The rocks have undergone several periods of regional metamorphism, to at least upper amphibolite facies, and there was a subsequent phase of retrograde metamorphism.
12.
Phyllites are said to have a texture called " phyllitic sheen, " and are usually classified as having formed through low-grade metamorphic conditions through regional metamorphism metamorphic facies.
13.
The original rocks have been affected by the processes of regional metamorphism, folding, and faulting to form rocks such as schist, quartzite, phyllite, slate, marble, and limestone.
14.
The age of this belt is approximately 1.8 to 1.18 Ga . Regional metamorphism is believed to have deformed this area at approximately 1.4 Ga and metamorphic thrusting at approximately 1.16 to 1.12 Ga.
15.
This accretion event is recorded by widespread granite and granodiorite intrusions, which comprise over 70 % of the Yilgarn craton; voluminous tholeiitic basalt and komatiite volcanism; regional metamorphism and deformation as well as the emplacement of the vast majority of the craton's endowment in gold mineralisation.
16.
Regional metamorphism tends to make the rock more indurated and at the same time to give it a foliated, shistose or gneissic texture, consisting of a planar arrangement of the minerals, so that platy or prismatic minerals like mica and hornblende have their longest axes arranged parallel to one another.
17.
Efforts to depict initial lithologies and tectonic formation of the Isua Belt have been difficult due to the immense episodes of regional metamorphism the area has experienced, which is why most efforts have been focused on the northern complex, called the Isukasia Terrane, where the area exhibits a lower metamorphic grade.
