Where: Russian Federation (70.6° N, 104.6° E: paleocoordinates 0.0° N, 0.0° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Kotuikan Formation (Billyakh Group), Calymmian (1600.0 - 1400.0 Ma)

• Upper Kotuikan Formation. K/Ar and Rb/Sr dates obtained on mineralogically characterized glauconite from the basal Ust'-Il'ya Formation are consistent and yield ages of 1459 +/- 10 and 1483 +/- 5 Ma, respectively (Gorokhov et al., 1991). Mineralogically unstudied glauconite from the Lower and Upper Members of the Yusmastakh Formation were reported to have K/Ar ages of 1260 and 1120-1140 Ma, respectively (Semikhatov and Serebryakov, 1983); however, these determinations were obtained in the late 1960s and are of questionable reliability. Carbon isotope profiles throughout the Kotuikan Formation are consistent with an early Mesoproterozoic age of deposition but inconsistent with a latest Mesoproterozoic or Neoproterozoic age. 1993). Therefore, we view all available chronostratigraphic data as indicating an early Mesoproterozoic age of deposition for the Ust'-Il'ya and Kotuikan Formations, consistent with the radiometric dates of 1450-1500 Ma cited above.

• bed-level stratigraphic resolution

Environment/lithology: peritidal; lithified, stromatolitic, black, cherty/siliceous dolomite

Size class: microfossils

Preservation: permineralized, original carbon, replaced with silica

Collection methods: peel or thin section

• Repository: Paleobotanical Collections of the Harvard University Herbaria (HUHPC) or Geological Institute of the Russian Academy of Sciences (GIN)

Primary reference: V. N. Sergeev, A. H. Knoll, and J. P. Grotzinger. 1995. Paleobiology of the Mesoproterozoic Billyakh Group, Anabar Uplift, northern Siberia. Paleontological Society Memoir 39:1-37 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 227500: authorized by Matthew Clapham, entered by Matthew Clapham on 13.10.2022

Creative Commons license: CC BY (attribution)