Environmental magnetic implications of magnetofossil occurrence during the Middle Eocene Climatic Optimum (MECO) in pelagic sediments from the equatorial Indian Ocean

Author(s)

Savian, Jairo F. ; Jovane, Luigi ; Giorgioni, Martino ; Iacoviello, Francesco ; Rodelli, Daniel ; Roberts, Andrew P. ; Chang, Liao ; Florindo, Fabio ; Sprovieri, Mario

• Document type: Journal article
• Source: PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY; v. 441, p. 11-pg., 2016-01-01.

Abstract

Magnetic properties of pelagic marine sediments that record the Middle Eocene Climatic Optimum (MECO) at similar to 40 Ma provide information about major environmental changes. The main variations observed during this transient warming event reflect a bacterial magnetofossil signal, but the cause of the linkage between bacterial production and climate remains unclear. We present an environmental magnetic study of middle Eocene deep-sea sediments from the northern edge of Madingley Rise (Ocean Drilling Program Hole 711A, equatorial Indian Ocean) to investigate the origin of the increased magnetic mineral concentration concomitant with subchron C18n.2n, which corresponds to the MECO interval in ODP Hole 711A. This magnetic mineral peak also coincides with a change in lithofacies from calcareous nannofossils to radiolarian ooze, and a slight increase in clay concentration. Magnetite is the main magnetic mineral in the MECO sediments, which occurs as magnetically non-interacting single domain biogenic particles. The increased magnetic mineral concentration across the MECO event is likely to have been caused by increased eolian iron fertilization. This is interpreted to have given rise to increased surface ocean productivity, where increased delivery of iron and nutrients to the seafloor enhanced magnetotactic bacterial populations during the MECO event. (C) 2015 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 12/15995-5 - Stable isotope geochemistry as main tool to unravel Eocene-Oligocene paleoclimate and paleoceanography
• Grantee: Martino Giorgioni
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• 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