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Full-Text Articles in Physical Sciences and Mathematics

Detrital Zircon (U-Th)/He Thermochronology In The Greater Caucasus: Implications For Thermal And Tectonic History Along-Strike, Kate Gutterman Nov 2020

Detrital Zircon (U-Th)/He Thermochronology In The Greater Caucasus: Implications For Thermal And Tectonic History Along-Strike, Kate Gutterman

LSU Master's Theses

Located along the northernmost boundary of the Arabia-Eurasia collision zone, the Greater Caucasus are a young, actively deforming mountain range striking WNW-ESE between the Black and Caspian Seas. Previous thermochronometric studies predominantly focused on the western portion of the range partially constrain the thermal and tectonic history of the Greater Caucasus. However, due to the complex nature of the tectonics in the region, multiple competing tectonic models have been suggested to explain the exact timing of collision and onset of rapid uplift. Furthermore, the Greater Caucasus exhibit competing along-strike gradients in modern shortening rates, mean annual precipitation, structural architecture and …


U/Pb Zircon Ages Of Felsic Veins In The Sawtooth Metamorphic Complex, Idaho, U.S.A: Implications For Magmatism And Vein Source, Kyle Tollefson Nov 2020

U/Pb Zircon Ages Of Felsic Veins In The Sawtooth Metamorphic Complex, Idaho, U.S.A: Implications For Magmatism And Vein Source, Kyle Tollefson

LSU Master's Theses

Veins associated with igneous activity provide numerous insights into the geologic history of an area. The Sawtooth Metamorphic Complex (SMC) in Idaho is a roof pendent of highgrade rocks cross-cut by numerous felsic veins of unknown age and source. Obtaining U/Pb zircon geochronology of these veins can facilitate understanding the ages of magmatism in the region, their source, when nearby batholiths were juxtaposed to the SMC, and provide additional insights into the geologic evolution of the area. Each potential source of these veins has a distinct age: the Sawtooth batholith (ca. 47 Ma), the Idaho batholith (98-53 Ma), an anatectic …


Seasonal Infilling And Sedimentary Characteristics In Sandy Versus Muddy Coastal Borrow Areas On The Louisiana Continental Shelf, Usa, Matthew Barley Aug 2020

Seasonal Infilling And Sedimentary Characteristics In Sandy Versus Muddy Coastal Borrow Areas On The Louisiana Continental Shelf, Usa, Matthew Barley

LSU Master's Theses

Offshore sand deposits on the Louisiana Continental Shelf, such as inner shelf shoals and buried paleo-river channels, can be excavated to restore beaches and barrier islands that are rapidly deteriorating due to subsidence, sea-level rise and deficits in coastal sediment supply. Presented here is grain size, x-radiograph, and Beryllium-7 (7Be) derived sedimentation rates from multicores (~ 50 cm depth) retrieved from borrow areas (BAs) in contrasting depositional settings, all of which have implications for management of water quality, seafloor sedimentology, and biogeochemistry in proximal areas. Multicores were retrieved in fall 2018 at Caminada BA — a sandy energetic …


Response Of Transient Base Level Signals To Erodibility Contrasts In Bedrock Streams, Joshua A. Wolpert Jul 2020

Response Of Transient Base Level Signals To Erodibility Contrasts In Bedrock Streams, Joshua A. Wolpert

LSU Master's Theses

It has long been recognized that bedrock streams gradually adjust their slopes towards topographic steady state, an equilibrium state between rock uplift rate and erosion rate. Tectonic geomorphology studies often analyze stream profiles for clues of this adjustment, which can initiate from changes in tectonic and climatic forcings. The stream power incision model, the most widely utilized framework with which to interpret bedrock stream profiles, predicts that streams perturbed from topographic steady state by changes in bedrock erodibility or uplift rate adjust their slopes to return to topographic steady state through upstream propagating waves of incision, or knickpoints. Under the …


The Long-Term Outlook Of The Mississippi-Atchafalaya Bifurcation: A Convergence Of Engineering, Economics, And Deltaic Evolution, Thomas Mitchell Andrus Apr 2020

The Long-Term Outlook Of The Mississippi-Atchafalaya Bifurcation: A Convergence Of Engineering, Economics, And Deltaic Evolution, Thomas Mitchell Andrus

LSU Doctoral Dissertations

The most recent and currently active delta lobe of the Mississippi River (MR) is the Atchafalaya-Wax Lake lobe, which was initiated approximately 400 years ago as a result of MR stream capture by the Atchafalaya River (AR). This capture process accelerated in the early to mid-1900s but further progress was prevented by construction and operation of the Old River Control Structure (ORCS) Complex. Many recent studies indicate that MR system below the ORCS is on a retreating geologic trajectory due to contributing factors such as sea level rise, subsidence, faulting, and declining hydraulic stream power. Diversions along the Lower MR …


Vegetation Prior To And During Onset Of East Antarctic Glaciation: High Resolution Palynological Insights From Sabrina Coast, East Antarctica, Meghan L. Duffy Mar 2020

Vegetation Prior To And During Onset Of East Antarctic Glaciation: High Resolution Palynological Insights From Sabrina Coast, East Antarctica, Meghan L. Duffy

LSU Master's Theses

The Aurora Subglacial Basin (ASB) contains an estimated 3.5 m of global sea-level equivalent ice volume and is primarily drained by the Totten Glacier system, which terminates at the Sabrina Coast, East Antarctica. Thinning and retreating of the Totten Glacier indicate that this region is highly susceptible to oceanographic and atmospheric warming. The paleoclimate reconstruction of these changes, conducted in the context of this MS thesis, will improve understanding of East Antarctic Ice Sheet (EAIS) dynamics in this sensitive system. A recent study used seismic and sediment core data to document a dynamic early evolution of the EAIS in the …


Constraining Prograde Metamorphic Paths In Archean High-Grade Garnet-Bearing Lithologies From The Eastern Beartooth Mountains, Montana, Usa, Larry Fisher Cliff-Tuttle Jr Mar 2020

Constraining Prograde Metamorphic Paths In Archean High-Grade Garnet-Bearing Lithologies From The Eastern Beartooth Mountains, Montana, Usa, Larry Fisher Cliff-Tuttle Jr

LSU Master's Theses

Prograde metamorphic pressures and temperatures of Archean high-grade garnet-bearing lithologies from the eastern Beartooth Mountains of Montana provide an important constraint on the tectonometamorphic history of this terrane and the early Earth in general. A particularly useful means to approximate prograde metamorphic conditions is examining entrapment conditions of garnet mineral inclusions during garnet growth. Lithologies of the eastern Beartooth Mountains are well-suited to this approach because of the presence of abundant mineral inclusions within garnet porphyroblasts. Consequently, prograde metamorphic pressures and temperatures in the Beartooth Mountains, conditions that have only been broadly constrained previously, can be more accurately determined and …