until the Middle Pleistocene, and a second one beneath the Central Apennines in the Middle Pleistocene. Our model indicates that the opening of those slab windows is a necessary condition for the second phase of rollback in the Tyrrhenian.</p> <div class="credits"> <p class="dwt_author">Magni, Valentina; Faccenna, Claudio; van Hunen, Jeroen; Funiciello, Francesca</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">88</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.bennett.karoo.net/topics/platetec.html"> <span id="translatedtitle">Internet Geography: <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This site is part of GeoNet Internet Geography, a resource for pre-collegiate British geography students and their instructors. This page focuses on the structure of the Earth and the theory of <span class="hlt">plate</span> tectonics, including <span class="hlt">continental</span> drift, <span class="hlt">plate</span> boundaries, the Ring of Fire, and mountains.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">89</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=%22Tectonic+Plates%22&pg=2&id=EJ638017"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics: A Paradigm under Threat.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Discusses the challenges confronting <span class="hlt">plate</span> tectonics. Presents evidence that contradicts <span class="hlt">continental</span> drift, seafloor spreading, and subduction. Reviews problems posed by vertical tectonic movements. (Contains 242 references.) (DDR)</p> <div class="credits"> <p class="dwt_author">Pratt, David</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">90</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70025941"> <span id="translatedtitle">GPS constraints on the kinematics of <span class="hlt">continental</span> deformation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Recent GPS observations from the western United States, New Zealand, central Greece, and Japan indicate that present-day <span class="hlt">continental</span> deformation is typically focused in narrow deforming zones whose extent is much smaller than the intervening largely inactive regions. However, these narrow zones are heterogeneously distributed, reflecting the inherent heterogeneity of <span class="hlt">continental</span> lithospheric strength and internal buoyancy. <span class="hlt">Plate</span> driving and resisting forces stress <span class="hlt">plate</span> boundary zones and <span class="hlt">plate</span> interiors and drive deformation. These forces change continuously and discontinuously, leading to <span class="hlt">continental</span> deformation that typically evolves and migrates with time. Magmatic and tectonic processes alter lithospheric rheology and internal buoyancy and also contribute to the time-varying character of <span class="hlt">continental</span> deformation.</p> <div class="credits"> <p class="dwt_author">Thatcher, W.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">91</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.teachersdomain.org/6-8/sci/ess/earthsys/shake/index.html"> <span id="translatedtitle">Mountain Maker- Earth Shaker (Convergent Boundary: oceanic-<span class="hlt">continental</span>)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The representation depicts <span class="hlt">plate</span> boundary interactions. The convergent boundary is one part of a larger interactive diagram (the 2nd slider/ arrow from the left), that focuses on an ocean <span class="hlt">plate</span> pressing against a <span class="hlt">continental</span> <span class="hlt">plate</span>. This review specifically addresses the part of the resource dealing with what happens when <span class="hlt">plates</span> pull apart. The "show intro" link provides instruction for diagram manipulation.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">92</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.T51E2509H"> <span id="translatedtitle"><span class="hlt">Continental</span> aggregation, subduction initiation, and plume generation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Several processes unfold during the supercontinent cycle, more than one of which might result in an elevation in subcontinental mantle temperatures through the generation of mantle plumes. Paleogeographic <span class="hlt">plate</span> reconstructions have indicated that sub-<span class="hlt">continental</span> mantle upwellings appear below large continents that are extensively ringed by subduction zones. Moreover, several numerical simulations of supercontinent formation and dispersal attribute the genesis of sub-<span class="hlt">continental</span> plumes to the generation of subduction zones on the edges of the supercontinent, rather than resulting from <span class="hlt">continental</span> insulation. However, the role of the location of downwellings in producing a return-flow upwelling, and on increasing sub-<span class="hlt">continental</span> mantle temperatures, is not fully understood. In this mantle convection study, we examine the evolution of mantle dynamics after supercontinent accretion over a subduction zone (analogous to the formation of Pangea) for a range of <span class="hlt">continental</span> coverage. We present 2D and 3D Cartesian geometry mantle convection simulations, featuring geotherm- and pressure-dependent viscosity with thermally and mechanically distinct oceanic and <span class="hlt">continental</span> <span class="hlt">plates</span>. Through changing the size of the continent we are able to analyze the factors involved in the generation of mantle plumes in purely thermal convection. Furthermore, we change the upper and lower mantle viscosity to determine their relation to plume formation in vigorous mantle convection simulations. Elevated sub-<span class="hlt">continental</span> temperatures are analyzed in relation to <span class="hlt">continental</span> coverage to further understand the influence of <span class="hlt">continental</span> tectonics on the thermal evolution of the mantle.</p> <div class="credits"> <p class="dwt_author">Heron, P. J.; Lowman, J. P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">93</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/CFR-2013-title43-vol2/pdf/CFR-2013-title43-vol2-sec3504-26.pdf"> <span id="translatedtitle">43 CFR 3504.26 - May I create <span class="hlt">overriding</span> royalties on my Federal lease?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p class="result-summary">...MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING OF SOLID MINERALS OTHER THAN COAL AND OIL SHALE Fees, Rental, Royalty and Bonds Royalties § 3504.26 May I create <span class="hlt">overriding</span> royalties on my Federal...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2013-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">94</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=PB2002104366"> <span id="translatedtitle">Auto Radio <span class="hlt">Override</span> Alert System for Emergency Vehicles and for Railroad-Highway Grade Crossings.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The project shall develop, test and perform pre-service deployment of a transceiver <span class="hlt">override</span> system for active automobile radios to warn the drivers in front of approaching emergency vehicles such as fire trucks, police, ambulance and trains nearing grade...</p> <div class="credits"> <p class="dwt_author">D. Maxwell</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">95</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3680538"> <span id="translatedtitle">Centromere fragmentation is a common mitotic defect of S and G2 checkpoint <span class="hlt">override</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">DNA damaging agents, including those used in the clinic, activate cell cycle checkpoints, which blocks entry into mitosis. Given that checkpoint <span class="hlt">override</span> results in cell death via mitotic catastrophe, inhibitors of the DNA damage checkpoint are actively being pursued as chemosensitization agents. Here we explored the effects of gemcitabine in combination with Chk1 inhibitors in a panel of pancreatic cancer cell lines and found variable abilities to <span class="hlt">override</span> the S phase checkpoint. In cells that were able to enter mitosis, the chromatin was extensively fragmented, as assessed by metaphase spreads and Comet assay. Notably, electron microscopy and high-resolution light microscopy showed that the kinetochores and centromeres appeared to be detached from the chromatin mass, in a manner reminiscent of mitosis with unreplicated genomes (MUGs). Cell lines that were unable to <span class="hlt">override</span> the S phase checkpoint were able to <span class="hlt">override</span> a G2 arrest induced by the alkylator MMS or the topoisomerase II inhibitors doxorubicin or etoposide. Interestingly, checkpoint <span class="hlt">override</span> from the topoisomerase II inhibitors generated fragmented kinetochores (MUGs) due to unreplicated centromeres. Our studies show that kinetochore and centromere fragmentation is a defining feature of checkpoint <span class="hlt">override</span> and suggests that loss of cell viability is due in part to acentric genomes. Furthermore, given the greater efficacy of forcing cells into premature mitosis from topoisomerase II-mediated arrest as compared with gemcitabine-mediated arrest, topoisomerase II inhibitors maybe more suitable when used in combination with checkpoint inhibitors.</p> <div class="credits"> <p class="dwt_author">Beeharry, Neil; Rattner, Jerome B.; Caviston, Juliane P.; Yen, Tim</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">96</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.discoveryeducation.com/teachers/free-lesson-plans/continental-drift.cfm"> <span id="translatedtitle"><span class="hlt">Continental</span> Drift</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on Alfred Wegener's theory of <span class="hlt">Continental</span> Drift and the evidence used to support it. Using fossil types and maps, students view similarities between continents that led Wegener to conclude that they had once been together as a supercontinent, Pangea. Included are objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">97</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.4522K"> <span id="translatedtitle">Tectono-stratigraphic evolution of the <span class="hlt">continental</span> Miocene basins in southern Anatolia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The exposed portion of the Tauride fold-thrust belt in southern Turkey is flanked and overlain by Neogene sedimentary basins. To the south and on top of the high ranges, these basins are mainly marine, whereas previously poorly studied intra-montane basins dominated by <span class="hlt">continental</span> deposits are exposed to the north. We have studied the stratigraphy and structure of these <span class="hlt">continental</span> basins - the Alt?napa, Yalvaç and Ilg?n Basins. Their stratigraphy displays overall fining upward sequences of fluvio-lacustrine sediments, deposition of which interrupted by basin-wide unconformities; similar hiatuses seems to exist in each basin. The most prominent unconformity surface occurred during the Middle Miocene and corresponds to the timing of volcanic activity in the region. 40Ar/39Ar dating of the volcaniclastic samples from the Alt?napa and Ilg?n basins yielded 11.8-11.6 Ma ages. The main basin forming regional deformation phase was extensional and occurred during the Middle Miocene. The extension directions obtained from paleostress inversion techniques indicate multidirectional extension under vertical uniaxial stress which are compatible with the recent seismic activity and available focal mechanism solutions. The main basin-bounding faults, however, are constrained mainly N-S to NW-SE implying that they are reactivated structures. The Middle Miocene and onwards extensional history of these basins occurs behind and atop a thrust front along the Cyprus arc, extending towards the Antalya nappes and Aksu thrust in the heart of the Isparta angle. The synchrounous, curved pairs of thrust fronts associated with subduction and <span class="hlt">overriding</span> <span class="hlt">plate</span> extension suggests that the Cyprus subduction zone has been retreating relative to central Anatolia since, at least, the Middle Miocene time. In addition to extensional history of the region, these <span class="hlt">continental</span> basins contain evidence for the post-Late Miocene differential uplift of the Taurides in southern Anatolia. All of these <span class="hlt">continental</span> basins were above sea level during the Middle and Late Miocene and are now found at an elevation of 1 km. On the other hand, the upper Miocene marine deposits just south of the study area currently are at an elevation of ~2 km, and have therefore been uplifted at least 1 km more than the <span class="hlt">continental</span> basins to the north. We conclude that the current high elevation of the Taurides is synchronous with, and at least in part related to late Neogene extension and vertical differential uplift, likely related to the dynamics of the Cyprian subduction zone.</p> <div class="credits"> <p class="dwt_author">Koç, Ayten; Kaymakci, Nuretdin; van Hinsbergen, Douwe J. J.; Kuiper, Klaudia F.; Vissers, Reinoud L. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">98</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1981ESRv...17...87M"> <span id="translatedtitle">The Brazilian <span class="hlt">continental</span> margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Brazilian <span class="hlt">continental</span> margin, with its interesting morphology, structure and sediments, has become better known only during the last two decades. Six physiographical provinces can be recognized at the <span class="hlt">continental</span> margin and the adjacent coast: (1) Cabo Orange-Parnaiba delta; (2) Parnaiba delta-Cabo Sa˜o Roque; (3) Cabo Sa˜o Roque-Belmonte; (4) Belmonte-Cabo Frio; (5) Cabo Frio-Cabo Santa Marta; and (6) Cabo Santa Marta-Chui. The shelf is rather wide near the Amazon Mouth, becoming narrower eastwards, continuing very narrow along the northeastern and eastern coast, and becoming wider again in the south towards the <span class="hlt">Plate</span> River. Prominent morphological features along the margin are the Amazon cone, the marginal plateaus off northeastern Brazil, the Sa˜o Francisco cone and canyon, the Abrolhos Bank, and the deep-sea plateaus of Pernambuco and Sa˜o Paulo. On the shelf proper a number of relief elements exist, such as sand waves east of the Amazon, submarine terraces at various places, and irregularities of structural origin. The shelf break is rather smooth in the far north and south, more abrupt in the remainder. Surface sediments of the Brazilian shelf show five distinct facies types: littoral quartz sands, mud, transition sand-mud, coralline algae, and biodetrital. The terrigenous elastic fractions dominate off the Amazon and in southern Brazil; between these areas they occupy a very narrow strip near the coast. The carbonate facies, predominantly composed of calcareous algae, is abundant between the Parnaiba delta and Cabo Frio; to the south this facies is more biodetrital and restricted to the outer shelf. Economically important on the Brazilian <span class="hlt">continental</span> margin besides oil, are sands and gravels, carbonate deposits, evaporites and some subsurface coal. Other possible mineral resources could be phosphate, heavy minerals and clays for ceramics.</p> <div class="credits"> <p class="dwt_author">Martins, L. R.; Coutinho, P. N.</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">99</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/21964273"> <span id="translatedtitle">Psychometric properties of an instrument for measuring threat/control-<span class="hlt">override</span> symptoms.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Threat/control-<span class="hlt">override</span> symptoms refer to delusional persecutory thoughts and feelings of losing control over mind and body. The Threat/Control-<span class="hlt">Override</span> Questionnaire (TCOQ) was developed to assess such symptoms, and the purpose of the present study was to examine the psychometric properties of this measure in nonclinical students (n = 759) and acute and stabilized psychotic patients (n = 111 and 33, respectively). Factor analysis of TCOQ data in students and acute psychotic patients yielded a two-factor solution, with components referring to "threat" and "control-<span class="hlt">override</span>" symptoms. Internal consistency and test-retest reliability were satisfactory and concurrent and discriminant validity were shown by a meaningful pattern of correlations with other self-report and interview measures. Group comparisons showed that patients displayed significantly higher scores on the TCOQ than did the nonclinical students. Altogether, it can be concluded that the TCOQ is a reliable and valid index for assessing feelings of persecution and losing control. PMID:21964273</p> <div class="credits"> <p class="dwt_author">Nederlof, Angela F; Muris, Peter; Hovens, Johannes E</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">100</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19930089591&hterms=diode+recovery&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddiode%2Brecovery"> <span id="translatedtitle">Experimental Investigation of an <span class="hlt">Overriding</span> Control to Effect Recovery from Surge and Stall in a Turbojet Engine</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The <span class="hlt">override</span> was designed to automatically recover the engine from stall and surge by reducing fuel flow and then increasing fuel flow in a manner to avoid repeated stalls and surges and successfully complete the acceleration. One of two parameters was used to operate the <span class="hlt">override</span>, tailpipe temperature, or the derivative of compressor-discharge pressure. The <span class="hlt">override</span> operating with tailpipe temperature recovered the engine from stall and surge. Operating on compressor-discharge-pressure derivative, the <span class="hlt">override</span> recovered the engine from surge, but failed when stall was encountered.</p> <div class="credits"> <p class="dwt_author">Stiglic, Paul M; Heppler, Herbert</p> <p class="dwt_publisher"></p> <p class="publishDate">1956-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_4");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span 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<a id="NextPageLink" onclick='return showDiv("page_7");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">101</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=Earth&pg=7&id=EJ946756"> <span id="translatedtitle">The <span class="hlt">Plate</span> Tectonics Project</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">The <span class="hlt">Plate</span> Tectonics Project is a multiday, inquiry-based unit that facilitates students as self-motivated learners. Reliable Web sites are offered to assist with lessons, and a summative rubric is used to facilitate the holistic nature of the project. After each topic (parts of the Earth, <span class="hlt">continental</span> drift, etc.) is covered, the students will…</p> <div class="credits"> <p class="dwt_author">Hein, Annamae J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">102</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008AGUFM.U53A0067W"> <span id="translatedtitle"><span class="hlt">Continental</span> Subduction Settings: Reduced Volatile Transport of Cl and S to the Surface?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A research focus of the Collaborative Research Center SFB 574 is the magmatic output of chlorine and sulfur as determined by melt inclusion analyses of primitive and evolved tephra deposits from the Central American (CAVA) and Southern Chilean (SVZ) arcs. Here we integrate our comprehensive geochemical data sets from the CAVA, consisting of 1200 melt inclusion and 300 whole-rock analyses from 71 volcanic centers, with our preliminary data from the SVZ and literature data from the Izu-Bonin-Marianas system (IBM). The highest chlorine contents in melt inclusions are reported from the IBM, an oceanic subduction zone endmember, whereas lower overall concentrations occur at the transitional CAVA. Melt-inclusion Cl-contents of both mafic and felsic CAVA rocks reach highest values in Nicaragua, where slab fluids dominate and the crust is thinnest, and gradually decrease towards the more <span class="hlt">continental</span> Guatemalan segment of the arc. An exception to this trend are the high Cl contents in central Costa Rican tephras where the influence of the subducted, compositionally OIB-like Cocos Ridge is high. Preliminary analyses from the SVZ <span class="hlt">continental</span> endmember reveal low melt Cl concentrations. Cl contents inversely correlate with Nd isotope ratios along the SVZ, with very low Cl and the highest Nd isotope ratios occurring at Llaima Volcano. Possible causes of this inverse relation are Cl-increase by crustal contamination reflected in lower Nd isotope ratios as well as lower degrees of partial melting of more enriched (pyroxenitic/eclogitic) material beneath thicker crust. The overall correlation, however, is modulated by local tectonic and compositional controls. Sulfur concentrations are also significantly lower in SVZ eruptives than at the CAVA, possibly reflecting absence of a S-rich source component at the SVZ. S-contents in mafic melt inclusions gradually decrease from ca. 2500 ppm in the southern SVZ to 500 ppm further north where the crust is thicker. This may reflect northward increasing S degassing during the melt's prolonged passage through the continually thickening <span class="hlt">continental</span> crust. Although the total magma fluxes and magma production rates of the SVZ are still being determined, these first constraints on eruptive volatile output as recorded by melt inclusion geochemistry, integrated with comprehensive findings from the CAVA and IBM, may point to a broad picture of more limited volatile turnover in the subduction segments characterized by thick <span class="hlt">continental</span> crust and thus a control on volatile contents based on the nature and thickness of the <span class="hlt">overriding</span> <span class="hlt">plate</span>.</p> <div class="credits"> <p class="dwt_author">Wehrmann, H.; Kutterolf, S.; Hoernle, K.; Freundt, A.; Portnyagin, M.; Heydolph, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">103</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.planetseed.com/relatedarticle/plate-borders-mountain-building"> <span id="translatedtitle"><span class="hlt">Plate</span> Borders and Mountain Building</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This page features animations of four different types of <span class="hlt">plate</span> boundaries, including one animation of the collision of two pieces of <span class="hlt">continental</span> crust, forming steep mountain ranges. The animations are all presented in flash, and the <span class="hlt">plate</span> convergence offers a useful, generic view of orogeny.</p> <div class="credits"> <p class="dwt_author">Schlumberger Excellence In Educational Development, Inc.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">104</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/48902677"> <span id="translatedtitle">The temporal evolution of <span class="hlt">plate</span> driving forces: Importance of “slab suction” versus “slab pull” during the Cenozoic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Although mantle slabs ultimately drive <span class="hlt">plate</span> motions, the mechanism by which they do so remains unclear. A detached slab descending through the mantle will excite mantle flow that exerts shear tractions on the base of the surface <span class="hlt">plates</span>. This “slab suction” force drives subducting and <span class="hlt">overriding</span> <span class="hlt">plates</span> symmetrically toward subduction zones. Alternatively, cold, strong slabs may effectively transmit stresses to</p> <div class="credits"> <p class="dwt_author">Clinton P. Conrad; Carolina Lithgow-Bertelloni</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">105</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://supercronopio.es.ucl.ac.uk/~crlb/RESEARCH/PAPERS/ConradCLB04.pdf"> <span id="translatedtitle">The temporal evolution of <span class="hlt">plate</span> driving forces: Importance of ``slab suction'' versus ``slab pull'' during the Cenozoic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Although mantle slabs ultimately drive <span class="hlt">plate</span> motions, the mechanism by which they do so remains unclear. A detached slab descending through the mantle will excite mantle flow that exerts shear tractions on the base of the surface <span class="hlt">plates</span>. This ``slab suction'' force drives subducting and <span class="hlt">overriding</span> <span class="hlt">plates</span> symmetrically toward subduction zones. Alternatively, cold, strong slabs may effectively transmit stresses to</p> <div class="credits"> <p class="dwt_author">Clinton P. Conrad; Carolina Lithgow-Bertelloni</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">106</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19860053909&hterms=plate+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dplate%2Bmotion"> <span id="translatedtitle"><span class="hlt">Plate</span> motion controls on back-arc spreading. [Cenozoic movement in Western Pacific</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The motions of the subducting and the <span class="hlt">overriding</span> <span class="hlt">plates</span> influence the spatial and temporal distribution of back-arc spreading. Cenozoic <span class="hlt">plate</span> motions in hot spot-fixed and no-net-rotation reference frames were studied with attention to correlations between changes in motion and episodes of back-arc spreading in the western Pacific. The results suggest that major back-arc opening occurs when both the <span class="hlt">overriding</span> <span class="hlt">plate</span> retreats from the trench in an absolute sense and the subducting <span class="hlt">plate</span> undergoes a significant speed-up. Neither phenomenon alone is sufficient to initiate spreading. Three major <span class="hlt">plate</span> velocity increases can be identified in the Cenozoic: (1) the Pacific <span class="hlt">plate</span> 5-9 Ma; (2) the Indian <span class="hlt">plate</span> at 27 Ma; and (3) the Pacific <span class="hlt">plate</span> at 43 Ma, due to its shift from northerly to more westerly motion. At the present time, the Indian and Philippine are the only <span class="hlt">overriding</span> <span class="hlt">plates</span> that are retreating from their Pacific trenches and back-arc spreading occurs only on these two retreating <span class="hlt">plates</span>. Although the Indian <span class="hlt">plate</span> has been retreating for at least 25 Ma, back-arc spreading began only following the Pacific <span class="hlt">plate</span> speed-up 5-9 Ma. Earlier, during the Indian <span class="hlt">plate</span> speed-up, no <span class="hlt">overriding</span> <span class="hlt">plates</span> were retreating strongly and no back-arc spreading epsiodes are preserved from this time. For the earliest Pacific <span class="hlt">plate</span> shift at 43 Ma, the Eurasian <span class="hlt">plate</span> was not advancing, thus creating the only favorable <span class="hlt">plate</span> kinematic conditions in the Cenozoic for back-arc basin formation in this region. It is unclear whether extension in the Japan Sea is a result of these conditions.</p> <div class="credits"> <p class="dwt_author">Fein, J. B.; Jurdy, D. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">107</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://learningcenter.nsta.org/product_detail.aspx?id=10.2505/7/SCB-PT.5.1"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics: Lines of Evidence</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This Science Object is the fifth of five Science Objects in the <span class="hlt">Plate</span> Tectonics SciPack. It explores the physical, geographical, and geological evidence for the theory of <span class="hlt">continental</span> drift and <span class="hlt">plate</span> tectonics. <span class="hlt">Plate</span> tectonics provide a unifying framework for understanding Earth processes and history, and is supported by many lines of evidence. Over geologic time, <span class="hlt">plates</span> move across the globe creating different continents (and positions of continents). Learning Outcomes:� Use <span class="hlt">plate</span> tectonics to explain changes in continents and their positions over geologic time.� Provide evidence for the idea of <span class="hlt">plates</span>, including the location of earthquakes and volcanoes, <span class="hlt">continental</span> drift, magnetic orientation of rocks in the ocean floor, etc.</p> <div class="credits"> <p class="dwt_author">National Science Teachers Association (NSTA)</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">108</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56308780"> <span id="translatedtitle"><span class="hlt">Continental</span> underplating model for the rise of the Tibetan Plateau</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The question of the possibility of <span class="hlt">continental</span> lithosphere subduction into the mantle, raised by Molnar and Gray (1979), is reexamined using new data on the Plio-Pleistocene timing of the uplift of the Tibetan Plateau. First, the constraints on the maximum amount of <span class="hlt">continental</span> lithosphere that can be subducted are considered. It is shown that, for the late Cenozoic Indo-Australian <span class="hlt">plate</span></p> <div class="credits"> <p class="dwt_author">C. Mca. Powell</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">109</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/1686396"> <span id="translatedtitle">Domain-<span class="hlt">overriding</span> and digital filtering for 3-D FDTD subgridded simulations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We report on an extension of finite-difference time-domain (FDTD) subgridding (SG) algorithms incorporating digital filters and domain-<span class="hlt">overriding</span> to three-dimensional (3-D) simulations and to problems involving materials traversing the SG interfaces. We show that significant improvements in accuracy can be obtained for these cases as well</p> <div class="credits"> <p class="dwt_author">Burkay Donderici; Fernando L. Teixeira</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">110</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24666325"> <span id="translatedtitle">Caffeine stabilizes Cdc25 independently of Rad3 in Schizosaccharomyces pombe contributing to checkpoint <span class="hlt">override</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Cdc25 is required for Cdc2 dephosphorylation and is thus essential for cell cycle progression. Checkpoint activation requires dual inhibition of Cdc25 and Cdc2 in a Rad3-dependent manner. Caffeine is believed to <span class="hlt">override</span> activation of the replication and DNA damage checkpoints by inhibiting Rad3-related proteins in both Schizosaccharomyces pombe and mammalian cells. In this study, we have investigated the impact of caffeine on Cdc25 stability, cell cycle progression and checkpoint <span class="hlt">override</span>. Caffeine induced Cdc25 accumulation in S.?pombe independently of Rad3. Caffeine delayed cell cycle progression under normal conditions but advanced mitosis in cells treated with replication inhibitors and DNA-damaging agents. In the absence of Cdc25, caffeine inhibited cell cycle progression even in the presence of hydroxyurea or phleomycin. Caffeine induces Cdc25 accumulation in S.?pombe by suppressing its degradation independently of Rad3. The induction of Cdc25 accumulation was not associated with accelerated progression through mitosis, but rather with delayed progression through cytokinesis. Caffeine-induced Cdc25 accumulation appears to underlie its ability to <span class="hlt">override</span> cell cycle checkpoints. The impact of Cdc25 accumulation on cell cycle progression is attenuated by Srk1 and Mad2. Together our findings suggest that caffeine <span class="hlt">overrides</span> checkpoint enforcement by inducing the inappropriate nuclear localization of Cdc25. PMID:24666325</p> <div class="credits"> <p class="dwt_author">Alao, John P; Sjölander, Johanna J; Baar, Juliane; Özbaki-Yagan, Nejla; Kakoschky, Bianca; Sunnerhagen, Per</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">111</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://disc.gsfc.nasa.gov/geomorphology/GEO_2/GEO_PLATE_T-11.shtml"> <span id="translatedtitle"><span class="hlt">Plate</span> T-11: Appalachian Mountains</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">Appalachian Mountain landforms clearly demonstrate the relation of <span class="hlt">plate</span> tectonics and structure to geomorphology. The folded rocks record the convergence of two <span class="hlt">continental</span> <span class="hlt">plates</span> in Pennsylvanian/Permian time. This page uses text, maps, and remotely sensed imagery to explain the relationship between <span class="hlt">plate</span> tectonics, geologic structures, and the resulting landforms. It is part of an out-of-print NASA publication entitled 'Geomorphology from Space'. Links to the rest of the book are provided.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">112</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=N8629426"> <span id="translatedtitle">Intraplate Deformation Due to <span class="hlt">Continental</span> Collisions: A Numerical Study of Deformation in a Thin Viscous Sheet.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary"><span class="hlt">Continental</span> collisions can result in the transmission of stress from the boundary between tectonic <span class="hlt">plates</span> into the <span class="hlt">plate</span> interiors. Extensive crustal deformations characterized by both horizontal and vertical crustal movements have occurred as a consequen...</p> <div class="credits"> <p class="dwt_author">S. C. Cohen R. C. Morgan</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">113</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=plate+AND+motion&pg=2&id=EJ409352"> <span id="translatedtitle">A Simple Class Exercise on <span class="hlt">Plate</span> Tectonic Motion.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Presented is an activity in which students construct a model of <span class="hlt">plate</span> divergence with two sheets of paper to show the separation of two <span class="hlt">continental</span> <span class="hlt">plates</span> in a system of spreading ridges and faults. Diagrams and procedures are described. (CW)</p> <div class="credits"> <p class="dwt_author">Bates, Denis E. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">114</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://static.icr.org/i/pdf/technical/Catastrophic-Plate-Tectonics-A-Global-Flood-Model.pdf"> <span id="translatedtitle">Catastrophic <span class="hlt">Plate</span> Tectonics: A Global Flood Model of Earth History</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In 1859 Antonio Snider proposed that rapid, horizontal divergence of crustal <span class="hlt">plates</span> occurred during Noah's Flood. Modern <span class="hlt">plate</span> tectonics theory is now conflated with assumptions of uniformity of rate and ideas of <span class="hlt">continental</span> \\</p> <div class="credits"> <p class="dwt_author">Steven A. Austin; John R. Baumgardner; D. Russell Humphreys; Andrew A. Snelling; Larry Vardiman; Kurt P. Wise</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">115</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006AGUFM.T42C..05L"> <span id="translatedtitle">BOLIVAR & GEODINOS: Investigations of the Southern Caribbean <span class="hlt">Plate</span> Boundary</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The southern Caribbean-South American <span class="hlt">plate</span> boundary has many similarities to California's San Andreas system: 1) The CAR-SA system consists of a series of strands of active right lateral strike-slip faults extending >1000 km from the Antilles subduction zone. This system has several names and includes the El Pilar, Coche, San Sebastian, Moron, and Oca faults. 2) The CAR-SA relative velocity has been about 20 mm/yr of mostly right lateral motion since about 55 Ma, giving a total displacement on the CAR-SA <span class="hlt">plate</span> boundary similar to that of the San Andreas system. 3) The <span class="hlt">plate</span> boundary has about 10% convergence in western SA, with less as one moves eastward due to relative convergence between North and South America. 4) The CAR-SA system has fold and thrust belts best developed continentward of the strike-slip faults, similar to the San Andreas. 5) There is a big bend in the CAR <span class="hlt">plate</span> boundary at approximately the same distance from the Antilles trench as the big bend in Southern California is from the Cascadia subduction zone. The tectonic origins of the CAR-SA <span class="hlt">plate</span> boundary and the San Andreas are very different, however, despite the similarities between the systems. Rather than impingement of a ridge on a trench, the CAR-SA system is thought to have resulted from a continuous oblique collision of the southern end of a Cretaceous island arc system with the northern edge of South America. During this process the CAR island arc and the modern CAR <span class="hlt">plate</span> overrode a proto-Caribbean <span class="hlt">plate</span> and destroyed a Mesozoic passive margin on the northern edge of SA. BOLIVAR and GEODINOS are multi-disciplinary investigations of the lithosphere and deeper structures associated with the diffuse CAR-SA <span class="hlt">plate</span> boundary zone. We review a number of observations regarding the <span class="hlt">plate</span> boundary obtained or confirmed from these studies: 1) The Caribbean Large Igneous Province, being overridden by the Maracaibo block in western Venezuela, can be identified beneath Aruba and coastal Venezuela, and is associated with broad uplift of the coastal regions. This is likely a site of <span class="hlt">continental</span> growth. 2) The accretionary wedge terranes of the Southern Caribbean Deformed Belt formed in the Neogene, and extend as far east as the Aves Ridge. They result from SA <span class="hlt">overriding</span> the CAR LIP, which for a number of reasons, we do not regard as normal subduction. 3) Igneous rocks on the islands of the Leeward Antilles arc, Aruba to Los Testigos, show a steady decrease in age from west to east (94.7-37.4 Ma), suggesting that the islands have been progressively captured from the Antilles arc by the <span class="hlt">plate</span> boundary during the prolonged island arc-continent collision. Terrane capture models thus far cannot completely explain the data. 4) High (> 6.5 km/s) P-velocity bodies are found in the shallow crust along the main strike-slip faults along much of the <span class="hlt">plate</span> boundary. We interpret these as elements of the HP/LT metamorphic terranes found in the adjacent thrust belts of central Venezuela. This suggests to us that displacement partitioning in the trench and subsequent strike-slip both play important roles in exhumation of the HP/LT terranes. 5) Crustal thickness variations in the <span class="hlt">plate</span> boundary region are large (> 10 km), of short spatial wavelength (< 100 km), and indicate that the highest elevations of the coastal mountain belts are not supported isostatically.</p> <div class="credits"> <p class="dwt_author">Levander, A.; Schmitz, M.; Working Groups, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">116</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/3991024"> <span id="translatedtitle">Three-dimensional miscible displacement simulations in homogeneous porous media with gravity <span class="hlt">override</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">High-accuracy three-dimensional numerical simulations of miscible displacements with gravity <span class="hlt">override</span> in homogeneous porous media are carried out for the quarter five-spot configuration. Special emphasis is placed on describing the influence of viscous and gravitational effects on the overall displacement dynamics in terms of the vorticity variable. Even for neutrally buoyant displacements, three-dimensional effects are seen to change the character of</p> <div class="credits"> <p class="dwt_author">A. Riaz; E. Meiburg</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">117</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://schizophreniabulletin.oxfordjournals.org/cgi/reprint/30/1/31.pdf"> <span id="translatedtitle">Schizophrenia, Delusional Symptoms, and Violence: The Threat\\/Control-<span class="hlt">Override</span> Concept Reexamined</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In 1994 Link and Stueve identified a number of symp- toms—called threat\\/control-<span class="hlt">override</span> (TCO) symp- toms—that were significantly more than others related to violence. This was confirmed by some, but not all, following studies. The contradictory results could be due to remarkable differences in sample compositions, sources used, and definitions and periods of recorded violence, but they are mainly due to</p> <div class="credits"> <p class="dwt_author">Thomas Stompe; Hans Schanda</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">118</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/49381210"> <span id="translatedtitle">Schizophrenia, Delusional Symptoms, and Violence: The Threat\\/Control-<span class="hlt">Override</span> Concept Reexamined</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">In 1994 Link and Stueve identified a number of symptoms—called threat\\/control-<span class="hlt">override</span> (TCO) symptoms—that were significantly more than others related to violence. This was confirmed by some, but not all, following studies. The contradictory results could be due to remarkable differences in sample compositions, sources used, and definitions and periods of recorded violence, but they are mainly due to problems defining</p> <div class="credits"> <p class="dwt_author">Thomas Stompe; Gerhard Ortwein-Swoboda; Hans Schanda</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">119</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/36523362"> <span id="translatedtitle">AURORA-A amplification <span class="hlt">overrides</span> the mitotic spindle assembly checkpoint, inducing resistance to Taxol</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The serine-threonine kinase gene AURORA-A is commonly amplified in epithelial malignancies. Here we show that elevated Aurora-A expression at levels that reflect cancer-associated gene amplification <span class="hlt">overrides</span> the checkpoint mechanism that monitors mitotic spindle assembly, inducing resistance to the chemotherapeutic agent paclitaxel (Taxol). Cells overexpressing Aurora-A inappropriately enter anaphase despite defective spindle formation, and the persistence of Mad2 at the kinetochores,</p> <div class="credits"> <p class="dwt_author">Shubha Anand; Sue Penrhyn-Lowe; Ashok R Venkitaraman</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">120</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6198486"> <span id="translatedtitle">Why does <span class="hlt">continental</span> convergence stop</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Convergence between India and Asia slowed at 45 Ma when they collided, but continues today. This requires that substantial proportions of the Indian and/or Asian lithospheric mantle are still being subducted. The resulting slab-pull is probably comparable with that from complete lithospheric slabs and may promote continued <span class="hlt">continental</span> convergence even after collision. Since descending lithospheric slabs are present at all collision zones at the time of collision such continued convergence may be general after <span class="hlt">continental</span> collisions. It may cease only when there is a major (global) <span class="hlt">plate</span> reorganization which results in new forces on the convergent continents that may counteract the slab-pull. These inferences may be tested on the late Paleozoic collision between Gondwanaland and Laurasia. This is generally considered to have been complete by mid-Permian time (250 Ma). However, this may be only the time of docking of Gondwanaland with North America, not that of the cessation of convergence. Paleomagnetic polar-wander paths for the Gondwanide continents exhibit consistently greater latitudinal shifts from 250 Ma to 200 Ma than those of Laurasia when corrected for post-Triassic drift, suggesting that convergence continued through late Permian well into the Triassic. It may have been accommodated by crustal thickening under what is now the US Coastal Plain, or by strike-slip faulting. Convergence may have ceased only when Pangea began to fragment again, in which case the cause for its cessation may be related to the cause of <span class="hlt">continental</span> fragmentation.</p> <div class="credits"> <p class="dwt_author">Hynes, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_5");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span 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<a id="NextPageLink" onclick='return showDiv("page_8");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">121</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.9241B"> <span id="translatedtitle">Crustal architecture and deep structure of the Namibian passive <span class="hlt">continental</span> margin around Walvis Ridge from wide-angle seismic data</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The opening of the South Atlantic ocean basin was accompanied by voluminous magmatism on the conjugate <span class="hlt">continental</span> margins of Africa and South America, including the formation of the Parana and Entendeka large igneous provinces (LIP), the build-up of up to 100 km wide volcanic wedges characterized by seaward dipping reflector sequences (SDR), as well as the formation of paired hotspot tracks on the rifted African and South American <span class="hlt">plates</span>, the Walvis Ridge and the Rio Grande Rise. The area is considered as type example for hotspot or plume-related <span class="hlt">continental</span> break-up. However, SDR, and LIP-related features on land are concentrated south of the hotspot tracks. The segmentation of the margins offers a prime opportunity to study the magmatic signal in space and time, and investigate the interrelation with rift-related deformation. A globally significant question we address here is whether magmatism drives <span class="hlt">continental</span> break-up, or whether even rifting accompanied by abundant magmatism is in response to crustal and lithospheric stretching governed by large-scale <span class="hlt">plate</span> kinematics. In 2010/11, an amphibious set of wide-angle seismic data was acquired around the landfall of Walvis Ridge at the Namibian passive <span class="hlt">continental</span> margin. The experiments were designed to provide crustal velocity information and to investigate the structure of the upper mantle. In particular, we aimed at identifying deep fault zones and variations in Moho depth, constrain the velocity signature of SDR sequences, as well as the extent of magmatic addition to the lower crust near the continent-ocean transition. Sediment cover down to the igneous basement was additionally constrained by reflection seismic data. Here, we present tomographic analysis of the seismic data of one long NNW oriented profile parallel to the <span class="hlt">continental</span> margin across Walvis Ridge, and a second amphibious profile from the Angola Basin across Walvis Ridge and into the <span class="hlt">continental</span> interior, crossing the area of the Etendeka Plateau basalts. The most striking feature is the sharp transition in crustal structure and thickness across the northern boundary of Walvis Ridge. Thin oceanic crust (6.5 km) of the Angola Basin lies next to the up to 35 km thick igneous crustal root founding the highest elevated northern portions of Walvis Ridge. Both structures are separated by a very large transform fault zone. The velocity structure of Walvis Ridge lower crust is indicative of gabbro, and, in the lowest parts, of cumulate sequences. On the southern side of Walvis Ridge there is a smooth gradation into the adjacent 25-30 km thick crust underlying the ocean-continent boundary, with a velocity structure resembling that of Walvis Ridge The second profile shows a sharp transition from oceanic to rifted <span class="hlt">continental</span> crust. The transition zone may be underlain by hydrated uppermost mantle. Below the Etendeka Plateau, an extensive high-velocity body, likely representing gabbros and their cumulates at the base of the crust, indicates magmatic underplating. We summarize by stating that rift-related lithospheric stretching and associated transform faulting play an <span class="hlt">overriding</span> role in locating magmatism, dividing the margin in a magmatic-dominated segment to the south, and an amagmatic segment north of Walvis Ridge.</p> <div class="credits"> <p class="dwt_author">Behrmann, Jan H.; Planert, Lars; Jokat, Wilfried; Ryberg, Trond; Bialas, Jörg; Jegen, Marion</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">122</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1991Tectp.186..365M"> <span id="translatedtitle">Gravity field and deep structure of the Bengal Fan and its surrounding <span class="hlt">continental</span> margins, northeast Indian Ocean</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A revised gravity anomaly map for the northeast Indian Ocean shows that the shelf edge underlying the eastern <span class="hlt">continental</span> margin of India is a rather narrow but extensively linear gravity low (minimum free-air = -149 mGal). The Bengal Fan seaward of the shelf has a depressed gravity field (average free-air = -20 to -30 mGal) in spite of the enormous thickness of sediments of as much as 10-15 km. The two buried ridges below the Bengal Fan—the 85° East and 90° East Ridges—have a large negative (-75 mgal) and a substantial positive (40 mGal) free-air anomaly, respectively. The Andaman and Burmese arcs lying along the east margin of the Bengal Fan are active subduction areas which have typical bipolar gravity signatures with a maximum amplitude of 300 mGal. Gravity interpretation for three regional traverses across the central and northern parts of the Bengal Fan and their surrounding <span class="hlt">continental</span> margins suggests that a thickened oceanic crustal wedge juxtaposes the transitional crust under the eastern <span class="hlt">continental</span> slope of India; the 85° East Ridge, that was created when the Indian Ocean lithosphere was very juvenile, appears to underlie a nearly 10 km thick and 120 km wide oceanic crustal block consisting of the ridge material embedded in the upper lithosphere; while the 90° East Ridge submarine topography/buried load below the Bengal Fan is probably isostatically compensated by a low-density mass acting as a cushion at the base of the crust. The Bengal Fan crust, with its thick sediment layer, is carried down the Andaman subduction zone to a depth of about 27 km where, possibly, phase transition takes place under higher pressure. The maximum sediment thickness at the Andaman-Burmese subduction zone is of the order of 10-12 km. The gravity model predicts a low density zone about 60 km wide below the Andaman-Burmese volcanic arc, penetrating from crustal to subcrustal depths in the <span class="hlt">overriding</span> Burma <span class="hlt">plate</span>. A more complex density distribution is however, envisaged for the Andaman volcanic arc that is split by the Neogene back arc spreading ridge. The ocean-continent crustal transition possibly occurs farther east of the volcanic arc; below the Shan plateau margin in Burma or below the Mergui terrace at the Malayan <span class="hlt">continental</span> margin east of the Andaman Sea.</p> <div class="credits"> <p class="dwt_author">Mukhopadhyay, Manoj; Krishna, M. R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-02-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">123</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://home.comcast.net/~rhaberlin/ptmod.htm"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics Learning Module</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This <span class="hlt">plate</span> tectonics unit was designed to be used with a college course in physical geography. Subject matter covered includes: the development of the theory including Wegener's <span class="hlt">Continental</span> Drift Hypothesis and the existence of Pangaea, Harry Hess and his work on sea-floor spreading, and the final theory. It points out that global features such as deep oceanic trenches, mid-ocean ridges, volcanic activity, and the location of earthquake epicenters can now be related to the story of <span class="hlt">plate</span> tectonics, since most geological activity occurs along <span class="hlt">plate</span> boundaries. Divergent, convergent and transform <span class="hlt">plate</span> boundaries are discussed in detail. This module contains a study guide and outline notes, study questions, and practice quizzes. One feature of the module is a web exploration section with links to twelve outside sites that augment the instruction.</p> <div class="credits"> <p class="dwt_author">Haberlin, Rita</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">124</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008NatGe...1..549G"> <span id="translatedtitle">Self-subduction of the Pangaean global <span class="hlt">plate</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">One of the most striking and rare occurrences in the Earth's history is the amalgamation of most of the <span class="hlt">continental</span> lithosphere into one supercontinent. The most recent supercontinent, Pangaea, lasted from 320 to 200 million years ago. Here, we show that after the <span class="hlt">continental</span> collisions that led to the formation of Pangaea, <span class="hlt">plate</span> convergence continued in a large, wedge-shaped oceanic tract. We suggest that <span class="hlt">plate</span> strain at the periphery of the supercontinent eventually resulted in self-subduction of the Pangaean global <span class="hlt">plate</span>, when the ocean margin of the continent subducted beneath the <span class="hlt">continental</span> edge at the other end of the same <span class="hlt">plate</span>. Our scenario results in a stress regime within Pangaea that explains the development of a large fold structure near the apex of the Palaeotethys Ocean, extensive lower crustal heating and <span class="hlt">continental</span> magmatism at the core of the continent as well as the development of radially arranged <span class="hlt">continental</span> rifts in more peripheral regions of the <span class="hlt">plate</span>.</p> <div class="credits"> <p class="dwt_author">Gutiérrez-Alonso, Gabriel; Fernández-Suárez, Javier; Weil, Arlo B.; Brendan Murphy, J.; Damian Nance, R.; Corfú, Fernando; Johnston, Stephen T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">125</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54017523"> <span id="translatedtitle">Paleoseismology of Upper <span class="hlt">Plate</span> Faults in the Chilean Covergent Margin: Insights from 10BE and OSL Dating</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Chilean convergent margin is the locus of most of the largest subduction earthquakes recorded in history. Slip deficit along this <span class="hlt">plate</span> boundary is absorbed by elastic deformation of the upper <span class="hlt">plate</span>. Numerical models and geodetic data suggest a fully elastic behaviour of the <span class="hlt">overriding</span> crust and that deformation is balanced between inter- and co-seismic phases earthquake cycle; thus, non</p> <div class="credits"> <p class="dwt_author">G. Gonzalez; J. A. Cortes; S. Binnie; R. Robinson; C. Toledo</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">126</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://webspinners.com/dlblanc/tectonic/ptABCs.php"> <span id="translatedtitle">An Introduction to the ABCs of <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This introduction to <span class="hlt">plate</span> tectonics covers <span class="hlt">plates</span> and boundaries, subduction zones, colliding continents, plumes, and earthquakes. There is also more advanced material on buoyancy, floating continents, and rates of isostasy; sedimentation, <span class="hlt">continental</span> growth, rifts and creation of <span class="hlt">continental</span> margins, passive and active margins, and island arcs and back-arc basins; <span class="hlt">continental</span> collision, folding of sedimentary layers, and collision of cratons; and the mechanism of <span class="hlt">plate</span> tectonics including convective mantles, convection models, distribution of plumes, plume driven convection, <span class="hlt">plate</span> rifting models, and triple junctions.</p> <div class="credits"> <p class="dwt_author">Blanchard, Donald</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">127</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUFM.T31C1855K"> <span id="translatedtitle">The Deformation Mode of <span class="hlt">Continental</span> Lithosphere Thinning Leading to <span class="hlt">Continental</span> Breakup</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Continental</span> breakup and sea-floor spreading initiation is necessarily preceded by thinning of the <span class="hlt">continental</span> lithosphere. The mode of lithosphere deformation responsible for thinning and stretching the <span class="hlt">continental</span> lithosphere leading to rupture of <span class="hlt">continental</span> crust and the initiation of sea-floor spreading remains a key question in understanding <span class="hlt">continental</span> breakup and rifted <span class="hlt">continental</span> margin formation. We use a generalised kinematic model of <span class="hlt">continental</span> lithosphere stretching and thinning to investigate lithosphere response to 4 deformation modes: depth-uniform pure-shear, two-layer decoupled pure-shear, upwelling divergent flow, and buoyancy induced upwelling. The deformation model advects lithosphere and asthenosphere material and temperature in response to these deformation modes, and the isostatic response to crustal thinning and thermal perturbations are used to predict the resulting margin geometry and bathymetry. Horizontal tensile <span class="hlt">plate</span> forces provide the driving force for lithosphere extension. We apply this generalised lithosphere deformation model to the formation of magma poor margins. The dominant deformation mechanism of the topmost cool brittle 10-15 km of the lithosphere is assumed to be by normal faulting, at all times, as observed not only in intra-<span class="hlt">continental</span> rifting but also at slow spreading ocean ridges. Beneath the cool brittle upper lithosphere, deformation may occur by pure-shear, upwelling divergent flow driven by a horizontal <span class="hlt">plate</span> boundary forces (c.f. ocean ridge), or upwelling (small scale convection) arising from thermal and melt buoyancy initiated by pure-shear lithosphere stretching. We compare the predictions of different modes of lithosphere deformation, and their combinations, with observations. Mantle exhumation and apparent observations at <span class="hlt">continental</span> margins of lithosphere and crustal thinning which exceed that predicted from observed upper crustal faulting, assuming depth-uniform (pure-shear) lithosphere stretching, both imply depth-dependent lithosphere stretching and thinning. Beneath the 10-15 km thick cool brittle topmost lithosphere, depth-dependent lithosphere thinning can be achieved by a combination of decoupled pure-shear, buoyancy induced upwelling, or upwelling divergent flow. Lithosphere thinning leading to <span class="hlt">continental</span> breakup, sea-floor spreading initiation and rifted margin formation is most likely achieved by a simultaneous combination of pure-shear and one or more of these other deformation modes. Localised rupture of the strong topmost mantle lid immediately beneath the Moho may play an important role in localising lithosphere breakup rupture and generating depth-dependent lithosphere thinning. Final rupture of <span class="hlt">continental</span> crust at breakup may be controlled by very large normal faults, with tens of km of heave within the cool 10-15 km thick topmost lithosphere, giving rise to broad regions of sub-horizontal exhumed footwall of crust or mantle.</p> <div class="credits"> <p class="dwt_author">Kusznir, N. J.; Manatschal, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">128</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=COM7311134"> <span id="translatedtitle">Paleomagnetism: One Key to <span class="hlt">Plate</span> Tectonics.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The article explains that glabal or <span class="hlt">plate</span> tectonics combines the hypothesis of seafloor spreading and <span class="hlt">continental</span> drift. It suggests that the earth's surface is made up of huge crustal <span class="hlt">plates</span> which are moving relative to one another. The motion of one pla...</p> <div class="credits"> <p class="dwt_author">H. Spall</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">129</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.wegener1/"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics: The Scientist Behind the Theory</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This video segment adapted from A Science Odyssey profiles Alfred Wegener, the scientist who first proposed the theory of <span class="hlt">continental</span> drift. Initially criticized, his theory was accepted after further evidence revealed the existence of tectonic <span class="hlt">plates</span> and showed that these <span class="hlt">plates</span> move.</p> <div class="credits"> <p class="dwt_author">Foundation, Wgbh E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-12-17</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">130</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012PhDT.......185P"> <span id="translatedtitle">Dynamic Analysis of Modifications to Simple <span class="hlt">Plate</span> Tectonic Theory</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A number of geological and geophysical observations suggest significant departures from simple, first-order <span class="hlt">plate</span> tectonic theory. In this thesis we address the dynamic implications of some of these observations and propose generalized theories to explain their dynamics and conditions of formation. In Chapter 2, we develop a generalized theory and analytic model to predict the conditions under which large-volume removal of <span class="hlt">continental</span> lithosphere can occur through the formation of drip instabilities. Using damage physics relevant for Earth, we find a large portion of the lithosphere may be mobilized and entrained into growing drip instabilities. For a critical amount of damage, the growth is accelerated sufficiently that large-volume drip instabilities may form within geologically feasible time frames. Our model suggests large-volume lithospheric drip instabilities may arise independently of tectonic settings through damage-assisted mobilization and entrainment of the highly viscous lithosphere. In Chapter 3, we develop a mechanical model independent of volcanism and thermal weakening to explain the initial formation and length scale of rifting and extension near convergent <span class="hlt">plate</span> boundaries. We conduct a linear stability analysis of a simple viscous necking model, which includes the lithosphere's negative buoyancy, non-Newtonian rheology, and freely moving top surface, to determine which properties of the lithosphere govern the location of rifting. We find that the negative buoyancy of the lithosphere promotes the formation of rifting structures when simple Newtonian viscosities are present. However, localized weakening, introduced through a power law exponent, is required to generate realistic rifting length scales. Our model suggests that the initial location of rifting in the <span class="hlt">overriding</span> <span class="hlt">plate</span> at subduction zones is primarily due to the mechanical extension induced by rollback of the subducting slab. In Chapter 4, we propose a theory to explain the seismic anisotropy directions observed in the subslab mantle of subduction zones globally. We develop a three-dimensional model using COMSOL Multiphysics® to investigate how interactions among the background mantle flow, trench migration, and the geometry of the slab determine the flow direction in the subslab mantle. We find that flow directions are determined primarily by the amount of coupling between the slab and the mantle, and the interaction between the net background flow (including trench migration) and the slab geometry. We present three-dimensional finite strain calculations, which demonstrate that the maximum stretching directions are aligned with the model subslab flow directions, allowing us to compare our flow directions directly to seismic anisotropy splitting directions of subduction zones globally. Our model successfully predicts the flow directions (parallel or perpendicular) suggested by a global dataset of fast splitting directions using only the net background mantle flow, and slab dip and depth.</p> <div class="credits"> <p class="dwt_author">Paczkowski, Karen</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">131</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5456289"> <span id="translatedtitle">Earthquakes in stable <span class="hlt">continental</span> crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Earthquakes can strike even in stable crust, well away from the familiar earthquake zones at the edges of tectonic <span class="hlt">plates</span>, but their mere occurrence is both a source of concern in planning critical facilities such as nuclear power plants. The authors sought answers to two major questions: Just how much seismic activity does take place within the stable parts of continents And are there specific geologic features that make some areas of stable crust particularly susceptible to earthquakes They began by studying North America alone, but it soon became clear that the fairly short record of these rare events on a single continent would not provide enough data for reliable analysis. Hence, they decided to substitute space for time--to survey earthquake frequency and distribution in stable <span class="hlt">continental</span> areas worldwide. This paper discusses their findings.</p> <div class="credits"> <p class="dwt_author">Johnson, A.C.; Kanter, L.R. (Memphis State Univ., TN (USA))</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">132</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6270979"> <span id="translatedtitle">Oceanology of the antarctic <span class="hlt">continental</span> shelf: Volume 43</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This book discusses the seas of the deep <span class="hlt">continental</span> shelf, which play an important climatic role in sea ice production, deep ocean ventilation and wastage of the Antarctic ice sheet. This volume includes analyses of measurements taken from ships and satellites, and from sea ice and glacial ice. High resolution profiling equipment, long term bottom-moored instruments, continuous remote sensors, geochemical tracers and computer models have provided the basis for new insights into the <span class="hlt">continental</span> shelf circulation. Color <span class="hlt">plates</span> and an accompanying GEBCO Circum-Antarctic map effectively portray the <span class="hlt">continental</span> shelf in relation to the glaciated continent, the sea ice and the surrounding Southern Ocean.</p> <div class="credits"> <p class="dwt_author">Jacobs, S.S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">133</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19760022699&hterms=Tectonic+Plates&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2522Tectonic%2BPlates%2522"> <span id="translatedtitle">Thermal and mechanical structure of the upper mantle: A comparison between <span class="hlt">continental</span> and oceanic models</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Temperature, velocity, and viscosity profiles for coupled thermal and mechanical models of the upper mantle beneath <span class="hlt">continental</span> shields and old ocean basins show that under the continents, both tectonic <span class="hlt">plates</span> and the asthenosphere, are thicker than they are beneath the oceans. The minimum value of viscosity in the <span class="hlt">continental</span> asthenosphere is about an order of magnitude larger than in the shear zone beneath oceans. The shear stress or drag underneath <span class="hlt">continental</span> <span class="hlt">plates</span> is also approximately an order of magnitude larger than the drag on oceanic <span class="hlt">plates</span>. Effects of shear heating may account for flattening of ocean floor topography and heat flux in old ocean basins.</p> <div class="credits"> <p class="dwt_author">Froidevaux, C.; Schubert, G.; Yuen, D. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1976-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">134</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3693770"> <span id="translatedtitle">Can Preoccupation with Alcohol <span class="hlt">Override</span> the Protective Properties of Mindful Awareness on Problematic Drinking?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Objectives To assess the mediating role of drinking restraint— specifically preoccupation with drinking— on the associations between mindful awareness and alcohol consumption and alcohol-related problems. Methods 390 heavy-drinking, undergraduate, college students (52% male) were assessed on measures of mindfulness, drinking restraint, alcohol consumption (prior 90-days), and alcohol-related problems via self-report surveys. Results Mindfulness was negatively associated with alcohol consumption, problems, and both factors of drinking restraint (emotional preoccupation and behavioral constraint). Emotional preoccupation, but not behavioral constraint, statistically mediated these relationships and demonstrated positive associations with both alcohol consumption and related problems. Conclusions Results replicate previous findings documenting a negative association between mindfulness and alcohol consumption and problems. Statistical mediation models suggest that preoccupation with drinking may be a risk factor that <span class="hlt">over-rides</span> the health-promoting effects of mindfulness.</p> <div class="credits"> <p class="dwt_author">Bramm, Stephanie M.; Cohn, Amy M.; Hagman, Brett T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">135</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006RvGeo..44.4002S"> <span id="translatedtitle">Subduction evolution and mantle dynamics at a <span class="hlt">continental</span> margin: Central North Island, New Zealand</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Central North Island, New Zealand, provides an unusually complete geological and geophysical record of the onset and evolution of subduction at a <span class="hlt">continental</span> margin. Whereas most subduction zones are innately two-dimensional, North Island of New Zealand displays a distinct three-dimensional character in the back-arc regions. Specifically, we observe "Mariana-type" subduction in the back-arc areas of central North Island in the sense of back-arc extension, high heat flow, prolific volcanism, geothermal activity, and active doming and exhumation of the solid surface. Evidence for emplacement of a significant percent of new lithosphere beneath the central North Island comes from heat flux of 25 MW/km of strike (of volcanic zone) and thinned crust underlain by rocks with a seismic wave speed consistent with underplated new crust. Seismic attenuation (Qp-1) is high (˜240), and rhyolitic and andesitic volcanism are widespread. Almost complete removal of mantle lithosphere is inferred here in Pliocene times on the basis of the rock uplift history and upper mantle seismic velocities as low as 7.4 ± 0.1 km/s. In contrast, southwestern North Island exhibits "Chilean-type" back-arc activity in the sense of compressive tectonics, reverse faulting, low-heat-flow, thickened lithosphere, and strong coupling between the subducted and <span class="hlt">overriding</span> <span class="hlt">plates</span>. This rapid switch from Mariana-type to Chilean-type subduction occurs despite the age of the subducted <span class="hlt">plate</span> being constant under North Island. Moreover, stratigraphic evidence shows that processes that define the extensional back-arc area (the Central Volcanic Region) are advancing southward into the compressional system (Wanganui Basin) at about 10 mm/yr. We link the progression from one system to another to a gradual and viscous removal of thickened mantle lithosphere in the back-arc regions. Thickening occurred during the Miocene within the Taranaki Fault Zone. The process of thickening and convective removal is time- and temperature-dependent and has left an imprint in both the geological record and geophysical properties of central North Island, which we document and describe.</p> <div class="credits"> <p class="dwt_author">Stern, T. A.; Stratford, W. R.; Salmon, M. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">136</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5105325"> <span id="translatedtitle"><span class="hlt">Plate</span> motion</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The motion of tectonic <span class="hlt">plates</span> on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current <span class="hlt">plate</span> motions, diffuse <span class="hlt">plate</span> boundaries and the oceanic lithosphere, the relation between <span class="hlt">plate</span> motions and distributed deformations, accelerations and the steadiness of <span class="hlt">plate</span> motions, the distribution of current Pacific-North America motion across western North America and its margin, <span class="hlt">plate</span> reconstructions and their uncertainties, hotspots, and <span class="hlt">plate</span> dynamics. A comprehensive bibliography is provided. 126 refs.</p> <div class="credits"> <p class="dwt_author">Gordon, R.G. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">137</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.T13F..04C"> <span id="translatedtitle">Relict basin closure during initial suturing accommodates <span class="hlt">continental</span> convergence with minimal crustal shortening or reduction in convergence rates</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In both the Indo-Eurasian and Arabia-Eurasian (Ab-Eu) collisions, documented post-collisional crustal shortening is hundreds to thousands of kilometers less than the amount of <span class="hlt">plate</span> convergence determined from independent <span class="hlt">plate</span> reconstructions. We propose that relict-basin closure may help resolve such shortening deficits, based on a synthesis of the late Cenozoic evolution of the Greater Caucasus Mountains in the Ab-Eu collision zone. This range is located ~700 km north of the Bitlis suture and defines the northern margin of the Ab-Eu collision zone between the Black and Caspian seas. The range formed from late Cenozoic tectonic inversion of the Greater Caucasus basin, a relict Mesozoic back-arc basin that originally formed in the Jurassic during north-dipping subduction of Neo-Tethys and rifting of the Lesser Caucasus arc from the southern margin of Eurasia (i.e., Scythia). This basin was originally wide enough to prevent sedimentary exchange of turbidites across it, as shown by provenance studies using U-Pb detrital zircon geochronology. The floor of the relict basin now forms a NE-dipping slab that extends to at least 158 km depth beneath the central and eastern Greater Caucasus, as revealed by a new earthquake compilation. Miocene to Quaternary felsic volcanic and intrusive rocks in the Greater Caucasus have geochemical signatures and eruptive centers similar to those in <span class="hlt">continental</span> margin arcs. Based on these data we propose the Ab-Eu collision occurred in two stages. The first (soft collision) started when Arabia collided with Eurasia, closed the Bitlis suture, and caused the locus of convergence to jump ~700 km north to the Greater Caucasus basin. Initial exhumation of the Greater Caucasus started at ~25-30 Ma and continued until ~ 5 Ma at rates of a few °C/Ma during north-directed subduction of the back-arc basin, with little structural evidence of this crustal shortening preserved. The second phase (hard collision) started at ~ 5 Ma, when the relict basin finally closed and the Lesser Caucasus collided with Scythia and increased exhumation rates by as much as a factor of ten. Relict basin closure appears to have had a significant impact on the mechanical behavior of the Ab-Eu collision and appears to explain why deceleration of <span class="hlt">plate</span> convergence was delayed 20-25 Myr after initial collision. Specifically, we suggest that initial collision and formation of the Bitlis suture did not significantly impede Ab-Eu convergence because deformation could jump to a relict basin within the <span class="hlt">overriding</span> <span class="hlt">plate</span>, continuing apace until that relict basin closed and triggered a switch from soft to hard collision and an associated structural reorganization of the whole Ab-Eu collision zone. Formation of such relict basins is likely common along <span class="hlt">continental</span> margins during the protracted subduction and terrane accretion that occurs prior to <span class="hlt">continental</span> collision at the end of a Wilson cycle. The Ab-Eu collision demonstrates the fundamental role that such basins can play in determining the deformational response of a continent during early collision.</p> <div class="credits"> <p class="dwt_author">Cowgill, E.; Forte, A. M.; Niemi, N. A.; Mumladze, T.; Elashvili, M.; Javakhishvili, Z.; Trexler, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">138</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1993E%26PSL.117..457W"> <span id="translatedtitle">Evidence for extension in the western Alpine orogen: the contact between the oceanic Piemonte and overlying <span class="hlt">continental</span> Sesia units</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the Alps and other orogens, major tectonic contacts must have been established during convergence and overthrusting. What is less clear is how strongly these contacts were modified as the orogen evolved. During Alpine collision, <span class="hlt">continental</span> crust of the <span class="hlt">overriding</span> <span class="hlt">plate</span>, the Sesia unit, is inferred to have been thrust northwest over oceanic material of the Piemonte unit. Both units preserve, in parts, eclogite facies metamorphism. However, all structures along this contact in our study area indicate that final movement was southeast directed (with no clear evidence of the kinematics of earlier movement). These structures include SE-verging folds, SE-directed shear bands, and larger normal faults downthrowing to the southeast. It is inferred that there was a SE-directed shear regime below the contact which, although locally buckling and shortening earlier lithological contacts, was dominantly extensional with respect to pre-existing tectonic layering. The lower limit of this shear regime has not been identified, although SE-directed shear is common throughout the upper, greenschist facies part of the Piemonte unit. We show that this shear passes beneath the Sesia zone and does not re-emerge. It is therefore a shear which was net extensional relative both to the modern surface and to the palaeosurface. It may have contributed to the unroofing of eclogite facies rocks in the lower part of the Piemonte unit, although additional timing data are required to clarify this. Nearby, SE-directed shears buckle and imbricate earlier layering within the Piemonte unit. These are normally identified as backthrusts, yet they do not appear to breach the base of the Sesia unit and might merge with the extensional shear. Even though these structures shorten layering, they too could have been extensional relative to the Earth's surface. The significance of Alpine 'backthrusts' should be reappraised in this context. This study indicates that hinterland-directed extension could have been an important phenomenon during Alpine evolution.</p> <div class="credits"> <p class="dwt_author">Wheeler, John; Butler, Robert W. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">139</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/255112"> <span id="translatedtitle">Initiation and propagation of shear zones in a heterogeneous <span class="hlt">continental</span> lithosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Numerical methods were used to investigate the deformation of a <span class="hlt">continental</span> <span class="hlt">plate</span> in northeastern Brazil. Of particular interest are the perturbations induced by a stiff compressional deformation of a highly heterogeneous <span class="hlt">continental</span> lithosphere on the development of a shear zone formed at the termination of a stiff block.</p> <div class="credits"> <p class="dwt_author">Tommasi, A.; Vauchez, A. [CNRS/Universite de Montpellier II (France)] [CNRS/Universite de Montpellier II (France)</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-11-10</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">140</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1992JGR....97..449B"> <span id="translatedtitle">Great thrust earthquakes and aseismic slip along the <span class="hlt">plate</span> boundary of the Makran Subduction Zone</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Makran subduction zone of Iran and Pakistan exhibits strong variation in seismicity between its eastern and western segments and has one of the world's largest forearcs. We determine the source parameters for 14 earthquakes at Makran including the great (Mw 8.1) earthquake of 1945 (the only instrumentally recorded great earthquake at Makran); we determine the loci of seismic and aseismic slip along the <span class="hlt">plate</span> boundary, and we assess the effects of the large forearc and accretionary wedge on the style of <span class="hlt">plate</span> boundary slip. We apply body waveform inversions and, for small-magnitude events, use first motions of P waves to estimate earthquake source parameters. For the 1945 event we also employ dislocation modeling of uplift data. We find that the earthquake of 1945 in eastern Makran is an interplate thrust event that ruptured approximately one-fifth the length of the subduction zone. Nine smaller events in eastern Makran that are also located at or close to the <span class="hlt">plate</span> interface have thrust mechanisms similar to that of the 1945 shock. Seaward of these thrust earthquakes lies the shallowest 70-80 km of the <span class="hlt">plate</span> boundary; we find that this segment and the overlying accretionary wedge remain aseismic both during and between great earthquakes. This aseismic zone, as in other subduction zones, lies within that part of the accretionary wedge that consists of largely uconsolidated sediments (seismic velocities less than 4.0 km/s). The existence of thrust earthquakes indicates that either the sediments along the <span class="hlt">plate</span> boundary in eastern Makran become sufficiently well consolidated and de watered about 70 km from the deformation front or older, lithified rocks are present within the forearc so that stick-slip sliding behavior becomes possible. This study shows that a large quantity of unconsolidated sediment does not necessarily indicate a low potential for great thrust earthquakes. In contrast to the east, the <span class="hlt">plate</span> boundary in western Makran has no clear record of historic great events, nor has modem instrumentation detected any shallow thrust events for at least the past 25 years. Most earthquakes in western Makran occur within the downgoing <span class="hlt">plate</span> at intermediate depths. The large change in seismicity between eastern and western Makran along with two shallow events that exhibit right-lateral strike-slip motion in central Makran suggest segmentation of the subduction zone. Two Paleozoic <span class="hlt">continental</span> blocks dominate the <span class="hlt">overriding</span> <span class="hlt">plate</span>. The boundary between them is approximately coincident with the transition in seismicity. Although relative motion between these blocks may account for some of the differing seismic behavior, the continuity of the deformation front and of other tectonic features along the subduction zone suggests that the rate of subduction does not change appreciably from east to west. The absence of <span class="hlt">plate</span> boundary events in western Makran indicates either that entirely aseismic subduction occurs or that the <span class="hlt">plate</span> boundary is currently locked and experiences great earthquakes with long repeat times. Evidence is presently inconclusive concerning which of these two hypotheses is most correct. The presence of well-defined late Holocene marine terraces along portions of the coasts of eastern and western Makran could be interpreted as evidence that both sections of the arc are capable of generating large <span class="hlt">plate</span> boundary earthquakes. If that hypothesis is correct, then western Makran could produce a great earthquake or it could rupture as a number of segments in somewhat smaller-magnitude events. Alternatively, it is possible that western Makran is significantly different from eastern Makran and experiences largely aseismic slip at all times. A knowledge of the velocity structure and nature of the state of consolidation or lithification of rocks at depth in the interior portion of the forearc of western Makran should help to ascertain whether that portion of the <span class="hlt">plate</span> boundary moves aseismically or ruptures in large to great earthquakes. A resolution of this question has important implications for seismic hazard not </p> <div class="credits"> <p class="dwt_author">Byrne, Daniel E.; Sykes, Lynn R.; Davis, Dan M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_6");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' 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showDiv("page_9");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">141</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012SolE....3..387B"> <span id="translatedtitle">Insight into collision zone dynamics from topography: numerical modelling results and observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Dynamic models of subduction and <span class="hlt">continental</span> collision are used to predict dynamic topography changes on the <span class="hlt">overriding</span> <span class="hlt">plate</span>. The modelling results show a distinct evolution of topography on the <span class="hlt">overriding</span> <span class="hlt">plate</span>, during subduction, <span class="hlt">continental</span> collision and slab break-off. A prominent topographic feature is a temporary (few Myrs) basin on the <span class="hlt">overriding</span> <span class="hlt">plate</span> after initial collision. This "collisional mantle dynamic basin" (CMDB) is caused by slab steepening drawing, material away from the base of the <span class="hlt">overriding</span> <span class="hlt">plate</span>. Also, during this initial collision phase, surface uplift is predicted on the <span class="hlt">overriding</span> <span class="hlt">plate</span> between the suture zone and the CMDB, due to the subduction of buoyant <span class="hlt">continental</span> material and its isostatic compensation. After slab detachment, redistribution of stresses and underplating of the <span class="hlt">overriding</span> <span class="hlt">plate</span> cause the uplift to spread further into the <span class="hlt">overriding</span> <span class="hlt">plate</span>. This topographic evolution fits the stratigraphy found on the <span class="hlt">overriding</span> <span class="hlt">plate</span> of the Arabia-Eurasia collision zone in Iran and south east Turkey. The sedimentary record from the <span class="hlt">overriding</span> <span class="hlt">plate</span> contains Upper Oligocene-Lower Miocene marine carbonates deposited between terrestrial clastic sedimentary rocks, in units such as the Qom Formation and its lateral equivalents. This stratigraphy shows that during the Late Oligocene-Early Miocene the surface of the <span class="hlt">overriding</span> <span class="hlt">plate</span> sank below sea level before rising back above sea level, without major compressional deformation recorded in the same area. Our modelled topography changes fit well with this observed uplift and subsidence.</p> <div class="credits"> <p class="dwt_author">Bottrill, A. D.; van Hunen, J.; Allen, M. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">142</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003AGUFM.S22A0410T"> <span id="translatedtitle">Rheology of the <span class="hlt">continental</span> lithosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The deformation of the <span class="hlt">continental</span> lithosphere is associated with a combination of ductile and brittle processes. Ductile deformation is analyzed utilizing creep (Newtonian, non-Newtonian) and plastic rheologies. These can be extremely sensitive to composition and temperature. In some cases elastic stresses are relaxed, but in other cases elastic stresses are preserved over 108-109 years. The distinction between renewable stress (<span class="hlt">plate</span> tectonic, bending) and nonrenewable (thermal, membrane) must be made. The concept of a yield stress is blurred. Brittle deformation tends to be much more complex. Displacements on faults certainly play an important role, but faults are present at all scales. Under some circumstances it is appropriate to treat these deformations in a continuum manner. An avenue for doing this is damage mechanics. The concept of damage mechanics have been utilized widely in engineering problems. We show that when damage mechanics is applied to the brittle deformation of the upper <span class="hlt">continental</span> crust, a non-Newtonian, power-law viscous rheology is derived. There is a well defined yield stress that can be associated with the dynamic coefficient of friction. Below this stress the upper crust behaves elastically and can act as a stress guide. Above the yield stress the continuum deformations can be modeled as a power-law viscous fluid (with exponent,l 10). This behavior is associated with aftershock sequences. A main shock suddenly increases the stress in regions of the upper crust. Stress relaxation is accomplished by the aftershock sequence and Omori­Ýs law for the decay of aftershocks quantifies the relevant fluid rheology.</p> <div class="credits"> <p class="dwt_author">Turcotte, D. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">143</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013E%26PSL.381..166H"> <span id="translatedtitle">The extent of <span class="hlt">continental</span> crust beneath the Seychelles</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The granitic islands of the Seychelles Plateau have long been recognised to overlie <span class="hlt">continental</span> crust, isolated from Madagascar and India during the formation of the Indian Ocean. However, to date the extent of <span class="hlt">continental</span> crust beneath the Seychelles region remains unknown. This is particularly true beneath the Mascarene Basin between the Seychelles Plateau and Madagascar and beneath the Amirante Arc. Constraining the size and shape of the Seychelles <span class="hlt">continental</span> fragment is needed for accurate <span class="hlt">plate</span> reconstructions of the breakup of Gondwana and has implications for the processes of <span class="hlt">continental</span> breakup in general. Here we present new estimates of crustal thickness and VP/VS from H-? stacking of receiver functions from a year long deployment of seismic stations across the Seychelles covering the topographic plateau, the Amirante Ridge and the northern Mascarene Basin. These results, combined with gravity modelling of historical ship track data, confirm that <span class="hlt">continental</span> crust is present beneath the Seychelles Plateau. This is ˜30-33 km thick, but with a relatively high velocity lower crustal layer. This layer thins southwards from ˜10 km to ˜1 km over a distance of ˜50 km, which is consistent with the Seychelles being at the edge of the Deccan plume prior to its separation from India. In contrast, the majority of the Seychelles Islands away from the topographic plateau show no direct evidence for <span class="hlt">continental</span> crust. The exception to this is the island of Desroche on the northern Amirante Ridge, where thicker low density crust, consistent with a block of <span class="hlt">continental</span> material is present. We suggest that the northern Amirantes are likely <span class="hlt">continental</span> in nature and that small fragments of <span class="hlt">continental</span> material are a common feature of plume affected <span class="hlt">continental</span> breakup.</p> <div class="credits"> <p class="dwt_author">Hammond, J. O. S.; Kendall, J.-M.; Collier, J. S.; Rümpker, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">144</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19890026387&hterms=Plate+Tectonics&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2522Plate%2BTectonics%2522"> <span id="translatedtitle">Beyond <span class="hlt">plate</span> tectonics - Looking at <span class="hlt">plate</span> deformation with space geodesy</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The requirements that must be met by space-geodetic systems in order to constrain the horizontal secular motions associated with the geological deformation of the earth's surface are explored. It is suggested that in order to improve existing <span class="hlt">plate</span>-motion models, the tangential components of relative velocities on interplate baselines must be resolved to an accuracy of less than 3 mm/yr. Results indicate that measuring the velocities between crustal blocks to + or - 5 mm/yr on 100-km to 1000-km scales can produce geologically significant constraints on the integrated deformation rates across <span class="hlt">continental</span> <span class="hlt">plate</span>-boundary zones such as the western United States.</p> <div class="credits"> <p class="dwt_author">Jordan, Thomas H.; Minster, J. Bernard</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">145</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.vims.edu/bridge/archive0902.html"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">In this activity students use data from underwater earthquakes to outline the location of <span class="hlt">plate</span> boundaries. Data from the Northeast Pacific, eastern Equatorial Pacific, and North Atlantic are examined in more detail. Background information on <span class="hlt">plate</span> tectonics is provided.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">146</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013Tectp.609..651H"> <span id="translatedtitle"><span class="hlt">Continental</span> growth and the crustal record</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">continental</span> crust is the archive of Earth history. The spatial and temporal distribution of the Earth's record of rock units and events is heterogeneous with distinctive peaks and troughs in the distribution of ages of igneous crystallisation, metamorphism, <span class="hlt">continental</span> margins and mineralisation. This distribution reflects the different preservation potential of rocks generated in different tectonic settings, rather than fundamental pulses of activity, and the peaks of ages are linked to the timing of supercontinent assembly. In contrast there are other signals, such as the Sr isotope ratios of seawater, mantle temperatures, and redox conditions on the Earth, where the records are regarded as primary because they are not sensitive to the numbers of samples of different ages that have been analysed. New models based on the U-Pb, Hf and O isotope ratios of detrital zircons suggest that at least ~ 60-70% of the present volume of the <span class="hlt">continental</span> crust had been generated by 3 Ga. The growth of <span class="hlt">continental</span> crust was a continuous rather than an episodic process, but there was a marked decrease in the rate of crustal growth at ~ 3 Ga. This appears to have been linked to significant crustal recycling and the onset <span class="hlt">plate</span> tectonics. The 60-70% of the present volume of the <span class="hlt">continental</span> crust estimated to have been present at 3 Ga, contrasts markedly with the < 10% of crust of that age apparently still preserved and it requires ongoing destruction (recycling) of early formed crust and subcontinental mantle lithosphere back into the mantle through processes such as subduction and delamination.</p> <div class="credits"> <p class="dwt_author">Hawkesworth, Chris; Cawood, Peter; Dhuime, Bruno</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">147</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.uky.edu/AS/Geology/howell/goodies/elearning/module04swf.swf"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This interactive Flash explores <span class="hlt">plate</span> tectonics and provides an interactive map where users can identify <span class="hlt">plate</span> boundaries with name and velocities as well as locations of earthquakes, volcanoes, and hotspots. The site also provides animations and supplementary information about <span class="hlt">plate</span> movement and subduction. This resource is a helpful overview or review for introductory level high school or undergraduate physical geology or Earth science students.</p> <div class="credits"> <p class="dwt_author">Smoothstone; Company, Houghton M.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">148</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ia.usu.edu/viewproject.php?project=ia:15692"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">Create a poster all about <span class="hlt">Plate</span> Tectonics! Directions: Make a poster about <span class="hlt">Plate</span> Tectonics. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about <span class="hlt">Plate</span> Tectonics. (5 points ...</p> <div class="credits"> <p class="dwt_author">Walls, Mrs.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-30</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">149</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22382982"> <span id="translatedtitle"><span class="hlt">Continental</span> collision slowing due to viscous mantle lithosphere rather than topography.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Because the inertia of tectonic <span class="hlt">plates</span> is negligible, <span class="hlt">plate</span> velocities result from the balance of forces acting at <span class="hlt">plate</span> margins and along their base. Observations of past <span class="hlt">plate</span> motion derived from marine magnetic anomalies provide evidence of how <span class="hlt">continental</span> deformation may contribute to <span class="hlt">plate</span> driving forces. A decrease in convergence rate at the inception of <span class="hlt">continental</span> collision is expected because of the greater buoyancy of <span class="hlt">continental</span> than oceanic lithosphere, but post-collisional rates are less well understood. Slowing of convergence has generally been attributed to the development of high topography that further resists convergent motion; however, the role of deforming <span class="hlt">continental</span> mantle lithosphere on <span class="hlt">plate</span> motions has not previously been considered. Here I show that the rate of India's penetration into Eurasia has decreased exponentially since their collision. The exponential decrease in convergence rate suggests that contractional strain across Tibet has been constant throughout the collision at a rate of 7.03?×?10(-16)?s(-1), which matches the current rate. A constant bulk strain rate of the orogen suggests that convergent motion is resisted by constant average stress (constant force) applied to a relatively uniform layer or interface at depth. This finding follows new evidence that the mantle lithosphere beneath Tibet is intact, which supports the interpretation that the long-term strain history of Tibet reflects deformation of the mantle lithosphere. Under conditions of constant stress and strength, the deforming <span class="hlt">continental</span> lithosphere creates a type of viscous resistance that affects <span class="hlt">plate</span> motion irrespective of how topography evolved. PMID:22382982</p> <div class="credits"> <p class="dwt_author">Clark, Marin Kristen</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">150</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=COM7310657"> <span id="translatedtitle">Antarctica and <span class="hlt">Continental</span> Drift.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary"><span class="hlt">Continental</span> drift reconstructions by computerized matching of the 1,000 fm isobaths are presented for Africa/Antarctica, Australia/Antarctica and India/Antarctica. Sufficiently good congruency is obtained for the first two to suggest that they are probabl...</p> <div class="credits"> <p class="dwt_author">R. S. Dietz J. C. Holden W. P. Sproll</p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">151</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=sedimentation&pg=3&id=EJ285784"> <span id="translatedtitle">The <span class="hlt">Continental</span> Crust.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary"><span class="hlt">Continental</span> crust underlies the continents, their margins, and also small shallow regions in oceans. The nature of the crust (much older than oceanic crust) and its dynamics are discussed. Research related to and effects of tectonics, volcanism, erosion, and sedimentation on the crust are considered. (JN)</p> <div class="credits"> <p class="dwt_author">Burchfiel, B. Clark</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">152</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2706198"> <span id="translatedtitle">Fuelling decisions in migratory birds: geomagnetic cues <span class="hlt">override</span> the seasonal effect</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Recent evaluations of both temporal and spatial precision in bird migration have called for external cues in addition to the inherited programme defining the migratory journey in terms of direction, distance and fuelling behaviour along the route. We used juvenile European robins (Erithacus rubecula) to study whether geomagnetic cues affect fuel deposition in a medium-distance migrant by simulating a migratory journey from southeast Sweden to the wintering area in southern Spain. In the late phase of the onset of autumn migration, robins exposed to the magnetic treatment attained a lower fuel load than control birds exposed to the ambient magnetic field of southeast Sweden. In contrast, robins captured in the early phase of the onset of autumn migration all showed low fuel deposition irrespective of experimental treatment. These results are, as expected, the inverse of what we have found in similar studies in a long-distance migrant, the thrush nightingale (Luscinia luscinia), indicating that the reaction in terms of fuelling behaviour to a simulated southward migration varies depending on the relevance for the species. Furthermore, we suggest that information from the geomagnetic field act as an important external cue <span class="hlt">overriding</span> the seasonal effect on fuelling behaviour in migratory birds.</p> <div class="credits"> <p class="dwt_author">Kullberg, Cecilia; Henshaw, Ian; Jakobsson, Sven; Johansson, Patrik; Fransson, Thord</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">153</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24436125"> <span id="translatedtitle">Enthalpic factors <span class="hlt">override</span> the polyelectrolyte effect in the binding of EGR1 transcription factor to DNA.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Protein-DNA interactions are highly dependent upon salt such that the binding affinity precipitously decreases with increasing salt concentration in a phenomenon termed as the polyelectrolyte effect. In this study, we provide evidence that the binding of early growth response (EGR) 1 transcription factor to DNA displays virtually zero dependence on ionic strength under physiological salt concentrations and that such feat is accomplished via favorable enthalpic contributions. Importantly, we unearth the molecular origin of such favorable enthalpy and attribute it to the ability of H382 residue to stabilize the EGR1-DNA interaction via both intermolecular hydrogen bonding and van der Waals contacts against the backdrop of salt. Consistent with this notion, the substitution of H382 residue with other amino acids faithfully restores salt-dependent binding of EGR1 to DNA in a canonical fashion. Remarkably, H382 is highly conserved across other members of the EGR family, implying that changes in bulk salt concentration are unlikely to play a significant role in modulating protein-DNA interactions central to this family of transcription factors. Taken together, our study reports the first example of a eukaryotic protein-DNA interaction capable of <span class="hlt">overriding</span> the polyelectrolyte effect. PMID:24436125</p> <div class="credits"> <p class="dwt_author">Mikles, David C; Bhat, Vikas; Schuchardt, Brett J; McDonald, Caleb B; Farooq, Amjad</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">154</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3571333"> <span id="translatedtitle">More than Motility: Salmonella Flagella Contribute to <span class="hlt">Overriding</span> Friction and Facilitating Colony Hydration during Swarming</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">We show in this study that Salmonella cells, which do not upregulate flagellar gene expression during swarming, also do not increase flagellar numbers per ?m of cell length as determined by systematic counting of both flagellar filaments and hooks. Instead, doubling of the average length of a swarmer cell by suppression of cell division effectively doubles the number of flagella per cell. The highest agar concentration at which Salmonella cells swarmed increased from the normal 0.5% to 1%, either when flagella were overproduced or when expression of the FliL protein was enhanced in conjunction with stator proteins MotAB. We surmise that bacteria use the resulting increase in motor power to overcome the higher friction associated with harder agar. Higher flagellar numbers also suppress the swarming defect of mutants with changes in the chemotaxis pathway that were previously shown to be defective in hydrating their colonies. Here we show that the swarming defect of these mutants can also be suppressed by application of osmolytes to the surface of swarm agar. The “dry” colony morphology displayed by che mutants was also observed with other mutants that do not actively rotate their flagella. The flagellum/motor thus participates in two functions critical for swarming, enabling hydration and <span class="hlt">overriding</span> surface friction. We consider some ideas for how the flagellum might help attract water to the agar surface, where there is no free water.</p> <div class="credits"> <p class="dwt_author">Partridge, Jonathan D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">155</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850023286&hterms=PangeA&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPangeA"> <span id="translatedtitle"><span class="hlt">Continental</span> magnetic anomaly constraints on <span class="hlt">continental</span> reconstruction</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Crustal magnetic anomalies mapped by the MAGSAT satellite for North and South America, Europe, Africa, India, Australia and Antarctica and adjacent marine areas were adjusted to a common elevation of 400 km and differentially reduced to the radial pole of intensity 60,000 nT. These radially polarized anomalies are normalized for differential inclination, declination and intensity effects of the geomagnetic field, so that in principle they directly reflected the geometric and magnetic polarization attributes of sources which include regional petrologic variations of the crust and upper mantle, and crustal thickness and thermal perturbations. <span class="hlt">Continental</span> anomalies demonstrate remarkably detailed correlation of regional magnetic sources across rifted margins when plotted on a reconstruction of Pangea. Accordingly, they suggest further fundamental constraints on the geologic evolution of the continents and their reconstructions.</p> <div class="credits"> <p class="dwt_author">Vonfrese, R. R. B.; Hinze, W. J.; Olivier, R.; Bentley, C. R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">156</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.boundaries/"> <span id="translatedtitle">Tectonic <span class="hlt">Plates</span> and <span class="hlt">Plate</span> Boundaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This interactive activity adapted from NASA features world maps that identify different sections of the Earth's crust called tectonic <span class="hlt">plates</span>. The locations of different types of <span class="hlt">plate</span> boundaries are also identified, including convergent, divergent, and transform boundaries.</p> <div class="credits"> <p class="dwt_author">Foundation, Wgbh E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-12-17</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">157</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/17jxl0rvh5fb20vl.pdf"> <span id="translatedtitle">The Cretaceous iron belt of northern Chile: role of oceanic <span class="hlt">plates</span>, a superplume event, and a major shear zone</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Cretaceous constitutes a turning point in the tectonic, magmatic, and metallogenic history of Chile. The geological evidence indicates that a major change occurred in late Neocomian time when superplume emplacement (Mid-Pacific Superplume) and <span class="hlt">plate</span> reorganization processes took place in the Pacific. The superplume event resulted in a major ridge-push force resulting in increased coupling between the subducting and <span class="hlt">overriding</span></p> <div class="credits"> <p class="dwt_author">Roberto Oyarzun; Jorge Oyarzán; Jean Jacques Ménard; Javier Lillo</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">158</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6462242"> <span id="translatedtitle">Shallow subduction, ridge subduction, and the evolution of <span class="hlt">continental</span> lithosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Subduction of oceanic lithosphere beneath <span class="hlt">continental</span> crust at a shallow angle has occurred throughout the Phanerozoic Eon. Ridge subduction often follows shallow subduction and causes bimodal volcanism and crustal rifting, forming back-arc basins. Recent models for Archean <span class="hlt">plate</span> tectonics propose very fast rates of spreading (400-800 km/Ma) and convergence, and sinking rates comparable to or slower (<10 km/Ma) than those of today. As faster convergence and slower sinking correspond to subduction at shallower angles, shallow subduction and ridge subduction must have been ubiquitous during the Archean permobile regime. This is compatible with a back-arc-basin origin for Archean greenstone belts. The common coexistence of tholeiitic and calc-alkaline igneous rocks in Archean greenstone belts, also implies ridge subduction. The authors envisage a transition, between 2.4 and 1.8 Ga., from a regime dominated by shallow subduction and repeated ridge subduction to one of normal <span class="hlt">plate</span> tectonics with steeper subduction. Spreading rates decreased; <span class="hlt">continental</span> <span class="hlt">plates</span> became larger and stable shelves could develop at trailing margins. Shallow subduction became the exception, restricted to episodes of abnormally fast convergence; nevertheless, the long span of post-Archean time makes it unlikely that any part of the <span class="hlt">continental</span> crust has escaped shallow subduction and ridge subduction. These processes recycle much volatile-rich oceanic crust into the sub-<span class="hlt">continental</span> upper mantle, thereby underplating the crust, effecting upper-mantle metasomatism and affecting intraplate magmatism.</p> <div class="credits"> <p class="dwt_author">Helmstaedt, H.; Dixon, J.M.; Farrar, E.; Carmichael, D.M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">159</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3325935"> <span id="translatedtitle">Pseudomonas aeruginosa <span class="hlt">Overrides</span> the Virulence Inducing Effect of Opioids When It Senses an Abundance of Phosphate</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">The gut during critical illness represents a complex ecology dominated by the presence of healthcare associated pathogens, nutrient scarce conditions, and compensatory host stress signals. We have previously identified key environmental cues, opioids and phosphate depletion that independently activate the virulence of Pseudomonas aeruginosa. Opioids induce quinolone signal production (PQS), whereas phosphate depletion leads to a triangulated response between MvfR-PQS, pyoverdin, and phosphosensory/phosphoregulatory systems (PstS-PhoB). Yet how P. aeruginosa manages its response to opioids during nutrient scarce conditions when growth is limited and a quorum is unlikely to be achieved is important in the context of pathogenesis in gut during stress. To mimic this environment, we created nutrient poor conditions and exposed P. aeruginosa PAO1 to the specific k-opioid receptor agonist U-50,488. Bacterial cells exposed to the k-opioid expressed a striking increase in virulence- and multi-drug resistance-related genes that correlated to a lethal phenotype in C. elegans killing assays. Under these conditions, HHQ, a precursor of PQS, rather than PQS itself, became the main inducer for pqsABCDE operon expression. P. aeruginosa virulence expression in response to k-opioids required PqsE since ?PqsE was attenuated in its ability to activate virulence- and efflux pumps-related genes. Extracellular inorganic phosphate completely changed the transcriptional response of PAO1 to the k- opioid preventing pqsABCDE expression, the activation of multiple virulence- and efflux pumps-related genes, and the ability of P. aeruginosa to kill C. elegans. These results indicate that when P. aeruginosa senses resource abundance in the form of phosphate, it <span class="hlt">overrides</span> its response to compensatory host signals such as opioids to express a virulent and lethal phenotype. These studies confirm a central role for phosphate in P. aeruginosa virulence that might be exploited to design novel anti- virulence strategies.</p> <div class="credits"> <p class="dwt_author">Zaborin, Alexander; Gerdes, Svetlana; Holbrook, Christopher; Liu, Donald C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">160</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53504798"> <span id="translatedtitle">A Magmatic System as an Indicator of Tectonic Stresses around <span class="hlt">Plate</span> Boundary; Crustal Deformation in and around Izu-Oshima Japan Derived from Continuous GPS Measurments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The area around Izu peninsula Japan is situated in a boundary region between the Philippine Sea <span class="hlt">plate</span> and a <span class="hlt">continental</span> <span class="hlt">plate</span>. There are a number of things that bring a complexity to the tectonic setting of the region; the proximity to a triple junction of a <span class="hlt">continental</span> and two oceanic <span class="hlt">plates</span> and a volcanic front running through being accompanied by</p> <div class="credits"> <p class="dwt_author">M. Murakami</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_7");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">161</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1981ESRv...17...69P"> <span id="translatedtitle">Brazilian <span class="hlt">continental</span> cretaceous</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Cretaceous deposits in Brazil are very well developed, chiefly in <span class="hlt">continental</span> facies and in thick sequences. Sedimentation occurred essentially in rift-valleys inland and along the coast. Three different sequences can be distinguished: (1) a lower clastic non-marine section, (2) a middle evaporitic section, (3) an upper marine section with non-marine regressive lithosomes. <span class="hlt">Continental</span> deposits have been laid down chiefly between the latest Jurassic and Albian. The lower lithostratigraphic unit is represented by red shales with occasional evaporites and fresh-water limestones, dated by ostracods. A series of thick sandstone lithosomes accumulated in the inland rift-valleys. In the coastal basins these sequences are often incompletely preserved. Uplift in the beginning of the Aptian produced a widespread unconformity. In many of the inland rift-valleys sedimentation ceased at that time. A later transgression penetrated far into northeastern Brazil, but shortly after <span class="hlt">continental</span> sedimentation continued, with the deposition of fluvial sandstones which once covered large areas of the country and which have been preserved in many places. The <span class="hlt">continental</span> Cretaceous sediments have been laid down in fluvial and lacustrine environments, under warm climatic conditions which were dry from time to time. The fossil record is fairly rich, including besides plants and invertebrates, also reptiles and fishes. As faulting tectonism was rather strong, chiefly during the beginning of the Cretaceous, intercalations of igneous rocks are frequent in some places. Irregular uplift and erosion caused sediments belonging to the remainder of this period to be preserved only in tectonic basins scattered across the country.</p> <div class="credits"> <p class="dwt_author">Petri, Setembrino; Campanha, Vilma A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">162</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009EGUGA..11.9644K"> <span id="translatedtitle">The mode of lithosphere deformation leading to <span class="hlt">continental</span> breakup and sea-floor spreading initiation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We investigate two contrasting modes of <span class="hlt">continental</span> lithosphere thinning leading to <span class="hlt">continental</span> breakup and sea-floor spreading initiation; lithosphere thinning by pure-shear and by buoyancy assisted upwelling divergent flow. Mantle exhumation at rifted <span class="hlt">continental</span> margins requires that rupture of <span class="hlt">continental</span> crust and the unroofing of mantle occur before the start of significant melt production. The relative timing of the onset of ocean ridge melt production is sensitive not only to extension rate, mantle temperature and mantle depletion but also the deformation mode of <span class="hlt">continental</span> lithosphere thinning leading to <span class="hlt">continental</span> breakup. Two end-member modes of <span class="hlt">continental</span> lithosphere thinning deformation have been examined: depth-uniform (pure-shear) lithosphere stretching and thinning, and lithosphere thinning by upwelling divergent flow. Horizontal tensile <span class="hlt">plate</span> forces provide the driving force for the pure-shear deformation. Upwelling divergent flow is assumed to be driven by a combination of horizontal <span class="hlt">plate</span> boundary forces and thermal and melt buoyancy initiated by pure-shear lithosphere stretching, and predicts a simple transition from pre-breakup lithosphere thinning to sea-floor spreading. For the N. Iberian - N. Newfoundland margins, pure-shear breakup lithosphere thinning model predicts that the onset of melt generation occurs prior to breakup rupture of the <span class="hlt">continental</span> crust for normal mantle temperature and chemical composition. In contrast the upwelling divergent flow model predicts the onset of melt generation after <span class="hlt">continental</span> crust rupture leading to ~ 100 km mantle exhumation on each margin. We propose that <span class="hlt">continental</span> lithosphere thinning leading to <span class="hlt">continental</span> breakup and sea-floor spreading initiation is achieved by a simultaneous combination of pure-shear and buoyancy driven upwelling divergent flow within <span class="hlt">continental</span> lithosphere and asthenosphere. The relative importance of these deformation modes is dependent on depth, pre-breakup extension rates and mantle temperature. Beneath 10-15 km depth the dominant mode of <span class="hlt">continental</span> lithosphere thinning leading to breakup is upwelling divergent flow driven by thermal and melt buoyancy, while for depths shallower than 10-15 km (corresponding to the cooler upper lithosphere) the dominant thinning mode is pure-shear in the form of brittle faulting. While horizontal tensile <span class="hlt">plate</span> forces provide the driving force for the pure-shear deformation, the buoyancy induced upwelling divergence flow provides the main contribution to <span class="hlt">continental</span> lithosphere thinning. Pre-breakup <span class="hlt">continental</span> lithosphere thinning by combined pure shear and buoyancy driven upwelling divergent flow also predicts depth-dependent stretching of <span class="hlt">continental</span> margin lithosphere, the development of pre-breakup sag basins with a paucity of pre-breakup brittle deformation and a simple transition from pre-breakup lithosphere thinning to sea-floor spreading.</p> <div class="credits"> <p class="dwt_author">Kusznir, N. J.; Fletcher, R. J.; Manatschal, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">163</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012SolED...4..889B"> <span id="translatedtitle">Insight into collision zone dynamics from topography: numerical modelling results and observations</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Dynamic models of subduction and <span class="hlt">continental</span> collision are used to predict dynamic topography changes on the <span class="hlt">overriding</span> <span class="hlt">plate</span>. The modelling results show a distinct evolution of topography on the <span class="hlt">overriding</span> <span class="hlt">plate</span>, during subduction, <span class="hlt">continental</span> collision and slab break-off. A prominent topographic feature is a temporary (few Myrs) deepening in the area of the back arc-basin after initial collision. This collisional mantle dynamic basin (CMDB) is caused by slab steepening drawing material away from the base of the <span class="hlt">overriding</span> <span class="hlt">plate</span>. Also during this initial collision phase, surface uplift is predicted on the <span class="hlt">overriding</span> <span class="hlt">plate</span> between the suture zone and the CMDB, due to the subduction of buoyant <span class="hlt">continental</span> material and its isostatic compensation. After slab detachment, redistribution of stresses and underplating of the <span class="hlt">overriding</span> <span class="hlt">plate</span> causes the uplift to spread further into the <span class="hlt">overriding</span> <span class="hlt">plate</span>. This topographic evolution fits the stratigraphy found on the <span class="hlt">overriding</span> <span class="hlt">plate</span> of the Arabia-Eurasia collision zone in Iran and south east Turkey. The sedimentary record from the <span class="hlt">overriding</span> <span class="hlt">plate</span> contains Upper Oligocene-Lower Miocene marine carbonates deposited between terrestrial clastic sedimentary rocks, in units such as the Qom Formation and its lateral equivalents. This stratigraphy shows that during the Late Oligocene-Early Miocene the surface of the <span class="hlt">overriding</span> <span class="hlt">plate</span> sank below sea level before rising back above sea level, without major compressional deformation recorded in the same area. This uplift and subsidence pattern correlates well with our modelled topography changes.</p> <div class="credits"> <p class="dwt_author">Bottrill, A. D.; van Hunen, J.; Allen, M. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">164</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.lp_platetectonics/"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">In this lesson, students are introduced to the theory of <span class="hlt">plate</span> tectonics and explore how the theory was developed and supported by evidence. Through class discussion, videos, and activities, students seek connections between tectonic activity and geologic features and investigate how the theory of <span class="hlt">plate</span> tectonics evolved.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">165</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://orgs.usd.edu/esci/exams/tectonics.html"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This site contains 25 questions on the topic of <span class="hlt">plate</span> tectonics, which covers the development of the theory, crustal movements, geologic features associated with tectonics, and <span class="hlt">plate</span> boundaries (convergent, divergent, transform). This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate verification.</p> <div class="credits"> <p class="dwt_author">Heaton, Timothy</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">166</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://jcb.rupress.org/cgi/reprint/136/1/29.pdf"> <span id="translatedtitle">Chromosomes with Two Intact Axial Cores Are Induced by G2 Checkpoint <span class="hlt">Override</span>: Evidence That DNA Decatenation Is not Required to Template the Chromosome Structure</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Here we report that DNA decatenation is not a physical requirement for the formation of mam- malian chromosomes containing a two-armed chromo- some scaffold. 2-aminopurine <span class="hlt">override</span> of G 2 arrest imposed by VM-26 or ICRF-193, which inhibit topo- isomerase II (topo II)-dependent DNA decatenation, results in the activation of p34 cdc2 kinase and entry into mitosis. After <span class="hlt">override</span> of a</p> <div class="credits"> <p class="dwt_author">Paul R. Andreassen; Françoise B. Lacroix; Robert L. Margolis</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">167</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52271326"> <span id="translatedtitle">Diffuse Oceanic <span class="hlt">Plate</span> Boundaries, Thin Viscous Sheets of Oceanic Lithosphere, and Late Miocene Changes in <span class="hlt">Plate</span> Motion and Tectonic Regime</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Diffuse <span class="hlt">plate</span> boundaries are often viewed as a characteristic only of <span class="hlt">continental</span> lithosphere and as a consequence of its rheology, while narrow boundaries and <span class="hlt">plate</span> rigidity are viewed as characteristic of oceanic lithosphere. Here we review some of the evidence that shows that deformation in the ocean basins is in many places just as diffuse as deformation in the continents.</p> <div class="credits"> <p class="dwt_author">R. G. Gordon; J. Royer</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">168</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://serc.carleton.edu/NAGTWorkshops/geomorph/activities/23500.html"> <span id="translatedtitle"><span class="hlt">Continental</span> Glaciation - Landforms</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">To prepare for this exercise, students participate in a teacher-led discussion about processes of erosion and deposition in different environments under and around <span class="hlt">continental</span> ice sheets. They then work in small groups of 2-3 to examine stereopairs of examples of landforms representative of subglacial and end-glacial settings. The culminating set of questions require them to find and analyze the sequence of formation of a dozen or so landforms from different glacial environments scattered over one topographic quadrangle. Designed for a geomorphology course Has minimal/no quantitative component</p> <div class="credits"> <p class="dwt_author">Whittecar, Rich</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">169</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/18174440"> <span id="translatedtitle">Intermittent <span class="hlt">plate</span> tectonics?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Although it is commonly assumed that subduction has operated continuously on Earth without interruption, subduction zones are routinely terminated by ocean closure and supercontinent assembly. Under certain circumstances, this could lead to a dramatic loss of subduction, globally. Closure of a Pacific-type basin, for example, would eliminate most subduction, unless this loss were compensated for by comparable subduction initiation elsewhere. Given the evidence for Pacific-type closure in Earth's past, the absence of a direct mechanism for termination/initiation compensation, and recent data supporting a minimum in subduction flux in the Mesoproterozoic, we hypothesize that dramatic reductions or temporary cessations of subduction have occurred in Earth's history. Such deviations in the continuity of <span class="hlt">plate</span> tectonics have important consequences for Earth's thermal and <span class="hlt">continental</span> evolution. PMID:18174440</p> <div class="credits"> <p class="dwt_author">Silver, Paul G; Behn, Mark D</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">170</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005PhDT.......150G"> <span id="translatedtitle">Mechanisms of <span class="hlt">continental</span> intraplate earthquakes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">To better understand the mechanisms of <span class="hlt">continental</span> intraplate earthquakes, a multistep approach was used. The first step involved analysis and synthesis of multidisciplinary data from 39 intraplate earthquakes spanning 20 <span class="hlt">continental</span> intraplate regions, to identify their characteristic and diagnostic features. This led to the following testable hypothesis: Intraplate earthquakes occur within pre-existing zones of weakness (most commonly failed rifts), in the vicinity of stress concentrators, such as, intersecting faults, buried plutons, and/or rift pillows in the presence of the ambient stress field. The next step involved testing this hypothesis---first with 2-D mechanical models and then with 3-D models. Since two-thirds of the examined intraplate regions had intersecting faults as a stress concentrator, its role was first evaluated. A Distinct Element Method was used wherein the models comprised of the structural framework of the concerned region represented by a set of rock blocks that are assigned elastic properties conforming to the known geology, and subjected to tectonic loading along the direction of maximum regional compression (S Hmax) at a rate similar to the ambient <span class="hlt">plate</span> velocity. The 2-D modeling was performed for two major intraplate regions in eastern U.S., viz., New Madrid and Middleton Place Summerville seismic zones, using a commercially available code called UDEC. These models adequately explain the spatial distribution of current seismicity in the regions. However, the absence of the third dimension limited the observation of tectonics in the depth dimension. Thus, 3-D models were developed for these two regions using the 3-D version of UDEC, called 3DEC. The preliminary results of these models adequately demonstrate correlation of locations of current seismicity with fault intersections in 3-D space, and also duplicate vertical movements. Although, the mechanical models demonstrated a causal association of seismicity with intersecting faults, their abundance in nature questions their uniqueness in causing seismicity, as many such faults are aseismic. Hence, a 2-D parametric study using UDEC, and a block model consisting of two and three intersecting faults, was performed to investigate whether preferred orientations of intersecting faults were responsible for causing seismicity. In the model, the orientation of the main fault with respect to SHmax was alpha, and the interior angle between the main and intersecting faults was beta. The results of this study showed that the optimum orientation of alpha for causing seismicity was 45° +/- 15°, whereas 65° ? beta ? 125° and 145° ? beta ? 170° were the optimum angles of beta. A similar 2-D parametric study using UDEC was performed of plutons of different shapes, sizes, and density contrasts, to evaluate their role in concentrating stresses to cause seismicity. The results showed that plutons of larger area, ellipticity, and density contrasts concentrated greater shear stresses around their peripheries. Additionally, plutons that are weaker than the surrounding country rocks concentrated larger shear stresses than those that are stronger than them. Cumulatively, the results of this study support the hypothesis of localized stress concentration in response to <span class="hlt">plate</span> tectonic forces.</p> <div class="credits"> <p class="dwt_author">Gangopadhyay, Abhijit Kumar</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">171</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5920133"> <span id="translatedtitle"><span class="hlt">Plate</span> motion and deformation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Our goal is to understand the motions of the <span class="hlt">plates</span>, the deformation along their boundaries and within their interiors, and the processes that control these tectonic phenomena. In the broadest terms, we must strive to understand the relationships of regional and local deformation to flow in the upper mantle and the rheological, thermal and density structure of the lithosphere. The essential data sets which we require to reach our goal consist of maps of current strain rates at the earth's surface and the distribution of integrated deformation through time as recorded in the geologic record. Our success will depend on the effective synthesis of crustal kinematics with a variety of other geological and geophysical data, within a quantitative theoretical framework describing processes in the earth's interior. Only in this way can we relate the snapshot of current motions and earth structure provided by geodetic and geophysical data with long-term processes operating on the time scales relevant to most geological processes. The wide-spread use of space-based techniques, coupled with traditional geological and geophysical data, promises a revolution in our understanding of the kinematics and dynamics of <span class="hlt">plate</span> motions over a broad range of spatial and temporal scales and in a variety of geologic settings. The space-based techniques that best address problems in <span class="hlt">plate</span> motion and deformation are precise space-geodetic positioning -- on land and on the seafloor -- and satellite acquisition of detailed altimetric and remote sensing data in oceanic and <span class="hlt">continental</span> areas. The overall science objectives for the NASA Solid Earth Science plan for the 1990's, are to Understand the motion and deformation of the lithosphere within and across <span class="hlt">plate</span> boundaries'', and to understand the dynamics of the mantle, the structure and evolution of the lithosphere, and the landforms that result from local and regional deformation. 57 refs., 7 figs., 2 tabs.</p> <div class="credits"> <p class="dwt_author">Minster, B.; Prescott, W.; Royden, L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">172</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850028424&hterms=Plate+tectonics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DPlate%2Btectonics"> <span id="translatedtitle">Caribbean tectonics and relative <span class="hlt">plate</span> motions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">During the last century, three different ways of interpreting the tectonic evolution of the Gulf of Mexico and the Caribbean have been proposed, taking into account the Bailey Willis School of a permanent pre-Jurassic deep sea basin, the Edward Suess School of a subsided <span class="hlt">continental</span> terrain, and the Alfred Wegener School of <span class="hlt">continental</span> separation. The present investigation is concerned with an outline of an interpretation which follows that of Pindell and Dewey (1982). An attempt is made to point out ways in which the advanced hypotheses can be tested. The fit of Africa, North America, and South America is considered along with aspects of relative motion between North and South America since the early Jurasic. Attention is given to a framework for reconstructing Caribbean <span class="hlt">plate</span> evolution, the evolution of the Caribbean, the <span class="hlt">plate</span> boundary zones of the northern and southern Caribbean, and the active deformation of the Caribbean <span class="hlt">plate</span>.</p> <div class="credits"> <p class="dwt_author">Burke, K.; Dewey, J. F.; Cooper, C.; Mann, P.; Pindell, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">173</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008AGUFM.T33F..07K"> <span id="translatedtitle">Dependence of Mantle Exhumation at Rifted <span class="hlt">Continental</span> Margins on the Deformation Mode of Breakup Lithosphere Thinning</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Mantle exhumation at rifted <span class="hlt">continental</span> margins requires that rupture of <span class="hlt">continental</span> crust and the unroofing of mantle occurs before the start of significant melt production. The relative timing of the onset of ocean ridge melt production is sensitive not only to extension rate, mantle temperature and mantle depletion but also the deformation mode of <span class="hlt">continental</span> lithosphere thinning leading to <span class="hlt">continental</span> breakup. Two end-member modes of <span class="hlt">continental</span> lithosphere thinning deformation have been examined: depth-uniform (pure-shear) lithosphere stretching and thinning, and lithosphere thinning by upwelling divergent flow. Horizontal tensile <span class="hlt">plate</span> forces provide the driving force for the pure-shear deformation. Upwelling divergent flow is assumed to be driven by a combination of horizontal <span class="hlt">plate</span> boundary forces and thermal and melt buoyancy initiated by pure-shear lithosphere stretching, and predicts a simple transition from pre-breakup lithosphere thinning to sea-floor spreading. For the N. Iberian - N. Newfoundland margins, pure-shear breakup lithosphere thinning model predicts that the onset of melt generation occurs prior to breakup rupture of the <span class="hlt">continental</span> crust for normal mantle temperature and chemical composition. In contrast the upwelling divergent flow model predicts the onset of melt generation after <span class="hlt">continental</span> crust rupture leading to ~ 100 km mantle exhumation on each margin. <span class="hlt">Continental</span> lithosphere thinning leading to <span class="hlt">continental</span> breakup and sea-floor spreading initiation is most likely achieved by a simultaneous combination of pure-shear and upwelling divergent flow within <span class="hlt">continental</span> lithosphere and asthenosphere. The relative importance of these deformation modes is dependent on depth, pre-breakup extension rates and mantle temperature. We proposes that beneath 10-15 km depth the dominant mode of <span class="hlt">continental</span> lithosphere thinning leading to breakup is upwelling divergent flow, while for depths shallower than 10-15 km (corresponding to the cooler upper lithosphere) the dominant thinning mode is pure-shear in the form of brittle faulting.</p> <div class="credits"> <p class="dwt_author">Kusznir, N. J.; Fletcher, R. J.; Manatschal, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">174</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/8090475"> <span id="translatedtitle">Femoral <span class="hlt">plating</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We have demonstrated that we are able to meet both trauma and orthopedic goals with immediate <span class="hlt">plate</span> fixation of femoral fractures in patients with blunt polytrauma. Our femoral fracture mortality rate is less than our predicted institutional mortality rate of patients with comparative injury severity scores. Ipsilateral femoral neck and shaft fractures are easily repaired with femoral <span class="hlt">plating</span>. Infections, even in open fractures and systemically unstable patients, are rare. Implant failures have been infrequent and are easily reconstructed with intramedullary nails. Knee motion has been restored reliably. Stainless steel DCP <span class="hlt">plate</span> fixation requires primary bone grafting. Achieving union and subsequent knee rehabilitation often requires that patients remain on crutches for up to 6 months. Our experience with titanium LCDCP <span class="hlt">plates</span> is preliminary, but we are seeing a significant amount of callus formation and, perhaps, earlier union and bearing weight. PMID:8090475</p> <div class="credits"> <p class="dwt_author">Riemer, B L; Foglesong, M E; Miranda, M A</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">175</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://serc.carleton.edu/NAGTWorkshops/intro/activities/23585.html"> <span id="translatedtitle"><span class="hlt">Plate</span> Motions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">To prepare for this exercise students read the Chapter on <span class="hlt">plate</span> tectonics in their text book. In class, they are given a color isochron map of the sea floor. They are given 4 tasks: Answer basic questions about the timing and rate of opening of the N. and S. Atlantic; Determine what has happened to the oceanic crust that is created on the eastern side of the East Pacific Rise; Determine what type of <span class="hlt">plate</span> boundary existed on the western edge of the N. America <span class="hlt">plate</span> before the San Andreas Fault and when this transition occurred; and Reconstruct the motion of the <span class="hlt">plates</span> over the last 40 Ma assuming that the surface area of the Earth has not changed.</p> <div class="credits"> <p class="dwt_author">Nunn, Jeffrey</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">176</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.4218D"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics in the Late Paleozoic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">As the chronicle of <span class="hlt">plate</span> motions through time, paleogeography is fundamental to our understanding of <span class="hlt">plate</span> tectonics and its role in shaping the geology of the present-day. To properly appreciate the history of tectonics—and its influence on the deep Earth and climate—it is imperative to seek an accurate and global model of paleogeography. However, owing to the incessant loss of oceanic lithosphere through subduction, the paleogeographic reconstruction of 'full-<span class="hlt">plates</span>' (including oceanic lithosphere) becomes increasingly challenging with age. Prior to 150 Ma ~60% of the lithosphere is missing and reconstructions are developed without explicit regard for oceanic lithosphere or <span class="hlt">plate</span> tectonic principles; in effect, reflecting the earlier mobilistic paradigm of <span class="hlt">continental</span> drift. Although these '<span class="hlt">continental</span>' reconstructions have been immensely useful, the next-generation of mantle models requires global <span class="hlt">plate</span> kinematic descriptions with full-<span class="hlt">plate</span> reconstructions. Moreover, in disregarding (or only loosely applying) <span class="hlt">plate</span> tectonic rules, <span class="hlt">continental</span> reconstructions fail to take advantage of a wealth of additional information in the form of practical constraints. Following a series of new developments, both in geodynamic theory and analytical tools, it is now feasible to construct full-<span class="hlt">plate</span> models that lend themselves to testing by the wider Earth-science community. Such a model is presented here for the late Paleozoic (410-250 Ma). Although we expect this model to be particularly useful for numerical mantle modeling, we hope that it can also serve as a general framework for understanding late Paleozoic tectonics, one on which future improvements can be built and further tested.</p> <div class="credits"> <p class="dwt_author">Domeier, Mat; Torsvik, Trond</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">177</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/17787173"> <span id="translatedtitle">Structural control of flank volcanism in <span class="hlt">continental</span> rifts.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Many volcanoes emerge from the flank (footwall) of normal faults in <span class="hlt">continental</span> rift zones. Because such locations are commonly topographically high and exhibit minor compressional structures, the association is enigmatic. A simple flexing <span class="hlt">plate</span> model shows that deformation of a flexurally supported upper crust during normal faulting generates a dilational strain field in the footwall at the base of the crust. This strain field allows cracking and tapping of preexisting melt. PMID:17787173</p> <div class="credits"> <p class="dwt_author">Ellis, M; King, G</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">178</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/44474538"> <span id="translatedtitle">Estimation of <span class="hlt">continental</span> precipitation recycling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The total amount of water that precipitates on large <span class="hlt">continental</span> regions is supplied by two mechanisms: (1) advection from the surrounding areas external to the region and (2) evaporation and transpiration from the land surface within the region. The latter supply mechanism is tantamount to the recycling of precipitation over the <span class="hlt">Continental</span> area. The degree to which regional precipitation is</p> <div class="credits"> <p class="dwt_author">Kaye L. Brubaker; Dara Entekhabi; P. S. Eagleson</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">179</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.T53C2739C"> <span id="translatedtitle">Post-rift km-scale uplift of passive <span class="hlt">continental</span> margins can be caused by compressive stresses within <span class="hlt">continental</span> crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Many passive <span class="hlt">continental</span> margins are flanked by a mountain range up to more than 2 km high (Elevated Passive <span class="hlt">Continental</span> Margins; EPCMs), e.g. Norway, east and west Greenland, East Brazil, eastern Australia and other margins elsewhere, that have been uplifted long after <span class="hlt">continental</span> break-up. Explanations for these uplifted margins have been ad hoc, but there has hitherto been no explanation that accounts for their presence at both volcanic and non-volcanic margins and in both polar and tropical climatic environments. A continent breaks up by extension and thinning of the <span class="hlt">continental</span> crust. Thinning varies from small amounts in the proximal rift to perhaps a factor of 5 or more adjacent to oceanic crust. <span class="hlt">Continental</span> crust > ca. 25 km thick contains two weak layers, one between strong upper (quartz-rich) and lower (dioritic) crust and the other between strong lower crust and strong mantle. <span class="hlt">Continental</span> crust < ca. 20 km thick is too thin for there to be weak layers and the strong layers are effectively annealed to one another and to the underlying strong mantle. Rifting of a passive <span class="hlt">continental</span> margin must take place under tension. After rifting ceases, however, the margin can come under compression from forces originating elsewhere on or below its <span class="hlt">plate</span>, e.g. collision between <span class="hlt">continental</span> <span class="hlt">plates</span>. The World Stress Map (www.world-stress-mp.org) shows that, where data exists, all EPCMs are currently under compression. <span class="hlt">Continental</span> crust responds to moderate compression stress in two modes; flow in the weak lower crust and by forming gentle buckle-folds with a wavelength of 200-400 km and an amplitude of ca. 0.5 km. Under moderate compression, material in the crust's weak layers starts to flow towards the rift from under the adjacent continent. The lack of weak layers under the thinned, distal rift basin means, however, that flow cannot continue towards the ocean. Mid- and lower crustal material therefore accumulates under the proximal rift, thickening the crust there and lifting it by isostatic response to the thickening. Material flows into the rift until the crust under it is once more as thick as it was prior to extension, but no thicker. This thickened layer extends gradually further and further below the rift, at speeds of a few km per million years, uplifting it and exposing post-rift sediments. At higher stress, buckling may enhance this uplift, and it may be enhanced even more by the isostatic response to the erosion of deep valleys in the rising mountains. Both the thickening and folding continues until there is a reduction in imposed far-field compressive stress, after which the thickened crust 'freezes' in place.</p> <div class="credits"> <p class="dwt_author">Chalmers, J. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">180</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53308470"> <span id="translatedtitle">The <span class="hlt">Plate</span> Boundary Observatory Component of the EarthScope Facility</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The <span class="hlt">Plate</span> Boundary Observatory (PBO), one of the core components of EarthScope, is a geodetic observatory designed to study the three-dimensional strain field resulting from <span class="hlt">plate</span> boundary deformation in the western US including Alaska. The science goals of PBO require that <span class="hlt">plate</span> boundary deformation be adequately characterized over the wide range of temporal and spatial scales common to active <span class="hlt">continental</span></p> <div class="credits"> <p class="dwt_author">M. Jackson; W. Prescott</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_8");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_11");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">181</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6373986"> <span id="translatedtitle">Geologic evolution of petroliferous basins on <span class="hlt">continental</span> shelf of China</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The coastline of southeastern China is about 18,000 km (11,200 mi) in length, and its aggregate <span class="hlt">continental</span> shelf area within 200-m (660-ft) water depth is well over 1 million km/sup 2/ (390,000 mi/sup 2/). Recent geophysical exploration and petroleum drilling records aid in understanding the geologic evolution of these petroliferous basins. Two types of tectonic basins are present on the <span class="hlt">continental</span> shelf areas: (1) Bohai Gulf, South Yellow Sea, and Beibu Gulf are intraplate polyphase rift-depression basins, and (2) East China Sea, mouth of the Pearl River, and the Yingge Sea are epicontinental rift-depressions basins. Both types are believed to be of extensional origin. The severe convergence of the Indian <span class="hlt">plate</span> with the Eurasia <span class="hlt">plate</span> produced east-northeast-spreading of the South China Sea basin, which resulted in two triple junctions on its northern margins. The Pacific <span class="hlt">plate</span> was subducted by downthrust beneath the Eurasia <span class="hlt">continental</span> crust. The extension mechanism could be the rising of an upper mantle plume to produce two weak north-northeast-trending fracture zones. A series of intraplate and epicontinental riftdepression basins was formed. The depositional models and sea level variations of these basins have been interpreted from drilling records and seismic profiles. They can be explained by the tectonoeustatic changes in sea level and Cenozoic climatic changes in China.</p> <div class="credits"> <p class="dwt_author">Desheng, L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">182</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFM.T23D2449K"> <span id="translatedtitle">Is There Really A North American <span class="hlt">Plate</span>?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Lithospheric <span class="hlt">plates</span> are typically identified from earthquake epicenters and evidence such as GPS movements. But no evidence indicates a <span class="hlt">plate</span> boundary between the North American and South American <span class="hlt">Plates</span>. Some <span class="hlt">plate</span> maps show them separated by a transform boundary, but it is only a fracture zone. Other maps show an "undefined <span class="hlt">plate</span> boundary" or put no boundary between these two <span class="hlt">plates</span> (check Google images). Early <span class="hlt">plate</span> maps showed a single large American <span class="hlt">Plate</span>, quite narrow east of the Caribbean <span class="hlt">Plate</span> (Le Pichon 1968, Morgan 1968). The North and South American <span class="hlt">Plates</span> became established by the leading textbook Earth (Press & Siever 1974). On their map, from a Scientific American article by John Dewey (1972), these new <span class="hlt">plates</span> were separated by an "uncertain <span class="hlt">plate</span> boundary." The reasons for postulating a North American <span class="hlt">Plate</span> were probably more psychological than geological. Each of the other continents of the world had its own <span class="hlt">plate</span>, and North American geologists naturally wanted theirs. Similarly, European geographers used to view Europe as its own continent. A single large <span class="hlt">plate</span> should again be hypothesized. But the term American <span class="hlt">Plate</span> would now be ambiguous ("Which <span class="hlt">plate</span>, North or South?") Perhaps future textbook authors could call it the "Two-American <span class="hlt">Plate</span>." Textbook authors ultimately decide such global-tectonic matters. I became aware of textbook authors' opinions and influence from my research into the history of Alfred Wegener's <span class="hlt">continental</span> drift (see Fixists vs. Mobilists by Krill 2011). Leading textbook author Charles Schuchert realized that <span class="hlt">continental</span> drift would abolish his cherished paleogeographic models of large east-west continents (Eria, Gondwana) and small oceans (Poseiden, Nereis). He and his junior coauthors conspired to keep drift evidence out of their textbooks, from the 1934-editions until the 1969-editions (Physical Geology by Longwell et al. 1969, Historical Geology by Dunbar & Waage 1969). Their textbooks ruled in America. Textbooks elsewhere, such as S.J. Shand (1933), E.B. Bailey (1939), and Arthur Holmes (1944), presented <span class="hlt">continental</span> drift as a working hypothesis that could elegantly solve important geological problems. Americans were preconditioned to dislike <span class="hlt">continental</span> drift theory, ever since James Dwight Dana taught in his Manual of Geology (1863...1895) that North America was the type continent of the world, and that it had stood alone since earliest time. Such beliefs sometimes trump geologic evidence. As noted by Stephen Jay Gould (1999) Sigmund Freud had much insight into the psychology of scientific revolutions: they involve a scientific development that shows humans to have lesser status than previously perceived. In the Copernican revolution (geocentrism vs. heliocentrism) humans no longer inhabited the center of the universe. In the Darwinian revolution (creationism vs. evolutionism) humans were no longer uniquely created. In the Wegenerian revolution (fixism vs. mobilism) North America was no longer uniquely created; it was just other fragment from Pangaea. North American geologists were pleased when Press & Siever gave them their own lithospheric <span class="hlt">plate</span>. Being a global-tectonic killjoy, I would like to take away that small consolation as well. Or at least pose the question: Is there really a North American <span class="hlt">Plate</span>?</p> <div class="credits"> <p class="dwt_author">Krill, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">183</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51597716"> <span id="translatedtitle">Magnetotelluric Data from the Tien Shan and Pamir <span class="hlt">Continental</span> Collision Zones, Central Asia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We present magnetotelluic (MT) data obtained within the framework of the multi-disciplinary Tien Shan - Pamir Geodynamic program (TIPAGE). The dynamics of the Tien Shan and Pamir orogenic belts are dominated by the collision of the Indian and Eurasian <span class="hlt">continental</span> <span class="hlt">plates</span>. With the geophysical components, we intend to image the deepest active intra-<span class="hlt">continental</span> subduction zones on Earth (the N-dipping Hindu</p> <div class="credits"> <p class="dwt_author">R. Oliver; A. Rybin; G. Munoz; V. Batalev; T. Krings; X. Chen</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">184</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55835159"> <span id="translatedtitle">Magnetotelluric Data from the Tien Shan and Pamir <span class="hlt">Continental</span> Collision Zones, Central Asia</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We present magnetotelluric (MT) data obtained within the framework of the multi-disciplinary Tien Shan - Pamir Geodynamic program (TIPAGE). The dynamics of the Tien Shan and Pamir orogenic belts are dominated by the collision of the Indian and Eurasian <span class="hlt">continental</span> <span class="hlt">plates</span>. With the geophysical components, we intend to image the deepest active intra-<span class="hlt">continental</span> subduction zones on Earth (the N-dipping Hindu</p> <div class="credits"> <p class="dwt_author">O. Ritter; P. Sass; A. Rybin; G. Munoz; V. Batalev</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">185</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.T14B..07B"> <span id="translatedtitle">Steady State Growth of <span class="hlt">Continental</span> Crust?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">More than twenty years since the publication of Armstrong's seminal paper, debate still rages about most aspects of the Earth's first billion years. Although orders of magnitude more data have been generated since then, the arguments remain the same. The debate is largely centered on the isotopic systematics of minerals and whole rocks, the major and trace element geochemistry of <span class="hlt">continental</span> crust, and various geodynamic models for differentiation of the planet. Most agree that earth, like all the terrestrial planets, differentiated into a crust, mantle and core very early in its history. After that, models of crustal evolution diverge significantly, including the suggestions that modern style <span class="hlt">plate</span> tectonics did not originate until ca. 2.7 Ga or younger and that plumes have played a major role in the generation of <span class="hlt">continental</span> crust. Many believe that the preserved rock record and the detrital zircon record are consistent with episodic crustal growth, which in turn has led to geodynamic models of episodic mantle convection driving major crust forming events. High-precision and high-throughput geochronology have led to claims of episodicity even more pronounced than that presented in Gastil's 1960 paper. We believe that Earth history has been dominated by <span class="hlt">plate</span> tectonics and that <span class="hlt">continental</span> crust is formed largely by amalgamation of island arcs, seamounts, micro continents, and oceanic plateaus. While there are geochemical differences in the average composition of Archean igneous rocks when compared to younger rocks, the processes responsible for their formation may not have changed a great deal. In this view, the so-called crustal growth curves originated by Hurley are in fact crude approximations of crustal preservation. The most highly cited rationales for the view that little silicic crust formed during Earth's first billion years are the lack of known exposed crust older than 3.5 Ga and the paucity of detrital zircons older than 4.0 Ga in sedimentary rocks of any age. If one accepts that the probability of preserving old crust decreases with increasing age, the few exposures of rocks older than 3.5 Ga should not be surprising. The thickness and compositional differences between Archean and younger lithospheric mantle are not fully understood nor is the role of thicker buoyant mantle in preserving <span class="hlt">continental</span> crust; these lead to the question of whether the preserved rock record is representative of what formed. It is notable that the oldest known rocks, the ca. 4.0 Ga Acasta Gneisses, are tonalities-granodiorites-granites with evidence for the involvement of even older crust and that the oldest detrital zircons from Australia (ca. 4.0-4.4 Ga) are thought to have been derived from granitoid sources. The global Hf and Nd isotope databases are compatible with both depleted and enriched sources being present from at least 4.0 Ga to the present and that the lack of evolution of the MORB source or depleted mantle is due to recycling of <span class="hlt">continental</span> crust throughout earth history. Using examples from the Slave Province and southern Africa, we argue that Armstrong's concept of steady state crustal growth and recycling via <span class="hlt">plate</span> tectonics still best explains the modern geological and geochemical data.</p> <div class="credits"> <p class="dwt_author">Bowring, S. A.; Bauer, A.; Dudas, F. O.; Schoene, B.; McLean, N. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">186</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2121042"> <span id="translatedtitle">Plus-end motors <span class="hlt">override</span> minus-end motors during transport of squid axon vesicles on microtubules</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Plus- and minus-end vesicle populations from squid axoplasm were isolated from each other by selective extraction of the minus-end vesicle motor followed by 5'-adenylyl imidodiphosphate (AMP-PNP)- induced microtubule affinity purification of the plus-end vesicles. In the presence of cytosol containing both plus- and minus-end motors, the isolated populations moved strictly in opposite directions along microtubules in vitro. Remarkably, when treated with trypsin before incubation with cytosol, purified plus-end vesicles moved exclusively to microtubule minus ends instead of moving in the normal plus-end direction. This reversal in the direction of movement of trypsinized plus-end vesicles, in light of further observation that cytosol promotes primarily minus-end movement of liposomes, suggests that the machinery for cytoplasmic dynein-driven, minus-end vesicle movement can establish a functional interaction with the lipid bilayers of both vesicle populations. The additional finding that kinesin <span class="hlt">overrides</span> cytoplasmic dynein when both are bound to bead surfaces indicates that the direction of vesicle movement could be regulated simply by the presence or absence of a tightly bound, plus-end kinesin motor; being processive and tightly bound, the kinesin motor would <span class="hlt">override</span> the activity of cytoplasmic dynein because the latter is weakly bound to vesicles and less processive. In support of this model, it was found that (a) only plus-end vesicles copurified with tightly bound kinesin motors; and (b) both plus- and minus-end vesicles bound cytoplasmic dynein from cytosol.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1996-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">187</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.k12science.org/curriculum/musicalplates3/en/index.shtml"> <span id="translatedtitle">Musical <span class="hlt">Plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This on-line project is part of the Center for Improved Engineering and Science Education (CIESE) program. As they complete this series of lessons, students will use real-time data to solve a problem, study the correlation between earthquakes and tectonic <span class="hlt">plates</span>, and determine whether or not there is a relationship between volcanoes and <span class="hlt">plate</span> boundaries. Musical <span class="hlt">Plates</span> has four Core Activities that will teach students how to access and interpret real-time earthquake and volcano data and to how use the information to solve a real-world problem. Each of the core activities is designed to be used in a 45-minute class period. This unit also has three enrichment lessons and a final project lesson that can also be used for assessment.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2007-12-12</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">188</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5571408"> <span id="translatedtitle">Palaeomagnetism and the <span class="hlt">continental</span> crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This book is an introduction to palaeomagnetism offering treatment of theory and practice. It analyzes the palaeomagnetic record over the whole of geological time, from the Archaean to the Cenozoic, and goes on to examine the impact of past geometries and movements of the <span class="hlt">continental</span> crust at each geological stage. Topics covered include theory of rock and mineral magnetism, field and laboratory methods, growth and consolidation of the <span class="hlt">continental</span> crust in Archaean and Proterozoic times, Palaeozoic palaeomagnetism and the formation of Pangaea, the geomagnetic fields, <span class="hlt">continental</span> movements, configurations and mantle convection.</p> <div class="credits"> <p class="dwt_author">Piper, J.D.A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">189</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006AGUFM.V43F..02S"> <span id="translatedtitle">Estimating the global volume of deeply recycled <span class="hlt">continental</span> crust at <span class="hlt">continental</span> collision zones</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">CRUSTAL RECYCLING AT OCEAN MARGINS: Large volumes of rock and sediment are missing from the submerged forearcs of ocean margin subduction zones--OMSZs. This observation means that (1) oceanic sediment is transported beneath the margin to either crustally underplate the coastal region or reach mantle depths, and that (2) the crust of the forearc is vertically thinned and horizontally truncated and the removed material transported toward the mantle. Transport of rock and sediment debris occurs in the subduction channel that separates the upper and lower <span class="hlt">plates</span>. At OMSZs the solid-volume flux of recycling crustal material is estimated to be globally ~2.5 km3/yr (i.e., 2.5 Armstrong units or AU). The corresponding rate of forearc truncation (migration of the trench axis toward a fix reference on the continent) is a sluggish 2-3 km/Myr (about 1/50th the orthogonal convergence rate). Nonetheless during the past 2.5 Gyr (i.e., since the beginning of the Proterozoic) a volume of <span class="hlt">continental</span> material roughly equal to the existing volume (~7 billion cubic km) has been recycled to the mantle at OMSZs. The amount of crust that has been destroyed is so large that recycling must have been a major factor creating the mapped rock pattern and age-fabric of <span class="hlt">continental</span> crust. RECYCLING AT CONTINENT/ARC COLLISIONS: The rate at which arc magmatism globally adds juvenile crust to OMSZs has been commonly globally estimated at ~1 AU. But new geophysical and dating information from the Aleutian and IBM arcs imply that the addition rate is at least ~5 AU (equivalent to ~125 km3/Myr/km of arc). If the Armstrong posit is correct that since the early Archean a balance has existed between additions and losses of crust, then a recycling sink for an additional 2-3 AU of <span class="hlt">continental</span> material must exist. As the exposure of exhumed masses of high P/T blueschist bodies documents that subcrustal streaming of <span class="hlt">continental</span> material occurs at OMSZs, so does the occurrence of exhumed masses of UHP metamorphic rock imply recycling also takes place at CCSZs. We thus target CCSZs as the setting for long-term crustal losses summing worldwide to 2-3 AU. An example is the ~10,000-km-long and 50-Myr duration of the Alpine- Himalaya CCSZ. Recycling is presumably effected by subduction (tectonic) erosion of the upper <span class="hlt">plate</span>, injection of lower <span class="hlt">plate</span> material into mantle circulation, and crustal delamination at collision-thickened orogenic welts. ALTERNATIVE MODEL: If the Armstrong assumption is incorrect and no long-term balance exist between the addition and losses of <span class="hlt">continental</span> crust, then significant crustal recycling at CCSZs may not occur and the global volume of arc-magmatically generated <span class="hlt">continental</span> crust has been growing with time.</p> <div class="credits"> <p class="dwt_author">Scholl, D. W.; Huene, R. V.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">190</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5132686"> <span id="translatedtitle">Coordination: Southeast <span class="hlt">continental</span> shelf studies</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The objective of this investigation is to obtain model descriptions of the flow modifications in the Southeast Atlantic <span class="hlt">continental</span> shelf due to Gulf Stream fluctuations and topographic effects. 2 refs., 4 figs.</p> <div class="credits"> <p class="dwt_author">Menzel, D.W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-26</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">191</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/14835122"> <span id="translatedtitle">India-Eurasia collision chronology has implications for crustal shortening and driving mechanism of <span class="hlt">plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The motion of the Indian <span class="hlt">plate</span> is determined in an absolute frame of reference and compared with the position of the southern margin of Eurasia deduced from palaeomagnetic data in Tibet. The 2,600 + or - 900 km of <span class="hlt">continental</span> crust shortening observed is shown to have occurred in three different episodes: subduction of <span class="hlt">continental</span> crust, intracontinental thrusting and internal</p> <div class="credits"> <p class="dwt_author">Philippe Patriat; José Achache</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">192</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70010170"> <span id="translatedtitle">Rotational inertia of continents: A proposed link between polar wandering and <span class="hlt">plate</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">A mechanism is proposed whereby displacement between continents and the earth's pole of rotation (polar wandering) gives rise to latitudinal transport of <span class="hlt">continental</span> <span class="hlt">plates</span> (<span class="hlt">continental</span> drift) because of their relatively greater rotational inertia. When extended to short-term polar wobble, the hypothesis predicts an energy change nearly equivalent to the seismic energy rate.</p> <div class="credits"> <p class="dwt_author">Kane, M. F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">193</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3233849"> <span id="translatedtitle">Heat acclimation and exercise training interact when combined in an <span class="hlt">overriding</span> and trade-off manner: physiologic-genomic linkage</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Combined heat acclimation (AC) and exercise training (EX) enhance exercise performance in the heat while meeting thermoregulatory demands. We tested the hypothesis that different stress-specific adaptations evoked by each stressor individually trigger similar cardiac alterations, but when combined, <span class="hlt">overriding</span>/trade-off interactions take place. We used echocardiography, isolated cardiomyocyte imaging and cDNA microarray techniques to assay in situ cardiac performance, excitation-contraction (EC) coupling features, and transcriptional programs associated with cardiac contractility. Rat groups studied were controls (sedentary 24°C); AC (sedentary, 34°C, 1 mo); normothermic EX (treadmill at 24°C, 1 mo); and heat-acclimated, exercise-trained (EXAC; treadmill at 34°C, 1 mo). Prolonged heat exposure decreased heart rate and contractile velocity and increased end ventricular diastolic diameter. Compared with controls, AC/EXAC cardiomyocytes demonstrated lower l-type Ca2+ current (ICaL) amplitude, higher Ca2+ transient (Ca2+T), and a greater Ca2+T-to-ICaL ratio; EX alone enhanced ICaL and Ca2+T, whereas aerobic training in general induced cardiac hypertrophy and action potential elongation in EX/EXAC animals. At the genomic level, the transcriptome profile indicated that the interaction between AC and EX yields an EXAC-specific molecular program. Genes affected by chronic heat were linked with the EC coupling cascade, whereas aerobic training upregulated genes involved with Ca2+ turnover via an adrenergic/metabolic-driven positive inotropic response. In the EXAC cardiac phenotype, the impact of chronic heat <span class="hlt">overrides</span> that of EX on EC coupling components and heart rate, whereas EX regulates cardiac morphometry. We suggest that concerted adjustments induced by AC and EX lead to enhanced metabolic and mechanical performance of the EXAC heart.</p> <div class="credits"> <p class="dwt_author">Kodesh, Einat; Nesher, Nir; Simaan, Assi; Hochner, Benny; Beeri, Ronen; Gilon, Dan; Stern, Michael D.; Gerstenblith, Gary</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">194</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1999Tecto..18..895S"> <span id="translatedtitle">Tectonics of the Jurassic-Early Cretaceous magmatic arc of the north Chilean Coastal Cordillera (22°-26°S): A story of crustal deformation along a convergent <span class="hlt">plate</span> boundary</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The tectonic evolution of a <span class="hlt">continental</span> magmatic arc that was active in the north Chilean Coastal Cordillera in Jurassic-Early Cretaceous times is described in order to show the relationship between arc deformation and <span class="hlt">plate</span> convergence. During stage I (circa 195-155 Ma) a variety of structures formed at deep to shallow crustal levels, indicating sinistral arc-parallel strike-slip movements. From deep crustal levels a sequence of structures is described, starting with the formation of a broad belt of plutonic rocks which were sheared under granulite to amphibolite facies conditions (Bolfin Complex). The high-grade deformation was followed by the formation of two sets of conjugate greenschist facies shear zones showing strike-slip and thrust kinematics with a NW-SE directed maximum horizontal shortening, i.e., parallel to the probable Late Jurassic vector of <span class="hlt">plate</span> convergence. A kinematic pattern compatible to this <span class="hlt">plate</span> convergence is displayed by nonmetamorphic folds, thrusts, and high-angle normal faults which formed during the same time interval as the discrete shear zones. During stage II (160-150 Ma), strong arc-normal extension is revealed by brittle low-angle normal faults at shallow levels and some ductile normal faults and the intrusion of extended plutons at deeper levels. During stage III (155-147 Ma), two reversals in the stress regime took place indicated by two generations of dikes, an older one trending NE-SW and a younger one trending NW-SE. Sinistral strike-slip movements also prevailed during stage IV (until ˜125 Ma) when the Atacama Fault Zone originated as a sinistral trench-linked strike-slip fault. The tectonic evolution of the magmatic arc is interpreted in terms of coupling and decoupling between the downgoing and <span class="hlt">overriding</span> <span class="hlt">plates</span>. The structures of stages I and IV suggest that stress transmission due to seismic coupling between the <span class="hlt">plates</span> was probably responsible for these deformations. However, decoupling of the <span class="hlt">plates</span> occurred possibly due to a decrease in convergence rate resulting in extension and the reversals of stages II and III.</p> <div class="credits"> <p class="dwt_author">Scheuber, Ekkehard; Gonzalez, Gabriel</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">195</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/53936997"> <span id="translatedtitle">Recently active reverse faulting in the Atacama Basin area, northern Chile: Implications for the distribution of convergence across the western South America <span class="hlt">plate</span> boundary</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The western South American margin is one of the most active <span class="hlt">continental</span> <span class="hlt">plate</span> boundaries in the world. The ongoing convergence between the Nazca <span class="hlt">plate</span>, or formerly the Farallon <span class="hlt">plate</span>, and the South American <span class="hlt">plate</span> produced the wide deformation belt of the Andes. In order to obtain more information about the active deformations in the central Andean belt to better understand</p> <div class="credits"> <p class="dwt_author">J. H. Shyu; G. Gonzalez; M. Simons; F. Aron; A. Veloso</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">196</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1981GMS....24..259G"> <span id="translatedtitle">Tectonics of China: <span class="hlt">Continental</span> scale cataclastic flow</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Stratigraphic, structural, and earthquake evidence indicates that cataclastic flow, that is, flow by brittle mechanisms (e.g., fracture and slip), was dominant in China from late Paleozoic. This process has operated over a range of scales including the <span class="hlt">continental</span> scale. China is made up of large brittle basement elements immersed in ductile zones which are analogous to porphyroclasts (large, often brittle fragments) surrounded by fluxion (foliation or flow) structures in cataclastic rocks, respectively. This basement fabric for China is seen on Landsat imagery and on tectonic maps and is comparable to cataclastic rock fabrics seen in fault zones, on outcrops, and in thin sections. Brittle basement elements are broken into two or more large rigid blocks, and the dimensions of elements and blocks are within 1 order of magnitude of each other. Ductile zones are made up of fragments which are many orders of magnitude smaller than the ductile zones. Rigid blocks and fragments are identified, and their dimensions are measured through earthquake, fault, and fracture patterns. Rigid basement blocks are surrounded by earthquakes. The sedimentary rocks over the basement faults at the block boundaries seem to be affected by fault movements because they are characterized by facies changes, thickness changes, high-angle faults, and forced folds. Ductile basement zones are earthquake prone, and deformation of the ductile basement affects the overlying sedimentary rocks, as is demonstrated by unconformities and by a wide variety of structures. Thrust faults, buckle folds, and strike slip faults are common in and adjacent to western ductile zones. Structures are most intensely developed where ductile zones abut brittle elements. Both brittle elements and ductile zones are rifted and cut by strike slip faults in eastern China. The mechanical fabric of China and the boundary conditions acting on China are now and always have been determined by its <span class="hlt">plate</span> tectonic history. This inference is made from recently published <span class="hlt">plate</span> tectonic interpretations. Geologic maps show that there are six elements and that each element has a Precambrian, crystalline core which is surrounded by upper Paleozoic <span class="hlt">continental</span> margin suites of rocks, including subduction complexes, among others. Geologic data on ophiolites demonstrate that the brittle elements and their margins were juxtaposed and then welded together along suture zones during Permian and Triassic time to make China. Cenofcoic <span class="hlt">plate</span> motions affecting China resulted in the collision with India where it converges with southwest China and the extension in eastern China where island arcs move away from the mainland and where grabens are actively forming. The juxtaposition to Siberia, which acts as a buttress against northern China, explains the compression of western China, and the absence of a buttress in the Pacific Ocean explains why eastern China can extend. Furthermore, laboratory data on the mechanical behavior of rock under conditions analogous to the shallow crustal conditions of interest in China show that all rocks are weaker in extension than they are in compression. Basement rock in western China is strong because it is compressed, but this same basement rock is weak in eastern China because it is in extension. The tectonics of China or, in mechanistic terms, the way in which the mechanical framework of China responds to Cenozoic boundary forces was a result of China's previous <span class="hlt">plate</span> tectonic history. Crystalline cores are the rigid blocks that form brittle elements. Both the <span class="hlt">continental</span> margin suites and the sutures are the ductile zones. The sutures and sediment patterns seen in the basins and ranges of China can be explained in terms of this tectonic scenario.</p> <div class="credits"> <p class="dwt_author">Gallagher, John J., Jr.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">197</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70010081"> <span id="translatedtitle">Pleistocene tectonic accretion of the <span class="hlt">continental</span> slope off Washington</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Interpretation of reflection profiles across the Washington <span class="hlt">continental</span> margin suggests deformation of Cascadia basin strata against the <span class="hlt">continental</span> slope. Individual reflecting horizons can be traced across the slope-basin boundary. The sense of offset along faults on the <span class="hlt">continental</span> slope is predominantly, but not entirely, west side up. Two faults of small displacement are seen to be west-dipping reverse faults. Magnetic anomalies on the Juan de Fuca <span class="hlt">plate</span> can be traced 40-100 km eastward under the slope, and structural interpretation combined with calculated rates of subduction suggests that approximately 50 km of the outer <span class="hlt">continental</span> slope may have been formed in Pleistocene time. Rocks of Pleistocene age dredge from a ridge exposing acoustic "basement" on the slope, plus the results of deep-sea drilling off northern Oregon, are consistent with this interpretation. The question of whether or not subduction is occurring at present is unresolved because significant strain has not affected the upper 200 m of section in the Cascadia basin. However, deformation of the outer part of the slope has been episodic and may reflect episodic yield, deposition rate, subduction rate, or some combination of these factors. ?? 1972.</p> <div class="credits"> <p class="dwt_author">Silver, E. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">198</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70012610"> <span id="translatedtitle">Circum-arctic <span class="hlt">plate</span> accretion - Isolating part of a pacific <span class="hlt">plate</span> to form the nucleus of the Arctic Basin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">A mosaic of large lithospheric <span class="hlt">plates</span> rims the Arctic Ocean Basin, and foldbelts between these <span class="hlt">plates</span> contain numerous allochthonous microplates. A new model for <span class="hlt">continental</span> drift and microplate accretion proposes that prior to the late Mesozoic the Kula <span class="hlt">plate</span> extended from the Pacific into the Arctic. By a process of circumpolar drift and microplate accretion, fragments of the Pacific basin, including parts of the Kula <span class="hlt">plate</span>, were cut off and isolated in the Arctic Ocean, the Yukon-Koyukuk basin in Alaska, and the Bering Sea. ?? 1980.</p> <div class="credits"> <p class="dwt_author">Churkin, Jr. , M.; Trexler, Jr. , J. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">199</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://wimedialab.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.boundaries/tectonic-plates-and-plate-boundaries/"> <span id="translatedtitle">Tectonic <span class="hlt">Plates</span> and <span class="hlt">Plate</span> Boundaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">Continents were once thought to be static, locked tight in their positions in Earth's crust. Similarities between distant coastlines, such as those on opposite sides of the Atlantic, were thought to be the work of a scientist's overactive imagination, or, if real, the result of erosion on a massive scale. This interactive feature shows 11 tectonic <span class="hlt">plates</span> and their names, the continents that occupy them, and the types of boundaries between them.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-05-09</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">200</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002EGSGA..27.3905B"> <span id="translatedtitle">New Insight Into The Crustal Structure of The <span class="hlt">Continental</span> Margin Off NW Sabah/borneo</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">continental</span> margin offshore NW Sabah/Borneo (Malaysia) has been investigated with reflection and refraction seismics, magnetics, and gravity during the recent cruise BGR01-POPSCOMS. A total of 4000 km of geophysical profiles has been acquired, thereof 2900 km with reflection seismics. Like in major parts of the South China Sea, the area seaward of the Sabah Trough consists of extended <span class="hlt">continental</span> lithosphere. We found evidence that the <span class="hlt">continental</span> crust also underlies the <span class="hlt">continental</span> slope land- ward of the Trough, a fact that raises many questions about the tectonic history and development of this margin. The characteristic pattern of rotated fault blocks and half grabens and the carbon- ates which are observed all over the Dangerous Grounds can be traced a long way landward of the Sabah Trough beneath the sedimentary succession of the upper <span class="hlt">plate</span>. The magnetic anomalies which are dominated by the magnetic signatures of relatively young volcanic features also continue under the <span class="hlt">continental</span> slope. The sedimentary rocks of the upper <span class="hlt">plate</span>, in contrast, seem to generate hardly any magnetic anoma- lies. We suspect that the volcanic activity coincided with the collision of Borneo and the Dangerous Grounds in middle or late Miocene time. The emplacement of an al- lochtonous terrane on top of the extended <span class="hlt">continental</span> lithosphere could be explained by overthrusting as a result of the collision or it could be related to gravity sliding following a broad uplift of NW Borneo at the same time.</p> <div class="credits"> <p class="dwt_author">Barckhausen, U.; Franke, D.; Behain, D.; Meyer, H.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_9");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" 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showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_12");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">201</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1994E%26PSL.123..269A"> <span id="translatedtitle">The sublithospheric mantle as the source of <span class="hlt">continental</span> flood basalts; the case against the <span class="hlt">continental</span> lithosphere and plume head reservoirs</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Continental</span> flood basalt (CFB) provinces have been attributed to a variety of sources. Among these are: (1) ancient <span class="hlt">continental</span> lithosphere (CL); (2) newly arrived plume heads from the core-mantle boundary; (3) steady-state plumes coincident with CL rifts; (4) fossil plume heads; and (5) contamination of deep upwellings (passive or active) by enriched sublithospheric shallow mantle. The criticism that CL is too cold to provide extensive magmatism has been countered by the proposal that the CL is wet, thereby lowering the melting point. This also lowers the viscosity and increases the local Rayleigh number. The calculated seismic velocities and viscosities in this proposed CL source show that it has a low velocity and is weak and has asthenosphere-like physical properties. It is apparent that what has been called '<span class="hlt">continental</span> lithosphere' is actually asthenosphere or the lower part of the thermal boundary layer (TBL) and is unlikely to be a long-lived part of the <span class="hlt">plate</span>. However, a low density and low viscosity region of the sublithospheric mantle (the perisphere) is a suitable reservoir for the enriched component of CFB. It helps to isolate the deeper depleted reservoir from contamination due to recycling at subduction zones. Lithospheric pull-apart at cratonic boundaries, rather than stretching of uniform lithosphere, is suggested as the trigger for extensive <span class="hlt">continental</span> magmatism.</p> <div class="credits"> <p class="dwt_author">Anderson, Don L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">202</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22469781"> <span id="translatedtitle">Using combination therapy to <span class="hlt">override</span> stromal-mediated chemoresistance in mutant FLT3-positive AML: synergism between FLT3 inhibitors, dasatinib/multi-targeted inhibitors and JAK inhibitors.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Acute myeloid leukemia (AML) progenitors are frequently characterized by activating mutations in the receptor tyrosine kinase Fms-like tyrosine kinase-3 (FLT3). Protein tyrosine kinases are integral components of signaling cascades that have a role in both FLT3-mediated transformation as well as viability pathways that are advantageous to leukemic cell survival. The bone marrow microenvironment can diminish AML sensitivity to tyrosine kinase inhibitors. We hypothesized that inhibition of protein kinases in addition to FLT3 may be effective in <span class="hlt">overriding</span> drug resistance in AML. We used a cell-based model mimicking stromal protection as part of an unbiased high-throughput chemical screen to identify kinase inhibitors with the potential to <span class="hlt">override</span> microenvironment-mediated drug resistance in mutant FLT3-positive AML. Several related multi-targeted kinase inhibitors, including dasatinib, with the capability of reversing microenvironment-induced resistance to FLT3 inhibition were identified and validated. We validated synergy in vitro and demonstrated effective combination potential in vivo. In particular Janus kinase inhibitors were effective in <span class="hlt">overriding</span> stromal protection and potentiating FLT3 inhibition in primary AML and cell lines. These results hint at a novel concept of using combination therapy to <span class="hlt">override</span> drug resistance in mutant FLT3-positive AML in the bone marrow niche and suppress or eradicate residual disease. PMID:22469781</p> <div class="credits"> <p class="dwt_author">Weisberg, E; Liu, Q; Nelson, Erik; Kung, A L; Christie, A L; Bronson, R; Sattler, M; Sanda, T; Zhao, Z; Hur, W; Mitsiades, C; Smith, R; Daley, J F; Stone, R; Galinsky, I; Griffin, J D; Gray, N</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">203</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4054699"> <span id="translatedtitle">Using combination therapy to <span class="hlt">override</span> stromal-mediated chemoresistance in mutant FLT3-positive AML: Synergism between FLT3 inhibitors, dasatinib/multi-targeted inhibitors, and JAK inhibitors</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Acute myeloid leukemia (AML) progenitors are frequently characterized by activating mutations in the receptor tyrosine kinase FLT3. Protein tyrosine kinases are integral components of signaling cascades that play a role in both FLT3-mediated transformation as well as viability pathways that are advantageous to leukemic cell survival. The bone marrow microenvironment can diminish AML sensitivity to tyrosine kinase inhibitors (TKIs). We hypothesized that inhibition of protein kinases in addition to FLT3 may be effective in <span class="hlt">overriding</span> drug resistance in AML. We used a cell-based model mimicking stromal protection as part of an unbiased high-throughput chemical screen to identify kinase inhibitors with the potential to <span class="hlt">override</span> microenvironment-mediated drug resistance in mutant FLT3-positive AML. Several related multi-targeted kinase inhibitors, including dasatinib, with the capability of reversing microenvironment-induced resistance to FLT3 inhibition were identified and validated. We validated synergy in vitro and demonstrated effective combination potential in vivo. In particular Janus kinase (JAK) inhibitors were effective in <span class="hlt">overriding</span> stromal protection and potentiating FLT3 inhibition in primary AML and cell lines. These results hint at a novel concept of using combination therapy to <span class="hlt">override</span> drug resistance in mutant FLT3-positive AML in the bone marrow niche and suppress or eradicate residual disease.</p> <div class="credits"> <p class="dwt_author">Weisberg, Ellen; Liu, Qingsong; Nelson, Erik; Kung, Andrew L.; Christie, Amanda L.; Bronson, Rod; Sattler, Martin; Sanda, Takaomi; Zhao, Zheng; Hur, Wooyoung; Mitsiades, Constantine; Smith, Robert; Daley, John F.; Stone, Richard; Galinsky, Ilene; Griffin, James D.; Gray, Nathanael</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">204</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70016562"> <span id="translatedtitle">Composite transform-convergent <span class="hlt">plate</span> boundaries: description and discussion</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">The leading edge of the <span class="hlt">overriding</span> <span class="hlt">plate</span> at an obliquely convergent boundary is commonly sliced by a system of strike-slip faults. This fault system is often structurally complex, and may show correspondingly uneven strain effects, with great vertical and translational shifts of the component blocks of the fault system. The stress pattern and strain effects vary along the length of the system and change through time. These margins are considered to be composite transform-convergent (CTC) <span class="hlt">plate</span> boundaries. Examples are given of structures formed along three CTC boundaries: the Aleutian Ridge, the Solomon Islands, and the Philippines. The dynamism of the fault system along a CTC boundary can enhance vertical tectonism and basin formation. This concept provides a framework for the evaluation of petroleum resources related to basin formation, and mineral exploration related to igneous activity associated with transtensional processes. ?? 1992.</p> <div class="credits"> <p class="dwt_author">Ryan, H. F.; Coleman, P. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">205</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003EAEJA.....5857H"> <span id="translatedtitle">Gravity and magnetic investigations along the Peruvian <span class="hlt">continental</span> margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This work presents the first three-dimensional gravity and magnetic investigation along the convergent Peruvian margin. Three-dimensional magnetic modelling is still a relatively untried and challenging technique. The gravity and magnetic models image nearly the whole margin which has been only partly resolved with geophysical methods up to now. The gravity and magnetic models are constructed for three areas between 7.25°S and 16.75°S and are based on the available wide-angle seismic velocity models (Hampel et al., 2002a; Broser et al., 2002). The <span class="hlt">continental</span> margin is characterised by positive free-air anomalies of varying amplitudes, indicating that the margin has been shaped by the subduction of different features on the Nazca <span class="hlt">Plate</span>. A comparison of the shipboard gravity measurements with the satellite data ensures that the data compiled from different marine surveys are compatible. In the Yaquina Area (7.25°S to 11°S) gravity anomalies caused by the Trujillo Trough and the Mendaña Fracture Zone are successfully modelled with remarkable undulations in the layer geometry of the oceanic crust. Along the <span class="hlt">continental</span> margin, especially in the Lima Area (10.50°S to 14.40°S), strong undulations of the lower <span class="hlt">continental</span> crust influence the upper sedimentary layers and support the development of basins along the Peruvian margin. The theory stating that the Peruvian margin is uplifted by the subducting Nazca Ridge (Kulm et al., 1988; Hagen &Moberly, 1994) is supported by gravity modelling. Consequently the buoyant Nazca Ridge is, at least partly, responsible for the extended region of flat subduction. The thickened and slightly asymmetrical crust of the Nazca Ridge is envisaged in gravity modelling. In the Nazca Ridge Area (14.25°S to 16.75°S) no accretionary prism is modelled. We conclude that the ridge is eroding the <span class="hlt">continental</span> margin; furthermore the subduction of eroded sediments is probable. Gravity modelling suggests that the Nazca Ridge has fractured the <span class="hlt">continental</span> margin. North of the ridge, in the Lima Area, a rather uniform accretionary complex is observed. This indicates that, after the margin was eroded by the southwards moving Nazca Ridge, the prism rapidly reached its stable size. In the Yaquina Area an accretionary prism is modelled in the whole research area but local variations of its location and structure indicate the former erosive influence on the <span class="hlt">continental</span> margin of subducting features on the Nazca <span class="hlt">Plate</span>. The layers of the oceanic crust show increasing densities implying they possess an originally high degree of porosity before actually subducting. The lineations 13 to 18 are traced from the southern part of the studied region as far north as the Mendaña Fracture Zone. Their orientation indicates that the Nazca <span class="hlt">Plate</span> has not significantly changed its convergence direction between 12°S and 17.5°S in the past 33 Ma. In the Nazca Ridge Area a different anomaly pattern compared to the surrounding areas is observed. We conclude that the ridge is younger than the respective Nazca <span class="hlt">Plate</span> and that it was formed on the already existing Nazca <span class="hlt">Plate</span> and obliterated the original magnetic anomalies. In all models the basaltic layer sheeted dykes is considerably weaker magnetised than the upper pillow lavas and the lower gabbros. Generally the rocks of the <span class="hlt">continental</span> margin possess a weak magnetisation. The Königsberg ratio is small for all layers of the oceanic crust, i.e. the induced magnetisation is partly higher than the remanent magnetisation. When it has subducted to a minimum depth of 25 km the magnetised oceanic crust exerts almost no influence on the observed total intensity field.</p> <div class="credits"> <p class="dwt_author">Heinbockel, R.; Dehghani, G. A.; Huebscher, Ch.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">206</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004AGUFM.T44A..01S"> <span id="translatedtitle">Crustal Recylcing at Ocean Margin and <span class="hlt">Continental</span> Subduction Zones and the Net Accumulation of <span class="hlt">Continental</span> Crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">CRUSTAL RECYCLING PROCESSES AND VOLUMES: At convergent ocean margins large volumes of rock and sediment are missing from the global length of submerged forearcs. Material is removed by the kindred tectonic process of sediment subduction and subduction erosion, both of which insert sediment and eroded crustal debris into the subduction channel separating the upper and lower <span class="hlt">plates</span>. The channel transports entrained debris toward the mantle where it is ultimately recycled. Large tracks of exposed high P/T rocks are exposed remnants of subduction channels. Over the past 100-200 my, the average solid-rock volume of recycled crust is estimated to have averaged globally 2.5-3.0 km3/yr--or 2.5 to 3 Armstrong Units (AU). Exposed tracts of UHP rocks at collisional orogens document that crustal material is subducted deep into the mantle at <span class="hlt">continental</span> subduction zones. Based on missing terranes of extended lower <span class="hlt">plate</span>, a volume of recycled <span class="hlt">continental</span> crust detached by slab failure can be estimated at ~5000 km3 for each km of the early Proterozoic Wopmay orogen of the NW Canadian Shield (Hildrenbrand and Bowring, 1999, Geology, v. 27, p.11-14). Averaged over an orogenic episode of ~40 my, the corresponding rate is ~125 km3/my/km of margin. Using the Wopmay- rate as a guide, and assuming that similar to the Cenozoic, collisional orogenic margins averaged 10-12,000 km in global length, then since the early Proterozoic crustal recycling at collisional subduction zones has averaged close to 1.5 AU (i.e., 1.5 km3/yr). Crustal losses from the upper <span class="hlt">plate</span> have also been recognized for sectors of the Variscan orogen (Oncken, 1998, Geology, v. 26, p. 1975-1078). The missing crust is roughly 40 km3/my for each km of upper <span class="hlt">plate</span>, thus globally tallying an additional ~0.5 AU. CRUSTAL GROWTH: New information implies that at intra-oceanic subduction zones the long-term (~50 my), global rate of arc magmatic productivity has averaged close to 5 AU, a much higher rate than formerly estimated (~1 AU). It is not clear that this rate, which is based on the growth of the Aleutian and Izu-Bonin-Mariana arc massifs corrected for subduction erosion losses, can be applied to <span class="hlt">continental</span> or Andean arcs. But allowing that it can, then the combined global rate of additions of juvenile igneous rock to build continents ( 5 AU) is similar to that recycled at ocean margin (2-3 AU) and <span class="hlt">continental</span> subduction zones (2 AU). Additional losses can arise from delamination of magmatically or tectonically thickened convergent-margin crust. The implication of these estimates and linked assumptions support the Armstrong posit that since the early Archean the yang of magmatic additions to the continents has been matched by the yin of recycling losses.</p> <div class="credits"> <p class="dwt_author">Scholl, D. W.; von Huene, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">207</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007AGUFM.T44A..01S"> <span id="translatedtitle">Crustal Recylcing at Ocean Margin and <span class="hlt">Continental</span> Subduction Zones and the Net Accumulation of <span class="hlt">Continental</span> Crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">CRUSTAL RECYCLING PROCESSES AND VOLUMES: At convergent ocean margins large volumes of rock and sediment are missing from the global length of submerged forearcs. Material is removed by the kindred tectonic process of sediment subduction and subduction erosion, both of which insert sediment and eroded crustal debris into the subduction channel separating the upper and lower <span class="hlt">plates</span>. The channel transports entrained debris toward the mantle where it is ultimately recycled. Large tracks of exposed high P/T rocks are exposed remnants of subduction channels. Over the past 100-200 my, the average solid-rock volume of recycled crust is estimated to have averaged globally 2.5-3.0 km3/yr--or 2.5 to 3 Armstrong Units (AU). Exposed tracts of UHP rocks at collisional orogens document that crustal material is subducted deep into the mantle at <span class="hlt">continental</span> subduction zones. Based on missing terranes of extended lower <span class="hlt">plate</span>, a volume of recycled <span class="hlt">continental</span> crust detached by slab failure can be estimated at ~5000 km3 for each km of the early Proterozoic Wopmay orogen of the NW Canadian Shield (Hildrenbrand and Bowring, 1999, Geology, v. 27, p.11-14). Averaged over an orogenic episode of ~40 my, the corresponding rate is ~125 km3/my/km of margin. Using the Wopmay- rate as a guide, and assuming that similar to the Cenozoic, collisional orogenic margins averaged 10-12,000 km in global length, then since the early Proterozoic crustal recycling at collisional subduction zones has averaged close to 1.5 AU (i.e., 1.5 km3/yr). Crustal losses from the upper <span class="hlt">plate</span> have also been recognized for sectors of the Variscan orogen (Oncken, 1998, Geology, v. 26, p. 1975-1078). The missing crust is roughly 40 km3/my for each km of upper <span class="hlt">plate</span>, thus globally tallying an additional ~0.5 AU. CRUSTAL GROWTH: New information implies that at intra-oceanic subduction zones the long-term (~50 my), global rate of arc magmatic productivity has averaged close to 5 AU, a much higher rate than formerly estimated (~1 AU). It is not clear that this rate, which is based on the growth of the Aleutian and Izu-Bonin-Mariana arc massifs corrected for subduction erosion losses, can be applied to <span class="hlt">continental</span> or Andean arcs. But allowing that it can, then the combined global rate of additions of juvenile igneous rock to build continents ( 5 AU) is similar to that recycled at ocean margin (2-3 AU) and <span class="hlt">continental</span> subduction zones (2 AU). Additional losses can arise from delamination of magmatically or tectonically thickened convergent-margin crust. The implication of these estimates and linked assumptions support the Armstrong posit that since the early Archean the yang of magmatic additions to the continents has been matched by the yin of recycling losses.</p> <div class="credits"> <p class="dwt_author">Scholl, D. W.; von Huene, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">208</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/3906061"> <span id="translatedtitle">The heat flow through oceanic and <span class="hlt">continental</span> crust and the heat loss of the earth</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Oceans and continents are now considered to be mobile and interconnected. The paper discusses heat flow through the ocean floor, <span class="hlt">continental</span> heat flow, heat loss of the earth, thermal structure and thickness of the lithosphere, as well as convection in the mantle and the thermal structure of the lithosphere, within the framework of the theory of <span class="hlt">plate</span> tectonics. It is</p> <div class="credits"> <p class="dwt_author">J. G. Sclater; C. Jaupart; D. Galson</p> <p class="dwt_publisher"></p> <p class="publishDate">1980-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">209</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6469769"> <span id="translatedtitle"><span class="hlt">Continental</span> crust: a geophysical approach</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This book develops an integrated and balanced picture of present knowledge of the <span class="hlt">continental</span> crust. Crust and lithosphere are first defined, and the formation of crusts as a general planetary phenomenon is described. The background and methods of geophysical studies of the earth's crust and the collection of related geophysical parameters are examined. Creep and friction experiments and the various methods of radiometric age dating are addressed, and geophysical and geological investigations of the crustal structure in various age provinces of the continents are studied. Specific tectonic structures such as rifts, <span class="hlt">continental</span> margins, and geothermal areas are discussed. Finally, an attempt is made to give a comprehensive view of the evolution of the <span class="hlt">continental</span> crust and to collect and develop arguments for crustal accretion and recycling. 647 references.</p> <div class="credits"> <p class="dwt_author">Meissner, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">210</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23991863"> <span id="translatedtitle">Weighing the deep <span class="hlt">continental</span> biosphere.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">There is abundant evidence for widespread microbial activity in deep <span class="hlt">continental</span> fractures and aquifers, with important implications for biogeochemical cycling on Earth and the habitability of other planetary bodies. Whitman et al. (P Natl Acad Sci USA, 95, 1998, 6578) estimated a <span class="hlt">continental</span> subsurface biomass on the order of 10(16) -10(17) g C. We reassess this value in the light of more recent data including over 100 microbial population density measurements from groundwater around the world. Making conservative assumptions about cell carbon content and the ratio of attached and free-living microorganisms, we find that the evidence continues to support a deep <span class="hlt">continental</span> biomass estimate of 10(16) -10(17) g C, or 2-19% of Earth's total biomass. PMID:23991863</p> <div class="credits"> <p class="dwt_author">McMahon, Sean; Parnell, John</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">211</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16..600M"> <span id="translatedtitle">Geometrical constraints of rift fissures on the formation of isolated micro <span class="hlt">continental</span> blocks during transition from <span class="hlt">continental</span> rifting to oceanic spreading based on analogue modelling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">From global ocean bathymetric data, we can observe many intraplate features such us submerged and non-submerged plateaus below sea level, islands, ridges, banks etc. All these features can be divided in three main groups: (1) blocks with oceanic crust; (2) blocks with <span class="hlt">continental</span> crust; (3) complex features. There are many hypotheses that try to describe their origin. Hypotheses, which we carried on: (1) features with <span class="hlt">continental</span> crust formed by ridge jumping into a <span class="hlt">continental</span> margin; (2) features with igneous composition formed by eruption of huge volumes of volcanic rocks; (3) complex features with jigsaw crust composition. We present preliminary results of our experimental modeling that show geometrical constraints for the formation of isolated blocks in oceanic crust due to the evolution of overlapping spreading centers. These can lead to the formation of an isolated <span class="hlt">continental</span> block if all following conditions are met: (1) the angle between extension direction and pre-existing fractures are between 45° to 60° ; (2) the length of two pre-existing fractures located on opposite sides of model <span class="hlt">plate</span> is equal; (3) the offset between two pre-existing fractures located on opposite sides of model <span class="hlt">plate</span> vary from 1.5 cm to 3 cm. Extension rates in the model vary from V = 1.67 *10-5 m/sec to V = 2.15×10-5 m/sec which correlate with slow spreading rates. The model <span class="hlt">plate</span> size was 12×25 cm. These experiments provide us with a probable mechanism of isolated <span class="hlt">continental</span> block formation. In addition, the experiments allow us to distinguish major geometrical parameters of <span class="hlt">continental</span> break up modelling. These results are preliminary and we will study other experimental settings such us influence of hotspot activity, interaction between propagating ridge and weakened zones and zones with more stable properties. For example, we consider the conditions of formation Elan Bank in Kerguelen Plateau structure.</p> <div class="credits"> <p class="dwt_author">Makushkina, Anna; Dubinin, Evgeny; Grokholsky, Andrey</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">212</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5930257"> <span id="translatedtitle"><span class="hlt">Continental</span> rifts and mineral resources</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary"><span class="hlt">Continental</span> rifts are widespread and range in age from the present to 3 b.y. Individual rifts may form parts of complex systems as in E. Africa and the Basin and Range. Rifts have originated in diverse environments such as arc-crests, sites of <span class="hlt">continental</span> collision, collapsing mountain belts and on continents at rest over the mantle circulation pattern. <span class="hlt">Continental</span> rift resources can be classified by depth of origin: For example, in the Great Dike, Norilsk and Mwadui magma from the mantle is the host. At shallower depths <span class="hlt">continental</span> crust partly melted above mafic magma hosts ore (Climax, Henderson). Rift volcanics are linked to local hydrothermal systems and to extensive zeolite deposits (Basin and Range, East Africa). Copper (Zambia, Belt), zinc (Red Dog) and lead ores (Benue) are related to hydrothermal systems which involve hot rock and water flow through both pre-rift basement and sedimentary and volcanic rift fill. Economically significant sediments in rifts include coals (the Gondwana of Inida), marine evaporites (Lou Ann of the Gulf of Mexico) and non-marine evaporites (East Africa). Oil and gas in rifts relate to a variety of source, reservoir and trap relations (North Sea, Libya), but rift-lake sediment sources are important (Sung Liao, Bo Hai, Mina, Cabinda). Some ancient iron ores (Hammersley) may have formed in rift lakes but Algoman ores and greenstone belt mineral deposits in general are linked to oceanic and island arc environments. To the extent that <span class="hlt">continental</span> environments are represented in such areas as the Archean of the Superior and Slave they are Andean Arc environments which today have locally rifted crests (Ecuador, N. Peru). The Pongola, on Kaapvaal craton may, on the other hand represent the world's oldest preserved, little deformed, <span class="hlt">continental</span> rift.</p> <div class="credits"> <p class="dwt_author">Burke, K. (Univ. of Houston, TX (United States). Geosciences Dept.)</p> <p class="dwt_publisher"></p> <p class="publishDate">1992-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">213</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.yale.edu/ynhti/curriculum/units/1991/6/91.06.05.x.html"> <span id="translatedtitle">The Great <span class="hlt">Continental</span> Drift Mystery</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This unit introduces students to the development of the theory of <span class="hlt">continental</span> drift. They will examine the early work of Alfred Wegener and Alexander DuToit, investigate lines of evidence that resulted in the development of the theory, and learn about the final lines of evidence that resulted in the theory's acceptance. There is a set of activities in which the students construct a map of Pangea using Wegener's clues, familiarize themselves with some important geographic locations, and investigate how fossil distribution can be used to enhance the study of <span class="hlt">continental</span> drift. Study questions and a bibliography are included.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">214</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007AGUFM.T51E..04T"> <span id="translatedtitle">Earthquakes and crustal structure beneath the central Cascadia <span class="hlt">continental</span> margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the summer of 2004, two clusters of "repeating" earthquakes occurred beneath the <span class="hlt">continental</span> shelf of the central Cascadia subduction zone near 44.5N, 124.5W where the subduction megathrust is thought to be locked or transitional. The largest event in each cluster reached moment magnitude M=4.8-4.9. Seismicity has continued since with small (M<3) earthquakes occurring in each cluster on August 23-25, 2007. Moment tensor analysis for the main shock in each cluster indicates a 6-15 degree eastward dipping fault plane, consistent with the <span class="hlt">plate</span> boundary dip of ~12 degrees. One cluster is serendipitously occurring on a transect along which crustal structure is well known from active source seismic experiments, and raytracing through this crustal model to match observed relative arrival times of secondary phases indicates a source depth of 16 ± 1 km, within 1 km of the <span class="hlt">plate</span> boundary. This segment of the forearc also displays several characteristics indicative of along-strike and down-dip variations in <span class="hlt">plate</span> coupling including: a subducted ridge on the downgoing <span class="hlt">plate</span>; a "bright spot" on the <span class="hlt">plate</span> boundary at a depth of ~15-20 km; an along-strike change in the gravity field and basement depth; a transition in <span class="hlt">plate</span> coupling indicated by inversion of GPS data; geologic indications of active folding in the upper <span class="hlt">plate</span>; and anomalous deformation in the adjacent oceanic <span class="hlt">plate</span>. On the other hand, no obvious correlation with ETS in this region is observed. In September, 2007, we deployed an array of ocean bottom seismometers to record microseismicity and distinguish among several possible models for the physical properties of the megathrust.</p> <div class="credits"> <p class="dwt_author">Trehu, A. M.; Braunmiller, J.; Nabelek, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">215</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004AGUFM.T51E..04T"> <span id="translatedtitle">Earthquakes and crustal structure beneath the central Cascadia <span class="hlt">continental</span> margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In the summer of 2004, two clusters of "repeating" earthquakes occurred beneath the <span class="hlt">continental</span> shelf of the central Cascadia subduction zone near 44.5N, 124.5W where the subduction megathrust is thought to be locked or transitional. The largest event in each cluster reached moment magnitude M=4.8-4.9. Seismicity has continued since with small (M<3) earthquakes occurring in each cluster on August 23-25, 2007. Moment tensor analysis for the main shock in each cluster indicates a 6-15 degree eastward dipping fault plane, consistent with the <span class="hlt">plate</span> boundary dip of ~12 degrees. One cluster is serendipitously occurring on a transect along which crustal structure is well known from active source seismic experiments, and raytracing through this crustal model to match observed relative arrival times of secondary phases indicates a source depth of 16 ± 1 km, within 1 km of the <span class="hlt">plate</span> boundary. This segment of the forearc also displays several characteristics indicative of along-strike and down-dip variations in <span class="hlt">plate</span> coupling including: a subducted ridge on the downgoing <span class="hlt">plate</span>; a "bright spot" on the <span class="hlt">plate</span> boundary at a depth of ~15-20 km; an along-strike change in the gravity field and basement depth; a transition in <span class="hlt">plate</span> coupling indicated by inversion of GPS data; geologic indications of active folding in the upper <span class="hlt">plate</span>; and anomalous deformation in the adjacent oceanic <span class="hlt">plate</span>. On the other hand, no obvious correlation with ETS in this region is observed. In September, 2007, we deployed an array of ocean bottom seismometers to record microseismicity and distinguish among several possible models for the physical properties of the megathrust.</p> <div class="credits"> <p class="dwt_author">Trehu, A. M.; Braunmiller, J.; Nabelek, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">216</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..1513576L"> <span id="translatedtitle">Inheritance of pre-existing weakness in <span class="hlt">continental</span> breakup: 3D numerical modeling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The whole process of <span class="hlt">continental</span> rifting to seafloor spreading is one of the most important <span class="hlt">plate</span> tectonics on the earth. There are many questions remained related to this process, most of which are poorly understood, such as how <span class="hlt">continental</span> rifting transformed into seafloor spreading? How the curved oceanic ridge developed from a single straight <span class="hlt">continental</span> rift? How the pre-existing weakness in either crust or lithospheric mantle individually influences the <span class="hlt">continental</span> rifting and oceanic spreading? By employing the state-of-the-art three-dimensional thermomechanical-coupled numerical code (using Eulerian-Lagrangian finite-difference method and marker-in-cell technic) (Gerya and Yuen, 2007), which can model long-term <span class="hlt">plate</span> extension and large strains, we studied the whole process of <span class="hlt">continental</span> rifting to seafloor spreading based on the following question: How the pre-existing lithospheric weak zone influences the <span class="hlt">continental</span> breakup? <span class="hlt">Continental</span> rifts do not occur randomly, but like to follow the pre-existing weakness (such as fault zones, suture zones, failed rifts, and other tectonic boundaries) in the lithosphere, for instance, the western branch of East African Rift formed in the relatively weak mobile belts along the curved western border of Tanzanian craton (Corti et al., 2007; Nyblade and Brazier, 2002), the Main Ethiopian Rift developed within the Proterozoic mobile belt which is believed to represent a <span class="hlt">continental</span> collision zone (Keranen and Klemperer, 2008),the Baikal rift formed along the suture between Siberian craton and Sayan-Baikal folded belt (Chemenda et al., 2002). The early stage formed rift can be a template for the future rift development and <span class="hlt">continental</span> breakup (Keranen and Klemperer, 2008). Lithospheric weakness can either reduce the crustal strength or mantle strength, and leads to the crustal or mantle necking (Dunbar and Sawyer, 1988), which plays an important role on controlling the <span class="hlt">continental</span> breakup patterns, such as controlling the breakup order of crust and mantle (Huismans and Beaumont, 2011). However, the inheritance of pre-existing lithospheric weakness in the evolution of <span class="hlt">continental</span> rifts and oceanic ridge is not well studied. We use 3D numerical modeling to study this problem, by changing the weak zone position and geometry, and the rheological structure of the model. In our study, we find that: 1).3D <span class="hlt">continental</span> breakup and seafloor spreading patterns are controlled by (a) crust-mantle rheological coupling and (b) geometry and position of the pre-existing weak zones. 2).Three spreading patterns are obtained: (a) straight ridges, (b) curved ridges and (c) overlapping ridges. 3).When crust and mantle are decoupled, abandoned rift structures often form.</p> <div class="credits"> <p class="dwt_author">Liao, Jie; Gerya, Taras</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">217</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFMED14C..02G"> <span id="translatedtitle">MACMA: a Virtual Lab for <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">MACMA (Multi-Agent Convective MAntle) is a tool developed to simulate evolutive <span class="hlt">plate</span> tectonics and mantle convection in a 2-D cylindrical geometry (Combes et al., 2012). The model relies mainly on a force balance to compute the velocity of each <span class="hlt">plate</span>, and on empirical rules to determine how <span class="hlt">plate</span> boundaries move and evolve. It includes first-order features of <span class="hlt">plate</span> tectonics: (a) all <span class="hlt">plates</span> on Earth do not have the same size, (b) subduction zones are asymmetric, (c) <span class="hlt">plates</span> driven by subducting slabs and upper <span class="hlt">plates</span> do not exhibit the same velocities, and (d) <span class="hlt">plate</span> boundaries are mobile, can collide, merge and disappear, and new <span class="hlt">plate</span> boundaries can be created. The MACMA interface was designed to be user-friendly and a simple use of the simulator can be achieved without any prerequisite knowledge in fluid dynamics, mantle rheology, nor in numerical methods. As a preliminary study, the simulator was used by a few students from bachelor's degree to master's degree levels. An initial configuration for <span class="hlt">plate</span> tectonics has to be created before starting a simulation: the number and types of <span class="hlt">plate</span> boundaries (ridge, subduction, passive margins) has to be defined and seafloor ages must be given. A simple but interesting exercise consists in letting students build such an initial configuration: they must analyze a map of tectonic <span class="hlt">plates</span>, choose a 2-D section and examine carefully a map of seafloor ages. Students mentioned that the exercise made them realize that the 3-D spherical structure of <span class="hlt">plate</span> tectonics does not translate directly in a simple 2-D section, as opposed to what is usually shown in books. Physical parameters: e.g. mantle viscosity, number of layers to consider in the mantle (upper and lower mantle, possible asthenosphere), initial time and mantle temperature, have to be chosen, and students can use this virtual lab to see how different scenarios emerge when parameters are varied. Very importantly, the direct visualization of the mobility of <span class="hlt">plate</span> boundaries is a feature that clearly seems interesting to students. They are used to see dynamic representations of <span class="hlt">continental</span> drift, but this does not include the dynamics of the oceanic lithosphere and the corresponding fluctuations in seafloor age distribution. The 2-D geometry of the simulator is a simplification that actually brings a clearer view of <span class="hlt">plate</span> boundary creations, migrations, and collisions, together with global <span class="hlt">plate</span> tectonics reorganization events.</p> <div class="credits"> <p class="dwt_author">Grigne, C.; Combes, M.; Tisseau, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">218</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6149382"> <span id="translatedtitle"><span class="hlt">Continental</span> crust beneath the Agulhas Plateau, Southwest Indian Ocean</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The Agulhas Plateau lies 500 km off the Cape of Good Hope in the southwestern Indian Ocean. Acoustic basement beneath the northern one third of this large, aseismic structural high has rugged morphology, but basement in the south is anomalously smooth, excepting a 30- to 90-km-wide zone with irregular relief that trends south-southwest through the center of the plateau. Seismic refraction profiles across the southern plateau indicate that the zone of irregular acoustic basement overlies thickened oceanic crust and that <span class="hlt">continental</span> crust, locally thinned and intruded by basalts, underlies several regions of smooth acoustic basement. Recovery of quartzo-feldspathic gneisses in dredge hauls confirms the presence of <span class="hlt">continental</span> crust. The smoothness of acoustic basement probably results from erosion (perhaps initially subaerial) of topographic highs with depositions and cementation of debris in ponds to form high-velocity beds. Basalt flows and sills also may contribute locally to form smooth basement. The rugged basement of the northern plateau appears to be of oceanic origin. A <span class="hlt">plate</span> reconstruction to the time of initial opening of the South Atlantic places the <span class="hlt">continental</span> part of the southern plateau adjacent to the southern edge of the Falkland Plateau, and both abut the western Mozambique Ridge. Both the Agulhas and Falkland plateaus were displaced westward during initial rifting in the Early Cretaceous. Formation of an RRR triple junction at the northern edge of the Agulhas <span class="hlt">continental</span> fragment during middle Cretaceous time may explain the origin of the rugged, thickened oceanic crust beneath plateau as well as the apparent extension of the <span class="hlt">continental</span> crust and intrusion of basaltic magmas beneath the southern plateau.</p> <div class="credits"> <p class="dwt_author">Tucholke, B.E.; Houtz, R.E.; Barrett, D.M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-05-10</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">219</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.visionlearning.com/library/module_viewer.php?mid=66"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics II: <span class="hlt">Plates</span>, <span class="hlt">plate</span> boundaries, and driving forces</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The distribution of earthquakes and volcanoes around the world confirmed the theory of <span class="hlt">plate</span> tectonics first proposed by Wegener. These phenomena also help categorize <span class="hlt">plate</span> boundaries into three different types: convergent, divergent, and transform.</p> <div class="credits"> <p class="dwt_author">Egger, Anne</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-03-18</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">220</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/17051208"> <span id="translatedtitle">Evolution of the <span class="hlt">continental</span> crust.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The <span class="hlt">continental</span> crust covers nearly a third of the Earth's surface. It is buoyant--being less dense than the crust under the surrounding oceans--and is compositionally evolved, dominating the Earth's budget for those elements that preferentially partition into silicate liquid during mantle melting. Models for the differentiation of the <span class="hlt">continental</span> crust can provide insights into how and when it was formed, and can be used to show that the composition of the basaltic protolith to the <span class="hlt">continental</span> crust is similar to that of the average lower crust. From the late Archaean to late Proterozoic eras (some 3-1 billion years ago), much of the <span class="hlt">continental</span> crust appears to have been generated in pulses of relatively rapid growth. Reconciling the sedimentary and igneous records for crustal evolution indicates that it may take up to one billion years for new crust to dominate the sedimentary record. Combining models for the differentiation of the crust and the residence time of elements in the upper crust indicates that the average rate of crust formation is some 2-3 times higher than most previous estimates. PMID:17051208</p> <div class="credits"> <p class="dwt_author">Hawkesworth, C J; Kemp, A I S</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-10-19</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_10");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a 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href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a style="font-weight: bold;">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_13");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">221</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19930064886&hterms=recycling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drecycling"> <span id="translatedtitle">Estimation of <span class="hlt">continental</span> precipitation recycling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The total amount of water that precipitates on large <span class="hlt">continental</span> regions is supplied by two mechanisms: 1) advection from the surrounding areas external to the region and 2) evaporation and transpiration from the land surface within the region. The latter supply mechanism is tantamount to the recycling of precipitation over the <span class="hlt">continental</span> area. The degree to which regional precipitation is supplied by recycled moisture is a potentially significant climate feedback mechanism and land surface-atmosphere interaction, which may contribute to the persistence and intensification of droughts. Gridded data on observed wind and humidity in the global atmosphere are used to determine the convergence of atmospheric water vapor over <span class="hlt">continental</span> regions. A simplified model of the atmospheric moisture over continents and simultaneous estimates of regional precipitation are employed to estimate, for several large <span class="hlt">continental</span> regions, the fraction of precipitation that is locally derived. The results indicate that the contribution of regional evaporation to regional precipitation varies substantially with location and season. For the regions studied, the ratio of locally contributed to total monthly precipitation generally lies between 0. 10 and 0.30 but is as high as 0.40 in several cases.</p> <div class="credits"> <p class="dwt_author">Brubaker, Kaye L.; Entekhabi, Dara; Eagleson, P. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1993-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">222</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/51310787"> <span id="translatedtitle">Fluid flow paths and upper <span class="hlt">plate</span> tectonics at erosional margins</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">An understanding of fluid flow regime and tectonics of convergent margins dominated by subduction erosion processes lags behind that for accretionary margins. Recent seafloor mapping and seismic images along Middle America and North Chile indicate that tectonic processes that pervasively fracture the upper <span class="hlt">plate</span> across the entire <span class="hlt">continental</span> slope create a complex hydrological system characterizing erosional margins. The most spectacular</p> <div class="credits"> <p class="dwt_author">C. R. Ranero; W. Weinrebe; R. von Huene; C. Huguen; H. Sahling; G. Bohrmann</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">223</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AGUFM.T32B..08N"> <span id="translatedtitle"><span class="hlt">Continental</span> Crust Growth as a Result of <span class="hlt">Continental</span> Collision: Ocean Crust Melting and Melt Preservation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The significance of the <span class="hlt">continental</span> crust (CC) on which we live is self-evident. However, our knowledge remains limited on its origin, its way and rate of growth, and how it has acquired the “andesitic” composition from mantle derived magmas. Compared to rocks formed from mantle derived magmas in all tectonic settings, volcanic arc rocks associated with oceanic lithosphere subduction share some common features with the CC; both are relatively depleted in “fluid-insoluble” elements (e.g., Nb, Ta and Ti), but enriched in “fluid-soluble” elements (e.g., U, K and Pb). These chemical characteristics are referred to as the “arc-like signature”, and point to a genetic link between subduction-zone magmatism and CC formation, thus leading to the “island-arc” model widely accepted for the origin of the CC over the past 40 years. However, it has been recognized also that this “island-arc” model has several difficulties. These include (1) bulk arc crust (AC) is basaltic, whereas the bulk CC is andesitic [1]; (2) AC has a variably large Sr excess whereas the CC is Sr deficient [2]; and (3) AC production is mass-balanced by subduction-erosion and sediment recycling, thus contributing no new mass to CC growth, at least in the Phanerozoic [3,4]. Our data on magmatic rocks (both volcanic and intrusive) formed during the India-Asia <span class="hlt">continental</span> collision (~65 - ~45Ma) [5] show a remarkable compositional similarity to the bulk CC with the typical “arc-like signature” [6]. Also, these syncollisional felsic rocks exhibit strong mantle isotopic signatures, implying that they were recently derived from a mantle source. The petrology and geochemistry of these syncollisional felsic rocks is most consistent with an origin via partial melting of upper oceanic crust (i.e., last fragments of underthrusting oceanic crust) under amphibolite facies conditions, adding net mantle-derived materials to form juvenile CC mass. This leads to the logical and testable hypothesis that <span class="hlt">continental</span> collision produces and preserves the juvenile crust, and hence maintains net <span class="hlt">continental</span> growth. References: [1] Gill, Orogenic andesites and <span class="hlt">plate</span> tectonics, Springer-Verlag, New York., 390 pp, 1981; [2] Niu & O’Hara, Lithos, 112, 1-17, 2009; [3] von Huene & Scholl, Rev. Geophys., 29, 279-316, 1991; [4] Clift & Vannucchi, Rev. Geophys., 42, RG2001., 2004; [5] Mo et al., Chem. Geol., 250, 49-67, 2008; [6] Rudnick & Gao, Treat. Geochem., 3, 1-64, 2003.</p> <div class="credits"> <p class="dwt_author">Niu, Y.; Zhao, Z.; Zhou, S.; Zhu, D.; Dong, G.; Mo, X.; Xie, G.; Dong, X.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">224</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1606503"> <span id="translatedtitle"><span class="hlt">Override</span> of the Osteoclast Defect in Osteopontin-Deficient Mice by Metastatic Tumor Growth in the Bone</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Osteopontin (OPN) is a major noncollagenous protein of bone that is frequently up-regulated in tumors, where it enhances tumor growth. OPN-deficient mice are resistant to stimulated bone resorption, including that occurring after ovariectomy. Using a new syngeneic model of bone metastasis (r3T), we examined whether OPN-deficient mice are similarly resistant to bone loss resulting from osteolytic tumor growth. Transformed mammary epithelial cells, r3T, which express parathyroid hormone-related protein but not receptor activator of nuclear factor-?B ligand, were injected via the intracardiac route into both wild-type and OPN?/? mice. We measured tumor burden in the bone by quantitative polymerase chain reaction assay and evaluated bone loss by X-ray and microCT. Unexpectedly, bone loss was similar in OPN?/? and wild-type mice bearing similar-sized tumors. Osteoclast number was comparable in both genotypes, and the expression of bone sialoprotein was similar in tumor-bearing bones of both genotypes, excluding two potential mechanisms of <span class="hlt">overriding</span> the defect. Taken together, these results indicate that in the absence of OPN, the bone loss associated with tumor growth at the bone site proceeds rapidly despite the osteoclast defects documented in OPN?/? mice, suggesting that the mechanism of bone loss due to tumor growth differs from that occurring in other pathologies.</p> <div class="credits"> <p class="dwt_author">Natasha, Tajneen; Kuhn, Misty; Kelly, Owen; Rittling, Susan R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">225</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3366670"> <span id="translatedtitle">A Marine Anthraquinone SZ-685C <span class="hlt">Overrides</span> Adriamycin-Resistance in Breast Cancer Cells through Suppressing Akt Signaling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Breast cancer remains a major health problem worldwide. While chemotherapy represents an important therapeutic modality against breast cancer, limitations in the clinical use of chemotherapy remain formidable because of chemoresistance. The HER2/PI-3K/Akt pathway has been demonstrated to play a causal role in conferring a broad chemoresistance in breast cancer cells and thus justified to be a target for enhancing the effects of anti-breast cancer chemotherapies, such as adriamycin (ADR). Agents that can either enhance the effects of chemotherapeutics or overcome chemoresistance are urgently needed for the treatment of breast cancer. In this context, SZ-685C, an agent that has been previously shown, as such, to suppress Akt signaling, is expected to increase the efficacy of chemotherapy. Our current study investigated whether SZ-685C can <span class="hlt">override</span> chemoresistance through inhibiting Akt signaling in human breast cancer cells. ADR-resistant cells derived from human breast cancer cell lines MCF-7, MCF-7/ADR and MCF-7/Akt, were used as models to test the effects of SZ-685C. We found that SZ-685C suppressed the Akt pathway and induced apoptosis in MCF-7/ADR and MCF-7/Akt cells that are resistant to ADR treatment, leading to antitumor effects both in vitro and in vivo. Our data suggest that use of SZ-685C might represent a potentially promising approach to the treatment of ADR-resistant breast cancer.</p> <div class="credits"> <p class="dwt_author">Zhu, Xun; He, Zhenjian; Wu, Jueheng; Yuan, Jie; Wen, Weitao; Hu, Yiwen; Jiang, Yi; Lin, Cuiji; Zhang, Qianhui; Lin, Min; Zhang, Henan; Yang, Wan; Chen, Hong; Zhong, Lili; She, Zhigang; Chen, Shengping; Lin, Yongcheng; Li, Mengfeng</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">226</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://svs.gsfc.nasa.gov/vis/a000000/a002900/a002953/index.html"> <span id="translatedtitle">Tectonic <span class="hlt">Plates</span> and <span class="hlt">Plate</span> Boundaries (WMS)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The earths crust is constantly in motion. Sections of the crust, called <span class="hlt">plates</span>, push against each other due to forces from the molten interior of the earth. The areas where these <span class="hlt">plates</span> collide often have increased volcanic and earthquake activity. These images show the locations of the <span class="hlt">plates</span> and their boundaries in the earths crust. Convergent boundaries are areas where two <span class="hlt">plates</span> are pushing against each other and one <span class="hlt">plate</span> may be subducting under another. Divergent boundaries have two <span class="hlt">plates</span> pulling away from each other and indicate regions where new land could be created. Transform boundaries are places where two <span class="hlt">plates</span> are sliding against each other in opposite directions, and diffuse boundaries are places where two <span class="hlt">plates</span> have the same relative motion. Numerous small microplates have been omitted from the <span class="hlt">plate</span> image. These images have been derived from images made available by the United States Geological Surveys Earthquake Hazards Program.</p> <div class="credits"> <p class="dwt_author">Sokolowsky, Eric; Mitchell, Horace</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-06-14</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">227</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/40382266"> <span id="translatedtitle">Pre-seismic crustal deformation caused by an underthrusting oceanic <span class="hlt">plate</span>, in eastern Hokkaido, Japan</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Eastern Hokkaido is being considered as one of the prime candidates for a future great earthquake in Japan. Geodetic work and seismological data suggest that the <span class="hlt">continental</span> <span class="hlt">plate</span> is being compressed and dragged down into the asthenosphere by the underthrusting Pacific <span class="hlt">plate</span>. A quantitative examination of this idea was carried out by an application of the finite-element method to a</p> <div class="credits"> <p class="dwt_author">Kunihiko Shimazaki</p> <p class="dwt_publisher"></p> <p class="publishDate">1974-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">228</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/jb/v080/i008/JB080i008p01053/JB080i008p01053.pdf"> <span id="translatedtitle">Subduction of the Nazca <span class="hlt">plate</span> under Peru as evidenced by focal mechanisms and by seismicity</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The focal mechanisms of 40 earthquakes in Peru and Ecuador, together with the seismicity of the region, indicate particular features of the subduction of the oceanic <span class="hlt">plate</span> beneath this portion of South America. At shallow depths near the coast and at foci along the contact between the subduction zone and the <span class="hlt">continental</span> <span class="hlt">plate</span> the focal mechanisms indicate an underthrust of</p> <div class="credits"> <p class="dwt_author">William Stauder</p> <p class="dwt_publisher"></p> <p class="publishDate">1975-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">229</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/41098425"> <span id="translatedtitle">Stability and dynamics of the <span class="hlt">continental</span> tectosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Continental</span> cratons overlie thick, high-viscosity, thermal and chemical boundary layers, where the chemical boundary layers are less dense than they would be due to thermal effects alone, perhaps because they are depleted in basaltic constituents. If the <span class="hlt">continental</span> tectosphere is the same age as the overlying Archaean crust, then the <span class="hlt">continental</span> tectosphere must be able to survive for several billion</p> <div class="credits"> <p class="dwt_author">Steven S Shapiro; Bradford H Hager; Thomas H Jordan</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">230</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1615127E"> <span id="translatedtitle">Capturing <span class="hlt">Continental</span> Rupture Processes in Afar</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Both <span class="hlt">continental</span> and oceanic rifting processes are highly 3D, but the stability of the along-axis segmentation from rifting to breakup, and its relationship to seafloor spreading remains debated. Three-dimensional models of the interactions of faults and magmatism in time and space are in development, but modelling and observations suggest that magmatic segments may propagate and/or migrate during periods of magmatism. Our ability to discriminate between the various models in large part depends on the quality of data in the ocean-transition zone, or, observations from zones of incipient <span class="hlt">plate</span> rupture. Largely 2D crustal-scale seismic data from magmatic passive margins reveal large magmatic additions to the crust, but the timing of this heat and mass transfer is weakly constrained. Thus, the lack of information on the across rift breadth of the deforming zone at rupture, and the relationship between the early rift segmentation and the seafloor spreading segmentation represent fundamental gaps in knowledge. Our study of Earth's youngest magmatic margin, the superbly exposed, tectonically active southern Red Sea, aims to answer the following questions: What are the geometry and kinematics of active fault systems across the 'passive margin' to zone of incipient <span class="hlt">plate</span> rupture? What is the relationship between the initial border fault segmentation, and the breakup zone segmentation? What is the distribution of active deformation and magmatism, and how does it compare to time-averaged strain patterns? We integrate results of recent experiments that suggest widespread replacement of crust and mantle lithosphere beneath the 'passive' margin, and explain the ongoing seismic deformation as a consequence of bending stresses across the ocean-continent transition, with or without a dynamic component.</p> <div class="credits"> <p class="dwt_author">Ebinger, Cynthia; Belachew, Manahloh; Tepp, Gabrielle; Keir, Derek; Ayele, Atalay</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">231</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1990Tectp.181...83N"> <span id="translatedtitle">Active faults, stress field and <span class="hlt">plate</span> motion along the Indo-Eurasian <span class="hlt">plate</span> boundary</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The active faults of the Himalayas and neighboring areas are direct indicators of Recent and sub-Recent crustal movements due to <span class="hlt">continental</span> collision between the Indian and Eurasian <span class="hlt">plates</span>. The direction of the maximum horizontal shortening or horizontal compressive stress axes deduced from the strike and type of active faulting reveals a characteristic regional stress field along the colliding boundary. The trajectories of the stress axes along the transcurrent faults and the Eastern Himalayan Front, are approximately N-S, parallel to the relative motion of the two <span class="hlt">plates</span>. However, along the southern margin of the Eurasian <span class="hlt">plate</span>, they are NE-SW in the Western Himalayan Front and NW-SE to E-W in the Kirthar-Sulaiman Front, which is not consistent with the direction of relative <span class="hlt">plate</span> motion. A simple model is proposed in order to explain the regional stress pattern. In this model, the tectonic sliver between the transcurrent faults and the <span class="hlt">plate</span> margin, is dragged northward by the oblique convergence of the Indian <span class="hlt">plate</span>. Thus, the direction of relative motion between the tectonic sliver and the Indian <span class="hlt">plate</span> changes regionally, causing local compressive stress fields. Judging from the long-term slip rates along the active faults, the relative motion between the Indian and Eurasian <span class="hlt">plates</span> absorbed in the colliding zone is about one fourth of its total amount; the rest may be consumed along the extensive strike-slip faults in Tibet and China.</p> <div class="credits"> <p class="dwt_author">Nakata, Takashi; Otsuki, Kenshiro; Khan, S. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">232</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.oceanexplorer.noaa.gov/explorations/02fire/background/education/media/ring_big_plates_5_6.pdf"> <span id="translatedtitle">The Biggest <span class="hlt">Plates</span> on Earth: <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">In this lesson, students investigate the movement of Earth's tectonic <span class="hlt">plates</span>, the results of these movements, and how magnetic anomalies present at spreading centers document the motion of the crust. As a result of this activity, students will be able to describe the motion of tectonic <span class="hlt">plates</span>, differentiate between three types of <span class="hlt">plate</span> boundaries, infer what type of boundary exists between two tectonic <span class="hlt">plates</span>, and understand how magnetic anomalies provide a record of geologic history and crustal motion around spreading centers. As an example, they will also describe <span class="hlt">plate</span> boundaries and tectonic activity in the vicinity of the Juan de Fuca <span class="hlt">plate</span> adjacent to the Pacific Northwest coast of North America.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">233</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6597111"> <span id="translatedtitle">Global Cretaceous <span class="hlt">plate</span> tectonics and paleogeography</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The International Geologic Correlation Program (IGCP) Project 191, The Cretaceous Paleoclimatic Atlas Project has compiled 89 Cretaceous paleogeographic maps representing ten regions or continents. The map resolution varies from stage by stage (e.g. North America, Europe, USSR, Australia) to four maps (e.g. China, Southern South America) to a compilation of localities (Antarctica). The paleogeography is plotted here on global <span class="hlt">plate</span> tectonic reconstructions for each stage. The reconstructions include <span class="hlt">continental</span> positions and latitude. In addition, the oceanic <span class="hlt">plates</span> are reconstructed including bathymetry based on a thermal age-depth relationship. The compiled paleogeography and <span class="hlt">plate</span> tectonic base maps represent the most comprehensive framework for plotting and analyzing sedimentologic, geochemical and paleontologic data with respect to geography and latitude for the Cretaceous time period.</p> <div class="credits"> <p class="dwt_author">Barron, E.J.; Beeson, D.; Chen, P.; Dingle, R.V.; Frakes, L.A; Funnell, B.M.; Kauffman, E.G.; Petri, S.; Reyment, R.A.; Riccardi, A.C.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">234</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60605170"> <span id="translatedtitle">Earth's Decelerating Tectonic <span class="hlt">Plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Space geodetic and oceanic magnetic anomaly constraints on tectonic <span class="hlt">plate</span> motions are employed to determine a new global map of present-day rates of change of <span class="hlt">plate</span> velocities. This map shows that Earth's largest <span class="hlt">plate</span>, the Pacific, is presently decelerating along with several other <span class="hlt">plates</span> in the Pacific and Indo-Atlantic hemispheres. These <span class="hlt">plate</span> decelerations contribute to an overall, globally averaged slowdown</p> <div class="credits"> <p class="dwt_author">A M Forte; R Moucha; D B Rowley; S Quere; J X Mitrovica; N A Simmons; S P Grand</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">235</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/7164217"> <span id="translatedtitle">Seismological studies of the <span class="hlt">continental</span> lithosphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The lithosphere,'' as used here in the generally accepted sense, includes the crust of the earth and that part of its upper mantle that, together with the crust, constitute the moving tectonic <span class="hlt">plates</span>. These are underlain by the more easily deformed asthenosphere'' at a depth on the order of 100 km. The seismic low-velocity zone (LVZ) in the mantle is usually identified with the asthenosphere. We are convinced that a better understanding of the <span class="hlt">continental</span> lithosphere is vital to society, much of that understanding can only be gained by the application of modern seismological methods, and to accomplish these objectives the United States needs urgently to upgrade its seismological capability. Our aim in this report is to convey to the reader our convictions with the hope that they will be translated into action. We suggest specific studies that should be undertaken now and some actions that, if taken, should realize the full potential of seismological techniques. 110 refs., 35 figs., 1 tab.</p> <div class="credits"> <p class="dwt_author">Not Available</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">236</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://learningcenter.nsta.org/product_detail.aspx?id=10.2505/7/SCB-PT.4.1"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics: Consequences of <span class="hlt">Plate</span> Interactions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This Science Object is the fourth of five Science Objects in the <span class="hlt">Plate</span> Tectonic SciPack. It identifies the events that may occur and landscapes that form as a result of different <span class="hlt">plate</span> interactions. The areas along <span class="hlt">plate</span> margins are active. <span class="hlt">Plates</span> pushing against one another can cause earthquakes, volcanoes, mountain formation, and very deep ocean trenches. <span class="hlt">Plates</span> pulling apart from one another can cause smaller earthquakes, magma rising to the surface, volcanoes, and oceanic valleys and mountains from sea-floor spreading. <span class="hlt">Plates</span> sliding past one another can cause earthquakes and rock deformation. Learning Outcomes:� Explain why volcanoes and earthquakes occur along <span class="hlt">plate</span> boundaries. � Explain how new sea floor is created and destroyed.� Describe features that may be seen on the surface as a result of <span class="hlt">plate</span> interactions.</p> <div class="credits"> <p class="dwt_author">National Science Teachers Association (NSTA)</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">237</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://commons.wikimedia.org/wiki/File%3ACaribbean_plate_tectonics-en.png"> <span id="translatedtitle">Caribbean <span class="hlt">plate</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This illustration available at Wikimedia Commons shows the <span class="hlt">plate</span> tectonic setting in the Caribbean. <span class="hlt">Plate</span> boundaries are color-coded by margin type and <span class="hlt">plate</span> motions are noted with direction and magnitude in mm/yr.</p> <div class="credits"> <p class="dwt_author">Sting; Commons, Wikimedia</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">238</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JSG....64....3N"> <span id="translatedtitle"><span class="hlt">Continental</span> transforms: A view from the Alpine Fault</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Continental</span> transform faults are dominantly highly localized strike-slip shear zones hundreds of kilometers long that accumulate tens to hundreds of kilometers of displacement. From work on the Alpine Fault, we pose the questions: what is the deep structure of a <span class="hlt">continental</span> transform, and how does the displacement become localized? We review research on the Alpine Fault and propose a model in which the fault partitions at depth into a steep zone extending into the mantle with largely fault-parallel motion and a flat ductile decollement in the lower crust. The fault localizes around two-thirds of the <span class="hlt">plate</span> motion within a 100 km wide zone of distributed deformation. A review of other active <span class="hlt">continental</span> fault systems suggests that variation between them may reflect their tectonic origins, the nature of the crust in which they develop, the presence of a significant oblique component of motion, and the displacement rate. All however have evidence for the development of a single principal fault zone that carries ?50% of the total displacement and extends as a localized zone of shear into the upper mantle. We review mechanisms of strain weakening and suggest that localization of a principal fault may be initiated in the seismogenic crust and through a series of positive feedbacks eventually extend through the lower crust into the upper mantle.</p> <div class="credits"> <p class="dwt_author">Norris, Richard J.; Toy, Virginia G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">239</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/7247662"> <span id="translatedtitle">Convergent <span class="hlt">plate</span> margin east of North Island, New Zealand</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The Indian-Pacific <span class="hlt">plate</span> boundary passes along the eastern margin of North Island, New Zealand, with the Pacific <span class="hlt">plate</span> being thrust under the Indian <span class="hlt">plate</span> to the west. The <span class="hlt">continental</span> slope forming the Indian <span class="hlt">plate</span> margin is broad with a well-formed series of trench slope basins and intervening ridges along the <span class="hlt">continental</span> slope and shelf, subparallel to the margin, and continuing onto land. Multichannel seismic reflection data recorded across this margin show a thick (2.5-km) sedimentary section overlying oceanic basement in the deep-water part of the profile, and part of this sedimentary section is apparently being subducted under the accretionary prism. At the toe of the <span class="hlt">continental</span> slope, nascent thrusts, often showing little apparent offset but a change in reflection amplitude, occur over a broad region. Well-defined trench slope basins show several episodes of basin formation and thrusting and are similar to structural interpretations for adjacent onshore basins. A bottom simulating reflector, which may delineate a gas-hydrate layer, can be traced over the midslope part of the profile. A major reflector, interpreted as the base of the accretionary prism, can be traced discontinuously to the coast where it coincides with the top of a zone of high seismicity, considered to mark the top of the subducted Pacific <span class="hlt">plate</span>.</p> <div class="credits"> <p class="dwt_author">Davey, F.J; Hampton, M.; Lewis, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">240</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54169667"> <span id="translatedtitle">The General Theory of <span class="hlt">Plate</span> Tectonics; No Role for Lower Mantle Components, Thermals or Other ad hoc Adjustments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Plate</span> tectonics introduces chemical,thermal,viscosity,melting and density inhomogeneities into the mantle and stress inhomogeneity into the <span class="hlt">plates</span>.Idealized models often assume uniform mantle, rigid homogeneous <span class="hlt">plates</span>,non-passive mantle, and ad hoc explanations for island chains, melting anomalies and <span class="hlt">continental</span> breakup. <span class="hlt">Plates</span>, however, drive and break themselves and organize the underlying mantle, in common with other cooled-from-above systems.Pressure, often ignored in simulations, suppresses thermal</p> <div class="credits"> <p class="dwt_author">D. L. Anderson; A. Meibom</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_11");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_12");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a style="font-weight: bold;">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_14");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">241</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2000Tecto..19...44S"> <span id="translatedtitle">Formation and evolution of the Solander Basin, southwestern South Island, New Zealand, controlled by a major fault in <span class="hlt">continental</span> crust and upper mantle</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Seismic reflection and refraction data from the Solander Basin, southern New Zealand, show that its structural evolution has been controlled by a major fault, named here the Tauru Fault, that cuts the entire crust and splays into a diffuse zone in the upper mantle. The tectonic setting of the Solander Basin has evolved from Eocene-Oligocene extension and transtension to Miocene-Quaternary transpression and subduction. The Tauru Fault is 100 km east of the active Puysegur subduction zone thrust and is part of the <span class="hlt">overriding</span> <span class="hlt">plate</span>. On the basis of lower crustal reflectivity, the base of the crust beneath the adjacent Stewart Island shelf is at ˜30 km depth (˜9 s two-way time (TWT)), and rises to ˜20 km (˜8 s TWT) beneath the Solander Basin. This is consistent with gravity data. Prominent dipping reflections show that the Tauru Fault can be traced to ˜30 km depth (˜12 s TWT), where it merges with a zone of subhorizontal reflectors in the upper mantle. The Tauru Fault dips ˜30° northeast and appears to offset the Moho in a reverse sense. Stratigraphic relationships show that the Tauru Fault was active as a normal fault during Eocene extension, when Solander Basin crust was thinned and ocean crust was generated farther south in the Solander Trough. It has been reactivated as a reverse fault during at least two phases of Miocene-Quaternary compression and is still active. The strike of the Tauru Fault, which is parallel to Paleozoic-Mesozoic structures and was poorly oriented for the known Eocene extension direction, strongly suggests that it formed prior to Eocene time. The Tauru Fault significantly influenced the geometry of Eocene basin formation, producing a strongly asymmetric basin dominated by east dipping normal faults, with a single eastern boundary fault. Our data demonstrate that Miocene-Quaternary simple shear associated with the Tauru Fault cuts the whole crust and continues into the upper mantle. We conclude that variations in strength of the lithosphere, particularly associated with inherited structures in the crust and upper mantle, may control many aspects of basin development, passive margin formation, and the kinematics of <span class="hlt">continental</span> deformation zones.</p> <div class="credits"> <p class="dwt_author">Sutherland, Rupert; Melhuish, Anne</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">242</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6247F"> <span id="translatedtitle">History and Evolution of Precambrian <span class="hlt">plate</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Plate</span> tectonics is a global self-organising process driven by negative buoyancy at thermal boundary layers. Phanerozoic <span class="hlt">plate</span> tectonics with its typical subduction and orogeny is relatively well understood and can be traced back in the geological records of the continents. Interpretations of geological, petrological and geochemical observations from Proterozoic and Archean orogenic belts however (e.g., Brown, 2006), suggest a different tectonic regime in the Precambrian. Due to higher radioactive heat production the Precambrian lithosphere shows lower internal strength and is strongly weakened by percolating melts. The fundamental difference between Precambrian and Phanerozoic tectonics is therefore the upper-mantle temperature, which determines the strength of the upper mantle (Brun, 2002) and the further tectonic history. 3D petrological-thermomechanical numerical modelling experiments of oceanic subduction at an active <span class="hlt">plate</span> at different upper-mantle temperatures show these different subduction regimes. For upper-mantle temperatures < 175 K above the present day value a subduction style appears which is close to present day subduction but with more frequent slab break-off. At upper-mantle temperatures 175 - 250 K above present day values steep subduction continues but the <span class="hlt">plates</span> are weakened enough to allow buckling and also lithospheric delamination and drip-offs. For upper-mantle temperatures > 250 K above the present day value no subduction occurs any more. The whole lithosphere is delaminating and due to strong volcanism and formation of a thicker crust subduction is inhibited. This stage of 200-250 K higher upper mantle temperature which corresponds roughly to the early Archean (Abbott, 1994) is marked by strong volcanism due to sublithospheric decompression melting which leads to an equal thickness for both oceanic and <span class="hlt">continental</span> <span class="hlt">plates</span>. As a consequence subduction is inhibited, but a compressional setup instead will lead to orogeny between a <span class="hlt">continental</span> or felsic terrain and an oceanic or mafic terrain as well as internal crustal convection. Small-scale convection with plume shaped cold downwellings also in the upper mantle is of increased importance compared to the large-scale subduction cycle observed for present temperature conditions. It is also observed that lithospheric downwellings may initiate subduction by pulling at and breaking the <span class="hlt">plate</span>. References: Abbott, D., Drury, R., Smith, W.H.F., 1994. Flat to steep transition in subduction style. Geology 22, 937-940. Brown, M., 2006. Duality of thermal regimes is the distinctive characteristic of <span class="hlt">plate</span> tectonics since the neoarchean. Geology 34, 961-964. Brun, J.P., 2002. Deformation of the <span class="hlt">continental</span> lithosphere: Insights from brittle-ductile models. Geological Society, London, Special Publications 200, 355-370.</p> <div class="credits"> <p class="dwt_author">Fischer, Ria; Gerya, Taras</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">243</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24747563"> <span id="translatedtitle">Bile acids <span class="hlt">override</span> steatosis in farnesoid X receptor deficient mice in a model of non-alcoholic steatohepatitis.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, and the pathogenesis is still not well known. The farnesoid X receptor (FXR) is a member of the nuclear hormone receptor superfamily and plays an essential role in maintaining bile acid and lipid homeostasis. In this study, we study the role of FXR in the pathogenesis of NFALD. We found that FXR deficient (FXR(-/-)) mice fed methionine- and choline-deficient (MCD) diet had higher serum ALT and AST activities and lower hepatic triglyceride levels than wild-type (WT) mice fed MCD diet. Expression of genes involved in inflammation (VCAM-1) and fibrosis (?-SMA) was increased in FXR(-/-) mice fed MCD diet (FXR(-/-)/MCD) compared to WT mice fed MCD diet (WT/MCD). Although MCD diet significantly induced hepatic fibrosis in terms of liver histology, FXR(-/-)/MCD mice showed less degree of hepatic steatosis than WT/MCD mice. Moreover, FXR deficiency synergistically potentiated the elevation effects of MCD diet on serum and hepatic bile acids levels. The super-physiological concentrations of hepatic bile acids in FXR(-/-)/MCD mice inhibited the expression of genes involved in fatty acid uptake and triglyceride accumulation, which may be an explanation for less steatosis in FXR(-/-)/MCD mice in contrast to WT/MCD mice. These results suggest that hepatic bile acids accumulation could <span class="hlt">override</span> simple steatosis in hepatic injury during the progression of NAFLD and further emphasize the role of FXR in maintaining hepatic bile acid homeostasis in liver disorders and in hepatic protection. PMID:24747563</p> <div class="credits"> <p class="dwt_author">Wu, Weibin; Liu, Xijun; Peng, Xiaomin; Xue, Ruyi; Ji, Lingling; Shen, Xizhong; Chen, She; Gu, Jianxin; Zhang, Si</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-23</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">244</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3473047"> <span id="translatedtitle">Mirrored Prominent Deck B Phenomenon: Frequent Small Losses <span class="hlt">Override</span> Infrequent Large Gains in the Inverted Iowa Gambling Task</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Since Bechara et al. pioneered its development, the Iowa Gambling Task (IGT) has been widely applied to elucidate decision behavior and medial prefrontal function. Although most decision makers can hunch the final benefits of IGT, ventromedial prefrontal lesions generate a myopic choice pattern. Additionally, the Iowa group developed a revised IGT (inverted IGT, iIGT) to confirm the IGT validity. Each iIGT trial was generated from the trial of IGT by multiplying by a “?” to create an inverted monetary value. Thus, bad decks A and B in the IGT become good decks iA and iB in the iIGT; additionally, good decks C and D in the IGT become bad decks iC and iD in the iIGT. Furthermore, IGT possessed mostly the gain trials, and iIGT possessed mainly the loss trials. Therefore, IGT is a frequent-gain–based task, and iIGT is a frequent-loss–based task. However, a growing number of IGT-related studies have identified confounding factors in IGT (i.e., gain-loss frequency), which are demonstrated by the prominent deck B phenomenon (PDB phenomenon). Nevertheless, the mirrored PDB phenomenon and guiding power of gain-loss frequency in iIGT have seldom been reexamined. This experimental finding supports the prediction based on gain-loss frequency. This study identifies the mirrored PDB phenomenon. Frequent small losses <span class="hlt">override</span> occasional large gains in deck iB of the iIGT. Learning curve analysis generally supports the phenomenon based on gain-loss frequency rather than final outcome. In terms of iIGT and simple versions of iIGT, results of this study demonstrate that high-frequency loss, rather than a satisfactory final outcome, dominates the preference of normal decision makers under uncertainty. Furthermore, normal subjects prefer “no immediate punishment” rather than “final reward” under uncertainty.</p> <div class="credits"> <p class="dwt_author">Lin, Ching-Hung; Song, Tzu-Jiun; Lin, Yu-Kai; Chiu, Yao-Chu</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">245</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5237428"> <span id="translatedtitle">DOSECC <span class="hlt">Continental</span> Scientific Drilling Program</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Deep Observation and Sampling of the Earth's <span class="hlt">Continental</span> Crust (DOSECC, for short) is a nonprofit corporation, currently composed of 41 member universities, that was founded to manage <span class="hlt">continental</span> Scientific Drilling Programs somewhat as Joint Oceanographic Institutions (JOI), Inc., manages the Ocean Drilling Program. Funding is provided by the National Science Foundation, with additional support from the US Geological Survey (USGS) and the Department of Energy (DOE). DOSECC currently has two projects in actual operation and several under development. The long-term DOSECC program can be separated into categories based either on drilling depth or on objectives. The first category consists of shallow- to intermediate-depth drilling (up to about 5 km) designed to attain targets related to a better understanding of active processes in the <span class="hlt">continental</span> crust. The second category of targets push the limit of drilling technology in terms of depth and sometimes with respect to temperature, pressure, and/or corrosive fluid environments. Ultimately DOSECC drilling projects are expected to achieve depths exceeding 15 km. Such ultradeep holes will not only examine dynamic processes in the crust but will also explore crustal history, structures, and conditions at depth. Current budgets allow the drilling of projects in the first category, and planning for eventual deeper drilling at a number of locations is in progress. This paper describes the first hole in the DOSECC program that is presently being drilled at Cajon Pass on the San Andreas fault near San Bernardino in central California.</p> <div class="credits"> <p class="dwt_author">Not Available</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">246</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=%22Tectonic+Plates%22&pg=4&id=EJ409416"> <span id="translatedtitle">Earthquakes in Stable <span class="hlt">Continental</span> Crust.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Discussed are some of the reasons for earthquakes which occur in stable crust away from familiar zones at the ends of tectonic <span class="hlt">plates</span>. Crust stability and the reactivation of old faults are described using examples from India and Australia. (CW)</p> <div class="credits"> <p class="dwt_author">Johnston, Arch C.; Kanter, Lisa R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1990-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">247</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011GeoJI.184...43B"> <span id="translatedtitle">Subduction and exhumation of <span class="hlt">continental</span> crust: insights from laboratory models</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">When slivers of <span class="hlt">continental</span> crust and sediment overlying oceanic lithosphere enter a subduction zone, they may be scraped off at shallow levels, subducted to depths of up to 100-200 km and then exhumed as high pressure (HP) and ultra-high pressure (UHP) rocks, or subducted and recycled in the mantle. To investigate the factors that influence the behaviour of subducting slivers of <span class="hlt">continental</span> material, we use 3-D dynamically consistent laboratory models. A laboratory analogue of a slab-upper mantle system is set up with two linearly viscous layers of silicone putty and glucose syrup in a tank. A sliver of <span class="hlt">continental</span> material, also composed of silicone putty, overlies the subducting lithosphere, separated by a syrup detachment. The density of the sliver, viscosity of the detachment, geometry of the subducting system (attached <span class="hlt">plate</span> versus free ridge) and dimensions of the sliver are varied in 34 experiments. By varying the density of the sliver and viscosity of the detachment, we can reproduce a range of sliver behaviour, including subduction, subduction and exhumation from various depths and offscraping. Sliver subduction and exhumation requires sufficient sliver buoyancy and a detachment that is strong enough to hold the sliver during initial subduction, but weak enough to allow adequate sliver displacement or detachment for exhumation. Changes to the system geometry alter the slab dip, subduction velocity, pattern of mantle flow and amount of rollback. Shallower slab dips with more trench rollback produce a mantle flow pattern that aids exhumation. Steeper slab dips allow more buoyancy force to be directed in the up-dip direction of the plane of the <span class="hlt">plate</span>, and aide exhumation of subducted slivers. Slower subduction can also aide exhumation, but if slab dip is too steep or subduction too slow, the sliver will subduct to only shallow levels and not exhume. Smaller slivers are most easily subducted and exhumed and influenced by the mantle flow.</p> <div class="credits"> <p class="dwt_author">Bialas, Robert W.; Funiciello, Francesca; Faccenna, Claudio</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">248</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005E%26PSL.229..247V"> <span id="translatedtitle">Dynamics of <span class="hlt">continental</span> rift propagation: the end-member modes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">An important aspect of <span class="hlt">continental</span> rifting is the progressive variation of deformation style along the rift axis during rift propagation. In regions of rift propagation, specifically transition zones from <span class="hlt">continental</span> rifting to seafloor spreading, it has been observed that contrasting styles of deformation along the axis of rift propagation are bounded by shear zones. The focus of this numerical modeling study is to look at dynamic processes near the tip of a weak zone in <span class="hlt">continental</span> lithosphere. More specifically, this study explores how modeled rift behavior depends on the value of rheological parameters of the crust. A three-dimensional finite element model is used to simulate lithosphere deformation in an extensional regime. The chosen approach emphasizes understanding the tectonic forces involved in rift propagation. Dependent on <span class="hlt">plate</span> strength, two end-member modes are distinguished. The stalled rift phase is characterized by absence of rift propagation for a certain amount of time. Extension beyond the edge of the rift tip is no longer localized but occurs over a very wide zone, which requires a buildup of shear stresses near the rift tip and significant intra-<span class="hlt">plate</span> deformation. This stage represents a situation in which a rift meets a locked zone. Localized deformation changes to distributed deformation in the locked zone, and the two different deformation styles are balanced by a shear zone oriented perpendicular to the trend. In the alternative rift propagation mode, rift propagation is a continuous process when the initial crust is weak. The extension style does not change significantly along the rift axis and lengthening of the rift zone is not accompanied by a buildup of shear stresses. Model predictions address aspects of previously unexplained rift evolution in the Laptev Sea, and its contrast with the tectonic evolution of, for example, the Gulf of Aden and Woodlark Basin.</p> <div class="credits"> <p class="dwt_author">Van Wijk, J. W.; Blackman, D. K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">249</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003TrGeo...3....1R"> <span id="translatedtitle">Composition of the <span class="hlt">Continental</span> Crust</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Earth is an unusual planet in our solar system in having a bimodal topography that reflects the two distinct types of crust found on our planet. The low-lying oceanic crust is thin (˜7 km on average), composed of relatively dense rock types such as basalt and is young (?200 Ma old) (see Chapter 3.13). In contrast, the high-standing <span class="hlt">continental</span> crust is thick (˜40 km on average), is composed of highly diverse lithologies (virtually every rock type known on Earth) that yield an average intermediate or "andesitic" bulk composition (Taylor and McLennan (1985) and references therein), and contains the oldest rocks and minerals yet observed on Earth (currently the 4.0 Ga Acasta gneisses (Bowring and Williams, 1999) and 4.4 Ga detrital zircons from the Yilgarn Block, Western Australia (Wilde et al., 2001)), respectively. Thus, the continents preserve a rich geological history of our planet's evolution and understanding their origin is critical for understanding the origin and differentiation of the Earth.The origin of the continents has received wide attention within the geological community, with hundreds of papers and several books devoted to the topic (the reader is referred to the following general references for further reading: Taylor and McLennan (1985), Windley (1995), and Condie (1997). Knowledge of the age and composition of the <span class="hlt">continental</span> crust is essential for understanding its origin. Patchett and Samson (Chapter 3.10) review the present-day age distribution of the <span class="hlt">continental</span> crust and Kemp and Hawkesworth (Chapter 3.11) review secular evolution of crust composition. Moreover, to understand fully the origin and evolution of continents requires an understanding of not only the crust, but also the mantle lithosphere that formed more-or-less contemporaneously with the crust and translates with it as the continents move across the Earth's surface. The latter topic is reviewed in Chapter 2.05.This chapter reviews the present-day composition of the <span class="hlt">continental</span> crust, the methods employed to derive these estimates, and the implications of the <span class="hlt">continental</span> crust composition for the formation of the continents, Earth differentiation, and its geochemical inventories.</p> <div class="credits"> <p class="dwt_author">Rudnick, R. L.; Gao, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">250</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002AGUFM.T61B1256L"> <span id="translatedtitle"><span class="hlt">Continental</span> Growth and Deformation in Taiwan -Insight from GPS data and Sandbox Experiments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Taiwan Mountain Belt is one of the youngest mountain belts on Earth surface. It results from the NW-directed oblique convergence between the Eurasian <span class="hlt">plate</span> and the Philippine Sea <span class="hlt">plate</span>. The accretion of the Luzon arc propagates southward and results in the <span class="hlt">continental</span> growth of Asian continent. In order to figure out the actual accretion of the Luzon Arc to the Asian continent. The former GPS (Global Positioning System) data were recalculated in consideration of Lanyu Island as a fixed point on the Philippine Sea <span class="hlt">plate</span>. Under this situation the relative movement between Asian <span class="hlt">continental</span> margin and the Philippine Sea <span class="hlt">plate</span> can be better clarified. The largest movement vector (102 mm/yr) occurs around the Suao area indicating the recent fast opening rate of Okinawa trough (~25mm/yr). The accretion of the Coastal Range to the Central Range along Western boundary of the Longitudinal Valley is about 79.2mm/yr. On the other hand, the <span class="hlt">continental</span> deformation is described insight of contours and vectors of the GPS velocity field and sand box modeling. The recent movement and displacement of the Chelungpu fault, back thrust system around the Kuanyin Basement High, the escape tectonics in southwestern Taiwan and the impact of the basement resulting in the occurrence of the out-of-sequence thrust are well documented.</p> <div class="credits"> <p class="dwt_author">Lu, C.; Yu, S.; Chu, H.; Chiao, L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">251</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6468C"> <span id="translatedtitle">Flow of material under compression in weak lower <span class="hlt">continental</span> crust can cause post-rift uplift of passive <span class="hlt">continental</span> margins</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">There are mountain ranges up to more than 2 km high along many passive <span class="hlt">continental</span> margins (e.g. Norway, eastern Australia, eastern Brazil, SE and SW Africa, east and west Greenland etc.), dubbed Elevated Passive <span class="hlt">Continental</span> Margins (EPCMs). EPCMs contain several features in common and observations indicate that uplift of these margins took place after <span class="hlt">continental</span> break-up. There are many explanations for their formation but none that satisfy all the observations. Lack of a geodynamical mechanism has meant that there has been difficulty in getting the community to accept the observational evidence. Formation of a passive <span class="hlt">continental</span> margin must take place under conditions of tension. After rifting ceases, however, the margin can come under compression from forces originating elsewhere on or below its <span class="hlt">plate</span>, e.g. orogeny elsewhere in the <span class="hlt">plate</span> or sub-lithospheric drag. The World Stress Map (www.world-stress-mp.org) shows that, where data exists, all EPCMs are currently under compression. Under sufficient compression, crust and/or lithosphere can fold, and Cloetingh & Burov (2010) showed that many <span class="hlt">continental</span> areas may have folded in this way. The wavelengths of folding observed by Cloetingh & Burov (2010) imply that the lower crust is likely to be of intermediate composition; granitic lower crust would fold with a shorter wavelength and basic lower crust would mean that the whole lithosphere would have to fold as a unit resulting in a much longer wavelength. <span class="hlt">Continental</span> crust more than 20 km thick would be separated from the mantle by a weak layer. However, crust less thick than that would contain no weak layers would become effectively annealed to the underlying strong mantle. Under sufficient horizontal compression stress, material can flow in the lower weak layer towards a <span class="hlt">continental</span> margin from the <span class="hlt">continental</span> side. The annealed extended crust and mantle under the rift means, however, that flow cannot continue towards the ocean. Mid- and lower crustal material therefore accumulates in the proximal rift and rift margin, thickening them and lifting them by isostatic response to the thickening. Flow into the rift margin is opposed by uplift and folding of the upper, strong crust, which imposes an additional normal stress, until crust thickens no more. However, flow continues through this thickened crust, thickening and uplifting the area "downstream", so widening the thickened area. Flow and uplift can continue until a reduction in imposed far-field compressive stress causes a consequent large reduction in inflow, thereby 'freezing' the thickened crust in place. Erosion of the uplifted area will lead to further uplift of the uneroded material because of the isostatic response to the erosion. Reference Cloetingh, S. & Burov, E. 2010: Lithospheric folding and sedimentary basin evolution: a review and analysis of formation mechanisms. Basin Research 22, 1365-2117. doi:10.1111/j.1365-2117.2010.00490.x.</p> <div class="credits"> <p class="dwt_author">Chalmers, James</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">252</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.classzone.com/books/earth_science/terc/content/visualizations/es0804/es0804page01.cfm?chapter_no=visualization"> <span id="translatedtitle">Observe animations of processes that occur along <span class="hlt">plate</span> boundaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">Here are three animations that reveal how tectonic <span class="hlt">plates</span> move relative to each other at three types of <span class="hlt">plate</span> boundaries--transform, convergent, and divergent boundaries. Key features such as the asthenosphere are labeled in the animations. In addition, each animation is equipped with movie control buttons that allow students to play, pause, and move forward and backward through each clip. The animation of a transform boundary shows the North American and Pacific <span class="hlt">plates</span> sliding past one another, while an oceanic <span class="hlt">plate</span> subducts under a <span class="hlt">continental</span> <span class="hlt">plate</span> producing volcanic activity in the convergent boundary animation. Two coordinated movie clips are used to demonstrate what occurs at a divergent boundary from different viewpoints. Copyright 2005 Eisenhower National Clearinghouse</p> <div class="credits"> <p class="dwt_author">Education, Terc. C.; Littell, Mcdougal</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">253</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/18075591"> <span id="translatedtitle">Dynamics of Mid-Palaeocene North Atlantic rifting linked with European intra-<span class="hlt">plate</span> deformations.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The process of <span class="hlt">continental</span> break-up provides a large-scale experiment that can be used to test causal relations between <span class="hlt">plate</span> tectonics and the dynamics of the Earth's deep mantle. Detailed diagnostic information on the timing and dynamics of such events, which are not resolved by <span class="hlt">plate</span> kinematic reconstructions, can be obtained from the response of the interior of adjacent <span class="hlt">continental</span> <span class="hlt">plates</span> to stress changes generated by <span class="hlt">plate</span> boundary processes. Here we demonstrate a causal relationship between North Atlantic <span class="hlt">continental</span> rifting at approximately 62 Myr ago and an abrupt change of the intra-<span class="hlt">plate</span> deformation style in the adjacent European continent. The rifting involved a left-lateral displacement between the North American-Greenland <span class="hlt">plate</span> and Eurasia, which initiated the observed pause in the relative convergence of Europe and Africa. The associated stress change in the European continent was significant and explains the sudden termination of a approximately 20-Myr-long contractional intra-<span class="hlt">plate</span> deformation within Europe, during the late Cretaceous period to the earliest Palaeocene epoch, which was replaced by low-amplitude intra-<span class="hlt">plate</span> stress-relaxation features. The pre-rupture tectonic stress was large enough to have been responsible for precipitating <span class="hlt">continental</span> break-up, so there is no need to invoke a thermal mantle plume as a driving mechanism. The model explains the simultaneous timing of several diverse geological events, and shows how the intra-<span class="hlt">continental</span> stratigraphic record can reveal the timing and dynamics of stress changes, which cannot be resolved by reconstructions based only on <span class="hlt">plate</span> kinematics. PMID:18075591</p> <div class="credits"> <p class="dwt_author">Nielsen, Søren B; Stephenson, Randell; Thomsen, Erik</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-12-13</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">254</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/19359581"> <span id="translatedtitle">A great earthquake rupture across a rapidly evolving three-<span class="hlt">plate</span> boundary.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">On 1 April 2007 a great, tsunamigenic earthquake (moment magnitude 8.1) ruptured the Solomon Islands subduction zone at the triple junction where the Australia and Solomon Sea-Woodlark Basin <span class="hlt">plates</span> simultaneously underthrust the Pacific <span class="hlt">plate</span> with different slip directions. The associated abrupt change in slip direction during the great earthquake drove convergent anelastic deformation of the upper Pacific <span class="hlt">plate</span>, which generated localized uplift in the forearc above the subducting Simbo fault, potentially amplifying local tsunami amplitude. Elastic deformation during the seismic cycle appears to be primarily accommodated by the <span class="hlt">overriding</span> Pacific forearc. This earthquake demonstrates the seismogenic potential of extremely young subducting oceanic lithosphere, the ability of ruptures to traverse substantial geologic boundaries, and the consequences of complex coseismic slip for uplift and tsunamigenesis. PMID:19359581</p> <div class="credits"> <p class="dwt_author">Furlong, Kevin P; Lay, Thorne; Ammon, Charles J</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-10</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">255</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19720017820&hterms=northport&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dnorthport"> <span id="translatedtitle">Sputtering and ion <span class="hlt">plating</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The proceedings of a conference on sputtering and ion <span class="hlt">plating</span> are presented. Subjects discussed are: (1) concepts and applications of ion <span class="hlt">plating</span>, (2) sputtering for deposition of solid film lubricants, (3) commercial ion <span class="hlt">plating</span> equipment, (4) industrial potential for ion <span class="hlt">plating</span> and sputtering, and (5) fundamentals of RF and DC sputtering.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">256</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.as.uky.edu/academics/departments_programs/EarthEnvironmentalSciences/EarthEnvironmentalSciences/Educational%20Materials/Documents/elearning/module04swf.swf"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics Animation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary"><span class="hlt">Plate</span> tectonics describes the behavior of Earth's outer shell, with pieces (<span class="hlt">plates</span>) bumping and grinding and jostling each other about. Explore these maps and animations to get a jump start on understanding <span class="hlt">plate</span> tectonic processes, history, and how motion of the <span class="hlt">plates</span> affects our planet today.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">257</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1999Litho..48..171P"> <span id="translatedtitle">The age of <span class="hlt">continental</span> roots</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Determination of the age of the mantle part of <span class="hlt">continental</span> roots is essential to our understanding of the evolution and stability of continents. Dating the rocks that comprise the mantle root beneath the continents has proven difficult because of their high equilibration temperatures and open-system geochemical behaviour. Much progress has been made in the last 20 years that allows us to see how <span class="hlt">continental</span> roots have evolved in different areas. The first indication of the antiquity of <span class="hlt">continental</span> roots beneath cratons came from the enriched Nd and Sr isotopic signatures shown by both peridotite xenoliths and inclusions in diamonds, requiring isolation of cratonic roots from the convecting mantle for billions of years. The enriched Nd and Sr isotopic signatures result from mantle metasomatic events post-dating the depletion events that led to the formation and isolation of the peridotite from convecting mantle. These signatures document a history of melt- and fluid-rock interaction within the lithospheric mantle. In some suites of cratonic rocks, such as eclogites, Nd and Pb isotopes have been able to trace probable formation ages. The Re-Os isotope system is well suited to dating lithospheric peridotites because of the compatible nature of Os and its relative immunity to post-crystallisation disturbance compared with highly incompatible element isotope systems. Os isotopic compositions of lithospheric peridotites are overwhelmingly unradiogenic and indicate long-term evolution in low Re/Os environments, probably as melt residues. Peridotite xenoliths from kimberlites can show some disturbed Re/Os systematics but analyses of representative suites show that beneath cratons the oldest Re depletion model ages are Archean and broadly similar to major crust-forming events. Some locations, such as Premier in southern Africa, and Lashaine in Tanzania, indicate more recent addition of lithospheric material to the craton, in the Proterozoic, or later. Of the cratons studies so far (Kaapvaal, Siberia, Wyoming and Tanzania), all indicate Archean formation of their lithospheric mantle roots. Few localities studied show any clear variation of age with depth of derivation, indicating that >150 km of lithosphere may have formed relatively rapidly. In circum-cratonic areas where the crustal basement is Proterozoic in age kimberlite-derived xenoliths give Proterozoic model ages, matching the age of the overlying crust. This behaviour shows how the crust and mantle parts of <span class="hlt">continental</span> lithospheric roots have remained coupled since formation in these areas, for billions of years, despite <span class="hlt">continental</span> drift. Orogenic massifs show more systematic behaviour of Re-Os isotopes, where correlations between Os isotopic composition and S or Re content yield initial Os isotopic ratios that define Re depletion model ages for the massifs. Ongoing Sr-Nd-Pb-Hf-Os isotopic studies of massif peridotites and new kimberlite- and basalt-borne xenolith suites from new areas, will soon enable a global understanding of the age of <span class="hlt">continental</span> roots and their subsequent evolution.</p> <div class="credits"> <p class="dwt_author">Pearson, D. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">258</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/7244051"> <span id="translatedtitle">Coordination: Southeast <span class="hlt">continental</span> shelf studies</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Under the terms of grant FG09-86ER6040 the principal investigator, D. Menzel, is responsible for coordinating activities associated with the conduct of research, sponsored by the Department of Energy, on the oceanography of the Southeast <span class="hlt">Continental</span> Shelf. These activities include: (1) serving as a contact between program managers at DOE and principal investigators associated with the program, (2) developing and implementing long-range research plans, (3) providing DOE with summaries of the results of past and current research, (4) conducting planning/reporting meetings involving principal investigators and interested agency personnel, and (5) consolidating and scheduling the use of research vessels.</p> <div class="credits"> <p class="dwt_author">Menzel, D.W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-26</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">259</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014WRR....50.3647G"> <span id="translatedtitle">Oceanic sources of <span class="hlt">continental</span> precipitation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">this special section, the authors have tried to address some of the many unanswered questions related to the transport of moisture from oceanic sources to the continents, including among others that of whether or not the moisture source regions have remained stationary over time, how the many changes in the intensity and position of the sources have affected the distribution of <span class="hlt">continental</span> precipitation, and also the question of the role of the main modes of climate variability in the variability of the moisture regions.</p> <div class="credits"> <p class="dwt_author">Gimeno, Luis</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">260</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://serc.carleton.edu/NAGTWorkshops/geodesy/activities/41187.html"> <span id="translatedtitle">Mapping <span class="hlt">Plate</span> Tectonic Boundaries</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">To prepare for this activity, students do background reading on <span class="hlt">Plate</span> Tectonics from the course textbook. Students also participate in a lecture on the discovery and formulation of the unifying theory of <span class="hlt">plate</span> tectonics, and the relationship between <span class="hlt">plate</span> boundaries and geologic features such as volcanoes. Lastly, in lecture, students are introduced to a series of geologic hazards caused by certain <span class="hlt">plate</span> tectonic interactions. The activity gives students practices at identifying <span class="hlt">plate</span> boundaries and allows them to explore lesser known tectonically active regions.</p> <div class="credits"> <p class="dwt_author">Kerwin, Michael</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_12");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> 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showDiv("page_15");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">261</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014E%26PSL.385..122V"> <span id="translatedtitle">Geodetic evidence for low coupling on the Hellenic subduction <span class="hlt">plate</span> interface</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We develop a block model for the Aegean and surrounding areas, constrained by Global Positioning System (GPS), in order to investigate the degree of coupling on the Hellenic subduction interface (i.e., the fraction of the motion across the <span class="hlt">plate</span> boundary accommodated by elastic strain accumulation). We use previously published models, and seismicity to define the geometry of the interface separating the down-going Nubian slab from the <span class="hlt">overriding</span> Aegean. This model provides a good fit to the GPS observations; for the ˜200,000 km2 Aegean block the wrms of the residual velocities is 1.4 mm/yr for 80 GPS velocity estimates, approximately the 95% level of the GPS velocity uncertainties. We investigate the degree of coupling on the seismically active <span class="hlt">plate</span> interface, the Hellenic trench splay fault (believed to be the source of the 365 AD Great Crete Earthquake and Tsunami), and the Kephalonia transform fault by comparing the modeled GPS residual velocity field for a range of coupling values. The GPS observations are almost insensitive to coupling on the Kephalonia transform fault, because of the vertical dip of the fault that creates interseismic deformation only close to the fault where few GPS sites exist. The absence of resolvable shortening of the leading edge of the Aegean <span class="hlt">Plate</span> precludes coupling of more than 0.2 (20% of the full Nubia-Aegean convergence rate) on the modeled <span class="hlt">plate</span> interface. Because of the shallow dip of the <span class="hlt">plate</span> interface and trench splay fault, and high rate of convergence, if these boundaries were fully coupled, high elastic strain rates would be expected to extend well into the <span class="hlt">overriding</span> Aegean <span class="hlt">plate</span>. Based on our preferred value for the degree of coupling (0.1), and assuming characteristic earthquake behavior, we estimate a recurrence time for great earthquakes with slip similar to that for the 365 Crete event of 5700-8300 yr, consistent with the absence of subsequent great earthquakes on this segment of the subduction zone.</p> <div class="credits"> <p class="dwt_author">Vernant, Philippe; Reilinger, Robert; McClusky, Simon</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">262</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19880020846&hterms=Continental+Crust+Composition+Evolution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DContinental%2BCrust%253A%2BComposition%2BEvolution."> <span id="translatedtitle">Thermal models pertaining to <span class="hlt">continental</span> growth</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Thermal models are important to understanding <span class="hlt">continental</span> growth as the genesis, stabilization, and possible recycling of <span class="hlt">continental</span> crust are closely related to the tectonic processes of the earth which are driven primarily by heat. The thermal energy budget of the earth was slowly decreasing since core formation, and thus the energy driving the terrestrial tectonic engine was decreasing. This fundamental observation was used to develop a logic tree defining the options for <span class="hlt">continental</span> growth throughout earth history.</p> <div class="credits"> <p class="dwt_author">Morgan, Paul; Ashwal, Lew</p> <p class="dwt_publisher"></p> <p class="publishDate">1988-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">263</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/FR-2011-01-18/pdf/2011-883.pdf"> <span id="translatedtitle">76 FR 2919 - Outer <span class="hlt">Continental</span> Shelf Official Protraction Diagram and Supplemental Official Outer <span class="hlt">Continental</span>...</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013</a></p> <p class="result-summary">...Supplemental Official Outer <span class="hlt">Continental</span> Shelf Block Diagrams AGENCY: Bureau of Ocean Energy...Supplemental Official Outer <span class="hlt">Continental</span> Shelf Block Diagrams...Diagram (OPD) and Supplemental Official OCS Block Diagrams (SOBDs) located in the...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-18</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">264</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1997AREPS..25..279W"> <span id="translatedtitle">Hydrological Modeling of <span class="hlt">Continental</span>-Scale Basins</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Hydrological models at <span class="hlt">continental</span> scales are traditionally used for water resources planning. However, <span class="hlt">continental</span>-scale hydrological models may be useful in assessing the impacts from future climate change on catchment hydrology and water resources or from human activity on hydrology and biogeochemical cycles at large scales. Development of regional-scale terrestrial hydrological models will further our understanding of the Earth's water cycle. <span class="hlt">Continental</span> scales allow for better understanding of the geographic distribution of land-atmospheric moisture fluxes, improved water management at <span class="hlt">continental</span> scales, better quantification of the impact of human activity and climate change on the water cycle, and improved simulation of weather and climate.</p> <div class="credits"> <p class="dwt_author">Wood, Eric F.; Lettenmaier, Dennis; Liang, Xu; Nijssen, Bart; Wetzel, Suzanne W.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">265</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003AGUFM.S41F..03S"> <span id="translatedtitle">Cenozoic History of the Interaction of the Nazca and South America <span class="hlt">Plates</span>: a Numerical Study for the Central Andes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Large-scale tectonic shortening in the Central Andes and Neogene uplift of the Altiplano-Puna plateau was preceeded by Eocene uplift of the Chilean Precordillera and subsequent rapid eastward expansion of compressional deformation between 40-30 Ma, by the marked decline of the magmatic arc activity at 33-23 Ma and by a strong increase of the convergence rate between the Nazca and South America (SA) <span class="hlt">plates</span> at 25-20 Ma. We use 2-D numerical thermo-mechanical modelling of the interaction of the subducting Nazca <span class="hlt">plate</span> and the <span class="hlt">overriding</span> SA <span class="hlt">plate</span> during the last 40 Myr to explore the possible relation between these events. The model employs realistic visco-elasto-plastic rheology, shear heating and phase transformations. The interface between the slab and the upper <span class="hlt">plate</span> is modelled as a few km thick subduction channel with low-friction Mohr-Coulomb rheology, the friction coefficient being the major modelling parameter. We show that variation of this parameter in the plausible range of 0.02-0.07 may dramatically change stress and strain fields in the upper <span class="hlt">plate</span>. Preliminary modelling results show that at friction coefficient of 0.05-0.07 the stress field in the <span class="hlt">overriding</span> <span class="hlt">plate</span> must have changed from minor extension to strong compression in response to the increase of the convergence rate. This could cause extensive tectonic shortening of the <span class="hlt">overriding</span> <span class="hlt">plate</span> if it had been rheologicaly weakened beforehand. We quantitatively explore possible mechanisms of such weakening, and currently favour the following scenario yielding the best fit. At ca. 40 Ma an oceanic plateau entered the trench; its motion below the SA <span class="hlt">plate</span> caused eastward expansion of compressional deformation at 40-30 Ma followed by flattening of the slab and cessation of volcanism. After the plateau was subducted at 25-20 Ma, the slab retreated which intensified the asthenospheric corner flow. This event coincided temporally with the acceleration of the convergence rate inducing increased compression in the upper <span class="hlt">plate</span> where the subduction-channel friction coefficient was relatively high. After some 10 Myr, required for the corner flow to heat and hence weaken the lithosphere of the upper <span class="hlt">plate</span>, the latter failed and tectonic shortening accelerated despite slowdown of convergence rate.</p> <div class="credits"> <p class="dwt_author">Sobolev, S. V.; Babeyko, A. Y.; Oncken, O.; Vietor, T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">266</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002AGUFM.T62C1317B"> <span id="translatedtitle">New Insight Into the Crustal Structure of the <span class="hlt">Continental</span> Margin offshore NW Sabah/Borneo</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">continental</span> margin offshore NW Sabah/Borneo (Malaysia) has been investigated with reflection and refraction seismics, magnetics, and gravity during the recent cruise BGR01-POPSCOMS. A total of 4000 km of geophysical profiles has been acquired, thereof 2900 km with reflection seismics. The focus of investigations was on the deep water areas. The margin looks like a typical accretionary margin and was presumably formed during the subduction of a proto South China Sea. Presently, no horizontal movements between the two <span class="hlt">plates</span> are being observed. Like in major parts of the South China Sea, the area seaward of the Sabah Trough consists of extended <span class="hlt">continental</span> lithosphere which is characterised by a pattern of rotated fault blocks and half grabens and a carbonate platform of Early Oligocene to Early Miocene age. We found evidence that the <span class="hlt">continental</span> crust also underlies the Sabah Trough and the adjacent <span class="hlt">continental</span> slope, a fact that raises many questions about the tectonic history and development of this margin. The tectonic pattern of the Dangerous Grounds' extended <span class="hlt">continental</span> crust can be traced a long way landward of the Sabah Trough beneath the sedimentary succession of the upper <span class="hlt">plate</span>. The magnetic anomalies which are dominated by the magnetic signatures of relatively young volcanic features also continue under the <span class="hlt">continental</span> slope. The sedimentary rocks of the upper <span class="hlt">plate</span>, in contrast, seem to generate hardly any magnetic anomalies. Based on the new data we propose the following scenario for the development of the NW Sabah <span class="hlt">continental</span> margin: Seafloor spreading in the present South China Sea started at about 30 Ma in the Late Oligocene. The spreading process separated the Dangerous Grounds area from the SE Asian continent and ceased in late Early Miocene when the oceanic crust of the proto South China Sea was fully subducted in eastward direction along the Borneo-Palawan Trough. During Lower and/or Middle Miocene, Borneo rotated counterclockwise and was thrusted onto the edge of the rifted <span class="hlt">continental</span> block of the Dangerous Grounds. The subducted oceanic crust of the proto South China Sea must today be located below the Eastern part of Sabah and not along the present NW Sabah Trough.</p> <div class="credits"> <p class="dwt_author">Barckhausen, U.; Franke, D.; Behain, D.; Meyer, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">267</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003JGRB..108.2328A"> <span id="translatedtitle">Seismic imaging of a convergent <span class="hlt">continental</span> margin and plateau in the central Andes (Andean <span class="hlt">Continental</span> Research Project 1996 (ANCORP'96))</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A 400-km-long seismic reflection profile (Andean <span class="hlt">Continental</span> Research Project 1996 (ANCORP'96)) and integrated geophysical experiments (wide-angle seismology, passive seismology, gravity, and magnetotelluric depth sounding) across the central Andes (21°S) observed subduction of the Nazca <span class="hlt">plate</span> under the South American continent. An east dipping reflector (Nazca Reflector) is linked to the down going oceanic crust and shows increasing downdip intensity before gradual breakdown below 80 km. We interpret parts of the Nazca Reflector as a fluid trap located at the front of recent hydration and shearing of the mantle, the fluids being supplied by dehydration of the oceanic <span class="hlt">plate</span>. Patches of bright (Quebrada Blanca Bright Spot) to more diffuse reflectivity underlie the plateau domain at 15-30 km depth. This reflectivity is associated with a low-velocity zone, P to S wave conversions, the upper limits of high conductivity and high V p /V s ratios, and to the occurrence of Neogene volcanic rocks at surface. We interpret this feature as evidence of widespread partial melting of the plateau crust causing decoupling of the upper and lower crust during Neogene shortening and plateau growth. The imaging properties of the <span class="hlt">continental</span> Moho beneath the Andes indicate a broad transitional character of the crust-mantle boundary owing to active processes like hydration of mantle rocks (in the cooler parts of the <span class="hlt">plate</span> margin system), magmatic underplating and intraplating under and into the lowermost crust, mechanical instability at Moho, etc. Hence all first-order features appear to be related to fluid-assisted processes in a subduction setting.</p> <div class="credits"> <p class="dwt_author">ANCORP Working Group,</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">268</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003JGRB..108.2328O"> <span id="translatedtitle">Seismic imaging of a convergent <span class="hlt">continental</span> margin and plateau in the central Andes (Andean <span class="hlt">Continental</span> Research Project 1996 (ANCORP'96))</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A 400-km-long seismic reflection profile (Andean <span class="hlt">Continental</span> Research Project 1996 (ANCORP'96)) and integrated geophysical experiments (wide-angle seismology, passive seismology, gravity, and magnetotelluric depth sounding) across the central Andes (21°S) observed subduction of the Nazca <span class="hlt">plate</span> under the South American continent. An east dipping reflector (Nazca Reflector) is linked to the down going oceanic crust and shows increasing downdip intensity before gradual breakdown below 80 km. We interpret parts of the Nazca Reflector as a fluid trap located at the front of recent hydration and shearing of the mantle, the fluids being supplied by dehydration of the oceanic <span class="hlt">plate</span>. Patches of bright (Quebrada Blanca Bright Spot) to more diffuse reflectivity underlie the plateau domain at 15-30 km depth. This reflectivity is associated with a low-velocity zone, P to S wave conversions, the upper limits of high conductivity and high Vp/Vs ratios, and to the occurrence of Neogene volcanic rocks at surface. We interpret this feature as evidence of widespread partial melting of the plateau crust causing decoupling of the upper and lower crust during Neogene shortening and plateau growth. The imaging properties of the <span class="hlt">continental</span> Moho beneath the Andes indicate a broad transitional character of the crust-mantle boundary owing to active processes like hydration of mantle rocks (in the cooler parts of the <span class="hlt">plate</span> margin system), magmatic underplating and intraplating under and into the lowermost crust, mechanical instability at Moho, etc. Hence all first-order features appear to be related to fluid-assisted processes in a subduction setting.</p> <div class="credits"> <p class="dwt_author">Oncken, O.; Asch, G.; Haberland, C.; Metchie, J.; Sobolev, S.; Stiller, M.; Yuan, X.; Brasse, H.; Buske, S.; Giese, P.; GöRze, H.-J.; Lueth, S.; Scheuber, E.; Shapiro, S.; Wigger, P.; Yoon, M.-K.; Bravo, P.; Vieytes, H.; Chong, G.; Gonzales, G.; Wilke, H.-G.; Lüschen, E.; Martinez, E.; RöSsling, R.; Ricaldi, E.; Rietbrock, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">269</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011GGG....12.5S32H"> <span id="translatedtitle">Submarine slope failures along the convergent <span class="hlt">continental</span> margin of the Middle America Trench</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present the first comprehensive study of mass wasting processes in the <span class="hlt">continental</span> slope of a convergent margin of a subduction zone where tectonic processes are dominated by subduction erosion. We have used multibeam bathymetry along ˜1300 km of the Middle America Trench of the Central America Subduction Zone and deep-towed side-scan sonar data. We found abundant evidence of large-scale slope failures that were mostly previously unmapped. The features are classified into a variety of slope failure types, creating an inventory of 147 slope failure structures. Their type distribution and abundance define a segmentation of the <span class="hlt">continental</span> slope in six sectors. The segmentation in slope stability processes does not appear to be related to slope preconditioning due to changes in physical properties of sediment, presence/absence of gas hydrates, or apparent changes in the hydrogeological system. The segmentation appears to be better explained by changes in slope preconditioning due to variations in tectonic processes. The region is an optimal setting to study how tectonic processes related to variations in intensity of subduction erosion and changes in relief of the underthrusting <span class="hlt">plate</span> affect mass wasting processes of the <span class="hlt">continental</span> slope. The largest slope failures occur offshore Costa Rica. There, subducting ridges and seamounts produce failures with up to hundreds of meters high headwalls, with detachment planes that penetrate deep into the <span class="hlt">continental</span> margin, in some cases reaching the <span class="hlt">plate</span> boundary. Offshore northern Costa Rica a smooth oceanic seafloor underthrusts the least disturbed <span class="hlt">continental</span> slope. Offshore Nicaragua, the ocean <span class="hlt">plate</span> is ornamented with smaller seamounts and horst and graben topography of variable intensity. Here mass wasting structures are numerous and comparatively smaller, but when combined, they affect a large part of the margin segment. Farther north, offshore El Salvador and Guatemala the downgoing <span class="hlt">plate</span> has no large seamounts but well-defined horst and graben topography. Off El Salvador slope failure is least developed and mainly occurs in the uppermost <span class="hlt">continental</span> slope at canyon walls. Off Guatemala mass wasting is abundant and possibly related to normal faulting across the slope. Collapse in the wake of subducting ocean <span class="hlt">plate</span> topography is a likely failure trigger of slumps. Rapid oversteepening above subducting relief may trigger translational slides in the middle Nicaraguan upper Costa Rican slope. Earthquake shaking may be a trigger, but we interpret that slope failure rate is lower than recurrence time of large earthquakes in the region. Generally, our analysis indicates that the importance of mass wasting processes in the evolution of margins dominated by subduction erosion and its role in sediment dynamics may have been previously underestimated.</p> <div class="credits"> <p class="dwt_author">Harders, Rieka; Ranero, CéSar R.; Weinrebe, Wilhelm; Behrmann, Jan H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">270</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5964066"> <span id="translatedtitle">Neogene rotations and quasicontinuous deformation of the Pacific Northwest <span class="hlt">continental</span> margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Paleomagnetically determined rotations about vertical axes of 15 to 12 Ma flows of the Miocene Columbia River Basalt Group of Oregon and Washington decrease smoothly with distance from the <span class="hlt">plate</span> margin, consistent with a simple physical model for <span class="hlt">continental</span> deformation that assumes the lithosphere behaves as a thin layer of fluid. The average rate of northward translation of the <span class="hlt">continental</span> margin since 15 Ma calculated from the rotations, using this model, is about 15 mm/year, which suggests that much of the tangential motion between the Juan de Fuca and North American <span class="hlt">plates</span> since middle Miocene time has been taken up by deformation of North America. The fluid-like character of the large-scale deformation implies that the brittle upper crust follows the motions of the deeper parts of the lithosphere.</p> <div class="credits"> <p class="dwt_author">England, P. (Oxford Univ. (England)); Wells, R.E. (Geological Survey, Menlo Park, CA (United States))</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">271</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007PEPI..160..124G"> <span id="translatedtitle">Intrusion of ultramafic magmatic bodies into the <span class="hlt">continental</span> crust: Numerical simulation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Intrusions of ultramafic bodies into the lower density <span class="hlt">continental</span> crust are documented for a large variety of tectonic settings spanning <span class="hlt">continental</span> shields, rift systems, collision orogens and magmatic arcs. The intriguing point is that these intrusive bodies have a density higher by 300-500 kg m -3 than host rocks. Resolving this paradox requires an understanding of the emplacement mechanism. We have employed finite differences and marker-in-cell techniques to carry out a 2D modeling study of intrusion of partly crystallized ultramafic magma from sublithospheric depth to the crust through a pre-existing magmatic channel. By systematically varying the model parameters we document variations in intrusion dynamics and geometry that range from funnel- and finger-shaped bodies (pipes, dikes) to deep seated balloon-shaped intrusions and flattened shallow magmatic sills. Emplacement of ultramafic bodies in the crust lasts from a few kyr to several hundreds kyr depending mainly on the viscosity of the intruding, partly crystallized magma. The positive buoyancy of the sublithospheric magma compared to the <span class="hlt">overriding</span>, colder mantle lithosphere drives intrusion while the crustal rheology controls the final location and the shape of the ultramafic body. Relatively cold elasto-plastic crust ( TMoho = 400 °C) promotes a strong upward propagation of magma due to the significant decrease of plastic strength of the crust with decreasing confining pressure. Emplacement in this case is controlled by crustal faulting and subsequent block displacements. Warmer crust ( TMoho = 600 °C) triggers lateral spreading of magma above the Moho, with emplacement being accommodated by coeval viscous deformation of the lower crust and fault tectonics in the upper crust. Strong effects of magma emplacement on surface topography are also documented. Emplacement of high-density, ultramafic magma into low-density rocks is a stable mechanism for a wide range of model parameters that match geological settings in which partially molten mafic-ultramafic rocks are generated below the lithosphere. We expect this process to be particularly active beneath subduction-related magmatic arcs where huge volumes of partially molten rocks produced from hydrous cold plume activity accumulate below the <span class="hlt">overriding</span> lithosphere.</p> <div class="credits"> <p class="dwt_author">Gerya, Taras V.; Burg, Jean-Pierre</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">272</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014P%26SS...98....5H"> <span id="translatedtitle">Biotic vs. abiotic Earth: A model for mantle hydration and <span class="hlt">continental</span> coverage</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The origin and evolution of life has undoubtedly had a major impact on the evolution of Earth's oceans and atmosphere. Recent studies have suggested that bioactivity may have had an even deeper impact and may have caused a change in the redox-state of the mantle and provided a path for the formation of continents. We here present a numerical model that assumes that bioactivity increases the <span class="hlt">continental</span> weathering rate and that relates the sedimentation rate to the growth of continents and to the hydration of the mantle using elements of <span class="hlt">plate</span> tectonics and mantle convection. The link between these factors is provided by assuming that an increase of the thickness of the sedimentary layer of low permeability on top of a subducting oceanic slab will reduce its dewatering upon subduction. This in turn leads to a greater availability of water in the source region of andesitic partial melt, resulting in an enhanced rate of <span class="hlt">continental</span> crust production, and to an increased regassing rate of the mantle. The mantle in turn responds by reducing the mantle viscosity while increasing the convective circulation rate, degassing rate and <span class="hlt">plate</span> speed. We use parameters that are observed for the present Earth and gauge uncertain parameters such that the present day <span class="hlt">continental</span> surface area and mantle water concentration can be obtained. Our steady state results show two stable fixed points in a phase plane defined by the fractional <span class="hlt">continental</span> surface area and the water concentration in the mantle, one of them pertaining to a wet mantle and the <span class="hlt">continental</span> surface area of the present day Earth, and the other to a dry mantle and a small <span class="hlt">continental</span> surface area. When the sedimentation rate is reduced, both fixed points move and the area of attraction of the latter fixed point increases systematically. We conclude that if the presence of life has increased the <span class="hlt">continental</span> weathering rate, as is widely believed, and led to the observables of a wet mantle and a <span class="hlt">continental</span> surface coverage of roughly 40%, an abiotic Earth would likely have evolved toward a dry mantle with a small <span class="hlt">continental</span> surface area instead.</p> <div class="credits"> <p class="dwt_author">Höning, Dennis; Hansen-Goos, Hendrik; Airo, Alessandro; Spohn, Tilman</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">273</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009E%26PSL.279...44W"> <span id="translatedtitle"><span class="hlt">Continental</span> geochemical signatures in dacites from Iceland and implications for models of early Archaean crust formation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Whether early Archaean felsic crust was formed by processes related to <span class="hlt">plate</span> subduction or melting of thick basaltic plateaus is vividly debated. Ultimately, the discussion hinges on the question of how Archaean felsic crust has obtained its distinct chemical traits. Here we report chemical and isotopic data for a suite of Cenozoic felsic volcanic rocks from Iceland. The samples exhibit the key-chemical characteristics of early Archaean felsic <span class="hlt">continental</span> crust such as calc-alkaline composition, strong enrichment in Na relative to K, high Pb/Ce, La/Nb, and Ta/Nb ratios. Involvement of pre-existing <span class="hlt">continental</span> lithosphere in the petrogenesis of the samples can be excluded, because their 207Pb/ 204Pb and 206Pb/ 204Pb ratios plot well within the range of Iceland basalts. Model calculations suggest that the chemical characteristics were produced by high-pressure partial melting of basaltic lower crust followed by fractional crystallisation of amphibole, plagioclase, and ilmenite. These findings demonstrate that <span class="hlt">plate</span> subduction and melting of subduction-modified mantle or lithosphere are not necessarily required to produce the key-chemical signatures of <span class="hlt">continental</span> crust. Hence, the calc-alkaline dacites provide intriguing support for early Archaean <span class="hlt">continental</span> crust formation by melting of thick mafic plateaus.</p> <div class="credits"> <p class="dwt_author">Willbold, Matthias; Hegner, Ernst; Stracke, Andreas; Rocholl, Alexander</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">274</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6812P"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonic controls geomagnetic reversal frequency</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The discovery of the reversals of Earth's magnetic field and the description of <span class="hlt">plate</span> tectonics are two of the main breakthroughs in geophysics in the 20th century. We claim that these two phenomena are correlated and that <span class="hlt">plate</span> tectonics controls long-term changes in geomagnetic reversals frequency. More precisely, we show that geological periods characterized by an asymmetrical distribution of the continents with respect to the equator generate periods of high reversal frequency. We infer that the distribution and symmetry of mantle structures driving <span class="hlt">continental</span> motions at the surface influence the equatorial symmetry of the flow within the core and thus changes the coupling between the dipolar and quadrupolar modes which controls the occurrence of reversals.</p> <div class="credits"> <p class="dwt_author">Petrelis, Francois; Besse, Jean; Valet, Jean-Pierre</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">275</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EPSC....8..947H"> <span id="translatedtitle">Considering bioactivity in modelling <span class="hlt">continental</span> growth and the Earth's evolution</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The complexity of planetary evolution increases with the number of interacting reservoirs. On Earth, even the biosphere is speculated to interact with the interior. It has been argued (e.g., Rosing et al. 2006; Sleep et al, 2012) that the formation of continents could be a consequence of bioactivity harvesting solar energy through photosynthesis to help build the continents and that the mantle should carry a chemical biosignature. Through <span class="hlt">plate</span> tectonics, the surface biosphere can impact deep subduction zone processes and the interior of the Earth. Subducted sediments are particularly important, because they influence the Earth's interior in several ways, and in turn are strongly influenced by the Earth's biosphere. In our model, we use the assumption that a thick sedimentary layer of low permeability on top of the subducting oceanic crust, caused by a biologically enhanced weathering rate, can suppress shallow dewatering. This in turn leads to greater vailability of water in the source region of andesitic partial melt, resulting in an enhanced rate of <span class="hlt">continental</span> production and regassing rate into the mantle. Our model includes (i) mantle convection, (ii) <span class="hlt">continental</span> erosion and production, and (iii) mantle water degassing at mid-ocean ridges and regassing at subduction zones. The mantle viscosity of our model depends on (i) the mantle water concentration and (ii) the mantle temperature, whose time dependency is given by radioactive decay of isotopes in the Earth's mantle. Boundary layer theory yields the speed of convection and the water outgassing rate of the Earth's mantle. Our results indicate that present day values of <span class="hlt">continental</span> surface area and water content of the Earth's mantle represent an attractor in a phase plane spanned by both parameters. We show that the biologic enhancement of the <span class="hlt">continental</span> erosion rate is important for the system to reach this fixed point. An abiotic Earth tends to reach an alternative stable fixed point with a smaller <span class="hlt">continental</span> surface area and dryer mantle. The origin and evolution of life on Earth might be responsible for the rise of continents 3.5 billion years ago.</p> <div class="credits"> <p class="dwt_author">Höning, D.; Spohn, T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">276</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUFMOS41A..06M"> <span id="translatedtitle">Warm-water flow above deep water methane hydrates at an Arctic <span class="hlt">continental</span> margin - A view on climate impacts</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We detected geophysical evidence for the base of the gas hydrate stability zone (GHSZ) in form of a bottom simulating reflector (BSR) at mid slope of the <span class="hlt">continental</span> margin of NW-Svalbard and collected acoustic and video-footage evidence for major methane release at the shelf (flares). Flares are acoustic expressions of methane bubbles emanating from the seabed. Warming of upper ocean water masses that impinge on sediments of the upper <span class="hlt">continental</span> slope may reduce the methane hydrate stability zone. As a result, it can cause melting of gas hydrates, overpressure build up, abrupt releases of methane from the seabed, and geohazards. However, the warm-water core of the W-Spitsbergen current does not intercept with the <span class="hlt">continental</span> slope (July 2009). There is also no evidence for a BSR pinch out on the upper <span class="hlt">continental</span> slope. Accordingly, warming of the W-Spitsbergen current at this location may have less or no effects on the release of methane from the seabed by reducing the GHSZ. Alternatively, fluids may be released by reactivation of faults due to seismic activity (< 7 magnitude) around Svalbard. Earthquakes occur frequently along the divergent <span class="hlt">plate</span> boundary and the nearby <span class="hlt">continental</span>-ocean boundary (COB) of the W-Svalbard <span class="hlt">continental</span> margin. We therefore consider two major ways to release fluids: 1) an upward migration of free gas beneath the GHSZ towards the projected outcrop zone at the upper <span class="hlt">continental</span> margin, and/ or 2) a migration and release of methane at active fault zones.</p> <div class="credits"> <p class="dwt_author">Mienert, J.; Bünz, S.; Greinert, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">277</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=PB223979"> <span id="translatedtitle">Sediments of the East Atlantic <span class="hlt">Continental</span> Margin.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This is a preliminary report on the study of sediments of the East Atlantic <span class="hlt">Continental</span> Margin. The location of sediment samples from the northern and equatorial portions of the western African <span class="hlt">continental</span> shelf and upper slope are presented, along with a...</p> <div class="credits"> <p class="dwt_author">J. D. Milliman</p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">278</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.gpo.gov:80/fdsys/pkg/FR-2013-05-29/pdf/2013-12679.pdf"> <span id="translatedtitle">78 FR 32183 - Importation of Avocados From <span class="hlt">Continental</span> Spain</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013</a></p> <p class="result-summary">...Importation of Avocados From <span class="hlt">Continental</span> Spain AGENCY: Animal and Plant Health Inspection...importation of avocados from <span class="hlt">continental</span> Spain (excluding the Balearic Islands and Canary...importation of avocados from <span class="hlt">continental</span> Spain (excluding the Balearic Islands and...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-29</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">279</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://kidshealth.org/teen/food_fitness/nutrition/pyramid.html"> <span id="translatedtitle">My <span class="hlt">Plate</span> Food Guide</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://medlineplus.gov/">MedlinePLUS</a></p> <p class="result-summary">... you won't get the best nutrition. 1. Vegetables The vegetable portion of My<span class="hlt">Plate</span> is shown in green. It's ... the largest sections on the <span class="hlt">plate</span>. That's because vegetables provide many of the vitamins and minerals we ...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">280</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.teachersdomain.org/resources/ess05/sci/ess/earthsys/wegener2/assets/ess05_vid_wegener2/ess05_vid_wegener2_56_mov.html"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics: Further Evidence</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The representation depicts the spreading of the sea floor along the mid-ocean ridges. The resource generally describes the theory of <span class="hlt">plate</span> tectonics, including the movement of <span class="hlt">plates</span> with regard to one another.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_13");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> 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showDiv("page_16");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">281</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://learningcenter.nsta.org/product_detail.aspx?id=10.2505/15/ERNASA10_0180"> <span id="translatedtitle">External Resource: <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This Windows to the Universe interactive webpage connects students to the study and understanding of <span class="hlt">plate</span> tectonics, the main force that shapes our planets surface. Topics: <span class="hlt">plate</span> tectonics, lithosphere, subduction zones, faults, ridges.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1900-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">282</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/969705"> <span id="translatedtitle">Earth's Decelerating Tectonic <span class="hlt">Plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Space geodetic and oceanic magnetic anomaly constraints on tectonic <span class="hlt">plate</span> motions are employed to determine a new global map of present-day rates of change of <span class="hlt">plate</span> velocities. This map shows that Earth's largest <span class="hlt">plate</span>, the Pacific, is presently decelerating along with several other <span class="hlt">plates</span> in the Pacific and Indo-Atlantic hemispheres. These <span class="hlt">plate</span> decelerations contribute to an overall, globally averaged slowdown in tectonic <span class="hlt">plate</span> speeds. The map of <span class="hlt">plate</span> decelerations provides new and unique constraints on the dynamics of time-dependent convection in Earth's mantle. We employ a recently developed convection model constrained by seismic, geodynamic and mineral physics data to show that time-dependent changes in mantle buoyancy forces can explain the deceleration of the major <span class="hlt">plates</span> in the Pacific and Indo-Atlantic hemispheres.</p> <div class="credits"> <p class="dwt_author">Forte, A M; Moucha, R; Rowley, D B; Quere, S; Mitrovica, J X; Simmons, N A; Grand, S P</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-08-22</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">283</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ig.utexas.edu/research/projects/plates/index.htm"> <span id="translatedtitle">The <span class="hlt">PLATES</span> Project</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This is the web page for <span class="hlt">PLATES</span>, a program of research into <span class="hlt">plate</span> tectonic and geologic reconstructions at the University of Texas at Austin Institute for Geophysics. The page contains links to a brief overview of <span class="hlt">plate</span> tectonics and <span class="hlt">plate</span> reconstructions using the <span class="hlt">PLATES</span> Project's global <span class="hlt">plate</span> reconstruction model, in addition to movies in the format of powerpoint animations which can be downloaded for later use. Models are shown on the evolution of the earth's oceans and the movement of the earth's tectonic <span class="hlt">plates</span> from the Late Precambrian through the present day, reconstructing (i.e. "predicting") geological environments through geologic history. Maps of the following can be accessed: late Neo-Proterozoic, Silurian, early Jurassic, early Cretaceous, Cretaceous-Tertiary Boundary, and Oligocene. Movies are available on the following subjects: global <span class="hlt">plate</span> motion, Jurassic to present day, opening of the Indian Ocean, and tectonic evolution of the Arctic region.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">284</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.8439K"> <span id="translatedtitle">Evolution of Oxidative <span class="hlt">Continental</span> Weathering</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Great Oxidation Event (GOE) is currently viewed as a protracted process during which atmospheric oxygen levels increased above 10-5 times the present atmospheric level. This value is based on the loss of sulphur isotope mass independent fractionation (S-MIF) from the rock record, beginning at 2.45 Ga and disappearing by 2.32 Ga. However, a number of recent papers have pushed back the timing for oxidative <span class="hlt">continental</span> weathering, and by extension, the onset of atmospheric oxygenation several hundreds of million years earlier despite the presence of S-MIF (e.g., Crowe et al., 2013). This apparent discrepancy can, in part, be resolved by the suggestion that recycling of older sedimentary sulphur bearing S-MIF might have led to this signal's persistence in the rock record for some time after atmospheric oxygenation (Reinhard et al., 2013). Here we suggest another possibility, that the earliest oxidative weathering reactions occurred in environments at profound redox disequilibrium with the atmosphere, such as biological soil crusts, riverbed and estuarine sediments, and lacustrine microbial mats. We calculate that the rate of O2 production via oxygenic photosynthesis in these terrestrial microbial ecosystems provides largely sufficient oxidizing potential to mobilise sulphate and a number of redox-sensitive trace metals from land to the oceans while the atmosphere itself remained anoxic with its attendant S-MIF signature. These findings reconcile geochemical signatures in the rock record for the earliest oxidative <span class="hlt">continental</span> weathering with the history of atmospheric sulphur chemistry, and demonstrate the plausible antiquity of a terrestrial biosphere populated by cyanobacteria. Crowe, S.A., Dossing, L.N., Beukes, N.J., Bau, M., Kruger, S.J., Frei, R. & Canfield, D.E. Atmospheric oxygenation three billion years ago. Nature 501, 535-539 (2013). Reinhard, C.T., Planavsky, N.J. & Lyons, T.W. Long-term sedimentary recycling of rare sulphur isotope anomalies. Nature 497, 100-104 (2013).</p> <div class="credits"> <p class="dwt_author">Konhauser, Kurt; Lalonde, Stefan</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">285</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.T33J..07B"> <span id="translatedtitle">An Analysis of Wilson Cycle <span class="hlt">Plate</span> Margins</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Wilson Cycle theory that oceans close and open along the same suture is a powerful concept in analyses of ancient <span class="hlt">plate</span> tectonics. It implies that collision zones are structures that are able to localize extensional deformation for long times after the collision has waned. However, some sutures are seemingly never reactivated and already Tuzo Wilson recognized that Atlantic break-up did not follow the precise line of previous junction. We have reviewed margin pairs around the Atlantic and Indian Oceans with the aim to evaluate the extent to which oceanic opening used former sutures, summarize delay times between collision and break-up, and analyze the role of mantle plumes in <span class="hlt">continental</span> break-up. We aid our analyses with <span class="hlt">plate</span> tectonic reconstructions using GPlates (www.gplates.org). Although at first sight opening of the North Atlantic Ocean largely seems to follow the Iapetus and Rheic sutures, a closer look reveals deviations. For example, Atlantic opening did not utilize the Iapetus suture in Great Britain and rather than opening along the younger Rheic suture north of Florida, break-up occurred along the older Pan-African structures south of Florida. We find that today's oceanic Charlie Gibbs Fracture Zone, between Ireland and Newfoundland, is aligned with the Iapetus suture. We speculate therefore that in this region the Iapetus suture was reactivated as a transform fault. As others before us, we find no correlation of suture and break-up age. Often <span class="hlt">continental</span> break-up occurs some hundreds of Myrs after collision, but it may also take over 1000 Myr, as for example for Australia - Antarctica and Congo - São Francisco. This places serious constraints on potential collision zone weakening mechanisms. Several studies have pointed to a link between <span class="hlt">continental</span> break-up and large-scale mantle upwellings. It is, however, much debated whether plumes use existing rifts as a pathway, or whether plumes play an active role in causing rifting. We find a positive correlation between break-up age and plume age, which we interpret to indicate that plumes can aid the factual <span class="hlt">continental</span> break-up. However, plumes may have been guided towards the rift for margins that experienced a long rift history (e.g., Norway-Greenland), to then trigger the break-up. This could offer a partial reconciliation in the debate of a passive or active role for mantle plumes in <span class="hlt">continental</span> break-up.</p> <div class="credits"> <p class="dwt_author">Buiter, S.; Torsvik, T. H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">286</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.1198A"> <span id="translatedtitle">Cretaceous high-pressure metamorphic belts of the Central Pontides (northern Turkey): pre-collisional Pacific-type accretionary <span class="hlt">continental</span> growth of Laurasian Margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Cretaceous blueschist-facies metamorphic rocks crop out widely in the central part of the Pontides, an east-west trending mountain belt in northern Turkey. They comprise an accretionary wedge along to the southern Laurasian active <span class="hlt">continental</span> margin and predate the opening of Black Sea basin. From North to South, the wedge consists of a low grade metaflysch unit with marble, Na-amphibole-bearing metabasite and serpentinite blocks. An extensional shear zone separates the accreted distal terrigenous sediments from HP/LT micaschists and metabasites of oceanic origin, known as Domuzda? Complex. The shear zone reaches up to one km in thickness and consists of tectonic slices of serpentinite, metabasite, marble, phyllite and micaschist with top to the NW sense of shear. The Domuzda? Complex predominantly consists of carbonaceous micaschist and metabasite with serpentinite, and minor metachert, marble and metagabbro. Metabasites consist mainly of epidote-blueschists sometimes with garnet. Fresh lawsonite-blueschists are found as blocks within the shear zone. Peak metamorphic assemblages in the micaschists are chloritoid-glaucophane and garnet-chloritoid-glaucophane-lawsonite in addition to phengite, paragonite, quartz, chlorite and rutile (P: 17 ± 1 Kbar, T: 390-450 °C). To the south, lithologies change slightly, with metabasite and thick, pale marble with few metachert and metapelitic horizons. The degree of metamorphism also changes. The metabasites range from high-pressure upper-greenschist facies with growth of sodic-amphibole to lower greenschist without any HP index mineral, suggesting a general decrease in pressure toward south within the prism. While Domuzda? Complex represents deep-seated underplated oceanic sediments and basalts, the carbonate-rich southern parts can be interpreted as seamounts integrated into the accretionary prism. Ar/Ar dating on phengite separates both from terrigenous and oceanic metasediments give consistent plateau ages of 100 ± 2 Ma. One of the Cld-micaschist, exposed to the South, gives a 92 ± 2 Ma age. This documents a southward younging of metamorphism within the accretionary prism. A mid-Jurassic (160 Ma) age, previously reported from a micaschist in the southern part of Domuzda? Complex, is also supported in this study. These rocks however differ from the Cretaceous HP unit both in lithology and degree of metamorphism (P: 10 ± 2 Kbar, T: 620 ± 30°C; Okay et al. 2013). It is not clear whether these rocks indicate episodic subduction process or represent tectonically emplaced slivers of the <span class="hlt">overriding</span> <span class="hlt">plate</span> which has widespread Mid-Jurassic high-grade metamorphic rocks and intrusions. The Cretaceous accretionary complex structurally overlies an arc-related low-grade metavolcanic unit, which is thrusted over the ophiolitic rocks of the main Tethyan ?zmir-Ankara-Erzincan Suture zone that separates the Pontides from the Gondwana-derived terranes. In the tectonic framework discussed above, the study area represents subduction and accretion related units, which are sandwiched between the southern Laurasian active margin and the Gondwana-derived K?r?ehir Block without any <span class="hlt">continental</span> fragments. This indicates that Pacific-type pre-collisional accretion has a major role in the Tethyan geology of the Central Pontides during Cretaceous. Okay et al. (2013) Tectonics 32: 1247-1271.</p> <div class="credits"> <p class="dwt_author">Aygul, Mesut; Okay, Aral I.; Oberhaensli, Roland; Sudo, Masafumi</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">287</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ucmp.berkeley.edu/geology/tectonics.html"> <span id="translatedtitle">Geology: <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This site is the <span class="hlt">Plate</span> Tectonics portion of the Geology site from the University of California, Berkeley, Museum of Paleontology. This exhibit has a section devoted to the explanation of the history of <span class="hlt">plate</span> tectonics and a section that focuses on the mechanisms driving <span class="hlt">plate</span> tectonics. The mechanisms section discusses convection, mid-oceanic ridges, geomagnetic anomalies, deep sea trenches, and island arcs. The site also contains links to numerous animations illustrating historical <span class="hlt">plate</span> positions and movements.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">288</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004AGUFM.T41C1243H"> <span id="translatedtitle">Along-strike Variations of Subduction Parameters at the Chilean <span class="hlt">Plate</span> Boundary</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Newly compiled data of the geometric, kinematic and mechanic properties and their variations along-strike the oblique Chilean subduction margin between 20° S and 46° S are used to weigh their competing influence on forearc deformation. Special emphasis lies on the formation of margin-parallel strike-slip systems. Among the parameters considered are the convergence rate and obliquity, the ocean floor age, the dip of the down-going and the slope of the <span class="hlt">overriding</span> <span class="hlt">plate</span>, the geodetic and seismic coupling depth, the interplate seismicity, the depth of the trench-fill and the mass transfer mode at the subduction front. Commonly discussed control factors for forearc deformation can be attributed to three major elements of a subduction system, namely (1) the <span class="hlt">plate</span> kinematic boundary conditions, (2) the <span class="hlt">plate</span> coupling properties that govern the effectiveness of force transmission from the subducting <span class="hlt">plate</span> to the <span class="hlt">overriding</span> <span class="hlt">plate</span>, and (3) the upper <span class="hlt">plate</span> heterogeneities affecting its rheology (e.g. elasticity, shear strength) or resistance to block motion (buttressing). An example is given for each of these elements: (1) Oblique convergence is a pre-requisite for the activation of margin-parallel strike-slip systems, but apparently not a sufficient condition. For example, strike-slip motion can presently be observed along the Liquiñe-Ofqui Fault Zone in southern Chile, while neither the Atacama Fault Zone nor the Precordilleran Fault System in northern Chile accommodate significant amounts of margin-parallel slip since the Pliocene. This difference can not be explained by variations of convergence rate or obliquity as the <span class="hlt">plate</span> kinematic framework is almost constant along the Chilean trench. (2) The <span class="hlt">plate</span> coupling force is a function of the frictionally coupled area on the <span class="hlt">plate</span> interface and of the shear friction that needs to be overcome. Along the Chilean margin various factors affect coupling in opposing manner: The slab-dip is shallower in southern Chile compared to northern Chile, resulting in a greater <span class="hlt">plate</span> contact area. On the other hand, subduction of younger and hotter oceanic <span class="hlt">plate</span> in the south could limit the frictionally coupled area (counter acted by increased buoyancy forces?). Subduction of wet sediments in the accretive margin of southern Chile compared to the erosive margin in the north may additionally weaken the interface. (3) The trenchward concave-shaped margin in North-Chile likely hampers margin-parallel motion of a forearc sliver, while strike-slip faulting may be supported in southern Chile due to the lateral proximity of the downdip end of coupling on the <span class="hlt">plate</span> interface and the rheologically weakened zone of the active volcanic arc. Establishing the current state of <span class="hlt">plate</span> coupling in southern Chile compared to northern Chile thus remains ambiguous. Margin-parallel strike-slip activity in southern Chile, however, may be facilitated by superposition of two conditions: a shallow-dipping slab that transfers stresses at the base of the <span class="hlt">overriding</span> <span class="hlt">plate</span> further arcward and an exceptionally close position of the arc to the trench.</p> <div class="credits"> <p class="dwt_author">Hoffmann-Rothe, A.; Kukowski, N.; Oncken, O.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">289</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1613274L"> <span id="translatedtitle">Anatomy of a diffuse cryptic suture zone exemplified by European Variscan belt: a new concept of <span class="hlt">continental</span> tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">plate</span> tectonics paradigm has offered a link between the horizontal movement of lithospheric <span class="hlt">plates</span>, closure of intervening oceanic basin and formation of oceanic suture zone preserved even during <span class="hlt">continental</span> collision. On the example of the Bohemian Massif we document the evolution of Andean type orogen involved in <span class="hlt">continental</span> collision. Based on combined geological data, geophysical imagery and fully scaled thermomechanical modelling a modified view on the internal architecture of collisional orogens is proposed. The characteristic feature of the model proposed for the Variscan orogen in the Bohemian Massif is the convergence of two contrasting domains of lithosphere, leading to subduction of an attenuated felsic metaigneous crust under the rifted (Gondwana) margin formed by a dense sequence of metasedimentary and metabasic rocks. The relamination of refractory light material rich in radioactive elements underneath the relatively dense upper <span class="hlt">plate</span> is responsible for the gravitational instabilities that lead to the overturns in the thickened crust. This mechanism results in the formation of a diffuse cryptic suture zone, i.e., a wide zone in which materials from the lower and upper <span class="hlt">plates</span> are mixed to form a hybrid <span class="hlt">continental</span> crust. The diffuse cryptic suture zone remains the only evidence of the original <span class="hlt">plate</span> boundary repeatedly re-appearing within the orogen. We propose that this model may have a general validity and possible link to modern orogens exemplified by comparison of Variscan and Tibetan orogenic systems is proposed based on petrological characteristics and similarities in geophysical signatures.</p> <div class="credits"> <p class="dwt_author">Lexa, Ondrej; Schulmann, Karel; Janoušek, Vojt?ch; Lardeaux, Jean Marc</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">290</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56839219"> <span id="translatedtitle">Laser induced copper <span class="hlt">plating</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Argon laser induced <span class="hlt">plating</span> of copper spots and lines from copper sulfate solutions on glass and phenolic resin paper has been investigated. The substrates had to be precoated with an evaporated copper film. The highest <span class="hlt">plating</span> rates have been obtained with a small film thickness of 25 nm. Spots with a thickness up to 30 ?m were <span class="hlt">plated</span>.</p> <div class="credits"> <p class="dwt_author">A. K. Al-Sufi; H. J. Eichler; J. Salk; H. J. Riedel</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">291</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26241419"> <span id="translatedtitle">Optimal truss <span class="hlt">plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Sandwich <span class="hlt">plates</span> comprised of truss cores faced with either planar trusses or solid sheets are optimally designed for minimum weight subject to prescribed combinations of bending and transverse shear loads. Motivated by recent advances in manufacturing possibilities, attention is focussed on <span class="hlt">plates</span> with truss elements and faces made from a single material. The optimized <span class="hlt">plates</span> are compared with similarly optimized</p> <div class="credits"> <p class="dwt_author">Nathan Wicks; John W Hutchinson</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">292</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://crack.seismo.unr.edu/ftp/pub/louie/class/plate-syll.html"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonic Theory</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This is the web site for a <span class="hlt">Plate</span> Tectonics Theory class at The University of Nevada, Reno. The home page/syllabus contains links to several of the topics covered in the course. The topics with web based lecture materials are earthquake seismology, structure of the Earth, composition of the Earth, lithospheric deformation, the <span class="hlt">plate</span> tectonics paradigm, and the driving mechanisms of <span class="hlt">plate</span> tectonics.</p> <div class="credits"> <p class="dwt_author">Louie, John</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">293</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://earthquake.usgs.gov/learn/topics/plate_tectonics/rift_man.php"> <span id="translatedtitle">Earthquakes and <span class="hlt">Plate</span> Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This article describes the theory of <span class="hlt">plate</span> tectonics and its relation to earthquakes and seismic zones. Materials include an overview of <span class="hlt">plate</span> tectonics, a description of Earth's crustal <span class="hlt">plates</span> and their motions, and descriptions of the four types of seismic zones.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">294</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUFMOS21A1143T"> <span id="translatedtitle">Study of southern CHAONAN sag lower <span class="hlt">continental</span> slope basin deposition character in Northern South China Sea</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Northern South China Sea Margin locates in Eurasian <span class="hlt">plate</span>,Indian-Australia <span class="hlt">plate</span>,Pacific <span class="hlt">Plates</span>.The South China Sea had underwent a complicated tectonic evolution in Cenozoic.During rifting,the <span class="hlt">continental</span> shelf and slope forms a series of Cenozoic sedimentary basins,including Qiongdongnan basin,Pearl River Mouth basin,Taixinan basin.These basins fill in thick Cenozoic fluviolacustrine facies,transitional facies,marine facies,abyssal facies sediment,recording the evolution history of South China Sea Margin rifting and ocean basin extending.The studies of tectonics and deposition of depression in the Southern Chaonan Sag of lower <span class="hlt">continental</span> slope in the Norther South China Sea were dealt with,based on the sequence stratigraphy and depositional facies interpretation of seismic profiles acquired by cruises of“China and Germany Joint Study on Marine Geosciences in the South China Sea”and“The formation,evolution and key issues of important resources in China marginal sea",and combining with ODP 1148 cole and LW33-1-1 well.The free-air gravity anomaly of the break up of the <span class="hlt">continental</span> and ocean appears comparatively low negative anomaly traps which extended in EW,it is the reflection of passive margin gravitational effect.Bouguer gravity anomaly is comparatively low which is gradient zone extended NE-SW.Magnetic anomaly lies in Magnetic Quiet Zone at the Northern <span class="hlt">Continental</span> Margin of the South China Sea.The Cenozoic sediments of lower <span class="hlt">continental</span> slope in Southern Chaonan Sag can be divided into five stratum interface:SB5.5,SB10.5,SB16.5,SB23.8 and Hg,their ages are of Pliocene-Quaternary,late Miocene,middle Miocene,early Miocene,paleogene.The tectonic evolution of low <span class="hlt">continental</span> slope depressions can be divided into rifting,rifting-depression transitional and depression stages,while their depositional environments change from river to shallow marine and abyssa1,which results in different topography in different stages.The topographic evolvement in the study area includes three stages,that is Eogene,middle stage of lately Oligocene to early Miocene and middle Miocene to Present.Result shows that there are a good association of petroleum source rocks,reservoir rocks and seal rocks and structural traps in the Cenozoic and Mesozoic strata,as well as good conditions for the generation-migration-accumulation-preservation of petroleum in the lower continatal slope of Southern Chaoshan Sag.So the region has good petroleum prospect. Key words:Northern South China Sea;Chaoshan Sag; lower <span class="hlt">continental</span> slope; deposition.</p> <div class="credits"> <p class="dwt_author">Tang, Y.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">295</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/doepatents/biblio/1012608"> <span id="translatedtitle">Angular shear <span class="hlt">plate</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p class="result-summary">One or more disc-shaped angular shear <span class="hlt">plates</span> each include a region thereon having a thickness that varies with a nonlinear function. For the case of two such shear <span class="hlt">plates</span>, they are positioned in a facing relationship and rotated relative to each other. Light passing through the variable thickness regions in the angular <span class="hlt">plates</span> is refracted. By properly timing the relative rotation of the <span class="hlt">plates</span> and by the use of an appropriate polynomial function for the thickness of the shear <span class="hlt">plate</span>, light passing therethrough can be focused at variable positions.</p> <div class="credits"> <p class="dwt_author">Ruda, Mitchell C. (Tucson, AZ); Greynolds, Alan W. (Tucson, AZ); Stuhlinger, Tilman W. (Tucson, AZ)</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-07-14</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">296</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005AGUFM.T23D..01B"> <span id="translatedtitle">Metamorphism in <span class="hlt">Plate</span> Boundary Zones</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Accretionary orogenic systems (AOS) form at sites of subduction of oceanic lithosphere; these systems dominate during supercontinent break-up and dispersal. Collisional orogenic systems (COS) form where ocean basins close and subduction ultimately ceases; these systems dominate during crustal aggregation and assembly of supercontinents. It follows that COS may be superimposed on AOS, although AOS may exist for 100s Ma without terminal collision. AOS are of two types, extensional-contractional AOS in dominantly extensional arc systems, and terrane-dominated AOS in which accretion of allochthonous elements occurs during oblique convergence. On modern Earth, regional metamorphism occurs in <span class="hlt">plate</span> boundary zones. Blueschists are created in the subduction zone and ultra-high pressure metamorphic (UHPM) rocks are created in collision zones due to deep subduction of <span class="hlt">continental</span> lithosphere; granulites are created deep under <span class="hlt">continental</span> and oceanic plateaus and in arcs and collision zones [high-pressure (HP) granulites, ultra-high temperature (UHT) granulites]. In extensional-contractional AOS, basement generally is not exposed, primitive volcanic rocks occur through the history, rift basins step oceanward with time, and a well-defined arc generally is absent. LP-HT metamorphism is dominant, with looping, CW or CCW P-T-t paths and peak metamorphic mineral growth syn-to-late in relation to tectonic fabrics. UHT and HP granulites are absent, and although rare, blueschists may occur early, but UHPM is not recorded. Short-lived contractional phases of orogenesis probably relate to interruptions in the continuity of subduction caused by features on the ocean <span class="hlt">plate</span>, particularly plateaus. Extensive granite (s.l.) magmatism accompanies metamorphism. Examples include the Lachlan Orogen, Australia, the Acadian Orogen, NE USA and Maritime Canada, and the Proterozoic orogens of the SW USA. At <span class="hlt">plate</span> boundaries, oblique convergence is partitioned into two components, one directed more orthogonal to the strike of the trench than the convergence vector, and the other directed parallel to the strike of the trench. The orthogonal component is accommodated by subduction, but the margin-parallel component gives rise to block rotations and extension, strike-slip motion, and shortening within the upper <span class="hlt">plate</span>. In some AOS, it has been argued that `paired' metamorphic belts characterize the metamorphic pattern. Commonly, this is a false construct that results from failure to recognize orogen-parallel terrane migration and the limitations of particular chronological datasets. Whereas a HP-LT (blueschist-eclogite) metamorphic belt may occur outboard, it is generally separated from a LP-HT (And-Sil type) metamorphic belt by a terrane boundary. These are terrane-dominated AOS. In some AOS an additional feature of the orogenic process is ridge subduction, which is reflected in the pattern of LP-HT metamorphism and the magmatism. Granulites may occur at the highest grade of metamorphism in the LP-HT belt, where granite (s.l.) magmatism is common, but UHPM occurs only rarely in the outboard HP-LT belt. Examples include the Mesozoic metamorphic belts of Japan and the North American Cordillera. COS commonly are characterized by syntectonic index minerals that record CW P-T-t paths and Barrovian-type metamorphic field gradients generated by thickening followed by exhumation. However, during the Neoproterozoic, ultra-high temperature granulite facies metamorphism is common in orogens that suture Gondwana, whereas during the Phanerozoic, metamorphism to high-pressure granulite/medium temperature eclogite facies and extreme UHPM conditions commonly occurs and may be more typical of younger COS; examples include the Alpides, the Qinling - Dabie Shan - Sulu orogens, the Variscides and the Caledonides.</p> <div class="credits"> <p class="dwt_author">Brown, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">297</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2005AGUFM.T13B0481P"> <span id="translatedtitle">Hydration and Flat-<span class="hlt">Plate</span> Subduction Stability</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Approximately 10% of the Earth's subduction zones are experiencing sub-horizontal subduction. This behaviour is commonly attributed to several factors including low <span class="hlt">plate</span> density, increased <span class="hlt">plate</span> convergence velocity, and slab suction. In addition, mantle hydration may also be a controlling factor in both the onset and ultimate failure of sub-horizontally subducting systems. Here, we present 2D numerical experiments aimed at studying the onset and stability of flat subduction in a scenario roughly reminiscent of the Farallon <span class="hlt">plate</span>'s sub-horizontal subduction beneath the western US from 80 to 40 mya. In these experiments, the lithosphere and mantle are modeled as a visco-elasto-plastic medium. The brittle parts of the lithosphere are modeled as a frictional and cohesional material. The ductile lithosphere is modeled as a non-Newtonian Maxwell visco-elastic material. Faults in the brittle parts of the model are formed by locally decreasing the cohesion and friction as a function of plastic strain. The rheological structure of the model is controlled by the initial temperature distribution and the temperature boundary conditions. A proxy to emulate phase changes allows for "instantaneous" transformations between phases at specified pressures and temperatures. In these experiments, both crustally-thickened (representing oceanic plateaus) and archetypical oceanic lithosphere are subducted beneath <span class="hlt">continental</span> lithosphere. These simulations begin with subduction initiation along a pre-weakened zone at the contact between oceanic and <span class="hlt">continental</span> lithospheres. Various parameters including subduction velocity, mantle viscosity, and bulk lithospheric density are varied (within realistic ranges) in order to promote large scale, stable, flat subduction. In these stable flat-slab systems, local mantle viscosities and densities will vary according to a preliminary phase change model proxy in order to simulate alteration of the lithosphere via hydration. This hydration is due to water and other volatiles released from the subducted slab that fails to trigger surface volcanism and remains trapped in mantle phases. Crustal phase densities also evolve via an eclogite phase change proxy. As the viscosity of the lithospheric mantle between the horizontally coupled <span class="hlt">plates</span> degrades due to hydration, flat or flattened subduction begins to fail. This results in slab rollback until a more typical subduction geometry arises. Preliminary results show that the retreat ultimately leads to catastrophic delamination of material from the <span class="hlt">continental</span> lithosphere resulting in a region of attenuated lithospheric thickness similar to that observed in the Basin and Range Provinces of North America. This outcome is consistent with, though certainly not a proof of, a possible role for a build-up of hydrated phases acting as a destabilization mechanism for flat slab subduction.</p> <div class="credits"> <p class="dwt_author">Patel, P. I.; Lavier, L.; Grand, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">298</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUFM.V43H..05S"> <span id="translatedtitle">Mantle Calcium Dominates <span class="hlt">Continental</span> Magmas</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Trace element and isotopic compositions of <span class="hlt">continental</span> igneous rocks are often used to model the generation and evolution of crustal magmas. Here we report new Ca isotopic measurements of crystal-poor (<10%) to monotonous crystal-rich (>35%) rhyolites from the Oligocene San Juan Volcanic Field (SJVF) and Pliocene to Pleistocene tuffs from Yellowstone Caldera. Because both volcanic fields are located within the North American craton the extruded magmas could have assimilated old crustal source components with radiogenic Ca that would be clearly distinguishable from that of the mantle. New Ca data are also reported for two crustal xenoliths found within the 28.2 Ma Fish Canyon Tuff (FCT) of the SJVF that yield ?Ca values of 3.8±0.6 (2 ?, n=3) and 7.5±0.4 (2 ?, n=3), respectively. The 40Ca excesses of these possible source rocks are due to long-term in situ 40K decay and suggest that they are Precambrian in age. In contrast to the excess radiogenic Ca signatures, most Cenozoic basalts and many silicic igneous rocks from Earth yield initial ?Ca values close to zero, which indicates that the 40Ca/44Ca ratio of the Earth’s mantle is well defined and virtually invariant at the resolution of our measurements. The crystal-rich FCT, inferred to result from batholith-scale remobilization of a shallow subvolcanic magma chamber, exhibits an ?Cai value of 0.32±0.02 (2 ?, n=5) that is indistinguishable from Ca in clinopyroxene from an ultramafic xenolith that has a mantle-like ?Cai value of -0.35±0.62 (2 ?, n=2). Simple mass balance calculations indicate that Ca in the FCT is greater than ~75% mantle derived. Similar mixing models based on published Nd data for the FCT that consider the range of possible crustal source components can deviate substantially from the Ca models. At face value the Nd data indicate that the FCT magma underwent significant crustal assimilation (i.e., at least ~10% and possibly ~75% of the Nd appears to have come from an enriched source component). So even in cases where a crustal component is clear (like the FCT), the importance of mantle magma input can be shown with Ca isotopes. The Ca isotopic compositions of the Lava Creek Tuff = 0.28±0.09 (2 ?, n=4) and Huckleberry Ridge Tuff = 0.11±0.17 (2 ?, n=1) of Yellowstone also imply substantial mantle sources. Crystal-poor ignimbrites from the SJVF exhibit similar to slightly higher ?Cai values. These include the Sapinero Mesa Tuff that has an ?Cai = 0.32±0.41 (2 ?, n=5), the Tuff of Saguache = 0.55±0.12 (2 ?, n=2), and the Blue Mesa Tuff = 1.77±0.64 (2 ?, n=3), respectively. Where ?Cai is clearly higher than zero (i.e., above +1.5), it is a good indication that the silicic magma has a source in the <span class="hlt">continental</span> crust. In extrusions where low ?Nd could also be due to melting from enriched reservoirs in the mantle lithosphere, the combination of high ?Cai with low ?Nd clearly identifies crustal melts. The mantle dominated isotopic composition of a major lithophile element in silicic magmas suggests that a significant component of their source rocks were either poor in incompatible elements and/or that the silicic magmas represent recent additions to the <span class="hlt">continental</span> crust.</p> <div class="credits"> <p class="dwt_author">Simon, J. I.; Depaolo, D. J.; Bachmann, O.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">299</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5587891"> <span id="translatedtitle">Regional magnetic anomaly constraints on <span class="hlt">continental</span> breakup</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary"><span class="hlt">Continental</span> lithosphere magnetic anomalies mapped by the Magsat satellite are related to tectonic features associated with regional compositional variations of the crust and upper mantle and crustal thickness and thermal perturbations. These <span class="hlt">continental</span>-scale anomaly patterns when corrected for varying observation elevation and the global change in the direction and intensity of the geomagnetic field show remarkable correlation of regional lithospheric magnetic sources across rifted <span class="hlt">continental</span> margins when plotted on a reconstruction of Pangea. Accordingly, these anomalies provide new and fundamental constraints on the geologic evolution and dynamics of the continents and oceans.</p> <div class="credits"> <p class="dwt_author">von Frese, R.R.B.; Hinze, W.J.; Olivier, R.; Bentley, C.R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">300</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19850062237&hterms=Geological+time&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGeological%2Btime"> <span id="translatedtitle"><span class="hlt">Continental</span> volume and freeboard through geological time</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The consequences of approximately constant freeboard for <span class="hlt">continental</span> growth are explored using a model that relates the volumes of isostatically compensated continents and oceans to the secular decline in terrestrial heat flow. It is found that a post-Archean increase in freeboard by 200 m requires <span class="hlt">continental</span> growth of only 10 percent, while a decrease in freeboard by 200 m during this same period necessitates a crustal growth of 40 percent. Shrinkage of the <span class="hlt">continental</span> crust since the end of the Archean can be ruled out. Changes of more than 10 percent in post-Archean crustal thickness are highly unlikely.</p> <div class="credits"> <p class="dwt_author">Schubert, G.; Reymer, A. P. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_14");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">301</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5031755"> <span id="translatedtitle"><span class="hlt">Continental</span> margin tectonics - Forearc processes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Recent studies of convergent <span class="hlt">plate</span> margins and the structural development of forearc terranes are summarized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the geometry of accretionary prisms (Coulomb wedge taper and vertical motion in response to tectonic processes), offscraping vs underplating or subduction, the response to oblique convergence, fluids in forearc settings, the thermal framework and the effects of fluid advection, and serpentinite seamounts. Also included is a comprehensive bibliography for the period.</p> <div class="credits"> <p class="dwt_author">Lundberg, N.; Reed, D.L. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">302</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1616887R"> <span id="translatedtitle">The Evolution of Surface <span class="hlt">Plate</span> Velocities and its Link to Mantle Dynamics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">At the present day, the outermost shell of the Earth is subdivided into several tectonic <span class="hlt">plates</span> whose velocities are well determined. By knowing these velocities, inferences about the present organization of Earth's deeper interior can be made, and consequently, understanding the evolution of <span class="hlt">plate</span> velocities can likely constrain the evolution of <span class="hlt">plate</span> tectonics in general and specifically its link to deeper mantle dynamics. In many previous studies using structure and velocities of the tectonic <span class="hlt">plates</span> have been reconstructed within a kinematic framework, with some <span class="hlt">plates</span> (e.g. India) showing significant temporal variations in their average velocity. However, these reconstructions are limited by the preservation of seafloor (i.e. < 200 Myr) and cannot explain Earth's surface evolution in a dynamically consistent manner. Here, we use fully dynamic 3D spherical mantle convection simulations with self-consistent <span class="hlt">plate</span> tectonics and <span class="hlt">continental</span> drift to study the structure and dynamic evolution of Earth's <span class="hlt">plate</span> velocities over timescales that significantly exceed the kinematically reconstructed timespans as well as the duration of Earth's supercontinent cycle. In this study, we present long-term evolutions of oceanic and <span class="hlt">continental</span> <span class="hlt">plate</span> velocities. We observe significant fluctuations in velocity magnitude for both types of <span class="hlt">plates</span> that seem to be linked to the assembly and break-up of large (super-)continents as well as large-scale reorganizations of mantle flow.</p> <div class="credits"> <p class="dwt_author">Rolf, Tobias; Tackley, Paul; Capitanio, Fabio</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">303</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012EGUGA..1412221H"> <span id="translatedtitle">Gravity and Flexure Modelling of Subducting <span class="hlt">Plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The long-term strength of the lithosphere is determined by its flexural rigidity, which is commonly expressed through the effective elastic thickness, Te. Flexure studies have revealed a dependence of Te on thermal age. In the oceans, loads formed on young (70 Ma) seafloor. In the continents, loads on young (1000 Ma) lithosphere. Recent studies have questioned the relationship of Te with age, especially at subduction zones, where oceanic and <span class="hlt">continental</span> lithosphere are flexed downwards by up to ~6 km over horizontal distances of up to ~350 km. We have therefore used free-air gravity anomaly and topography profile data, combined with forward and inverse modelling techniques, to re-assess Te in these settings. Preliminary inverse modelling results from the Tonga-Kermadec Trench - Outer Rise system, where the Pacific <span class="hlt">plate</span> is subducting beneath the Indo-Australian <span class="hlt">plate</span>, show large spatial variations in Te that are unrelated to age. In contrast to the southern end of the system, where Te is determined by the depth to the 600° C and 900° C isotherms, the northern end of the system shows a reduction in strength. Results also suggest a reduction in Te trenchward of the outer rise that is coincident with a region of pervasive extensional faulting visible in swath bathymetry data. In a <span class="hlt">continental</span> setting, the Ganges foreland basin has formed by flexure of the Indo-Australian <span class="hlt">plate</span> in front of the migrating loads of the Himalaya. Preliminary forward modelling results, using the Himalaya as a known surface topographic load, suggest that Te is high - consistent with the great age of Indian cratonic lithosphere. However, results from inverse modelling that solves for unknown loads (vertical shear force and bending moment) show significant scatter and display trade-offs between Te and these driving loads.</p> <div class="credits"> <p class="dwt_author">Hunter, J. A.; Watts, A. B.; SO 215 Shipboard Scientific Party</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">304</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=ADA374245"> <span id="translatedtitle">Method for Interpreting <span class="hlt">Continental</span> and Analytic Epistemology.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">Current investigations in epistemology tend to follow either the <span class="hlt">continental</span> or the analytic school of thought. These schools of thought have different goals for epistemology and different procedures for achieving these goals. The purpose of this thesis i...</p> <div class="credits"> <p class="dwt_author">S. R. McCoy</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">305</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=DE96733844"> <span id="translatedtitle">Petroleum resources on the Norwegian <span class="hlt">continental</span> shelf.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">The overall objective of the Norwegian Petroleum Directorate (NPD) is to maximize the creation of value on the Norwegian <span class="hlt">continental</span> shelf by promoting the sound management of petroleum resources having a balanced regard for the natural, safety-related, e...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">306</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009PEPI..177..180G"> <span id="translatedtitle"><span class="hlt">Continental</span> margin deformation along the Andean subduction zone: Thermo-mechanical models</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Chilean Andes extend north-south for about 3000 km over the subducting Nazca <span class="hlt">plate</span>, and show evidence of local rheological controls on first-order tectonic features. Here, rheological parameters are tested with numerical models of a subduction driven by slab-pull and upper <span class="hlt">plate</span> velocities, and which calculate the development of stress and strain over a typical period of 4 Myr. The models test the effects of subduction interface strength, arc and fore-arc crust rheology, and arc temperature, on the development of superficial near-surface faulting as well as viscous shear zones in the mantle. Deformation geometries are controlled by the intersection of the subduction interface with <span class="hlt">continental</span> rheological heterogeneities. Upper <span class="hlt">plate</span> shortening and trench advance are both correlated, and favored, to a first-order by upper <span class="hlt">plate</span> weakness, and to a second-order by interface strength. In cases of a strong interface, a weak fore-arc crust is dragged downward by “tectonic erosion”, a scenario for which indications are found along the northern Chilean margin. In contrast for a resistant fore-arc, the slab-pull force transmits to the surface and produces topographic subsidence. This process may explain present-day subsidence of the Salar de Atacama basin and/or the persistence of a Central Depression. Specific conditions for northern Chile produce a shear zone that propagates from the subduction zone in the mantle, through the Altiplano lower crust into the Sub-Andean crust, as proposed by previous studies. Models with a weak interface in turn, allow buoyant subducted material to rise into the <span class="hlt">continental</span> arc. In case of cessation of the slab-pull, this buoyant material may rise enough to change the stress state in the <span class="hlt">continental</span> crust, and lead to back-arc opening. In a case of young and hydrated oceanic <span class="hlt">plate</span> forced by the slab-pull to subduct under a resistant continent, this <span class="hlt">plate</span> is deviated and indented by the <span class="hlt">continental</span> mantle, and stretches horizontally at ˜100 km depth. This situation might explain the flat Wadati-Benioff zone of Central Chile.</p> <div class="credits"> <p class="dwt_author">Gerbault, Muriel; Cembrano, J.; Mpodozis, C.; Farias, M.; Pardo, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">307</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JAESc..88...28S"> <span id="translatedtitle">Cenozoic tectonic jumping and implications for hydrocarbon accumulation in basins in the East Asia <span class="hlt">Continental</span> Margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Tectonic migration is a common geological process of basin formation and evolution. However, little is known about tectonic migration in the western Pacific margins. This paper focuses on the representative Cenozoic basins of East China and its surrounding seas in the western Pacific domain to discuss the phenomenon of tectonic jumping in Cenozoic basins, based on structural data from the Bohai Bay Basin, the South Yellow Sea Basin, the East China Sea Shelf Basin, and the South China Sea <span class="hlt">Continental</span> Shelf Basin. The western Pacific active <span class="hlt">continental</span> margin is the eastern margin of a global convergent system involving the Eurasian <span class="hlt">Plate</span>, the Pacific <span class="hlt">Plate</span>, and the Indian <span class="hlt">Plate</span>. Under the combined effects of the India-Eurasia collision and retrogressive or roll-back subduction of the Pacific <span class="hlt">Plate</span>, the western Pacific active <span class="hlt">continental</span> margin had a wide basin-arc-trench system which migrated or ‘jumped’ eastward and further oceanward. This migration and jumping is characterized by progressive eastward younging of faulting, sedimentation, and subsidence within the basins. Owing to the tectonic migration, the geological conditions associated with hydrocarbon and gashydrate accumulation in the Cenozoic basins of East China and its adjacent seas also become progressively younger from west to east, showing eastward younging in the generation time of reservoirs, seals, traps, accumulations and preservation of hydrocarbon and gashydrate. Such a spatio-temporal distribution of Cenozoic hydrocarbon and gashydrate is significant for the oil, gas and gashydrate exploration in the East Asian <span class="hlt">Continental</span> Margin. Finally, this study discusses the mechanism of Cenozoic intrabasinal and interbasinal tectonic migration in terms of interplate, intraplate and underplating processes. The migration or jumping regimes of three separate or interrelated events: (1) tectonism-magmatism, (2) basin formation, and (3) hydrocarbon-gashydrate accumulation are the combined effects of the Late Mesozoic extrusion tectonics, the Cenozoic NW-directed crustal extension, and the regional far-field eastward flow of the western asthenosphere due to the India-Eurasia <span class="hlt">plate</span> collision, accompanied by eastward jumping and roll-back of subduction zones of the Pacific <span class="hlt">Plate</span>.</p> <div class="credits"> <p class="dwt_author">Suo, Yanhui; Li, Sanzhong; Yu, Shan; Somerville, Ian D.; Liu, Xin; Zhao, Shujuan; Dai, Liming</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">308</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70011594"> <span id="translatedtitle">Freshwater peat on the <span class="hlt">continental</span> shelf</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Freshwater peats from the <span class="hlt">continental</span> shelf off northeastern United States contain the same general pollen sequence as peats from ponds that are above sea level and that are of comparable radiocarbon ages. These peats indicate that during glacial times of low sea level terrestrial vegetation covered the region that is now the <span class="hlt">continental</span> shelf in an unbroken extension from the adjacent land areas to the north and west.</p> <div class="credits"> <p class="dwt_author">Emery, K. O.; Wigley, R. L.; Bartlett, A. S.; Rubin, M.; Barghoorn, E. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1967-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">309</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52236391"> <span id="translatedtitle">Annual Hydroclimatology of the <span class="hlt">Continental</span> United States</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The annual hydroclimatology of the <span class="hlt">continental</span> United States is explored using a unique set of monthly hydroclimatic time-series which accounts for the complex variations in hydrology and climate. Several approaches are compared for estimating the long-term water balance, the interannual variability of streamflow and climate elasticity of streamflow at 1337 watersheds in the <span class="hlt">continental</span> U.S. Budyko-type relations which predict actual</p> <div class="credits"> <p class="dwt_author">S. Arumugam; R. Vogel</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">310</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6679173"> <span id="translatedtitle">Coordination: southeast <span class="hlt">continental</span> shelf studies. Progress report</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The objectives are to identify important physical, chemical and biological processes which affect the transfer of materials on the southeast <span class="hlt">continental</span> shelf, determine important parameters which govern observed temporal and spatial varibility on the <span class="hlt">continental</span> shelf, determine the extent and modes of coupling between events at the shelf break and nearshore, and determine physical, chemical and biological exchange rates on the inner shelf. Progress in meeting these research objectives is presented. (ACR)</p> <div class="credits"> <p class="dwt_author">Menzel, D.W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-02-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">311</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/3814237"> <span id="translatedtitle">Subduction of <span class="hlt">continental</span> lithosphere: Some constraints and uncertainties</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Two effects that contribute to the subduction of <span class="hlt">continental</span> lithosphere are the negative buoyancy of the relatively cold mantle part of <span class="hlt">continental</span> lithosphere and the pull of a downgoing slab of oceanic lithosphere on <span class="hlt">continental</span> lithosphere trailing behind it. The mantle part of the lithosphere could continuously subduct about 10 km of <span class="hlt">continental</span> crust, if the upper and lower crust</p> <div class="credits"> <p class="dwt_author">Peter Molnar; Dale Gray</p> <p class="dwt_publisher"></p> <p class="publishDate">1979-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">312</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.7346D"> <span id="translatedtitle">Time-integrated Rb/Sr as a proxy for the composition of the new <span class="hlt">continental</span> crust through time</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Recent models on <span class="hlt">continental</span> growth suggest that 65-70% of the present volume of the <span class="hlt">continental</span> crust was present by 3 Ga, and that the rates of <span class="hlt">continental</span> growth were significantly higher before 3 Ga than subsequently. This change has been tentatively linked to the onset of subduction-driven <span class="hlt">plate</span> tectonics and discrete subduction zones. If correct this represents a fundamental change in the evolution of the Earth, with implications for the nature of the magmas generated, the efficiency with which crustal material is returned back into the mantle and the cooling history of the Earth. Geochemical constraints indicate that about 80% of the crust still preserved today was formed in subduction settings, with the rest being mostly related to intraplate magmatism (i.e. oceanic island and <span class="hlt">continental</span> flood magmas). New <span class="hlt">continental</span> crust that is currently formed and preserved along destructive <span class="hlt">plate</span> margins, such as the Andes, has an intermediate/felsic-dominated composition that is similar to the composition of the bulk <span class="hlt">continental</span> crust. In contrast crust formed in intraplate settings has a more mafic composition. Because of the poor preservation of rocks and minerals after billions of years of crustal evolution, a major uncertainty remains about the composition of new, juvenile <span class="hlt">continental</span> crust in the Hadean and the Archaean, and hence the conditions and the tectonic setting(s) in which it was generated. One way forward is to evaluate the composition of new <span class="hlt">continental</span> crust from the time-integrated parent/daughter ratios of isotope systems in magmatic rocks subsequently derived from that new crust. Because of the highly incompatible character of the Rb-Sr system, crustal differentiation processes produce a large range of highly fractionated Rb/Sr ratios. As a consequence mafic crust typically has Rb/Sr at least five times grater than intermediate/felsic bulk crust. We calculated time-integrated Rb/Sr in crustal material with pre- and post-3 Ga Nd model ages. Preliminary data indicate that time-integrated Rb/Sr were, on average, much lower in the Hadean/Mesoarchaean than subsequently. This suggests that new <span class="hlt">continental</span> crust was principally mafic over the first 1.5 Ga of Earth evolution, that a large volume of pre-3 Ga crust may have been associated with intraplate magmatism, and that ~3 Ga may indeed mark the onset of <span class="hlt">plate</span> tectonics on Earth.</p> <div class="credits"> <p class="dwt_author">Dhuime, Bruno; Hawkesworth, Chris; Cawood, Peter</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">313</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1988EOSTr..69..580C"> <span id="translatedtitle">The <span class="hlt">Continental</span> Crust: A Geophysical Approach</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Nearly 80 years ago, Yugoslavian seismologist Andrija Mohorovicic recognized, while studying a Balkan earthquake, that velocities of seismic waves increase abruptly at a few tens of kilometers depth , giving rise to the seismological definition of the crust. Since that discovery, many studies concerned with the nature of both the <span class="hlt">continental</span> and oceanic crusts have appeared in the geophysical literature.Recently, interest in the <span class="hlt">continental</span> crust has cascaded. This is largely because of an infusion of new data obtained from major reflection programs such as the Consortium for <span class="hlt">Continental</span> Reflection Profiling (COCORP) and British Institutions Reflection Profiling Syndicate (BIRPS) and increased resolution of refraction studies. In addition, deep <span class="hlt">continental</span> drilling programs are n ow in fashion. The <span class="hlt">Continental</span> Crust: A Geophysical Approach is a summary of present knowledge of the <span class="hlt">continental</span> crust. Meissner has succeeded in writing a book suited to many different readers, from the interested undergraduate to the professional. The book is well documented , with pertinent figures and a complete and up-to-date reference list.</p> <div class="credits"> <p class="dwt_author">Christensen, Nikolas I.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">314</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/5677505"> <span id="translatedtitle">Hypervelocity <span class="hlt">plate</span> acceleration</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Shock tubes have been used to accelerate 1.5-mm-thick stainless steel <span class="hlt">plates</span> to high velocity while retaining their integrity. The fast shock tubes are 5.1-cm-diameter, 15.2-cm-long cylinders of PBX-9501 explosive containing a 1.1-cm-diameter cylindrical core of low-density polystyrene foam. The <span class="hlt">plates</span> have been placed directly in contact with one face of the explosive system. Plane-wave detonation was initiated on the opposite face. A Mach disk was formed in the imploding styrofoam core, which provided the impulse required to accelerate the metal <span class="hlt">plate</span> to high velocity. Parametric studies were made on this system to find the effect of varying <span class="hlt">plate</span> metal, <span class="hlt">plate</span> thickness, foam properties, and addition of a barrel. A maximum <span class="hlt">plate</span> velocity of 9.0 km/s has been observed. 6 refs., 17 figs.</p> <div class="credits"> <p class="dwt_author">Marsh, S.P.; Tan, T.H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1991-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">315</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3104516"> <span id="translatedtitle">Mapping the evolving strain field during <span class="hlt">continental</span> breakup from crustal anisotropy in the Afar Depression</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Rifting of the continents leading to <span class="hlt">plate</span> rupture occurs by a combination of mechanical deformation and magma intrusion, yet the spatial and temporal scales over which these alternate mechanisms localize extensional strain remain controversial. Here we quantify anisotropy of the upper crust across the volcanically active Afar Triple Junction using shear-wave splitting from local earthquakes to evaluate the distribution and orientation of strain in a region of <span class="hlt">continental</span> breakup. The pattern of S-wave splitting in Afar is best explained by anisotropy from deformation-related structures, with the dramatic change in splitting parameters into the rift axis from the increased density of dyke-induced faulting combined with a contribution from oriented melt pockets near volcanic centres. The lack of rift-perpendicular anisotropy in the lithosphere, and corroborating geoscientific evidence of extension dominated by dyking, provide strong evidence that magma intrusion achieves the majority of <span class="hlt">plate</span> opening in this zone of incipient <span class="hlt">plate</span> rupture.</p> <div class="credits"> <p class="dwt_author">Keir, Derek; Belachew, M.; Ebinger, C.J.; Kendall, J.-M.; Hammond, J.O.S.; Stuart, G.W.; Ayele, A.; Rowland, J.V.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">316</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014E%26PSL.393..105C"> <span id="translatedtitle">Magmas trapped at the <span class="hlt">continental</span> lithosphere–asthenosphere boundary</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The lithosphere-asthenosphere boundary (LAB) beneath the continents is a key interface in <span class="hlt">plate</span> tectonics, yet its nature remains elusive. A partial melt layer has been advocated to explain its geophysical characteristics. However, the main counter-argument is that such a layer cannot be stable as melts should rise through the lithosphere. Density measurements of volatile-containing alkali basalts taken as a proxy for LAB melts show that they are neutrally buoyant at the pressure (P)-temperature (T) conditions of the LAB under continents. Complementary X-ray diffraction and Raman data provide structural insights on melt compaction mechanisms. Basalts generated below the lithosphere may thus be gravitationally trapped and accumulate over time. Their presence provides answers to key questions on <span class="hlt">continental</span> lithosphere geodynamics, and in particular on cratonic keels stability. This buoyancy trap would cease to exist at higher mantle T such as those relevant of the Archean, and as such, could be linked to the onset of <span class="hlt">plate</span> tectonics.</p> <div class="credits"> <p class="dwt_author">Crépisson, C.; Morard, G.; Bureau, H.; Prouteau, G.; Morizet, Y.; Petitgirard, S.; Sanloup, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">317</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5317865"> <span id="translatedtitle">Ceramic burner <span class="hlt">plate</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This invention relates to a ceramic burner <span class="hlt">plate</span> using a fiber composite ceramic of low thermal conductivity having gas passages, and provides a burner <span class="hlt">plate</span>, wherein the burner <span class="hlt">plate</span> contains a lithium component and such components as nickel, manganese, cobalt, titanium, copper, iron, chromium, and vanadium, to assist in the combustion of gas, and has a surface construction having triangular projections, hexagonal projections or rhombic projections, to ensure increased heat radiation.</p> <div class="credits"> <p class="dwt_author">Mihara, T.; Kusuda, T.; Noma, K.; Taki, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-03-12</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">318</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19740045837&hterms=fresnel+zone+plate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dfresnel%2Bzone%2Bplate"> <span id="translatedtitle">Zone <span class="hlt">plate</span> interferometer</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A developed form of the Fresner zone-<span class="hlt">plate</span> interferometer is described. Three basic configurations are distinguished, associated with the real and virtual first order foci of a zone <span class="hlt">plate</span>. Related versions and higher order variants are also educed. Compensated phase zone <span class="hlt">plates</span> used in this application are found to produce uniform amplitude wavefronts. The properties of the interferometer in this form are discussed and an example given of its high-quality performance.</p> <div class="credits"> <p class="dwt_author">Smartt, R. N.</p> <p class="dwt_publisher"></p> <p class="publishDate">1974-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">319</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.usgs.gov/gip/dynamic/understanding.html"> <span id="translatedtitle">Understanding <span class="hlt">Plate</span> Motions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This interactive site uses illustrations and photographs along with text to explain the movement of tectonic <span class="hlt">plates</span> and the result of this movement on the surface of the Earth. There is a detailed discussion of the movement at each of the four types of <span class="hlt">plate</span> boundaries: divergent, convergent, transform, and <span class="hlt">plate</span> boundary zones. Both lateral and vertical movements are depicted by maps and diagrams and resulting Earth structures are shown in photographs.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">320</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.unavco.org/community_science/science-support/crustal_motion/dxdt/model.html"> <span id="translatedtitle"><span class="hlt">Plate</span> Motion Calculator</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This program calculates tectonic <span class="hlt">plate</span> motion at any location on Earth using one or more <span class="hlt">plate</span> motion models. The possible <span class="hlt">plate</span> motion models are GSRM v1.2 (2004), CGPS (2004), HS3-NUVEL1A, REVEL 2000, APKIM2000.0, HS2-NUVEL1A, NUVEL 1A, NUVEL 1, and two models for ITRF2000. <span class="hlt">Plates</span> or frames are selected from dropdown lists or can be entered by the user. Position coordinates can be entered in geographic coordinates (decimal degrees, or degrees/minutes/seconds) or in WGS84 cartesian XYZ, as either a single point or multiple points.</p> <div class="credits"> <p class="dwt_author">Estey, Lou</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_15");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" 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style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a style="font-weight: bold;">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_18");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">321</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.amnh.org/ology/features/plates/"> <span id="translatedtitle"><span class="hlt">Plates</span> on the Move</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This fun Web article is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here, they learn about the Earth's outer shell and its constant movement. It begins with an overview that explains tectonic <span class="hlt">plates</span>. There is an animation that shows recent earthquakes and their relationship to <span class="hlt">plate</span> boundaries. Students can click to explore 12 individual volcanoes, mountains, hotspots, and earthquakes. For each of the geological formations or events, they will see a map that shows how the <span class="hlt">plates</span> are moving, an animation about <span class="hlt">plate</span> interaction, stats, and a story about that particular formation or event.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">322</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..12.2376L"> <span id="translatedtitle">New insights into <span class="hlt">continental</span> rifting from a damage rheology modeling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Previous studies have discussed how tectonic processes could produce relative tension to initiate and propagate rift zones and estimated the magnitude of the rift-driving forces. Both analytic and semi-analytic models as well as numerical simulations assume that the tectonic force required to initiate rifting is available. However, Buck (2004, 2006) estimated the minimum tectonic force to allow passive rifting and concluded that the available forces are probably not large enough for rifting of thick and strong lithosphere in the absence of basaltic magmatism (the "Tectonic Force" Paradox). The integral of the yielding stress needed for rifting over the thickness of the normal or thicker <span class="hlt">continental</span> lithosphere are well above the available tectonic forces and tectonic rifting cannot happen (Buck, 2006). This conclusion is based on the assumption that the tectonic stress has to overcome simultaneously the yielding stress over the whole lithosphere thickness and ignore gradual weakening of the brittle rocks under long-term loading. In this study we demonstrate that the rifting process under moderate tectonic stretching is feasible due to gradual weakening and "long-term memory" of the heavily fractured brittle rocks, which makes it significantly weaker than the surrounding intact rock. This process provides a possible solution for the tectonic force paradox. We address these questions utilizing 3-D lithosphere-scale numerical simulations of the <span class="hlt">plate</span> motion and faulting process base on the damage mechanics. The 3-D modeled volume consists of three main lithospheric layers: an upper layer of weak sediments, middle layer of crystalline crust and lower layer of the lithosphere mantle. Results of the modeling demonstrate gradual formation of the rift zone in the <span class="hlt">continental</span> lithosphere with the flat layered structure. Successive formation of the rift system and associated seismicity pattern strongly depend not only on the applied tectonic force, but also on the healing parameters of the crustal rocks. Results of the modeling also demonstrate how the lithosphere structure and especially depth to the Moho interface affects the geometry of the propagating rift system. With the same boundary conditions and physical properties of rocks as in the case of the flat <span class="hlt">continental</span> structure, a rift terminates above the passive <span class="hlt">continental</span> margin and a new fault system is created normal to the direction of the rift propagation. These results demonstrate that the local lithosphere structure is one of the major key factors controlling the geometry of the evolving rift system, faulting and seismicity pattern. Results of simulations suggest that under wide range of conditions a rift propagating through a <span class="hlt">continental</span> lithosphere might cease before it reaches the margin where transition to oceanic lithosphere occurs. Close to the margin different tectonic styles might take over the propagation. This behavior has been suggested for the NW continuation of the active Red Sea-Suez rift system and initiation of the Dead Sea Transform (Steckler and ten Brink, 1986). With the onset of the Red Sea opening (about Oligocene) the sub-parallel Azraq-Sirhan rift was also activated and propagated in a NW direction from the Arabian continent toward the Levant basin oceanic crust. By applying our 3-D lithosphere-scale numerical simulations on the Azraq-Sirhan rift system, we conclude that thinning of the crystalline crust and strengthening of the Arabian lithosphere led to a decrease or even termination of the rate of rift propagation next to the <span class="hlt">continental</span> margin.</p> <div class="credits"> <p class="dwt_author">Lyakhovsky, Vladimir; Segev, Amit; Weinberger, Ram; Schattner, Uri</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">323</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23744647"> <span id="translatedtitle">B7-1/B7-2 blockade <span class="hlt">overrides</span> the activation of protective CD8 T cells stimulated in the absence of Foxp3+ regulatory T cells.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Although T cell activation has been classically described to require distinct, positive stimulation signals that include B7-1 (CD80) and B7-2 (CD86) costimulation, <span class="hlt">overriding</span> suppression signals that avert immune-mediated host injury are equally important. How these opposing stimulation and suppression signals work together remains incompletely defined. Our recent studies demonstrate that CD8 Teff activation in response to cognate peptide stimulation is actively suppressed by the Foxp3(+) subset of CD4 cells, called Tregs. Here, we show that the elimination of Treg suppression does not bypass the requirement for positive B7-1/B7-2 costimulation. The expansion, IFN-? cytokine production, cytolytic, and protective features of antigen-specific CD8 T cells stimulated with purified cognate peptide in Treg-ablated mice were each neutralized effectively by CTLA-4-Ig that blocks B7-1/B7-2. In turn, given the efficiency whereby CTLA-4-Ig <span class="hlt">overrides</span> the effects of Treg ablation, the role of Foxp3(+) cell-intrinsic CTLA-4 in mitigating CD8 Teff activation was also investigated. With the use of mixed chimera mice that contain CTLA-4-deficient Tregs exclusively after the ablation of WT Foxp3(+) cells, a critical role for Treg CTLA-4 in suppressing the expansion, cytokine production, cytotoxicity, and protective features of peptide-stimulated CD8 T cells is revealed. Thus, the activation of protective CD8 T cells requires positive B7-1/B7-2 costimulation even when suppression by Tregs and in particular, Treg-intrinsic CTLA-4 is circumvented. PMID:23744647</p> <div class="credits"> <p class="dwt_author">Ertelt, James M; Buyukbasaran, Esra Z; Jiang, Tony T; Rowe, Jared H; Xin, Lijun; Way, Sing Sing</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">324</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24954638"> <span id="translatedtitle">Signals from activation of B-cell receptor with anti-IgD can <span class="hlt">override</span> the stimulatory effects of excess BAFF on mature B cells in vivo.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The selection and maturation of B-cell clones are critically determined by tonic signals from activated B cell receptors (BCR) and survival signals from BAFF cytokine. These finely tuned and coordinated signals provide a net positive signal that can promote the selection, maturation, proliferation and differentiation of a developing B cell. Stimulation with an anti-IgD antibody can also activate BCR but can lead to depletion and an arrest of mature B-cell development in vivo. It is not known whether survival signals from excess BAFF can <span class="hlt">override</span> the suppressive effects of treatment with anti-IgD on mature B cells in vivo. Herein, we examined the effects of co-treatment of BAFF and anti-IgD on the mature B-cell compartment and antibody production in vivo by treating mice with either 1mg/kg BAFF or anti-IgD alone or in combination for 3 consecutive days. We found that co-treatment with anti-IgD significantly abrogated these stimulatory effects of BAFF treatment on splenic CD19+ B cells as well as mature CD19+IgD(hi)IgM+ B cells in vivo. Anti-IgD down-regulated the expression of the BCR complex (mIgM, mIgD and CD19) and the BAFF receptor TACI without regard to the presence of BAFF. Anti-IgD treatment also significantly negated BAFF-induced IgM production in vivo. Both BAFF and anti-IgD could individually stimulate IL-10 synthesis in B cells but did not affect one another. Taken together, our data suggest that activation of BCR with an anti-IgD antibody can <span class="hlt">override</span> the stimulatory effects from excess BAFF on B cell proliferation and antibody production by down-regulating the expression of BCR complex and BAFF receptors. PMID:24954638</p> <div class="credits"> <p class="dwt_author">Nguyen, Tue G; Morris, Jonathan M</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-09-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">325</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004E%26PSL.218..109C"> <span id="translatedtitle">Great earthquakes and slab pull: interaction between seismic coupling and <span class="hlt">plate</span>-slab coupling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Great earthquakes, the few largest earthquakes that account for most of the Earth's seismic energy release, have occurred at only a few subduction zones around the world. Strong locking, or 'seismic coupling', of the interface between <span class="hlt">plates</span> at certain subduction zones is often invoked to explain these great earthquakes. Although past studies have correlated strong seismic coupling with a compressional stress environment that is characterized by back-arc compression and caused by trenchward motion of the <span class="hlt">overriding</span> <span class="hlt">plate</span>, the consequences of this compressional environment for the tectonic forces that drive global <span class="hlt">plate</span> motions are not yet clear. To examine these consequences, we compared subduction zone earthquake magnitudes to tectonically constrained estimates of the degree to which each slab transmits its excess weight as a direct pull force on a subducting <span class="hlt">plate</span>. At seismically uncoupled subduction zones that generate only moderate-sized earthquakes, we find that slabs must transmit nearly their entire upper mantle weight as a pull force on the subducting <span class="hlt">plate</span>. At seismically coupled subduction zones that produce great earthquakes, however, we find that slabs must be nearly completely detached from their subducting <span class="hlt">plates</span>. This suggests that slabs subducting in a compressional environment experience stress-induced weakening that prevents the effective transmission of the slab pull force. Convergent mantle flow above a descending slab that becomes decoupled from its surface <span class="hlt">plate</span> may induce additional surface compression that further locks the subduction zone and leads to additional slab decoupling and detachment. The resulting redistribution of <span class="hlt">plate</span>-driving forces may be responsible for rapid changes in <span class="hlt">plate</span> motion.</p> <div class="credits"> <p class="dwt_author">Conrad, Clinton P.; Bilek, Susan; Lithgow-Bertelloni, Carolina</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">326</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.agu.org/journals/jb/v079/i032/JB079i032p04845/JB079i032p04845.pdf"> <span id="translatedtitle">A Model of Convergent <span class="hlt">Plate</span> Margins Based on the Recent Tectonics of Shikoku, Japan</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Displacements generated by a (viscoelastic finite element) <span class="hlt">plate</span> tectonic model are compared with and found to be compatible with geodetic survey data taken on the island of Shikoku, Japan. The model indicates that prior to the 1946 Nankaid0 earthquake, large vertical displacements occurred along the <span class="hlt">continental</span> slope, increasing in magnitude toward and approaching a maximum of 7 m at the</p> <div class="credits"> <p class="dwt_author">Richard Edward Bischke</p> <p class="dwt_publisher"></p> <p class="publishDate">1974-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">327</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/11048717"> <span id="translatedtitle">The possible subduction of <span class="hlt">continental</span> material to depths greater than 200 km.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Determining the depth to which <span class="hlt">continental</span> lithosphere can be subducted into the mantle at convergent <span class="hlt">plate</span> boundaries is of importance for understanding the long-term growth of supercontinents as well as the dynamic processes that shape such margins. Recent discoveries of coesite and diamond in regional ultrahigh-pressure (UHP) metamorphic rocks has demonstrated that <span class="hlt">continental</span> material can be subducted to depths of at least 120 km (ref. 1), and subduction to depths of 150-300 km has been inferred from garnet peridotites in orogenic UHP belts based on several indirect observations. But <span class="hlt">continental</span> subduction to such depths is difficult to trace directly in natural UHP metamorphic crustal rocks by conventional mineralogical and petrological methods because of extensive late-stage recrystallization and the lack of a suitable pressure indicator. It has been predicted from experimental work, however, that solid-state dissolution of pyroxene should occur in garnet at depths greater than 150 km (refs 6-8). Here we report the observation of high concentrations of clinopyroxene, rutile and apatite exsolutions in garnet within eclogites from Yangkou in the Sulu UHP metamorphic belt, China. We interpret these data as resulting from the high-pressure formation of pyroxene solid solutions in subducted <span class="hlt">continental</span> material. Appropriate conditions for the Na2O concentrations and octahedral silicon observed in these samples are met at depths greater than 200 km. PMID:11048717</p> <div class="credits"> <p class="dwt_author">Ye, K; Cong, B; Ye, D</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-10-12</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">328</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003AGUFM.T32C..06P"> <span id="translatedtitle">Length and Time Scales in <span class="hlt">Continental</span> Drift</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Nonlinear feedback between continents and the mantle through thermal blanketing has long been surmised as a mechanism for <span class="hlt">continental</span> drift and Wilson cycles. Paleomagnetism provides ample evidence for large scale (10,000 km) <span class="hlt">continental</span> motion on time scales of several hundred million years, indicative of large scale mantle circulation. While much has been learned about the interactions between continents and mantle flow from analog and numerical modeling studies in two and three dimensions, a rigorous sensitivity study on the effects of continents in high resolution 3D spherical mantle convection models has yet to be pursued. As a result, a quantitative understanding of the scales of <span class="hlt">continental</span> motion as they relate to relevant fluid dynamic processes is lacking. Here we focus on the effect of <span class="hlt">continental</span> size. Continents covering 30% of the surface are representative of a supercontinent such as Pangea, smaller continents (10% of Earth's surface) are representative of present day Asia, and still smaller continents (3% of Earth's surface) are similar to present day Antarctica. These continents are introduced into simple end-member mantle flow regimes characterized by combinations of bottom or internal heating and uniform or layered mantle viscosity. We find that large scale mantle structure, and correspondingly the large scale displacement of continents, depends not only on mantle heating mode and radial viscosity structure, but also on <span class="hlt">continental</span> size. Supercontinents promote heterogeneity on the largest scales (spherical harmonic degree one), especially when combined with strong bottom heating and a high viscosity lower mantle. Degree one heterogeneities in turn drive cyclical <span class="hlt">continental</span> motion, with continents moving from the hot to the cold hemisphere on time scales of several hundred million years. Smaller continents are unable to initiate degree one convection. As a result, their motion is governed by shorter length and time scales. We apply these insights toward understanding the motion of several continents to study the aggregation and dispersal of <span class="hlt">continental</span> groups.</p> <div class="credits"> <p class="dwt_author">Phillips, B. R.; Bunge, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">329</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/6198169"> <span id="translatedtitle">North Sinai-Levant rift-transform <span class="hlt">continental</span> margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The passive <span class="hlt">continental</span> margin of northern Egypt and the Levant coast formed during the Early mesozoic as the relatively small Anatolia <span class="hlt">plate</span> broke away from northern Africa. The oceanic basin of the eastern Mediterranean and the unusual right-angle bend in the North Sinai-Levant shelf margin are both products of <span class="hlt">plate</span> separation along a rift-transform fracture system, the south arm of Tethys. The north-south trending Levant transform margin is considerably narrower than the east-west trending rift margin of northern Egypt. Both exhibit similar facies and depositional histories through the mid-Tertiary. Analysis of subsurface data and published reports of the regional stratigraphy point to a three-stage tectonic evolution of this passive margin. The Triassic through mid-Cretaceous was marked by crustal breakup followed by rapid rotational subsidence of the shelf margins about hinge lines located just south and east of the present shorelines. Reef carbonates localized on the shelf edge separated a deep marine basin to the north from a deltaic-shallow marine platform to the south and east. In the Late Cretaceous-Early Tertiary, inversion of earlier formed half-grabens produced broad anticlinal upwarps of the Syrian Arc on the shelf margin that locally influenced facies patterns. The episode of inversion corresponds with the onset of northward subduction of the Africa <span class="hlt">plate</span> beneath southern Asia. Beginning in the Oligocene and continuing to the present, there has been renewed subsidence of the North Sinai shelf margin beneath thick, outward building clastic wedges. The source of this large volume of sediment is the updomed and erosionally stripped margins of the Suez-Red Sea Rift and the redirected Nile River.</p> <div class="credits"> <p class="dwt_author">Ressetar, R.; Schamel, S.; Travis, C.J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1985-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">330</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60421893"> <span id="translatedtitle">Estimated oil and gas reserves, Gulf of Mexico Outer <span class="hlt">Continental</span> Shelf and <span class="hlt">Continental</span> Slope</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Remaining recoverable reserves of oil and gas in the Gulf of Mexico Outer <span class="hlt">Continental</span> Shelf and <span class="hlt">Continental</span> Slope have been estimated to be about 2.98 billion barrels of oil and 39.8 trillion cubic feet of gas, as of December 31, 1982. These reserves are recoverable from 468 studied fields under the Federal submerged lands off the coasts of Louisiana and</p> <div class="credits"> <p class="dwt_author">J. E. Hewitt; J. P. Brooke; J. H. Knipmeyer</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">331</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/60664999"> <span id="translatedtitle">Estimated oil and gas reserves, Gulf of Mexico Outer <span class="hlt">Continental</span> Shelf and <span class="hlt">Continental</span> Slope</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Remaining recoverable reserves of oil and gas in the Gulf of Mexico Outer <span class="hlt">Continental</span> Shelf and <span class="hlt">Continental</span> Slope have been estimated to be about 3.41 billion barrels of oil and 43.7 trillion cubic feet of gas, as of December 31, 1983. These reserves are recoverable from 505 studied fields under the Federal submerged lands off the coasts of Louisiana and</p> <div class="credits"> <p class="dwt_author">J. E. Hewitt; J. P. Brooke; J. H. Knipmeyer</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">332</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19880027623&hterms=plate+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dplate%2Bmotion"> <span id="translatedtitle"><span class="hlt">Plates</span> and their motions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Work on <span class="hlt">plate</span> motions published in 1983-1986 and in early 1987 is reviewed. Models for these motions, including global ones for driving forces and local ones for subduction history and back-arc spreading, are addressed. The problem of reference frames, both hotspot and paleomagnetic, is discussed. The assessment of errors in <span class="hlt">plate</span> motion studies is reviewed.</p> <div class="credits"> <p class="dwt_author">Jurdy, Donna M.</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">333</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ntis.gov/search/product.aspx?ABBR=AD839178"> <span id="translatedtitle">Magnitogorsk Armor <span class="hlt">Plate</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ntis.gov/search/index.aspx">National Technical Information Service (NTIS)</a></p> <p class="result-summary">This is a sketch of how the metallurgists at the Magnitogorsk (Magnitka) steel factory in the Soviet Union fulfilled the Soviet Union's need for armor <span class="hlt">plate</span> during World War II. Since no mills for rolling armor <span class="hlt">plate</span> existed in Magnitka before the war, en...</p> <div class="credits"> <p class="dwt_author">Y. Petrov</p> <p class="dwt_publisher"></p> <p class="publishDate">1968-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">334</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/19878127"> <span id="translatedtitle">Polygonal Fresnel zone <span class="hlt">plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The performance of Fresnel zone <span class="hlt">plates</span> having a polygonal boundary between zones has been studied. The contribution of the complex amplitude of each zone is calculated analytically and numerically solved. The case of a continuous phase <span class="hlt">plate</span> is considered as the limit case in performance for each polygonal shape. This performance is compared with respect to the circular case. Also</p> <div class="credits"> <p class="dwt_author">Javier Alda; Francisco Javier González</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">335</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=blue&id=EJ829832"> <span id="translatedtitle">Blue Willow Story <span class="hlt">Plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">In the December 1997 issue of "SchoolArts" is a lesson titled "Blue Willow Story <span class="hlt">Plates</span>" by Susan Striker. In this article, the author shares how she used this lesson with her middle-school students many times over the years. Here, she describes a Blue Willow <span class="hlt">plate</span> painting project that her students made.</p> <div class="credits"> <p class="dwt_author">Fontes, Kris</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">336</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://content.lib.washington.edu/costumehistweb/index.html"> <span id="translatedtitle">Fashion <span class="hlt">Plate</span> Collection</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">There are fashion <span class="hlt">plates</span>, and then there are the exquisite fashion <span class="hlt">plates</span> that constitute the University of Washington Libraries digitized collection. The <span class="hlt">plates</span> were first collected by long-time home economics professor Blanche Payne, who taught at the University from 1927 to 1966. The <span class="hlt">plates</span> come from leading French, American, and British fashion journals of the 19th and early 20th century and they document many stylistic periods, such as the Empire, Romantic, Victorian, and Edwardian. Visitors will want to start by reading an essay on the collection, and then they should feel welcome to browse the collection of over 400 <span class="hlt">plates</span> at their leisure, or to browse the collection by subject. One fascinating aspect of the site is an extended excerpt from the 1913 book "Dame fashion" which comments on the history and transformation of various fashions during the 19th century.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">337</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFM.T14C..04D"> <span id="translatedtitle">Episodic vs. Continuous Accretion in the Franciscan Accretionary Prism and Direct <span class="hlt">Plate</span> Motion Controls vs. More Local Tectonic Controls on Prism Evolution</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Subduction at the Franciscan trench began ?170-165 Ma and continues today off Oregon-Washington. <span class="hlt">Plate</span> motion reconstructions, high-P metamorphic rocks, and the arc magmatic record suggest that convergence and thus subduction were continuous throughout this period, although data for 170 to 120 Ma are less definitive. About 25% of modern subduction zones are actively building an accretionary prism, whereas 75% are nonaccretionary, in which subduction erosion is gradually removing the prism and/or forearc basement. These contrasting behaviors in modern subduction zones suggest that the Franciscan probably fluctuated between accretionary and nonaccretionary modes at various times and places during its 170 million year lifespan. Accumulating geochronologic data are beginning to clarify certain accretionary vs. nonaccretionary intervals. (1) The oldest Franciscan rocks are high-P mafic blocks probably metamorphosed in a subophiolitic sole during initiation of subduction. They yield garnet Lu-Hf and hornblende Ar/Ar ages from ?169 to 147 Ma. Their combined volume is extremely small and much of the Franciscan was probably in an essentially nonaccretionary mode during this period. (2) The South Fork Mountain Schist forms the structural top of the preserved wedge in northern California and thus was apparently the first genuinely large sedimentary body to accrete. This occurred at ?123 Ma (Ar/Ar ages), suggesting major accretion was delayed a full ?45 million years after the initiation of subduction. The underlying Valentine Spring Fm. accreted soon thereafter. This shift into an accretionary mode was nearly synchronous with the end of the Early Cretaceous magmatic lull and the beginning of the prolonged Cretaceous intensification of magmatism in the Sierra Nevada arc. (3) The Yolla Bolly terrane has generally been assigned a latest Jurassic to earliest Cretaceous age. Detrital zircon data confirm that some latest Jurassic sandstones are present, but they may be blocks in olistotromes and the bulk of the terrane may be mid-Cretaceous trench sediments. (4) New data from the Central mélange belt are pending. (5) Detrital zircon ages suggest much of the voluminous Coastal belt was deposited in a short, rapid surge in the Middle Eocene, coincident with major extension, core complex development, volcanism, and erosion in sediment source areas in Idaho-Montana. Rapid Tyee Fm deposition in coastal Oregon occurred at virtually the same time from the same sources. (6) Exposed post-Eocene Franciscan rocks are rare. It is tempting to ascribe subduction zone tectonic events directly to changes in relative motions between the subducting and <span class="hlt">overriding</span> lithospheric <span class="hlt">plates</span>. However, in modern subduction zones, varying sediment supply to the trench appears to be a more important control on accretionary prism evolution and this seems to be the case in the Franciscan as well. Franciscan accretion was apparently influenced primarily by complex <span class="hlt">continental</span> interior tectonics controlling sediment supply from the North American Cordillera (which may in part reflect <span class="hlt">plate</span> motion changes), rather than directly by changes in the motions of tectonic <span class="hlt">plates</span>.</p> <div class="credits"> <p class="dwt_author">Dumitru, T. A.; Ernst, W. G.; Wakabayashi, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">338</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.T43F2740M"> <span id="translatedtitle">The influence of oceanic fracture zones on the segmentation of <span class="hlt">continental</span> margins and the evolution of intra-<span class="hlt">continental</span> rift systems: Case studies from the Atlantic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It has been a long held view that oceanic fracture zones play an important role in the segmentation of <span class="hlt">continental</span> margins and therefore provide a major structural control on their evolution and the development of associated petroleum systems. The geometry of fracture zones reflects the spreading history of the seafloor: subtle changes in <span class="hlt">plate</span> motion causes stress-field reorientation, which in turn results in changes in the orientation of the fracture zone. These changes can introduce strike-perpendicular compression or extension across transform faults; the latter may lead to increased ridge segmentation and the initiation of new spreading centres. We present two examples of secondary fracture zone initiation and disappearance within the Atlantic Ocean between 1) the Atlantis and Kane major fracture zones in the Central Atlantic and 2) the Ascension and Rio de Janeiro fracture zones in the South Atlantic. We investigate the discontinuous nature of these fracture zones by exploring their relationship with major <span class="hlt">plate</span> re-organisation events and seafloor spreading geometry. Using a series of stage reconstruction poles that represent the motion of both North and South America relative to Africa since the initiation of Atlantic seafloor spreading, we have performed a quantitative analysis of spreading directions along major Atlantic fracture zones. Our results demonstrate a notable correlation between the timing of major <span class="hlt">plate</span> reorganisation events and the initiation and disappearance of secondary fracture zones. Such events are clearly recorded in the Atlantic margin stratigraphic record as major unconformities. We are therefore able to interpret fracture zone abundance in terms of palaeo-spreading geometry and the opening history of the Atlantic Ocean. This allows us to make important inferences about the influence of fracture zones on the segmentation and structural control of <span class="hlt">continental</span> margins. Specifically, in our South Atlantic case study, where secondary fracture zones do not extend up to the offshore Angolan and conjugate Brazilian margins, we conclude that small offset transform faulting did not influence the evolution of the <span class="hlt">continental</span> margin as has been previously suggested. On a regional scale, the evolution of the Africa-wide Mesozoic rift system is intimately linked to global <span class="hlt">plate</span> tectonics and to changes in <span class="hlt">plate</span> interactions. On a basinal scale, changes in the orientation of the dominant stress field resulting from <span class="hlt">plate</span> reorganisation have had a clear impact on the deformation history and fault geometries of rift basins. We demonstrate this relationship by correlating the timing of changes in South Atlantic fracture zone geometries and African margin unconformities with major unconformities that are observed in a unified stratigraphy chart for the West and Central African Rift System. We propose a controlling mechanism in which changes in <span class="hlt">plate</span> stress control the effective elastic strength of a <span class="hlt">plate</span>, resulting in a focused change in isostatic response over <span class="hlt">continental</span> margins.</p> <div class="credits"> <p class="dwt_author">Masterton, S.; Fairhead, J. D.; Green, C. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">339</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009GeoRL..3610302E"> <span id="translatedtitle">Gondwana breakup and <span class="hlt">plate</span> kinematics: Business as usual</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A tectonic model of the Weddell Sea is built by composing a simple circuit with optimized rotations describing the growth of the South Atlantic and SW Indian oceans. The model independently and accurately reproduces the consensus elements of the Weddell Sea's spreading record and <span class="hlt">continental</span> margins, and offers solutions to remaining controversies there. At their present resolutions, <span class="hlt">plate</span> kinematic data from the South Atlantic and SW Indian oceans and Weddell Sea rule against the proposed, but controversial, independent movements of small <span class="hlt">plates</span> during Gondwana breakup that have been attributed to the presence or impact of a mantle plume. Hence, although supercontinent breakup here was accompanied by extraordinary excess volcanism, there is no indication from <span class="hlt">plate</span> kinematics that the causes of that volcanism provided a unique driving mechanism for it.</p> <div class="credits"> <p class="dwt_author">Eagles, Graeme; Vaughan, Alan P. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">340</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pbs.org/wgbh/aso/tryit/tectonics/intro.html"> <span id="translatedtitle">Intro to <span class="hlt">Plate</span> Tectonic Theory</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This website from PBS provides information about the <span class="hlt">plate</span> tectonics, the theory that the Earth's outer layer is made up of <span class="hlt">plates</span>, which have moved throughout time. The four types of <span class="hlt">plate</span> boundaries are described and illustrated with animations. The first page of <span class="hlt">plate</span> tectonics also provides a <span class="hlt">plate</span> tectonics activity and information about related people and discoveries.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2008-05-28</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" 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id="NextPageLink" onclick='return showDiv("page_19");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">341</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.T23C2693V"> <span id="translatedtitle">A lithospheric seismic profile across northern Taiwan, from arc-<span class="hlt">continental</span> collision to extension</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Taiwan is one of a few locations where a subduction zone is transitioning to arc-continent collision. The north-south trending Luzon arc, which is built on the Philippine Sea <span class="hlt">Plate</span>, has been <span class="hlt">overriding</span> the Eurasian margin here since the Late Miocene. Shortening of the Eurasian margin lead to the formation of the Taiwan mountain belt. The <span class="hlt">plate</span> boundary is quite complicated in northeastern Taiwan, because the Philippine Sea <span class="hlt">Plate</span> also subducts beneath the Eurasian <span class="hlt">plate</span> along the east-west trending Ryukyu trench. Since the Pleistocene, backarc extension behind the Ryukyu arc in the Okinawa Trough has propagated into the Ilan Plain, a region that previously experienced shortening during collision with the Luzon arc. The deep structure of northern Taiwan can therefore give us insight in the evolution of the orogen from compression to post-collisional collapse. During the 2008 and 2009 field seasons of the TAIGER project we acquired active-source and earthquake seismic data in Taiwan and surrounding oceans to better understand the different stages of arc-continent collision. On the island of Taiwan, explosion seismic, onshore-offshore and marine seismic data constrain the crustal structure along three large east-west transects across the <span class="hlt">plate</span> boundary. In the north, TAIGER transect T6 spans a distance of 360 km from the Taiwan Strait eastward across the Hsuehshan Range and the Central Range, and onto the Ryukyu forearc. Marine seismic data were shot with the R/V Marcus Langseth in the Taiwan Strait and east of Taiwan. Twelve ocean-bottom seismometers from National Taiwan Ocean University (NTOU) recorded seismic refractions offshore, and land-seismic stations from IRIS/PASSCAL recorded airgun shots from the Langseth and 4 large land seismic explosions. These different types of active-source data together provide good spatial coverage for imaging seismic velocity structure across the orogen and the <span class="hlt">plate</span> boundary. The seismic refraction data include crustal turning waves and wide-angle Moho reflections. To improve our constraints on the crustal root beneath Taiwan and on the upper mantle seismic velocity structure we augment this data set with first-arriving phases from 52 local earthquakes that were recorded on the IRIS/PASSCAL instruments during the active-source seismic experiment. With this combined seismic data set we will develop a detailed seismic velocity model along a profile across northern Taiwan and the Ryukyu forearc.</p> <div class="credits"> <p class="dwt_author">Van Avendonk, H. J.; McIntosh, K. D.; Lavier, L. L.; Wu, F. T.; Okaya, D. A.; Kuochen, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">342</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/22422979"> <span id="translatedtitle">A change in the geodynamics of <span class="hlt">continental</span> growth 3 billion years ago.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Models for the growth of <span class="hlt">continental</span> crust rely on knowing the balance between the generation of new crust and the reworking of old crust throughout Earth's history. The oxygen isotopic composition of zircons, for which uranium-lead and hafnium isotopic data provide age constraints, is a key archive of crustal reworking. We identified systematic variations in hafnium and oxygen isotopes in zircons of different ages that reveal the relative proportions of reworked crust and of new crust through time. Growth of <span class="hlt">continental</span> crust appears to have been a continuous process, albeit at variable rates. A marked decrease in the rate of crustal growth at ~3 billion years ago may be linked to the onset of subduction-driven <span class="hlt">plate</span> tectonics. PMID:22422979</p> <div class="credits"> <p class="dwt_author">Dhuime, Bruno; Hawkesworth, Chris J; Cawood, Peter A; Storey, Craig D</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-03-16</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">343</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://web.ics.purdue.edu/~braile/edumod/flipbook/flipbook.htm"> <span id="translatedtitle">Voyage Through Time: <span class="hlt">Plate</span> Tectonics Flipbook</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This activity will enable students to view the breakup of the super-continent Pangaea over the past 190 million years and chart the subsequent movement of land masses, and to better understand <span class="hlt">plate</span> tectonics. Students are provided with copies of map sheets with frames which are reconstructed maps of the land masses that existed on Earth at a specific time. Beginning with frame 20 and working backwards students identify the land masses listed in an available table. By assigning different land masses to different groups, the students will be able to share their results when the flipbooks are completed and several different <span class="hlt">continental</span> movements and tectonic interactions will be illustrated on the different flipbooks. All required maps and tables are provided at this site.</p> <div class="credits"> <p class="dwt_author">Braile, Larry; Braile, Sheryl</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">344</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004AGUFM.S51B0165K"> <span id="translatedtitle"><span class="hlt">Plate</span> convergence along the northern Manila Trench, Taiwan-Luzon region</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Philippine Sea <span class="hlt">Plate</span> <span class="hlt">overrides</span> the Eurasian <span class="hlt">Plate</span> along the east-dipping Manila Trench. From Luzon to Taiwan, the <span class="hlt">plate</span> convergence evolves gradually from normal subduction to collision. Further north, the Taiwan orogen has been created. As evidenced by the earthquakes, the subduction-related earthquakes become diffusive close to Taiwan. The accretionary prism has also become wider toward Taiwan. To understand the transition of the <span class="hlt">plate</span> convergence, we have collected 6 reflection seismic profiles across the Manila Trench between Luzon and Taiwan. The results show that the basement generally displays larger dipping angle in the south than in the north. The trench-fill sediments near the trench have larger quantity in the south than in the north. In the north, the trench-fill sediments have even been uplifted. Structural analysis shows that the crustal structures close to the trench area can be divided into two distinctive sub-areas: the normal fault zone and the proto-thrust zone. The normal fault zone is characterized by the distribution of numerous normal faults in the upper layer of the bent subducting <span class="hlt">plate</span>. When the normal faults approache the trench, they are generally covered by trench-fill sediments. It implies that the normal faults occur at a maximum bending moment of the <span class="hlt">plate</span>. Some normal faults resumes probably due to the strong <span class="hlt">plate</span> convergence near the accretionary prism. The proto-thrust zone is located between the normal fault zone and the frontal thrust of the accretionary prism. Proto-thrust zone contains numerous blind-thrust beneath the trench area. The observation of the proto-thrust zone suggests two tectonic insights. Firstly, the compression of <span class="hlt">plate</span> convergence comes from the base of the decollement and propagates upwards. Alternatively, the blind-thrusts come from the inheritance of the subducting normal faults.</p> <div class="credits"> <p class="dwt_author">Ku, C.; Hsu, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">345</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1996EOSTr..77..255B"> <span id="translatedtitle"><span class="hlt">Continental</span> Rifts: Evolution, Structure and Tectonics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Twenty one “friends of <span class="hlt">continental</span> rifts” wrote <span class="hlt">Continental</span> Rifts: Evolution, Structureand Tectonics. They define the object of their passion as elongate tectonic depressions along which the entire lithosphere has been modified by extension. Strictly speaking, passive margins and highly extended terranes such as the Basin and Range are not included in this definition, but the authors consider them to be related to <span class="hlt">continental</span> rifts. The authors hail from academia and set as their main goal “an improved understanding of the fundamental lithospheric processes of rifting, with primary focus on deep structures and processes associated with rifting.” Consequently, many well-known extensional systems, for example, the North Sea grabens, the Suez Basin, onshore and offshore eastern China, and large areas of southeast Asia, are barely considered. Rift aficionados from the petroleum industry will find very little to interest them in this book.</p> <div class="credits"> <p class="dwt_author">Bally, A. W.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">346</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002Geo....30..411A"> <span id="translatedtitle">How many <span class="hlt">plates</span>?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Herein I address the current number of <span class="hlt">plates</span>, the number there should be, and whether there is a pattern in the <span class="hlt">plate</span> mosaic. Related issues are the optimal sizes and shapes of <span class="hlt">plates</span> and spacings of ridges, trenches, and transform faults. Similar questions arise in studies of foams, bubble rafts, buckyballs, mudcracks, columnar jointing, the tessellation of spheres, and the planforms of convection. In sphere-covering problems, and in dynamic problems, pentagons replace the familiar hexagons. The “ground” state of <span class="hlt">plate</span> tectonics on a homogeneous planet may involve ˜12 <span class="hlt">plates</span> with five nearest and five next-nearest neighbors. The <span class="hlt">plate</span> mosaic may be a self-organized network of <span class="hlt">plates</span> and force chains, which are readily reorganized by stress changes. This paper starts with the premise that the mosaic may have simple and surficial explanations rather than convective or plutonic causes. The study of the tessellation of Earth can be called “platonics” to distinguish it from the idea that the lithosphere necessarily mirrors the planform of mantle convection.</p> <div class="credits"> <p class="dwt_author">Anderson, Don L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">347</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70011433"> <span id="translatedtitle">Earthquakes and <span class="hlt">plate</span> tectonics.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Earthquakes occur at the following three kinds of <span class="hlt">plate</span> boundary: ocean ridges where the <span class="hlt">plates</span> are pulled apart, margins where the <span class="hlt">plates</span> scrape past one another, and margins where one <span class="hlt">plate</span> is thrust under the other. Thus, we can predict the general regions on the earth's surface where we can expect large earthquakes in the future. We know that each year about 140 earthquakes of magnitude 6 or greater will occur within this area which is 10% of the earth's surface. But on a worldwide basis we cannot say with much accuracy when these events will occur. The reason is that the processes in <span class="hlt">plate</span> tectonics have been going on for millions of years. Averaged over this interval, <span class="hlt">plate</span> motions amount to several mm per year. But at any instant in geologic time, for example the year 1982, we do not know, exactly where we are in the worldwide cycle of strain build-up and strain release. Only by monitoring the stress and strain in small areas, for instance, the San Andreas fault, in great detail can we hope to predict when renewed activity in that part of the <span class="hlt">plate</span> tectonics arena is likely to take place. -from Author</p> <div class="credits"> <p class="dwt_author">Spall, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">1982-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">348</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007JGRB..11210402G"> <span id="translatedtitle">Burma <span class="hlt">plate</span> motion</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Plate</span> motion in the Indo-Burmese Arc-Andaman-Sumatra region of Burma <span class="hlt">plate</span> is poorly resolved. This is mainly due to lack of relevant data and complex tectonics of the region. We analyze (1) azimuths of coseismic displacements due to the 2004 Sumatra-Andaman and 2005 Nias earthquakes; (2) estimates of interseismic deformation in the Indo-Burmese Arc, Andaman, Sumatra, and Sagaing Fault regions (all based on GPS measurements); (3) long-term <span class="hlt">plate</span> motion rates across Sumatra Fault System, Sagaing Fault, and Andaman Sea from geomorphological and other geophysical studies, and (4) the earthquake focal mechanisms in the region. We suggest that the SSW motion of Sunda <span class="hlt">plate</span> with respect to Indian <span class="hlt">plate</span> may be partitioned into the dextral strike-slip motion across the Sagaing Fault in the north and Sumatra Fault System in south in the back-arc region, and the arc-normal motion across the Sumatra subduction zone, which becomes oblique in Andaman and southern Indo-Burmese Arc region and dextral in the northern Indo-Burmese Arc region of the fore arc. Under the rigid <span class="hlt">plate</span> approximation, we estimate a pole for India-Burma <span class="hlt">plate</span> pair at 27 ± 1°N, 82 ± 1.1°E with an angular velocity of 0.845 ± 0.12°/Ma and for Burma-Sunda at 22.3 ± 1.1°N, 109.3 ± 2.5°E with an angular velocity of 0.67 ± 0.12°/Ma. Thus the <span class="hlt">plate</span> motion in the northern and southern regions of Burma <span class="hlt">plate</span>, namely, the Indo-Burmese Arc and Andaman-Sumatra Arc, may be explained by a single pole and does not require a boundary between the two.</p> <div class="credits"> <p class="dwt_author">Gahalaut, Vineet K.; Gahalaut, Kalpna</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">349</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2004JPhD...37.2607S"> <span id="translatedtitle">Pixelated neutron image <span class="hlt">plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Neutron image <span class="hlt">plates</span> (NIPs) have found widespread application as neutron detectors for single-crystal and powder diffraction, small-angle scattering and tomography. After neutron exposure, the image <span class="hlt">plate</span> can be read out by scanning with a laser. Commercially available NIPs consist of a powder mixture of BaFBr : Eu2+ and Gd2O3 dispersed in a polymer matrix and supported by a flexible polymer sheet. Since BaFBr : Eu2+ is an excellent x-ray storage phosphor, these NIPs are particularly sensitive to ggr-radiation, which is always present as a background radiation in neutron experiments. In this work we present results on NIPs consisting of KCl : Eu2+ and LiF that were fabricated into ceramic image <span class="hlt">plates</span> in which the alkali halides act as a self-supporting matrix without the necessity for using a polymeric binder. An advantage of this type of NIP is the significantly reduced ggr-sensitivity. However, the much lower neutron absorption cross section of LiF compared with Gd2O3 demands a thicker image <span class="hlt">plate</span> for obtaining comparable neutron absorption. The greater thickness of the NIP inevitably leads to a loss in spatial resolution of the image <span class="hlt">plate</span>. However, this reduction in resolution can be restricted by a novel image <span class="hlt">plate</span> concept in which a ceramic structure with square cells (referred to as a 'honeycomb') is embedded in the NIP, resulting in a pixelated image <span class="hlt">plate</span>. In such a NIP the read-out light is confined to the particular illuminated pixel, decoupling the spatial resolution from the optical properties of the image <span class="hlt">plate</span> material and morphology. In this work, a comparison of experimentally determined and simulated spatial resolutions of pixelated and unstructured image <span class="hlt">plates</span> for a fixed read-out laser intensity is presented, as well as simulations of the properties of these NIPs at higher laser powers.</p> <div class="credits"> <p class="dwt_author">Schlapp, M.; Conrad, H.; von Seggern, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">350</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://serc.carleton.edu/NAGTWorkshops/intro/activities/29360.html"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics Jigsaw</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This activity is a slight variation on an original activity, Discovering <span class="hlt">Plate</span> Boundaries, developed by Dale Sawyer at Rice University. I made different maps, including more detail in all of the datasets, and used a different map projection, but otherwise the general progression of the activity is the same. More information about jigsaw activities in general can be found in the Jigsaws module. The activity occurs in several sections, which can be completed in one or multiple classes. In the first section, students are divided into "specialist" groups, and each group is given a global map with a single dataset: global seismicity, volcanoes, topography, age of the seafloor, and free-air gravity. Each student is also given a map of <span class="hlt">plate</span> boundaries. Their task in the specialist group is to become familiar with their dataset and develop categories of <span class="hlt">plate</span> boundaries based only on their dataset. Each group then presents their results to the class. In the second section, students reorganize into groups with 1-2 of each type of specialist per group. Each new group is given a <span class="hlt">plate</span>, and they combine their different datasets on that one <span class="hlt">plate</span> and look for patterns. Again, each <span class="hlt">plate</span> group presents to the class. The common patterns and connections between the different datasets quickly become apparent, and the final section of the activity involves a short lecture from the instructor about types of <span class="hlt">plate</span> boundaries and why the common features are generated at those <span class="hlt">plate</span> boundaries. A follow-up section or class involves using a problem-solving approach to explain the areas that don't "fit" into the typical boundary types - intra-<span class="hlt">plate</span> volcanism, earthquakes in the Eastern California Shear Zone, etc.</p> <div class="credits"> <p class="dwt_author">Egger, Anne</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">351</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.T33H..05L"> <span id="translatedtitle">Subduction and <span class="hlt">Plate</span> Edge Tectonics in the Southern Caribbean</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The southern Caribbean <span class="hlt">plate</span> boundary consists of a subduction zone at at either end connected by a strike-slip fault system: In the east at the Lesser Antilles subduction zone, the Atlantic part of the South American <span class="hlt">plate</span> subducts beneath the Caribbean. In the north and west in the Colombia basin, the Caribbean subducts under South America. In a manner of speaking, the two <span class="hlt">plates</span> subduct beneath each other. Finite-frequency teleseismic P-wave tomography confirms this, imaging the Atlantic and the Caribbean subducting steeply in opposite directions to transition zone depths under northern South America (Bezada et al, 2010). The two subduction zones are connected by the El Pilar-San Sebastian strike-slip fault system, a San Andreas scale system that has been cut off at the Bocono fault, the southeastern boundary of the Maracaibo block. A variety of seismic probes identify where the two <span class="hlt">plates</span> tear as they begin to subduct (Niu et al, 2007; Clark et al., 2008; Miller et al. 2009; Growdon et al., 2009; Huang et al., 2010; Masy et al., 2011). The El Pilar system forms at the southeastern corner of the Antilles subduction zone with the Atlantic <span class="hlt">plate</span> tearing from South America. The deforming <span class="hlt">plate</span> edges control mountain building and basin formation at the eastern end of the strike-slip system. In northwestern South America the Caribbean <span class="hlt">plate</span> very likely also tears, as its southernmost element subducts at shallow angles under northernmost Colombia and the northern, nonsubducting part underthrusts the <span class="hlt">continental</span> edge. The subducting segment rapidly descends to transition zone depths under Lake Maracaibo (Bezada et al., 2010). We believe that the flat slab produces the Merida Andes, the Perija, and the Santa Marta ranges. The nonsubducting part of the Caribbean <span class="hlt">plate</span> underthrusts northern Venezuela to about the width of the coastal mountains (Miller et al., 2009), where the <span class="hlt">plate</span> edge supports the coastal mountains, and controls continuing deformation.</p> <div class="credits"> <p class="dwt_author">Levander, A.; Schmitz, M.; Niu, F.; Bezada, M. J.; Miller, M. S.; Masy, J.; Ave Lallemant, H. G.; Pindell, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">352</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003E%26PSL.212....1C"> <span id="translatedtitle">Ultrahigh-pressure metamorphism: tracing <span class="hlt">continental</span> crust into the mantle</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">More and more evidence is being discovered in Phanerozoic collision belts of the burial of crustal rocks to previously unsuspected (and ever increasing) depths, presently on the order of 150-200 km, and of exhumation from such depths. This extends by almost one order of magnitude the depth classically ascribed to the metamorphic cycling of <span class="hlt">continental</span> crust, and demonstrates its possible subduction. The pieces of evidence for this new, ultrahigh-pressure (UHP) metamorphism exclusively occur in the form of relics of high-pressure minerals that escaped back-transformation during decompression. The main UHP mineral indicators are the high-pressure polymorphs of silica and carbon, coesite and microdiamond, respectively; the latter often demonstrably precipitated from a metamorphic fluid and is completely unrelated to kimberlitic diamond or any shock event. Recent discoveries of pyroxene exsolutions in garnet and of coesite exsolutions in titanite suggest a precursor garnet or titanite containing six-fold coordinated silicon, therefore still higher pressures than implied by diamond stability, on the order of 6 GPa. The UHP rocks raise a formidable geological problem: that of the mechanisms responsible for their burial and, more pressingly, for their exhumation from the relevant depths. The petrological record indicates that large tracts of UHP rocks were buried to conditions of low T/ P ratio, consistent with a subduction-zone context. Decompression occurred in most instances under continuous cooling, implying continuous heat loss to the footwall and hangingwall of the rising body. This rise along the subduction channel - an obvious mechanical discontinuity and weak zone - may be driven by buoyancy up to mid-crustal levels as a result of the lesser density of the acidic crustal rocks (even if completely re-equilibrated at depth) after delamination from the lower crust, in a convergent setting. Chronological studies suggest that the rates involved are typical <span class="hlt">plate</span> velocities (1-2 cm/yr), especially during early stages of exhumation, and bear no relation to normal erosion rates. Important observations are that: (i) as a result of strain partitioning and fluid channelling, significant volumes of subducted crust may remain unreacted (i.e. metastable) even at conditions as high as 700°C and 3 GPa - with implications as to geophysical modeling; (ii) subducted <span class="hlt">continental</span> crust shows no isotopic or geochemical evidence of interaction with mantle material. An unknown proportion of subducted <span class="hlt">continental</span> crust must have escaped exhumation and effectively recycled into the mantle, with geochemical implications still to be explored, bearing in mind the above inefficiency of mixing. The repeated occurrence of UHP metamorphism, hence of <span class="hlt">continental</span> subduction, through time and space since at least the late Proterozoic shows that it must be considered a common process, inherent to <span class="hlt">continental</span> collision. Evidence of older, Precambrian UHP metamorphism is to be sought in high-pressure granulite-facies terranes.</p> <div class="credits"> <p class="dwt_author">Chopin, Christian</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">353</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1987JVGR...32...35M"> <span id="translatedtitle">Basalt geochemistry and tectonic discrimination within <span class="hlt">continental</span> flood basalt provinces</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Continental</span> flood basalts are usually regarded as a single tectonomagmatic entity but frequently quoted examples exhibit a variety of tectonic settings. In one well-studied, classic, flood basalt province, the Mesozoic Karoo province of southern Africa, magmatism occurred in the following tectonic settings: (a) <span class="hlt">continental</span> rifting leading to ocean-floor spreading in the South Atlantic Ocean (Etendeka suite of Namibia); (b) stretched <span class="hlt">continental</span> lithosphere and rifting not leading directly to ocean-floor formation (Lebombo suite of southeastern Africa); and (c) an a-tectonic, within-<span class="hlt">plate</span>, <span class="hlt">continental</span> setting characterized by an absence of faulting or warping (Lesotho highlands and Karoo dolerites of South Africa). By means of spidergrams of the elements Rb, Ba, Th, Nb, K, La, Ce, Sr, Nd, P, Hf, Zr, Sm, Ti, Tb, Y, V, Ni and Cr, uncontaminated tholeiites from (c) above [i.e. the Lesotho-type <span class="hlt">continental</span> flood basalts (LTCFB)] are compared with mid-ocean ridge basalts (MORB), ocean-island tholeiites (OIT), and tholeiites and calc-alkali basalts from subduction environments. The comparison reveals the LTCFBs are geochemically distinct. The differences are reflected in relative enrichments or depletions of the more incompatible elements (Rb-Ce) to less incompatible elements (Ce-Y), i.e. the overall slope of the spidergrams, and in anomalous enrichments or depletions of one or more of the elements Th, K, Nb, Sr, Ti, Hf, and Zr. The distinctive geochemical character of the Lesotho LTCFBs is interpreted in terms of a lithospheric mantle source for the basalts. This is supported by isotopic data. There are no major geochemical differences between Lesotho CFBs and basalts of the rift-related Etendeka and Lebombo suites, although the latter are somewhat enriched in Rb, Ba and K. However, unlike the Lesotho basalts, the Lebombo and Etendeka basalts are associated with voluminous silicic volcanics or intrusive centres and late-stage dolerites having MORB/OIT (i.e. asthenospheric) geochemical characteristics. The flood basalt/silicic magmatism/late-stage dyke swarm association is characteristic of several rift or thinned lithosphere environments (e.g., Ethiopia, Skye, eastern Greenland) but in many of these the flood basalts have ocean-island basalt (OIT) geochemical characteristics. The Lesotho-type CFB geochemistry is exhibited by the Grande Ronde Basalt of the Columbia River Group (a possible subduction-related flood basalt province) and the basic rocks associated with Mesozoic rifting in the North and South Atlantic. Basalt geochemistry alone is unhelpful in determining the tectonic setting of CFBs although the rift-related environments may be identified by the petrology and geochemistry of the whole igneous suite. A two-source model is proposed for the mantle-derived basic rocks in rift-related CFB provinces. Early enriched basalts are derived from the lithosphere and, following pronounced lithospheric attenuation or rifting, later MORB-like melts are emplaced from the rising asthenosphere. The presence of both Lesotho- and OIT-type geochemical patterns in rift-related CFBs suggests that the lithosphere exhibits different styles of enrichment.</p> <div class="credits"> <p class="dwt_author">Marsh, Julian S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1987-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">354</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.geology.wisc.edu/~chuck/Classes/Mtn_and_Plates/"> <span id="translatedtitle">Mountains and Moving <span class="hlt">Plates</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">These are the lecture notes for a class on <span class="hlt">plate</span> tectonics and mountain building which is taught at the University of Wisconsin-Madison. The course describes the connections between the earth's tectonic <span class="hlt">plates</span>, earthquakes, and its many mountain ranges. Topics include basic geography, the structure of the earth's interior, the relationships between the seismic cycle, volcanism, and <span class="hlt">plate</span> movements, erosion of mountains, and mass wasting. Links are provided to additional resources, including aerial photos of geologic features, an interactive map of geology and topography of the United States, and a glossary.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">355</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://egov.oregon.gov/DSL/SSNERR/docs/EFS/EFS27tectwork.pdf"> <span id="translatedtitle"><span class="hlt">Plate</span> Tectonics at Work</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">This is a brief description of the results of <span class="hlt">plate</span> movement according to the Theory of <span class="hlt">Plate</span> Tectonics. It explains how divergence at the mid-ocean ridges accounts for the discoveries of Harry Hess. The site also refers to the invention of the magnetometer and the discovery of the young age of the ocean floor basalt. It concludes that these are the kinds of discoveries and thinking that ultimately led to the development of the theory of <span class="hlt">plate</span> tectonics and that in just a few decades, have greatly changed our view of and notions about our planet and the sciences that attempt to explain its existence and development.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">356</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://svs.gsfc.nasa.gov/vis/a000000/a002400/a002410/index.html"> <span id="translatedtitle">Farallon <span class="hlt">Plate</span> remnants</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The Rockies are fifteen hundred kilometers, or one thousand miles, to the east. The cause must be the tectonic <span class="hlt">plate</span> that built these mountains. Its name is Farallon. Farallon started off normally enough. It plunged beneath the North American <span class="hlt">Plate</span> at a forty-five degree angle. This process sprouted volcanoes to form the Sierra Nevada in what is now California. Next, mantle motions pulled North America westward over Farallon, and the <span class="hlt">plate</span> scraped along the bottom of the continent - for fifteen hundred kilometers. As North America continued its westward trek, Farallon settled to the bottom of the mantle.</p> <div class="credits"> <p class="dwt_author">Snodgrass, Stuart; Bunge, Hans-Peter</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-03-14</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">357</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2003EAEJA.....8061B"> <span id="translatedtitle">A geodynamic constraint on Archean <span class="hlt">continental</span> geotherms</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Dewey (1988) observed that gravitational collapse appears to currently limit the altitudes of large plateaus on Earth to about 3 to 5 km above sea level. Arndt (1999) summarized the evidence for the failure of large parts of the <span class="hlt">continental</span> crust to reach even sea-level during the Archean. If this property of Archean <span class="hlt">continental</span> elevations was also enforced by gravitational collapse, it permits an estimation of the geothermal gradient in Archean <span class="hlt">continental</span> crust. If extensional (collapse) tectonics is primarily a balance between gravitational power and the power consumed by extensional (normal) faulting in the upper brittle crust, as analysed by Bailey (1999), then it occurs when <span class="hlt">continental</span> elevations above ocean bottoms exceed about 0.4 times the thickness of the brittle crust (Bailey, 2000). Assuming an Archean oceanic depth of about 5 km, it follows that that the typical thickness of Archean <span class="hlt">continental</span> brittle crustal must have been less than about 12 km. Assuming the brittle-ductile transition to occur at about 350 degrees Celsius, this suggests a steep geothermal gradient of at least 30 degrees Celsius per kilometer for Archean continents, during that part of the Archean when continents were primarily submarine. This result does not help resolve the Archean thermal paradox (England and Bickle, 1984) whereby the high global heat flow of the Archean conflicts with the rather shallow crustal Archean geotherms inferred from geobarometry. In fact, the low elevation of Archean <span class="hlt">continental</span> platforms raises another paradox, a barometric one: that continents were significantly below sea-level implies, by isostasy, that <span class="hlt">continental</span> crustal thicknesses were significantly less than 30 km, yet the geobarometric data utilized by England and Bickle indicated burial pressures of Archean <span class="hlt">continental</span> material of up to 10 kb. One resolution of both paradoxes (as discussed by England and Bickle) would be to interpret such deep burials as transient crustal thickening events of duration less than the crustal thermal equilibriation time (about 10 to 30 Ma). Temporary entrainment in the wake of basal eclogite ``sinkers'' might provide such transient burial. Vlaar's (1994) modelling of this eclogite delamination process (tectonically elaborated by Zegers and van Keken (2001)) indicates such sinker events would be significantly shorter than 10 Ma. The topographic re-equilibriation of a hot moho above such a process would be similarly short (Kaufmann and Royden, 1994).</p> <div class="credits"> <p class="dwt_author">Bailey, R. C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">358</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19820016723&hterms=atlantic+drift+continental&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Datlantic%2Bdrift%2Bcontinental"> <span id="translatedtitle">MAGSAT anomaly map and <span class="hlt">continental</span> drift</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Anomaly maps of high quality are needed to display unambiguously the so called long wave length anomalies. The anomalies were analyzed in terms of <span class="hlt">continental</span> drift and the nature of their sources is discussed. The map presented confirms the thinness of the oceanic magnetized layer. <span class="hlt">Continental</span> magnetic anomalies are characterized by elongated structures generally of east-west trend. Paleomagnetic reconstruction shows that the anomalies found in India, Australia, and Antarctic exhibit a fair consistency with the African anomalies. It is also shown that anomalies are locked under the continents and have a fixed geometry.</p> <div class="credits"> <p class="dwt_author">Lemouel, J. L. (principal investigator); Galdeano, A.; Ducruix, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">359</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/146023"> <span id="translatedtitle">Paleozoic <span class="hlt">plate</span>-tectonic evolution of the Tarim and western Tianshan regions, western China</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The <span class="hlt">plate</span>-tectonic evolution of the Tarim basin and nearby western Tianshan region during Paleozoic time is reconstructed in an effort to further constrain the tectonic evolution of Central Asia, providing insights into the formation and distribution of oil and gas resources. The Tarim <span class="hlt">plate</span> developed from <span class="hlt">continental</span> rifting that progressed during early Paleozoic time into a passive <span class="hlt">continental</span> margin. The Yili terrane (central Tianshan) broke away from the present eastern part of Tarim and became a microcontinent located somewhere between the Junggar ocean and the southern Tianshan ocean. The southern Tianshan ocean, between the Tarim craton and the Yili terrane, was subducting beneath the Yili terrane from Silurian to Devonian time. During the Late Devonian-Early Carboniferous, the Tarim <span class="hlt">plate</span> collided with the Yili terrane by sinistral accretional docking that resulted in a late Paleozoic deformational episode. Intracontinental shortening (A-type subduction) continued through the Permian with the creation of a magmatic belt. 21 refs., 7 figs., 1 tab.</p> <div class="credits"> <p class="dwt_author">Yangshen, S.; Huafu, L.; Dong, J. [Nanjing Univ. (China)] [and others</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-11-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">360</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70018843"> <span id="translatedtitle">Tectonic implications of post-30 Ma Pacific and North American relative <span class="hlt">plate</span> motions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">The Pacific <span class="hlt">plate</span> moved northwest relative to North America since 42 Ma. The rapid half rate of Pacific-Farallon spreading allowed the ridge to approach the continent at about 29 Ma. Extinct spreading ridges that occur offshore along 65% of the margin document that fragments of the subducted Farallon slab became captured by the Pacific <span class="hlt">plate</span> and assumed its motion proper to the actual subduction of the spreading ridge. This <span class="hlt">plate</span>-capture process can be used to explain much of the post-29 Ma Cordilleran North America extension, strike slip, and the inland jump of oceanic spreading in the Gulf of California. Much of the post-29 Ma <span class="hlt">continental</span> tectonism is the result of the strong traction imposed on the deep part of the <span class="hlt">continental</span> crust by the gently inclined slab of subducted oceanic lithosphere as it moved to the northwest relative to the overlying continent. -from Authors</p> <div class="credits"> <p class="dwt_author">Bohannon, R. G.; Parsons, T.</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return 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href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a style="font-weight: bold;">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_20");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">361</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..12.6636S"> <span id="translatedtitle">Evolution of the oceanic-<span class="hlt">continental</span> subduction style since the Precambrian</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Plate</span> tectonics is a self-organizing global system driven by the negative buoyancy of the thermal boundary layer resulting in subduction. Although the signature of <span class="hlt">plate</span> tectonics is recognized with some confidence in the Phanerozoic geological record on continents, evidence for <span class="hlt">plate</span> tectonics is less certain further back in time. To improve our understanding of <span class="hlt">plate</span> tectonics on the Earth during the Precambrian, we have to combine knowledge derived from the geological record with results from realistic numerical modeling. In a series of experiments using a 2D petrological-thermomechanical numerical model of oceanic-<span class="hlt">continental</span> subduction we have systematically investigated the dependence of tectono-metamorphic and magmatic regimes at an active <span class="hlt">continental</span> margin on upper-mantle temperature, crustal radiogenic heat production, degree of lithospheric weakening as well as other physical parameters. The model includes spontaneous slab bending, dehydration of subducted crust, aqueous fluid transport, mantle wedge melting, and melt extraction from the mantle resulting in crustal growth. We have identified a first-order transition from a "no-subduction" tectonic regime through a "pre-subduction" tectonic regime to the modern style of subduction. The first transition is gradual and occurs at upper-mantle temperatures between 250-200 K above present-day values, whereas the second transition is more abrupt and occurs at 175-160 K. The link between geological observations and model results suggests that the transition to the modern <span class="hlt">plate</span> tectonics regime might have occurred during the Mesoarchean-Neoarchean time (ca. 3.2-2.5 Ga). In the case of a "pre-subduction" tectonic regime (upper-mantle temperature 175-250 K above present) the <span class="hlt">plates</span> are weakened by intense percolation of melts derived from the underlying hot melt-bearing sub-lithospheric mantle. In such cases, convergence does not produce self-sustaining one-sided subduction, but rather results in shallow underthrusting of the oceanic <span class="hlt">plate</span> under the <span class="hlt">continental</span> <span class="hlt">plate</span>. A further increase in the upper-mantle temperature (> 250 K above present) induces a transition to a "no-subduction" regime where horizontal movements of small deformable <span class="hlt">plate</span> fragments are accommodated by internal strain and even under imposed convergence shallow underthrusts do not form. To better understand the underlying physics of these models we performed an additional series of experiments using similar 2D petrological-thermomechanical numerical model but without hydration, melting and extraction procedures. In these models, we have obtained a similarly abrupt transition from the modern style of subduction to the "no-subduction" regime at the upper-mantle temperature 160-180 K above the present-day values. This temperature is approximately the same as determined in the first set of experiments. The "no-subduction" regime is characterized by ‘dripping-off' of the <span class="hlt">plate</span> tips, most likely because of the small effective viscosity constrast between subducting slab and surrounding mantle. Indeed we do not observe a transitional "pre-subduction" tectonic regime with underthrusting of the oceanic <span class="hlt">plate</span> in these sets of models. This implies critical role of rheological weakening by sublithospheric melts in defining how transition between ancient "no-subduction" stage and modern <span class="hlt">plate</span> tectonic regime occurred in the Earth's history.</p> <div class="credits"> <p class="dwt_author">Sizova, Elena; Gerya, Taras; Kaus, Boris; Brown, Michael; Perchuk, Leonid</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">362</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/12763845"> <span id="translatedtitle">Block rotations and <span class="hlt">continental</span> extension in the central Aegean Sea: palaeomagnetic and structural evidence from Tinos and Mykonos (Cyclades, Greece)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The Aegean Sea, floored by an attenuated <span class="hlt">continental</span> crust, is a Mediterranean-type back-arc basin formed above the subducting African <span class="hlt">plate</span>. We investigated post-12 Ma block rotation in relation to back-arc extension in the area of the western Cyclades (central Aegean Sea). On Tinos island, NW-trending dacitic dikes and a Miocene monzogranite penetrated an Alpine metamorphic series. K?Ar analyses of 6</p> <div class="credits"> <p class="dwt_author">Dov Avigad; Gidon Baer; Ariel Heimann</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">363</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/5187340"> <span id="translatedtitle">Tertiary evolution and petroleum potential of Oregon-Washington <span class="hlt">continental</span> margin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The Oregon-Washington <span class="hlt">continental</span> margin was the site of a deep marginal basin in which more than 7000 m of Tertiary sedimentary and volcanic rocks accumulated. Oceanic basalts of Paleocene to early Eocene age form the basin floor and are interpreted to represent eruptions in an elongate trough formed by rifting of the <span class="hlt">continental</span> margin. Middle Eocene turbidite sandstone overlapped both the oceanic crust and the pre-Tertiary rocks of the Klamath Mountains, thus indicating that suturing of the Coast Range-Olympic terrane to North America was about 50 Ma. Oblique convergence between the Farallon and North American <span class="hlt">plates</span> occurred during most of the middle Eocene to middle Miocene. Sedimentation, punctuated by episodes of volcanism, was essentially continuous in a forearc basin whose axis lay along the present inner <span class="hlt">continental</span> shelf. The oblique interaction between the <span class="hlt">plates</span> was interrupted by two periods of more head-on convergence during the middle late Eocene and late middle Miocene. Thick accretionary melange wedges of Eocene and of late Oligocene to late middle Miocene ages were formed during these strongly compressive episodes. Geochemical analyses indicate that the accretionary melange wedges, which crop out along the west side of the Olympic Peninsula and beneath the adjacent shelf, have the highest potential for oil and gas generation. They are the source rocks for numerous gas seeps and oil and gas shows in exploratory wells, and for the 12,000 bbl of 38.9 /sup 0/ API paraffin-based oil produced from a well drilled on the southwest Washington coast. Potential exploration targets exist where the Eocene and Oligocene-Miocene melanges are underplated to a position beneath the lower Eocene oceanic basalt. Hydrocarbons generated in the melanges could migrate upward into structures in strata that overlie the basalt in the upper <span class="hlt">plate</span>.</p> <div class="credits"> <p class="dwt_author">Snavely, P.D. Jr.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">364</div> <div class="resultBody element"> <p class="result-title"><a target