The structural architecture of the CITZ constitutes a set of subparallel crustal scale shear zones occurring mostly at the boundaries of distinct lithological assemblages including the supracrustals, gneisses, and granulite belts.
Such a model is not in itself inconsistent with models involving lithospheric delamination, but I find it hard to see how the highest supracrustal sedimentary rocks in the core of the Cantabrian Orocline could have been preserved if a lithosphere-detaching thickening had taken place here.
The samples they studied come from the Nuvvuagittuq Supracrustal belt, a sedimentary banded iron formation located in the Archean Superior craton.
Given the apparent thickness of the (meta)sedimentary supracrustal units, the crystalline crust beneath this area is quite thin (< 20 km) supporting the hypothesis that there may have been delamination of (lower) continental crust in this area involved in the evolution of the seismic Vrancea zone.
The Mesoproterozoic Svinsaga Formation overlies a major unconformity (sub-Svinsaga unconformity) in the Telemark Supracrustal rocks (southern Norway).
The Isua supracrustal belt, or I.S.B., as it is formally known, is an outcropping in southwest Greenland, right at the edge of the inland ice sheet.
Writing in the journal Nature, Friend, together with a team of Australian scientists including his long-term collaborator Allen Nutman of the University of Wollongong, reveal how they discovered what they believe to be stromatolites in rocks of the Isua supracrustal belt in southwest Greenland.
But the oldest known rocks on Earth are in Greenland, where a formation known as the Isua supracrustal belt (ISB) dates to between 3.7 billion and 3.8 billion years old.
High ammonium contents 54-955 ppm) have been found in authigenic clays of the Isua supracrustal rocks of Western Greenland, suggesting that clays were major sinks of NH4+ or other nitrogen compounds on the Earth's surface already at 3800 Ma [2].
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