Pierre‐Yves Berthou & Peter Bengtson: Stratigraphic correlation by microfacies of the Cenomanian‐Coniacian of the Sergipe Basin, Brazil

Abstract

LethaiaVolume 22, Issue 3 p. 246-246 Pierre-Yves Berthou & Peter Bengtson: Stratigraphic correlation by microfacies of the Cenomanian-Coniacian of the Sergipe Basin, Brazil First published: July 1989 https://doi.org/10.1111/j.1502-3931.1989.tb01335.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Abstract: Microfacies analysis of outcrop samples from the Cenomanian-Coniacian carbonate sequence of the Sergipe Basin in northeastern Brazil was carried out: (1) to provide complementary data for the biochronostratigraphic framework of the area, based primarily on ammonites, (2) to test the utility of microfacies analysis for local chronocorreiation within an established biostratigraphic framework, and (3) to contribute stratigraphic and paleoenvironmental data for the reconstruction of the mid-Cretaceous development of the Sergipe Basin and its bearing on the history of the South Atlantic. Within the 25 × 120 km outcrop area 604 localities were sampled for microfacies analysis; of these, 278 yielded ammonities and/or inoceramids for biostratigraphic dating. Despite a scarcity of determinable, stratigraphically diagnostic microfossils, microfacies analysis was shown to be useful for complementary dating on an intrabasinal scale down to stage, or occasionally even substage, level. Four main groups of microfacies types were recognized and, supported by macrofossil evidence, found to correspond to the Cenomanian, lower Turonian, upper Turonian, and Coniacian, respectively. The various microfacies types and varieties are described and illustrated. Distinction of microfacies types is based primarily on grain size, general texture, abundance of faunal debris, presence of saccocomid-like echinoderms and certain indeterminate echinoderm remains, as well as on the few microfossils that are determinable in thin section. The Cenomanian microfacies are relatively coarse-grained with locally abundant faunal debris (echinoderms, saccocomids(?), hedbergellids, heterohelicids, calcispheres, sponge spicules, etc.); reworked oncoids and ooids also occur. The lower Turonian microfacies contain common calcispheres but on the whole less faunal debris, which attains a minimum in the upper Turonian peloidal microfacies; in the latter, sponge spicules and calcispheres are generally abundant. The peloidal microfacies continue into the Coniacian, which is essentially characterized by abundant macrofaunal debris and scarcity of calcispheres. The abundance and diversity of the saccocomid-like echinoderms decrease upwards in the sequence. The benthic foraminifers Hemicyclammina sigali Maync and Patellina subcretacea Cushman & Alexander and the alga Heteroporella lepina Praturlon were found to be stratigraphically useful. Deposition is inferred to have taken place predominantly in the outer shelf region, slope and, subordinately, in a deep-marine cratonic basin. Throughout the sequence the amount of macrofaunal debris decreases from northeast to southwest. The littoral zone is inferred to have lain in the north, and at a certain distance from the outcrop area in the central and southern parts of the basin. Volume22, Issue3July 1989Pages 246-246 RelatedInformation