Underlying maintenance mechanisms of reef ecosystems in Early and Middle Palaeozoic, and earliest Mesozoic time: Elucidation of ecosystem-generatingprocesses under greenhouse-Earth environments

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This research project deals with greenhouse reefs typical of individual ages. In addition, the Scleractinia, which are the most representative reef-builders, were examined in light of their modes of asexual reproduction and growth.1. As to the Lower Ordovician reefs, special attention was paid to the construction traits of reefs that were made up mainly of large, phylogenetically pioneer, skeletal reefs and stromatolite reefs. Detailed regional and age-specific ecological successions were examined, along with the chief causes of the lateral coexistence of both large skeletal and microbial reefs at a particular geologic time.2. Concerning the Lower Devonian examples, reefs were especially remarkable in their main constituents, and the immediate genetic mechanisms of reefal limestones were deciphered in terms of biotic interactions. I paid special attention to what kinds of habitat microenvironments caused what kinds of changeovers in biotic interrelations, and how they were consequently … More recorded in reefal limestones. Finally, the relevant reefal limestones were summarized in view of the genesis of the carbonate components, as well as the constructive and destructive roles in reef textures and structures.3. Lowest Triassic thrombolite reefs clearly express their palaeoenvironmental implications immediately after the end-Permian extinction. High-resolution fluctuations were reconstructed on the basis of (1) the distinctive unconformable contact between the Permian and Triassic, (2) successive changes in microbialite texture and structure within a particular trend, and (3) δ^<13>C fluctuation patterns and their global correlation, particularly with those at the GSSP.4. The study of extant scleractinians produced insights into essential phenomena regarding both asexual modes of reproduction and the resultant growth modes, as well as their ecological response to deteriorating environmental changes.The above-mentioned findings are also of great importance for understanding the self-creation processes of geobiological environments throughout geologic time and the true nature of the modern Earth. Less