Details

Autor(en) / Beteiligte

• Bakaeva, Alexandra V.
• Chazhengina, Svetlana Y.
• Svetov, Sergei A.

Titel

Neoarchean paleosols in the Eastern Fennoscandian Shield of Central Karelia, Russia, and their paleoatmospheric implication

Ist Teil von

• Palaeogeography, palaeoclimatology, palaeoecology, 2024-09, Vol.649, p.112319, Article 112319

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2024

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• Precambrian paleosols provide important evidence for deciphering ancient atmospheric conditions; however, reconstruction using the Archean–Early Proterozoic weathering crusts is challenging due to reworking by later superimposed events. In this paper, we describe 2.6 Ga paleoweathering crusts developed on ultramafic rocks recognized in the Eastern Fennoscandian Shield of northwest Karelia, Russia. Mafic index of alteration shows an increasing trend from parent rock to the paleosol and indicates moderate weathering. Geochemical and mineralogical data provide evidence for paleosol formation under anoxic acidic conditions. The results allow reconstruction of palaeoatmospheric pO2 and pCO2 levels estimated to be 1 × 10−4 PAL and 22 PAL, respectively. Analysis of the paleosols in the Eastern Fennoscandian Shield reveals that the anoxic weathering seems to have prevailed over Archean–Early Proterozoic interval. The study contributes to understanding of evolution of atmospheric oxygen levels and paleoenvironmental conditions prior to the Great Oxidation Event. •Neoarchean paleosols have been recognized in the Eastern Fennoscandian Shield•Pitkilampi paleosols developed under a cool to temperate and humid climate•Anoxic weathering in the Eastern Fennoscandian Shield during pre-GOE timeframe