Chenaillet ophiolite

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The Chenaillet ophiolite is a 165 million year old ophiolite of the western Alps , originating from an oceanic crustal area of the Penninic . Of all the alpenophiolites, it shows the slightest metamorphic overprint and therefore enables the intensive study of an ocean floor spreading very slowly, with 2 to 4 centimeters per year .

description

The Mont Chenaillet from the west - on the right the southwest ridge, on the left the north-northwest ridge with pillow lavas

The type locality of the Chenaillet ophiolite (sometimes also known as Montgenèvre ophiolite or Montgenèvre-Chenaillet ophiolite ) is located on Mont Chenaillet in the Queyras massif of the Cottian Alps . The ophiolite, which belongs to the internal Piedmont zone of the South Penninic, lies here as a 5.5 × 4.5 kilometer ceiling floe (with a floor area of ​​25 square kilometers) on the ceiling of the Queyras ophiolite (here its heavily deformed and blue slate-embossed Lago Nero unit ) . The Queyras ophiolite shows affinities to the Bündner schists and, in contrast to the Chenaillet ophiolite, has preserved its sedimentary skin from radiolarites , ophicalcites and calcareous schists.

The ophiolite ceiling is bounded in the north by the municipalities of Montgenèvre , Claviere and Cesana Torinese , in the south by the localities of La Chau and Rif Tord (municipality of Cervières ). Inside it contains three notable peaks: Mont Chenaillet (2650 meters), Grand Charvia (2648 meters) and La Loubatière (2545 meters). The floor slab is at 1850 meters above sea level, the highest elevation of the ceiling is reached in the 2650 meter high Mont Chenaillet. The nappe is bounded or cut off at its south and north edges by two large lateral shifts - in the south by the northeast-trending Cervières fault and in the north by the likewise northeast-trending Montgenèvre fault . The two lateral shifts separate the Chenaillet ophiolite from rocks of the external Piedmont zone such as the Upper Triassic Dolomites at the 3136 meter high Mont Chaberton ( Chaberton unit ) in the north and at the 3320 meter high Pic de Rochebrune ( Rochebrune unit ) in the south. The front of the ceiling is formed by the north-south trending Gondran fault , where the underlying Lago-Nero unit is crossed in a westerly direction.

The Lago Nero unit appears as a small tectonic window within the Chenaillet ophiolite north of the 2403 meter high Col de Gimont . In turn, it is postponed on the 2,459 meter high Sommet des Anges (or Cime du Gondran) and on the 2565 meter high Sommet de Château Jouan (or Mont Janus) to the west over the external Piedmont zone (northern extension of the Rochebrune unit).

introduction

View from the summit of Mont Chenaillet to the north towards Montgenèvre and Mont Chaberton

As already mentioned, the relatively thin Chenaillet ophiolite is the only western Alpenophioilite (abbreviated WAO ) of the Liguria-Piedmont Ocean ( LPO ) that has as good as escaped the deformations and metamorphosis of the Alpine orogenesis. His Ophiolithabfolge consists of peridotites of the upper mantle , in the hecto- to kilometric, mafic Gabbrostöcke and felsic courses during Calloviums had invaded. The thus caused thermal weakening of the oceanic crust region led to shearing ( detachments ) in the hanging wall of the intrusions. By further advancing crustal strain oceanic core complexes are formed ( English Ocean Core Complexes or OCC ), now in the interstices of basaltic magmas penetrated and as pillow lava flew out. Normally, in the subsequent tectonic rest stage, oceanic sediments follow over the pillow lavas, but these are missing in the Chenaillet ophiolite - in contrast to the Queyras and Monviso ophiolite . The very thin sediments present are all due to internal tectonic movements and consist of reprocessed material.

Oceanic volcanism

The slowly spreading ocean floors of the Atlantic or Indian Oceans are opened up by means of tectonic exhumation of the earth's mantle and the lenticular gabbro bodies built up in it. This exhumation on the ocean floor takes place before or at the same time as the basaltic volcanoes are seated, but their spatial extent remains quite insignificant compared to the mantle surface. Two tectonic processes are responsible for the exhumation during the oceanic opening: shear with simple shear on only weakly dipping shear surfaces or rift formation with pure shear on steep faults. These two processes can also be combined, ie shallow shear followed by steep faults.

stratigraphy

The southwest ridge on Mont Chenaillet, showing the different units

Internally, the Chenaillet ophiolite is built up as follows (from hanging to lying ):

The peridotites are now mainly in the form of serpentinitized lherzolites , but serpentinitized resinburgites , pyroxenites , dunites and wehrlites also occur to a lesser extent . The mafic intrusives include troctolites , gabbros, diorites and dolerites and appear within the serpentinitized peridotites as separate bodies less than 1 kilometer in size that have been synmagmatically deformed. These bodies consist of a thin layer of layered troctolites and olivine- bearing gabbros. Diorite and dolerite occur within the gabbros as ducts or veins, their contacts can be sharp or blurred. Dolerites and basalt veins are also found in sheared gabbros and are tied to steep internal faults . Dolerites also appear in serpentinized peridotites.

Over the intrusiva follows a thin, up to 10 meters thick skin, which has emerged from reclaimed mantle serpentinites and igneous rocks. These rocks are of cataclastic origin and are interpreted by Manatschal (2011) as a shear horizon.

The sediments of the syn-extensional series begin with a 2-meter-thick, matrix- to clast -supported, polygenic ophiolite breccia , which is overlaid by graded sand and siltstones .

Massive dolerite then underlay the basaltic pillow lavas of the hanging wall. The volcanic series of the hanging wall can reach an apparent total thickness of up to 400 meters and, in addition to pillow lavas, consists of lava flows, pillow breccias and hyaloclastites . Sediments can also be present within the volcanic sequence.

Act as rarity Plagiogranite ( Alkalisyenite ) or Albitite ) serving as gears or bearings transitions occur in serpentinite, in deformed gabbros and also in igneous Brecciated the pillow lava.

Petrology

Peridotites

The black, massive lherzolites have a porphyroclastic structure and reveal a foliation of the high temperature area. They mainly belong to the spinel - and more rarely to the plagioclase - carrying type. The porphyroclasts consist of enstatite , clinopyroxene and chromium spinel . Neoblastic neoplasms such as olivine, clinopyroxene and, rarely, amphibole are preserved in places. The lherzolites are thus of a secondary nature and were created by metasomatosis from Harzburgites of the residual upper mantle (below the European continental margin) - as also revealed by trace element investigations.

Mafite

Green bottle gabbro from Mont Chenaillet

The troctolites are composed of olivine and plagioclase with a subordinate clinopyroxene . The gabbros consist of plagioclase and clinopyroxene and contain only a small amount of olivine and opaque minerals. They are pegmatitic, coarse-grained and rich in magnesium and aluminum . Locally, they show the typical structure of flaser gabbros, which were deformed along ductile shear zones and then recrystallized into mineral aggregates of augite and hornblende . As synkinematic partial melting products, veins and plugs of leuco diorites were created. In addition to the Mg-Al-rich gabbros, there are occasionally black, fine-grain ferrogabbros (rich in iron and titanium ), which are present in the gabbros as tunnels penetrating the oceanic crust and metric storage tunnels. They are made up of clinopyroxene (augite), brown amphibole , ilmenite , albitized plagioclase, apatite and titanite .

Felsite

The leukodiorites contain quartz , plagioclase, clinopyroxene and pargasitic amphibole. The albitites or alkali isenites are fine-grained to occasionally porphyry rocks with more than 90 percent albite , brown-green amphibole pseudomorphic after actinolite / tremolite , opaque minerals and accessories such as allanite , apatite and zircon . They appear in both the serpentinites and the gabbros and indicate a new section with now Felsic magmatism that followed the high-temperature ductile movements with their metamorphic changes. Occasionally they are penetrated by basaltic dolerite dikes and are therefore older than basaltic volcanism.

Cataclasites

The cataclastic gabbros of the shear horizon contain angular gabbroclasts, embedded in a matrix of albite, amphibole, chlorite and epidote . The cataclastic serpentinites consist of matrix-supported serpentine fragments .

Volcanites

The pillow lavas are basaltic in nature and show geochemical affinities to basalts of the mid-ocean ridges (MORB), in particular to the southwest Indian ridge . The homogeneous structure of the basalts is microlithic, skeletal, spherulitic and only rarely porphyry. It becomes blistered at the top of the pillow. Their mineral structure consists of albitized plagioclase, augite and pseudomorphic olivine and magnetite . The dark dolerites differ from the basalts in their fine-grain Intersertal structure ( grain size 0.1 to 2 millimeters). They indicate areas of increased heat flow , but nevertheless change very quickly into basalts.

Sediments

The sediments are ophicarbonates consisting of peridotite clasts in the centimeter to decimeter range, which are cemented by a network of calcite veins.

Structural internal structure

Pillow lavas on Mont Chenaillet

An examination of the volcanic rocks (pillow lavas, etc.) reveals two types of structure. The most common are conical structures made of tubes and cushions that emerge around a central conveyor passage. Tongue-shaped structures made of tubes and pillows appear less common. The internal structure of the two types indicates that they were built on a slope that was being formed. The topographically highest volcanic structures are systematically always the youngest.

Organizationally, two arrangements can also be distinguished - a staircase and a crest arrangement on often very steep slopes with an extension of hundreds of square meters to several square kilometers. The staircase arrangements are older than the comb arrangements. They consist of tongues that are nourished at the base of the respective stages by crevice injections. The ridge arrangements are built up from volcanic cones that lie over intersecting fractures. The latter and related secondary fractures served as magmatic conveying channels. The fractures often run pseudo-symmetrically to ridges of the terrain, which are occupied by the most recent buildings.

The total thickness of the volcanic structures does not exceed 50 meters. They nestle against the underlying coat that emerges between the staircase and comb arrangements. The mantle foundation is generally arched in a north-north-west-south-south-east direction (with an east-north-east trending axis direction), but is also overprinted by secondary foundations, which develop their strongest amplitude under significant composite volcanoes. These bulges were associated with the eruptive activity, but can also be seen in areas with minimal volcanic structures. Furthermore, a general rise of the mantle foundation to the west-south-west can be observed.

The relatively thin, less than 50 meters thick gabbros form elongated bodies, which also follow or trace the curvature of the mantle foundation in a meridional direction. Occasionally they form the basis of some rare volcanic structures. In the west of the ophiolite cover, their exposure had clearly preceded the placement of the volcanoes. In the east, however, their exhumation took place synchronously with the eruptive activity that was progressing on the lateral edges of the mantle bulge.

The thin tectonic breccia horizons that lie on top of both the serpentinized mantle and the gabbros can be assigned to detachments. They uncovered the base of the volcanic structures on the ocean floor, which in turn enabled a better morphological characterization of the generally vaulted (and undulating in detail) mantle foundation.

Metamorphosis and deformation

The Chenaillet ophiolite was only slightly tectonically stressed and metamorphosed within the alpine nappes during the compression stage. The metamorphic overprinting of the mafic rocks (gabbros and pillow lavas) is mainly due to hydrothermal processes within the oceanic crust. It reached the conditions of the prehnite pumpellyite up to the green slate facies and shows itself in the new formation of the minerals albite, prehnite, pumpellyite , actinolite and epidote. From this it can be concluded that the Chenaillet ophiolite, in contrast to the underlying Lago-Nero unit and most of the other alpine ophiolites, was not subducted . Rather, it was pushed over to the proximal European continental margin together with the Briançonnais units . Hence the low alpine stress and the excellent maintenance of oceanic contact conditions within the Chenaillet ophiolite.

In the cushion lavas, the ophitically intergrown minerals clinopyroxene, plagioclase and titanomagnetite were partially replaced by chlorite , albite and titanite, respectively. In more porphyry basalts, olivine phenocrystals were completely chloritized and plagioclase phenocrystals were partially displaced by albite and chlorite. The minerals epidote, albite, chlorite, prehnite, pumpellyite, pyrite , calcite and quartz grew again in hydrothermal veins .

The effects of the hydrothermal, crust-internal metamorphosis can also be observed in the gabbros - for example, igneous pyroxene phenocrystals have been converted into black amphiboles. Coarse-grained gabbros also occasionally contain angular inclusions of amphibolites . These are metagabbros that had been metamorphosed below the back and then incorporated into the gabbros - which in turn were hydrothermally changed. The explanation for this lies in the slowly spreading backs, which show only a small and episodic magma production. The oceanic crust is not continuous on them and the gabbro bodies only take place in them in stages. Thus, the associated heat supply is sporadic and locally limited. The resulting metamorphosis is therefore not a generally continuous process, but the result of selective events.

The current green slate facies in the metagabbros is the end product of thermal cooling on the surface of the oceanic lithosphere at a more or less constant pressure of 0.2 gigapascals - starting from the granulite facies through the amphibolite facies to the green slate facies. This can be observed very well in the originally igneous clinopyroxene. A recrystallizate of fine-grained clinopyroxene with an interstitial brown hornblende appears in the granular facies. If the deformation is somewhat lower, a symplectite of clinopyroxene and brown hornblende is created instead . With entry into the amphibolite facies, green hornblende forms instead of brown (brown hornblende is rich in titanium), and at the transition to the green slate facies finally changes into a mixture of actinolite, chlorite and epidote. The prehnite-pumpellyite facies are manifested by black plagioclase, which is actually a fine-grained aggregate of pumpellyite, chlorite and albite. Olivine becomes unstable at the border between the amphibolite and green slate facies and, according to the reaction olivine + orthopyroxene + plagioclase + water, transforms into tremolite surrounded by a corona structure made of chlorite.

Age

Age determinations carried out to date on the Chenaillet ophiolite have yielded results that vary widely and lie between 198 and 142 million years. More recent work, however, limits this period, which is unusually long for oceanic sequences and lasts around 55 million years, to the 11 million year span 166 to 155 million years. For example, troctolite and albitite dikes could be dated 165 ± 1 million years ago. The leucodiorites in turn lasted 156 ± 3 million years. Costa and Caby (2001) found that the albitites were only 148 ± 2 million years old.

geochemistry

As geochemical studies suggest, the serpentinized peridotites underlying the Liguria-Piedmont Ocean are likely to originate mainly from subcontinental mantle rocks. Microstructurally, they can be divided into two types:

  • granular to porphyroclastic spinel peridotites with beginning recrystallization of plagioclase
  • granular to porphyroclastic peridotites with rich granoblastic plagioclase aggregates and interstitial, partly deformed mantle minerals of the spinel facies.

The rocks of the first type are enriched (fertile) lherzolites rich in clinopyroxene, depleted clinopyroxene poor peridotites occur only to a minor extent. The second type, to which the Chenaillet ophiolite belongs, generally consists of abyssal peridotites that are poor in clinopyroxene. However, enriched peridotites can also appear in it.

The geochemical composition of the igneous rocks is variable and ranges from ultramafic accumulations to highly differentiated plagiogranites. They represent the crystallizate of a typical MORB parent magma, which went through a tholeiitic fractionation process at low pressures.

Cumulative processes played an important role in the genesis of gabbros. Their pattern of rare earth elements (English Rare Earth Elements or REE ) is controlled by the main cumulus mineral phases. The crystallization sequence olivine → plagioclase → clinopyroxene can be observed - with simultaneous covariation of the forsterite content in olivine and anorthite content in plagioclase. Clinopyroxenes in primitive accumulates show a depletion of light (LREE) and flat medium (MREE) to heavy rare earths (HREE). The neodymium signature with ε Nd (T)> +8 of the gabbros of the Chenaillet ophiolite resembles Gabbro's mid-ocean ridge and therefore suggests that their magma came from a depleted mantle source and did not experience any continental contamination. A modeling of the rare earth data for gabbros and leukodiorites supports the hypothesis that the dioritic magmas were formed by low partial melting (≤ 5%) of the surrounding gabros, which occurred under high-temperature shear.

In the case of the volcanic rocks (pillow lavas), petrological and geochemical investigations could clearly demonstrate their tholeiitic character with N-MORB affinity.

meaning

The importance of the Chenaillet ophiolite lies in its completely unexpected and amazing degree of preservation. His volcanic series in particular is practically undisturbed and allows us a direct view of a fossil, slowly spreading ocean floor. It can therefore be assumed that this section of the ocean floor was covered by a considerable layer of sediment, which protected it from the erosion of the alpine glaciations. The Chenaillet Ophiolite has all the characteristics for a section in an internal rift - as can currently be observed on the Mid-Atlantic Ridge . On closer examination of the dimensions, the topography, the morphology and the spatial organization of the submarine volcanic structures, the analogy of an abyssal volcanic hilly landscape comes to the fore. This conclusion is reinforced by the presence of serpentinitized mantle rocks on both sides of the volcanic hill zone - typical of slowly spreading oceanic axes.

In the Chenaillet ophiolite, only the uppermost section of the oceanic crust can be seen and there are no fresh peridotites. Its shallow nature is further confirmed by the absence of any peridotite inclusions in the serpentinites. Since it belongs to the slowly spreading heterogeneous crust type, it differs fundamentally from the classic Penrose ophiolite model, which is realized, for example, in the Semail ophiolite in Oman or in the Troodos ophiolite in Cyprus . In the case of rapidly spreading Penrose ophiolites, the Moho lies at the petrological transition from peridotites to stratified gabbros, at a depth of about 6 kilometers and a seismic speed v p of 8 km / s. In the case of heterogeneous ophiolites, the MOHO can only be determined with the onset of serpentinization (serpentinization front in the peridotites), which takes place at a depth of around 5 kilometers.

In conclusion, it can be stated that no real oceanic lithosphere can be found anywhere in the Alps - with the possible exception of the Monte Maggiore ophiolite in Corsica , which, however, also lacks the deck sediments. All ophiolites of the Alps rather stem from the transition region continent-ocean ( English Ocean Continent Transition or abbreviated OCT ), such as the Tasna- or Platta-ophiolite . The Chenaillet ophiolite is the only alpine ophiolite that contains real oceanic crust and can therefore actually be viewed as an embryonic ocean. Its ages are generally 5 to 10 million years younger than other magmatites of the Alpine OCT range. With a spreading rate of 10 to 20 millimeters per year - typical for magma-poor systems ( MP-OCT - magma-poor ocean-continent transition ) - the Chenaillet ophiolite is 50 to 100 kilometers east of the edge of the alpine rift .

Individual evidence

  1. ↑ a b Xian Hua Li, Michel Faure, Wei Lin and Gianreto Manatschal: New isotopic constraints on age and magma genesis of an embryonic oceanic crust: The Chenaillet Ophiolite in the Western Alps . In: Lithos . tape 160–161 , 2013, pp. 283-291 .
  2. ^ R. Polino and M. Lemoine: Détritisme mixte d'origine continental et océanique dans les sédiments jurassico-crétacés supra-ophiolitiques de la Téthys Ligure: la série du Lago Nero (Alpes Occidentales franco-italiennes) . In: Comptes Rendus Académie Sciences, Paris . 298, II, 1984, pp. 359-364 .
  3. ↑ JC Barfety include: Carte géologique de France (1/50 000), feuille Briançon (823) . BRGM, Orléans 1996.
  4. ↑ a b J. Bertrand, V. Dietrich, P. Nievergelt and M. Vuagnat: Comparative major and trace element geochemistry of gabbroic and volcanic rock sequences, Montgenèvre ophiolite, western Alps . In: Swiss mineralogical and petrographic messages . tape 67 , 1987, pp. 147-169 .
  5. ↑ a b Gianreto Manatschal, Daniel Sauter, Anne Marie Karpoff, Emmanuel Masini, Geoffroy Mohn and Yves Lagabrielle: The Chenaillet Ophiolite in the French / Italian Alps: an ancient analogue for an Oceanic Core Complex? In: Lithos . tape 124 , 2011, pp. 169-184 .
  6. ^ M. Cannat: Emplacement of Mantle Rocks in the seafloor at Mid-Ocean Ridges . In: Journal Geophysical Research . 98, n ° B3, 1993, p. 4163-4172 .
  7. ^ JE Snow, HJ Dick, E. Hellebrand, A. Büchl, A. von der Handt, C. Langmuir and P. Michael: Mantle peridotites of Gakkel Ridge, Artic Ocean . In: Fourth International Workshop on Orogenic Lherzolites and Mantle Processes, Aug. 26 - Sept. 3, 2002, extended abstract . 2002, p. 146-147 .
  8. ^ RB Whitmarsh, G. Manatschal and TA Minshull: Evolution of magma-poor continental margins from rifting to seafloor spreading . In: Nature . tape 413 , 2001, p. 150-154 .
  9. ↑ Y. Lagabrielle, D. Bideau, M. Cannat, JA Karson and C. Mevel C .: ultramafic Mafic Plutonic rock Suites Exposed Along the Mid-Atlantic Ridge (10 ° N-30 ° N). Symmetrical-Asymmetrical Distribution and Implications for Seafloor Spreading Processes . In: Faulting and Magmatism at Mid-Ocean Ridges, WR Buck, PT Delaney, JA Karson and Y. Lagabrielle (Eds), Geophysical monograph . tape 106 , 1998, pp. 153-176 .
  10. ↑ C. Mével, R. Caby and JR Kienast: Amphibolite facies conditions in the oceanic crust: example of amphibolized flaser-gabbro and amphibolites from the Chenaillet ophiolite massif (Hautes Alpes, France) . In: Earth and Planetary Science Letters . tape 39 , 1978, p. 98-108 .
  11. ↑ a b F. Chalot-Prat, J. Ganne and A. Lombard: No significant element transfer from the oceanic plate to the mantle wedge during subduction and exhumation of the Tethys Ocean (western Alps) . In: Lithos . tape 69 , 2003, p. 69-103 , doi : 10.1016 / S0024-4937 (03) 00047-1 .
  12. ^ R. Caby: Plastic Deformation of Gabbros in a Slowspreading Mesozoic Ridge: Example of the Mongenèvre Ophiolite. Western Alps . In: RLM Vissers and A. Nicolas (Eds), Mantle and Lower Crust Exposed in Oceanic Ridges and in Ophiolites . Kluwer Academic Publishers, 1995, p. 123-145 .
  13. ^ A b c S. Costa and R. Caby: Evolution of the Ligurian Tethys in the Western Alps: Sm / Nd and U / Pb geochronology and rare-earth element geochemistry of the Montgenève ophiolite (France) . In: Chemical Geology . tape 175 , 2001, p. 449-466 .
  14. ↑ a b Françoise Chalot-Prat, Eric Coco and Pierre-Yves Bourlier: L'you ophiolite Chenaillet (Montgenèvre, Alpes francoitaliennes) témoin d'un segment de ride volcanique axial d'un océan à croissance lente . 2006, doi : 10.13140 / RG.2.1.2171.8882 .
  15. ↑ a b Françoise Chalot-Prat: An undeformed ophiolite in the Alps: field and geochemical Evidences for a link between volcanism and shallow plate tectonic processes . In: GR Foulger, JH Natland, DC Presnall and DL Anderson, eds, Plates Plumes & Paradigms, Geological Society of America, Special Paper . tape 388 , 2005, p. 751-780 .
  16. ^ R. Lafay, Lukas Baumgartner, S. Schwartz, S. Picazo, G. Montes-Hernandez and T. Vennemann: Petrologic and stable isotopic studies of a fossil hydrothermal system in ultramafic environment (Chenaillet ophicalcites, Western Alps, France): processes of carbonate cementation . In: Lithos . tape 294–295 , 2017, pp. 319-338 .
  17. ↑ AD Lewis and JD Smewing: The Montgenèvre ophiolite (Hautes-Alpes, France): metamorphism and trace element geochemistry of the volcanic sequence . In: Chemical Geology . tape 28 , 1980, pp. 291-306 .
  18. ^ E. Rampone and GB Piccardo: The ophiolite-oceanic lithosphere analogue: new insights from the Northern Apennines (Italy) . In: Y. Dilek et al., Ophiolites and Oceanic Crust: New Insights from Field Studies and the Ocean Drilling Program (Ed.): Geological Society of America, Special Papers . tape 349 , 2000, pp. 21-34 .
  19. ↑ L. Desmurs, O. Müntener and G. Manatschal: Onset of magmatic accretion within magma-poor passive margin: a case study from the Err-Platta ocean-continent transition, Eastern Switzerland . In: Contributions to Mineralogy and Petrology . tape 144 , 2002, pp. 365 .
  20. ↑ M. Bill, T. Nägler and H. Masson: Major, minor and trace element, Sm-Nd and Sr isotope composition of mafic rocks from the earliest oceanic crust of the Alpine Tethys . In: Swiss mineralogical and petrographic messages . tape 80 , 2000, pp. 131-146 .
  21. ^ Christian Nicollet: Mais où est donc le Moho au Chenaillet? In: Bulletin de l'APBG . 2017, p. 133-140 .
  22. ^ C. Mével: Serpentinization of abyssal peridotites at mid-ocean ridges . In: Comptes Rendus Geosciences . 2003.
  23. ^ E. Rampone: Mantle dynamics during Permo-Mesozoic extension of the Europe-Adria lithosphere: insights from the Ligurian ophiolites . In: Periodico di Mineralogia . tape 73 , 2004, pp. 215-230 .
  24. ↑ Gianreto Manatschal and Othmar Müntener: A type sequence across an ancient magma-poor ocean-continent transition: The Example of the western Alpine Tethys ophiolites . In: Tectonophysics . 2008, doi : 10.1016 / j.tecto.2008.07.021 .