Universidad Complutense de Madrid
E-Prints Complutense

Reconstructing subduction polarity through the geochemistry of mafic rocks in a Cambrian magmatic arc along the Gondwana margin (Órdenes Complex, NW Iberian Massif)

Impacto

Downloads

Downloads per month over past year



Andonaegui Moreno, Pilar and Sánchez Martínez, Sonia and Castiñeiras García, Pedro and Abati Gómez, Jacobo and Arenas Martín, Ricardo (2016) Reconstructing subduction polarity through the geochemistry of mafic rocks in a Cambrian magmatic arc along the Gondwana margin (Órdenes Complex, NW Iberian Massif). International Journal of Earth Sciences, 105 (3). pp. 713-725. ISSN ISSN: 1437-3254, online ISSN: 1437-3262

[img] PDF
Restringido a Repository staff only

1MB

Official URL: https://link.springer.com/journal/531/105/3


URLURL Type
https://springer.com/journalUNSPECIFIED


Abstract

In the allochthonous complexes of the NW Iberian Massif, the Upper Units have been interpreted as a section of a peri-Gondwanan magmatic arc active from Middle Cambrian to Early Ordovician times. The main plutonic bodies intruding the arc metasediments are the Monte Castelo gabbronorites and the Corredoiras orthogneisses, which include minor metagabbronorite bodies, both dated at ca 500 Ma. The geochemical features of Monte Castelo metagabbronorites indicate a tholeiitic affinity, with negative Nb anomaly; its 143Nd/144Nd ratios are high (0.5143119–0.513019), whereas initial 87Sr/86Sr ratios are low (0.702562–0.703174), with positive εNdi values (+7.8 to +5.4). The geochemistry of Corredoiras metagabbronorites indicates a calc-alkaline affinity, also with negative Nb anomaly, low 143Nd/144Nd (0.512575– 0.512436) and high initial 87Sr/86Sr (0.705082–0.706684), εNdi values ranging between −0.65 and +1.83. In the εNd versus age diagram, Monte Castelo samples show compositions equivalent to the contemporaneous depleted mantle. Corredoiras metagabbros have much lower εNdi values compared with Monte Castelo samples, with older model ages ranging between 1165 and 1291 Ma, suggesting contamination of the original mafic mantle-derived magmas with an older continental crust. These geochemical features can be linked to the setting of a mature volcanic arc, in which Monte Castelo metagabbros were located close to the trench, while Corredoiras metagabbros would be in a relatively distant position from the trench, thus indicating subduction polarity.


Item Type:Article
Uncontrolled Keywords:Peri-Gondwanan Cambrian arc , Subduction polarity , Gabbronorites , Sr and Sm–Nd isotopic geochemistry , Órdenes Complex , NW Iberia
Subjects:Sciences > Geology > Petrology
ID Code:55120
Deposited On:29 Apr 2019 06:33
Last Modified:29 Apr 2019 08:34

Origin of downloads

Repository Staff Only: item control page