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Title: Lithostratigraphy and geochemistry of the Paraná-Etendeka large igneous Province and constraints on the petrophysical properties of volcano-sedimentary sequences
Author: Rossetti, Lucas de Magalhães May
ISNI:       0000 0004 7658 9464
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2018
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The surface expression and geochemistry of the Paraná-Etendeka Province lavas reflect deep magmatic process prior to eruption. The onset of magmatism is composed of compound pahoehoe basalt and basaltic andesite lavas formed during low-volume eruptions and are grouped in the Torres Formation. These magmas were formed by melting of the asthenospheric mantle (30 - 40 kbar) with minor contributions of SCLM and have fractionated polybarically, from picritic melts, assimilating crust prior to eruption. During the peak of magmatism, these parental melts evolved to basaltic andesite compositions that have formed high volumes of thick and widespread lavas (Vale do Sol Formation). Magma evolution is marked by a progressive shallowing of magma chambers and fractionation (+assimilation) at middle to upper crustal levels. Palmas Formation overlay the Vale do Sol Formation in the central and eastern outcrop area and Torres Formation lavas in the west. The unit is characterized by dacites and rhyolite lava domes and tabular flow units. The acidic magmas represent melts formed by extensive AFC of the parental basaltic magmas. The upper stratigraphic unit is composed of basaltic pahoehoe flow fields emplaced during the waning phase of volcanism in the area (Esmeralda Formation). Significant lithospheric thinning occur during magmatism and the last lavas were formed by partial melting of asthenosphere at shallow depths in the spinel stability field of the upper mantle, with neglectable contribution from lithospheric melts. Sedimentary interbeds are preserved throughout the stratigraphy and represent key markers. The volcano-sedimentary rocks have heterogeneous rock properties. Sandstones preserve high-porosity (>15%) and permeability (avg. 450 mD) and have good reservoir properties. In the lavas, petrophysical properties vary cyclic and are controlled by flow structure and can be further modified by alteration processes. Locally, the lavas present good reservoir properties and might represent potential targets in prolific hydrocarbon provinces.
Supervisor: Hole, Malcolm J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Flood basalts ; Igneous rocks ; Geochemistry ; Lava ; Parana´-Etendeka traps