Date:11/27/2012

nerals and determine the amounts and isotopic compositions of U and Pb, using them to calculate the age of the minerals. The method has been under development for the past century and has become the most widely used geochronological tool. This paper by F. Corfu reviews the most salient developments in the modern history of the method, focusing especially on one important factor which complicates its application. This is the fact that some minerals, especially zircon, often reveal some discrepancies between the U-Pb ages obtained by the two decay systems. The main reasons for the discordance are generally partial loss of lead or mixing of multi age components, but there are also other factors. Much of the development of U-Pb geochronology has been devoted to the search and testing of techniques and approaches on how to eliminate the discordance. We have now come a long way towards a solution of the problem, but many challenges remain.

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Submarine slope processes in rift-margin basins, Miocene Suez Rift, Egypt
Lorna J. Strachan et al., School of Earth, Environment & Atmospheric Sciences, University of Manchester, Manchester, M13 9PL, UK. Posted online 31 October 2012; http://dx.doi.org/10.1130/B30665.1.

Submarine rift basins are prominent features on Earth's surface that provide insight to plate tectonics and contain important economic deposits. This study by Lorna J. Strachan and colleagues of ancient (Miocene) strata in the Sinai Peninsula, Egypt, reveals the complexity of sediment transport and deposition in an actively-rifting submarine basin. The research focuses on rift-margin basin evolution immediately adjacent to rift-bounding faults. Erosion and transport on the steep rift margin resulted in deposits built from energetic coalescing channelized gravity-flow deposits. Contemporaneous tectonic events modified seafloor relief, changing the pathways of sedime
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Contact: Kea Giles kgiles@geosociety.org Geological Society of America Source:Eurekalert

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