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The Barremian-Aptian boundary in the Poggio le Guaine core (central Italy); evidence for magnetic polarity Chron M0r and Oceanic Anoxic Event 1a

Jairo F. Savian, Ricardo Trindade, Liliane Janikian, Luigi Jovane, Renato Paes de Almeida, Rodolfo Coccioni, Fabrizio Frontalini, Marianna Sideri, Milene Figueiredo, Leonardo R. Tedeschi and Hugh C. Jenkyns
The Barremian-Aptian boundary in the Poggio le Guaine core (central Italy); evidence for magnetic polarity Chron M0r and Oceanic Anoxic Event 1a (in The stratigraphic record of Gubbio; integrated stratigraphy of the Late Cretaceous-Paleogene Umbria-Marche pelagic basin, Marco Menichetti (editor), Rodolfo Coccioni (editor) and Alessandro Montanari (editor))
Special Paper - Geological Society of America (2016) 524: 57-78

Abstract

The Early Cretaceous represents a time interval in the greenhouse world that was characterized by dramatic changes in the paleogeography, paleoceanography, and paleoclimate of the Earth system. Furthermore, a striking, prominent feature of the geomagnetic polarity time scale is the approximately 34 m.y. period of the normal polarity field (Cretaceous Normal Polarity Superchron). Although marine anomalies and paleomagnetic data from deep-sea cores and land sections indicate that a reversed polarity (M0r) with a duration of approximately 0.4 m.y. occurred before the superchron, incomplete exposure, coupled with gaps in sampling due to the presence of marl layers, has limited the identification of M0r in a number of sections. An integrated multidisciplinary investigation of lower Cretaceous sediments at the base of the Poggio le Guaine (PLG) core (Northern Apennines, central Italy) was carried out to identify the Barremian-Aptian contact, which is defined by the M0r lower boundary. Rock magnetic measurements of the studied interval of the PLG core reveal magnetite as the main magnetic carrier. Paleomagnetic results indicate a short interval characterized by reverse polarity. This interval is in the uppermost part of the Hedbergella excelsa planktonic foraminiferal zone and in the upper part of the Chiastozygus litterarius (NC6) calcareous nannofossil zone. Stable carbon (delta (super 13) C) and oxygen (delta (super 18) O) isotopes indicate a chemostratigraphy of the PLG core with the signature of oceanic anoxic event 1a (OAE 1a). The lithological expression of OAE 1a is the organic-rich black shale unit known as the Selli Level. The comparison of our magnetostratigraphic, biostratigraphic, and chemostratigraphic records throughout the Barremian-Aptian boundary with those available from previously investigated oceanic and land-based sites allows recognition of the magnetochron M0r and OAE 1a at PLG for the first time.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 524
Title: The Barremian-Aptian boundary in the Poggio le Guaine core (central Italy); evidence for magnetic polarity Chron M0r and Oceanic Anoxic Event 1a
Title: The stratigraphic record of Gubbio; integrated stratigraphy of the Late Cretaceous-Paleogene Umbria-Marche pelagic basin
Affiliation: Universidade de Sao Paulo, Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Sao Paulo, Brazil
Pages: 57-78
Published: 2016
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 109
Accession Number: 2016-094090
Categories: GeochronologyStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map, 5 tables, strat. cols.
N43°32'60" - N43°32'60", E12°34'60" - E12°34'60"
Secondary Affiliation: Universidade Federal do Rio Grande do Sul, BRA, BrazilUniversidade Federal de Sao Paulo, BRA, BrazilUniversita degli Studi di Urbino "Carlo Bo", ITA, ItalyPetrobras Petroleo Brasileiro, BRA, BrazilUniversity of Oxford, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201646
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