High-resolution conodont biostratigraphy from the Darriwilian Stage (Middle Ordovician) of the Argentine Precordillera and biodiversity analyses: a CONOP9 approach

Lethaia ◽  
2018 ◽  
Vol 52 (2) ◽  
pp. 188-203 ◽  
Author(s):  
Fernanda Serra ◽  
Nicolás A. Feltes ◽  
Guillermo L. Albanesi ◽  
Daniel Goldman
Keyword(s):  
High Resolution ◽  
Conodont Biostratigraphy ◽  
Middle Ordovician ◽  
Argentine Precordillera

Integrated conodont biostratigraphy and carbon isotope chemostratigraphy in the Lower–Middle Ordovician of southern Sweden reveals a complete record of the MDICE

2016 ◽  
Vol 154 (2) ◽  
pp. 334-353 ◽  
Author(s):  
RONGCHANG WU ◽  
MIKAEL CALNER ◽  
OLIVER LEHNERT
Keyword(s):  
North America ◽  
Carbon Isotope ◽  
South China ◽  
North China ◽  
Southern Sweden ◽  
Conodont Biostratigraphy ◽  
Middle Ordovician ◽  
The Core ◽  
Core Section ◽  
Argentine Precordillera

AbstractOne of the few and most complete records of the MDICE (Middle Darriwilian Isotope Carbon Excursion) is herein documented from Baltoscandia. Based on a core section penetrating the condensed Lower–Middle Ordovician succession (~46 m) on the island of Öland, southeastern Sweden, we provide an integrated scheme for carbon isotope chemostratigraphy (313 samples) and conodont biostratigraphy (29 samples) for this period. The carbonate succession in the Tingskullen core records 12 conodont zones and 6 subzones, including theOepikodus evae, Trapezognathus diprion, Baltoniodus triangularis, B. navis, B. norrlandicus, Lenodus antivariabilis, L. variabilis, Yangtzeplacognathus crassus, Eoplacognathus pseudoplanus(Microzarkodina hagetianaandMicrozarkodina ozarkodellasubzones),E. suecicus, Pygodus serra(E. foliaceus, E. reclinatus, E. robustusandE. lindstroemisubzones) andPygodus anserinuszones in ascending order. The δ13Ccarbrecord reveals an apparently complete record of the MDICE, including a rising limb, a well-defined peak and a falling limb. The anomaly covers a thickness ofc. 27 m in the core and spans theEoplacognathus pseudoplanus, E. suecicus, Pygodus serraandP. anserinusconodont zones. Combined with the new, detailed conodont biostratigraphy, the MDICE in the Tingskullen core can be used for detailed correlation with successions from Baltica, North America, the Argentine Precordillera, South China and North China.

scholarly journals Conodont biostratigraphy and global correlation of the middle Darriwilian-lower Sandbian (Ordovician) Las Aguaditas Formation, Precordillera of San Juan, Argentina

2016 ◽  
Vol 43 (1) ◽  
pp. 60 ◽  
Author(s):  
Nicolás A. Feltes ◽  
Guillermo L. Albanesi ◽  
Stig M. Bergström
Keyword(s):  
North American ◽  
Recovery Phase ◽  
San Juan ◽  
Conodont Biostratigraphy ◽  
Middle Ordovician ◽  
Study Section ◽  
The North ◽  
Global Correlation ◽  
Low Diversity ◽  
Argentine Precordillera

Middle Darriwilian to lower Sandbian conodonts were recorded from the Las Aguaditas Formation at its type section in the Argentine Precordillera. A total of 9,974 conodont specimens were recovered from 46 carbonate samples, which represent 68 species of 38 genera. A biostratigraphic study verified a middle Darriwilian age for the interval spanning the contact between the San Juan and the Las Aguaditas formations. The following zones are determined in the study section: the Lenodus variabilis Zone, with the Periodon gladysae and Paroistodus horridus subzones following the Precordilleran scheme; the L. variabilis, Yangtzeplacognathus crassus, and the Eoplacognathus pseudoplanus zones with the Microzarkodina hagetiana and M. ozarkodella subzones, and the Pygodus anserinus Zone, according to the Scandinavian scheme; the Periodon macrodentatus Zone, with the Histiodella sinuosa, H. holodentata and H. cf. holodentata subzones, and the P. zgierzensis Zone with the H. kristinae Subzone that correlates the North American scheme. A stratigraphic gap was recognized between the lower and middle members of the Las Aguaditas Formation. It comprises the Eoplacognathus suecicus and Pygodus serra zones, and the lower subzone of the Pygodus anserinus Zone. The variation of conodont diversity through the study section conforms to shallowing and deepening patterns, which accompanies the changes of the provenance lithology. Three conodont assemblages were quantitatively recognized: a) Diverse conodont association, b) Low diversity conodont association and c) Recovery phase association. We propose to use the North American biozonal scheme of conodonts for the Central Precordillera because of the affinity of documented index taxa, which provides a more accurate intercontinental correlation for the global Middle Ordovician Series.

Amsassia (calcareous alga) from the Lower Ordovician (Tremadocian) of western Newfoundland, and the biologic affinity and geologic history of the genus

2021 ◽  
pp. 1-18
Author(s):  
Dong-Jin Lee ◽  
Robert J. Elias ◽  
Brian R. Pratt
Keyword(s):  
South China ◽  
Geologic History ◽  
Shallow Marine ◽  
Middle Ordovician ◽  
Calcareous Alga ◽  
Tarim Block ◽  
Lower Ordovician ◽  
History Of ◽  
Argentine Precordillera ◽  
Extinct Group

Abstract Modular coral-like fossils from Lower Ordovician (Tremadocian) thrombolitic mounds in the St. George Group of western Newfoundland were initially identified as Lichenaria and thought to include the earliest tabulate corals. They are here assigned to Amsassia terranovensis n. sp. and Amsassia? sp. A from the Watts Bight Formation, and A. diversa n. sp. and Amsassia? sp. B from the overlying Boat Harbour Formation. Amsassia terranovensis n. sp. and A. argentina from the Argentine Precordillera are the earliest representatives of the genus. Amsassia is considered to be a calcareous alga, possibly representing an extinct group of green algae. The genus originated and began to disperse in the Tremadocian, during the onset of the Great Ordovician Biodiversification Event, on the southern margin of Laurentia and the Cuyania Terrane. It inhabited small, shallow-marine reefal mounds constructed in association with microbes. The paleogeographic range of Amsassia expanded in the Middle Ordovician (Darriwilian) to include the Sino-Korean Block, as well as Laurentia, and its environmental range expanded to include non-reefal, open- and restricted-marine settings. Amsassia attained its greatest diversity and paleogeographic extent in the Late Ordovician (Sandbian–Katian), during the culmination of the Great Ordovician Biodiversification Event. Its range included the South China Block, Tarim Block, Kazakhstan, and Siberia, as well as the Sino-Korean Block and Laurentia, and its affinity for small microbial mounds continued during that time. In the latest Ordovician (Hirnantian), the diversity of Amsassia was reduced, its distribution was restricted to non-reefal environments in South China, and it finally disappeared during the end-Ordovician mass extinction. UUID: http://zoobank.org/ef0abb69-10a6-46de-8c78-d6ec7de185fe

Early orthoceratoid cephalopods from the Argentine Precordillera (Lower-Middle Ordovician)

2007 ◽  
Vol 81 (6) ◽  
pp. 1266-1283 ◽  
Author(s):  
Björn Kröger ◽  
Matilde S. Beresi ◽  
Ed Landing
Keyword(s):  
New Species ◽  
Southern Hemisphere ◽  
North China ◽  
North China Block ◽  
Middle Ordovician ◽  
Strong Affinity ◽  
Middle Latitudes ◽  
The North ◽  
Lower Ordovician ◽  
Argentine Precordillera

The Early and Middle Ordovician Orthocerida and Lituitida of Precordilleran Argentina are described, and their systematics and paleogeographic significance are revised. These cephalopods show a strong affinity to coeval faunas of North China, suggesting a location of the Precordillera at middle latitudes in the Southern Hemisphere east of the North China block and relatively close to the Gondwanan margin during the early Middle Ordovician. The descriptive terminology of characters of the septal necks, the position and shape of the siphuncule, and the shape of the connecting ring is improved. The distribution of these characters support an emendation of the Baltoceratidae, Sactorthoceratidae, and Proteoceratidae. Braulioceras n. gen. (Sactorthoceratidae) and Palorthoceras n. gen. (Orthoceratidae) are erected. The new species Braulioceras sanjuanense, Eosomichelinoceras baldisii, Gangshanoceras villicumense, and Rhynchorthoceras minor are proposed. Palorthoceras n. gen. from the Lower Ordovician Oepikodus evae Zone represents the earliest known orthocerid.

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