A critique of vorticity analysis using rigid clasts
Book 1 of Lithology
Language: English
38.01.00=General Geology 38.15.00=Lithology 38.17.00=Tectonics 41.15.00=Astrometry Lithology actual wks acute angle analysis analysis method analytical solution angular velocity apophysis arc arc method aspect ratio axis black dash bouchez boundary brc method bulk carter cartesian cartesian coordinate cartesian plot case china series circle clast clast align clast apophyses clast generated clast plotted clast rotates clast rotation clast shape clast start common practice completely characterize constructed coordinate correctly identied deformation deformation advance ductile ductile extrusion eds eld elds elsevier estimated estimated vorticity estimated vorticity number extrusion model fabric fabric evolution frassi geological geology geophysics hyperbola ildefonse initial orientation interface slip intermediate intrinsic uncertainty jeffery jefferys theory jiang jiang journal johnson journal journal structural journal structural geology kinematic kinematic vorticity kinematics koukouvelas law large uncertainty law london long axis mancktelow marques mechanical interaction method modeling modeling result monoclinic monoclinic ows monoclinic symmetry motion mxy natural natural shear nite deformation nite strain number numerical numerical experiment numerical modeling open circle orientation original width paper parallel particle passchier paul pennacchioni plane plane straining plane-straining plot plotted polar coordinate polar plot porphyroclast pure shear quartz lpo ramberg ramberg passchier ramsay random number range ratio rcrit rcutoff reach reach parallelism reference frame result reviews reviews geophysics rigid rigid clast rigid inclusion rigid particle rock rock reviews rotate permanently rotates permanently rotating rotating clast rotation rotation behavior rotation path rotation sense royal society rst plot sarkarinejad schmid science shape shape fabric shear shear plane shear zone shearing signicantly differ simple simple shear simple shearing simpson solid branch special case stabilized stabilized clast stable stable orientation stable position steady strain straining structural structural geology sullivan symbols symmetry symmetry axis tectonic evolution tectonophysics theoretical rcrit theory transpression truesdell tullis type type clast uncertainty uncertainty large vector viscous vorticity vorticity analysis vorticity number vorticity vector wallis wenk wide range williams williams lin xypolias zhang zone
Published: Dec 31, 2010
Description:
_Journal of Structural Geology 33 (2011) 203e219_ _Contents lists available at ScienceDirect_ _Journal of Structural Geology_ _journal homepage: www.elsevier.com locate jsg_ _A critique of vorticity analysis using rigid clasts_ _Changcheng Li*, Dazhi Jiang_ _Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada N6A 5B7_ _article info_ .Article history: Received 15 January 2010 Received in revised form 24 June 2010 Accepted 2 September 2010 Available online 15 September 2010 _Keywords: Monoclinic flow Rigid clast Shear zone Transpression Vorticity number Vorticity analysis_ _abstract_ _Estimating the kinematic vorticity numbers from rock fabrics presents many problems. In this paper we use numerical modeling to investigate the reliability of those widely-used vorticity analysis methods using rigid clasts. We use very simple flows (steady state homogeneous and having monoclinic symmetry) to represent plane-straining zones and transpressional zones and assume that the rotation of rigid clasts perfectly obeys the theory of Jeffery (1922, Proceedings of the Royal Society of London A102, 161e179). These are assumptions made in current vorticity analysis using rigid clasts. Even with these simple assumptions our modeling shows that the current methods have intrinsic uncertainties so large that it is pointless to use the estimated vorticity numbers to constrain shear zone boundary conditions and kinematics. It is perfectly consistent with numerical modeling results if the currently reported vorticity numbers estimated from rigid clasts (in the range of 0.50e0.85) are all interpreted as being from natural shear zones with close-to-simple-shearing flows. The large uncertainties arise because the motion of rigid clasts is intrinsically a three dimensional problem._ _© 2010 Elsevier Ltd. All rights reserved._ Ключевые слова: random number, actual wks, aspect ratio, zhang, signicantly differ, ramsay, nite deformation, kinematic, black dash, kinematics, boundary, polar plot, shear zone, koukouvelas law, nite strain, science, ?ow, rotation behavior, vorticity vector, rotation path, stabilized, transpression, china series, type, sc, symmetry, reference frame, xypolias, zone, plane, elds, shear, rst plot, ratio, journal structural, law, elsevier, jeffery, wallis, simple, rock reviews, initial orientation, number, angular velocity, clast generated, vorticity number, correctly identied, arc method, plotted, mxy, deformation advance, mancktelow, common practice, modeling, range, analytical solution, ildefonse, ?ows, jiang journal, apophysis, ductile, rigid particle, shear plane, structural geology, shape, bouchez, stable position, orientation, theory, london, completely characterize, rigid clast, rotate permanently, shearing, rock, plane straining, truesdell, symmetry axis, schmid, jefferys theory, vorticity analysis, steady, motion, estimated vorticity, stabilized clast, clast plotted, geology, arc, symbols, clast align, rcutoff, analysis method, geophysics, rotating clast, simpson, uncertainty, numerical experiment, method, sullivan, wks, particle, brc method, shape fabric, large uncertainty, constructed, deformation, ?nite, ductile extrusion, analysis, sarkarinejad, rotating, large, acute angle, simple shearing, intrinsic uncertainty, reviews geophysics, eds, cartesian, clast rotation, journal structural geology, vns, reviews, strain, rcrit, rotation sense, rotation, royal society, plot, fabric, simple shear, clast shape, eld, monoclinic ows, solid branch, paper, cartesian coordinate, paul, uncertainty large, plane-straining, passchier, tectonophysics, long axis, original width, ax, rotates permanently, bulk, tectonic evolution, polar coordinate, clast start, rigid inclusion, williams lin, ramberg, numerical modeling, clast rotates, estimated, quartz lpo, porphyroclast, straining, frassi, intermediate, circle, special case, result, williams, interface slip, vector, stable orientation, tullis, ?nite strain, numerical, monoclinic symmetry, axis, estimated vorticity number, hyperbola, clast apophyses, geological, extrusion model, vorticity, wide range, stable, clast, natural shear, journal, natural, pure shear, theoretical rcrit, reach parallelism, carter, marques, li, reach, structural, wenk, kinematic vorticity, modeling result, type clast, fabric evolution, parallel, general, monoclinic, mechanical interaction, jiang, coordinate, case, rigid, open circle, johnson, ramberg passchier, pennacchioni, viscous, cartesian plot