The 3D crustal structure of the Alps of eastern Switzerland and western Austria interpreted from a network of deep-seismic profiles

Hitz, L.

doi:10.1016/0040-1951(95)00025-i

Cited by 18 publications

(12 citation statements)

References 23 publications

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“…3), most faults dip steeply close to the surface, particularly in the inner (north‐east) part of the massif where back‐thrust structures are observed (Fry, 1989). Compared with the northern ECM (Ménard, 1988; Guellec et al ., 1990; Hitz and Pfiffner, 1994), it is suggested here that the fault dip progressively decreases at depth below the Argentera, such that the faults would branch into a major shear zone at the top of the lower crust. In our interpretation, the deepest part of the Argentera upper crust is shifted to the NE relative to the topographic crest, consistent with the crustal model calculated by Calais et al .…”

Section: Geological Outline Of the Argentera Massifmentioning

confidence: 77%

“…Schmid et al ., 1996). From balanced cross‐sections at crustal scale, shortening of the external European upper crust was evaluated at about 30 km and 50 km in the Belledonne and Mont Blanc transects, respectively (Ménard and Thouvenot, 1987; Sommaruga, 1997), while Hitz and Pfiffner (1994) suggest a 25‐km shortening for the Aar massif. In the Argentera case, Lickorish and Ford (1998) provide an estimate of c .…”

Section: Discussionmentioning

confidence: 99%

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Apatite fission track analysis in the Argentera massif: evidence of contrasting denudation rates in the External Crystalline Massifs of the Western Alps

et al. 2000

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Apatite fission track dating from a central transect in the Argentera massif (southernmost External Crystalline Massif = ECM) yielded ages between 8.05 + 0.6 and 2.4 + 0.2 Myr, with a positive age/altitude correlation above 3 Ma, 1200 m. Recognising a thermal peak at c. 2508C, 33 Ma, based on stratigraphic, metamorphic and 39 Ar/ 40 Ar data, the present results suggest a slow cooling rate (8±58C) for the Argentera massif during the Oligocene±early Pliocene. This rate compares with that from the Pelvoux massif, but contrasts with those observed in the northern ECM (Mont-Blanc and Aar: up to 148C Myr 71 ) for the same time interval. This can be related to the different location of the ECM within the collided European margin. At about 3±4 Ma, the denudation rate would have increased up to c. 1 mm yr 71 in the Argentera massif, reaching the same value as in the Belledonne and northern ECM, likely a consequence of Penninic thrust inversion.

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Section: Geological Outline Of the Argentera Massifmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Apatite fission track analysis in the Argentera massif: evidence of contrasting denudation rates in the External Crystalline Massifs of the Western Alps

et al. 2000

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“…The TALP consists of a stack of subhorizontal to gently south dipping nappe that abruptly steepens and becomes overturned north of the Periadriatic Fault (Figure d). Further north, the only thick‐skinned type of deformation of the nappe stack is a low‐amplitude and large‐wavelength antiform that forms the Engadine Window (Figure d), inferred to accommodate 10–12 km of shortening [ Hitz , ]. Recent investigations suggest that the Subalpine Molasse thrust belt, in the area of the Engadine section, was affected by an Oligocene‐Miocene shortening of ~30 km [ Ortner et al ., ].…”

Section: Cross Sections Exhumation Level and Collisional Shorteningmentioning

confidence: 99%

Relating orogen width to shortening, erosion, and exhumation during Alpine collision

et al. 2015

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We investigate along-strike width changes of the thickened, accreted lower plate (TALP) in the Central and in the Eastern Alps. We set the width of the TALP in relation to the inferred amount of collisional shortening and exhumation along six orogen-scale cross sections. Taking the present-day, along-strike gradients in the amount of collisional shortening to represent the temporal evolution of the collisional wedge, it may be concluded that the cross-sectional area of the TALP diminishes during ongoing shortening, indicating that the erosional flux outpaced the accretionary flux. Higher amounts of collisional shortening systematically coincide with smaller widths of the TALP and dramatic increases of the reconstructed eroded rock column. Higher amounts of shortening also coincide with larger amplitudes of orogen-scale, upright folds, with higher exhumation and with higher exhumation rates. Hence, erosion did play a major role in reducing by >30 km the vertical crustal thickness in order to accommodate and allow shortening by folding. Long-term climate differences cannot explain alternating changes of width by a factor of almost 2 along straight segments of the orogen on length scales less than 200 km, as observed from the western Central Alps to the easternmost Eastern Alps. Sedimentary or paleontological evidences supporting such paleo-climatic differences are lacking, suggesting that erosional processes did not directly control the width of the orogen.

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“…This is due to the wide range of minerals and polymineralic rocks which have not been tested, uncertainty of the conditions in the crust, and processes such as cataclastic flow, frictional sliding behavior, and stress corrosion cracking that are not fully understood. Nevertheless, the general pattern of mechanical layering shown by strength profiles is probably qualitatively correct based on, for example, the correlation of strength profiles with the foci of earthquakes in convergent settings [ Cloetingh and Banda , 1992; Zeyen and Fernández , 1994; Hitz , 1995; Okaya et al , 1996]. For simplicity, wet rheologies are chosen for the entire lithosphere due to the large reduction of plastic yield strength by even trace amounts of water.…”

Section: Mechanical Layering Of the Lithospherementioning

confidence: 99%

Syncollisional delamination and tectonic wedge development in convergent orogens

Moore¹,

Wiltschko

2004

Tectonics

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Delamination of the lower crust and lithospheric mantle has occurred in several convergent orogens, most notably the Alps and Pyrenees. Some workers suggest that the process is mechanically similar to tectonic wedging and triangle‐zone development, and dependent on the pattern of mechanical layering. A search of over 35 orogens that have been explored by geophysical techniques showed that no correlation exists between crustal composition and delamination. Delamination of passive subducting plate margins is more common than that of tectonically and/or volcanically active overriding margins. Estimates show that the lithospheric mantle of cool passive margins may contain greater net negatively buoyant mass than warmer active margins. The top of the lower lithospheric layer containing the greatest net negatively buoyant mass is aligned with a weak zone near the Moho. Passive margin lithosphere thus has a greater tendency to delaminate during a collisional event than active margin lithosphere. For delamination to initiate above the Moho, the lower crust must be subducted or depressed to allow for exposure to eclogite grade conditions. Transformation of the mafic lower crust to mafic eclogite also creates a likely delamination horizon above a lower lithospheric layer containing net negatively buoyant mass aligned with a weak zone in the lithosphere. In contrast to the stratigraphic delamination that is key to the development of small‐scale wedge structures, syncollisional delamination is likely to occur in response to an increase in the lateral tectonic stress on a weak horizon already stressed by net negatively buoyant mass in the lower lithosphere.

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The 3D crustal structure of the Alps of eastern Switzerland and western Austria interpreted from a network of deep-seismic profiles

Cited by 18 publications

References 23 publications

Apatite fission track analysis in the Argentera massif: evidence of contrasting denudation rates in the External Crystalline Massifs of the Western Alps

Apatite fission track analysis in the Argentera massif: evidence of contrasting denudation rates in the External Crystalline Massifs of the Western Alps

Relating orogen width to shortening, erosion, and exhumation during Alpine collision

Syncollisional delamination and tectonic wedge development in convergent orogens

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