丹沢山地のグリーンタフに関する研究(その1) : 北部地域の層序と構造

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The stratigraphical study of the Neogene system, the so-called "Green tuff", distributed in the northern region of the Tanzawa massif, Central Japan was carried out by the present writers. The Neogene system in the surveyed area can be devided into the following two parts, namely, the Tsuru group which mainly consists of volcanic materials, and the Iwatonosan formation (nearly corresponding with the Nishikatsura group in the past) which consists mainly of conglomerates. The former is conformably overlain by the latter in this region. The Tsuru group with thickness of 12,000 m consists of a large amount of basaltic to andesitic pyroclastic rocks and lava flows. The Iwatonosan formation mainly consists of conglomarates intercalated with sandstone and mudstone, and its thickness reaches more than 1,000 m. Moreover, this formation can be divided into two members according to the differences in the sort of pebbles contained in it. The details of facies of each member were described. As to the Tsuru group, the transition of the volcanic activities of those days were deduced from the horizontal and the vertical facies changes. Rock facies of some quartz diorite bodies distributed in the western part of the surveyed area are very similar to that of larger one which intrudes into the center of the Tanzawa massif. The Neogene system in the surveyed area generally has a strike of NE-SW or E-W direction with northward dip, but the area is subdivided into several blocks by many faults. Of these, fault systems with strike of NEE-SWW or NW-SE which is developed in the central part of the surveyed area are dip slip faults accompanied with andesite, porphyrite, and dolerite dykes. On the contrary, other faults system with strike of NE-SW developed in the northern margin and those with strike of NEE-SWW in the southern margin of this region are diagonal slip faults without accompanying igneous intrusion. The nature of each fault was described, and its origin was considered. On the mode of occurrence and the origin of schistose rocks were also mentioned. The source rocks of shistose rock except those occuring as roof-pendants in a quartz diorite body belong to the Tsuru group, and it is difficult to recognize that they are regional crystalline schist.
日本地質学会の論文
1973-07-01

丹沢山地のグリーンタフに関する研究(その1) : 北部地域の層序と構造

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