Introduction to geochemistry of metalliferous black shales
نویسندگان
چکیده
Metalliferous black shales exhibit a wide range of physical and chemical characteristics. They can be enriched in many different metals, and the metals can be in a variety of geochemical states. Depositional and geological histories of these shales are diverse. Some metalliferous black shales contain relatively high concentrations of organic matter whereas others do not. Because of elevated carbonate contents, some are calcareous shales or marlstones. Metal enrichments can result from redox reactions mediated by bacteria during early diagenesis and also from those associated with hydrothermal processes after deep burial. However, unifying characteristics of metalliferous black shales are sufficiently well established to justify combining a diverse number of fine-grained sedimentary rock types under a common term that reflects enhanced metal content, dark color and an inferred association with organic matter (e.g., Huyck, 1990). Moreover, the term "metalliferous black shales" is sufficiently accepted that Working Group 254 of the International Geological Correlation Program (IGCP) has that title and focus. This special issue of Chemical Geology brings together reports describing characteris-
منابع مشابه
Diagenetic Evolution of Mudstones: Black Shales to Laminated Limestones, an Example from the Lower Jurassic of SW Britain
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