The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa

Catherine  Martin-Jones; Christine S. Lane; Maarten Blaauw; Darren F. Mark; Dirk Verschuren; Thijs Van der Meeren; Maarten Van Daele; Hannah Wynton; Nick Blegen; Mary Kisaka; Melanie J. Leng; Philip Barker

doi:10.1016/j.quascirev.2023.108476

The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa

Catherine Martin-Jones, Christine S. Lane^*, Maarten Blaauw, Darren F. Mark, Dirk Verschuren, Thijs Van der Meeren, Maarten Van Daele, Hannah Wynton, Nick Blegen, Mary Kisaka, Melanie J. Leng, Philip Barker

^*Corresponding author for this work

School of Natural and Built Environment

Research output: Contribution to journal › Article › peer-review

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Abstract

Regional tephrostratigraphic frameworks connect palaeoclimate, archaeological and volcanological records preserved in soils or lake sediments via shared volcanic ash (tephra) layers. In eastern Africa, tracing of tephra isochrons between geoarchaeological sequences is an established chronostratigraphic approach. However, to date, few long tephra records exist from sites with continuous depositional sequences, such as lake sediments, which offer the potential to connect local and discontinuous sequences at the regional scale. Long lake sediment sequences may also capture more complete eruptive histories of understudied volcanic centres. Here, we present and date the tephrostratigraphic record of a >250,000-year (>250-kyr) continuous sediment sequence extracted from Lake Chala, a crater lake on the Kenya-Tanzania border near Mt Kilimanjaro. Single-grain glass major and minor element analyses of visible and six cryptotephra layers reveal compositions ranging from mafic foidites and basanites to more evolved tephri-phonolites, phonolites, trachytes and a single rhyolite. Of these, nine are correlated to scoria cone eruptions of neighbouring Mt Kilimanjaro or the Chyulu volcanic field ∼60 km to the north; seven are correlated to phonolitic eruptions of Mt Meru, ∼100 km to the west; and four to voluminous trachytic eruptions of Central Kenyan Rift (CKR) volcanoes located ∼350 km to the north. The only rhyolitic tephra layer, a cryptotephra, correlates to the 73.7-ka BP (before present, taken as 1950 CE) Younger Toba Tuff (YTT) from Sumatra. Two of the CKR tephra layers provide direct ties with terrestrial sequences relevant to Middle Stone Age archaeology of the eastern Lake Victoria basin in Kenya. Absolute age estimates obtained by direct ⁴⁰Ar/³⁹Ar dating of 10 tephra layers are combined with six ²¹⁰Pb and 162 ¹⁴C dates covering the last 25-kyr and the well-constrained known age of the YTT to build a first absolute chronology for the full Lake Chala sediment sequence. The uninterrupted >250-kyr Lake Chala sedimentary archive represents a unique tephrostratotype sequence for eastern Africa, optimising the chronological value of tephra correlations in regional palaeoenvironmental, archaeological and volcanological research. Further study of cryptotephra in the Lake Chala sequence and additional geochemical characterisation and dating of ancient volcanic eruptions from nearby and further afield may eventually produce a regionally connected and detailed tephrostratigraphic framework for eastern equatorial Africa.

Original language	English
Article number	108476
Number of pages	23
Journal	Quaternary Science Reviews
Volume	326
Early online date	20 Jan 2024
DOIs	https://doi.org/10.1016/j.quascirev.2023.108476
Publication status	Published - 15 Feb 2024

Bibliographical note

Funding Information:
This research was funded jointly by a UK Natural Environment Research Council standard grant (NE/P011969/1) to CSL, a Ghent University Collaborative Research Operation grant (BOF13/GOA/023) to DV, and by the International Continental Scientific Drilling Program (ICDP) and diverse commingled financing from multiple scientific partners of the DeepCHALLA project (https://www.icdp-online.org/projects/world/africa/lake-challa-kenya-tanzania/). The authors thank the wider DeepCHALLA science team for their contributions and discussion of ideas, and the Continental Scientific Drilling (CSD) Facility, at the University of Minnesota (Minneapolis, USA) for facilitating the initial splitting, non-destructive scanning, photographing and description of the DeepCHALLA cores. Tephra analyses on the DeepCHALLA and CHALLACEA sequences were carried out in the Cambridge Tephra Laboratory within the Department of Geography Science Laboratories at the University of Cambridge, following pilot work on the CHALLACEA sequence undertaken in the Research Laboratory for Archaeology and the History of Art, University of Oxford as part of a Leverhulme Trust Early Career Fellowship to CSL. We thank Alma Piermattei and Friederike Murach-Ward for assisting with cryptotephra analysis on the CHALLACEA record. We are grateful to Audrey DelCamp (Vrije Universiteit Brussel) for providing a valuable recent tephra sample from Mt. Meru and Karen Fontijn (Université Libre de Bruxelles) for advice and comments on an early version of this paper. We also thank Iris Buisman (University of Cambridge) and Victoria Smith (University of Oxford) for supporting EPMA analyses. Finally, the authors thank the two anonymous referees for their constructive advice on improving the manuscript.

Funding Information:
This research was funded jointly by a UK Natural Environment Research Council standard grant (NE/P011969/1) to CSL, a Ghent University Collaborative Research Operation grant (BOF13/GOA/023) to DV, and by the International Continental Scientific Drilling Program (ICDP) and diverse commingled financing from multiple scientific partners of the DeepCHALLA project ( https://www.icdp-online.org/projects/world/africa/lake-challa-kenya-tanzania/ ). The authors thank the wider DeepCHALLA science team for their contributions and discussion of ideas, and the Continental Scientific Drilling (CSD) Facility, at the University of Minnesota (Minneapolis, USA) for facilitating the initial splitting, non-destructive scanning, photographing and description of the DeepCHALLA cores. Tephra analyses on the DeepCHALLA and CHALLACEA sequences were carried out in the Cambridge Tephra Laboratory within the Department of Geography Science Laboratories at the University of Cambridge, following pilot work on the CHALLACEA sequence undertaken in the Research Laboratory for Archaeology and the History of Art, University of Oxford as part of a Leverhulme Trust Early Career Fellowship to CSL. We thank Alma Piermattei and Friederike Murach-Ward for assisting with cryptotephra analysis on the CHALLACEA record. We are grateful to Audrey DelCamp (Vrije Universiteit Brussel) for providing a valuable recent tephra sample from Mt. Meru and Karen Fontijn (Université Libre de Bruxelles) for advice and comments on an early version of this paper. We also thank Iris Buisman ( University of Cambridge ) and Victoria Smith ( University of Oxford ) for supporting EPMA analyses. Finally, the authors thank the two anonymous referees for their constructive advice on improving the manuscript.

Publisher Copyright:
© 2024 The Authors

Keywords

Africa
Argon-dating
East African rift system
Geochemistry
Geochronology
Holocene
Lake Chala
Lake sediments
Palaeoclimate
Pleistocene
Tephrochronology

ASJC Scopus subject areas

Global and Planetary Change
Ecology, Evolution, Behavior and Systematics
Archaeology
Archaeology
Geology

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The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa
Copyright 2024 the authors. This is an open access article published under a Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
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Martin-Jones, C., Lane, C. S., Blaauw, M., Mark, D. F., Verschuren, D., Van der Meeren, T., Van Daele, M., Wynton, H., Blegen, N., Kisaka, M., Leng, M. J., & Barker, P. (2024). The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa. Quaternary Science Reviews, 326, Article 108476. https://doi.org/10.1016/j.quascirev.2023.108476

@article{d29d369131dd488e9c44c7f864a10721,

title = "The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa",

abstract = "Regional tephrostratigraphic frameworks connect palaeoclimate, archaeological and volcanological records preserved in soils or lake sediments via shared volcanic ash (tephra) layers. In eastern Africa, tracing of tephra isochrons between geoarchaeological sequences is an established chronostratigraphic approach. However, to date, few long tephra records exist from sites with continuous depositional sequences, such as lake sediments, which offer the potential to connect local and discontinuous sequences at the regional scale. Long lake sediment sequences may also capture more complete eruptive histories of understudied volcanic centres. Here, we present and date the tephrostratigraphic record of a >250,000-year (>250-kyr) continuous sediment sequence extracted from Lake Chala, a crater lake on the Kenya-Tanzania border near Mt Kilimanjaro. Single-grain glass major and minor element analyses of visible and six cryptotephra layers reveal compositions ranging from mafic foidites and basanites to more evolved tephri-phonolites, phonolites, trachytes and a single rhyolite. Of these, nine are correlated to scoria cone eruptions of neighbouring Mt Kilimanjaro or the Chyulu volcanic field ∼60 km to the north; seven are correlated to phonolitic eruptions of Mt Meru, ∼100 km to the west; and four to voluminous trachytic eruptions of Central Kenyan Rift (CKR) volcanoes located ∼350 km to the north. The only rhyolitic tephra layer, a cryptotephra, correlates to the 73.7-ka BP (before present, taken as 1950 CE) Younger Toba Tuff (YTT) from Sumatra. Two of the CKR tephra layers provide direct ties with terrestrial sequences relevant to Middle Stone Age archaeology of the eastern Lake Victoria basin in Kenya. Absolute age estimates obtained by direct 40Ar/39Ar dating of 10 tephra layers are combined with six 210Pb and 162 14C dates covering the last 25-kyr and the well-constrained known age of the YTT to build a first absolute chronology for the full Lake Chala sediment sequence. The uninterrupted >250-kyr Lake Chala sedimentary archive represents a unique tephrostratotype sequence for eastern Africa, optimising the chronological value of tephra correlations in regional palaeoenvironmental, archaeological and volcanological research. Further study of cryptotephra in the Lake Chala sequence and additional geochemical characterisation and dating of ancient volcanic eruptions from nearby and further afield may eventually produce a regionally connected and detailed tephrostratigraphic framework for eastern equatorial Africa.",

keywords = "Africa, Argon-dating, East African rift system, Geochemistry, Geochronology, Holocene, Lake Chala, Lake sediments, Palaeoclimate, Pleistocene, Tephrochronology",

author = "Catherine Martin-Jones and Lane, {Christine S.} and Maarten Blaauw and Mark, {Darren F.} and Dirk Verschuren and {Van der Meeren}, Thijs and {Van Daele}, Maarten and Hannah Wynton and Nick Blegen and Mary Kisaka and Leng, {Melanie J.} and Philip Barker",

note = "Funding Information: This research was funded jointly by a UK Natural Environment Research Council standard grant (NE/P011969/1) to CSL, a Ghent University Collaborative Research Operation grant (BOF13/GOA/023) to DV, and by the International Continental Scientific Drilling Program (ICDP) and diverse commingled financing from multiple scientific partners of the DeepCHALLA project (https://www.icdp-online.org/projects/world/africa/lake-challa-kenya-tanzania/). The authors thank the wider DeepCHALLA science team for their contributions and discussion of ideas, and the Continental Scientific Drilling (CSD) Facility, at the University of Minnesota (Minneapolis, USA) for facilitating the initial splitting, non-destructive scanning, photographing and description of the DeepCHALLA cores. Tephra analyses on the DeepCHALLA and CHALLACEA sequences were carried out in the Cambridge Tephra Laboratory within the Department of Geography Science Laboratories at the University of Cambridge, following pilot work on the CHALLACEA sequence undertaken in the Research Laboratory for Archaeology and the History of Art, University of Oxford as part of a Leverhulme Trust Early Career Fellowship to CSL. We thank Alma Piermattei and Friederike Murach-Ward for assisting with cryptotephra analysis on the CHALLACEA record. We are grateful to Audrey DelCamp (Vrije Universiteit Brussel) for providing a valuable recent tephra sample from Mt. Meru and Karen Fontijn (Universit{\'e} Libre de Bruxelles) for advice and comments on an early version of this paper. We also thank Iris Buisman (University of Cambridge) and Victoria Smith (University of Oxford) for supporting EPMA analyses. Finally, the authors thank the two anonymous referees for their constructive advice on improving the manuscript. Funding Information: This research was funded jointly by a UK Natural Environment Research Council standard grant (NE/P011969/1) to CSL, a Ghent University Collaborative Research Operation grant (BOF13/GOA/023) to DV, and by the International Continental Scientific Drilling Program (ICDP) and diverse commingled financing from multiple scientific partners of the DeepCHALLA project ( https://www.icdp-online.org/projects/world/africa/lake-challa-kenya-tanzania/ ). The authors thank the wider DeepCHALLA science team for their contributions and discussion of ideas, and the Continental Scientific Drilling (CSD) Facility, at the University of Minnesota (Minneapolis, USA) for facilitating the initial splitting, non-destructive scanning, photographing and description of the DeepCHALLA cores. Tephra analyses on the DeepCHALLA and CHALLACEA sequences were carried out in the Cambridge Tephra Laboratory within the Department of Geography Science Laboratories at the University of Cambridge, following pilot work on the CHALLACEA sequence undertaken in the Research Laboratory for Archaeology and the History of Art, University of Oxford as part of a Leverhulme Trust Early Career Fellowship to CSL. We thank Alma Piermattei and Friederike Murach-Ward for assisting with cryptotephra analysis on the CHALLACEA record. We are grateful to Audrey DelCamp (Vrije Universiteit Brussel) for providing a valuable recent tephra sample from Mt. Meru and Karen Fontijn (Universit{\'e} Libre de Bruxelles) for advice and comments on an early version of this paper. We also thank Iris Buisman ( University of Cambridge ) and Victoria Smith ( University of Oxford ) for supporting EPMA analyses. Finally, the authors thank the two anonymous referees for their constructive advice on improving the manuscript. Publisher Copyright: {\textcopyright} 2024 The Authors",

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Martin-Jones, C, Lane, CS, Blaauw, M, Mark, DF, Verschuren, D, Van der Meeren, T, Van Daele, M, Wynton, H, Blegen, N, Kisaka, M, Leng, MJ & Barker, P 2024, 'The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa', Quaternary Science Reviews, vol. 326, 108476. https://doi.org/10.1016/j.quascirev.2023.108476

TY - JOUR

T1 - The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa

AU - Martin-Jones, Catherine

AU - Lane, Christine S.

AU - Blaauw, Maarten

AU - Mark, Darren F.

AU - Verschuren, Dirk

AU - Van der Meeren, Thijs

AU - Van Daele, Maarten

AU - Wynton, Hannah

AU - Blegen, Nick

AU - Kisaka, Mary

AU - Leng, Melanie J.

AU - Barker, Philip

N1 - Funding Information: This research was funded jointly by a UK Natural Environment Research Council standard grant (NE/P011969/1) to CSL, a Ghent University Collaborative Research Operation grant (BOF13/GOA/023) to DV, and by the International Continental Scientific Drilling Program (ICDP) and diverse commingled financing from multiple scientific partners of the DeepCHALLA project (https://www.icdp-online.org/projects/world/africa/lake-challa-kenya-tanzania/). The authors thank the wider DeepCHALLA science team for their contributions and discussion of ideas, and the Continental Scientific Drilling (CSD) Facility, at the University of Minnesota (Minneapolis, USA) for facilitating the initial splitting, non-destructive scanning, photographing and description of the DeepCHALLA cores. Tephra analyses on the DeepCHALLA and CHALLACEA sequences were carried out in the Cambridge Tephra Laboratory within the Department of Geography Science Laboratories at the University of Cambridge, following pilot work on the CHALLACEA sequence undertaken in the Research Laboratory for Archaeology and the History of Art, University of Oxford as part of a Leverhulme Trust Early Career Fellowship to CSL. We thank Alma Piermattei and Friederike Murach-Ward for assisting with cryptotephra analysis on the CHALLACEA record. We are grateful to Audrey DelCamp (Vrije Universiteit Brussel) for providing a valuable recent tephra sample from Mt. Meru and Karen Fontijn (Université Libre de Bruxelles) for advice and comments on an early version of this paper. We also thank Iris Buisman (University of Cambridge) and Victoria Smith (University of Oxford) for supporting EPMA analyses. Finally, the authors thank the two anonymous referees for their constructive advice on improving the manuscript. Funding Information: This research was funded jointly by a UK Natural Environment Research Council standard grant (NE/P011969/1) to CSL, a Ghent University Collaborative Research Operation grant (BOF13/GOA/023) to DV, and by the International Continental Scientific Drilling Program (ICDP) and diverse commingled financing from multiple scientific partners of the DeepCHALLA project ( https://www.icdp-online.org/projects/world/africa/lake-challa-kenya-tanzania/ ). The authors thank the wider DeepCHALLA science team for their contributions and discussion of ideas, and the Continental Scientific Drilling (CSD) Facility, at the University of Minnesota (Minneapolis, USA) for facilitating the initial splitting, non-destructive scanning, photographing and description of the DeepCHALLA cores. Tephra analyses on the DeepCHALLA and CHALLACEA sequences were carried out in the Cambridge Tephra Laboratory within the Department of Geography Science Laboratories at the University of Cambridge, following pilot work on the CHALLACEA sequence undertaken in the Research Laboratory for Archaeology and the History of Art, University of Oxford as part of a Leverhulme Trust Early Career Fellowship to CSL. We thank Alma Piermattei and Friederike Murach-Ward for assisting with cryptotephra analysis on the CHALLACEA record. We are grateful to Audrey DelCamp (Vrije Universiteit Brussel) for providing a valuable recent tephra sample from Mt. Meru and Karen Fontijn (Université Libre de Bruxelles) for advice and comments on an early version of this paper. We also thank Iris Buisman ( University of Cambridge ) and Victoria Smith ( University of Oxford ) for supporting EPMA analyses. Finally, the authors thank the two anonymous referees for their constructive advice on improving the manuscript. Publisher Copyright: © 2024 The Authors

PY - 2024/2/15

Y1 - 2024/2/15

N2 - Regional tephrostratigraphic frameworks connect palaeoclimate, archaeological and volcanological records preserved in soils or lake sediments via shared volcanic ash (tephra) layers. In eastern Africa, tracing of tephra isochrons between geoarchaeological sequences is an established chronostratigraphic approach. However, to date, few long tephra records exist from sites with continuous depositional sequences, such as lake sediments, which offer the potential to connect local and discontinuous sequences at the regional scale. Long lake sediment sequences may also capture more complete eruptive histories of understudied volcanic centres. Here, we present and date the tephrostratigraphic record of a >250,000-year (>250-kyr) continuous sediment sequence extracted from Lake Chala, a crater lake on the Kenya-Tanzania border near Mt Kilimanjaro. Single-grain glass major and minor element analyses of visible and six cryptotephra layers reveal compositions ranging from mafic foidites and basanites to more evolved tephri-phonolites, phonolites, trachytes and a single rhyolite. Of these, nine are correlated to scoria cone eruptions of neighbouring Mt Kilimanjaro or the Chyulu volcanic field ∼60 km to the north; seven are correlated to phonolitic eruptions of Mt Meru, ∼100 km to the west; and four to voluminous trachytic eruptions of Central Kenyan Rift (CKR) volcanoes located ∼350 km to the north. The only rhyolitic tephra layer, a cryptotephra, correlates to the 73.7-ka BP (before present, taken as 1950 CE) Younger Toba Tuff (YTT) from Sumatra. Two of the CKR tephra layers provide direct ties with terrestrial sequences relevant to Middle Stone Age archaeology of the eastern Lake Victoria basin in Kenya. Absolute age estimates obtained by direct 40Ar/39Ar dating of 10 tephra layers are combined with six 210Pb and 162 14C dates covering the last 25-kyr and the well-constrained known age of the YTT to build a first absolute chronology for the full Lake Chala sediment sequence. The uninterrupted >250-kyr Lake Chala sedimentary archive represents a unique tephrostratotype sequence for eastern Africa, optimising the chronological value of tephra correlations in regional palaeoenvironmental, archaeological and volcanological research. Further study of cryptotephra in the Lake Chala sequence and additional geochemical characterisation and dating of ancient volcanic eruptions from nearby and further afield may eventually produce a regionally connected and detailed tephrostratigraphic framework for eastern equatorial Africa.

AB - Regional tephrostratigraphic frameworks connect palaeoclimate, archaeological and volcanological records preserved in soils or lake sediments via shared volcanic ash (tephra) layers. In eastern Africa, tracing of tephra isochrons between geoarchaeological sequences is an established chronostratigraphic approach. However, to date, few long tephra records exist from sites with continuous depositional sequences, such as lake sediments, which offer the potential to connect local and discontinuous sequences at the regional scale. Long lake sediment sequences may also capture more complete eruptive histories of understudied volcanic centres. Here, we present and date the tephrostratigraphic record of a >250,000-year (>250-kyr) continuous sediment sequence extracted from Lake Chala, a crater lake on the Kenya-Tanzania border near Mt Kilimanjaro. Single-grain glass major and minor element analyses of visible and six cryptotephra layers reveal compositions ranging from mafic foidites and basanites to more evolved tephri-phonolites, phonolites, trachytes and a single rhyolite. Of these, nine are correlated to scoria cone eruptions of neighbouring Mt Kilimanjaro or the Chyulu volcanic field ∼60 km to the north; seven are correlated to phonolitic eruptions of Mt Meru, ∼100 km to the west; and four to voluminous trachytic eruptions of Central Kenyan Rift (CKR) volcanoes located ∼350 km to the north. The only rhyolitic tephra layer, a cryptotephra, correlates to the 73.7-ka BP (before present, taken as 1950 CE) Younger Toba Tuff (YTT) from Sumatra. Two of the CKR tephra layers provide direct ties with terrestrial sequences relevant to Middle Stone Age archaeology of the eastern Lake Victoria basin in Kenya. Absolute age estimates obtained by direct 40Ar/39Ar dating of 10 tephra layers are combined with six 210Pb and 162 14C dates covering the last 25-kyr and the well-constrained known age of the YTT to build a first absolute chronology for the full Lake Chala sediment sequence. The uninterrupted >250-kyr Lake Chala sedimentary archive represents a unique tephrostratotype sequence for eastern Africa, optimising the chronological value of tephra correlations in regional palaeoenvironmental, archaeological and volcanological research. Further study of cryptotephra in the Lake Chala sequence and additional geochemical characterisation and dating of ancient volcanic eruptions from nearby and further afield may eventually produce a regionally connected and detailed tephrostratigraphic framework for eastern equatorial Africa.

KW - Africa

KW - Argon-dating

KW - East African rift system

KW - Geochemistry

KW - Geochronology

KW - Holocene

KW - Lake Chala

KW - Lake sediments

KW - Palaeoclimate

KW - Pleistocene

KW - Tephrochronology

U2 - 10.1016/j.quascirev.2023.108476

DO - 10.1016/j.quascirev.2023.108476

M3 - Article

AN - SCOPUS:85182891635

SN - 0277-3791

VL - 326

JO - Quaternary Science Reviews

JF - Quaternary Science Reviews

M1 - 108476

ER -

The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa

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Bibliographical note

Keywords

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