Showing papers in "Journal of Structural Geology in 1986"

TL;DR: In this article, the authors show that duplexes may form at bends on strike-slip faults by a process kinematically analogous to the sequential imbrication of ramps on dip-slink faults.

TL;DR: The geometry of a porphyroclast and its tails can serve as a valuable indicator of the sense of vorticity as discussed by the authors, which can be used as a measure of porphyric properties.

TL;DR: In this paper, the Coulomb-Mohr theory of shear failure is used to rationalize the sequence of faults and three-dimensional geometry of wrench failure. But the model is not suitable for the case of a large number of shears.

TL;DR: In this article, the authors derived an analytical expression that relates the shape of a fault in cross-section to its shape of the bedding horizons in its hanging wall block, assuming that the wall deforms by simple shear and that the footwall remains undeformed throughout.

TL;DR: In this paper, the concept of passive-roof-duplex was introduced and discussed in the Kirthar and Sulaiman Ranges in the Baluchistan Province of Pakistan.

TL;DR: In the case of the Porcupine Creek anticlinorium and the Selkirk fan structure, a reversal in vergence between the bottom and the top of a tectonic wedge has been observed.

TL;DR: In this paper, an attempt to date the individual deformation episodes, over 50 conventional K-Ar and 1140 Ar/39Ar incremental gas release analyses have been carried out on fine grained white micas separated from samples whose structural settings were well known.

TL;DR: In this paper, the part of a mountain front which is visible at the surface consists of foreland-dipping thrust belt rocks elevated above their regional structural position and overlain more or less conformably by molasse.

TL;DR: A broad zone of dominantly ductile high-strain deformation lies beneath the Aguilon nappe in the Sierra Alhamilla, southern Spain this article, which is characterized in outcrop by a distinctive platy foliation and a strong NNE-trending stretching lineation.

TL;DR: In this paper, the authors present two balanced cross-sections of the Canadian Cordillera, based on available structural, petrologic, geophysical and geochronologic data.

TL;DR: In this paper, a detailed mapping of the South Pyrenean zone in the eastern Spanish Pyrenees is presented, showing that a great number of Alpine thrusts affect the basement and the cover.

TL;DR: In this article, the response of boudins to shear is a synthetic flow of those corner volumes lying within the extensional quadrants of the kinematic framework of the deformation into the inter-boudin gaps (Type 1 asymmetrical pull-aparts).

TL;DR: Experimental deformation by pressure solution was performed on an aggregate of small grains subjected to deviatoric stress (50 MPa) for a long time (several weeks or months) at relatively high temperature and pressure in contact with various fluids (air, water, 0.1 to 1 N NaOH for quartz, water and 5% NH 4 Cl for calcite).

TL;DR: In this paper, the authors used field structural data and systematic analysis of the microstructures and the preferred orientations of enstatite and olivine to establish that the peridotites were thrust over continental crust from the WSW to the ENE, in relatively low temperature conditions for the porphyroclastic and mylonitic textures: T ⋍ 900°C) but high enough to lead to syntectonic migmatization in crustal rocks, with identical kinematic signatures on both sides of the contact.

TL;DR: In this paper, the dominant deformation mechanism within foreland thrust sheets is the displacement of blocks of weakly deformed rock on discrete, mineral-coated minor faults, such minor faults are members of families or populations of consistently oriented structures.

TL;DR: In this article, a study of the deformation of a granitic massif indicates a relationship between palaeostress fields and the geometry of microfractures as defined by fluid-inclusion trails.

TL;DR: In this article, a simple geometrical construction is demonstrated for determining the orientations of the principal axes of the infinitesimal strain ellipsoid in tectonic zones where boundaries obliquely converge or diverge.

TL;DR: In this paper, the energy required in duplex formation can be determined by calculating the total work involved in emplacing each horse: this is given by where W t =W p +W b +W g +W i Wp is involved in initiating and propagating a fracture.

TL;DR: In this article, it is shown that a stretching lineation is seen parallel to fold hinges over a range of fold axes orientations of at least 40° in strongly deformed quartz-mica schists from Syros, Greece.

TL;DR: In this article, an integrated microstructural and petrofabric study of the plastically deformed and partially recrystallized Roche Maurice quartzites of Plougastel, western Brittany, has revealed a clear correlation between the pattern of c-axis fabrics displayed by detrital quartz grains and the symmetry of the calculated strain ellipsoid.

TL;DR: In this paper, a simple model for the driving force for grain boundary migration based on dislocation density contrasts, as controlled by intra-grain strains and grain orientations, is proposed and tested, with an 80% success rate for the mobile grain boundaries studied.

TL;DR: The median tectonic line (MTL), the most prominent onshore fault in Japan, demarcates the Cretaceous Hiji quartz dioritic gneiss of the Ryoke belt from the high P/T type Sambagawa metamorphic rocks on the east in the Takato area as discussed by the authors.

TL;DR: In this paper, a line-length balance using massive relatively uncleaved beds (e.g. Knox Group, Southern Appalachians) can be used as a basis for restoring the section, given strain data and cleavage trajectories for individual thrust sheets, providing line lengths and formation areas which can be fitted to the keybed of the undeformed section.

TL;DR: In this paper, a bed-length balance technique is presented to calculate listric normal fault trajectories using roll-over geometry and fault displacements, which can also be applied to subsidiary normal fault fans above a major fault to calculate the major listric fault geometry.

TL;DR: Folds in a single thrust sheet can be classified as trailing edge (formed over footwall ramps), intraplate (due to shortening within the body of the sheet) and leading edge.

TL;DR: In this article, the authors show that with progressive left-lateral displacement on basal left-stepping, en echelon strike-slip faults, an extremely complicated zone of evolving fracture, strain and subsidence patterns develops in the overlying clay.

TL;DR: In this paper, it was shown that the restoration of thrusts to a staircase trajectory has no mechanical significance as the thrust is merely acting as a marker if restored back beyond the time at which it propagated.

TL;DR: The Mondonedo nappe as discussed by the authors is one of the main units in the internal zone of the Hercynian belt in the Iberian Peninsula, and it consists of low to medium grade metasediments, late Precambrian and Palaeozoic in age, folded by large D 1 E-verging recumbent structures, and thrusted several tens of km towards the east during a D 2 deformation episode.

TL;DR: In this article, the orientation of phyllosilicate grains changes discontinuously from being preferentially parallel to bedding to being parallel to cleavage, and crystal imperfections as expressed in layer terminations, low angle grain boundary-like features and other defects decrease in density.

TL;DR: The Osen-Roa thrust sheet of the southern Norwegian Caledonides comprises the coarse clastic late Precambrian Sparagmite region and the folded and imbricated Cambro-Silurian rocks of the Oslo region.