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The Aegean region constitutes the overriding plate of the Africa‐Eurasia convergent plate system, in the eastern Mediterranean. To explain the fault kinematics and tectonic forces that controlled rift evolution in the Aegean area, we present fault-slip data from about 900 faults, and summarise the structural analyses of five key structural “provinces”. Five regional tectonic maps are used as the basis for a new stress map for the Aegean region and for discussions on regional geodynamics. Since the Late Miocene, the central Aegean has been affected by WNW- and NE-trending faults which transfer the motion of the Anatolian plate to the southwest, synchronous with arc-normal pull acting on the boundary of the Aegean plate. At the same time, the Hellenic Peninsula has suffered moderate extension by NW-trending grabens formed due to collapse of the Hellenic mountain chain. During intense extension in the southern Aegean in the Plio-Quaternary the arcuate shape of the Hellenic Trench was established. Arcnormal pull in the Aegean plate margin, combined with transform resistive forces along the Hellenic subduction gave rise to widespread strike-slip and oblique-normal faults in the eastern segment and moderate oblique extension in the western segment of the arc. To the north, subduction involves more continental crust and consequently the push of subduction is transmitted to the overriding plate (Hellenic Peninsula), resulting in the formation of NE-trending grabens. WNW-trending grabens in this area are considered to have propagated westward from the Aegean Sea to the Ionian Sea during Plio-Quaternary times, probably acting as pull-apart structures between stable Europe and the rapidly extending southern Aegean area. q 2001 Elsevier Science Ltd. All rights reserved.

Potassium-rich volcanic rocks of the shoshonite suite are common features of postorogenic extensional settings inboard from subduction zones. Various petrogenetic processes and tectonic settings have been proposed for their origin. Early Miocene volcanic rocks of Limnos, part of the northeast Aegean shoshonite belt, show distinctive geochemical features that allow their petrogenesis to be well constrained. The rocks are principally trachyandesites and dacites. Very strong fractionation of light and middle rare earth elements (REEs), similar to that found in adakites, is inconsistent with a mantle source, but it can be modeled by melting of meta-basalt enriched in incompatible elements. A comparison with experimental melting of metabasaltic amphibolite requires small degrees of dehydration melting of amphibole, plagioclase, clinopyroxene, and minor garnet at a temperature >950 °C. Melting was triggered by mantle-derived magma, evidenced by repetitive zoning in clinopyroxene with Cr-rich cores. Nd and Sm isotopes suggest that some of this magma was similar to lamproite found elsewhere in this shoshonite belt and some was of asthenospheric origin. The amphibolite source is inferred to be subduction-enriched metabasalt that underplated the crust during pre-Mesozoic subduction. The regional trigger for dehydration melting was upwelling of asthenosphere as a result of slab detachment. The geochemistry and radiogenic isotopes of other shoshonitic rocks in the northeastern Aegean suggest a similar origin, but with higher degrees of partial melting of base-of-crust metabasaltic amphibolite. Similar processes appear likely for shoshonitic magmatism in some postcollisional settings elsewhere.