Multi-proxy assessment of coral reef formation and biotic-abiotic diversity in an urban coastal reef ecosystem in northeastern Brazil.

Coral reefs are habitats with high animal and mineral diversity and are subject to both climate change and anthropogenic impacts. This article presents novel and relevant data on the Seixas coral reef environment's geological, sedimentological, mineralogical, and biotic aspects in Paraíba State, northeastern Brazil. The aim of this study is to evaluate the processes of reef formation and the diversity of coral reef species in urban coastal environments in northeastern Brazil using a multi-proxy approach. Materials and methods employed to analyze the formation and diversity of biotic and abiotic species include (a) bathymetric survey, (b) collection of sedimentological, mineralogical, and granulometric data, (c) geological and stratigraphic determination, and (d) identification of biotic and abiotic species. Mineralogical slide results reveal that the Seixas Reef is a recent biogenic coral-algal carbonate formation associated with coastline evolution, high coastal sedimentation, and changes that occurred alongside sea-level rise (Holocene-Quaternary period). The diversity results indicate that benthic organism settlement occurred on a consolidated arenite base, with the fauna undergoing continuous succession processes. It can be concluded that this coral reef is highly vulnerable due to the material of its formation and comprises subsectors with high diversity (fore reef) and others with low diversity (reef top), which are affected by both anthropogenic and natural factors. Studies of this nature can contribute to understanding the evolution of coastal reefs, as their proximity to the continent makes them more vulnerable, and they experience direct physical impacts from fishing and tourist activities.

3D gravity modelling of areas under the aptian lakes in the Jatobá basin and Tucano Norte sub-basin - Negra and Tonã hills.

Due to structural similarities and the possibility of connection between the two Aptian paleolakes in the Jatobá Basin and the Tucano Norte Sub-basin in North-eastern Brazil, the influence of the architecture of the crystalline basement under these lacustrine sedimentary rocks was analysed using gravimetric data near the faulted edges of the basins where the paleolakes are located. The Negra (Jatobá Basin) and Tonã (Tucano Norte Sub-basin) Hills are mainly sedimentary deposits of Aptian age and are linked to the post-rift I tectonic sequence. Aiming at the study of reservoirs analogous to pre-salt reservoirs, the gravimetric data were processed and interpreted to define the structural framework of the basin regions around these hills. Depth maps and density models were generated that could be analysed from various 3D perspectives, and the behaviour of the crystalline basement below these sedimentary sequences was investigated. In addition to the identification of horsts and semi-grabens that influenced the current relief pattern, the modelling showed that the Aptian paleolake sedimentary rocks of the Negra Hill are in the Ibimirim Low, which is approximately 2,900 m deep, while in the Tonã Hill, the sedimentary rocks are in the Salgado do Melão Low, which is approximately 5,100 m deep.

New marine data and age accuracy of the Romualdo Formation, Araripe Basin, Brazil.

A combined biostratigraphic and palaeoecological study of foraminifera, ostracodes and microfacies was carried out on the Aptian in the Sítio Sobradinho section of the Araripe Basin, northeast Brazil. The analysed section represents a deepening-upward sequence with mid-ramp shoal and outer ramp to basin facies associations on a mixed siliciclastic-carbonate marine ramp. The analysed rocks are dominated by Early Cretaceous planktic foraminifera (Hedbergella aptiana, H. praelippa, H. sigali, Blesfucuiana cf. cumulus, Microhedbergella miniglobularis, Gorbachikella cf. kugleri, Pseudoguembelitria blakenosensis, Globigerinelloides clavatus, Globigerinelloides aff. aptiensis, Gubkinella sp. and Loeblichella sp.). Ostracoda fauna is composed mainly of Pattersoncypris crepata and Pattersoncypris micropapillosa. The occurrence of P. crepata associated with the Aptian planktic foraminifera demonstrates the potential of this ostracode species to date this interval. The planktic foraminifera from the upper Aptian (Microhedbergella miniglobularis Zone) of the Araripe Basin show characteristical Tethyan affinities.