10Be dating of Younger Dryas Salpausselkä I formation in Finland

Boulders of the Younger Dryas Salpausselkä I (Ss I) formation west of Lahti, southern Finland, were sampled for surface exposure dating. The ¹⁰Be concentrations, determined by accelerator mass spectrometry, yield minimum exposure ages of 11 930 ± 950, 11 220 ± 890, 11 050 ± 910 and 11 540 ± 990 years, using recently published production rates scaled for latitude and elevation. This includes a correction to the production rate resulting from postglacial uplift of the Fennoscandian lithosphere (i.e. changing elevation) during the time of exposure. The error‐weighted mean exposure age of 11 420 ± 470 years of the analysed boulders agrees with previous varve dates of Ss I, which range from 11 680 to 11 430 calendar years BP. However, erosion has to be taken into account as a process affecting rock surfaces and therefore influencing exposure ages. Available information suggests an erosion rate of 5 mm/kyr, which increases the error‐weighted mean exposure age to a value of 11 610 ± 470 years. Within the errors, the formation of Ss I in the Vesala area west of Lahti falls into the Younger Dryas time bracket, as defined by the GRIP and GISP 2 ice core (Greenland).     

Cosmogenic 10 Be ages on the Pomeranian Moraine, Poland

Rinterknecht, V. R., Marks, L., Piotrowski, J. A., Raisbeck, G. M., Yiou, F., Brook, E. J. & Clark, P. U. 2005 (May): Cosmogenic ¹⁰Be ages on the Pomeranian Moraine, Poland. Boreas , Vol. 34, pp. 186–191. Oslo. ISSN 0300–9483.
We measured the ¹⁰Be concentrations in boulders collected from the Pomeranian Moraine in Poland, providing the first direct dating of the southern margin of the Scandinavian Ice Sheet (SIS) in the Polish Lowland. The mean age of 8 ¹⁰Be ages of the Pomeranian Moraine in northwestern Poland is 14.30.8 ¹⁰Be ka, while in northeastern Poland the mean age of 19 ¹⁰Be ages of the moraine is 15.00.5 ¹⁰Be ka. Given the excellent agreement between the two age groups, we calculate a mean age of 14.80.4 ¹⁰Be ka for final deposition of the Pomeranian Moraine of northern Poland. The age of the Pomeranian Moraine suggests that the southern margin of the SIS was near its maximum extent in Poland at a younger time than previously inferred, and that retreat from the moraine at 14.80.4 ¹⁰Be ka probably occurred in response to the onset of the Bølling interstade.     

Cosmogenic and bomb-produced7Be in stratospheric air

Concentration of⁷Be has been measured in 15 air filters flown at 18·3 km in the latitudes 10 to 25°N and longitudes 80 to 96°W. Testing of nuclear weapons in atmosphere increased⁷Be considerably, on two occasions, above the expected cosmic-ray production level in the stratosphere. This provides evidence for the existence of interhemispheric mixing,via stratosphere.     

冰碛垄表面碎屑物质宇生核素暴露测年可行性研究

原地生宇宙成因核素(宇生核素)~(10)Be和~(26)Al暴露测年技术已广泛应用于各种地貌年代测定,尤其是在冰川地貌年代测定中备受青睐。多数学者通常选择冰碛垄表面散布的冰川漂砾作为测年对象。然而,冰川漂砾在暴露测年研究中存在暴露后期翻转、不等时暴露等问题,不仅影响冰川地貌测年的精度,而且难以获得较老的冰川地貌年代。冰碛垄表面碎屑物质,一直附着于冰碛垄"表面",可以规避冰川漂砾测年存在的不等时暴露问题,而且可以减少测试样本量、降低测试费用。因此,本文尝试探讨利用冰碛垄表面碎屑物质进行暴露测年研究的可行性,可望为较老冰川地貌暴露测年研究提供新的思路。     

宇宙成因核素26Al/10Be埋藏测年法在宁夏沙坡头黄河砾石阶地年代研究中的应用

本文利用宇宙成因核素26Al/10Be埋藏测年法对宁夏沙坡头地区黄河左岸的T5、T6、T8和T9阶地开展了年代学研究。采用简单快速埋藏模式获得4级阶地的26Al/10Be埋藏年龄分别约为0.25Ma、0.36Ma、0.59Ma和1.06Ma,如果考虑后期剥蚀作用的影响（E≈5m/Ma）,则4级阶地的年龄分别约为0.42Ma、0.39Ma、1.02Ma和1.59Ma。本研究未发现砾石大小与10Be、26Al核素浓度及26Al/10Be比值有明显相关性。     

Cosmogenic radionuclide dating indicates ice‐sheet configuration during MIS 2 on Nordaustlandet,Svalbard

Hormes, A., Akçar, N. & Kubik, P. W. 2011: Cosmogenic radionuclide dating indicates ice‐sheet configuration during MIS 2 on Nordaustlandet, Svalbard. Boreas, 10.1111/j.1502‐3885.2011.00215.x. ISSN 0300‐9483.0300‐9843 Glacial geological field surveys, aerial image interpretation and cosmogenic radionuclide (CRN) dating allowed us to reconstruct the ice‐sheet configuration on Nordaustlandet, the northernmost island of the European sector on the margin of the Arctic Ocean. The timing of deglaciation was investigated by determining the ²⁶Al and ¹⁰Be ages of glacially scoured bedrock, weathered periglacial blockfields and glacial erratic boulders. Only ¹⁰Be ages were useful for our interpretations, because of unresolved analytical problems with ²⁶Al. Fjords and lowlands on Nordaustlandet yielded Late Weichselian ¹⁰Be ages, indicating that actively erosive ice streams scoured the coastal fjord bathymetry during marine isotope stage (MIS) 2. In Murchisonfjorden, ground‐truthed air‐photograph interpretation and ¹⁰Be ages of boulders indicated a cold‐based glacier ice cover during MIS 2 on higher plateaus. ¹⁰Be ages and lithological studies of erratic boulders on higher and interior plateaus of Prins Oscars Land (>200–230 m a.s.l.) suggest that the Mid‐Weichselian glaciation (MIS 4) might have been more extensive than that during MIS 2.     

10 Be在大洋边缘海洋学中的应用及模型

主要讨论宇宙射线成因核素¹⁰Be（T _1/2＝ 1．5Ma）在大洋边缘海洋学尤其是中国近海海洋研究中的应用。在过去的近20年中，在中国开展的¹⁰Be研究在黄土堆积年龄及地层对比方面获得了诸多成果，但在海洋方面的应用研究距国际水平仍有一定的差距，尚需进一步加强。综述了海洋环境中¹⁰Be作为一个地球化学示踪剂的研究现状，着重介绍¹⁰Be在中国东部海域的收支平衡模式以及讨论¹⁰Be在太平洋西部边缘海及岛弧地区的应用前景。     

Cosmogenic Be inferred lake-level changes in Sumxi Co basin, Western Tibet

Most Tibetan lakes are surrounded by conspicuous regressive shorelines attesting to high-water levels in the past. Concentrations of the in situ produced cosmogenic radionuclide ¹⁰Be in bedrock from the three highest terraces surrounding Sumxi Co, situated in Western Kunlun, indicate that the highest lake-level appeared before 10,000–11,500 yr, and most likely between 11,000 and 12,800 yr. Younger ages for the two lower terraces imply regression of Sumxi Co during the early-mid Holocene. The concurrency of the highest lake-level with orbitally induced maximum northern hemisphere summer insolation suggests that the increase in water supply to Sumxi Co was most likely associated with increased recharge from melting glaciers. We conclude that the enhanced Indian monsoon during the early Holocene did not penetrate the Tibetan plateau and affect the northwestern part of Tibet significantly.     

宇宙成因核素~(10)Be揭示的北祁连山侵蚀速率特征

山脉侵蚀速率的大小和时空分布信息是研究山脉构造—气候相互作用和地貌演化的关键切入点,其大小是受气候还是构造控制争论已久。宇宙成因核素10Be方法为从千年至万年尺度上定量研究流域平均侵蚀速率提供了一种先进和快捷的技术手段,为揭示侵蚀速率与现代气候和构造地貌因子的关系并进行相关分析提供了基础。利用该方法对北祁连山近现代侵蚀速率进行了研究。所采集的9个流域现代河沙样品,结合前人数据进行共同分析,结果显示该区侵蚀速率的变化范围为18.7~833 mm/ka,北祁连山中段的侵蚀速率约为323 mm/ka,该区侵蚀速率与降雨量没有明显的对应关系,但与流域平均坡度呈现很好的非线性关系,揭示坡度是该区侵蚀速率的最主要控制因素。通过对比北祁连山地表平均侵蚀速率和该区域的断层垂直滑动速率发现整体上该区域地表侵蚀速率要低于祁连山北缘断层的垂直滑动速率,反映了北祁连山正处于地形抬升和生长的过程之中。     

Comparison between radiocarbon and varve dating in Lake Lampellonjärvi, south Finland

The annual nature of organic laminations in the sediment from a small lake, Lampellonjärvi (61°04'N; 25°04'E), was determined. The core was obtained using an in situ freezing method and the laminations were checked by a detailed microscopical analysis of adhesive tape preparations. A series of six radiocarbon dates were obtained for levels in the core which had previously been dated by means of varve counts to ages between A.D. 182 and AD. 1513. The radiocarbon dates were between 547 and 1525 years older. Two additional ¹⁴C dates from the lower part of the same profile (ca. 1880 B.C. and ca. 3100 B.C.), however, gave expected results. Erosion of old organic terrestrial material due to agricultural activity in the surroundings of the lake was assumed to have been the cause of abnormally old radiocarbon ages. Dates from the pre-agricultural period had a deviation from varve years similar to the difference between tree rings, historical documents and radiocarbon dating recorded in other studies.     

黄土中宇宙成因核素10Be示踪古地磁场变化研究进展

宇宙成因核素10Be示踪古地磁场的研究在海洋和冰芯研究中得到了广泛应用,然而受黄土来源及沉降过程的复杂性制约,运用中国黄土10Be示踪古地磁场变化的研究直到近年来才取得突破进展.综述了黄土10Be的研究现状并指出将其应用于地磁场示踪研究存在的关键问题,重点介绍了为分离黄土10Be浓度记录所包含的气候因素和地磁场影响因素而建立的LGM分离方法、剩磁矫顽力估算模型方法和平均值概念方法.各种创新数理方法的建立基本解决了黄土10Be示踪古地磁场的科学难题,使黄土10Be示踪古地磁场变化研究成为可能.     

闽西南地区紫金山岩体锆石SHRIMP定年及其地质意义

笔者通过锆石SHRIMP定年,精确厘定了紫金山岩体的成岩成矿时代.紫金山黑云母化岗岩中锆石CL图像显示锆石分为3种形态,定年结果显示这3种锆石有不同的年龄,具有不同的地质意义.第一种锆石晶形发育、具有核一边双层结构.核部的锆石呈磨网状,这类锆石为继承性锆石,年龄为1000 Ma左右;第二种锆石晶形发育良好,但是呈不完整形态,有不清晰的生长环带或者无生长环带,呈现岩浆锆石的特征,年龄为168±4 Ma(n=13,MSWD=0.97),这一年龄应代表了岩石的结晶年龄,属于中侏罗世;第三种锆石晶形发育良好,有清晰的生长环带,这种锆石受后期改造作用,年龄为(119±15)Ma,属于早白垩世.(168±4)Ma时本区并未发生大规模的成矿事件,因此紫金山岩体主体并非含矿岩体,仅有轻微的锡矿化.紫金山花岗岩锆石SHRIMP定年的第三组年龄为(119±15)Ma是大规模成矿作用的记录,可能正是这一期的热液作用开始了本区大规模的长时期的多期次的岩浆热液作用的序幕,从而为本区铜金成矿作用奠定了基础.     

Cosmogenic10Be: A critical view on its widespread dominion in geosciences

The radionuclide¹⁰Be (half-life = 1.5my), produced naturally in the Earth’s atmosphere by nuclear interactions of cosmic rays, was sought in ocean sediments in the late fifties, considering its potential usefulness as a radiotracer for dating sediments.¹⁰Be was discovered independently by two groups, one in India and the other in the USA, and used only for dating marine sediments and manganese nodules until the seventies. Subsequently, as a result of a technical advance resulting in the improvement in the sensitivity of measurement of¹⁰Be by about a factor of 10⁶, there was a global rush to measure this nuclide in most materials participating in the physical, chemical and biological processes in the dynamic geosphere. This paper outlines the reasons for this “isotope rush”, and the lessons learned from these studies. I also present my personal views of the special attractive features of this nuclide on the one hand, and on the other, the pitfalls or the wrong message this nuclide could convey!     

昆仑山垭口地区"望昆冰期"冰碛宇宙成因核素10Be测年

昆仑山垭口地区是东昆仑山现代冰川作用中心之一,在第四纪冰期间冰期旋回中保留了多套较为完整的冰川沉积.位于垭口盆地西侧山脊上的望昆冰碛,是本区已知最老的冰川沉积.应用宇宙成因核素10Be暴露年龄方法对望昆冰碛进行年代测定,5个样品中有4个介于(56.9±5.6)～(38.2±3.5)ka BP之间,相当于MIS3阶段,明显年轻于前人所测ESR和古地磁年代,且与地貌系列不符.这一结果不能代表望昆冰碛的实际年代,而应为所测漂砾后期暴露的年代,反映了MIS3阶段昆仑山垭口地区曾遭受过强烈地表剥蚀过程.望昆冰碛10Be暴露年龄显著地年轻,表明应用宇宙核素暴露年代测定冰碛物形成时代具有复杂性,应充分考虑后期剥蚀等地表过程,并应使用其他测年方法进行相互验证.     

Three-dimensional geologic modeling and visualization of the Virttaankangas aquifer,southwestern Finland

A need exists for a reliable and long-term water supply for the 285,000 inhabitants of the Turku area in southwestern Finland. In response to this need, there are plans to replace the present water supply from the surface sources with artificially infiltrated groundwater from a Quaternary esker aquifer called the Virttaankangas aquifer. New sedimentological studies of the Virttaankangas area have revealed the complexities of the esker system and its surrounding glacial, glaciofluvial, and glaciolacustrine geology. This led to the characterization of the hydrogeological units of the aquifer, the result of which has been a three-dimensional (3-D) truly integrated solids model that represents the geometry, interrelationships, and hydrostratigraphy of the study area. The 3-D model was made with EarthVision geologic modeling software. The 3-D geological model of the Virttaankangas aquifer can be used for planning the infiltration of river water into the aquifer and to understand the geologic and geographic boundaries of the hydrogeologic units hosting the groundwater reserve and the geologic relationships between the units. Another major outcome of this study is a powerful visualization tool that will be provided to municipal and government authorities who must understand the geologic complexities involved with water-resource planning prior to their decision making. Electronic Publication     

Luminescence dating of neotectonic activity on the southwestern coastal plain,Taiwan

The southwestern coastal plain of Taiwan is heavily urbanised, with a population of more than 6 million. The area is known to be subsiding, and the resulting basin is filled with thick fluvial deposits, of at least 200 m thickness. In the past century, three large earthquakes have occurred in the area; two caused surface ruptures, and resulted in large property loss and more than 2000 casualties. There is an urgent need for an understanding of the dynamics and recurrence intervals of this neotectonic activity, but little is known of the chronology of the late Pleistocene deposits. Recently more than 20 cores longer than 250 m were taken from the coastal plain as part of a large hydrogeological investigation, and basic data on lithology, hydrogeology and palaeobiology were collected. The base of these cores is beyond the ¹⁴C age limit, and so the application of luminescence dating to these sediments has been investigated.Optically stimulated luminescence methods have been applied to quartz sand-sized grains extracted from 29 samples. Dosimetry based on gamma spectrometry is also compared with ICP-MS and XRF analyses. In the age range up to ∼40 ka, radiocarbon ages are compared with the luminescence results, to give confidence that the initial bleaching of these sediments was sufficient. The luminescence ages are then discussed and differential rates of basin subsidence are deduced. It is clear from these data that the study area is tectonically active, and it may be that regions of similar subsidence rate correlate with identifiable geological structures.     

<Superscript>10</Superscript>Be surface exposure dating of the last deglaciation in the Aare Valley,Switzerland

The combined Rhone and Aare Glaciers presumably reached their last glacial maximum (LGM) extent on the Swiss Plateau prior to 24 ka. Two well-preserved, less extensive moraine stades, the Gurten and Bern Stade, document the last deglaciation of the Aare Valley, yet age constraints are very scarce. In order to establish a more robust chronology for the glacial/deglacial history of the Aare Valley, we applied ¹⁰Be surface exposure dating on eleven boulders from the Gurten and Bern Stade. Several exposure ages are of Holocene age and likely document post-depositional processes, including boulder toppling and quarrying. The remaining exposure ages, however yield oldest ages of 20.7 ± 2.2 ka for the Gurten Stade and 19.0 ± 2.0 ka for the Bern Stade. Our results are in good agreement with published chronologies from other sites in the Alps.     

Cosmogenic radionuclide dating of glacial landforms in the Lahul Himalaya,northern India: defining the timing of Late Quaternary glaciation

The timing of glaciation in the Lahul Himalaya of northern India was ascertained using the concentrations of cosmogenic ¹⁰Be and ²⁶Al from boulders on moraines and drumlins, and from glacially polished bedrock surfaces. Five glacial stages were identified: Sonapani I and II, Kulti, Batal and Chandra. Of these, cosmogenic exposure ages were obtained on samples representative of the Batal and Kulti glacial cycles. Stratigraphical relationships indicate that the Sonapani I and II are younger. No age was obtained for the Chandra glacial advance. Batal Glacial Stage deposits are found throughout the valley, indicating the presence of an extensive valley glacial system. During the Kulti Stage, glaciers advanced ca. 10 km beyond their current positions. Moraines produced during the Batal Stage, ca. 12–15.5 ka, are coeval with the Northern Hemisphere Late‐glacial Interstadial (Bølling/Allerød). Deglaciation of the Batal Glacial Stage was completed by ca. 12 ka and was followed by the Kulti Glacial Stage during the early Holocene, at ca. 10–11.4 ka. On millennial time‐scales, glacier oscillations in the Lahul Himalaya apparently reflect periods of positive mass‐balance coincident with times of increased insolation. During these periods the South Asian summer monsoon strengthened and/or extended its influence further north and west, thereby enhancing high‐altitude summer snowfall. Copyright © 2001 John Wiley & Sons, Ltd.