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Integrated chronostratigraphy of Proterozoic-Cambrian boundary beds in the western Anabar region, northern Siberia

Kaufman, Alan J. and Knoll, Andrew H. and Semikhatov, Mikhail A. and Grotzinger, John P. and Jacobsen, Stein B. and Adams, William (1996) Integrated chronostratigraphy of Proterozoic-Cambrian boundary beds in the western Anabar region, northern Siberia. Geological Magazine, 133 (5). pp. 509-533. ISSN 0016-7568.

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Carbonate-rich sedimentary rocks of the western Anabar region, northern Siberia, preserve an exceptional record of evolutionary and biogeochemical events near the Proterozoic/Cambrian boundary. Sedimentologically, the boundary succession can be divided into three sequences representing successive episodes of late transgressive to early highstand deposition; four parasequences are recognized in the sequence corresponding lithostratigraphically to the Manykai Formation. Small shelly fossils are abundant and include many taxa that also occur in standard sections of southeastern Siberia. Despite this coincidence of faunal elements, biostratigraphic correlations between the two regions have been controversial because numerous species that first appear at or immediately above the basal Tommotian boundary in southeastern sections have first appearances scattered through more than thirty metres of section in the western Anabar. Carbon- and Sr-isotopic data on petrographically and geochemically screened samples collected at one- to two-metre intervals in a section along the Kotuikan River, favour correlation of the Staraya Reckha Formation and most of the overlying Manykai Formation with sub-Tommotian carbonates in southeastern Siberia. In contrast, isotopic data suggest that the uppermost Manykai Formation and the basal 26 m of the unconformably overlying Medvezhya Formation may have no equivalent in the southeast; they appear to provide a sedimentary and palaeontological record of an evolutionarily significant time interval represented in southeastern Siberia only by the sub-Tommotian unconformity. Correlations with radiometrically dated horizons in the Olenek and Kharaulakh regions of northern Siberia suggest that this interval lasted approximately three to six million years, during which essentially all 'basal Tommotian' small shelly fossils evolved.

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Knoll, Andrew H.0000-0003-1308-8585
Grotzinger, John P.0000-0001-9324-1257
Additional Information:© 1996 Cambridge University Press. Received 22 June 1995; accepted 5 February 1996. Samples for isotopic analysis were collected during a joint US-Russian expedition to the Anabar region in 1992. We thank V. N. Sergeev and P. Yu. Petrov for help in the field, J. Milder and R. Pflaum for laboratory support A. Yu. Rozanov for helpful discussions of biostratigraphy, and M. Brasier for comments on the manuscript. This research was supported in part by NASA Grant NAGW-893 (to AHK), NSF Grant EAR-9086119 (To JPG), NSF Grant EAR-9118628 (to SBJ) and ISF Grant ML0-000 and ISF/Russian Government Grant ML0-300 (to MAS).
Funding AgencyGrant Number
Israel Science FoundationML0-000
Israel Science FoundationML0-300
Issue or Number:5
Record Number:CaltechAUTHORS:20130304-091115863
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Official Citation:A. J. Kaufman, A. H. Knoll, M. A. Semikhatov, J. P. Grotzinger, S. B. Jacobsen, and W. Adams Integrated chronostratigraphy of Proterozoic-Cambrian boundary beds in the western Anabar region, northern Siberia Geological Magazine, September 1996, v. 133, p. 509-533
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37267
Deposited By: Tony Diaz
Deposited On:06 Mar 2013 16:14
Last Modified:09 Mar 2020 13:18

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