Restore the Archean oceanic hydrothemai cross section: Geologicai and geochemical approach for frnding of early biosphere

恢复太古宙海洋水热剖面：早期生物圈的地质和地球化学方法

基本信息

批准号：
14340153
负责人：
KIYOKAWA Shoichi
金额：
$ 9.41万
依托单位：
Kyishu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The 3.2-Ga. Dixon Island Formation in the Cleaverville Group of the coastal Pilbara terrane, Australia, is one of the best sequences that preserves an example of middle Archean oceanic stratigraphy and contains possible microbial material. Field observations and geochemical evidence suggest that the Dixon Island Formation contains low temperature hydrothermal vents system with a biogenic microbial colony in the Archean ocean. The Dixon Island Formation is approximately 350 m thick and consists of the Rhyolite Tuff, Black Chert and Varicolored Chert members. Many black-chert vein swarms in the Rhyolite Tuff Member imply intensive low-temperature hydrothermal activity during deposition of the Black Chert Member, which is 15〜20 m thick. Abundant pseudomorph of silica after aragonite, barite, and gypsum, and a distinctly continuous, stromatolite-like biomat layer (10〜20 cm in thick), are preserved within the laminated black-chert bed. The stromatolite-like biomat bed formed fine iron or ir … More on-coated quartz pisoids within fine-grained silica. The absence of detrital sediments of continental origin and many vein injection implies that this sedimentary facies represents a pelagic hydrothermal environment at about 500〜2000 m in paleodepth, which is not very deep oceanic plane, such as a slope of immature island arc setting.Microbial material has been preserved well in the Black Chert Member, which is composed of massive black chert, laminated black chert, dark greenish siliceous shale and tuffaceous laminated chert. These rocks are mainly composed very fine quartz. The massive black chert has carbonaceous peloids (0.3 mm〜2 mm in diameter) similar to those in the black chert veins. The massive black chert contains spiral-, rod- and dendrite-shaped bacterial material. Total organic carbon (TOC in the black chert and black chert veins varies within 0.05〜0.16% (average 0.1%) and the carbon isotope (delta 13C values of these rocks are -32〜-27 per mil (average 30 per mill). This evidence suggests that the carbonaceous grains and bacteria-shaped material in the black cherts are biogenic origin and formed close to a low temperature hydrothermal vent system. The microbial colony might have been quickly fossilized by silicification related to hydrothermal activity. Less

3.2-ga。澳大利亚沿海皮尔巴拉地座的克莱弗维尔小组的迪克森岛形成是保留中大帝海洋层学典型典范的最佳序列之一，并包含可能的微生物材料。现场观察和地球化学证据表明，迪克森岛的形成包含高温水热通风系统，在大帝海洋中具有生物生物微生物菌落。迪克森岛的地层约为350 m，由流纹岩凝灰岩，黑色cher和静脉曲张的chert成员组成。流纹岩凝灰岩成员中的许多黑切口静脉群暗示着在15-20 m厚的黑切尔特成员沉积过程中，强烈的低温水热活性。在层压的黑凝结床中保存了二氧化硅丰富的二氧化硅的大量二氧化硅，以及明显连续的类质子石状野生型生物层（厚10-20厘米）（厚10-20厘米）。基质岩状的野生床形成细铁或IR…在细粒二氧化硅中更多涂层的石英菌素。 The absence of detrital sediments of continuous origin and many vein injection implies that this sedimentary faces represent a pelagic hydrothermal environment at about 500-2000 m in paleodepth, which is not very deep oceanic plane, such as a slope of immature island arc setting.Microbial material has been preserved well in the Black Chert Member, which is composed of massive black chert, laminated black chert, dark greenish silicaous页岩和绷带层状的缝隙。这些岩石主要组成非常细的石英。巨大的黑色缝隙具有与黑裂静脉相似的碳质胶体（直径为0.3 mm至2 mm）。巨大的黑色裂缝包含螺旋，杆和树突形的细菌材料。总有机碳（在黑缝和黑色缝隙中的TOC在0.05-0.16％（平均0.1％）和碳同位素（这些岩石的Delta 13c值为-32---27磨米）内（平均每磨机30磨）（平均每磨30分）（平均30个）。此证据表明，该证据表明，碳质晶粒和细菌形状的液化系统是潮汐孔和形式的液体，是氢晶体的液态和形式的良好的含量。微生物菌落可能通过与热液活性相关的硅化迅速化