First report of hexactinellid dictyosponges and other sponges from the Upper Mississippian Bangor Limestone, northwestern Alabama

Rigby, J. Keith; Keyes, Richard

doi:10.1017/s0022336000019983

Cited by 6 publications

(1 citation statement)

References 3 publications

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“…The inclusion of sponges in the animal kingdom has been supported by recent molecular phylogeny studies using 16S rRNA (Wainright et al, 1993) and 28S RNA (Christen et al, 1991). Their relegation to an early branch on the metazoan tree has fed the expectation of a Precambrian fossil record (for a review see Rigby, 1986). Of the many re ported spicules from Proterozoic sediments most have proven to be volcanic shards or other inorganic crystals (Pickett, 1983).…”

Section: Introductionmentioning

confidence: 99%

Long expected sponges from the Neoproterozoic Ediacara fauna of South Australia

1996

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New fossils from the Neoproterozoic Ediacara fauna of South Australia are interpreted as the oldest known hexactinellid sponges. They occur within the Ediacara Member of the Rawnsley Quartzite (Pound Subgroup) from several locations in the Flinders Ranges. The new genus, Palaeophragmodictya, is characterized by disc-shaped impressions preserving characteristic spicular networks and is reconstructed as a convex sponge with a peripheral frill and an oscular disc at the apex.

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Section: Introductionmentioning

confidence: 99%

Long expected sponges from the Neoproterozoic Ediacara fauna of South Australia

1996

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A biodetrital coral mound complex: Key to early diagenetic processes in the Mississippian Bangor Limestone

Haywick

Kopaska-Merkel

Bersch

2009

Carbonates and Evaporites

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The Bangor Limestone is a Mississippian (Chesterian) shallow marine carbonate formation exposed over a large portion of the Interior Low Plateaus province of northern Alabama. It is dominated by oolitic grainstone and skeletal wackestone and packstone, but in one outcrop near Moulton, Alabama, the Bangor contains a five m thick, 25 m wide, oolite -biodetrital mound -tidal flat succession. This sequence is interpreted as a 4th order sea level cycle.Four petrofacies (oolite, mound, skeletal and mudstone/dolomicrite) and four diagenetic phases (iron oxide, fibrous calcite cement, calcite spar cement and dolomite) are distinguished at the study site. Iron oxide, a minor component, stained and/or coated some ooids, intraclasts and skeletal components in the oolite petrofacies. Many of the allochems were stained prior to secondary cortical growth suggesting a short period of subaerial exposure during oolite sedimentation. The oolite petrofacies also contains minor amounts of fibrous calcite cement, a first generation marine cement, and rare infiltrated micrite that might represent a second phase of marine cement, or a first phase of meteoric cement (i.e., "vadose silt") (Dunham 1969). Intergranular pore space in all four petrofacies is filled with up to three phases of meteoric calcite spar cement. The most complete record of meteoric cementation is preserved within coralline void spaces in the mound petrofacies and indicates precipitation in the following order: (1) non-ferroanscalenohedral spar, (2) ferro an drusy spar (0.1-0.4 wt% Fe 2 +) and (3) non-ferroan drusy spar. The first scalenohedral phase of meteoric cement is distributed throughout the oolite and mound petrofacies. The ferro an phase of meteoric.calcite is a void-filling cement that is abundant in the mound petrofacies and less common in the skeletal and mudstone/dolomicrite petrofacies. Non-ferroan drusy calcite is pervasive throughout the Bangor Limestone at the Moulton study site.Growth ofthe fourth diagenetic phase, dolomite, was the dominant event in the micrite/dolomicrite petrofacies, particularly just below an irregular surface overlain by a brecciated interval. The irregular surface is interpreted as an exposure surface. Three phases of dolomite occur below the exposure surface. The majorityis finely crystalline, anhedral, and enriched in Si 4 +, criteria which support a supratidal or mixed hypersaline\meteoric origin. Secondary phases of coarser euhedral non-ferroan and ferro an dolomite are restricted to fenestrae and other voids in the micrite/dolomicrite petrofacies and were precipitated during subsequent meteoric diagenesis, Diagenesis of the Bangor Limestone at the Moulton outcrop was dominated by synsedimentary and very early meteoric processes driven by periods of subaerial exposure. Large voids within the mound petrofacies were particularly important, as they remained open long enough to record a more detailed early meteoric cement stratigraphy that might not be evident in Bangor Limestone outcrops elsewhere in Alabama.

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Eponges siliceuses du Dévonien supérieur de la Rade de Brest (France)

Pickett

Plusquellec²

1998

Geobios

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First report of hexactinellid dictyosponges and other sponges from the Upper Mississippian Bangor Limestone, northwestern Alabama

Cited by 6 publications

References 3 publications

Long expected sponges from the Neoproterozoic Ediacara fauna of South Australia

Long expected sponges from the Neoproterozoic Ediacara fauna of South Australia

A biodetrital coral mound complex: Key to early diagenetic processes in the Mississippian Bangor Limestone

Eponges siliceuses du Dévonien supérieur de la Rade de Brest (France)

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