An extensive, crustally-derived, 3325 to 3310 Ma silicic volcanoplutonic suite in the eastern Pilbara Craton: evidence from the Kelly Belt, McPhee Dome and Corunna Downs Batholith

New sensitive high resolution ion microprobe zircon U-Pb dating indicates t hat the eastern Pilbara Craton contains an extensive suite of variably defo rmed 3325 to 3310 Ma rhyolites, high-level quartz-feldspar porphyries and g ranitoids. These range in composition from Na-rich trondhjemite (low-K rhyo lite) to K-rich monzogranite, with silica-rich (> 68%) biotite (+/- hornble nde) bearing porphyritic granodiorites and monzogranites most abundant. Ini tial volcanism accompanied regional extension at similar to 3325 Ma and was followed by intrusion of high-level porphyritic stocks and emplacement of massive to foliated batholithic granitoids at similar to 3315 Ma. The compo sitions of this volcano plutonic suite suggest that the most likely source for parent magmas is older continental crust with tonalite-trondhjemite-gra nodiorite suite compositions. Crustally-derived silicic volcanic rocks and granitoids have traditionally been considered rare in pre-3.0 Ga granitoid- greenstone terranes. Evidence from the eastern Pilbara indicates that magma tic recycling of continental crust has occurred at least as early as 3.3 Ga . (C) 1999 Elsevier Science B.V. All rights reserved.