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。     

沂沐断裂带钙结核的ESR测年

应用ＥＳＲ测年方法对采自沂沐断裂带第四纪沉积物中的１８个钙结核样品进行了测定，结果表明这一方法适用于钙结核的测年井给出了沂沐断裂带最后一次强烈活动的大致年代．     

石英ESR测年信号衰退特征研究进展

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.     

ESR测年技术在第四纪冰川年代学中的研究综述

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.     

释光年代学样品前处理流程

释光测年是第四纪年代学中应用较广泛的重要测年方法。释光技术的发展经历了热释光(Thermoluminescence,简写TL)阶段到光释光(Optically Stimulated Luminescence,简写OSL)阶段,测年研究的载体矿物主要是长石和石英。因测试目的不同,前处理方法有一定的差异。本文主要在前人工作的基础上,针对沉积物、陶瓷、暴露岩石三种释光测年样品的长石或石英获取方法进行总结,以期对释光测年样品前处理起到参考作用。     

第四纪测年研究新进展

第四纪与人类的关系及其在地质历史中的重要位置,需要高精度高分辨率的测年。第四纪地质学家们改进、发展了许多第四纪的测年方法。文章主要从岩石地层法、生物法、磁性地层法、考古法、放射性定年法等方面讨论了近年第四纪测年的一些研究进展。目前,这些方法的主要进展表现在由于科学技术的提高,如激光显微探测技术等,使得测年的精度、功效显著提高而样品的用量却有了显著的降低,并且拓展了一些测年的应用领域,如电子自旋法应用于冰碛物的测年,其据测年结果建立的序列可与深海氧同位素阶段对比。但要使得测年的可靠性增强,则需要有丰富的地质工作经验,根据所测样品的特征选择恰当的测年方法,且要尽量选择多种适当方法进行对比测年。      

洞穴次生碳酸盐的ESR年龄测定

本文报导了浙江桐庐县瑶琳洞及广西都安县八仙洞26个石钟乳,石笋及片流石样品的ESR及~(14)C年龄测定结果,并对ESR测年方法的可靠性及实验误差进行了讨论。通过与~(14)C年龄及样品沉积层序的对比,证明了ESR方法是测定第四纪洞穴次生碳酸盐沉积物年龄的一种有效手段,但在降低实验误差方面仍须进一步工作。     

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。     

甘肃巴谢剖面黄土-古土壤的光释光测年研究

光释光（OSL）测年是测定第四纪沉积物年龄的一种新技术。它通过单色光束激发使晶体中储存的电离辐射能释放出来。与热释光（TL）测年相比，OSL测年可以不考虑残留的OSL信号，而且测量具有简便、迅速且准确等优点。本文用细颗粒光释光技术对甘肃巴谢剖面的黄土-古土壤进行了测定，其测年结果与14C测年结果相吻合。这表明，光释光是一项极潜力的年代学技术。     

α铀系测年方法在低铀含量样品中的应用

桂林是世界著名的岩溶区,洞穴沉积物极其发育,是研究第四纪古环境变化很理想的区域,但因岩溶沉积物中铀含量极低,大大地增加了分析测试的难度。本文通过几年的摸索和与其它方法的对比研究,对低铀含量的石笋样品α- U系测年取得了较为成功的经验,并为桂林20万年石笋记录古环境重建提供了可靠的年龄数据系列。      

碎屑沉积物中石英低温Al心的ESR测年初探

老于20万年的碎屑沉积物的绝对测年方法急待建立。本文利用我国典型的碎屑沉积物——洛川黄土石英中的Al心，在115K温度下进行ESR测年研究，初步给出了4层黄土剖面的古剂量值。结果表明，古剂量值随地层深度的增加而呈增长趋势，说明利用ESR方法测定低温Al心可获得老于20万年的碎屑沉积物的地质年龄。     

岷江叠溪古堰塞湖沉积物中孢粉特征

对岷江上游叠溪古堰塞湖200余米厚的堰塞湖相沉积物进行了大量采样测试分析.主要对湖相沉积物中的孢粉和沉积年代进行了测试.通过测试获得了古堰塞湖沉积物的沉积时间和气候环境特征.古堰塞湖沉积物底部形成时间约3.0万年, 靠近顶部形成时间约为1.5万年前.孢粉测试结果显示, 古堰塞湖沉积物沉积剖面可划分为9个气候环境段: (1)温凉半湿润的针阔叶混交森林草原气候环境; (2)寒冷干旱的针叶森林草原气候环境; (3)温凉半干旱的针、阔叶混交疏林草原气候环境; (4)温暖湿润的针、阔叶混交森林草原气候环境; (5)凉半干的针、阔叶混交疏林草原气候环境; (6)温湿的针叶疏林草原气候环境; (7)温凉半干旱的针阔叶混交疏林草原气候环境; (8)凉半湿润的森林草原气候环境; (9)冷干的疏林草原气候环境.研究成果揭示了青藏高原东部边缘至四川盆地过渡带3.0~1.5万年间的古气候古环境演化特征, 为区域环境研究提供了宝贵的资料.      

Late quaternary of the middle Caquetá River area (Colombian Amazonia)

The late Quaternary history of the middle Caquetá River area in Colombia, northwestern Amazonia is described, based on observations of river bank sections, radiocarbon dates and palynological analyses of organic layers in floodplain and low terrace sediments of the Caquetá River. It is shown that the Late Pleistocene and Holocene climatic changes that took place in the Andean Cordilleras, were related to the depositional and erosional history of the Caquetá River in the Colombian Amazonian lowlands. The low terrace sediments consist of sandy and gravelly deposits covered by clays that sometimes contain lenses of peaty material. From these organic low terrace sediments, seven finite radiocarbon dates were obtained of Middle Pleniglacial age, between 56 000 and 30 000 yr BP. The coarse textured basal deposits of the low terrace apparently stem from the early part of the Middle Pleniglaciai period, during which the effective rainfall in the Andes was relatively high and the Andean glaciers had a considerable extension. Palynological data from silty sediments with organic remains at one site, show an interval when drier and more open types of vegetation on poor soils must have covered a larger area than today, but Amazonian forest was still the dominating type of vegetation. This interval might correspond to one of the Middle Pleniglacial savanna intervals from eastern Amazonia (Carajas). No organic sediments from the Upper Pleniglacial period were found and hence radiocarbon dates were not obtained. In the Andes this period had a very cold climate with low effective rainfall and in the east Amazonian Carajas area it is characterised by the relative extension of open savanna vegetation. The river run-off and sediment transport must have been much lower than in the Middle Pleniglacial and the Caquetá River cut itself down in its own sediments. Two Late-glacial radiocarbon datings obtained at one site (ca. 12 500 yr BP) indicate the existence of a Late-glacial sedimentation phase, separated from the Holocene sequence by a minor erosional phase. Organic layers in the Holocene floodplain sediments yielded 28 radiocarbon dates between 10 000 and 355 yr BP. Holocene sedimentation started with the rapid deposition of (sandy) clay possibly in a partly permanently inundated Caquetá valley. During the major part of the Holocene (silty) clays were deposited, with a dominant seasonal inundation cycle.     

台湾海峡西部海域晚第四纪地层

对台湾海峡西部海域的16个柱状岩芯进行孢粉、硅藻、有孔虫、¹⁴C和古地磁的系统分析测定,将本海域的晚第四纪地层自老到新划分为E、D、C、B、A层。研究结果证实了早武木冰期中晚期的琅岐海侵层（D层上部）、武木亚间冰期的福州海侵层（C层）和冰后期的长乐海侵层（A层）的存在,并首次发现里斯-武木间冰期的金门海侵层（E层）。研究表明,晚武木冰期吋本海域仍为浅海环境,沉积了“海峡海侵层”（B层）。     

南黄海陆架区CSDP-1孔沉积物碎屑锆石U-Pb年龄物源判别

南黄海作为东部陆架海的一部分,其沉积物记录了源区、气候及古环境演变等多方面的信息。本文利用激光剥蚀等离子体质谱（LA-ICPMS）的方法,对南黄海西部CSDP-1孔沉积物进行了碎屑锆石U-Pb年龄测定。结果表明,CSDP-1孔沉积物碎屑锆石主要表现出300~100,500~300,1 000~700,2 100~1 700和2 600~2 300 Ma 5组年龄区间。由底部到顶部,钻孔沉积物中除了1 000~700和2 100~1 700 Ma的锆石质量分数变化较大,其他年龄组的锆石质量分数没有明显的变化趋势;长江、黄河、废黄河和淮河作为钻孔区域可能的物质来源,其沉积物碎屑锆石U-Pb年龄分布存在显著差异,其中长江沉积物以1 000~700 Ma的锆石为特征,黄河沉积物中2 100~1 700 Ma的锆石质量分数最高,废黄河与淮河沉积物中500~300 Ma的锆石质量分数均比黄河和长江沉积物高。通过对CSDP-1钻孔及河流沉积物进行物源判别并结合相关性分析可认为：钻孔沉积物3.20 Ma以来存在多源物质贡献,长江源物质占优势,淮河源次之;淮河从2.16 Ma开始对钻孔区域有影响;0.78 Ma该区开始有黄河源的物质,且以黄河沉积物为主要物质来源;废黄河对钻孔区域几乎没有影响。     

Infilling of the Younger Kathmandu–Banepa intermontane lake basin during the Late Quaternary (Lesser Himalaya,Nepal): a sedimentological study

The Kathmandu and Banepa Basins, Central Nepal, are located in a large syncline of the Lesser Himalayas. The Older Kathmandu Lake evolved during the Pliocene and early Pleistocene; the Younger Kathmandu Lake, which is the focus of this study, is infilled with late Quaternary sediments. Three formations, arranged in stratigraphical order, the Kalimati, Gokarna and Thoka Formations formed during the infilling stage of this lacustrine basin. Structural and textural sedimentological analyses, a chemical survey across the basin and mineralogical investigations of fine‐grained sediments form the basis of this palaeogeographical study. The basin under investigation was covered by a perennial freshwater lake before 30 000 yr BP. The lake was infilled with alluvial and fluvial sediments delivered mainly from the mountains north of the basin. A fairly low gradient was favourable for the formation of diatomaceous earths, carbonaceous mudstones and siltstones, which were laid down in the centre of the lake and in small ponds. Towards the basin edge, lacustrine sediments gave way to deltaic deposits spread across the delta plain. Crevasse splays and anastomosing rivers mainly delivered suspended load for the widespread siltstones and mudstones. The proximal parts of the alluvial–fluvial sedimentary wedge contain debris flows that interfinger with fine‐grained floodplain deposits. Three highstands of the water‐level (>30 000 yr BP, 28 000–19 000 yr BP, 11 000–4000 yr BP (?)) have been recognised in the sedimentary record of the younger Kathmandu Lake in the Late Quaternary. Second‐order water‐level fluctuations are assumed to be triggered by local processes (damming by tectonically induced landslides). First‐order water‐level fluctuations are the result of climatic changes. Copyright © 2003 John Wiley & Sons, Ltd.     

关于江苏建湖庆丰剖面全新世沉积环境与海面变化关系的讨论

应用有孔虫、介形虫、软体动物和现代沉积环境等方面的研究成果,对江苏建湖庆丰剖面所显示的全新世沉积环境和海面变化进行讨论。认为在露头上大量原地埋藏的软体动物壳体指示环境的作用比有孔虫埋藏群更有意义。庆丰剖面所揭示的情况是 6 0 0 0～ 12 70aBP该地区一直处于潮间带-河口湾环境。 6 0 0 0aBP以前海面是上升的,6 0 0 0aBP达到了与现今海面相当的位置,其后海面是稳定的,看不出海面波动现象。     

一种新的粒度指标:沉积物粒度分维值及其环境意义

根据分形理论，对1000个不同类型沉积物样品的粒度分形结构及其分维值作了定量计算。结果表明：各类型沉积物都具有良好的统计自相似性，并且各自有着不同的分维值。粒度分维值的大小与分选好坏密切相关。没有经过外力搬运与分选的风化破碎物质(碎屑物)——断层泥、冻土的粒度分维值接近于碎形体的分维值2．60左右；经过外力搬运但分选作用较弱的冰碛物、水石流、泥石流堆积物的粒度分维值也接近2．60；而经过强烈外力分选作用的河床、湖泊沉积物、潮滩及海底沉积物的分维值明显偏小。鉴于此，本认为分维值可以作为沉积物类型判别的重要参数之一。     

Sediment provenance of the Wilderness barrier dunes,southern Cape coast,South Africa

Trace‐element geochemistry has been used to discern the provenance of sediments derived from geologically distinct sources found in a range of depositional settings. This study investigates whether this approach can also identify provenance signatures in sediments derived from clastic sedimentary rocks of similar origins, within a complex coastal transport environment. The potential local sediment sources of a coastal barrier dune in South Africa were analysed to assess their relationships with the barrier and whether these have varied with time. Results indicate that the oldest part of the barrier, partly formed during MIS 6 when sea levels were lower than at present, has a closer affinity to fluvial sediment provided by local rivers than either younger samples from the barrier′s seaward flank or the Holocene dunes atop its crest, both formed during sea‐level highstands. Constraints on the timing of barrier formation provided by OSL dating proved helpful in discriminating between provenance and weathering signals. Terra Nova, 00, 000–000, 2010     

Chronology of Hydrothermal Activity Within the Yubileynoye Ore Field (Mid-Atlantic Ridge, 20°08′ N)

This paper reports on the integrated geochronological and geochemical methods used in studying the ore deposits and metalliferous sediments of the Yubileinoye field. This study gives the opportunity to carry out cross dating of hydrothermal deposits, including the ²³⁰Th/U dating of sulfides, the ²³⁰Th, ¹⁴C dating, and foraminiferal analysis of the sediments, and, on this basis, to reconstruct hydrothermal activity over time. It was established that the ores started forming about 100 000–123 000 years ago and were renewed 4–5 times with a frequency of 10–20 ka. As a result, the complex of pyrite-marcasite, chalcopyrite and sphalerite ores and the associated metal-bearing and ore-bearing sediments with consistent geochemical specialization were formed. The integrated geochronological and geochemical studies of the ores and sediments allow us to obtain detailed data on evolution of the hydrothermal ore-formation not only in the certain areas but also for the entire Mid-Atlantic Ridge.