Optical Dating Equivalent Dose (De) Comparison of Global Standardised Growth Curve (gSGC) and Single-aliquot Regenerative-dose (SAR) Methods for Quartz Grains

Optical dating is a method of measuring the time since the sample was buried from last thermal event or light exposure. Samples such as quartz and feldspar grains are the most commonly used sediment of measurement. Single-Aliquot Regenerative-dose (SAR) method has become the most acceptable procedure for obtaining the equivalent Dose (D_e) of a sample. The Standardised Growth Curve (SGC) method provides a possible procedure for measuring a large number of samples; the limitation is that the growth curve fitted by different samples or even different aliquots is divergent. The global Standardised Growth Curve (gSGC) method improves the shortage by normalizing the dose response curves using one regenerative dose OSL signal. The gSGC provides a possible method for obtaining the D_e value of the sample efficiently and quickly. However, due to the radiation dose rate, operating procedures and instrument error and the selected regenerative-dose normalized dose value, etc., each laboratory should develop their own gSGC which has unique parameters. This study established the gSGC curve and measurement process of our laboratory, and then compared the consistency of the equivalent Dose (D_e) values from gSGC and SAR methods. In gSGC procedure, the D_e value of an aliquot can be estimated from the nature signal, one regenerative dose signal and their corresponding test dose signal. It will speed up the optical dating measurement rate of our laboratory and provide reference to establish gSGC in other laboratories. It is found that in the low dose range (0~100 Gy) the obtained D_e values were well consistent by gSGC and SAR methods. There were obviously differences in the higher dose range (>100 Gy) compared to the SAR results. It may be due to the insufficient number of older samples used to fit gSGC in this study. It is necessary to gradually accumulate more samples to improve the gSGC parameters in the future work. For some aliquots, individual quartz grains do not follow the global standardised growth curve, which leads to some deviations of D_e from gSGC. However, these two methods could obtain the similar average De value when multiple aliquots measuring.     

海啸波作用下泥沙运动——Ⅱ.床沙组成变化分析

在波浪水槽实验的基础上,对海啸波作用下的床沙组成变化规律开展研究。实验采用1/10~1/20的组合坡度,选取N波作为入射波。实验对波高进行采集,对波浪的上爬、回落和水跃过程进行拍摄记录,对每个波作用后的地形进行测量,并对初始和最终的床面顶层泥沙进行采样筛分。实验结果表明,N波作用下泥沙在离岸区水跃发生区域堆积,淤积沙坝泥沙粒径呈粗化趋势。同时采用规则波和非规则波进行对比,波浪作用后形成岸滩也为沙坝剖面,淤积沙坝泥沙粒径呈细化趋势,结果均遵循Çelikoğlu提出的泥沙运动的基本规律,细颗粒泥沙会在强烈的紊动作用下从床面中被筛选出来,并被搬运到低紊动地区,此过程造成了剧烈紊动区泥沙的粗化。     

Polarimetric properties of the reflection nebula R Mon/NGC 2261

The linear polarization of the reflection nebula R Mon/NGC 2261 has been observed since November 1991 with a multi-channel polarimeter at Dodaira Observatory, one of the branches of the National Astronomical Observatory of Japan. Results of the observations are reported.     

Wind anisotropy revealed by dust formation around wolf-rayet stars

The presence of heated circumstellar dust around WC type Wolf-Rayet stars requires the episodic or persistent condensation of carbon grains in their stellar winds. In order to survive in the stars' strong ultraviolet radiation fields, the grains must be located at least 100AU from the stellar surfaces. The densities in isotropic winds at such large distances are too low to allow grain growth and anisotropies such as clumps, disks or wind-collision wakes in colliding-wind binary systems are required to provide grain nurseries. Observational evidence for such features in grain-forming W-R stars is examined.     

金矿物及其赋存状态

已发现的金矿物有60余种。本文将其分为七类。在附表中列有20种较常见的金矿物及其鉴定特征。金在自然界中有三种赋存状态:可见独立矿物形式;呈次显微状于载体矿物中;或以原子状态混入其他矿物。金的工业矿物以第一种赋存状态为主,它们常与黄铁矿、毒砂、黄铜矿、磁黄铁矿、闪锌矿、方铅矿、黝铜矿和石英等连生,或以其作为载体矿物。呈次显微状的金,是以粒径小于0.2um的球粒形质点,呈机械混入物状态于黄铁矿等硫化物中。     

斜向波作用下海底管线周围床沙组成变化

海底管线周围的不平衡输沙影响着海底管线的局部冲刷,进而影响海底管线的安全运营。基于波浪港池实验,考虑规则波的作用,采用中值粒径为0.219 mm的原型沙铺设与波浪传播方向成45°夹角的斜坡,斜坡坡度为1∶15,研究管线局部冲刷坑床沙组成变化情况。实验结果表明:与冲刷深度随时间的发展类似,冲刷宽度随时间的发展也分为初级阶段和次级阶段;管线周围床沙粗化程度最高的地方并不在管线的正下方,而在管线的后下方;周期增加,冲刷坑床沙粗化程度增大;与原始床沙相比,周期较小时,冲刷坑下方床沙细化,周期较大时则粗化,而波高对床沙扰动的影响具有不稳定性。     

Holocene changes in precipitation seasonality in the western Mediterranean Basin: a multi‐species approach using δ13C of archaeobotanical remains

Precipitation has been of utmost importance in shaping the evolution of landscapes and human settlements in the Mediterranean. However, information on seasonal precipitation patterns through the Holocene is scarce. This study attempts to quantify the evolution of seasonal precipitation in the East Iberian Peninsula (5000 BC to AD 600) based on the carbon isotope composition (δ¹³C) of archaeobotanical remains. Data on Holm oak, Aleppo pine and small‐grain cereals were combined, and precipitation was inferred from models relating present‐day records to the δ¹³C of modern samples. Subsequently, charred grains were used as a proxy for ancient moisture during April–May, whereas oak and pine charcoals provided complementary rainfall estimates for September–December and January–August, respectively. The results reveal aridity changes throughout the Holocene in the western Mediterranean. Past spring–summer precipitation was consistently higher than at present. In contrast, autumn and early winter precipitation showed stronger fluctuations, particularly during the first millennium BC, and often exhibited values below those of the present. The high contribution of autumn precipitation to the annual water budget, typical of the present Mediterranean climate, was definitively established at the beginning of the current era. This study shows how a combination of species holding complementary environmental signals can contribute to a wider knowledge of local precipitation dynamics. Copyright © 2011 John Wiley & Sons, Ltd.     

On laboratory studies of grains from outside the solar system

An overview is given of the identified surviving presolar grains in primitive meteorites. Two of these phases are discussed in more detail: (a) Presolar silicon carbide, with special emphasis on heavy element isotopic compositions which trace the slow neutron capture process (s-process) of nucleosynthesis. It is argued that there are problems either with the grain or neutron capture cross section data or with current basic understanding of heavy element nucleosynthesis, (b) Presolar diamonds, where new developments are discussed concerning the origin of the (supernova) Xenon-HL component thought to be contained within them; in addition, arguments are presented in favor of diverse carrier phases for the various Xe components observed in diamond separates.     

澜沧江流域主要断裂断层泥中石英碎砾表面SEM特征及其断裂活动研究

根据断层泥及地层中石英碎砾表面SEM结构特征的研究，澜沧江断裂带早，中更新世是其主要活动时期，晚更新世活动减弱，全新世以来基本不活动；澜沧－勐遮断裂，孟连断裂晚更新世以来至全新世仍明显活动；木戛断裂，谦迈河断裂，平掌寨断裂及贵基处－瓦窑断裂晚更新世后期以来基本不活动。因此澜沧－勐遮断裂，勐连断裂术及相关地区未来地震地质灾害频度相对较高。     

Palynology of Upper Cretaceous (uppermost Campanian–Maastrichtian) deposits in the South Yellow Sea Basin, offshore Korea

Forty-seven samples from Upper Cretaceous sections penetrated by the Kachi-1 and Inga-1 wells in the South Yellow Sea Basin have been analysed for their spore and pollen content. Thirty-five species of 18 spore genera and 54 species of 28 pollen genera are documented. One new monotypic genus, Diporocolpopollenites, and its type species, D. kachiensis sp. nov., are erected, and Dilwynites Harris, 1965, and its type species, D. granulatus Harris, 1965, are emended. There are also three new combinations: Ephedripites eocaenicus (Selling, 1944), E. praeclarus (Chlonova, 1961), and Retitricolpites anguloluminosus (Anderson, 1960). Two palynological zones are erected: anAquilapollenites attenuatus Assemblage Zone, which encompasses deposits that are considered to be latest Campanian–Early Maastrichtian in age, and an Aquilapollenites eurypteronus Assemblage Zone for sections that have been dated as Late Maastrichtian. The assemblages are typical of the Yenisey-Amur Subprovince of the Aquilapollenites (floral) Province. Lowland floodplain to shallow, commonly mesotrophic, lacustrine environments of deposition are indicated. The climate was probably wet subtropical, with rainfall being somewhat higher during the Late Maastrichtian than through the latest Campanian–Early Maastrichtian.