scholarly journals The Early Ordovician trilobite distribution and zonation of the East Baltic

2006 ◽  
Vol 55 (2) ◽  
pp. 109
Author(s):  
H Pärnaste
Keyword(s):  
Early Ordovician

Early Ordovician alkali-ultramafic Zhilandy complex (Central Kazakhstan): structure and age of formation

2019 ◽  
Vol 484 (1) ◽  
pp. 61-65
Author(s):  
R. M. Antonuk ◽  
A. A. Tretyakov ◽  
K. E. Degtyarev ◽  
A. B. Kotov
Keyword(s):  
Complex Formation ◽  
Central Asian Orogenic Belt ◽  
Early Cambrian ◽  
Early Ordovician ◽  
Late Cambrian ◽  
Central Asian ◽  
Geochronological Study ◽  
Three Stages ◽  
Late Neoproterozoic ◽  
Quartz Monzodiorites

U–Pb geochronological study of amphibole-bearing quartz monzodiorites of the alkali-ultramafic Zhilandy complex in Central Kazakhstan, whose formation is deduced at the Early Ordovician era (479 ± 3 Ma). The obtained data indicate three stages of intra-plate magmatism in the western part of the Central Asian Orogenic Belt: Late Neoproterozoic stage of alkali syenites of the Karsakpay complex intrusion, Early Cambrian stage of ultramafic-gabbroid plutons of the Ulutau complex formation, and Late Cambrian–Early Ordovician stage of formation of the Zhilandy complex and Krasnomay complex intrusions.

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.

scholarly journals The genesis of I- and S-type granitoid rocks of the Early Ordovician Oledo pluton, Central Iberian Zone (central Portugal)

Lithos ◽  
2009 ◽  
Vol 111 (3-4) ◽  
pp. 168-185 ◽  
Author(s):  
I.M.H.R. Antunes ◽  
A.M.R. Neiva ◽  
M.M.V.G. Silva ◽  
F. Corfu
Keyword(s):  
Central Iberian Zone ◽  
Early Ordovician ◽  
Central Portugal ◽  
Granitoid Rocks

Tubular phosphatic microproblematica from the Early Ordovician of China

Lethaia ◽  
1989 ◽  
Vol 22 (4) ◽  
pp. 439-446 ◽  
Author(s):  
JOHN A. LONG ◽  
CLIVE F. BURRETT
Keyword(s):  
Early Ordovician

Neoproterozoic to Early Ordovician Evolution of the Paleo-Asian Ocean: Implications to the Break-up of Rodinia

2003 ◽  
Vol 6 (2) ◽  
pp. 143-159 ◽  
Author(s):  
Nikolay L. Dobretsov ◽  
Mikhail M. Buslov ◽  
Valery A. Vernikovsky
Keyword(s):  
Early Ordovician ◽  
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