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 194 for “"Basalts"”.
-
Global isotopic signatures of oceanic island basalts
Sr, Nd and Pb isotopic analyses of 477 samples representing 30 islands or island groups, 3 seamounts or seamount chains, 2 oceanic ridges and 1 oceanic plateau [for a total of 36 geographic features] are compiled to form a comprehensive oceanic island basalt [OIB] data set. These samples are …
-
Mantle Heterogeneity Through Mid-Ocean Ridge Basalts
… mantle is often examined through mid-ocean ridge basalts (MORB), which contest the prevalent assumption of a well-mixed convecting mantle. This dissertation delves into studying mantle heterogeneity from a local to regional scale. Initially, petrological models were utilized to scrutinize the …
-
The hydrothermal alteration of oceanic basalts by seawater
… and chemistry of hydrothermally altered pillow basalts dredged from the Mid-Atlantic Ridge, and belonging to the greenschist facies, have been studied in order to determine the mineralogical changes that result from hyrdrothennal alteration, and to assess the chemical fluxes that result from …
-
Geochemistry and mineralogy of selected Atlantic Ocean basalts
… major and trace element variations in selected basalts from the FAMOUS area, in conjunction with a detailed study of the chemistry of phenocryst minerals and associated melt inclusions are used to place constraints on the genetic relationships between the various lava types. The distribution of …
-
Global isotopic signatures of oceanic island basalts / by
Sr, Nd and Pb isotopic analyses of 477 samples representing 30 islands or island groups, 3 seamounts or seamount chains, 2 oceanic ridges and 1 oceanic plateau [for a total of 36 geographic features] are compiled to form a comprehensive oceanic island basalt [OIB] data set. These samples are …
-
The hydrothermal alteration of oceanic basalts by seawater.
Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences.
-
Element fractionation in the petrogenesis of ocean island basalts
… element ratios characteristic of 'himu' basalts (Weaver 1991). In contrast, the 206pb/204pb ratios of the La Palma basanites (19.6±0.05) are lower than the isotopically defined'high p' basalts (Zindler & Hart 1986) which suggests that the La Palma source is geochemically similar, but …
-
The Origin and Petrogenesis of the Ethiopian Flood Basalts
… the course of continental separation. The flood basalts of the Ethiopian Plateau constitute the larger part of this province and are associated with melting in the head of the Afar Plume. High-Ti picrites from the eastern part of the NW Plateau are among the earliest uncontaminated outpourings of …
-
A paleomagnetic study of early tertiary basalts in West Texas
The natural remanent magnetization of thirty-one early Tertiary lava flows from West Texas was measured. Stratigraphic controls and some potassium-argon dates were used to determine the relative age of the flows. Stability of magnetization was established by ac demagnetization. Because of large …
-
High pressure phase equilibrium studies of near-primary planetary basalts
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
-
Stratigraphy and petrogenesis of the Parana continental flood basalts, southern Brazil
… Magmatism is dominated by tholeiitic basalts (> 90 %), with minor rhyolites as a late-stage feature along the continental margin. The basaltic magmas show a wide diversity in trace element and isotope composition, and a revised scheme of distinct magma types is proposed, based on new …
-
Late Cenozoic basalts from the Basin-Range province, western United States
… United States, are predominantly alkali-olivine basalts. Associated with these lavas are lesser volumes of basaltic andesite which appear to be differentiates from the more primitive alkali basalts. Late Cenozoic basalts from adjacent regions (Columbia River Plateau, Snake River Plain, …
-
Self-Reversal of Remanent Magnetisation of Basalts - Origin, Mechanisms and Consequences
… present work was placed on the investigation of basalts exhibiting partial or complete self-reversal of natural remanent magnetisation (NRM). This phenomenon is not an exotic rarity but a widespread characteristic of many basaltic rocks. However it remains usually unnoticed by routine …
-
The geochemistry of the Gough Island basalts and their mantle source region
Ten Gough Island primary magma compositions were calculated for use in constrained forward modelling. The primary magma compositions were calculated by the addition of 14-28% clinopyroxene and equilibrium olivine, in equal proportions, back into the primitive lava compositions in 1 % increments …
-
Experimental constraints on the generation and evolution of mid-ocean ridge basalts
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
-
Petrology and geochemistry of intra-back arc basalts from the Argentine Andes
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994.
-
Analysis of Chemical Elements in Basalts using Mislabeled Data, a Machine Learning Approach
<p>Scientists use basalt chemistry to discriminate among different tectonic settings. There are well-known chemical elements used to classify tectonic settings. An exploration of new features is done using Logistic Regression and Random Forest to discover any new elements of interest. The models …
-
Mantle convection, melt migration and the generation of basalts at mid-ocean ridges
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and Woods Hole Oceanographic Institute, 1991.
-
Crustal contamination recorded by zoned plagioclase in primitive Karoo flood basalts, Luenha River, Mozambique
Jurakautinen (182 Ma) Karoon laakiobasalttiprovinssi on geokemialtaan erittäin heterogeeninen. Heterogeenisyyden on ajateltu olevan peräisin kahdesta toisistaan eriävästä vaippalähteestä. Mozambikin koillisosassa sijaitseva Luenha joen paljastuma sisältää primitiivistä pikriittejä, …
-
Diverse Primitive Basalts from an Extensional Back-arc Setting: Fort Rock Volcanic Field, Oregon
… landforms contain a diverse array of primitive basalts, with an Mg# (xMgO / (xMgO + xFeO) * 100) > 60 (molar %), deducing information of mantle source regions and melting processes through geochemical analyses of major and trace elements to achieve a greater understanding of the complex tectonic …
Page 1 of 10