Magma recharge and hybridization in an alkaline magmatic system: Evidence from clinopyroxene and olivine from the Pariquera-Açu Suite, SE Brazil

Autor(es)

Cetina, Lina ; Azzone, Rogerio G. ; Ubide, Teresa ; Dias, Vinicius Gonsalves

• Tipo de documento: Artigo Científico
• Fonte: LITHOS; v. 518, p. 20-pg., 2025-11-04.

Resumo

Crystal populations in igneous rocks record complex open-system processes within magmatic plumbing systems. These processes remain poorly explored in alkaline plutonic environments. This study investigates zoned clinopyroxene and olivine from the Pariquera-A & ccedil;u Suite (SE Brazil) to characterize magma evolution in alkaline systems. This fossilized intrusion, with zoned facies from cumulate shonkinites at the margin to inequigranular malignites in the center, provides a natural laboratory for studying open-system processes. We analyzed textures and major and trace element compositions of clinopyroxene and olivine, including LA-ICP-MS trace element mapping, and applied a range of thermobarometric approaches. We identify four clinopyroxene and olivine populations that reflect four main stages in the system's evolution: (1) Crystallization of antecrystic Mg-rich beige clinopyroxene and primitive olivine cores in a deep reservoir (similar to 580 MPa, similar to 1132 degrees C), with compositional variations recording fractional crystallization. (2) Shallow reservoir (similar to 170 MPa, similar to 1110 degrees C) crystallization fed by an alkali mafic melt carrying antecrysts, forming Ti-Al-rich brown clinopyroxene mantles (overgrowing beige cores) and intermediate olivine cores or rims. (3) Mafic recharge events leading to reverse zoning in clinopyroxene (beige bands) and Ni-rich intermediate olivine cores. (4) Felsic melt input producing green-reddish reaction rims on clinopyroxene and evolved olivine rims. The evolution of this shallow magma chamber is controlled by fractional crystallization, coupled with recharge events that drive mixing and hybridization processes, and trigger a dynamic environment with compaction and mush disintegration and remobilization, imprinting textural features represented by cumulate and inequigranular facies. This study highlights the role of mineral-scale textures and compositions in revealing magmatic processes. (AU)

• Processo FAPESP: 20/15299-5 - Processos de mistura de magmas e assimilação crustal de magmas básicos alcalinos em ambiente de câmara magmática: o complexo alcalino Pariquera-Açu, Província Alcalina Arco de Ponta Grossa, SE Brasil
• Beneficiário: Lina Maria Cetina Tarazona
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 23/11826-9 - Mapeamento de elementos traço de clinopiroxênio e apatita e análise isotópica in situ 87Sr/86Sr em apatita do complexo alcalino Pariquera-Açu: Estudo dos processos de mistura de magma e assimilação crustal em uma câmara magmática rasa fossilizada
• Beneficiário: Lina Maria Cetina Tarazona
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 19/22084-8 - A Província Magmática Paraná: petrogênese, cronologia e impacto ambiental do magmatismo toleítico, alcalino e silícico Cretáceo na Plataforma Brasileira
• Beneficiário: Valdecir de Assis Janasi
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 23/11675-0 - Corpos magmáticos de afinidade básica-ultrabásica insaturados em SiO2 da plataforma brasileira: estudo de fontes e processos de evolução em sistema aberto em complex plumbing systems a partir de abordagem microanalítica
• Beneficiário: Rogério Guitarrari Azzone
• Modalidade de apoio: Auxílio à Pesquisa - Regular