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Comments on researches of Paleo-Ryoke belts

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Akira Ono*
Abstract : The Paleo-Ryoke belt is a missing geological unit (tectonic land) proposedby Ichikawa (+31*) in order to explain Mesozoic paleo-geographic features of Southwest
Japan. The Paleo-Ryoke belt was located between the Ryoke and Sanbagawa belts,
which was mainly composed of basement rocks underlying the Honshu geosynclinal
sediments. On the other hand, Kimura (+32*) suggested that the geology of the
Paleo-Ryoke belt was similar to that of the Abukuma and South Kitakami belts. Thissuggestion is consistent with the recent Paleo-Ryoke belt described by Takagi andShibata (+330). Nevertheless, the Paleo-Ryoke belt is a complex terrane consisting ofvarious kinds of rocks with various ages. It is required to divide the Paleo-Ryoke belt
into fundamental geologic units. In this paper, the Higo-Abukuma belt and KinshozanSouth Kitakami belt are proposed instead of the Paleo-Ryoke belt.
Key words : Southwest Japan, missing tectonic land, Paleo-Ryoke belt, Higo-Abukuma
belt, Kinshozan-South Kitakami belt

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cd#e$ .$ .+.῎.,*Ichikawa, K. and Kojima, G., +30., A crustal proﬁleof Southwest Japan inferred from geological
data. Internat. Geol. Congr., India, part IV, +῎+-.
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Kobayashi, T., +3.+, The Sakawa orogenic cycle
and its bearing on the originof the JapaneseIslands. J. Fac. Sci. Imp. Univ. Tokyo, Sec. ,, /,,+3῎/12.
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Matsuda, T. and Uyeda, S., +31+, On the Paciﬁc-type
orogeny and its model. Extension of the paired
belts concept and possible origin of the marginal seas. Tectonophysics, ++, /῎,1.
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Miyashiro, A., +30+, Evolution of metamorphic
belts. J. Petrol. ,, ,11῎-++.
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Suzuki, K. and Adachi, M., +332, Denudation history of the high T/P Ryoke metamorphic belt,
Southwest Japan : constrains from CHIME
monazite ages of gneisses and granitoids. Jour.
Metamorphic Geol., +0, ,-῎-1.

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Ogawamachi Group in the Kanto Mountains,
Japan. Ann. Rep. Ins. Geosci. Univ. Tsukuba, .,/-ῌ/0.

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