TITLE:
Barrellite and Pillarrite: A Description and a Mode of Formation of a Novel Post-Sedimentary Twin Structures from As-Subbiyah, North of Kuwait Bay, Kuwait
AUTHORS:
Ali T. Al-Mishwat
KEYWORDS:
Barrellite, Pillarrite, As-Subbiyah, Kuwait, Post-Sedimentary, Twin Structure
JOURNAL NAME:
International Journal of Geosciences,
Vol.12 No.7,
July
22,
2021
ABSTRACT: I report on the occurrence of a pair of novel and related
post-sedimentary structures that form in the Neogene cross-bedded
red sandstones in the As-Subbiyah area, north of Kuwait Bay, Kuwait. I named
them barrellite and pillarrite. Barrellite forms as vertical tubes of
concentric sheaths of siltstone with partially hollow interior or intervening
homogeneous and structure-less sandstone. It stands as barrels above the
background sandstone. Pillarrite forms as discrete, vertical and solitary
spines of homogeneous sandstone and siltstone, or inside barrellite masses from
which successive siltstone sheaths were stripped. The structures range in
diameter from one-centimeter poke marks to one-meter-wide barrels and hunks,
and their vertical length exceeds two meters. Barrellite, pillarrite and their
complex intergrowths develop near thin quartz veins and chaotic zones, and form
with them complex geometrical relationships. The dual structures are genetically
related and fall within the general class of tubular structures in sedimentary
rocks. I consider them as a special type of sand injectites. The mode
of formation of these structures is enigmatic. They develop in a geological
setting that displays evidence of a widespread and vigorous oil field brine. I
suggest a tentative scenario for their formation,
involving flushing of the brine through hydraulic fracturing of the sedimentary
succession above the Ebharah Oil Field reservoir in the As-Subbiyah area. The
brine plucks mineral and rock fragments and mixes with them along its
paths, producing a heterogeneous slurry. Ultimately, the slurry solidifies as
barrellite and pillarrite, chaotic zones and quartz veins. The vertical nature
of the structures, circular and internal concentric arrangements, as well as
the homogenous lithology inside their masses mimic characteristics of flow and
deposits in vertical and horizontal pipelines.