Significance and role of chemosynthetic bacteria in the formation of Carboniferous, deep-water, laminated carbonates.

1.通过对1991年野外调查中采集的手标本进行薄片分析和仔细观察，发现1）以化学合成群落为特征的碳酸盐岩不仅分布在纽芬兰，而且也分布在新玩法; 2）石炭纪期间，在加拿大大西洋沿岸非常广泛的沉积盆地中普遍存在来自海底的甲烷渗漏。对管虫土丘中方解石的碳氧同位素组成进行了测定。苔藓虫和腕足动物的表层方解石具有1.1至-1.4 o/oo Δ ^<13>C（PDB）和-3.6至-6.6 o/oo Δ ^<18>O（PDB），而填充贝壳和洞穴间隙的亮晶方解石胶结物具有2.3至-1.9 o/oo Δ ^<13>C和-8.6至-10.7 o/oo Δ ^<18>O。亮晶方解石中的轻氧可能指示较高的沉淀温度.硫化物矿物以各种形式出现在管虫土丘中。浸染状黄铁矿的Δ <34>S为0.75 - 6.37 o/oo，而直径为几米的块状硫化物矿石的Δ <34>S为28.3 o/oo。这表明，与浸染状黄铁矿相比，块状硫化物矿石是在更高的温度下从更进化的“海水”中沉淀出来的。结合纹理分析，化学分析和同位素特征，我们得出结论，管虫土丘是在以下过程中形成的：1）微生物过程受冷、甲烷和硫化物溶液的渗透和排出的增强控制，2）由于温度升高和原生沃茨的混合，方解石胶结物的发展，深部高温卤水运移形成块状硫化物矿。

1. Thin section analyses and close inspection of hand specimens, which were collected during the field survey in 1991, have revealed that 1) carbonatemounds characterized by chemosynthetic communities distributed not only in New Foundland, but also in New Brunswick, and 2) methane-seepage from the sea floor prevailed in very wide sedimentary basin in the Atlantic Canada during Carboniferous age.2. Carbon and oxygen isotope compositions were determined on calcite from tube worm mounds. Skeletal calcite of bryozoa and brachiopod have 1.1 to -1.4 o/oo delta^<13>C (PDB) and -3.6 to -6.6 o/oo delta^<18>O (PDB), whereas sparry calcite cement filling interstices of shells and cavities have 2.3 to -1.9 o/oo delta^<13>C and -8.6 to -10.7 o/oo delta^<18>O. Light oxygen of sparry calcite may suggest higher temperature of precipitation.3. Sulfide minerals occur as various forms in tube worm mounds. Disseminated pyrite has delta^<34>S of 0.75 to 6.37 o/oo, whereas massive sulfide ore a few m in diameter has delta^<34>S of 28.3 o/oo. This suggests that massive sulfide ore was precipitated from the more evolved "sea-water" at higher temperatures compared with disseminated pyrite.4. Combined textural analyses, chemical analyses, and isotopic signatures lead us to conclude that tube worm mounds were formed in the following processes : 1) Microbial process controlled by enhanced seep and expulsion of cold, methane and sulfide containing solutions, 2) development of calcite cement due to increased temperatures and mixing of connate waters, and 3) formation of massive sulfide ores caused by migration of high-temperature brines derived from deeper levels.