Rubielos de la Cérida impact structure explained

Rubielos de la Cérida impact structure
Confidence:	Largely rejected
Diameter:	Claimed
Age:	Supposedly 30 - 40 Ma
Country:	Spain
District:	Aragon
Municipality:	Teruel

The c. 80 km x 40 km sized Rubielos de la Cérida structure is a claimed impact feature located in Aragon, northeast Spain, north of Teruel purported to have formed during the Upper Eocene or Oligocene (roughly 30 - 40 Mill. years ago). The name is derived from the nearby village of Rubielos de la Cérida. The claim that the structure represents an impact feature is rejected by the majority of scientists, and the mainstream consensus is that the supposed structure is explained by non-impact related tectonic structures, namely the Jiloca-Calatayud graben and the Alfambra-Teruel graben.^[1]

Reception

The origin of the Rubielos de la Cérida structure has been debated, and the mainstream opinion of Spanish geologists is that the structure is not an impact feature.^{[2] [3] [4]} The supposed shock effects are actually tectonic features, the purported impact ejecta are Cenozoic alluvial fans or conglomerates and supposed impact breccias and dike breccias are interpreted as karst features and soil formations. The opposition against the impact origin for Rubielos de la Cérida (and Azuara) has been supported by an analysis and paper (Langenhorst & Deutsch 1996)^[5] rejecting the occurrence of shock metamorphism in Azuara rocks.^{[6] [7]} It is not listed in the Earth Impact Database.

See also

• Azuara impact structure

External links

• Comprehensive report on the Rubielos de la Cérida basin
• Comprehensive report on the Azuara structure
• Jarmo Moilanen's list of impact structures of the world
• The impact breccia page
• The suevite page
• Shatter cones
• EDEIS Expert Database on Earth Impact Structures
• Impact melt page - impact melt rocks
• Shock metamorphism page
• The Azuara - Rubielos de la Cérida controversy
• Understanding the Impact Cratering Process: a Simple Approach

Notes and References

1. Web site: The mid-Tertiary Azuara and Rubielosde la Cérida paired impact structure. Ernstson, K., Claudin, F., Schüssler, U. & Hradil, K. (2002): The mid-Tertiary Azuara and Rubielos de la Cérida paired impact structures (Spain). - Treb. Mus. Geol. Barcelona, 11, 5 - 65.
2. Cortés A. L., Diaz-Martínez E., Sanz-Rubio E., Martínez-Frías J. and Fernández C. (2002) "Cosmic impact versus terrestrial origin of the Azuara structure (Spain): A review." Meteoritics & Planetary Science 37: 875-894.
3. Diaz Martínez, E., Sanz Rubio, E., and Martinez Frias, J (2002): Sedimentary record of impact events in Spain. Geological Society of America. Special Paper 356: 551-562.
4. Díaz-Martínez, E. 2005. Registro geológico de eventos de impacto meteorítico en España: revisión del conocimiento actual y perspectivas de future. [Geological record of meteorite impact events in Spain: review of current knowledge and future perspectives.]. Journal of Iberian Geology 31 (1) 2005: 65-84.
5. Langenhorst F. and Deutsch A. (1996) The Azuara and Rubielos structures, Spain: Twin impact craters or Alpine thrust systems? Lunar and Planetary Science XXVII.
6. Web site: Shock effects (shock metamorphism) in rocks from the Azuara impact structure . https://web.archive.org/web/20110112183405/http://www.impact-structures.com/spain/shock-metamorphism.html . 12 Jan 2011. Shock effects (shock metamorphism) in rocks.
7. Web site: The controversy: The Spanish impact structures and the competing models of an endogenetic origin . https://web.archive.org/web/20031001210652/http://www.impact-structures.com/spain/controversy/controversy.htm . 1 Oct 2003. The controversy: The Spanish impact structures and competing models of an endogenetic origin.