共查询到19条相似文献，搜索用时 171 毫秒
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简述了近年来我国学者在与地震学和地球内部物理学相关的实验岩石力学和构造物理学研究方面的进展．在此领域的进展主要体现在:大量实验以及数学模拟结果丰富了对岩石脆性破裂过程，特别是结构和介质非均匀条件下破裂过程的认识；在非均匀断层的摩擦行为与失稳成核方面取得了一些新结果，揭示了断层滑动行为的复杂性；在岩石脆塑性转换和塑性流变方面取得了一些新结果，特别是在下地壳和上地幔物质的流变性质方面取得了重要进展；在高温高压岩石物理方面取得了一批实验结果, 并应用于地球内部物质的组成和状态的研究．这些结果为深入理解地球内部物质的物理性质、变形机制及地震物理过程提供了有价值的参考资料. 相似文献
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地层年代确定是地质学研究领域的重要课题,地质类定年方法具有各种不利因素.本文选择地球物理方法确定地层年代,以中国大陆沉积盆地为研究区,通过对盆地中实测速度、深度和年代三者间关系的深入研究,应用统计、拟合和扫描的方法,建立了中国大陆沉积盆地中速度、深度和年代之间的定量关系,此关系式为测定年代提供了一种新的方法.利用此关系式计算了沉积盆地基底的年代范围,并与同位素实测的年龄作了比较,表明该方法可以粗略确定稳定基底年代.计算基底年龄和实测数据之间存在误差,其原因主要是本文把中国大陆沉积盆地看作一个构造单元所致. 相似文献
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重力极潮，即极移引起的重力变化，是地球由于惯性离心力变化导致地球形变的综合反映，其观测和研究有助于了解地球在长周期频段的响应，约束地球形变、地球内部构造和物理参数.区别于以往研究，本文采用了集合经验模态分解方法（Ensemble Empirical Mode Decomposition，EEMD）从全球5个超导重力仪台站连续重力观测资料中提取重力极潮、消除仪器漂移及极潮频段以外的大部分噪声信号，该方法所用的基函数是基于自身信号获得的；在此基础上，利用最小二乘匹配法分离极潮中的周年项和Chandler项，估算Chandler周期的极潮潮汐因子.结果表明，基于EEMD得到的极潮潮汐因子与前人基于其他消除仪器漂移方法（数学模型或小波分析）得到的结果相符合，精度相当，但由于这种方法是自适应的，因此本文结果更能反映实际物理过程. 相似文献
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回顾了近半个世纪以来，特别是近几年来我国核地球物理勘查的发展及取得的成就．它已由50年代创建初期的单纯用于找铀矿，发展到现在在环境科学、水文地质和工程地质、寻找油气田、钾盐、磷矿、铜锡矿等方面的全方位应用；在理论上有所突破，方法技术上有所创新，并已逐步走向系列化和标准化；在与其他学科相互渗透方面得到了发展；以及在油气、煤炭测井的测试仪器等方面也都有重要进展．本文还对核地球物理今后的发展提出了看法，首先，为适应多领域应用和方法技术本身的发展，应深化应用基础理论研究；其次，要发展和提高测量结果的推断解释水平，研究消除、减少干扰因素的理论和技术；第三，应更多地运用近代科学技术的新成果，创立自已的理论和方法；第四，要根据经济的发展和生产的需要，使核物探稳步走向市场． 相似文献
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从地球物理反演的基本概念出发，认为地球物理反演是 对实测数据的地球物理属性的理解或解释，多方法的地球物理数据联合反演是一种多传感器 的数据融合. 本文分析了地球物理数据的模糊特性，采用基于语义的模糊化方法，使不同物 理意义和尺度的特征数据及测区的地质和地球物理背景成为一体，结合地球物理专家解释的 方法，利用基于模糊逻辑系统的神经网络实现了融合. 该方法充分利用了各种地球物理探测 数据的全部信息，避免了线性反演的复杂计算；其数据融合的观点,为解决地球物理联合反 演问题提供了新的思路. 通过模拟实验和应用实例验证，该方法是有效的. 相似文献
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《中国科学:地球科学》2020,(2)
目前,中国正在东南极Dome A地区的昆仑站(Kunlun)进行深冰芯钻探工程,截至2018/2019年,经过6个钻探季度的工作,已经钻进超过800m.冰龄和积累率是古气候与冰盖模式的重要边界条件.冰雷达探测得到的冰盖内部等时层可被用来测定冰体的年代并反演过去的冰雪积累率. 2004/2005年中国国家南极科学考察队和2007/2008年德国阿尔弗雷德韦格纳研究所收集了Dome A冰穹地区以及Dome A至Vostok冰芯钻探点的冰雷达数据.通过连接昆仑站钻探点与Vostok深冰芯钻探点的雷达内部等时层,比较了两个钻探位置的深度-年代关系.基于Vostok的冰芯年代,获得了昆仑站冰芯钻探点50%的冰盖厚度以上的10条连续的内部等时层的年代.这些层的冰龄涵盖从威斯康星(Wisconsin)冰期、Eemian间冰期到海洋氧同位素6期等冰期-间冰期旋回.在表面以下1640m处与最深层相对应的昆仑站冰芯冰体的年代被确定为～160400年.内部层的年代及其几何结构提供了冰芯所在区域冰盖过去上表面地貌信息.利用所得到的年代-深度关系,基于一个一维冰流模式,估算了该地区相应历史阶段的冰雪积累率,计算表明:Dome A区域过去16万年以来的积累率较低,与目前的观测结果一致.基于内部等时层获得的年龄-深度关系和古积累率信息将有助于构建并约束昆仑站深冰芯断代. 相似文献
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D. Macdougall 《Earth and Planetary Science Letters》1971,10(4):403-406
The fission track dating method is applied to glass shards from volcanic ash layers in deep sea sediments which have also been dated by other methods. Measured ages for three samples are in excellent agreement with previously determined K-Ar, paleomagnetic and paleontologic ages. The fission track method of dating of glass shards seems to offer itself as a valuable tool for dating marine sediments. 相似文献
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The geological record preserved in coastal salt marshes provides an opportunity to determine past hurricane activity during the Late Holocene in New England, USA. High precision dating is important to correlate overwash sand layers associated with hurricane strikes between different sites along the coastline. Three different optical dating methods have been tested and compared with independent age control; i) optically stimulated luminescence from quartz, ii) infrared stimulated luminescence from K-feldspar, and iii) a subtraction method.Quartz and K-feldspar dating results for three samples in a core from Round Hill Beach Marsh are in stratigraphic order and they are consistent within errors with radiocarbon ages and with each other. Subtraction dating results agreed with the quartz and K-feldspar ages for two of the three samples, but the subtraction age of the youngest sample gave an age underestimate. Replicate equivalent dose values from quartz showed a larger variation than those from feldspars, and this resulted in larger errors for the quartz and subtraction ages than those based on feldspars. K-feldspar yields the most precise optical ages, but is complicated by the need to correct for anomalous fading. Both quartz and K-feldspar are suitable for optical dating of hurricane overwash deposits in New England. 相似文献
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Accurate calculation of the environmental radiation dose rate (Ḋ) is an essential part of trapped charge dating methods, such as luminescence and electron spin resonance dating. Although the calculation of Ḋ is not mathematically complex, the incorporation of multiple variables and the propagation of uncertainties can be challenging. The Dose Rate and Age Calculator (DRAC) is an open access, web-based program which enables rapid Ḋ calculation for trapped charge dating applications. Users can select from recently published attenuation and conversion factors to make mathematically robust, reproducible Ḋ calculations. Comparison of DRAC calculated Ḋ values against the published Ḋ determinations of 422 samples from 32 studies results in a reproducibility ratio of 1.01 ± 0.05. It is anticipated that DRAC will facilitate easier inter-laboratory comparisons and will provide greater transparency for Ḋ calculations. DRAC will be updated to reflect the latest advances in Ḋ calculation and is freely accessible at www.aber.ac.uk/alrl/drac. The code for DRAC is available from github at https://github.com/DRAC-calculator/DRAC-calculator. 相似文献
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通过回顾近六十年来矿井物探的发展历程,简要分析总结了国内外现有的煤矿矿井物探技术的分类与特点、研究现状与应用成果,详细介绍了主要矿井物探方法技术（矿井地震法、矿井电磁法）的研究应用新进展,提出了目前我国矿井物探技术存在的一些迫切需要解决的问题和今后的发展方向.结果表明：矿井物探是地面勘探技术的重要补充,是矿井地质工作的重要手段,它相对于常规的矿井地质手段而言,具有更准确、更快捷、更方便等特点,已成为我国煤矿现代化安全生产中必备的探测技术手段,具有广阔的发展前景. 相似文献
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17 samples were collected from aeolian and lacustrine profiles within the environment sensitive zone of the Loess Plateau,
and an experimental method was established which is suitable for pollen extraction from aeolian sediment. A comparative study
of pollen dating was carried out using the accelerator mass spectrometry (AMS)14C dating of known age samples, and then an experiment with the pollen concentrates was performed. The results indicate that
pollen that has been deposited simultaneously with sediment in a stable environment can provide reliable ages. This technique
will provide a way of improving the chronological framework for the Loess Plateau since the late Pleistocene. TheI4c dating was combined with field investigations, and from the geological record within this zone, evidence was extracted of
four major monsoon precipitation changes during the transition from the late Pleistocene to Holocene.
Project supported by the National Natural Science Foundation of China (Grant Nos. 49894170, 49725308), Chinese Academy of
Sciences (Nos. KZ-951-A1-402& KZ-952-S1-419), and State Committee of Science and Technology of China. 相似文献
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The potassium-argon method is attractive for dating volcanics since it can be applied to rocks of Pleistocene age and older, thus encompassing important periods of general volcanic activity. However it has been found that dates obtained on whole rocks and on included minerals frequently show gross discordances. In order to establish this dating method in this application an attempt has been made to trace the sources of the anomalies. To illustrate these efforts, dating results from a rhyodacite of Mauna Kuwale, Oahu, Hawaii, are reported. Determinations on several minerals and the whole rock of this ridge give a concordant age of 2.3 ± 0.3 million years, excluding some few results on minerals which show old age anomalies. It has been noted that xenoliths in certain Hawaiian volcanics contain fluid inclusions which show evidence of formation at depth. We have found that gas released from such inclusions by crushing contains radiogenic argon, and that the constituent minerals give very old potassium-argon ages (circa 800 million years). Similar gaseous inclusions have been noted in a variety of other lava phenocrysts, and their presence in a dated sample may produce an anomalous old age. In the minerals from Mauna Kuwale sporadic occurrences of inclusions have been noted in biotites and hornblendes, and crushing of the mineral releases the excess radiogenic argon. The determination of the age of such a material would give an old age, and thus account for the anomalies found. For meaningful dating of volcanics by the potassium argon method it is concluded that phenocryst-containing materials should be examined for fluid inclusion content, and samples which contain these should be rejected. 相似文献
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Similar to the loess in the Chinese Loess Plateau (CLP), the loess deposits in the Ili basin of Central Asia arid area play an important role in understanding the climate and environmental changes. However, in contrast to the intensively investigated loess deposits in the CLP, the Ili loess is still insufficiently known and poorly understood. The geochronology study of the Ili loess remains controversial. In order to examine the potential of optically stimulated luminescence (OSL) dating for the Ili loess, we carry out a combined luminescence and radiocarbon dating study on a 6.9 m loess section in the south margin of the Ili basin. Polymineral fine grains were investigated by post infrared (IR) OSL using a Multiple-Aliquot Regenerative-dose (MAR) protocol. Radiocarbon dating of organic carbon were carried in a 3 Megavolt (MV) multi-element Accelerator Mass Spectrometry (AMS). The results indicate that the OSL ages are in agreement with the observed stratigraphy in the field, which is well correlated with that of the CLP, but the AMS 14C ages are much younger than the OSL and assumed stratigraphical ages. Thus, the OSL dating technique may provide an absolute chronology in this loess section. Further methodological approaches and more samples analysis will lead to the improvement of this chronology for high-resolution paleoclimatic interpretation. 相似文献
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Whilst optically stimulated luminescence (OSL) is commonly more suitable for sediment dating because of faster signal resetting, thermoluminescence (TL) remains important for dating burnt material, e.g. in archaeological contexts, or for studying the luminescence properties of different materials. A lack of user-optimized analysis software for TL data has exacerbated the decline of TL dating in comparison to OSL. However, exciting developments in TL dating of flint and calcite indicate a rise in application of this underused method.R is a programming language and environment for statistical computing and graphics. It provides a wide variety of statistical and graphical techniques and is highly extendable. A package specifically designed for luminescence data analysis is available. However, it mainly includes functions for the analysis of OSL data. The TLdating package is a new R package specifically dedicated to TL dating. This package is designed to be fully compatible with the existing Luminescence package and is user-friendly. It includes functions for TL data pretreatment and palaeodose estimation using the MAAD and the SAR protocols. The functionality of the TLdating package is evaluated using heated flints from Taibeh, Jordan. 相似文献
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Thomas Stevens Simon J. Armitage Huayu Lu David S.G. Thomas 《Quaternary Geochronology》2007,2(1-4):15-22
Detailed analysis of the depositional characteristics of Chinese loess is required to determine the nature of the paleoclimate record preserved in these extensive sediments. High sampling resolution optically stimulated luminescence (OSL) dating has the potential to facilitate such an analysis. However, high-resolution dating is extremely time consuming and therefore of limited practical applicability. This study assesses the luminescence characteristics of loess from three sections on the Chinese Loess Plateau in an attempt to identify methods of increasing sample throughput without compromising data quality. Using the single-aliquot regenerative-dose technique, samples yield internally consistent results. However, dose recovery data indicate that care is required in selecting preheating regimes for different sections. The standardized growth curve approach was tested and found to be applicable within, but not between, sites. Nonetheless, the use of standardized growth curves offers increases in sample throughput that will allow more routine high-resolution dating of Chinese loess. High-resolution dose rates calculated using inductively coupled plasma (ICP) methods show relative homogeneity of radioisotope concentrations and are comparable to lower resolution field gamma-spectrometry measurements. Consequently, high-resolution OSL dating has great potential to elucidate the depositional characteristics of Chinese loess and facilitate more precise use of the paleoclimatic information it preserves. 相似文献