Halysis Høeg, 1932 in Ordovician Carbonate Mounds, Tarim Basin, Nw China

Shen, Yuefeng; Neuweiler, Fritz

doi:10.2110/palo.2014.096

Cited by 8 publications

(18 citation statements)

References 33 publications

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“…Notably, the inferred green, dasycladacean algae were already present in the communities found at the base of Aferdou el Mrakib, whereas Rothpletzella , a potential cyanobacterium (cf., Riding, ), is found both at the pioneer stage and, occasionally, within the skeletons of the climax reef builders. This is accompanied by the local presence in the debris strata of mass accumulations of Halysis , a problematicum assigned to either red (Riding & Braga, ) or green algae (Shen & Neuweiler, ) and considered typical of relatively shallow‐water palaeoenvironments (Shen & Neuweiler, ).…”

Section: Discussionmentioning

confidence: 99%

“…((d)–(e)) Microphotograph of dense accumulations of the alga Halysis found in nodular carbonates in the distal part of the fore‐reef succession (see Figure b). Note the tripartite wall structure characteristic of the genus (cf., Shen & Neuweiler, ). (f) Intercalations of clay‐rich, off‐reef strata and biodetrital carbonates deposited by mass flow events.…”

Section: Reef Foundationmentioning

confidence: 99%

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At the southern limits of the Devonian reef zone: Palaeoecology of the Aferdou el Mrakib reef (Givetian, eastern Anti‐Atlas, Morocco)

et al. 2018

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Devonian reefs of north-western Gondwana represent the southernmost record of shallow-water coral reefs in the Palaeozoic. However, few studies have attempted to date palaeoecological reconstructions of these high-latitude reefal buildups. This study provides the first detailed palaeoecological analysis of Aferdou el Mrakib, an isolated, Givetian coral-stromatoporoid reef, which developed in a semirestricted basin in the south-eastern part of the Rheic Ocean. The study documents spatial facies variability and succession of faunal replacements accompanying progressive reef accretion towards the sea surface. The investigations included both autochthonous communities found at the base of the reef and, partially, within the reef core, and allochthonous deposits of reef-derived skeletal debris that accumulated in the fore-reef setting. Contrary to some previous suggestions, the study shows that the Aferdou reef shared many characteristics of classical Middle Devonian coral-stromatoporoid buildups, including the ecological succession, limited role of calcareous algae, and development within the range of the euphotic zone, but likely below the zone of regular water agitation. Critical factors in the facies development and temporal changes in the character of reef building were the palaeobathymetry, dominant sedimentary and circulation regimes, level of wave energy, and, possibly, light availability. Distinctive features of the palaeoecology of Aferdou el Mrakib are the dominance of massive colonies of heliolitid tabulates and a subordinate role of massive stromatoporoids, both explained here primarily as a result of increased water turbidity in the high-latitude sedimentary basin.The growth of the high-latitude coral-stromatoporoid reefs in the south-eastern Rheic Ocean was favoured by a combination of the exceptionally warm climate and plate tectonic configuration typifying the Devonian. Of critical importance appears the palaeogeographic position of the Rheic, which resulted in the seawater circulation in the ocean being dominated by tropical water masses, with restricted inflow of cold water from the circumpolar oceanic circulation.

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Section: Discussionmentioning

confidence: 99%

Section: Reef Foundationmentioning

confidence: 99%

At the southern limits of the Devonian reef zone: Palaeoecology of the Aferdou el Mrakib reef (Givetian, eastern Anti‐Atlas, Morocco)

et al. 2018

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“…(B) Detailed view of study area with location of stratigraphic sections (numbers for internal use). Geological map of the Dawuzitag–Leyayilitag Ridge redrawn from Shen & Neuweiler (). (C) Lithostratigraphic and biostratigraphic subdivision of the Lower to Middle Ordovician sequence.…”

Section: Study Area and Stratigraphymentioning

confidence: 99%

“…Early to Middle Ordovician carbonate build‐ups recorded the transition from the late Cambrian (Furongian) siliceous sponge–microbial benthic community associated with calcimicrobes such as Girvanella , Renalcis and Epiphyton (Lee et al ., ; Coulson & Brand, ) towards the Palaeozoic benthic community representing a very first assemblage of clonal, massive to sheet‐forming metazoan skeletons (bryozoans, corals and coralline sponges). This Palaeozoic diversification of metazoan skeletogenesis (Porter, ) is associated with a rapidly evolving Ordovician flora consisting of green and red calcareous algae, as well as new calcimicrobes such as Wetheredella and Rothpletzella (Chuvashov & Riding, ; Alberstadt & Repetski, ; Brunton & Dixon, ; Zhuravlev, ; Webby, ; Shen & Neuweiler, , ).…”

Section: Introductionmentioning

confidence: 99%

Questioning the microbial origin of automicrite in Ordovician calathid–demosponge carbonate mounds

Shen

Neuweiler

2017

Sedimentology

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Calathid-demosponge carbonate mounds are a feature of Early to Middle Ordovician shallow-marine carbonate depositional environments of tropical to subtropical palaeolatitudes. These mounds contain an important amount of autochthonous non-skeletal microcrystalline calcium-carbonate (automicrite) conventionally considered microbial in origin. Here, the automicrite of calathid-demosponge carbonate mounds (Tarim Basin, north-west China) is broken down into five distinct fabrics: an in situ peloidal-spiculiferous fabric (AM-1), an in situ peloidal fabric (AM-2), an aphanitic-microtubular fabric (AM-3), a minipeloidal fabric (AM-4) and a laminoid-cerebroid fabric (AM-5). Type AM-1 occurs with AM-2 being succeeded by an assemblage of AM-3 and AM-4. Types AM-4 and AM-5 are separated by an erosional disconformity. A good correlation of fluorescence and cathodoluminescence of automicrites indicates that induced and supported organomineralization produced automicrite, probably via the permineralization of non-living organic substrates adsorbing dissolved metal-humate complexes. Using a spreadsheet with six parameters and 17 characters, AM-1 to AM-4 turn out to be non-microbial in origin. Instead, these automicrites represent relics of calcified metazoan tissues, such as siliceous sponges, non-spiculate sponges or the basal attachment structures of stalked invertebrates. Fabric AM-5 is a microbial carbonate but is post-mound in origin forming a drape within a reefal framework established by AM-4. The five automicritic fabrics, individually or as an assemblage, are a common element of Ordovician calathiddemosponge carbonate mounds in general. The reassessment of the origins of these automicritic fabrics holds consequences for understanding of the Great Ordovician Biodiversification Event in terms of community structure, reef ecology and reef evolution. Episodically, these fabrics are also present in other carbonate build-ups stretching from the Neoproterozoic over the entire Phanerozoic Eon. The massive calcification of metazoan soft tissue (AM-1 to AM-4) characterizes episodes and conditions of enhanced marine calcification and might be of value to refine secular trends of pCO 2 , Ca concentration and Mg/Ca ratio at the scale of individual sedimentary basins.

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“…Halysis Høeg 1932 is a problematic calcareous microfossil occurring commonly in Early-to Mid-Paleozoic carbonate rocks (Shen and Neuweiler 2015). It has been reported from shallow marine limestones of the Lower Ordovician to Devonian Systems (Guilbault et al 1976;Poncet 1986;Mamet and Shalaby 1995;Munnecke et al 2001;Riding and Braga 2005;Feng et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Halysis Høeg, 1932 — an ancestral tabulate coral from the Ordos Basin, North China

Zheng

Jiang

et al. 2020

J. Palaeogeogr.

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The problematic calcareous microfossil Halysis is abundant in the Middle Ordovician Darriwilian Stage of the western edge of the Ordos Basin, North China. The rich and well-preserved specimens of Halysis in this area facilitate detailed studies for its skeletal construction and tube microstructure. Halysis differs from calcified cyanobacteria and calcareous red and green algae in morphology, skeletal construction and microstructure, as well as reproduction mode. Halysis typically consists of multiple juxtaposed parallel tubes arranged in sheets (‘multiple-tube’ type) or is just composed of one tube (‘single-tube’ type). In ‘multiple-tube’ Halysis, tube fission by bifurcation results from the insertion of a microcrystalline wall at the center of a mother tube. This study demonstrates for the first time that the tube walls of Halysis have a laminofibrous (fibronormal) microstructure, composed of fibrous calcite perpendicular to wall surface, and recognizes the ‘single-tube’ type Halysis composed of one tube; in addition, for the first time, this study finds out that ‘multiple-tube’ Halysis develops buddings from the conjunction of two tubes and ‘single-tube’ Halysis shows wide-angle Y-shaped branchings. Based on these findings, this study further compares Halysis with tabulate corals. Halysis appears stratigraphically earlier than Catenipora and Aulopora, and has a smaller tube size. ‘Multiple-tube’ Halysis resembles Catenipora and ‘single-tube’ Halysis resembles Aulopora in skeletal construction and microstructure, and in their tube walls of laminofibrous microstructure composed of fibrous calcite perpendicular to the tube wall surface. Catenipora and Halysis are both characterized by the absence of septal spines. The similarities suggest that Halysis may be the ancestor of Catenipora-like and Aulopora-like tabulate corals.

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Halysis Høeg, 1932 in Ordovician Carbonate Mounds, Tarim Basin, Nw China

Cited by 8 publications

References 33 publications

At the southern limits of the Devonian reef zone: Palaeoecology of the Aferdou el Mrakib reef (Givetian, eastern Anti‐Atlas, Morocco)

At the southern limits of the Devonian reef zone: Palaeoecology of the Aferdou el Mrakib reef (Givetian, eastern Anti‐Atlas, Morocco)

Questioning the microbial origin of automicrite in Ordovician calathid–demosponge carbonate mounds

Halysis Høeg, 1932 — an ancestral tabulate coral from the Ordos Basin, North China

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