Low-temperature zircon growth related to hydrothermal alteration of siderite concretions in Mississippian shales, Scotland

作者：Bojanowski Maciej J^*; Baginski Boguslaw; Clarkson Euan; Macdonald Ray; Marynowski Leszek

来源：Contributions to Mineralogy and Petrology, 2012, 164(2): 245-259.

DOI：10.1007/s00410-012-0736-6

• Zircon
• Concretions
• Diagenesis
• Hydrothermal alteration
• Vitrinite reflectance
• PAHs

Zircon occurs in voids and cracks in phosphatic coprolites enclosed in siderite concretions in Mississippian shales near Edinburgh, Scotland. The zircon formed during hydrothermal alteration of early-diagenetic concretions and occurs as spherical aggregates of prismatic crystals, sometimes radiating. Vitrinite reflectance measurements indicate temperatures of similar to 270A degrees C for the zircon-bearing concretions and the host shales. Molecular parameter values based on dibenzothiophene and phenanthrene distribution and occurrence of di- and tetra-hydro-products of polycyclic aromatic compounds suggest that the rocks experienced relatively high-temperature aqueous conditions related to hydrothermal fluids, perhaps associated with neighboring mafic intrusions. The zircon was dissolved from the concretions, transported in fluids, and reprecipitated in voids. This is the first record of the precipitation of authigenic zircon in sedimentary rock as a new phase, not as outgrowths.

• 出版日期2012-8