共查询到19条相似文献,搜索用时 171 毫秒
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目前裂变径迹低温热年代学的理论基础是建立在温度是导致径迹退火的唯一诱因之上的。然而,辐射损伤是否能够促进裂变径迹退火尚处于争论中。文章采用云南临沧四块花岗岩样品的磷灰石裂变径迹测试分析方法,对辐射损伤与裂变径迹退火行为之间的关系进行了研究。云南临沧磷灰石单颗粒年龄71~15 Ma,封闭径迹长度9~16μm, U含量24~290μg/g。统计分析结果表明,磷灰石封闭径迹长度以及单颗粒年龄分别随相应U含量增加而减小。综合分析认为,这种变化趋势初步表明了辐射损伤能够促进裂变径迹退火,是导致裂变径迹退火的另一诱因,为辐射损伤诱发裂变径迹退火行为研究提供了新证据。 相似文献
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磷灰石裂变径迹退火是一个繁杂的化学动力学过程,清楚地了解其退火的影响因素对于该技术的应用十分重要。文章概述了磷灰石裂变径迹退火动力学模型的发展史,并结合以往对其退火影响因素的研究,将磷灰石裂变径迹退火影响因素分为自身和外部环境两方面:自身影响因素包括化学成分、晶体结构、径迹长度与半径、径迹与结晶轴的方位关系,其中化学成分对退火起到主导作用;外部环境影响中,温度是主导因素,压力和蚀刻条件的改变也会影响退火。研究成果有利于完善磷灰石裂变径迹的实验室退火模型,提高其作为热历史记录器的精度。 相似文献
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磷灰石裂变径迹分析(AFTA)——一种研究含油气盆地古热构造史的新方法 总被引:2,自引:0,他引:2
磷灰石裂变径迹分析近年来广泛地被用来研究含油气盆地古热定史与古构造史及指导油气勘探,这主要是根据磷灰石裂变径迹退火是时间和温度的函数,而烃的生成与热成熟同是也是和温度的函数,而且磷灰石裂变径迹退火温度范围与石油的生成门限相吻合,退火除受温度、时间影响外、还受化学成分,取向因素控制。AFTA包括裂变径迹年龄分析和裂变径迹长度分析,通过前者可获得退火方面信息,通过后者可获得最大古地温及其随时间的变化及 相似文献
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裂变径迹法原理及其在盆地分析中的应用 总被引:1,自引:0,他引:1
裂变径迹法对于研究盆地热史有着不可替代的作用,它可以通过对于年龄和温度的确定,将地热的发展史揭露出来。从裂变径迹的发展历史入手,分析裂变径迹的成因和退火产生的影响。由于裂变径迹具有温度和长度双重特征,就可以对于盆地热史或盆地边缘山体隆升情况进行具体恢复。因此通过具体实例,说明裂变径迹法在盆地热史分析以及如何研究盆地热发展史和成矿、断裂的作用。概述了磷灰石裂变径迹的加强机制研究,建立标准,多方法结合,自动化技术发展趋势。 相似文献
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裂变径迹退火动力学及其研究进展 总被引:2,自引:0,他引:2
李小明 《矿物岩石地球化学通报》1999,(3)
裂变径迹定年是60年代开始兴起的一种新的同位素年代学方法。人们一开始就注意到了它的退火特性,例如使用总体定年时,先把样品分成两份,其中一份经高温退火,退去所有的自发裂变径迹,再送反应堆辐射,用来测诱发裂变径迹密度。但直到80年代初,裂变径迹分析方法还... 相似文献
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磷灰石裂变径迹年代学已经被广泛地应用于山体隆升、限定潜在物源区、沉积盆地后期的抬升时间等方面的研究。通常情况下,无论是基岩隆升,还是碎屑沉积地层的后期抬升,磷灰石裂变径迹年龄出现的“拐点”都具有重要的地质意义。本文从磷灰石裂变径迹的年龄形成机制、径迹封闭温度、径迹退火基本概念入手,总结了碎屑和基岩磷灰石裂变径迹年龄出现的拐点的基本意义,并针对每个具体的应用给出了研究实例。在碎屑磷灰石中,未发生强烈退火的径迹年龄形成的两阶段和单阶段移动峰,可限定物源变化的时间以及约束潜在物源区。完全退火后,新形成的径迹年龄拐点,可限定地层的变形时间。岩体经历快速隆升,在一定高程范围内的径迹年龄彼此接近,与部分退火带相接的部位会出现拐点。
相似文献9.
利用磷灰石裂变径迹计算隆升速率的一些问题 总被引:10,自引:2,他引:10
主要讨论了利用磷灰石理解变径迹年龄--地形高差法计算隆升速率存在的一些问题,介绍了近年来国外在磷灰石裂变径迹退火方面取得的新进展及其在研究隆升速率问题上的应用,并分析了利用磷灰石裂变径迹研究隆升速率应当注意的问题,强调了加强径迹长度分析的研究。 相似文献
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磷灰石裂变径迹的退火作用及其在沉积盆地油气勘探中的应用:?… 总被引:3,自引:0,他引:3
以研究沉积盆地热历史具有独特优越性的新技术方法-裂变径迹法为主要研究手段,通过对东濮凹陷不同区带钻井样品中磷灰石裂变径迹分析,从磷灰石裂变径退火特征所确定的古地渐及古地温梯度,磷灰石裂变径迹表现年龄及退火范围,以及它们与“石油窗”的关系出发,分析了东濮凹陷内油气形成的有利地段,预测了油气远景区,为油田进一步勘探开发提供了理论依据。 相似文献
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裂变径迹定年技术在构造演化研究中的应用 总被引:11,自引:0,他引:11
裂变径迹技术是一种以磷灰石和锆石等矿物为定年对象的低温热年代学方法,特别适用于研究上地壳岩石冷却剥露的时间和过程。该技术在地学中的应用早期以定年为主,随着对裂变径迹长度分布特征与裂变径迹退火特性的深入研究,这种方法得到更广泛的应用,在此基础上综述了裂变径迹技术在下列构造演化问题中的应用和进展,包括:(1)造山带隆升时代及隆升速率的研究;(2)造山带热演化历史的研究;(3)快速蚀顶或冷却事件的年代确定;(4)盆地反转时代的确认;(5)盆地基底岩系构造热历史的研究;(6)盆山耦合过程的研究。 相似文献
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伊犁盆地南缘隆升剥蚀及其盆地南部的沉积响应——利用磷灰石裂变径迹分析 总被引:2,自引:0,他引:2
分析了伊犁盆地南缘蚀源区14件磷灰石样品,其中南缘中西部10件,东部4件。磷灰石裂变径迹表观年龄及其与高程的关系、单颗粒年龄、封闭径迹分布特征表明,伊犁盆地南缘样品均遭受了不同程度的退火,但没有发生明显的区域性热事件。通过封闭径迹正演热史模拟得出,伊犁盆地南缘中新生代构造演化经历了三叠纪-侏罗纪晚期快速隆升,白垩纪-古近纪相对稳定和新构造快速隆升三个阶段。东西两段略有不同,西段隆升时间较早,样品所在地在早三叠世就开始强烈隆升,说明当时该处离原型盆地边界较近,而东段此时样品所在位置还可能接受沉积,直至中侏罗世末期才开始隆升剥蚀。侏罗纪原型盆地南部边界至少跨过大板煤矿,因为在该处出露中侏罗世西山窑组残留地层。相应的稳定阶段东段要滞后一些,稳定时间相对较短,西段该时段长达100Ma,而东段多在50~60Ma。新构造运动强烈活动的时间东段相对较早,局部地段在38Ma就开始隆升。盆地南缘沉积相带的发育特征和新近纪(或第四纪)内给出的电子自旋共振年龄(ESR)均说明,沉积对构造具明显的响应,盆缘快速隆升阶段其盆地内相应的沉积物较粗,相对稳定阶段对应的沉积较细或缺失。 相似文献
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D. A. Coyle G. A. Wagner E. Hejl R. Brown P. Van den Haute 《International Journal of Earth Sciences》1997,86(1):203-209
A detailed fission-track analysis was carried out on 41 apatite samples from the 4001-m-deep pilot hole of the German Continental Deep Drilling Program (KTB). The investigations include dating by the population method and length measurements of horizontal confined tracks. Age and length information indicate that all samples above the present-day partial annealing zone cooled from temperatures above 120?°C in the Cretaceous. The top two kilometres of the profile show less variation of age with depth than was expected. Modelling of the profile indicates that the distribution of fission track ages with depth requires that the profile was disturbed during or after cooling through the partial annealing zone. Modelling of individual samples reveals that at least the upper 2?km experienced reverse faulting, effectively thickening the upper part of the rock column by up to 1000?m in the Tertiary. A present-day partial annealing zone for apatite was observed between 2000 and 4000?m (~60–110?°C). This confirms earlier in situ observations of the position of the partial annealing zone. 相似文献
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一种约束盆地低温热历史的裂变径迹技术 总被引:1,自引:0,他引:1
裂变径迹(FT)技术是根据矿物中铀裂变产生的辐射损伤特性进行分析的低温热年代技术。随着对FT退火行为和实验退火模型研究的深入,使得这一技术成为约束沉积盆地低温热历史的重要手段。Laslett等、Crowley等和Ketcham等先后提出3个重要的磷灰石FT实验退火模型,其中以Ketcham等的退火模型研究最为深入,它分析了磷灰石类型、时间、温度和化学成分对其径迹退火的影响,使用c轴投射径迹长度和Dpar等参数,形成了描述磷灰石FT多元动力学退火的数学模型。锆石FT与U-Th/He技术、Ro值、地表温度和地层年龄等,均是约束磷灰石FT热历史重建的重要约束条件,HeFTy(2009)是进行低温热历史模拟的主要软件之一。 相似文献
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裂变径迹法在研究造山带隆升过程中的应用介绍 总被引:14,自引:0,他引:14
介绍了4种类型的造山带隆升-冷却模式,不同模式对应不同的磷灰石裂变径年龄--高程图特征;了不同构造造背景下的热历史特征一裂变径迹年龄序列。裂变径变宅遮挡同统计分布型式对应于不同的热历史,具有不同的年代学意义。 相似文献
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Jörg Giese Diane Seward Finlay M. Stuart Eliane Wüthrich Edwin Gnos Daniel Kurz Urs Eggenberger Guido Schreurs 《Geostandards and Geoanalytical Research》2010,34(1):39-48
Apatite fission-track and (U-Th)/He analyses require the liberation of intact idiomorphic apatite grains from rock samples. While routinely being carried out by mechanical methods, electrodynamic disaggregation (ED) offers an alternative approach. The high-voltage discharges produced during the ED process create localised temperature peaks (10000 K) along a narrow plasma channel. In apatite, such high temperatures could potentially reduce the length of fission tracks, which start to anneal at temperatures > 60 °C, and could also enhance He diffusion, which becomes significant at 30–40 °C over geological time scales. A comparison of fission-track analyses and (U-Th)/He ages of apatites prepared both by mechanical (jaw crusher, disk mill) and ED processing provides a way of determining whether heating during the latter method has any significant effect. Apatites from three samples of different geological settings (an orthogneiss from Madagascar, the Fish Canyon Tuff, and a muscovite-gneiss from Greece) yielded statistically identical track length distributions compared to samples prepared mechanically. Additionally, (U-Th)/He ages of apatites from a leucogranite from Morocco prepared by both methods were indistinguishable. These first results indicated that during electrodynamic disaggregation apatite crystals were not heated enough to partially anneal the fission tracks or induce significant diffusive loss of He. 相似文献
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Confined fission track lengths in apatite: a diagnostic tool for thermal history analysis 总被引:66,自引:0,他引:66
A. J. W. Gleadow I. R. Duddy P. F. Green J. F. Lovering 《Contributions to Mineralogy and Petrology》1986,94(4):405-415
Fission-track ages in apatite are generally accepted as giving a measure of the time over which a sample has been exposed to temperatures below approximately 100° C. A compilation of the lengths of confined fission tracks in a wide variety of apatites from different geological environments has shown that the distribution of confined track lengths can provide unique thermal history information in the temperature range below about 150° C over times of the order of 106 to 109 years. The distribution of confined lengths of freshly produced induced tracks is characterised by a narrow, symmetrical distribution with a mean length of around 16.3 m and a standard deviation of the distribution of approximately 0.9 m. In volcanic and related rocks which have cooled very rapidly, and never been reheated above about 50° C, the distribution is also narrow and symmetric, but with a shorter mean of 14.5 to 15 m, and a standard deviation of the distribution of approximately 1.0 m. In granitic basement terrains which are thought never to have been significantly disturbed thermally, since their original post-emplacement cooling, the distribution becomes negatively skewed, with a mean around 12 or 13 m and a standard deviation between 1.2 and 2 m.This distribution is thought to characterise slow continuous cooling from temperatures in excess of 120° C, to ambient surface temperatures. More complex thermal histories produce correspondingly complex distributions of confined tracks. The continuous production of tracks through time, coupled with the fact that the length of each track shrinks to a value characteristic of the maximum temperature it has experienced, gives a final length distribution which directly reflects the nature of the variation of temperature with time. Most distinctive of the myriad possible forms of the final distribution are the bimodal distributions, which give clear evidence of a two-stage history, including high and low temperature phases. The study of confined length distributions therefore offers invaluable evidence on the meaning of any fission-track age, and bears the potential of providing rigorous constraints on thermal history in the temperature regime below about 150° C. The results of this study strongly suggest that any apatite fission-track age determination should be supported by a confined track length distribution. 相似文献
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Considerable attention has been paid in recent years to the study of geothermal history by using spontaneous fission tracks of 238U recorded in minerals.Apatite and zircon were used for fission track study in this paper because apatitie has been widely used as a natural geothermometer(Wang Shicheng et al., 1994) to reveal the thermal evolution of sedimentary rocks based on its low annealing temperature of fission tracks and zircon is characterized by a closing temperature above 700℃,The samples were collected from ferruginous,siliceous slate wall rock at the upper levels of the orebody and Nb-REE-Fe ores from deep tunnels.The age and thermal evolution of the orebody were discussed in terms of fission track characters and their length variations observed in the coexisting apatite and zircon in the same specimen. 相似文献