Timing of Proterozoic regional deformation in the southern Manzano Mountains, central New Mexico
- New Mexico Bureau of Mines and Mineral Resources, Socorro, NM (United States)
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Earth, Atmospheric, and Planetary Sciences
- Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Geology
Early Proterozoic supracrustal and plutonic rocks of the Manzano Mtns have sustained a remarkably complex history of ductile deformation, metamorphism, and plutonism. A comparison of field relations and deformational features between the two southernmost plutons suggests that they differ greatly in timing of intrusion with respect to regional deformation. The Monte Largo pluton consists of medium-grained granodiorite and quartz monzonite that is bounded on three sides by strongly deformed quartzite and phyllite. An S1 foliation is folded by upright, N-trending folds (F2). S2, axial planar to F2, is mylonitic along the E pluton margin. The degree of deformation in the pluton is comparable to that in the country rock. The Monte Largo pluton has a U-Pb zircon age of ca. 1.66 Ga. The Priest pluton is a 10-km-long, N-S elongate, megacrystic quartz monzonite that is intrusive into quartzite sand schists. Large microcline crystals define a magmatic foliation. The body contains a weakly to moderately well-developed NE-striking tectonic foliation defined by flattened quartz grains, best developed along the W margin. On the N end of the pluton, map-scale folds in quartzite and schist have been cross-cut, and a contact metamorphic aureole cross-cuts country rock structures. The degree of deformation in the pluton is significantly less than that of country rock quartzites, some of which are mylonitic. The Priest Pluton has a U-Pb zircon age of ca. 1.45 Ga. These data suggest that the ca. 1.66 Ga Monte Largo pluton is syntectonic with respect to regional deformation, whereas the ca. 1.45 Ga priest pluton is post-tectonic with respect to the regional deformation.
- OSTI ID:
- 5935385
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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