Abstract
Chitinozoans were recovered from the Naranco, Huergas and Gustalapiedra formations of northern Spain, which yielded a diverse assemblage including 29 taxa in 9 named genera. The deposits are of early Givetian age, a time when Iberia was isolated from large continents as part of the Armorican Terrane Assemblage. The formations studied here consist of a large clastic unit interrupting carbonate deposition, with large limestone formations positioned above and below the formations analyzed here. This clastic unit includes the Kačák Event, an important global extinction event associated with anoxia in the marine realm. In this paper, the relatively well-preserved chitinozoan assemblage is described and considered from a biogeographical and stratigraphical perspective. The chitinozoan community was deposited in a short space of time and includes various taxa not previously known from the Middle Devonian, though the assemblage as a whole is attributable to the period. Only moderate similarity is seen with assemblages reported from Laurussia and Gondwana, with a slight bias towards the latter. This report adds to our knowledge of chitinozoan paleobiogeography and to other recent studies of Middle Devonian palynology in northern Iberia.
Highlights
While the chitinozoan record of the Silurian and Early Devonian of northern Spain is relatively well-known, with over one hundred taxa described from the area (Cramer, 1964, 1966a, 1966b; Cramer and Díez, 1978; Díez and Cramer, 1978; Richardson et al, 2001), the Middle Devonian strata has received next to no formal study
This is not for lack of suitable deposits or geological information; the lithostratigraphy has received extensive study, and units are often well exposed and present various features of interest. These deposits consist of a clastic unit sandwiched between thick carbonate deposits, representing a marine onshore–offshore transect, and are very well described sedimentologically, while they are well age-constrained by conodont and land plant spore biostratigraphy
The present study aims to comprehensively describe the chitinozoan taxa from this sequence for the first time, comment on the assemblage's biogeographical similarities/
Summary
While the chitinozoan record of the Silurian and Early Devonian of northern Spain is relatively well-known, with over one hundred taxa described from the area (Cramer, 1964, 1966a, 1966b; Cramer and Díez, 1978; Díez and Cramer, 1978; Richardson et al, 2001), the Middle Devonian strata has received next to no formal study. This is not for lack of suitable deposits or geological information; the lithostratigraphy has received extensive study, and units are often well exposed and present various features of interest. These deposits consist of a clastic unit sandwiched between thick carbonate deposits, representing a marine onshore–offshore transect, and are very well described sedimentologically, while they are well age-constrained by conodont and land plant spore biostratigraphy. Differences with contemporary assemblages and add to other recent studies concerning the palynology of this sequence
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