East African mid-Holocene wet-dry transition recorded in palaeo-shorelines of Lake Turkana, northern Kenya Rift
East African mid-Holocene wet-dry transition recorded in palaeo-shorelines of Lake Turkana, northern Kenya Rift
复制标题
DOI：
10.1016/j.epsl.2012.03.016
复制
发表时间：
2012-05-15
影响因子：
5.3
通讯作者：
Tiercelin, Jean-Jacques
中科院分区：
文献类型：
--
作者：
Garcin, Yannick;Melnick, Daniel;Tiercelin, Jean-Jacques
热带非洲全新世早期到中期的“湿润”，随着季风的增强，突然转向干燥的条件，最终被持续到今天的干燥气候所取代。这一重大气候转变的强迫机制、时间和空间范围还没有得到很好的理解，仍然是正在进行的研究的主题。我们使用了一个详细的古海岸线记录图尔卡纳湖（肯尼亚）来破译和解释这一显着的气候转变在东非。我们提出了一个高精度的调查保存完好的古海岸线，新的放射性碳年龄从海岸线沉积物，和氧同位素测量淡水软体动物壳，以阐明全新世水分历史从以前的湖泊水位在这个气候敏感的地区。结合以前发表的数据，我们的研究表明，在全新世早期的图尔卡纳湖水位高，湖泊溢出暂时进入白色尼罗河排水系统。然而，在全新世中期（类似于5270 +/- 300 cal. yr BP），湖泊水位下降了50米，与非洲大陆的主要干旱事件同时代。图尔卡纳盆地的古水文和考古数据之间的比较表明，全新世中期的气候转变与史前文化的根本变化，突出了自然气候变化的重要性和相关的长期干旱时期的主要环境压力因素影响人类在东非裂谷系统的占领。(C)2012爱思唯尔有限公司版权所有。
The 'wet' early to mid-Holocene of tropical Africa, with its enhanced monsoon, ended with an abrupt shift toward drier conditions and was ultimately replaced by a drier climate that has persisted until the present day. The forcing mechanisms, the timing, and the spatial extent of this major climatic transition are not well understood and remain the subject of ongoing research. We have used a detailed palaeo-shoreline record from Lake Turkana (Kenya) to decipher and characterise this marked climatic transition in East Africa. We present a high-precision survey of well-preserved palaeo-shorelines, new radiocarbon ages from shoreline deposits, and oxygen-isotope measurements on freshwater mollusk shells to elucidate the Holocene moisture history from former lake water-levels in this climatically sensitive region. In combination with previously published data our study shows that during the early Holocene the water-level in Lake Turkana was high and the lake overflowed temporarily into the White Nile drainage system. During the mid-Holocene (similar to 5270 +/- 300 cal. yr BP), however, the lake water-level fell by similar to 50 m, coeval with major episodes of aridity on the African continent. A comparison between palaeo-hydrological and archaeological data from the Turkana Basin suggests that the mid-Holocene climatic transition was associated with fundamental changes in prehistoric cultures, highlighting the significance of natural climate variability and associated periods of protracted drought as major environmental stress factors affecting human occupation in the East African Rift System. (C) 2012 Elsevier B.V. All rights reserved.