# Azuara impact structure

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Azuara structure Morphological signature of the Azuara structure taken from the digital map of Spain, 1:250,000 Impact crater/structure Confidence Unlikely Diameter Supposedly ~30 km (19 mi) Age 32 to 40 Ma Late Eocene or Early Oligocene Exposed Yes Drilled No Location Coordinates 41°11′N 0°53′W / 41.18°N 0.88°W / 41.18; -0.88[1] Country Spain State Aragon Province Zaragoza Province Municipality Azuara Location of the crater in Spain

The **Azuara structure** is a structural feature of about 30 kilometres (19 mi) diameter,[1] located in northeastern Spain, roughly 50 kilometres (31 mi) south of [Zaragoza](/source/Zaragoza).[2] The name is attributed to the small town of [Azuara](/source/Azuara) located near the center of the structure. It has been subject to controversial, generally rejected claims that it represents an [impact feature](/source/Impact_structure). It was formerly listed in the [Earth Impact Database](/source/Earth_Impact_Database), but was subsequently removed.

## History

The first claims of an [impact](/source/Impact_event) origin was given by Wolfgang Hammann as early as 1980, and the first field work was done by [Johannes Fiebag](https://de.wikipedia.org/wiki/Johannes_Fiebag) in the early eighties. In 1985, Ernstson et al.[3] published the purported occurrence of [shock metamorphism](/source/Shock_metamorphism).

## Reception

Mainstream scientific opinion rejects the Azuara structure as being of impact origin, with the shock effects being [tectonic](/source/Tectonics) features, the supposed impact ejecta (Pelarda Formation) actually being [Quaternary](/source/Quaternary) [alluvial fans](/source/Alluvial_fans) and supposed impact breccias and dike breccias are generally interpreted as [karst](/source/Karst_topography) features and soil formations.[4] The opposition against the impact origin for Azuara has been supported by an analysis and paper (Langenhorst & Deutsch 1996) rejecting the occurrence of shock metamorphism in Azuara rocks.[5] Based on this paper and analysis, Azuara was removed from the Canadian [Impact Data Base](/source/Earth_Impact_Database) when its management changed to the University of New Brunswick.[6]

## See also

- [Rubielos de la Cérida impact structure](/source/Rubielos_de_la_C%C3%A9rida_impact_structure)

## References

1. ^ [***a***](#cite_ref-Mikheeva2017_1-0) [***b***](#cite_ref-Mikheeva2017_1-1) Mikheeva, 2017

1. **[^](#cite_ref-AzuaraMikheeva_2-0)** [Azuara](http://labmpg.sscc.ru/a.html)

1. **[^](#cite_ref-Ernstson1_3-0)** Ernstson, K.; Hammann, W.; Fiebag, J.; Graup, G. (1985). "Evidence of an impact origin for the Azuara structure (Spain)". *Earth and Planetary Science Letters*. **74** (4): 361–370. [Bibcode](/source/Bibcode_(identifier)):[1985E&PSL..74..361E](https://ui.adsabs.harvard.edu/abs/1985E&PSL..74..361E). [doi](/source/Doi_(identifier)):[10.1016/S0012-821X(85)80008-X](https://doi.org/10.1016%2FS0012-821X%2885%2980008-X).

1. **[^](#cite_ref-Cortés_4-0)** Cortés, A. L.; Díaz-Martínez, E.; Sanz-Rubio, E.; Martínez-Frías, J.; Fernández, C. (2002). ["Cosmic impact versus terrestrial origin of the Azuara structure (Spain): A review"](https://doi.org/10.1111%2Fj.1945-5100.2002.tb00862.x). *Meteoritics & Planetary Science*. **37** (6): 875–894. [Bibcode](/source/Bibcode_(identifier)):[2002M&PS...37..875C](https://ui.adsabs.harvard.edu/abs/2002M&PS...37..875C). [doi](/source/Doi_(identifier)):[10.1111/j.1945-5100.2002.tb00862.x](https://doi.org/10.1111%2Fj.1945-5100.2002.tb00862.x). [hdl](/source/Hdl_(identifier)):[10261/35962](https://hdl.handle.net/10261%2F35962).

1. **[^](#cite_ref-Langenhorst_F_5-0)** Langenhorst, F.; Deutsch, A. (1996). "The Azuara and Rubielos structures, Spain: Twin impact craters or Alpine thrust systems? TEM investigations on deformed quartz disprove shock origin". *Lunar and Planetary Science*. **27**: 725–726. [Bibcode](/source/Bibcode_(identifier)):[1996LPI....27..725L](https://ui.adsabs.harvard.edu/abs/1996LPI....27..725L).

1. **[^](#cite_ref-6)** [EDEIS Expert Database on Earth Impact Structures](http://tsun.sscc.ru/nh/impact.php?iname=&country=spain&min_age=0.0&max_age=3400.0&min_valid=0&max_valid=4&min_lat=-90&max_lat=90&min_lon=-180&max_lon=180&min_dia=0.0&max_dia=2250.0&search=Search+Database) [Archived](https://web.archive.org/web/20110727124028/http://tsun.sscc.ru/nh/impact.php?iname=&country=spain&min_age=0.0&max_age=3400.0&min_valid=0&max_valid=4&min_lat=-90&max_lat=90&min_lon=-180&max_lon=180&min_dia=0.0&max_dia=2250.0&search=Search+Database) July 27, 2011, at the [Wayback Machine](/source/Wayback_Machine)

### Bibliography

- Mikheeva, Anna (2017), [*The Complete Catalog of the Earth's Impact structures*](http://labmpg.sscc.ru/impact/index1.html), [Russian Academy of Sciences](/source/Russian_Academy_of_Sciences), p. 1, retrieved 2019-04-02

## External links

- [EDEIS Expert Database on Earth Impact Structures](https://web.archive.org/web/20110727124028/http://tsun.sscc.ru/nh/impact.php?iname=&country=spain&min_age=0.0&max_age=3400.0&min_valid=0&max_valid=4&min_lat=-90&max_lat=90&min_lon=-180&max_lon=180&min_dia=0.0&max_dia=2250.0&search=Search+Database)

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Adapted from the Wikipedia article [Azuara impact structure](https://en.wikipedia.org/wiki/Azuara_impact_structure) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Azuara_impact_structure?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.