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 36 for “"eclogite"”.
-
Fluid Release During Eclogite Formation, North Qaidam Terrane, Western China
Ultrahigh-pressure (UHP, depths ≳100 km) eclogite samples from the Dulan area of the North Qaidam Terrane, western China, preserve evidence of fluid release along a prograde pressure-temperature (P-T) path. Eclogite sample D126A, Grt + Omp + Qtz + Zo + Amp + Phe + minor Rt + Hem, contains garnet …
-
Cratonic eclogite xenoliths - formation and evolution of the subcontinental lithospheric mantle
… (cpx)), coesite-, kyaniteand corundum-bearing eclogites. Metasomatized eclogites (Type I) have a higher alkali- (Na2O in garnet and K2O in omphacite) and LREE, LILE-content. Non-metasomatized (Type II) eclogites include two main compositional groups, derived from different protoliths. The first …
-
Geobarometry, phase relations and elasticity of eclogite under conditions of Earth’s upper mantle
Eclogite rocks, composed mainly of garnet and clinopyroxene, form principally as a metamorphic product of oceanic crust as it undergoes subduction. The equilibrium between garnet and clinopyroxene is sensitive to temperature and pressure, therefore eclogitic outcrops and xenoliths can reveal …
-
The geochemistry of a suite of eclogite xenoliths from the Rietfontein Kimberlite, South Africa
… of xenocryst lithologies, including peridotite, eclogite and a suite of megacryst minerals. This study focuses on a suite of eclogite xenoliths, which were subject to a detailed petrographical and geochemical study, aimed at their characterisation and comparison to eclogites from on-craton and …
-
A detailed geochemical investigation of diamond-bearing eclogite xenoliths from the Kaalvallei kimberlite, South Africa
The eclogites are essentially bimeneralic assemblages of garnet and clinopyroxene. Thirteen xenoliths contain accessory diamond with graphite on diamond surfaces. One has accessory ilmenite. The rocks are well equilibrated and are classified as Group 1 eclogites, based on their mineral textures and …
-
Experimentally generated partition coefficients for the first-row transition elements during eclogite partial melting at three gigapascals
… which is metamorphosed into a rock called eclogite. The extent of lithological heterogeneity has implications for the rate of convective stirring and chemical homogenization of the mantle but is not well-constrained. Basaltic melts extracted from the mantle carry geochemical information …
-
The geochemistry and origin of xenoliths from the Roberts Victor Mine
… with previous observations greater than 95% are eclogite xenoliths. The paucity of peridotite nodules is attributed to selective sampling by the kimberlite, and to the preferential abrasion of the more readily altered peridotites. 250 samples were selected for further study in slabbed section. …
-
Estimating the thickness of an ultrahigh-pressure (UHP) terrane: insights from phase equilibria modelling and Zr-in-rutile thermometry, Dulan area, North Qaidam terrane, China
… UHP terrane, in western China, exposes minor UHP eclogites hosted by ortho- and paragneisses. In the southeastern part of the terrane, the Dulan area exposes eclogite with the mineral assemblage Grt + Omp ± Ky ± Ph ± Zo ± Qz/Coe. LASS U-Pb analyses of zircons yield weighted mean ages of 463-425 …
-
Metamorphic P-T Path and Multiple Fluid Events During Burial and Exhumation of the Tso Morari UHP Terrane, NW Himalaya
… belt underwent ultrahigh-pressure (UHP) coesite-eclogite metamorphism due to northward subduction of the Indian continent under the Eurasian continent during the early Eocene. In this study we optimized a best protocol for thermodynamically modelling pressure-temperature (P-T) paths of high-grade …
-
Temporal and petrological constraints of ultrahigh-pressure metamorphism and exhumation of crustal material from mantle depths to Earth's surface: Insights from a large and small ultrahigh-pressure terrane
… with minor (~5%) layers and lenses of UHP eclogite; at least twenty terranes have been described and identified by the preservation of UHP minerals (i.e., coesite and diamond) mainly within eclogite. These terranes fall into two broad categories: 1) large (30,000 km2) coherent terranes …
-
The thermal structure of collisional orogens – insights from the Grenville orogen in Canada and Scotland
… research focuses on two study regions: (1) the eclogite-facies Glenelg inlier in northwest Scotland, and (2) a 130 km across-strike transect through the type-locality in eastern Canada, encompassing the orogenic foreland and two overlying thrust sheets. Together, these areas span a wide range of …
-
A geochemical study of diamonds, diamond inclusion minerals and other mantle minerals from the Klipspringer kimberlites, South Africa
… The Klipspringer lithosphere is dominated by eclogite and Iherzolite with harzburgite and dunite present to a lesser extent.
-
Advances in Subduction Zone Processes
… as it transitions from blueschist to eclogite facies resulting in the breakdown of volatile-bearing minerals and producing anhydrous minerals and a free fluid phase. Previous works attempting to understand the evolution of subducted lithologies have provided a firm foundation in which …
-
Mineral equilibria constraints on open-system melting and consequences of melt loss in metabasic rocks
… evolution of representative amphibolite and eclogite compositions under orogenic P-T conditions in the crust.
-
Applying Garnet and Zircon REE Linkages to Determine Timing of P-T Conditions and Tectonic Implications for UHP Eclogites and HP Granulites, Dulan UHP Terrane, China
… the timing of peak P-T conditions in UHP eclogites and HP granulites, and the tectonic significance of their spatial relationship within the Dulan UHP terrane are not well understood. This study, (1) evaluates rare earth element (REE) equilibrium between garnet and zircon, to assess coeval …
-
From the Appalachians to the Alps: Constraints on the Timing, Duration, and Conditions of Metamorphism at Convergent Margins
… chapter 4, diffusional speedometry is applied to eclogite breccias from the Monviso ophiolite to quantify the periodicity of transient deformation and metamorphism at eclogite facies P-T conditions. The maximum timescale for repeated fracturing is constrained to ~1 Myr., likely caused by cyclic …
-
Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity
… subduction zones, a refractory, rutile-bearing eclogite may contribute the positive TITAN anomalies.
-
Petrology and tectonic setting of relatively low temperature eclogites and related rocks in the Dalsfjord area, Sunnfjord, West Norway.
… the overlying unit by a zone of protomylonites. Eclogites are found in all the units. Gradational or intrusive relationships show that all the units are mutually autochthonous. Many eclogites had demonstrable low-pressure igneous protoliths and/or intrusive relationships with the gneisses, …
-
Surface textures on pyrope, picroilmenite and chrome diopside from Kimberlite
… commonly found in most garnet peridotites, some eclogite xenoliths from kimberlite, as well as a few garnet-bearing serpentinites. Although the relative abundance of kelyphite-encrusted garnet varies from one kimberlite to another, kelyphite shells are most commonly developed on mauve garnets …
-
Petrological and geochronological constraints on the metamorphic evolution of high-pressure granulites and eclogites of the Snowbird tectonic zone, Canada
… geochronology of high-pressure granulites and eclogites within the Snowbird tectonic zone of the western Canadian Shield. The focus of this study is the East Athabasca mylonite triangle (EAmt), a well-exposed terrane of granulite facies mylonitic rocks along the trace of the Snowbird tectonic …
Page 1 of 2