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Theses and Dissertations

Geology

2015

Rejuvenation

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Cooling Before Super-Eruption: No Role For Rejuvenation In The Cottonwood Wash Tuff Magma Body, Southern Great Basin Ignimbrite Province, Utah And Nevada, Keryn Tobler Ross Dec 2015

Cooling Before Super-Eruption: No Role For Rejuvenation In The Cottonwood Wash Tuff Magma Body, Southern Great Basin Ignimbrite Province, Utah And Nevada, Keryn Tobler Ross

Theses and Dissertations

The model of rejuvenation of a near-solidus crystal mush to produce large volumes of crystal-rich magma is tested here by analyzing the mineralogical, chemical, modal, and physical characteristics of the 31.1 Ma super-eruptive (2000 km3) Cottonwood Wash Tuff. It is the oldest in a series of three so-called “monotonous intermediate” ignimbrites from the Indian Peak-Caliente volcanic field in southern Utah and Nevada. A crystal-rich (~50% Pl > Qz ≈ Hbl ≈ Bt > Mag ≈ Ilm > Cpx + Zrn + Ap+ Po) dacite (62 – 69 wt% SiO2), the Cottonwood Wash Tuff is similar in age, volume, mineralogy, crystallinity, and elemental composition …


Cooling Before Super-Eruption: No Role For Rejuvenation In The Cottonwood Wash Tuff Magma Body, Southern Great Basin Ignimbrite Province, Utah And Nevada, Keryn Tobler Ross Dec 2015

Cooling Before Super-Eruption: No Role For Rejuvenation In The Cottonwood Wash Tuff Magma Body, Southern Great Basin Ignimbrite Province, Utah And Nevada, Keryn Tobler Ross

Theses and Dissertations

The model of rejuvenation of a near-solidus crystal mush to produce large volumes of crystal-rich magma is tested here by analyzing the mineralogical, chemical, modal, and physical characteristics of the 31.1 Ma super-eruptive (2000 km3) Cottonwood Wash Tuff. It is the oldest in a series of three so-called "monotonous intermediate" ignimbrites from the Indian Peak-Caliente volcanic field in southern Utah and Nevada. A crystal-rich (~50% Pl > Qz ≈ Hbl ≈ Bt > Mag ≈ Ilm > Cpx + Zrn + Ap+ Po) dacite (62 - 69 wt% SiO2), the Cottonwood Wash Tuff is similar in age, volume, mineralogy, crystallinity, and elemental composition …