1990/11/10 by Frank Perry, W. Scott Baldridge, Donald J. DePaolo +1 · 1 citation
Earth and Planetary Sciences · #Geological and Geochemical Analysis #High-pressure geophysics and materials #earthquake and tectonic studies #Geology #Rhyolite #Fractional crystallization (geology) #Geochemistry #Crust #Continental crust #Magma chamber #Volcanic rock #Basalt #Igneous differentiation #Volcano #Magma #Earth science #Petrology
paper · doi:10.1029/jb095ib12p19327
openalex publication_date 1990/11/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23
In this paper we present geologic mapping, K‐Ar chronology, major and trace element data, mineral chemistry, and Nd, Sr, and O isotopic data for volcanic rocks of the Mount Taylor volcanic field (MTVF). The MTVF lies on the tectonic boundary between the Basin and Range province and the southeastern Colorado Plateau and is dominated by Mount Taylor, a composite volcano active from ≈ 3 to 1.5 m.y. ago. Growth of the volcano began with eruption of rhyolite, followed by quartz latite and finally latite. Basalts erupted throughout the lifetime of the volcano. The compositional variations of MTVF rocks resulted primarily from fractional crystallization of mildly alkaline hy‐hawaiite magmas. Differentiation of magmas occurred in multiple, short‐lived magma chambers, a result of a low magma flux from the mantle that could not support a single, long‐lived chamber. Rare mixing of evolved hy‐hawaiite and rhyolite produced a few intermediate magmas, primarily in the early history of the field. Mixing may have occurred when rhyolite magmas in the lower crust ascended to upper crustal levels and were injected into the bases of mafic magma chambers. Small amounts of crustal assimilation accompanied fractional crystallization and affected all the evolved MTVF rocks. Assimilation/fractional crystallization occurred primarily in the lower crust as hy‐hawaiite differentiated to mugearite or latite. Early in the history of the field, evolved lower crustal magmas ascended into the upper crust, where density filtering and a reduced tensional stress field inhibited further ascent until magmas evolved to rhyolite or quartz latite. Later in the history of the field, latite magmas ascended directly from the lower crust and erupted without further significant differentiation because of increased crustal extension.