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Constraining the evolution of river terraces with integrated OSL and cosmogenic nuclide data

Constraining the evolution of river terraces with integrated OSL and cosmogenic nuclide data

Authors :
Naomi Porat
Ari Matmon
David Fink
Yoav Avni
Benny Guralnik
Source :
Quaternary Geochronology. 6:22-32
Publication Year :
2011
Publisher :
Elsevier BV, 2011.

Abstract

We present a framework for consistent incorporation of optically-stimulated luminescence dates with cosmogenic radionuclide concentrations measured in a single alluvial section, and apply it on two late Quaternary terraces in the Negev Desert, Israel, to derive constraints on their evolution. We solve an integrated, self-consistent and co-dependant set of equations to reproduce either dataset based on three model parameters of (i) uniform cosmogenic inheritance, (ii) constant terrace aggradation rate and (iii) subsequent exposure time. A subset of all possible parameter combinations, which approximates the measurements within the uncertainties of their best-fits, yields a better constraint of the alluvial history than that obtained by any of these dating proxies alone. The derived set of common solutions indicates similar paleo-inheritances of ∼1 × 10 5 10 Be atoms g −1 in both terraces; progressive deposition of the higher terrace (T2) began at ∼250 ka, lasted for a period of ∼80 ka, was abandoned at ∼170 ka and since that time has remained intact; the lower terrace (T1) was most likely deposited at ∼3 ka and rapidly abandoned by ∼2 ka. In an alternative interpretation for T2, which treats the two geochronometers separately, this terrace might have experienced discrete events of aggradation at (216 ± 13) ka and deep truncation at 118 − 29 + 42 ka, significantly separated in time. In the currently active channel of the Neqarot canyon, contemporary stripping of the lowest terrace located along the stream is suggested by decreasing values of 10 Be downstream along the river channel.

Details

ISSN :
18711014
Volume :
6
Database :
OpenAIRE
Journal :
Quaternary Geochronology
Accession number :
edsair.doi...........6db48b74672f550105b892820485adf4
Full Text :
https://doi.org/10.1016/j.quageo.2010.06.002