Microfossils in a specimen of Cambrian (?) sandstone from Karstula, Central Finland

Tynni, R.

doi:10.17741/bgsf/46.1.002

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…Probable Terreneuvian strata are known from the extreme north of Finland (Systra & Jensen 2006), but how these relate to contemporaneous deposits in southern Baltoscandia is still unclear. Cambrian sediments are also known to the west of the Lappajärvi crater, from the Söderfjärden impact crater in western Finland (Tynni 1978(Tynni , 1982aHagenfeldt 1989b,c; Uutela 1998), from a number of scattered erratics and fissures around Finland (Simonen & Kouvo 1955;Martinsson 1956;Simonen 1956;Tynni 1974;Uutela 1983), from fissure-fills in Åland (Martinsson 1968;Bergman 1982;Tynni 1982b) and from sediments underlying the Bothnian Sea (Hagenfeldt 1989b,c;Slater et al 2017a). Where it can be established, however, these sediments all appear to be younger than Terreneuvian age, and most are lateearly Cambrian (Hagenfeldt 1989b,c).…”

Section: Age Of the Lappajärvi Scf Assemblagementioning

confidence: 99%

Early Cambrian small carbonaceous fossils (SCFs) from an impact crater in western Finland

Slater

Willman

2019

LET

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We describe an assemblage of small carbonaceous fossils (SCFs) and acritarchs from cored siltstones of the Lappajärvi impact structure, west‐central Finland. Previous studies had detected a depauperate acritarch biota ascribed to a deep Proterozoic origin—this age, however, was based on recovery of long‐ranging poorly age‐diagnostic sphaeromorphs. To resolve the age and provenance of these crater sediments, we applied low‐manipulation processing techniques optimized for retrieval of larger organic‐walled microfossils. Our study revealed a previously undetected assemblage containing numerous metazoan SCFs consisting of flattened ‘protoconodonts’ (grasping spines assignable to total group Chaetognatha) and a distinctive fossilised chaeta, possibly representing the oldest known annelid remains. Phylogenetically problematic fossils include various acritarchs (large Leiosphaeridia sp., Tasmanites tenellus, smaller sphaeromorphs, Synsphaeridium, Archaeodiscina and Granomarginata) and filamentous forms (Palaeolyngbya‐ and Rugosoopsis‐like filaments, Siphonophycus), likely representing prokaryotic or protistan grades of organisation. As well as adding new diversity to an emerging SCFs record, these data substantially refine the age of these sediments by more than half a billion years, to an early Cambrian Terreneuvian age. More specifically, the assemblage is equivalent to that of the Lontova Formation from the Baltic States and northwest Russia, but is previously unreported from Finland. Identification of Lontova‐type SCFs/organic‐walled microfossils at Lappajärvi further constrains the poorly resolved extent of maximum flooding during the early Cambrian in Baltica. Renewed attention should be directed to strata that have thus far produced only biostratigraphically long‐ranging or ambiguous palynological assemblages—‘SCF‐style’ processing can reveal hitherto undetected, age‐informative microfossils that are otherwise selectively removed in conventional palynological studies.

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Section: Age Of the Lappajärvi Scf Assemblagementioning

confidence: 99%

Early Cambrian small carbonaceous fossils (SCFs) from an impact crater in western Finland

Slater

Willman

2019

LET

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“…1). Sandstone erratics -probably Cambrian in age -have been found in Karstula, Ostrobothnia (Simonen & Kouvo 1955, Tynni 1974) and on the eastern coast of the Bothnian Bay (Uutela 1983). They show the Cambrian sea reached up to 65° N.…”

Section: Introductionmentioning

confidence: 99%

Extent of the northern Baltic Sea during the Early Palaeozoic Era - new evidence from Ostrobothnia, western Finland

Uutela¹

1998

Bull Geol Soc Finland

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This study reports new evidence of the extent of the northern Baltic Sea during the Cambrian and Ordovician periods. A drillcore (DC304) from the Lappajärvi impact crater, western Finland, and erratics from the surrounding area were studied for acritarchs. The acritarchs from the drillcore were reworked by the explosion but indicate, however, that the Baltic Sea extended beyond the western coast of central Finland during the Lower Cambrian Vergale and the Middle Cambrian Kibartai regional stages as well as during Middle Ordovician transitions from Aseri to Lasnamägi and from Idavere to Jöhvi regional stages. The provenance of the erratics was the Bothnian Bay, further north than the Lower Palaeozoic deposits previously known in the Bothnian Sea. The age could be determinated by their acritarch composition which shows that the sea also covered Central Ostrobothnia during the Lower Ordovician Billingen and early Middle Ordovician Lasnamägi regional stages. The drillcore samples contained also unknown spores. They suggest that there have been sediments and/or a terrestrial flora later than Ordovician in the Lappajärvi area.

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The Lower Cambrian of Scandinavia: Depositional environment, sequence stratigraphy and palaeogeography

Nielsen

Schovsbo

2011

Earth-Science Reviews

163

193

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Microfossils in a specimen of Cambrian (?) sandstone from Karstula, Central Finland

Cited by 3 publications

References 3 publications

Early Cambrian small carbonaceous fossils (SCFs) from an impact crater in western Finland

Early Cambrian small carbonaceous fossils (SCFs) from an impact crater in western Finland

Extent of the northern Baltic Sea during the Early Palaeozoic Era - new evidence from Ostrobothnia, western Finland

The Lower Cambrian of Scandinavia: Depositional environment, sequence stratigraphy and palaeogeography

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