Neodymium isotope provenance of eolian dust in the South Pacific from 70 to 30 Ma

Author(s): Rencurrel, M. C.; Thomas, D. J.
Author Affiliation(s): Primary:
Texas A&M University, Department of Atmospheric Sciences, College Station, TX, United States
Volume Title: AGU 2013 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2013; American Geophysical Union 2013 fall meeting, San Francisco, CA, Dec. 9-13, 2013. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Late Cretaceous and Early Paleogene was the most recent interval of global greenhouse warmth, likely due to atmospheric carbon dioxide levels that were 2-5 times higher than modern levels. Proxy reconstructions of sea-surface temperatures suggest that the meridional temperature gradient during the Early Eocene (∼50 Ma) was possibly as much as 15°C lower than that of the modern. Theory and climate model simulations predict that one potential consequence of overall warmth and the associated low meridional thermal gradient is that zonal wind belts extended further poleward than in the modern climate. The resulting variations in zonal wind patterns likely would have impacted the transport of heat and moisture. In this study we generated temporal records of dust provenance to reconstruct zonal wind patterns in the Southern Hemisphere. The Neodymium (Nd) isotopic composition of eolian dust that accumulated in pelagic sediments retains the fingerprint of the dust source region and therefore may be a useful indicator of wind direction accumulation in locations far removed from the influence of fluvial or hemipelagic processes. Here we present the first Late Cretaceous and Early Paleogene eolian provenance records from South Pacific DSDP Site 596 and IODP Site U1370. The paleo-latitude of Site U1370 was ∼60°S at 50 Ma, while the paleo-latitude of Site 596 was ∼35°S. The detrital εNd(t) values recorded at both Sites 596 and U1370 varied between ∼-6.5 and -9 throughout the 70 to 30 Ma study interval, with little overall temporal trend. The similarity of values at both sites suggests that the overall source of dust to this broad region spanning the subtropics to temperate latitudes was similar. The relatively low Nd isotopic signature indicates a significant contribution of dust from a continental source region. The likely Southern Hemisphere source in the Pacific was Australia implying that both sites were influenced by the westerlies throughout the study interval.
Year of Publication: 2013
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Cenozoic; Clastic sediments; Cores; Cretaceous; DSDP Site 596; Deep Sea Drilling Project; Dust; East Pacific; Expedition 329; IODP Site U1370; IPOD; Integrated Ocean Drilling Program; Isotopes; Leg 91; Lower Paleogene; Marine sediments; Mesozoic; Metals; Neodymium; Pacific Ocean; Paleogene; Rare earths; Sediments; South Pacific; Southeast Pacific; Tertiary; Upper Cretaceous
Coordinates: S415107 S415107 W1530623 W1530623
S235113 S235111 W1653916 W1653917
Record ID: 2015080398
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