Intertrappean Beds


The Intertrappean Beds are a Late Cretaceous and early Paleogene geologic unit in India. These beds are found as interbeds between Deccan Traps layers, including the slightly older Lameta Formation. They consist a number of different subgroups and formations, and span the Cretaceous–Paleogene boundary.
Many mostly fragmentary fossils, especially of small vertebrates, are known from the formation. Indeterminate theropod and pterosaur remains have been recovered from the formation, as well as dinosaur eggs. The mammal genera Deccanolestes, Sahnitherium, Bharattherium, Indoclemensia, Indotriconodon and Kharmerungulatum have been recovered from several localities. The Early Eocene-aged Bamanbor locality in Gujarat preserves articulated freshwater fish specimens. A rich plant flora is known from the formation.

Stratigraphy

Although often thought of as a contemporaneous unit that was formed in a single rapid eruption event, more studies that date the age of the volcanic beds indicate that the Deccan Traps did not erupt all at once. Instead, different portions appear to have erupted during different periods of time. This means that the Intertrappean Beds are best understood as a group of different volcanic-associate formations of varying ages.

Divisions

Kale et al divided the group into the following provinces:Sahyadri Group or Western Province Satpura Group or Central ProvinceMalwa Group Amarkantak Group or Mandla Province
Mittal et al divided the group into the following provinces:Western Ghats-Central Indian Volcanic Province Saurhastra-Kutchh Province Malwa Plateau Province
  • '''Mandla Lobe Province'''

Formations

Chemostratigraphic definition

Kale et al divided the group as follows. Subgroups/formations are classified based on oldest to youngest.Wai Subgroup
  • * Desur Formation
  • * Panhala Formation
  • * Mahabaleshwar Formation
  • * Ambenali Formation
  • * Poladpur FormationLonavala Subgroup
  • * Bushe Formation
  • * Khandala FormationKalsubai Subgroup
  • * Bhimashankar Formation
  • * Thakurwadi Formation
  • * Neral Formation
  • * Igatpuri Formation
  • * '''Jawhar Formation'''

Lithostratigraphic definition

Kale et al divided the group as follows. Subgroups/formations are classified based on oldest to youngest.Sahyadri '''Group:
  • * Bombay Subgroup
  • ** Borivali Formation
  • ** Elephanta Formation
  • * Khandala Subgroup
  • ** Mahabaleshwar Formation
  • ** Purandargarh Formation
  • ** Diveghat Formation
  • ** Karla Formation
  • ** Indrayani Formation
  • * Kalsubai Subgroup
  • ** Upper Ratangarh Formation
  • ** Lower Ratangarh Formation
  • ** Salher FormationSatpura Group:
  • * Karanja Formation
  • * Buldhana Formation
  • * Chikli Formation
  • * Ajanta Formation
  • * Upper Ratangarh Formation
  • * Karanja Formation
  • * Buldana Formation
  • * Chikli Formation Malwa Group:
  • * Singarchori Formation
  • * Bargonda Formation
  • * Indore Formation
  • * Kankaria-Pirukheri Formation
  • * Kalisindh Formation
  • * Mandleshwar Formation
  • * Gaganwara Formation Amarkantak Group:
  • * Kuleru Formation
  • * Khamla/Kampla Formation
  • * Amarwara Formation
  • * Multai Formation
  • * Linga Formation
  • * Pipardehi Formation
  • * Dhuma Formation
  • * Mandla Formation
Within the newly defined Saurhastra Group, the following divisions were found by Patel & Shah :Ninama Basin:
  • * Ninama Limestone
  • * Sukhbhadar Formation Chotila Basin:
  • * Bamanbor Formation
  • * Chotila Chert
  • * Rangpar Formation'''

Paleobiota