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

Savian, J.F.; Jovane, Luigi; Frontalini, Fabrizio; Trindade, R. I.; Coccioni, Rodolfo; Bohaty, Steven M; Wilson, Paul A.; Florindo, Fabio; Roberts, Andrew P.; Catanzariti, Rita; Iacoviello, Francesco

doi:10.1016/j.palaeo.2014.08.009

Cited by 42 publications

(46 citation statements)

References 101 publications

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“…The low coercivity component can be interpreted as coarse detrital magnetite (Egli, ; Savian et al, ). Coercivity and DP values for the second component are consistent with the narrow grain size range of biogenic magnetite produced in situ by magnetotactic bacteria (Egli, , ; Jovane et al, ; Kruiver & Passier, ; Roberts et al, ; Savian et al, ). The higher DP and coercivity distribution of this component below 30 and 40 cm may be due to alteration of biogenic magnetite.…”

Section: Resultsmentioning

confidence: 99%

“…Magnetite produced by MTB has specific characteristics in terms of stoichiometry, crystal structure, morphology, size, and spatial organization (Chen et al, ; Egli, ; Kopp & Kirschvink, ; Mann et al, ; Yan et al, ). The magnetic properties of biogenic magnetite have been studied extensively (Chang et al, ; Egli, , 2004b, 2004c; Egli et al, ; Jovane et al, ; Kruiver & Passier, ; Mohamed et al, ; Moskowitz et al, ; Pan, Petersen, Davila, et al, , Pan, Petersen, Winklhofer, et al, ; Roberts et al, ; Savian et al, , ), and a range of techniques exist to recognize and characterize such crystals. Environmental magnetic studies can be a rapid and reliable way to track the spatial distribution of MTB, which have the potential to enable reconstruction of oxygen gradients in natural environments (Chang et al, ), where other proxies or methods of study are less readily applicable.…”

Section: Introductionmentioning

confidence: 99%

“…Magnetite produced by MTB has specific characteristics in terms of stoichiometry, crystal structure, morphology, size, and spatial organization (Chen et al, 2014;Egli, 2004b;Kopp & Kirschvink, 2008;Mann et al, 1984;Yan et al, 2012). The magnetic properties of biogenic magnetite have been studied extensively (Chang et al, 2018;Egli, 2004aEgli, , 2004bEgli, , 2004cEgli et al, 2010;Jovane et al, 2012;Kruiver & Passier, 2001;Mohamed et al, 2011;Moskowitz et al, 1993;Roberts et al, 2011;Savian et al, 2014Savian et al, , 2016, and a range of techniques exist to recognize and characterize such crystals. Environmental magnetic studies can be a rapid and reliable way ©2019.…”

Section: Introductionmentioning

confidence: 99%

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Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

et al. 2019

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Magnetotactic bacteria (MTB) synthesize magnetite and greigite crystals under low oxygen conditions in the water column or uppermost sediment (greigite‐producing bacteria are found below the oxic‐anoxic transition). Dissolved iron and oxygen contents in local environments are known to be limiting factors for the production and preservation of biogenic magnetite. Understanding the processes that link MTB to their living environments is fundamental to reconstructing past chemical variations in the water column and sediment, and for using the magnetic properties of biogenic magnetite as environmental proxy indicators. Previous studies have suggested that the frequently identified biogenic soft (BS) and biogenic hard (BH) magnetite types are associated with equant and more elongated morphologies, respectively, and that their abundance varies in accordance with sedimentary oxygen content, where MTB that produce the BH component live in less oxygenated environments. We test this hypothesis in a high‐resolution integrated environmental magnetic and geochemical study of surface sediments from Mamanguá Ría, SE Brazil. Based on magnetic and pore water profiles, we demonstrate that both the BS and BH components occur within microaerobic environments and that as sediment oxygen content decreases with depth, the BS component disappears before the BH component. With continued burial into the sulfidic diagenetic zone, both components undergo progressive dissolution, but the BH component is more resistant to dissolution than the BS component. Our observations confirm previous inferences about the relative stability of these phases and provide a firmer basis for use of these two types of biogenic magnetite as paleoenvironmental proxies.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

et al. 2019

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“…Global climate proxies indicate warm conditions from the K/Pg boundary until the early Eocene (Zachos et al, 2001(Zachos et al, , 2008, followed by a long-term global cooling trend characterizing the Eocene. However, short-(5-100 kyr) and mid-term episodes (>100 kyr) of warming climate such as the hyperthermals (Lourens et al, 2005;Zachos et al, 2010) and the middle Eocene Climatic Optimum (MECO; Bohaty and Zachos, 2003;Jovane et al, 2007;Savian et al, 2014Savian et al, , 2016 occurred throughout the Eocene. Horizon 2 can be correlated to the strong and important middle Eocene reflector along the BEM, which has probably a direct relation to the MECO event.…”

Section: Discussionmentioning

confidence: 99%

Seismostratigraphy of the Ceará Plateau: Clues to Decipher the Cenozoic Evolution of Brazilian Equatorial Margin

et al. 2016

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“…Biogenic magnetite is now considered to be a major constituent of magnetic mineral assemblages in marine sediments [ Roberts et al ., ; Yamazaki , ; Yamazaki and Ikehara , ; Heslop et al ., ; Yamazaki and Shimono , ; Channell et al ., ]. The abundance of fossil biogenic magnetite (magnetofossils) in sediments can be used in appropriate settings as a proxy for paleoproductivity changes because organic carbon supply to the seafloor may control the population of magnetotactic bacteria [ Roberts et al ., ; Larrasoaña et al ., ; Yamazaki and Ikehara , ; Savian et al ., ; Liu et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Precessional control on ocean productivity in the Western Pacific Warm Pool for the last 400 kyr: Insight from biogenic magnetite

Yamazaki

Horiuchi

2016

Geochem Geophys Geosyst

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Abstracts The Western Pacific Warm Pool plays a significant role in large‐scale atmospheric circulation and global hydrology. We conducted an environmental magnetic study of two late Pleistocene sediment cores from the western equatorial Pacific Ocean offshore of New Guinea in order to better constrain climatic and oceanographic variability, particularly spatiotemporal ocean productivity variations. Magnetic property measurements and transmission electron microscopy reveal that the magnetic mineral assemblages in the studied sediments are a mixture of biogenic and terrigenous magnetite. Variations in the acid soluble sediment component, interpreted as carbonate content, and the proportion of biogenic to terrigenous magnetite estimated from the ratio of anhysteretic to saturation remanent magnetizations are in‐phase with northern hemisphere summer insolation variations. We interpret that ocean productivity increased during insolation maxima, which induced higher populations of magnetotactic bacteria through a larger nutrient supply to the seafloor. This interpretation assumes that magnetotactic bacterial populations are greatest in sediments just below the seafloor. Precessional frequencies in magnetic mineral concentration variations are suppressed after correction for carbonate dilution, whereas cyclic changes with a ∼100 kyr periodicity remain in carbonate‐free magnetic concentration variations. Glacial/interglacial changes in bottom water currents may have influenced transportation and deposition of magnetic minerals. We demonstrate the usefulness of magnetic proxies for paleoceanographic studies, particularly of biogenic magnetite proxies for estimating paleoproductivity variations.

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

Cited by 42 publications

References 101 publications

Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

Seismostratigraphy of the Ceará Plateau: Clues to Decipher the Cenozoic Evolution of Brazilian Equatorial Margin

Precessional control on ocean productivity in the Western Pacific Warm Pool for the last 400 kyr: Insight from biogenic magnetite

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