Porifera-microbialites of the Lower Liassic (Northern Calcareous ...

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82 Although sometimes difficult to evaluate, the majority of sponges from platform localities also represent predominantly disarticulated (parautochthonous?) skeletons whereas complete autochthonous communities are only preserved at slopes and ramps of the northern platform edge. But in contrast to basinal settings, the situation here seems to be controlled rather by local environmental conditions. For example, the facies at Adnet reef slope show that these paleoenvironments were characterized by episodically elevated sedimentation rate and an apparently special water regime. In this regard, the predominance of erect, tube shaped sponges could be interpreted as an adaption to higher rates of background sedimentation and to steady water currents (contour currents, sensu Böhm et al. 1999) of which a tubular species can take an advantage by the chimney effect (Krautter 1995). Concerning the faunal composition, the platform margins were also colonized by mainly lyssacinosid species. They were able to settle on softgrounds and appeared here as pioneers. Dead and partly collapsed specimens have then successively formed spicular mats that provided secondary firm-/hardgrounds for intermediate abundances of associated hexactinosid taxa that settled in between. In contrast to these sponge communities that most likely emanated from faunas of the adjacent Kössen basin (Fig. 39), the origin of non-lithistid demosponges in southern localities is rather related to the Tethys realm. Anyway, they seem to be a common faunal element only in Sinemurian to Pliensbachian red limestones that slided down towards the north into small basins that formed when parts of the carbonate platform break apart during Middle Liassic time. Fig. 39. Illustration of sponge evolution, diversification and palaeogeographical extension in the Salzburg area (Northern Calcareous Alps) during Upper Triassic and Lower Liassic time. Data about Triassic faunas obtained from Mostler (1976, 1978, 1986, 1989b).
Comparison with other Spiculites 83 7. Comparison with other Spiculites Since the highest diversity of recent Hexactinellida is known from the bathyal zone (Tabachnick, 1994), these taxa mostly elude direct observation. As a result rare Recent autochthonous sponge communities from shallow environments as well as fossil assemblages present the best possibility for extensive investigations. The preservation of fossil spiculites on drowned Triassic reefs reflect peculiar taphonomic processes that seem to be closely related to the synsedimentary environment. The same relation is also confirmed by the record of several other alpine examples of Lower Liassic spiculite/stromatactis limestones, e.g. from the Hochlerch-Silleck-Syncline / Chiemgau Alps (Mathur 1975), the Misone Limestone of the Trento Platform / Italy (Castellarin 1972; Krautter 1996), the Gozzano High at the western margin of the Lombardian Basin (Montanari 1969) or from Arzo locality at the Lugano High in the Lombardian Basin / Switzerland (Neuweiler and Bernoulli 2005). They all document biostromes or flat mounds, mostly restricted to the slopes of drowned platform areas. While spiculites formed on elevated position have previously been discussed as a model for mud mound genesis (Reitner and Neuweiler 1995) comparative studies with two other sponge communities are given here to point up the relevance of environmental conditions during spiculite formation. This is shown by spiculitic mats from the crest of Recent “Arctic Vesterisbanken Seamount” (Central Greenland Sea) and by Campanian sponge spicule- dominated sediments exposed on the top of the Albian “Murguia” Diapir (Province Alava, Basco-Cantabrian Basin, Spain, Fig. 40, 41, Engeser 1984). Throughout all localities sponge settlement was apparently controlled first by the water regime, more precisely by the nutrient supply via consistent currents. In the cold waters at Vesterisbanken these currents probably derived from a “streamlined downwelling vortex known as the Taylor column” (Henrich et al. 1992) whereas sites of temperate lattitudes (Diapir of Murguia, Steinplatte/Plattenkogel) were more likely dominated by upwelling systems or contour currents as postulated for alpine spiculites at Adnet (Böhm et al. 1999). Furthermore the faunal composition is different in all studied sites and depends on the given substrate. At Murguia (Reitner 1982, 1987), the nowadays sunken center of the diapir top exposes marls of Lower Campanian age showing the initial stage of recolonization by mainly non-lithistid Demosponges. Followed much later by a coral reef growth in the Upper Campanian Oro Member (Stackelberg 1964; Engeser 1984), the pioneer sponge fauna comprises specimens with non-rigid skeletons formed by unfused spicules the remains of their collapsed skeletons formed spiculitic mats that served as secondary substrates for hexactinosid and demosponge lithistid taxa (Pl. 21).
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Porifera-microbialites of the Lower
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Abstract In the aftermath of the Tr
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Zusammenfassung Nach dem Aussterbee
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Content 1. Introduction ...........
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Introduction 9 1. Introduction In U
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Geological Setting 11 2. Geological
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Geological Setting 13 Fig. 2. Locat
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Methods 15 3. Methods In the Rot-Gr
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Localities (Facies and Sponge Analy
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Page 31 and 32: Localities (Facies and Sponge Analy
Page 51: Localities (Facies and Sponge Analy
Page 54 and 55: 54 and ferromanganese crusts. The b
Page 56 and 57: 56 5.1.1. The Sponge Fauna of the S
Page 58 and 59: 58 Skeleton: Lyssacinosid type with
Page 60 and 61: 60 Fig. 29a. Skeleton types and ass
Page 62 and 63: 62 new data from recent species to
Page 64 and 65: 64 sheltered by the adjacent sand d
Page 66 and 67: 66 In addition to the episodic sedi
Page 68 and 69: 68 found in the most condensed sect
Page 70 and 71: 70 5.2.1. The Sponge Fauna of the S
Page 72 and 73: 72 5.2.2. Diagenesis Sponge-dominat
Page 75 and 76: Fossil Record of Sponges 75 6. Foss
Page 77 and 78: Fossil Record of Sponges 77 Fig. 35
Page 79 and 80: Fossil Record of Sponges 79 Fig. 37
Page 81: Fossil Record of Sponges 81 Fig. 38
Page 85: Comparison with other Spiculites 85
Page 88 and 89: 88 Hallam 1996; Hallam and Goodfell
Page 90 and 91: 90 From the Lower Liassic Kendlbach
Page 92 and 93: 92 At Steinplatte/Plattenkogel loca
Page 94 and 95: 94 8.2. Major and Trace Elements We
Page 96 and 97: 96 sediments. Due to this “contam
Page 98 and 99: 98 significance of microbial involv
Page 100 and 101: 100
Page 102 and 103: 102 � The Lower Liassic sediments
Page 104 and 105: 104 Böhm F (1992) Mikrofazies und
Page 106 and 107: 106 Garrison RE, Fischer AG (1969)
Page 108 and 109: 108 Krause FF, Scotese CR, Nieto C,
Page 110 and 111: 110 Olsen PE, Kent DV, Sues H-D, Ko
Page 112 and 113: 112 Schulze FE (1904) Hexactinellid
Page 114 and 115: 114 Wendt J (1969) Stratigraphie un
Page 116 and 117: Plate 1 Glasenbachklamm - Lower Lia
Page 118 and 119: Plate 2 Mühlstein-South - Hornstei
Page 120 and 121: Plate 3 Sonntagkendlgraben - Flecke
Page 122 and 123: Plate 4 Hochgern - Liassic sediment
Page 124 and 125: Plate 5 Scheibelberg - Type locatio
Page 126 and 127: Plate 6 Luegwinkel - Liassic sedime
Page 128 and 129: Plate 7 Moosbergalm - Slope and bas
Page 130 and 131: Plate 8 Tannhauser Berg - Liassic s
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Plate 9 Adnet / Rot-Grau-Schnöll Q
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Plate 10 Adnet / Rot-Grau-Schnöll
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Plate 15 Adnet / Lienbacher Quarry
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Plate 16 Adnet / Eisenmann Quarry -
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Plate 17 Steinplatte / Plattenkogel
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Plate 21 Diapir of Murguia / Spain
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Plate 22 Arctic Vesterisbanken Seam
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Supplement 1.1 (datas to Fig. 42) -
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Supplement 1.2 (datas to Fig. 43 +
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Supplement 2. (datas to Fig. 47) -
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Supplement 3.2 (datas to Fig. 46) -
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Supplement 4. - Energy Dispersive X
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Supplement 6. - Register of Localit
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Steinplatte/Fischer’s Coral Garde
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Publications Parts of this study ar
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Curriculum Vitae Geboren in Bremerh
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