Structural analysis along 24 cross sections crosscutting several windows in the central Hellenides provides the sense of nappe movements as well as the location of destroyed oceans lying between the Apulian and Eurasian continents from the Mesozoic. Orogeny took place in two phases: The first phase, “the Eo‐Hellenic” phase, was initiated by convergence of the Apulian and Pelagonian plates with west directed subduction and closure of the Pindos Ocean. Late Jurassic obduction of oceanic lithosphere over the western margin of the Pelagonian plate was followed by footwall imbrication, mylonites and sheath folds. During the late Cretaceous, uplift was associated with ductile normal faulting at depth and tectonic unroofing at shallow crustal levels. The second phase, “the Meso‐Hellenic” phase, comprised the closure of the Ambelakia Ocean at the eastern margin of the Pelagonian plate and continental subduction along the eastern margin of the Apulian plate. West directed subduction of the Ambelakia Ocean was associated with eastward directed ductile thrusting, folding and blueschist metamorphism. Blueschist formed within a simple duplex structure at depth and was subsequently overthrusted in the late Eocene onto the Olympos microcontinent, which acted as a major obstacle to the eastward directed nappe movements. Up to 150‐m‐thick cataclasites, kink folds and a spaced cleavage were formed during the late stage of the continental collision. “A subduction” along the eastern margin of the Apulian plate caused kink folding and reimbrication of the western parts of the Pelagonian basement. Since the Oligocene, the overthickened crust collapsed by means of low‐angle normal faults.

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The widespread Triassic volcanic rocks of Greece, dismembered during the Hellenide orogeny, are used to interpret the nature of Triassic rifting. Four assemblages of volcanic rocks are distinguished on geochemical criteria: (1) a predominant subalkaline basalt-andesite-dacite series with a high proportion of pyroclastic rocks; (2) minor shoshonites; (3) alkali basalt and (4) MORB. The stratigraphic and palaeogeographic distribution of these rock types is synthesized. New Pb and Nd isotopic data are used to discriminate between hypotheses suggesting that either subduction or extension was responsible for the Triassic volcanism. In the subalkaline basalt assemblage, ε Nd is negative with depleted mantle model ages > 1.5 Ga. Pb isotopic compositions are mostly close to the very distinctive compositional field of Cenozoic extensional rocks of the Aegean area, with very high 207 Pb/ 204 Pb for relatively low 206 Pb/ 204 Pb ratios. These isotopic data confirm interpretations based on trace elements that subalkaline basalts were predominantly derived from melt-depleted peridotite in the sub-continental lithospheric mantle as a result of extension. Small areas of enriched hydrous mantle partially melted to yield shoshonitic magmas. Nd and Pb isotopic compositions of the alkali basalts are quite different from those in other rock types and suggest a HIMU mantle source component derived from a small plume, which also influenced MORB compositions. Distribution of these various rock types is used to constrain palaeogeographic reconstruction of Triassic micro-continental blocks.

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Fifteen U–Pb (zircon) radiometric age determinations have been made on igneous rocks of Middle Devonian to Early Carboniferous age from the southern margin of the Magdalen basin in Cape Breton Island and northern mainland Nova Scotia. Volcanic rocks interbed with early rift-basin sedimentary rocks with some palynological biostratigraphy; dated intrusive rocks cut these sedimentary units. Our biostratigraphically constrained ages are in close agreement with the current Devonian time scale. Combined with previously published data, the age determinations show that igneous activity occurred in four pulses: Middle Devonian (390–385 Ma), early Late Devonian (375–370 Ma), latest Devonian to early Tournaisian (365–354 Ma), and late Tournaisian to early Visean (ca. 339 Ma). Middle Devonian (385–389 Ma) volcanic rocks are confined to the Guysborough Group. The Fisset Brook Formation (basalt and minor rhyolite) in the type area and elsewhere in Cape Breton Island and northern mainland Nova Scotia is Late Devonian (ca. 373 Ma), whereas the biostratigraphically distinct succession at Lowland Cove is younger (365 Ma). These Late Devonian rocks are synchronous with plutonism in the Cape Breton Highlands and the Meguma terrane. In the Cobequid Highlands, rhyolite of the Fountain Lake Group was synchronous with Horton Group deposition and with widespread granite plutons (362–358 Ma) emplaced during shear on the Cobequid fault zone. The overlying Diamond Brook Formation basalts are slightly younger (355 Ma). Late Tournaisian – early Visean mafic intrusions and minor basalt occur along the Cobequid – Chedabucto fault zone and in a belt from southern New Brunswick through Prince Edward Island to southwestern Cape Breton Island.

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