ESR and OSL dating of fossil-bearing deposits from Naracoorte Cave Complex palaeontological sites,south Australia     

《Quaternary Geochronology》2022

Little work has been undertaken on combined dating of sedimentary quartz grains using electron spin resonance (ESR) and optically stimulated luminescence (OSL) techniques in Australia. This study aims to assess the suitability of a combined ESR and OSL dating approach for establishing improved chronologies of Middle-Late Pleistocene deposits within the Naracoorte Cave Complex (NCC), South Australia. Here, we apply ESR and OSL dating in tandem to a series of samples collected from three different NCC sites: Whale Bone, Specimen and Alexandra cave. ESR quartz dating focuses on the multi-centre (MC) approach, which involves comparative evaluations of Al and Ti centre signals, while paired luminescence dating focuses on single-grain OSL analysis and includes examination of multi-grain averaging effects. The comparative ESR-OSL dating results exhibit broad agreement for deposits spanning 50–150 thousand years, with either the Ti–H or Al centre ages overlapping with paired OSL ages at 2σ in nearly all cases. MC ESR evaluations (Al v Ti–Li v Ti–H age assessments) indicate incomplete resetting of the bleachable Al centre signal for a small number of samples. Two-thirds of samples exhibit Ti–Li ages that are significantly older than corresponding Al centre ages, which is unexpected from a bleaching kinetics perspective and may indicate a broader reliability issue for Ti–Li palaeodose evaluation with these particular samples. Our findings: (i) support the applicability of both palaeodosimetric dating methods in this depositional setting; (ii) highlight the merits of applying combined ESR-OSL analyses in tandem, and; (iii) provide one of the first reliable evaluations of quartz ESR MC dating for samples with natural dose ranges as low as only a few tens of Gy. These results show that the Whale Bone, Specimen and Alexandra cave sites are temporally related and can be used to derive multi-site reconstructions of faunal assemblages and palaeoenvironmental history.  相似文献   

Very high-frequency and seasonal cave atmosphere P_CO2 variability: Implications for stalagmite growth and oxygen isotope-based paleoclimate records     

James U.L. Baldini  Frank McDermott  Dirk L. Hoffmann  David A. Richards  Nicholas Clipson 《Earth and Planetary Science Letters》2008,272(1-2):118-129

Cave air P_CO2 at two Irish sites varied dramatically on daily to seasonal timescales, potentially affecting the timing of calcite deposition and consequently climate proxy records derived from stalagmites collected at the same sites. Temperature-dependent biochemical processes in the soil control CO₂ production, resulting in high summer P_CO2 values and low winter values at both sites. Large Large-amplitude, high-frequency variations superimposed on this seasonal cycle reflect cave air circulation. Here we model stalagmite growth rates, which are controlled partly by CO₂ degassing rates from drip water, by considering both the seasonal and high-frequency cave air P_CO2 variations. Modeled hourly growth rates for stalagmite CC-Bil from Crag Cave in SW Ireland reach maxima in late December (0.063 μm h^− 1) and minima in late June/early July (0.033 μm h^− 1). For well-mixed ‘diffuse flow’ cave drips such as those that feed CC-Bil, high summer cave air P_CO2 depresses summer calcite deposition, while low winter P_CO2 promotes degassing and enhances deposition rates. In stalagmites fed by well-mixed drips lacking seasonal variations in δ¹⁸O, integrated annual stalagmite calcite δ¹⁸O is unaffected; however, seasonality in cave air P_CO2 may influence non-conservative geochemical climate proxies (e.g., δ¹³C, Sr/Ca). Stalagmites fed by ‘seasonal’ drips whose hydrochemical properties vary in response to seasonality may have higher growth rates in summer because soil air P_CO2 may increase relative to cave air P_CO2 due to higher soil temperatures. This in turn may bias stalagmite calcite δ¹⁸O records towards isotopically heavier summer drip water δ¹⁸O values, resulting in elevated calcite δ¹⁸O values compared to the ‘equilibrium’ values predicted by calcite–water isotope fractionation equations. Interpretations of stalagmite-based paleoclimate proxies should therefore consider the consequences of cave air P_CO2 variability and the resulting intra-annual variability in calcite deposition rates.  相似文献   

湖北清江和尚洞洞穴温度对气候变化的响应   总被引：9，自引：6，他引：3  

何璐瑶  胡超涌  曹振华  马仲武  熊志方 《中国岩溶》2008,27(3):273-277

对湖北清江流域和尚洞内、洞外气温进行同步高频监测,发现洞穴温度响应洞外气温的变化,但由于受到洞穴的“缓冲作用” ,由外及里的温度变化幅度变小,时间滞后,且响应的快慢具有明显的季节性。2003- 2008年度监测的数据统计表明,在150m 洞深处,洞内日温度的变化幅度仅0. 2℃ ,明显低于洞外气温变化幅度( 6. 9℃ ) ;同样,洞内夏、冬季节温差变化( 6. 9℃ )也小于洞外( 31. 8℃ )。比较洞内外温度的时间序列,发现日尺度上,洞内气温滞后洞外0～ 2小时,而在季节尺度上则滞后10～ 40天,其中降温阶段滞后小,升温阶段滞后大。此外,一年四季中,洞内温度对外界气温变化的响应呈现慢( 2- 4月)→快( 5- 7月)→较快( 8- 10月)→较慢( 11- 1月)的特点,可能与不同季节下洞穴“缓冲作用”的强弱变化有关。   相似文献   

丹东形变观测洞室改造     

尤权民  姚圣安  迮安民  姚菲菲  陈尚尉  梁永信  隋玉鹏  邓志岩  刘芳彤 《地震地磁观测与研究》2009,30(3):74-79

“十五”期间,为了新增水管仪、伸缩仪,丹东地震台对形变观测洞室进行了环境改造,新建了仪器基墩,解决了建造仪器基墩过程中遇到的施工难题,为水管仪和伸缩仪运行提供了良好的观测条件。文中介绍的方法对其他台站建造仪器基墩有一定借鉴意义。  相似文献   

洞穴钟乳石类的分类方案   总被引：11，自引：7，他引：4  

朱学稳 《中国岩溶》2005,24(3):169-174

为填补我国洞穴钟乳石类尚无一较系统的分类方案的空白,根据我国洞穴调查与探测的现有研究程度与发现,和我国主要属“雨水型喀斯特”的基本特点,提出了一个以钟乳石类形成的水动力机制为基础,以形态特征为主导,较适宜于中国洞穴应用的分类方案,共有重力水沉积、非重力水沉积、协同沉积、叠置沉积和异因同形沉积五大类,列出和讨论了在国内洞穴中已被发现分属于各类的60多种个体形态名称及其部分特征。   相似文献   

塔河油田奥陶系岩溶洞穴发育特征及其与油气的关系   总被引：3，自引：1，他引：2  

景建恩  魏文博  梅忠武 《吉林大学学报(地球科学版)》2005,35(5):622-625

溶蚀孔、洞是塔河油田奥陶系油气的主要储集场所。为深入了解奥陶系的油气分布,研究了该区奥陶系岩溶洞穴的发育特征,介绍岩溶洞穴在钻井录井、岩心、测井、地震等资料上的识别标志,并识别了本区14口井的岩溶洞穴;恢复了本区海西早期的岩溶古地貌。研究发现：岩溶斜坡靠近岩溶高地和岩溶谷地一侧是岩溶洞穴发育且保存最好的所在地,岩溶洞穴主要分布在“双峰灰岩”顶面下40~80 m、110~130 m、150~190 m、230~260 m的深度范围内,多数井在岩溶洞穴发育段表现出了极好的油气生产能力。  相似文献   

溶洞对路基稳定性影响分析——以常张高速公路K122+200路基为例   总被引：2，自引：0，他引：2  

刘悟辉  刘伟 《中国岩溶》2006,25(4):347-351

利用弹塑性理论和有限差分方法,对常张高速公路下伏溶洞处理前后对路基变形和稳定性影响进行了计算分析和评价。计算结果表明,在汽车动载作用下,常张高速公路K122+ 200路基和溶洞上部土层产生较大的塑性变形, 整个路基处于不稳定状态。进一步分析表明,溶洞的顶板厚度是影响路基稳定性的主导因素,随着顶板厚度的增加,路基地面变形迅速减小。K122+ 200路基下伏溶洞采用回注水泥粘土浆液加固处理后,路基变形和溶洞上部土体的塑性变形明显减小,可见回注水泥粘土浆液加固溶洞效果明显,能满足工程建设的要求。   相似文献   

湖北清江和尚洞石笋的高分辨率碳氧同位素及古气候研究   总被引：1，自引：1，他引：0       下载免费PDF全文

黄俊华  胡超涌 《地球科学》2000,25(5):505-509

通过对湖北清江和尚洞HS - 2号石笋的沉积特征及碳、氧同位素特征分析, 利用U系法定年, 获取了湖北地区19.0~6.9ka的古气候、古环境信息(平均分辨率为17a, 局部分辨率达到7a).得出如下结论: (1) 19.0~16.6ka, C, O同位素偏轻, 气候冷湿; (2) 16.6~11.1ka, C, O同位素偏重, 气候干热; (3) 11.1~10.3ka干热时期中的突然回冷事件对应于新仙女木事件; (4) 10.3~6.9ka气候温和, 雨量较丰, 后期逐渐变冷.反映了历史时期湿冷、干热、温暖交替变化的气候趋势, 得出了千年级和百年级的一些气候变化趋势   相似文献   

腾龙洞造成的洪涝灾害及治理方案的优选   总被引：2，自引：2，他引：0  

钱建龙  杨录军 《中国岩溶》2001,20(4):290-294

湖北省利川市毗邻清江,其下游腾龙洞清江伏流段阻流壅水严重,影响到了城区。本文通过对腾龙洞形态结构特点及其周围地质环境的研究,认为该地下河入口(落水洞)至银河洞尾一段过水断面狭窄,阻流壅水是造成利川市城郊遭受水灾的主要原因。治理时,以隧道加溶洞方案最为经济。   相似文献   

重庆丰都雪玉洞群的洞穴特征和洞穴沉积物   总被引：15，自引：11，他引：4  

朱学稳  张远海  韩道山  文汝平  陈炳清 《中国岩溶》2004,23(2):85-168

重庆市丰都县的雪玉洞群,由水洞子(雪玉洞群主洞)、水鸣洞和羊子洞组成,发育于三叠系下统的嘉陵江灰岩中,均为沿单斜构造地层走向发育的纵向洞穴系统,集中分布在龙河峡谷左岸2km 内高、中、低不同的相对高度,但洞穴发育特征差异甚大。在该洞穴群的次生物理— 化学沉积物( speleo thems )中碳酸盐类(方解石、文石)和硫酸盐类(石膏)并存,而且其形态的多样与完美,类型的稀有而珍贵,质地的纯粹而白净,在国内已发现的洞穴中是不多见的,其中尤以地石盾、塔珊瑚、钙膜晶锥、卷曲石等生成物为代表。   相似文献