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Kilometre‐scale sand injectites in the intracratonic Murzuq Basin (South‐west Libya): an igneous trigger?
Author(s) -
MOREAU JULIEN,
GHIENNE JEAN FRANÇOIS,
HURST ANDREW
Publication year - 2012
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.2011.01308.x
Subject(s) - geology , structural basin , outcrop , paleozoic , devonian , paleontology , ordovician , tectonics , intrusion , geomorphology , horizon , geochemistry , physics , astronomy
Mount Telout, situated at the edge of the Murzuq Basin, is a 325 m high conical hill within a circular collapse structure that records 0·5 km 3 of sand intrusion into Silurian shales. Based on a comparison with other similar circular collapse structures around the Murzuq Basin, it is argued that sand injection in the form of pipes occurred during the Devonian. The overpressures triggering the process are inferred to result from a combination of: (i) tectonic uplift at a basin scale that initially focused regional ground water flows; and (ii) igneous intrusion within the sand‐rich Cambrian–Ordovician strata. The palaeorelief buried under the regionally extensive Silurian shales may have locally focused overpressures and localized sand injection at the 1 to 10 km scale. The Mount Telout injected sandbody and related features offer exceptional, seismic‐scale outcrop analogues for sand injections that are often identified in seismic reflection data. Large‐scale sand injections might be essential in petroleum exploration of the North African Lower Palaeozoic basins as they form seal‐bypass systems.