The Kanar Melange is an ophiolitic melange underlain by Cretaceous shelf-slope argillites and overlain by a thrust sheet of Cretaceous ophiolites. The melange consists of a chaotic mixture of millimeter to kilometer-size clasts embedded in a dominantly argillaceous matrix. The affinities of the clasts are continental (e.g., Mesozoic shelf carbonate rocks, clastic and sedimentary rocks, mafic-ultramafic and alkali-volcanic rock bearing conglomerates) and oceanic (serpentinite, gabbro, and basalt). The matrix is mildly deformed to strongly folded and foliated. The melange was emplaced during the Paleocene in a trough located on the western margin of the Indo-Pakistan subcontinent. A two stage model for the origin of melange is proposed. It involves Paleocene oblique convergence between the western margin of the Indian Plate and the adjoining Neo-Tethys along a Cretaceous transform boundary. This resulted in the formation of a zone of tectonically mixed continental and oceanic rocks (proto-Kanar Melange) bounded by a trough (tectonic foredeep) on the continental margin. Debris from the mixed zone was shed into the trough, leading to the formation of the Kanar Melange. Tectonic mixing of contrasting rock types is considered an important step in the genesis of the Kanar Melange. However, the presence of sedimentary features in the matrix of the melange and its depositional relationship with the underlying Sembar Formation suggest that the emplacement of the melange may have been controlled by sedimentary processes. Oblique convergence culminated in the obduction of ophiolite nappes above the melange and regional-scale folding of the whole area. These events produced a tectonic overprint that obscured primary stratigraphic and structural relationships within the melange belt.

Abstract The southern Kirthar Fold Belt (KFB) and the contiguous Middle Indus Basin (MIB) constitute a major oil and gas province on the southern Pakistan foreland. In the Middle Indus Basin, gas is reservoired in Early Cretaceous marginal marine sandstones sealed by Paleocene shales. Reservoir quality of the Early Cretaceous sediments deteriorates towards the fold belt, but recent discoveries of gas in Upper Cretaceous sandstones sealed by Paleocene shales have highlighted its potential. To understand better the petroleum systems of this region and provide a potential correlation scheme for comparison with other areas of the country, a sequence stratigraphic interpretation was carried out on the Jurassic to Recent sediments of the KFB and MIB. On the basis of outcrop and well data, 23 depositional sequences have been identified: five in the Jurassic units, 10 in the Cretaceous units and eight in the Tertiary units. Sequence boundaries have been defined according to the Exxon method of identifying unconformities and their correlative conformities. However, equal importance has been given to identifying the potentially more chronostratigraphically significant maximum flooding surfaces between these sequence boundaries so as to define accurately the component systems tracts of each sequence. The depositional systems are described in terms of their relationship to the existing lithostratigraphic framework and interpreted in terms of sedimentary responses to external (eustatic) or local (tectonic) events. Notwithstanding the presence of a eustatic signature on some sequences, the majority appear to be tectonically driven and can be related to plate margin events affecting the NW margin of the Indo-Pakistan Plate during its rift-drift-collision history.

Abstract A study of the southern Kirthar fold belt in Pakistan was undertaken to elucidate the hinterland structure and hydrocarbon prospectivity. Interpretation of structure and stratigraphy is difficult because of suboptimal seismic data, a lack of hinterland well data, and a transition from shelfal to basinal stratigraphy. An interpretation of two cross sections was made using outcrop and seismic data and well data from foreland discoveries. The Institut Français du Pétrole Thrustpack ® software was used to validate the structural model and provide data on the maturity of the source rock. The Kirthar fold belt is dominated by open and symmetrical folds that are driven by inversion of basement-involved Jurassic extensional faults. Thrusts have been interpreted with two detachments, thrusts with a shallow detachment in the Eocene mudstones and thrusts with a deeper detachment in the Lower Cretaceous source rock interval that involve the reservoir during deformation. The major mountain-building episode is interpreted as late Pliocene–Pleistocene, but there is evidence for earlier inversion dating from the late Paleocene associated with the emplacement of the Bela ophiolite and constrained by maturity data obtained from outcrop. Early inversion and uplift impacts the burial curve and, thus, the prospectivity of the area.

Abstract The Nanga Parbat massif lies in the core of the major north-south trending, broadly upright antiform that marks the NW syntaxis of the Himalayan arc. However, this antiformal structure is not evident in the trend of foliation and banding within the central and southern parts of the massif. Reconnaissance field studies in this region (Astor, Rama and Rupal areas) have delineated an important shear zone with top-to-the-south overthrust kinematics. This Rupal Shear Zone carries the migmatitic core of the massif onto non-migmatitic metasediments locally termed the Tarshing Group. The shear zone traces north into a broad high strain zone of steep foliation with gently plunging mineral elongation lineations with no consistent sense of shear. A tentative model is proposed whereby top-to-the-south overshear in the Rupal area passes northwards into a steep belt of apparently constrictional N–S elongation. This type of large-scale transpression may record the early growth of the syntaxis. However, relating these structures to Himalayan orogenesis and the amplification of the NW syntaxis is problematic. The Nanga Parbat massif displays a long and complex history of polyphase deformation, metamorphism and magmatism, as might be expected of a terrane derived from the basement of the Indian sub-continent. Although at least the later part of the constrictional steep belt developed with syn-kinematic leucogranite intrusions (< 10 Ma), the old age limit on the Rupal Shear Zone remains unconstrained.

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Four left-stepping pressure ridges extend for nearly 60 km parallel and close to the southern margin of the Peshawar basin, cutting diagonally across older imbricate thrust structures of the Attock-Cherat Range. Lacustrine, fluvial, and alluvial-fan deposits dated at 2.8 to 0.6 Ma are strongly folded, faulted, and eroded prior to deposition of alluvial-fan gravels, which are themselves cut by east-northeast–trending faults with their north sides upthrown. The pressure ridges postdate some of the fan drainage but deflect other drainage. The east-northeast–trending faults are high-angle and accompanied by instrumental seismicity; there is no evidence for strike-slip except for the en echelon distribution of the ridges and low-angle slickensides on one of the faults. Alluvial-fan and fluvial sediments are folded and faulted at Tarbela Dam, 40 km east-northeast of the easternmost pressure ridge, and the base of Indus River gravels is apparently displaced by a reverse fault with the northwest side up. Farther north, a fault adjacent to Tarbela Lake has left-lateral displacement. Additional lineations and south-facing scarps occur throughout the Attock-Cherat Range, and Jurassic limestone is faulted over gravels at the western end of the Nizampur basin. We interpret these features as part of a broad zone of deformation involving seismogenic crust; direction of slip is south-southwest. There is no evidence of surface rupture in this zone during Holocene time.

Abstract The outcrops are located in southern Pakistan in the southern part of the Pab mountain range, in a north-south-trending monocline more than 200 km (125 mi) long. In this area, the late Maastrichtian Pab Formation consists of turbidite and gravity-flow deposits in a lower-slope to basin setting. The Pab mountain belt is incised by dry river gullies, which provide excellent, large-scale 3-D exposures of the architecture of the Pab Formation. At the base of the Pab Formation outcrop belt, a sand-rich turbidite system is preserved from the canyon setting to the lobes of the basin-floor fan. This lower Pab Formation turbidite system consists of three vertically stacked channel complexes, organized in a backstepping succession, that onlap the paleomargin; each channel is >100 m (>330 ft) at its thickest point. The following pages describe the uppermost channel complex of the lower Pab Formation. This channel complex consists of several multi-story, individual channels that are stacked vertically or migrated laterally, depending on the local confinement. These channels have cut into sheet sands. The outcrop at the North Baddho gully location is interpreted as being in the midfan setting at a location approximately 10 km (6 mi) basinward of the canyon mouth. The vertical organization of the complex is overall backstepping. At the base of the complex, bypass facies dominate; fill and then spill deposits become dominant toward the top. During the erosional stage of the individual channels, bypass facies were deposited (mud-clast lags, thin-bedded drapes, and monogenic debris flows), while overflow deposits (levees and crevasse lobes)

Abstract The outcrops are located in southern Pakistan in the southern part of the Pab mountain range, in a north-south-trending monocline more than 200 km (125 mi) long. In this area, the late Maastrichtian Pab Formation consists of turbidite and gravity-flow deposits in a lower slope to basin setting. The Pab mountain belt is incised by dry river gullies, which provide excellent, large-scale 3-D exposures of the architecture of the Pab Formation. At the base of the Pab Formation outcrop belt, a sand-rich turbidite system is preserved from the canyon setting to the lobes of the basin floor fan. This lower Pab Formation turbidite system consists of three vertically stacked channel complexes organized in a backstepping succession onlapping the paleomargin, each one more than 100 m (330 ft) at its thickest point. The following pages describe the three stacked channel complexes in the Drabber Dhora outcrop, which is interpreted as being located at the canyon mouth of the lower Pab Formation turbiditic system. These channel complexes consist of several multistory, individual channels that are stacked vertically because of the confinement of the system. The vertical organization of the complex is overall backstepping. At the base of the complex, bypass facies dominate, whereas fill and then spill deposits become dominant towards the top. During the erosional stage of individual channels, bypass facies were deposited (mud-clast lags, tractive megadunes, gravel lags, and monogenic debris flows), while overflow deposits (levees) were deposited laterally to the channel axis. Overflow deposits are poorly developed in the canyon-mouth setting because of the confinement of the system.

Abstract The Main Mantle Thrust (MMT) represents the tectonic boundary between metamorphic shield and platform rock of the Indian plate hinterland, and dominantly mafic and ultramafic rock of the Kohistan-Ladakh arc complex in Pakistan. In some areas, this boundary is a sharp planar fault with development of mylonite; in other areas, it is a brittle-ductile imbricate zone; in still other areas, it contains large, discontinuous, slices of internally sheared and deformed ophiolitic mélange. The character of the MMT along its entire trace is discussed and it is concluded that there is no single continuous fault which marks the contact between the Indian plate and the Kohistan-Ladakh arc. On this basis, we propose a revised definition for the MMT that is consistent with both the original definition and with the usage of the term in literature. We suggest that the MMT fault contact be defined as the series of faults, of different age and tectonic history, that collectively define the northern margin of the Indian plate in Pakistan. On this basis, faults that define the MMT vary in age from Quaternary to possibly as old as Late Cretaceous. Discontinuous lenses of ophiolitic mélange that overlie the MMT fault contact, and which intervene between the Indian plate and the Kohistan-Ladakh arc, are considered to be part of an MMT zone that is equivalent with the Indus Suture Zone.

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