Stratigraphy of the Quaternary Ash and Pumiceous Products in Southwestern Hokkaido, N. Japan (The Pliocene and Quaternary Geology of Hokkaido, 1st Report)
Year: 1972
Type: article
Abstract: AVolcanoes geCalderas O"/OOKm Fig. 1 Distribution of the Quaternary Volcanic Chains.'" Noboribetsu, Ponayoro I and II, Shadai, Morino aiid Shikotsu Formations (Table 1).In fact, each ash or pumice fall member is composed of several separate falls with fairly distinct laminations.Each of these is undot}btedly the product of a volcanic explosion associated with an imfnense quantity of steam.Nevertheless, this kind of volcanic product, at least those parts most distant from the center of activity, may be regarded as a kind of aeolian deposit, transported by wind in the stratosphere and finally depositecl on the land surface.Such pumice and ash fali are chiefly distributed eastward from the supposed center of explosion, probably reflecting a prevailing west or soi.ithwest stratosphere wind at the time of eruptioR.In addition, the volcanic ash or pumice falls are intercalated with numerous n,on-volcanic aeolian deposits such as rock flour or loess.These beds lool< like sandy loam and their boundary with volcanic aslii falls is almost always very sharp, with little evidence of intermixing.The hiatus between the two fnay thus represent a considerable amount of time (Table 1).Pvmiice flows or ash fiows are always pure volcanic products which include both large and small pumices together with varying amounts of exotic rock STRATIGRAPHY OF THE QUATERNARY VOLCANIC PRODUCTS, SW HOI<I<AIDO 68I .V T I{ .-TlC; H .t i, HICAL SE ･2 t' ￡. b: CE O }' i, l' }l ]CEe L/ S VO 1.
Language: English
Subfield: Geology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W55433725