Postmagmatic mineral parageneses of dikes may be used to estimate the PT data of their country rocks: An example from the Bayerischer Wald, Germany

Narrow magmatic dikes cool so fast that their cooling history is almost exclusively determined by that of the country rock. Postmagmatic hydrothermal minerals in dikes, if present, are therefore formed under the PT conditions of the country rock. This effect may be used to estimate the temperature and pressure of the country rock at the time of intrusion of such dikes. For the late Variscan dikes of the Bayerischer Wald a temperature of 200 ′ 50 °C and a pressure of 100 to 180MPa is estimated.