Labyrinth patterns in Magadi (Kenya) cherts: Evidence for early formation from siliceous gels

K. Leet, T.K. Lowenstein, R.W. Renaut, R.B. Owen, A. Cohen

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Sedimentary cherts, with well-preserved microfossils, are known from the Archean to the present, yet their origins remain poorly understood. Lake Magadi, Kenya, has been used as a modern analog system for understanding the origins of nonbiogenic chert. We present evidence for synsedimentary formation of Magadi cherts directly from siliceous gels. Petrographic thin-section analysis and field-emission scanning electron microscopy of cherts from cores drilled in Lake Magadi during the Hominin Sites and Paleolakes Drilling Project in 2014 led to the discovery of two-dimensional branching “labyrinth patterns” in chert, which are a type of fractal “squeeze” pattern formed at air-liquid interfaces. Labyrinth patterns preserved in chert from Lake Magadi cores indicate invasion of air along planes in dewatering gels. These patterns support the precipitation of silica gels in the saline-alkaline Lake Magadi system and syndepositional drying of gels in contact with air as part of chert formation. Recognizing cherts as syndepositional has been critical for our use of them for U-Th dating. Identification of labyrinth patterns in ancient cherts can provide a better understanding of paleoenvironmental and geochemical conditions in the past © 2021 Geological Society of America. For permission to copy, contact editing@geosociety.org.
Original languageEnglish (US)
Pages (from-to)1137-1142
Number of pages6
JournalGeology
Volume49
Issue number9
DOIs
StatePublished - Sep 2021

Bibliographical note

Funding Information:
We thank the Hominin Sites and Paleolakes Drilling Project, the U.S. National Science Foundation (grants EAR-1123942, BCS-1241859, and EAR-1338553), the Geological Society of America, and the Hong Kong Research Grants Council (grant 12304018) for providing project funding. We would also like to thank LacCore, the International Continental Scientific Drilling Program (ICDP), Jeff Carpenter, and the Analytical and Diagnostics Laboratory at Binghamton University (New York, USA). DOSECC Exploration Services (Utah, USA), Drilling and Prospecting International (Nairobi Kenya), the Magadi County Council, and the Kenyan National Council for Science and Technology and Kenyan Ministry of Mines are thanked for providing research and export permits for drilling, and the National Environmental Management Authority of Kenya for providing environmental permits for drilling. This is publication 33 of the Hominin Sites and Paleolakes Drilling Project. We wish to extend special thanks to Peter Burgess and two anonymous reviewers whose thoughtful comments improved this work.

Funding Information:
We thank the Hominin Sites and Paleolakes Drilling Project, the U.S. National Science Foundation (grants EAR-1123942, BCS-1241859, and EAR-1338553), the Geological Society of America, and the Hong Kong Research Grants Council (grant 12304018) for providing project funding. We would also like to thank LacCore, the International Continental Scientific Drilling Program (ICDP), Jeff Carpenter, and the Analytical and Diagnostics Laboratory at Binghamton University (New York, USA). DOSECC Exploration Services (Utah, USA), Drilling and Prospecting International (Nairobi Kenya), the Magadi County Council, and the Kenyan National Council for Science and Technology and Kenyan Ministry of Mines are thanked for providing research and export permits for drilling, and the National Environmental Management Authority of Kenya for providing environmental permits for drilling. This is publication 33 of the Hominin Sites and Paleolakes Drilling Project. We wish to extend special thanks to Peter Burgess and two anonymous reviewers whose thoughtful comments improved this work

Publisher Copyright:
© 2021 Geological Society of America. For permission to copy, contact editing@geosociety.org.

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