Cryptic layering
WebThe anomalous position of highly calcic plagioclase near the top of the intrusion, inferred from field relations, coupled with possible reverse cryptic layering suggests a separation of anorthosite by flotation or rafting of plagioclase. © 1975 Geological Society of America. WebJan 1, 2000 · Modal layering of silicates and magnetite is well developed in the mafic rocks as is modal and cryptic (precious metals) layering of the sulfides in the Precious Metals …
Cryptic layering
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Web1.Cryptic layering develops when the magma chamber is not periodically recharged. 2.Podiform chromite crystallizes at the forearc region. 3.Layered intrusions are associated with ophiolite complexes. 4.Cryptic layering in LMI’s is likely to occur when the magma in the intrusion is not replenished. WebJun 1, 1992 · This type of cryptic layering has not previously been described and is informally called ‘cryptorhythmic’ layering. Pyroxene compositional variation is related to …
WebCryptic layering. Not visible to naked eye, chemical variations. Mg content in mafic phases and Ca content in plag decrease going upward. Rhythmic layering. Layers repeat … WebJan 1, 1996 · Layering is a common, almost ubiquitous, feature of gabbroic and syenitic intrusions. Individual layers, or layered sequences, however, vary greatly in such features as thickness and length, the nature of layer boundaries, internal vertical and lateral variations within layers, and the relationships to other nearby layers.
WebSome chemical trends in the rocks indicate that cryptic layering is present but is the reverse of that found in most mafic layered intrusions. The anomalous position of highly … Web1.Cryptic layering develops when the magma chamber is not periodically recharged. 2.Podiform chromite crystallizes at the forearc region. 3.Layered intrusions are …
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WebAfter the Second World War this “Skaergaard memoir” quickly became the “avant garde” of much igneous petrologic thinking, and the study of layered intrusions, the cumulates they contain, and the rhythmic and cryptic layering they exhibit, became a major field of research. A follow-up expedition to E Greenland was not possible until 1953. shubert ho edmondsWebOct 1, 2024 · It displays evident layering of modal abundance, visible directly in outcrop, as well as cryptic layering discernible through changes in mineral compositions. The western and eastern lobes of the Dahanib intrusion occur in the form of a lopolith with readily correlated layers, especially in the upper mafic unit. shubert hopkinsWebcryptic layering (Fig. 5a–f). Indeed, the traverse a-b appears to be oriented across the layering rather than extending along a monotonous layer of orthopyroxenite, as is … theo somsenhttp://www.alexstrekeisen.it/english/pluto/cumulate.php#:~:text=%E2%80%A2%20Cryptic%20layering%3A%20Systematic%20variation%20in%20the%20chemical,feldspars%29%20with%20stratigraphic%20height%20in%20a%20layered%20sequence. shubert internshipWeblayering is less pronounced. Textures indicate that rocks cooled very slowly and the co-existing mineral compositions indicate re-equilibration to usually low temperatures. theo sommer gmbhWebSep 1, 2024 · A slurry refers to a crystal-liquid mixture that is only able to flow under pressure ( i.e., a Bingham fluid), whereas a mush is a partially molten rock consisting of a continuous solid framework, within which trapped liquids may percolate and convect ( Marsh, 2013; Cashman et al., 2024 ). theo sommer wikiWebMar 10, 2024 · Cryptic melt replenishment with incomplete mixing and variable melt-crystal ratios may be responsible for: (1) apparent chemical disequilibrium among crystals, as to overgrowth, remelting and formation … shuberth rapex helmet