DETRITAL ZIRCON GEOCHRONOLOGY OF PALEOZOIC SEQUENCES IN NORTHWESTERN MEXICO INDICATING LAURENTIAN AND GONDWANAN PROVENANCE

Detrital zircon geochronology was performed in Palezoic sedimentary and metamorphic sequences along a N-S section from central Sonora to northern Sinaloa, northwestern Mexico. Cambrian arenites display plots typically founded along the southwestern Cordillera, with main group ages at 1.6-1.8 Ga, 1.4-1.5 Ga, and 1.0–1.3 Ga, reflecting the igneous-metamorphic basement of that region, which extends until north-central Sonora. Ordovician sequences from the northern and southern ends of the section also display detrital zircon plots typical of other southwestern Cordillera sequences with peaks at ~1.8 and 2.7 Ga, which suggest southward longshore transport of sediments likely arising from the Paleoproterozoic Mojave and Arquean Wyoming provinces respectively. An alternative option for far traveled sediments is the southward tectonic displacement of terranes. Detrital zircon plots of metavolcanosedimentary sequences of southern Sonora interpreted as deposited in abyssal environments indicate Laurentian derived sediments with the same peaks as the shelf deposits, but also a minor influence of Paleozoic igneous sources. At last, metasedimentary sequences of the Sonora-Sinaloa boundary yield zircon plots clearly related to Gondwanan terranes with main Neoproterozoic-Cambrian peaks at 534, 592, 627, 673 Ma, and younger smaller peaks at 475, 375, and 336 Ma.