Abstract The Caledonian Orogeny lasted from the late Cambrian to the Devonian with the main collisional events occurring during Ordovician and Silurian times. Direct evidence of the extent of this orogenic event across central Europe is limited because of the lack of outcrops of this age. The Caledonian Orogeny, together with the subsequent Variscan and Alpine orogenies, is one of a succession of major tectonic events which have defined the geological evolution of Central Europe. Thus, the present configuration and condition of the lithosphere of central Europe is the result of superimposed periods of deformation (Fig. 7.1 ). Consequently, a wide range of investigative techniques needs to be employed to unravel these events in order to determine the properties of the various elements of the Caledonides and to elucidate the evolution of the Caledonian Orogeny. Additionally, evidence of the orogeny is deeply buried beneath thick successions of younger sediments, e.g. Dutch and North German Basin, or has been reworked extensively by later events, e.g. Belgium or to the SE of the Trans-European Suture Zone. The word ‘Caledonia’, the Latin name for northern Scotland, was used by Eduard Suess (1885-1909) not only to describe a geographic region but also to indicate an orogen he termed ‘Caledonisches Gebirge’. Furthermore, Suess was the first to put his definition into a tectonic context: ‘Die in der Kaledonischen Faltungsära gebildeten Gebirge treten vor allem in Irland, Wales, Schottland und im Westteil Skandinaviens in Erscheinung’. [The mountains built during the Caledonian folding era appear particularly in Ireland,

Abstract The Caspian Sea basins of central Eurasia constitute one of the major petroleum provinces of the world. The tectonic setting and geological evolution of the South Caspian Basin remain enigmatic, particularly with respect to the generation of such significant hydrocarbon resources. Situated in the Alpine–Himalayan collisional zone, the Caspian Sea separates the locus of young continental collision in the Caucasus to the west from large-scale strike-slip faulting in the Kopeh-Dagh system to the east. Although the basin is thought to have originated in the Mesozoic, as much as 8–10 km (4.8–6 mi) of Pliocene–Pleistocene strata have accumulated, representing average depositional rates of greater than 1.5 km/m.y. (0.9 mi/m.y.) for the last 5 m.y. The presence of numerous gas-driven mud volcanoes and active oil and gas seeps suggests that hydrocarbons areforming and migrating within the basin today. Furthermore, active seismicity in the region attests that structures and associated hydrocarbon traps in the shallow section are forming now. New deep normal-incidence seismic reflection data from the South Caspian Basin provide the firstfull crustal and upper mantle image of this basin. Collected as part of a 1998 acquisition program directed by Chevron Overseas Petroleum Inc., two roughly perpendicular deep seismic reflection profiles were acquired offshore Azerbaijan (Figure 1 ). These profiles, in the vicinity of the Apsheron Ridge, are each about 70 km (43 mi) in length and are recorded to 20 s in a key area for understanding the regional tectonics of the enigmatic Caspian Basin system. The main aim of collecting deep seismic data in this important petroliferous basin was to (1) reveal the deep structure and tectonics of the Alpine–Himalanyan continent– continent collisional zone beneath the South to Central Caspian Sea; (2) portray the full Mesozoic(?)– Quaternary section of the sedimentarybasin that is inferred to be, in places, thicker than 20 km (12 mi); and (3) elucidate the thickness and nature of the crust, providing critical information for subsidence and thermal modeling, with implication for source rock maturation. These new reflection data provide a pseudo-three-dimensionalarchitecture of the South Caspian Basin in the vicinity of the Apsheron Ridge. Although recorded with standard industry parameters (airgun source of 52,111 cm 3 [3180 in. 3 ] at 1900 psi [13 MPa], 25 m [82 ft] hydrophone spacing, 5100 m [17,716 ft] streamer length, 4 ms sample rate), the two deep seismic lines provide an image of the basin down to the upper mantle depths.

The main conclusion of this paper is that some form of plate tectonics started at ca. 3.0 Ga or possibly as early as 3.1 Ga., and that, since then, plate tectonics has steadily become dominant over plumes as a mechanism of heat loss. Modern plate tectonics started at ca. 0.6 Ga. The volume history of the continental crust is one of fast Early Archean growth to generate a, probably, globally continuous crust, then a growth, probably exceeded or balanced, long-term, by crustal return to the mantle reservoir.