宇宙成因核素^(26)Al/^(10)Be约束贵州涟江流域沉积物埋藏历史  

In-Situ Cosmogenic Nuclide ^(26)Al/^(10)Be Constraints the Burial History of Sediments in Lianjiang Drainage,Guizhou

作　　者：张顺成 杨业[1] 崔丽峰 徐胜 ZHANG Shuncheng;YANG Ye;CUI Lifeng;XU Sheng(Institute of Surface-Earth System Science,School of Earth System Science,Tianjin University,Tianjin300072,China)

机构地区：[1]天津大学地球系统科学学院-表层地球系统科学研究院,天津300072

出　　处：《地球与环境》2022年第4期439-447,共9页Earth and Environment

基　　金：《第二次青藏高原综合科学考察》项目(2019QZKK0707)。

摘　　要：贵州喀斯特地区位于青藏高原向丘陵地貌转换过渡带,区内发育多级层状地貌面,是研究区域构造-气候-剥蚀耦合作用的天然实验场。本文测定了贵州省惠水县境内涟江I级阶地沉积物中原位宇宙成因核素^(10)Be和^(26)Al浓度,通过暴露-埋藏模型对沉积物埋藏历史和物源进行研究。与前人研究结果相比,涟江流域单核素剥蚀速率(^(10)Be平均剥蚀速率为10.85±0.97 m/Ma)显著低于贵州高原其他流域。结合双核素暴露-埋藏模型,研究结果表明更新世以来沉积物样品可能经历了复杂暴露-埋藏-再暴露过程,其物源可能是异地埋藏或洞穴堆积等非稳态剥蚀区。宇宙成因核素对^(26)Al-^(10)Be联用能有效判别非稳态剥蚀过程,弥补了单核素不能表征沉积物埋藏历史的不足。Located in the transitional zone from Tibet plateau to hilly landform,Guizhou karst area is characterized by multi-layered landform surfaces,and is considered as a natural experimental field for studying the coupling effect of regional tectonics-climate-denudation.In this study,two riverine sediments were collected from Lianjiang catchment and analyzed for the in-situ cosmogenic nuclide ^(10)Be and ^(26)Al concentrations from which the burial history and provenance were studied by the exposure-burial model.Compared with previous studies,the denudation rates(10.85±0.97 m/Ma)of single nuclide(^(10)Be)in the Lianjiang River Drainage are significantly lower than that in other drainages of the Guizhou Plateau.Combined with the dual-nuclide exposure-burial model,the results indicate that the sediment samples may have experienced a complex exposure-burial-re-exposure process since the Pleistocene,and the provenance may be in the non-steady denudation zones,such as heterochthonous burial or speleothem.The combination of cosmogenic nuclides ^(26)Al and ^(10)Be can effectively distinguish the unsteady denudation process,which makes up for the deficiency that single nuclide cannot characterize the complex burial history of sediments.

关 键 词：^(26)Al/^(10)Be 河流沉积物 埋藏历史 剥蚀速率 涟江流域 贵州 

分 类 号：P597[天文地球—地球化学]