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Full-Text Articles in Geology

Kinematic Vorticity And Porphyroclast Rotation In Mylonites Of The Norumbega Fault System: Implications For Paleoviscometry, Hendrik Lenferink Dec 2023

Kinematic Vorticity And Porphyroclast Rotation In Mylonites Of The Norumbega Fault System: Implications For Paleoviscometry, Hendrik Lenferink

Honors College

Crystallographic and shape preferred orientation (SPO) fabrics that develop in mylonitic shear zones can preserve the mean kinematic vorticity number (Wm) of bulk flow. Microstructural methods exploiting dynamically recrystallized quartz and porphyroclast SPO fabrics typically yield conflicting values of Wm. The Sandhill Corner Mylonite Zone of the Norumbega Fault System, Maine, USA, serves as a case study for investigating this discrepancy; Wm estimates range from 0.90 to 1.00 employing the former method (Method 1) and from 0.3 to 0.6 employing the latter method (Method 2). Using a numerical model, I show how a low-viscosity layer (LVL) surrounding clasts affects their …


Rift-Induced Disruption Of Cratonic Keels Drives Kimberlite Volcanism, Thomas M. Gernon, Stephen M. Jones, Sascha Brune, Thea K. Hincks, Martin Palmer, John C. Schumacher, Rebecca M. Primiceri, Matthew Field, William L. Griffin, Suzanne Y. O'Reilly, Derek Keir, Christopher J. Spencer, Andrew S. Merdith, Anne Glerum Jul 2023

Rift-Induced Disruption Of Cratonic Keels Drives Kimberlite Volcanism, Thomas M. Gernon, Stephen M. Jones, Sascha Brune, Thea K. Hincks, Martin Palmer, John C. Schumacher, Rebecca M. Primiceri, Matthew Field, William L. Griffin, Suzanne Y. O'Reilly, Derek Keir, Christopher J. Spencer, Andrew S. Merdith, Anne Glerum

Geology Faculty Publications and Presentations

Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past1,2,3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity4. Whether their mobilization is driven by mantle plumes5 or by mechanical weakening of cratonic lithosphere4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical …


Impact Of Lithological Variation And Topology On The Connectivity And Intensity Of Fracture Networks In Carbonates, Fahad Qassim May 2023

Impact Of Lithological Variation And Topology On The Connectivity And Intensity Of Fracture Networks In Carbonates, Fahad Qassim

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Assessing fracture network connectivity in reservoirs remains a challenging task because of the complex nature of fracture networks at various length scales, which significantly impacts fluid flow behavior. Outcrop studies are essential for understanding subsurface fracture networks because intersecting fracture sheets' length, orientation, height distribution, and, therefore, network connectivity and intensity are difficult to measure from wellbores and are typically below seismic resolution. Nevertheless, fracture network connectivity is a crucial parameter and a critical factor in understanding, evaluating, and predicting fluid flow behavior in hydrocarbon reservoirs, aquifers, hazardous waste and CO2 storage systems, and geothermal energy exploitation. Moreover, fracture …