Abstract The genetic analysis of fold and thrust belts is facilitated by tracking the evolution of their organic endowment (petroleum tectonics). Petroleum tectonic analysis of convergent orogenic systems provides an audit of the processes that control the deformation and kinematics of orogenic belts. The distribution and deformation paths of the organic endowment intervals are key factors in determining the petroleum system evolution of fold and thrust belts. This comparison of orogenic systems illustrates the importance of flexural v. dynamic processes, orogenic wedge taper, mechanical stratigraphy and inherited architecture on the creation, preservation and destruction of petroleum accumulations. The Zagros, Pyrenees, Sevier and Beni Sub-Andean convergent systems share key characteristics of fold and thrust belts, with major differences in scale, degree of incorporation of organic endowment in evolution of the fold and thrust belt and its foreland, and preservation of fold and thrust belt wedge-top deposits. The Zagros is an orogen dominated by flexural processes that is a perfect storm for hydrocarbon generation and preservation. Its multiple stacked sources ensure continuous hydrocarbon generation while stacked detachments foster a low taper and thick wedge-top basins. The Pyrenees is also a flexurally dominated orogen, but the early consumption of its source rocks led to minimal survival of hydrocarbon accumulations during exhumation in a long lasting, high-taper orogenic wedge. The Sevier was initially a flexural orogen that was later dominated by dynamic uplift of the fold and thrust belt and distal foreland subsidence with foreland deformation. The consumption of its pre-orogenic sources during the early low-taper phase indicates a probable robust petroleum system at that time. However, the late high-taper phase exhumed and destroyed much of the early petroleum system. The addition of syntectonic foreland sources to be matured by both local and dynamic subsidence created an additional later set of petroleum systems. Post-orogenic events have left only remnants of world-class petroleum systems. The Beni segment of the Sub-Andean Orogen is a flexural system with probable dynamic overprints. Its most robust petroleum system probably occurred during its early low-taper flexural phase, with dynamic subsidence enhancement. Its late high-taper phase with possible dynamic uplift shuts down and stresses the petroleum systems. Comparison of these orogenic systems illustrates the importance of flexural v. dynamic processes, orogenic wedge taper kinematics, mechanical stratigraphy, distribution of source rocks relative to shortening and inherited architecture on the creation, preservation and destruction of petroleum accumulations in fold and thrust belts.

Abstract Traditional structural analysis in fold and thrust belts has focused on quantifying horizontal movements. In this paper, the importance of quantifying vertical movements is illustrated using a case study from Kurdistan, northern Iraq. The subsidence history of this area can be determined by analysis of the stratigraphic record from deep exploration wells. A phase of thermal subsidence from Middle Permian to Late Cretaceous (tectonic subsidence 1.8–1.9 km) was followed by flexural subsidence in the Late Cretaceous and Cenozoic (tectonic subsidence >0.6 km) in response to the closure of the Neo-Tethys Ocean. The main phase of continental collision during the Neogene resulted in the development of the Zagros fold and thrust belt; the amount of uplift at individual anticlines can be estimated from their amplitude (up to 3 km), but regional cross-sections indicate that approximately 1 km of additional basement-involved uplift is present NE of the Mountain Front. The timing of basement-involved uplift is interpreted to be coeval with the deposition of a Pliocene–Quaternary growth sequence adjacent to the Mountain Front. The amount of erosion resulting from the uplift can be estimated from vitrinite reflectance and cross-sections; these estimates show a similar pattern, with maximum erosion in the mountains NE of the Mountain Front (>1.5 km) and lesser erosion in the adjacent foreland basin (generally <0.8 km). The results provide a quantitative understanding of subsidence, uplift and erosion, and have been used to define prospective and high-risk areas for petroleum exploration.