Magnetostratigraphy of the Hominin Sites and Paleolakes Drilling Project (HSPDP) Baringo-Tugen Hills-Barsemoi core (Kenya)
Sier, Mark J.; Dupont-Nivet, Guillaume; Langereis, Cor; Deino, Alan L.; Kingston, John D.; Cohen, Andrew S.
(2021) Palaeogeography, Palaeoclimatology, Palaeoecology, volume 570, pp. 1 - 12
(Article)
Abstract
The principal objective of the Hominin Sites and Paleolakes Drilling project (HSPDP) is to study the relationship between climate and environmental change and the implications on human evolution in eastern Africa. For this purpose, HSPDP has recovered a 228 m core in the Chemeron Formation of the Baringo Basin (Kenya).
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The Chemeron Formation spans approximately 3.7 Myr, from around 1.6 to 5.3 Ma, and has yielded many vertebrate fossils, including fossil hominins. The magnetostratigraphy of the Baringo core contributes to the chronological framework. A total of 567 individual paleomagnetic samples were collected from 543 levels at regular intervals throughout the core and 264 were processed using thermal and alternative field stepwise demagnetizations. In most samples, distinct Low-Temperature (LT; 20–150 °C) and High-Temperature (HT; 150–550 °C) Characteristic Remanent Magnetization (ChRM) could be determined. Typical demagnetization behaviors and some rock magnetic experiments suggest titanomagnetite acts as the main carrier of the HT ChRM with pervasive secondary overprints in normal polarity expressed by the LT component. Normal and reversed polarities were identified based on the secondary overprints LT ChRM directions, either parallel or antiparallel to the HT ChRM directions respectively. Our study identified four paleomagnetic reversals interpreted as the Matuyama-Gauss, Gauss-Kaena, Kaena-Gauss and the Gauss-Mammoth transitions. These boundaries provide chronostratigraphic tie-points that can be combined with those derived from 40Ar/39Ar dating of tuffs (Deino et al., 2020) and together indicate that the HSPDP Baringo core has an age range of ~3.3 Ma to ~2.6 Ma. The consistent paleomagnetic and radioisotopic age constraints are incorporated into a Bayesian age model of the core (Deino et al., 2020).
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Keywords: Drillcore orientation, Gauss, ICDP, Kaena, Lower Matuyama, Mammoth, Taverne, Oceanography, Ecology, Evolution, Behavior and Systematics, Earth-Surface Processes, Palaeontology
ISSN: 0031-0182
Publisher: Elsevier Saunders
Note: Funding Information: Acquisition of the BTB13 drill core and sampling was funded by the International Continental Drilling Program and US-NSF grants (EAR-1123942, BCS-1241790, EAR-1338553, and EAR-1322017). MJS was funded by Netherlands Organisation for Scientific Research grants NWO-ALW 823.01.003 and is currently funded as a Juan de la Cierva post-doctoral fellow. GDN acknowledges funding from Marie Curie CIG FP7 grant 294282 ?HIRESDAT?. We thank the Kenyan National Council for Science and Technology and Kenyan Ministry of Mines for providing research and export permits, and the National Environmental Management Authority of Kenya for providing environmental permits for the drilling in the Tugen Hills. We also would like to acknowledge DOSECC Exploration Services for drilling supervision, the team of the US National Lacustrine Core Facility (LacCore) for help during drilling and sampling. Finally, we would like to thank the two anonymous reviewers whose comments greatly improved this paper. This is publication number 30 of the Hominin Sites and Paleolakes Drilling Project. Funding Information: Acquisition of the BTB13 drill core and sampling was funded by the International Continental Drilling Program and US-NSF grants ( EAR-1123942 , BCS-1241790 , EAR-1338553 , and EAR-1322017 ). MJS was funded by Netherlands Organisation for Scientific Research grants NWO-ALW 823.01.003 and is currently funded as a Juan de la Cierva post-doctoral fellow. GDN acknowledges funding from Marie Curie CIG FP7 grant 294282 “HIRESDAT”. We thank the Kenyan National Council for Science and Technology and Kenyan Ministry of Mines for providing research and export permits, and the National Environmental Management Authority of Kenya for providing environmental permits for the drilling in the Tugen Hills. We also would like to acknowledge DOSECC Exploration Services for drilling supervision, the team of the US National Lacustrine Core Facility (LacCore) for help during drilling and sampling. Finally, we would like to thank the two anonymous reviewers whose comments greatly improved this paper. This is publication number 30 of the Hominin Sites and Paleolakes Drilling Project. Publisher Copyright: © 2021 Elsevier B.V.
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