Thermal Consequences of Deep Crustal Underplating in the Paraná Basin

Thermal effects of a magmatic underplate at the base of the crust beneath the Parana Basin have been examined using simple heat conduction models. The results obtained indicate that the peak of the 'thermal front' arrives at near surface layers within 5 to 10 million years after the onset of underplating but its decay may persist for several tens of millions of years. The magnitude of temperature perturbation is found to be in the range 10 to 40°C depending on the value of crustal thermal gradient. Thus underplating may have remarkable influence on the thermal maturities of deeper sedimentary layers. These results are not in agreement with the conclusions of a recent work by Hurter and Pollack (Basin Research, 6: 239- 244, 1994) who seem to have underestimated the magnitude of thermal effects in their model calculations.