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GEOREF RECORD

Geobiological and diagenetic insights from Malvinokaffric Devonian biota (Chapada Group, Parana Basin, Brazil); paleobiological and paleoenvironmental implications

Bruno Becker-Kerber, Gabriel Ladeira Oses, Jessica Fleury Curado, Marcia de Almeida Rizzutto, Isaac Daniel Rudnitzki, Guilherme Raffaeli Romero, Silvio Yuji Onary-Alves, Victoria Giopato Benini, Douglas Galante, Fabio Rodrigues, Pedro Victor Buck, Elidiane Cipriano Rangel, Renato Pirani Ghilardi and Mirian Liza Alves Forancelli Pacheco
Geobiological and diagenetic insights from Malvinokaffric Devonian biota (Chapada Group, Parana Basin, Brazil); paleobiological and paleoenvironmental implications
Palaios (April 2017) 32 (4): 238-249

Abstract

This study tests the presence of differential preservation in the Devonian Malvinokaffric fauna from the Chapada Group (Parana Basin, Brazil). Results of EDXRF, EDS, Raman Spectroscopy, and petrographic analyses show differential preservation of shells that were originally calcite as hematite and goethite fossils, while organisms with original calcium phosphate shells tend to be preserved inside phosphatic concretions. Both preservation types are commonly associated with pseudoframboids, while calcium sulfate minerals are commonly associated with hematized fossils. From this evidence, a diagenetic model for these fossils is proposed. The model includes an early diagenetic phase (characterized by anaerobic sulfate reduction and precipitation of pyrite and carbonate-fluorapatite) and a second, near-surface chemical weathering phase (characterized by the oxidation of pyrite and precipitation of iron oxyhydroxides and calcium sulfates). Acidic conditions in both phases may account for the dissolution of less stable minerals compared to calcium phosphate. It is considered that this model may assist in understanding other similarly preserved biotas, as well as enhancing understanding of the taphonomic overprint that may occur within this important and endemic Devonian biota.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 32
Serial Issue: 4
Title: Geobiological and diagenetic insights from Malvinokaffric Devonian biota (Chapada Group, Parana Basin, Brazil); paleobiological and paleoenvironmental implications
Affiliation: Universidade Federal de Sao Carlos, Programa de Pos-graduacao em Ecologia e Recursos Naturais, Sao Carlos, Brazil
Pages: 238-249
Published: 201704
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 56
Accession Number: 2017-041925
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., 2 tables, geol. sketch map
S18°55'00" - S18°55'00", W54°51'00" - W54°51'00"
Secondary Affiliation: Universidade de Sao Paulo, BRA, BrazilCentro Universitario da Fundacao Educacional Inaciana, BRA, BrazilUniversidade Federal do Para, BRA, BrazilBrazilian Center for Research in Energy and Materials, BRA, BrazilUniversidade Estadual Paulista Julio de Mesquita Filho, BRA, Brazil
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201723
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