Stratigraphic architecture of a multi-sourced, Deepwater lobe complex (early Permian, Paraná basin, Brazil)

Abstract

The Rio Segredo Member of the Taciba Formation (Paraná Basin, Brazil) represents a unique example of a multi-sourced turbidite lobe complex, providing valuable insights into the stratigraphic architecture and depositional processes of delta-fed submarine ramp systems. This study investigates the lobe complex, which extends over 120 km and reaches a thickness of up to 40 m, with a focus on bed type distribution, facies associations, and stratigraphic architecture. Through the analysis of 16 measured sections and detailed facies analysis, 14 distinct bed types were identified, including turbidites (TBDs), hybrid event beds (HEBs), and slump and blocky flow deposits (MTDs). These beds are organized into four sub-environments: lobe axis, lobe off-axis, lobe fringe, and distal lobe fringe, reflecting a compensational stacking pattern with lobe centroids shifting southward by an average of 25 km. Paleocurrent data indicates predominant flow directions to the northwest (320°) and southwest (235°), supporting the interpretation of a multi-sourced system. The lobe complex is interpreted as a delta-fed submarine ramp, with deposition driven by delta-front instabilities and hyperpycnal flows via conduits connected to prograding delta. Hybrid event beds, which are common in the basal sandy portion of the succession, are linked to substrate erosion and interactions with small-scale morphological highs, highlighting the influence of paleophysiography on flow dynamics. This study enhances the understanding of multi-sourced turbidite systems and provides a framework for identifying similar systems in other basins. The findings underscore the importance of autogenic controls, such as lobe avulsion and topographic compensation, in shaping the stratigraphic architecture of delta-fed turbidite systems.