HEAT REFRACTION AND LOW-PRESSURE METAMORPHISM IN THE NORTHERN FLINDERS RANGES, SOUTH AUSTRALIA

Unusually high lateral temperature gradients associated with metamorph ism of the lower sedimentary sequences of the Adelaide Fold Belt near the basal unconformity with Proterozoic gneisses of the Mt Painter Inl ier in the northern Flinders Ranges raise the possibility that heat re fraction can give rise to a unique type of regionally extensive, uncon formity-related, contact metamorphism. Numerical models are used to ex plore the possibility that the metamorphism may reflect lateral variat ions in thermal conductivity and heat production using simple geometri es appropriate to the deformed basement-cover interface at Mt Painter. The thermal models provided here show that with typical values of the rmal conductivity and heat production, heat refraction can account, at most, for about 1/3 to 1/2 of the observed metamorphic signature, Add itional advective heat transfer such as high-temperature fluid flow fo cused by the heat-refraction mechanism may have contributed to the lat eral temperature gradients surrounding the basement-cover contact.