Akakus Sandstone Fm
Period:
Silurian
Age Interval:
Ludfordian – Pridoli, Lb2
Province:
Libya
Type Locality and Naming
Column: Fezzan Basin
Synonym: Acacus Sandstone Fm
Lithology and Thickness
Fine to medium-grained silty sandstone, thinly bedded, and frequently cross-bedded with ripple marks and flute marks. The top of the unit contains a ferruginous sandstone horizon which contains stromatolitic structures.
Lithology Pattern:
Fine-grained sandstone
Relationships and Distribution
Lower contact
Regionally, the schematic strat column indicates the next older unit as Tanzuft Shale Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Tadrart Sandstone Fm
Regional extent
GeoJSON
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Fossils
Trace fossils include trilobite burrows.
Age
Ludfordian – Pridoli. USGS Chart places this formation in the Upper Silurian, in the Ludlovian stage.
Age Span:
Beginning stage:
Ludfordian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
425.01
Ending stage:
Pridoli
Fraction up in the ending stage:
1.0
Ending date (Ma):
419.00
Depositional setting
Depositional environment ranges from fluvial to shallow marine with tidal bars.
Depositional pattern:
Additional Information
Compiler:
Chart derived from: USGS Correlation Chart and Columnar Section for Rocks in Libya, 1963. Descriptions from: Hallet, Don: Petroleum Geology of Libya, 2002.