Geochemistry, geochronology, and tectonic aspects of the Angicos plutonism: Insights into equigranular high-K calc-alkaline magmatism in the northern Borborema Province

Author(s)

de Macedo Filho, Antomat Avelino ; Oliveira, Alisson L. ; Mansur, Eduardo T. ; Janasi, Valdecir A. ; Melo, Alanny C. C. ; Lima, Francisco G. F. ; Avila, Carlos F. ; Tavazzani, Lorenzo ; Dantas, Alana R.

• Document type: Journal article
• Source: LITHOS; v. 502, p. 21-pg., 2025-03-01.

Abstract

The Borborema Province is renowned for its prominent Ediacaran to Cambrian plutonism, constituting more than 15 % of its total area. Within this context, the Angicos Batholith is a NNE-trending elongated pluton with ca. 250 km(2), representing one of the largest bodies with equigranular texture in the northern part of the province. On the northwestern margin of the batholith, the Poco da Oiticica Stock forms a N-S elongated intrusion, while the NWSE semicircular Flores Stock is situated on the northeastern side. Both exhibit compositions and textures like those of the batholith. Despite its volume, the understanding of the granitogenesis in this area remains limited due to a lack of comprehensive data concerning geochemistry, geochronology, and geological-geophysical mapping approaches. In this study, we present a new analytical dataset of Angicos Plutonism combined with remote sensing and aerogeophysical data to assist in geological-structural mapping. The equigranular granites are composed of orthoclase (Or(96-90)Ab(4-10)), oligoclase (An(21-17)Ab(77-81)Or(2-1)), and Fe-biotite with smaller amounts of magnetite, ilmenite, apatite, allanite, monazite, fluorite, and zircon. These rocks exhibit SiO2 contents ranging from 70 to 75 wt%, total alkalis from 8.8 to 9.0 wt%, and weakly peraluminous compositions. The batholith has enrichment in large ion lithophile elements and depletion in high-field strength elements. The light rare earth elements content is high [4 <= (La/Sm)(N) <= 11], combined with negative Eu anomalies (Eu/Eu* = 0.4-0.9) and a fractionated spectra of heavy rare earth elements [4.2 <= (Gd/Yb)(N) <= 7.7]. The newly obtained UPb age of 584.8 +/- 0.9 Ma on the southern side of the body is compatible with the peak of plutonic activity in the northern Borborema Province. The compositional and textural similarity between the Angicos granites and younger neighboring stocks (similar to 550-530 Ma) highlight a long-lived period of high-K calc-alkaline magmatism in the region, with the Angicos Batholith representing one of the oldest members of this suite. The geochemical signature combined with the presence of xenoliths of banded gneisses along with inherited zircons of the Rhyacian Period, suggests crustal recycling in the region, where metaplutonic rocks of the Caico<acute accent> Complex would be the main source of granites. The equigranular texture of such a large pluton would be justified by high undercooling rates. In this context, the extensional bridging accommodation mechanism in laterally alternating shear zones emerges as a plausible model for the emplacement of the Angicos Batholith. (AU)

• FAPESP's process: 24/14170-0 - High-Precision Geochronology of Cretaceous Magma Plumbing Systems on the South Atlantic Realm
• Grantee: Antomat Avelino de Macêdo Filho
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 23/02630-3 - "(U-Th)/He thermochronology applied to active orogenesis and landscape evolution in the Amazonian Andes
• Grantee: Alisson Lopes Oliveira
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/03365-9 - Geochemical and geochronological investigation of giant dike swarms associated with West Gondwana breakup: keys to geodynamical correlations between large igneous provinces in South America
• Grantee: Antomat Avelino de Macêdo Filho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral