Evidence for Late Ordovician glaciation of Al Kufrah Basin, Libya

Heron, Daniel Paul Le; Howard, James P.

doi:10.1016/j.jafrearsci.2010.04.001

Cited by 24 publications

(7 citation statements)

References 30 publications

(43 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The presence of a soft‐sediment striated surface, which is morphologically comparable to those described from the Mamuniyat Formation elsewhere in Libya (e.g. Le Heron & Howard, ; Le Heron et al ., ), implies the shearing of unconsolidated sand by an overriding ice mass (Sutcliffe et al ., ; Le Heron et al ., ). Le Heron et al .…”

Section: Stratigraphy and Sedimentology Of The Jabal Eghei Regionsupporting

confidence: 71%

“…The presence of a soft‐sediment striated surface within the thickly bedded sandstone facies association may testify to the presence of a grounded ice sheet in Jabal Eghei during deposition. The surface bears close resemblance to striated pavements of Late Ordovician age from Morocco, western Libya, Saudi Arabia and South Africa (Le Heron et al ., ), as well as those described from the eastern flank of Al Kufrah Basin at Jabal Azbah (Le Heron & Howard, ). A photograph of a similar striated surface was published by Ghnia et al .…”

Section: Stratigraphy and Sedimentology Of The Jabal Eghei Regionsupporting

confidence: 62%

See 1 more Smart Citation

Early Palaeozoic evolution of Libya: perspectives from Jabal Eghei with implications for hydrocarbon exploration in Al Kufrah Basin

et al. 2014

View full text Add to dashboard Cite

This paper presents new stratigraphic and sedimentological data of the Ordovician, Silurian, and Mesozoic succession exposed on the western flank of Al Kufrah Basin. Field data (logged sections, photographs, palaeocurrent analyses) are presented from the Jabal Eghei region. This region lies ca. 200 km E of the closest stratigraphic tie point at Mourizidie on the eastern flank of the Murzuq Basin. The succession starts with the Hawaz Formation (Middle Ordovician) comprising >100 m of cross-bedded and bioturbated sandstones that are interpreted as deposits of tidal currents in an open shelf setting. The contact between the Hawaz and Mamuniyat formations is an erosional unconformity, incised during advance of Late Ordovician ice sheets towards the NE. The Mamuniyat Formation comprises >150 m of massive and graded sandstones tentatively assigned to the Hirnantian, and contains an intraformational, soft-sediment striated surface that is interpreted to record re-advance of ice sheets over Jabal Eghei. The outcrop section suggests the sandstone would form an excellent reservoir in the subsurface. The Mamuniyat Formation is overlain by the Tanezzuft Formation (uppermost Ordovician-lowermost Silurian). This includes sandy limestone/calcareous sandstone, a Planolites horizon, and then 50 m of interbedded shale, silt and fine-grained, graded and hummocky cross-stratified sandstone recording deposition from both shallow marine turbidity currents and storm flows. A striated pavement in the lower part of this sequence is overlain by calcareous lonestone-bearing intervals (interpreted as ice-rafted debris). These features testify to late phases of glacial advance probably post-dating the regional Hirnantian glacial maximum. The basal Silurian 'hot shale' facies is not developed in this area, probably because late glacial advance suppressed the preservation of organic matter. The upper part of the Tanezzuft Formation is truncated by an unconformity above which palaeosol-bearing fluvial deposits (undifferentiated Mesozoic) occur.

show abstract

Section: Stratigraphy and Sedimentology Of The Jabal Eghei Regionsupporting

confidence: 71%

Section: Stratigraphy and Sedimentology Of The Jabal Eghei Regionsupporting

confidence: 62%

Early Palaeozoic evolution of Libya: perspectives from Jabal Eghei with implications for hydrocarbon exploration in Al Kufrah Basin

et al. 2014

View full text Add to dashboard Cite

show abstract

“…One of the largest mass extinctions of the Phanero zoic took place at the close of the Ordovi cian Period (Sepkoski, 1981;Brenchley et al, 2001;Sheehan, 2001;Bambach et al, 2004), an interval also marked by the development of extensive continental ice sheets on the south polar super continent Gondwana (Hambrey and Harland, 1981;Hambrey, 1985;Ghienne , 2003;Le Heron et al, 2007;Le Heron and Dowdeswell, 2009;Le Heron and Howard, 2010;Loi et al, 2010). This glaciation and the possible Early Silurian glaciation (Caputo and Crowell, 1985;Grahn and Caputo, 1992;Díaz-Martínez and Grahn, 2007) stand out as the only episodes in a 210 m.y.…”

Section: Introductionmentioning

confidence: 99%

Terminal Ordovician carbon isotope stratigraphy and glacioeustatic sea-level change across Anticosti Island (Quebec, Canada)

Jones

Fike

Finnegan

et al. 2011

Geological Society of America Bulletin

View full text Add to dashboard Cite

Globally documented carbon isotope excursions provide time-varying signals that can be used for high-resolution stratigraphic correlation. We report detailed inorganic and organic carbon isotope curves from carbonate rocks of the Ellis Bay and Becscie Formations spanning the Ordovician-Silurian boundary on Anticosti Island, Québec, Canada. Strata of the Anticosti Basin record the development of a storm-dominated tropical carbonate ramp. These strata host the well-known Hirnantian positive carbon isotope excursion, which attains maximum values of ~4.5‰ in carbonate carbon of the Laframboise Member or the Fox Point Member of the Becscie Formation. The excursion also occurs in organic carbon, and δ 13 C carb and δ 13 C org values covary such that no reproducible Δ 13 C (= δ 13 C carb -δ 13 C org ) excursion is observed. The most complete stratigraphic section, at Laframboise Point in the west, shows the characteristic shape of the Hirnantian Stage excursion at the global stratotype section and point (GSSP) for the Hirnantian Stage in China and the Silurian System in Scotland. We therefore suggest that the entire Hirnantian Stage on Anticosti Island is confi ned to the Laframboise and lower Fox Point Members.By documenting discontinuities in the archi tecture of the carbon isotope curve at multiple stratigraphic sections spanning a proximal to distal transect across the sedimentary basin, we are able to reconstruct glacioeustatic sea-level fl uctuations corresponding to maximum glacial conditions asso ciated with the end-Ordovician ice age. The combined litho-and chemostratigraphic approach provides evidence for the diachroneity of the oncolite bed and Becscie limestones; the former transgresses from west to east, and the latter progrades from east to west. The sea-level curve consistent with our sequence-stratigraphic model indicates that glacioeustatic sea-level changes and the positive carbon isotope excursion were not perfectly coupled. Although the start of the isotope excursion and the initial sea-level drawdown were coincident, the peak of the isotope excursion did not occur until after sea level had begun to rise. Carbon isotope values did not return to baseline until well after the Anticosti ramp was refl ooded. The sea-level-δ 13 C carb relationship proposed here is consistent with the "weathering" hypothesis for the origin of the Hirnantian δ 13 C carb excursion.

show abstract

“…Leicester, 2007; Le Heron & Craig, 2008). This unconformity has recently been recognized in the northern and eastern flanks of the Kufra Basin (Le Heron & Howard, 2010; Le Heron et al . 2010).…”

Section: Introductionmentioning

confidence: 78%

“…These data indicate that the graptolite marker bed must have been deposited before the early Aeronian. The graptolite-bearing bed occurs above a glaciogenic unconformity thought to be of Hirnantian age (Le Heron & Howard, 2010). Given the stratophenetic argument that N. kufraensis emerged from the N. angustus lineage in the latest Ordovician, the lowermost shales of the Tanezzuft Formation were deposited at sometime in or after the Hirnantian and before the earliest Aeronian.…”

Section: Biostratigraphic Age Constraints and Deglacial Anoxiamentioning

confidence: 99%

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

et al. 2013

View full text Add to dashboard Cite

-Normalograptus kufraensis sp. nov. occurs as monospecific assemblages in the Tanezzuft Formation at the western margin of the Kufra Basin (Jabal Eghei), southern Libya. These graptolites have parallel-sided rhabdosomes with long, straight virgellae, climacograptid thecae and a full straight median septum. N. kufraensis is intermediate between Ordovician graptolites from the N. angustus (Perner) lineage and the younger sister species N. ajjeri (Legrand) and N. arrikini Legrand. N. kufraensis differs from these taxa as follows: it is broader than N. angustus; it has greater thecal spacing than N. ajjeri or N. arrikini. A table comparing measurements of N. kufraensis with 44 other Normalograptus taxa differentiates it from other members of this morphologically conservative group. Even though N. angustus and N. ajjeri are very long-ranging graptolites, a stratophenetic approach suggests that the specimens from Jabal Eghei may be of late Hirnantian or younger age. The faunal composition and preservation suggests these graptolites occupied the 'cratonic invader' biotope. The stratigraphic succession records deglacial flooding and fluctuating of redox in the Tanezzuft Formation, with the graptolites indicating a short-lived interval of anoxia.

show abstract

Evidence for Late Ordovician glaciation of Al Kufrah Basin, Libya

Cited by 24 publications

References 30 publications

Early Palaeozoic evolution of Libya: perspectives from Jabal Eghei with implications for hydrocarbon exploration in Al Kufrah Basin

Early Palaeozoic evolution of Libya: perspectives from Jabal Eghei with implications for hydrocarbon exploration in Al Kufrah Basin

Terminal Ordovician carbon isotope stratigraphy and glacioeustatic sea-level change across Anticosti Island (Quebec, Canada)

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

Contact Info

Product

Resources

About