Polyphase tectono-magmatic evolution during mantle exhumation in an ultra-distal, magma-poor rift domain: example of the fossil Platta ophiolite, SE Switzerland

Epin, Marie‐Eva; Manatschal, Giänreto; Amman, M.; Ribes, Charlotte; Clausse, Antoine; Guffon, T.; Lescanne, Marc

doi:10.1007/s00531-019-01772-0

Cited by 28 publications

(56 citation statements)

References 49 publications

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“…This corroborates our interpretation that stage 3 (165-154 Ma) corresponds to the formation of the (hyper-)distal OCT zone, with the juxtaposition of pelagic sediments, serpentinized mantle, gabbros, basalts (e.g. Epin et al, 2019), prior break-up. The detachment of continental allochthons, such as Sesia (Figure 4; e.g.…”

Section: Opening and Extent Of The Pl Basinsupporting

confidence: 90%

“…However, extension related to final rifting in the most distal part of the margin along the ocean-continent transition (OCT) can lead to juxtaposition of extremely diverse types of rock such as slices of continental crust in contact with exhumed serpentinized mantle, pelagic sediments as well as gabbros and basalts (e.g. Florineth and Froitzheim, 1994;Froitzheim and Manatschal, 1996;Hermann and Müntener, 1996;Marroni et al, 1998;Müntener and Hermann, 2001;Ferrando et al, 2004;Manatschal et al, 2006;Manatschal and Müntener, 2009;Epin et al, 2019). Indeed, some Alpine Tethys Ophiolites are interpreted as representing https://doi.org/10.5194/se-2020-161 Preprint.…”

Section: The Piemont-liguria Basinmentioning

confidence: 99%

“…Studies of hyper-extended magma-poor type of continental margins such as in the Alps have shed light on the tectonic complexities of distal and ocean-continental transition zones, along which various types of rocks such as continental allochthons, serpentinized mantle rocks, gabbros and basalts are put in contact by major detachment faults (e.g. Florineth and Froitzheim, 1994;Müntener and Hermann, 2001;Ferrando et al, 2004;Manatschal, 2004;Manatschal and Müntener, 2009;Epin et al, 2019). These zones of inherited weakness and thermal anomalies may represent ideal candidates for localization of subduction initiation when plate motion becomes convergent (Beltrando et al, 2010;Tugend et al, 2014;Stern and Gerya, 2018;Kiss et al, 2020;Zhou et al, 2020).…”

mentioning

confidence: 99%

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Kinematics and extent of the Piemont-Liguria Basin – implications for subduction processes in the Alps

Breton¹,

Brune²,

Ustaszewski³

et al. 2020

Preprint

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Abstract. Assessing the size of a former ocean, of which only remnants are found in mountain belts, is challenging but crucial to understand subduction and exhumation processes. Here we present new constraints on the opening and width of the Piemont-Liguria (PL) Ocean, known as the Alpine Tethys together with the Valais Basin. We use a regional tectonic reconstruction of the Western Mediterranean-Alpine area, implemented into a global plate motion model with lithospheric deformation, and 2D thermo-mechanical modelling of the rifting phase to test our kinematic reconstructions for geodynamic consistency. Our model fits well with independent datasets (i.e. ages of syn-rift sediments, rift-related fault activity and mafic rocks) and shows that the PL Basin opened in four stages: (1) Rifting of the proximal continental margin in Early Jurassic (200–180 Ma), (2) Hyper-extension of the distal margin in Early-Middle Jurassic (180–165 Ma), (3) Ocean-Continent Transition (OCT) formation with mantle exhumation and MORB-type magmatism in Middle-Late Jurassic (165–154 Ma), (4) Break-up and mature oceanic spreading mostly in Late Jurassic (154–145 Ma). Spreading was slow to ultra-slow (max. 22 mm/yr, full rate) and decreased to ~ 5 mm/yr after 145 Ma while completely ceasing at about 130 Ma due to motion of Iberia relative to Europe during the opening of the North Atlantic. The final width of the PL Ocean reached a maximum of 250 km along a NW–SE transect between Europe and Adria (Ivrea). In the Cretaceous and Cenozoic, the amount of plate convergence between Adria (Ivrea) and Europe during Alpine subduction (84–35 Ma, 420 km) and collision (35–0 Ma, 260 km) largely exceeded the width of the ocean. We suggest that at least 63 % of the subducted and accreted material was highly thinned continental lithosphere and most of the Alpine Tethys Ophiolites exhumed today derived from OCT zones. Our work highlights the importance of distal rifted continental margins during subduction and exhumation processes and provides quantitative estimates for future geodynamic modelling and a better understanding of the Alpine Orogeny.

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Section: Opening and Extent Of The Pl Basinsupporting

confidence: 90%

Section: The Piemont-liguria Basinmentioning

confidence: 99%

mentioning

confidence: 99%

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Kinematics and extent of the Piemont-Liguria Basin – implications for subduction processes in the Alps

Breton¹,

Brune²,

Ustaszewski³

et al. 2020

Preprint

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“…This is consistent with Seamount B being composed of serpentinized mantle rocks and a lack of volcanic products (Tanahashi et al, 1997), as serpentinized peridotites are unlikely to hold a coherent remnant magnetization capable of producing marine magnetic anomalies (Bronner et al, 2014; Maffione et al, 2014). Based on the case study of an OCT in the Western Tethys, Epin et al (2019) offer further support that OCTs record a transition from no magmatic addition during the initial stages of mantle exhumation to increasing magmatism (shallow gabbroic intrusions and volcanism) oceanward (Müntener et al, 2010). Thus, evidence of melt impregnation at high pressure at Seamount B likely highlights the presence of melt generation during rifting.…”

Section: Discussionmentioning

confidence: 99%

Revisiting the Australian‐Antarctic Ocean‐Continent Transition Zone Using Petrological and Geophysical Characterization of Exhumed Subcontinental Mantle

McCarthy

Falloon

Sauermilch

et al. 2020

Geochem Geophys Geosyst

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The final lithospheric breakup of the Australian‐Antarctic rift system remains controversial due to sparse geological constraints on the nature of the basement along the ocean‐continent transition (OCT) zones. We present new interpretations of multichannel seismic reflection transects and new petrological data of dredged mantle rocks along the East Antarctic margin (Seamount B, offshore Terre Adélie). By combining both data sets, we show that a 50–100 km wide domain of cold and fertile subcontinental mantle was exhumed along the magma‐poor Antarctic margin. This study represents only the second locality, along with the Iberia‐Newfoundland margins, where the importance of exhumed mantle domains along OCTs can be clearly identified. The dredged peridotites preserve characteristics similar to mantle xenoliths found in syn‐ to post‐rift volcanism at the eastern end of the Australian margin (Victoria and Tasmania), indicating the exhumation of fertile subcontinental mantle during rifting between Australia and Antarctica. Seamount B represents the initial stages of exhumation of cold subcontinental lithosphere along an OCT during rifting. This thick mantle domain was likely affected by melt impregnation at high pressure (8 kbar), leading to the formation of plagioclase‐pyroxenites. The combination of continental rifted blocks, a wide domain of volcanic‐poor subcontinental mantle and (ultra‐) slow spreading is analogous to OCTs from the Jurassic Western Tethys and Iberia‐Newfoundland rifted margins. Additionally, evidence of melt stagnation at high pressure suggests that magmatism along the Australian‐Antarctic rifted margins was sufficient to form magnetic anomalies that can be used as isochrons despite their formation in lithosphere other than mature, steady‐state ocean crust.

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“…In addition, the Late Jurassic-Early Cretaceous U-Pb age (144 ± 13 Ma) in calcite from Cotschens is much younger than the intrusion of the gabbros (161 ± 1 Ma, Schaltegger et al 2002) to which hydrothermal activity is related according to Coltat et al (2019a). Even though Epin et al (2019) report the intrusion of a lone magmatic sill in the Lower Cretaceous Aptychus Limestone near Bivio, the significance of this Late Jurassic-Early Cretaceous numerical age is most uncertain. It is also much younger than the onset of deposition of the syn-to post-rift radiolarites that, however, in Graubünden is not precisely dated.…”

mentioning

confidence: 98%

Reply to ‘Discussion of oxygen isotopes in ophicalcites: an ever‐lasting controversy?’ by R. Coltat, Ph. Boulvais, Y. Branquet, M. Poujol, P. Gautier and G. Manatschal

Bernoulli

Weissert

2021

Int J Earth Sci (Geol Rundsch)

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Polyphase tectono-magmatic evolution during mantle exhumation in an ultra-distal, magma-poor rift domain: example of the fossil Platta ophiolite, SE Switzerland

Cited by 28 publications

References 49 publications

Kinematics and extent of the Piemont-Liguria Basin – implications for subduction processes in the Alps

Kinematics and extent of the Piemont-Liguria Basin – implications for subduction processes in the Alps

Revisiting the Australian‐Antarctic Ocean‐Continent Transition Zone Using Petrological and Geophysical Characterization of Exhumed Subcontinental Mantle

Reply to ‘Discussion of oxygen isotopes in ophicalcites: an ever‐lasting controversy?’ by R. Coltat, Ph. Boulvais, Y. Branquet, M. Poujol, P. Gautier and G. Manatschal

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