An overview of the geochemistry of Eoarchean to Mesoarchean ultramafic to mafic volcanic rocks, SW Greenland: Implications for mantle depletion and petrogenetic processes at subduction zones in the early Earth

Detrital zircon U–Pb ages and Hf-isotope systematics from the Gadag Greenstone Belt: Archean crustal growth in the western Dharwar Craton, India

“…Knowledge of early crustal growth processes is fundamental to understanding the evolution of the early earth (e.g., Amelin et al, 1999;Kinny and Maas, 2003;Harrison et al, 2005;Hawkesworth and Kemp, 2006;Kramers, 2007;Scherer et al, 2007;Condie and Kröner, 2011;Polat et al, 2011). The discovery of 3.6-4.4 Ga detrital zircons in younger sedimentary rocks allows ancient crustal remnants to be identified and characterized, and inferences to be made about their source rock and formation conditions (Mojzsis et al, 2001;Wilde et al, 2001).…”

Geochronology and geochemistry of 2.5 to 2.4Ga granitic plutons from the southern margin of the North China Craton: Implications for a tectonic transition from arc to post-collisional setting

“…The protoliths of greenstone belts are generally believed to be derived from the mantle in a rift setting, marginal basin or continental-margin environment (e.g., Kröner, 1985). TTG assemblages and greenstone belts provide important constraints for the evolution of Precambrian continental crust (Polat et al, 2011;Zhai and Santosh, in press). On the other hand, wide-spread K-rich GGM suites have been considered to be closely related to craton stabilization process, such as those reported in the Rum Jungle Complex of the North Australia Craton (Drüppel et al, 2009) and the Wyoming Craton in North America (Frost et al, 1998).…”

A Geochemical Overview of Mid-Archaean Metavolcanic Rocks from Southwest Greenland

“…Finally, recent metamorphic modelling also points to pressure-temperature paths that are consistent with subduction zone settings [11,12]. Although the region has generally experienced amphibolite-to granulite-facies metamorphism, the geochemical composition of the metavolcanic belt have generally not been significantly affected, although there are areas which have indeed locally experienced melt loss and thus geochemical modification [2,6]. It is also important to point out that there appears to have been Eoarchaean basement for at least some of the Mesoarchaean supracrustal belts, as documented for the 3075 Ma Ivisaartoq Supracrustal Belt [13].…”

“…These metavolcanic rocks occur as random inclusions and enclaves ranging in scales from decimeter to kilometer within the dioritic-tonalitic orthogneiss that comprises the continental crust of the North Atlantic Craton [5]. Systematic geological studies have been carried out on many individual metavolcanic rock suites in the region, and essentially all studies have concluded that they formed in a subduction zone-related setting [6,7]. However, this conclusion hinges on the negative Nb-Ta-Ti-anomalies observed in the geochemical data for the metavolcanic rocks, which resembles the trace element systematics of modern-style volcanic arc rocks [8].…”