Accurately calibrated X-ray fluorescence core scanning (XRF-CS) record of Ti ∕ Al reveals Early Pleistocene aridity and humidity variability over North Africa and its close relationship to low-latitude insolation
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Published:2022-11-22
Issue:11
Volume:18
Page:2509-2521
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ISSN:1814-9332
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Container-title:Climate of the Past
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language:en
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Short-container-title:Clim. Past
Author:
Hennekam Rick, Grant Katharine M., Rohling Eelco J., Tjallingii RikORCID, Heslop David, Roberts Andrew P., Lourens Lucas J., Reichart Gert-Jan
Abstract
Abstract. In eastern Mediterranean sediments, the titanium-to-aluminum ratio
(Ti/Al) captures relative variability in eolian to river-derived
material and predominantly integrates climate signals over the Saharan and
Sahel regions. Long Ti/Al time series can, therefore, provide valuable
records of North African humidity and aridity changes. X-ray fluorescence core
scanning (XRF-CS) can generate near-continuous Ti/Al records with relatively
modest effort and in an acceptable amount of time, provided that accurate
Ti/Al values are acquired. Calibration of raw XRF-CS data to those of
established analytical methods is an important pathway for obtaining the
required accuracy. We assess how to obtain reliable XRF-CS Ti/Al calibration
by using different calibration reference sample sets for a long sediment
record from ODP Site 967 (eastern Mediterranean Sea). The accuracy of
reference concentrations and the number of reference samples are important
for reliable calibration. Our continuous Ti/Al record allows detailed
time series analysis over the past 3 Myr. Near-direct control of low-latitude
insolation on the timing and amplitude of North African aridity and humidity is
observed from 3 to ∼ 1.2 Ma. In our Ti/Al record, most arid
North African intervals (i.e., with the longest period and highest
amplitude) occur after the mid-Pleistocene transition (MPT; ∼ 1.2–0.7 Ma), when ice ages intensified. We also observe a subdued
relationship between low-latitude insolation and North African climate after
the MPT. These findings support the growing consensus that African climate
became more sensitive to remote high-latitude climate when a threshold ice
volume was reached during the MPT.
Funder
Aard- en Levenswetenschappen, Nederlandse Organisatie voor Wetenschappelijk Onderzoek Netherlands Earth System Science Centre Australian Research Council
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Global and Planetary Change
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