Upper Devonian biostratigraphy of the Iberian Pyrite Belt, southwest Spain Part Two: Organic-walled microphytoplankton

Gonzalez, Felipe, Moreno, Carmen and Playford, Geoffrey (2005) Upper Devonian biostratigraphy of the Iberian Pyrite Belt, southwest Spain Part Two: Organic-walled microphytoplankton. Palaeontographica. Abteilung B, Palaophytologie, 273 4: 53-86.

Author Gonzalez, Felipe
Moreno, Carmen
Playford, Geoffrey
Title Upper Devonian biostratigraphy of the Iberian Pyrite Belt, southwest Spain Part Two: Organic-walled microphytoplankton
Journal name Palaeontographica. Abteilung B, Palaophytologie   Check publisher's open access policy
ISSN 0375-0299
Publication date 2005
Sub-type Critical review of research, literature review, critical commentary
Volume 273
Issue 4
Start page 53
End page 86
Total pages 34
Place of publication Stuttgart, Germany
Publisher E. Schweizerbart'sche Verlagsbuchhandlung
Collection year 2005
Language eng
Subject C1
260113 Palynology
780104 Earth sciences
04 Earth Sciences
040308 Palaeontology (incl.Palynology)
Abstract Upper Devonian rocks of the Iberian Pyrite Belt (IPB) in southwest Spain, comprising the Phyllite-Quartzite Group (PQ) and the lower part of the overlying Volcano-Sedimentary Complex (VSC), contain a diversity of terrestrial and marine palynomorphs (miospores and organic-walled microphytoplankton, respectively), which constitute the basis of this biostratigraphically oriented research project. Part One of the report has previously detailed the miospore content of the constituent 117 palyniferous samples. In the present paper (i.e., the concluding Part Two), the organic-walled microphytoplankton (acritarchs and prasinophyte phycomata) are systematically described and illustrated, and their occurrence in the study material is fully documented. The acritarchs are represented by 23 species (including one species complex) allocated among 14 genera (one of which, Dupliciradiatum, is newly established), together with a very rare and novel category (informally termed Gen. nov. A). The following new acritarch species are formally instituted: Dupliciradiatum crassum (type species), D. tenue, Histopalla languida, and Winwaloeusia repagulata. Five genera allied with the prasinophycean algae are identified; these accommodate a total of 15 species of which two - Cymatiosphaera tenuimembrana and Maranhites multioculus - are formally proposed as new. In addition, representatives of the prasinophyte genera Leiosphaeridia and Tasmanites are recorded but are not discriminated at species level. The microphytoplankton suite is clearly consonant, from previously published occurrences in other regions, with a Late Devonian dating. However, most of the species are known to be relatively long ranging through (and in some cases beyond) that epoch and hence are not amenable to detailed biozonal subdivision of the IPB succession. Moreover, the distribution of the species therein tends to be erratic in comparison with the more consistently occurring miospores, possibly due to stress factors induced by fluctuating conditions in the IPBs Upper Devonian marine environment. By contrast, the land-derived (miospore) assemblages are readily applicable in a blostratigraphic context: they can be correlated precisely with the Devonian miospore biozonation scheme for Western Europe. In those terms, the sampled PQ strata are assignable to the Diducites versabilis-Grandispora cornuta (VCo) Biozone of late Famennian age; while the samples from the anoxic sequence at the base of the VSC belong to the Retispora lepidophyta-Verrucosisporites nitidus (LN) Biozone (latest Famennian = latest Devonian). The biochronostratigraphic data, in conjunction with the findings from earlier IPB studies, imply two appreciable palynostratigraphic breaks within the PQ. These are representative, respectively, of the lower Frasnian-middle Famennian interval and of part of the Strunian/upper Famennian. Speculation currently remains as to whether the inferred gaps are more apparent than real; i.e., whether one or both represent actual hiatuses in IPB sedimentation or are simply a manifestation of hitherto unsampled and/or non-palyniferous PQ strata.
Keyword Paleontology
Upper Devonian
Iberian Pyrite Belt
Organic-walled Microphytoplankton
Q-Index Code C1
Institutional Status UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Excellence in Research Australia (ERA) - Collection
2006 Higher Education Research Data Collection
School of Physical Sciences Publications
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Created: Wed, 15 Aug 2007, 07:50:01 EST