Biotic Association Research Articles

Triassic mid‐oceanic sedimentation in Panthalassa Ocean: Sambosan accretionary complex, Japan

Abstract The Sambosan accretionary complex of southwest Japan was formed during the uppermost Jurassic to lowermost Cretaceous and consists of basaltic rocks, carbonates and siliceous rocks. The Sambosan oceanic rocks were grouped into four stratigraphic successions: (i) Middle Upper Triassic basaltic rock; (ii) Upper Triassic shallow‐water limestone; (iii) limestone breccia; and (iv) Middle Middle Triassic to lower Upper Jurassic siliceous rock successions. The basaltic rocks have a geochemical affinity with oceanic island basalt of a normal hotspot origin. The shallow‐water limestone, limestone breccia, and siliceous rock successions are interpreted to be sediments on the seamount‐top, upper seamount‐flank and surrounding ocean floor, respectively. Deposition of the radiolarian chert of the siliceous rock succession took place on the ocean floor in Late Anisian and continued until Middle Jurassic. Oceanic island basalt was erupted to form a seamount by an intraplate volcanism in Late Carnian. Late Triassic shallow‐water carbonate sedimentation occurred at the top of this seamount. Accumulation of the radiolarian chert was temporally replaced by Late Carnian to Early Norian deep‐water pelagic carbonate sedimentation. Biotic association and lithologic properties of the pelagic carbonates suggest that an enormous production and accumulation of calcareous planktonic biotas occurred in an open‐ocean realm of the Panthalassa Ocean in Late Carnian through Early Norian. Upper Norian ribbon chert of the siliceous rock succession contains thin beds of limestone breccia displaced from the shallow‐water buildup resting upon the seamount. The shallow‐water limestone and siliceous rock successions are nearly coeval with one another and are laterally linked by displaced carbonates in the siliceous rock succession.

Paleoecology of the Permian (Wolfcampian) Phylloid Alga Calcipatera from an In Situ Occurrence in Kansas, U.S.A.

In situ occurrences of the calcareous marine phylloid alga Calcipatera cottonwoodensis in the Permian Cottonwood Limestone Member (Beattie Limestone) occur in Greenwood County, Kansas, in association with platy algal packstones, which are the phylloid algal facies most commonly described in the literature. The in situ algal facies occurs in the upper 0.45 m of an exposure where it is overlain and underlain by algal packstones composed of transported and broken fragments of Calcipatera cottonwoodensis.
 Calcipatera cottonwoodensis colonized coarse carbonate sands or carbonate mud substrates. During growth, carbonate mud accumulated in the cup-shaped thalli, and death followed when the rate of sedimentation exceeded the rate of algal growth. The three lithologies--substrate, cup-filling, and smothering--are easily recognized on polished surfaces.
 Other members of the Calcipatera cottonwoodensis benthic community are Shamovella, encrusting and boring algae, foraminiferids, fenestrate and ramose bryozoans, brachiopods, bivalves, gastropods, trilobites, ostracodes, and echinoids. This occurrence and biotic association compares well with those described by Toomey (1976) and Wahlman (1988, 2002) from the Permian (Wolfcampian) of West Texas.

Biotic association and palaeoenvironmental reconstruction of the “Loma del Pterodaustro” fossil site (Early Cretaceous, Argentina)

A sedimentological analysis of the basal section of the Early Cretaceous, lacustrine LagarcitoFormation at “Loma del Pterodaustro” (San Luis, Argentina) and a summary of its biological components are presented. Three sedimentological facies can be recognized in the basal sequence of the Lagarcito Formation. Fossil remains are particularly abundant in laminated claystones of a facies interpreted as deposits formed in offshore areas of the lake. The preservation of delicate structures allows recognition of these deposits as a Konservat Lagerstätte. Up to now, rocks at “Loma del Pterodaustro” have yielded plants, conchostracans, semionotid and pleuropholid fishes, pterodactyloid pterosaurs, and a variety of invertebrate traces. The chronology of the Lagarcito Formation is discussed and it is concluded that this unit is of Albian age. The palaeoenvironment of deposition of the basal sequence of the Lagarcito Formation at “Loma del Pterodaustro” is interpreted as a perennial, shallow lake developed within an alluvial plain, under semiarid climatic conditions.

Tardigrades of the Australian Antarctic Territories: The Larsemann Hills, East Antarctica

A survey of the terrestrial tardigrades inhabiting algae, lichens, and mosses in the Larsemann Hills, East Antarctica was conducted at 61 sites during the austral summer of 1987. Five genera and six species of Tardigrada were recovered. Statistical analysis of biotic association was conducted and for most species-pairs, tardigrades occur randomly with respect to each other. The hypothesis is proposed that distribution of tardigrades in the Antarctic is more strongly influenced by dispersal capabilities than by climatic factors or biotic interactions. East Antarctica is a series of widely dispersed, small, ice-free areas surrounded by a continuous sea of mostly frozen water. These islands, scattered along the Antarctic circle, provide a discontinuous habitat for terrestrial organisms. Tardigrade research in East Antarctica has been conducted entirely within the current century. Richters (1904, 1907) described the first tardigrades from this area, and later he listed 13 species, providing also the first discussion of distribution. Over 50 years passed before Morikawa (1962) and Sudzuki (1964) reported finding tardigrades near the Japanese base at Syowa, Queen Maud Land. Korotkevich (1964) found, but did not identify, tardigrades in bodies of freshwater in the Bungar Hills and the Obruchev Hills of Wilkes Land. Thomas (1965) found an unidentified Macrobiotus in the meltwater pools near the abandoned Wilkes Base on the Clark Peninsula. Another decade passed without reports of tardigrades from East Antarctica, until Sudzuki (1979) again described the animals from the Syowa area. In the early 1980's, the ecology of Antarctic tardigrades was discussed by Everitt (1981) and Miller (1983). Dastych (1984) expanded the list of species known from Antarctica and the sub-Antarctic islands and described eight species new to science. Gardiner & Pidgeon (1987) reported collections at sites in East Antarctica; this paper is the culmination of that work. The tardigrade fauna of the Vestfold We are grateful to the Australian National Antarctic Research Expeditions (ANARE) and to the personnel of the Australian Antarctic Division, especially Martin Betts, for logistical support and advice, and for making the expedition possible, and to Dr. Rod Seppelt for identification of the mosses and lichens. Publication costs, in part, are being met by a grant from the Spencer-Tolles Fund of the American Microscopical Society. TRANS. AM. MICROSC. SOC., 113(2): 142-160. 1994. ? Copyright, 1994, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.251 on Thu, 14 Jul 2016 06:20:29 UTC All use subject to http://about.jstor.org/terms VOL. 113, NO. 2, APRIL 1994 Hills near Davis Base was surveyed by Miller et al. (1988); they discussed the ecology, distribution, and association patterns. Dastych (1989) reported on specimens collected in the area of Casey Station. Ryan et al. (1989) extended the known distribution of five species with a report from Robertskollen near the South African base of Sanae. Dastych et al. (1990) described two new species from the same area of Robertskollen. Dastych (1991) redescribed the species Hypsibius antarcticus, reducing confusion between this very common species and Hypsibius arcticus. Tardigrade research at locations other than East Antarctica was reviewed by Miller et al. (1988). Despite these efforts, many of the ice-free areas of East Antarctica remain unexplored and unsurveyed for tardigrades. The present report constitutes the first records of tardigrades from the Larsemann Hills on the Ingrid Christensen Coast of East Antarctica.

Tubiphytes-archaeolithoporella-girvanella reefal facies in Permian buildup, Mino terrane, central Japan

The Lower to Middle Permian Okumino buildup of the Mino terrane, central Japan, formed a carbonate cap on a seamount which was sitting in an open-ocean realm. Microscopic examination reveals considerable amounts of Tubiphytes, Archaeolithoporella, and Girvanella in these rocks. These low laminar encrusting organisms together with cystopore bryozoa and syndepositional radial-fibrous cements formed bindstones. The bindstones are interpreted as having formed wave-resistant algal reefal mounds on the marginal terrace of the Okumino buildup which also has the lagoonal flat, sand bar or shoal, and foreslope facies. The Okumino buildup is closer in its biotic association of major encrusting organisms to the Trogkofel buildup in southern Alps than to the Capitan Reef Complex in New Mexico and Texas. The similarity implies that Tubiphytes and Archaeolithoporella were the most predominant and significant rock-forming encrusting organisms in Early to early Middle Permian times.