Biozonation of the Furongian (upper Cambrian) Alum Shale Formation at Hunneberg, Sweden

Preservation of soft integument in calcareous nodules seems to be more widespread geographically and stratigraphically than hitherto realized. It cannot be recognized in the field, and to recover such material requires special etching techniques. Such preservation can be of exceptional quality, with fossils preserved three dimensionally either by secondary phosphatization or by silicification. Coating as well as the replacement of integument has been observed even within the same sample. Methodical search for such preservation may be based on the common denominators of depositional, geochemical, and environmental indicators in previously described occurrences. As such exceptionally preserved material may be rare within the samples, large quantities of rock have to be prepared. The examples described here are from anthraconitic limestones (Orsten) of the Upper Cambrian Alum Shale Formation in Sweden. They are now known from many localities and from different trilobite zones. In addition nodules from the Lower Cretaceous Santana Formation in Brazil, the Upper Devonian cephalopod limestone in the Carnic Alps, the Lower Triassic of Spitzbergen and the Miocene Barstow Formation in California have all yielded extremely fine material.

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Yuepingia? sp., a ceratopygid trilobite from the upper Cambrian (Furongian) of Scandinavia

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2010-58-03 ◽

2010 ◽

Vol 58 ◽

pp. 29-33

Author(s):

Thomas Weidner ◽

Arne Thorshøj Nielsen

Keyword(s):

East Coast ◽

Upper Cambrian ◽

South Central ◽

Alum Shale ◽

Shale Formation

A single pygidium found in an ice-rafted loose boulder of coquinoid bituminous limestone represents an ‘exotic’ trilobite hitherto unknown from the Scandinavian Alum Shale Formation. The limestone, found on the east coast of Jutland, Denmark, also contains Leptoplastus paucisegmentatus, Parabolina spinulosa and Orusia lenticularis and derives from the upper Cambrian (Furongian) Leptoplastus paucisegmentatus Zone of Västergötland, south-central Sweden. The ‘exotic’ pygidium shows closest resemblance to the ceratopygid Yuepingia glabra, described from Alaska, and is treated as Yuepingia? sp. The Laurentian Y. glabra occurs in the Ptychaspis-Prosaukia Zone which corresponds in age to the Scandinavian Leptoplastus Superzone.

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Furongian (upper Cambrian) trilobites and agnostoids from the Alum Shale Formation of Bornholm, Denmark: revised taxonomy and biostratigraphy

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2021-69-08 ◽

2021 ◽

Vol 32 ◽

pp. 123-213

Author(s):

Arne Thorshøj Nielsen ◽

Line Frigaard Andersen

Keyword(s):

New Species ◽

Natural History ◽

Natural History Museum ◽

Basal Part ◽

History Museum ◽

Upper Cambrian ◽

Alum Shale ◽

Cambrian Trilobite ◽

Shale Formation ◽

One New Species

The Furongian (upper Cambrian) trilobite-agnostoid fauna from the Alum Shale Formation of Bornholm, Denmark, is reviewed and revised. The study is based on the museum material stored at the Natural History Museum of Denmark, including the material originally monographed by C. Poulsen (1923) [Bornholms Olenuslag og deres fauna. Danmarks Geologiske Undersøgelse II. Række, Vol. 40, 83 pp]. A total of 8502 specimens, mostly disarticulated sclerites, have been registered. The taxonomy of all species is updated and the best preserved specimens are illustrated. A total of 39 olenid and 5 agnostoid taxa (incl. the Miaolingian Agnostus pisiformis) are recorded including one new species, Ctenopyge magna n. sp. Two specimens of Ctenopyge, treated in open nomenclature as Ctenopyge sp. 1 and sp. 2, may also rep-resent new species. 14 taxa have not been previously reported from Bornholm, viz. Ctenopyge ahlbergi, Ctenopyge tumidoides, Eurycare brevicauda, Leptoplastus abnormis, Leptoplastus crassicornis, Olenus transversus, Parabolina lobata praecurrens, Peltura acu-tidens, Peltura minor, Peltura westergaardi, Protopeltura planicauda, Protopeltura praecursor, Pseudagnostus leptoplastorum? and Sphaerophthalmus drytonensis. Ctenopyge pecten and Ctenopyge affinis are also new to Bornholm as the material formerly described under these names represent Ctenopyge tenuis and C. magna n. sp., respectively. Lotagnostus americanus, Ctenopyge fletcheri, Sphaerophthalmus alatus and Triangulopyge humilis were described under different names by C. Poulsen (1923). Peltura westergaardi and Ctenopyge tenuis are elevated from subspecies to species rank. A redescription of Leptoplastus bornholmensis is presented; the species is transferred to Eurycare. The identification of isolated skeletal parts of L. abnormis and Leptoplastus ovatus and Sphaerophthalmus flagellifer and S. drytonensis are remarked on. The presence of three agnostoid and 14 trilobite zones is confirmed by fossils and all six Furongian superzones are developed on Bornholm. At least the Leptoplastus paucisegmentatus and Leptoplastus raphidophorus zones seem to be absent. Other undocumented zones may be unfossiliferous, not exposed or truly absent. Three different trilobite assemblages (potential subzones) are discerned in the Peltura acu-tidens–Ctenopyge tumida Zone; Ctenopyge tumidoides and Sphaerophthalmus angustus range into the basal part of this zone. All exposures of the Furongian Alum Shale Formation along the Læså and Øleå streams on southern Bornholm are briefly described including GPS coordinates.

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Biostratigraphy of the Furongian (upper Cambrian) Alum Shale Formation at Degerhamn, Öland, Sweden

GFF ◽

10.1080/11035897.2016.1276099 ◽

2017 ◽

Vol 139 (2) ◽

pp. 92-118 ◽

Cited By ~ 5

Author(s):

Bo W. Rasmussen ◽

Jan A. Rasmussen ◽

Arne T. Nielsen

Keyword(s):

Upper Cambrian ◽

Alum Shale ◽

Shale Formation

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Effects of inherent pyrite on hydrocarbon generation by thermal pyrolysis: An example of low maturity type-II kerogen from Alum shale formation, Sweden

Fuel ◽

10.1016/j.fuel.2021.122865 ◽

2022 ◽

Vol 312 ◽

pp. 122865

Author(s):

Kang Li ◽

Zhongfeng Zhao ◽

Hong Lu ◽

Xinran Liu ◽

Ping'an Peng ◽

...

Keyword(s):

Hydrocarbon Generation ◽

Type Ii ◽

Thermal Pyrolysis ◽

Alum Shale ◽

Shale Formation ◽

Maturity Type

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Orientation of agnostid shields in Alum Shale (Upper Cambrian): Implications for the depositional environment

GFF ◽

10.1080/11035899901214301 ◽

1999 ◽

Vol 121 (4) ◽

pp. 301-306 ◽

Cited By ~ 11

Author(s):

Johan Eklöf ◽

Jens Rydell ◽

Jemima Fröjmark ◽

Maria Johansson ◽

Adolf Seilacher

Keyword(s):

Depositional Environment ◽

Upper Cambrian ◽

Alum Shale

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Skeletal carbonate productivity and phosphogenesis at the lower–middle Cambrian transition of Scania, southern Sweden

Geological Magazine ◽

10.1017/s0016756809990021 ◽

2009 ◽

Vol 147 (1) ◽

pp. 59-76 ◽

Cited By ~ 14

Author(s):

J. JAVIER ÁLVARO ◽

PER AHLBERG ◽

NIKLAS AXHEIMER

Keyword(s):

Primary Productivity ◽

Microbial Mats ◽

High Energy ◽

Nutrient Supply ◽

Energy Conditions ◽

Southern Sweden ◽

Middle Cambrian ◽

Alum Shale ◽

Shale Formation ◽

Reducing Environment

AbstractThe lower–middle Cambrian transitional interval of Scania is largely represented by condensed limestone beds, lithostratigraphically grouped in the Gislöv Formation (1–5.7 m thick), and the Forsemölla and Exsulans Limestone beds (lower part of the Alum Shale Formation, up to 4 m thick). The strata display a combination of skeletal carbonate productivity, episodic nucleation of phosphate hardground nodules, and polyphase reworking recorded on a platform bordering the NW corner of Baltica. The shell accumulations can be subdivided into three deepening-upward parasequences, separated by distinct erosive unconformities. The parasequences correspond biostratigraphically to the Holmia kjerulfi, Ornamentaspis? linnarssoni and Ptychagnostus gibbus zones, the latter two generally being separated by a stratigraphic gap that includes the middle Cambrian Acadoparadoxides oelandicus Superzone. Except for the Exsulans Limestone, the carbonates reflect development of a prolific epibenthic biota, dominated by filter-feeding nonreefal chancelloriid–echinoderm–sponge meadows, rich in trilobites and brachiopods, and which were subjected to high-energy conditions. The absence of microbial mats or veneers encrusting the erosive surfaces of these event-concentration low-relief shoal complexes may be related to long hiatal episodes resulting in microboring proliferation. High levels of nutrient supply resulted in high primary productivity, eutrophic conditions, glauconite precipitation, phosphogenesis (in some case microbially mediated) and microendolithic infestation. An early-diagenetic mildly reducing environment is suggested by the presence of authigenic (subsequently reworked) pyrite, which contrasts with the syndepositional normal oxygenated conditions reflected by macroburrowing and the abundance of benthic fossils.

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Anopolenus henrici Salter, a middle Cambrian (Drumian) centropleurid trilobite from the Alum Shale Formation of Scandinavia

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2018-66-13 ◽

2018 ◽

Vol 66 ◽

pp. 223-228

Author(s):

Thomas Weidner ◽

Jan Ove R. Ebbestad

Keyword(s):

Middle Cambrian ◽

Alum Shale ◽

Shale Formation

Centropleurid trilobites include five genera of which Centropleura Angelin, Anopolenus Salter, Clarella Howell and Luhops Šnajdr are known from eight species in the traditional middle Cambrian (Miaolingian Series, Drumian Stage) of Sweden and Denmark (Bornholm). Beishanella Xiang & Zhang has not been recorded in Scandinavia so far, and no centropleurids have been reported from Norway. Of these taxa, only Centropleura is common in Scandinavia. Two pygidia previously identified as Centropleura sp. and Anopolenus sp. from erratics in Germany and Bornholm, respectively, as well as a new pygidum from Scania in Sweden are here identified as Anopolenus henrici Salter. Elsewhere, the species is known from Wales, Avalonian Canada, Siberia, Alaska, and Sardinia, occurring in the A. atavus and P. punctuosus zones (the former in Siberia only). The presence of this species increases the known diversity of Centropleuridae in Scandinavia and is important for correlation between Baltica and Avalonia.

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Stratigraphy and geochemical composition of the Cambrian Alum Shale Formation in the Porsgrunn core, Skien–Langesund district, southern Norway.

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2018-66-01 ◽

2018 ◽

Vol 66 ◽

pp. 1-20

Author(s):

Niels Hemmingsen Schovsbo ◽

Arne Thorshøj Nielsen ◽

Andreas Olaus Harstad ◽

David L. Bruton

Keyword(s):

Gamma Ray ◽

Geochemical Composition ◽

Middle Cambrian ◽

Alum Shale ◽

Carbon Isotope Excursion ◽

Lower Ordovician ◽

Shale Formation ◽

Sedimentary Succession ◽

Southern Norway ◽

Spice Event

The fully cored BHD-03-99 borehole (hereafter referred to as the Porsgrunn borehole and core) penetrated Ordovician and Cambrian strata in the Skien–Langesund district, southern part of the Oslo region in Norway. Hand-held X-ray fluorescence (HH-XRF) measurements combined with spectral gamma ray and density core scanning of the Middle Cambrian – Furongian Alum Shale Formation have been made and compared with similar measurements obtained on Alum Shale cores from Scania (southernmost Sweden) and Bornholm (Denmark). The Porsgrunn drill site is located in an area that was only mildly overprinted by Caledonian tectonics and represents one of the few sites in the Oslo area where a nearly untectonised sedimentary succession can be studied in terms of thickness and geochemistry. The Alum Shale Formation is 28.8 m thick in the Porsgrunn core, excluding the thickness of five 0.9–5.5 m thick dolerite sills of assumed Permian age. In the Alum Shale Formation the bulk densities are around 2.7 g/cm3 with a slightly decreasing trend up through the formation. The shale has total organic carbon (TOC) values up to 14 wt%, which is comparable to the TOC levels for the Alum Shale elsewhere in the Oslo area and for dry gas matured Alum Shale in Scania and Bornholm. The basal Furongian is characterised by a gamma ray low and an increase in Mo interpreted to reflect the Steptoean Positive Carbon Isotope Excursion (SPICE) event. The Porsgrunn core data suggest that the Mo concentration remained high also after the SPICE event. Characteristic, readily identified features in the gamma log motif are named the Andrarum gamma low (AGL), base Furongian gamma low (BFGL), Olenus triple gamma spike (OTGS) and the Peltura gamma spike (PGS). No Lower Ordovician Alum Shale is present. The 14.8 m thick Furongian part of the Alum Shale represents the Olenus, Parabolina, Leptoplastus, Protopeltura and Peltura trilobite superzones judging from log-stratigraphic correlations to Scania and Bornholm. The Middle Cambrian interval is 14.0 m thick and includes the Exsulans Limestone Bed and 1.4 m of quartz sandstone. A 0.3 m thick primary limestone bed may be an equivalent to the Andrarum Limestone Bed. The succession represents the Paradoxides paradoxissimus and P. forchhammeri superzones. The Alum Shale Formation rests atop the 13.0 m thick Lower Cambrian Stokkevannet sandstone (new informal name) that in turn directly overlies the basement. Overall, the stratigraphic development of the comparatively thin Alum Shale Formation resembles the condensed sequence seen on Bornholm.

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