TY - JOUR
T1 - Characterization of primary and secondary magnetite in marine sediment by combining chemical and magnetic unmixing techniques
AU - Ludwig, P.
AU - Egli, R.
AU - Bishop, S.
AU - Chernenko, V.
AU - Frederichs, T.
AU - Rugel, G.
AU - Merchel, S.
AU - Orgeira, M. J.
N1 - Funding Information:
The search for 60 Fe supernova signatures is supported by the German Research Foundation, Grant DFG-Bi1492/1-1. We are grateful to two anonymous reviewers for their constructive comments which helped improve the original manuscript.
PY - 2013/11
Y1 - 2013/11
N2 - 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.
AB - 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.
KW - Citrate-bicarbonate-dithionite extraction
KW - First-order reversal curve
KW - Magnetotactic bacteria and magnetofossils
KW - Pelagic carbonates
KW - Primary and secondary magnetic minerals
KW - Supernova explosion signatures
UR - http://www.scopus.com/inward/record.url?scp=84888839097&partnerID=8YFLogxK
U2 - 10.1016/j.gloplacha.2013.08.018
DO - 10.1016/j.gloplacha.2013.08.018
M3 - Article
AN - SCOPUS:84888839097
SN - 0921-8181
VL - 110
SP - 321
EP - 339
JO - Global and Planetary Change
JF - Global and Planetary Change
ER -
