Albin volcanism in Marivan region: Indication of extension in the Sanandaj-Sirjan continental arc

The Marivan region located in the west of Kurdistan province, northwest of Iran and in the structural geological divisions of Iran (Stöcklin and Nabavi, 1973). The Mesozoic volcanic rocks are widespread in the Northern Sanandaj- Sirjan zone in comparison to the central and southern parts of this zone. The basic term of this volcanic belt with a calc-alkaline tendency is dominant where was formed in association with the Sanandaj-Sirjan arc magmatism in the Mesozoic which generated as a result of the subduction of the Neotethys oceanic crust under the active continental margin of Central Iran (Omrani et al., 2008; Azizi and Jahangiri, 2008; Moinevaziri et al., 2015).The studied area located in the Sanandaj Cretaceous volcanic belt (SVB) (Azizi and Moinevaziri, 2009), is characterized by the presence of basalts and andesite-basalts, often intruded shales, sandstones, and Cretaceous limestones. Rahimzadeh et al. (2021) investigated the North of Sanandaj-Sirjan magmatism in two basic and acidic phases and attributed their formation to a continental arc tectonic environment with extension. Also, the general age of the North Sanandaj-Sirjan zone magmatism varies from 110 to 130 million years (Barmian-Aptian). Ali et al. (2016) determined a bimodal model for the volcanic rocks of the Kata-rash region in Iraq Kurdistan (north of the study area), which originated 108 Ma (Albian) in an oceanic arc tectonic environment. The main purpose of the present paper is to study the petrology and geochemistry of the volcanic rocks of the area, in order to determine their tectonic setting.Regional GeologyThe The studied area is located in the north and east of Marivan city and is a part of the 1:100,000 geological map of Marivan (Sabzehi et al., 2009). Structurally, it is located in the northwestern part of Sanandaj-Sirjan zone. The rock units with Albian age, are a sequence of low metamorphosed volcanic-sedimentary rocks and consist of basaltic lavas, andesite-basalt, rhyodacite, pyroclastic, shale, calcareous shale, metamorphosed limestone, sandstone and minor amounts of conglomerate. A great volume of basic rocks is found in the north of Marivan while the acidic domes are seen in the east of the Marivan. The field relationships of volcano-sedimentary sequence indicates that the volcanic rocks erupted from deep to shallow marine environment (Rahimzadeh et al., 2021).Research methodEleven samples selected from the Marivan volcanic rocks for chemical analyses. The major elements