https://scholars.lib.ntu.edu.tw/handle/123456789/626965
標題: | Orbital control of Pleistocene euxinia in Lake Magadi, Kenya | 作者: | Deocampo, DM Owen, RB Lowenstein, TK Renaut, RW Rabideaux, NM Billingsley, A Cohen, A Deino, AL Sier, MJ Luo, S CHUAN-CHOU SHEN Gebregiorgis, D Campisano, C Mbuthia, A |
關鍵字: | OLORGESAILIE FORMATION; ENVIRONMENTAL-CHANGE; RIFT; SEDIMENTATION; VARIABILITY; BASIN | 公開日期: | 2022 | 出版社: | GEOLOGICAL SOC AMER, INC | 卷: | 50 | 期: | 1 | 起(迄)頁: | 42 | 來源出版物: | GEOLOGY | 摘要: | Lake Magadi is an internally drained, saline and alkaline terminal sump in the southern Kenya Rift. Geochemistry of samples from an ∼200 m core representing the past ∼1 m.y. ofthe lake’s history shows some of the highest concentrations of transition metals and metalloidsever reported from lacustrine sediment, including redox-sensitive elements molybdenum,arsenic, and vanadium. Elevated concentrations of these elements represent times when thelake’s hypolimnion was euxinic—that is, anoxic, saline, and sulfide-rich. Euxinia was commonafter ca. 700 ka, and after that tended to occur during intervals of high orbital eccentricity.These were likely times when high-frequency hydrologic changes favored repeatedepisodes of euxinia and sulfide precipitation. High-amplitude environmental fluctuations atpeak eccentricity likely impacted water balance in terrestrial habitats and resource availabilityfor early hominins. These are associated with important events in human evolution,including the first appearance of Middle Stone Age technology between ca. 500 and 320 kain the southern Kenya Rift |
URI: | https://scholars.lib.ntu.edu.tw/handle/123456789/626965 | ISSN: | 0091-7613 | DOI: | 10.1130/G49140.1 |
顯示於: | 地質科學系 |
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