Tectonic and Stratigraphic Evolution Based on Seismic Sequence Stratigraphy: Central Rift Section of the Campos Basin, Offshore Brazil

Abstract

The rift section of the Brazilian basins represent the sedimentary record associated with the first stages of Gondwana break-up in the Early Cretaceous phase (Berriasian to Aptian). The rift succession of the Campos Basin constitutes one of the main petroleum systems of Brazil’s marginal basins. This interval contains the main source rock and important reservoirs in the Lagoa Feia Group deposits. The Lagoa Feia Group is characterized by siliciclastic, carbonate and evaporite sediments deposited during the rift and post-rift phases. Despite the economic relevance, little is known in stratigraphic terms regarding this rift interval. To date, most studies of the Lagoa Feia Group have adopted a lithostratigraphic approach, while this study proposes a tectonostratigraphic framework for the deep-rift succession of the Campos Basin (Lagoa Feia Group), using the fundamentals of seismic sequence stratigraphy. This work also aims to establish a methodological and practical procedure for the stratigraphic analysis of rift basins, using seismic data and seismofacies, and focusing on tectonicstratigraphic analysis. The dataset comprised 2D seismic lines, core and lithological logs from exploration wells. Three seismic facies were identified based on reflector patterns and lithologic data from well cores, providing an improved subdivision of the pre-, syn- and post-rift stages. The syn-rift stage was further subdivided based on the geometric patterns of the reflectors. Tectonics was the main controlling factor in the sedimentary succession, and the pattern and geometry of the seismic reflectors of the syn-rift interval in the Campos Basin allowed the identification of three tectonic systems tracts: (i) a Rift Initiation Systems Tract; (ii) a High Tectonic Activity Systems Tract and (iii) a Low Tectonic Activity Systems Tract.

Tectono‐stratigraphic evolution of the rift and post‐rift systems in the Northern Campos Basin, offshore Brazil

“…In the northern Campos basin, we observed significant erosion on the top of the Macabu Formation (Figure 9). A similar observation was made in the shallow water domain of the Central Campos Basin (Alvarenga et al, 2021;Goldberg et al, 2017). Such a long sub-aerial exposure (9 Myr) could imply the occurrence of extensive epigenetic karstification on the uppermost section of the pre-salt sequence, which was never reported in the literature on the Campos and Santos Basins.…”

“…We tentatively compared our findings with the few publications focused on the petrological–sedimentological content and the 2D seismic‐stratigraphic architecture of a single half‐graben in the shallow water domain of the Central Campos Basin (Alvarenga et al, 2021; Goldberg et al, 2017). Three syn‐rift system tracts represent the rift tectono‐sedimentary record as interpreted by Alvarenga et al (2021).…”

“…We tentatively compared our findings with the few publications focused on the petrological-sedimentological content and the 2D seismic-stratigraphic architecture of a single half-graben in the shallow water domain of the Central Campos Basin (Alvarenga et al, 2021;Goldberg et al, 2017). Three syn-rift system tracts represent the rift tectono-sedimentary record as interpreted by Alvarenga et al (2021). Their basal unit (Rift Initiation) could potentially be correlated with RP1, and the upper High and uppermost Low Tectonic Activity Systems Tracts could be correlated with, respectively, SRII and syn-rift III (SRIII) (i.e., the RP2).…”

“…Several studies of rifting of the Campos Basin in the context of the break‐up of the South Atlantic Ocean during the Early Cretaceous have been made using a combination of regional 2D seismic, wellbore and potential field data (Chang et al, 1992; Ponte & Asmus, 1976; Stanton et al, 2019). However, relatively few studies have been made using high‐resolution 3D seismic data at the scale of segments of basin‐wide faults that constitute the rift system (Alvarenga et al, 2021; Fetter, 2009; Olivito & Souza, 2020). Also, systematic structural mapping is only available for the Central sector of the Campos Basin (Guardado et al, 1989a).…”

“…high-resolution 3D seismic data at the scale of segments of basin-wide faults that constitute the rift system (Alvarenga et al, 2021;Fetter, 2009;Olivito & Souza, 2020). Also, systematic structural mapping is only available for the Central sector of the Campos Basin (Guardado et al, 1989a).…”