Structural and metamorphic evolution of a subducted passive margin: insights from the Briançonnais nappes of the Western Alps (Ubaye–Maira valleys, France–Italy)

Dana, Davide; Iaccarino, Salvatore; Schmid, Stefan M.; Petroccia, Alessandro; Michard, André

doi:10.1186/s00015-023-00445-0

Swiss Journal of Geosciences

Table 1 List of units derived from the Briançonnais s.l. paleogeographical domain in the SW Alps (see Figs. 2, 3), including their equivalents in the Guil transect located further north (second column)

From: Structural and metamorphic evolution of a subducted passive margin: insights from the Briançonnais nappes of the Western Alps (Ubaye–Maira valleys, France–Italy)

Ubaye-Maira transect	Guil transect equivalent	Pre-rift succession	Post-rift succession	Relative tectonic position
ACH Aiguille de Chambeyron–Sautron	–	Middle Triassic carbonates	UJ locally reduced, UC “calcschist” + breccias, Flysch noir	FW = Haut Rochouse, Marinet HW = Châtelet
AMA Aiguilles de Mary	–	Permian, Lower Triassic, Middle–Upper Triassic carbonates and breccia	UC “calcschist” + breccia, Flysch noir	FW = Marinet HW = Ceillac–Chiappera
CB Combe-Brémond (Acceglio type)	–	Permian, Strongly reduced Lower Triassic, Anisian–Ladinian	UJ sandy marble, UC–PC breccia and chlorite marbles	FW = Schistes Lustrés HW = Roure, Chapelue, Pointe de Rasis
CCH Ceillac–Chiappera	CCH Ceillac–Chiappera -	Middle–Upper Triassic carbonates and breccia	Middle–Upper Jurassic limestone, UC “calcschists”, Flysch noir	FW = Roure, Chapelue, Combe-Brémond
CHA Châtelet sensu stricto	–	Middle–Upper Triassic carbonate and breccia	Middle–Upper Jurassic limestones, UC “calcschist”, Flysch noir	FW = Aiguille de Chambeyron–Sautron HW = Font Sancte, Peyre Haute
CHP Chapelue	CHP Chapelue	Permian, Lower Triassic quartzite, Middle Triassic carbonates	–	FW = Pointe de Rasis, Combe-Brémond HW = Roure, Ceillac–Chiappera, Clapiere
–	CL Clapière	Norian dolostone	UJ limestone, UC calcschist	FW = Ceillac–Chiappera, Chapelue, Arvieux HW = Pic d’Assan
FS Font–Sancte	FS Font–Sancte	Middle–Upper Triassic carbonates and breccia	Middle–Upper Jurassic limestones, UC “calcschists”, Flysch noir	FW = Marinet, Aiguilles de Mary, Ceillac -Chiappera, Pic d’Assan, Agnelil, Guil HW = Peyre Haute
HR Haut Rochouse	–	Permian (rhyol. or conglom.), Lower Triassic quartzites, Middle–Upper Triassic carbonates and breccia	Middle–Upper Jurassic limestones, UC “calcschists” Flysch noir	FW = Rocca Peroni–Oserot HW = Aiguillle de Chambeyron–Sautron
MAR Marinet	GUI Nappe inférieure du Guil	Upper Carbonif. (?)-Permian (andesites or conglom.), Lower Triassic quartzite, strongly eroded Triassic carbonate	UJ reduced/lacking, UC + breccia, Flysch noir	FW = ? HW = Font-Sancte
–	PA Pic d’Assan	Middle Triassic carbonates	UJ limestones, UC “calcschists”, Flysch noir	FW = Font Sancte HW = Agnelil
PH Peyre Haute (minor klippen)	PH Peyre Haute	Carnian with gypsum and Norian « Hauptdolomit» dolostone	UJ limestones UC “calcschists” Flysch noir	FW = Guil, Font Sancte–Châtelet, Agnelil, Roche Charnière, Champcella HW = ?
–	RA Pointe da Rasis	Middle Triassic dolostones	UJ limestones, UC “calcschists” Flysch noir	FW = Roche des Clots–Péouvou HW = Chapelue
ROU Roure (Acceglio type)	–	Permian conglom., Lower Triassic quartzite	–	FW = Combe-Brémond HW = Ceillac–Chiappera
RPO Rocca Peroni–Oserot	–	Permian rhyol., Lower Triassic quartzite, Middle Triassic carbonates	MJ limestones, UC “calcschists” + breccia, Flysch noir (locally)	FW = Subbriançonnais HW = Haut Rochouse

The list is alphabetically ordered using acronyms as in Fig. 2. Note that syn-rift Rhaetian-Hettangian argillaceous limestone and breccia are present only in the Peyre-Haute unit (not listed in this table). Such syn-rift sediments are also found in the Pre-Piemonte units outside the area of Fig. 3 (Michard et al., 2022). The Cretaceous-Paleocene, pelagic detrital “calcschists” are often labeled “marbres en plaquettes”. Additional information is given in Additional file 2.
PC Paleocene, UC Upper Cretaceous to lower Paleogene, UJ Upper Jurassic, MJ Middle Jurassic, FW/HW footwall/hanging-wall units.

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