Characterization of primary and secondary magnetite in marine sediment by combining chemical and magnetic unmixing techniques

We present a novel technique for quantitative unmixing of primary and secondary ferrimagnetic minerals in sediments. Hysteresis and high-resolution first-order reversal curve (FORC) measurements are performed on sediment samples before and after digestion in a citrate-bicarbonate-dithionite (CBD) so...

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Detalles Bibliográficos
Autores principales: Ludwig, P., Egli, R., Bishop, S., Chernenko, V., Frederichs, T., Rugel, G., Merchel, S., Orgeira, M.J.
Formato: JOUR
Materias:
Citrate-bicarbonate-dithionite extraction
First-order reversal curve
Magnetotactic bacteria and magnetofossils
Pelagic carbonates
Primary and secondary magnetic minerals
Supernova explosion signatures
First-order reversal curves
Magnetic minerals
Magnetotactic Bacteria
Supernova explosion
Chemical detection
Extraction
Iron oxides
Magnetic hysteresis
Magnetic variables measurement
Magnetism
Minerals
Numerical methods
Submarine geology
Sediments
bacterium
bicarbonate
carbonate
dilution
explosion
iron oxide
magnetite
measurement method
mineral
optimization
quantitative analysis
sediment analysis
sediment chemistry
Bacteria (microorganisms)
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_09218181_v110_n_p321_Ludwig
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:We present a novel technique for quantitative unmixing of primary and secondary ferrimagnetic minerals in sediments. Hysteresis and high-resolution first-order reversal curve (FORC) measurements are performed on sediment samples before and after digestion in a citrate-bicarbonate-dithionite (CBD) solution optimized for maximum selective extraction of secondary fine-grained iron oxides. The difference between magnetic measurements of untreated and CBD-treated sample materials is used to calculate the original magnetic signature of CBD-extractable minerals. A combination of selective chemical extraction and magnetic measurements suited for the detection of single-domain particles provides a cross-check between chemical and magnetic unmixing of primary and secondary iron oxides and resolves the non-uniqueness problem of numerical unmixing methods. A quantitative magnetic characterization of secondary ferrimagnetic minerals in a magnetofossil-rich pelagic carbonate is presented for the first time. It can be used for calibration of recently developed fast magnetic unmixing techniques. CBD-based Fe extraction from sediments with minimal clastic and/or aeolian inputs, such as pelagic carbonates, is particularly suited for the search for cosmogenic 60Fe signatures from supernova explosions, because 60Fe dilution by dissolved primary Fe-bearing minerals is minimized. © 2013 Elsevier B.V.

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