Electron Microscoplc and mineralogical studies on biologically induced metal ores and minerals

研究生物诱导的金属矿石或金属外围相是很有意义的。这些过程对地球表面环境和地球历史都有很大的影响。本项目选取了三个主要的主题：(1)群马狮子矿等生物成因铁矿的形成过程；(2)古老的和现代的叠层石构造及其特征；(3)生物成因(磁铁-细菌)磁铁矿。这些研究的主要成果之一是关于(1)群马铁矿。以下是总结。对该铁矿沉积铁矿进行了矿物学描述，铁矿由纳米针铁矿、结晶度较好的黄钾铁矾矿和极少量的强度岩组成。特征矿石类型包括厚带铁矿石、薄带狮子矿和富含苔藓和/或叶子的化石集合体矿石。在厚带状矿石中，藻类化石清楚地保存在针铁矿带中。晶格成像显示了针铁矿纳米晶的特征结晶取向。细粒状狮子矿可能是细菌铁生物矿化作用形成的。这些条带可能是生物节律或季节节律造成的。生物矿化产物见于现今富pH 2~3、Fe~(2+)、SO_4~(2-)、富SO_4~(2-)、Fe-P-(S)至Fe-S-(P)沉淀中。苔藓和绿藻也在细胞内和细胞周围收集铁沉淀。这些矿石被认为是生物成因的铁矿。(2)在日本和澳大利亚的前寒武纪地层中均发现了含锰叠层石。(3)对磁铁矿进行了矿物学和结晶金相检验。

It is interesting to investigate biologically Induced metal ore or rnineral phases. The processes have much impact to Earth'ssurf ace environments and also on Earth History. In this project, three major sub-themas were selected : that is, (1) Formation processes of biolocgically induced iron ore, such as Gunma lion Mine, (2) Old and recent stromatoilte structures and their characteristics, and (3) biogenic (magne to tactic bacterial) magnetite. One of the major results of these studies is about (1) on Gunma Iron mine. The following is the summary. Sedimentary iron ores From the Iron Mine were mine ralogically described .The Iron ore is composed of nanocrystalline goethite, well crystallized jarosite and very small amounts of strengite. Characteristiciron-ore types include thick-banded iron, thin-banded lion ore and fossil-aggregate ore rich in moss and/or leaves. Algal fossils are clearly preserved in the goethite bands in the thick-banded ore. Lattice imaging howed characteristic crystallographic orientations of the goethite nanocrystals. The thin- banded lion ores may probably formed by bacterial iron biominera1ization. The bandings may be attributed to biological or seasonal rhythms. Various products of biomineraIization are found in the present pH 2-3, Fe2^<2+>-and SO_4^<2-> rich streams ; Fe-P-(S) to Fe-S-(P) precipitates. Mosses and green algae are also collecting Fe precipitates in and around the cells. These ores are regarded as Biologicaly Induced lron Ore. (2) Mn stromatolite were found both from Japan (as recent hot springsediments), and from Australia precambrian strata. (3) The magnetite was mine ralogically and cryst allographically examined.