Agree, the fault morphological dating seems excellent
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E-mail: s. Carretier, J-F Ritz, J. Jackson, A. We relate reverse fault scarp morphology formed by several earthquake dislocations to the average deformation rate, using a morphological dating model based on a diffusion analogue of erosion. Our scarp degradation model includes diffusive erosion during the interseismic period, the gravitational collapse of the coseismic fault scarp just after formation, and the variation of the surface rupture location. Interactions between thrusting and geomorphic processes acting on scarp morphology are analysed along the Gurvan Bogd Range in Mongolia.
Downslope Conservation of the Debris Flux A hillslope profile may be thought of as a series of linear segments each receiving debris at its upslope end and discharging debris at its downslope end. If more debris enters a segment than leaves, conservation of mass requires that the debris within the segment must increase, resulting in an increase in the elevation of the segment Figure Conversely, if more debris leaves than enters a segment, its elevation must decrease Figure Thus the downslope change in the debris flux, q, determines the change in elevation at a point on a hillslope.
Abstract. Morphologic dating of fault scarps determines late Cenozoic fault activity by comparing observed topographic profiles with those determined using a calibrated hillslope development model. We postulate that the material transport rate along the profile is a function only of local slope and is cbeebies-games.com by:
Debris will accumulate and the elevation will increase where q decreases downslope, such as at basal concavities. Debris will be depleted and the elevation will decrease where q increases downslope.
In spatial dimension, x, the change in elevation, y, with time, t, on a hillslope profile is therefore equal to the downslope divergence of the debris flux, or Equation Although Eq. Nash b, demonstrated that Eq.
Hanks et al. Hanks and Wallace in press demonstrate that the degradation pattern observed on shoreline scarps formed by Lake Lahontan in western Nevada may be closely modeled with Eq. The model also predicts that the degradation of a transport-limited scarp is not accompanied by retreat, which would explain why the scarps formed during the West Yellowstone earthquake are generally located near the center of much older scarps formed by previous offsets of the same fault Figure The model also successfully predicts the inverse relationship between scarp height and the slope angle documented by Bucknam and Anderson in a study of a degraded fault scarp near Drum Mountain, Utah Nash, b; Colman and Watson, ; Hanks et al.
The crestal convexity and basal concavity become more rounded and the midsection reclines. In the same time that the uppermost horizon of that profile has taken to acquire the mobility necessary for migration, a rock layer of the same thickness throughout has become reduced. At the close of a further equal interval of time, a further layer of rock, again of the same thickness and of equal thickness at every part of the slope, passes over into the reduced form.
Removal of a uniform thickness of loosened debris from the scarp face results in parallel retreat with no rounding of the crestal convexity or basal concavity. The pattern of degradation, however, is dependent on whether the loosened debris accumulates at the base of the scarp or is removed. Accumulation of a Basal Debris Apron As long as debris is swept clear of the base of a scarp, the scarp retreats parallel to itself. This process may be observed on active fluvial cut-banks and wave-cut bluffs.
When undercutting ceases and debris is no longer removed, an apron of debris inclined at a characteristic angle of repose will progressively grow, ultimately burying the retreating scarp face. The first analytical model of parallel retreat with accumulation of a basal debris apron was formulated by Fisher to describe the degradation of coastal chalk cliffs. Fisher's model assumed a vertical scarp face and a horizontal crest and base. Lehmann modified the model to permit the treatment of nonvertical scarp faces and to allow for changes in volume of the debris as it moves from the scarp face to the debris apron.
The model was further modified by Nash a to permit the treatment of scarps with nonhorizontal crests and bases. The pattern of degradation predicted by this model is shown in Figure Note that the model predicts the development of an uneroded, parabolic core of debris beneath the debris apron. Immediately adjacent to the base of the retreating scarp face, the surface of the uneroded core of material is thinly buried and nearly parallel to the overlying surface of the debris apron.
The predicted pattern of degradation of the scarp face is nearly identical to that documented by Wallace for scarps formed during the Yellowstone earthquake Figure It can also be used to explain the origin of the flight of faceted spurs along along the Wasatch Front above the Wasatch Fault noted by Hamblin and Anderson Figures Pediments are bare or thinly veneered bedrock surfaces frequently found at the bases of loosening-limited ranges Cooke and Warren, In numerous areas where the retreating face has been completely or extensively removed and the alluvial cover has been completely stripped away, the pediment the authoritative version for attribution.
He suggested that the noses formed beneath a debris apron that was able to accumulate at the base of the retreating cliff during a prehistoric period of lower sea level. The subsequent rise of the sea to its present level removed the basal debris apron, exposing the uneroded chalk nose. Before this can be done, the initial morphology of a scarp must be accurately estimated and the models must be calibrated.
Neither of these tasks is simple, nor are they even possi the authoritative version for attribution. Although dating can be performed on several different types of scarp underlain by different kinds of materials, the following discussion of fault scarp dating is limited primarily to scarps produced by normal faulting of relatively cohesionless alluvium such as those produced by range-front faulting of alluvial fans in the Basin and Range region of the western United States.
The initial morphology of such scarps can be quite complex. Frequently the fault surface will splay close to the ground surface to produce an assemblage of smaller scarps rather than producing a single scarp.
Repeated faulting often superimposes younger scarps on much older ones. The initial morphology of these complex scarps is difficult or impossible to determine with an accuracy sufficient to permit morphologic dating.
Nash suggested that independent geologic evidence e. The analysis below is for simple scarps. Recently, however, Hanks et al. The retreating free face is progressively buried by a basal apron of debris shed from its surface.
Fault morphological dating
The free face of the retreating scarp is nearly buried compare with Figure Photo courtesy of R. Wallace, U. Subsequent movements of the fault may produce a new scarp before the older scarp is eliminated compare with Figure Initial Morphology of Fault Scarps It is assumed here that the initial morphology consists of a single scarp that offsets a straight crest and base inclined at the prefaulting slope of the fan surface Figure Theoretically, for a purely cohesionless material, a slope cannot exceed Carson,therefore, the initial fault scarp should rapidly recline to.
Instead, a loosening-limited free face is produced that retreats, progressively burying its base with debris. The time necessary for the retreating free face to be completely buried, producing a continuous debris apron that atvaries with.
Wallace found that the free face of most of the fault scarps produced by the earthquake in West Yellowstone are now nearly buried. On the other hand, the free face of the scarp produced by faulting during the Pleasant Valley, Nevada, earthquake is still clearly visible, and Wallace estimated that yr will be required for it to be completely buried.
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The time necessary for the complete burial of the retreating free face may be from seconds to centuries but is probably most often on the order of decades. In the first, the loosening-limited free face retreats. After the free face has been buried, the second, transport-limited stage of degradation begins. Degradation thus proceeds in two stages.
During the first stage, the retreating free face may be described with the loosening-limited model. The second stage begins when the free face has been completely buried by the debris apron. Subsequent degradation of this apron may be described with the transport-limited model Figure Although the scarp retreats during the first stage, the center of the initial free face and the center of the debris apron that it produces are nearly the same, so that future movements of the fault will nearly bisect the debris apron Figures Morphologic Dating of Loosening-Limited Scarps Dating of fault scarps in the initial loosening-limited stage of degradation is simple in principle but difficult in practice: the distance that the free face has retreated from the fault is divided by the rate of scarp retreat.
The accuracy of the calculated age is dependent on the accuracy of the retreat rate used, which varies not only from scarp to scarp but also along a given scarp face. A large variation in the retreat rate along the Pleasant Valley scarp is quite evident; in some locations the free face is still standing immediately adjacent to a fresh-appearing basal graben, while nearby it has been completely buried. Retreat rates are probably a function of variations in the cohesion of the alluvium and of the climate.
It is also likely that rate of retreat varies over relatively short periods of time a great deal of retreat may occur during a particularly severe storm. Despite these limitations, when the effects that underlying material and climate have on retreat rates are understood well enough to permit accurate calibration of the loosening-limited model, it is likely that relatively accurate dates may be derived for some fault scarps in the first, retreating stage of degradation.
Morphologic Dating of Transport-Limited Scarps With the burial of the free face by the basal debris apron, the scarp becomes transport-limited and dating must be based on Eq. The first technique proposed for such dating Nash, a uses the relationship between scarp height and rate of degradation to date the Drum Mountain, Utah, fault scarp observed by Bucknam and Anderson The method requires that a scarp of known age be located nearby and that both are underlain by the same material and show a continuous range of heights along their length.
Morphological dating of cumulative reverse fault scarps: examples from the Gurvan Bogd fault system, Mongolia S. Carretier,1,? J-F Ritz,1 J. Jackson2 and A. Bayasgalan2 1Laboratoire de G?eophysique Tectonique et S?edimentologie, CNRS-UMR, Universit?e Montpellier II, 4, Place Eug'ene Bataillon, Montpellier, cbeebies-games.com by: Quaternary alluvial-fan development, climate and morphologic dating of fault scarps in Laguna Salada, Baja California, Mexico. Quantitative morphological ages of the Laguna Salada fault-scarps, derived from linear diffusive degradation modeling, are consistent with the age of the scarps based on cross-cutting relationships. Cited by: Feb 01, Morphological dating has been applied mainly in the cases of one-event fault scarps, terrace risers (e.g. Nash ; Hanks & Schwartz ; Enzel ) and cumulative normal fault scarps (Avouac & Peltzer ; Nash ). In this paper, we are concerned with estimating slip rates from morphological dating of cumulative reverse fault scarps Cited by:
These requirements greatly limit the applicability of the technique. More flexible methods have subsequently been proposed by Nash bColman and Watsonand Hanks et al. The Nash b method is presented here, but all techniques based on Eq.
As it enters the second, rounding stage of degradation, the scarp is assumed to have a straight midsection at the angle of repose of the underlying debris,separating a straight base and crest equally inclined at an angle ofthe original slope of the faulted fan surface Figure As it degrades, the crestal convexity and basal concavity of the scarp become more rounded but may still be observed beyond the extent of this rounding the authoritative version for attribution.
The midsection of the degraded profile is defined as the straight inflection segment separating the basal concavity from the crestal convexity. The degraded excess midsection slope angle,is defined as the angle by which the inclination of the degraded midsection exceeds.
For hillslopes with horizontal crests and bases i. This relationship Figure According to Figure If t is known then c may be calculated. If c has been calculated for a nearby scarp of known age or has been derived by some other means, t may be calculated. Because the time required for completion of the first, loosening-limited stage of degradation is relatively short rarely more than a few centuriest is generally assumed to be equal to the total age of the scarp. The accuracy of t is dependent on the validity of assuming that a scarp had an initial morphology similar to that shown in Figure Gilbert's contribution to the study of hillslopes.
It is likely that c is a function of underlying material, climate, and scarp ct and thus is highly site specific. Ideally, the value used for c should be derived from a nearby scarp of known age, underlain by the same material, and having the same ct as the scarp to be dated. Pre-Holocene dates are thus suspect, and it is possible that the moderation of climate during the xerotherm yr BP may have been sufficient to have changed c significantly.
This relationship forms the basis of the morphologic dating technique used here for dating transport-limited scarps. If a significant asymmetry of the crestal convexity and basal concavity is observed, dating should be attempted with great caution [slope wash processes probably cannot be modeled with Eq.
Both c and the rate of retreat of a free face are probably a function of factors such as climate, underlying material, and scarp ct and therefore are highly site specific.
Currently, both parameters must be determined from a nearby scarp having the same ct and underlain by the same material as the scarp to be dated generally such a scarp will not be available.
If the effects of climate, material, and ct on the retreat rate and c could be determined accurately, however, appropriate values for either parameter could be estimated by measurement of these factors. To determine these effects, retreat and rounding rates must be found for a large number of dated transport- and loosening-limited hillslopes in various climates, with a variety of cts and underlying materials. The study of initial scarp morphology and rates of retreat of the free face would be helped considerably if a continuous set of photogrammetric quality stereo images were taken at ground level along each scarp immediately after faulting and at yr intervals thereafter.
This set of imagery would also permit future investigators to make measurements of morphologic parameters not considered by the initial investigators. In the first, the steep, loosening-limited free face retreats back, progressively burying itself with a basal apron of debris. The second stage of degradation begins when the free face is completely buried by debris to yield a midsection uniformly inclined at the angle of repose of the debris. Degradation of this transport-limited scarp proceeds by progressive rounding of the basal concavity and crestal convexity and recline of the midsection gradient.
Both the parallel retreat of the free face in the first stage and the rounding of the scarp in the second stage can be described by two simple models. If the initial morphology of the scarp can be accurately estimated and if the models are properly calibrated, they can be used to date a scarp in either stage of degradation. The applicability of morphologic dating is limited by the need to recalibrate the models for each scarp to be dated, currently only possible by analysis of a nearby similar scarp of known age.
With additional investigation, it is likely that the influence that climate, underlying material, and ct have on c and on the rate of retreat will be known with sufficient accuracy that the models can be calibrated directly from measurements of these factors. Morphologic dating is not applicable to all scarps formed by normal faulting of alluvial fans.
Degradation by slope wash cannot be described with either model, so dating of wash eroded scarps should probably be avoided such scarps will often have a more rounded basal concavity than crestal convexity. It is also likely that the pre-Holocene climate was sufficiently different from the present that c was also different, making pre-Holocene dates suspect.
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Morphologic dating should not be applied to fault scarps that cannot be assumed to have had a simple initial morphology comprising an equally inclined crest and base separated by a straight midsection.
Despite these limitations, morphologic dating, when used with considerable care, should prove itself to be a valuable tool for determining the deformational history of areas of active tectonism. Arvid M. Johnson and Thomas C. Hanks are thanked for their critical reviews of this manuscript. Rebecca Chavlot-Talmon is thanked for her assistance with the drafting.
Geol Stud. Brunsden, D. Kesel Slope development on a Mississippi River bluff in historic time, J. Bryan, K. Erosion and sedimentation in the Papago Country, Arizona, U. Anderson Carson, M. Kirkby Hillslope Form and Processes, Cambridge Univ. Press, Cambridge, pp. Colman, S. Watson Cooke, A. Warren Culling, W. Analytical theory of erosion, J. Soil creep and the development of hillside slopes, J. Theory of erosion on soil- covered slopes, J. Davis, W. The geographical cycle, Geogr.
Davison, C. Note on the movement of scree- material, Q. Fisher, O. On the disintegration of a chalk cliff, Geol. Fleming, R. Soil creep in the vicinity of Stanford University, Ph. Gilbert, G. Geology of the Henry Mountains, U. Geographical and Geological Survey, pp. Hack, J. Interpretation of erosional topography in humid regions, Am. Hamblin, W. The age of the top surface of these alluvial fans may be younger than 50 kyr, by analogy with the fans near Elat [Enzel et al.
Other fault scarps interest different parts of the alluvial fans Figure 5, sites 6. Active tectonics along the Wadi Araba-Jordan Valley transform fault. Dec Paolo Galli. A geological study has been carried out along the km long Wadi Araba following the transform fault that separates the Arabian and Sinai-African Plates. Recent movements along this structure affect upper Pleistocene-Holocene deposits and archaeological sites.
Kinematic indicators show sinistral strike-slip and oblique movements, in agreement with the relative motion between the two plates. Other evidence of recent horizontal displacement exists along the Jordan Valley Fault, both on the Dead Sea-Lake Tiberias segment and on the segment north of Lake Tiberias.
Faulting may also occur along shorter subsegments, as shown by bends in the Wadi Araba-Jordan River Fault and by the growth of local compression and extension features. Instrument-recorded seismicity appears to be mainly concentrated along some of these subsegments. A comparison between the observed seismic and field-determined slip rates across the fault indicates possible strain accumulation during the last years. The deposition of several generations of overlapping, superimposed and dissected alluvial fans in lower Wadi Araba is an indicator of continuous uplifting of the eastern granitic horst and the overlying Paleozoic-Mesozoic sedimentary succession, and active intermountain wadis, whose outlets at the horst front were upraised continuously above the floor of Wadi Araba .
Nevertheless, it has been claimed that alluvial fans are considered here an irreplaceable record of neotectonic seismic earthquake along the Wadi Araba-Dead Sea Transform DST , where several minor fault scarps and terrace risers are recorded and attributed to paleo earthquakes  .
The increment of fan slope towards fan head is assigned to sediment buildup and the occurrence of steep normal fault scarps at mountain fronts, which constitutes an indicator of recent uplift in the watershed area. Oct Jan OJG. The area-elevation ratio method was utilized to extract the hypsometric integral values within a GIS environment.
A prominent variation exists in the HC shapes and HI values. Seventeen HCs pertained to the River Jordan and the Dead Sea watersheds evince remarkably upward convex shapes indicating that such drainage basins are less eroded, and at the youth-stage of the geomorphic cycle of erosion. Catchments draining to Wadi Araba are of intermediate HI values 0.
Accordingly, they correspond to a late mature stage of geomorphic development. Additionally, Wadi Nukhaileh yields the lowest HI value 0. High HI values indicate that these watersheds have been subjected to tectonic uplift, down faulting of the Rift and intense rejuvenation.
Fault scarps and terrace risers in the southern Arava, Israel, were analyzed to determine the applicability of morphologic dating through a diffusion modeling approach a) . About Cookies, including instructions on how to turn off cookies if you wish to do so. By continuing to browse this site you agree to us using cookies as described in About Cookies. Remove maintenance message. Morphologic Dating of Loosening-Limited Scarps Dating of fault scarps in the initial loosening-limited stage of degradation is simple in principle but difficult in practice: the distance that the free face has retreated from the fault is divided by the rate of scarp retreat.
Differences in HI values can be attributed to disparity in tectonic uplift rate, base level heights, and mean heights of the River Jordan watersheds, the Dead Sea and Wadi Araba watersheds, and variation in lithology, which caused noticeable differences in rejuvenation processes, and channel incision.
Regression analysis reveals that R2 values which represent the degree of control of driving parameters on HI, are positive and generally low ranging from 0. Such results mean that the height of base level has a significant at 0. It is obvious that the most crucial driving morphometric factor influencing HI values of the Jordan Rift drainage basins, is the height of base level m. On geological data, the slip rate was estimated at 3.
Alchalbi et al. In southeastern Turkey, the NE-trending Antakya Graben forms an asymmetric depression filled by Pliocene marine siliciclastic sediment, Pleistocene to Recent fluvial terrace sediment, and alluvium. Along the Mediterranean coast of the graben, marine terrace deposits sit at different elevations ranging from 2 to m above present sea level, with ages ranging from MIS 2 to Normal faults, which are younger than the sinistral ones, bound the graben's southeastern margin.
The westward escape of the continental Iskenderun Block, delimited by sinistral fault segments belonging to the DSF in the east and the Eastern Anatolian Fault in the north caused the development of a sinistral transtensional tectonic regime, which has opened the Antakya Graben since the Pliocene.
In the later stages of this opening, normal faults developed along the southeastern margin that caused the graben to tilt to the southwest, leading to differential uplift of Mediterranean coastal terraces. Most of these normal faults remain active.
Comparison of morphological dating models for cumulative reverse fault scarps S. Carretier,1 F. Lucazeau, J.-F. Ritz, and H. Philip Laboratoire de Ge?ophysique Tectonique . Scarp morphological dating has proved to be a very useful tool, but unfortunately, as is illustrated in Fig. 1, the solutions are not a unique function of time, rather, they are unique in the product cbeebies-games.com k a narrowly constrained parameter, this would not be a significant problem, but in fact k commonly varies over at least two orders of magnitude in unconsolidated cbeebies-games.com by: Morphological dating of fault scarps has the potential to provide a fast and cost-effective means of determining the spatial and temporal pattern of paleo-seismic events over broad regions. Scarp-morphology dating algorithms are based on diffusion degradation relations but have not been adequately calibrated for sensitivity or repeatability. Using Terrestrial Laser Scanner (TLS) Author: P. Shilpakar, J. S. Oldow.
In addition to these tectonic movements, Pleistocene sea level changes in the Mediterranean affected the geomorphological evolution of the area.
Apr The Antakya Graben, in southeastern Turkey, is a NE-trending asymmetric depression delimited by normal faults in its southeastern part. Pliocene regressive marine siliciclastics, Pleistocene to Recent fluvial terraces and alluvium filled the graben. Along the Mediterranean coast, marine terraces flank both side of the graben at elevations ranging from 2 m to m above present sea level, dating from MIS 2 to MIS Normal faults bounding the southeastern margin caused the graben to tilt southeastward, while an older sinistral fault system that parallels the graben and these faults caused differential uplift of marine terraces on either side of the graben.
Based on these data, we interpret that westward escape of the continental Amanos Block along the sinistral faults within the graben caused the Antakya Graben to open since Pliocene. In the later stages of this opening, the graben tilted southeastward due to normal faults along its southeastern margin.
These faults are still active and produce small to medium earthquakes. In addition to these tectonic movements, eustatic sea level changes in the Mediterranean have controlled the morphological evolution of the region.
Nov James P. McCalpin Alan Nelson. Conference Paper. Jalal Al Dabbeek Radwan el-kelani. The 11 February earthquake ML 5. The earthquake was felt in the Palestinian cities: Jericho, Hebron, Nablus, Ramallah, Bethlehem and Jerusalem but no life loss was reported.
Moreover, few smaller earthquakes followed the Earthquake of 11 February at different locations and times of the same year 7 July ML 4. They mainly felt in the northern part of West Bank especially in Nablus City, although they are not closed to Nablus but because of some site effects factors geological formations, structures etc.
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