Using multiple chronometers to establish a long, directly-dated lacustrine record: Constraining >600,000 years of environmental change at Chew Bahir, Ethiopia
Using multiple chronometers to establish a long, directly-dated lacustrine record: Constraining >600,000 years of environmental change at Chew Bahir, Ethiopia
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DOI：
10.1016/j.quascirev.2021.107025
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发表时间：
2021-07
影响因子：
4
通讯作者：
H. Roberts;C. Ramsey;M. S. Chapot;A. Deino;C. Lane;C. Vidal;A. Asrat;A. Cohen;Verena Foerster;H. Lamb;F. Schäbitz;M. Trauth;F. Viehberg
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作者：
H. Roberts;C. Ramsey;M. S. Chapot;A. Deino;C. Lane;C. Vidal;A. Asrat;A. Cohen;Verena Foerster;H. Lamb;F. Schäbitz;M. Trauth;F. Viehberg
尽管东非是智人出现和随后从非洲扩散出去的关键地点，但该地区缺乏长期的、日期明确的气候记录来描述这段历史。为了解决这个问题，我们从Chew Bahir，埃塞俄比亚南部，使用三个独立的计时器（放射性碳，40 Ar/39 Ar，光释光）结合地球化学相关的一个已知的年龄火山灰的一个293米长的复合沉积物芯。该遗址位于气候敏感地区，靠近奥莫基比什（Omo Kibish），这是非洲东部最早的人类化石遗址，也是人类离开非洲的传播路线。由各种技术产生的30个年龄是内部一致的，地层连贯的，并跨越整个范围的核心深度。贝叶斯年龄-深度模型使用这些年龄的结果，形成了一个最长的独立日期，高分辨率的湖相沉积物记录从非洲东部的年表。年表表明，任何保存在Chew Bahir复合沉积物岩心中的环境变化记录都将跨越现代人类进化和扩散的整个时间尺度，包括从Acheulean过渡到中石器时代（MSA）的时间段，以及随后到晚石器时代（LSA）的技术，使岩心能够很好地解决有关环境变化和人类进化适应的问题。直接测年和使用多个独立的计时器的好处进行了讨论。
Despite eastern Africa being a key location in the emergence ofHomo sapiensand their subsequent dispersal out of Africa, there is a paucity of long, well-dated climate records in the region to contextualize this history. To address this issue, we dated a ∼293 m long composite sediment core from Chew Bahir, south Ethiopia, using three independent chronometers (radiocarbon,40Ar/39Ar, and optically stimulated luminescence) combined with geochemical correlation to a known-age tephra. The site is located in a climatically sensitive region, and is close to Omo Kibish, the earliest documentedHomo sapiensfossil site in eastern Africa, and to the proposed dispersal routes forH. sapiensout of Africa. The 30 ages generated by the various techniques are internally consistent, stratigraphically coherent, and span the full range of the core depth. A Bayesian age-depth model developed using these ages results in a chronology that forms one of the longest independently dated, high-resolution lacustrine sediment records from eastern Africa. The chronology illustrates that any record of environmental change preserved in the composite sediment core from Chew Bahir would span the entire timescale of modern human evolution and dispersal, encompassing the time period of the transition from Acheulean to Middle Stone Age (MSA), and subsequently to Later Stone Age (LSA) technology, making the core well-placed to address questions regarding environmental change and hominin evolutionary adaptation. The benefits to such studies of direct dating and the use of multiple independent chronometers are discussed.