Assessing the sediment factory: The role of single grain analysis

Type and amount of sediment generation are intimately connected to tectonic and climatic processes active at the earth's surface today as well as throughout the geologic past. Detrital single grains (sand to very coarse silt sized) from well-dated sedimentary formations serve as mineral tracers in sedimentary systems and record the sediment-forming processes. In this review, a selection of individual methods available to extract petrogenetic and chronological information from detrital mineral grains is compiled. Emphasis is placed on techniques, concepts, and their possibilities and shortcomings in defining the type and geologic history of source rocks, as well as the rates and relative proportions at which sediments are being eroded and delivered to basins. Statistical issues intrinsically coupled to the interpretation of detrital single-grain distributions are highlighted, as well as new emerging techniques. These include geochronology of phases like e.g. titanite, monazite, or rutile to overcome the common restriction to apatite or zircon bearing lithologies, as well as any kind of double or triple dating to extract both high-T and low-T thermochronological information from the very same detrital grains. Mineral pairs are especially suited to quantify the relative contributions of well-defined source rocks or areas to the sediment when the two phases (i) occur in contrasting rock types, (ii) are relatively stable under sedimentary conditions, and (iii) allow for extracting significant and detailed information on source rock petrology and chronology. In general, however, multi-method approaches are the only way to overcome ambiguous information from the sedimentary record. In combination with either independent information on sediment flux or erosion rates derived from single-grain thermochronology, the sediment-forming processes as well as their controlling mechanisms and overall geologic settings can be properly assessed.