The nature of Miocene Amazonian epicontinental embayment: High-frequency shifts of the low-gradient coastline

Abstract

Research Article| November 01, 2007 The nature of Miocene Amazonian epicontinental embayment: High-frequency shifts of the low-gradient coastline Jussi Hovikoski; Jussi Hovikoski 1Department of Geology, University of Turku, 20014 Turku, Finland Search for other works by this author on: GSW Google Scholar Murray Gingras; Murray Gingras 2Department of Earth and Atmospheric Sciences, 1–26 Earth Science Building, University of Alberta, Edmonton, T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar Matti Räsänen; Matti Räsänen 3Department of Geology, University of Turku, 20014 Turku, Finland Search for other works by this author on: GSW Google Scholar Luisa A. Rebata; Luisa A. Rebata 3Department of Geology, University of Turku, 20014 Turku, Finland Search for other works by this author on: GSW Google Scholar Javier Guerrero; Javier Guerrero 4Departamento de Geociencias, Universidad Nacional de Colombia, Bogotá, Colombia Search for other works by this author on: GSW Google Scholar Alceu Ranzi; Alceu Ranzi 5Laboratorio de Pesquisas Paleontologicas, Departamento de Ciencias de Natureza, Universidade Federal do Acre (UFAC), 69.915-900 Rio Branco-Acre, Brazil Search for other works by this author on: GSW Google Scholar Janira Melo; Janira Melo 5Laboratorio de Pesquisas Paleontologicas, Departamento de Ciencias de Natureza, Universidade Federal do Acre (UFAC), 69.915-900 Rio Branco-Acre, Brazil Search for other works by this author on: GSW Google Scholar Lidia Romero; Lidia Romero 6Laboratorio de Paleontología, INGEMMET, Avenida San Borja 1470, Lima, Peru Search for other works by this author on: GSW Google Scholar Hernando Nuñez del Prado; Hernando Nuñez del Prado 6Laboratorio de Paleontología, INGEMMET, Avenida San Borja 1470, Lima, Peru Search for other works by this author on: GSW Google Scholar Freddy Jaimes; Freddy Jaimes 6Laboratorio de Paleontología, INGEMMET, Avenida San Borja 1470, Lima, Peru Search for other works by this author on: GSW Google Scholar Shirley Lopez Shirley Lopez 7SERGEOMIN, La Paz, Bolivia Search for other works by this author on: GSW Google Scholar GSA Bulletin (2007) 119 (11-12): 1506–1520. https://doi.org/10.1130/0016-7606(2007)119[1506:TNOMAE]2.0.CO;2 Article history received: 16 Nov 2006 rev-recd: 17 Apr 2007 accepted: 20 May 2007 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Jussi Hovikoski, Murray Gingras, Matti Räsänen, Luisa A. Rebata, Javier Guerrero, Alceu Ranzi, Janira Melo, Lidia Romero, Hernando Nuñez del Prado, Freddy Jaimes, Shirley Lopez; The nature of Miocene Amazonian epicontinental embayment: High-frequency shifts of the low-gradient coastline. GSA Bulletin 2007;; 119 (11-12): 1506–1520. doi: https://doi.org/10.1130/0016-7606(2007)119[1506:TNOMAE]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A sedimentological and ichnological data set that covers the Lower-Upper Miocene sedimentary series of western Amazonian foreland basin indicates that widespread, restricted marine ingressions shaped western Amazonia throughout the Miocene. The late Lower–early Upper Miocene sedimentary series (Pebas Formation) consists of stacked, 3- to 10-m-thick, tidally influenced, brackish to freshwater, bay-margin sequences. The overlying Upper Miocene (“post-Pebas”) strata bear tidally influenced, low-salinity, channel deposits that are interbedded with continental deposits. The data suggest that several tens of high-frequency ingressions reached the basin during the Miocene. The ingressions were shallow and restricted, and were interspersed with rapid progradation. Along with the prograding shorelines, the continental environments—swamps, lagoons, floodplains and forests—constrained the extent of the marginal marine embayment. Consequently, the Miocene marginal marine and continental strata are closely interbedded throughout the basin. These results refine the recent depositional models for Miocene Amazonia, and challenge the theory that marine ingressions shaped the area only during one brief time interval (late Middle-early Late Miocene) during the epoch.Much of recent literature has documented fossils of mangrove pollen, brackish-euryhaline fish and brackish-water ostracods, brackish-water trace fossil assemblages, and tidal deposits from various Miocene stratigraphic levels. Commonly, these data sets are collected from the same outcrops as those for which data sets imply freshwater conditions. We propose that these seemingly contrasting data sets can be unified, if the repetitive nature of the ingressions is considered, and all the paleoenvironmental data are presented in a detailed lithological and stratigraphical context. You do not currently have access to this article.