Composition of algae in the Middle-Upper carboniferous skeletal mounds on the Shchuger river

Lithological-paleoecological study of the Mid–Upper Carboniferous reef limestones from the section «Verkhnie Vorota» on the Shchuger River revealed the complex of green phylloid algae Ivanovia tenuissima Khvorova, Eugonophyllum konishi Kulik, Anchicodium gracile Johnson, which are directly involved in the construction of buildup frameworks. Problematic Tubiphytes, rare cyanobacteria Bevocastria sp., dasiclads Clavaporella sp., Pseudoepimastopora cf. likana (Kochansky et Herak), Pseudoepimastopora sp., Asphaltinella cf. horowizi Mamet et Roux, phylloid Neoanchicodium sp. and red Ungdarella uralica Maslov, Komia sp., Flugelia johnsoni (Flugel) algae were associated with them. The revealed algal complex indicates the existence of a shallow warm sea with good bottom illumination and weak water movement.

Remarks on the Cortical Structure of Late Paleozoic “Phylloid Algae”

The cortical structure of the green anchicodiacean alga Anchicodium in the Pennsylvanian Dueñas Formation of the Cantabrian Zone (northwestern Spain) is described and illustrated. Anchicodium is characterized by a broad phylloid or leaflike calcified thallus, consisting of a bilateral cortex and a poorly calcified central medulla. The organization and morphology of the cortical system have been revealed with great detail using cathodoluminescence microscopy. Anchicodium cortex is composed of up to three (four?) orders of dichotomized branched cortical siphons that are usually swollen at the center; primary siphons are bulbous and are followed by elongate cylindrical siphons. Cortical siphons are preserved as dull-bright luminescent molds filled with micrite or microsparite, and contrast sharply with the surrounding non-luminescent calcite infilling the intersiphonal spaces, originally occupied by aragonite. Anchicodium in the Dueñas Formation exhibits a variety of preservational stages. Through a compilation of the taxonomic nomenclature and morphologic re-interpretations, it is concluded that some late Paleozoic anchicodiacean algae might represent diagenetic stages of Anchicodium or Eugonophyllum without any taxonomic significance. This conclusion is suggested particularly for the taphotaxon Ivanovia.

Study on Paleoecology of Late Pennsylvanian Phylloid Algae in South Guizhou, China

Pennsylvanian phylloid algal reefs are widespread and well exposed in south Guizhou, China. Dense networks of closely living phylloid algae induced community restriction on seafloor and organisms seldom survived in such environment. Algal reefs in Guizhou differ from examples reported to date by high biodiversity. This contrasts to the “poisoning hypothesis” and chemical defense was not pronounced. Phylloid algae were able to thrive over a large depth range. Delicate framework formed by upright blades often occurred in calm deepen waters. Blades became larger and fleshy in moderately agitated environment and formed isolated, wide, cup-shaped framework. Large blade size could capture much more sunlight to improve rate of growth and calcification. But successive progressively shallower water may have arrested phylloid algae growth. Thinner, small blades grew closely packed and juxtaposed near and above one another in a wave-dominant environment, producing dense framework clusters to prevent wave destruction.

Facies interpretation of Middle Carboniferous to Lower Permian Pope succession limestone of Cache Creek Group, Fort St. James, central British Columbia

Lithostratigraphy and microfacies of the Bashkirian to Asselian Pope succession limestone of the Cache Creek Group near Fort St. James, central British Columbia, were lithologically grouped into five facies associations A to E. On the basis of fusulines and conodonts, facies associations A to D and the lower part of facies association E are time-equivalent, ranging from the lower Bashkirian to lower Kasimovian, and the upper part of facies association E is dated as upper Gzhelian to Asselian. The Pope succession limestone is interpreted to have been built on a basaltic basement of an oceanic plateau or seamount in an open-ocean realm. The limestone is devoid of terrigenous grains, is associated with basaltic rocks, and laterally grades into deeper-water spicular cherts. Microfacies analysis of facies associations A to E showed that they exhibit characteristic facies of (A) deep-water basinal setting, (B) marginal basin to lower slope, (C) shallow-subtidal bank margin, (D) peritidal algal mound on the bank margin, and (E) shallow-subtidal bank margin to intertidal lagoonal flat,. Moscovian to Asselian rocks of facies associations C, D, and E record an upward increase of low-relief encrusting calci-microbes as rock-builders. This tendency is closely correlated with that in limestone buildups mapped from the Panthalassan Ocean. The abundance of phylloid algal plates and the reefal facies of the Moscovian rocks of facies association D are the same as the reef-building phylloid algae of the Bashkirian to Sakmarian limestone of both the Tethyan and Panthalassan oceans. The Pope succession limestone has many similarities in tectonic, stratigraphic, sedimentologic, and paleontologic aspects to the Akiyoshi buildup, a representative Panthalassan buildup in a Permian subduction-related accretionary complex in Japan. The timing of the increasing importance of the calci-microbes and phylloid algae in the Pope and Akiyoshi buildups is also correlatable.