有明海々底の第四系と花粉学

Pleistocene sediments under the bottom of the Ariake sea, which are confirmed from eighteen boring cores, consist of three formations. Stratigraphic classification is as follows. Alluvium deposits unconformity Pumice bearing tuff (New Aso pyroclastic rock) unconformity Upper formation (Unzen pyroclastic rocks) unconformity Lower formation (Unzen pyroclastic rocks) The lower formation is mainly composed of the pyroclastic rocks of hornblende biotite andesite. Silt or clay beds, 0.1 to 5 m in thickness, lie in several horizons. Judging from the boring no. B-3, the lower formation is estimated at about 25 m in thickness. There has been found many spores, pollen grains, and phytoplankton from silt or clay, 10 cm to 5 m in thickness, in several horizons. The upper formation is mostly volcanic sediments, that is, volcanic ashes, silt, sand, and gravel originated from volcanic ejectas. The lowermost part consists of slightly carbonized woods bearing humus silt or sand, which greatly varies in thickness. The thickness of this formation varies from 1.1 to 12m. Humus silt or sand and tuffaceous silt of this formation contain also many spores and pollen grains which are divided into two pollen-spore assemblages. Many spores and pollen grains from twenty seven samples of eighteen boring cores are palynologically and biostratigraphically studied. Three pollen-spore assemblages are divisible. The A type of pollen-spore group consists mainly of Pinus, Gleicheniaceae, Tsuga, Picea, Ilex, Fagus, Polypodiaceae etc. and is derived from the upper and middle part of the upper formation. The B type of pollen-spore assemblage is composed mostly of Taxodiaceae, Alnus, and Picea. Its stratigraphic horizon corresponds to the lowermost part of the upper formation. Main constituents of the C type of pollen-spore group are Quercus, Castanea, Chenopodiaceae, Pinus, Polypodiaceae etc. They are found in the lower formation.
長崎大学教養部紀要. 自然科学. 1968, 9, p.33-44