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The ages of fault events of active faults have been estimated using electron spin resonance ESR signals of siliceous gouges. This technique of ESR method is limited by obtaining only ages that are greater than tens of millennia. So this study focuses on developing a new technique of using calcareous gouges to gain an insight into the ages of latest seismogenic event within the Holocene. For the first time, signal B of the ESR method has been used to estimate the age of the Ushikubi fault from calcareous gouge. This technique proved reliable because the mean age 1. Moreover, isochronal experiment revealed that the gouge did not comprise pure carbonates but consisted of a mixture of calcite and quartz grains. A younger age value would have been obtained if a lower artificial irradiation dose rate and a relatively pure carbonate fault gouge were used in the ED determination.

It is worth noting that to recognize a signal base on its g value only is not sufficient to label a paramagnetic center [ 20 ]. Signals A, B and C are ascribed torespectively. Measurement conditions were: microwave frequency 9.

Because of the difficulties in distinguishing and assigning g values to various paramagnetic defect centers in the samples, isochronal annealing experiments were performed on some of the samples CFG4, CFG2, CFG1 and BVB-5a.

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From the isochronal curves, a decrease in signal intensity occurred in two stages as shown in Fig. This unique behavior in the decay pattern of signal C in the different samples is attributed to the presence of defect center in quartz whose intensity increases with increase in temperature.

The annealing experiment was done in an Isuzu muffle oven.

Fault gouge is a tectonite (a rock formed by tectonic forces) with a very small grain size. Fault gouge has no cohesion and it is normally an unconsolidated rock type, unless cementation took place at a later stage. A fault gouge forms in the same way as fault breccia, the latter also having larger clasts. Fault gouge is the predominant fault rock formed at shallow crustal levels and records important information on the structural and mechanical behavior of fault zones. The dating of fault activity from analyses of fault gouge is a key research topic, as fault dating is useful in earthquake forecasting and site selection for radioactive waste Cited by: 1. Another important development is the use of absolute dating methods in retrograde clay gouges in which clays in a fault develop from igneous or metamorphic wall rocks that contain no clays. In addition, the method has also been shown to be useful at dating folds in fold-and-thrust belts.

The ESR intensity of signal C equally showed a unique behavior. A general decrease in the intensities of signals A and B was equally observed in this sample while that of signal C decreased in two stages as the temperature was increased. The ESR spectra of the artificially irradiated samples East. Neither pre- nor pro-thermal treatment was done on the artificially irradiated samples.

At lower levels of artificial irradiation, the intensities of the different signals were enhanced and there was no growth with increasing irradiation dose implying signal saturation. A decrease in signal intensity was observed in some of the peaks e. Although an increase in signal intensity was observed at a lower dose range, some signals got saturated as the dose was increased. The overall observation in the saturation behavior of some of the signals with increasing dose is summarized in Fig.

Summary of the saturation behavior of the ESR spectra e. When signal intensity does not increase upon addition of artificial irradiation dose, it means signal are saturated. The A, B and C signals are attributed to therespectively [ 1021 ]. The signal C corresponding to the is the most frequently used signals in carbonate dating [ 1021 ].

The slight variation in the temperatures could be as a result of an additional defect center center since the samples contained a mixture of quartz and calcite as shown in the micrograph of Fig. One possible explanation for the variation in the temperature could also be that the samples investigated are different from those previously investigated by other researchers carbonates in fossils, speleothem, fault gouge, etc.

From the isochronal curves Fig. These results are consistent with the observation of Toyoda and Schwarcz [ 7 ] and Ikeya et al. Moreover, at a low to moderate microwave power, its dependency showed a saturation behavior of this peak as shown in Fig.

The defect center in quartz saturates easily at low microwave power as reported by Hataya et al. This signal is not greatly enhanced upon artificial irradiation Fig. The intensity of this signal increased with increasing temperature at the expense of signal B Fig.

The microwave power dependence of this signal shows that this signal does not saturate even at a moderate to high microwave power Fig.

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This observation is supported by the findings of Ikeya et al. This signal is enhanced by artificial irradiation Fig. Signal C saturates at a moderate to high microwave power, while signals A and B do not saturate even at high microwave power. The saturation pattern of the different signals are the same in the different samples investigated, e. However, the degree of saturation varies among different signals in different samples.

To estimate the ESR-based age T ESR of the latest event of the Ushikubi fault using calcareous fault gouge, the equivalent dose ED and the annual dose rate D were key parameters used as stated in [ 10 ].

Dating of fault gouge

The equivalent dose Fig. Although some of the signals showed saturation behavior with increasing dose, the data points were fitted into a simple saturation curve of Eq. Moreover, it is possible to estimate the ED at low added dose since the signals did not show saturation behavior at that level.

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But to better understand the nature of the growth curve, fitting all the data points into a simple saturation growth curve is necessary. However, determining the ED with only three data points will not be enough to come out with a concrete conclusion.

This signal gives a high correlation coefficient when compared with the others. The correlation coefficient in this sample is much more higher than in the other samples.

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The correlation coefficient is higher when compared with sample CFG1. The equivalent dose was obtained by extrapolation to the zero ordinate with the least-square fitting method.

Since the degree of saturation varied between signals in different samples, signal B in the different samples was considered for the estimation of the equivalent dose, which was then used to determine the age of the latest event of the Ushikubi fault. This is because signal B had the highest correlation R 2 coefficient and best fitting when compared with the signals A and C Fig.

More so, Ikeya et al. The correlation coefficient is small as compared to that of signal B. The correlation coefficient of this signal is also small. CFG calcareous fault gouge from the central part of the Ushikubi fault, East. CFG calcareous fault gouge from the eastern part of the Ushikubi fault. The ESR ages for the calcareous gouges were then determined using Eq.

Electron spin resonance dating, or ESR dating, is a technique used to date newly formed materials which radiocarbon dating cannot, like carbonates, tooth enamel, or materials that have been previously heated like igneous shawchapman.comon spin resonance dating was first introduced to the science community in , when Motoji Ikeya dated a speleothem in Akiyoshi Cave, Japan. The central Menderes Massif in western Turkey is a bivergent metamorphic core complex characterised by two detachment faults that operated with opposite sense of shear. Here, we present K-Ar ages and hydrogen isotope data for fault gouge as well as fission track and (U-Th)/He ages for apatite and zircon from bedrock samples to constrain the timing of detachment faulting. Comparison of the K-Ar. The palaeomagnetic properties and magnetic fabric of clay-rich fault gouge in a prominent fault at Porth-y-pistyll on the northern coast of Anglesey, North Wales, have been investigated in an attempt to constrain the age of last movement on this fault. The texture and mineralogy of the gouge has been examined by scanning electron microscopy.

The ages obtained from calcareous gouge from the central part of the Ushikubi fault ranged from 1. Considering no water and radon loss, the ages obtained ranged from 1. By taking the average of the ages obtained from both the central and the eastern part of the Ushikubi fault 1.

Folds and Faults

The observed agreement in the ESR-based calcareous gouge age in this study with the radiocarbon dating suggests that the novel method of using calcareous gouge ESR signal to determine latest event of active faults, which is the focus of this study, is probably a reliable tool for dating active fault events. However, the age obtained in this study is slightly greater than the age obtained through the indirect radiocarbon dating method [ 15 - 17 ]. A relatively younger age value could be obtained if a smaller irradiation dose rate is used.

Although the additive method is a standard method in the field of ESR, a high artificial irradiation dose rate e. Ikeya et al. This observation could be a contributing factor to the relatively older age value obtained in this study. ESR analysis showed that g factors 2.

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Despite the depth-dependent difference in g factors, both the shallow and deep fault gouges showed signals that are indicative of ABand C. Isochronal annealing experiment revealed a unique behavior in the ESR spectra of signal C in both the surface and the core samples in that a decrease in the signal intensity occurred at two stages indicating the presence of another signal the defect centers of quartz. When the samples were irradiated artificially, some of the signals got saturated with increasing dose rate.

Although the degree of saturation varied within signals in different samples, signal B was considered for the estimation of equivalent dose which was then used to determine the age of the latest event of the Ushikubi fault. For the first time, ESR method using signal B has been used to estimate the age of the Ushikubi fault from calcareous gouge. The mean age 1. This proved the effectiveness of the method using calcareous gouge as a dating technique that measured the latest age of the fault activity directly.

Although the age obtained in this study is slightly greater than the age obtained indirectly from radiocarbon dating, a maximum resolution of the latest fault event by this promising method could be obtained if pure carbonate gouge samples and a smaller irradiation dose rate can be used. We are grateful to MEXT for providing logistics during my stay in Japan within the framework of Monbushokagaku scholarship. We sincerely appreciate the Toyama city research group for allowing us to use the core samples in this study.

The assistance given to us by Prof. Shigeru Otoh and Prof.

Fault gouge

Masaaki Shimizu of the University of Toyama in the making of thin sections and the use of X-ray diffractometer, respectively, are greatly acknowledged. Next Article.

Research Article September 01, Fault gouge dating: history and evolution Peter Vrolijk ; Peter Vrolijk. Google Scholar. David Pevear ; David Pevear.

Michael Covey ; Michael Covey. Clay Minerals 53 3 : - Article history received:. ABSTRACT Radiometric dating of fault gouges has become a useful tool for regional tectonics studies and for exploring and understanding fault and earthquake processes. GeoRef Subject. You do not currently have access to this article.

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Thermoluminescence (TL) dates of fault gouge suggest that there have been three episodes of recent fault activity in Hong Kong; these occurred at approximately at , and years BP. TL dating of alluvial sediments also indicates fault activity in the Late Pleistocene. Fault Gouge Dating In The Southern Appalachians Usa, girl im dating has spending problem, luftkampf simulation dating, rencontre handicape gratuit/ The first steps back in the world of dating should not to be taken lightly. You shouldn't attempt Age Dating Fault Gouge to bed new women to Age Dating Fault Gouge take revenge on your ex, whether it's to lure her back with jealousy or as a way to get over her. You should do it because you're a single guy and that's what single guys do.

Peacor for assistance and several Cordilleran geologists for discussion, and the National Science Foundation and ExxonMobil Upstream Research Company for support of our fault gouge research. Correspondence to Ben A. Reprints and Permissions. The dating of shallow faults in the Earth's crust. Download citation. Received : 14 June Accepted : 19 April Issue Date : 12 July Journal of Structural Geology Geological Journal Scientific Reports Geostandards and Geoanalytical Research By submitting a comment you agree to abide by our Terms and Community Guidelines.

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Figure 1: Representative Ar age spectra of clays in samples at the Lewis thrust for three grain size populations. References 1 Murphy, P. Article Google Scholar 2 Kralik, M. Article Google Scholar 4 Eide, E. Article Google Scholar 5 Foland, K. Google Scholar 10 Pevear, D. Google Scholar 12 Fermor, P. Article Google Scholar 13 Constentius, K. Article Google Scholar 14 Wiltschko, D. Google Scholar 15 Vrolijk, P. Article Google Scholar 16 Yan, Y. Google Scholar 22 Pevear, D. Google Scholar 23 Srodon, J.

Google Scholar 24 Grathoff, G. Acknowledgements D.



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