Transgressive–regressive sequence stratigraphy of Pennsylvanian Donezella bioherms in a foreland basin (Lena Group, Cantabrian Zone, NW Spain)

Abstract

A well-preserved Pennsylvanian (early Moscovian) succession including Donezella mounds, which accumulated in a highly subsiding foreland basin (Cantabrian Zone, NW of Spain), is described and discussed. This succession has been interpreted as one 3rd-order sequence reaching a thickness up to 815 m and recording »2.3-My duration. It consists of four 4th-order transgressive-regressive (T-R) sequences (105-350 m thick and »0.6-My duration), each subdivided into several 5th-order (»70-ky duration) meter-scale cycles (23-m average thickness). Nearly all the Donezella mounds are present in the second and third 4th-order sequences deWned (Levinco Formation). They are up to »90 m in thickness and several hundreds of meters wide, showing lenticular to domal morphologies with steep slopes up to 35-40°. Bioherms are composed of micritic boundstones with heterogeneous microfabrics and a diverse biotic community, including the microproblematic Donezella, calcitornellid foraminifers, bryozoans, agglutinated worm tubes, crinoids, and calcareous algae (red Komia/Ungdarella, beresellids, dasycladaceans and phylloids). According to the biotic assemblage and sedimentological features, these Donezella-rich bioherms thrived in a relatively shallow and low-energy environment (below fair-weather wave-base), and resulted from the baZing and binding ability of Donezella and associated biota, and the in situ-precipitation of microbial micrite. The upward evolution of the succession mainly resulted from the interplay between high tectonic subsidence rates and high-frequency moderate-amplitude glacioeustatic sealevel changes. The mounds growth mainly occurred during the transgressive phase of the 3rd-order sequence (Vereian), whereas during the regressive phase (Kashirian), deltaic siliciclastics prograding westward gradually buried and prevented the buildup development.

Facies, geometry and growth phases of the Valdorria carbonate platform (Pennsylvanian, northern Spain)

“…The presence of encrusting and benthic foraminifera (tetrataxids and Eotuberitina ), the algae Ungdarella , Stacheoides and Archaeolithoporella , and bryozoans suggest a setting exposed to moderately agitated waters in an open‐marine environment (Rácz, ; Eichmüller, ; Della Porta et al ., ,b). Sparitic cements filling Donezella ‐built primary cavities have been described in previous studies (Riding, ; Poncet, ; Samankassou, ; Della Porta et al ., ; Choh & Kirkland, ; Corrochano et al ., ) and indicate in situ early precipitation.…”

Pennsylvanian carbonate platforms adjacent to deltaic systems in an active marine foreland basin (EscaladaFm.,CantabrianZone,NW Spain)

“…The exact correlation between the Central Asturian Coalfield and Ponga thrust system is hampered by the lack of precise fusulinid biostratigraphy in the former unit. Nevertheless, it can be stated that the Escalada I platform correlates landward with a thick paralic succession of shale, siltstone, sandstone with coal seams and limestone beds in the Central Asturian Coalfield, at least including the Tendeyón and Caleras mining stratigraphic packages, dated also on the basis of fusulinid biostratigraphy as upper Kashirian‐lower Podolskian (Van Ginkel, ; Corrochano et al ., ).…”

“…) shows that some cycles bounded by exposure surfaces in the Beleño and Sobrefoz sections comprise 3–4 cycles (4–5th order) in the Campo Caso section, suggesting that two different ranks of high‐frequency sequences can be recognized in lateral time‐equivalent sections. Similarly, other studies had documented high‐frequency cycles in the carbonate successions of the Cantabrian Zone (Della Porta et al ., ; Corrochano et al ., ,b).…”

A novel population of composite mounds: their initiation, growth and demise. San Emiliano Formation, Cantabrian Mountains, Spain

“…Maslov (1929) originally assigned Donezella to the red algae (Johnson 1963), however, in successive subsequent studies Donezella has been considered to be: green (Codiaceae) alga (Rácz 1964), alga incertae sedis (Rich 1967), Foraminifera (Riding 1979), calcareous sponges (Termier et al 1977), microproblematica (Riding 1979;Chuvashov and Riding 1984), green (Paleosiphonocladales) algae (Shuysky 1985;Ivanova 1999), green algae of incertae familiae (Groves, 1986), green (Dasycladales) algae (Deloffre, 1988) and pseudo-algae (Vachard et al 1989). Recent work regarding Donezella refers to the genus as green (Chlorophycophyta) algae (Mamet and Villa 2004), algae incertae sedis (Mamet and Zhu 2005), algospongia (Vachard and Cózar 2010) or more commonly, microproblematica (Samankassou 2001;Della Porta et al 2002;Choh and Kirkland 2006;Corrochano et al 2012). Donezella accumulations are often interpreted to have grown within a warm, shallow (low to moderate energy, below fair-weather wave base) environment but have been shown to thrive over a range of water depths up to 200 m (Della Porta et al 2002;Choh and Kirkland 2006;Corrochano et al 2012).…”

“…Recent work regarding Donezella refers to the genus as green (Chlorophycophyta) algae (Mamet and Villa 2004), algae incertae sedis (Mamet and Zhu 2005), algospongia (Vachard and Cózar 2010) or more commonly, microproblematica (Samankassou 2001;Della Porta et al 2002;Choh and Kirkland 2006;Corrochano et al 2012). Donezella accumulations are often interpreted to have grown within a warm, shallow (low to moderate energy, below fair-weather wave base) environment but have been shown to thrive over a range of water depths up to 200 m (Della Porta et al 2002;Choh and Kirkland 2006;Corrochano et al 2012). Environmental conditions from quiet to quite agitated have been interpreted (Rácz 1964;Bowman 1979).…”