The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)
<p>One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained fr...
| Auteurs principaux: | , , , , , , , , |
|---|---|
| Format: | Journal article |
| Publié: |
Elsevier
2017
|
| _version_ | 1826293092132585472 |
|---|---|
| author | Sier, M Langereis, C Dupont-Nivet, G Feibel, C Joordens, J van der Lubbe, J Beck, C Olago, D Cohen, A |
| author_facet | Sier, M Langereis, C Dupont-Nivet, G Feibel, C Joordens, J van der Lubbe, J Beck, C Olago, D Cohen, A |
| author_sort | Sier, M |
| collection | OXFORD |
| description | <p>One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing outcrop sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a ~216-meter core (WTK13) in 2013 from Early Pleistocene Paleolake Lorenyang deposits in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the WTK13 core, providing a first age model for upcoming HSPDP paleoclimate and paleoenvrionmental studies on the core sediments. Rock magnetic analyses reveal the presence of iron sulfides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai Subchron. From this excellent record, we find no evidence for the ‘Vrica Subchron’ previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica Subchron have been affected by the oxidation of iron sulfides initially present in the sediments -as evident in the core record- and by subsequent remagnetization. We discuss the implications of the observed geomagnetic record for human evolution studies.</p> |
| first_indexed | 2024-03-07T03:24:45Z |
| format | Journal article |
| id | oxford-uuid:b8a9d1d4-d357-4be9-a3f0-2973516daf9c |
| institution | University of Oxford |
| last_indexed | 2024-03-07T03:24:45Z |
| publishDate | 2017 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | oxford-uuid:b8a9d1d4-d357-4be9-a3f0-2973516daf9c2022-03-27T04:57:22ZThe top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:b8a9d1d4-d357-4be9-a3f0-2973516daf9cSymplectic Elements at OxfordElsevier2017Sier, MLangereis, CDupont-Nivet, GFeibel, CJoordens, Jvan der Lubbe, JBeck, COlago, DCohen, A <p>One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing outcrop sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a ~216-meter core (WTK13) in 2013 from Early Pleistocene Paleolake Lorenyang deposits in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the WTK13 core, providing a first age model for upcoming HSPDP paleoclimate and paleoenvrionmental studies on the core sediments. Rock magnetic analyses reveal the presence of iron sulfides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai Subchron. From this excellent record, we find no evidence for the ‘Vrica Subchron’ previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica Subchron have been affected by the oxidation of iron sulfides initially present in the sediments -as evident in the core record- and by subsequent remagnetization. We discuss the implications of the observed geomagnetic record for human evolution studies.</p> |
| spellingShingle | Sier, M Langereis, C Dupont-Nivet, G Feibel, C Joordens, J van der Lubbe, J Beck, C Olago, D Cohen, A The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP) |
| title | The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP) |
| title_full | The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP) |
| title_fullStr | The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP) |
| title_full_unstemmed | The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP) |
| title_short | The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP) |
| title_sort | top of the olduvai subchron in a high resolution magnetostratigraphy from the west turkana core wtk13 hominin sites and paleolakes drilling project hspdp |
| work_keys_str_mv | AT sierm thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT langereisc thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT dupontnivetg thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT feibelc thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT joordensj thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT vanderlubbej thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT beckc thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT olagod thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT cohena thetopoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT sierm topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT langereisc topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT dupontnivetg topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT feibelc topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT joordensj topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT vanderlubbej topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT beckc topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT olagod topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp AT cohena topoftheolduvaisubchroninahighresolutionmagnetostratigraphyfromthewestturkanacorewtk13homininsitesandpaleolakesdrillingprojecthspdp |