| 摘要: |
| 通过建立他念他翁山流域仁措湖地区的花岗岩风化晕生长模型与侵蚀模型，并利用此模型定量了仁措湖地区花岗岩暴露年代。研究结果显示：该地区花岗岩风化晕平均生长速率为4.88 mm∙ (10 ka) −1；平均侵蚀速率为2.15 mm∙ka−1。通过此模型对仁措湖地区的年代进行计算，得出该地区花岗岩风化时间约为(236±88)— (19834±1560) a。结合原地生成宇宙成因核素（terrestrial in situ cosmogenic nuclide，TCN）测年原理，推算出青藏高原花岗岩冰川沉积物至少侵蚀速率分别为：青藏高原东北部为(2.61±0.05) mm∙ka−1、青藏高原东南部为(3.43±0.70) mm∙ka−1、青藏高原中部为(3.42±0.34) mm∙ka−1、喜马拉雅中部为(3.71±0.72) mm∙ka−1、高原西部为(3.14±0.52) mm∙ka−1、喜马拉雅山脉西部为(3.36±0.67) mm∙ka−1、帕米尔高原东部为(3.45±0.59) mm∙ka−1、帕米尔高原西部为(3.11±0.41) mm∙ka−1、天山为(3.63±0.53) mm∙ka−1，恢复后整个青藏高原的TCN测年精度提高了10%左右。 |
| 关键词: 花岗岩风化晕 生长曲线模型 侵蚀模型 TCN测年 仁措湖 |
| DOI：10.7515/JEE182083 |
| CSTR： |
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| 基金项目:国家自然科学基金项目（41671005，41271093，41270743） |
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| Study on growth and erosion model of granite weathering-rinds (WRs) in Rencuo Lake area in the middle of Taniantaweng Mountains and terrestrial in situ cosmogenic nuclide (TCN) measurement |
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ZHANG Wei, LI Yapeng, CHAI Le, QIAO Jingru, TANG Qianyu
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College of Urban and Environmental Sciences, Liaoning Normal University, Dalian 116029, China
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| Abstract: |
| Background, aim, and scope With the advent of terrestrial in situ cosmogenic nuclide (TCN) as a more attractive and complex calibration age tool, weathering-rinds (WRs) provide only a rough age distribution compared to their precise radiation age. However, WRs should not be abandoned as a timing tool, and it can be used as a cosmogenic nuclides chronological correction indicator and sampling indicator to obtain the most accurate cosmological age. We intend to establish a model of granite WRs growth and erosion in the Rencuo Lake area of the Taniantaweng Mountains, and use this model to quantify the granite exposure age in the Rencuo Lake area. The granite WRs growth and erosion model combined with the TCN dating principle is used to quantify the granite glacial sediments at least eroded the rate and estimated the glacial age under the erosion, in order to provide a reference for the accurate dating of glacial deposits in the Taniantaweng Mountains. Materials and methods In order to obtain the most representative WRs thickness of each measuring point, the data of the measuring point are grouped into weighted groups, and the weighted average value is calculated as the WRs thickness of the measuring point. In order to verify the influence of topographic shielding and slope on the thickness of WRs, the shielding coefficient of sampling points and the correlation between slope and thickness of WRs were calculated. Therefore, the growth and erosion model of granite WRs in Rencuo Lake area is established, and the glacial age and erosion rate are measured by TCN dating method. Results Using the growth and erosion model of granite WRs, the growth rate of granite WRs is about 4.88 mm∙ (10 ka) −1 and the average erosion rate is 2.15 mm∙ka−1. Discussion The results of 10Be dating in the Qinghai-Tibet Plateau and its surrounding mountainous areas were restored by combining the WRs growth erosion model with the TCN dating theoretical model. At least the average erosion rates are (2.61±0.05) mm·ka−1, (3.43±0.70) mm·ka−1, (3.42±0.34) mm·ka−1, (3.71±0.72) mm∙ka−1, (3.14±0.52) mm∙ka−1, (3.36±0.67) mm∙ka−1, (3.36±0.67) mm∙ka−1, (3.45±0.59) mm∙ka−1, (3.11±0.41) mm∙ka−1, (3.63±0.53) mm∙ka−1, which reduces the uncertainty of the theoretical model assuming that the erosion rate is zero, and provides an external rationalization factor for improving the dating accuracy. Conclusions In this model, calculated by Rencuo Lake area, the area of granite weathering time is about (236±88)— (19834±1560) a. The results show that the glacial age of the whole Qinghai-Tibet Plateau has been increased by about 10% on average, and the glacial sediments of the Qinghai-Tibet Plateau have been restored at least according to the results of the previous years. Recommendations and perspectives It is only a preliminary attempt to determine the age and erosion rate of glaciers by combining WRs growth and erosion model with TCN chronology. Further research is needed to solve the problem of TCN dating error and improve its accuracy. |
| Key words: granite WRs growth curve model erosion model TCN dating Rencuo Lake |
