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Plateau (Fig. 2). Here, the surface expression is that of a buried mountain front. A typical traverse may start from the axis of the Soan syncline across the Khairi-Murat Range. Along this traverse, autochthonous flat strata along the axis of the Soan syncline are tilted increasingly northward above a south-dipping passive backthrust (JaswalABSTRACT Surface geology and seismic reflection profiles reveal the geometry of a triangle zone in the Himalayan foreland of Pakistan. Surface expression of the triangle zone is the Soan syncline (monocline), the northern foreland-dipping steep limb of which is located above a bedding-parallel backthrust in the Tertiary molasse strata. The hinterland-dipping Khairi-Murat thrust is located on the proximal end of the triangle zone. The steep Dhurnal backthrust becomes shallower to the south and dies out at a depth of about 2 to 4 km. At this depth, it merges with a north-dipping blind thrust that propagates upsection as a ramp from a layer of Eocambrian evaporites at a depth of about 8 km and forms a flat along a pelitic horizon in Miocene molasse strata. The two faults bound a blind, tapered wedge of allochthonous strata (core wedge) inserted below the backthrust. Coherent and discoherent reflections above and below the Dhurnal backthrust show the undeformed planar and deformed (pop-ups) geometry of the footwall and hanging wall outside and inside the wedge.We interpret the three-dimensional geometry of the triangle zone in terms of a core wedge having flat-ramp-flat geometry and internal as well as external pop-ups. The presence of blind faults of smaller lateral extent (about 10 km) and shortening (about 2 km) indicates the occurrence of more than one hydrocarbon trap in the triangle zone.Published magnetostratigraphy limits the formation of the triangle zone between 2.1 to 1.9 Ma. On the basis of cross-section balancing, we calculate horizontal contraction of 4.5 km and rock uplift of about 2.8 km along the core wedge. The shortening and rock uplift rates amount to about 22 mm/yr and about 14 ± 2 mm/yr, respectively. The presence of hydrocarbons (the Dhurnal oil field) in such young structural traps in the Salt Range has important bearings for the exploration of oil and gas in the Himalayan foreland.

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The burial and pore fluid pressure history of fluorite ore deposits is reconstructed: (i) at Hammam Zriba–Djebel Guebli along the eastern margin of the Tunisian Atlas; and (ii) at Koh‐i‐Maran within the northern part of the Kirthar Range in Pakistan. Both the deposits are hosted by Late Jurassic carbonate reservoirs, unconformably overlain by Late Cretaceous seals. Microthermometric analyses on aqueous and petroleum fluid inclusions with pressure–volume–temperature–composition (PVTX) modeling of hydrocarbon fluid isochores are integrated with kinematics and thermal 2D basin modeling in order to determine the age of mineralization. The results suggest a Cenozoic age for the fluorite mineralization and a dual fluid migration model for both ore deposits. The PVTX modeling indicates that the initial stage of fluorite cementation at Hammam Zriba occurred under fluid pressures of 115 ± 5 bars and at a temperature close to 130°C. At Koh‐i‐Maran, the F3 geodic fluorite mineralization developed under hydrostatic pressures of 200 ± 10 bars, and at temperatures of 125–130°C. The late increase in temperature recorded in the F3 fluorites can be accounted for by rapid rise of hotter fluids (up to 190°C) along open fractures, resulting from hydraulic fracturing of overpressured sedimentary layers.

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