Type Geological formation Coordinates 05º46´S-47º31´W | Primary red sandstone Country Brazil | |
Region Parnaíba River Basin
State of Tocantins | ||
The Corda Formation is a red sandstone geologic formation in the Parnaíba River Basin, in State of Tocantins of Brazil.
Contents
It was formed during the Neoaptian to Eoalbian series of the Early Cretaceous subperiod of the Mesozoic Era.
Fossil sauropod tracks have been reported from the formation.
Origin
The Corda Formation is characterized by deposits of windy deserts and fast flowing freshwater streams. Therefore, fossils are very rare.
Occurrence
This formation outcrops in the central part of the Parnaíba Basin, between the mouth of the Araguaia river in the west the Parnaíba river in the east.
Lithology
The Corda Formation consists largely of red sandstone, with very fine to medium grain size, rich in zeolites and iron oxide. Where whinstones are overlaying fragments of this rock are also present. Typical structures of wind dunes (cross bedding, ripples, and grain flow) are common. This is consistent with deposition in a desert system.