Solar forcing of Nile discharge and sapropel S1 formation in the early to middle Holocene eastern Mediterranean. (19th May 2014)

• Record Type: Journal Article
• Authors: Hennekam, Rick; Jilbert, Tom; Schnetger, Bernhard; de Lange, Gert J.
• Is Part Of: Paleoceanography. Volume 29:Number 5(2014)
• Page Start: 343
• Page End: 356
• Publication Date: 2014-05-19
• Subjects: Paleoceanography -- Periodicals; 551.46
• DOI: 10.1002/2013PA002553
• Languages: English
• ISSNs: 0883-8305

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>We present high‐resolution records for oxygen isotopes of the planktic foraminifer <italic>Globigerinoides ruber</italic> (δ<sup>18</sup>O<sub>ruber</sub>) and bulk sediment inorganic geochemistry for Holocene‐age sediments from the southeast Mediterranean. Our δ<sup>18</sup>O<sub>ruber</sub> record appears to be dominated by Nile discharge rather than basin‐scale salinity/temperature changes. Nile discharge was enhanced in the early to middle Holocene relative to today. The timing of the long‐term maximum in Nile discharge during the early Holocene corresponds to the timing of maximum intensity of the Indian Ocean‐influenced Southwest Indian summer monsoon (SIM). This coincidence suggests a major influence of an Indian Ocean moisture source on Nile discharge in the early to middle Holocene, while, presently, the Atlantic Ocean is the main moisture source. Nile discharge was highly variable on multicentennial time scale during the early to middle Holocene, being strongly influenced by variable solar activity. This solar‐driven variability is also recorded in contemporaneous SIM records, however, not observed in an Atlantic Ocean‐derived West African summer monsoon record from the Holocene. This supports the hypothesis that the Indian Ocean moisture source predominantly controlled Nile discharge at that time. Solar‐driven variability in Nile discharge also influenced paleoenvironmental conditions in the eastern Mediterranean. Bulk sediment Ba/Al and V/Al, used as indicators for (export) productivity and redox conditions, respectively, varied both in response to solar forcing on multicentennial time scales. We suggest that changes in Nile discharge on these time scales have been concordant with nutrient inputs to, and shallow ventilation of, the eastern Mediterranean.</p> </abstract>