Identification of a Sturtian cap carbonate in the Neoproterozoic Sete Lagoas carbonate platform, Bambui Group, Brazil | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Identification of a Sturtian cap carbonate in the Neoproterozoic Sete Lagoas carbonate platform, Bambui Group, Brazil

Type de publication:

Journal Article

Source:

Comptes Rendus Geoscience, Volume 339, Ticket 3-4, p.240-258 (2007)

ISBN:

1631-0713

URL:

http://www.sciencedirect.com/

Mots-clés:

ORGANIC-MATTER; SOUTH CHINA; GLACIATION

Résumé:

A sedimentological and C-O isotopic study has been carried out in nine sections of the Sete Lagoas Formation at its classical outcropping area, in the southern tip of the Sao Francisco craton (central Brazil), with the objective of refining its stratigraphic position within the Neoproterozoic. At the study area, the Neoproterozoic Sete Lagoas Formation comprises two shallowing-upward megacycles, corresponding to more than 200 m in thickness. Each cycle is limited by a flooding surface amalgamated with a third-order sequence boundary. The first megacycle presents deep-platform deposits with abundance of crystal fans (aragonite pseudomorphs). These deposits are characterized by negative C-isotope values (-4.5%(0)). They grade upward to storm-wave and tide-influenced layers with delta C-13 values around 0%(0). In the second megacycle, a new transgression drowned the platform, depositing a thick, mixed sub-storm wave-base succession. This megacycle comprises deposits of lime mudstone-pelite rhythmite, which grade to crystalline limestone rich in organic matter, both with unusually positive delta C-13 values (up to + 14%(0)). Regional correlation of Sete Lagoas deposits indicate that they rest atop glaciomarine rocks of the Macaubas Group and basal strata show seafloor precipitates with negative delta C-13 values. Therefore, it is possible to characterize the Sete Lagoas carbonate as a cap carbonate sequence. The very high 613C in the second megacycle together with geochronologic data suggest that this unit correlates better with post-Sturtian sequences. Some differences in the depositional record are observed between Sete Lagoas and the other post-Sturtian units previously described in North America, Australia, and Namibia. Those differences may in part be due to deposition in shallower settings of the Sete Lagoas carbonates, thus preserving a thick record of storm- and wave-influenced sedimentation not found elsewhere. Alternatively, they may also be attributed to diachronic deposition of the so-called post-Sturtian cap carbonate sequences.

Notes:

C. R. Geosci.ISI Document Delivery No.: 169QLTimes Cited: 0Cited Reference Count: 64Cited References:ALKMIM FF, 2001, GEOLOGY, V29, P319ALLEN PA, 2004, BASIN RES, V16, P507, DOI10.1111/j.1365-2117.2004.00249.xALLEN PA, 2005, NATURE, V433, P123, DOI 10.1038/nature03176ALVARENGA CJS, 2004, PRECAMBRIAN RES, V131, P1BABINSKI M, 1999, CHEM GEOL, V160, P175BABINSKI M, 2003, 4 S AM S IS GEOL SAL, P321BRASIER MD, 1996, GEOL MAG, V133, P445CHANG HK, 1993, 2 S CRAT SAO FRANC S, P195CHEEL RJ, 1993, PLANET SCI, V23, P451CHEMALE F, 1993, BALKEMA, P29CONDON D, 2005, SCIENCE, V308, P95, DOI 10.1126/science.1107765CORDANI UG, 2000, TECTONIC EVOLUTION S, P19CORKERON ML, 2001, GEOL SOC AM BULL, V113, P1121CORSETTI FA, 2000, INT GEOL REV, V42, P516CORSETTI FA, 2003, GEOL SOC AM BULL, V115, P916COSTA MT, 1961, ANAIS, V15, P1COZZI A, 2004, GEOL SOC AM BULL, V116, P1367, DOI 10.1130/B25387.1DAGRELLA MS, 2000, PRECAMBRIAN RES, V99, P179DARDENNE MA, 1978, AN 30 C BRAS GEOL, V2, P597DERRY LA, 1992, GEOCHIM COSMOCHIM AC, V56, P1317EVANS DAD, 2000, AM J SCI, V300, P347FANNING CM, 2004, GEOLOGY, V32, P881GERMS GJB, 1995, PRECAMBRIAN RES, V73, P137GORJAN P, 2003, J AFR EARTH SCI, V36, P89, DOI10.1016/S0899-5362(03)00002-2GROTZINGER JP, 2000, SEPM SPEC PUBL, V67, P3HALVERSON GP, 2004, BASIN RES, V16, P297, DOI10.1111/j.1365-2117.2004.00234.xHALVERSON GP, 2005, GEOL SOC AM BULL, V117, P1181, DOI 10.1130/B25630.1HARMS JC, 1982, SOC EC PALEONTOL MIN, V249HAYES JM, 1999, CHEM GEOL, V161, P103HIGGINS JA, 2003, GEOCHEM GEOPHY GEOSY, V4, ARTN 1028HOFFMAN PF, 1998, GSA TODAY, V8, P1HOFFMAN PF, 2002, TERRA NOVA, V14, P129HOFFMANN KH, 2004, GEOLOGY, V32, P817, DOI 10.1130/G20519.1IYER SS, 1995, PRECAMBRIAN RES, V73, P271JACOBSEN SB, 1999, CHEM GEOL, V161, P37JAMES NP, 2001, CAN J EARTH SCI, V38, P1229JIANG GQ, 2003, SEDIMENTOLOGY, V50, P921, DOI10.1046/j.1365-3091.2003.00589.xKARFUNKEL J, 1988, PALAEOGEOGR PALAEOCL, V65, P1KAUFMAN AJ, 1991, PRECAMBRIAN RES, V49, P301KAUFMAN AJ, 1995, PRECAMBRIAN RES, V73, P27KENNEDY MJ, 1996, J SEDIMENT RES B, V66, P1050KENNEDY MJ, 1998, GEOLOGY, V26, P1059KENNEDY MJ, 2001, GEOLOGY, V29, P443KIMURA H, 2005, PRECAMBRIAN RES, V138, P1, DOI10.1016/j.precamres.2005.02.002KUMP LR, 1999, PALAEOGEOGR PALAEOCL, V152, P173LORENTZ NJ, 2004, PRECAMBRIAN RES, V130, P57, DOI10.1016/j/precamres.2003.10.017MACHADO N, 1989, 5 S GEOL NUCL MIN GE, P1MARSHAK S, 1989, TECTONICS, V8, P555MARTINSNETO MA, 2001, SEDIMENT GEOL, V141, P343MCKIRDY DM, 2001, PRECAMBRIAN RES, V106, P149MISI A, 1998, PRECAMBRIAN RES, V89, P87MITCHUM RM, 1991, SEDIMENT GEOL, V70, P131NARBONNE GM, 1995, PRECAMBRIAN RES, V73, P101NOGUEIRA ACR, 2003, GEOLOGY, V31, P613PEDROSASOARES AC, 2000, REV BRAS GEOC, V30, P58PERYT TM, 1990, SEDIMENTOLOGY, V37, P279SANTOS RV, 2000, PRECAMBRIAN RES, V104, P107SCHRAG DP, 2002, GEOCHEM GEOPHY GEOSY, V3, ARTN 1036SHIELDS GA, 2002, EARTH PLANET SC LETT, V196, P99SUMNER DY, 2002, INT ASS SEDIMENTARY, V33, P107TRINDADE RIF, 2007, C R GEOSCIENCE, V339UHLEIN A, 1999, J S AM EARTH SCI, V12, P435WALTER MR, 2000, PRECAMBRIAN RES, V100, P371ZHOU CM, 2004, GEOLOGY, V32, P437, DOI 10.1130/G20286.1