The sinking of lithosphere at subduction zones couples Earth’s exterior with its interior, spawns continental crust and powers a tectonic regime that is unique to our planet. In spite of its importance, it is unclear how subduction is initiated. Two general mechanisms are recognized: induced and spontaneous nucleation of subduction zones. Induced nucleation (INSZ) responds to continuing plate c...

The Gulf of Mexico opened as a Late Triassic-Mid Jurassic continental rift that was first largely covered by the Mid-Jurassic Louann Salt and later split apart triangular-shaped oceanic crust. in hampers imaging interpretation underlying pre-salt crustal geometries, which are fundamental for assessing early kinematic evolution margin. To better define these deep geometries their lateral variati...

Ultra-high-pressure (UHP) eclogites and ultramafites associated fluid inclusions from the Western Gneiss Region, Norwegian Caledonides, have been analysed for F, Cl, Br I using electron-probe micro-analysis, time-of-flight secondary ion mass spectrometry neutron-irradiated noble gas spectrometry. Textures of multi-phase in cores silicate grains indicate formation during growth host crystal at U...

kalateh ahani is located 27 km southeast of gonabad within the khorasan razavi province. the area is part of lut block. sub-volcanic monzonitic rocks intruded regional metamorphosed shemshak formation (jurassic age). magnetic susceptibility of less altered monzonitic rocks is 0.6%., as, pb and zn > 1%, au up to 150 ppb and sn = 133 ppm. the sn content of vein in the northern part of kalateh aha...

Carboniferous magmatism in southwestern Iberia was continuously active for more than 60 m.y. during the development of Appalachian-Variscan belt North America, Africa and Western-Central Europe. This collisional orogen that records closure Rheic Ocean is essential to understanding late Paleozoic amalgamation Pangea supercontinent. However, oblique convergence between Laurussia Gondwana lasted f...

The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Icelan...

Title of Document: TRACING CONTINENTALWEATHERING USING LITHIUM AND MAGNESIUM ISOTOPES: INSIGHTS FROM THE CHEMICAL WEATHERING OF COLUMBIA RIVER BASALTS AND MASS BALANCE MODELING Xiao-Ming Liu, Ph.D., 2013 Directed By: Professors Roberta L. Rudnick & William F. McDonough, Department of Geology Chemical weathering is an important mechanism that changes the mass and composition of the continental c...

Valentine and Moores [Valentine JW, Moores EM (1970) Nature 228:657-659] hypothesized that plate tectonics regulates global biodiversity by changing the geographic arrangement of continental crust, but the data required to fully test the hypothesis were not available. Here, we use a global database of marine animal fossil occurrences and a paleogeographic reconstruction model to test the hypoth...