水相沉积物石英Ti心ESR测年可靠性初探

本文以北京顺义高丽营钻孔样品为测试对象,对其石英Ti心ESR信号进行了测试.结果表明,高丽营剖面B/M界限样品的ESR年龄为(861±89)ka,与已知古地磁结果偏差≤10%;用同样方法和参数测试不同深度的高丽营钻孔样品,其ESR年龄随样品深度增加而变老,符合水相沉积序列特征.以上研究结果表明,利用石英Ti心ESR法至少可以获得距今780 ka以来的水相沉积物的年龄.     

北京猿人遗址的ESR年代再研究

报道了第二批鹿牙样品的测年结果。采用新近发展的非线性拟合外推法获得样品的累积剂量。应用适合于牙釉质层样品的剂量率公式,计算了四种铀吸收模式的ESR年龄及其误差,得出了北京猿人遗址含有北京猿人头盖骨地层的年代分别为:第11层575±101ka,第8—9层409±72ka,第6—7层365±64ka和第3层290±51ka。     

科尔沁沙地全新世风沙沉积物的石英单测片蓝光释光测年和风沙活动年代学

通过科尔沁沙地内部甘旗卡固定一半固定沙丘地带五个处于不同微地貌的全新世古风沙沉积地层剖面的观测和取样,对25个沙丘砂、古土壤和相关沼泽沉积物样品采用粗颗粒石英单测片蓝光释光测年技术和程序进行沉积年龄测定,并对5个沼泽沉积物和古土壤样品进行有机碳14C年龄测定。在此基础上提出了研究区全新世沙丘活动的年代学框架,即在10-7.5 ka B.P期间沙丘由活动转为固定;约7.5 kaB.P至约(2.0±0.2)ka B.P.期间沙丘广泛发育草原或疏林草原土壤;从约(2.0±0.2)ka B.P以来沙丘又重新进入活动或半活动状态, 并主要取决于人类活动的影响。     

六盘山东麓断裂断层泥ESR测年研究

断层泥是断层活动的信息载体.利用电子自旋共振(ESR)方法对采自六盘山东麓断裂带中的断层泥样品进行了测年研究,断层泥ESR年龄远大于野外地貌估计年龄.扫描电镜(SEM)显示断层泥中石英颗粒呈现不同微形貌,可能是断层多期次活动的结果.由于不能把不同期次形成的颗粒分开,也不能确定最后一次强烈活动能否使ESR信号完全回零,所以,断层泥EsR测年仍存在许多不定因素,还需要进行深入、系统地研究.     

兰州盆地黄河三级阶地的光释光年龄

对兰州盆地黄河南岸范家坪三级阶地剖面进行了观测和地层结构分析,对剖面中段细粒沉积层以2.5cm的间隔采取了粒度、磁化率样品.通过对16个光释光(OSL)样品的细颗粒石英简单多片技术的测年以及下伏早期冲积层的电子自旋共振(ESR)测年,得到三级阶地地层剖面的年代学结果:下伏早期冲积层为中、下更新统范家坪组砾石层,黄河至少于8万年前在其上开始河床沉积,约7万年左右开始堆积以冲洪积相为主的细粒层.推测黄河三级阶地形成年龄约为7万年左右,对应晚更新世末次间冰期与末次冰期之间.     

不同释光方法测试冰川沉积物等效剂量的尝试

在青藏高原东部硬普沟采集6个冰川沉积光释光测年样品(2个现代样、3个新冰期和1个末次冰期样品),运用SAR结合SGC技术,采用石英大测片、小测片BSL以及多矿物IRSL等3种方法进行了等效剂量(De)的测试,SAR和SGC技术测得的De值相近。3种方法的测试结果表明,De值IRSL>大测片BSL>小测片BSL。多矿物IRSL测得的De值比石英BSL偏高,表明长石比石英较难晒退,不适于该地冰川沉积测年。石英大测片适于晒退较好的样品。该地石英的释光敏感性较低,小测片的测试情况不理想,且不能完全区分不同晒退程度的颗粒。对于年代较老的、较明亮的冰川沉积样品,石英小测片甚至单颗粒技术可能是可行的。今后需要更多研究如何应对释光敏感性低的样品的测试问题。     

关于牙釉ESR测年计算方法的讨论

一种新的针对薄层的牙釉样品的电子自旋共振测年方法－ROSY ESR测年程序是采用one-gruop传递理论计算牙釉中的β剂量率,其结果比原有的DATA程序计算出的β剂量率小,但与统计学中的蒙特卡罗理论计算结果更为接近,本文还采用ROSY和DATA两种方法计算了湖北郧县遗址的6个牙釉样品的年龄,并进行了比较。     

偃师商城宫城建筑基址夯土的光释光测年初步研究

用光释光测年技术对河南偃师商城宫城部分宫殿和围墙基址夯土进行了定年。在夯土基址的建造过程中，有些石英颗粒可能见光而使其光释光信号被释放回零，光释光‘时钟’重新开始计时。本文用单片再生剂量法测夯土中粗颗粒石英的等效剂量，测得的等效剂量值的分布说明石英颗粒的光释光信号在基址建造过程中有不同程度的晒退。据晒退相对彻底的石英颗粒得出的夯土光释光年龄分别是4.0ka、2.2ka和2.5ka。尽管这些年龄值与考古年龄存在差异，但表明用光释法测年技术对宫殿建筑基址夯土进行定年是可行的。     

释光断代的可靠性分析

释光断代是一种测年方法,利用的主要是石英等矿物晶体对放射性辐射的次级响应规律.该方法不受其他因素干扰,断代时间基本涵盖第四纪范围,而且适用样品广泛,在细颗粒沉积物测年方面方法独特,在一定程度上弥补了测年工作中的某些空缺,受到第四纪、考古、地震、水文、环境演变等专业研究人员的重视.不过,其断代数据时有偏差,引起应用人员的困惑.本文试图对此进行一些分析和讨论.     

聚四氟乙烯电子束辐射降解研究

研究了辐照剂量、辐照剂量率和辐照气体环境等因素对聚四氟乙烯(Polytetrafluoroethene,PTFE)薄膜电子束辐射降解效应的影响,并采用傅里叶变换红外(Fourier Transform Infrared Spectroscopy,FTIR)、电子自旋共振(Electron Spin Resonance,ESR)和X射线衍射(X-ray Diffraction,XRD)等方法进行分析。结果表明:电子束能够有效地对聚四氟乙烯进行降解。PTFE样品的辐射降解主要发生在主链C-C键上;在相同的吸收剂量和气体环境下辐照,低剂量率辐照样品降解好于高剂量率样品;而在相同的吸收剂量和剂量率下辐照,在空气中的辐照降解效果好于N2气环境下。     

释光技术在构造事件定年中的应用

利用矿物的释光现象进行测年已有几十年的历史,释光测年现已成为第四纪沉积物测年技术中的一个重要方法,尤其对一些不含有机碳和老于4万年的沉积物.本文介绍了释光测年的基本原理,分析了断层泥测年的可行性,以及释光测年技术在新构造定年中的应用和一些最新发展.     

Mass-spectrometric 10Be dating of deep-sea sediments applying the Zürich tandem accelerator

We have measured ¹⁰Be in deep-sea sediment cores from the Central North Pacific (GPC-3, 30° N 157° W) and from areas with high biological activity, off West Africa and the South Atlantic near Antarctica.In core GPC-3 we observe a decrease with depth which can be decomposed into three exponentials. Sediment accumulation rates of 2 mm/ka for the upper 2.2 m, 1.1 mm/ka for the section between 2.2 m and 4.7 m and 0.5 mm/ka from 4.7 m to 10 m have been derived. The changes in the accumulation rate occurred at 1.1 Ma and 3.3 Ma BP.In core GPC-3 the ¹⁰Be chronology agrees (20%) with paleomagnetic dating of the uppermost 4.2 m, corresponding to a time range of 2.43 Ma (Matuyama-Gauss Boundary).The average ¹⁰Be flux into the sediments at locality GPC-3 during the past 1.1 Ma is comparable to the assumed depositional flux from the atmosphere. On sediment cores from off West Africa and the South Atlantic we observe, on the contrary, fluxes of ¹⁰Be which exceed more than 10 times the depositional flux. This indicates that the concentration of ¹⁰Be in the open ocean at localities in the proximity of highly productive areas may be strongly modulated by variations of bioactivity throughout time.     

黑龙江向阳山地区盆地盖层沉积特征与砂岩型铀矿成矿前景分析

详细论述了向阳山地区盆地盖层的沉积体系和沉积相特征，并结合测井曲线将其划分为冲积扇和冲积平原两大沉积体系及五类沉积相,对每一沉积相从岩性、沉积构造、测井曲线的形态以及粒度分布等方面进行了详细的研究;分析了沉积相的时空展布特点和层间氧化带在泉二段中的发育情况。最后从沉积相发育的角度分析了研究区层间氧化带砂岩型铀矿的前景。     

CHEMICAL SPECIES OF IRIDIUM AND OTHER TRACE ELEMENTS IN THE CRETACEOUS-TERTIARY BOUNDARY CLAYS AND ITS IMPLICATION

The geological samples: Cretaceous- Tertiary (K- T) boundary clays, meteorites, volcanic lava, and ultrabasic rock were separated into carbonate, metal, sulfide, oxide, silicate and acid- resistant residue by a selective chemical dissolution procedure developed in our laboratory. Some conclusions were drawn by analyzing the chemical speciation of anomalous iridium in the above samples and especially by studying the characteristics of mineral components in those residue phases. (1) It is impossible that the anomalous Ir was caused by geochemical enrichment; (2) The iridium enrichment in the K- T boundaries did not necessarily associate with kerogen; (3) The volcano activity has participated in the extinction event at the end of Cretaceous; (4) Extraterrestrial impact was the trigger of K- T event. Then, we proposed a mixed model by which the extant anomalous Ir in K- T boundary clays was interpreted as a combined effect of extraterrestrial impact, volcano eruption and post- depositional redistribution.     

14C dating of small archaeological samples: neolithic to iron age in the central alpine region

Accelerator mass spectrometry (AMS) radiocarbon ¹⁴C dating will widen enormously the range and scope of archaeological investigations. This is due mainly to 100- to 1000-fold sample size reduction over conventional dating. In order to determine the size and the quality of samples that can be accepted for AMS ¹⁴C dating, we have selected archaeological samples relating to the Neolithic to Iron Age. The basis of our AMS target preparations is the coking (pyrolysis) of organic matter after elimination of impurities by various physical and chemical treatments. The effect of the morphology as well as of the grain size distribution of the charcoal particles was determined in order to achieve optimal conditions for accelerator dating.     

利用陶范或砂范对青铜器进行间接热释光断代

利用青铜器中残留的一些具有热释光特性的陶范或砂范对陕西出土的几件青铜器进行热释光测年研究,取得了满意的年代数据,测年精度一般都能达到８％－１２％。由于本方法在陶范取样过程中一般不会对青铜器本体造成伤害,使得这一热释光测年及真伪鉴别法具有更广阔的应用前景。     

Forensic applications of C at CIRCE

The decreasing trend of the radiocarbon pulse produced during the atmospheric tests of nuclear weapons (bomb-carbon) coupled with high sensitivity accelerator mass spectrometry (AMS) measurements, drastically increased the precision of radiocarbon age determinations since the second part of the sixties, allowing the application of radiocarbon AMS to a wide range of studies previously not directly involving conventional radiocarbon dating (i.e. food authenticity, forensic, biochemistry). In the framework of authenticity evaluation of artworks, high precision radiocarbon (¹⁴C) AMS measurements (ΔR/R < 0.3%) reduce the conventional uncertainty of the dating to few decades, allowing precise age estimation of materials containing carbon (C). The Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) during its activity on AMS ¹⁴C dating achieved high precision measurements opening the opportunity to these kinds of applications. This paper presents the main results obtained from radiocarbon measurements on a set of bone samples analyzed for the determination of the post-mortem interval in the framework of an unsolved case investigated by the Rome prosecutor office. The chronological characterization of the wooden support of the “Acerenza portrait” is also presented with the aim to evaluate its age and to further investigate the possibility to attribute this artwork to Leonardo da Vinci.Bomb-¹⁴C dating on the lipid and collagen fractions of bones allows the evaluation of the year of the death of the individuals by means of ad hoc calibration data sheet with the typical few years precision and difference between collagen apparent age and the year of death appeared in agreement with the age of one individual estimated by dating of tooth collagen. Conventional radiocarbon dating on both wood and wood extracted cellulose leads to an estimation of the portrait wood board age (2σ) of 1459-1524 AD (57% relative probability), 1571-1631 AD interval (42% relative probability).and 1559-1563 AD (1% relative probability). These results attribute with the highest relative probability an age comprised within the life span of Leonardo (1452-1519) to the support.     

Development of a web-based sorption database (KAERI-SDB) and application to the safety assessment of a radioactive waste disposal

Sorption plays a key role in a retardation of radionuclide migration in various geological environments. Hence sorption of radionuclides onto geological media is one of the important factors for the safety assessment of radioactive waste disposal. A web-based radionuclide sorption database program named KAERI-SDB has been developed to provide a database for the sorption of radionuclides onto geological media at various geochemical conditions. The KAERI-SDB is designed to determine the distribution coefficient (K_d) of a radionuclide and evaluate sorption properties by easily accessing an internet web-site (http://sdb.kaeri.re.kr). The KAERI-SDB provides a useful output and search result as a scatter plot chart or an index chart. The KAEI-SDB was designed to show the search results in a statistical way by representing the mean K_d value at 95% of confidence as a function of major geochemical indices. Several case studies were carried out to demonstrate the applicability of the KAERI-SDB and the result showed a successful applicability of the KAERI-SDB to various radionuclide sorption cases.     

ESR-铀系法牙齿化石测年及其在中早更新世考古遗址年代学研究中的应用

介绍了电子自旋共振(ESR)法与铀系测年法联合对牙齿化石测年的基本原理,通过引入参数p反映牙齿化石中各组织的铀吸收过程;阐述了ESR-U系联合测年法的测年时限、测年精度及影响因素.对于我国中早更新世考古遗址的化石测年具有潜在优势,是目前唯一可行的对老地点化石样品进行直接测年的方法.