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The equatorial Atlantic Magmatic Province (EQUAMP):a geochemical and geochronological approach

Grant number: 17/08423-9
Support type:Regular Research Grants
Duration: July 01, 2017 - June 30, 2019
Field of knowledge:Physical Sciences and Mathematics - Geosciences - Geology
Principal Investigator:Maria Helena Bezerra Maia de Hollanda
Grantee:Maria Helena Bezerra Maia de Hollanda
Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Assoc. researchers: Antonius Adrianus Koppers ; Carlos José Archanjo ; Daniel Paul Miggins ; Francisco de Assis Negri ; Richard John Walker ; Valdecir de Assis Janasi ; Victor Sacek

Abstract

This proposal intends to study magmatic events exposed in the northeastern Brazil that were related to the evolution of the Atlantic continental margin during the Cretaceous and therefore to the break-up of the West Gondwana. These events are represented by: (1) a continental-scale arcuate mafic (dolerites) dike swarm that crosscuts a major Precambrian basement block named the Borborema Province, and (2) a sill province intruding the Paleozoic sedimentary succession of the Parnaíba basin. The mafic dikes were until recently restrict to be a 350 km-long E-trending swarm consisting mainly of high-Ti tholeiitic dolerites closely related to the Atlantic Ocean opening. It has been known as Rio Ceará-Mirim Dike Swarm. Recent high-resolution airborne magnetic surveys carried out on the Borborema Province have shown its continuation to SW extending about 1,000 km in length across the province, thus representing a giant dike swarm as defined in the classical work of Ernst and Buchan (1997) [AGU Geophysical Monograph, 100: 297-333]. The sill province is, in turn, located immediately west of the exposure area of the swarm, and is mostly represented by high-Ti coarse-grained basalts to basaltic andesites. They have been named as Sardinha sills. The very close spatial relationship between the dike swarm and the sills, together with existence of Early Cretaceous K-Ar ages in the literature allow us to test the hypothesis that they are part of a major continental magmatic province. In this proposal, we collectively refer them as the Equatorial Atlantic Magmatic Province (EQUAMP), and intend to formally characterize it as a new Gondwanan Large Igneous Province (LIP) in South America. In order to have success in our initiative we will follow some of the recommendations of the LIP Commission and firstly examine the CMDS and Sardinha sills based on geochemistry and geochronology. We will focus on gathering (1) textural, geochemical and Sr-Nd-Pb isotope data and (2) 40Ar/39Ar ages to understand the geochemical evolution of the EQUAMP magmas and establish timing and duration of their emplacement. With these results we will examine the dynamics of the lithospheric mantle and asthenosphere, as well as crust, during the evolution of the Equatorial Atlantic margin in the Cretaceous, as result of the Gondwana disruption. In order to have success in our initiative we will follow some of the recommendations of the LIP Commission and examine the CMDS and Sardinha sills based on geochemistry and geochronology. We will focus on gathering (1) elemental and Sr-Nd-Pb isotope data and (2) 40Ar/39Ar ages to understand the geochemical evolution of the EQUAMP magmas and establish timing and duration of their emplacement. With these results we will examine the dynamics of the lithospheric mantle and asthenosphere, as well as crust, during the evolution of the Equatorial Atlantic margin in the Cretaceous as result of the Gondwana disruption. In a wider perspective, our data will be added to the data pool of international bibliography in order to extend the existing knowledge on modern plate tectonics and, consequently, how supercontinents have broken up. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
NGONGE, EMMANUEL DONALD; BEZERRA MAIA DE HOLLANDA, MARIA HELENA; PUCHTEL, IGOR S.; WALKER, RICHARD J.; ARCHANJO, CARLOS JOSE. Characteristics of the lithospheric mantle beneath northeastern Borborema Province, Brazil: Re-Os and HSE constraints on peridotite xenoliths. Journal of South American Earth Sciences, v. 96, DEC 2019. Web of Science Citations: 0.
MACEDO FILHO, A. A.; ARCHANJO, C. J.; HOLLANDA, M. H. B. M.; NEGRI, F. A. Mineral chemistry and crystal size distributions of mafic dikes and sills on the eastern border of the Parnaiba Basin, NE Brazil. JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, v. 377, p. 69-80, JUN 1 2019. Web of Science Citations: 0.

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