Palaeomagnetism of the Puerto Vallarta intrusive complex and the accretion of the Guerrero terrain, Mexico
Abstract The batholith exposed around Puerto Vallarta is part of the Guerrero tectonostratigraphic terrain, presumably accreted to Mexico during the Laramide orogenic phase. Fourteen sites on this batholith were studied palaeomagnetically and geochemically. Nine sites define a paleopole at 76.6°N, 181.8°E, with α 95 = 6.6°, coinciding with the reference pole for stable North America. It is proposed that no important movements of the region relative to North America have occurred since emplacement of the intrusive rocks ∼ 80 Ma ago. This would mean that the Guerrero terrain was accreted to the Mexican continental margin before that time. Geochemical data support this interpretation, characterizing the rocks as volcanic-arc granites intruded at an active continental margin.