The formation of Pliocene Mediterranean sapropels: constraints from high-resolution major and minor element studies

Abstract

Two Pliocene Mediterranean sediment cores from Sites 964 (Pisano Plateau, Ionian Basin) and 967 (lower northern slope of Eratosthenes Seamount, south of Cyprus), which comprise a total of 428 samples, have been analyzed for major and minor elements (Si, Ti, Al, Fe, Mg, Ca, K, Ba, Cr, Ni, V, Zn, and Zr) by X-ray fluorescence analysis at a depth resolution of 3-4 cm. Core 160-964C-9H comprises five sapropels with up to 9.7% total organic carbon (TOC), one 2.5-m-thick turbidite, and a 50-cm segment of a second turbidite, whereas Core 160-967B-9H contains eight sapropels with TOC content of up to 6.7%.Cyclic variations in carbonate content and detrital-matter composition are evident at both sites. At Site 964 (Pisano Plateau) terrigenous detrital matter chemistry reflects periods of stronger Saharan dust input alternating with fluvial input from the northern borderlands (higher K/Al and Mg/Al ratios). Cyclicity is not that well expressed at this location because turbidites or other short-term resedimentation processes occur. Site 967 (Eratosthenes Seamount) sediments are strongly influenced by discharge from the Nile River during humid periods (low K/Al and Mg/Al ratios).At Site 967 sapropels are occurring only during periods of enhanced Nile discharge and the corresponding lower

Tracking provenance change during the late Miocene in the eastern Mediterranean using geochemical and environmental magnetic parameters

“…North African dust can be traced by identifying hematite and goethite, which provide information concerning the abundance of transported dust [ Larrasoaña et al , 2003a]. Geochemical data in the eastern Mediterranean region can enable discrimination between materials originating from the Aegean or North Africa [ Bergametti et al , 1989; Wehausen and Brumsack , 1998; 2000; Lourens et al , 2001].…”

“…Previous investigations demonstrated that Al and Ca, and the ratios Ni/Al, Si/Al, Fe/Al, and Ti/Al are indicative of different sediment origins and can be linked to environmental conditions in certain source areas [e.g., Bergametti et al , 1989; Wehausen and Brumsack , 1998; Lourens et al , 2001]. Ni is associated with ultramafic rocks, which in this area are exclusively found in the Aegean region, whereas Si/Al and Ti/Al represent the African sources [ Wehausen and Brumsack , 2000].…”

A distal 140 kyr sediment record of Nile discharge and East African monsoon variability

“…This view is supported by several investigations (Wehausen and Brumsack, 1998;Emeis et al, 2000;Revel et al, 2010;Blanchet et al, 2014). However, it is in conflict with some other studies (Adamson et al, 1980;Krom et al, 1999aKrom et al, , 2002Box et al, 2011) that have argued for a lower Blue Nile sediment discharge during the warm and humid Holocene AHP and higher fluxes during dry climate phases.…”

Using non-negative matrix factorization in the “unmixing” of diffuse reflectance spectra

“…The sediments recovered from ODP 967A were composed of bioturbated nannofossil oozes, nannofossil clays and sapropels, which could be constrained within an astronomical chronology Sakamoto et al, 1998;Kroon et al, 1998) based on the timescale of Lourens et al (1996). Previous investigations of ODP 967A have provided geochemical (Wehausen and Brumsack, 1998;Lourens et al, 2001) and rock magnetic (Larrasoana et al, 2003) evidence for aeolian dust input, originating from Northern Africa.…”