(Table 1) Types of giant magnetofossils in ODP holes


Autoria(s): Chang, Liao; Roberts, Andrew P; Williams, Wyn; Fitz Gerald, John D; Larrasoaña, Juan C; Jovane, Luigi; Muxworthy, A R
Cobertura

MEDIAN LATITUDE: -48.169425 * MEDIAN LONGITUDE: 57.459750 * SOUTH-BOUND LATITUDE: -64.517000 * WEST-BOUND LONGITUDE: 3.100400 * NORTH-BOUND LATITUDE: -2.742700 * EAST-BOUND LONGITUDE: 82.787800 * DATE/TIME START: 1987-01-18T12:30:00 * DATE/TIME END: 1988-01-17T05:00:00 * MINIMUM DEPTH, sediment/rock: 35.01 m * MAXIMUM DEPTH, sediment/rock: 285.63 m

Data(s)

19/06/2012

Resumo

Magnetotactic bacteria biomineralize magnetic minerals with precisely controlled size, morphology, and stoichiometry. These cosmopolitan bacteria are widely observed in aquatic environments. If preserved after burial, the inorganic remains of magnetotactic bacteria act as magnetofossils that record ancient geomagnetic field variations. They also have potential to provide paleoenvironmental information. In contrast to conventional magnetofossils, giant magnetofossils (most likely produced by eukaryotic organisms) have only been reported once before from Paleocene-Eocene Thermal Maximum (PETM; 55.8 Ma) sediments on the New Jersey coastal plain. Here, using transmission electron microscopic observations, we present evidence for abundant giant magnetofossils, including previously reported elongated prisms and spindles, and new giant bullet-shaped magnetite crystals, in the Southern Ocean near Antarctica, not only during the PETM, but also shortly before and after the PETM. Moreover, we have discovered giant bullet-shaped magnetite crystals from the equatorial Indian Ocean during the Mid-Eocene Climatic Optimum (~40 Ma). Our results indicate a more widespread geographic, environmental, and temporal distribution of giant magnetofossils in the geological record with a link to "hyperthermal" events. Enhanced global weathering during hyperthermals, and expanded suboxic diagenetic environments, probably provided more bioavailable iron that enabled biomineralization of giant magnetofossils. Our micromagnetic modelling indicates the presence of magnetic multi-domain (i.e., not ideal for navigation) and single domain (i.e., ideal for navigation) structures in the giant magnetite particles depending on their size, morphology and spatial arrangement. Different giant magnetite crystal morphologies appear to have had different biological functions, including magnetotaxis and other non-navigational purposes. Our observations suggest that hyperthermals provided ideal conditions for giant magnetofossils, and that these organisms were globally distributed. Much more work is needed to understand the interplay between magnetofossil morphology, climate, nutrient availability, and environmental variability.

Formato

text/tab-separated-values, 18 data points

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.815860

doi:10.1594/PANGAEA.815860

Idioma(s)

en

Publicador

PANGAEA

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Chang, Liao; Roberts, Andrew P; Williams, Wyn; Fitz Gerald, John D; Larrasoaña, Juan C; Jovane, Luigi; Muxworthy, A R (2012): Giant magnetofossils and hyperthermal events. Earth and Planetary Science Letters, 351-352, 258-269, doi:10.1016/j.epsl.2012.07.031

Palavras-Chave #113-689D; 115-711A; 119-738B; 119-738C; DEPTH, sediment/rock; DRILL; Drilling/drill rig; Event label; Fossils; Indian Ocean; Joides Resolution; Leg113; Leg115; Leg119; Ocean Drilling Program; ODP; ODP sample designation; Period; Sample code/label; South Atlantic Ocean; South Indian Ridge, South Indian Ocean
Tipo

Dataset