As the
oceanic crust subducts, it experiences a very high pressure but relatively low temperature style of regional metamorphism, and the basalt and gabbro are transformed to blueschist (or glaucophane schist) and then to eclogite (Figure 5).
"Our aim is to be able to use the
oceanic crust microfossil record as a model system to guide Martian exploration," Ivarsson explains.
It's related to southwards subduction of the Meso-Tethys
oceanic crust and slab breaking off (Zhu et al., 2009; Harris, Inger, & Ronghua, 1990; Coulon, Maluski, & Bollinger, 1986).
What is the difference in composition between the
oceanic crust and the continental crust?
Following this process, eventually in upper Cretaceous and Paleocene eras simultaneous with closure of the Neotethyan Ocean, some parts of the
oceanic crust have had obduction movement.
Hayasaka [12] suggested that the cumulate metagabbro (pyroxenite, anorthosite, and eucrite) in the Asago area is rather similar in petrography and geochemistry to those in the Oshima peninsula and Ayabe areas (Figure 1), thus suggesting that this metagabbro originated from a lower crustal section of
oceanic crust and was derived from the T-type MORB source (i.e., OB ophiolite) (Figure 2(a)).
The team measured oxygen concentrations in sediment cores collected above the rocky
oceanic crust, almost three miles below the sea surface, on the western edge of the remote Mid-Atlantic Ridge.
Local high rates of convergence at the Hellenic subduction zone (35mm/yr) are associated with back-arc spreading throughout Greece and western Turkey above the subducting Mediterranean
oceanic crust. Crustal normal faulting throughout this region is a manifestation of extensional tectonics associated with the back-arc spreading.