The fate of olivine in the lower crust: Pseudomorphs after olivine …
2016年9月1日 · Olivine in crustal rocks is highly susceptible to alteration by weathering, hydrothermal processes, or metamorphism (Delvigne et al., 1979). Nevertheless, its former presence can be inferred from a variety of pseudomorphs, ranging from clay minerals and sheet silicates in low-temperature settings to orthopyroxene-bearing coronas in high-grade ...
Olivine is mainly associated with other basic or ultramafic minerals that crystallized during the first stages of magmatic fractionation, viz. with pryoxenes (enstatite, bronzite, hypersthene, augite), with certain
The fate of olivine in the lower crust: Pseudomorphs after olivine …
2016年9月1日 · The unusual co-occurrence of granulite-facies pseudomorphs after olivine with an alteration product formed at near-surface conditions indicates that some olivine may survive protracted high-grade metamorphism in environments where fluid access is limited.
Iddingsite - Wikipedia
It is a pseudomorph that has a composition that is constantly transforming from the original olivine, passing through many stages of structural and chemical change to create a fully altered iddingsite. Because iddingsite is constantly transforming it does not have a definite structure or a definite chemical composition.
Pseudomorphs after olivine in Markle basalt from Holyrood Park, Edinburgh, consist of an intimate mixture of hematite and chlorite, along with a small percentage of quartz.
Olivine Pseudomorphs after Serpentinized Orthopyroxene Record …
2012年8月21日 · Even though olivine (Ol) grains are parallel, misorientations between areas are high and no specific crystallographic plane can be associated with the ‘pseudo-cleavage’ appearance.
Olivine Pseudomorphs after Serpentinized Orthopyroxene Record …
Whole-rock compositions indicate a harzburgitic composition; however, microstructural and chemical observations and the current absence of primary orthopyroxene suggest that the precursor silicate of every parallel olivine domain was a single orthopyroxene grain that was initially serpentinized and later dehydrated to result in the present ...
We examine the partial survival of high-temperature mantle microstructures throughout multi-stage hydration- and dehydration-mediated pseudomorphism at differing pressure^temperature^fluid...
(PDF) Formation of Mg-rich Olivine Pseudomorphs in
2016年1月6日 · A unique feature of the serpentinization in the Nuasahi dunites, which to our knowledge has not been previously described, is the formation of a pseudomorphic rim of Mg-rich olivine (Fo98)...
Pseudomorphs after olivine in Markle basalt | Mineralogical …
Pseudomorphs after olivine in Markle basalt from Holyrood Park, Edinburgh, consist of an intimate mixture of hematite and chlorite, along with a small percentage of quartz. A definite relationship exists between the orientations of the two main constituents and is …