Early Precambrian mantle derived rocks in the southern Prince Charles Mountains, East Antarctica: age and isotopic constraints

Mafic and ultramafic rocks occurring as lenses, boudins, and tectonic slabs within metamorphic units in the
southern Mawson Escarpment display mantle characteristics of either a highly enriched, or highly depleted nature.
Fractionation of these mantle rocks from their sources may be as old as Eoarchaean (ca 3850 Ma) while their tectonic
emplacement probably occurred prior to 2550 Ma (U-Pb SHRIMP data). These results provide for the first time
evidence for Archaean suturing within East Antarctica. Similar upper mantle sources are likely present in the northern
Mawson Escarpment. A younger age limit of these rocks is 2200 Ma, as indicated by presumably metamorphic zircon
ages while their magmatic age may be constrained by single zircon dates at 2450-2250 Ma. The area of the northern
Mawson Escarpment is most likely of ensimatic origin and includes mafic rocks which were derived from distinct
mantle source(s) during Palaeoproterozoic time.