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1.
电子自旋共振（ESR）是一种对断层物质、燧石、火山灰和沉积物（水系、风成、冰川）定年的重要方法,它广为接受的测年范围为第四纪。对断层泥和沉积物样品,石英ESR信号的不完全归零往往使ESR年龄偏老,多重ESR中心法和颗粒大小“平顶判据”是判断信号归零特征的两种有效方法。为将ESR测年范围拓展至前第四纪,通常采用石英氧空位在加热转化后极大增强的E’心作为测年信号,但由于石英氧空位形成转化机理不明确,加热后增强的ESR信号与地质年龄的相关性有待进一步验证。近期研究表明石英ESR的封闭温度为49 ℃～82 ℃,可在比磷灰石（U-Th）/He更低的温度区间内研究地球近地表的构造演化过程。释光技术热年代学研究发展迅速,与之测年原理接近的ESR在低温热年代学领域展现了良好的应用前景,它与释光及磷灰石（U-Th）/He可相互比对、共同提高地球近地表构造和地形演化问题的分析精度。 相似文献
2.
《Quaternary Science Reviews》2003,22(10-13):1339-1343
The Wangsan fault is exposed at Kyeongju, Korea. The andesite is unconformably covered by Quaternary alternating conglomerate and sandstone deposits. The unconformity is cut by the thrust fault which displaces a hanging wall block of about 30 m. Exposed at the surface of this fault is a light gray and brown fault gouge, about 40–120 cm thick. In order to test the consistency of ESR ages from a single fault gouge zone, we collected six gouge samples systematically along and across the Wangsan fault. We found that six samples collected from the same gouge zone show consistent ESR date estimates (average 550 ka). Because fault rock is rare along faults in unconsolidated sediments due to low confining stress near the surface, we consider that this fault gouge has been moved up with the hanging wall block along the fault. The estimated average uplift rate of the hanging wall block is about 0.04 cm/year based on the age of the displaced Quaternary deposits (vertical separation; about 20 m) dated by OSL dating methods. The depth of the fault gouge at the time of reactivation, which was estimated from uplift rate and the ESR ages, is about 220 m. Therefore, we conclude that the results of ESR age estimates represent the time of reactivation of the fault gouge at a depth of 220 m in the past during fault movement, because later movements which occurred during uplift near the surface may not have zeroed ESR signals significantly for ESR dating of fault movements. 相似文献
3.
《Quaternary Science Reviews》2005,24(1-2):223-231
Signal resetting by sunlight prior to burial is a crucial assumption in electron spin resonance (ESR) dating of sediments. This resetting process is expected to be completed to a greater extent in arid than in fluvial environments. The present paper investigates the natural and artificially irradiated signal intensity of Ti related centres in single quartz grains collected from the desert surface (Eastern Desert, Egypt) in order to test this hypothesis. The results suggest that in most grains both the Ti–Li and Ti–H signal are completely reset to zero. Additive dose curves based on the sum of both Ti centres show an anomaly in the low dose region. Possible causes for this behaviour are briefly discussed. Three fitting procedures are conducted and each of them shows a different palaeodose distribution with a rather large spread in DE values. It is concluded that similar fossil deposits would be datable by single grain ESR using Q-band measurements of the Ti–Li or Ti–H signals in quartz. 相似文献
4.
石英ESR测年信号衰退特征研究进展 总被引：3，自引：0，他引：3
电子自旋共振(ESR)测年法是第四纪地质年代学的重要测试方法之一,其测年范围广,特别是对于20万年至百万年尺度的第四纪样品有着重要意义.准确测量古剂量是影响ESR测年法精度和可信度的重要因素之一,而掌握ESR信号衰退特征及机制是获得准确、可信古剂量的重要前提.ESR测年法适用的地质样品种类较多,如热液石英脉、地质断层泥、水系沉积物等,不同样品的ESR信号衰退特征和机制有较大差异.近年来,国内外学者针对不同地质样品中石英ESR信号的衰退特征和机制深入开展了一系列的实验室模拟和野外观测研究,取得了诸多新认识.回顾了近年来在石英ESR信号衰退特征领域取得的进展,特别是水系沉积物石英ESR信号的衰退特征,并展望了这一领域的未来工作重点. 相似文献
5.
近些年,宇宙成因核素暴露年代、光释光和放射性碳埋藏年代等方法在第四纪冰碛物的年代测定中已经取得显著进展.但对于第四纪冰川沉积物10万年甚至百万年以上的冰碛物样品的埋藏年代和暴露年代,由于方法自身问题或沉积物后期地质地貌过程的改造,使上述方法存在定年方面的挑战.而电子自旋共振（ESR）广泛的测年范围,使其在第四纪样品的测年中发挥着不可替代的作用.目前,石英ESR信号的衰退特征已有许多研究进展,但是对于冰碛物中的ESR信号的研究还很少.ESR测年方法由于缺乏测年机理的研究,西方学者和国内一些测年学者对这种方法的定年存有疑虑.因此,我们在典型冰川区开展对冰碛物中石英砂ESR信号变化的机理研究,得到人工研磨可以使ESR信号强度下降到原来值的53%~69%,但并不能使ESR信号完全归零.如果在以后的研究中能够找出这些残留信号值大小,并予以扣除,将会大大提高ESR冰碛物测年精度.在今后的研究中应探求其测年机理,提高测试样品的石英纯度,增强ESR测年信号的精度,使这种方法成为冰碛物交叉测年中独立可信的测年方法之一,为第四纪冰川研究中的老冰碛物的定年提供准确的年代依据. 相似文献
6.
T. K. Gundu Rao C. P. Rajendran George Mathew Biju John 《Journal of Earth System Science》2002,111(2):103-113
The field investigations in the epicentral area of the 1994 Wadakkancheri (Desamangalam), Kerala, earthquake (M 4.3) indicate
subtle, but clearly recognizable expressions of geologically recent fault zone, consisting of fracture sets showing brittle
displacement and a gouge zone. The fracture zone confines to the crystalline basement, and is spatially coincident with the
elongation of the isoseismals of the 1994 mainshock and a 10-km-long WNW-ESE trending topographic lineament. The preliminary
results from the electron spin resonance (ESR) dating on the quartz grains from the fault gouge indicate that the last major
faulting in this site occurred 430 ± 43 ka ago. The experiments on different grain sizes of quartz from the gouge showed consistent
decrease in age to a plateau of low values, indicating that ESR signals in finer grains were completely zeroed at the time
of faulting due to frictional heat. The results show a relatively young age for displacement on the fault that occurs within
a Precambrian shear zone. Discrete reactivated faults in such areas may be characterized by low degree of activity, but considering
the ESR age of the last significant faulting event, the structure at Desamangalam may be categorized as a potentially active
fault capable of generating moderate earthquakes, separated by very long periods of quiescence. 相似文献
7.
断层电子自旋共振定年中石英信号强度的影响因素分析 总被引：1，自引：0，他引：1
电子自旋共振(ESR)是一种利用矿物在地质环境中的累计辐射能进行测年的技术方法,它采用的测年矿物石英广泛分布,并具有记录断层作用良好的计时零点,是同位素测年的重要补充。ESR信号强度是决定ESR年龄精确度的关键因素,但是各种参数条件对测量结果的影响方式及其程度缺乏系统研究。本文以取自断层带石英的一种顺磁中心——E’心为研究对象,运用单因素重复性实验方法,分析石英ESR定年中5种影响因素与ESR信号强度的相关关系。结果表明,微波功率、调制幅度、扫描宽度是影响ESR信号强度的主控因素,样品管方位及直径对测量结果影响不大。微波功率0.02~0.1 m W、调制幅度0.25~0.4 Gs可作为精确测量断层泥石英E’心普适性的参数区间,过大或过小的扫描宽度均不利于ESR测量,可利用在大扫描宽度条件下先预扫描再精细扫描的方法确定合适的扫描宽度,重复测量后求取平均值可有效降低测量误差。利用本文提出的参数区间及其确定的方法测量断层泥石英的E’心信号强度,能显著提高ESR测量精度。 相似文献
8.
9.
在充分论证厦门地区现代区域构造应力场基础上,应用叠加断裂作用原理,分析厦门地区的断裂稳定性。厦门地区的断裂可划分为稳定型、基本稳定型、次稳定型和不稳定型4种。最后,利用地面调查、物探和勘探等综合技术手段确定断裂带的位置,在厦门地区典型的北东向、北西向断裂中采集断层泥样品。通过对断层泥进行显微刻蚀形貌测年、热释光测年及电子自旋共振测年,表明在现代区域构造应力场作用下这些断裂在第四纪时期有过多次活动。证实叠加断裂作用原理在厦门地区断裂稳定性分析中应用的可行性。 相似文献
10.
Reliable dating is an essential element of palaeoseismological studies, yet whilst a suite of geochronological methods can now provide late Quaternary age control it remains very difficult to date modern events (i.e., those occurring within the last 150 years). This is significant because the starting point for many palaeoseismological investigations is a modern surface-rupturing event, whose geological effects need to be disentangled in trench stratigraphies from palaeoseismic ruptures. Two dating methods which, in combination, can provide robust dating control in recently deposited sediments are the 210Pb and 137Cs dating methods. Here, we test the applicability of using 210Pb and 137Cs to date colluvial sediments exposed in three trenches excavated across an earthquake fault—the Eliki fault, Gulf of Corinth, Greece—which ruptured in an earthquake in 1861. The 210Pb and 137Cs profiles observed in these colluvial sequences are relatively erratic due to the mixed nature of the sediments, i.e., their deposition in an environment where the supply of slope sediments is driven by seasonal rainfall, causing non-uniform sediment accretion and sediment reworking. In one trench, however, 210Pb dating, corroborated by 137Cs dating, indicates that a proposed post-1861 surface colluvial unit has been deposited over the period 1950 AD–present (at a rate of ca. 9 mm/year), and overlies a significantly older unit (>120 years old). The dating control provided here by 210Pb and 137Cs dating corroborates the published interpretation of the trench stratigraphy, and refines the 14C-based estimated dates for the upper unit. At two other trenches 210Pb and 137Cs dating only provided minimum ages (based on the presence or absence of 210Pbexcess and 137Cs). Such approximate ages, however, may still useful in corroborating interpretations made using the trench stratigraphy, or, at sites which have long earthquake recurrence intervals, determining which earthquake event was responsible for a particular bed offset. 相似文献
11.
12.
ESR定年：一种确定脆性断层活动年龄的方法原理与应用 总被引：16，自引：0，他引：16
在浅层低温环境中，脆性断层活动难以生成新的变质矿物，断层的准确活动年龄就难以确定。但在浅层断层活动中，往往伴生有同期生成的石英脉，对石英脉采用热活化电子自旋共振(ESR)测年，能够确定石英脉的生成年龄，从而能提供断层活动的年龄。如果断层带中发育有多期石英脉，通过测定还能提供断层多次活动的年龄。以雪峰山2条断裂带为例，使用ESR定年方法获得了202.3~60.6 Ma的地质年龄，并探讨了2条断裂带的演化与区域构造活动的关系，最后对ESR测年的可信性与使用条件进行了讨论。 相似文献
13.
电子自旋共振(ESR)技术是一种确定物质成分和结构的顺磁性质的分析方法,也能够用于沉积物定年。该方法的测量技术和测年的物理机制等还处于发展阶段。冰川作用过程十分复杂,形成各种类型的冰川沉积物,其顺磁信号的归零机制有显著差异,ESR测年的实验方案也有所差异。因此,识别冰碛物类型,采集合适的样品对于ESR测年的准确性十分重要。冰下融出碛和滞碛经过了冰下磨蚀过程,结构致密,细颗粒基质含量高,石英砂中的一些杂质芯的ESR信号能够衰退。许多冰上融出碛,结构疏松,但细颗粒基质含量高,不但经过了搬运过程中的冰下磨蚀过程使ESR信号衰退,又经历了沉积时的冰上阳光直射过程使信号衰退,一些样品的ESR信号能够完全晒退。冰水湖泊和冰水河流沉积的细砂和粉砂来源于冰下研磨的产物,信号会衰退;在搬运沉积过程中又可能被阳光直射,信号进一步衰退。其它类型的冰碛物的ESR信号衰退机制不明,或粒径不适合用ESR方法测年。采集冰碛物ESR年代样品时,最好同时采集信号衰退机制相同的现代冰碛物样品,以便对照,并用于扣除可能的残留信号。 相似文献
14.
江南隆起带北缘新生代构造演化的石英ESR年代学研究 总被引：1，自引：1，他引：0
运用α石英热活化ESR定年法对江南隆起带北缘35件样品进行了研究。结果显示,江南隆起带北缘的石英脉ESR年龄范围在195.8~3.4 Ma之间,主要集中在喜山期(75~3.4 Ma)。结合其他地质证据,江南隆起带北缘新生代构造演化可以划分为伸展断陷期(75~61.5 Ma)和挤压隆升期(43.2~3.4 Ma)两个阶段。前者以发育正断层和断陷盆地为特征,后者以重力滑脱构造为特征。喜山期的构造作用对先存构造进行了强烈的改造,包括南华北、中下扬子和江南隆起带北缘的整个中国东部地区在喜山期都经历了显著的构造活动。ESR测年结果与江南隆起带已有地质事实相吻合,检验了ESR测年的可靠性。 相似文献
15.
《Quaternary Science Reviews》2003,22(10-13):1345-1351
In the last 20 years, the electron spin resonance (ESR) dating method has allowed the establishment of a chronological time frame over most of the history of human evolution. Despite many difficulties found for ESR dating of bones and carbonates, tooth enamel dated by ESR has been proven as a reliable method in its application to fossil teeth and quartz. Both of the latter materials have allowed dating of Early and Middle Pleistocene sites which are not datable using other methods such as the Argon–Argon method. In particular, recent discoveries of human remains in western Europe have been proposed to be sites of the earliest arrival of humans there, and have been dated to the Early Pleistocene by ESR using quartz and tooth enamel.Combined ESR and U-series dating of fossil herbivore teeth are the only means of dating layers from which such ancient remains have been recovered in western Europe. Good examples are the sites of Atapuerca Gran Dolina, Spain and Visogliano, Italy which have been dated using tooth enamel.When no bones and teeth can be found in prehistoric sites, ESR dating on quartz extracted from sediments has been used to date sites whose ages range over the entire Quaternary period. We present here two examples that occur in fluvial terraces of the river Creuse, France and at Monte Poggiolo site, Italy, where several artefacts of an archaic pebble industry have been recovered. 相似文献
16.
《Quaternary Science Reviews》2003,22(10-13):1329-1334
In optically stimulated luminescence dating, apparent ages of individual grains are thought to reflect a wide distribution of initial bleaching levels in hard to bleach sediments. Although having a larger age range (up to 1 Ma and beyond), this approach has not been used yet in electron spin resonance (ESR) dating. Here we report on the first results of ESR measurements on single sedimentary quartz grains. Initial bleaching levels are evaluated for two different River Meuse deposits in Limburg, NE Belgium. Measurements were done with a Q-band ESR spectrometer on transparent quartz grains of sufficiently large diameter (0.5–0.7 mm). Single crystal ESR properties were used to identify different ESR active centres. In about 50% of the selected grains an Al and/or Ti–Li signal was detected and the latter has been selected for further measurements. Artificial bleaching experiments show a strong signal decrease with UV light exposure. After gamma-ray irradiation, a number of different signal intensity vs. artificial dose curves could be observed: exponential growth, exponential saturation, linear, with inflexion points, and unclear ones. Many grains show increasing ESR signals with doses up to 1000 Gy, suggesting that the age range could be extended over 1 Ma, covering the Middle Pleistocene and part of the Early Pleistocene. Accumulated doses of individual grains were calculated using the additive dose method. The results show a large dose distribution of individual grains for both deposits. It is concluded that insufficiently bleached grains can be detected using single grain ESR measurements of sedimentary quartz in a fluvial environment. 相似文献
17.
Inflexion points interfere with the radiation growth curve of the dating signal at g = 2.0014 for mollusc samples. Several experiments give evidence that the definition of the dating signal at g = 2.0014 has to be reconsidered. A reliable AD determination very often seems questionable for ESR dating of mollusc samples. 相似文献
18.
《International Geology Review》2012,54(1):90-97
The fault is 200 km in length, trending N 5°W., cutting the N 30° E-trending structure of the Sikhote-Alin Mountains. Correlation of northwesterly-dipping Paleozoic and Mesozoic sequences on either side of the fault show that the fault is vertical, with a left-lateral displacement of about 40 km. The youngest beds displaced are Senonian, dating the movement as Upper Senonian (a post-geosynclinal stage of the Sikhote-Alin development). — P. B. Ives 相似文献
19.
Equivalent dose (ED) estimates for speleothem calcite derived by ESR measurements of the g = 2.0005 signal have a typical precision of ±7% (minimum ±2%), and depend on the signal strength, radiation sensitivity and the presence of interfering signals. Underestimation of ED will occur if the crushing signal at g = 2.0001 is not removed by acid etching, while overestimation may be caused if the short-lived radiation induced interfering signal at g = 2.0020 is not removed by annealing. Quoted errors for ESR ages are rarely better than ±10% and are typically ±15% because of uncertainties in ED, calibration of dosimeters and gamma source, and in the a-value. Serial analyses along the growth axis of single speleothems, and between speleothems interbedded in a sequence demonstrate excellent stratigraphic concordance. Intercomparison of ESR and uranium series ages for samples derived from 11 geographically diverse sites show good agreement with no indication of systematic error. Although validation is more difficult for samples beyond the limit of
dating, the results appear encouraging, but recrystallisation and changes in the external radiation dose may cause problems. 相似文献
20.
通过对金沙江上游叶巴滩水电站外围竹英-贡达断裂带的新活动性研究,利用扫描电镜对选取的断层泥中的石英颗粒样品进行溶蚀微形貌的观察和统计分析,发现断层泥中的石英颗粒表面的溶蚀微形貌特征简单,以橘皮状为主,表明竹英-贡达断裂不具有新活动性.这与电子自旋共振测年方法显示的结果一致,同时也说明了该方法可以反映断层活动的年代信息. 相似文献