Late-Holocene paleomagnetic secular variation records from Lake Turkana, East Equatorial Africa

Steve Lund, Ellen Platzman, Chris Scholz

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We have carried out a paleomagnetic study of three piston cores collected from Lake Turkana. The goal is to recover a Holocene paleomagnetic secular variation (PSV) record for this lake and to correlate it with other Holocene PSV records from the East Africa Rift Valley (EARV). All three cores were sampled with u-channels and magnetic measurements of magnetic susceptibility, the natural remanence (NRM), and two artificial remanences, anhysteretic remanence (ARM) and saturation isothermal remanence (SIRM), were made on them. The remanences were routinely step-wise demagnetized and measured at 10 mT steps up to 60 mT. The NRMS had a simple pattern of demagnetization with a characteristic direction (ChRM) removed between 10 and 60 mT. ARM and SIRM demagnetization indicated that the magnetic grains were relatively soft with median destructive fields (MDF) less than 30 mT. We interpret the magnetic grains to be multi-domain (silt-sized) magnetite/titanomagnetite. The resulting magnetic records of all three cores could be correlated. A chronology for these cores was determined from four radiocarbon dates on core 4P. We also estimated the sediment ages by correlating the PSV to two other well-dated PSV records from the same region, Lakes Malawi and Victoria. PSV age estimation indicates that the radiocarbon dates are about 500 year too old; a correction for that offset causes three of the four radiocarbon ages to become consistent with the PSV age estimates. The final composite Lake Turkana PSV record for the last ~4000 years is the highest resolution directional record of PSV (~200 cm/ky) ever to be recovered from Africa.

Original languageEnglish (US)
Pages (from-to)321-333
Number of pages13
JournalHolocene
Volume32
Issue number4
DOIs
StatePublished - Apr 2022

Bibliographical note

Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was funded by NSF grant EAR-1316507 (2013-2015).

Publisher Copyright:
© The Author(s) 2022.

Keywords

  • East Africa Rift Valley
  • environmental magnetism
  • Holocene
  • Lake Turkana
  • paleomagnetic chronostratigraphy
  • paleomagnetic secular variation

Continental Scientific Drilling Facility tags

  • STURK

Fingerprint

Dive into the research topics of 'Late-Holocene paleomagnetic secular variation records from Lake Turkana, East Equatorial Africa'. Together they form a unique fingerprint.

Cite this