Geology of the Monte Largo Hills area, New Mexico: Structural and metamorphic study of the eastern aureole of the Sandia Pluton
J. Michael Timmons, Karl E. Karlstrom, and Eric Kirby

Abstract:

The easternmost aureole of the 1.42 Ga Sandia pluton is exposed in the Monte Largo Hills area, east of the Sandia Mountains in central New Mexico. The Sandia pluton and aureole record the dynamic interaction of deformation, magmatism and metamorphism. Heat from emplacement created a 2-km-wide thermal aureole within which syn-emplacement ductile deformation is recorded by shallow lineations and syntectonic contact metamorphic porphyroblasts in country rock and by S-C fabrics and dynamically recrystallized feldspar porphyroclasts in granite. Recent 1:10,000 mapping suggests that the roof of the Sandia pluton is shallowly SE-dipping and truncates vertically foliated supracrustal rocks of interlayered metarhyolite, amphibolite, quartzite and muscovite schist. Metamorphic grade increases toward the pluton from upper greenschist regional metamorphism of the distant country rock to sillimanite grade contact metamorphism. Pluton emplacement postdates the main subvertical fabric, but was synchronous with dextral strike slip. The Monte Largo Hills area thus helps define the eastern edge of the Sandia pluton and contributes to a growing understanding of the thermal and structural setting for 1.4 Ga
tectonism.


Citation:

  1. Timmons, J. Michael; Karlstrom, Karl E.; Kirby, Eric, 1995, Geology of the Monte Largo Hills area, New Mexico: Structural and metamorphic study of the eastern aureole of the Sandia Pluton, in: Geology of the Sante Fe Region, Bauer, Paul W.; Kues, Barry S.; Dunbar, Nelia W.; Karlstrom, K. E.; Harrison, Bruce, New Mexico Geological Society, Guidebook, 46th Field Conference, pp. 227-232.

More information...