Alna Fm
Period:
Silurian
Age Interval:
Sheinwoodian – Ludfordian, Iq3
Province:
Iraq
Type Locality and Naming
Column: Rutba Uplift (W Iraq)
Synonym:
Lithology and Thickness
Consists of three units, a lower mudstone and siltstone unit, a middle sandstone unit, and an upper black mudstone unit.
Lithology Pattern:
Clayey sandstone
Relationships and Distribution
Lower contact
Regionally, the schematic strat column indicates the next older unit as Akkas Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Tawil Fm
Regional extent
GeoJSON
{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[39.46,32.74],[39.29,32.46],[39.43,32.14],[39.97,32.04],[40.05,32.1],[40.04,32.34],[39.95,32.64],[39.46,32.74]]]]}}
Fossils
Age
Sheinwoodian – Ludfordian
Age Span:
Beginning stage:
Sheinwoodian
Fraction up in beginning stage:
0.5
Beginning date (Ma):
431.78
Ending stage:
Ludfordian
Fraction up in the ending stage:
0.65
Ending date (Ma):
423.53
Depositional setting
Depositional pattern:
Additional Information
Compiler:
From S. Z. Jassim and J. C. Goff, Geology of Iraq, 2006. pg 92, Fig. 8-1: "Stratigraphic correlation of megasequences AP1 to AP5 for Iraq and surrounding countries."