Enhanced primary productivity and magnetotactic bacterial production in response to middle Eocene warming in the Neo-Tethys Ocean

Author(s):Show less -

Savian, Jairo F. ^[1] ; Jovane, Luigi ^[2] ; Frontalini, Fabrizio ^[3] ; Trindade, Ricardo I. F. ^[4] ; Coccioni, Rodolfo ^[3] ; Bohaty, Steven M. ^[5] ; Wilson, Paul A. ^[5] ; Florindo, Fabio ^[6] ; Roberts, Andrew P. ^[7] ; Catanzariti, Rita ^[8] ; Iacoviello, Francesco ^[2]

Affiliation

^[1] Univ Fed Rio Grande do Sul, Inst Geociencias, Dept Geol, BR-91501970 Porto Alegre, RS - Brazil

^[2] Univ Sao Paulo, Inst Oceanog, Dept Oceanog Fis, BR-05508120 Sao Paulo - Brazil

^[3] Univ Urbino Carlo Bo, Dipartimento Sci Terra Vita & Ambiente, I-61029 Urbino - Italy

^[4] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Geofis, BR-05508090 Sao Paulo - Brazil

^[5] Univ Southampton, Natl Oceanog Ctr, Southampton SO14 3ZH, Hants - England

^[6] Ist Nazl Geofis & Vulcanol, I-00143 Rome - Italy

^[7] Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200 - Australia

^[8] CNR, Ist Geosci & Georisorse, I-56124 Pisa - Italy

• Document type: Journal article
• Source: PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY; v. 414, p. 32-45, NOV 15 2014.
• Web of Science Citations: 13

Abstract

Earth's climate experienced a warming event known as the Middle Eocene Climatic Optimum (MECO) at similar to 40 Ma, which was an abrupt reversal of a long-term Eocene cooling trend. This event is characterized in the deep Southern, Atlantic, Pacific and Indian Oceans by a distinct negative delta O-18 excursion over 500 kyr. We report results of high-resolution paleontological, geochemical, and rock magnetic investigations of the Neo-Tethyan Monte Cagnero (MCA) section (northeastern Apennines, Italy), which can be correlated on the basis of magneto- and biostratigraphic results to the MECO event recorded in deep-sea sections. In the MCA section, an interval with a relative increase in eutrophic nannofossil taxa (and decreased abundances of oligotrophic taxa) spans the culmination of the MECO warming and its aftermath and coincides with a positive carbon isotope excursion, and a peak in magnetite and hematite/goethite concentration. The magnetite peak reflects the appearance of putative magnetofossils, while the hematite/goethite apex is attributed to an enhanced detrital mineral contribution, likely as aeolian dust transported from the continent adjacent to the Neo-Tethys Ocean during a drier, more seasonal climate during the peak MECO warming. Based on our new geochemical, paleontological and magnetic records, the MECO warming peak and its immediate aftermath are interpreted as a period of high primary productivity. Sea-surface iron fertilization is inferred to have stimulated high phytoplankton productivity, increasing organic carbon export to the seafloor and promoting enhanced biomineralization of magnetotactic bacteria, which are preserved as putative magnetofossils during the warmest periods of the MECO event in the MCA section. Together with previous studies, our work reinforces the connection between hyperthermal climatic events and the occurrence (or increased abundance) of putative magnetofossils in the sedimentary record. (C) 2014 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 11/22018-3 - Primary productivity in oceans studying magnetotactic bacteria in sediments
• Grantee: Luigi Jovane
• Support Opportunities: Research Program on Global Climate Change - Young Investigators
• FAPESP's process: 12/18304-3 - Environmental and climatic evolution of the Amazon River and the Brazilian northern margin using clay minerals
• Grantee: Francesco Iacoviello
• Support Opportunities: Scholarships in Brazil - Post-Doctoral