Browsing by Author "Elphick, KE"

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    Micro-scale dissolution seams mobilise carbon in deep-sea limestones
    (Springer Nature, 2021-08-27) Schrank, CE; Jones, MMW; Kewish, CM; van Riessen, GA; Elphick, KE; Sloss, CR; Nothdurft, LD; Webb, GE; Paterson, DJ; Regenauer-Lieb, K
    Measuring the amount of carbon captured in deep-sea limestones is fundamental to understanding the long-term carbon cycle because pelagic limestones represent Earth’s largest carbon sink since the mid-Mesozoic. However, their contribution to the long-term carbon cycle is poorly quantified. Here, we use X-ray fluorescence and scanning X-ray diffraction microscopy for high-resolution chemical and structural analysis of pelagic limestone from the Paleocene Kaiwhata Formation in New Zealand. We identify densely packed diagenetic micro-dissolution seams that are invisible to light and electron-beam microscopes in most cases. Mass-balance calculations indicate that individual seams remove ~50% of the calcite mud matrix while their bulk-sample carbon loss adds up to ~10%. The liberated carbon is trapped in situ as calcite cement or returned to the ocean during physical compaction or soft-sediment deformation. We suggest micro-dissolution structures may play an important role in the long-term carbon cycle by modulating carbon exchange between the geosphere and hydrosphere. © 2024 The Authors - Open Access - CC-BY 4.0