Conodonts from the Niur Formation (Silurian) of the Derenjal Mountains, Central Iran

2013 ◽  
Vol 150 (4) ◽  
pp. 639-650 ◽  
Author(s):  
P. MÄNNIK ◽  
C. G. MILLER ◽  
V. HAIRAPETIAN

AbstractA Llandovery to Ludlow age for the Niur Formation in the Derenjal Mountains (east-central Iran) is proposed based on new conodont data and previous work on other fossils. The uppermost part of the studied section yielded no diagnostic conodonts but may be Pridoli in age. Some intervals can be dated more precisely: Unit 11 (at least its upper part) is middle Telychian in age and corresponds to thePterospathodus amorphognathoides lennartiZone; the lowermost part of Unit 16 is earliest Ludlow in age and corresponds to theKockelella crassaZone; the uppermost Unit 16 is late Ludlow (Ludfordian) in age and corresponds to theOzarkodina snajdriInterval Zone. The Llandovery–Wenlock boundary lies between units 12 and 13 based on sedimentological evidence. The precise location of the Wenlock–Ludlow boundary in the section is not clear but lies below Unit 16. Present-day Iran was located far away from Baltica and Laurentia, on the other side of the Rheic Ocean. This ocean does not seem to have been a major migration barrier for most organisms including the conodonts.

Facies ◽  
2009 ◽  
Vol 56 (1) ◽  
pp. 59-87 ◽  
Author(s):  
Markus Wilmsen ◽  
Franz T. Fürsich ◽  
Kazem Seyed-Emami ◽  
Mahmoud R. Majidifard ◽  
Massoud Zamani-Pedram

2005 ◽  
Vol 176 (3) ◽  
pp. 231-242 ◽  
Author(s):  
Bertrand Lefebvre ◽  
Mansooreh Ghobadipour ◽  
Elise Nardin

Abstract Two echinoderm assemblages are described in the Middle Ordovician of Iran (Darriwilian). The Simeh Kuh section (Damghan area, eastern Alborz range) has yielded a rich and diverse blastozoan fauna consisting of fistuliporite (Echinosphaerites, Heliocrinites) and dichoporite rhombiferans (cheirocrinids indet., hemicosmitids indet.), as well as aristocystitid (Sinocystis) and sphaeronitid diploporites (Glyptosphaerites, Tholocystis). Heliocrinites, cheirocrinids, hemicosmitids, Glyptosphaerites, and Tholocystis are reported for the first time in the Ordovician of Iran. A less diverse assemblage was collected in the Shirgesht section (Tabas area, Derenjal Mountains), and represents the first report of Ordovician echinoderms in east-central Iran. The Shirgesht fauna includes fistuliporite rhombiferans (Heliocrinites), aristocystitid and sphaeronitid diploporites. The new Iranian material documents some of the earliest known assemblages of diploporites and rhombiferans, and thus, brings important information on the radiation of these two major blastozoan classes. The two Iranian echinoderm faunas show relatively strong affinities with contemporary faunas from Baltica, the northern Gondwanan margin (e.g. Bohemia, Morocco), Sibumasu, and South China terranes. Aristocystitids suggest stronger links between Iran, and regions from the “Province à Amphorides” (northern Gondwanan margin, Sibumasu, South China). These observations support a palaeogeographical position of Iran at intermediate palaeolatitudes during the early Middle Ordovician, in the periphery of the northeastern Gondwanan margin.


2010 ◽  
Vol 46 (1) ◽  
pp. 9-21 ◽  
Author(s):  
Heinz-Günter Stosch ◽  
Rolf L. Romer ◽  
Farahnaz Daliran ◽  
Dieter Rhede
Keyword(s):  

1995 ◽  
Vol 69 (5) ◽  
pp. 805-812 ◽  
Author(s):  
Calvin H. Stevens

The discovery of a new locality yielding giant Guadalupian (Lower Permian) fusulinids in east-central Alaska extends the range of these forms much farther north than previously known, and into a tectonostratigraphic terrane from which they previously had not been reported. The number of areas from which giant parafusulinids are known in North America is thus raised to eight. Three of these localities are in rocks that previously had been referred to the allochthonous McCloud belt arc, and one, West Texas, is known to have been part of Paleozoic North America. Comparison of species from all areas suggests that there are two closely related species groups: one represented in Texas and Coahuila, and the other represented in Sonora, northern California, northeastern Washington, southern and northern British Columbia, Alaska, and apparently in Texas. These groups may differ because they are of slightly different ages or because interchange between the faunas of Texas–Coahuila area and the other regions was somewhat inhibited during the Early Permian.


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