ARTÍCULO
Magmatic source and metamorphic grade of metavolcanic rocks from the Granjeno Schist: was northeastern Mexico a part of Pangaea?,
Torres Sánchez S. A., Augustsson C., Barboza-Gudiño J. R., Jenchen U., Ramirez Fernández J. A., Abratis M. and Scherstén A.,
(Published online in Wiley Online Library (wileyonlinelibrary.com). v. 9, p 361-384, DOI: 10.1002/gj.2702, 2015.
ABSTRACT:
The geochemistry of the metavolcanic rocks from the Granjeno Schist in northeastern Mexico indicates an origin in different tectonic environments: mid-ocean ridge and ocean island. High ratios of Hf/Th and Th/Nb (4.4–14 and 0.08–0.15), low ratios of LaN/YbN and LaN/SmN (0.74–1.7 and 0.60–1.4) and depleted LREE patterns in metabasalt display mid-ocean ridge characteristics. In contrast,the pattern of trace-element ratios and REEs in metabasalt and metapillow lava 60 km to the west indicates a magma source with ocean-island basalt characteristics. Both areas were metamorphosed during the Late Carboniferous (300 ± 4 Ma).