Microbialite fields developed in a protected rocky coastline: The shallow carbonate ramp of the Aptian Romualdo Formation (Araripe Basin, NE Brazil)

Varejão FG, Fürsich F, Warren LV, Matos SA, Rodrigues MG, Assine ML, Sales AM, Simões MG (2019)

Publication Type: Journal article

Publication year: 2019

Journal

Sedimentary Geology Elsevier

Book Volume: 389

Pages Range: 103-120

DOI: 10.1016/j.sedgeo.2019.06.003

Abstract

The Aptian Romualdo Formation is a siliciclastic-dominated sedimentary unit recording the last marine ingression within the Cretaceous interior basins of northeastern Brazil. At the western margin of the Araripe Basin, rocks of the Romualdo Formation are mainly represented by carbonates resting abruptly over the Proterozoic crystalline basement. Detailed mapping and stratigraphic analysis revealed two stromatolite fields that were described and discussed for the first time. Several bioherms, biostromes and isolated stromatolites characterized by distinct microbialite morphologies associated with echinoid-rich strata have been identified, suggesting that hypersalinity, water depth and hydraulic conditions were the main factors controlling stromatolite morphogenesis. A cm-thick amalgamated bivalve rudstone, resting directly on the basement and representing a shell concentration formed above the fair-weather wave base was also recorded. Based on the regional distribution of the stromatolite types and associated sedimentary facies, we interpret the depositional environment as a local low-gradient carbonate ramp deepening to the east. Our data robustly indicated that the western rocky shorelines of the Araripe Basin during the Aptian were populated by microbial mats and stromatolites in a condition analogous to the modern world-famous Hamelin Pool, Shark Bay, Western Australia. Finally, the development of stromatolites and echinoid-bearing microbialites at the western margin of the basin may be correlated with the formation of bakevelliid- and cassiopid-rich shell beds in the upper part of the Romualdo Formation at the eastern margin.

Authors with CRIS profile

Franz Fürsich

Involved external institutions

São Paulo State University / Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP) BR Brazil (BR) Universidade Regional do Cariri BR Brazil (BR)

How to cite

APA:

Varejão, F.G., Fürsich, F., Warren, L.V., Matos, S.A., Rodrigues, M.G., Assine, M.L.,... Simões, M.G. (2019). Microbialite fields developed in a protected rocky coastline: The shallow carbonate ramp of the Aptian Romualdo Formation (Araripe Basin, NE Brazil). Sedimentary Geology, 389, 103-120. https://dx.doi.org/10.1016/j.sedgeo.2019.06.003

MLA:

Varejão, F. G., et al. "Microbialite fields developed in a protected rocky coastline: The shallow carbonate ramp of the Aptian Romualdo Formation (Araripe Basin, NE Brazil)." Sedimentary Geology 389 (2019): 103-120.

BibTeX: Download