Doctor of Philosophy, Miami University, 2022, Geology and Environmental Earth Science

Volcanic rocks record the complex nature of magmatic systems. The mineralogical, petrological, and geochemical heterogeneity that exists within an eruptive unit at a single volcano is challenging to reconcile with a static magma chamber model. Current understanding, therefore, supports the presence of complex, dynamic trans crustal magmatic systems (TCMSs) that consist of interconnected regions of magma storage where liquid-poor, crystal-rich mushes exist and variably interact. This dissertation presents an investigation into the magmatic and crustal components of TCMSs through a study of andesitic-dacitic lavas, hornblendite cumulates, and crustal xenoliths from the Plio- Pleistocene Pampa Aullagas (PA) and Quillacas (QL) monogenetic centers on the Bolivian Altiplano, Central Andes. In Chapter 1, amphibole's role in continental arc petrogenesis is investigated through a textural and geochemical study of hornblendite cumulates entrained within QL lavas. Granular, idiomorphic textures, the absence of relict clinopyroxene, and mesocumulate textures defined by intercumulus feldspar, apatite, and Fe-Ti oxides all support the formation of the hornblendites as cumulates in the lower arc crust. Reaction rims associated with cumulus amphiboles record cumulate mobilization, ascent, and eruption through TCMSs over relatively short timescales (<30 days). In Chapter 2, the crustal components of the QL and PA TCMSs are investigated through a lithologically diverse crustal xenolith suite which provides insights into the tectonomagmatic history of the Central Andean continental crust. From U-Pb zircon geochronology, evidence for ~3 Ga of tectono-magmatic events is recorded within the Central Andean continental basement. Age population peaks correlate with global supercontinent cycles, including the establishment of Nuna, Rodinia, and Gondwana, and record a long history of terrane accretion and arc magmatism along the western margin of South America. In Chapter 3, the origin of num (open full item for complete abstract)

Committee: Claire McLeod (Advisor); Michael Brudzinski (Committee Member); Jennifer Blue (Committee Member); Alicia Cruz-Uribe (Committee Member); Mark Krekeler (Committee Member) Subjects: Geochemistry; Geology; Mineralogy; Petrology

MS, University of Cincinnati, 2019, Arts and Sciences: Geology

The Oquirrh basin is a Pennsylvanian to early Permian mixed clastic and carbonate basin in northwestern Utah. The basin is the northwesternmost expression of the Ancestral Rocky Mountains (ARM) orogeny, and locally contains up to 9 km of sediment. Depositional facies range from shelf carbonates to deep marine turbidites, debrites, and hybrid flow deposits, with a general deepening from basin initiation to the early Permian; however, the tectonic drivers and sediment source(s) for the basin are poorly constrained. To better understand the subsidence and tectonic history of the Oquirrh basin, tectonic subsidence analysis was performed on 10 published stratigraphic sections across the basin. Two phases of tectonism are interpreted to have occurred on either side of the basin, forming distinct depocenters during the middle Pennsylvanian and early Permian. Pennsylvanian subsidence is interpreted as a flexural response to a crustal load east of the basin coeval with the ARM, whereas Permian subsidence in the western part of the basin may be related to the uplift and unconformity sequence documented in the Antler Overlap basins of northeastern Nevada. Unlike other ARM basins, no basin-bounding fault or highland has been identified. To test links between sediment provenance and tectonism, 26 thin-sections were analyzed from 8 locations in a northwest to southeast transect across the basin. Gazzi-Dickinson point counting was used to determine composition and provenance. Samples fell into three mature compositional categories: quartz arenite, sublitharenite, and quartz wacke indicating cratonic interior and recycled orogenic provenances. Petrographic analysis of middle Pennsylvanian sediments revealed very well sorted, finer-grained sandstones in the southeast and northwest parts of the basin versus moderately well sorted, coarser-grained sandstones in the basin center. Permian sediments have decreasing sorting and increasing variability in grain size toward the southeast. (open full item for complete abstract)

Committee: Daniel Sturmer Ph.D. (Committee Chair); Tandis Bidgoli Ph.D. (Committee Member); Craig Dietsch Ph.D. (Committee Member) Subjects: Geology

Master of Science (MS), Ohio University, 2015, Geological Sciences (Arts and Sciences)

Available U–Pb age data for the Cornubian Batholith of SW England is based almost entirely on monazite and xenotime, and very little zircon U–Pb age data has been published. As a result, no zircon inheritance data are available for the batholith, by which the nature of the unexposed basement of the Rhenohercynian Zone in SW England might be constrained. Zircon LA-ICPMS data for the Cornubian Batholith provides Concordia ages (Bodmin Moor granite: 316 ± 4 Ma, Carnmenellis granite: 313 ± 3 Ma, Dartmoor granite: ~310 Ma, St. Austell granite: 305 ± 5 Ma, and Land's End granite: 300 ± 5 Ma) that are consistently 20-30 Ma older than previously published emplacement ages for the batholith and unrealistic in terms of geologic relative age relationships. Several of the batholith's granite plutons contain a component of late-Devonian inheritance that may record rift-related, lower crustal melting or arc-related magmatism associated with subduction of the Rheic Ocean. In addition, the older granites likely contain Mesoproterozoic inheritance, although the highly discordant nature of the Mesoproterozoic ages precludes their use in assigning an affinity to the Rhenohercynian basement in SW England. Submitted for publication in Tectonophysics as “Neace, E.R., Nance, R.D., Murphy, J.B., Lancaster, P., Shail, R.K. (2016). Zircon LA-ICPMS geochronology of the Cornubian Batholith, SW England.”

Committee: Richard Nance (Advisor); Craig Grimes (Committee Member); Douglas Green (Committee Member) Subjects: Geological; Geology

Master of Environmental Science, Miami University, 2013, Geology and Environmental Earth Science

The E-W-trending Ulukisla basin (UB) in Turkey occurs between the Central Anatolian Crystalline Complex to the north and the Tauride carbonate platform to the south. It contains 5 km-thick, uppermost Cretaceous to Miocene-Pleistocene strata and Eocene magmatic rocks. The Cretaceous - Eocene sedimentary rocks comprise an upward shallowing sequence of clastics. The Eocene sequence includes marine turbidites and is transitional upwards into Oligocene rocks. The upward transition from Lower Oligocene shallow marine, deltaic deposits to Upper Oligocene-Miocene evaporate and terrestrial deposits indicates a record of a successor basin. The Upper Cretaceous and Lower Paleocene rocks and the Middle Eocene - Middle Miocene units are deformed by north- and south-vergent, upright and overturned folds and thrust, strike-slip faults. The E-W normal faults in the Middle Paleocene and Middle Eocene units represent extensional deformation coeval with slab breakoff and induced mafic magmatism. The Ulukisla depocenter initially developed as a successor basin in the latest Mesozoic-early Cenozoic and then evolved into a terrestrial basin in the late Tertiary.

Committee: Yildirim Dilek (Advisor) Subjects: Geology; Plate Tectonics; Sedimentary Geology

Master of Science (MS), Ohio University, 2008, Geological Sciences (Arts and Sciences)

The petrography and U-Pb probability ages of detrital zircons from four channel sandstones representing all three fluvial styles within the Conemaugh and Monongahela Groups were compared to determine if changes in composition and age of the framework grains and heavy minerals were a function of fluvial style, climate, or provenance. The results show that the petrographic differences between the samples are best explained by variations in grain size and provenance. Assimilation of zircon age probability data for the Late Paleozoic of the Appalachian basin shows the presence of at least two sub-basins present throughout deposition of the Pottsville Group (Early Pennsylvanian) to the Dunkard Group (Early Permian?). The southern boundary of the northern sub-basin, which includes this study area, is near the margin of the Pennsylvanian structural salient, which suggests the boundary was likely influenced by irregularities formed during the rifting of Rodinia.

Committee: Gregory C. Nadon PhD (Advisor); Douglas Green PhD (Committee Member); R. Damian Nance PhD (Committee Member) Subjects: Geology

MS, Kent State University, 2009, College of Arts and Sciences / Department of Earth Sciences

The eastern margin of the Archean Wyoming craton (Black Hills, SD) records a complex history of Precambrian thermotectonism and magmatism associated with convergence, rifting, and supercontinent cycles. U-Pb isotopic spot-analysis by ion-microprobe of zircon, monazite, and xenotime in six rocks from here provides new insights into part of this history. Firstly, quartzite and metapelite xenoliths in the 2560 Ma Little Elk Granite (LEG) record 207Pb/206Pb upper-intercept ages of 2554 ± 15 Ma (2σ, MSWD = 18) and 2552 ± 14 Ma (2σ, MSWD = 3.2), indicating that older, pre-LEG zircon was reconstituted during LEG reheating. Secondly, nine populations of detrital zircon were found within the 2560-2480 Ma Boxelder Creek metaconglomerate, which range in age from 2590 to 3370 Ma and thereby indicate Wyoming cratonic provenance. Thirdly, zircon from the Bogus Jim mafic sill (BJS) has yielded a 207Pb/206Pb upper-intercept age of 2011.8 ± 3.5 Ma (2σ, MSWD = 1.8), which constrains the time of magmatism, represents a maximum age for deposition of the Homestake iron formation and its associated gold deposit, and indicates that the eastern Wyoming craton was actively rifting at this time (probably from the southern Superior craton). Fourthly, magmatic zircon, monazite, and xenotime in the Harney Peak Granite (HPG) have yielded precise 207Pb/206Pb ages of 1716.8 ± 9.3 Ma (2σ, MSWD = 0.95); 1703.2 ± 2.2 Ma (2σ, MSWD = 2.1); and 1695.9 ± 2.9 Ma (2σ, MSWD = 1.8), respectively. Within error, these results appear to indicate that the HPG magmatic event lasted for 9-33 (or 23 +10 -12) Myr.

Committee: Peter S. Dahl PhD (Advisor); Abdul Shakoor PhD (Committee Member); Donna Witter PhD (Committee Member) Subjects: Geochemistry; Geology

MS, Kent State University, 2009, College of Arts and Sciences / Department of Earth Sciences

Th/U-bearing accessory minerals monazite, zircon, and titanite occurring in selected metamorphic and igneous rocks from the northern Black Hills (NBH), South Dakota, were analyzed by standard U-Pb radiometric methods to unravel the Precambrian thermotectonic events that affected the area. Four metapelites from the Crook Mountain borehole contain metamorphic monazites for which EMP spot-analysis yielded total-Pb dates ranging from ~2680-1600 Ma but mostly between ~1790-1650 Ma. Individual spot-dates obtained for the metapelites were grouped according to compositional domains, as revealed by X-ray imagery, whereupon the resultant domain ages resolved into four discrete age clusters of ~1780 ± 3 Ma (32% of the dates), ~1751 ± 3 Ma (44%), ~1718 ± 14 Ma (7%), and ~1650 ± 9 Ma (16%, all dates reported at 95% confidence). These dates correspond to thermotectonic and magmatic events previously recognized at these times in the southern Black Hills, and the timing of Homestake gold mineralization is constrained between ~1740 -1718 Ma. Spot-analysis of zircon grains extracted from a Crook Mountain granite pegmatite yielded 207Pb/206Pb upper- and lower-intercept ages of 1718 ± 22 Ma and 51 ± 17 Ma, which are interpreted as intrusive and uplift ages, respectively. Detrital zircons of magmatic origin from two Black Hills metapelites have also been spot-dated. Five 207Pb/206Pb age populations are recognized at: ~3830 ± 8, ~3365 ± 5, ~3425 ± 7, ~3240 ± 4, and ~2970 ± 11 Ma. These ages indicate zircon provenance from the ~3550-2550 Ma Wyoming craton rather than from the ~2900-2600 Ma Superior craton. Thus, the Black Hills appears to have been part of the Wyoming craton as of 2015-1880 Ma shale deposition.

Committee: Peter Dahl PhD (Advisor); Abdul Shakoor PhD (Committee Member); Daniel Holm PhD (Committee Member) Subjects: Geochemistry; Geology