海洋沉积物14C测年数据整合与校正问题探讨

随着放射性碳(14C)测年技术的发展,海洋沉积物年代学已成为研究古环境和古气候变化的重要手段。文章从14C测年数据整合角度,辨析和厘定了放射性碳测年有关术语及相互关系,探讨了数据校正的关键环节,制定了14C测年数据整合格式。测年数据整合格式应包括站位信息、样品测试信息、测年方法信息和校正方法信息等,其中惯用年龄是核心要素,而校正方法选择及与之相关的参数的使用是获得正确年龄的关键。采用CALIB7.0对选取的24个不同时期、不同实验室样本数据进行了统一校正,整合前后结果对比分析表明,软件不同版本或不同方式校正结果有数十年至一千多年的差异。14C日历校正年龄与惯用年龄大小、标准校正曲线、校正软件以及海洋储库年龄(R(t))或区域海洋储库校正值(ΔR)有关,建议资料整合时在惯用年龄基础上选择适合的校正软件重新对数据进行统一校正。同时,应加强我国近海海洋放射性碳储库年龄的研究,为测年数据校正提供更为准确的校正参数。     

沉积物的ESR测年

对沉积物中石英ESR测年的特性进行了较为详细地研究，可用沉积物中石英的Ge心信号进行ESR测年；根据石英E心饱和功率较小这一特性，采用较大的微波功率可以测得较老海洋沉积物（大于0.5Ma）的ESR年龄；石英E心的异常较照剂量响应是判断海岸风成沙环境的一个标志。此外，还介绍了沉积物ESR测年在地质上的应用。     

光释光测年技术在海洋沉积物研究中的应用现状与展望

海岸带地区沉积环境复杂,长期以来都较难获取其沉积物的准确年龄信息。而光释光测年技术独有的揭示砂粒级矿物末次曝光年龄的特点,正好适用于复杂的海岸带沉积环境,并且不受限于宇宙成因核素年代学分析方法中核素污染等干扰因素的影响。在回顾光释光测年技术发展历史的基础上,综述了该技术在澳大利亚、非洲、美洲、欧洲、亚洲以及中东和地中海等海岸地区的海洋沉积物测年研究中的应用现状,分析了它目前所存在的主要问题和发展前景。随着近些年海岸演化及其与全球气候变化关系等方面的研究日益受到学术界的关注,相信光释光测年技术在海平面变化、全球气候变化及区域海洋地质演化等研究领域具有广阔的发展前景。     

山地灾害沉积物的测年综述

山地灾害事件发生的年代是理解其发育机制并作出预测的基础.在长时间尺度上,常用的测牟方法有光释光、14C、宇宙成因核素和火山灰测年等,其中的关键是能否在剖面中寻找到合适的测年物质.短时间尺度的测年方法以树轮为主,辅以地衣测年.在山地灾害中,不仅灾害沉积本身,其相关沉积物对事件年代也具有指示意义.在实际应用中,根据测年材料...     

年轻沉积物36Cl测年研究进展

宇宙成因核素36Cl对第四纪地层及第四纪时代的厘定具有独特的优势.近年来随着加速器质谱(AMS)技术的不断发展,36Cl已经能被高灵敏测量,使得36Cl测年技术前景广阔.本文介绍了36Cl测年的研究现状和研究难点,对于陆相沉积物的36Cl测年方法进行了探索,对制约其发展的测年公式中早期放射性比度I0对测年精度的影响以及在地球科学中的应用前景进行了探讨,进一步提出不同海拔高度对I0存在叠加效应.同时介绍了36Cl样品的制备流程,该流程采用离子交换树脂驱除试样中的硫和可能产生“盐效应”的常量金属元素,有效地排除了36S对36Cl的干扰,建立了动态的AgCl制样技术流程,方法高效快捷.     

第四纪沉积物光释光测年中等效剂量测定方法的对比研究

准确地测定碎屑矿物沉积后吸收的等效剂量第四纪沉积物释光测年中最关键的一环。用光释光测年技术对几年全新世坡积物,古土地和黄土等样品中的石英,长石等碎屑矿物进行了测定等效剂量的对比研究。     

第四纪沉积物测年新进展

由于沉积环境和沉积物类型与成因的差异,第四纪沉积物岩性、组成会随时间变化,并且结构和厚度在空间上也可能发生明显变化,使得长期以来难以测得其准确年代。论文对K/Ar法和⁴⁰Ar/³⁹Ar法、玻璃陨石法、铀系定年、氨基酸外消旋法、宇宙成因核素法、电子自旋共振定年等各种方法的定年范围和测定对象进行了介绍,分析了第四纪测年方法新进展存在的主要问题和改进途径。要提高所测年代结果的可靠性和准确度,不仅需要丰富的地质工作经验,还需要选择最恰当的定年方法,并且尽可能用多种定年方法进行交叉对比。随着第四纪环境演变及全球气候变化等方面的研究日益受到地质学者的关注,相信第四纪沉积物定年方法在全球气候变化、环境演化等研究领域具有更加广阔的发展前景。     

海洋沉积物孔隙水的制备方法

介绍了几种海洋沉积物中孔隙水的制备方法,包括离心法、压榨过滤法和真空抽提法等,并对这些方法的优缺点进行了比较。     

Luminescence dating of well-sorted marine terrace sediments on the southeastern coast of Korea

Along the southeastern coastline of the Korean peninsula, well-developed marine terraces are found at various elevations. The ages of these terraces, and the time of deposition of the terrace sediments are important to our understanding of the geological history of this area during the Quaternary period, and represent a unique record of the regional tectonic activity. Previous efforts to establish a chronology using optically stimulated luminescence (OSL) methods have produced controversial results, particularly because of stratigraphic inconsistency and poor reproducibility. In this paper, the application of OSL dating based on the single-aliquot regenerative-dose (SAR) protocol for quartz is investigated. The dependence of equivalent dose on the preheat and cut-heat temperatures (thermal treatment of the regeneration and test-doses, respectively) are examined. Linearly modulated luminescence signals from chemically cleaned quartz samples are used to identify the presence of a thermally unstable component with a large optical cross-section (component A′), which in part affects the ability to correct for sensitivity changes during measurements, and thus the reliability of the equivalent dose estimates. In some samples, a higher heat treatment after the test-dose is shown to improve our ability to measure a dose given in the laboratory before any heat treatment (dose recovery test). This higher temperature treatment effectively removes component A′, and hence improves sensitivity correction. Furthermore, the samples were broadly divided into poorly sorted and well-sorted, based on field evidence. The poorly sorted samples contain friable, weathered gravel clasts, which is a likely post-depositional source of quartz grains. In general, these grains will not have been zeroed prior to deposition, and so the poorly sorted samples are rejected from further age studies. Results obtained from the well-sorted samples are reproducible at each sampling location, and give ages grouping broadly into 50–70 and 110–120 ka, but laterally discontinuous on a scale of tens of km. Our OSL results for the younger group are supported by radiocarbon ages from overlying terrestrial deposits. It is concluded that these results point to considerable tectonic activity in the southeast of Korea during the Late Pleistocene.     

Thermoluminescence dating of sediments

The potential for using the thermoluminescence behaviour of sediments for dating them was first recognized by Soviet scientists G.V. Morozov and V.N. Shelkoplyas, and for over a decade their TL dates, obtained from a variety of sediments, have appeared in the Soviet literature. Since 1977 TL sediment dates have been published by six additional groups using a variety of methods.In this review we describe the principles of TL dating, the various methods used, and contrast TL dating of sediments with the now well-accepted TL dating of pottery. We conclude that while TL dating has the potential to solve many sedimentary problems, more fundamental research needs to be carried out before such dates should be accepted. A set of criteria for acceptable dates is proposed.     

Comparison of radiocarbon and uranium-series dating methods as applied to marine apatite

A comparison of uranium-series geochronology and radiocarbon dating, the first systematic test of its kind applied to authigenic marine apatite, has been made for nine seafloor phosphate nodules sampled from the Peruvian and Chilean shelves. Radiocarbon ages agree well with the ²³⁰Th ages for all six samples with ²³⁰Th ages younger than the practical dating limit of the ¹⁴C technique for marine samples. Two of three “old” samples contain no significant ¹⁴C activities, as expected. However, one sample with a high concentration of phosphate pellets contains more than 30% of the modern ¹⁴C activity. The discrepancy between the ¹⁴C and U-series age for this sample is thought to be due to post-depositional adsorption of the particle-reactive elements thorium and protactinium onto pellet surfaces.     

寿山石的品种简介

福建省福州市产出的寿山石由田坑石、水坑石、掘性石(坡积石)和山坑石组成。经初步统计,有田坑石16种,水坑石12种,掘性石(坡积石)18种,山坑石118种,合计164种。它们分别主要由迪开石或珍珠石或高岭石或绢云母或叶蜡石组成。     

大地构造运动与钾盐成矿研究简述

钾盐是重要的工农业生产资料,虽然已经有诸多关于钾盐矿成因的研究,但关于大地构造运动与钾盐成矿的构造背景和成矿模式方面的研究还比较分散.本文首先从钾元素的初始成因出发,梳理出钾盐的物质来源.然后分别从钾盐矿形成的大地构造环境进一步分析在稳定克拉通环境、陆块汇聚环境和陆块裂解环境下的钾盐矿成矿过程,说明包括构造、物质来源和...     

国际大洋科学钻探计划简介

正1968年由美国等多个国家启动的深海钻探计划及后续的国际大洋钻探计划、综合大洋钻探计划和正在实施的国际大洋发现计划是地球科学领域内迄今规模最大、影响最深、历时最久的大型国际合作研究计划,我国于1998年加入该计划。40多年来,科学大洋钻探在全球各大洋共完成钻井3000余口,累积取芯超过40万m。研究成果验证了海底扩张和板块构造理论,创立了古海洋学,揭示了气候演变的规律,发现了海底"深部生物圈"和"可燃     

世界超深井简介

随着全球钻探技术的进步和人们对矿产资源的渴求,寻找地球深部矿产资源,已成为全球找矿的重要方向。特别是在石油天然气领域突破万米的深井已有多处,呈现出钻探有多深、油气有多深的趋势。现将国内外超深井现状介绍如下。