Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 106 for “"Continental Crust"”.
-
The evolution of the Archaean continental crust of Northern Zimbabwe
… Archaean conglomerates indicate the presence of continental crust in Northern Zimbabwe prior to the"" 2.7 to "" 2.6Ga "event" which terminated with the stabilisation of the Zimbabwe Craton. The "Kober Technique" (Kober, 1986, 1987) of direct thermal ionisation of zircons has been set up in order …
-
Archean continental crust formation and the rise of atmospheric oxygen
… planetary surface: the establishment of the continental crust and the progressive rise of an oxygenated atmosphere. The volume of continental crust on the earliest Earth is a critical parameter for constraining the chemical evolution of major terrestrial reservoirs, and radiogenic isotope …
-
Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems
To understand the growth of continental crust, the balance between juvenile mantle derived extraction, infracrustal reworking and crustal recycling, needs to be estimated. Since the beginning of the century, the use of coupled in situ zircon U–Pb, Lu–Hf and O isotope analyses as a tool to address …
-
Mineral Equilibrium Constraints on the Feasibility of Diffusively-Fluxed Melting in the Continental Crust
… alternative mechanism for granite generation and crustal differentiation. Water-fluxed melting is recognised by voluminous melt production at relatively low temperature, where hydrous minerals are stable and anhydrous minerals are preferentially consumed during melting. Mineral equilibrium …
-
Brittle-viscous deformation cycles at the base of the seismogenic zone in the continental crust
… fault zone active at the base of the seismogenic crust. Object of analysis are samples from the sinistral strike-slip fault zone BFZ045 from Olkiluoto (SW Finland), located at the site of a deep geological repository for nuclear waste. Combined microstructural analysis, electron backscatter …
-
Impact of accessory minerals on the distribution of trace elements in the continental crust: an integrated petrologic and phase equilibria modeling study of migmatites, The
Partial melting of the lower continental crust and subsequent melt emplacement at higher structural levels is an important crustal differential process that is predicted to produce an enriched granitic upper crust and depleted, more mafic lower crust. However, the common occurrence of accessory …
-
INTO THE STRUCTURE OF THE PERMIAN DEEP CONTINENTAL CRUST: A MULTISCALE APPROACH TO RECONSTRUCT MIGMATIZATION IN THE VALPELLINE SERIES (DENT BLANCHE TECTONIC SYSTEM, WESTERN ITALIAN ALPS)
… such as those associated with collisional crustal thickening during orogenic events and post-collisional or back-arc lithospheric thinning. Studying these rocks provides an exceptional opportunity to observe the deep portions of the continental lithosphere and infer insights into the …
-
Evaluating mantle and crustal processes using isotope geochemistry
… distinct reservoirs such as the Earth's crust, mantle and core. In this dissertation the strategy has been to work on a broad range of topics to evaluate crustal and mantle processes. This study presents Re-Os systematics to constrain the composition, formation and age of the lower …
-
Platinum-group elements geochemistry of felsic rocks
… constrain the PGE and Re abundances in the upper continental crust. The results lead to a revised PGE composition of the upper continental crust, especially for Ru and Rh. These results are of importance for understanding PGE abundances in felsic igneous rocks that form by direct melting or …
-
Platinum-group elements geochemistry of felsic rocks
… constrain the PGE and Re abundances in the upper continental crust. The results lead to a revised PGE composition of the upper continental crust, especially for Ru and Rh. These results are of importance for understanding PGE abundances in felsic igneous rocks that form by direct melting or …
-
Crustal structure of rifted and convergent margins : the U.S. East Coast and Aleutian margins
… most important processes that create and modify continental crust occur at continental margins, but recently has the scientific community acquired the necessary intrumentation to image crustal structure across margins in detail. In this thesis we investigate the crustal structure across the U.S. …
-
Gravity Modeling, Seismic Stratigraphy, and Thermal Maturity Modeling of Hydrocarbons of the Permian Foreland Basin, USA, and the Sergipe-Alagoas Rifted-Passive Margin, Brazil
… better understand the changing tectonic setting, crustal structure, and sedimentary basin fill influenced the hydrocarbon potential of these two basins. In Chapter 2, I created 2D and 3D gravity models to better define the tectonic origin of the Abilene gravity minimum (AGM) underlying the …
-
Characterizing the southeast Caribbean-South American plate boundary at 64°W
The crustal and lithospheric structure of the northern South America plate boundary with the southeast Caribbean has been the focus of many studies. In this region, westward subduction of (Atlantic) oceanic South America transitions to east-west transform between continental South America and the …
-
Modeling target rock composition of two impact events
… a rare opportunity to investigate early Earth's crustal evolution. Spherule layers, formed through condensation of vaporized target rock and bolide material during meteorite impacts, represent a unique window into this time. This study models target rock compositions of two …
-
Deciphering the Tectonics of the Caucasus from Post-Collisional Volcanism
… the Eurasian plate is a well-studied region of continental collision. The Caucasus mountains lie at the centre of the Alpine-Himalayan orogenic belt, and differs from their better studied neighbours by the presence of intense, largely mantle derived post-collisional magmatism. Volcanism began …
-
Processes of felsic melt migration through the mid-crust : evidence from field relations in the central zone of the Damara Belt, Namibia
… mass, and the chemical differentiation of the continental crust. Whereas the processes of melt segregation and emplacement are relatively well understood, melt ascent mechanisms are more speculative. Specific outstanding questions include the structure of melt conduits, the driving forces of …
-
Mineral equilibria constraints on open-system melting and consequences of melt loss in metabasic rocks
… the process of internal differentiation in the continental crust. The recent development of thermodynamic activity-composition (a-x) relations for high T mineral and melt phases allows the processes of melt generation and segregation to be quantified using high-resolution mineral equilibria …
-
Evaluating mantle and crustal processes using isotope geochemistry
… distinct reservoirs such as the Earth's crust, mantle and core. In this dissertation the strategy has been to work on a broad range of topics to evaluate crustal and mantle processes. This study presents Re-Os systematics to constrain the composition, formation and age of the lower …
-
Chemical, isotopic, and temporal variations during crustal differentiation : insights from the Dariv Igneous Complex, Western Mongolia
… in producing a compositionally stratified continental crust characterized by a silicic upper crust and a mafic lower crust. This thesis explores outstanding questions associated with fractional crystallization through detailed field, petrological, and geochemical studies of the Dariv …
-
Temperature-dependent thermal transport properties of major Archean rock types and implications for the thermal evolution of Archean terranes
… to formation of dome-and-keel terranes. Early continental crust was comprised of rock associations such granite-greenstone (GG) belts and intrusions of high heat-producing tonalite-trondhjemite-granodiorite (TTG), and the burial of TTG rocks below GG rocks is believed to have triggered …
Page 1 of 6