Microstructure and fluid flow in the vicinity of basin bounding faults in rifts – the Dombjerg Fault, NE Greenland rift system

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.jsg.2021.104463. This is version 2 of this Preprint.

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Authors

Eric Salomon, Atle Rotevatn , Thomas Berg Kristensen , Sten-Andreas Grundvåg, Gijs Allard Henstra 

Abstract

Faults commonly form loci for high fluid flux in sedimentary basins, where fluids, rocks and deformation processes frequently interact. Here, we elucidate the interaction of fluid flow, diagenesis and deformation near basin-bounding faults in sedimentary basins through a study in the vicinity (0-3.5 km) of the Dombjerg Fault in the NE Greenland rift system. Due to fault-controlled fluid circulation, fault-proximal syn-rift clastics underwent pervasive calcite cementation, whereas uncemented clastics at some distance from the fault remained highly porous and friable. Correspondingly, two distinct deformation regimes developed to accommodate continued deformation: discrete brittle fractures formed in calcite cemented rocks, whereas cataclastic deformation bands formed in uncemented deposits.

We show that low-permeable deformation bands forming in highly porous rocks were associated with localized host rock alteration, and chemical reduction of porosity along bands. In rocks with cementation-induced low porosity, brittle fractures created new pathways for fluids, but were subsequently filled with calcite. Occasionally, veins comprise multiple generations of microcrystalline calcite, likely precipitated from rapidly super-saturated fluids injected into the fractures. This suggests cemented deposits sealed uncemented compartments, where fluid overpressure developed. We conclude that compartmentalized flow regimes may form in fault-bounded basins, which has wide implications for assessments of potential carbon storage, hydrocarbon, groundwater, and geothermal sites.

DOI

https://doi.org/10.31223/X5FP57

Subjects

Earth Sciences, Geology, Sedimentology, Tectonics and Structure

Keywords

fracturing, fluid flow, syn-rift, fault evolution, structural diagenesis, cementation

Dates

Published: 2021-06-17 10:24

Last Updated: 2021-10-19 13:56

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License

CC BY Attribution 4.0 International

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Conflict of interest statement:
None

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