The mesozoic equatorial atlantic magmatic province (EQUAMP): A new large igneous province in South America
Mafic dike swarms and sills intruding, respectively, the Precambrian Borborema and Paleozoic Parnaíba provinces (NE Brazil) constituteÂ two major magmatic events related to the continental break-up that formed the Equatorial Atlantic. Available whole rock K–Ar determinations and a few plagioclase 40Ar/39Ar ages suggest that these eventsÂ occurred approximately between 135 and 120Â Ma. Airborne magnetic data indicates that the main dike swarm, the Rio Ceará-Mirim swarm, can be traced for about 1,000Â km along an arcuate trajectory between the Cretaceous Potiguar rift near the Atlantic coastline, and the northern margin of the São Francisco craton. The dikes of the suchÂ aÂ giant swarm form isolated (often en-echelon) segments that can reach up to 40Â km in length and have a mean width of about 70Â m. The sills, known as Sardinha magmatism, are intercalated between the Paleozoic sedimentary strata of the Parnaíba basin having major expression in subsurface rather than on surface.Â Geochemical data indicate that the parental tholeiitic magmas of dikes and sills would largely derive from melting of subcontinental lithospheric sources. However, a subordinate OIB-type component identified in some dikes would indicate contribution of a mantle plume as a melt source. In this paper we propose thatÂ the Sardinha and Rio Ceará-MirimÂ magmatic products, which are found over an area of about 700,000Â km2, all togetherÂ represent a newly recognized Cretaceous LIP in South America here named Equatorial Atlantic Magmatic Province (EQUAMP).
Hollanda, M.H.B.M. (M. H.B.M.), Archanjo, C.J. (C. J.), Macedo Filho, A.A. (A. A.), Fossen, H. (H.), Ernst, R.E, de Castro, D.L. (D. L.), … Oliveira, A.L. (A. L.). (2019). The mesozoic equatorial atlantic magmatic province (EQUAMP): A new large igneous province in South America. In Dyke Swarms of the World: A Modern Perspective. doi:10.1007/978-981-13-1666-1_3