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Carbonate alteration of dolerite intruding coal seams: Natural
carbon sequestration during fossil fuel combustion?
Reginald T Mathivha 1 , J. Vogeli 2,3 , D. Reid 4
1. Department of Geological Sciences, University of Cape Town, South Africa, mthreg003@uct.ac.za
2. Centre for Minerals Research, Department of Chemical Engineering, University of Cape Town,
vgljac001@uct.ac.za
3. Department of Geological Sciences, University of Cape Town, South Africa, vgljac001@uct.ac.za
4. Department of Geological Sciences, University of Cape Town, South Africa, david.reid@uct.ac.za
ABSTRACT
Recent investigations of Karoo dolerite intrusions into coal seams have revealed the operation of what seems to be
a natural carbon sequestration process perhaps significant in our understanding of industrial methods designed to
curb the buildup of greenhouse gases in the atmosphere.
Significant carbonation of the dolerite intrusions in the vicinity of coal points to redox reactions driven by
magmatic temperatures, abundant fluids and geological time scales. A principal aim of the current study is
determine whether the carbonates are derived from reactions involving olivine, pyroxenes and feldspars that
constitute the original magmatic assemblage. An insight to these reactions could aid in devising possible industrial
processes that could be applied.
Acid leaching and gasimetry analysis have been done in order to determine the amount of CO2 in the samples.
Optical microscopy, QEMSCAN, XRD and EMP techniques has been used to determine the textural relations,
carbonate - silicate interactions, mineral structure and compositional patterns.
While it is clear that Karoo dolerite has the potential to absorb significant carbon dioxide (25-35%) given the right
circumstances and environment, alternative but mineralogically similar reservoir materials are abundantly available
in the form of mine tailings.
KEYWORDS: Dolerite Dyke, carbon sequestration
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