SiO₂-アルカリ図では,本地域の前期中新世の玄武岩質岩は高アルカリソレアイト質,中期中新世のドレライトは過アルカリ岩質である。FeO^*/MgO-TiO₂図では,玄武岩はMORB, 玄武岩質安山岩は島弧ソレアイトの領域にプロットされる。MORBで規格化した玄武岩のスパイダーグラムは島弧玄武岩的で,アルカリドレライトは, within-plateの玄武岩とされる隠岐島前のNbに富むアルカリ玄武岩のそれに近い。コンドライトで規格化したREEパターンでは,玄武岩は高アルカリソレアイト (JB-3) に近く,アルカリドレライトはアルカリ玄武岩 (JB-1) より高い。
一方,ソレアイト質玄武岩 (No.2) とアルカリドレライト (No. 3) はε_Nd-⁸⁷Sr/⁸⁶Sr図上で,マントルアレイにのり,北九州,中国地方南部の中新世～第四紀の玄武岩とほぼ同じ領域にプロットされ,それらの玄武岩と同じ起源物質から供給されたものと考えられる。

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ラテライト中に金の微粉,砂粒あるいはナゲットが産出する例が最近各地で報告され,その成因論の構築が注目を浴びつつある。南インド,ニランブール鉱床では,金の特徴的な産状と組織が観察され,それらは浅部風化環境下での低温溶液による化学的な溶解-移動-再沈澱を示している。ラテライト断面の上部に産出する金粒は亜球形で,無数のエッチピットがみられる。下部に産する金は不定形であり,融蝕はほとんどみられない。二次沈澱金生成の初期段階は,フィラメソト状や樹脂状の集合体,あるいは花弁状や薄膜の形成である。これらは初生金粒の一部に付着し,あるいはそれを部分的に覆って成長している。産状と金粒の形態の特徴に基づいて,本地域における金の風化濃集モデルは以下のように考えられた。「黄鉄鉱の風化による酸性溶液の生成-その中への初生含金脈からの金の溶出およびこの溶液の上方への移動(塩化錨体)-上部風化帯の高Ehおよび中性～アルカリ性環境下に於けるFe²⁺による錯体の還元と金の沈澱」。化学的再沈澱は浅部風化環境下で生成される金の純度を高める効果をもたらすと考えられる。

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Talc-amphibole rocks and mafic conglomerates conformably occur in slaty rocks of the Kobotoke Group in the Katsunuma area, Yamanashi Prefecture. Their occurrence is almost same to that of previously reported serpentinite and picrite basalt bodies. The talc-amphibole rocks, now mainly composed of talc and actinolite, were derived from clastic serpentinite. Detrital chromian spinels have wide range of Cr/(Cr + Al) from 0.4 to 0.8, even in one thin section. The chemistry of spinels are almost equivalent to spinels in the Circum-Izu Massif (CIM) serpentinites. The mafic conglomerates were derived from olivine-rich basalts.
Chemical characteristics of bulk rock and relic chromian spinel indicate that they are equivalent to picrite to olivine basalts from the CIM serpentine belt. Geological and petrographical data of the talc-amphibole rocks and associated conglomerates indicate that a protrusion of a mafic-ultramafic complex had occurred at the Katsunuma area of the Kobotoke sedimentary basin in the Oligo-Miocene time.
The Katsunuma mafic-ultramafic complex composed of serpentinite and olivine-rich basalts are similar in petrological characteristics to other CIM equivalents.

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Nepheline was found in contaminated rocks accompanied with the gehlenite-spurrite skarns at Kushiro, Hiroshima Prefecture. The mineral occurs as a main rock forming mineral up to 2mm wide, associated with clinopyroxene, potash feldspar, titanite and apatite. It is hexagonal with the unit cell dimensions: a=9.986 (3), c=8.372 (3) A. Optically, it is uniaxial negative with refractive indices ω=1.534 and ε=1.528. Vickers microhardness is 634-762 kg/mm² (100g load) and observed density is 2.63g/cm³. The average chemical composition of the mineral is FeNe_1.3 Ne_70.5Ks_21.3An_2.0Q_4.9. Chemical composition is not variable.
The nepheline-bearing contaminated rocks are thought to have been derived by local desilication of quartz monzonitic magma.

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The Kitakami Mountains are geologically divided into three main belts : the South Kitakami Belt, the North Kitakami belt and the Iwaizumi belt. The former is made up mainly of littoral sediments and the latter two are marine ones. Samples of sandstones and mudstones from the belts were chemically analysed by a wet chemical method, atomic absorption and ICP, for major elements and such minor elements as Zn, Pb, Cu, Ni, Co, Cr, V and Li.
SiO₂ and K₂O contens of sandstones increase and Fe₂O₃^* (total Fe₂O₃) content decreases from the South Kitakami Belt, through the North Kitakami belt to the Iwaizumi belt in accordance with the change of the sandstone composition; from wacke to arkose. Among above elements Zn and V correlate most strongly with Fe₂O₃^* in both sandstones and mudstones. These elements might be accompanied closely by mafic components in the formation of the sediments. Values of most minor elements in the South Kitakami Belt range more widely than those in other belts as a result that the South Kitakami Belt is made up of small basins and sediments of the belt are derived from various source rocks. It seems that Cr/V and Cr/Zn ratios of mudstones in the South Kitakami Belt are lower than those in other belts although the source rocks of the sediments in the belt are mainly mafic. It is inferred that Cr content decreases if pelitic sediments were formed in oxidizing conditions such as in the South Kitakami Belt.

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Many acidic dykes representing final activities of acidic magma intruded into the Upper Cretaceous Ryoke granites exposed widely in the Takanawa peninsula, northwest Shikoku. Whole rock Rb-Sr isochron age and K-Ar age of the Ryoke granite are 93 Ma and 87 Ma respectively. Present whole rock K-Ar ages of the three acidic dykes collected from the north of Matsuyama are from 81.2 to 82.9 Ma and 82.3 Ma on an average. Intrusion of acidic dykes retarded 5 to 11 Ma after essential magmatism of granitic intrusion.
Paleomagnetic investigation suggests that intrusion of acidic dykes at 82 Ma and successive upheaval and errosion of the Takanawa peninsula had followed by sedimentary basin of Izumi Group in the northwest Shikoku triggered by displacement of the Median Tectonic Line at 80-81 Ma.

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