Research Interests

Primary research interests lie in the application of petrology to geologic problems; research has been conducted on a variety of topics, including petrogenesis of basaltic rocks, paleovolcanology, and tectonics. Petrology and geochemistry have been used principally to investigate the origins of igneous rocks, both lavas and pyroclastic deposits, and their tectonic settings. Research has concentrated on understanding continental flood basalts, their petrogenesis, and relationships between plumes and plate stresses in their formation. Petrology of clastic and volcaniclastic sequences has been used to address tectonic settings of sedimentary basins and volcanic sequences.

Research Programs

1) Continental flood basalts

Research has been conducted over a number of years on the continental flood basalt province in Antarctica (Ferrar Magmatic Province or Large Igneous Province) associated with Gondwanaland break-up. The Ferrar includes thick dolerite (diabase) sills intruded into the Permo-Triassic Beacon Supergroup, and extrusive rocks that include pyroclastic deposits overlain by the Kirkpatrick Basalt lavas.

The timing and duration of Ferrar magmatism has been a focus, and this is being extended to other regions (Antarctica ,Tasmania, South Africa) where Middle Jurassic break-up magmatism is recorded. Geochemically the Ferrar is characterized by enriched Sr and Nd isotope ratios and crust-like trace element ratios, even in the most mafic rocks (ca. 9% MgO); how the Ferrar acquired the overwhelming crustal signature remains a major problem. Currently these problems are being investigated in collaboration with Drs. K.A. Foland and T.H. Fleming. A silicic tuff sequence of probable Early Jurassic age occurs below the Ferrar basaltic pyroclastic rocks. The precise age and relationship to the Ferrar is unclear, as well as the geochemical signature because of secondary processes. These rocks may be related to an episode of back-arc extension rather than to break-up processes.

2) Paleovolcanology

The Ferrar flood lavas were preceded by a phase of phreatomagmatic activity that deposited unusually thick basaltic tuff-breccias and subordinate base-surge and airfall beds. The individual tuff-breccia beds are uncommonly thick, if not unique in the occurrence of 400-m-thick sections that lack any sign of bedding. These tuff-breccias, which contain abundant sedimentary rock clasts, exhibit evidence for magma/water interaction at depth in the underlying Permo-Triassic stratigraphic column. Their mode of formation and mechanism of deposition are problematic.

The Ohio State University field station is situated in Sanpete Valley about 120 miles south of Salt Lake City. Apart from the Cretaceous and Lower Tertiary strata related to the Sevier and Laramide Orogenies, extensive mid-Tertiary volcaniclastic sedimentary rocks and pyroclastic deposits occur in the Sanpete Valley region where they are known as the Moroni Formation. The Moroni Formation was emplaced during the transition from Laramide compression to Basin and Range extension. The source of the volcanic components has been regarded as the Tintic center which lies about 50 miles northwest and across the southern Wasatch Mountains (Mt. Nebo and the Charleston-Nebo Thrust Plate) but that scenario is incompatible with mid-Tertiary paleotopography. Studies on the Moroni Formation are directed at the tectonic and paleovolcanologic setting.

3) Secondary mineralization in volcanic and sedimentary sequences

The Middle Jurassic Ferrar basaltic rocks show widespread zeolitization and deposition of other secondary minerals. Zeolitization in flood basalt sequences is commonly regarded as following closely on eruption while the lava pile is still hot, but dating of apophyllite in the Ferrar extrusive rocks shows that a major part of the secondary mineralization occurred in the mid to late Cretaceous. This is thought to reflect paleohydrologic changes consequent on the initial stages of uplift which ultimately formed the Transantarctic Mountains. This research is being conducted in collaboration with Drs K.A. Foland and T.H. Fleming.

4) Sedimentary petrology and tectonic settings of depositional basins

The volcanic components of sand-sized detritus in clastic sequences reflects the source terrains and magmatic events,and have been used to document an active calc-alkaline arc during deposition of the Permo-Triassic strata in the Transantarctic Mountains, and the evolving source terrain for Upper Cretaceous to Lower Tertiary marine strata off the Antarctic Peninsula. Arkoses in the Lower Jurassic volcaniclastic beds beneath the Ferrar tuff-breccias have demonstrated a rift setting for silicic volcanism.

Current projects include:

paleovolcanology of Jurassic basaltic pyroclastic deposits that preceded eruption of the Gondwanaland break-up continental flood basalts in Antarctica
paleovocanological setting of the mid-Tertiary Moroni Formation, central Utah.
secondary mineralization in Jurassic pyroclastic rocks in the Transantarctic Mountains
Jurassic tectonic evolution of the Transantarctic Mountains.