Marine or freshwater? Accessing the paleoenvironmental parameters of the Caldas Bed, a key marker bed in the Crato Formation (Araripe Basin, NE Brazil)

Author(s)

Filipe Giovanini Varejão ^[1] ; Victor Ribeiro Silva ; Mario Luis Assine ^[3] ; Lucas Veríssimo Warren ^[4] ; Suzana Aparecida Matos ^[5] ; Mariza Gomes Rodrigues ; Franz Theodor Fürsich ^[7] ; Marcello Guimarães Simões ^[8]

Affiliation

^[1] Universidade Federal do Paraná. Departamento de Geologia. Instituto LAMIR - Brasil

^[3] Universidade Estadual Paulista “Júlio de Mesquita Filho”. Instituto de Geociências e Ciências Exatas. Departamento de Geologia - Brasil

^[4] Universidade Estadual Paulista “Júlio de Mesquita Filho”. Instituto de Geociências e Ciências Exatas. Departamento de Geologia - Brasil

^[5] Universidade Estadual Paulista “Júlio de Mesquita Filho”. Instituto de Biociências - Brasil

^[7] Friedrich-Alexander-Universität Erlangen-Nürnberg. FG Paläoumwelt. GeoZentrum Nordbayern - Alemanha

^[8] Universidade Estadual Paulista “Júlio de Mesquita Filho”. Instituto de Biociências - Brasil

• Document type: Journal article
• Source: BRAZILIAN JOURNAL OF GEOLOGY; v. 51, n. 1 2020-12-21.

Abstract

Abstract The Aptian Crato Formation is world renowned for its well-preserved fossils in microbially-induced laminated limestones, which are regarded as one of the main Cretaceous Konservat-Lagerstätte of the geological record. Detailed stratigraphic investigation and mapping of the up to 90-m-thick Crato Formation at the eastern border of the Araripe Plateau allowed recognition of a regionally persistent fossil-bearing muddy interval, herein defined as the Caldas Bed. At its type locality, it is defined as an up to 2-m-thick coarsening-upward succession of grey/green mudstone and interbedded sandy siltstone and claystone. The 0.85- to 2-m-thick interval was recognized in several localities along the outcrop belt, and it is bounded by sharp, lower (Konservat-Lagerstätte limestone) and upper (sandstone and heterolithic facies) contacts. Despite previous literature data suggesting the presence of marine mollusks, the bed contains freshwater bivalves, small gastropods, spinicaudatans, plant remains, trace fossils, and rare ostracods. The Caldas Bed records benthic paleocommunities representing a short-term isochronous regional freshening event, marked by abrupt changes in sedimentation pattern, bathymetry, salinity, oxygenation and water chemistry. (AU)

• FAPESP's process: 18/01750-7 - Bakevelliidae bivalves of the Romualdo Formation (Alagoas stage, Lower Cretaceous), Araripe Basin, Brazil: paleoenvironmental and paleogeographic significance
• Grantee: Mariza Gomes Rodrigues
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 17/20803-1 - Stratigraphic and Paleoenvironmental Context of the Macroinvertebrate Assemblages of the Romualdo Formation, Cretaceous, Araripe Basin, and its Paleogeographic Implications
• Grantee: Suzana Aparecida Matos da Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/22036-8 - Systematics and paleoecology of the bivalves of the crato formation (Lower Cretaceous), Northeastern Brazil: paleoenvironmental and paleogeographic significance
• Grantee: Victor Ribeiro da Silva
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 14/00519-9 - Centralities of night-time leisure in the city of São Carlos-SP and the interface relations
• Grantee: Tiago Ferreira Lopes Machado
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 16/13214-7 - Multi-proxy approach of the mixed carbonate-siliciclast Crato Formation: sedimentary evolution, paleogeography and tectonics
• Grantee: Filipe Giovanini Varejão
• Support Opportunities: Scholarships in Brazil - Doctorate