Geology Commons^™

Diatoms As Recorders Of Sea Ice In The Bering And Chukchi Seas: Proxy Development And Application, Beth A. Caisse

Open Access Dissertations

The recent, rapid decline in Arctic summer sea ice extent has prompted questions as to the rates and magnitude of previous sea ice decline and the affect of this physical change on icerelated ecosystems. However, satellite data of sea ice only extends back to 1978, and mapped observations of sea ice prior to the 1970s are sparse at best. Inventories of boreal ecosystems are likewise hampered by a paucity of investigations spanning more than the past few decades. Paleoclimate records of sea ice and related primary productivity are thus integral to understanding how sea ice responds to a changing climate. …

How Does Hydropeaking Alter The Hydrology Of A River Reach? A Combined Water Budget, Modeling, And Field Observation Study. Deerfield River, Massachusetts, Brian C. Yellen

Masters Theses 1911 - February 2014

Hydroelectric releases on the Deerfield River in northwestern Massachusetts affect surface water-groundwater interactions there by daily reversing the head gradient between river and groundwater. Artificially elevated stage drives river water into the riparian aquifer. Water budget analysis indicates that roughly 10% of this bank-stored water is permanently lost from the river system in a 19.5 km reach, likely as a result of transpiration by bank vegetation.

Field observations as well as two-dimensional modeling results show that water losses are not uniform throughout the study reach. Riparian aquifer transmissivity in river sub-reaches largely determines the magnitude of surface water-groundwater exchange as …

Evolution Of Volatile Content Of The Parent Magma Of The 1875 Eruption Of Askja Volcano, Iceland, Heather A. Clark

Masters Theses 1911 - February 2014

The bulk of the eruption of Askja in north central Iceland on March 28-29 1875 consisted of a plinian eruption that lasted 6-7 hours, produced 0.2 km³ of ash and rhyolitic pumice, and created a surge and partially welded ash/pumice fall deposit that crops out on the shore of the modern caldera lake (Sparks et al. 1981). We evaluate the volatile budget of the magma during the eruption and focus on water concentration in glass fragments and shards, glass adjacent to crystals, and melt inclusions (MIs). Sparks et al. (1981) estimated the gas exit velocity at the vent was …

A Paleoclimate Modeling Experiment To Calculate The Soil Carbon Respiration Flux For The Paleocene-Eocene Thermal Maximum, David M. Tracy

Masters Theses 1911 - February 2014

The Paleocene-Eocene Thermal Maximum (PETM) (55 million years ago) stands as the largest in a series of extreme warming (hyperthermal) climatic events, which are analogous to the modern day increase in greenhouse gas concentrations. Orbitally triggered (Lourens et al., 2005, Galeotti et al., 2010), the PETM is marked by a large (-3‰) carbon isotope excursion (CIE). Hypothesized to be methane driven, Zeebe et al., (2009) noted that a methane based release would only account for 3.5°C of warming. An isotopically heavier carbon, such as that of soil and C3 plants, has the potential to account for the …

Characterization Of Damage Zones Associated With Laboratory Produced Natural Hydraulic Fractures, Erin Bradley

Masters Theses 1911 - February 2014

Both joint sets and fault-related fractures serve as important conduits for fluid flow. In the former case, they can strongly influence both permeability and permeability anisotropy, with implications for production of water, hydrocarbons and contaminant transport. The latter can affect issues of fluid flow, such as whether a given fault seals or leaks, and fault mechanics. These fractures are commonly interpreted as Natural Hydraulic Fractures (NHFs), i.e., mode 1 fractures produced when pore fluid pressure exceeds the tensile strength of the rock. Various mathematical models have been a rich source of hypotheses to explain the formation and propagation of NHFs, …

Fractures Of The Dammam Dome Carbonate Outcrops: Their Characterization, Development, And Implications For Subsurface Reservoirs, Mohammed M. Al-Fahmi

Masters Theses 1911 - February 2014

The exposed Tertiary carbonates of the Dammam Dome present an opportunity to study fractures in outcrops within the oil-producing region of Eastern Saudi Arabia. The study focuses on: 1) the characterization of fractures, 2) interpretation of their fracturing mechanism, and 3) the implications for the deep carbonate reservoirs of the Dammam Dome. The characterization of the outcrop fractures is integrated with structural analysis of the near-surface horizons mapped from reflection seismic and well data. Fractures are observed within all exposed carbonate units, but predominantly within the widely exposed Middle Rus unit. The fractures are opening-mode, bed-bound joints that form orthogonal …