Assessment of a lumped coupled flow‐isotope model in data scarce Boreal catchments          下载免费PDF全文

A. Smith  C. Welch  T. Stadnyk 《水文研究》2016,30(21):3871-3884

Quantifying streamflow sources within remote, data scarce, Boreal catchments remains a significant challenge because of limited accessibility and complex, flat topography. The coupled use of hydrometric and isotopic data has previously been shown to facilitate quantification of streamflow sources, but application has generally been limited to small basins and short time scales. A lumped flow‐isotope model was used to estimate contributing streamflow sources (soil, ground, and wetland water) over a four‐year period in two large nested headwater catchments (Sapochi and Odei Rivers) in northern Manitoba, Canada. On average, the primary streamflow source was estimated as soil water (60%) in the Sapochi River, and groundwater (54%) in the Odei River. A strong seasonal influence was observed: soil water was the primary streamflow source in summer, changing to groundwater and wetlands during the winter. Interannual variability in streamflow sources was strongly linked to the presence or absence of late summer rainfall. The greatest uncertainties in source quantification were identified during the spring freshets and high precipitation events, and hence, simulations may be improved through explicit representation of the soil freeze/thaw process and data collection during this period. Assessment of primary streamflow components and qualitative uncertainty estimation using coupled isotope‐flow modelling is an effective method for first‐order identification of streamflow sources in data sparse remote headwaters. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Last Deglaciation Climatic Fluctuation Record by the Palaeo-Daocheng Ice Cap,Southeastern Qinghai-Tibetan Plateau     

ZHANG Zhigang  XU Xiaobin  WANG Jian  ZHAO Zhijun  BAI Shibiao  and CHANG ZhiYang 《《地质学报》英文版》2014,88(6):1863-1874

The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau(QTP) is often a target study area for understanding hemispheric, or even global environment changes. The glacial landforms on the QTP provide a unique perspective for its climate change. In order to investigate the onset of the last deglaciation at the QTP and its regional correlation, the terrestrial cosmogenic nuclides(TCN) 10 Be and 26 Al surface exposure dating was chosen to date the roche moutonnée, the polished surface and the moraine debris located at the palaeo-Daocheng Ice Cap(pDIC), southeastern QTP. Our results show that the onset of the last deglaciation is at about 19 ka, followed by another warming event occurring around 15 ka in the p-DIC area. These timings agree well with other records, e.g. equivalent with a rapid sea level rise at 19 ka and the onset of B?lling warming event at about 15 ka. Thus, our new data can provide good reveal constraint on the climate evolution at the QTP.  相似文献   

下扬子中部志留系盖层封闭性动态演化评价          下载免费PDF全文

袁玉松  李双建熊 航 《地质科学》2018,(4):1419-1430

下扬子中部地区海相层系在印支-燕山期经历了强烈的构造改造,保存条件成为油气成藏的关键控制因素之一。志留系泥页岩盖层是下古生界的区域性盖层,对原生油气藏的保存具有决定性的作用。基于志留系样品的实测数据对志留系盖层现今的封闭性做出了评价。采用孔隙度-排替压力史法、渗透率-排替压力史法及超固结比（OCR）参数重建了志留系盖层在地质历史时期封闭性的动态演化过程。结果显示：下扬子中部志留系盖层具有低孔、低渗、高排替压力特征,总体上现今物性封闭能力较强。在埋藏阶段排替压力达到了封闭高压和超高压气藏的能力,但在早白垩世期间,句容地区志留系盖层排替压力显著降低且OCR 值超过脆性破裂门限值,下古生界保存条件破坏较为严重,在常州和泰兴地区OCR 值小于脆性破裂门限值,破坏程度相对较弱。  相似文献   

First period analyses of five neglected Algol-type eclipsing binaries: TT And, V342 Aql, RW Cap, BZ Cas and TW Lac     

A. Erdem  F. Soydugan  S.S. Doru  B. zkarde  D. Doru  M. Tüysüz  O. Demircan 《New Astronomy》2007,12(8):613-621

We present the first study of the orbital period variations of five neglected Algol-type eclipsing binaries TT And, V342 Aql, RW Cap, BZ Cas and TW Lac, using their O–C diagrams gathered from all available times of eclipse minima. These O–C diagrams indicate that short term periodic variations superimposed on secular period increases as expected in mass transferring Algols. However, due to short time coverage of the data, the secular period increase is not clear in the case of BZ Cas and V342 Aql. The secular period increase is interpreted in terms of the combined effect of mass transfer between the components of the system and the mass loss by a stellar wind from the system. The mass transfer rates from the less massive secondary components to the more massive primaries for non-conservative cases would be about 10⁻⁷M/yr and 10⁻⁸M/yr for RW Cap and V342 Aql, respectively, and 10⁻⁹M/yr for TT And and TW Lac. Therefore, the Algol systems RW Cap and V342 Aql have the largest mass transfer rate, which could be in Case AB type, while those of the Algol systems TT And and TW Lac display the slow mass transfer rate and they could be in Case B type. The sinusoidal forms of the orbital period variations of all five Algol systems can be due to either by the light-time effects due to unseen components in these systems, or by the cyclic magnetic activity effects of the cool secondary components. The possible third bodies in all five Algol binaries would have masses larger than one solar mass. If these hypothetical large massive third bodies were normal stars, they should be detectable. Therefore, new photometric and spectroscopic observations of these systems and careful analyses of those data are required. Otherwise, the cyclic magnetic activity effects of the secondary components could be the basis of a working hypothesis in explaining the cyclic period variations of these systems.  相似文献   

稻城冰帽冰碛物光释光测年研究中遇到的问题及探讨     

张志刚  王建  赖忠平  徐孝彬  白世彪  张茂恒 《地质学报》2012,86(4):602-610

冰川事件是气候波动最直接的地质证据,利用冰川作用过程中形成的冰碛物的年代数据建立冰川事件的时间顺序,是反演冰川演化历史以及区域古气候和古环境的有效途径。然而,由于冰川沉积环境的复杂性,很大程度限制了冰川年代数据的获取。近年来,随着光释光测年技术的不断完善,其应用范围已经扩展到冰川沉积物的年代测定。本文利用光释光(OSL)测年技术对青藏高原东南部稻城冰帽库照日地区系列冰碛垄进行年代测定,试图建立库照日地区冰川事件的年代序列。然而,光释光(OSL)年代结果与先前发表的ESR和宇生核素10Be暴露年代数据不一致,且个别数据与地貌新老关系不符。通过对比分析显示:冰碛物样品埋藏前释光信号的部分晒退以及样品提取的石英不纯,可能导致冰碛物光释光测年的较大误差和不准确性,应该引起足够的注意。  相似文献   

The structural evolution of sheath folds: A case study from Cap de Creus     

G.I. Alsop  J. Carreras 《Journal of Structural Geology》2007,29(12):1915-1930

It has long been recognised that within zones of intense non-coaxial deformation, fold hinges may rotate progressively towards the transport direction ultimately resulting in highly curvilinear sheath folds. However, there is a surprising lack of detailed and systematic field analysis of such “evolving” sheath folds. This case study therefore focuses on the sequential development of cm-scale curvilinear folds in the greenschist-facies El Llimac shear zone, Cap de Creus, Spain. This simple shear-dominated dextral shear zone displays superb three dimensional exposures of sheath folds defined by mylonitic quartz bands within phyllonite. Increasing amounts of fold hinge curvature (δ) are marked by hinge segments rotating into sub-parallelism with the mineral lineation (Lm), whilst the acute angle between the axial-planar hinge girdle and foliation (ω) also displays a sequential reduction. Although Lm bisects the noses of sheath folds, it is also clearly folded and wrapped-around the sheath hinges. Lm typically preserves a larger angle (θ) with the fold hinge on the lower limb (L) compared to the upper (U) limb (θL > θU), suggesting that Lm failed to achieve a steady orientation on the lower limb. Adjacent sheath fold hinges forming fold pairs may display the same sense of hinge arcing to define synthetic curvature, or alternatively opposing directions of antithetic curvature. Such patterns reflect original buckle fold geometries coupled with the direction of shearing. The ratio of long/short fold limbs decreases with increasing hinge curvilinearity, indicating sheath folds developed via stretching of the short limb, rather than migrating or rolling hinge models. This study unequivocally demonstrates that both hinges of fold pairs become curvilinear with sheaths closing in the transport direction recording greater hinge-line curvilinearity compared to adjacent return hinges. This may provide a useful guide to bulk shear sense.  相似文献   

太白山第四纪冰碛物特征与冰期   总被引：3，自引：0，他引：3  

马秋华  何元庆 《冰川冻土》1988,(1)

在晚更新世早期(Q_3~1)和晚期(Q_8~3),太白山主峰八仙台先后发生过两次冰川作用,即三爷海冰期和太白冰期。其中太白冰期又可划分为早太白和晚太白两个副冰期。经人工剖面证实的三道不同时期的侧碛垄分别与上述冰期相对应。各种冰蚀地貌都受到该区构造的控制和影响。  相似文献   

南极乔治王岛柯林斯冰帽小冰穹物质平衡特征的初步分析          下载免费PDF全文

温家洪  谢自楚  韩建康  康建成  朱国才  井晓平  高新生 《极地研究》1994,6(1):50-60

柯林斯冰帽小冰穹属于冷季补给型冰川。该冰穹高差不大，但末端比顶部的消融期长两个月；暖季消融随高度上升迅速递减。冷季积累随高度的变化显著。ＳＤＳ断面１９９１／１９９２年度物质平衡差额为１６３ｍｍ，零平衡线海拔高度为１４０ｍ，比动力平衡线低２０ｍ。其物质平衡特征表现为物质平衡梯度较大，而物质平衡水平较低，稳定性系数较小，反映了亚极地海洋性气候下冰川物质平衡的特有性质  相似文献   

柯林斯冰帽雷达测厚和冰下地形研究          下载免费PDF全文

朱国才  井晓平  韩建康  高新生  康建成  温家洪 《极地研究》1994,6(2):43-48

使用一台３００ＭＨｚ高频脉冲雷达，对柯林斯冰帽１５０个测点进行冰厚探测，描绘出１５ｋｍ冰床雷达回波剖面。该冰帽小冰穹最大冰厚１２５－１３１ｍ，位于其顶部，小冰穹顶至主冰穹顶脊线上的平均厚度约１０９ｍ；主冰穹顶部附近５０－８５ｍ深度处有一被钻探证实为含水界面的雷达回波；小冰穹近乎南北向的冰下地形与该岛北方台地地形相似。  相似文献   

A locally calibrated,late glacial 10Be production rate from a low-latitude,high-altitude site in the Peruvian Andes     

《Quaternary Geochronology》2015

Well-dated records of tropical glacier fluctuations are essential for developing hypotheses and testing proposed mechanisms for past climate changes. Since organic material for radiocarbon dating is typically scarce in low-latitude, high-altitude environments, surface exposure-age dating, based on the measurement of in situ produced cosmogenic nuclides, provides much of the chronologic information on tropical glacier moraines. Here, we present a locally calibrated ¹⁰Be production rate for a low-latitude, high-altitude site near Quelccaya Ice Cap (∼13.95°S, 70.89°W, 4857 m asl) in the southeastern Peruvian Andes. Using an independent age (12.35 +0.2, −0.02 ka) of the late glacial Huancané IIa moraines based on thirty-four bracketing radiocarbon ages and twelve ¹⁰Be concentrations of boulders on the moraines, we determine a local production rate of 43.28 ± 2.69 atoms gram⁻¹ year⁻¹ (at g⁻¹ yr⁻¹). Reference ¹⁰Be production rates (i.e., production rates by neutron spallation appropriate for sea-level, high-latitude sites) range from 3.97 ± 0.09 to 3.78 ± 0.09 at g⁻¹ yr⁻¹, determined using scaling after Lal (1991) and Stone (2000) and depending on our assumed boulder surface erosion rate. Since our boulder surface erosion rate estimate is a minimum value, these reference production rates are also minimum values. A secondary control site on the Huancané IIIb moraines suggests that the ¹⁰Be production rates are at least as low as, or possibly lower than, those derived from the Huancané IIa moraines. These sea-level, high-latitude production rates are at least 11–15% lower than values derived using the traditional global calibration dataset, and they are also lower than those derived from the late glacial Breque moraine in the Cordillera Blanca of Peru. However, our sea-level, high-latitude production rates agree well with recently published, locally calibrated production rates from the Arctic, New Zealand, and Patagonia. The production rates presented here should be used to calculate ¹⁰Be exposure ages in low-latitude, high-altitude locations, particularly in the tropical Andes, and should improve the ability to compare the results of studies using ¹⁰Be exposure-age dating with other chronological data.  相似文献