Francisco Valdir Silveira

Dr. Francisco Valdir Silveira

orcid

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 April 2026 in Gondwana Research
Verified
Journal Article
Open access
ADA. Demény
A. Demény
PNP. Németh
P. Németh
SMS.J. Mojzsis
S.J. Mojzsis
BPB. Pécz
B. Pécz
NZN. Zajzon
N. Zajzon
FSFrancisco Valdir Silveira
Francisco Valdir Silveira


24 December 2025 in Minerals
Verified
Journal Article
Open access
PDF file
MNMatheus Andrade Nascimento
Matheus Andrade Nascimento
DRDébora Correia Rios
Débora Correia Rios
NMNivea Magalhães
Nivea Magalhães
FSFrancisco Valdir Silveira
Francisco Valdir Silveira
This study redefines the Nordestina Kimberlite Province (PKN), in the northeastern sector of the São Francisco Craton (SFC), as a composite kimberlitic–lamproitic system that hosts two genetically distinct magma types: (1) the primitive Braúna kimberlite and (2) hybridized phlogopite-rich lamproites belonging to the SFC lamproite variety. Braúna kimberlites represent an olivine-rich kimberlite sourced from a metasomatized lithospheric mantle, as reflected by its high MgO (15%–30.6%), Ni (up to 1172 ppm), and Cr (up to 2500 ppm). These geochemical signatures are consistent with a primitive melt capable of preserving diamond stability conditions. In contrast, the SFC lamproite variety exhibits strong crustal overprinting, marked by hydrothermal barite–carbonate–silica veining, cristobalite, elevated SiO2 (up to 80 wt.%), and high LOI (up to 27.5%). These features indicate significant post-magmatic alteration, felsic crust assimilation, and melt hybridization. Textural and mineralogical features found in both magma types, including olivine-phlogopite aggregates, irregular zoning, and disequilibrium assemblages, suggest magma mingling between compositionally distinct melts and/or crystallization under polybaric conditions. These findings clarify long-standing classification controversies by demonstrating that PKN magmatism is not represented by a single rock type but instead spans a continuum spectrum from primitive kimberlite to strongly hybridized lamproite. Regionally, the data reveal that PKN magmatism reflects Paleoproterozoic mantle metasomatism reactivated during Neoproterozoic tectonism. This dual-stage evolution explains the contrasting degrees of primitiveness and hybridization melt signatures observed across the province.

1 December 2022 in Journal of the Geological Survey of Brazil
Verified
Journal Article
Closed access
GBGeological Survey Of Brazil
Geological Survey Of Brazil
VAVidyã Almeida
Vidyã Almeida
JRJoseneusa Rodrigues
Joseneusa Rodrigues
INIzaac Cabral Neto
Izaac Cabral Neto
FSFrancisco Valdir Silveira
Francisco Valdir Silveira
BEBrazil Explore
Brazil Explore