Fine-grained sedimentary provenance analysis: a new approach for deposits in the Western Amazon

Abstract

The analysis of heavy minerals for determining provenance in sediments is commonly carried out on grains from the fine sand to very fine sand fraction, and doesn't explore the silt fractions. However, recent contributions in the literature have explored the analysis of heavy minerals in fractions smaller than 64 µm, using techniques such as Raman spectroscopy, which makes it possible to identify the mineralogical composition in silt granulometric ranges. This approach overcomes the limitations of conventional optical microscope analysis, making it possible to identify opaque minerals and offering a more precise characterization of heavy mineral assemblages. In this context, the proposed work involves the analysis of heavy minerals in Amazonian sedimentary deposits, focusing on fine fractions (5µm~64µm), in order to overcome limitations present in conventional analysis carried out on coarser fractions. The results obtained will be integrated with available geochronological and palynological data, seeking a more complete understanding of sedimentary provenance in the western Amazon region. This study will have relevance for future studies related to the application of heavy minerals in drill cores associated with the FAPESP Thematic Project TADP (Trans Amazon Drilling Project), allowing provenance analysis in finer grains and in situations with restricted sample volume. During a four-month internship at the University of Milano Bicocca, under the supervision of Associate Professor Sergio Andò, the candidate intends to deepen her knowledge in the analysis of heavy minerals in the silt fraction using Raman Spectroscopy. The expected gains include the training of the candidate as a researcher, the future application of Raman Spectroscopy in projects in Brazil and the contribution to the advancement of sedimentary provenance studies in the Amazon region. Collaboration on the TADP Project strengthens the links between the institutions and extends the impact of the results beyond the scope of the undergraduate research project.