Abstract Precambrian high-pressure (HP) granulites provide important information for reconstructing ancient continental nuclei. Here we report granulites in Eastern Hebei, North China Craton (NCC). They experienced three metamorphic events related to Neoarchean–early Paleoproterozoic orogenesis. The garnet–clinopyroxene granulite defines the M 1 event at P–T conditions of 11–13 kbar and 780–830°C, while the two-pyroxene granulite was produced during the M 2 event at 7–9 kbar and 850–950°C. Both the garnet–clinopyroxene and two-pyroxene granulites experienced amphibolite retrogression during the M 3 event at 5–7 kbar and 710–730°C. Geochemical compositions of these granulites exhibit affinity to island-arc andesites. Zircon U–Pb dating shows that their magmatic precursors were erupted at c. 2538 Ma, and have experienced two-stage growth of zircon rims at c. 2458 and c. 2285 Ma, respectively. The c. 2458 Ma age may represent orogenic events during the amalgamation of micro-continental blocks of the eastern NCC, and the c. 2285 Ma age may be interpreted as the effect of late Paleoproterozoic magmatism. We suggest that the Neoarchean andesitic protoliths of the granulites were metamorphosed at HP granulite-facies conditions during collision of micro-continental blocks, and then exhumed to shallow levels. These early Paleoproterozoic HP granulites recorded the amalgamation of micro-continental blocks to reach the cratonization of the eastern NCC.

Abstract This paper concerns the kinematics of active strike-slip faults in the Arabia–Eurasia collision zone, and how they accommodate plate convergence. Several roles are discernible: (1) collision zone boundaries , the left-lateral Dead Sea Fault System and right-lateral faults in eastern Iran form the western and eastern boundaries of the collision zone; (2) tectonic escape structures , the North and East Anatolian faults transport intervening crust westwards, out of the path of the Arabia; (3) strain partitioning , right-lateral slip on the Zagros Main Recent Fault and NW–SE-striking thrusts to its SW produce north–south convergence, parallel to the plate vector; left-lateral slip along the Alborz range and thrusts across it produce oblique left-lateral shortening; (4) shortening arrays , arrays of strike-slip faults (e.g. Kopeh Dagh and eastern Iranian faults) rotate about vertical axes, producing north–south shortening without crustal thickening; (5) transfer zones , fold trends and earthquake slip vectors change orientation across strike-slip faults in the Zagros, suggesting that these faults allow for changes in thrust transport along strike in the orogen. These different roles emphasize the complex behaviour of continental crust, and the advantages of studying active tectonics rather than ancient examples.

The westward motion of Turkey relative to Eurasia between the North and East Anatolian faults has been cited as one of the best examples of lateral transport of continental crust from a collision zone, in this case the Arabia-Eurasia collision. This process is variously called “escape” or “extrusion” tectonics. Range-parallel strike-slip faults within the Alborz (e.g., the Mosha fault) and Zagros Mountains (the Main Recent fault) of Iran have been regarded as playing roles similar to those of the North and East Anatolian faults in that they are responsible for the eastward transport of intervening Iranian crust away from the northward motion of the Arabia plate relative to Eurasia. However, both seismicity and GPS data show that there is no net eastward transport of Iranian crust with respect to Eurasia. Here we summarize how the tectonically active mountain ranges of Iran deform by combinations of thrusting and strike-slip movement oblique to the overall convergence vector across each region, without requiring net eastward movement with respect to Eurasia. A general conclusion is that strike-slip faults in collision zones can have different roles. These include not only the lateral transport of crustal material demonstrated in Turkey, but also the partitioning of strain into shortening and strike-slip components shown by the Alborz and Zagros structures and the accommodation of crustal shortening by strike-slip faults that rotate about a vertical axis.