Physical Sciences and Mathematics Commons^™

Evidence Of Four Generations Of Monazite Growth In Proterozoic Migmatites Of The Santa Fe Range, North-Central New Mexico, Dan Heuer

Dan Heuer

No abstract provided.

Evidence For Monazite Growth At ~1.6 Ga And ~1.4 Ga In Proterozoic Migmatites Of The Santa Fe Range, North-Central New Mexico, Dan Heuer, Christopher Daniel

Dan Heuer

Supracrustal Proterozoic migmatites exposed in the Aspen Basin area of the Santa Fe Range represent the northernmost exposure of the Mazatzal (~1.65 Ga) crustal province. Two migmatite samples (plag-bt-ms-qtz-hem±grt) yield preliminary in-situ electron microprobe U-Th-total Pb ages from monazite that are ~1.4 Ga; however, 1 grain yields a core age of ~1.6 Ga.

Monazite are generally aligned subparallel to a regional moderately, south-dipping foliation (S1), indicating monazite growth was pre- or synkinematic. X-ray mapping of monazite shows variable U, Th, Pb, Y, and Ce zoning, interpreted to reflect three periods of monazite growth. Xenotime are relatively unzoned in most elements, …

Monazite Thermochronometry In Migmatites From North-Central New Mexico: Contact Metamorphism Or A Regional Mid-Crustal Melt-Rich Layer?, Dan Heuer, Christopher Daniel, Joseph Pyle

Dan Heuer

Monazite thermochronometry demonstrates that Proterozoic migmatites exposed in the central Santa Fe range and the Rincon range of north-central New Mexico preserve high-temperature monazite that crystallized near 1.4 Ga. No 1.4 Ga plutons are exposed in the Rincon range; however, undated plutons are present in the Santa Fe Range and a contact metamorphic setting is possible. Alternatively, partial melting in these two areas may represent a regional, mid-crustal, melt-rich layer.

Subhedral monazite in both areas are commonly aligned subparallel with the dominant regional foliation. Monazite from the central Santa Fe range show three distinct compositional domains. Relatively high-Y cores yield …

Evidence For A Normal P-T Gradient And Top-North Displacement In The Central Bhutan Himalaya: Shear Sense And P-T Estimates From The Chekha Fm. And The Greater Himalayan Sequence, Dan Heuer, John Witmer, Adam Kahler, M. Ryan Delaney, Adam Dennis, Djordje Grugic, Christopher Daniel

Dan Heuer

Upper amphibolite facies metasedimentary rocks at the base of the Chekha Fm overlie the partially melted Greater Himalaya Sequence (GHS) and likely correlate with the Everest Series in the Mt. Everest massif. From the base of the Chekha Fm, metamorphic grade decreases to slates and unmetamorphosed rocks of the Tethyan sedimentary series (TSS) with increasing elevation. The Chekha Fm is separated from both the GHS and the overlying TSS by normal-sense shear zones related to the south Tibetan Detachment zone (STDZ).

Five samples from near the base of the Chekha Fm are characterized by the mineral assemblage Grt-Bt-St. Garnet crystals …