<i>Broeggeria</i>Walcott and other upper Cambrian and Tremadocian linguloid brachiopods from NW Argentina

Benedetto, Juan L.; Lavié, Fernando Julián; Muñoz, Diego F.

doi:10.1002/gj.2880

Cited by 3 publications

(2 citation statements)

References 60 publications

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“…Popov & Holmer (1994), in defining the Broeggeria Assemblage, noted its extensive distribution in late Cambrian and early Ordovician black shales in Scandinavia, Nova Scotia, the southern Urals, central Kazakhstan and the Kendyktas Range together with the Anglo-Welsh Basin (Avalonia) from where the type species was first described. More recently, the geographical range of the assemblage has been extended to the Purmamarca area of NW Argentina (see Benedetto et al (2018) for fuller discussion of the distribution of the assemblage). The association is of low diversity, inhabiting open-shelf, dysaerobic, olenid-dominated environments and may appear during the transgression of black shale facies onto the shelf (Popov & Holmer, 1994).…”

Section: The Brachiopodsmentioning

confidence: 99%

A Cambrian–Ordovician boundary section in the Rafnes–Herøya submarine tunnel, Skien–Langesund District, southern Norway

Rønning¹,

Bruton²,

Harper³

et al. 2020

NJG

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Rock specimens and contained fossils collected in 1976 from a submarine tunnel driven between Herøya and Rafnes in the Skien-Langesund area of southern Norway, have been restudied. The contained fossils include olenid and agnostoid trilobites, graptolites and brachiopods, groups described in detail for the first time from the area and documenting a Cambrian-Ordovician boundary section unique in the district where the upper Cambrian Alum Shale Formation is elsewhere overlain by the Middle Ordovician Rognstranda Member of the Huk Formation (Kundan in terms of Baltoscandian chronostratigraphy). The hiatus at the base of the Huk Formation is thus smaller in the section described herein, beginning at a level within rather than below the Tremadocian. Estimated thickness of the Alum Shale includes 10-12 m of Miaolingian and 20-22 m of Furongian strata with trilobite zones identified, and a Tremadocian section of 8.1 m identified by species of the graptolite Rhabdinopora in the basal 2.6 m and Bryograptus ramosus at the top. The Tremadocian section is preserved in a postulated zone of synsedimentary subsidence along the Porsgrunn-Kristiansand Fault Zone, while at the same time there was extensive erosion across an emergent, level platform elsewhere in the Skien-Langesund District and the southern part of the Eiker-Sandsvaer District to the north. Aspects of stratigraphy and tectonics are highlighted together with a discussion on the Cambrian-Ordovician boundary locally and worldwide.

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Section: The Brachiopodsmentioning

confidence: 99%

A Cambrian–Ordovician boundary section in the Rafnes–Herøya submarine tunnel, Skien–Langesund District, southern Norway

Rønning¹,

Bruton²,

Harper³

et al. 2020

NJG

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“…Benedetto ; Benedetto et al . , ; Salas ; Balseiro & Waisfeld ; Cichowolski et al . ; Benedetto & Muñoz , ; Toro et al .…”

Section: Geological Settingunclassified

Radiation, diversity and environmental expansion of Early Ordovician ostracods: a view from the Southern Hemisphere

Salas

Waisfeld

Muñoz

2019

LET

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Tremadocian–Floian siliciclastic successions in the Argentine Cordillera Oriental are of great interest for the study of early ostracod radiation. Four genera and five species of ostracods have so far been documented in the basin from the Early–Late Tremadocian (Tr2). This contrasts with occurrences from other palaeocontinental areas, where typically only one species is described. Patterns of environmental distribution and ecological approaches of ostracod assemblages were analysed on the basis of richness, Fisher's alpha diversity, relative abundance and occupancy. Ecological patterns remained stable throughout the studied interval, mostly with one genus notably dominant over the others. At the regional scale, dominant taxa occur at a relatively large number of sites, which display high occupancy. The literature data on carbonate successions from the Baltoscandian basin show a similar pattern, with a single taxon dominant over the others in local assemblages and wide regional distribution of these dominants. This ecological pattern would therefore have persisted at least until the Dapingian, independently of the sedimentary regime. Ostracods were already present along the onshore–offshore gradient during the initial stages of radiation, showing a strong preference for deep subtidal settings during Tr2 and then spreading to shallower environments in Tr3 and to deeper ones in the Floian (Fl2–Fl3). A compilation of ostracod diversity data from several regions shows a remarkable increase during the Darriwilian. Based on the regions studied herein, this rise in diversity is decoupled from the environmental expansion of ostracods, as they were already recorded along the onshore–offshore profile early in their history on both siliciclastic and carbonate shelves. The Argentine Cordillera Oriental could be considered as a cradle of diversity, with an important role in the subsequent radiation of the group.

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The Ordovician ocean circulation: a modern synthesis based on data and models

Pohl

Nardin

Vandenbroucke

et al. 2022

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Surface currents constitute an efficient transport agent for (larvae of) marine faunas, while the circulation of water masses in the ocean interior drives nutrient redistribution, ventilates the ocean and contributes to shaping surface biological productivity and the benthic redox landscape. Therefore, a robust understanding of ocean circulation, both shallow and deep, and of its response to climate change, is required to interpret paleobiogeographic signals, biological productivity patterns and biodiversity trends. This is especially critical during periods of dynamic biological change, such as the Ordovician. Yet, oceanic circulation patterns leave no direct evidence in the geological record and can therefore be reconstructed solely based on indirect indicators, such as the distribution of faunas and geochemical proxies. General circulation models offer independent, physically robust insights onto the coupling between climate change and ocean circulation. Integrated approaches based on the assimilation of geological data in numerical models thus constitute a promising way forward. We here provide a literature review and updated synthesis of the current understanding of the Ordovician ocean circulation, based on data and models.

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BroeggeriaWalcott and other upper Cambrian and Tremadocian linguloid brachiopods from NW Argentina

Cited by 3 publications

References 60 publications

A Cambrian–Ordovician boundary section in the Rafnes–Herøya submarine tunnel, Skien–Langesund District, southern Norway

A Cambrian–Ordovician boundary section in the Rafnes–Herøya submarine tunnel, Skien–Langesund District, southern Norway

Radiation, diversity and environmental expansion of Early Ordovician ostracods: a view from the Southern Hemisphere

The Ordovician ocean circulation: a modern synthesis based on data and models

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