What question did this study set out to answer?

This research aims to explore the geochemical and geochronological characteristics of the Transminas and Pirenópolis dike swarms to better understand their role in the South Atlantic Magmatic Provinces.

March 26, 2026Open Access

The Transminas and Pirenópolis dike swarms: new evidence for the central and South Atlantic Magmatic Provinces in South America

Key Points

This research aims to explore the geochemical and geochronological characteristics of the Transminas and Pirenópolis dike swarms to better understand their role in the South Atlantic Magmatic Provinces.
Analyzed geochemical compositions of dikes, including TiO2 and MgO levels.
Conducted 40 Ar/39 Ar and K–Ar dating to determine ages of dike emplacement.
Examined isotopic data (Sr, Nd, Pb) to infer mantle source characteristics.
Transminas dikes show high-Ti compositions with well-defined trends and lengths exceeding 800 km.
Pirenópolis dikes exhibit a low-Ti composition with Triassic age correlations (∼210.7–205.5 Ma).
High-Ti dikes are dated to the Early Cretaceous (∼133–131.5 Ma), linked to the breakup of West Gondwana.

Abstract

• PEMP and EQUAMP compose a single Mesozoic LIP: the South American Magmatic Province (SAMP). • High-Ti tholeiitic magmatism in SAMP shows strong similarities, suggesting a common mantle source and magmatic processes in the whole LIP. • The Transbrasiliano Lineament is a major tectonic-structural boundary separating Mesozoic LIPs in West Gondwana. This study reports new geochemical and geochronological data for the Transminas and Pirenópolis dike swarms in Brazil. The Transminas dikes comprise two branches in southeastern Brazil: The Az-170 swarm, trending NNW–SSE and extending for over 800 km, and the Az-125 swarm, trending NW–SE with a total length of 1,100 km. The Pirenópolis dikes, in turn, encompass two NNW–SSE-oriented subswarms (∼50 km) in Central Brazil. The dikes are subalkaline/tholeiitic basalts and basaltic andesites with high-Ti (TiO 2 = 4.3–3.1 wt%) and low MgO (4.93–3.34 wt%) compositions, except a low-Ti subswarm (TiO 2 6.5 wt%). 40 Ar/ 39 Ar and K–Ar dating of the low-Ti Pirenópolis dikes yields Triassic dates (∼210.7–205.5 Ma), linking their emplacement to the. In contrast, the high-Ti dikes from both the Transminas and Pirenópolis swarms record Early Cretaceous dates (∼133–131.5 Ma), coeval with the initial breakup of West Gondwana, and are therefore associated with the Paraná–Etendeka Magmatic Province (PEMP). High-Ti dikes have 87 Sr/ 86 Sr = 0.71157–0.70549 and ε Nd = −0.9 to −16.2. Lead isotopes indicate a signature compatible with an enriched mantle source (EMI; 206 Pb/ 204 Pb = 18.40–18.12). The integrated datasets for the high-Ti tholeiites of the PEMP giant dike swarms and those of the Equatorial Atlantic Magmatic Province (EQUAMP) indicate derivation from compositionally similar or possibly shared mantle source reservoirs. Such a connection further supports the integration of these Early Cretaceous provinces into the South Atlantic Magmatic Province (SAMP). When assessing the spatial distribution of the magmatic remnants of the CAMP and SAMP, we conclude that the Transbrasiliano Lineament acted as a tectonic boundary, modulating the emplacement realm of the two LIPs during the Mesozoic.

Read Full Paperexternally

Bookmark

View Full Paper

Cite This Study

Filho et al. (Sun,) studied this question.

synapsesocial.com/papers/69c4cc69fdc3bde4489179bd https://doi.org/https://doi.org/10.1016/j.gsf.2026.102306

Bookmark

View Full Paper