TY - JOUR
T1 - Neoproterozoic magmatic arc volcanism in the Borborema Province, NE Brazil
T2 - possible flare-ups and lulls and implications for western Gondwana assembly
AU - Caxito, Fabrício Andrade
AU - Basto, Camila Franco
AU - Santos, Lauro Cézar Montefalco de Lira
AU - Dantas, Elton Luiz
AU - Medeiros, Vladimir Cruz de
AU - Dias, Tatiana Gonçalves
AU - Barrote, Vitor
AU - Hagemann, Steffen
AU - Alkmim, Ana Ramalho
AU - Lana, Cristiano
PY - 2021/4
Y1 - 2021/4
N2 - New zircon U-Pb (SHRIMP and LA-ICPMS), elemental and Nd-Sr geochemistry data on rhyolitic metavolcanic and metavolcaniclastic rocks of NE Brazil characterize widespread arc-related phenomena during the Neoproterozoic, related to the Conceição-type or Stage I plutonic rocks. U-Pb zircon dating pinpoint the main phase of magmatic activity at ca. 635-600 Ma in the 700-km long sigmoidal Piancó-Alto Brígida domain, but other important flare-ups might have taken place at ca. 670-690, 730-760, 810-820 and 860-880 Ma. A comprehensive compilation of detrital zircon data from metavolcanosedimentary successions of the entire Borborema Province (n=5532) confirms the occurrence of a quasi-continuum Neoproterozoic spectra punctuated by peaks at those same age intervals separated by minor lulls. Low Th/U rims of zircon crystals dated at ca. 577 Ma provide an estimate of the age of regional transpressional metamorphism. Samples of all age ranges are mostly calc-alkaline, magnesian and peraluminous, with moderately to highly fractionated LREE enrichment, negative Nb-Ta anomalies akin to convergent settings, and plot mainly within the volcanic arc field in tectonic discrimination diagrams. Nd-Sr isotope systematics indicate the involvement of juvenile Neoproterozoic melts from the mantle wedge, which upon mixing with Archean-Paleoproterozoic basement and contamination with the host metasedimentary rocks yield Mesoproterozoic TDM mainly at 1.14-1.44 Ga, near-chondritic εNd(t) and 87Sr/86Sri 0.703-0.710. We put forward a model involving a major continental back-arc zone related to the development of the Conceição magmatic arc, akin to the modern-day Taupo volcanic zone of New Zealand, crosscutting NE Brazil and presumably continuing through the schist belts of Nigeria and Cameroon. The main magmatic flare ups might have been induced by extra-arc phenomena, such as collision of the West African paleocontinent with the northwestern Borborema edge due to closure of the exterior Goiás-Pharusian Ocean, force-speeding subduction in the interior V-shaped oceanic basins that constituted the Transnordestino-Central African Ocean and generating clockwise windshield-wiper-like rotation of the blocks back towards the São Francisco-Congo paleocontinent in a complete Wilson Cycle.
AB - New zircon U-Pb (SHRIMP and LA-ICPMS), elemental and Nd-Sr geochemistry data on rhyolitic metavolcanic and metavolcaniclastic rocks of NE Brazil characterize widespread arc-related phenomena during the Neoproterozoic, related to the Conceição-type or Stage I plutonic rocks. U-Pb zircon dating pinpoint the main phase of magmatic activity at ca. 635-600 Ma in the 700-km long sigmoidal Piancó-Alto Brígida domain, but other important flare-ups might have taken place at ca. 670-690, 730-760, 810-820 and 860-880 Ma. A comprehensive compilation of detrital zircon data from metavolcanosedimentary successions of the entire Borborema Province (n=5532) confirms the occurrence of a quasi-continuum Neoproterozoic spectra punctuated by peaks at those same age intervals separated by minor lulls. Low Th/U rims of zircon crystals dated at ca. 577 Ma provide an estimate of the age of regional transpressional metamorphism. Samples of all age ranges are mostly calc-alkaline, magnesian and peraluminous, with moderately to highly fractionated LREE enrichment, negative Nb-Ta anomalies akin to convergent settings, and plot mainly within the volcanic arc field in tectonic discrimination diagrams. Nd-Sr isotope systematics indicate the involvement of juvenile Neoproterozoic melts from the mantle wedge, which upon mixing with Archean-Paleoproterozoic basement and contamination with the host metasedimentary rocks yield Mesoproterozoic TDM mainly at 1.14-1.44 Ga, near-chondritic εNd(t) and 87Sr/86Sri 0.703-0.710. We put forward a model involving a major continental back-arc zone related to the development of the Conceição magmatic arc, akin to the modern-day Taupo volcanic zone of New Zealand, crosscutting NE Brazil and presumably continuing through the schist belts of Nigeria and Cameroon. The main magmatic flare ups might have been induced by extra-arc phenomena, such as collision of the West African paleocontinent with the northwestern Borborema edge due to closure of the exterior Goiás-Pharusian Ocean, force-speeding subduction in the interior V-shaped oceanic basins that constituted the Transnordestino-Central African Ocean and generating clockwise windshield-wiper-like rotation of the blocks back towards the São Francisco-Congo paleocontinent in a complete Wilson Cycle.
KW - Back-arc basin
KW - Continental arc magmatism
KW - Introversion tectonics
KW - West Gondwana
KW - Wilson Cycle
UR - http://www.scopus.com/inward/record.url?scp=85099060787&partnerID=8YFLogxK
U2 - 10.1016/j.gr.2020.11.015
DO - 10.1016/j.gr.2020.11.015
M3 - Article
AN - SCOPUS:85099060787
SN - 1342-937X
VL - 92
SP - 1
EP - 25
JO - Gondwana Research
JF - Gondwana Research
ER -