Stratigraphy and Petrology of the Nonmarine Honda Group (Miocene), Upper Magdalena Valley, Colombia

Abstract

Research Article| August 01, 1970 Stratigraphy and Petrology of the Nonmarine Honda Group (Miocene), Upper Magdalena Valley, Colombia SAMUEL S WELLMAN SAMUEL S WELLMAN Shell Oil Company, Box 2241, Houston, Texas 77001 Search for other works by this author on: GSW Google Scholar Author and Article Information SAMUEL S WELLMAN Shell Oil Company, Box 2241, Houston, Texas 77001 Publisher: Geological Society of America Received: 07 Jul 1969 Received: 17 Mar 1970 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1970) 81 (8): 2353–2374. https://doi.org/10.1130/0016-7606(1970)81[2353:SAPOTN]2.0.CO;2 Article history Received: 07 Jul 1969 Received: 17 Mar 1970 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation SAMUEL S WELLMAN; Stratigraphy and Petrology of the Nonmarine Honda Group (Miocene), Upper Magdalena Valley, Colombia. GSA Bulletin 1970;; 81 (8): 2353–2374. doi: https://doi.org/10.1130/0016-7606(1970)81[2353:SAPOTN]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Miocene Honda Group, more than 3000 m thick in the Upper Magdalena Valley of Colombia, was derived from the volcanically active igneous-metamorphic central range (Cordillera Central) of the Andes, which was mantled with sedimentary and volcanic rocks. The group was deposited by rivers flowing generally normal to the central range, indicating that major uplift of the eastern range occurred after accumulation of the Honda sediments.Two major depositional environments of fluvial sedimentation are interpreted from sedimentologic and petrologic evidence: low gradient-high sinuosity, and high gradient-low sinuosity streams. The former type, favored during low tectonic and/or volcanic activity, resulted in red hematitic floodplain mudstones of montmorillonite, illite-montmorillonite and kaolinite, with subordinate thin tan, nonconglomeratic, subarkosic to arkosic, simple sand-bodies. The sandbodies, elongate with a low width: depth ratio, show the vertical arrangement of sedimentary features and fining-upward grain-size that characterize point bar deposits of low gradient, meandering streams. Directions of cross-stratification within the sandbody and the sandbodies themselves have a high variance.The second type, operative during moderate to high tectonism and/or volcanism, was probably braided and deposited thick sandbodies, commonly multistory and multilateral, with a high width: depth ratio. Sedimentary structures have a predictable vertical arrangement but do not become finer in grain size upward. Directions of cross-strata in sandbodies and the sandbodies themselves have a lower variance than those of the first type. The gray, conglomeratic, arkosic to impure arkosic sandbodies are associated with subordinate drab mudstone of montmorillonite and illite-montmorillonite.The Honda Group consists of two formations. The lower, La Dorada Formation (new name), was deposited during increasing tectonism an P volcanism, which were almost nil during accumulation of the conformably underlying La Cira Formation. The Puerto Salgar Member (new name) of the La Dorada is overlain by the Perico Member (new name), which is capped by an orthoconglomeratic interval. The upper formation of the Honda, the Villavieja (new name), accumulated during mild tectonic activity and episodic volcanism which yielded two sharply contrasting lithofacies: the Baraya Volcanic Member (new name) and the Cerro Colorado Redbed Member (new name). This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.