Chemical Fingerprinting, A Precise and Efficient Method To Determine Sediment Sources

Abstract

Abstract An accurate method of determining source locations for detrital sediment is presented using the chemical composition of Fe-oxide minerals like a fingerprint. This method is an improvement in the use of Fe-oxide minerals for provenance determinations because it requires less time and fewer source samples. A rigorous test of the method uses a database of more than 38,000 grains from known locations. The average error of matching grains back to 45 source locations designated for this database is less than 2%. The method allows for proportional matching of a grain to multiple sources if other grains in the source database meet the compositional match criteria, which helps reduce the error of incorrect matches. Most provenance studies do not involve source basins as large as the entire Arctic Ocean, where sediment can be ice-rafted several thousand kilometers. For most studies, only a few samples (∼ 100 grain analyses/sample) would be required to characterize a source if strategically placed, such as near a river mouth. Deposits more than 40 million years old can be traced to specific sources using this method because Fe-oxide grains are relatively stable in most deposits.