Sedimentation und Diagenese einer absinkenden Karbonatplattform: Rhät und Lias des Brünnstein-Auerbach-Gebietes, Bayerische Kalkalpen

Schott, Michael

doi:10.1007/bf02536658

Cited by 13 publications

(2 citation statements)

References 19 publications

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“…The Rhaetian microfacies found offshore Australia and their distribution are similar in part to those described in Central Europe (Piller, 1981;Schott, 1983). The calcispongetabulozoan facies encountered in members A and C resemble some Steinplatte mound facies described by Stanton and Flügel (1989).…”

Section: Carbonate Sedimentologysupporting

confidence: 65%

Upper Triassic (Rhaetian) Sequences of the Australian Northwest Shelf Recovered on Leg 122: Sea-Level Changes, Tethyan Rifting, and Overprint of Indo-Australian Breakup

Dumont¹

1992

Proceedings of the Ocean Drilling Program

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During Leg 122, Upper Triassic shallow-marine sequences capped by an erosional post-rift unconformity with a 80-m.y. sedimentary gap were recovered in the northern part of the Exmouth marginal plateau (Sites 759-761 and 764). The continent/ocean boundary is located only a few kilometers north of the northernmost site (Hole 764B). The components and microfacies of the most recent sediments below the post-rift unconformity (Rhaetian; about 200 samples) were analyzed. These sediments were found in two sites about 20 km apart (Holes 761C and 764B). Based on microfacies analysis and chemical logs, a correlation between these two sites is proposed. It is suggested that the uppermost Rhaetian beds at Site 764 do not exist at Site 761 (later erosion), and that the part existing in both holes (about 170 m) is only 5% thicker at Site 764. Rhaetian tilting along a north-south direction was thus insignificant (0.02°). The Rhaetian series are composed of two shallowing-upward sequences which correspond to third-order depositional sequences (sensu Haq et al., 1987). The lack of evidence for Rhaetian syn-sedimentary tectonics in the study area, and the similarities between the northwestern Australian sedimentary sequences and the European series, indicate that global eustasy has played a major role during the Rhaetian. The analysis of Rhaetian beds, which were deposited upon a rather stable platform, and the geometry of underlying Triassic beds, do not document any causal link between the Late Triassic rifting and the breakup in the nearby Argo Abyssal Plain 80 m.y. later. This breakup is probably more related to the Neocomian separation between India and Australia, and cuts obliquely through the rim of marginal plateaus of the older Tethyan margin. The geodynamic evolution of this latter Gondwanan Tethyan margin around the Triassic-Jurassic boundary appears closely comparable to, and synchronous with, the evolution of the European margin of the Ligurian Tethys, presently outcropping in the Western Alpine nappes. 1 von Rad, U., Haq, B. U., et al., 1992. Proc. ODP, Sci. Results, 122: College Station, TX (Ocean Drilling Program).

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Section: Carbonate Sedimentologysupporting

confidence: 65%

Upper Triassic (Rhaetian) Sequences of the Australian Northwest Shelf Recovered on Leg 122: Sea-Level Changes, Tethyan Rifting, and Overprint of Indo-Australian Breakup

Dumont¹

1992

Proceedings of the Ocean Drilling Program

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“…Even at a lower level we found an intimate relationship. Comparable to the Rhaetian of the Calcareous Alps (e.g., Piller, 1976;Schàfer, 1979;Schott, 1983;Senowbari-Daryan, 1980;Stanton and Flügel, 1989), several microfacies types of the Rhaetian at Sites 761 and 764 can be combined to characteristic facies units (Fig. 7).…”

Section: Facies Units and Comparison With Western Tethyan Triassic Outcrops Faciesmentioning

confidence: 99%

Microfacies, Paleoenvironment, and Facies-Dependent Carbonate Diagenesis in Upper Triassic Platform Carbonates off Northwest Australia

Röhl¹,

Rad²,

Wirsing³

1992

Proceedings of the Ocean Drilling Program

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During Ocean Drilling Program Leg 122, 900 m of Upper Triassic (Carnian to Rhaetian) sediments on the Wombat Plateau (northern Exmouth Plateau) were drilled, an ideal sequence to study eastern Tethyan shallow-water carbonate environments. The early-rift series consists of fluviodeltaic siliciclastics and shallow-marine carbonates including reefal facies.By comparison with Upper Triassic carbonates of the western Tethys (e.g., Northern Calcareous Alps), several microfacies types could be combined to characteristic facies units: biolithite-facies, different reef talus types, grapestone-oncoid facies, and calcareous algae-foraminifer detritus facies showing the reef-back-reef/fore-reef-lagoon transitions. The Carnian and Norian sequences are dominated by fluviodeltaic sediments that contain many carbonate intercalations. Their frequency and the amount of allochems increase upward in this shallowing-upward system.Overlying a global sequence boundary at the base of the Rhaetian ("Rhaetian transgression," 215 Ma), several shallowing-upward cycles from bioturbated wackestones to dolomitic algal bindstones suggest shallow subtidal to intertidal environments. Typical reef development was observed at the platform margin. The limestone-marl alternations of the open-marine shelf grade into local bioclastic and oolitic grainstones, which are the base for the incipient carbonate buildup. Later, calcisponge patch reefs were formed which developed into coral reefs. Several cycles characterize a catch-up carbonate system ("highstand systems tract"). The reef growth ended abruptly with the second sequence boundary, coinciding with a sea-level fall followed by the eustatic latest Rhaetian sea-level rise.The carbonates were affected by strong diagenesis. Mostly late-diagenetic alteration destroyed earlier diagenetic features. However, several phases can be distinguished which were formed in meteoric-vadose, meteoric-phreatic, marine-phreatic, and burial-diagenetic environments.The diagenetic successions of the Rhaetian carbonates in Leg 122 suggest that the locally uplifted Wombat Plateau horst was subaerially eroded, probably during the Callovian-Oxfordian.

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Upper triassic tethyan carbonates off northwest Australia (Wombat Plateau, ODP leg 122)

Röhl

Dumont

Rad

et al. 1991

Facies

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Sedimentation und Diagenese einer absinkenden Karbonatplattform: Rhät und Lias des Brünnstein-Auerbach-Gebietes, Bayerische Kalkalpen

Cited by 13 publications

References 19 publications

Upper Triassic (Rhaetian) Sequences of the Australian Northwest Shelf Recovered on Leg 122: Sea-Level Changes, Tethyan Rifting, and Overprint of Indo-Australian Breakup

Upper Triassic (Rhaetian) Sequences of the Australian Northwest Shelf Recovered on Leg 122: Sea-Level Changes, Tethyan Rifting, and Overprint of Indo-Australian Breakup

Microfacies, Paleoenvironment, and Facies-Dependent Carbonate Diagenesis in Upper Triassic Platform Carbonates off Northwest Australia

Upper triassic tethyan carbonates off northwest Australia (Wombat Plateau, ODP leg 122)

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