Biocorrosion features and their potential impact on stalagmite U/Th dating within the karst system of the Kongo-Central region.
| dc.contributor.author | Verheyden, S. | |
| dc.contributor.author | Bazebizonza, N. | |
| dc.contributor.author | Ngala, N. | |
| dc.contributor.author | Boudzoumou, F. | |
| dc.contributor.author | Kakule, R. | |
| dc.contributor.author | Degeltagne, J-P. | |
| dc.contributor.author | Cheng, H. | |
| dc.contributor.author | Lahogue, P. | |
| dc.coverage.spatial | Africa | |
| dc.coverage.spatial | Africa - Central | |
| dc.coverage.spatial | Congo | |
| dc.date | 2024 | |
| dc.date.accessioned | 2024-03-14T13:28:27Z | |
| dc.date.available | 2024-03-14T13:28:27Z | |
| dc.identifier.uri | https://orfeo.belnet.be/handle/internal/13204 | |
| dc.description | Paleoclimate proxies recorded within speleothems offer invaluable insights into past climate through the incorporation of various trace elements and changes in stable isotopic composition over time. These proxies reflect changes in temperature, precipitation, and other local environmental factors. Central African speleothems are poorly studied. First dating attempts on these formations have shown high contamination of detrital Thorium (Th). First observations, such as a high porosity and black traces in the studied speleothems, suggest corrosive effects of bat guano. Consequently, this research is focused on investigating this relationship in the Congo area, by observing the effects of bat guano corrosion together with the elaboration of cave climate and environment monitoring. To enhance the understanding in this area, it would be highly beneficial to initiate the process by inventorying the biocorrosion features present in the studied caves. Subsequently, coupling this inventory with geochemical analysis applied to the drip water from monitoring stations would provide valuable insights into the underlying processes. The Karst system in Kongo-Central is formed within carbonate rocks, which are part of the Neoproterozoic Schisto-calcaire subgroup. It stretches, with a distance over 1400km, from southwest Gabon to northwest Angola, traversing the Democratic Republic of the Congo (DRC) and the Republic of the Congo (RC) from NW to SE, covering nearly 500 km with a width that can reach up to 180 km. The layers of this system predominantly maintain a sub-horizontal orientation. Remarkably, the cumulative thickness of the carbonate rocks can exceed 1000 m, making it a significant and fascinating geological feature in the region. The research started with comprehensive investigation of the cave deposits and stalagmites within the caves under study. Although the dating results have not been entirely precise, the ongoing investigations are currently shedding light on the deposits, with special emphasis on the guano found in most of the surveyed sites. To collect crucial data, a seasonally based cave-monitoring approach is adopted, involving the collection of drip samples during both humid and dry seasons, with two to three samples per season. Additionally, continuous temperature recordings and in-situ parameter measurements are taken during each sampling time to capture a comprehensive view of environmental conditions within the caves. Nine samples collected from three stalagmites sampled, originated from both sides of Congo River in the karst area, underwent U-series dating. The obtained results proved to be unusable due to the exceedingly low Thorium (Th) content in the stalagmites. This remarkably low Th concentration contributed to increased errors in age estimation. The presence of Thorium 230 (230Th) at the outset could be attributed to the influence of detrital material or an open geochemical system, possibly linked to the biocorrosion caused by bat guano within the caves and leading to the overestimation of ages. During the last field trip in the DRC, remarkable observations of cave morphology in the neighbouring regions were illustrated. The intriguing biocorrosion features caused by bat guano within the caves were illustrated, as evidenced by the following figures. Notably, Biological Cupolas, guano-holes in the ground, and bell holes in the roof, which bear striking resemblance to similar features observed in other parts of the world, such as France and Slovakia. These observed elements have sparked reflections on their significance in the late morphological evolution of caves. The presence of such biocorrosion prompts to consider their potential impact on cave development and the formation of unique cave structures. Understanding the role of bat guano in shaping the caves' morphology could shed light on the broader processes influencing cave evolution in various geographical contexts. To deepen the understanding in this field, investigating the potential of DRC and RC speleothems as paleoclimatic archives would be immensely valuable. This would enable a detailed study of their petrographic characteristics, aiding in the identification of hiatus layers resulting from the biocorrosion process, while testing for dating possibilities. | |
| dc.language | eng | |
| dc.publisher | Geologica Belgica | |
| dc.title | Biocorrosion features and their potential impact on stalagmite U/Th dating within the karst system of the Kongo-Central region. | |
| dc.type | Conference | |
| dc.subject.frascati | Earth and related Environmental sciences | |
| dc.audience | Scientific | |
| dc.subject.free | Geodynamics and mineral resources | |
| dc.source.title | 1ére édition de la conférence internationale Géologie et ressources naturelles en Afrique centrale, impact sociétal et développement durable | |
| Orfeo.peerreviewed | No | |
| dc.identifier.rmca | 6618 |
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