|Budget Amount *help
¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1988: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1987: ¥5,500,000 (Direct Cost: ¥5,500,000)
n-alkane assemblage, vitrinite refrectance and mineral assemblage for 130 marine sediments of the Nishikurosawa, Onnagawa and Funakawa Formations of the Miocene age in the Yokote and Taihei-zan areas, Akita Prefecture, Japan, were studied diagenetically and sedimentologically, refering to other data, namely, contents of organic matter, contents of pigments in extractable organic matter, organic types and values of "Tmax" by means of Rock-Eval", alteration of minerals in thin section and field evidences. The results are summerized as follows:
1. Geological column in the Yokote area is divided into three alterationzone by mineral assemblage enalysis ;clinoptilorite, analcime and leumontite zones. Columun in the Taiheizan area is divieded into opal-CT - mordenite, opal-CT and mica-chrolite alteration zones.
2. Vitrinite refrectance of the Neogene mudrocks is related mutually with "Tmax" by means of Rock-Eval.
3. Paleo-geothermal gragient of column in the Taiheizan area is higher than that of column in the Yokote area.
4. Vitrinite refrectances attest to the immaturity of organic matter in the samples.
5. Content of organic carbon show that. the Neogene mudrocks belong to the category of "fair" and "good" source rock.
6. On the H.I.-O.I.diagram, the mudrocks in the Yokote area and taiheizan area plotted in the field showing kerogn type I,II,II-III type and II-III, iiitype, respectively.
7. Stratigraphical distribution of the content of metal porphyrins and polycyclicaromatis hydrocarbons shows no tedency in the Neogene Tertiary of the studied areas.
8. Stratigraphical distribution of CPI value show no tendency in the studied areas.
9. n-alkane in the most of samples show polymodal distribution pattern between C15-C35, with predominance odd carbon chain length C29 and C31. We suggest that n-alkanes may have a biogenic origin.