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| 2. |
- Bergman, C F, et al.
(författare)
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The jawed annelid Rhytiprion magnus Kielan-Jaworowska, 1966 - a muddy bottom dweller
- 2003
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Ingår i: GFF. - 2000-0863. ; 125:4, s. 191-199
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 3. |
- Bergström, Stig M., et al.
(författare)
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Obituary Lennart Jeppsson 1940-2015
- 2015
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Ingår i: The Palaeontological Association Newsletter. - 0954-9900. ; 89, s. 103-105
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Calner, Mikael, et al.
(författare)
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An atypical intra-platform environment and biota from the Silurian of Gotland, Sweden
- 2008
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Ingår i: GFF. - 2000-0863. ; 130:Part 2, s. 79-86
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Tidskriftsartikel (refereegranskat)abstract
- A condensed shale from the middle Silurian of Gotland (Sweden) is herein described with regard to its biotic and environmental significance. The fauna is characterised by an overall low diversity and anomalous abundance patterns, notably a mass-occurrence of scolecodonts. Other elements include abundant chitinozoans, dendroid and graptoloid graptolites, conodonts, eurypterids, and the brachiopod Lingula. An unusually good collection of the rare, minute conodont Aldridgeodus minimus gen. et sp. nov., was recovered and is therefore formally described herein. The conspicuous faunal composition and palaeogeographical position of the shale in the interior area of a carbonate platform is unique for any stratum of Gotland and may represent a rarely preserved environment for the lower Palaeozoic.
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| 5. |
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| 6. |
- Calner, Mikael, et al.
(författare)
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Evidence for rapid environmental changes in low latitudes during the Late Silurian Lau Event: the Burgen-1 drillcore, Gotland, Sweden
- 2006
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Ingår i: Geological Magazine. - 0016-7568. ; 143:1, s. 15-24
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Tidskriftsartikel (refereegranskat)abstract
- Erosional outliers are an important component of the Ludlow (Late Silurian) stratigraphy of Gotland, Sweden. However, due to the poor degree of exposure, outcrop studies have not revealed a detailed section from any of these outliers. The first complete stratigraphy of such an erosional remnant. the Burgen outlier, is presented here, based on the recently recovered Burgen-1 drillcore. Stratigraphical units encountered are, from oldest to Youngest, the uppermost Hemse Group (> 35 m), Eke Formation (0.4 m), Burgsvik Formation (3.4 m) and the basal Hamra Formation (12 in preserved). Based on carbon stable isotopes and lithological correlation to nearby outcrops that are zoned by conodonts, it can be concluded that the most profound late Ludlow sedimentary changes took place shortly after the onset of the globally recognized Lau Event (delta(13)C values reach 8.7 parts per thousand in the lower Hamra Formation). Sedimentary changes include development of discontinuity surfaces, widespread occurrence of an intraclastic conglomerate, increased microbial activity (Rothpletzella and Wetheredella), and influx of clastics to the basin. These changes are linked to substantial base-level changes during the event. A general comparison with the Prague basin suggests contemporaneous sedimentary changes on Baltica and on cratonic elements from peri-Gondwana during the event.
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| 7. |
- Calner, Mikael, et al.
(författare)
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Silurian research at the crossroads
- 2006
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Ingår i: GFF. - 2000-0863. ; 128:2, s. 73-74
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
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| 9. |
- Calner, Mikael, et al.
(författare)
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The Record of Microbially Induced Sedimentary Structures (MISS) in the Swedish Paleozoic
- 2012
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Ingår i: Microbial Mats in Siliciclastic Depositional Systems Through Time. - 2159-5755 .- 1060-071X. - 9781565763142 ; :101, s. 29-35
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Konferensbidrag (refereegranskat)abstract
- Microbially induced sedimentary structures (MISS) in siliciclastic shallow-marine strata occur in the lower and middle Cambrian and the Silurian of southern Sweden. These are typically transparent wrinkle structures with a wide range of morphologies. They are exclusively associated with shoreface to lower shoreface environments, characterized by fine-grained sandstone interbedded with mudstone and a Cruziana ichnofacies. Thicker, non-transparent forms with high-relief crinkled surfaces occur in the same paleoenvironments. The landward sand-dominated facies belt with Skolithos ichnofacies (upper shoreface foreshore) lack preserved wrinkle structures. Evidently, wrinkle structures are more common than previously thought in the Swedish Paleozoic and provide an important tool for understanding paleoenvironments and benthic paleoecology in strata largely devoid of body and trace fossils.
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| 10. |
- Calner, Mikael, et al.
(författare)
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Ytterholmen revisited - implications for the Late Wenlock stratigraphy of Gotland and coeval extinctions
- 2004
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Ingår i: GFF. - 2000-0863. ; 126:2, s. 231-241
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Tidskriftsartikel (refereegranskat)abstract
- 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 'g' (c. 12-20 m), Atrypa "reticularis" Beds (c. 0.5 m), Frojel Formation (c. 0.5 m), and the Halla Formation. The boundary between the Frojel 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 Frojel 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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