Orbital tuning for the middle Eocene to early Oligocene Monte Cagnero Section (Central Italy): Paleoenvironmental and paleoclimatic implications

Autor(es)

Kochhann, Marcus V. L. ^[1] ; Savian, Jairo F. ^[2] ; Tori, Flavia ^[3] ; Catanzariti, Rita ^[4] ; Coccioni, Rodolfo ^[5] ; Frontalini, Fabrizio ^[6] ; Jovane, Luigi ^[7] ; Florindo, Fabio ^[8] ; Monechi, Simonetta ^{[3, 9]}

Afiliação do(s) autor(es)

^[1] Univ Fed Rio Grande do Sul, Programa Posgrad Geociencias, Av Bento Goncalves 9500, BR-91501970 Porto Alegre, RS - Brazil

^[2] Univ Fed Rio Grande do Sul, Inst Geociencias, Dept Geol, Av Bento Goncalves 9500, BR-91501970 Porto Alegre, RS - Brazil

^[3] Univ Firenze, Dipartimento Sci Terra, Via Pira 4, I-50121 Florence - Italy

^[4] Consiglio Nazl Ric CNR, Ist Geosci & Georisorse, I-56124 Pisa - Italy

^[5] Univ Urbino Carlo Bo, Campus Sci, I-61029 Urbino - Italy

^[6] Univ Urbino Carlo Bo, Dipartimento Sci Pure & Applicate, Campus Sci, I-61029 Urbino - Italy

^[7] Univ Sao Paulo, Inst Oceanog, Dept Oceanog Fis Quim & Geol, Praca Oceanog 191, BR-05508120 Sao Paulo - Brazil

^[8] Ist Nazl Geofis & Vulcanol, Via Vigna Murata 605, I-00143 Rome - Italy

^[9] Inst Climate Change Solut, I-61040 Frontone - Italy

• Tipo de documento: Artigo Científico
• Fonte: PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY; v. 577, SEP 1 2021.
• Citações Web of Science: 0

Resumo

During the middle Eocene to early Oligocene Earth transitioned from a greenhouse to an icehouse climate state. The interval comprises the Middle Eocene Climatic Optimum (MECO; similar to 40 Ma) and a subsequent long-term cooling trend that culminated in the Eocene-Oligocene transition (EOT; similar to 34 Ma) with the Oi-1 glaciation. Here, we present a refined calcareous nannofossil biostratigraphy and an orbitally tuned age model for the Monte Cagnero (MCA) section spanning the middle Eocene to the early Oligocene (similar to 41 to similar to 33 Ma). Spectral analysis of magnetic susceptibility (MS) data displays strong cyclicities in the orbital frequency band allowing us to tune the identified 405 kyr eccentricity minima in the MS record to their equivalents in the astronomical solution. Our orbitally tuned age model allows us to estimate the position and duration of polarity chrons (C18 to C13) and compare them with other standard and orbitally tuned ages. We were also able to constrain the timing and duration of the MECO event, which coincides with a minimum in the 2.4 Myr and 405 kyr eccentricity cycles. Our study corroborates the previous estimated age for the base of the Rupelian stage (33.9 Ma) and estimates the base of the Priabonian stage in the MCA section to be at 37.4 Ma. Finally, calcareous nannofossils with known paleoenvironmental preferences suggest a gradual shift from oligotrophic to meso-eutrophic conditions with an abrupt change at similar to 36.8 Ma. Besides, nannofossil assemblages suggest that enhanced nutrient availability preceded water cooling at the late Eocene. Altogether, this evidence points to a poorly developed water column stratification prior to the cooling trend. (AU)

• Processo FAPESP: 16/24946-9 - Mudanças do nível do mar e o Sistema Monçônico Global: avaliação através de testemunhos marinhos no Brasil
• Beneficiário: Luigi Jovane
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático