地表侵蚀速率是衡量地貌演化的一个重要因子。本研究利用原地宇宙成因核素^(10)Be和26Al对合黎山西南部地表岩石侵蚀速率进行了首次测定。结果显示:约30 ka以来,合黎山西南部的地表岩石侵蚀速率约为24 mm?ka^(-1)。这一结果与已见报道...地表侵蚀速率是衡量地貌演化的一个重要因子。本研究利用原地宇宙成因核素^(10)Be和26Al对合黎山西南部地表岩石侵蚀速率进行了首次测定。结果显示:约30 ka以来,合黎山西南部的地表岩石侵蚀速率约为24 mm?ka^(-1)。这一结果与已见报道的其他基岩侵蚀速率值一致。这一结果与Small et al获得的非干旱地区的基岩侵蚀速率也基本一致,但是显著高于干旱的南极地区和半干旱的澳大利亚。^(10)Be和26Al获得的侵蚀速率的良好一致性表明本研究中所用侵蚀模式的有效性。所得的侵蚀速率小于Palumbo et al测定的合黎山平均流域侵蚀速率(99 mm?ka-1),原因解释尚待更多地点和样品的研究。展开更多
大洋富钴结壳的生长速率及其定年测量在研究古大洋环流、古环境及古气候变迁等方面具有重要意义,而宇宙成因核素10Be、26Al因为其测量时间尺度长、精度高,而被视为富钴结壳年代测定的最有效手段之一。本文在前人研究的基础上,对富钴结壳...大洋富钴结壳的生长速率及其定年测量在研究古大洋环流、古环境及古气候变迁等方面具有重要意义,而宇宙成因核素10Be、26Al因为其测量时间尺度长、精度高,而被视为富钴结壳年代测定的最有效手段之一。本文在前人研究的基础上,对富钴结壳中10Be、26Al定年新方法进行了探究。对采自太平洋的2块富钴结壳样品进行连续的淋滤实验,并对其中1个样品CXD08-1自生相中的10Be和26Al进行分离、纯化及AMS(Accelerator Mass Spectrometry)测量分析。利用10Be浓度和10Be/9Be值计算得到CXD08-1在5~10 mm间的平均生长速率分别为(10.23-0.47^+0.52)mm/Ma和(14.25-0.89^+1.02)mm/Ma。而26Al因为大量衰变及27Al载体的加入而未得到可靠的分析结果,因此,26Al定年须进一步探索。展开更多
In situ terrestrial cosmogenic nuclide （TCN） exposure dating using 10Be is one of the most successful techniques used to determine the ages of Quaternary deposits and yields data that enable the reconstruction of th...In situ terrestrial cosmogenic nuclide （TCN） exposure dating using 10Be is one of the most successful techniques used to determine the ages of Quaternary deposits and yields data that enable the reconstruction of the Quaternary glacial history of the Tibetan Plateau and the surrounding mountain ranges. Statistical analysis of TCN 10Be exposure ages, helps to reconstruct the history of glacial fluctuations and past climate changes on the Tibetan Plateau, differences in the timing of glacier advances among different regions. However, different versions of the Cosmic-Ray-prOduced NUclide Systematics on Earth （CRONUS-Earth） online calculator, which calculates and corrects the TCN ages of Quaternary glacial landforms, yield different results. For convenience in establishing contrasts among regions, in this paper, we recalculate 1848 10Be exposure ages from the Tibetan Plateau that were published from 1999 to 2017 using version 2.3 of the CRONUS-Earth calculator. We also compare the results obtained for 1594 10Be exposure ages using different versions （2.2, 2.3 and 3.0） of the CRONUS- Earth calculator. The results are as follows. （1） Approximately 97% of the exposure ages are less than 200 ka. A probability density curve of the exposure ages suggests that greater numbers of oscillations emerge during the Holocene, and the peaks correspond to the Little Ice Age, the 8.2 ka and 9.3 ka cold events; the main peak covers the period between 12 and 18 ka. （2） In most areas, the newer versions of the calculator produce older 10Be exposure ages. When different versions of the CRONUS-Earth calculator are used, approximately 29% of the 10Be exposure ages display maximum differences greater than 10 ka, and the maximum age difference for a single sample is 181.1 ka.展开更多
The concentration of cosmogenic loBe in riverine sediments has been widely used as a proxy for catchment-wide denudation rate （CWDR）. One of the key assumptions of this approach is that sediments originating from su...The concentration of cosmogenic loBe in riverine sediments has been widely used as a proxy for catchment-wide denudation rate （CWDR）. One of the key assumptions of this approach is that sediments originating from sub-basins with different erosional histories are well mixed. A tragic debris flow occurred in the Seti River watershed, central Nepal, on May 5, 2012. This catastrophic debris flow was triggered by slope failure on the peak of Annapurna IV and resulted in many casualties in the lower Seti Khola. However, it provided an opportunity to test the assumption of equal mixing of sediments in an understudied rapidly eroding watershed. This study documents the CWDR of ^10Be to evaluate the extent of the influence of episodic erosional processes such as debris flow on the spatio-temporal redistribution of loBe concentrations. Our data show that the debris flow caused little change in CWDR across the debris flow event. In addition to isotopic measurement, we calculated denudation rates by using the modeled concentrations in pre- and post-landslide sediments based on the local ^10Be production rate. The modeled result showed little change across the event, indicating that the debris flow in May 2012 played a minor role in sediment evacuation, despite the rapid erosion in the catchment. Our study concludes that although the 2012 event caused many casualties and severe damage, it was a low-magnitude, high frequency event.展开更多
Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial ad...Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial advances of the Thajwas Glacier(TG) in the Great Himalayan Range of the Kashmir Himalaya. FromBe exposure dating of ten moraine boulders, four glacial stages with ages ~20.77 ±2.28 ka, ~11.46 ± 1.69 ka, ~9.12 ± 1.39 ka and ~4.19 ± 0.78 ka, were identified. The reconstructed cosmogenic radionuclide ages confirmed the global Last Glacial Maximum(g LGM), Younger Dryas, Early Holocene, and Neoglaciation episodes. As per area and volume change analyses, the TG has lost 51.1 km~2 of its area and a volume of 2.64 km~3 during the last 20.77 ± 2.28 ka. Overall, the results suggested that the TG has lost 64% of area and 73% of volume from the Last glacial maximum to Neoglaciation and about 85.74% and 87.67% of area and volume, respectively, from Neoglaciation to the present day. The equilibrium line altitude of the TG fluctuated from 4238 m a.s.l present to3365 m a.s.l during the g LGM(20.77 ± 2.28 ka). The significant cooling induced by a drop in mean ambient temperature resulted in a positive mass balance of the TG during the g LGM. Subsequently the melting accelerated due to the continuing rise of the global ambient temperature. Paleo-glacial history reconstruction of the Kashmir Himalaya, with its specific geomorphic and climatic setting, would help close the information gap about the chronology of past regional glacial episodes.展开更多
In situ terrestrial cosmogenic nuclide(TCN)has been widely applied to date the ages of Quaternary glacial deposits in Antarctica and plays an important role in reconstructing the glacial evolution and climate change.I...In situ terrestrial cosmogenic nuclide(TCN)has been widely applied to date the ages of Quaternary glacial deposits in Antarctica and plays an important role in reconstructing the glacial evolution and climate change.It helps to under‐stand the Antarctic ice sheet's evolution process in Quaternary and shed light on the application of Cosmogenic Nu‐clide exposure dating technique in Glacial Geomorphology.In this paper,we retrieved 49510Be age samples in Ant‐arctica from literature published between 2004 and 2020 and recalculated the TCN ages using version 3.0 online cal‐culator of Cosmic-Ray Produced Nuclide Systematics on Earth(CRONUS-Earth).Several conclusions can be drawn from the results:(1)75%of the exposure ages are younger than 400 ka,and 91%younger than 1,100 ka.Northern Antarctic Peninsula exposure result is visibly younger than the main glaciers in East Antarctica due to climate change and geological evaluation since the LGM(Last Glacial Maximum).(2)TCN ages are relevant to the samples'relative positions in the Antarctic continent,but a relationship between their ages and elevations is yet to be determined based on the collected data.展开更多
The timing and mechanisms of fluvial terrace formation along the Yangtze River in the Yichang region provide critical insights into the interplay between tectonics,climate,and river evolution.In this study,we present ...The timing and mechanisms of fluvial terrace formation along the Yangtze River in the Yichang region provide critical insights into the interplay between tectonics,climate,and river evolution.In this study,we present new cosmogenic nuclide isochron burial ages for the fifth(T5)and fourth(T4)terraces,yielding ages of 0.49±0.05 Ma and 0.35±0.04 Ma,respectively.By integrating our data with existing 14C and ESR ages for lower terraces,we reconstruct a detailed incision history,showing~85 m of river downcutting since the Middle Pleistocene.Incision rates varied over time,with a notable acceleration after 0.1 Ma coinciding with the Gonghe movement of the Tibetan Plateau,highlighting the role of tectonic uplift in driving fluvial incision.The formation of the fifth terrace is associated with the Kunlun–Huanghe uplift,while the development of the fourth terrace corresponds to the phase of regional uplift in the Qinling Mountains.Sedimentological evidence further indicates that terrace formation was influenced by both climatic and tectonic controls:while T4 aggraded during a glacial period,T5 formed during the interglacial MIS 13 under strong monsoonal conditions—demonstrating that major aggradation can occur during warm phases.However,sustained incision required tectonic forcing,as climatic transitions alone were insufficient to drive deep bedrock erosion.Our results also constrain the longdebated integration of the Three Gorges.The 0.49 Ma age for T5 provides a robust minimum age for the hydrological connection between the Sichuan and Jianghan Basins.This timing,combined with the earlier formation of the"First Bend of the Yangtze"(Eocene–Miocene),contradicts the classical east-towest headward erosion model.Instead,geomorphic analysis of the gorges—showing diachronous valley development from east to west—supports a progressive,bottom-to-top integration,initiated in the Xiling Gorge and culminating in the incision of the Qutang Gorge.This sequence aligns with knickpoint migration driven by base-level fall and regional tectonic uplift.We conclude that the evolution of the Yangtze River through the Three Gorges is the result of a complex interplay between climate,tectonics,and base-level dynamics,with terraces serving as key archives of landscape response to these forces.展开更多
文摘地表侵蚀速率是衡量地貌演化的一个重要因子。本研究利用原地宇宙成因核素^(10)Be和26Al对合黎山西南部地表岩石侵蚀速率进行了首次测定。结果显示:约30 ka以来,合黎山西南部的地表岩石侵蚀速率约为24 mm?ka^(-1)。这一结果与已见报道的其他基岩侵蚀速率值一致。这一结果与Small et al获得的非干旱地区的基岩侵蚀速率也基本一致,但是显著高于干旱的南极地区和半干旱的澳大利亚。^(10)Be和26Al获得的侵蚀速率的良好一致性表明本研究中所用侵蚀模式的有效性。所得的侵蚀速率小于Palumbo et al测定的合黎山平均流域侵蚀速率(99 mm?ka-1),原因解释尚待更多地点和样品的研究。
文摘大洋富钴结壳的生长速率及其定年测量在研究古大洋环流、古环境及古气候变迁等方面具有重要意义,而宇宙成因核素10Be、26Al因为其测量时间尺度长、精度高,而被视为富钴结壳年代测定的最有效手段之一。本文在前人研究的基础上,对富钴结壳中10Be、26Al定年新方法进行了探究。对采自太平洋的2块富钴结壳样品进行连续的淋滤实验,并对其中1个样品CXD08-1自生相中的10Be和26Al进行分离、纯化及AMS(Accelerator Mass Spectrometry)测量分析。利用10Be浓度和10Be/9Be值计算得到CXD08-1在5~10 mm间的平均生长速率分别为(10.23-0.47^+0.52)mm/Ma和(14.25-0.89^+1.02)mm/Ma。而26Al因为大量衰变及27Al载体的加入而未得到可靠的分析结果,因此,26Al定年须进一步探索。
基金supported by the National Natural Science Foundation of China(Grant No.41503054)the China Postdoctoral Science Foundation(2015M582728)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)(Grant No.164320H116)the Yulong Mountain tourism development and management committee special project
文摘In situ terrestrial cosmogenic nuclide （TCN） exposure dating using 10Be is one of the most successful techniques used to determine the ages of Quaternary deposits and yields data that enable the reconstruction of the Quaternary glacial history of the Tibetan Plateau and the surrounding mountain ranges. Statistical analysis of TCN 10Be exposure ages, helps to reconstruct the history of glacial fluctuations and past climate changes on the Tibetan Plateau, differences in the timing of glacier advances among different regions. However, different versions of the Cosmic-Ray-prOduced NUclide Systematics on Earth （CRONUS-Earth） online calculator, which calculates and corrects the TCN ages of Quaternary glacial landforms, yield different results. For convenience in establishing contrasts among regions, in this paper, we recalculate 1848 10Be exposure ages from the Tibetan Plateau that were published from 1999 to 2017 using version 2.3 of the CRONUS-Earth calculator. We also compare the results obtained for 1594 10Be exposure ages using different versions （2.2, 2.3 and 3.0） of the CRONUS- Earth calculator. The results are as follows. （1） Approximately 97% of the exposure ages are less than 200 ka. A probability density curve of the exposure ages suggests that greater numbers of oscillations emerge during the Holocene, and the peaks correspond to the Little Ice Age, the 8.2 ka and 9.3 ka cold events; the main peak covers the period between 12 and 18 ka. （2） In most areas, the newer versions of the calculator produce older 10Be exposure ages. When different versions of the CRONUS-Earth calculator are used, approximately 29% of the 10Be exposure ages display maximum differences greater than 10 ka, and the maximum age difference for a single sample is 181.1 ka.
基金supported by the College of Education,Korea University Grant in 2016
文摘The concentration of cosmogenic loBe in riverine sediments has been widely used as a proxy for catchment-wide denudation rate （CWDR）. One of the key assumptions of this approach is that sediments originating from sub-basins with different erosional histories are well mixed. A tragic debris flow occurred in the Seti River watershed, central Nepal, on May 5, 2012. This catastrophic debris flow was triggered by slope failure on the peak of Annapurna IV and resulted in many casualties in the lower Seti Khola. However, it provided an opportunity to test the assumption of equal mixing of sediments in an understudied rapidly eroding watershed. This study documents the CWDR of ^10Be to evaluate the extent of the influence of episodic erosional processes such as debris flow on the spatio-temporal redistribution of loBe concentrations. Our data show that the debris flow caused little change in CWDR across the debris flow event. In addition to isotopic measurement, we calculated denudation rates by using the modeled concentrations in pre- and post-landslide sediments based on the local ^10Be production rate. The modeled result showed little change across the event, indicating that the debris flow in May 2012 played a minor role in sediment evacuation, despite the rapid erosion in the catchment. Our study concludes that although the 2012 event caused many casualties and severe damage, it was a low-magnitude, high frequency event.
基金conducted with the help of grants from the Department of Science and Technology (DST), Government of India under the sponsored research project titled “Centre of Excellence for Glacial Studies in Western Himalaya”granting fellowship to Omar Jaan Paul under the project No. UFR-59313。
文摘Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial advances of the Thajwas Glacier(TG) in the Great Himalayan Range of the Kashmir Himalaya. FromBe exposure dating of ten moraine boulders, four glacial stages with ages ~20.77 ±2.28 ka, ~11.46 ± 1.69 ka, ~9.12 ± 1.39 ka and ~4.19 ± 0.78 ka, were identified. The reconstructed cosmogenic radionuclide ages confirmed the global Last Glacial Maximum(g LGM), Younger Dryas, Early Holocene, and Neoglaciation episodes. As per area and volume change analyses, the TG has lost 51.1 km~2 of its area and a volume of 2.64 km~3 during the last 20.77 ± 2.28 ka. Overall, the results suggested that the TG has lost 64% of area and 73% of volume from the Last glacial maximum to Neoglaciation and about 85.74% and 87.67% of area and volume, respectively, from Neoglaciation to the present day. The equilibrium line altitude of the TG fluctuated from 4238 m a.s.l present to3365 m a.s.l during the g LGM(20.77 ± 2.28 ka). The significant cooling induced by a drop in mean ambient temperature resulted in a positive mass balance of the TG during the g LGM. Subsequently the melting accelerated due to the continuing rise of the global ambient temperature. Paleo-glacial history reconstruction of the Kashmir Himalaya, with its specific geomorphic and climatic setting, would help close the information gap about the chronology of past regional glacial episodes.
基金the National Natural Science Foundation of China(No.41971009 and No.41503054)the China Postdoctoral Science Foundation(No.2015M582728)the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.64320H116).
文摘In situ terrestrial cosmogenic nuclide(TCN)has been widely applied to date the ages of Quaternary glacial deposits in Antarctica and plays an important role in reconstructing the glacial evolution and climate change.It helps to under‐stand the Antarctic ice sheet's evolution process in Quaternary and shed light on the application of Cosmogenic Nu‐clide exposure dating technique in Glacial Geomorphology.In this paper,we retrieved 49510Be age samples in Ant‐arctica from literature published between 2004 and 2020 and recalculated the TCN ages using version 3.0 online cal‐culator of Cosmic-Ray Produced Nuclide Systematics on Earth(CRONUS-Earth).Several conclusions can be drawn from the results:(1)75%of the exposure ages are younger than 400 ka,and 91%younger than 1,100 ka.Northern Antarctic Peninsula exposure result is visibly younger than the main glaciers in East Antarctica due to climate change and geological evaluation since the LGM(Last Glacial Maximum).(2)TCN ages are relevant to the samples'relative positions in the Antarctic continent,but a relationship between their ages and elevations is yet to be determined based on the collected data.
基金supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea(NRF2023S1A5A2A01077716)。
文摘The timing and mechanisms of fluvial terrace formation along the Yangtze River in the Yichang region provide critical insights into the interplay between tectonics,climate,and river evolution.In this study,we present new cosmogenic nuclide isochron burial ages for the fifth(T5)and fourth(T4)terraces,yielding ages of 0.49±0.05 Ma and 0.35±0.04 Ma,respectively.By integrating our data with existing 14C and ESR ages for lower terraces,we reconstruct a detailed incision history,showing~85 m of river downcutting since the Middle Pleistocene.Incision rates varied over time,with a notable acceleration after 0.1 Ma coinciding with the Gonghe movement of the Tibetan Plateau,highlighting the role of tectonic uplift in driving fluvial incision.The formation of the fifth terrace is associated with the Kunlun–Huanghe uplift,while the development of the fourth terrace corresponds to the phase of regional uplift in the Qinling Mountains.Sedimentological evidence further indicates that terrace formation was influenced by both climatic and tectonic controls:while T4 aggraded during a glacial period,T5 formed during the interglacial MIS 13 under strong monsoonal conditions—demonstrating that major aggradation can occur during warm phases.However,sustained incision required tectonic forcing,as climatic transitions alone were insufficient to drive deep bedrock erosion.Our results also constrain the longdebated integration of the Three Gorges.The 0.49 Ma age for T5 provides a robust minimum age for the hydrological connection between the Sichuan and Jianghan Basins.This timing,combined with the earlier formation of the"First Bend of the Yangtze"(Eocene–Miocene),contradicts the classical east-towest headward erosion model.Instead,geomorphic analysis of the gorges—showing diachronous valley development from east to west—supports a progressive,bottom-to-top integration,initiated in the Xiling Gorge and culminating in the incision of the Qutang Gorge.This sequence aligns with knickpoint migration driven by base-level fall and regional tectonic uplift.We conclude that the evolution of the Yangtze River through the Three Gorges is the result of a complex interplay between climate,tectonics,and base-level dynamics,with terraces serving as key archives of landscape response to these forces.
