Physical Sciences and Mathematics Commons^™

Climatic Controls On The Porewater Chemistry Of Mid-Continental Wetlands, Zeno Francis Levy

Dissertations - ALL

Wetlands develop where climate and physiography conspire to maintain saturated soils at the land surface, support diverse plant and animal communities, and serve as globally important sinks for atmospheric carbon. The chemistry of wetland porewaters impacts near-surface biological communities and subsurface biogeochemical processes that influence carbon cycling in the environment. Wetland porewater chemistry is a dynamic byproduct of complex hydrogeological processes that cause meteoric waters to enter groundwater systems (recharge) or groundwater to flow to the land surface (discharge). Changes in climate can alter subsurface hydraulic gradients that determine the recharge and discharge functions of wetlands, which in turn control …

Isotopic Characterization Of Bedrock, Sediments, And Minerals As Provenance Tools: Examples From An Inselberg In The Mojave Desert Of Se California, Mariana Belen Bonich-Wissink

Dissertations - ALL

Our understanding of the evolution of the Earth’s surface is driven by our knowledge and comprehension of the processes which shape the landscape. The source, formation, and transport pathways of sediment are critical components to understanding crustal processes and changes and are often grouped under the broad scope of provenance analysis. Much of what we know of how sediments evolve and shape our landscape stems from provenance analysis, which tries to trace the pathway of source to sink. However, complexities arise when the final composition or signature of the detrital material is altered, which results in provenance signature deviations from …

Effects Of Stream Restoration And Storm Events On Stream-Groundwater Interactions, Margaret Zimmer

Earth & Environmental Sciences - Theses

The body of literature on stream-groundwater interactions is rapidly growing, but little is known about the effects of either storm events or in-stream restoration on the interactions between surface water and groundwater. The chapters of this thesis explore two of these questions at the same locality of interest: (1) subsurface geochemical dynamics across a riffle bedform in an unrestored stream during a storm event and subsurface geochemical, and (2) hyporheic exchange dynamics at baseflow conditions pre- and one year post- stream restoration.

The study site was a 30 m stretch of stream that underwent stream restoration through installation of a …

Geochemical And 40ar/39ar Constraints On The Evolution Of Volcanism In The Woodlark Rift, Papua New Guinea, Joseph Paul Catalano

Earth & Environmental Sciences - Theses

The tectonic mechanisms producing Pliocene to active volcanism in eastern Papua New Guinea (PNG) have been debated for decades . In order to assess mechanisms that produce volcanism in the Woodlark Rift, we evaluate the evolution of volcanism in eastern PNG using 40Ar/39Ar thermochronology and whole rock geochemistry.

Active volcanism in southeastern Papua New Guinea occurs on the Papuan Peninsula (Mt. Lamington, Mt. Victory and Waiwa), in the Woodlark Rift (Dobu Island, SE Goodenough Island, and Western Fergusson Island), and in the Woodlark Basin . In the Woodlark Basin, seafloor spreading is active and decompression melting of the upper mantle …

Investigating The Utility Of Detrital Mineral Microchemistry And Radiogenic Isotope Compositions As Provenance Discriminators, Jack Hietpas

Earth & Environmental Sciences - Dissertations

The provenance of clastic sediments remains one of the key tools for understanding the complex dynamic history of the Earth. Detritus shed from ancient orogens may be the only evidence available for determining the timing, evolution, paleogeography, and existence of tectonic events active over the 4.56 Ga of Earth history. The focus of this dissertation research is to assess the strengths and limitations of existing, as well as novel, tools for determining the provenance of siliciclastic sediments.

The utility of detrital monazite crystallization ages was investigated as a provenance indicator in both modern and ancient sedimentary systems. The results from …