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Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321 Creataceous and Paleogene of the Russian Platform) is documented (Muravyov, 1983). The presence of biogenic siliceous remnants (radiolarian shells and silicon sponge spiculas) in Pan- deri Zone deposits was reported in (Vishnevskaya and Baraboshkin, 2001). According to our data radiolarian shells are presented mainly in the upper part of OM-rich shale unit. Both in diffuse condition and in the form of mass accumulations on individual narrow interval. They are present in much more appreciable quantities in the overlying silty deposits of the Virgatus Zone. The initial siliceous substance typically does not remain in shells, and they usually are filled by autigenic phos- phates or glauconite-like fine clay aggregates, however lighter ones – greenish, grayish and yellowish shades of color. These formations are closer to smectites than micas (actually glauconites) in their optical properties. As well as the previous researchers (Riboulleau et al., 2003; Ruffell et al., 2002), we consider that clay mineral association I (with low smectite content) has terrigenuos detrital origin in Upper Jurassic sediments under the study. However, clay mineral associations II, III and IV (with high smectite content) occurred at the Panderi Zone time interval should be connected, in the first place, with more or less intensive processes clay mineral neoformation (i.e. specific smectite-clinop- tilolite mineral association, apparently with a tributary quantity of silica minerals) during early diagenesis stage, not with paleoclimatic changes. Generally similar relationship between decreasing of kaolinite-smectite ratio, on one hand, and enrichment in siliceous fauna remnants, on the other hand, was observed in other Upper Jurassic sections, particularly in the Northern part of the Russian Platform (in Syssola River region) and evidently displays the common regularity. At the same time, constancy of the ratio kaolinite, illite and smectite is a characteristic feature of Upper Jurassic sediments from Kostroma Region, i.e. Lower Kimmeridgian and Middle Volgian (Panderi Zone) deposits containing no biogenic silica remnants (and authigenic minerals developed on them) (Gavri- lov et al., 2008). Also it should note that clay mineral palygorskite is common in Upper and Middle Carbon sediments in the central part of the Russian Platform ( Rateev, 1985) as well as in Famennian deposits of the Upper Devo- nian of Voronezh syneclise where it is one of the main minerals ( Karpova, 2004). Since Devonian and Car- bon deposits closely contact Upper Jurassic deposits (sometimes Middle Volgian deposits) in many places of the central part of the Russian Platform, there exist all grounds to connect the presence palygorskite, which is sporadically found in the form of traces on different stratigraphic levels of Upper Jurassic, with its redeposition (recycling) from more ancient sedimentary units. In particular, Panderi Zone episodes were apparently connected with the lowering of the erosion basis in the course of general Late Jurassic marine regression, 328 which affected the relatively raised central part of the Russian Platform, in the first place. Thus, the paleogeographic reconstructions based on clay mineral distribution in Upper Jurassic deposits of the Russian Platform should be careful. Factors distorting the initial “climatic memory” of clay minerals, such as: a) early diagenetic neoformation of clay minerals; b) redeposition (recycling) of clay minerals from more ancient sediments should be taken into consideration. Acknowledgements: RFBR Project No. 09-05- 00872. Key words: Upper Jurassic; Clay minerals; Рaleo- climatic reconstructions; Russian Platform References: Gavrilov Y.O., Shchepetova E.V., Rogov M.A., et al. Sedimentology, geochemistry, and biota of Volgian carbonaceous sequences in the northern part of the central Russian Sea (Kostroma region). Lithology and Mineral Resources, 2008, 43: 354- 379. Karpova E.V. Sedimento- and litogenesis of the Devo- nian deposits (Voronezh syneclisa). Un- published Ph.D. thesis, 2004 (in Russian). Muravyov V.I. Mineral Paragenesises of Glauconite- siliceous Formations. M: Nauka, 1983: 208 (in Russian). Price G.D., Rogov M.A. An isotopic appraisal of the Late Jurassic greenhouse phase in the Russian Platform. Palaeogeography, Palaeoclimatology, Palaeoecology, 2009, 273: 41-49. Rateev М.А. Regularities in the Distribution and genesis of Clay Minerals in Recent and Old Marine Basins. M: Nauka, 1985: 251 (in Russian). Rengarten N.V. Kuznetsova K.I. Pyroclastic material in the Upper Jurassic sediments of the Russian Plat- form. Doklady Akademii Nauk of USSA. 1967, 173(1). Riboulleau A., Baudin F., Deconink J.F., et al. Deposi- tional conditions and organic matter pre- servation pathways in an epicontinental environ- ment: The Upper Jurassic Kashpir oil shales (Volga Basin, Russia). Palaeogeography, Palaeoclimatology, Palaeoecology, 2003, 197: 171-197. Ruffell A.H., Price G.D., Mutterlose J., еt al. Palaeo- climate indicators (clay minerals, calcareous nannofossils, stable isotopes) compared from two successions in the Late Jurassic of the Volga Basin (SE Russia). Geological Journal, 2002, 37: 17-33. Vishnevskaya V.S., Baraboshkin E.Y. New data on biostratigraphy of the lectostratotype of Volgian Stage near d. Gorodishche (Middle Volga River region) Stratigraphy and Geological Correlation, 2001, 9(5): 77-86.
Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321 Toward the Stratigraphic Correlation and Reconstruction of Atmospheric pCO2 in Terms of Stable Carbon Isotope in the Terrestrial Jurassic Carbonates, China H. Hirano 1* , G. Li 2 , T. Sakai 3 , T. Kozai 4 , H. Ishiguro 5 1. Waseda University Tokyo, Japan (E-mail: hhirano@waseda.jp) 2. Nanjing Institute of Geology and Palaeontology, CAS, Nanjing, China 3. Kyushu University, Fukuoka, Japan 4. Naruto University of Education, Naruto, Japan 5. Waseda University, Tokyo, Japan We have been studying the non-marine middle and late Mesozoic in China from the bio-, stable carbon isotope-, and sequence stratigraphic points of view. In 2009, we collected samples from the lower to upper Jurassic in and around Heibei, Chongqing, Sichuan Provinces for the international correlation by using the fluctuation curve of the stable carbon isotope as well as for the reconstruction of atmospheric pCO2 by calcareous concretions in paleosols. The non-marine lower Jurassic Ziliujing, Middle Jurassic Xintiangou, Lower Shaximao, and upper Jurassic Upper Shanximao Formations (Liet al., 1997) distributed in the studying area. This age correlation is based on dinosaurs (ditto). For the stable carbon isotope stratigraphy, we collected samples from the Daanzhai Member of the Ziliujing Formation. The member is lacustrine beds composed of quarts grains with carbonate matrix. We have tried high resolution correlation by using stable carbon isotope curves for the non-marine lower Cretaceous which is correlated with the Jehol Group in Heilongjiang, Jilin, Liaoning, and Hebei Provinces. We obtained δ 13 C from the terrestrial organic matter in visual kerogen contained in mud stones of those beds. This method is based on the successful results which we conducted for the marine Cretaceous Yezo Group distributed in Hokkaido, Japan. Ninety-nine percent of visual kerogen is composed of terrestrial organic matter in the marine Cretaceous Yezo Group (e.g. Uramoto et al., 2007, 2009). There- fore, it is not always difficult to obtain the d13C of terrestrial organic matter in the Group for the stratigraphic correlation. However, in the non-marine lower Cretaceous of northern China often the ratio of terrestrial organic matter is low and there is much amount of algae (e.g. the Jiufotang Formation, δ 13 C values range from -29 per mil to -23 per mil; in some levels the amorphous organic matter occupies 98% of TOC).Algae show different δ 13 C values from terrestrial organic matter. Therefore, it is often impossible to make stratigraphic correlation by using the stable carbon isotope fluctuation. It is necessary to develop the method to remove algae from the visual kerogen by using specific gravity separation, which we are trying. Additionally, the lower Cretaceous which is famous by well preserved fossils like feathered dinosaurs contains too much amount of tuff and the total organic carbon contents are relatively smaller amount. It is also difficult to obtain δ 13 C from such beds. It is desirable to make cross checks for the obtained correlation by stable carbon isotope from various aspects. In the case of the Yezo Group, ammonoids, inoceramid bivalves, planktic foraminifers, radiolarians, sporopollen, dinoflagellates and radio- metric method were used for the cross checks and the validity was confirmed (e.g. Uramoto et al., 2007, 2009).In the case of the Chinese non-marine beds, the validity of the obtained excursion curve of stable carbon isotope would be checked by some marine organisms which are sometimes found in the marine invasions. The analytical results of the terrestrial lower Jurassic Daanzhai Member (carbonate matrix) do not show the negative spike of the early Toarcian anoxic event (Jenkyns, 1988) which continued for 500,000 years. The analytical values are different from the expected values. We are now considering it. We also began to reconstruct the atmospheric pCO2 of Jurassic and Cretaceous by using calcareous concretions obtained from the paleosols. For Jurassic, we have studied the pCO2 by samples from the above mentioned Jurassic in and around Beibei district. The analytical results are fairly concordant from various data obtained in the world. At present, we are analyzing concretions and calculating the raw data. We would like to show you the results at the time of the symposium. Key words: Stable carbon isotope stratigraphy; International Correlation; Atmospheric pCO2; Ter- restrial Jurassic References: Hesselbo S.P., Grocke D.R., Jenkyns H.C., et al. Massive dissociation of gas hydrate during a Jurassic oceanic anoxic event. Nature, 2000, 406: 392-395. Jenkyns H.C. The early Toarcian (Jurassic) anoxic 329
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