A record of Neoarchaean cratonisation from the Storo Supracrustal Belt, West Greenland

During the late Archaean, exotic juvenile continental (TTG) terranes assembled into stable cratons leading to continental emergence and deposition of shallow-marine sedimentary sequences. This period of cratonisation coincided with crustal reworking and maturation driving the production of granites sensu stricto on most cratons, and may mark a final transition to mobile-lid tectonics. We investigate the relative timing of continental assembly, stabilization, emergence, and maturation, during the formation of the North Atlantic Craton (NAC) in West Greenland from its constituent terranes, using geochemical data from zircon and monazite extracted from its oldest mature metasedimentary unit, the Storo quartzite. Zircons form two U-Pb age groups: (i) an older > 2820 Ma group with juvenile (elevated) EHf(t) and delta 18O, derived from weathering surrounding Mesoarchaean terranes; and (ii) a younger < 2700 Ma group with less radiogenic (lower) EHf(t) and elevated delta 18O that record post-burial metamorphism peaking ca. 2620 Ma. The quartzite protolith has a maximum depositional age of ca. 2830 Ma, and was deposited after final TTG formation but prior to granite magmatism at ca. 2715 Ma, during which time terranes had sufficiently assembled, stabilized, and emerged to form a common watershed. Cratons form via lateral accretion which requires strong continental lithosphere, for which one agent is crustal reworking and maturation. However, for the NAC, terrane assembly and emergence commenced prior to granite formation, and crustal reworking may be a response to lithospheric thickening. Cratonisation involves a series of complex, intertwined processes operating over 100's of millions of years, which together lead to the development of thick, stable, continental lithosphere. Studies of ancient mature metasediments such as the Storo quartzite can help build timelines for these processes to ultimately better understand their choreography and co-dependencies, that together produced Earth's enduring cratons.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

During the late Archaean, the assembly and stabilization of juvenile continental terranes contributed to the emergence and deposition of shallow-marine sedimentary sequences. This study examines the formation of the North Atlantic Craton in West Greenland and investigates the timing of continental assembly, stabilization, emergence, and maturation. The geochemical data from zircon and monazite extracted from the Storo quartzite, the oldest mature metasedimentary unit, provide insight into the geological processes involved. The findings contribute to our understanding of the complex processes that led to the development of enduring cratons.