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A possible 5 km wide impact structure with associated 22 km wide exterior collapse terrain in the Alhabia–Tabernas Basin, southeastern Spain

Sánchez Gómez, Sebastián Tomás ; Ormö, Jens ; Alwmark, Carl LU ; Holm-Alwmark, Sanna LU ; Zachén, Gabriel LU orcid ; Lilljequist, Robert and Sánchez Garrido, Juan Antonio (2023) In Meteoritics and Planetary Science 58(10). p.1512-1539
Abstract

The Tabernas–Alhabia Basin is a structural depression situated in the province of Almería, southeastern Spain. The basin is filled with Neogene, Pliocene, and Pleistocene sediments resting discordantly on a Paleozoic metamorphic basement. During the marine Tortonian sedimentation, a bed of breccia (Gordo megabed) was formed. It consists of rotated sedimentary megablocks commonly capped and/or surrounded by a polymict breccia composed mainly of up to dm-sized clasts of the crystalline (schist) basement. Previous work has suggested the bed to be a seismite corresponding to events induced by earthquakes. Here, we link the formation of the Gordo megabed with an ∼5 km wide, rimmed depression with exposed breccias on the northern flank of the... (More)

The Tabernas–Alhabia Basin is a structural depression situated in the province of Almería, southeastern Spain. The basin is filled with Neogene, Pliocene, and Pleistocene sediments resting discordantly on a Paleozoic metamorphic basement. During the marine Tortonian sedimentation, a bed of breccia (Gordo megabed) was formed. It consists of rotated sedimentary megablocks commonly capped and/or surrounded by a polymict breccia composed mainly of up to dm-sized clasts of the crystalline (schist) basement. Previous work has suggested the bed to be a seismite corresponding to events induced by earthquakes. Here, we link the formation of the Gordo megabed with an ∼5 km wide, rimmed depression with exposed breccias on the northern flank of the Sierra de Gádor mountain. This semicircular structure, developed in mainly schists and dolostone of the basement, is delimited to the W, S, and E by an up to 350 m high escarpment with overturned stratigraphy. Toward the north, this crater-like structure opens toward the Gordo megabed of the Tabernas Basin. In the southern sector, the overturned strata transform outward for into a blocky allochthonous breccia with decreasing thickness and clast size. In the interior of the structure, there are occurrences of graded breccia and arenite superposed on a blocky, autochthonous breccia. Based on the presence of mineralogical shock metamorphic evidence, potential shatter cones, and a high Ir anomaly (∼500 ppb) as well as the position of the structure near the town of Alhama de Almería, we propose to call it the Alhama de Almería impact structure.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Meteoritics and Planetary Science
volume
58
issue
10
pages
28 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85169671494
ISSN
1086-9379
DOI
10.1111/maps.14063
language
English
LU publication?
yes
id
fca22e08-a764-41ca-812e-d199e6bcf928
date added to LUP
2023-11-10 12:35:41
date last changed
2023-11-25 01:21:22
@article{fca22e08-a764-41ca-812e-d199e6bcf928,
  abstract     = {{<p>The Tabernas–Alhabia Basin is a structural depression situated in the province of Almería, southeastern Spain. The basin is filled with Neogene, Pliocene, and Pleistocene sediments resting discordantly on a Paleozoic metamorphic basement. During the marine Tortonian sedimentation, a bed of breccia (Gordo megabed) was formed. It consists of rotated sedimentary megablocks commonly capped and/or surrounded by a polymict breccia composed mainly of up to dm-sized clasts of the crystalline (schist) basement. Previous work has suggested the bed to be a seismite corresponding to events induced by earthquakes. Here, we link the formation of the Gordo megabed with an ∼5 km wide, rimmed depression with exposed breccias on the northern flank of the Sierra de Gádor mountain. This semicircular structure, developed in mainly schists and dolostone of the basement, is delimited to the W, S, and E by an up to 350 m high escarpment with overturned stratigraphy. Toward the north, this crater-like structure opens toward the Gordo megabed of the Tabernas Basin. In the southern sector, the overturned strata transform outward for into a blocky allochthonous breccia with decreasing thickness and clast size. In the interior of the structure, there are occurrences of graded breccia and arenite superposed on a blocky, autochthonous breccia. Based on the presence of mineralogical shock metamorphic evidence, potential shatter cones, and a high Ir anomaly (∼500 ppb) as well as the position of the structure near the town of Alhama de Almería, we propose to call it the Alhama de Almería impact structure.</p>}},
  author       = {{Sánchez Gómez, Sebastián Tomás and Ormö, Jens and Alwmark, Carl and Holm-Alwmark, Sanna and Zachén, Gabriel and Lilljequist, Robert and Sánchez Garrido, Juan Antonio}},
  issn         = {{1086-9379}},
  language     = {{eng}},
  number       = {{10}},
  pages        = {{1512--1539}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Meteoritics and Planetary Science}},
  title        = {{A possible 5 km wide impact structure with associated 22 km wide exterior collapse terrain in the Alhabia–Tabernas Basin, southeastern Spain}},
  url          = {{http://dx.doi.org/10.1111/maps.14063}},
  doi          = {{10.1111/maps.14063}},
  volume       = {{58}},
  year         = {{2023}},
}