PETROGRAPHIC AND DIAGENETIC CHARACTERIZATION OF THE PALEOGENE OF THE SÃO PAULO BASIN IN THE METROPOLITAN REGION OF SÃO PAULO

Petrographic and diagenetic characterization of the Paleogene of the northwest of the São Paulo Basin

Abstract

The São Paulo Basin is located in the southeastern portion of the State of São Paulo, encompassing a significant area of the São Paulo Metropolitan Region (RMSP). This study aims to deepen the petrographic understanding of the São Paulo and Resende Formations (Paleogene), as well as to establishing the diagenetic sequence that affected these deposits. To achieve this, qualitative and semi-quantitative petrographic analyses were conducted on drill core samples provided by the São Paulo Metropolitan Company (METRÔ) across the RMSP. These analyses allowed for the petrographic classification of the units, the identification of a well-difined diagenetic sequence, and the determination of the sediments depositional environment signature. The petrographic results indicate that the sandstones of the São Paulo and Resende Formations are predominantly subarkose and arkose. The diagenetic analysis reveals that the basin was subjected to shallow and low-intensity diagenetic processes (eodiagenesis) under a warm and humid climate, with no evidence of mesodiagenetic or telodiagenetic conditions. Additionally, this study documents diagenetic minerals not previously reported in the literature for this basin. Consequently, the present work contributes to a more comprehensive understanding of the textural, mineralogical, and compositional characteristics of the aquifers that constitute the São Paulo Basin.