Plant macrofossiles of Kalariz Formation (Rhaetian) from Kenar-Rud coal mines (SW Chaboksar), Dating and Correlation with the other regions in West of Alborz Range

Structural- facies region is divided into three subareas or structural zones of north Alborz, central Alborz, and south Alborz. Coaly sediments of Alborz according to structural specification, coal mining, and geographical divisions have been divided into three areas west Alborz, central Alborz, and east Alborz (Moin-o Sadat & Zade-Kabir, 1991). Range of study related to north Alborz subarea and from the viewpoint of coal mines classification is related west Alborz area. Between three formations of Ekrassar, Laleband and Kalariz with the age of Late Triassic (Late Carnian- Rhaetian) that before had depended on three members of Tazare formation, except Ekrassar formation, two formations of Laleband and Kalariz have coal veins that coal veins in Kalariz formation are very more and workable and economic so that in north Alborz, Kalariz formation is main beds of Shemshak Group coal mines. There are little exposures over in the area of north Alborz and SW Chaboksar (the eastern edge of Gilan province) coal local mines as more or less scattered related to sedimentary beds of Kalariz formation in near Kenar-Rud village as a small audit that not so long ago, people of the region used from these mines aim of limited extraction of coal. According to collapsing audits of the mines, a few plant remains have been found as loos specimens.

The localities studied are located in near of Kenar-Rud village in SW of Chaboksar, between 50° 29' and 50° 30' E and 36° 51' and 36° 53' N. Access path is Chalus, Ramsar, Javaher-Deh and Kenar-Rud road. Studied locality according to because of the Javaher-Deh formation located in north Alborz subarea. According to the last of divided of Shemshak group (Fürsich et al., 2009) in north Alborz subarea consists of four formations as Ekrasar formation (Late Carnian- Norian), Lale-band formation (Late Norian-Rhaetian), Kalariz formation (Rhaetian) and Javaher-Deh (Hettangian- Early Bajocian). Eastern bound of west Alborz is Chalus River. West Alborz is divided into five coaly regions of Sangrud, Aghusbon, Ramsar, Ghazwin, and Azarbayjan coal area, and the Ramsar coal region is divided into two sub-regions of Neydasht and Ekrassar, so that studied mines in this study located coal region of Ramsar and sub-region of Neydasht. The coal region of Ramsar is located in the northeast of the coal basin west Alborz in between Chaboksar to Tonekabon and Neydasht subarea is located in the northwest end of the coaly region of Ramsar. Studied beds related to the upper part of Kalariz formation near of Javaher-Deh formation beds.

In total, eight species are found from Kenar-Rud coal mines that include:Dictyophyllum nathorstii Zeiller 1903 (Age: Late Norian- Late Rhaetian), Nilssonia pseudobrevis (Barnard 1967b) Corsin & Stampfli 1977 (Age: Norian-Rhaetian), Pterophyllum aequale (Brongniart 1824) Nathorst 1878 (Age: Late Rhaetian), Pterophyllum sp., Dictyozamites asseretoi Barnard 1965 (Age: Rhaetian), Dictyozamites sp., cf. Nilssoniopteris musafolia Barnard 1965 (Age: Rhaetian), Anthrophyopsis crassinervis Nathorst 1878 (Age: Late Rhaetian).
Kalariz formation in north Alborz structural- facies zone; Kalariz and Alasht formations in central Alborz structural- facies zone and Kalariz, Alasht & Dansirit formations in south Alborz structural- facies zone consist of economic coal. Alasht formation in central Alborz structural- facies zone and Kalariz formation in the north and south Alborz has maximum coal in a total of west Alborz. Kanar-Rud coal mines in SW of Chaboksar located in the west Alborz coal area, Ramsar coal region, and Neydasht coal sub-region.

Coal mines around of Kenar-Rud village in SW of Chaboksar (East of Gilan province) consist of Rhaetian plant macrofossils from Kalariz formation that according to species of Dictyophyllum nathorstii, Anthrophyopsis crassinervis, Nilssonia pseudobrevis, Pterophyllum aequale & Dictyozamites asseretoi age of studied beds are Rhaetian and particularly two species of Anthrophyopsis crassinervis and Pterophyllum aequale the age of beds are Late Rhaetian (upper Kalariz). Dictyozamites and two species of Nilssonia pseudobrevis and Dictyozamites assretoi from western Alborz basin, Pterophyllum aequale from Ramsar region and Anthrophyopsis crassinervis Neydasht sub-region have been reported for the first time. Three divisions of Cycadophyta (especially order of Bennettitales), Filicophyta (true ferns) and Pteridospermophyta (seed ferns) in a total of genus trance is 78% and in species, trance is 81% from the total of plant macrofossils collection of western Alborz basin and remains of genus and species related to three divisions of Coniferophyta, Sphenophyta, and Ginkgophyta. The vegetation of Rhaetian time in two regions of Ghazwin and Sangrud-Aghuzbon is somewhat similar of each other (with Sorensenʼs similarity index 47%) and on the other hand vegetation of Ramsar region has different with two regions of Ghazwin (with Sorensenʼs similarity index 17%) and Sangrud- Aghuzbon (with Sorensenʼs similarity index 23%). Plant macrofossils collection in the western Alborz coal basin confirms the subtropical wet weather up to the tropical weather for the Rhaetian time (Kalariz formation).