Genese et evolution comparees de deux marges continentales passives; marge iberique de l'Ocean atlantique et marge europeenne de la Tethys dans les Alpes occidentales

The Alpine Tethys rifted margins: Reconciling old and new ideas to understand the stratigraphic architecture of magma‐poor rifted margins

“…A second genetic sequence is marked by the progressive cessation of rift activity in the proximal domain, together with migration and localization into the future distal margin (De Graciansky et al ., ; Eberli, ; Bertotti et al ., ; Berra et al ., ; T3 to T5 in Fig. ).…”

“…Indeed, crustal tilted blocks and half graben basins were well‐imaged offshore Europe (De Charpal et al ., ; Montadert et al ., ) and their isostatic and stratigraphic evolution was successfully predicted by the pure shear rift model proposed by McKenzie (). These new ideas were immediately used to explain the fossil Alpine margins (De Graciansky et al ., ) and supported the idea that the Alpine Tethys resulted from a Liassic rifting event associated with the formation of fault bounded tilted blocks.…”

Constraints on the deep structure and dynamic processes beneath the Alps and adjacent regions from an analysis of gravity anomalies

“…Abundant geologic mapping of sedimentary rock in the Alps shows that those rocks were deposited on the continental margin of Europe in Mesozoic and early Tertiary time (Bourbon et af. 1976;Caron 1977;de Graciansky et al 1979;Debelmas 1974;Masson et al 1980;Tri.impy 1960Tri.impy , 1980. Subsidence of the margin was surely associated with crustal thinning, but because most of record of this subsidence is carried by rocks now folded and overthrust on top of one another, it is very difficult to determine where the old southern margin of Europe lay with respect to the part that has remained stable.…”

“…The Alps appear to be a consequence of the collision between a block of continental crust that now comprises much of Italy and the Adriatic Sea floor (Adria) with the southern margin of the European platform (Dewey et al 1973). Prior to the collision, oceanic lithosphere comprising part of the Eurasian lithosphere was underthrust beneath Adria, and then during the collision, sedimentary rock, deposited both on oceanic crust (Homewood 1983;Homewood & Caron 1982) and on the margin of the European platform (Bourbon et al 1976;Debelmas 1974;de Graciansky et al 1979;Masson, Herb & Steck 1980;Triimpy 1960, became detached from the underlying crust and was thrust onto the edge of the European Platform. The dominantly northwestward vergence of folds and thrust faults in the Alps attests to a major shearing as the European plate continued to underthrust beneath the northern margin of Italy (Milnes 1978;Ramsay, Casey & Kligfield 1983;Steck 1984), but a later phase of 'retrocharriage', with a vergence in the opposite sense is pervasive in the interior, or SE, part of the belt (Allenbach & Caron 1986;Caron 1977;Tricart 1984).…”

Instability structures, synsedimentary faults and turbidites, witnesses of a Liassic seismotectonic activity in the Dauphiné Zone (French Alps): A case example in the Lower Pliensbachian at Saint-Michel-en-Beaumont

“…1c and d), where tilted blocks settled during the Tethyan rifting ( Fig. 1a and b) (Barféty et al, 1979;de Graciansky et al, 1979;Lemoine et al, 1981;Gidon and Aprahamian, 1980;Barféty andGidon, 1983, 1984). Three regional extensional phases have been characterized, related to this rifting: (i) a first one, N-S trending and considered as a pre-rift stage, Triassic in age, (ii) a NE-SW trending extension dated of the Early Liassic and regarded as the initial rifting (Grand, 1987;Grand et al, 1987;Claudel and Dumont, 1999), and (iii) a NW-SE trending extension, corresponding to the paroxysm of the rifting, which occurred during the Late Liassic, associated to significant synsedimentary processes, such as the occurrence of the Ornon olistolithe (Barféty et al, 1979;Barféty and Gidon, 1984).…”