Toshio Kawamura

A Late Permian coral reef complex, South Kitakami Terrane, Japan

Abstract The early Late Permian (Kubergandian to Midian) Iwaizaki Limestone of the South Kitakami Terrane, situated in Northeast Japan, represents a coral reef complex which was formed on a faulted-bank in an active continental margin. The reef-building organisms include cerioid and dendroid rugose corals, a fasciculate tabulate coral and solenoporacean algae as constructors, calcisponges, bryozoans and crinoids as bafflers, and Tubiphytes, Archaeolithoporella and cyanobacteria as binders. The biotic composition is more diverse than the other coeval reefs. Characterized by the existence of an obvious framework, this reef is similar to the Recent coral reefs and unique among Late Permian reefs, most of which are mainly formed by calcisponges and calcareous algae. The distribution of Late Permian reefs is closely related to the palaeoclimate. Coral reefs were developed mainly around the South China and Indochina continental masses between the Tethys Sea and the Panthalassa Ocean, in the tropics. While, calcisponge reefs and Tubiphytes -algal crust reefs were common in tropical to subtropical regions, and stromatolite-bryozoan reefs developed in arid areas. The gradational distribution of Late Permian organic reefs including localized development of coral reefs were probably caused by decreasing of the glaciers and changing of the ocean current systems.

Upper Permian coral reef and colonial rugose corals in northwest Hunan, South China

SummaryThe roles of Permian colonial corals in forming organic reefs have not been adequately assessed, although they are common fossils in the Permian strata. It is now known that colonial corals were important contributors to reef framework during the middle and late Permian such as those in South China, northeast Japan, Oman and Thailand. A coral reef occurs in Kanjia-ping, Cili County, Hunan, South China. It is formed by erect and unscathed colonies ofWaagenophyllum growing on top of one anotherin situ to form a baffle and framework. Paleontological data of the Cili coral reef indicates a middle to late Changhsing age (Late Permian), corresponding to thePalaeofusulina zone. The coral reef exposure extends along the inner platform margin striking in E-S direction for nearly 4 km laterally and generally 35 to 57 m thick. The Cili coral reef exhibits a lateral differentiation into three main reef facies; reef core facies, fore-reef facies, and marginal slope facies. The major reef-core facies is well exposed in Shenxian-wan and Guanyin-an sections where it rests on the marginal slope facies. Colonial corals are dispersed and preserved in non-living position easward. Sponges become major stabilizing organisms in the eastern part of Changhsing limestone outcrop in Kanjia-ping, but no read sponge reefs were formed. Coral reefs at Cili County in Human are different distinctly from calcisponge reefs in South China in their palaeogeography, lithofacies development, organic constitutuents, palaeoecology and diagenesis. The Cili coral reef also shows differences in age, depositional facies association, reef organisms and diagenesis from coral reefs in South Kitakami of Japan, Khorat Plateau of Thailand, and Saih Hatat of Oman. Although some sponge reefs and mounds can reach up to the unconformable Permian/Triassic boundary, coral reef at Kanjia-ping, Cili County, is the latest Permian reef known. This reef appears to had been formed in a palaeoenvironment that is different from that of the sponge reefs and provides an example of new and unique Permian reef type in South China, and could help us to: 1) understand the significance of colonial corals in Permian carbonate buildups; 2) evaluate the importance of coral community evolution prior to the collapse of reef ecosystems at the Permian/Triassic boundary; 3) better understand the effects of the biotic extinction events in Palaeotethys realm; 4) look for environmental factors that may have controlled reefs through time and space, and 5) provide valuable data for the study of Permian palaeoclimate and global evolutionary changes of Permian reefs and reef community.

Guadalupian algae-sponge reefs in siliciclastic environments - the reefs at Lengwu (South China) compared with the reef at Iwaizaki (Japan)

SummaryGuadalupian reefs occur locally in Guangxi, Guizhou, Yunnan and Western Zhejiang, South China. Two types of Guadalupian reefs can be recognized, one is developed in carbonate platforms, e.g. those in the juncture areas of Guangxi, Yunnan and Guizhou; the other occurs in a littoral clastic shelf. The Lengwu reef in Western Zhejiang is a representative of the latter type, which is a major topic of this paper. Lengwu algae-sponge reef, more than one hundred meters in thickness, are composed mainly of sponges, hydrozoans, algae, bryozoans, microbes and lime mud. Reef limestones sit on the mudstone interbedded with fine sandstone of the proximal prodelta facies and are overlain by coarse clasts of the delta front sediments. Lengwu reef displays a lens-shaped relief, dipping and thinning from the reef core, which is remarkably different from the surrounding sediments, showing a protruding relief. Sponges and microbe/algae form bafflestone, bindstone and framestone of the reef core facies. Fore-reef facies is characterized by lithoclastic rudstone and bioclastic packstone. Reef limestone sequence is composed of three cycles and controlled by sea level changes and sediment influx. Such reef is unique among the Guadalupian reefs in South China, but seems similar in some aspects to Iwaizaki reef limestones of south Kitakami in Japan. Algae and microbes growing around sponges to form rigid structure in Lengwu reef are a typical feature, which is distinctly different to Guadalupian reefs in a stable platform facies of Guizhou, Yunnan and Guangxi, South China.

Middle Pennsylvanian Rugose Corals from the Baird Formation, Klamath Mountains, Northwestern California

Abstract Four new species of colonial corals, one previously described coral, and two other unidentified species of coral have been recovered from the Baird Formation in the Klamath Mountains of northwestern California. The newly erected species are Heritschioides armstrongi n. sp., Pararachnastraea klamathensis n. sp., P. watkinsi n. sp., and P. kabyaiensis n. sp. These corals are associated with the fusulinids Millerella marblensis Thompson, 1944, Paramillerella Thompson, 1951, and Pseudostaffella Thompson, 1942, emend Groves, 1984, suggesting an early Atokan (Bashkirian) age. Both the coral and foraminiferal faunas bear a resemblance to those of similar age in the Brooks Range, Alaska, which could suggest geographic proximity between the two terranes at that time. These corals also represent the earliest known occurrence of the Family Durhamididae.

New Unusual Skeletal Structure in An Upper Carboniferous Rugose Coral, Klamath Mountains, Northern California

Abstract Unique among the Rugosa are specialized cyst-like structures in corals from an upper Carboniferous limestone within the Baird Formation in the Klamath Mountains, northern California. These structures, here referred to as septal cysts, occur mostly along the distal margins of the dark line extending along the axes of the major septa as seen in transverse section. However, they also commonly extend beyond the distal extent of those lines and may interrupt the fibrous coating in the more proximal parts of some septa. Their function is uncertain. Also present are small dissepiments which form a ring around the distal margins of the minor septa. These structures, however, do not appear to be related to the development of those septa. Some other taxa, including corals from the Bashkirian of Spain and the Kasimovian of Kansas, possess some specialized structures similar to those in the California specimens suggesting at least a remote relationship.