ロシア, サハリン島南部, マカロフ地域およびチェホフ地域における前期中新世の不整合とその意義 Early Miocene Unconformity in the Makarov and Chekhov Areas, Southern Sakhalin Island, Russia, and its Implication
This paper reviews the Tertiary chronostratigraphy and paleoenvironments in the Makarov and Chekhov areas, southern Sakhalin Island, Russia, emphasizinsubsidence and uplifting history. After the late Cretaceous to Paleocene accretion of fore-arsediments and trench-fills, subsidence started in the middle Eocene in the Chekhov area, on the west coast of Sakhalin, and in the late Oligocene in the Makarov area, on the east coast of Sakhalin. This subsidence culminated perhaps during the late Oligocene, followed by uplifting to the surface with increasing eruptions of tholeiitic or calcalkaline basalt to andesite. Subsidence in the two areas started again in the late early Miocene at a very rapid rate, followed by slow subsidence or uplifting after the adjacent Chishima (Kuril) and the Japan Sea Basins ceased opening at about 15 Ma. The first subsidence perhaps implies the rifting of the back-arc or intra-arc area of Sakhalin Island, and the second subsidence implies the opening the Chishima and Japan Sea Basins. The early Miocene unconformity, which separates two cycles of Tertiary subsidence and uplifting, also occurs along the Japan Sea side areas of Hokkaido and Tohoku Provinces, northeast Japan, and is thought to record a tectonic uplifting with the upwelling of the athenospheric mantle, or by other unknown processes related to the opening of the back-arc basins.
地學雜誌 109(2), 262-280, 2000-04-25
Tokyo Geographical Society