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This article reports the discovery of numerous subaerial exposure surfaces which occur in the ca. 2200 Ma Kuetsjdrvi Sedimentary Formation (KSF) from the Pechenga Greenstone Belt, NE Fennoscandian Shield, Russia. The formation was accumulated within an intraplate rift and is composed of fluviatile-deltaic siliciclastic deposits and lacustrine dolostones. The dolostones are enriched in C-13 (delta(13)C = +6.6 to +7.6parts per thousand V-PDB, delta(18)O = 16.7 to 21.5parts per thousand V-SMOW), which is, in general, assigned to a global perturbation of the carbon cycle. The lacustrine dolostone unit contains desiccated and in situ brecciated carbonate beds, subaerial erosion and dissolution surfaces, epikarst, surficial silicification (silcretes) and hot-water spring travertines. The dissolution surfaces-marked by formation of a few centimetre thick, ’vuggy’, non-laminated, dolomicrite capped by silicified nodular zone-resemble modem calcretes which formed by capillary rise of surface waters (per-ascensum calcrete) following saturation of the regolith zone under and or semi-arid conditions. Abundant red, iron-stained, superficial dolocrete implies the existence of an O-2-rich atmosphere. Rezolith, ’black pebbles’, alveolar septal structures, Microcodium’ and other fabrics associated with plant roots and input of terrestrial organic matter, which are typical for post-Cretaceous pedogenic calcretes, have not been identified. Alfa fabrics can be applied to describe dolocretes though rhombic calcite crystals are lacking. Neither C-13-depletion nor C-13-enrichment has been documented in the dolocrete, which suggests no contribution Of CO2 derived from soil or from any other C-org-rich sources enriched in 12 C, and apparent lack of biological uptake of 12 C during formation of the dolocrete. Both petrographic and carbon isotope data do not support earlier assertions that Palaeoproterozoic subaerial surface was colonised by microbial mats. A few samples have high delta(18)O values (up to 30parts per thousand) despite diagenetic and metamorphic resetting of the oxygen isotope system, suggesting evaporation during formation of the superficial dolocrete. Such documented episodes of subaerial exposure, formation of hot-water travertines, superficial dolocrete and silcrete suggest that there must have been frequent decoupling between the Kuetsjarvi depositional system and the bordering sea. This imposes an additional restriction on the use of the isotopic composition of the KSF dolostones for reconstruction of the delta(13)C(arb) global secular curve. (C) 2004 Elsevier B.V. All rights reserved.