Santa Marta - Hypervelocity Impact Crater

Alternate Names
Local Language
Coordinates 10° 10' 12" S; 45° 13' 48" W
Notes
  1. Located in SE portion of Piaui State, ~30 km N of the town of Corrente.
Country Brazil
Region Piaui
Date Confirmed 2014
Notes
  1. Confirmed based on the presence of shatter cones and abundant PDFs in quartz (De Oliveira et al., 2014).
Buried? No
Drilled? No
Target Type Sedimentary
Notes
  1. The Santa Marta impact structure is located in the Urucuia Group of the Sanfranciscan Basin which is comprised of sandstones, conglomeratic sandstones, and pelites and has a Cretaceous age (De Oliveira et al., 2014).
Sub-Type Conglomerate, Sandstone, Shale
Apparent Crater Diameter (km) 10 km
Age (Ma) <100
Notes :
  1. Impact is younger than the 66-100 Ma Cretaceous rocks the impact structure is located in (De Oliveira et al., 2014). *Minimum age poorly constrained by probable Pleistocene glaciation which eroded some of crater

Method :
  1. Stratigraphy
Impactor Type Unknown

Advanced Data Fields

Notes

Erosion
3
  1. Reasonably well-preserved compared to older structures in Brazil found in similar target rocks. Raised rim is preserved (De Oliveira et al., 2014).
Final Rim Diameter
Unknown
Apparent Rim Diameter
10 km
  1. Almost circular shape 10 km in diameter (De Oliveira et al., 2014).
Rim Reliability Index
2
  1. Complex crater with raised rim of ~150 m and an off-centre central elevated plateau ~3.2 km wide. SU estimated at 700 m (De Oliveira et al., 2014).
Crater Morphology
Complex
Central Uplift Diameter
3.2km
Central Uplift Height
Unknown
Uplift Reliability Index
3
Structural Uplift
700 m
Thickness of Seds
Target Age
Mesozoic
Marine
No
Impactor Type
Other Shock Metamorphism
Feather features
  1. Feather features (FF) are notable in samples from shatter cones (De Oliveira et al., 2014).
Shatter Cones
Yes
  1. Shatter cones have been identified in sandstones from the central elevated plateau (De Oliveira et al., 2014).
Planar Fractures
Yes
  1. Frequently found in sandstone samples (De Oliveira et al., 2014).
Planar Deformation Features
Yes
  1. Multiple sets of PDFs found in quartz grains (De Oliveira et al., 2014).
Diaplectic Glass
No
Coesite
No
Stisovite
No
Crater Fill
LB
  1. Polymict and monomict breccias are scattered throughout the impact structure. There is a 50 m thick layer of polymict breccia near the centre. Other polymict breccias occur along the crater rim in outcrops or loose blocks. Monomict breccias are also found in the central uplift area and rim of structure (De Oliveira et al., 2014). Polymict and monomict lithic breccias also occur as dykes in the central uplift. Both have a fine-grained matrix with poorly-sorted clasts (De Oliveira et al., 2017).
Proximal Ejecta
LB
Distal Ejecta
Dykes
LB
Volume of Melt
Depth of Melting

References

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G J G Oliveira, M A R Vasconcelos, Alvaro P Crósta, W U Reimold, A M Góes, A Kowitz (2014) Shatter cones and planar deformation features confirm Santa Marta in Piauí State, Brazil, as an impact structure, Meteoritics and Planetary Science 49(10), p. 1915-1928, url, doi:10.1111/maps.12368

G J G Oliveira, M A C Chamani, A M Góes, Alvaro P Crósta, M A R Vasconcelos, W U Reimold (2017) Geological investigation of the central portion of the Santa Marta impact structure, Piauí State, Brazil, Brazilian Journal of Geology 47(4), p. 673-692, doi:10.1590/2317-4889201720160095

E F Ferreira, M A R Vasconcelos, J C Batista, A Santos-Matos, Alvaro P Crósta, S Sena, A O Alves (2019) Geoelectric signatute of the Santa Marta impact structure, Brazil, Large Meteorite Impacts and Planetary Evolution VI, p. 5031, url

G J G Oliveira, M A R Vasconcelos, Alvaro P Crósta, F Sena (2019) Gravity forward modelling of the Santa Maria impact structure, LPI Contributions, p. 5028, url