Summary: ABSTRACT
Large-volume granitic plutons in the
Burro Mountains, southwestern New Mex-
ico, cover an area of 1300 km2
and include
biotite leucogranite and biotite-hornblende
granodiorite. These intrusions are part of
the ca. 1.4 Ga granite and rhyolite province
stretching across Laurentia. U-Pb zircon
dating of five samples of the biotite leuco-
granite yielded ages ranging from 1469 ±
12 to 1455 ± 11 Ma (2s uncertainty). Three
samples of granodiorite range from 1470 ±
16 Ma to 1459 ± 14 Ma. All of the zircon
ages are within error and together have a
weighted mean age of 1462 ± 3 Ma, but the
granodiorite is older than the granite based
on crosscutting relationships.
Pressure and temperature estimates from
metapelitic country rock, the first from

Source: Amato, Jeff - Department of Geological Sciences, New Mexico State University

Collections: Geosciences