FROM THE PICURIS TO THE PINWARE: THE TALE OF A 4500 KM LONG CONVERGENT MARGIN AND MESOPROTEROZOIC CA. 1.50 TO 1.36 GA OROGENIC EVENTS

Precambrian rocks of Arizona and New Mexico preserve a significant record of Mesoproterozoic, ca. 1500 Ma to 1450 Ma deposition, followed by ca. 1450 Ma to 1360 Ma regional metamorphism, deformation, and plutonism that defines the Picuris Orogeny. Depositional age constraints come from detrital zircon and metarhyolite clast crystallization ages from the Marquenas Formation, New Mexico, and detrital zircon ages in metasedimentary rocks and zircon crystallization ages from metatuff layers in the Yankee Joe and Trampas groups of Arizona and New Mexico, respectively. Both Mesoproterozoic and underlying Paleoproterozoic rocks were subsequently buried to mid–crustal depths (8 to 25 km) and experienced regional greenschist to near-granulite facies metamorphism, local contact metamorphism and regional contractional deformation. Timing of metamorphism is constrained by a range of minerals and isotopic systems to be ca. 1450 Ma to ca. 1360 Ma.

We propose that the ca. 1450 Ma to 1360 Ma Picuris Orogeny in the southwestern US and the 1500 Ma to 1450 Ma Pinware Orogeny of eastern Canada reflect a 4000-5000 km long Mesoproterozoic convergent plate margin along the southern margin of Laurentia. The Pinware Orogeny is attributed to an Andean style plate margin. Such a model may be consistent with the Picuris Orogeny.