GraphicalabstractCondensed timetable of major geologic events in the East African Orogen. Opening of the Mozambique Ocean and formation of rift basins in Zambia, Malawi, Mozambique and SW Madagascar was accompanied by emplacement of anorthosite melt in extending crust. A first phase of ocean closure and accretion of terranes defines the East African Orogeny. The second orogen phase, Kuungan Orogeny, mainly affected the southern parts of east Africa and Madagascar. Both shortening events were followed by extension phases that were accompanied by emplacement of late- to post-tectonic granitoids. EGCD: Eastern Granulite–Cabo Delgado Nappe Complex; Madag: Madagascar; Ub–Us: Usagaran/Ubendian Belts; WG: Western Granulite Belt; IB (Z–M): Irumide Belt of Zambia and Malawi; IB (M): Irumide Belt of Mozambique.

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The Egersund dike swarm of SW Norway is made up of 11 basaltic dikes trending ESE-WNW. Two groups are defined: porphyritic dikes with bytownite phenocrysts of tholeiitic affinity and aphyric dikes of tholeiitic to alkaline affinity. Baddeleyite in the most alkaline dike gives a U-Pb intrusive age of 616 Ϯ 3 Ma. The swarm is parallel to the Neoproterozoic southwestern (present-day orientation) Tornquist margin of Baltica. It is coeval with the Long Range swarm of Labrador which is parallel to the southeastern proto-Appalachian margin of Laurentia. Both swarms are related to rifting that resulted in the opening of Iapetus ocean. Chronocorrelation of Neoproterozoic rift-related magmatic suites in western Baltica and eastern Laurentia suggests diachronic opening of Iapetan oceanic basins at ca. 610 Ma along the northwestern Baltoscandian margin of Baltica and at ca. 550 Ma along the proto-Appalachian margin of Laurentia and Tornquist margin of Baltica.

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[1] This paper presents results of a large multidiciplinary geological mapping project in NE Mozambique, with a focus on the structural evolution of this part of the East African Orogen (EAO). It integrates field structural studies with geophysical interpretations and presents new geochronological data. The tectonic architecture of NE Mozambique can be subdivided into five megatectonic units on the basis of lithology, structure and geochronology: unit 1, Paleoproterozoic Ponta Messuli Complex in the extreme NW corner of NE Mozambique, which represents the local NW foreland to the EAO; unit 2, a collage of Mesoproterozoic metamorphic complexes, which forms the basement to unit 3, a stack of Neoproterozoic, NW directed imbricate thrust nappes named here the ''Cabo Delgado Nappe Complex'' (CDNC); unit 4, restricted Neoproterozoic metasedimentary basins; and unit 5, two exotic Neoproterozoic granulite mé lange complexes. The units were assembled during a long and complex history of NW directed shortening, which commenced with nappe stacking and emplacement of the CDNC over the Mesoproterozoic basement terranes toward the NW foreland. It is proposed that the CDNC and the Eastern Granulites farther north in Tanzania are remnants of Neoproterozoic volcanic arcs and microcontinents formed ''outboard'' of the Mesoproterozoic continent after 596 ± 11 Ma. Field and potential field geophysical data show that the nappes were folded by regional-scale NE -SW trending folds that formed in response to a later stage of the same shortening episode and this episode gave rise to the Lurio Belt, a prominent structural feature of northern Mozambique and a key element (often as suture zone) in many Gondwana reconstructions. The Lurio Belt is here interpreted as a structure generated during folding of the CDNC during later stages of the progressive shortening event. It is, however, a repeatedly reactivated shear zone, probably at the site of an older (Mesoproterozoic?) discontinuity, with an intense pure shear deformation history. It is cored by strongly attenuated lenses of a granulitic tectonic mélange, the Ocua Complex (megatectonic unit 5) and is intruded by Late Pan-African granitoids of the Malema Suite. The compressional phase of the orogen was postdated by NW-SE directed extension. New U-Pb zircon and monazite dates show that extension was initiated at circa 540 Ma in the eastern Lurio Belt. It is argued that extension was the result of a major episode of orogenic collapse of the EAO, initiated by gravitational instabilities resulting from crustal thickening during the shortening phase.

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