Sanz-Montero,M.E. and Rodriguez（iの頭は´）-Aranda,J.P.(2009): Silicate bioweathering and biomineralization in lacustrine microbialites: ancient analogues from the Miocene Duero Basin, Spain. Geol. Mag., 146(4), 527-539.

『湖成微生物岩における珪酸塩生物風化および生物鉱化作用（バイオミネラリゼーション）：スペインの中新世デュエロ盆地からの古代の類似物（アナログ）』

『Abstract
　The Miocene dolomite-chert microbialites studied here offer a complete record of the geochemical cycles of silicate weathering and the subsequent formation of secondary products. The microbialites were formed in lacustrine systems during the Miocene of the Duero Basin, central Spain. Mineralogical, chemical and petrographic results provide evidence of the mediation of microbes in early weathering and by-product formation processes. Irrespective of the composition, the surfaces of the grains were subject to microbial attachment and concomitant weathering. Palaeo-weathering textures range from surface etching and pitting to extensive physical disaggregation of the minerals. Extreme silicate weathering led to the complete destruction of the silicate grains, whose prior existence is inferred from pseudomorphs exhibiting colonial textures like those recognized in the embedding matrix. Detailed petrographic and microanalytical examinations of the weathering effects in K-feldspars show that various secondary products with diverse crystalinity and chemical composition can coexist in the interior of a mineral. The coexistence of by-products is indicative of different microenvironmental conditions, likely created by microbial reactions. Thus, the presence of varied secondary products can be used as a criterion of biogenicity. Intensive alteration of P-bearing feldspars suggests that mineral weathering may have been driven by the nutrient requirements of the microbial consortium involved in the precipitation of dolomite. The rock record provides useful information on mineral weathering mediated by microbes.

Keywords: silicate dissolution; microbial weathering; biomineralization; lake; dolomite

1. Introduction
2. Geological and sedimentary setting
3. Material and methods
4. Results
　4.a. Dolostone: petrographic features and microbial origin
　4.b. Silicate occurrences and composition
　4.c. The silicate - matrix interface
　4.d. Weathering features on silicates
　　4.d.1. Quartz weathering
　　4.d.2. Phyllosilicate weathering
　　4.d.3. Plagioclase weathering
　　4.d.4. K-feldspars weathering
　4.e. Vanished silicates in dolostone and chert beds
5. Discussion
　5.a. Evidence for microbial involvement in the weathering processes
　5.b. Secondary products
　5.c. Silicate composition and weathering sequence
6. Conclusions
Acknowledgements
References

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