Revisiting afro-alpine Lake Garba Guracha in the Bale Mountains of Ethiopia: rationale, chronology, geochemistry, and paleoenvironmental implications

Publikation: Beitrag in FachzeitschriftForschungsartikelBeigetragenBegutachtung

Beitragende

  • L. Bittner - , Professur für Physische Geographie mit Schwerpunkt Paläoumweltforschung (Heisenberg), Martin-Luther-Universität Halle-Wittenberg (Autor:in)
  • M. Bliedtner - , Friedrich-Schiller-Universität Jena (Autor:in)
  • D. Grady - , Aberystwyth University (Autor:in)
  • G. Gil-Romera - , Aberystwyth University, Consejo Superior de Investigaciones Científicas (Autor:in)
  • C. Martin-Jones - , University of Cambridge, Ghent University (Autor:in)
  • B. Lemma - , Martin-Luther-Universität Halle-Wittenberg (Autor:in)
  • B. Mekonnen - , Martin-Luther-Universität Halle-Wittenberg, Universität Bayreuth (Autor:in)
  • H. F. Lamb - , Aberystwyth University (Autor:in)
  • H. Yang - , University College London (Autor:in)
  • B. Glaser - , Martin-Luther-Universität Halle-Wittenberg (Autor:in)
  • S. Szidat - , Universität Bern (Autor:in)
  • G. Salazar - , Universität Bern (Autor:in)
  • N. L. Rose - , University College London (Autor:in)
  • L. Opgenoorth - , Philipps-Universität Marburg (Autor:in)
  • G. Miehe - , Philipps-Universität Marburg (Autor:in)
  • W. Zech - , Universität Bayreuth (Autor:in)
  • M. Zech - , Professur für Physische Geographie mit Schwerpunkt Paläoumweltforschung (Heisenberg) (Autor:in)

Abstract

Previous paleolimnological studies demonstrated that the sediments of Garba Guracha, situated at 3950 m asl in the afro-alpine zone of the Bale Mountains of Ethiopia, provide a complete Late Glacial and Holocene paleoclimate and environmental archive. We revisited Garba Guracha in order to retrieve new sediment cores and to apply new environmental proxies, e.g. charcoal, diatoms, biomarkers, and stable isotopes. Our chronology is established using 210Pb dating and radiocarbon dating of bulk sedimentary organic matter, bulk n-alkanes, and charcoal. Although bedrock was not reached during coring, basal ages confirm that sedimentation started at the earliest ~ 16 cal kyr BP. The absence of a systematic age offset for the n-alkanes suggests that “pre-aging” is not a prominent issue in this lake, which is characterised by a very small afro-alpine catchment. X-ray fluorescence scans and total organic carbon contents show a prominent transition from minerogenic to organic-rich sediments around 11 cal kyr BP coinciding with the Holocene onset. While an unambiguous terrestrial versus aquatic source identification seems challenging, the n-alkane-based Paq proxy, TOC/N ratios, δ13C values, and the sugar biomarker patterns suggest a predominantly autochthonous organic matter source. Supraregional climate events, such as the African Humid Period, the Younger Dryas (YD), a 6.5 cal kyr BP short drying event, and the 4.2 cal kyr BP transition to overall drier climate are recorded in our archive. The Garba Guracha record suggests that northern hemisphere forcings played a role in the Eastern African highland paleoclimate.

Details

OriginalspracheEnglisch
Seiten (von - bis)293-314
Seitenumfang22
FachzeitschriftJournal of Paleolimnology
Jahrgang64
Ausgabenummer3
PublikationsstatusVeröffentlicht - 1 Okt. 2020
Peer-Review-StatusJa

Schlagworte

Schlagwörter

  • Afro-alpine, Biomarkers, Paleolimnology, Radiocarbon dating, Sedimentation rate, XRF scanning

Bibliotheksschlagworte