Detrital zircon evidence for Paleoproterozoic West African crust along the eastern North American continental margin, Georges Bank, offshore Massachusetts, USA.

Basement rocks from the Continental Offshore Stratigraphic Test (COST) No. G-1 petroleum exploration well, Georges Bank, offshore Massachusetts, USA, show the first direct evidence for a fragment of Paleoproterozoic West African crust preserved along the eastern North American continental margin. Detrital zircon from two metawacke samples near the base of the core yielded ca. 3.05-1.90 Ga laser ablation-inductively coupled plasma-mass spectrometry dates, with a predominant 2.2-2.0 Ga population. This detrital zircon signature is consistent with that in the Taghdout Group of the Anti-Atlas region, which is part of the Paleoproterozoic passive margin rocks deposited directly on the Archean-Paleoproterozoic WAC shortly after its formation. African provenance has previously been recognized for the Suwannee and Meguma terranes in the southern and northern Appalachians, respectively. However, these areas represent Neoproterozoic-Paleozoic sedimentary basins, deposited well over a billion years after formation of the Paleoproterozoic WAC and cover rocks, including those in the COST No. G-1 well. The Paleoproterozoic rocks in the COST No. G-1 well were likely amalgamated with the North American margin during final closure of the Rheic Ocean and assembly of Pangea near the end of the Paleozoic. [ABSTRACT FROM AUTHOR]