Environmental factors influencing skeletal grain sediment associations: a critical review of Miocene examples from the western Mediterranean

Abstract

The presence of foramol, rhodalgal and bryomol skeletal grain associations in ancient shallow‐marine limestones is commonly interpreted as evidence for non‐tropical palaeoclimate, despite temperature being only one of several factors influencing skeletal grain associations. Such interpretations neglect the multitude of factors other than temperature that influence carbonate‐producing biota. These include nutrients, water energy, water transparency, depth of the sea floor, salinity, oxygen, Ca2+ and CO2 concentrations, Mg/Ca ratio, alkalinity, substrate requirements, competitive displacement as well as biological and evolutionary trends. This uniformitarian approach also disregards the probability that conditions of present‐day biological systems may not be representative of past conditions of analogous systems. Here, the importance of considering these other factors is illustrated through two examples of carbonate platforms in the western Mediterranean. These platforms are dominated by foramol, rhodalgal and bryomol associations of Miocene age in spite of having formed in tropical conditions. The platforms discussed are: (1) the Lower Tortonian ramp on Menorca, Balearic Islands; and (2) the Lower–Middle Miocene ramps of the central Apennines, Italy. Evidence for tropical conditions in the Mediterranean during the period of growth of these platforms is provided by species of red algae and larger foraminifera, by data from coeval continental basins and by global oxygen isotope data.

Alteration of Triassic carbonates in the Buda Mountains —a hydrothermal model

“…At least in part, these calcitic speleo-concretions grew within a matrix of intensely pulverized dolomite and dolomite breccia, as suggested by the occurrence of abundant patches of pulverized dolomite within the concretions. These concretions are very similar to the groundwater concretions extensively described in the literature (Pomar et al 2004). Nevertheless, late stages of concretional growth could occur along the walls of open channels and caves rather than within the pulverized dolomite body.…”

The influence of terrestrial run off on marine biotic communities: An example from a thrust-top carbonate ramp (Upper Pennsylvanian foreland basin, Picos de Europa, NW Spain)

“…Environmental factors, primarily water depth, light, temperature, salinity, oxygen level and nutrient supply, control the composition of carbonate rocks, as has been demonstrated in numerous studies during the last decades (Chave, 1967;Lees and Buller, 1972;Lees, 1975;Birkeland, 1977;Hallock, 1987;Carannante et al, 1988;Hallock, 1988;Hallock et al, 1988;Nelson, 1988;Carannante et al, 1997;Hallock, 2001;Mutti and Hallock, 2003;Vecsei, 2003;Halfar et al, 2004;Pomar et al, 2004;Wilson and Vecsei, 2005;Halfar et al, 2006). The biotic associations and non-biogenic composition of carbonate rocks thus represent good proxies for the reconstruction of environmental parameters (James, 1997;Hallock, 2001;Mutti and Hallock, 2003;Pomar et al, 2004;Schlager, 2005).…”

“…The biotic associations and non-biogenic composition of carbonate rocks thus represent good proxies for the reconstruction of environmental parameters (James, 1997;Hallock, 2001;Mutti and Hallock, 2003;Pomar et al, 2004;Schlager, 2005).…”

Biostratigraphy and paleoecology of the Oligo-Miocene Asmari Formation in the Izeh zone (Zagros Basin, SW Iran)

“…A similar assemblage was reported from the inner ramp of the Miocene sediments of the Central Apennines (Corda and Brandano, 2003) and from the Early Oligocene deposits of the Lower Inn Valley (Nebelsick et al, 2001). The abundance of larger benthic foraminifera (Borelis, Peneroplis, Dendritina, Heterostegina, Operculina) and zooxanthellate corals indicate mesophothic to euphotic condition (Halfar et al, 2004;Pomar et al, 2004;Pomar and Hallock, 2008;Brandano et al, 2009b;Mazzucchi and Tomassetti, 2011;Tomassetti and Brandano, 2013). During the Burdigalian a slightly restricted lagoon became established over the entire width of the platform in the SW (e.g.…”

“…The symbiont bearing larger foraminifera are known to thrive in tropical waters (Langer and Hottinger, 2000). According to Heydari (2008) (Langer and Hottinger, 2000;Halfar et al, 2004;Pomar et al, 2004;Bassi and Nebelsick, 2010). Oligotrophic to mesotrophic conditions in the inner ramp setting (Chattian-Burdigalian) lead to the occurrence of larger imperforate foraminifera such as Archaias, Borelis, Peneroplis and Austrotrillina.…”