Eustatic and local tectonic impact on the Late Ordovician – early Silurian facies evolution on the SW margin of peri-Baltica (the southern Holy Cross Mountains, Poland)

2021 ◽  
pp. 1-15
Author(s):  
Wiesław Trela
Keyword(s):  
Late Ordovician ◽  
Coarse Grained ◽  
Upper Ordovician ◽  
Sedimentary Record ◽  
Trade Winds ◽  
Sedimentary Environments ◽  
Holy Cross Mountains ◽  
Se Poland ◽  
Clastic Sediments ◽  
Insight Into

Abstract This paper provides insight into the Late Ordovician to earliest Silurian evolution of sedimentary environments in the southern Holy Cross Mountains (SE Poland), which at that time were a part of the SW periphery of Baltica. The facies layout in this area was influenced by the basement block faulting, which differentiated the basin bathymetry into submarine horst and grabens, controlling facies distribution. However, the local tectonism was insufficient to fully mask the global eustatic events. Therefore, it is possible to correlate some facies changes in the Upper Ordovician and lower Llandovery sedimentary record of the southern Holy Cross Mountains with eustatic and palaeoceanographic changes reported worldwide. The most noticeable influence of eustasy on the sedimentary record in the studied area occurs at the Ordovician/Silurian boundary. It is manifested by Hirnantian regressive coarse-grained clastic sediments overlain by a post-glacial anoxic/dysoxic interval represented by the Rhuddanian transgressive black cherts and shales. It is noteworthy that the pre- and post-Hirnantian sedimentary environments in the southern Holy Cross Mountains were affected by upwelling induced by the SE trade winds.

Paleoecology of commensal epizoans fouling Flexicalymene (Trilobita) from the Upper Ordovician, Cincinnati Arch region, USA

2010 ◽  
Vol 84 (6) ◽  
pp. 1121-1134 ◽  
Author(s):  
Marcus M. Key ◽  
Gregory A. Schumacher ◽  
Loren E. Babcock ◽  
Robert C. Frey ◽  
William P. Heimbrock ◽  
...  
Keyword(s):  
Water Column ◽  
Life Style ◽  
Late Ordovician ◽  
Hard Substrate ◽  
Upper Ordovician ◽  
Sea Floor ◽  
Life Habits ◽  
Observational Bias ◽  
Fouling Organisms ◽  
Insight Into

Commensal epizoozoans and episkeletozoans are rarely preserved attached to the external exoskeleton of the Late Ordovician trilobite Flexicalymene. Of nearly 15,000 Flexicalymene specimens examined, 0.1% show epizoozoans or episkeletozoans. Factors limiting Flexicalymene fouling include a shallow burrowing life style, frequent molting of the host, larval preference for other substrates, observational bias caused by overlooking small fouling organisms, and the loss of the non-calcified, outermost cuticle prior to fossilization or as the trilobite weathers from the encasing sediment. Trepostome bryozoans, articulate and inarticulate brachiopods, cornulitids, and a tube-dwelling/boring nonbiomineralized organism represent the preserved members of the Late Ordovician marine hard substrate community fouling Flexicalymene. This assemblage of organisms is less diverse than the hard substrate community fouling Late Ordovician sessile epibenthic organisms. Fouling is not restricted to only large Flexicalymene specimens as observed in previous studies but occurs in medium to large individuals interpreted as early to late holaspid specimens.Epizoozoans fouling the carcasses or molt ensembles of 16 Flexicalymene specimens provide insight into the life habits of the host and these fouling organisms. Trepostome bryozoans, articulate and inarticulate brachiopods, and cornulitids preferentially attached to elevated portions of the dorsal exoskeleton, and preferentially aligned in either the direct line or lee side of currents generated by Flexicalymene walking on the sea floor or swimming through the water column.

scholarly journals New Recent foraminiferal genera and species from the lagoon at Madang, Papua New Guinea

1992 ◽  
Vol 11 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Martin R. Langer
Keyword(s):  
New Species ◽  
Shallow Water ◽  
Papua New Guinea ◽  
New Guinea ◽  
Coarse Grained ◽  
New Genera ◽  
Low Oxygen ◽  
Shell Surface ◽  
Sedimentary Environments ◽  
Tropical Lagoon

Abstract. Two new genera and eight new species of benthic foraminifera are described from the shallow water, tropical lagoon of Madang, Papua New Guinea. The new hauerinid genus Pseudolachlanella is characterized by juvenile cryptoquinqueloculine, adult almost massiline arranged chambers, and a slitlike, curved aperture with parallel sides and a long, slender, curved miliolid tooth. Pitella haigi n. gen., n. sp. is a new foraminifera with cryptoquinqueloculine arranged chambers, an almost entirely pitted shell surface (pseudopores) and a rounded aperture with a short simple tooth. Among the other species described as new are four hauerinids and two agglutinated foraminifera All new species described here occur sporadically in the shallow water back- and forereef environments of the lagoon (0–55m), and live infaunally and epifaunally in well-oxygenated, fine and coarse grained biogenic sediments. They are absent in muddy, organic-rich, low-oxygen sedimentary environments within bay inlets where variations of salinity are considerable.

Katian (Late Ordovician) conodonts on the northwestern margin of the North China Craton

2021 ◽  
pp. 1-22
Author(s):  
Zhihua Yang ◽  
Xiuchun Jing ◽  
Hongrui Zhou ◽  
Xunlian Wang ◽  
Hui Ren ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Late Ordovician ◽  
Carbonate Platforms ◽  
Upper Ordovician ◽  
The North ◽  
Low Latitudes ◽  
Northwestern Margin ◽  
Conodont Fauna ◽  
Stratigraphic Range

Abstract Upper Ordovician strata exposed from the Baiyanhuashan section is the most representative Late Ordovician unit in the northwestern margin of the North China Craton (NCC). In total, 1,215 conodont specimens were obtained from 24 samples through the Wulanhudong and Baiyanhuashan formations at the Baiyanhuashan section. Thirty-six species belonging to 17 genera, including Tasmanognathus coronatus new species, are present. Based on this material, three conodont biozones—the Belodina confluens Biozone, the Yaoxianognathus neimengguensis Biozone, and the Yaoxianognathus yaoxianensis Biozone—have been documented, suggesting that the Baiyanhuashan conodont fauna has a stratigraphic range spanning the early to middle Katian. The Baiyanhuashan conodont fauna includes species both endemic to North China and widespread in tropical zones, allowing a reassessment of the previous correlations of the Katian conodont zonal successions proposed for North China with those established for shallow-water carbonate platforms at low latitudes. UUID: http://zoobank.org/7cedbd4a-4f7a-4be6-912f-a27fd041b586

scholarly journals Effect of Hydrothermal Activity on Organic Matter Enrichment of Shale: A Case Study of the Upper Ordovician and the Lower Silurian in the Lower Yangtze, South China

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 495 ◽  
Author(s):  
Yizhou Huang ◽  
Zhenxue Jiang ◽  
Kun Zhang ◽  
Yan Song ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Oxygen Isotope ◽  
Shale Gas ◽  
Organic Matter Content ◽  
Hydrothermal Activity ◽  
Late Ordovician ◽  
Sedimentary Organic Matter ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Activity Intensity

The effect of organic matter on hydrocarbon potential, storage space, and gas content of shale is well-known. Additionally, present-day content of sedimentary organic matter in shale is controlled by depositional and preservation processes. Therefore, a study of the enrichment mechanisms of sedimentary organic matter provides a scientific basis for the determination of favorable areas of shale gas. In this study the Upper Ordovician Xinkailing Fm. and the first member of the Lower Silurian Lishuwo Fm. were examined. Stratigraphic sequences were identified through conventional logs and elemental capture spectrum data. Oxygen isotope analysis was applied to recover paleotemperature of seawater in the study area. The excess silicon content was calculated and the origin of the silica was determined by the Fe-Al-Mn ternary plot. The enrichment mechanism of organic matter was analyzed by two aspects: redox conditions and paleoproductivity. As a result, the stratigraphic interval was divided into two 3rd-order sequences. Through oxygen isotope, the paleotemperature of seawater was 62.7–79.2 °C, providing evidence of the development of hydrothermal activity. Analysis of excess siliceous minerals identified two siliceous mineral origins: terrigenous and hydrothermal. It also revealed an upwards decreasing tendency in hydrothermal activity intensity. Strong hydrothermal activity during the Late Ordovician, recognized as TST1, formed a weak-oxidizing to poor-oxygen environment with high paleoproductivity, which promoted organic matter enrichment. During the Late Ordovician to the Early Silurian, identified as RST1, TST2, and RST2, weakening hydrothermal activity caused the decline of paleoproductivity and increased oxidation of bottom waters, leading to a relative decrease of organic matter content in the shale. Therefore, favorable areas of shale gas accumulation in the Upper Ordovician and Lower Silurian are determined stratigraphically as the TST1, with a high total organic carbonate content. Geographically, the hydrothermally-active area near the plate connection of the Yangtze and the Cathaysian is most favorable.

Postembryonic development of Dalmanitina, and the evolution of facial suture fusion in Phacopina

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 638-659
Author(s):  
Harriet B. Drage ◽  
Lukáš Laibl ◽  
Petr Budil
Keyword(s):  
Fossil Record ◽  
Postembryonic Development ◽  
Large Sample Size ◽  
Upper Ordovician ◽  
Geological Time ◽  
Fusion Event ◽  
Large Sample ◽  
Prague Basin ◽  
Suture Fusion ◽  
Insight Into

AbstractA large sample of postembryonic specimens of Dalmanitina proaeva elfrida and D. socialis from the Upper Ordovician (Sandbian to Katian) Prague Basin allows for the first reasonably complete ontogenetic sequence of Dalmanitoidea (Phacopina). The material provides an abundance of morphological information, including well-preserved marginal spines in protaspides and meraspides, and hypostome external surfaces throughout. The development of D. proaeva elfrida is unusual due to variability in timing of the first trunk articulation. This broadens our developmental understanding of Phacopina, a diverse group of phacopid trilobites, and also allows us to study the evolution of their specializations in exoskeletal molting behavior. Adult phacopines, unlike most other trilobites, had fused facial sutures. This means that rather than molting through the sutural gape mode, characterized by opening of the facial sutures and separation of the librigenae, they disarticulated the entire cephalon in Salter’s mode of molting. For other phacopine clades (Phacopoidea) the transition to Salter’s mode occurs during the meraspid period or at the onset of holaspis, and its developmental timing is intraspecifically fixed. However, owing to the large sample size, we can see that facial suture fusion likely occurred later in Dalmanitina, usually during the holaspid period, and was intraspecifically variable with holaspides of varying sizes showing unfused sutures. Further, D. proaeva elfrida specimens showed an initial librigenal–rostral plate fusion event, where the librigenae began as separate entities but appear fused with the rostral plate as one structure (the “lower cephalic unit”) from M1, and are discarded as such during molting. Dalmanitoidea is considered to represent the first phacopine divergence, occurring earliest in the fossil record. This material therefore provides insight into how linked morphologies and behaviors evolved, potentially suggesting the timing of facial suture fusion in Phacopina moved earlier during development and became more intraspecifically fixed over geological time.

scholarly journals The specificity of paleocoenosis and a trophic structure of the Upper Ordovician Bol’shaya Kos’yu reef (Northern Urals)

2020 ◽  
Author(s):  
L. A. Shmeleva ◽  
Keyword(s):  
Trophic Structure ◽  
Active Participation ◽  
Late Ordovician ◽  
Close Connection ◽  
Upper Ordovician ◽  
Northern Urals ◽  
Leading Role ◽  
Microbial Organisms

The study of the spatial-temporal and paleoecological structures of the paleocenoses of the Bolshaya Kosyu reef showed that the sphinctozoic sponges Amblysiphonelloides reticulata Rigby & Potter, 1986 and Corymbospongia sp. starting from the late Ordovician could settle in sublittoral environments with active hydrodynamics in close connection with cyanobacteria, which played a leading role in the functioning of the trophic structure of this ecosystem. Fossilized biofilms and glycocalyx, tubular and worm-like bacteriomorphs found on the surface of sponges are evidence of active participation of microbial organisms in the life of sphinctozoal sponges.

scholarly journals Dilute Solution Structure of Bottlebrush Polymers

2019 ◽  
Author(s):  
Sarit Dutta ◽  
Matthew A. Wade ◽  
Dylan J. Walsh ◽  
Damien Guironnet ◽  
Simon A. Rogers ◽  
...  
Keyword(s):  
Brownian Dynamics ◽  
Solution Structure ◽  
Coarse Grained ◽  
Poly Lactic Acid ◽  
Linear Polymers ◽  
Molecular Architecture ◽  
Wide Range ◽  
Conformational Properties ◽  
Atomistic Structure ◽  
Insight Into

<div>Bottlebrush polymers are a class of macromolecules that has recently found use</div><div>in a wide variety of materials, ranging from lubricating brushes and</div><div>nanostructured coatings to elastomeric gels that exhibit structural color. These</div><div>polymers are characterized by dense branches extending from a central backbone,</div><div>and thus have properties distinct from linear polymers. It remains a challenge</div><div>to specifically understand conformational properties of these molecules, due to</div><div>the wide range of architectural parameters that can be present in a system, and</div><div>thus there is a need to accurately characterize and model these molecules. In</div><div>this paper, we use a combination of viscometry, light scattering, and computer</div><div>simulations to gain insight into the conformational properties of dilute</div><div>bottlebrush polymers. We focus on a series of model bottlebrushes consisting of</div><div>a poly(norbornene) (PNB) backbone with poly(lactic acid) (PLA) side chains. We</div><div>demonstrate that intrinsic viscosity and hydrodynamic radius are experimental</div><div>observations \emph{sensitive} to molecular architecture, exhibiting distinct</div><div>differences with different choices of branch and backbone lengths. Informed by</div><div>the atomistic structure of this PNB-PLA system, we rationalize a coarse-grained</div><div>simulation model that we evaluate using a combination of Brownian Dynamics and</div><div>Monte Carlo simulations. We show that this exhibits quantitative matching to</div><div>experimental results, enabling us to characterize the overall shape of the</div><div>bottlebrush via a number of metrics that can be extended to more general</div><div>bottlebrush architectures.</div>

scholarly journals Upper Ordovician graptolites from the Cape Phillips Formation, Canadian Arctic Islands

1987 ◽  
Vol 35 ◽  
pp. 191-202
Author(s):  
M. J. Melchin
Keyword(s):  
Great Britain ◽  
Shallow Water ◽  
Depositional Environment ◽  
Canadian Arctic ◽  
Late Ordovician ◽  
Outer Shelf ◽  
Upper Ordovician ◽  
The World ◽  
Cape Phillips Formation ◽  
Varying Length

Ashgill age graptolites have been collected from seven sections of the Cape Phillips Formation across most of its outcrop belt. The earliest graptolite zone recognisable is that of Orthograptus fastigatus. It is correla­ted with the Dicellograptus ornatus · Zone of the northern Canadian Cordilllera and the Dicellograptus complexus Subzone of the Dicel/ograptus anceps Zone of Great Britain although no dicellograptids have been found at any of the present sections. The overlying zone is that of Paraorthograptus pacificus, an ea­sily recognisable zone around much of the world. Graptolites of the C/imacograptus extraordinarius and Glyptograptus persculptus zones appear to be en­tirely absent from this formation. This is attributed to the Late Ordovician glaciation which has induced regression and submarine erosion in many areas worldwide. The earliest recognisable Silurian zone varies from section to section due to buried or barren intervals and/or hiatuses of varying length. The Parakidograptus acuminatus Zone has been recognised at only one section. At the others, the Atavograptus atavus, the Lagarograptus acinaces-Coronograptus gregarius, the Monograptus convolutus or the Monograptus spiralis Zone (s.1.) are the earliest recognisable Silurian fau­nas. Relatively low fauna! diversities in the Ashgill and lowest Llandovery portion of the section and the to­tal lack of dicellograptids are interpreted to be due to relatively shallow water, outer shelf or carbonate ramp depositional environment.

The brachiopods Alwynella and Grorudia: homeomorphic plectambonitoids in the Middle and Upper Ordovician of Baltoscandia

2007 ◽  
Vol 98 (3-4) ◽  
pp. 271-280 ◽  
Author(s):  
Linda Hints ◽  
David A. T. Harper
Keyword(s):  
New Species ◽  
Baltic Sea ◽  
Late Ordovician ◽  
Drill Core ◽  
Upper Ordovician ◽  
The Baltic Sea ◽  
New Material ◽  
The Baltic ◽  
A New Species ◽  
Water Facies

ABSTRACTTwo Ordovician plectambonitoid genera, Alwynella and Grorudia, occur in drill core sections of Latvia in the East Baltic, and in exposures and loose blocks on the Swedish Island of Öland in the Baltic Sea. The new material confirms differences between the two taxa that are assigned herein to separate families, Alwynellidae fam. nov. and Grorudiidae Cocks & Rong, 1989. In particular, the undercut cardinalia separates Alwynella from Grorudia and indicates its proximity to the sowerbyellids. The genus Grorudia, which is externally similar to Alwynella, is more closely related to the palaeostrophomenines. A new species Grorudia morrisoni sp. nov. is established in the East Baltic. The specimens from Öland are included tentatively within the genus Grorudia due to lack of interiors. Both Alwynella and Grorudia were confined to deeper-water facies in the Baltic palaeobasin, within successions ranging in age from latest Mid (late Llanvirn) to earliest Late Ordovician (mid Caradoc).

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