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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Source of the climate signal recorded by magnetic susceptibility variations in Indian Ocean sediments.
AU - Hounslow, Mark W.
AU - Maher, Barbara A.
N1 - Copyright (1999) American Geophysical Union.
PY - 1999
Y1 - 1999
N2 - The origins of magnetic susceptibility variations in deep-sea sediments from the Indian Ocean (ODP Leg 117) have been examined to identify the specific connections between climate shifts and sediment magnetic properties. In a previous study, the magnetic susceptibility variations in ODP Hole 722B were identified as an outstanding proxy paleoceanographic record, despite evidence of post-depositional loss of magnetic minerals through reductive diagenesis. This paradox is addressed by assessing the contributions of ferrimagnetic detrital iron oxides, bacterial magnetosomes, and paramagnetic detrital Fe-silicate minerals to the magnetic susceptibility signal. In addition to detailed magnetic analyses, mineralogical, morphological and grain size data have been obtained from representative magnetic extracts. For Hole 722B, magnetic responses to climate change result from: i) fluctuations in the volume magnetic susceptibility, which is primarily controlled by carbonate dilution; ii) a ferrimagnetic signal which is restricted to the upper 7 mbsf and which largely reflects source area aridity; and iii) a paramagnetic susceptibility record below 7 mbsf, which is coincident in frequency with variations in lithogenic grain size.
AB - The origins of magnetic susceptibility variations in deep-sea sediments from the Indian Ocean (ODP Leg 117) have been examined to identify the specific connections between climate shifts and sediment magnetic properties. In a previous study, the magnetic susceptibility variations in ODP Hole 722B were identified as an outstanding proxy paleoceanographic record, despite evidence of post-depositional loss of magnetic minerals through reductive diagenesis. This paradox is addressed by assessing the contributions of ferrimagnetic detrital iron oxides, bacterial magnetosomes, and paramagnetic detrital Fe-silicate minerals to the magnetic susceptibility signal. In addition to detailed magnetic analyses, mineralogical, morphological and grain size data have been obtained from representative magnetic extracts. For Hole 722B, magnetic responses to climate change result from: i) fluctuations in the volume magnetic susceptibility, which is primarily controlled by carbonate dilution; ii) a ferrimagnetic signal which is restricted to the upper 7 mbsf and which largely reflects source area aridity; and iii) a paramagnetic susceptibility record below 7 mbsf, which is coincident in frequency with variations in lithogenic grain size.
KW - Magnetic records
KW - climate change
KW - deep sea sediments
KW - magnetic susceptibility
KW - Indian Ocean
U2 - 10.1029/1998JB900085
DO - 10.1029/1998JB900085
M3 - Journal article
VL - 104
SP - 5047
EP - 5061
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
ER -