DETRITAL ZIRCON EVIDENCE FOR MIXING OF MAZATZAL PROVINCE AGE DETRITUS WITH YAVAPAI (CA. 1700–1740 MA) AND OLDER DETRITUS IN THE CA. 1650 MA MAZATZAL PROVINCE OF CENTRAL NEW MEXICO, USA

Preliminary detrital zircon age distributions from Mazatzal crustal province quartzite and schist exposed in the Manzano and Pedernal mountains of central New Mexico are consistent with a mix of detritus from Mazatzal age (ca. 1650 Ma), Yavapai age (ca. 1720 Ma) and older sources. A quartzite sample from the Blue Springs Formation, Manzano Mountains shows two dominant peak ages of 1735 Ma and 1790 Ma with a minimum peak age of ca. 1650 Ma. Quartzite and micaceous quartzite samples from near Pedernal Peak give unimodal peak ages of ca. 1695 Ma and ca. 1738 Ma with minimum detrital zircon ages of ca. 1625 Ma and 1680 Ma, respectively. A schist sample from the southern exposures of the Pedernal Peak area gives a unimodal peak age of ca. 1680 Ma with a minimum age of ca. 1635 Ma. Minor amounts of older detritus (>1800 Ma) possibly reflect Trans-Hudson, Mojave, Wyoming province and older Archean sources. The Blue Springs Formation metarhyolite from near the top of the Proterozoic section in the Manzano Mountains yields a preliminary U–Pb zircon crystallization age of 1621 ± 5 Ma and provides a minimum age constraint for deposition in the Manzano Mountains.

Cathodoluminescence images of detrital zircon from the both areas show igneous zoning characteristics. Zircon range in size from 50 to 250 µm with a majority of the grains being sub-angular to well rounded. Angular, euhedral to subhedral grains are less common. Igneous zircon from the metarhyolite are euhedral to subhedral and range in size from 100 to 200 µm.

These new data are similar to previously reported age distributions in the Burro and San Andres mountains southern New Mexico and suggest that Yavapai province age detritus was deposited and intermingled with Mazatzal province age detritus across much of the Mazatzal crustal province in New Mexico. Regional metamorphism and deformation in the area must postdate ca. 1610 Ma–1620 Ma rhyolite crystallization and is attributed to the Mesoproterozoic ca. 1480-1400 Ma Picuris Orogeny.