Late-Quaternary lowstands of lake Bosumtwi, Ghana: evidence from high-resolution seismic-reflection and sediment-core data

Brooks, Keely M.; Scholz, Christopher A.; King, John W.; Peck, John A.; Overpeck, Jonathan T.; Russell, James M.; Amoako, P. Y.

doi:10.1016/j.palaeo.2004.10.005

Cited by 28 publications

(29 citation statements)

References 40 publications

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“…The lowest topographic point on the crater rim has an elevation of 210 m, about 110 m above the present lake level, which is the elevation at which the lake will overflow (Turner et al 1996a(Turner et al , 1996b. Data presented by these authors, as well as by Peck et al (2004) and Brooks et al (2005), indicate that the lake level has shown significant fluctuations during the past 20,000 years or so. Peck et al (2004), from a study of magnetic parameters of minerals in an 11 m long core, spanning 26,000 years of deposition, found abrupt shifts in the magnetic parameters that were interpreted to represent pronounced arid conditions when the summer monsoon was greatly weakened.…”

Section: Importance For Paleoenvironmental Studiesmentioning

confidence: 90%

“…Another apparent exposure surface observed in a sediment core was interpreted to have developed prior to 16.8 cal ky BP when the lake was 60 m bpll. Three older, erosional surfaces have estimated ages of ~65, ~86, ~108 cal ky BP (Brooks et al 2005). These lowstands of Lake Bosumtwi are likely a response to increased aridity in this part of the equatorial tropics and may correlate with other observed continent-wide shifts in African climate over the past 100 ky. More recent fluctuations in lake level have also been documented (e.g., Talbot and Delibrias 1977;Russell et al 2003;Shanahan et al 2005Shanahan et al , 2006.…”

Section: Importance For Paleoenvironmental Studiesmentioning

confidence: 92%

“…These authors correlated these arid intervals to the Younger Dryas and Heinrich event 1 and 2, thus showing a coupling between high-and lowlatitude climate change. Brooks et al (2005), using high-resolution, singlechannel seismic-reflection profiles and sedimentological data from a 14 C-dated sediment piston core, found four seismic sequence boundaries and an exposure surface from a sediment core, which they interpreted as erosional surfaces formed during lake lowstands. The most recent severe lowstand occurs as much as 31 m below present lake level (bpll), which was interpreted by Brooks et al (2005) to be coeval with the late-Holocene dry period between 500 to 1000 calendar years before present (cal yr BP).…”

Section: Importance For Paleoenvironmental Studiesmentioning

confidence: 99%

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An international and multidisciplinary drilling project into a young complex impact structure: The 2004 ICDP Bosumtwi Crater Drilling Project—An overview

Koeberl

Milkereit

Overpeck

et al. 2007

Meteorit & Planetary Scien

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102

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Abstract-The Bosumtwi impact crater in Ghana, arguably the best-preserved complex young impact structure known on Earth, displays a pronounced rim and is almost completely filled by Lake Bosumtwi, a hydrologically closed basin. It is the source crater of the Ivory Coast tektites. The structure was excavated in 2.1-2.2 Gyr old metasediments and metavolcanics of the Birimian Supergroup. A drilling project was conceived that would combine two major scientific interests in this crater: 1) to obtain a complete paleoenvironmental record from the time of crater formation about one million years ago, at a near-equatorial location in Africa for which very few data are available so far, and 2) to obtain a complete record of impactites at the central uplift and in the crater moat, for ground truthing and comparison with other structures.Within the framework of an international and multidisciplinary drilling project led by the International Continental Scientific Drilling Program (ICDP), 16 drill cores were obtained from June to October 2004 at six locations within Lake Bosumtwi, which is 8.5 km in diameter. The 14 sediment cores are currently being investigated for paleoenvironmental indicators. The two impactite cores LB-07A and LB-08A were drilled into the deepest section of the annular moat (540 m) and the flank of the central uplift (450 m), respectively. They are the main subject of this special issue of Meteoritics & Planetary Science, which represents the first detailed presentations of results from the deep drilling into the Bosumtwi impactite sequence. Drilling progressed in both cases through the impact breccia layer into fractured bedrock. LB-07A comprises lithic (in the uppermost part) and suevitic impact breccias with appreciable amounts of impact melt fragments. The lithic clast content is dominated by graywacke, besides various metapelites, quartzite, and a carbonate target component. Shock deformation in the form of quartz grains with planar microdeformations is abundant. First chemical results indicate a number of suevite samples that are strongly enriched in siderophile elements and Mg, but the presence of a definite meteoritic component in these samples cannot be confirmed due to high indigenous values. Core LB-08A comprises suevitic breccia in the uppermost part, followed with depth by a thick sequence of graywacke-dominated metasediment with suevite and a few granitoid dike intercalations. It is assumed that the metasediment package represents bedrock intersected in the 484 C. Koeberl et al.

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Section: Importance For Paleoenvironmental Studiesmentioning

confidence: 90%

Section: Importance For Paleoenvironmental Studiesmentioning

confidence: 92%

Section: Importance For Paleoenvironmental Studiesmentioning

confidence: 99%

See 1 more Smart Citation

An international and multidisciplinary drilling project into a young complex impact structure: The 2004 ICDP Bosumtwi Crater Drilling Project—An overview

Koeberl

Milkereit

Overpeck

et al. 2007

Meteorit & Planetary Scien

Self Cite

102

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“…These data and also the highresolution single channel data are proving valuable in deciphering the climate record stored in the lacustrine section (e.g., Peck et al 2005;Brooks et al 2005).…”

Section: Discussionmentioning

confidence: 99%

“…These include a seismic refraction experiment that used ocean-bottom hydrophones (Karp et al 2000) as well as gravity and magnetic studies that were used to corroborate the subsurface models. Initial results of the seismic reflection studies appear in Scholz et al (2002) and Brooks et al (2005). Recent aeromagnetic surveys (Plado et al 2000) and Landsat TM data show that the ejecta blanket for the Bosumtwi structure extends 1-12 km from the center of the structure (Wagner et al 2002).…”

Section: Geologic Background and Previous Workmentioning

confidence: 98%

Structure and morphology of the Bosumtwi impact structure from seismic reflection data

Scholz

Karp

Lyons

2007

Meteorit & Planetary Scien

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Abstract-The Lake Bosumtwi impact structure in West Africa offers unparalleled opportunities for the study of cratering processes, as the structure is young (1.1 Myr) and minimally eroded. Because the center part of the structure is covered by Lake Bosumtwi, which is 8 km in diameter and ~70 m deep, it is possible to use marine-type seismic reflection techniques to obtain high-fidelity images of the lake subsurface, including key elements of the impact structure.Eight profiles of multichannel seismic reflection (MCS) data were acquired in a radial pattern across the basin, as well as two other high-resolution seismic reflection surveys. The MCS data show a well-defined central uplift near the north-central part of the lake. Observed within the annular moat surrounding the buried central uplift is a section of post-impact lacustrine sediments more than 300 m thick. The central uplift structure has a diameter of 1.9 km and a maximum height of 130 m above the annular moat. The central uplift has an overall irregular upper surface with a small graben structure. We observe a series of normal faults that extend as much as 120 m into the sedimentary section above the central uplift. We interpret the normal faults to be a consequence of ongoing compaction of the high-porosity materials that comprise the central uplift. The interpreted impact structure surface, defined using seismic reflection data, was combined with regional topographic data from outside the lake in the form of a digital elevation model, which provides a useful perspective of overall impact structure morphology.

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Regional Description – Africa and Madagascar

Heine

2024

Springer Textbooks in Earth Sciences, Geography and Environment

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Late-Quaternary lowstands of lake Bosumtwi, Ghana: evidence from high-resolution seismic-reflection and sediment-core data

Cited by 28 publications

References 40 publications

An international and multidisciplinary drilling project into a young complex impact structure: The 2004 ICDP Bosumtwi Crater Drilling Project—An overview

An international and multidisciplinary drilling project into a young complex impact structure: The 2004 ICDP Bosumtwi Crater Drilling Project—An overview

Structure and morphology of the Bosumtwi impact structure from seismic reflection data

Regional Description – Africa and Madagascar

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