BIBLIOS

Document type
Journal articles

Document subtype
Full paper

Title
Palaeoecology, taphonomy, and preservation of a lower Pliocene shell bed (coquina) from a volcanic oceanic island (Santa Maria Island, Azores)

Participants in the publication
Sérgio P. Ávila (Author)
Ricardo S. Ramalho (Author)
Jörg M. Habermann (Author)
Rui Quartau (Author)
Andreas Kroh (Author)
Björn Berning (Author)
Markes Johnson (Author)
Michael X. Kirby (Author)
Vittorio Zanon (Author)
Jürgen Titschack (Author)
Adam Goss (Author)
Ana Cristina Rebelo (Author)
Carlos Melo (Author)
Patrícia Madeira (Author)
Ricardo Cordeiro (Author)
Ricardo Meireles (Author)
Leila Bagaço (Author)
Ana Hipólito (Author)
Alfred Uchman (Author)
Carlos Marques da Silva (Author)
Dep. Geologia
IDL
Mário Cachão (Author)
Dep. Geologia
IDL
José Madeira (Author)
Dep. Geologia
IDL

Summary
Massive fossil shell accumulations require particular conditions to be formed and may provide valuable insights into the sedimentary environments favouring such concentrations. Shallow-water shell beds appear to be particularly rare on reefless volcanic oceanic islands on account of narrow, steep and highly-energetic insular shelves where the potential for preservation is limited. The occurrence of an exceptional coquina (Pedra-que-pica) within the Miocene–Pliocene deposits of Santa Maria Island (Azores), therefore provides a rare opportunity to understand the conditions that led to the formation and preservation of a massive shell bed at mid-ocean insular setting. This study provides a detailed analysis regarding a 10–11-m-thick bivalve-dominated fossil assemblage exposed at Pedra-que-pica on Santa Maria Island in the Azores. Integration of taphonomical, palaeoecological and sedimentological observations are used to reconstruct the genesis of the coquina bed and related events, and to discuss why such exceptional sedimentary bodies are so rare on shelves around reefless volcanic oceanic islands.\nThe sequence at Pedra-que-pica demonstrates a complex succession of sedimentary environments in response to the drowning of an existing coastline during a period of rapid sea-level rise. The Pedra-que-pica shell bed incorporates storm-related materials and possible debris falls that originated nearby in a shallow and highly productive carbonate factory. Deposition took place below fair-weather wave base, at around 50 m depth, as inferred from the overlying volcanic succession. The preservation of this coquina was favoured by deposition on a platform laterally protected by a rocky spur, combined with rapid burial by water-settled volcanic tuffs and subsequent volcanic effusive sequences. The recent exhumation of the deposit is the result of island uplift and subsequent erosion.


Where published
Palaeogeography, Palaeoclimatology, Palaeoecology

Publication Identifiers
ISSN - 0031-0182

Publisher
Elsevier BV



Document Identifiers
DOI - https://doi.org/10.1016/j.palaeo.2015.04.015
URL - http://dx.doi.org/10.1016/j.palaeo.2015.04.015

Rankings
SCIMAGO Q1 (2015) - 1.285 - Earth surface processes

Keywords
Coquina Sedimentary processes Palaeoenvironmental reconstruction Island shelves Volcanic oceanic islands Azores