Late Aptian (Cretaceous) paleoceanography of the South Atlantic Ocean inferred from dinocyst communities of the Sergipe Basin, Brazil

Abstract

The late Aptian (Early Cretaceous) is a crucial time interval for understanding the paleoceanographic changes in the Southern Hemisphere. Oceanographic changes in the emerging South Atlantic Ocean during this interval are reflected in the stratigraphic distribution of dinoflagellate communities recorded in the Muribeca and Riachuelo formations of the Sergipe Basin in northeastern Brazil. The Subtilisphaera community, in the lower and middle parts of the section, appears to be related to the Subtilisphaera Ecozone and suggests the onset of Tethyan influence in the central South Atlantic, in a restricted to inner-neritic environment. The succeeding Spiniferites community, in the middle part of the section, represents the first significant transgression, probably of eustatic origin. The Cyclonephelium-Exochosphaeridium community, in the upper part of the section, appears to be related to an oceanic event characterized by intermittent dysoxic-anoxic conditions. The uppermost part of the section is dominated by the Spiniferites community, related to a progressive regional transgression and culminating in an open-marine, fully Tethyan environment in the central part of the widening South Atlantic.

Early Cretaceous subsidence of the Naturaliste Plateau defined by a new record of volcaniclastic-rich sequence at IODP Site U1513

“…Circulodinium hystrix/vannophorum has an age range from the Valanginian to the Aptian (Backhouse, 1988) and can be associated with marginal, brackish, coastal, nearshore environments with unstable conditions or high environmental stress (Carvalho et al, 2016).…”

Upper Cretaceous Palynology of the Campos-01 Well, Northern Campos Basin: Paleoenvironmental Inferences

“…However, some species are also found in sediments associated to the nearshore conditions (Hultberg & Malmgren, 1986;Carvalho et al, 2016). The second and third most abundant genera in this association are Hystrichokolpoma and Operculodinium, respectively.…”

“…The Spiniferites are associated with open marine environment (Brinkhuis, 1994;Sluijs et al, 2008;Carvalho et al, 2016). However, some species are also found in sediments associated to the nearshore conditions (Hultberg & Malmgren, 1986;Carvalho et al, 2016).…”

“…However, only few studies (e.g., Arai, 2007;Arai & Viviers, 2013;Carvalho et al, 2016) have correlated dinocyst distribution and ecological characteristics to the environmental changes. Palynological studies of Cretaceous sediments in Campos Basin have shown variations in palynomorphs, especially dinoflagellates, and have been correlated with environmental parameters such as distance from shoreline, diversity, productivity, terrigenous inputs.…”

Cretaceous (Hauterivian–Cenomanian) palaeoceanographic conditions in southeastern Tethys (Matruh Basin, Egypt): Implications for the Cretaceous climate of northeastern Gondwana

“…In addition, dinocyst species diversity in PF-1B assemblages is high (samples 21-37) like those in PF-1A, but is less variable than in PF-1A ( high diversity/low dominance assemblages have been found to increase in basinward shelfal settings of normal marine salinity (e.g., Mutterlose and Harding, 1987;Lister and Batten, 1988;Habib et al, 1992). The increase in the abundance of Oligosphaeridium and Florentinia may represent periodically slightly more offshore/deeper water conditions or the influence of onshore currents re-depositing more offshore taxa (Lister and Batten, 1988;Prauss, 2001Prauss, , 2006Carvalho et al, 2016;Deaf and Tahoun, 2018). Generally, the higher abundance of innermiddle shelf, proximate cysts Pseudoceratium and Circulodinium (Harding, 1986;Brinkhuis, 1994;Deaf and Tahoun, 2018) over the inner shelf cavate cysts Subtilisphaera (Harding, 1986;Lister and Batten, 1988;Deaf and Tahoun, 2018) and the open marine (middle-outer shelf) chorate cysts suggests a proximal middle shelf setting for samples 21-37.…”