Late jurassic tectonics and sedimentation: breccias in the Unken syncline, central Northern Calcareous Alps

Ortner, Hugo; Ustaszewski, Michaela; Rittner, Martin

doi:10.1007/978-3-7643-9950-4_4

Cited by 3 publications

(11 citation statements)

References 41 publications

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“…In Fig. 2 the former interpretation (Ortner et al 2008) of the investigated rocks as Early Cretaceous (Valanginian-Barremian) is indicated. In contrast, our reinvestigation of some of these rocks gives evidence for the Kimmeridgian age.…”

Section: Geological Settingmentioning

confidence: 94%

“…(Darga & Schlagintweit 1991) of the southern Plassen Carbonate Platform (Lärchberg Carbonate Platform - Gawlick et al 2009), later overthrust -most probably in the latest Tithonian -above the studied Kimmeridgian resediments ( = line in Fig. 2b, formerly interpreted as the boundary between the Saalach Unit and the Tirolic Unit - Ortner et al 2008). The investigated resediments are attributed to the Sillenkopf Formation (Fig.…”

Section: Geological Settingmentioning

confidence: 97%

“…2) and belongs to the Hallstatt Mélange area of the Saalach zone (Tollmann 1985) or Saalach Fault Zone . A more detailed geological sketch map of the area was recently published by Ortner et al (2008) and for details the reader is referred to Fig. 2 in Ortner et al (2008).…”

Section: Geological Settingmentioning

confidence: 99%

“…Mandl 2000Mandl , 2013 versus strike-slip tectonics (e.g. Channell et al 1990Channell et al , 1992Frank & Schlager 2006;Ortner et al 2008) versus obduction related tectonics in the Jurassic of the Austroalpine domain (Gawlick et al 1999;Faupl & Wagreich 2000;Missoni & Gawlick 2011a,b).…”

Section: Introductionmentioning

confidence: 99%

“…For more details concerning the controversial discussion the reader is referred to the publications of Ortner et al (2008) and Missoni & Gawlick (2011a,b).…”

Section: Introductionmentioning

confidence: 99%

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Ophiolitic detritus in Kimmeridgian resedimented limestones and its provenance from an eroded obducted ophiolitic nappe stack south of the Northern Calcareous Alps (Austria)

Gawlick¹,

Aubrecht²,

Schlagintweit³

et al. 2015

Geologica Carpathica

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Abstract:The causes for the Middle to Late Jurassic tectonic processes in the Northern Calcareous Alps are still controversially discussed. There are several contrasting models for these processes, formerly designated "Jurassic gravitational tectonics". Whereas in the Dinarides or the Western Carpathians Jurassic ophiolite obduction and a Jurassic mountain building process with nappe thrusting is widely accepted, equivalent processes are still questioned for the Eastern Alps. For the Northern Calcareous Alps, an Early Cretaceous nappe thrusting process is widely favoured instead of a Jurassic one, obviously all other Jurassic features are nearly identical in the Northern Calcareous Alps, the Western Carpathians and the Dinarides. In contrast, the Jurassic basin evolutionary processes, as best documented in the Northern Calcareous Alps, were in recent times adopted to explain the Jurassic tectonic processes in the Carpathians and Dinarides. Whereas in the Western Carpathians Neotethys oceanic material is incorporated in the mélanges and in the Dinarides huge ophiolite nappes are preserved above the Jurassic basin fills and mélanges, Jurassic ophiolites or ophiolitic remains are not clearly documented in the Northern Calcareous Alps. Here we present chrome spinel analyses of ophiolitic detritic material from Kimmeridgian allodapic limestones in the central Northern Calcareous Alps. The Kimmeridgian age is proven by the occurrence of the benthic foraminifera Protopeneroplis striata and Labyrinthina mirabilis, the dasycladalean algae Salpingoporella pygmea, and the alga incertae sedis Pseudolithocodium carpathicum. From the geochemical composition the analysed spinels are pleonastes and show a dominance of Al-chromites (Fe 3+ -Cr 3+ -Al 3+ diagram). In the Mg/(Mg+ Fe 2+ ) vs. Cr/(Cr + Al) diagram they can be classified as type II ophiolites and in the TiO 2 vs. Al 2 O 3 diagram they plot into the SSZ peridotite field. All together this points to a harzburgite provenance of the analysed spinels as known from the Jurassic suprasubduction ophiolites well preserved in the Dinarides/Albanides. These data clearly indicate Late Jurassic erosion of obducted ophiolites before their final sealing by the Late Jurassic-earliest Cretaceous carbonate platform pattern.

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Section: Geological Settingmentioning

confidence: 94%

Section: Geological Settingmentioning

confidence: 97%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…For more details concerning the controversial discussion the reader is referred to the publications of Ortner et al (2008) and Missoni & Gawlick (2011a,b).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Ophiolitic detritus in Kimmeridgian resedimented limestones and its provenance from an eroded obducted ophiolitic nappe stack south of the Northern Calcareous Alps (Austria)

Gawlick¹,

Aubrecht²,

Schlagintweit³

et al. 2015

Geologica Carpathica

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Bulk inclusion micro‐zircon U–Pb geochronology: A new tool to date low‐grade metamorphism

Hollinetz

Schneider

McFarlane

et al. 2021

Journal Metamorphic Geology

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Dating low‐grade metamorphism is challenging since such rocks commonly lack suitable target minerals for acquiring pressure–temperature–time–deformation (P–T–t–d) data. Herein a new geochronological method termed ‘bulk inclusion dating’ is applied to a chloritoid‐bearing schist from the Staufen‐Höllengebirge Nappe (SHN, Austroalpine Unit, Eastern Alps, Austria) for which Cretaceous metamorphism is imprecisely constrained. Thermodynamic modelling of the phase relations and mineral chemistry predicts the stability of the equilibrium assemblage in a P–T field between 450–490℃ and 0.5–0.7 GPa, which agrees with peak temperature constraints ~490℃ derived from Raman spectroscopy of carbonaceous material. Chemical zoning of, and the zonation of inclusions within, chloritoid confirm porphyroblast growth at these conditions. High‐resolution imaging reveals thousands of minute (length: 0.1–3 µm), euhedral micro‐zircon crystals included in chloritoid porphyroblasts and in the matrix. The morphological and microstructural characteristics of micro‐zircon as well as the crystal size distributions indicate that it nucleated and grew at greenschist facies conditions most likely from a Zr‐saturated fluid. In situ laser ablation inductively coupled plasma mass spectroscopy bulk inclusion dating of metamorphic zircon in the chloritoid rim using a laser spot diameter of 120 μm yields a U–Pb age of 116.7 ± 9.1 Ma (MSWD: 1.5, n: 79). We interpret zircon precipitation and progressive coarsening coeval with chloritoid growth during prograde metamorphism and thus link the age to the late prograde part of the P–T evolution. The contribution of other U‐bearing phases (apatite, epidote, rutile) does not significantly disturb the U–Pb age. The data provide clear evidence for Early Cretaceous metamorphism in the SHN and indicates that metamorphism started at least 20 m.y. before the formation of eclogites in the Austroalpine Unit. The method introduced here allows integration between metamorphic conditions and age constraints in low‐grade metamorphic rocks and opens up new potential applications in petrochronology.

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A geological snapshot from the front of the Northern Calcareous Alps: Well Obermoos TH-1, Salzburg, Austria

Wessely¹,

Neubauer²,

Salcher³

et al. 2016

AJES

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The deep thermal well Obermoos TH-1 (total depth 2468 m, year 1990) was drilled within the Upper Cretaceous Salzburg-Reichenhall basin of the Northern Calcareous Alps at the southwestern edge of Salzburg city, Austria. The lithologic log shows c. 200 m thick Quaternary sediments of the glacially overdeepened Salzach Valley above bedrock. The Quaternary infill is underlain by c. 250 m thick, almost horizontally lying coarse clastics and marls, which belong to the Upper Cretaceous Salzburg-Reichenhall Gosau basin. From 456 m to 2468 m, a steeply dipping, more or less continuous succession from Cenomanian strata to Upper Triassic Hauptdolomit was encountered. This succession is considered being part of the Bajuvaric nappe of the central Northern Calcareous Alps, which is entirely overridden by units of the Tyrolic arc in the study area. The new data from the deep drilling provides (i) new information on depth and filling of the deeper parts of the Pleistocene valley and (ii) new insights into the complex structure of the Bajuvaric nappe. We also discuss a potential fault crossing the Salzburg-Reichenhall basin being part of the Cenozoic Innsbruck-Salzburg-Amstetten fault system. On a larger scale, the Tyrolic unit exposed in the southern margin of the Salzburg-Reichenhall basin and potentially overlying the borehole section must be the same as in the flat-laying Tyrolic nappe found in two deep drill holes, 15 km southeast and 18 km east of the City of Salzburg (Vigaun 1 and Vordersee 1).

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Late jurassic tectonics and sedimentation: breccias in the Unken syncline, central Northern Calcareous Alps

Cited by 3 publications

References 41 publications

Ophiolitic detritus in Kimmeridgian resedimented limestones and its provenance from an eroded obducted ophiolitic nappe stack south of the Northern Calcareous Alps (Austria)

Ophiolitic detritus in Kimmeridgian resedimented limestones and its provenance from an eroded obducted ophiolitic nappe stack south of the Northern Calcareous Alps (Austria)

Bulk inclusion micro‐zircon U–Pb geochronology: A new tool to date low‐grade metamorphism

A geological snapshot from the front of the Northern Calcareous Alps: Well Obermoos TH-1, Salzburg, Austria

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