Micro-scale dissolution seams mobilise carbon in deep-sea limestones
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Date
2021-08-27
Journal Title
Journal ISSN
Volume Title
Publisher
Springer Nature
Abstract
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
Description
Keywords
Carbon, Limestone, Sea bed, Dissolution, Carbon cycle, Fluorescence, Microscopy, Structural chemical analysis, Electron microscopes, Hydrosphere
Citation
Schrank, C. E., Jones, M. M. W., Kewish, C. M., van Riessen, G. A., Elphick, K. E., Sloss, C. R., Nothdurft, L. D., Webb, G. E., Paterson, D. J., & Regenauer-Lieb, K. (2021). Micro-scale dissolution seams mobilise carbon in deep-sea limestones. Communications Earth & Environment, 2(1), 174. doi:10.1038/s43247-021-00257-w