Seyed Hamid Vaziri; Mahmoud Reza Majidifard; Marc Laflamme
Abstract
The Precambrian Kushk Series in the Bafq and Behabad regions of Central Iran contains a diverse assemblage of latest Ediacaran fossils that showcase a fossil assemblage much more diverse than typically known from the latest Ediacaran systems worldwide. The Kushk Series reaches a thickness of >500 ...
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The Precambrian Kushk Series in the Bafq and Behabad regions of Central Iran contains a diverse assemblage of latest Ediacaran fossils that showcase a fossil assemblage much more diverse than typically known from the latest Ediacaran systems worldwide. The Kushk Series reaches a thickness of >500 m and consists of carbonate (sandy dolomitic limestone and dolomite) and siliciclastic (shale, sandstone, and siltstone) facies with extensive accumulations of volcanic rhyolite, microdiorite, and tuff, which its argillaceous shales contain an assemblage of abundant Ediacaran fossils including Kuckaraukia multituberculata,Persimedusites chahgazensis, Corumbella werneri, Cloudinasp., Chuaria sp., Kimberella persii, Gibbavasis kushkii, Erniettomorpha, Rangeomorpha and numerous tubular organisms. The discovery of classic terminal-Ediacaran index fossils Cloudina and Corumbella in this assemblage confirms a latest Ediacaran age (Nama-Assemblage ~545-539 Ma) for these deposits. These taxa help expand our understanding of the latest Ediacaran prior to the Ediacaran extinction and the Cambrian explosion of complex animals.
R. Jamali Ashtiani; J. Hassanzadeh; M. Rahgoshay
Abstract
Two different ages of Precambrian and Jurassic are considered for the Zayanderud metamorphic complex in the Najafabad and Chadegan geology maps, respectively. This disagreement has made these two maps to be the most incompatible adjacent maps. The metamorphic complex is nonconformably covered by fossiliferous ...
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Two different ages of Precambrian and Jurassic are considered for the Zayanderud metamorphic complex in the Najafabad and Chadegan geology maps, respectively. This disagreement has made these two maps to be the most incompatible adjacent maps. The metamorphic complex is nonconformably covered by fossiliferous Permian limestones suggesting a Pre-Permian age. This relative age is supported by 206Pb/238U zircon ages of Neoproterozoic for the cross-cutting mylonitic orthogneisses. In this paper we discuss the Jurassic age considered for protolith of the metamorphic and granitoid rocks in the Chadegan map as an misunderstanding in field observations. Also we argue that Ar/Ar Jurassic ages represent the time of metamorphism and do not reflect the protolith age.
R. Hajialioghli; M. Moazzen
Abstract
The Prototethys ocean is formed between tow giant continents of Gondwana in the north and Eurasia in the south. Iranian terrain as neigburhood countries in the Oman, Pakestan, SE Turkey has been belonged to the giant Gondwana during Precambrian and Paleozoic. Precambrian terrains in Iran show limited ...
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The Prototethys ocean is formed between tow giant continents of Gondwana in the north and Eurasia in the south. Iranian terrain as neigburhood countries in the Oman, Pakestan, SE Turkey has been belonged to the giant Gondwana during Precambrian and Paleozoic. Precambrian terrains in Iran show limited out crops including of middle part of the Central Iran in Saghand and Poshtbadam regions, Uromiyeh, Zanjan, Golpayegan, Anabolaghi (in Miyaneh) and Takab. The Takht-e-Soleyman metamorphic complex is located in the north eastern Takab. It is composed of variety of metamorphic rocks including metapelites, metabasites, calc-silicates and meta-ultramafic rocks. On the basis of fieldgeology, petrology and zircon U/Pb isotopic data, the Takht-e-Soleyman complex is comparable with the Central Iranian micro-continent. On the basis of 207Pb/206Pb isotopic data, age of the oldest hetrogen fragments rocks in the Takht-e-Soleyman continental crust gives ca. 2800 Ma, which is comparable with the ages from the Central Iran Micro-continent (ca. 2400 Ma). The regional metamorphism of the basement rocks in the Takht-e-Soleyman complex occurred during compressional regimes related to the Katangan Orogeny corresponding to the Precambrian. Partial melting of the metamorphic rocks has been occurred during Oligocene to Miocene corresponding to the final continental collision of the Neotethys ocean. Migmatites of the Takht-e-Soleyman complex are formed in this regard.
