Fast or slow melting of the Marinoan snowball Earth? The cap dolostone record

Author(s)

Font, E. ^[1] ; Nedelec, A. ^[2] ; Trindade, R. I. F. ^[3] ; Moreau, C. ^[4]

Affiliation

^[1] Univ Lisbon, IDL, Fac Ciencias, P-1749016 Lisbon - Portugal

^[2] Univ Toulouse, LMTG, UMR 5563, CNRS IRD, OMP, F-31400 Toulouse - France

^[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo - Brazil

^[4] CEA Saclay, LMC14, UMS2572, F-91191 Gif Sur Yvette - France

• Document type: Journal article
• Source: PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY; v. 295, n. 1-2, p. 215-225, SEP 1 2010.
• Web of Science Citations: 26

Abstract

The end of the Neoproterozoic era is punctuated by two global glacial events marked by the presence of glacial deposits overlaid by cap carbonates. Duration of glacial intervals is now consistently constrained to 3-12 million years but the duration of the post-glacial transition is more controversial due to the uncertainty in cap dolostone sedimentation rates. Indeed, the presence of several stratabound magnetic reversals in Brazilian cap dolostones recently questioned the short sedimentation duration (a few thousand years at most) that was initially suggested for these rocks. Here, we present new detailed magnetostratigraphic data of the Mirassol d'Oeste cap dolostones (Mato Grosso, Brazil) and ``bomb-spike{''} calibrated AMS (14)C data of microbial mats from the Lagoa Vermelha (Rio de Janeiro, Brazil). We also compile sedimentary, isotopic and microbiological data from post-Marinoan outcrops and/or recent depositional analogues in order to discuss the deposition rate of Marinoan cap dolostones and to infer an estimation of the deglaciation duration in the snowball Earth aftermath. Taken together, the various data point to a sedimentation duration in the range of a few 10(5) years. (C) 2010 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 98/03621-4 - Participation of cratonic units of South America in the evolution of supercontinents since the Mesoproterozoic period
• Grantee: Igor Ivory Gil Pacca
• Support Opportunities: Research Projects - Thematic Grants