Geothermal palaeogradients and metamorphic zonation from the conodont colour alteration index (CAI) |
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| Authors: | Susana García-López Fernando Bastida Jesús Aller & Javier Sanz-López |
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| Institution: | Departamento de Geología, Universidad de Oviedo, 33005 Oviedo, Spain,;Facultad de Ciencias da Educación, Universidade da Coruña, 15011 A Coruña, Spain |
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| Abstract: | The conodont colour alteration index (CAI) is potentially valuable in thermal history investigations, but there are problems in its use. An approach is proposed herein to overcome the problem of establishing reliable geothermal palaeogradients in areas with burial metamorphism, based on knowledge of the stratigraphic succession thickness, the boundaries of chronostratigraphic units, and the age and duration of deformation episodes. Although also problematical that a correlation between CAI and Kübler index (KI) values does not exist, there are areas where CAI and KI values are notably consistent for the anchizone boundaries; however, anomalous correlations between CAI and KI values have also been found in some areas. A CAI anchizone (or ancaizone) is defined in order to enable CAI values to be used independently to establish a metamorphic zonation. |
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