Diapiric deformations in the Quaternary deposits of the central Ebro Basin, Spain

1986 ◽  
Vol 123 (1) ◽  
pp. 45-57 ◽  
Author(s):  
J. L. Simón ◽  
A. Soriano
Keyword(s):  
Compressive Stress ◽  
Plastic Flow ◽  
Plastic Material ◽  
Middle Pleistocene ◽  
Normal Faults ◽  
Ebro Basin ◽  
Quaternary Deposits ◽  
Horizontal Compressive Stress ◽  
Tension Cracks ◽  
Fluvial Sedimentation

AbstractFrom a study of 24 outcrops in Neogene and Quaternary deposits of the central Ebro Basin, a number of diapiric deformations have been recognized, two principal types being differentiated: domal or pillow structures, and piercement or intrusive structures. The former are incipient diapirs of gypsum. Piercing structures have reverse faulted contacts not caused by halokinesis; here Neogene marls are the active plastic material, contrasting with the competent behaviour of gypsum. These intrusive structures are viscous diapirs which easily pierce the non-consolidated, low strength Quaternary gravel overburden and submit it to a horizontal compressive stress. As a consequence, reverse faults and flexures develop in it. Generally normal faults and tension cracks do not appear. Underlying gypsum beds are frequently pulled up into diapirs and they constitute the structural core.Density contrast and conditions for plastic flow exist at the marl–gravel boundary. It seems to have been specially common at the time of Quaternary fluvial sedimentation, so that much deformation is synsedimentary. Diapiric phenomena have been very active during early to middle Pleistocene time, becoming weaker afterwards.

Theory and Application of the Parallel-Plate Plastimeter. Part 2

1935 ◽  
Vol 8 (4) ◽  
pp. 587-596 ◽  
Author(s):  
J. R. Scott
Keyword(s):  
Plastic Flow ◽  
Parallel Plate ◽  
Plastic Material ◽  
Compressive Load ◽  
Flow Equation ◽  
Simple Type ◽  
Plastic Properties ◽  
Further Development ◽  
Rubber Stock ◽  
Existing Data

Abstract In Part I (loc. cit.) the behavior of a plastic material in the parallel-plate (Williams) plastimeter was studied, and an expression was deduced showing how the rate of decrease in thickness of the sample during compression depends on the volume of the sample, its plastic properties, the compressive load, and the thickness itself. Subsequently, observations were published which showed that the basic principle adopted in this study was incorrect in certain particulars. Peek (loc. cit.), using these observations as a basis, deduced a new expression for the rate of decrease in thickness, though this is too complex for convenient practical use, except in an approximate simplified form. It has now been shown that the expression deduced in Part I, in spite of the inaccurate basis used, is sufficiently near to the truth to render substantially correct the conclusions there stated concerning the plastic properties of unvulcanized rubber stocks. By adopting the more accurate basis used by Peek, moreover, expressions for the rate of decrease in thickness can be deduced for materials showing more complex types of plastic flow than that considered in Part I or by Peek; this had proved impossible by the method previously used. The expression obtained by Peek for the simple type of plastic flow, as well as those now deduced for the more complex types, can be expressed in a form that furnishes a simple and rapid method of examining and analyzing experimental results. As a result of the work described in this paper, it is thus possible to determine, from results obtained with the parallel-plate plastimeter, whether or not a material such as unvulcanized rubber stock exhibits any of the types of plastic flow represented in the general form by Equation 1, and, if so, to find the values of the plastic constants of the material. The procedure is similar to that described in Part I, and consists simply in comparing, by superposition, a set of standard curves drawn on transparent paper with the curve plotted from experimental data. This further development of the method of studying plastic properties by means of the parallel-plate plastimeter should greatly increase its utility as an instrument of research. It has not yet been possible to apply the new method to a systematic study of rubber stocks, but from an examination of existing data it appears that these stocks, tested at 90° C., agree approximately with various forms of the generalized plastic flow equation already referred to.

Pleistocene Terraces of the Alto Henares (Guadalajara), Spain

1972 ◽  
Vol 2 (4) ◽  
pp. 473-486 ◽  
Author(s):  
Bruce G. Gladfelter
Keyword(s):  
Radiocarbon Dating ◽  
Drainage System ◽  
Middle Pleistocene ◽  
Ebro Basin ◽  
Lower Paleolithic ◽  
Lower Pleistocene

A suite of four terraces in the upper Rio Henares drainage system (Rio Tajo basin) now provides a partial geomorphological link between the Middle Pleistocene, Lower Paleolithic archeological sites at Ambrona and Torralba (upper Ebro basin) and those in the vicinity of Madrid. The Campiña and Low Terrace features are shown by radiocarbon dating to be of Holocene and Würm ages, respectively, while the Middle and High Terraces are best designated as being Middle and Lower Pleistocene ages, respectively. Stratigraphic relationships between the upper and lower Rio Henares segments need to be established.

Rubber Plastometer with Uniform Rate of Shear—Shearing-Cone Plastometer

1946 ◽  
Vol 19 (3) ◽  
pp. 822-831 ◽  
Author(s):  
G. H. Piper ◽  
J. R. Scott
Keyword(s):  
Plastic Flow ◽  
Mechanical Design ◽  
Plastic Material ◽  
Edge Zone ◽  
Uniform Rate ◽  
Wide Range

Abstract A new shearing-cone plastometer, suitable for investigating the plastic-flow relations of highly viscous materials over a wide range of stress, is described. A mushroom-shaped rotor, having upper and lower surfaces of conical type, is rotated in the plastic material contained in a cylindrical mould. With this type of shearing surface the rate of shear is uniform throughout the material, except for a small edge zone, thus overcoming some disadvantages of previous plastometers. The mechanical design is based on the Mooney shearing-disk plastometer except that provision is made for a wide range of speeds of rotation.

scholarly journals Late Quaternary Fluvial Sedimentation in the Voidomatis Basin, Epirus, Northwest Greece

1991 ◽  
Vol 35 (1) ◽  
pp. 103-115 ◽  
Author(s):  
John Lewin ◽  
Mark G. Macklin ◽  
Jamie C. Woodward
Keyword(s):  
Mediterranean Basin ◽  
Late Quaternary ◽  
Radiometric Dating ◽  
Middle Pleistocene ◽  
The Mediterranean ◽  
Fluvial Sedimentation ◽  
The Mediterranean Basin

AbstractDetailed morpho- and lithostratigraphic investigations, allied with radiometric dating, in the Voidomatis basin, Epirus, northwest Greece, have identified four Quaternary terraced alluvial fills that range from middle Pleistocene to historic in age. Major-periods of alluviation during the late Quaternary were associated with valley glaciation (ca. 26,000–20,000 yr B.P.) and subsequent deglaciation (ca. 20,000–15,000 yr B.P.) in the Pindus Mountains during Late Würmian times, and more recently linked to overgrazing sometime before the 11th century AD. The late Quaternary alluvial stratigraphy of the Voidomatis River is more complex than the “Older Fill” and “Younger Fill” model outlined previously, and it is suggested that these terms should no longer form the basis for defining alluvial stratigraphic units in the Mediterranean Basin.

Simultaneous Middle Pleistocene eruption of three widespread tholeiitic basalts in northern California (USA): Insights into crustal magma transport in an actively extending back arc

Geology ◽  
2020 ◽  
Vol 48 (12) ◽  
pp. 1216-1220
Author(s):  
Drew T. Downs ◽  
Duane E. Champion ◽  
Patrick Muffler ◽  
Robert L. Christiansen ◽  
Michael A. Clynne ◽  
...  
Keyword(s):  
Magma Ascent ◽  
Middle Pleistocene ◽  
Normal Faults ◽  
Northern California ◽  
Spatially Distributed ◽  
Dry Lake ◽  
Eruption Age ◽  
Tectonic Settings ◽  
Back Arc ◽  
Crustal Magma

Abstract Mapping and chronology are central to understanding spatiotemporal volcanic trends in diverse tectonic settings. The Cascades back arc in northern California (USA) hosts abundant lava flows and normal faults, but tholeiitic basalts older than 200 ka are difficult to discriminate by classic mapping methods. Paleomagnetism and chemistry offer independent means of correlating basalts, including the Tennant, Dry Lake, and Hammond Crossing basalt fields. Paleomagnetic analysis of these chemically similar basalts yield notable overlap, with statistical analysis yielding 7 chances in 1,000,000 that their similar mean remanent directions are random. These basalts also have overlapping 40Ar/39Ar ages of 272.5 ± 30.6 ka (Tennant), 305.8 ± 23.9 ka (Dry Lake), and 300.4 ± 15.2 and 322.6 ± 17.4 ka (Hammond Crossing). Chemical and paleomagnetic analyses indicate that these spatially distributed basalts represent simultaneous (<100 yr uncertainty) eruptions, and thus we use 305.5 ± 9.8 ka (weighted mean) as the eruption age. Their vents align on a N25°W trend over a distance of 39 km. Tennant erupted the largest volume (3.55 ± 0.75 km3) at the highest elevation; both factors decay to the south-southeast at Dry Lake (0.75 ± 0.15 km3) and Hammond Crossing (0.15 ± 0.05 km3). We propose vertical magma ascent beneath the Tennant vent area, where the most evolved, high-SiO2 magma erupted, with lateral dike propagation in the brittle crust. Propagation was near orthogonal to east-west extension (0.3–0.6 mm/yr) along north-northwest–trending normal faults.

Quantitative reconstruction of landscape dynamics and tectonics from sediment calibre and architecture: an example from the Kerinitis megadelta, Gulf of Corinth, Greece

2020 ◽  
Author(s):  
Daniel Hobley ◽  
Alexander Whittaker
Keyword(s):  
Grain Size ◽  
Middle Pleistocene ◽  
Normal Faults ◽  
Sudden Increase ◽  
Level Control ◽  
Data Set ◽  
Accommodation Space ◽  
Gulf Of Corinth ◽  
Climatic Environment ◽  
Climatic History

<p>In tectonically active landscapes, fault movement drives both the creation of accommodation space (i.e., basins), and the production of topography on which geomorphic processes act (i.e., mountains). The action of fluvial processes on those mountains will route eroded sediment into the basins; in many extensional mountain belts, this leads to the deposition of coarse alluvial fans or Gilbert deltas in the hanging-walls of normal faults as they slip and create accommodation space. The stratigraphic architecture and sedimentary characteristics of such deposits clearly respond to and thus in principle can record the tectono-climatic environment controlling the system. This implies that key stratigraphic variables, such as grain size and unit thicknesses, can be quantitatively inverted to recover a tectono-climatic history. However, confounding variables also active in erosional-depositional systems (e.g., far-field base level control, stochastic processes, signal degradation during transport) may complicate attempts to decode this archive and may buffer or shred tectono-climatic signals before they are preserved.</p><p>The well-exposed early to middle Pleistocene deltaic stratigraphy of the Corinth Rift, central Greece, provides a rare opportunity to test these ideas quantitatively. Here, we present a preliminary data set attempting to decode the geomorphic and hence tectono-climatic history of a key section of the rift directly from the grain size and architecture of a very large (~500 m thick), fault controlled, and now uplifted Gilbert delta in the Kerinitis valley, located on the southern margin of the Gulf of Corinth. We used a series of high-resolution drone surveys to obtain 27 vertical transects through the incised delta, from which detailed grain size and sediment thickness data were obtained from photogrammetric analyses (~10,000 images). Our data enabled us to produce a highly detailed correlation of stratal horizons within the deltaic package, from which we were able to describe the evolution of grain size trends both downstream and through the ca. 800 ky lifespan of the delta. We are able to resolve a marked acceleration of the driving fault from the delta stratigraphy itself, which is recorded in a sudden increase in downstream fining rate, driven by more rapid extraction of sediment from the river supplying material to the delta. The timing of this increase correlates with independent constraints from stratigraphic form on the onset of “rift climax” in this delta. Post fault acceleration, we demonstrate that the fining rates begin to fall back, consistent with transient response to tectonic perturbation in the upstream catchment and with a wave of incision sweeping up through the terrestrial system. Our results demonstrate that sophisticated insights into fault evolution can be drawn from deltaic stratigraphy, and emphasise the importance of transient landscape response in creating rift zone sedimentary archives.</p>

Corrosion Assessment Method Validation for High-Grade Line Pipe

2010 ◽  
Author(s):  
Michael Besel ◽  
Steffen Zimmermann ◽  
Christoph Kalwa ◽  
Theo Ko¨ppe ◽  
Andreas Liessem
Keyword(s):  
Plastic Flow ◽  
Predictive Accuracy ◽  
Plastic Material ◽  
Assessment Method ◽  
Burst Pressure ◽  
High Grade ◽  
Line Pipe ◽  
Corrosion Defect ◽  
Von Mises Plasticity ◽  
Grade Steel

The present paper deals with the pressure containment and deformation capacity of corroded high-grade steel line pipe. Firstly, some well established models are investigated concerning their predictive accuracy if applied to high-grade line pipe steel. In particular, it will be shown that all models under consideration tend to overestimate the remaining strength in the case of high-grade steel pipes. Afterwards, FE-analyses are performed in order to study the local evolution of plastic flow in the area of the corrosion defect; at the same time, the burst pressure is predicted applying von Mises plasticity and a simple failure criterion. Although different defect geometries are associated with well pronounced differences in the evolution of the plastic flow around the corrosion defect no significant effect on the burst pressure is found. Finally, the main results of a hydrostatic burst test performed on a pristine X100 line pipe joint are presented. It appears that the material under consideration seems to have anisotropic plastic material properties which may have effect on burst pressure.

Dissolution collapse of a growing diapir from radial, concentric, and salt-withdrawal faults overprinting in the Salinas de Oro salt diapir, northern Spain

2017 ◽  
Vol 87 (2) ◽  
pp. 331-346
Author(s):  
Jesús Guerrero
Keyword(s):  
Fracture Pattern ◽  
Salt Diapir ◽  
Normal Faults ◽  
Northern Spain ◽  
Concentric Ring ◽  
Quaternary Deposits ◽  
Ring Fracture ◽  
Active Salt ◽  
Roof Strata ◽  
Salt Flow

AbstractA geomorphic investigation of the Salinas de Oro salt diapir in the Pyrenees reveals that the ring fracture pattern related to the karstic collapse of the diapir crest may vary significantly depending on the rates of dissolution and salt flow, and the rheology of the overburden. The salt diapir has well-developed concentric faults related to salt dissolution subsidence throughout the Quaternary. Roof strata accommodate subsidence by a combination of downward sagging and brittle collapse leading to the development of a ring monocline that is broken by 5 to 20 m throw conjugated normal faults and a 40 m throw, 9.5-km-long and 200-m-wide keystone graben. The salt diapir top has >100-m-long sinkholes that coalesce to form hollows >70 m deep. Up to 3-km-long radial grabens with a 70 to 90 m vertical throw overprint concentric-ring faulting and displace Quaternary deposits demonstrating active salt flow and diapir rise. Radial faults are linked with salt-withdrawal faults of the Andia Fault Zone (AFZ). Salt flow from the AFZ into the Salinas de Oro salt diapir causes brittle gravitational extension of limestone strata leading to a sequence of grabens and Quaternary faults >10 km long and several hundred meters deep.

The quaternary deposits of central Leicestershire

1968 ◽  
Vol 262 (1131) ◽  
pp. 459-509 ◽  
Keyword(s):  
Surface Expression ◽  
Normal Faults ◽  
Quaternary Deposits ◽  
River Terraces ◽  
North Eastern ◽  
Local Equivalent ◽  
Sand And Gravel ◽  
Weichselian Glaciation ◽  
Eemian Interglacial ◽  
North Western

A programme of mapping and augering has shown the glacial drifts of central Leicestershire to consist of a basal sand and gravel overlain by a complex succession of tills and interbedded waterlaid sediments. The tills display a transition from materials of predominantly north-western derivation to those of north-eastern derivation. Arguments are adduced by which the succession is correlated with that described by Shotton in Warwickshire, and it is concluded that the vast majority of the drifts belong to the Saalian glaciation. A widespread but discontinuous horizon of sand and gravel is believed to denote a temporary melt phase in the middle of the glaciation, while more limited beds of stoneless silt and clay betoken still-water sedimentation which, south of Leicester, is regarded as the local equivalent of the lacustrine Wolston clay of Warwickshire. Although the bedrock surface over most of central Leicestershire has a form consistent with an origin by normal stream erosion, there remain a number of areas where it is difficult to sustain such an interpretation. At Narborough excavations and augering have revealed virtually the full drift succession cut by a series of normal faults traceable over a distance of at least a mile. Near these faults there is evidence of an enclosed depression scored into bedrock and filled with water-laid drift. Although subsequent to the deposition of the drift, the faults have no surface expression at the present time, the structures being truncated by an early post-glacial erosion surface. Later phases in the post-glacial evolution of the Soar and Wreak valleys are associated with a suite of river terraces which, from their included fauna, span the period of the Eemian interglacial and the Weichselian glaciation.

scholarly journals Regional tectonic stress near the San Andreas fault in central and southern California

2021 ◽  
Author(s):  
John Townend ◽  
M Zoback
Keyword(s):  
Compressive Stress ◽  
San Francisco ◽  
Southern California ◽  
San Andreas Fault ◽  
Horizontal Stress ◽  
Tectonic Stress ◽  
Bay Area ◽  
San Andreas ◽  
Regional Tectonic ◽  
Horizontal Compressive Stress

Throughout central and southern California, a uniform NNE-SSW direction of maximum horizontal compressive stress is observed that is remarkably consistent with the superposition of stresses arising from lateral variations in lithospheric buoyancy in the western United States, and farfield Pacific-North America plate interaction. In central California, the axis of maximum horizontal compressive stress lies at a high angle to the San Andreas fault (SAF). Despite relatively few observations near (±10 km) the fault, observations in the greater San Francisco Bay area indicate an angle of as much as 85°, implying extremely low fault strength. In southern California, observations of stress orientations near the SAF are rotated slightly counter-clockwise with respect to the regional field. Nevertheless, we observe an approximately constant angle between the SAF and the maximum horizontal stress direction of 68 ± 7° along ∼400 km of the fault, indicating that the SAF has moderately low frictional strength in southern California. Copyright 2004 by the American Geophysical Union.

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