長野県北部,犀川中流地域に分布する新第三系の層序と構造

概要

論文の詳細を見る
The Cenozoic strata, Middle Miocene to early Quaternary in age, are widey distributed in the northwest side of the "Central Uplift Zone" in Nagano region, Central Japan. The Neogene strata are very thick (4,000 m) and intensely deformed (folded and faulted). They are stratigraphically classified, in descending order, as follows: [Table] The geologic structure of the Neogene system in the surveyed area is characterized by two overturned anticlinal structures, that is the Sai-kawa Anticline and the Noma Anticline. Between them there is a closed syncline, namely the Komiji Syncline with reversed limbs. There are remarkable differences in the thickness of the Upper Miocene strata between the west and east limbs of the Sai-kawa Anticline. The authors concluded that the zone of the Sai-kawa Anticline was situated upon a boundary between two basins subsiding at different rates during the Late Miocene time, and that the strata in this zone acquired an anticlinal structure as a result of sedimentation which gave rise to "thickness-difference". However, the overturned Sai-kawa Anticline as now seen in this zone has not been formed until Pliocene time when this district has been under the stress condition of horizontal (E-W) compression.
日本地質学会の論文
1976-12-30