海進を反映する化石フジツボの産状 : 仙台市南西部の茂庭-碁石地域に分布する中新統名取層群の例

抄録

Modes of occurrence of fossil barnacle reflecting transgression are discovered from the basal part of the Miocene Natori Group in the Moniwa-Goishi area. The group exhibits the transgressive sequence from subaerial lavas and volcaniclastics to shoreface-shelf deposits in ascending order. Fossil barnacles show autochthonous (in situ individuals on gravel surface) to allochthonous (disarticulated fragments) occurrences. Autochthonous barnacle species, Balanus bisulcatus and Concavus sendaicus are found from bay deposits of the early transgressive stage, and the overlying ravinement deposits formed during marine flooding, respectively. Discoveries of autochthonous barnacles make possible reconstruction of depositional environments and paleoecolgy of extinct barnacles.