Early Paleozoic tectonic reconstruction of Iran: Tales from detrital zircon geochronology

Abstract

In this study we use detrital zircons to probe the Early Paleozoic history of NE Iran and evaluate the link between sediment sources and Gondwanan pre-Cadomian, Cadomian and younger events. U-Pb zircon ages and Hf isotopic compositions are reported for detrital zircons from Ordovician and Early Devonian sedimentary rocks from NE Iran.These clastic rocks are dominated by zircons with major age populations at ~2.5 Ga, ~0.8-0.6 Ga, 0.5 Ga and ~0.5-0.4 Ga as well as a minor broad peak at ~1.0 Ga. The source of 2.5 Ga detrital zircons is enigmatic; they may have been supplied from the Saharan Metacraton (or West African Craton) to the southwest or Afghanistan-Tarim to the east. The detrital zircons with age populations at 0.8-0.6 Ga probably originated from Cryogenian-Ediacaran juvenile igneous rocks of the Arabian-Nubian Shield; this inference is supported by their juvenile Hf isotopes, although some negative εHf (t) values suggest that other sources (such as the West African Craton) were also involved.The age peak at ca 0.

The pre-orogenic detrital zircon record of the Peri-Gondwanan crust

“…Recognizing the vast spatial distribution of this type of Peri-Gondwanan crust, Dörr et al (2015) combined different domains, including North Iberia, Sardinia, Apulia, the Hellenides and Pontides and referred to them as the ‘Minoan Terrane Assemblage’. As visualized in Figure 6, the spatial distribution of the East African–Arabian provenance actually is even larger and reaches at least as far to the east as Iran (Moghadam et al 2017), possibly as far as Tarim and South China. Our data analysis (Fig.…”

Provenance and geochemical variations across the Ediacaran–Cambrian transition in the Soltanieh Formation, Alborz Mountains, Iran

“…This interpretation is in agreement with that of the underlying Kahar Formation (Etemad-Saeed et al 2015), which contains immature arc-derived greywackes and mudrocks. This is also supported by the presence of Cadomian felsic rocks in Iran during this time interval as main parent rocks for the Kahar and Soltanieh sediments (Moghadam et al 2015(Moghadam et al , 2016(Moghadam et al , 2017Malek-Mahmoudi et al 2017). However, it should be noted that the zircon age populations of the Kahar Formation indicate a distal-minor parent rock for the Kahar sediments within the Arabian-Nubian Shield (East African Orogen; Horton et al 2008;Etemad-Saeed et al 2015), which can also act as a secondary source for the Soltanieh sediments.…”

“…Although some authors have proposed a passive marginal setting for Iran as part of the Afro-Arabian platform (Stocklin, 1968b;Husseini, 1989;Berberian & King, 1981;Talbot & Alavi, 1996), there are other publications showing evidence of an active margin setting for Iran as a part of peri-Gondwanan terranes (Malek-Mahmoudi et al 2017;Ramezani & Tucker, 2003;Hassanzadeh et al 2008;Horton et al 2008). New geochemical and geochronological constraints on the crystalline granitic and orthogneissic basement rocks of Iran (c. 650-500 Ma) support the second scenario, indicating Cadomian arc plutonism and volcanism in Iran during southwards subduction of the Proto-Tethys ocean along the northern margin of Gondwana (Moghadam et al 2015(Moghadam et al , 2016(Moghadam et al , 2017Malek-Mahmoudi et al 2017).…”

U–Pb ages and Hf isotopes of detrital zircons from pre-Devonian sequences along the southeast Yangtze: a link to the final assembly of East Gondwana

“…The εHf(t) values of 650-560 Ma in the Ediacaran strata in the northern and western margins of the Yangtze show positive values (+8 to +1); however, the contemporaneous detritus in the contemporary Cathaysia strata have a wider range of εHf(t) (+2 to −17) values. The εHf(t) values of the 650-560 Ma zircons in the rocks of northern and western Yangtze are comparable to those in the Late Neoproterozoic juvenile arc magmatic rocks in the Arabian-Nubian Shield as the northern extension of the East African Orogen (Robinson et al 2014;Moghadam et al 2017) and the Paterson Orogen in NW Australia (Martin, Collins & Kirkland, 2017). Considering that Australia was separated from the composite India-SCC in Ediacaran times (Xu et al 2014b;Cawood et al 2017), and the εHf(t) values of 650-560 Ma zircons in the Cathaysia section of the SCC are similar to those in the Upper Neoprotero-zoic magmatic rocks in South India, including Madurai (Santosh et al 2017) and Sri Lanka Santosh et al (2014b), we propose that the Late Ediacaran detritus in the SCC was mainly derived from the Arabia-India terrain rather than the India-Australia terrain.…”