Composition, Texture, and Weathering Controls on the Physical and Strength Properties of Selected Intrusive Igneous Rocks from Northern Pakistan

Abstract

This study examines the mineralogy, texture, and weathering grades of intrusive igneous rocks from northern Pakistan, as well as their impacts on physical and strength properties. In comparison to felsic rocks, mafic and intermediate rocks have lower cumulative proportions of quartz, feldspar, and plagioclase, as well as higher specific gravity, strength (i.e., UCS and R-value), and UPV values. Similarly, samples with anhedral grain shapes, irregular boundaries, and fine to medium grain sizes (UD, ANS, and CGN) exhibited greater strength values, with compressive strengths of 121, 118, and 91 MPa and tensile strengths of 11, 9, and 12 MPa, respectively. The physical and strength properties of the investigated samples corresponded well with the weathering grades assigned to them, such as fresh (WG-I), slightly weathered (WG-II), and highly weathered (WG-III). That is, as the grade increased from WG-I to WG-III, the porosity and water absorption increased (0.28% and 0.72%, respectively), whereas the specific gravity, compressive strength, and tensile strength decreased (2.04, 20, and 2.5 MPa, respectively, for CGA). Although the presence of quartz impacts rock strength, no significant association was found between the strength and the maximum and mean grain sizes of other minerals.

Determination of Dynamic Properties of Fine-Grained Soils at High Cyclic Strains

“…The faults influencing the region of Peshawar are the Main Mantle Thrust (MMT), Hazara-Kashmir Syntax, Punjal fault, and faults with reverse faulting mechanisms in the Kohat ranges. Most of the earthquakes that affect Peshawar have their origin in the Hindu Kush region of Afghanistan or the northern areas of Pakistan [28][29][30]. The Hazara-Kashmir syntax is connected to the Punjal fault, Jhelum fault, and Main Boundary Thrust (MBT) [31][32][33].…”

“…The DYNATRIAX software produced the shear modulus and damping ratio. Figure 5 depicts a symmetrical hysteresis loop (SHL), illustrating the conventional approach for calculating dynamic properties [30]. In this method, the dynamic shear modulus (G) is determined using the secant Young's modulus (Esec), which is obtained by connecting the peak compressive and tensile stress-strain points.…”

Chemical Elements Analysis of Arjuno-Welirang Igneous Rocks

“…This can usually be found in volcanoes or volcanic valleys. Volcanic rocks in petrology and geology are extrusive igneous rocks (Yasir et al, 2022). This type of rock is formed from magma that comes to the surface, which is called lava (Adikusuma et al, 2020;Boomeri et al, 2020;Patro et al, 2022).…”

Weathering Effects on Engineering Geological Properties of Trachydacitic Volcanic Rocks from the Monte Amiata (Southern Tuscany, Italy)

“…While lithology depends on the rock-forming environment and does not evolve over time, the degree of weathering may be time-dependent, and it may show different degrees of intensity in space. Rock weathering may play an important role on the evolution of landforms [5,6], slope instability [7][8][9][10][11][12][13] and engineering geological properties [14][15][16]. Namely, strength parameters are strictly dependent on both intrinsic lithology and secondary weathering degree [4], the latter being often evaluated through expert-based visual properties [17,18] and/or mineralogical characteristics determined by modal analyses [19].…”