RT Journal Article
T1 Rhodoliths, uniformitarianism, and Darwin: Pleistocene and Recent carbonate deposits in the Cape Verde and Canary archipelagos
A1 Markes, E. Johnson
A1 Baarli, B. Gudveig
A1 Cachão, Mário
A1 Silva, Carlos da
A1 Ledesma Vázquez, Jorge
A1 Mayoral Alfaro, Eduardo
A1 Ramalho, Ricardo S
A1 Santos, Ana Alexandra Guerreiro dos
AB Visiting “St. Jago” (Santiago) in the Cape Verde Islands in 1832 and again in 1836aboard HMS Beagle, Charles Darwin was the first to trace and describe the tri-partsequence of white limestone and sandstone beds stratigraphically located between twolevels of basalt exposed almost uninterrupted for 10 km along coastal cliffs. ThePleistocene carbonate sediments dominated by rhodoliths and rhodolith debrisaccumulated on a basalt shelf and subsequently became buried by subaerial andsubmarine basalt on the southeast coastline of Santiago. The main goal of thiscontribution is to re-examine Darwin’s stratigraphic sequence. The secondary goal is toprovide a general taphonomical model based on the observation of Recent rhodolithdeposits for evaluation of fossil rhodolith assemblages. Environmental uniformitarianismis employed to understand the depositional history of the southern Santiago rhodolith bearing strata. The mixed clastic-carbonate sequence includes a basalt-derived basalconglomerate with an intertidal to shallow subtidal fossil assemblage mainly denoted bylimpets and oysters. Upper layers typically demonstrate swaley and hummocky crossstratification incorporating rhodolith debris further modified by bioturbation. Pillowbasalts from 10 – 18 m in thickness succeeded by subaerial flows imply swift burial ofthe carbonate succession under equivalent water depths. The calcareous nannofossilassemblage was investigated to more precisely date the deposits. Darwin’s paleoshore isreinterpreted to represent two different transgressions occurring between approximately1.1 and 0.7 Ma. Taphonomic grades from whole rhodoliths to finely crushed rhodolithdebris observed under present-day conditions on Maio (Cape Verde Islands) andFuerteventura (Canary Islands) were used to model rhodolith preservation and toconstrain the depositional settings to which rhodoliths may be transported from theoffshore banks where they naturally thrive. Coastward transport of rhodoliths commonlyends with deposition in subtidal storm beds, tidal pools, and platform over-wash deposits,as well as beach, berm, hurricane, tsunami, and coastal dune deposits.
PB Elsevier
SN 0031-0182
SN 1872-616X (electrónico)
YR 2012
FD 2012-02-18
LK https://hdl.handle.net/10272/24442
UL https://hdl.handle.net/10272/24442
LA eng
NO Johnson, M. E., Baarli, B. G., Cachão, M., da Silva, C. M., Ledesma-Vázquez, J., Mayoral, E. J., Ramalho, R. S., & Santos, A. (2012). Rhodoliths, uniformitarianism, and Darwin: Pleistocene and Recent carbonate deposits in the Cape Verde and Canary archipelagos. In Palaeogeography, Palaeoclimatology, Palaeoecology (Vols. 329–330, pp. 83–100). Elsevier BV. https://doi.org/10.1016/j.palaeo.2012.02.019
NO Soporte de la Junta de Andalucía al Grupo de Investigación RNM316Ministerio de Ciencia y Tecnología, subprograma Juan de la Cierva, ref. JCI-2008-2431PTDC/MAR/102800/2008
DS Repositorio Institucional de la Universidad de Huelva
RD 31 may 2026