Lower Cretaceous (Upper Barremian-Lower Aptian?) Palynoflora from the Kitadani Formation (Tetori Group, Inner Zone of Central Japan)

Abstract

The Tetori Group, which crops out in the Inner Zone of central Japan, has been extensively studied for its rich floral and vertebrate fossil assemblages. The authors provide the first contribution to the palynoflora of the Kitadani Formation, which has been dated as late Barremian to early Aptian on the basis of the fresh- water bivalves recorded from it. The studied assemblage yields 45 genera and 41 species of spores and gymno- sperm pollen grains, some freshwater algae, one epiphyllous fungus, and various plant fragments. No angiosperm pollen grains were observed. Some forms described here in detail are not yet known from the lit- erature. They probably correspond to new species, but the scarcity of the specimens has caused us to place them temporarily in open nomenclature. This palynological study adds new data to the present knowledge on the Barremian-Aptian Tetori-type Paleoflora of eastern Asia. The authors compare the palynological inventory with recently published data obtained from the Barremian strata of the Choshi Group, the Outer Zone of Southwest Japan. Then, they situate the results among the previous paleoenvironmental reconstructions of the Tamodani Flora, and confirm a warm temperate and moderately humid climate, with locally drier conditions. Even if some elements of the assemblage suggest transportation, all of them are of continental origin and con- firm a fluvio-lacustrine environment for the deposition.