@article{MAKHILLRJAS2012739197,
title = {Strain Partitioning and Dimensional Preferred Orientation in a syn-Tectonic Granitoid, S.E. Nigeria},
journal = {Research Journal of Applied Sciences},
volume = {7},
number = {3},
pages = {158-164},
year = {2012},
issn = {1815-932x},
doi = {rjasci.2012.158.164},
url = {https://makhillpublications.co/view-article.php?issn=1815-932x&doi=rjasci.2012.158.164},
author = {Michael I.},
keywords = {phenocrysts,orientation,arithmetic,geometric,harmonic,Strain},
abstract = {Uwet granodiorite, a syn-tectonic granitoid of Pan-African
age in South Eastern Nigeria is partly porphyritic, containing megacrysts of
K-feldspars, xenoliths and ellipsoidal bodies. The preferred orientations of
the feldspar phenocrysts are in the NE-SW, NW-SE and N-S, the strongest being
the NW-SE trend. The E-W sectors show minimum grain orientation. Calculated
values of strain-arithmetic mean
, geometric mean G and harmonic mean H show minimum strain for grains in E-W
orientation and maximum strain for grains in N-S orientation. Phenocrysts in
NE-SW and NW-SE orientations showed intermediate values of strain with the latter
axis having higher values than the former. Generally, irrespective of orientation
or axis, the relationship
>
G>H was found to hold. The analysis favours the interpretation that when
two simple shears and a pure shear operate simultaneously in a viscous/ductile
matrix at high temperature under a non-hydrostatic stress state, dimensional
preferred orientation and strain are partitioned unequally along those axes.
The paucity of phenocryst orientation and low strain values in the E-W axis
are an indication that maximum compressive stress (
)
was oriented in this direction, during the Orogeny.}
}