Santa Bárbara Formation (Caçapava do Sul, southern Brazil): depositional sequences and evolution of an Early Paleozoic postcollisional basin

Late to Post-Orogenic Brasiliano-Pan-African Volcano-Sedimentary Basins in the Dom Feliciano Belt, Southernmost Brazil

“…According to the same authors, the Lanceiros Formation is related to the progradation of an interlaced and sandy deltaic system of the longitudinal character, and the Pedra do Segredo Formation can be bounded to the progradation of an interlaced and sandy-conglomeratic of transversal nature. Borba & Mizusaki (2003) organized the Santa Bárbara Formation rocks in three depositional sequences named as, from the base to the top: Sequence I, Sequence II and Sequence III. The two basal sequences (I and II) represent a coherent depositional pattern, with axial fluvial and deltaic fan systems, which deposit North-Eastward with lateral contribution from alluvial fans.…”

Santa Bárbara Formation (Early Paleozoic, Caçapava do Sul, southern Brazil): Petrographic and Sm–Nd isotopic provenance parameters

“…The sedimentary record of the Santa Bárbara Formation consists of conglomerates, sandstones and siltstones deposited under semiarid conditions through the activity of alluvial fans, fluvial plains and ephemeral, constantly dried shallow lakes. Three depositional sequences have been recognized (Borba and Mizusaki, 2003). In sequences I and II, poorly sorted, massive or horizontally stratified conglomerates are the coarse-grained rocks, while trough-and planar-cross stratified sandstones, interlayered with siltstones that show abundant desiccation features (mudcracks, mud curlets, raindrop imprints), compose the fine-grained section.…”

“…On the other hand, sequence III marks the inversion of the transport sense in the depositional basin and an abrupt increasing of grain-size. This topmost unit, with markedly erosional character, is composed of trough-cross stratified, scoop-shaped beds of poorly sorted conglomerates and conglomeratic sandstones, with paleocurrents to southwest (Borba and Mizusaki, 2003).…”

“…The deposition of the Santa Bárbara Formation sedimentary rocks was processed during the dominantly extensional post-collisional setting of the Brasiliano/Pan-African orogenic cycle (900-540 Ma, Chemale, 2000), in a strike-slip or pull-apart basin (Paim et al, 2000;Borba and Mizusaki, 2003). A stratigraphic framework composed of three depositional sequences was proposed for this unit, in which the two basal sequences, I and II, record a general northeastward sedimentation trend, and sequence III marks the inversion of paleocurrents to southwest, together with incision and partial erosion of the basal sequences (Borba and Mizusaki, 2003).…”

“…2. Stratigraphic framework proposed by Borba and Mizusaki (2003) for Santa Bárbara Formation, made up of three depositional sequences. The rose-diagrams represent the measured paleocurrents, and the grey lozenges indicate the stratigraphic position of the samples analyzed in this study (geographic setting of P1, P2 and P3 profiles can be seen in Fig.…”