TITLE:
Controls and Implications of Geo-Technical Variation in Quartzose Rocks from Peshawar Basin, North-Western Pakistan
AUTHORS:
Khan Zada, Mohammad Arif, Muhammad Sajid
KEYWORDS:
Quartzose Rocks, Petrography, Strength, Physical Properties, Geo-Technical Feasibility
JOURNAL NAME:
Geomaterials,
Vol.5 No.4,
October
12,
2015
ABSTRACT: Petrographic and geo-mechanical
properties of samples representing quartzose rocks of Tanawal Formation (Baja
Bamkhel area, Swabi) and Misri Banda quartzite (Nowshera) from Peshawar Basin,
NW Pakistan, have been investigated. Although formerly referred to as
quartzite, mineralogical composition and textural details support
characterization of the studied quartzose samples of Tanawal Formation as
blasto-psammite and those of Misri Banda as sub-arkose. The two rock types also
show significant differences in terms of matrix and heavy mineral
concentrations as well as the degree and frequency of intra-granular deformation.
On the basis of unconfined compressive strength (UCS), both fall in the
category of very strong rocks. Correspondingly, their specific gravity and
water absorption values are high and low respectively and lie well within the
range permissible for use as construction material. However, both contain high
amounts of deleterious components, i.e. reactive forms of
silica (chert and/or strained quartz) and clay minerals. Therefore, they cannot
be used as coarse aggregate with Ordinary Portland Cement (OPC) and asphalt.
The modal abundance of quartz is higher in the Misri Banda than the Tanawal
samples, but the quartz to feldspar ratios are higher for the latter. Yet, the
sub-arkosic Misri Banda rocks are stronger than the Tanawal blasto-psammites,
most probably because they are i) almost totally devoid of matrix; ii) finer
grained; iii) having a higher percentage of grains with irregular and sutured
contacts and iv) lesser abundance of grains displaying intra-granular
deformation.