Significance of a Halysitid-Heliolitid Mud-facies Autobiostrome from the Middle Silurian of Gotland, Sweden

Calner, Mikael; Sandström, Olof; Mõtus, Mari-Ann

doi:10.1669/0883-1351(2000)015<0511:soahhm>2.0.co;2

Cited by 20 publications

(15 citation statements)

References 28 publications

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“…They 'differ from the others in large number of small dendroid and encrusting tabulates and bryozoans' (Klaamann and Einasto 1977). On western Gotland the earliest post-extinction reef is a low-diversity halysitid-heliolitid autobiostromedominated by dendroid heliolitids-that differs from all other Wenlock-Ludlow reefs on Gotland (Calner et al 2000). During this interval, stromatolites are important in the East Baltic part of the basin (Calner et al 2004a).…”

Section: Facies Anomalies During the Mulde Eventmentioning

confidence: 99%

Silurian carbonate platforms and extinction events—ecosystem changes exemplified from Gotland, Sweden

Calner

2005

Facies

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Recent and ancient carbonate platforms are major marine ecosystems, built by various carbonate-secreting organisms with different sensitivity for environmental change. For this reason, carbonate platforms are excellent sensors for changes in contemporaneous marine environments. A variety of ecosystem changes in carbonate platforms have previously been recognised in the aftermath of mass extinction events. This paper addresses how two Silurian extinction events among graptolites, conodonts, and pentamerid brachiopods can be related to changes in the style of carbonate production and general evolution of low latitude carbonate platforms in a similar way as previously reported from the major five mass extinctions of the Phanerozoic. Strata formed on Gotland during the Mulde and Lau events share remarkably many similarities but are strikingly different in composition compared to other strata on the island. The event-related strata is characterised by the sudden appearance of widespread oolites, deviating reef composition, flat-pebble conglomerates, abundant microand macro-oncoids, stromatolites, and other microbial facies suggesting decreased bioturbation levels in contemporaneous shelf seas. Importantly, these changes can be tied to high-resolution biostratigraphic frameworks and global stable isotope excursions. The anomalous intervals may therefore be searched for elsewhere in order to test their regional or global significance.

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Section: Facies Anomalies During the Mulde Eventmentioning

confidence: 99%

Silurian carbonate platforms and extinction events—ecosystem changes exemplified from Gotland, Sweden

Calner

2005

Facies

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“…The strata are fundamentally different from the earliest transgressive strata on the main island. There, reefs are absent in strata immediately above Datum Plane 2 of the Mulde Event (Calner et al 2000). Instead, oolites and algal-dominated carbonates predominated across the platform.…”

Section: Recovery Interval Deposition (Halla Formation)mentioning

confidence: 99%

“…These strata crop out in the southernmost Klintehamn area on western Gotland (Fig. 1), which is the reference area for the Mulde Event; ; Jeppsson (1998) ;Calner (1999Calner ( , 2002; Calner et al (2000); ; . The Mulde Event is characterized by stepwise extinctions (at three datum points), followed by a low diversity interval, and a recovery interval.…”

Section: Introductionmentioning

confidence: 99%

Ytterholmen revisited – implications for the Late Wenlock stratigraphy of Gotland and coeval extinctions

Calner¹,

Jeppsson²,

Eriksson³

2004

GFF

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The latest Cyrtograptus lundgreni graptolite Chron (Late Wenlock, middle Silurian) is characterized globally by the Mulde Event faunal extinctions and glacio-eustatic sea-level change. Only in the last decade has it been recognized as one of the most severe extinction events of the Silurian Period. A section spanning the Slite Group-Halla Formation boundary on the islet Ytterholmen off main Gotland (Sweden) is unique in that strata through the extinction interval are preserved within a reef complex. The importance of Ytterholmen is twofold: First, based on conodonts, lithology and stratigraphic boundaries, the stratigraphy of the Slite Group-Halla Formation boundary interval on eastern Gotland is now fully understood, in ascending order: Slite ʻgʼ (c. 12-20 m), Atrypa "reticularis" Beds (c. 0.5 m), Fröjel Formation (c. 0.5 m), and the Halla Formation. The boundary between the Fröjel and Halla formations is an unconformity as previously reported across most of the main island. Second, correlation of the Ytterholmen section with the Mulde Event reference profile on western Gotland for the first time enables study of this event in very shallow interior areas of the carbonate platform. Here, the c. 1 m thick extinction interval (including the Atrypa "reticularis" Beds and the Fröjel Formation) is characterized by mass-occurrences of an atrypid brachiopod, deposition of fine siliciclastic material and termination of the reef complex. Correlation with the East Baltic and Podolia, Ukraine, suggests that similar reef termination occurred contemporaneously throughout the basin. Small patch-reefs occurring immediately above the unconformity on Ytterholmen are among the earliest Mulde Event post-extinction reefs reported from the Baltic basin.

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“…In distal platform environments, seaward of the mid-Homerian lowstand shoreline position, the Bara Oolite Member is overlain by prograding mudstones and highly argillaceous wacke-packe-stones of the Mulde Brick-clay and Djupvik members ( Fig. 4; Calner et al 2000). Rhytiprion magnus is relatively abundant, from a few percent up to almost 26% (in sample 70-26LJ) of the jawed polychaete fauna, only in the marly strata of the Djupvik Member, particularly at Djupvik 2 (Figs.…”

Section: Gotland Swedenmentioning

confidence: 99%

“…Numbers 1-4 refer to geographical areas and drillcores; 1 = När-1 drillcore, 2= Bjärges-1 drilling, 3 = Klintehamn area, 4 = Ytterholmen. See Calner et al (2000) for detailed locality-and stratigraphical data to this figure. …”

Section: Gotland Swedenmentioning

confidence: 99%

The jawed annelidRhytiprion magnusKielan-Jaworowska, 1966 – a muddy bottom dweller

Bergman

Eriksson

Calner

2003

GFF

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The Ordovician jawed polychaete annelid Rhytiprion magnus has hitherto been recorded in erratic boulders of probable East Baltic provenance and in drill cores from Poland and North Estonia. In this study the stratigraphical range and geographical distribution are extended as R. magnus is recorded from the Silurian of Gotland (Sweden) and Indiana (U.S.A.). Hence, R. magnus is now known from the Middle Ordovician to the middle Silurian (lower Ludlow; Kockelella v. variabilis conodont Zone) and comprises one of the few Palaeozoic polychaete species with a documented intercontinental distribution. The species is generally very rare but is abundant at a few localities; on Gotland, in the offshore setting of the Late Wenlock (K. ortus absidata conodont Zone; Colonograptus? praedubeli graptolite Zone) Djupvik Member of the Halla Formation. The distribution pattern shows that R. magnus thrived in low energy, distal platform environments, in which marly and muddy terrigenous sediments accumulated.

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Significance of a Halysitid-Heliolitid Mud-facies Autobiostrome from the Middle Silurian of Gotland, Sweden

Cited by 20 publications

References 28 publications

Silurian carbonate platforms and extinction events—ecosystem changes exemplified from Gotland, Sweden

Silurian carbonate platforms and extinction events—ecosystem changes exemplified from Gotland, Sweden

Ytterholmen revisited – implications for the Late Wenlock stratigraphy of Gotland and coeval extinctions

The jawed annelidRhytiprion magnusKielan-Jaworowska, 1966 – a muddy bottom dweller

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