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SUMMARY:Petrologic and Geochemical Constraints on the Evolution of Rocks i
 n Southwest Ugep\, Southeastern Nigeria
DTSTART;VALUE=DATE-TIME:20260325T101000Z
DTEND;VALUE=DATE-TIME:20260325T103000Z
DTSTAMP;VALUE=DATE-TIME:20260426T030117Z
UID:indico-contribution-10339@events.saip.org.za
DESCRIPTION:Speakers: ADAEZE UGWU (University of Wyoming\, USA)\nUgep Sout
 hwest is an extension of the Nigerian Basement Complex. It consists of Pre
 cambrian crustal rocks that include a succession of deformed metamorphic r
 ocks and non-deformed sedimentary rocks that overlie the basement rocks. T
 he metamorphic rocks are intruded by granodiorites and pegmatites. Gneisse
 s display a sharp contact relationship with the schists\, occurring in ass
 ociation with quartzite as observed in Ikot Ekperem. Granodiorites contain
  enclaves of schistose xenoliths\, indicating that magmatic stoping was th
 e mode of emplacement during the Pan-African Orogeny (600 ± 50 Ma). Ugep 
 Southwest has undergone various stages of deformation\, as evidenced by co
 mplex structures such as folding\, faulting\, fracturing\, lineation\, and
  foliation. The grade of metamorphism was progressive from lower greenschi
 st facies (phyllites and schists) in the west to middle amphibolite facies
  (gneisses) in the east. Petrological observation using Scanning Electron 
 Microscope (SEM) reveals that the metamorphosed rocks are dominantly compo
 sed of plagioclase\, biotite\, chlorite\, and muscovite. Pegmatites have a
  higher concentration of quartz relative to their magma source. Geochemica
 l analysis using X-ray Fluorescence Spectrometer (XRF) reveals high conten
 ts of silica and alumina\, implying a crustal origin for the rocks. Barium
  concentration was higher\, suggesting contamination by crustal materials.
  The geochemistry of these rocks reveals that phyllite and schist are meta
 sediments of pelitic and greywacke composition\, while the gneiss is ortho
 gneiss. Granodiorite is calc-alkaline\, and the dolerite is tholeiitic. Th
 e plots in variation diagrams confirm these geochemical signatures.\n\nhtt
 ps://events.saip.org.za/event/272/contributions/10339/
LOCATION:
URL:https://events.saip.org.za/event/272/contributions/10339/
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