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Frisk, Åsa
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Publications (10 of 22) Show all publications
Brosse, M., Bucher, H., Baud, A., Frisk, Å., Goudemand, N., Hagdorn, H., . . . Hautmann, M. (2019). New data from Oman indicate benthic high biomass productivity coupled with low taxonomic diversity in the aftermath of the Permian-Triassic Boundary mass extinction. Lethaia: an international journal of palaeontology and stratigraphy, 52(2), 165-187
Open this publication in new window or tab >>New data from Oman indicate benthic high biomass productivity coupled with low taxonomic diversity in the aftermath of the Permian-Triassic Boundary mass extinction
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2019 (English)In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 52, no 2, p. 165-187Article in journal (Refereed) Published
Abstract [en]

A new Early Triassic marine fauna is described from an exotic block (olistolith) from the Ad Daffah conglomerate in eastern Oman (Batain), which provides new insights into the ecology and diversity during the early aftermath of the Permian-Triassic Boundary mass extinction. Based on conodont quantitative biochronology, we assign a middle Griesbachian age to the upper part of this boulder. It was derived from an offshore seamount and yielded both nektonic and benthic faunas, including conodonts, ammonoids, gastropods and crinoid ossicles in mass abundance. This demonstrates that despite the stratigraphically near extinction at the Permian-Triassic Boundary, Crinoidea produced enough biomass to form crinoidal limestone as early as middle Griesbachian time. Baudicrinus, previously placed in Dadocrinidae, is now placed in Holocrinidae; therefore, Dadocrinidae are absent in the Early Triassic, and Holocrinidae remains the most basal crown-group articulates, originating during the middle Griesbachian in the Tethyan Realm. Abundant gastropods assigned to Naticopsis reached a shell size larger than 20 mm and provide another example against any generalized Lilliput effect during the Griesbachian. Whereas the benthic biomass was as high as to allow the resumption of small carbonate factories, the taxonomic diversity of the benthos remained low compared to post-Early Triassic times. This slow benthic taxonomic recovery is here attributed to low competition within impoverished post-extinction faunas.

Place, publisher, year, edition, pages
WILEY, 2019
Keywords
benthos, biotic recovery, Griesbachian, Oman, Permian-Triassic Boundary
National Category
Geology Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-380426 (URN)10.1111/let.12281 (DOI)000461190100002 ()
Funder
Swedish Research Council
Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-04-01Bibliographically approved
Egenhoff, S., Maletz, J., Ahlberg, P., Mast, A., Frisk, Å., Ebbestad, J. O. & Newby, W. (2018). Sedimentology of the Lower Ordovician (upper Tremadocian) Bjørkasholmen Formation at Flagabro, southern Sweden. GFF, 140(1), 55-65
Open this publication in new window or tab >>Sedimentology of the Lower Ordovician (upper Tremadocian) Bjørkasholmen Formation at Flagabro, southern Sweden
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2018 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 140, no 1, p. 55-65Article in journal (Refereed) Published
Abstract [en]

The Lower Ordovician Bjørkasholmen Formation at Flagabro, Scania, southern Sweden, consists of a 0.8m thick succession of carbonates with three siliciclastic mudstones, 5, 1 and 100mm thick, intercalated in the central part of the unit. Carbonate and siliciclastic mudstone beds show both normal and inverse grading. The carbonates are mud-rich and subdivided into a mudstone, a wackestone and a packstone facies. Grain types in the carbonates are mostly shells and shell fragments of brachiopods and trilobites. The carbonate rocks are strongly bioturbated seen as in roundish burrows filled with mud and a clear cement; additionally, bioturbation is reflected in the random orientation of shells. The siliciclastic mudstones are subdivided into two facies; one contains large amounts of shells and is in part grain-supported, the other is matrix-dominated and laminated to massive. The succession reflects sedimentation on a low-inclined shelf equivalent to a mid-ramp to basinal setting. Most mud- and wackestones (facies 3 and 4) represent fair-weather sedimentation, and the intercalated wacke- and packstones (facies 4 and 5) represent concentration of shell debris during high-energy storm. The siliciclastic mudstones in the central part of the succession reflect deposition in a basinal setting. The entire BjOrkasholmen Formation at Flagabro is equivalent to a lowstand of third (?) order without a well-developed internal cyclicity and is in that respect similar to the Bjørkasholmen Formation of oland, but different from the age-equivalent Norwegian sections.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2018
Keywords
Bjørkasholmen Formation, carbonates, siliciclastic mudstones, Flagabro
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-356330 (URN)10.1080/11035897.2018.1445777 (DOI)000432160200006 ()
Available from: 2018-07-24 Created: 2018-07-24 Last updated: 2018-07-24Bibliographically approved
Hautmann, M., Bagherpour, B., Brosse, M., Frisk, Å., Hofmann, R., Baud, A., . . . Bucher, H. (2015). Competition in slow motion: the unusual case of benthic marine communities in the wake of the end-Permian mass extinction. Palaeontology, 58(5), 871-901
Open this publication in new window or tab >>Competition in slow motion: the unusual case of benthic marine communities in the wake of the end-Permian mass extinction
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2015 (English)In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 58, no 5, p. 871-901Article in journal (Refereed) Published
Abstract [en]

Changes of community structure in response to competition usually take place on timescales that are much too short to be visible in the geological record. Here we report the notable exception of a benthic marine community in the wake of the end-Permian mass extinction, which is associated with the microbial limestone facies of the earliest Triassic of South China. The newly reported fauna is well preserved and extraordinarily rich (30 benthic macroinvertebrate species, including the new species Astartella? stefaniae (Bivalvia) and Eucochlis obliquecostata (Gastropoda)) and stems from an environmentally stable setting providing favourable conditions for benthic organisms. Whereas changes in the taxonomic composition are negligible over the observed time interval of 10-100ka, three ecological stages are identified, in which relative abundances of initially rare species continuously increased at the cost of previously dominant species. Concomitant with the changes of dominant species is an increase in faunal evenness and heterogeneity. In the absence of both environmental and taxonomic changes, we attribute this pattern to the long-term effects of interspecific competition, which acted at an unusually slow pace because the number of competing species and potential immigrants was dramatically reduced by the end-Permian mass extinction. We suggest that these non-actualistic conditions led to decreased rates of niche differentiation and hence to the delayed rediversification of benthos that characterizes the aftermath of the greatest Phanerozoic mass extinction event. A hyperbolic diversification model is proposed, which accounts for the positive relationship between the intensity of interspecific competition and the rate of niche differentiation and resolves the conundrum of delayed rediversification at a time when niche space was largely vacated.

Keywords
diversification, competition, benthos, Early Triassic, China
National Category
Geology Ecology
Identifiers
urn:nbn:se:uu:diva-263450 (URN)10.1111/pala.12186 (DOI)000360586100007 ()
Available from: 2015-10-06 Created: 2015-09-30 Last updated: 2017-12-01Bibliographically approved
Brosse, M., Bucher, H., Bagherpour, B., Baud, A., Frisk, Å. M., Guodun, K. & Goudemand, N. (2015). Conodonts from the Early Triassic Microbialite of Guangxi (South China): Implications for the Definition of the Base of the Triassic System. Palaeontology, 58(3), 563-584
Open this publication in new window or tab >>Conodonts from the Early Triassic Microbialite of Guangxi (South China): Implications for the Definition of the Base of the Triassic System
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2015 (English)In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 58, no 3, p. 563-584Article in journal (Refereed) Published
Abstract [en]

We describe a new Early Triassic (Griesbachian) succession of conodont faunas from a high-resolution sampling of the basal Early Triassic microbial limestone and the base of the overlying unit at the Wuzhuan section (Nanpanjiang Basin, Guangxi, South China). The microbial limestone records the earliest phase of the Early Triassic biotic recovery after the end-Permian mass extinction. For the first time, rich conodont faunas are reported from within the microbialite. The faunas from Wuzhuan are largely dominated by anchignathodontids, including several Isarcicella species, which were previously documented only from strata above the microbialite. A total of 14 conodont species assigned to three genera is recorded from the Wuzhuan section. Starting from the base of the microbialite upwards, several species are sequentially added to the conodont assemblage. The alpha diversity peaks at the top of the microbialite. The conodont record in the considered microbialite interval at Wuzhuan is presumably unaffected by local ecological changes. It therefore more likely represents an evolutionary rather than an ecological pattern. We compare the Wuzhuan's conodont record with a well-supported phylogenetic model and suggest that the sequence of first occurrences at Wuzhuan is the closest to the true' sequence of evolutionary events that took place during this Griesbachian radiation of anchignathodontids. Based on comparisons with the GSSP section at Meishan, we suggest further that the first occurrence of Hindeodus parvus in Meishan does not correspond to its first appearance datum.

Keywords
Permian-Triassic boundary, Nanpanjiang Basin, microbial limestone, calcarenite lenses, anchignathodontids
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-252989 (URN)10.1111/pala.12162 (DOI)000353398000010 ()
Available from: 2015-05-19 Created: 2015-05-18 Last updated: 2017-12-04Bibliographically approved
Ebbestad, J. O., Hogstrom, A. E. S., Frisk, Å. M., Martma, T., Kaljo, D., Kroger, B. & Parnaste, H. (2015). Terminal Ordovician stratigraphy of the Siljan district, Sweden. GFF, 137(1), 36-56
Open this publication in new window or tab >>Terminal Ordovician stratigraphy of the Siljan district, Sweden
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2015 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 137, no 1, p. 36-56Article, review/survey (Refereed) Published
Abstract [en]

Integration of new isotopic data and earlier biostratigraphic information from eight sections through the terminal Ordovician (Pirgu and Porkuni stages) of the Siljan district, Sweden, allows a more precise correlation of sections in terms of biostratigraphy and carbon isotope dating. Four levels with positive delta C-13 excursions are identified (from bottom) - the Moe, an unnamed excursion, Paroveja and Hirnantian Carbon Isotope Excursion (HICE). The delta C-13 values through the Boda Limestone are 1-2 parts per thousand higher than usual in Baltica, only the values for the HICE remains within what is expected. Background values increase from 1.5 parts per thousand in the bottom of the core of the Boda Limestone up to 3 parts per thousand in the top of it. The HICE is identified in five of eight sections and the main peak falls according to inferred correlation within the Metabolograptus persculptus Biozone, at or close to the Hindella beds in the Upper Boda Member. The late Katian (Pirgu) age of Holorhynchus in the Siljan district is clear and its co-occurrence with the chitinozoan Belonechitina gamachiana in Estonia supports a Katian age for this zone. The base of the Ozarkodina hassi Biozone may occur within units B-C of the Upper Boda Member and in the upper part of the Loka Formation and most likely is correlated with the M. persculptus Biozone. The Hirnantia-Dalmanitina faunas reported from the lowermost part of the Loka Formation and units B-D of the Upper Boda Member seem to range through all the Hirnantian, but detailed morphological studies allow to distinguish an older (=extraordinarius) and a younger (=persculptus) fauna.

Keywords
chemostratigraphy, Upper Ordovician, carbon isotope excursions, Boda [Limestone] Formation, brachiopod coquinas, biozones
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-247684 (URN)10.1080/11035897.2014.945620 (DOI)000349787800005 ()
Available from: 2015-03-23 Created: 2015-03-23 Last updated: 2017-12-04Bibliographically approved
Ebbestad, J. O., Högström, A. & Frisk, Å. (2013). Gastropods and tergomyans from the Upper Ordovician (Viru–Harju) of the Fågelsång area, Scania, southern Sweden. Journal of Systematic Palaeontology, 11(3), 295-336
Open this publication in new window or tab >>Gastropods and tergomyans from the Upper Ordovician (Viru–Harju) of the Fågelsång area, Scania, southern Sweden
2013 (English)In: Journal of Systematic Palaeontology, ISSN 1477-2019, E-ISSN 1478-0941, Vol. 11, no 3, p. 295-336Article in journal (Refereed) Published
Abstract [en]

A diverse tergomyan and gastropod assemblage is described from the Global Boundary Stratotype Section and Point (GSSP)section of the Sandbian Stage, Upper Ordovician, in the Fågelsång area, Scania, southern Sweden. Deep water graptolitic mudstone and shale comprise the succession, and previously only one gastropod species was known. The new material spans the Sularp Formation through the Lindegård Mudstone (Nemagraptus gracilisDicellograptus complanatus biozones). Fourteen species are described: two tergomyan, five bellerophontoid gastropods, and seven anisostrophically coiled gastropods.Three species are new: Peelerophon hodites, Tetranota scanica and Lophospira sandbiana. Three taxa (Tritonophon subtrilobatus,Tetranota scanica and Holopea mobergi) are found high in the Lindegård Mudstone (Vormsi–Pirgu stages). Cyrtodiscus, Peelerophon and Tritonophon are recorded for the first time in Baltoscandia. Some taxa may have been transportedfrom shallower water settings, whereas species of Peelerophon, Joleaudella, Mestoronema and Sinuites may have been partof the local benthos. Except for Bucania erratica, no species are shared with the fauna of the coeval Dalby Limestone in Sweden. Deaechospira elliptica, common in the Dalby Limestone, is not recorded at Fågelsång, although two closely relatedspecies are found (Deaechospira rotunda and Deaechospira? sp.). The Fågelsång assemblage has more in common with the older to coeval fauna of the Elnes and Arnestad formations in the Oslo Region, Norway (e.g. sharing Joleaudella, Sinuites, Mestoronema and Pararaphistoma). The Sandbian fauna of Fågelsång includes peri-Gondwanan taxa, e.g. Cyrtodiscus,Peelerophon and Deaechospira. Nevertheless, cluster analysis reveals that the faunas of Baltica and Laurentia were most similar, whereas faunas from Perunica and Baltica remained distinct and separated during the Darriwilian–Sandbian. The few similarities may result from spread of a temperate fauna supplementing rather than replacing taxa in deep water assemblages.The main Fåagelsång assemblage coincides both with the Baltoscandian Middle Caradoc Faunal Turnover and the Gutenberg Carbon Isotope Excursion.

Keywords
gastropods; tergomyans; deep water; palaeobiogeography; Sandbian; Mid Caradoc Faunal Turnover
National Category
Geology
Research subject
Historical Geology and Paleontology
Identifiers
urn:nbn:se:uu:diva-196044 (URN)10.1080/14772019.2012.660994 (DOI)000316588200002 ()
Available from: 2013-03-04 Created: 2013-03-04 Last updated: 2017-12-06Bibliographically approved
Frisk, Å. M. (2009). Late Ordovician Faunal Distribution and Ecospace Partitioning in Marine Impact Craters: The Aftermath of the Lockne and Tvären Events. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Late Ordovician Faunal Distribution and Ecospace Partitioning in Marine Impact Craters: The Aftermath of the Lockne and Tvären Events
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the Middle to Late Ordovician a boost of marine biodiversity occurred which is regarded as the most rapid diversity in Earth’s history, and termed the Great Ordovician Biodiversification Event. This time is also unique in that at least four marine meteorite craters with a good record of post-impact sediments are preserved in Baltoscandia. Catastrophic impacts can serve as constructive events and produce wide-ranging environments providing new ecological niches for a diverse biota to occupy. Additionally, they generate distinctive patterns of biological destruction and recovery. This, and the study of distribution and ecospace utilisation of Late Ordovician faunas, has been analysed in two almost contemporary (around 455 million years ago) meteorite craters (Lockne and Tvären, Sweden). Within the confined space of the impact craters environments varied from shallow and reef-like to over 200 m in depth and from well oxygenated to hypoxic. These types of environments favored colonization of different individual groups. In Tvären rhynchonelliformean brachiopod assemblages from the shallow crater rim include a range of morphotypes, not established elsewhere in the crater. Within the crater depression rhynchonelliformean brachiopods were not established until the upper third of the remaining crater fill. Colonization of post-impact faunas varies dependent on topography, depth and susbstrate within the impact craters. This is recognised for scolecodonts in Tvären and for gastropod-like mollusks, linguliform and craniiform brachiopods in both of the craters, as they inhabit a wide range of ecospace. A succession of different taxa is observed from the deepest part of each crater and upwards towards inferably more shallow, higher energy, water settings. The development of new community types and narrowly-defined niches in the craters helped further drive both α and β biodiversity during a critical phase of the Great Ordovician Biodiversification Event.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. p. 45
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 685
Keywords
impact crater, Lockne, Tvären, ecospace, the Great Ordovician Biodiversification Event
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-109605 (URN)978-91-554-7639-7 (ISBN)
Public defence
2009-12-04, Axel Hambergsalen, Geocentrum, Villavägen 16, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2009-11-09 Created: 2009-10-20 Last updated: 2009-11-12
Frisk, Å. & Ormö, J. (2008). Facies distribution of post- impact sediments in the Ordovician Lockne and Tvären impact craters: Indications for unique impact-generated environments.. In: 28th Nordic Geological Wintermeeting - Abstract volume: Aalborg Denmark (pp. 1).
Open this publication in new window or tab >>Facies distribution of post- impact sediments in the Ordovician Lockne and Tvären impact craters: Indications for unique impact-generated environments.
2008 (English)In: 28th Nordic Geological Wintermeeting - Abstract volume: Aalborg Denmark, 2008, p. 1-Conference paper, Published paper (Other (popular scientific, debate etc.))
Identifiers
urn:nbn:se:uu:diva-12758 (URN)87-91606-16-0 (ISBN)
Available from: 2008-01-13 Created: 2008-01-13
Egenhoff, S., Cassle, C., Maletz, J., Ebbestad, J. O. & Frisk, Å. M. (2008). Tectonically-Induced Lowstand on an Ordovician Ramp – the Björkåsholmen Formation of Scandinavia. In: 2008 Houston Annual Meeting (5–9 October 2008).: Geological Society of America Abstracts with Programs. Paper presented at Geological Association of America, Annual Meeting, Houston,5–9 October 2008 (pp. 393). Geological Society of America
Open this publication in new window or tab >>Tectonically-Induced Lowstand on an Ordovician Ramp – the Björkåsholmen Formation of Scandinavia
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2008 (English)In: 2008 Houston Annual Meeting (5–9 October 2008).: Geological Society of America Abstracts with Programs, Geological Society of America , 2008, p. 393-Conference paper, Published paper (Other academic)
Abstract [en]

The Tremadoc Björkåsholmen Formation is an approximately one meter thick unit consisting of several carbonate beds with intercalated shales and some glauconite content in its upper part. It is underlain by the Cambrian-Ordovician Alum Shale Formation throughout Scandinavia, and in Norway and westernmost Sweden overlain by the Lower- to Middle Ordovician Tøyen Formation. The Björkåsholmen Formation is remarkably widespread in Scandinavia with relatively little variation in thickness or faunal composition. Internally, the unit consists of thin beds at the base with thicker ones in the center and again thinner beds towards the top. Thin beds are generally mud-rich while thicker ones display packstones. In the Norwegian sections the grain-rich facies have been mostly diagenetically overprinted, whereas eastern Swedish localities are characterized by much better facies preservation regardless of lithology. The overall mud-rich facies of the Björkåsholmen Formation reflects deposition on a low-inclined ramp environment. Coarse-grained sediments represent the proximal facies while increasing mud content shows deeper water middle to outer ramp deposition. Facies trends indicate that the Björkåsholmen Formation consists of at least five regressions and successive transgressions with a maximum lowstand represented by its coarse-grained central portion. As the Björkåsholmen Formation is sandwiched between two prominent outer shelf shales in the Norwegian and westernmost Swedish localities it also represents the most pronounced sea-level lowstand in the Early Ordovician of Scandinavia.This lowstand is within the upper part of the Aorograptus victoriae Biozone and the basal Kiaerograptus supremus Biozone. Deposition of the Björkåsholmen Formation therefore likely represents a fairly short time-span. However, this remarkably strong lowstand in Scandinavia is not paralleled by base-level falls in Bolivia, China or Newfoundland. It is therefore suggested that the Björkåsholmen Formation reflects a tectonic rather than a eustatic event which is restricted exclusively to Baltoscandia.

Place, publisher, year, edition, pages
Geological Society of America, 2008
National Category
Geology
Research subject
Earth Science with specialization in Historical Geology and Palaeontology
Identifiers
urn:nbn:se:uu:diva-10122 (URN)
Conference
Geological Association of America, Annual Meeting, Houston,5–9 October 2008
Available from: 2008-10-15 Created: 2008-10-15 Last updated: 2015-01-13
Frisk, Å. & Ebbestad, J. O. (2007). Diversity and distribution of paragastropods, tergomyans and gastropods in the Upper Ordovician Dalby Limestone, Sweden.. In: Palaeontological Association 51st Annual Meeting: Uppsala University, Sweden (pp. 1).
Open this publication in new window or tab >>Diversity and distribution of paragastropods, tergomyans and gastropods in the Upper Ordovician Dalby Limestone, Sweden.
2007 (English)In: Palaeontological Association 51st Annual Meeting: Uppsala University, Sweden, 2007, p. 1-Conference paper, Published paper (Other (popular scientific, debate etc.))
Identifiers
urn:nbn:se:uu:diva-12759 (URN)
Available from: 2008-01-13 Created: 2008-01-13
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