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| 1 | 贵州高原沉积物原位宇宙成因核素^(10)Be、^(26)Al和^(21)Ne测年研究显示文摘地貌演化受到区域构造抬升、气候变化和河流动力学共同调节.然而,如何通过地表剥蚀和河流下切作用来区分这些机制仍存在争议.本文对贵州高原地区洞穴沉积物、现代河流沉积物和基岩中石英颗粒的原位宇宙成因核素^(10)Be、^(26)Al和^(21)Ne含量进行分析,探讨了^(21)Ne在地质年代学中的适用性,并讨论了该地区第四纪地貌演化历史.通过^(26)Al-^(10)Be和^(21)Ne-^(10)Be核素对的对比分析,我们发现石英样品中由U和Th衰变产生的核反应成因^(21)Ne含量不可忽视,同时也有可能存在继承性宇宙成因^(21)Ne.在前人的研究基础上,我们总结了宇宙成因核素^(21)Ne精确定年须注意的几个方面:(1)评估样品中核反应成因^(21)Ne的贡献;(2)避免采集有复杂埋藏历史的样品以排除继承性^(21)Ne的影响;(3)对第四纪样品^(10)Be-^(26)Al-^(21)Ne三核素联用.基于^(26)Al-^(10)Be核素对计算出的样品埋藏年代和流域在埋藏前的剥蚀速率,我们确定了贵州高原地区不同时间尺度地表剥蚀速率和河流下切速率的变化.不同时间尺度的^(26)Al-^(10)Be流域剥蚀速率、^(36)Cl剥蚀速率和现代河流剥蚀速率的一致性,表明贵州高原景观尺度的地表剥蚀速率可能在第四纪以来已经达到稳定状态.该地区河流下切速率略高于局部地表剥蚀速率,表明区域构造抬升导致的河流动力学可能尚未达到稳定状态. | 杨业 刘彧 马严 徐胜 刘丛强 王世杰 Finlay M.STUART Derek FABEL | 2021 | 中国科学:地球科学2021，51，8： | 1 |
| 2 | The performance of the Noblesse multi-collector noble gas mass spectrometer for ^(40)Ar/^(39)Ar geochronology显示文摘Noblesse multi-collector noble gas mass spectrometer is specially designed for multi-collection of Ar isotopes with different beam sizes, especially for small ion beams, precisely, and hence is perfectly suitable for ^(40)Ar/^(39)Ar geochronology. We have analyzed widely used sanidine, muscovite, and biotite standards with recommended ages of ~ 1.2–133 Ma, with the aim to assess the reliability of Noblesse for ^(40)Ar/^(39)Ar dating. An ESI MIR1030W CO_2 laser was used for total fusion or incremental heating samples. Extracted gases were routinely purified by four SAES NP10 getters(one at * 400 °C and others at room temperature). A GP50 getter and a metal cold finger cooled by liquid N(-196 °C) were also attached for additional purification if necessary. The Ar isotopes were then measured by Noblesse using Faraday or multiplier according to the signal intensities. Over a period of 1.5 months 337 air calibrations produced a weighted mean ^(40)Ar/^(36)Ar of 296.50 ± 0.08(2σ, MSWD = 4.77). Fish Canyon sanidine is used to calculate J-values, which show good linear relationship with position in irradiation. The age of four mineral standards(Alder Creek sanidine,Brione muscovite, Yabachi sanidine, and Fangshan biotite)are within error of the accepted ages. Five Alder Creek sanidine aliquots yielded an age range of 1.174–1.181 ± 0.013 Ma(2σ) which broadly overlaps the established age of the standard and the uncertainty approaches those of the foremost Ar/Ar laboratories in the world. The weighted mean ages of four Brione muscovite aliquots (18.75 ± 0.16 Ma, 2σ), five Yabachi sanidine aliquots (29.50 ± 0.19 Ma, 2σ), and three Fangshan biotite aliquots (133.0 ± 0.76 Ma, 2σ) are consistent with the recommended values of these standards, and the uncertainties are typical of modern Ar/Ar laboratories worldwide. | Defeng He Finlay M.Stuart Dan N.Barfod Fang Xiao Hong Zhong | 2018 | Acta Geochimica2018，37，5： | 1 |
| 3 | In situ cosmogenic ^(10)Be, ^(26)Al, and ^(21)Ne dating in sediments from the Guizhou Plateau, southwest China显示文摘Landscape evolution is modulated by the regional tectonic uplift,climate change,and river dynamics.However,how to distinguish these mechanisms through the research of surface exhumation and fluvial incision remains controversial.In this study,cosmogenic ^(10)Be,^(26)Al,and ^(21)Ne concentrations in quartz from cave deposits,modern river sediments,and bedrocks were measured to constrain the applicability of cosmogenic ^(21)Ne and discuss Quaternary landscape evolution history in the Guizhou Plateau,southeast China.Using the ^(26)Al-^(10)Be and ^(21)Ne-^(10)Be pairs to distinguish the cosmogenic ^(21)Ne concentration from the excess ^(21)Ne,we found that the nucleogenic ^(21)Ne produced by the U and Th decay in quartz is significant in the samples although there is the possibility of inherited cosmogenic ^(21)Ne.Combining with previous studies,we suggest that the precise approach for applying the cosmogenic ^(21)Ne could be reached by(1)estimating the contribution from nucleogenic ^(21)Ne,(2)avoiding samples with complex burial histories to exclude inherited cosmogenic ^(21)Ne,and(3)combining the ^(10)Be-^(26)Al-^(21)Ne nuclides method for the Quaternary samples.In addition,both pre-burial basin denudation rates and burial ages derived from the ^(26)Al-^(10)Be pair were used to determine the different timescale surface denudation rate and fluvial incision rate in relation to previous work.The consistency of the different timescales pre-burial basin denudation rate,^(36)Cl surface denudation rate,and modern basin denudation rate indicates that the landscape-scale surface denudation has been likely stabilized since the Quaternary in the Guizhou Plateau area.The slightly higher river incision rates than the local surface denudation rate show that the river dynamics may not have reached a steady-state due to the regional tectonic uplift in the Guizhou Plateau. | Ye YANG Yu LIU Yan MA Sheng XU Cong-Qiang LIU Shi-Jie WANG Finlay M.STUART Derek FABEL | 2021 | Science China Earth Sciences2021，64，8： | 1 |
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