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Seismic numerical modeling technique provide most suitable way for the simulation of wave propagation through subsurface rocks and play an essential role in seismic interpretation, seismic inversion and in evaluating and designing a seismic survey. In order to delineate subsurface more precisely, different approaches are proposed for numerical modeling in which the solutions of Biot’s poroelastic equation are given by using reflectivity, finite element and finite difference algorithms. In current study, a finite difference forward modeling method is proposed to quantify the variation in wave properties during its propagation in a poroelastic media exhibiting mesoscopic heterogeneity due to the existence of three phase fluids. The Biot’s poroelastic wave equations are resolved and a generalized finite difference technique in time domain (FDTD) is used to examine seismic responses in a poroelastic media saturated with three phase fluids. So that the ability to detect geo-fluids through forward modeling technique can be improved. The accuracy of the simulation will lay a good foundation for the follow up work and will enhance our understandings about wave propagation through multi-phase poroelastic media and will also assist in detection and discrimination between fluids of different nature. Also, the proposed approach is of great significance for imaging and prediction of subsurface structures and distribution of fluids.

Subsurface samples of the Talhar shale, Lower Goru Formation, are analyzed for smectite (montmorillonite) and illite in the Nur-dep#1 (ND‒1), well 2, Southern Lower Indus Basin, Pakistan. The ND‒1, well 2 is an unsuccessful well drilled by the OGDCL, Pakistan, for the shale gas exploration. Illitization and elemental content constrained using XRD qualitative and XRF quantitative analyses, respectively. The illite content increases from 15 to 55% with increasing depth. The fine-grained shale comprises chlorite, kaolinite, halloysite, allophane, muscovite, microcline, illite and montmorillonite. Chlorite was observed at 3450–3452 m, whereas kaolinite is present at depth range of 3450–3482 m. The mix layer expandability decreases from 40 to 20% at depth ranges from 3450 to 3552 m, respectively. The interstratification is random to ordered. Potassium and silicon contents with respect to aluminum and calcium are increasing with depth. Data obtained in this research indicate that the shale gas is immature and the oil is an early–medium stage of maturation.

The Chakdara Granitic Gneisses (CGG) of the Indian plate and Kamila Amphibolite of the Kohistan Island Arc (KIA) along the Main Mantle Thrust (MMT) in Shigo Kas, Talash Dir Lower, indicate that tectonically induced foliations and lineations strongly affected the geomechanical properties of these rocks. The earlier S1 crenulated cleavages are well preserved in the microlithon of a well-developed ENE-WSW trending S2 crenulation cleavage. The pervasive S2 foliations, D2 fold axes, and L22 lineations are induced by NNW-SSE horizontal bulk shortening. The core samples obtained parallel and perpendicular to the main ENE-WSW trending S2 and L22 have higher and lower uniaxial compressive strength (UCS) values, respectively. The UCS and uniaxial tensile strength (UTS) average values of four core samples obtained parallel and perpendicular to the main S2 are 51.8 MPa and 12.21 MPa versus 45.65 MPa and 12.45 MPa, respectively. Core samples from the weakly foliated S-2 specimen shows little variation in the UCS and UTS values. The variation in the UCS values in the core samples cut perpendicular and parallel to the main tectonic fabric has been controlled by micro-shear zones at the contact zones of crenulated and crenulation cleavages and sigmoidal mica fish. The UCS values are higher in the core samples parallel to the pervasive S2 and L22 because the parallel shear on the sigmoidal crenulated cleavages in microlithon of the S2 and S2 mica fish counterbalance the parallel external applied load. However, the UCS values decrease in the core samples that were cut perpendicular to the pervasive S2 and L22 because the perpendicular shear on the sigmoidal crenulated cleavages in microlithon of the S2 and S2 mica fish enhances the external applied load, which lead to the failure of core samples.

New metamorphic petrology and geochronology from the Loe Sar dome in the Swat region of northern Pakistan place refined constraints on the pressure, temperature and timing of metamorphism and deformation in that part of the Himalayan orogen. Thermodynamic modelling and monazite petrochronology indicate that metamorphism in the area followed a prograde evolution from ∼525 ± 25 °C and 6 ± 0.5 kbar to ∼610 ± 25 °C and 9 ± 0.5 kbar, between ca. 39 Ma and 28 Ma. Partitioning of heavy rare earth elements between garnet rims and 30–28 Ma monazite are interpreted to indicate coeval crystallization at peak conditions. Microtextural relationships indicate that garnet rim growth post-dated the development of the main foliation in the area. The regional foliation is folded about large-scale N–S trending fold axes and overprinting E–W trending folds to form km-scale domal culminations. The textural relationships observed indicate that final dome development must be younger than the 30–28 Ma monazite that grew with garnet rims post-regional foliation development, but pre-doming-related deformation. This new timing constraint helps resolve discrepancy between previous interpretations, which have alternately suggested that N–S trending regional folds must be either pre- or post-early Oligocene. Finally, when combined with existing hornblende and white mica cooling ages, these new data indicate that the study area was exhumed rapidly following peak metamorphism. Keywords: Pakistan, Himalaya, Monazite petrochronology, Metamorphism, Phase equilibria modelling, Deformation

Bedding parallel stylolites (BPS), N–S trending microscopic to macroscopic normal faults, and N–S trending calcite-filled veins in the E–W trending Early Devonian Khyber Limestone are synchronously formed as a consequence of vertical shortening. Veins, early stylolite surfaces, and flow folds that oriented oblique to stylolite surfaces have been dissolved in a way that they appear to be displaced by a fault with a strike–slip components. These apparent strike–slip movements along the younger stylolite surfaces have been imparted by selective pressure dissolution of the oblique calcite-filled veins in the Khyber Limestone. The concentration of insoluble residue along the stylolite interface has also facilitated strike–slip movement in an opposite direction to apparent displaced by pressure dissolution. Crosscutting relationship of calcite-filled veins and BPS led to distinguish at least two generations of vein and stylolite formation across the region.