Willingham T O, Nagy B, Nagy L A, Krinsley D H, Mossman D J
Department of Geosciences, The University of Arizona, Tucson 85721, USA.
Can J Earth Sci. 1985;22:1930-44. doi: 10.1139/e85-209.
The Elliot Lake-Blind River, Ontario, paleoplacer deposits in the basal Matineda Formation, lowermost member of the 2.25-2.45 Ga old Huronian Supergroup, contain organic matter chemically consistent with kerogen. This substance is also referred to as thucholite. Uranium ores and some gold occur here, and these minerals may be in close association with the kerogen. Two uraniferous and auriferous stratiform kerogens, obtained from the Denison Mines Limited's Denison mine and Rio Algom Limited's Stanleigh mine, have been analyzed by combined high-vacuum pyrolysis--gas chromatography--mass spectrometry and by neutron activation. The reflectances of these samples have also been determined. Related samples containing dispersed kerogen have been examined by backscattered scanning electron microscopy. The polymer-like matrix of the two stratiform kerogens consists of aromatic, alkyl aromatic hydrocarbon, and sulphur moieties and contains 20 and 32% uranium with gold abundances in the parts per billion range. The reflectances of the two kerogens are generally higher than those of the dispersed kerogens; the atomic H/C ratios of the former are approximately 0.6 and approximately 0.4. Backscattered scanning electron microscopy and petrographic observations reveal a complex diagenetic history. Stratigraphic position and supportive analytical data suggest that the stratiform kerogens were probably derived from ancient mats of cyanobacteria, subjected to various radiation-induced reactions, and, at least in part, were affected in a manner similar to the surrounding rocks. The latter experienced physical and chemical diagenetic reactions, which often caused repeated mineral fracturing and led to the local development of authigenic carbonates and feldspar. Some of the chemical nature and history of the stratiform kerogens resemble those of the Witwatersrand carbon seam kerogen.
安大略省埃利奥特湖 - 布莱因德里弗地区，休伦超群最下部成员马蒂内达组底部的古砂矿沉积物中含有化学性质与干酪根一致的有机物。这种物质也被称为钍沥青。这里有铀矿和一些金矿，这些矿物可能与干酪根密切相关。从丹尼森矿业有限公司的丹尼森矿和里奥阿尔戈姆有限公司的斯坦利矿获得的两种含铀和金的层状干酪根，已通过高真空热解 - 气相色谱 - 质谱联用和中子活化分析。还测定了这些样品的反射率。含有分散干酪根的相关样品已通过背散射扫描电子显微镜检查。两种层状干酪根的聚合物状基质由芳香族、烷基芳香烃和硫部分组成，含铀量分别为20%和32%，金含量在十亿分之几的范围内。这两种干酪根的反射率通常高于分散干酪根；前者的原子H/C比分别约为0.6和约为0.4。背散射扫描电子显微镜和岩相学观察揭示了复杂的成岩历史。地层位置和支持性分析数据表明，层状干酪根可能源自古代蓝细菌垫，经历了各种辐射诱导反应，并且至少部分地受到了与周围岩石类似的影响。后者经历了物理和化学成岩反应，这些反应常常导致矿物反复破裂，并导致自生碳酸盐和长石的局部发育。一些层状干酪根的化学性质和历史与维特沃特斯兰德煤层干酪根相似。
