The Lower Devonian succession of the Murzuq Basinossible indicators of eustatic and tectonic controls on sedimentation

Adamson, Keith; Glover, T.; Whittington, R J; Craig, Jonathan

doi:10.1016/b978-044450611-5/50023-4

Cited by 4 publications

(7 citation statements)

References 21 publications

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“…Across the Murzuq Basin, these deposits are sharply overlain unconformably by Devonian sandstones of the Tadrart Formation (Fig. ) (Adamson et al ., ).…”

Section: Stratigraphymentioning

confidence: 97%

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Neoproterozoic–Devonian stratigraphic evolution of the eastern Murzuq Basin, Libya: a tale of tilting in the central Sahara

2012

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The Murzuq Basin is one of the most petroliferous basins of North Africa. Its remote eastern flank has been largely ignored since early reconnaissance work in the 1950s and 1960s. This article presents new stratigraphic and sedimentological data on the Neoproterozoic through Devonian succession from the Mourizidie and Dor el Gussa regions. The Neoproterozoic to Cambrian Mourizidie and Hasawnah formations in the eastern part of the Mourizidie region dip to the east and north-east, resting directly on late Precambrian metasediments and granitoids. These strata record the initial progradation of sand-dominated braidplain systems upon peneplained Precambrian basement. Rhyolite clasts in the Hasawnah Formation may record tectonically driven uplift and unroofing in the southern Tibesti Massif or tectonomagmatic rejuvenation to the south of this massif. In the western part of the Mourizidie region, Late Ordovician through Silurian strata (Mamuniyat and Tanezzuft-Akakus formations) directly overlie late Precambrian metasediments and granitoids, and dip at a low angle towards the west into the Murzuq Basin. Elsewhere at the eastern Murzuq Basin flank, in Dor el Gussa, Late Ordovician glaciogenic sediments rest with angular unconformity upon shallow marine sandstones of Cambrian-Ordovician age. This angular unconformity may also occur in the Mourizidie region and indicates widespread tectonism, either as a result of a Middle-Late Ordovician orogenic event, far-field tectonism related to the opening of the Rheic Ocean along the northern margin of Gondwana or alternatively crustal depression associated with the growth of Late Ordovician ice sheets. Unconformity development was also probably associated with glacial incision. Following ice sheet retreat, isostatic rebound during deglaciation resulted in uplift of tens to hundreds of metres, locally removing all Cambrian and Ordovician formations. Rising sea levels in the Silurian led to deposition of the Tanezzuft Formation on Precambrian basement in the northwestern Mourizidie region.

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“…Across the Murzuq Basin, these deposits are sharply overlain unconformably by Devonian sandstones of the Tadrart Formation (Fig. ) (Adamson et al ., ).…”

Section: Stratigraphymentioning

confidence: 97%

“…Fello et al ., ). Analyses of Devonian (Adamson et al ., ) and Carboniferous (Fröhlich et al ., ) strata have also focused on sedimentological aspects of specific parts of the stratigraphic successions. Studies on the provenance of the sedimentary strata were presented by Meinhold et al .…”

Section: Introductionmentioning

confidence: 99%

Neoproterozoic–Devonian stratigraphic evolution of the eastern Murzuq Basin, Libya: a tale of tilting in the central Sahara

2012

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“…The effects of subsequent tectonic overprint have been minimalized by flattening the isochores to a top Devonian datum, which has been chosen as it is a regionally extensive flooding surface (e.g. Adamson et al 2000). Isochron data, by comparison, give the 'time thickness' of a data interval, such as between two unconformities, to provide information on the stratigraphic thickness between these two surfaces.…”

Section: A Seismic Stratigraphymentioning

confidence: 99%

Interpretation of Late Ordovician glaciogenic reservoirs from 3-D seismic data: an example from the Murzuq Basin, Libya

Heron

2009

Geol. Mag.

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Understanding the recessional behaviour of ancient pre-Cenozoic ice sheets based on seismic reflection studies is generally difficult through scarcity of data. In North Africa, however, hydrocarbon exploration has produced high quality seismic reflection datasets that permit an analysis of the morphology and internal sedimentary architecture of incisions of Late Ordovician age related to the Hirnantian glaciation. Analysis of a high-resolution 3-D seismic dataset covering a small area in western Libya (the N Murzuq Basin) reveals a sharply defined, WNW-ESE-oriented palaeoescarpment, with a higher (cliff-forming) western margin and a lower (basin-forming) eastern margin. The palaeo-escarpment defines the western flank of a sub-basin extending up to 60 km in width, known as the Awbari Trough. The escarpment and the trough are interpreted as the morphological expression of a major unconformity dividing pre-glacial sediments below from Late Ordovician (?Hirnantian) glacially related sediments above. Two hypotheses are considered for the origins of both the escarpment and the Awbari Trough: (1) as a tectonic feature such as a half graben that was active during sedimentation and (2) a glacially related palaeotopography, with the latter interpretation preferred, owing to the lack of evidence for syn-sedimentary fault activity. The width of the Awbari Trough compares to the large-scale cross-shelf troughs in modern high latitude settings, such as the Barents Shelf, produced by ice streams. The Awbari Trough was progressively filled in by gravity flow deposits throughout the course of the glaciation, until the initial incision became filled in with sediments during an overall glacial retreat phase and ceased to influence sedimentation patterns. Glacial re-advance across the basin produced a second unconformity observed in seismic data. Above this unconformity, meltwater processes incised a shallow (∼ 20 m) and wide (∼ 5 km) subglacial tunnel valley. Stabilization of the ice front prior to its ultimate retreat resulted in the deposition of a delta complex prior to the Early Silurian transgression.

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“…Continental facies were deposited in the Kufra Basin (Bellini and Massa, 1980;Turner, 1980;Bellini et al, 1991;Turner, 1991); the Murzuq Basin (Bellini and Massa, 1980;Carniero de Castro et al, 1991;Clark-Lowes and Ward, 1991;Pierobon et al, 1991;Mergl and Massa, 2000;Echikh and Sola, 2000;Adamson et al, 2000); the Ghadames Basin (Belhaj, 1996(Belhaj, , 2000 and the Gargaf Arch (Vos, 1981b). However, offshore marine mudstones were only deposited in Morocco (Vos, 1977;Wendt, 1991).…”

Section: Lst 3: Tadrart (Libya Tunisia) Grès Massif (Algeria) and Rmentioning

confidence: 99%

“…Continental sediments characterise deposition in the Kufra Basin (Bellini and Massa, 1980;Turner, 1980;Bellini et al, 1991;Turner, 1991). Shallow-marine shelf sandstones to offshore marine mudstones occur in the Murzuq Basin (Bellini and Massa, 1980;Carniero de Castro et al, 1991;Clark-Lowes and Ward, 1991;Pierobon et al, 1991;Mergl and Massa, 2000;Adamson et al, 2000); marginal-marine deposits in the Ghadames Basin (Bellini and Massa, 1980;Bracaccia et al, 1991;Belhaj, 2000), and offshore marine mudstones in the Gargaf Arch area (Vos, 1981b), Saharan Platform (Fekirine and Abdallah, 1998), Tunisia (Crossley and McDougal, 1998) and Morocco (Vos, 1977;Wendt, 1991), with offshore mudstones and carbonates in Egypt (Keeley, 1989). Braided fluvial and tidal delta deposits are confined to the Kufra Basin, with shallow-and offshore-marine sediments deposited over the rest of the study area.…”

Section: Tst 3: Zeitoun (Egypt) Tadrart Ouan Kasa (Libya Tunisia)mentioning

confidence: 99%

Second‐order Sequence Stratigraphy of the Palaeozoic of North Africa

Carr¹

2002

Journal of Petroleum Geology

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A synthesis of the sedimentology and sequence stratigraphy of the Palaeozoic succession of North Africa is presented. Two chronostratigraphic correlation panels have been constructed at roughly right angles to each other across North Africa, in WNW-ESE and NNW-SSE orientations. The panels illustrate the way in which sedimentology and hydrocarbon geology vary across the continent through time. The Palaeozoic succession is divided into five second-order sequences (NA 1, Early Cambrian to Late Ordovician; NA 2, Late Ordovician to Late Silurian; NA 3, Devonian; NA 4, Carboniferous; NA 5, Permian), with sequence boundaries, maximum flooding surfaces and systems tracts being defined for NA 1 to NA 4. Palaeogeographic reconstructions for the North African region from the Cambrian to the Carboniferous are illustrated, and a sea-level curve based on the panels and palaeogeographic reconstructions is compared to other published sea-level curves. The proximity of the North African region to the South Pole during the Palaeozoic and its relative tectonic stability suggest that sea-level curves derived from the area should closely reflect Palaeozoic glacio-eustasy. This study may be used to investigate the occurrence of reservoir, seal and source rocks away from areas of data control, and is intended to provide a useful framework for future third-order studies. SECOND-ORDER SEQUENCES WITHIN THE NORTH AFRICAN PALAEOZOICIn this section, each sequence is described in terms of key surfaces and general characteristics; within each sequence, systems tracts have been defined by age, bounding

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The Lower Devonian succession of the Murzuq Basinossible indicators of eustatic and tectonic controls on sedimentation

Cited by 4 publications

References 21 publications

Neoproterozoic–Devonian stratigraphic evolution of the eastern Murzuq Basin, Libya: a tale of tilting in the central Sahara

Neoproterozoic–Devonian stratigraphic evolution of the eastern Murzuq Basin, Libya: a tale of tilting in the central Sahara

Interpretation of Late Ordovician glaciogenic reservoirs from 3-D seismic data: an example from the Murzuq Basin, Libya

Second‐order Sequence Stratigraphy of the Palaeozoic of North Africa

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