Quiricó Formation

The Quirico Formation is a lithostratigraphic unit ( formation ) of sedimentary rocks from the Lower Cretaceous of Brazil. It belongs to Areado group, a group of Sanfranciscana Basin. The formation is known for numerous fossils, such as the remains of the sauropod dinosaur Tapuiasaurus.

Stratigraphic division and classification

The Quirico lineup is the average of the three formations of Areado group. Below the formation follows the Abaeté lineup, above follows the Três Barras - formation. The Areado group belongs to Sanfranciscana Basin, a vast sedimentary basin that extends to a length of about 1100 km in north-south direction in the central Brazil. This basin is interpreted as a grave breach, which is caused by the same tensile forces, which also led to the opening of the southern Atlantic Ocean.

Description

The sediments of the formation were probably deposited within a lacustrine shallow lake with a high evaporation rate, and then the relationship between quartz and calcium points. The rocks are mainly to mudstone, siltstone and limestone, but also layers of sandstone. The thickness of the formation is up to 100 meters. The time of the deposit can be dated to the Aptian.

Fossil content

From the formation 15 non-marine species of ostracods were registered. Fish of the formation close Laeliichthys and Dastilbe with a. Significant is the discovery of the Titanosauriers Tapuiasaurus, which includes a nearly complete skull with bone next to the rest of the skeleton - the only found in South America Titanosaurier Skull.