Thermal modeling of a metamorphic aureole around a paleogene hypabissal basic intrusion within the Potiguar Basin, Northeast of Brazil
DOI:
https://doi.org/10.11606/issn.2316-9095.v17-362Keywords:
Pyrometamorphism, Petrophysics, Potiguar Basin, NE Brazil.Abstract
The Potiguar Basin encompasses a considerable volume of alkaline basic rocks. The thermal effects associated with the emplacement of igneous rocks on sedimentary sequences can cause a peculiar type of contact metamorphism, the pyrometamorphism, which produces partial melting of host rocks and generate new rocks. This paper discusses the thermal effects caused by Cenozoic intrusions, known as Macau Magmatism, over Cretaceous rocks of the Potiguar Basin by means of field, petrographic and petrophysical data. Using mathematical models, the thermal cooling was simulated in the proximity of the São João plug, northeastern of Pedro Avelino village (state of Rio Grande do Norte, NE, Brazil). The results were correlated with mineralogical changes in the surrounding rocks. The most significant physical and textural changes from high to low temperatures are partial melting and recrystallization, compression and hydraulic fracturing. The thermal modeling indicates that the metamorphic aureole can reach up to 150 m from the contact. In addition, mineral assemblages related to contact metamorphism (cordierite, tridymite, spurrite, besides glass) allow to estimate minimum temperature conditions of the order of 1,000 °C and pressure of 0.5 kbar. Thermal modeling suggests that mineralogical and textural changes were effective for temperatures above 400 °C. The estimate for the São João plug cooling time is about 10,000 years. These data are relevant in order to understand the effect of magmatism on the remobilization of hydrocarbons and its influence on the Potiguar Basin petroliferous systems.
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