Syntectonic emplacement of the Harding Pegmatite, Taos County, New Mexico
Clyde C. Northrup and C. K. Mawer
The Harding pegmatite of Taos County, New Mexico, displays evidence of internal and marginal deformation. Within the pegmatite, quartz exhibits undulose extinction and contains well-developed subgrains. Lath-shaped spodumene crystals are broken, kinked and folded. Both the hanging-wall contact of the pegmatite against strongly foliated and lineated amphibolite, and the internal contact between the quartz and quartz-lath spodumene zones, show cuspate-lobate folds. The folds display a range of amplitudes (up to 2 m) and variable wavelengths; fold hinges are parallel to the intersection of a foliation developed by shearing in the amphibolite with the pegmatite/amphibolite contact. The foliation fans divergently around the lobate hinges and into the cuspate hinges of the folds along the upper contact of the pegmatite. The morphology and orientation of the Harding pegmatite bodies with respect to the orientation and tectonic transport direction of shearing in the amphibolite are similar to those of extension fractures developed in brittle-ductile shear zones.
- Northrup, Clyde C.; Mawer, C. K., 1990, Syntectonic emplacement of the Harding Pegmatite, Taos County, New Mexico, in: Tectonic development of the southern Sangre de Cristo Mountains, New Mexico, Bauer, Paul W.; Lucas, Spencer G.; Mawer, Christopher K.; McIntosh, William C., New Mexico Geological Society, Guidebook, 41st Field Conference, pp. 201-206.