Bosumtwi impact structure, Ghana: Evidence for fluidized emplacement of the ejecta

David Baratoux, Cheikh Ahmadou Bamba Niang, Wolf Uwe Reimold, Marian Selorm Sapah, Mark Walter Jessell, Daniel Boamah, Gayane Faye, Sylvain Bouley, Olivier Vanderheaghe

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The about 10.5 km diameter Bosumtwi impact crater is one of the youngest large impact structures on Earth. The crater rim is readily noticed on topographic maps or in satellite imagery. It defines a circular basin filled by water (Lake Bosumtwi) and lacustrine sediments. The morphology of this impact structure is also characterized by a circular plateau extending beyond the rim and up to 9–10 km from the center of the crater (about 2 crater radii). This feature comprises a shallow ring depression, also described as an annular moat, and a subdued circular ridge at its outer edge. The origin of this outermost feature could so far not be elucidated based on remote sensing data only. Our approach combines detailed topographic analysis, including roughness mapping, with airborne radiometric surveys (mapping near-surface K, Th, U concentrations) and field observations. This provides evidence that the moat and outer ring are features inherited from the impact event and represent the partially eroded ejecta layer of the Bosumtwi impact structure. The characteristics of the outer ridge indicate that ejecta emplacement was not purely ballistic but requires ejecta fluidization and surface flow. The setting of Bosumtwi ejecta can therefore be considered as a terrestrial analog for rampart craters, which are common on Mars and Venus, and also found on icy bodies of the outer solar system (e.g., Ganymede, Europa, Dione, Tethys, and Charon). Future studies at Bosumtwi may therefore help to elucidate the mechanism of formation of rampart craters.

Original languageEnglish
Number of pages16
JournalMeteoritics and Planetary Science
DOIs
Publication statusE-pub ahead of print - 13 Feb 2019

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Ghana
impact structure
ejecta
craters
crater
emplacement
rims
lacustrine deposit
ridges
Charon
radiometric survey
Ganymede
Tethys
Europa
satellite imagery
fluidization
airborne survey
rings
Venus (planet)
Dione

Cite this

Baratoux, David ; Niang, Cheikh Ahmadou Bamba ; Reimold, Wolf Uwe ; Sapah, Marian Selorm ; Jessell, Mark Walter ; Boamah, Daniel ; Faye, Gayane ; Bouley, Sylvain ; Vanderheaghe, Olivier. / Bosumtwi impact structure, Ghana : Evidence for fluidized emplacement of the ejecta. In: Meteoritics and Planetary Science. 2019.
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abstract = "The about 10.5 km diameter Bosumtwi impact crater is one of the youngest large impact structures on Earth. The crater rim is readily noticed on topographic maps or in satellite imagery. It defines a circular basin filled by water (Lake Bosumtwi) and lacustrine sediments. The morphology of this impact structure is also characterized by a circular plateau extending beyond the rim and up to 9–10 km from the center of the crater (about 2 crater radii). This feature comprises a shallow ring depression, also described as an annular moat, and a subdued circular ridge at its outer edge. The origin of this outermost feature could so far not be elucidated based on remote sensing data only. Our approach combines detailed topographic analysis, including roughness mapping, with airborne radiometric surveys (mapping near-surface K, Th, U concentrations) and field observations. This provides evidence that the moat and outer ring are features inherited from the impact event and represent the partially eroded ejecta layer of the Bosumtwi impact structure. The characteristics of the outer ridge indicate that ejecta emplacement was not purely ballistic but requires ejecta fluidization and surface flow. The setting of Bosumtwi ejecta can therefore be considered as a terrestrial analog for rampart craters, which are common on Mars and Venus, and also found on icy bodies of the outer solar system (e.g., Ganymede, Europa, Dione, Tethys, and Charon). Future studies at Bosumtwi may therefore help to elucidate the mechanism of formation of rampart craters.",
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Baratoux, D, Niang, CAB, Reimold, WU, Sapah, MS, Jessell, MW, Boamah, D, Faye, G, Bouley, S & Vanderheaghe, O 2019, 'Bosumtwi impact structure, Ghana: Evidence for fluidized emplacement of the ejecta' Meteoritics and Planetary Science. https://doi.org/10.1111/maps.13253

Bosumtwi impact structure, Ghana : Evidence for fluidized emplacement of the ejecta. / Baratoux, David; Niang, Cheikh Ahmadou Bamba; Reimold, Wolf Uwe; Sapah, Marian Selorm; Jessell, Mark Walter; Boamah, Daniel; Faye, Gayane; Bouley, Sylvain; Vanderheaghe, Olivier.

In: Meteoritics and Planetary Science, 13.02.2019.

Research output: Contribution to journalArticle

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T1 - Bosumtwi impact structure, Ghana

T2 - Evidence for fluidized emplacement of the ejecta

AU - Baratoux, David

AU - Niang, Cheikh Ahmadou Bamba

AU - Reimold, Wolf Uwe

AU - Sapah, Marian Selorm

AU - Jessell, Mark Walter

AU - Boamah, Daniel

AU - Faye, Gayane

AU - Bouley, Sylvain

AU - Vanderheaghe, Olivier

PY - 2019/2/13

Y1 - 2019/2/13

N2 - The about 10.5 km diameter Bosumtwi impact crater is one of the youngest large impact structures on Earth. The crater rim is readily noticed on topographic maps or in satellite imagery. It defines a circular basin filled by water (Lake Bosumtwi) and lacustrine sediments. The morphology of this impact structure is also characterized by a circular plateau extending beyond the rim and up to 9–10 km from the center of the crater (about 2 crater radii). This feature comprises a shallow ring depression, also described as an annular moat, and a subdued circular ridge at its outer edge. The origin of this outermost feature could so far not be elucidated based on remote sensing data only. Our approach combines detailed topographic analysis, including roughness mapping, with airborne radiometric surveys (mapping near-surface K, Th, U concentrations) and field observations. This provides evidence that the moat and outer ring are features inherited from the impact event and represent the partially eroded ejecta layer of the Bosumtwi impact structure. The characteristics of the outer ridge indicate that ejecta emplacement was not purely ballistic but requires ejecta fluidization and surface flow. The setting of Bosumtwi ejecta can therefore be considered as a terrestrial analog for rampart craters, which are common on Mars and Venus, and also found on icy bodies of the outer solar system (e.g., Ganymede, Europa, Dione, Tethys, and Charon). Future studies at Bosumtwi may therefore help to elucidate the mechanism of formation of rampart craters.

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JO - Meteoritics and Planetary Science

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SN - 1086-9379

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