catchment
; clay mineral
; core analysis
; discharge
; Heinrich event
; humid environment
; interstadial
; monsoon
; paleoclimate
; Quaternary
; reconstruction
; river plume
; seasonal variation
; sediment core
; sediment transport
; Blue Nile [Nile River]
; Ethiopian Highlands
; Israel
; Mediterranean Sea
; Nile River
英文摘要:
Clay mineral assemblages in a sediment core from the distal Nile discharge plume off Israel have been used to reconstruct the late Quaternary Nile sediment discharge into the eastern Mediterranean Sea (EMS). The record spans the last ca. 140ĝ€kyr. Smectite abundances indicate the influence of the Blue Nile and the Atbara River that have their headwaters in the volcanic rocks of the Ethiopian Highlands. Kaolinite abundances indicate the influence of wadis, which contribute periodically to the suspension load of the Nile.
Due to the geographical position, the climate and the sedimentary framework of the EMS is controlled by two climate systems. The long-Term climate regime was governed by the African monsoon that caused major African humid periods (AHPs) with enhanced sediment discharge at 132 to <ĝ€126 (AHP 5), 116 to 99 (AHP4), and 89 to 77ĝ€ka (AHP3). They lasted much longer than the formation of the related sapropel layers S5 (>ĝ€2ĝ€kyr), S4 (3.5ĝ€kyr), and S3 (5ĝ€kyr). During the last glacial period (Marine Isotope Stages (MISs) 4-2), the long-Term changes in the monsoonal system were superimposed by millennial-scale changes in an intensified midlatitude glacial system. This climate regime caused short but pronounced drought periods in the Nile catchment, which are linked to Heinrich events and alternate with more humid interstadials.
Ehrmann W.,Schmiedl G.,Seidel M.,et al. A distal 140ĝ€kyr sediment record of Nile discharge and East African monsoon variability[J]. Climate of the Past,2016-01-01,12(3)