Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Matmon, A. Articles by Finkel, R. Search for Related Content GeoRef GeoRef Citation

Desert pavement–coated surfaces in extreme deserts present the longest-lived landforms on Earth

Ari Matmon^1,, Ori Simhai², Rivka Amit³, Itai Haviv⁴, Naomi Porat⁵, Eric McDonald⁶, Lucilla Benedetti⁷ and Robert Finkel⁸

¹ The Institute of Earth Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
² The Institute of Earth Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel, and Geological Survey of Israel, 30 Malkhe Israel Street, Jerusalem 95501, Israel
³ Geological Survey of Israel, 30 Malkhe Israel Street, Jerusalem 95501, Israel
⁴ The Institute of Earth Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
⁵ Geological Survey of Israel, 30 Malkhe Israel Street, Jerusalem 95501, Israel
⁶ Desert Research Institute, 2215 Raggio Parkway, Reno, Nevada 89512, USA
⁷ Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement, Europôle Méditerranéen de l'Arbois, BP 80, Aix en Provence, cedex 04, 13545, France
⁸ Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA

Correspondence: E-mail: arimatmon{at}cc.huji.ac.il.

All exposed rocks on Earth's surface experience erosion; the fastest rates are documented in rapidly uplifted monsoonal mountain ranges, and the slowest occur in extreme cold or warm deserts—millennial submeter-scale erosion may be approached only in the latter. The oldest previously reported exposure ages are from boulders and clasts of resistant lithologies lying at the surface, and the slowest reported erosion rates are derived from bedrock outcrops or boulders that erode more slowly than their surroundings; thus, these oldest reported ages and slowest erosion rates relate to outstanding features in the landscape, while the surrounding landscape may erode faster and be younger. We present erosion rate and exposure age data from the Paran Plains, a typical environment in the Near East where vast abandoned alluvial surfaces (10²–10⁴ km²) are covered by well-developed desert pavements. These surfaces may experience erosion rates that are slower than those documented elsewhere on our planet and can retain their original geometry for more than 2 m.y. Major factors that reduce erosion converge in these regions: extreme hyperaridity, tectonic stability, flat and horizontal surfaces (i.e., no relief), and effective surface armoring by a clast mosaic of highly resistant lithology. The ¹⁰Be concentrations in amalgamated desert pavement chert clasts collected from abandoned alluvial surfaces in the southern Negev, Israel (representing the Sahara-Arabia Deserts), indicate simple exposure ages of 1.5–1.8 Ma or correspond to maximum erosion rates of 0.25–0.3 m m.y.^–1. The ³⁶Cl in carbonate clasts, from the same pavement, weathers faster than the chert and yields simple exposure ages of 430–490 ka or maximum erosion rates of 0.7–0.8 m m.y.^–1. These ages and rates are exceptional because they represent an extensive landform. The ¹⁰Be concentrations from samples collected at depth and optically stimulated luminescence (OSL) dating reveal a two-stage colluvial deposition history followed by eolian addition of 40 cm of silt during the past 170 k.y. Our results highlight the efficiency of desert pavement armor in protecting rocks from erosion and preserving such geomorphic surfaces for millions of years.