Scrivner, Adam E. et al. (2004): New neodymium isotope data quantify Nile involvement in Mediterranean anoxic episodes

Leg/Site/Hole:
ODP 160
ODP 160 967
Identifier:
2004-056722
georefid

10.1130/G20419.1
doi

Creator:
Scrivner, Adam E.
Royal Holloway University of London, Department of Geology, Egham, United Kingdom
author

Vance, Derek
Southampton University, United Kingdom
author

Rohling, Eelco J.
author

Identification:
New neodymium isotope data quantify Nile involvement in Mediterranean anoxic episodes
2004
Geology (Boulder)
Geological Society of America (GSA), Boulder, CO, United States
32
7
565-568
The development of widespread anoxic conditions in the deep oceans is evidenced by the accumulation and preservation of organic-carbon-rich sediments, but its precise cause remains controversial. The two most popular hypotheses involve (1) circulation-induced increased stratification resulting in reduced oxygenation of deep waters or (2) enhanced productivity in the surface ocean, increasing the raining down of organic matter and overwhelming the oxic remineralization potential of the deep ocean. In the periodic development of deep-water anoxia in the Pliocene-Pleistocene Mediterranean Sea, increased riverine runoff has been implicated both as a source for nutrients that fuel enhanced photic-zone productivity and a source of a less dense freshwater cap leading to reduced circulation, basin-wide stagnation, and deep-water oxygen starvation. Monsoon-driven increases in Nile River discharge and increased regional precipitation due to enhanced westerly activity-two mechanisms that represent fundamentally different climatic driving forces-have both been suggested as causes of the altered freshwater balance. Here we present data that confirm a distinctive neodymium (Nd) isotope signature for the Nile River relative to the Eastern Mediterranean-providing a new tracer of enhanced Nile outflow into the Mediterranean in the past. We further present Nd isotope data for planktonic foraminifera that suggest a clear increase in Nile discharge during the central intense period of two recent anoxic events. Our data also suggest, however, that other regional freshwater sources were more important at the beginning and end of the anoxic events. Taken at face value, the data appear to imply a temporal link between peaks in Nile discharge and enhanced westerly activity.
English
Serial
Coverage:Geographic coordinates:
North:34.0411
West:32.4331East: 32.4331
South:34.0411

Quaternary geology; Isotope geochemistry; Africa; anaerobic environment; biochemistry; Cenozoic; East Mediterranean; Foraminifera; geochemistry; hydrology; Invertebrata; isotope ratios; isotopes; Leg 160; Levantine Basin; marine environment; Mediterranean Sea; metals; microfossils; Nd-144/Nd-143; neodymium; Nile River; O-18/O-16; Ocean Drilling Program; ODP Site 967; organic compounds; oxygen; paleo-oceanography; paleohydrology; planktonic taxa; Pleistocene; Protista; Quaternary; rare earths; rivers and streams; sapropel; sea water; stable isotopes; surface water; tracers;

.