Depositional Environment and Bone Diagenesis of the Mio/Pliocene Langebaanweg Bonebed, South Africa

Research Article| December 01, 2013 DEPOSITIONAL ENVIRONMENT AND BONE DIAGENESIS OF THE MIO/PLIOCENE LANGEBAANWEG BONEBED, SOUTH AFRICA I.M. BRUMFITT; I.M. BRUMFITT Department of Geological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, Cape Town, South Africa Corresponding author: e-mail: ian_brumfitt@yahoo.co.uk) Search for other works by this author on: GSW Google Scholar A. CHINSAMY; A. CHINSAMY Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, Cape Town, South Africa, e-mail: anusuya.chinsamy-turan@uct.ac.za Search for other works by this author on: GSW Google Scholar J.S. COMPTON J.S. COMPTON Department of Geological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, Cape Town, South Africa, e-mail: john.compton@uct.ac.za Search for other works by this author on: GSW Google Scholar South African Journal of Geology (2013) 116 (2): 241–258. https://doi.org/10.2113/gssajg.116.2.241 Article history first online: 09 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 I.M. BRUMFITT, A. CHINSAMY, J.S. COMPTON; DEPOSITIONAL ENVIRONMENT AND BONE DIAGENESIS OF THE MIO/PLIOCENE LANGEBAANWEG BONEBED, SOUTH AFRICA. South African Journal of Geology 2013;; 116 (2): 241–258. doi: https://doi.org/10.2113/gssajg.116.2.241 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 SocietySouth African Journal of Geology Search Advanced Search Abstract Langebaanweg is a world renowned, richly fossiliferous Miocene/Pliocene bone assemblage on the West Coast of South Africa. Despite considerable palaeontological investigation of the biodiversity of the site, few studies have been conducted on the bone diagenesis. This study examines the petrography of fossil bones and teeth in relation to the host sediment matrix. The Langebaanweg bonebed is variably matrix- and clast-supported, containing abundant gravel-size bone and phosphorite clasts in a quartzose sand matrix with minor amounts of peloidal phosphate grains and kaolinitic clay. The bimodal size distribution of clasts and sand matrix indicates a mixture of beach, fluvial and aeolian sources, consistent with a riverine or aquifer-fed waterhole palaeoenvironment proximal to the sea. Both macro- and microfaunal bones exhibit a range of surface colours (cream/brown through dark orange/brown to black) indicative of secondary mineral precipitation (including manganese) and some show physical damage from trampling. Three phases of bone diagenesis are recognised; an early, rapid transformation of bone (bioapatite) to mineral carbonate hydroxylapatite, an apatite cementation phase and a single, late growth of infilling Mn-rich alteration material. Except for rare burnt bones, bones and teeth mostly preserve fine histological detail. Despite differences in secondary mineral burden and physical deformation (trampling), diagenesis is fairly uniform within the deposit. The excellent bone preservation, and the fact that the deposit has not been reworked is important for depositional models. The classic Palaeo-Berg River fluvial depositional model is challenged in this paper by an alternative possibility that the deposit was an aquifer-fed, near coastal waterhole. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.