Source provenance of carbonate grains in the Wahiba Sand Sea, Oman, using a new LIBS method

The Wahiba Sand Sea is a large dune system composed of northern and southern zones. The dunes receive sand from multiple sources including two fluvial systems draining mountain basins, older underlying dunes, and a large coastline. Although the sand sea is distinctly divided into geomorphic regions with different dunes types, ages, and bulk mineral compositions, the ubiquitous presence of carbonate grains throughout the dune field has led to models that suggest the coast and shallow shelf is the direct and primary source of sediment for the entire sand sea. This study uses a novel method which couples selective, grain-by-grain analysis using laser-induced breakdown spectroscopy (LIBS) of a single mineral species with the classification method of Soft Independent Modeling of Class Analogy (SIMCA). The analysis of carbonate grains using the LIES method reveals that the carbonates are comprised of several sub-populations that are well mixed throughout the dune field. Individual sources of carbonate grains are also composed of multiple sub-populations creating further complexity. Sand in the Northern Wahiba is predominantly, and directly, derived from wadi systems that lie on the west and northeast sides of the dunes and once bordered the southern end of the dunes. The Southern Wahiba is composed of a more complex mixture of sand derived from the coast; however, the coastal sediments themselves were dominantly derived from the fluvial systems in the region, along with sediment of unknown original source. The new LIBS/SIMCA method of grain-by-grain analysis shows promise for unraveling complex mixing patterns in sedimentary deposits. (C) 2014 Published by Elsevier B.V.