From Middle Jurassic heating to Neogene cooling: The thermochronological evolution of the southern Alps

Zattin, Massımılıano; Cuman, A.; Fantoni, Roberto; Martin, Silvana; Scotti, Paolo; Stefani, Cristina

doi:10.1016/j.tecto.2005.10.020

Cited by 46 publications

(62 citation statements)

References 26 publications

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“…This basin represents part of a paleogeographic domain that formed when Jurassic rifting created a series of N-S-oriented structural highs (platforms) and lows (basins), which persisted through much of the Paleogene (Bernoulli and Jenkyns, 1974;Bernoulli et al, 1979;Winterer and Bosellini, 1981). Importantly, from the Cretaceous to the middle-late Eocene, expanded deep sea sediment successions accumulated within the basins at nominally 30 • N latitude (Stefani and Grandesso, 1991;Agnini et al, 2006Agnini et al, , 2011Zattin et al, 2006). The Cicogna section consists of two lithostratigraphic units (Fig.…”

Section: The Cicogna Sectionmentioning

confidence: 99%

Stable isotope and calcareous nannofossil assemblage record of the late Paleocene and early Eocene (Cicogna section)

Agnini

Spofforth²,

Dickens

et al. 2016

Clim. Past

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Abstract. We present records of stable carbon and oxygen isotopes, CaCO 3 content, and changes in calcareous nannofossil assemblages across an 81 m thick section of upper Paleocene-lower Eocene marine sedimentary rocks now exposed along the Cicogna Stream in northeast Italy. The studied stratigraphic section represents sediment accumulation in a bathyal hemipelagic setting from approximately 57.5 to 52.2 Ma, a multi-million-year time interval characterized by perturbations in the global carbon cycle and changes in calcareous nannofossil assemblages. The bulk carbonate δ 13 C profile for the Cicogna section, once placed on a common timescale, resembles that at several other locations across the world, and includes both a long-term drop in δ 13 C and multiple short-term carbon isotope excursions (CIEs). This precise correlation of widely separated δ 13 C records in marine sequences results from temporal changes in the carbon composition of the exogenic carbon cycle. However, diagenesis has likely modified the δ 13 C record at Cicogna, an interpretation supported by variations in bulk carbonate δ 18 O, which do not conform to expectations for a primary signal. The record of CaCO 3 content reflects a combination of carbonate dilution and dissolution, as also inferred at other sites. Our detailed documentation and statistical analysis of calcareous nannofossil assemblages show major differences before, during and after the Paleocene-Eocene Thermal Maximum. Other CIEs in our lower Paleogene section do not exhibit such a distinctive change; instead, these events are sometimes characterized by variations restricted to a limited number of taxa and transient shifts in the relative abundance of primary assemblage components. Both long-lasting and short-lived modifications to calcareous nannofossil assemblages preferentially affected nannoliths or holococcoliths such as Discoaster, Fasciculithus, Rhomboaster/Tribrachiatus, Sphenolithus and Zygrhablithus, which underwent distinct variations in abundance as well as permanent evolutionary changes in terms of appearances and disappearances. By contrast, placoliths such as Coccolithus and Toweius, which represent the main component of the assemblages, were characterized by a gradual decline in abundance over time. Comparisons of detailed nannofossil assemblage records at the Cicogna section and at ODP Site 1262 support the idea that variations in the relative and absolute abundances, even some minor changes, were globally synchronous. An obvious link is through climate forcing and carbon cycling, although the linkages between variations in calcareous nannoplankton, changes in δ 13 C records and oceanography will need additional work.

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Section: The Cicogna Sectionmentioning

confidence: 99%

Stable isotope and calcareous nannofossil assemblage record of the late Paleocene and early Eocene (Cicogna section)

Agnini

Spofforth²,

Dickens

et al. 2016

Clim. Past

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“…Hejl 1997, Fügenschuh et al 1997. Cooling through the AFT annealing zone was nearly coeval along the Brenner fault (Fü-genschuh et al 1997), the central axes of the TW (Grundmann & Morteani1985;Staufenberg 1987;Most 2003), the Jaufen, Passeier and Giudicarie faults , and the Valsugana thrust system (Zattin et al 2006), arguing for orogen-scale cooling and exhumation since ca. 12 Ma.…”

Section: From Regional To Orogen-scale Exhumation and Coolingmentioning

confidence: 99%

Mapping of the post-collisional cooling history of the Eastern Alps

Lüth

Willingshofer

2008

Swiss J. Geosci.

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We present a database of geochronological data documenting the post-collisional cooling history of the Eastern Alps. This data is presented as (a) georeferenced isochrone maps based on Rb/Sr, K/Ar (biotite) and fission track (apatite, zircon) dating portraying cooling from upper greenschist/amphibolite facies metamorphism (500-600 °C) to 110 °C, and (b) as temperature maps documenting key times (25, 20, 15, 10 Ma) in the cooling history of the Eastern Alps. These cooling maps facilitate detecting of cooling patterns and cooling rates which give insight into the underlying processes governing rock exhumation and cooling on a regional scale.The compilation of available cooling-age data shows that the bulk of the Austroalpine units already cooled below 230 °C before the Paleocene. The onset of cooling of the Tauern Window (TW) was in the Oligocene-Early Miocene and was confined to the Penninic units, while in the Middle-to Late Miocene the surrounding Austroalpine units cooled together with the TW towards near surface conditions. High cooling rates (50 °C/Ma) within the TW are recorded for the temperature interval of 375-230 °C and occurred from Early Miocene in the east to Middle Miocene in the west. Fast cooling post-dates rapid, isothermal exhumation of the TW but was coeval with the climax of lateral extrusion tectonics. The cooling maps also portray the diachronous character of cooling within the TW (earlier in the east by ca. 5 Ma), which is recognized within all isotope systems considered in this study.Cooling in the western TW was controlled by activity along the Brenner normal fault as shown by gradually decreasing ages towards the Brenner Line. Cooling ages also decrease towards the E-W striking structural axis of the TW, indicating a thermal dome geometry. Both cooling trends and the timing of the highest cooling rates reveal a strong interplay between E-W extension and N-S orientated shortening during exhumation of the TW.

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“…All aforementioned authors concluded that the heat flow decreased to values of approximately 70 mW m −2 by 220 Ma. In contrast, Zattin et al (2006) suggested that heat flow remained at high values until the end of Jurassic rifting. We believe that the observations of Barth et al (1993) -a hydrothermal event in the Val di Fassa area resetting isotopic clocks at around 230-225 Ma -much better reflects the thermal evolution in our study area.…”

Section: Time-temperature Historymentioning

confidence: 93%

“…This interval of convergence was shortly interrupted by an Oligocene extensional phase recorded along the Periadriatic Line by plutonic intrusions (e.g. Adamello pluton) and dykes as well as by effusive basalts at the southwest termination of the Trento Plateau (Zattin et al, 2006). Upper Oligocene shallow-marine conglomerates (Monte Parei Fm) record uplifted source areas during ongoing or renewed continent collision in the eastern Dolomites (Cros, 1966;Mair et al, 1996).…”

Section: Basin and Carbonate-platform Developmentmentioning

confidence: 99%

“…Vitrinite reflectance data on seven sample locations were previously published (Buggisch, 1978;Schulz & Fuchs, 1991;Bielefeld, 1998; Table 2). One location was included where T max data were available that complemented the published dataset on thermal maturity (Zattin et al, 2006; Table 2). In addition to this dataset, 11 samples from Upper Permian sandstones (Gröden Fm) to Middle Triassic basinal shaly limestones (Buchenstein Fm) were analysed in this study.…”

Section: Vitrinite Reflectance and Apatite Fission-tracksmentioning

confidence: 99%

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Numerical Simulation of the Syn‐ to Post‐Depositional History of a Prograding Carbonate Platform: The Rosengarten, Middle Triassic, Dolomites, Italy

Emmerich

Tscherny

Bechstädt

et al. 2008

Analogue and Numerical Modelling of Sedimentary Systems: From Understanding to Prediction

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A combination of thermal history, numerical basin-reverse and sequence-stratigraphic forward modelling is applied to the Mesozoic outcrop analogue of the Rosengarten carbonate platform area in the Dolomites of northern Italy. This integrated multidisciplinary approach of numerical simulation quantifies the thermal, subsidence, geometrical and subsequent facies evolution of the area. Calibration data during modelling were vitrinite reflectance (VR) and apatite fission-track (FT) analyses as well as detailed outcrop studies. Vitrinite reflectance values in strata underlying the carbonate platform vary between 0.5 and 0.8% VR r ; apatites from these formations reveal cooling ages of around 165.6 Ma and track lengths of approximately 9.8 µm. This low thermal maturity combined with the FT data in apatites indicates a relatively cool (<110 • C), protracted (between 250 and 30 Ma) and shallow burial (thickness of eroded strata overlying present-day topography is <1100 m), as well as a fast exhumation from the Middle Miocene onward. Maximum temperatures are reached during the Middle/Late Triassic, when the basal heat flow was elevated owing to regional volcanic and hydrothermal activity. Local anomalies in vitrinite reflectance of up to 1.1% VR r in the immediate surroundings of the Predazzo/Monzoni volcanic centre show that its thermal influence decreased rapidly with increasing distance. The geometrical evolution of the Middle Triassic (Anisian/Ladinian) Rosengarten platform is twofold: the first stage reveals aggradation, the second progradation of the platform margin. Basin-reverse modelling results indicate that these two intervals originate from a temporal change in tectonic subsidence. Spatial variations in flexural and tectonic subsidence along the 6 km transect are insignificant due to the rigidity of the basement (up to 2500 m of Late Permian ignimbrites). During the first stage of platform evolution, high pulse-like total subsidence rates of up to 820 m Myr −1 led to aggradation, whereas the subsequent drop to 100 m Myr −1 initiated platform progradation. The short-spanned subsidence peak was linked to block movements in a strike-slip tectonic setting (Cima Bocche Anticline-Stava Line approximately 10 km southeast of the study area). Stratigraphic forward modelling quantifies the sediment volumes involved in the geometrical evolution of the platform. In order to replicate platform architecture, constant carbonate accumulation rates between 900 and 1000 m Myr −1 -increasing from periplatform environments to the slope -have to be assumed throughout the existence (approximately 5.8 Myr) of the Rosengarten. As the carbonate factory successfully keeps up with the modelled accommodation rates, it must have completely recovered from the Permian-Triassic biotic crisis during the onset of platform growth in latest Anisian times despite the low biotic diversity of the platform succession seen elsewhere in the Dolomites. Our forward modelling confirms that the main carbonate factory was situated on the slope at water dep...

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From Middle Jurassic heating to Neogene cooling: The thermochronological evolution of the southern Alps

Cited by 46 publications

References 26 publications

Stable isotope and calcareous nannofossil assemblage record of the late Paleocene and early Eocene (Cicogna section)

Stable isotope and calcareous nannofossil assemblage record of the late Paleocene and early Eocene (Cicogna section)

Mapping of the post-collisional cooling history of the Eastern Alps

Numerical Simulation of the Syn‐ to Post‐Depositional History of a Prograding Carbonate Platform: The Rosengarten, Middle Triassic, Dolomites, Italy

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