Isalo Gr
Type Locality and Naming
Morondava Basin and Majunga Basin (Madagascar). Named for regions in Madagascar. It represents the major Late Triassic to Early Jurassic depositional sequence within the Malagasy rift basins. It is often subdivided into units such as Isalo I and Isalo II. Includes in Stormberg Gr in Morondava Basin (Madagascar)
Synonym:
Lithology and Thickness
The group is characterized largely by coarse clastic sequences, predominantly fluvial conglomerates and sandstones.
Relationships and Distribution
Lower contact
The Isalo Group (specifically the medial Isalo II in the Morondava Basin) possesses a marked basal unconformity, overstepping older Karoo strata directly onto the Precambrian basement. Regionally, it rests above the Upper Sakamena Gr.
Upper contact
Conformably to unconformably succeeded by transgressive marine Liassic (Early Jurassic) deposits.
Regional extent
Found within the Karoo-aged rift basins of Madagascar, specifically the Morondava Basin in the south and the correlated Majunga Basin to the north. Stormberg Gr equivalent in Madagascar.
GeoJSON
Fossils
Age
Depositional setting
Fluvial environments with marginal marine influences.
Additional Information
In the Majunga Basin to the north, Isalo I appears to be the Stormberg Gr-equivalent unit, whereas in the Morondava Basin, Isalo II is considered the equivalent.