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Full-Text Articles in Tectonics and Structure

Timescales Of Magma Transport In The Columbia River Flood Basalts, Determined By Paleomagnetic Data, Joseph Biasi, Leif Karlstrom Oct 2021

Timescales Of Magma Transport In The Columbia River Flood Basalts, Determined By Paleomagnetic Data, Joseph Biasi, Leif Karlstrom

Other Staff Materials

Flood basalts represent major events in Earth History, in part because they are linked to large climate perturbations and mass extinctions. However, the durations of individual flood basalt eruptions, which directly impact potential environmental crises, are poorly constrained. Here we use a combination of paleomagnetic data and thermal modeling to create a magnetic geothermometer (MGT) that can constrain the active transport lifetime of magmatic conduits and intrusions. We apply the MGT technique to eight feeder dike segments of the Columbia River basalts (CRB), demonstrating that some dike segments were actively heating host rocks for less than one month, while other …


Geology Of The Clairmont Springs 7.5-Minute Quadrangle And Geochronology Of The Alabama Blue Ridge, Adelie Ionescu Aug 2021

Geology Of The Clairmont Springs 7.5-Minute Quadrangle And Geochronology Of The Alabama Blue Ridge, Adelie Ionescu

MSU Graduate Theses

The Alabama Blue Ridge (USA) of the southern Appalachians contains metamorphic rocks and structures associated with island arc accretion and continent-continent collision that record the Acadian and Alleghenian orogenies. The western Blue Ridge is underlain by Cambrian to Mississippian, clastic and carbonate, low-grade, greenschist facies metamorphic Talladega belt that formed outboard from the Alabama promontory or along the Laurentian margin. The eastern Blue Ridge contains the Neoproterozoic to Paleozoic, lithologically diverse, high grade, middle to upper amphibolite facies Ashland Supergroup. Geologic mapping of the Clairmont Springs 7.5- minute quadrangle unveils tectonic relationships between the eastern and western Blue Ridge and …


Geochemical Classification Of The East Central Minnesota Batholith, Simon Taylor Apr 2021

Geochemical Classification Of The East Central Minnesota Batholith, Simon Taylor

Ramaley Celebration

The East Central Minnesota Batholith (ECMB) is a series of granitic plutons exposed along the Sauk river valley near St. Cloud Minnesota. The currently accepted understanding of the processes that generated these plutons relies on the location and age of emplacement. The location of the ECMB is within a terrain that was accreted onto the North American continent during the Penokean orogeny between 1875 to 1835 Ma (Van Schmus, 1976). However the granites within the ECMB are younger than that having ages between 1772 Ma and 1783 Ma (Holm et al., 2005), similar to ages for the Yavapai orogeny occurring …


Analysis Of Water Concentration Formed Within Deformed Synthetic Quartz Crystals, Andrew Steward Jan 2021

Analysis Of Water Concentration Formed Within Deformed Synthetic Quartz Crystals, Andrew Steward

Williams Honors College, Honors Research Projects

Analyzing the strength of synthetic quartz is essential to understanding the strength of natural milky quartz, which likely controls the strength of Earth’s continental crust. Synthetic quartz is sometimes used for deformation experiments because it has a homogenous water distribution unlike natural milky quartz. The purpose of this study is to determine if annealing synthetic quartz at T = 600°C will convert the water in synthetic quartz to free water, like milky quartz, but with little water loss. Following two annealing experiments at Texas A&M University, I performed four annealing experiments to measure the water content of five synthetic quartz …


Genesis Of Trondhjemite By Low-Pressure Fraction Anatexis Of Hornblende-Gabbro At Alvand Plutonic Complex (Hamedan, Nw Iran): Insights From Geochemical Modelling., Federico Lucci, Adel Saki, Mirmohammad Miri, Ahmad Rabiee, John C. White Jan 2021

Genesis Of Trondhjemite By Low-Pressure Fraction Anatexis Of Hornblende-Gabbro At Alvand Plutonic Complex (Hamedan, Nw Iran): Insights From Geochemical Modelling., Federico Lucci, Adel Saki, Mirmohammad Miri, Ahmad Rabiee, John C. White

EKU Faculty and Staff Scholarship

Amphibole-dominated dehydration melting of gabbro is the primary process responsible for the genesis of adakites, low-K tonalites, modern trondhjemites, and plagiogranites aswell as Archean tonalite-trondhjemite-granodiorite suites that represent the earliest examples of continental crust. Previous literature has mostly focused on the role of Al-rich amphibole during anatexis of a mafic source and many of these studies have investigated this process through experimental melting runs. However, due to experimental boundary conditions, little is known about partial melting of amphibole-bearing mafic rock at temperatures < 800°C for upper crustal conditions (pressure < 500 MPa). Classic and forward thermobarometric modelling suggests that in situ trondhjemite leucosomes, hosted by Cheshmeh-Ghasaban mafic metatexites (Alvand Plutonic Complex, Hamedan, NW Iran), represent a rare natural case study of a low-temperature incipient amphibole-dominated anatectic event of a mafic source with a primary assemblage (Pl+Hbl+Cpx+Bt+Opx) typical of a hornblende-bearing gabbroic rock.


Peralkaline Silicic Extrusive Rocks: Magma Genesis, Evolution, Plumbing Systems, And Eruption., Ray Macdonald, John C. White, Harvey E. Belkin Jan 2021

Peralkaline Silicic Extrusive Rocks: Magma Genesis, Evolution, Plumbing Systems, And Eruption., Ray Macdonald, John C. White, Harvey E. Belkin

EKU Faculty and Staff Scholarship

Peralkaline silicic extrusive rocks are an important component of the volcanological record. Here we review several aspects of their formation and evolution, including the tectonic settings in which they occur, their main petrological and geochemical features, the magmatic lineages along which they evolve, and the parameters (T, P, fO2, melt water contents) that control the lineages. Particular attention is paid to the composition of the extraordinary melts formed at the lowest temperatures. Various lines of evidence are presented to explain the silica-gaps in some lineages. The partial melting of continental crust and the role of crustal contamination …


Petrogenesis And Tectonic Implications Of Cordierite-Orthoamphibole Gneisses (Cog) In The Nw Wyoming Province, Brianna K. Crenshaw Ms Jan 2021

Petrogenesis And Tectonic Implications Of Cordierite-Orthoamphibole Gneisses (Cog) In The Nw Wyoming Province, Brianna K. Crenshaw Ms

Graduate Student Theses, Dissertations, & Professional Papers

Studying cordierite orthoamphibole gneisses (COG) from five different mountain ranges across the Montana Metasedimentary Terrane (MMT) of the Wyoming Province offers a unique opportunity to elucidate the enigmatic origins and petrogenesis of the lithology in addition to gaining a further understanding of Precambrian crustal assembly processes. Geochemical analyses suggest that COG originates from a basalt that underwent metasomatic alteration, likely via seawater, prior to metamorphism. Moreover, COG is considered to represent oceanic crust that was part of the epicontinental sea adjacent to the Wyoming Province before collision with the Medicine Hat Block. Field observations of associated lithologies such as marbles, …


Advancement Of Full-Vector Variable-Temperature Magnetometry For Rock-Magnetic And Paleointensity Applications, Leonid Surovitskii Jan 2021

Advancement Of Full-Vector Variable-Temperature Magnetometry For Rock-Magnetic And Paleointensity Applications, Leonid Surovitskii

Dissertations, Master's Theses and Master's Reports

Data on the variation of the direction and strength of Earth’s ancient magnetic field (absolute paleointensity) provide crucial information into the mechanisms of the geodynamo and the Earth’s thermal history. However, the use of conventional methods and instrumentation for absolute paleointensity determination has been hampered by physicochemical alteration of the samples caused by multiple high-temperature cycles and long experiment durations. The reliability and efficiency of the measurement process can be improved by the measurement of the full remanent magnetization vector simultaneously with the temperature cycling of a sample. Such as approach can also substantially expand the scope of materials available …


Quantifying Bedrock Recharge In Two Paired Mountainous Watersheds, Kimberly Bolhuis Jan 2021

Quantifying Bedrock Recharge In Two Paired Mountainous Watersheds, Kimberly Bolhuis

Graduate Student Theses, Dissertations, & Professional Papers

This study focuses on 1) estimating the magnitude of bedrock recharge and 2) mean transit time as a function of bedrock permeability in two paired catchments underlain by different lithology. Networks of bedrock wells and stream gauges were installed in two adjacent catchments of approximately the same size in west central Montana. Fracture network properties for both lithologies were characterized from borehole core logging and scan lines on exposed outcrop. Recharge was evaluated using the Water Table Fluctuation (WTF) method on bedrock well hydrographs installed in both catchments. Stable water isotope samples, collected approximately monthly, from precipitation and stream water …