Petrology of a Late Archaean, Highly Potassic, Sanukitoid Pluton from the Baltic Shield: Insights into Late Archaean Mantle Metasomatism

Geochemical and Nd isotope constraints on petrogenesis of granitoids from NW part of the eastern Dharwar craton: Possible implications for late Archaean crustal accretion

“…Breaking of the slab due to terrane accretion and consequent upwelling of hot asthenosphere (Fig. 10) progressive shifting of magma generation locale (Beakhouse and Davis, 2005;Calvert et al, 2004;Davies and Blanckenburg, 1995;Lobach-Zhuchenko et al, 2008;Whalen et al, 2004b). This scenario of hot juvenile magmatic accretion is also in agreement with the presence of high temperature, low pressure metamorphic assemblages in, and the recent tectonomagmatic interpretation of EDC, envisioning pervasive flow of hot, buoyant, partially molten, soft crust in a convergent set up (Chardon et al, 2011;Jayananda et al, 2011).…”

“…The porphyritic granodiorites share many geochemical characteristics of the Archaean sanukitoid suite (Halla, 2005;Kampunzu et al, 2003;Kapyaho, 2006;Lobach-Zhuchenko et al, 2008;Sarvothaman, 2001;Shirey and Hanson, 1986;Smithies and Champion, 2000;Stern and Hanson, 1991;Stevensen et al, 1999;Whalen et al, 2004b). Rocks of sanukitoid suites range from diorites to granites and, generally in comparison to TTG, are distinguished by their calc-alkaline nature, high Mg# (0.43-0.62), Cr (20-150 ppm), Ni (20-60 ppm), Sr (500-2000 ppm), Ba (800-2000 ppm), and P 2 O 5 (0.1-0.6 wt%), low Rb/Sr (0.04-0.16) and steeply fractionated REE (Ce N /Yb N = 10-50) with enriched LREE (Ce N = 65-200), depleted HREE (Yb N = 1-10) and no to slightly negative Eu anomalies (Martin et al, 2005(Martin et al, , 2009Moyen et al, 2003a;Smithies and Champion, 2000).…”

The gabbro (shoshonitic)–monzonite–granodiorite association of Khankandi pluton, Alborz Mountains, NW Iran

“…Fowler and Henney, 1996;Fowler et al, 2001;Jiang et al, 2002). The generation of these intermediate and silicic rocks, that in most cases dominates in volume over the outcropping gabbros, by either fractionation alone (Lobach-Zhuchenko et al, 2008;Shirey and Hanson, 1984;Shirey et al, 2001) or fractionation plus crustal assimilation (Fowler et al, 2001), is not well constrained and, thus, the role of these mantle magmas in crustal-making processes remains controversial. The possibility that at least part of the intermediate magmas (i.e.…”

Archaean granitoids: an overview and significance from a tectonic perspective

“…A slab breakoff has been suggested as the trigger of sanukitoid magmatism by, for example, Calvert et al (2004), Whalen et al (2004), Lobach-Zhuchenko et al (2008) and , and delamination is favoured by Gao et al (2004). Slab breakoff is thought to follow attempted subduction of buoyant continental lithosphere during continental collision (Wortel & Spakman 2000;van Hunen & van den Berg 2008).…”