The Doi Chiang Dao Limestone: Paleo-Tethyan Mid-oceanic Carbonates in the Inthanon Zone of North Thailand

The Doi Chiang Dao Limestone distributed in the Inthanon Zone of North Thailand represents mid-oceanic carbon-ates formed upon seamount (or oceanic plateau) bases in the Paleo-Tethys Ocean. It consists essentially of oceanic island basalt at the base and overlying thick, pure and massive carbonates that are essentially free from continental siliciclastic input. Shallow-marine microfacies such as bioclastic grainstone, ooid grainstone, oncoidal rudstone and bioclastic packstone, are dominant in the carbonates. The limestone records an almost continuous, Carboniferous-Permian foraminiferal faunal succession of a Paleo-Tethyan pelagic shallow-marine setting, ranging from the Visean (Mississippian/Early Carboniferous) to the Changhsingian (latest Permian) over approximately 90 m.y. Moreover, con-odonts suggest that it could range up to the Dienerian (early Early Triassic) crossing the Permian-Triassic boundary. The Doi Chiang Dao Limestone is comparable in origin with huge carbonate bodies distributed in the Central zone of the Changning-Menglian Belt of West Yunnan, Southwest China and well-studied Panthalassan seamount carbonates (such as the Akiyoshi Limestone) found within accretionary complexes in the Japanese Islands. It is regarded as