Lower Ordovician sponge bioherms in the Makkol Formation, Taebaeksan Basin, mideast Korea

Facies ◽  
2003 ◽  
Vol 48 (1) ◽  
pp. 79-90 ◽  
Author(s):  
Yi Kyun Kwon ◽  
Dong Jin Lee ◽  
Duck K. Choi ◽  
Sung Kwun Chough
Keyword(s):  
Taebaeksan Basin ◽  
Lower Ordovician ◽  
Sponge Bioherms

The Ibexian Series (Lower Ordovician), a replacement for "Canadian Series" in North American chronostratigraphy

1993 ◽  
Author(s):  
R.J. Ross ◽  
L.F. Hintze ◽  
Raymond L. Ethington ◽  
J.F. Miller ◽  
M.E. Taylor ◽  
...  
Keyword(s):  
North American ◽  
Lower Ordovician

The first Early Ordovician graptolites and marine incursions in eastern Alborz, Iran

2021 ◽  
pp. 1-14
Author(s):  
Adrian W. A. Rushton ◽  
Mansoureh Ghobadi Pour ◽  
Leonid E. Popov ◽  
Hadi Jahangir ◽  
Arash Amini
Keyword(s):  
Northern Iran ◽  
Early Ordovician ◽  
Lower Ordovician ◽  
Shale Formation ◽  
Kopet Dagh ◽  
Semnan Province

Abstract Graptolites have been collected from sections through Lower Ordovician strata in northern Iran. At the Saluk Mountains, in the Kopet–Dagh region, mudrocks yielded fragmentary tubaria of Rhabdinopora sp. cf. R. flabelliformis, indicating the presence of lower Tremadocian strata there; stratigraphically, they lie between two limestone beds with the euconodont Cordylodus lindstromi. At Simeh–Kuh in the eastern Alborz Mountains (Semnan Province), upper Tremadocian – lower Floian strata include laminated dark mudstones that contain restricted graptolite faunas, mainly of small declined didymograptids; these are thought to represent incursions of plankton during periods of marine highstands. The lower major flooding surface in Simeh–Kuh coincides with an invasion of the graptolite biofacies and an incursion of Hunnegraptus? sp.; the second major flooding surface is associated with an incursion of Baltograptus geometricus. They were most probably synchronous with those in the lower part of the Hunnegraptus copiosus Biozone and at the base of the Cymatograptus protobalticus Biozone in the of the Tøyen Shale Formation succession of Västergötland, Scandinavia, suggesting that observed characters of sedimentation were eustatically controlled.

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