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Structural assemblage of high‐pressure mantle and crustal rocks in a subduction channel (Cabo Ortegal, NW Spain)
Author(s) -
Ábalos B.,
Puelles P.,
Gil Ibarguchi J. I.
Publication year - 2003
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2002tc001405
Subject(s) - geology , lineation , nappe , subduction , gneiss , mantle (geology) , eclogite , petrology , metamorphic rock , granulite , lithosphere , metamorphic facies , geochemistry , tectonics , seismology , geomorphology , structural basin , facies
High‐pressure metamorphic fold‐nappes and ductile thrusts occur in the Cabo Ortegal upper allochthons. They involve arc‐root lithospheric mantle peridotites, high‐pressure volcanic‐arc granulites, normal mid‐oceanic ridge basalt eclogites and shallow crustal volcanosedimentary high‐pressure gneiss units. Confluence of units from such disparate tectonic settings occurred at an eo‐Hercynian convergent plate margin. Their internal deformation, juxtaposition, and high‐pressure synmetamorphic reworking resulted from kinematically simple but intense and polyphase ductile deformations. Fold nappes exhibit a remarkable sheath‐like form and contain mineral and stretching lineations defined by high‐pressure mineral assemblages subparallel to fold axes. We argue that these structures outline the internal organization of high‐pressure sheets at deep tectonic realms of an oblique subduction/collision orogenic channel.