Diagenesis of magnetic minerals at the Southwest Pacific DSDP Site 277

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Ohneiser, C.
Tapia Orellana, Claudio
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NEW ZEALAND JOURNAL OF GEOLOGY AND GEOPHYSICS,Vol.63,250-261,2020
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Abstract
We present a paleomagnetic and rock magnetic record from a 465.2 m long drill core recovered at DSDP Site 277 in the Southwest Pacific. Our study sought to construct a magnetostratigraphy and thus enable further paleoenvironmental work on this sedimentary succession. Magnetic remanence measurements revealed a stable magnetisation in the upper 34.8 m and lower 58.7 m of the core. However, between 34.8 and 397.5 m sediments are very weakly magnetised, do not carry a stable magnetisation, and rock magnetic analyses revealed a lack of remanence carrying minerals in this interval. We suggest that during the period spanning Paleocene to Oligocene sufficiently high organic matter (reagents) accumulation resulted in complete reduction and dissolution of ferri/ferromagnetic grains.
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