The Cabo Ortegal complex (northwestern Iberian massif) is a klippen formed of several structural units stacked during the Hercynian collision. All these units include ultramafic rocks, metabasites and quartz-feldspathic gneisses affected by different metamorphic conditions. The Bacariza formation is heterogeneous showing a conspicuous layering mainly defined by alternate high-pressure ultrabasic-to-basic granulites, retrogressed garnet amphibolites of intermediate composition and rare acid rocks forming garnet trondhjemitic gneisses. This layering is inherited from a gabbroic protolith showing a composition rich in Fe and Ti. Major and trace elements of these rocks can be correlated to continental tholeiitic series of extensional settings. These high-pressure granulites are situated in normal contact between ± serpentinised ultramafic rocks and other high-grade metabasites with less-evolved and more-depleted composition comparable to T-type and N-type MORB. It is suggested that the layered gabbro-type protolith was part of a continuous mafic crust. This crust was initially formed during Early Ordovician in a continental extensional setting and progressively evolved to oceanic spreading.
|Translated title of the contribution||Geochemical Evolution of High-Pressure Mafic Granulites from the Bacariza Formation (Cabo Ortegal Complex, NW Spain): An Example of a Heterogeneous Lower Crust|
|Original language||Multiple languages|
|Publication status||Published - 1 Jan 1997|
- Hercynian belt
- Mafic granulites