The Irtysh shear zone (ISZ) is an important structure in the framework of the Central Asian Orogenic Belt (CAOB). It represents the site of final collision of Kazakhstan with Siberia during Hercynian times and records up to 1000 km of lateral displacement during subsequent reorganization in the CAOB edifice. We present new zircon U/Pb, apatite fission track and fault kinematic data along the ISZ and consequently derived its tectonic history with emphasis on its formation and reactivation episodes. Carboniferous (340–320 Ma) zircon U/Pb ages were obtained for the syn- and post-collisional Kalba–Narym intrusives, dating their emplacement in the framework of the Siberia–Kazakhstan collision. During this period, the ISZ experienced an ‘early brittle’ left-lateral, mainly transtensional stress regime. Late Carboniferous–Early Permian post-collisional intrusives were emplaced and the stress regime changed to a ‘late brittle regime, characterized by more compressional conditions, indicating rheological strengthening as a response to cessation of ductile shearing and cooling of the ISZ crust. Apatite fission track data and thermal history modeling reveal Late Cretaceous (100–70 Ma) cooling of the ISZ basement rocks as a response to denudation of a bordering Late Mesozoic Altai orogen. After this denudation event, the tectonic activity ceased during the Late Mesozoic–Early Cenozoic. A final step of cooling (from 25 Ma), exhibited by some of the thermal history models, may reflect reactivation of the ISZ and initiation of Cenozoic Altai mountain building. The Late Plio-Pleistocene phase of mountain building coincides with a new change in the Palaeostress field, characterized by minor transpressional, right-lateral shear conditions.

The following structural elements have been recognized to constitute the tectonic demarcation of Central Asian Foldbelt: (1) The Kazakhstan–Baikal composite continent, its basement formed in Vendian–Cambrian as a result of Paleoasian oceanic crust, along with Precambrian microcontinents and Gondwana-type terranes, subduction beneath the southeastern margin of the Siberian continent (western margin in present-day coordinates). The subduction and subsequent collision of microcontinents and terranes with the Kazakhstan–Tuva–Mongolia island arc led to crustal consolidation and formation of the composite-continent basement. In Late Cambrian and Early Ordovician, this continent was separated from Siberia by the Ob’–Zaisan ocean basin. (2) The Vendian and Paleozoic Siberian continental margin complexes comprising the Vendian–Cambrian Kuznetsk–Altai island arc and the rock complexes of Ordovician–Early Devonian passive margin and Devonian to Early Carboniferous active margin. Fragments of Vendian–Early Cambrian oceanic crust represented by ophiolite and paleo-oceanic mounds dominate in the accretionary wedges of island arc. The Gondwana-type continental blocks are absent in western Siberian continental margin complexes and supposedly formed at the convergent boundary of a different ocean, probably, Paleopacific. (3) The Middle–Late Paleozoic Charysh–Terekta–Ulagan–Sayan suture-shear zone separating the continental margin complexes of Siberia and Kazakhstan–Baikal. It is composed of fragments of Cambrian and Early Ordovician oceanic crust of the Ob’–Zaisan basin, Ordovician blueschists and Cambrian–Ordovician turbidites, and Middle Paleozoic metamorphic rocks of shear zones. In the suture zone, the Kazakhstan–Baikal continental masses moved westward along the southeastern margin of Siberia. In Late Devonian and Early Carboniferous, the continents amalgamated to form the North Asian continent. (4) The Late Paleozoic strike-slip faults forming an orogenic collage of terranes, which resulted from Late Devonian to Early Carboniferous collision between Kazakhstan–Baikal and Siberian continents and Late Carboniferous to Permian and Late Permian to Early Triassic collisions between East European Craton and North Asian continent. As a result, the Vendian to Middle Paleozoic accretion-collisional continental margins of Siberia and the entire Kazakhstan–Baikal composite continent became fragmented by large-amplitude (up to a few thousand kilometers) strike-slip faults and conjugate thrusts into several strike-slip terranes, which mixed with each other and thus disrupted the original geodynamic, tectonic, and paleogeographic demarcation.

In the past few decades, the petroleum industry has seen great exploration successes in petroliferous sedimentary basins worldwide; however, the net volume of hydrocarbons discovered each year has been declining since the late 1970s, and the number of new field discoveries per year has dropped since the early 1990s. We are finding hydrocarbons in more difficult places and in more subtle traps. Although geophysical and engineering technologies are crucial to much of the exploration success, fundamentally, the success is dependent on innovative play concepts associated with spatial and temporal relationships among deformation, deposition, and hydrocarbon accumulation. <...>