DOI: 10.1016/j.quascirev.2017.07.005
Scopus记录号: 2-s2.0-85024089002
论文题名: A 3 million year index for North African humidity/aridity and the implication of potential pan-African Humid periods
作者: Grant K.M. ; Rohling E.J. ; Westerhold T. ; Zabel M. ; Heslop D. ; Konijnendijk T. ; Lourens L.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2017
卷: 171 起始页码: 100
结束页码: 118
语种: 英语
英文关键词: Aeolian dust
; African monsoon
; ODP Site 967
; Plio-Pleistocene
; Sapropels
; Scanning XRF
Scopus关键词: Aluminum alloys
; Atmospheric thermodynamics
; Calibration
; Climate change
; Dust
; Geochemistry
; Salinity measurement
; Scanning
; Aeolian dusts
; African monsoons
; ODP Site 967
; Plio-pleistocene
; Sapropels
; Principal component analysis
; aridity
; chemical composition
; composite
; data set
; depositional environment
; detrital deposit
; eolian deposit
; geochemical survey
; humid environment
; humidity
; Last Glacial
; Mediterranean environment
; monsoon
; Ocean Drilling Program
; paleoclimate
; Pliocene-Pleistocene boundary
; sapropel
; sediment analysis
; X-ray fluorescence
; East Africa
; North Africa
; Sahara
英文摘要: Mediterranean sediments are valuable archives of both African monsoon variability and higher-latitude climate processes, and can also be used to provide an environmental context for early human migrations and settlements. However, the long history of Mediterranean palaeoclimate studies largely pre-dates the advent of widespread x-ray fluorescence (XRF) core-scanning, so there are few continuous and high-resolution geochemical records from this key region that extend beyond the last glacial cycle. Here we present XRF core-scanning results for ODP Site 967 (Eastern Mediterranean) that have been fully-calibrated into element concentrations spanning the last 3 million years (My). Comparison with independent geochemical data from conventional XRF highlights disparities for certain element/element ratios, thus suggesting the need for caution when taking ratios of scanning XRF data. Principal component analysis of the calibrated XRF dataset reveals two dominant components: detrital inputs (PC1) and a ‘sapropel' (≈monsoon run-off) signal (PC2), which we use to establish a new orbitally-tuned chronology. We observe inverse covariation between PC2 and a previously published aeolian dust record from ODP Site 967 (Larrasoaña et al., 2003), and combine these records to produce a composite index of humidity and aridity for the wider North African region over the past 3 My. We propose that by combining run-off and dust signals in a single metric, our index captures the effects of both strengthening/northward migration (increased run-off) and weakening/southward retreat (increased dust) of the North African monsoon. Comparison of the index with published records of Northwest and East African palaeohumidity suggests that it tracks the timing of “Green Sahara Periods” throughout the Plio-Pleistocene, and that at least 30 of these intervals coincided with increased humidity across East Africa. We tentatively suggest that these specific episodes may be termed “pan-African Humid Periods”, as a means to highlight large-scale climate trends and to provide an environmental framework for palaeo-anthropological research. © 2017 Elsevier Ltd 资助项目: We thank Walter Hale and Vera Lukies at Marum for their assistance with core scanning and sampling, and Roy Wilkens for help with IGOR Pro software. This work was supported by Australian Research Council Australian Laureate Fellowship FL1201000050 (EJR), and by the Deutsche Forschungsgemeinschaft (We5479-1) (TW). We thank Jess Tierney and Rik Tjallingii for helpful feedback on the manuscript.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59122
Appears in Collections: 过去全球变化的重建
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作者单位: Research School of Earth Sciences, The Australian National University, Canberra, Australia; Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, United Kingdom; MARUM, University of Bremen, Bremen, Germany; Department of Earth Sciences, University of Utrecht, Utrecht, Netherlands
Recommended Citation:
Grant K.M.,Rohling E.J.,Westerhold T.,et al. A 3 million year index for North African humidity/aridity and the implication of potential pan-African Humid periods[J]. Quaternary Science Reviews,2017-01-01,171