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Petrogenesis of Neoproterozoic Ultramafic Rocks, Wadi Ibib–Wadi Shani, South Eastern Desert, Egypt: Constraints from Whole Rock and Mineral Chemistry
- Source :
- Applied Sciences, Volume 11, Issue 22, Applied Sciences, Vol 11, Iss 10524, p 10524 (2021)
- Publication Year :
- 2021
- Publisher :
- MDPI AG, 2021.
-
Abstract
- This contribution deals with new geology, petrography, and bulk-rock/mineral chemistry of the poorly studied ultramafics of Wadi Ibib–Wadi Shani (WI–WS) district, South Eastern Desert, Egypt. These ultramafics are dismembered ophiolitic rocks that can be subdivided into serpentinites and serpentinized peridotites. Primary minerals such as olivine and pyroxene are absent in serpentinites, but relics of them occur in serpentinized peridotites. Pseudomorph after olivine is indicated by common hourglass textures with less mesh, whilst schistose bastites reflect a pyroxene pseudomorph. Chromite can be subdivided into Cr-spinel and Al-spinel. Cr-spinel ranges from chromite to magnesochromite in composition, whereas Al-spinel belongs to the spinel field. Cr-spinel includes YCr (Cr/(Cr+Al+Fe+3), YAl (Al/(Al+Cr+Fe+3), and YFe+3 (Fe+3/(Fe+3+Al+Cr), similar to forearc peridotite, whilst Al-spinel is more similar to abyssal peridotite, and may be formed during inanition of subduction processes in proto forearc environments. The main secondary minerals are tremolite, talc, and chlorite—which is subdivided into pycnochlorite and diabantite—and their temperature ranges from 174 to 224 °C. The examined rocks had undergone high partial melting degrees (&gt<br />25%), as indicated by the Cr# of their unaltered cores (Cr-spinel, &gt<br />0.6), whole rocks (Al2O3, SiO2, CaO, and MgO), trace and REEs, depleted Na2O, Al2O3, and Cr2O3 of clinopyroxene, and high forsterite content ((Fo = 100 Mg/Mg + Fe), av. 95.23 mol%), consistent with forearc settings.
- Subjects :
- Technology
QH301-705.5
partial melting
QC1-999
Geochemistry
serpentinization
Pyroxene
engineering.material
element mobility
Ultramafic rock
General Materials Science
Biology (General)
QD1-999
Instrumentation
Petrogenesis
Fluid Flow and Transfer Processes
Peridotite
Olivine
Physics
Process Chemistry and Technology
General Engineering
Partial melting
Engineering (General). Civil engineering (General)
Computer Science Applications
Chemistry
engineering
Chromite
TA1-2040
forearc affinity
Pseudomorph
Geology
Subjects
Details
- ISSN :
- 20763417
- Volume :
- 11
- Database :
- OpenAIRE
- Journal :
- Applied Sciences
- Accession number :
- edsair.doi.dedup.....35719c0abb951e98a4db8541fe85992b