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Tanezzuft Formation

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Journal Article

A unique new genus of Acritarcha (organic-walled microphytoplankton) from the Tanezzuft Formation (Silurian) of Libya Free

Gordon D. Wood, Ali O. Tekbali
Journal: Palynology
Published: 01 October 1987
Palynology (1987) 11 (1): 107–112.
Add to Citation Manager for A unique new genus of Acritarcha (organic-walled microphytoplankton) from the <span class="search-highlight">Tanezzuft</span> <span class="search-highlight">Formation</span> (Silurian) of Libya
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Newly recognized glacial features within the Tanezzuft Formation of Jabal Eghei. The stratigraphic position of these features is shown in Figure 4. (a) Soft-sediment striated surface, comprising streamlined ridges and grooves similar to those described elsewhere in Al Kufrah Basin within the Mamuniyat Formation (e.g. Le Heron &amp; Howard 2010; Le Heron et al. 2010). (b) Circular concretions overgrowing and crosscutting the striations allow the hypothesis that the grooves are aeolian to readily be dismissed. (c) Further detail of striated surface, showing local evidence for crosscutting striations. (d) Micritic lonestone ‘floating’ within a siltstone bed, tentatively interpreted as a dropstone. Pencil 5 cm long.

Newly recognized glacial features within the Tanezzuft Formation of Jabal E... Available to Purchase

Published: 01 March 2013
Fig. 6. Newly recognized glacial features within the Tanezzuft Formation of Jabal Eghei. The stratigraphic position of these features is shown in Figure 4 . ( a ) Soft-sediment striated surface, comprising streamlined ridges and grooves similar to those described elsewhere in Al Kufrah Basin
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Figure 3.

Shelly fossils from the Tanezzuft Formation in Jabal Eghei, western Kufra B... Available to Purchase

Published: 11 February 2013
Figure 3. Shelly fossils from the Tanezzuft Formation in Jabal Eghei, western Kufra Basin. (a) Brachiopod similar to ? Eocoelia X.50191.16. (b) Orthocone, X.50191.17.
Journal Article

Did lingering ice sheets moderate anoxia in the Early Palaeozoic of Libya? Available to Purchase

Daniel Paul Le Heron, Guido Meinhold, Alex Page, Andrew Whitham
Published: 01 March 2013
Journal of the Geological Society (2013) 170 (2): 327–339.
DOI: https://doi.org/10.1144/jgs2012-108
...Fig. 6. Newly recognized glacial features within the Tanezzuft Formation of Jabal Eghei. The stratigraphic position of these features is shown in Figure 4 . ( a ) Soft-sediment striated surface, comprising streamlined ridges and grooves similar to those described elsewhere in Al Kufrah Basin...
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Journal Article

Normalograptus kufraensis , a new species of graptolite from the western margin of the Kufra Basin, Libya Available to Purchase

ALEX PAGE, GUIDO MEINHOLD, DANIEL P. LE HERON, MOHAMED ELGADRY
Published: 11 February 2013
Geological Magazine (2013) 150 (4): 743–755.
DOI: https://doi.org/10.1017/S0016756812000787
...Figure 3. Shelly fossils from the Tanezzuft Formation in Jabal Eghei, western Kufra Basin. (a) Brachiopod similar to ? Eocoelia X.50191.16. (b) Orthocone, X.50191.17. ...
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View PDF for article title, Normalograptus kufraensis , a new species of graptolite from the western margin of the Kufra Basin, Libya
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Measured section straddling the Mamuniyat and Tanezzuft formations and the ‘Nubian Sandstone’ in Jabal Eghei. The curve to the right of the logged section shows gamma-ray values obtained using a GF-InstrumentsTM gamma-ray spectrometer on the outcrop, for 3 min count intervals. The U content is commonly taken as a direct and linear proxy for former total organic carbon enrichment (TOC) (e.g. Lüning &amp; Kolonic 2003; Lüning et al. 2003). The curve does not illustrate that proxy TOC values were elevated at or near the base of the Tanezzuft Formation, as is observed elsewhere in North Africa, such as in the Ghat area of SW Libya (Lüning et al. 2003). A simple interpretation (high versus low) of relative sea level, ice and anoxia is also shown. This relative sea-level curve takes into account the progressive upsection loss of hummocky cross-stratification and increase in mud content, compatible with a deepening trend. Ice presence is interpreted on the basis of soft-sediment striae and/or lonestones and manganese oxide concretions. Anoxia is inferred on the basis of faunal preservation in the graptolite assemblage (Page et al. 2013), with more oxic conditions indicated by the presence of bioturbation and manganese nodules.

Measured section straddling the Mamuniyat and Tanezzuft formations and the ... Available to Purchase

Published: 01 March 2013
Fig. 4. Measured section straddling the Mamuniyat and Tanezzuft formations and the ‘Nubian Sandstone’ in Jabal Eghei. The curve to the right of the logged section shows gamma-ray values obtained using a GF-Instruments TM gamma-ray spectrometer on the outcrop, for 3 min count intervals. The U
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Chronostratigraphy of the studied succession on Jabal Eghei, where four stratigraphic units are recognized. These comprise, in ascending stratigraphic order, the Hawaz, Mamuniyat and Tanezzuft formations and the Mesozoic sandstone (‘Nubian Sandstone’). Age constraints on the Hawaz Formation and ‘Nubian Sandstone’ are limited, but lithostratigraphic comparisons coupled with fossil occurrences, including wood fragments in the latter unit, allow Middle Ordovician and Jurassic ages to be assigned respectively (e.g. Bellini et al. 1991). The Mamuniyat Formation similarly is ill constrained in Jabal Eghei, whereas the Tanezzuft Formation contains graptolites of Hirnantian–Rhuddanian affinity (Page et al. 2013).

Chronostratigraphy of the studied succession on Jabal Eghei, where four str... Available to Purchase

Published: 01 March 2013
Fig. 2. Chronostratigraphy of the studied succession on Jabal Eghei, where four stratigraphic units are recognized. These comprise, in ascending stratigraphic order, the Hawaz, Mamuniyat and Tanezzuft formations and the Mesozoic sandstone (‘Nubian Sandstone’). Age constraints on the Hawaz
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Basal sandy carbonate facies association. (a) Relationship between the topmost part of the Mamuniyat Formation and the Tanezzuft Formation in Jabal Eghei. The basal sandy carbonate facies association fills in hollows on the topmost surface of the Mamuniyat Formation sandstones beneath. This contact is clearly marked on the measured section in Figure 4, which encompasses all strata visible in this photograph. The Tanezzuft Formation forms the generally recessive topography in the middle distance to background, which is capped disconformably by the ‘Nubian Sandstone’ of probable Jurassic age (see Fig. 2 for chronostratigraphy). (b) Bioturbated, quartz-bearing grainstone. (c) Mottled grainstone to floatstone with clearly visible crinoid ossicles among the shell fragments. Pencil 5 cm long.

Basal sandy carbonate facies association. ( a ) Relationship between the to... Available to Purchase

Published: 01 March 2013
Fig. 5. Basal sandy carbonate facies association. ( a ) Relationship between the topmost part of the Mamuniyat Formation and the Tanezzuft Formation in Jabal Eghei. The basal sandy carbonate facies association fills in hollows on the topmost surface of the Mamuniyat Formation sandstones beneath
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Model illustrating the envisaged environmental setting of Jabal Eghei during the deposition of the lower part of the Tanezzuft Formation. Of note is (1) the presence of tidewater ice sheets in a marine basin (accounting for both the striated surface and the occurrence of lonestones that are interpreted as ice-rafted debris) and (2) the formation of MnO2 concretions by influx of glacial meltwaters. The presence of tidewater ice sheets is argued to preclude the development of anoxia in this shallow marine setting, hence restricting the preservation potential of organic material on the sea floor. The lack of U enrichment in the Tanezzuft Formation, when used as a proxy for former TOC values in mudrocks, suggests that organically enriched sediments were not deposited at Jabal Eghei.

Model illustrating the envisaged environmental setting of Jabal Eghei durin... Available to Purchase

Published: 01 March 2013
Fig. 9. Model illustrating the envisaged environmental setting of Jabal Eghei during the deposition of the lower part of the Tanezzuft Formation. Of note is (1) the presence of tidewater ice sheets in a marine basin (accounting for both the striated surface and the occurrence of lonestones
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Figure 4.

Photomicrographs of Normalograptus kufraensis sp. nov. from the ... Available to Purchase

Published: 11 February 2013
Figure 4. Photomicrographs of Normalograptus kufraensis sp. nov. from the graptolite-bearing bed of the Tanezzuft Formation in Jabal Eghei, western Kufra Basin. Specimen numbers: (a) X.50191.10, (b) X.50191.6b, (c) X.50191.6a, (d) X.50191.13. Scale bar
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Photomicrograph and camera lucida drawing of the late Hirnantian or rhuddanian graptolite Normalograptus kufraensisPage et al. (2013) preserved as a part-pyritised carbonaceous compresssion in the graptolite-bearing bed of the Tanezzuft Formation at Jabal Eghei, western Al Kufrah Basin. Specimen CAM SM X.50191.6a. Scale bar = 1 mm.

Photomicrograph and camera lucida drawing of the late Hirnantian or rhuddan... Available to Purchase

Published: 01 March 2013
Fig. 8. Photomicrograph and camera lucida drawing of the late Hirnantian or rhuddanian graptolite Normalograptus kufraensis Page et al . (2013) preserved as a part-pyritised carbonaceous compresssion in the graptolite-bearing bed of the Tanezzuft Formation at Jabal Eghei, western Al Kufrah
Journal Article

Silurian palynomorphs from the Tanezzuft and Acacus formations, Tripolitania, North Africa Available to Purchase

John B. Richardson, N. Ioannides
Published: 01 July 1973
Micropaleontology (1973) 19 (3): 257–307.
View PDF for article title, Silurian palynomorphs from the <span class="search-highlight">Tanezzuft</span> and Acacus <span class="search-highlight">formations</span>, Tripolitania, North Africa
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Lithostratigraphy and spectral gamma-ray data for section Ghat-3, located 10 km north of Ghat. The basal part of the Tanezzuft Formation is characterised by a 12-m thick interval enriched in uranium, interpreted here as representing the lower Silurian hot shale. Notably, uranium-values do not exceed 20 ppm, compared to peak values of 50 ppm in sections Ghat-2 and Ghat-7.

Lithostratigraphy and spectral gamma-ray data for section Ghat-3, located 1... Open Access

Published: 01 July 2006
Figure 9: Lithostratigraphy and spectral gamma-ray data for section Ghat-3, located 10 km north of Ghat. The basal part of the Tanezzuft Formation is characterised by a 12-m thick interval enriched in uranium, interpreted here as representing the lower Silurian hot shale. Notably, uranium-values
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Figure 5.

Camera lucida drawings of Normalograptus kufraensis sp. nov. from ... Available to Purchase

Published: 11 February 2013
Figure 5. Camera lucida drawings of Normalograptus kufraensis sp. nov. from the graptolite-bearing bed of the Tanezzuft Formation in Jabal Eghei, western Kufra Basin. Specimen numbers: (a) X.50191.6a, (b) X.50191.3c, holotype, (c) X.50191.1, (d) X
Journal Article

Identification of early Llandovery (Silurian) anoxic palaeo-depressions at the western margin of the Murzuq Basin (southwest Libya), based on gamma-ray spectrometry in surface exposures Open Access

Nuri Fello, Sebastian Lüning, Petr Štorch, Jonathan Redfern
Journal: GeoArabia
Publisher: Gulf Petrolink
Published: 01 July 2006
GeoArabia (2006) 11 (3): 101–118.
DOI: https://doi.org/10.2113/geoarabia1103101
...Figure 9: Lithostratigraphy and spectral gamma-ray data for section Ghat-3, located 10 km north of Ghat. The basal part of the Tanezzuft Formation is characterised by a 12-m thick interval enriched in uranium, interpreted here as representing the lower Silurian hot shale. Notably, uranium-values...
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Ordovician-Silurian contact exposed in section Ghat-6 (a) and Ghat-7 (b) (see Figure 2 for location map). The vehicles stand on sandstones of the upper Ordovician Mamuniyat Formation, while the hills are formed by the basal part of the Silurian Tanezzuft shales. In section Ghat-7 (b) the exposed shales are capped by a volcanic rock unit. (c) Typical red and green colours of the Silurian hot shale in the Ghat outcrop belt (section Ghat-3). (d) Close-up of the contact between Ordovician Mamuniyat Formation sandstones and Silurian Tanezzuft shales in section Ghat-3.

Ordovician-Silurian contact exposed in section Ghat-6 (a) and Ghat-7 (b) (s... Open Access

Published: 01 July 2006
Figure 7: Ordovician-Silurian contact exposed in section Ghat-6 (a) and Ghat-7 (b) (see Figure 2 for location map). The vehicles stand on sandstones of the upper Ordovician Mamuniyat Formation, while the hills are formed by the basal part of the Silurian Tanezzuft shales. In section Ghat-7 (b
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Total gamma-ray log of well E1-NC174. Latest Ordovician-early Silurian Tanezzuft Shale Formation with the basal radioactive, organic-rich ‘hot’ shale, overlying Ordovician sandstones of the Memouni at Formation (modified after Lüning et al., 2000).

Total gamma-ray log of well E1-NC174. Latest Ordovician-early Silurian Tane... Open Access

Published: 01 April 2003
Figure 2: Total gamma-ray log of well E1-NC174. Latest Ordovician-early Silurian Tanezzuft Shale Formation with the basal radioactive, organic-rich ‘hot’ shale, overlying Ordovician sandstones of the Memouni at Formation (modified after Lüning et al., 2000).
Journal Article

Petroleum generation and migration in the Ghadames Basin, north Africa: A two-dimensional basin-modeling study Available to Purchase

Ruth Underdown, Jonathan Redfern
Journal: AAPG Bulletin
Published: 01 January 2008
AAPG Bulletin (2008) 92 (1): 53–76.
DOI: https://doi.org/10.1306/08130706032
... conditions continued to persist farther north ( Van de Weerd and Ware, 1994 ). The Early Silurian included a major postglacial transgressive episode that peaked during the Wenlockian, with deposition of thick, laterally continuous marine mudstones (Tanezzuft Formation). Subsequent regression...
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Satellite image of sections Ghat-5 to 8 in the northern and southern parts of the study area (see Figure 2 for location map). The Silurian Tanezzuft Shale in the Ghat outcrop belt is part of an eastward-dipping Palaeozoic unit and forms a valley that lies between harder Cambrian-Ordovician sandstones to the west and Silurian sandstones (Akakus Formation) to the east. Satellite images courtesy Nasa Applied Sciences Directorate (https://zulu.ssc.nasa.gov/mrsid/).

Satellite image of sections Ghat-5 to 8 in the northern and southern parts ... Open Access

Published: 01 July 2006
Figure 3: Satellite image of sections Ghat-5 to 8 in the northern and southern parts of the study area (see Figure 2 for location map). The Silurian Tanezzuft Shale in the Ghat outcrop belt is part of an eastward-dipping Palaeozoic unit and forms a valley that lies between harder Cambrian
Book Chapter

Biostratigraphy, chemostratigraphy and thermal maturity of the A1-NC198 exploration well in the Kufra Basin, SE Libya Available to Purchase

Author(s)
S. Schäfer, G. Johannson, P. Barnard, E. Brooker, T. Pearce, N. Miles, S. Lüning
Book: Petroleum Geology: From Mature Basins to New Frontiers – Proceedings of the 7th Petroleum Geology Conference
Series: Geological Society, London, Petroleum Geology Conference Series
Publisher: Geological Society of London
Published: 01 January 2010
DOI: 10.1144/0070761
EISBN: 9781862394131
... of the Silurian Tanezzuft Formation in well A1-NC198. GR in API units. The study was based on 71 cuttings samples, mostly claystones, sampled throughout the entire well section. The analysis is based on counts of 200 palyno-specimens per sample, using 10 µm sieved preparations. The rest of the slide...
Abstract
View PDF for content titled, Biostratigraphy, chemostratigraphy and thermal maturity of the A1-NC198 exploration well in the Kufra Basin, SE Libya
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Abstract The A1-NC198 exploration well was drilled in the Kufra Basin in 2007 by RWE Dea and represented only the third well in a large, 400 000 km 2 frontier basin. Despite being dry and lacking any hydrocarbon shows, the well provides important data to improve the understanding of the regional petroleum play. In the 1980s and 1990s the basin's prospectivity was questioned largely because of supposed (1) lack of structuration, (2) lack of source rock and (3) thermal immaturity at Silurian level. Following a series of academic and industry studies over the past 10 years, these assertions can no longer be upheld. The analysis of available seismic has proven the existence of Murzuq-style fault blocks as well as late Ordovician glacial erosional relict buried hills, potentially forming suitable structural and stratigraphic traps. The presence of hot shale in the Kufra Basin is evidenced by typical seismic onlaps of strong amplitude reflectors at base Silurian levels, shallow drilling results and outcrop spectral gamma-ray evidence. A spore colouration study of A1-NC198 cuttings indicates a deep oil window maturity for the Silurian, implying potential oil generation in the basin if suitable Silurian source rocks exist. The stratigraphy of the A1-NC198 succession was analysed by means of biostratigraphy and chemostratigraphy, which form the basis for improved well correlations within the basin.