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Sizing up the sub-Tommotian unconformity in Siberia

Knoll, Andrew H. and Kaufman, Alan J. and Semikhatov, Mikhail A. and Grotzinger, John P. and Adams, William (1995) Sizing up the sub-Tommotian unconformity in Siberia. Geology, 23 (12). pp. 1139-1143. ISSN 0091-7613. doi:10.1130/0091-7613(1995)023<1139:SUTSTU>2.3.CO;2.

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Sedimentary rocks in the western Anabar region, northwestern Siberia, preserve an exceptional record of evolution and biogeochemical events near the Proterozoic-Cambrian boundary. Carbon isotopic data on petrographically and geochemically screened samples collected at 1 to 2 m intervals support correlation of the lower Anabar succession (Staraya Reckha and lower Manykai Formations) with sub-Tommotian carbonates of the Ust&-Yudoma Formation in southeastern Siberia. In contrast, the upper Manykai and most of the overlying Medvezhya Formation appear to preserve a sedimentary and paleontological record of an evolutionarily important time interval represented in southeastern Siberia only by the sub-Tommotian unconformity. Correlation of the Anabar section with other northern Siberian successions that contain well-dated volcanic rocks permits the estimate that the sub-Tommotian unconformity in southeastern Siberia spans approximately 3 to 6 m.y. Diverse small shelly fossils (but not archaeocyathans) previously thought to mark the base of the Tommotian Stage evolved sequentially throughout this earlier interval.

Item Type:Article
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URLURL TypeDescription<1139:SUTSTU>2.3.CO;2DOIArticle
Knoll, Andrew H.0000-0003-1308-8585
Grotzinger, John P.0000-0001-9324-1257
Additional Information:© 1995 Geological Society of America. Manuscript received May 5, 1995. Revised manuscript received August 4, 1995. Manuscript accepted August 18, 1995. Supported in part by National Aeronautics and Space Administration grant NAGW-893 (to Knoll), National Science Foundation grant EAR-9058199 (to Grotzinger), and International Science Foundation–Russian Government grants MLO-000 and MLO-300 (to Semikhatov). Samples were collected during a joint U.S.-Russian expedition in 1992. We thank V. N. Sergeev and P. Yu. Petrov for help in the field and A. Yu. Rozanov for helpful discussions.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
International Science Foundation–Russian Government grantMLO-000
International Science Foundation–Russian Government grantMLO-300
Issue or Number:12
Record Number:CaltechAUTHORS:20130227-145333815
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Official Citation: Andrew H. Knoll, Alan J. Kaufman, Mikhail A. Semikhatov, John P. Grotzinger, and William Adams Sizing up the sub-Tommotian unconformity in Siberia Geology, December, 1995, v. 23, p. 1139-1143, doi:10.1130/0091-7613(1995)023<1139:SUTSTU>2.3.CO;2
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37185
Deposited By: Ruth Sustaita
Deposited On:28 Feb 2013 16:05
Last Modified:09 Nov 2021 23:27

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