Sediment-hosted geothermal systems: Review and first global mapping

What is it about?

Sediment-Hosted Geothermal Systems (SHGSs) are hybrid geological systems, where volcanic and sedimentary domains interact, leading to mixtures of inorganic and organic gases. We find that SHGSs are characterized by: (a) fluids dominated by mantle or decarbonation-methamorphic CO2 (> 50 vol%); (b) considerable amounts of CH4 and heavier hydrocarbons (at least 1.5 vol%, generally up to 30–40 vol%); (c) tectonically active sedimentary basins (back-arc, rift zones and foredeep), generally hosting petroleum fields and within ~300 km from recent or ancient volcanic centers.

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Why is it important?

SHGSs may have implications for energy resource exploration, and global climate change studies. SHGSs can host source rocks with enhanced thermal maturity and a potential development of hydrocarbons in the sedimentary rocks . These hydrocarbon systems may not occur in conventional petroleum system settings, and as such they may not be considered within the standard target areas of petroleum exploration. Therefore, SHGSs can represent frontier resources for natural gas exploration. Moreover, SHGSs can be a significant natural source of greenhouse gas (CO2 and CH4) for the atmosphere.