In order to verify the presence of residual organic matter in some S-type granites, a method used conventionally in petroleum geochemistry for isolation of kerogen was employed to separate carbonaceous material (CM) from the Xihuashan granite, Jiangxi Prov., China. Optical, XRD and SEM/EDAX analyses identified the acid-insoluble residue as mainly composed of various mineral debris, with a minor carbonaceous fraction found in the residue. LMR and micro-FTIR studies showed that the residue contained a small amount of CM, which is heterogeneous in composition and structural state. The occurrence of CM in the granite implies that this granitic magma originated from sediments and crystallized at relatively lower temperatures and high pressures. This deduction is consistent with geological and geochemical studies of the Xihuashan granite. A tentative model was suggested which connects CM in S-type granite with organic matter in sedimentary rocks. The conditions under which CM can be preserved in S-type granite are discussed. The occurrence of some heavy hydrocarbons is expected in the Xihuashan granite.

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Solid bitumens found in carbonate rocks of the Shiwan Dashan basin, south China, are suggested to have been matured under high pressure and moderate temperature conditions. These bitumens have different geochemical characteristics from thermally matured bitumen: very high bitumen reflectance (R_OB) values and compact molecular structures (bigger size of crystal nucleus, more layer number of aromatic cycle, lower lamellar distance and so on) in spite of the chemical components reflecting lower thermal maturity. Therefore these are named as compressively matured bitumen. The geochemical characteristics of the compressively matured bitumens result from increase in its crystalline degree (grain size) under high pressures, not at high temperatures. The compressively matured bitumens retain chemical composition, molecular evolution parameters (associated with their chemical components) and hydrocarbon-producing potential similar to those of thermally less mature bitumens. High temperature and high pressure experiments proved that pressure and temperature have similar effect on the maturation indices, such as R_OB values and molecular structures. The above contrasting geochemical characteristics can be used to distinguish the compressively matured bitumens from thermally matured bitumens.

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Re-Os dating method was applied to the Kuroko ores from of the Wanibuchi Mine, southwestern Japan. Two whole-rock Kuroko ores and two yellow color fragments separated from one Kuroko ore sample were analyzed. Their Re and Os concentrations range from 3.52 to 50.6 ppb and from 20.1 to 92.9 ppt, respectively, and their ¹⁸⁷OS/¹⁸⁸Os ratios vary from 0.911 to 1.609. These data yield an isochron age of 18.44 ± 0.60 Ma with initial ¹⁸⁷Os/¹⁸⁸Os of 0.621 ± 0.013. The age is older than the inferred Kuroko formation age of northeastern Kuroko deposits, and also about three Ma older than the time of the clockwise rotation of southwestern Japan (ca. 15 Ma). The Wanibuchi Kuroko deposits are considered to have formed at the waning stage of the first phase (28–18 Ma) of the rifting and seafloor spreading in the Japan Sea area. The initial ¹⁸⁷Os/¹⁸⁸Os ratio might reflect the contemporaneous local seawater ratio that was more affected by mantle-derived Os resulted from the volcanic activities of Japan Sea formation than the typical oceanic Os ratio.

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The Precambrian basement of the Korean Peninsula, located at the east margin of Asian continent, consists of the Nangrim Massif, the Gyeonggi Massif and the Sobaegsan (Yeongnam) Massif. Two kinds of orthogneisses (biotite gneiss and granitic gneiss) from the central part of the Sobaegsan Massif show the particular difference in geochemical features suggesting the discrimination in formation history. The biotite gneisses give an Sm-Nd whole rock isochron age of 819 ± 114 Ma (2σ) with ε_Nd (0.82 Ga) = −15, and the granitic gneisses give an age of 1484 ± 810 Ma (2σ) with ε_Nd (1.48 Ga) = +7. The ε_Nd and ε_Ce, values for the granitic gneisses show characteristics of highly depleted mantle material and those of the biotite gneisses show their sources having light-REE enriched continental-like feature. Chondrite-normalized REE patterns are also different. Biotite gneisses have less fractionated patterns with (La/Yb)_N ratio of 10∼16 and negative Eu anomalies, while granitic gneisses have fractionated patterns with (La/Yb)_N ratio of 30∼180 with no/or positive Eu anomalies. The Ce-Nd isotopic results obtained here indicate that the Sobaegsan biotite gneisses were derived from continental-like sources having light-REE enriched feature, while the Sobaegsan granitic gneisses were derived from MORB-like sources having light-REE-depleted feature. These isotopic and REE data are interpreted as recording LREE fractionation events associated with major episodes of crust formation in East Asia. And the comparison of the initial ε_Nd value of the Sobaegsan biotite gneiss at 0.82 Ga with those of the Chinese and Japanese Precambrian rocks implies that the sources for the Sobaegsan biotite gneisses and these Chinese and Japanese rocks had common light-REE enriched pattern, e.g., ¹⁴⁷Sm/¹⁴⁴Nd ratio ranging from 0.09–0.13. Furthermore, it suggests that these sources having light-REE enriched patterns were derived from depleted mantle at the late Archean.

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The weight ratio of total organic carbon to total nitrogen (C/N ratio) in 20 meters of sediment core from Nakaumi Lagoon (coastal brackish lake), Japan is examined for its suitability as an organic source indicator. The C/N ratio depth profile is compared to the depth profiles of other proxies, i.e., weight ratio of total organic carbon to total organic nitrogen (C/N_org. ratio), stanol compositions, n-alkane compositions and the hydrogen-index by Rock-Eval pyrolysis. The C/N ratios of the lagoonal sediments, which have been deposited over the last ca. 8, 000 years, have a different profile from that of the C/N_org. ratio and other proxies due to the effects of a constant level of inorganic nitrogen (N_inorg.: ca. 0.04%) in the sediments. When C_org. content is less than 1 wt%, the presence of N_inorg. lowers the C/N ratio considerably, giving an inaccurate indication of organic source. C-N and C/N ratio–C_org. plots are useful for evaluating the effect of N_inorg.; if the depth profiles of the C/N ratio and C_org. content exhibit similar trends, this is taken as a warning that the apparent variation in the C/N ratio should be carefully examined in conjunction with the other plots and proxies. It is also found that the C/N_org. ratio itself also tends to increase due to the preferential decomposition of nitrogen compounds, and that in sediments containing high proportions of planktonic organic matter (OM), the sensitivity of the C/N ratio to changes in the proportions of planktonic-terrestrial OM is relatively low.

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Osmium and Reabundance and ¹⁸⁷Os/¹⁸⁸Os ratios of reference rocks, JB-1a, JA-2 and JP-1, were determined through isotope dilution—negative thermal ionization mass spectrometry (ID-NTI-MS). Duplicate analyses of each sample show heterogeneous distribution of Re and Os in the reference rocks. The ranges of Re and Os concentrations are 150–200 and 9–12 ppt for JB-1a, 59–67 and 10–12 ppt for JA-2 and 28–32 and 2400–2700 ppt for JP-1, respectively. Extremely high ¹⁸⁷Os/¹⁸⁸Os ratios of 0.20–0.28, much higher than that of the chondritic mantle (0.12–0.13), of JB-1a and JA-2 indicates involvement of components with highly radiogenic ¹⁸⁷Os/¹⁸⁸Os ratios such as the subducting slab-derived materials. The reference rocks JP-1, Horoman peridotite, yields sub-chondritic Os isotopic composition of 0.12.

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