Proterozoic thermal and deformational history and geochemical evolution of the 1.4 Ga Priest pluton and its aureole
type: CreativeWork
description: Paleoproterozoic (1.7-1.6 Ga) supracrustal rocks in the aureole of the 1.43 +/- 0.01 ga Priest pluton provide evidence for a polyphase Proterozoic metamorphic history in central New Mexico. This history involved pre-, syn-, and post-emplacement metamorphic mineral growth. The Priest pluton contact aureole is 1.2 kilometers wide and is characterized by two isograds (first appearance of sillimanite and staurolite, respectively). Garnet-biotite temperatures combined with assemblage data (sillimanite + K-feldspar) suggest an increase from 525 degrees to ~650 degrees Celsius toward the pluton at pressures of ~4 kbar, suggesting emplacement depths of ~12 km. An 40Ar/39Ar age of 1.44+/- 0.005 Ga for hornblende in the aureole suggests rapid cooling through ~500 degrees Celsius following pluton emplacement. The well-defined thermal aureole can be used to help constrain both pre- and post-emplacement metamorphisms. Pre-pluton metamorphism is recorded by amphibolite-facies inclusions inside contact metamorphic porphyroblasts. Included minerals are interpreted to be part of a regional metamorphic assemblage because similar minerals are found outside the aureole. P-T estimates outside the aureole suggest pre-pluton regional conditions near 525 degrees Celsius and 4 kbar. Post-emplacement greenschist-facies retrograde metamorphism was superimposed on the northern and southern parts of the contact aureole and is characterized by the replacement of contact-metamorphic porphyroblasts with muscovite and/or chlorite. Retrogression was most likely due to continued cooling following pluton emplacement. 40Ar/39Ar muscovite plateau ages from the aureole range from 1.39 to 1.36 Ga. These data bracket the retrograde metamorphism between 1.43 and 1.39-1.36 Ga, and suggest that ambient temperatures following pluton emplacement were about 350 degrees Celsius for a prolonged (30 Ma) period, suggesting slow cooling following 1.4 Ga plutonism. The 1.43 Ga Priest pluton in the southern Manzano Mou…
abstract: Paleoproterozoic (1.7-1.6 Ga) supracrustal rocks in the aureole of the 1.43 +/- 0.01 ga Priest pluton provide evidence for a polyphase Proterozoic metamorphic history in central New Mexico. This history involved pre-, syn-, and post-emplacement metamorphic mineral growth. The Priest pluton contact aureole is 1.2 kilometers wide and is characterized by two isograds (first appearance of sillimanite and staurolite, respectively). Garnet-biotite temperatures combined with assemblage data (sillimanite + K-feldspar) suggest an increase from 525 degrees to ~650 degrees Celsius toward the pluton at pressures of ~4 kbar, suggesting emplacement depths of ~12 km. An 40Ar/39Ar age of 1.44+/- 0.005 Ga for hornblende in the aureole suggests rapid cooling through ~500 degrees Celsius following pluton emplacement. The well-defined thermal aureole can be used to help constrain both pre- and post-emplacement metamorphisms. Pre-pluton metamorphism is recorded by amphibolite-facies inclusions inside contact metamorphic porphyroblasts. Included minerals are interpreted to be part of a regional metamorphic assemblage because similar minerals are found outside the aureole. P-T estimates outside the aureole suggest pre-pluton regional conditions near 525 degrees Celsius and 4 kbar. Post-emplacement greenschist-facies retrograde metamorphism was superimposed on the northern and southern parts of the contact aureole and is characterized by the replacement of contact-metamorphic porphyroblasts with muscovite and/or chlorite. Retrogression was most likely due to continued cooling following pluton emplacement. 40Ar/39Ar muscovite plateau ages from the aureole range from 1.39 to 1.36 Ga. These data bracket the retrograde metamorphism between 1.43 and 1.39-1.36 Ga, and suggest that ambient temperatures following pluton emplacement were about 350 degrees Celsius for a prolonged (30 Ma) period, suggesting slow cooling following 1.4 Ga plutonism. The 1.43 Ga Priest pluton in the southern Manzano Mou…
author: Thompson, Amy G.
language: English
keywords: Proterozoic, Proterozoic Deformational History, Proterozoic Thermal History, Proterozoic History, Geochemical Evolution, Priest Pluton
date published: 1996-07-01T07:00:00Z
date modified: 2026-07-24T05:26:22Z
provider: University of New Mexico
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of New Mexico

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property ID: Handle
value: http://hdl.handle.net/1928/24730