On the age of the Vedrette di Ries (Rieserferner) massif and its geodynamic significance

Borsi, S.; Moro, A. Del; Sassi, Francesco; Zirpoli, G.

doi:10.1007/bf01821121

Cited by 42 publications

(21 citation statements)

References 7 publications

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“…The K/Ar-biotite cooling ages obtained excellently fit the age pattern observed in former investigations (Borsi et al 1979;Hammerschmidt 1981;Prochaska 1981). Cooling ages north of the DAV Line increase from around 17 Ma at the Rensen Pluton in the west to 27 Ma at the western end of the Rieserferner Pluton (Fig.…”

Section: New K/ar Mica and Fission-track Resultssupporting

confidence: 85%

“…This age is interpreted to reflect cooling after Cretaceous metamorphism (Stöckhert 1984). Further to the north, strongly decreasing K/Ar white-mica cooling ages overlap within error limits with Rb/Sr white-mica ages, suggesting rapid Borsi et al (1979) and K/Ar-muscovite ages from earlier investigations (see insert), and new data. Indicated are the two analysed pegmatitic rocks from the basement in the south of the DAV Line yielding an Early Jurassic age.…”

Section: New K/ar Mica and Fission-track Resultssupporting

confidence: 72%

“…13 Cooling history of the Austroalpine basement in the north of the DAV Line and direct constraints on the amount of exhumation assuming an average geothermal gradient of 28°C/km. The standard deviation of the summarised age data from this study and previous data (Borsi et al 1979;Coyle 1994;Stöckhert et al 1999) for the different exhumation paths is presented by horizontal error bars. Vertical error bars reflect uncertainties from closure temperatures of the different isotopic systems.…”

Section: Exhumation Of the Austroalpine Basementmentioning

confidence: 94%

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Cooling and exhumation of the Rieserferner Pluton (Eastern Alps, Italy/Austria)

Steenken¹,

Siegesmund²,

Heinrichs³

et al. 2002

International Journal of Earth Sciences

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The Defereggen-Antholz-Vals (DAV) Line marks the southern border of alpine greenschist facies metamorphism within the Austroalpine basement to the south of the western Tauern window. During the Oligocene sinistral-strike slip, coeval with vertical displacement, was accompanied by the syntectonic emplacement of the Rieserferner Pluton along the north side of the fault. To the north of the DAV Line Rb/Sr as well as K/Ar-biotite cooling ages continuously increase from 16 Ma at the Rensen Pluton in the west to 30 Ma at the eastern end of the Rieserferner Pluton. Similar trends are apparent from zircon and apatite fission-track data, which increase eastward from 19 to 29 Ma, and 13 to 16 Ma, respectively. Low cooling rates allow a direct transformation into exhumation rates assuming an average geothermal gradient of 28°C km -1 . The resulting exhumation rates of less than 1 mm year -1 do not affect the depth of isotherms in a geologically significant manner. Hence, variable cooling rates within the basement north of the DAV Line are a result of differential exhumation of individual blocks. High exhumation rates bracketed between the intrusion age of the Rieserferner Pluton at 31±3 Ma and the apatite partial annealing zone (PAZ) range between 0.4 and 0.6 mm year -1 , whereas final exposure takes place at reduced exhumation rates of 0.2 mm year -1 . East-side-down tilting of the block north of the DAV Line, as indicated by variations in exhumation rates, strongly affects the western part of the area studied between the Rensen and the Central Rieserferner Pluton whereas, further east, block rotation becomes less important. A total difference in exhumation of about 2.2 km corresponding to 5°tilting between the Western and Eastern Rieserferner, as indicated by K/Ar-biotite and zircon fission-track data, occurred before going through the PAZ for apatite fission-tracks. Furthermore, the significance of the cooling ages, especially for biotite, is tested by calculating a finite element approximation. Different numerical models indicate fast cooling of the intrusive melts prior to approaching the closure temperature of the K/Ar system in biotite.

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Section: New K/ar Mica and Fission-track Resultssupporting

confidence: 85%

Section: New K/ar Mica and Fission-track Resultssupporting

confidence: 72%

Section: Exhumation Of the Austroalpine Basementmentioning

confidence: 94%

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Cooling and exhumation of the Rieserferner Pluton (Eastern Alps, Italy/Austria)

Steenken¹,

Siegesmund²,

Heinrichs³

et al. 2002

International Journal of Earth Sciences

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“…In the case of the sample from the Steinernes Meer block (Table 1; Fig. 5b), the age of the euhedral crystals (33.11.5 Ma) is identical to the age of the pronounced peak of activity of the main Periadriatic magmatism in Oligocene times (~33±30 Ma; Borsi et al 1979;Blanckenburg and Davies 1995). Frisch et al (1998Frisch et al ( , 1999 and Brügel et al (2000) showed that the Periadriatic intrusive bodies presently exposed on the surface were topped by volcanic edifices in Oligocene times, which are completely eroded today.…”

Section: Zircon Fission-track Datamentioning

confidence: 64%

The Dachstein paleosurface and the Augenstein Formation in the Northern Calcareous Alps – a mosaic stone in the geomorphological evolution of the Eastern Alps

et al. 2001

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The central and eastern areas of the Northern Calcareous Alps (NCA) are characterized by remnants of the Dachstein paleosurface, which formed in Late Eocene (?) to Early Oligocene time and is preserved with limited modification on elevated karst plateaus. In Oligocene time, the Dachstein paleosurface subsided and was sealed by the Augenstein Formation, a terrestrial succession of conglomerates and sandstones, which are only preserved in small remnants on the plateaus, some in an autochthonous position. Thermochronological data suggest a maximum thickness of the Augenstein Formation of >1.3 km, possibly >2 km. The age of the Augenstein Formation is constrained by the overall geological situation as Early Oligocene to earliest Miocene. Fission track age data support an Early Oligocene age of the basal parts of the formation. The source area of the Augenstein Formation consisted predominantly of weakly metamorphic Paleozoic terrains (Greywacke Zone and equivalents) as well as the Late Carboniferous to Scythian siliciclastic base of the NCA to the south of the depositional area. To the west, the Augenstein Formation interfingered with the Tertiary deposits of the Inntal. Sedimentation of the Augenstein Formation was terminated in Early Miocene time in the course of the orogenic collapse of the Eastern Alps. The Augenstein sediments were eroded and redeposited in the foreland Molasse zone. From Pannonian times (~10 Ma) on, the NCA and the denuded Dachstein surface experienced uplift in several pulses. The Dachstein paleosurface has been preserved in areas, in which thick limestone sequences allowed subsurface erosion by cave formation and thus prevented major surface erosion.

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“…Due to sinistral shearing, contact-related andalusite porphyroblasts are transformed into s-clasts, where syndeformational growth of white mica occurs. White mica±andalusite pairs yielded a Rb±Sr microsampling age of 30.14.6 Ma (Müller et al 2000b), which is similar to the age of intrusion of the Rieserferner pluton (313 Ma; Borsi et al 1978b). Ages of fault rocks collected along various PAF-related faults (North Giudicarie, Tonale, Mauls, DAV) provide direct evidence for Oligocene deformation.…”

Section: Oligocene (32±25 Ma)mentioning

confidence: 71%