The change of oceanic plate motion might be recorded in the strata of arc-trench system, because the difference of thickness is remarkable between the oceanic plate and the sedimentary bodies in the basin as shown in Fig. 1.
Plate motion during the least 42 Ma: JACKSON et al. (1975) presented the periodicitic changes of loci of individual shield volcanoes along the Hawaiian chain (Fig. 3a). They concluded that the Pacific plate has been subjected to oscillatory, but principally clockwise, rotations of horizontal stress components as shown in Fig. 3c. In this paper, it is presumed that the oscillatory curve in Fig. 3c means the periodicities of real rotational motions of the Pacific plate. The changing point (maxmum or minimum in the curve) between two torque is called "JACKSON episode".
Plate motion during the least 175Ma: Relative motions during late Mesozoic and Cenozoic were calculated by ENGEBRETSON (1982) between oceanic and continental plates in the Pacific region based on the magnetic anomaly lineations, fracture zone trends and hotspots. MARUYAMA et al. (1982) presented the relative motion of the Pacific, Kula and Farallon plates with respect to Eurasia plate at the Japanese Islands (Fig. 13 (2)-(5)) using the ENGEBRETSON'S data.
On the basis of these history of the plate motion, the various phenomena, such as igneous activities, tecton-ism, sedimentation and sea level change, are correlated and discussed for the Cenozoic and Mesozoic in the basins of the Japanese Islands which have precise chronologic discrimination. The JACKSON episodes of the changing time of the Pacific plate motion may correspond to the events of igneous activity (Fig. 4 (1) (2)), the change of stress field (Fig. 4 (3)) and the intensity of tectonism, such as the period of unconformity, deformation or movement (Fig. 6 (3), 9). JACKSON episodes also control the rise and fall of sedimentary basin, that is, the variation of sedimentation (Fig. 5-8), depositional rate (Fig. 7-9), hiatus (Fig. 6-8), subsidence (Fig. 7) and paleobathymetry (Fig. 8). Moreover, the same relationships can be obtained between the plate motion and geologic events for the long history in the basin. Grobal cyclic curve of relative sea level change proposed by VAIL et al. (1977) (Fig. 10) records the changes of plate motion (Fig. 12, 13). The cyclic curves can also explain some phenomena of transgression and regression, but not the intensity of the phenomena in the basins of arc-trench system.
The agreements among these episodic periods or events suggest that oceanic plate motion is the most important factor for the various geological phenomena in the sedimentary basin of arc-trench system. The images of the process, mechanism or effect are also presented for these relationships based on the plate motion.

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The Cretaceous magnetite (apatite-actinolite) ore deposits of the Chilean territory are grouped in a N-S narrow band, extended between latitudes 25° and 31°S. This paper relates the principal stage of iron mineralization to a period of crustal extension and mafic magmatism (125-110 m.y.), associated to a low and uniform convergence speed of the lithospheric plates (FRUTOS, 1981).
Several hypothesis proposed for the genesis of these deposits are discussed. As a general conclusion, the Cretaceous iron mineralization is considered to be a result of the coincidence of particular tectonic and magmatic conditions. Hydration of dry mafic magmas by deep ground water probably had a major role in the genesis of the deposits. As a general principle, it is postulated that dry mafic magmas, with low Fe clinopyroxene as dominant ferromagnesian phase, have a higher iron mineralization potential than the hydrous hornblende-rich ones, where a larger part of iron is retained by the silicate phase.

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The "PUMOS" hypothesis advocates that the mean settling-flux of biogenic entities in the ocean, i.e., PUMOS (Primitive Undifferentiated Metalliferous Organic Sediment), is the common parental source materi-al for the kuroko and manganese deposits as well as oil deposits occuring in the Neogene "Green Tuff" region of Japan (KAJIWARA, 1982, 1983;KAJIWARA and HIRAYAMA, 1983a, b).In this paper is made a further attempt to extend the "PUMOS" hypothesis to the origin of some other important types of ore deposits in nature, which include Besshi-type stratiform sulfide deposits, hydrothermal vein-type deposits and pyrometasomatic skarn-type deposits from Japan and recent submarine hydrothermal sulfide deposits such as those from Red Sea and East Pacific Rise. The author's contentions reached by this study are as follows.(1) PUMOS is diagenetically differentiated to create the following two major types of primitive ore deposits, i.e., "diagenetic residual-type deposits" of which the kuroko deposits are representative and "diagenetic released-type deposits" in which metals relatively depleted in the kuroko deposits are concentrated. Ore-petrochemical characteristics of the two primitive diagenetic deposits are quantitatively distinguishable definitely in the systems of Fe-Cu-(Zn+Pb) and Cu-Zn-Pb (Figs.1 and 2 in the text).
(2) All the natural ore deposits studied in this paper are fairly consistent in ore-petrochemistry either with the "diagenetic residual-type deposits" or with the "diagenetic released-type deposits" (Figs. 3 to 9 in the text).It thus appears highly probable that a majority of ore deposits in nature are ultimately of PUMOS origin rather than of magmatic origin as what has long been assumed tacitly.
(3) In conclusion is proposed a new "diagenetic differentiation" scheme to account for the ore-type diversity in nature (Fig.10 in the text). The traditional "magmatic differentiation" scheme may be of help to realize modi-fications and remobilizations of the primitive diagenetic ore deposits within the earth's crust.

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Futagojima granodiorite, which was previously thought to be a part of Cretaceous Ryoke granitoids, is turned out to be upper Miocene granitoids (7.5 Ma). The granodiorite contains magnetite and is depleted in lithophile components. This is characteristics of magnetite-series granitoids in the Green Tuff terrains. All the Miocene granitoids in Koshiki Islands are relatively mafic consisting of hornblende-bearing facies'such as quartz diorite, tonalite and granodiorite; thus belonging to I-type magnetite series. These rocks are considered to have generated at depth and formed along a rift zone during Miocene time (13-7 Ma). Thus, Koshiki Islands may represent an aborted rift at margin of the Danjo basin.
Miocene granitoids of Koshiki Islands are small stocks but magmatic-hydrothermal ore deposits are only seen in Futagojima. This localization of mineralization is explained by a high degree of magmatic fractionation, which is only observed in Futagojima and by a low rate of erosion to preserve the mineralized horizons. Mineralization here is unique having brannerite-magnetite and chalcopyrite-molybdenite-quartz assemblages. No gold and silver were detected from the vein-type deposit.

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Digital processing for partitioning a composite population into constituent single populations of known distribution type was attempted with a microcomputer on the basis of nonlinear least squares method.
The technique of partitioning was applied to two examples of actual geochemical exploration data, each of which was inferred to be composed of two single and roughly log-normal populations.
The results show that the method was quite satisfactory for providing basic and sound information for the interpretation of composite geochemical data, when applied together with the determination of statistical frequency distribution described in the previous report (OTSU et al., 1983).

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