HIGH-RESOLUTION PROVENANCE STUDIES: INTEGRATING BULK AND SINGLE GRAIN TECHNIQUES (Invited Presentation)

Provenance studies have been deeply affected by the technical developments that took place in the last decades. Time-consuming classical techniques such as bulk petrography and heavy mineral analysis have been progressively combined by new techniques that allow collection of larger datasets, extending the analytical precision and the range of grain sizes that can be investigated, granting the study of the mineralogy and compositional variability of sand and silt in different geological setting and depositional environments.

Detrital geochronology and single-grain techniques in general, combined with progressive improvements in time- and cost-effectiveness and the array of potential target minerals, are perhaps the field that gained the largest popularity in the last years, relegating optical observations and traditional methods to secondary roles.

Applying high-resolution techniques on specific detrital minerals on the one hand allows the collection of large datasets, more robust statistics and operator-independent results; on the other hand, an increased precision does not always mean greater accuracy in provenance interpretation, as numerous biases must be properly taken into account.

An integrated approach, combining both bulk and single grain techniques and quantitative models on physical and chemical processes that affect sediment composition from source to sink and after deposition, is thus required. Examples from modern sediments and sedimentary successions in Africa and Indus Fan will show how optical observations under the microscope and textural analysis can be coupled with detrital zircon geochronology and Raman spectroscopy on garnet, pyroxene, amphibole, epidote and zircon to reconstruct their individual tale and the story of the whole sediment, allowing to balance their intrinsic biases and improving the resolution of provenance investigations.