Eastern Alborz

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1 - Biotite mineral chemistry, geothermobarometry and the role of total Al content of biotite in distinguishing of mineralization in the Touyeh- Darvar granitoid, SW of Damghan, Eastern Alborz.
Azin Naderi Habibolah Ghasemi Lamberini Papadopoulou

Touyeh- Darvar granitoid pluton is situated in the south of eastern Alborz zone (45Km SW of Damghan in Semnan province). This pluton has intruded into the late Paleozoic formations (including Barut and Lalun). Based on the field observations and petrographic studies, th More

Touyeh- Darvar granitoid pluton is situated in the south of eastern Alborz zone (45Km SW of Damghan in Semnan province). This pluton has intruded into the late Paleozoic formations (including Barut and Lalun). Based on the field observations and petrographic studies, the pluton is composed of monzonites, quartz monzonite and monzodiorite. In terms of mineralogy, the Touyeh- Darvar granitoid consists of plagioclase, orthoclase, quartz, ± hornblende and ±biotite. Accessory minerals consists of ilmenite, magnetite, zircon, apatite, titanite and pyrite. Sericite, epidote, calcite, and chlorite are considered as secondary phases. The iron-rich biotite is the most significant mafic mineral which are situated in the alkaline and anorogenic biotite fields. The total Al content of biotite in granitic rocks can be a useful indicator for distinguishing between mineralized and non-mineralized granitic rocks. The presence of mineral veins from oxides and hydroxides of iron and manganese, fluorite, barite, lead and zinc in the host rock of this pluton also confirms that the biotite composition is useful for mineralization potential study of this pluton. Applying the thermometry based on the Ti content of biotite and barometery based on total Al content of biotite resulted in calculating temperature ranges of 650–730°C and pressures lower than 1Kb for stopping the exchange and final equilibrium of this mineral in the pluton. Manuscript profile
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2 - Palynostratigraphy and palaeoecology of the Middle Jurassic strata, Tapal, west of Shahrood, eastern Alborz
F. Sajjadi Firoozeh Hashemi Yazdi Hossain Hashemi
20.1001.1.17357128.1402.17.65.6.8

Palynological data are used for palynostratigraphy and reconstruction of some environmental parameters of the Middle Jurassic (Bajocian - Callovian) deposits at the Tapal stratigraphic section, west of Shahrood, eastern Alborz. The studied strata (Dalichai Formation) co More

Palynological data are used for palynostratigraphy and reconstruction of some environmental parameters of the Middle Jurassic (Bajocian - Callovian) deposits at the Tapal stratigraphic section, west of Shahrood, eastern Alborz. The studied strata (Dalichai Formation) contain diverse, relatively well-preserved palynofloras, including miospores (spores and pollens), dinoflagellates cysts, fungal spores, foraminiferal test linings, acritarchs and Tasmanites. The palynofloras include 22 species of spores (belonging to 18 genera), 15 species of pollen (attributed to 9 genera) and 28 species of dinoflagellate cysts (assigned to 15 genera). Based on the stratigraphic distribution of miospores, the Klukisporites variegatus-Araucariacites australis-Cerebropollenites macroverrucosus Assemblage Zone is recognized in the sequence examined, Presence of some index dinoflagellate species led to the identification of three successive biozones including, in an ascending order, Cribroperidinium crispum Total Range Zone (late Bajocian), Dichadogonyaulax sellwoodii Interval Zone (Bathonian – early Callovian) and Ctenidodinum continuum Interval Biozone (early - middle Callovian). To reconstruct some parameters of the sedimentary environments of the studied strata, evidences such as frequency and diversity of spores attributable to ferns, relative abundance of drier/wetter and warmer/cooler elements in different plant communities, ratio of palynological elements and palynofacies, presence of index shallow water dinoflagellate cysts for instance Dichadogonyaulax sellwoodii, Ctenidodinium spp., Valensiella ovulum, Pareodinia spp., Nannoceratopsis gracilis, abundance of proximate dinocysts forms, presence of fungal spores and warm - temperate water dinoflagellate (Gonyaulacysta centriconnata, Nannoceratopsis pellucida, Gonyaulacysta jurassica, Pareodinia ceratophora) are utilized. Based on the above criteria, the material examined seems to have been deposited in a marine margin, low oxygen environment, with low rate sedimentation, under hot and humid climate conditions, where the surrounding terrestrial vegetation was dominated by ferns. Manuscript profile

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List of Articles Eastern Alborz