Stratigraphy and Palaeontology
Nasrollah Abbassi; Safoora Shakeri; Javad Rabbani
Abstract
Numerous Proboscidean footprints have been discovered in the outcrop (135 m) of lower rock unit of the Upper Red Formation (Middle-Late Miocene) in the north Avaj (Qazvin province), central Iran. These footprints are preserved as circular concave epi-relief in the upper bedding planes with smooth or ...
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Numerous Proboscidean footprints have been discovered in the outcrop (135 m) of lower rock unit of the Upper Red Formation (Middle-Late Miocene) in the north Avaj (Qazvin province), central Iran. These footprints are preserved as circular concave epi-relief in the upper bedding planes with smooth or levee rims or with sediment accumulation in the front of the footprints. Five digit imprints present in some of the footprints. The frequency of footprints is considerable the most of the upper surface of layers which was resulted by movement of proboscis herds. Ichnotaxonomically these footprints identified as Proboscipedaen igmatica. The footprints are classified as two sizes as small (15 cm) and large (25 cm) categories, and based on the geometric relationships, the height of shoulder was estimated as 140-170 cm for adult and 76-106 cm immature individuals. According to reports of Miocene Proboscidean body fossils from Iran, and based on the distributions of the Proboscidean in this time, it seems that the Choerolophodon (Gomphotheriidae) is candidate as track-maker of the Avaj footprints. Among the Proboscidean footprints, there are crocodile and fish swimming imprints which were left in the shallow pools.
R. Mohamadi; M.H., Emami; M. Vosoghiabedi
Abstract
The area is located about 230 km of southwest of Tehran. Based of geological observations, the plutonic rocks in the area consist of Neogene (Miocene) alkaline gabbro , gabbrodiorite, locogabbro and diabase . The Oligo - Miocene calc-alkaline extrusive rocks are dacite - ryodacite , andesite trachyandesite ...
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The area is located about 230 km of southwest of Tehran. Based of geological observations, the plutonic rocks in the area consist of Neogene (Miocene) alkaline gabbro , gabbrodiorite, locogabbro and diabase . The Oligo - Miocene calc-alkaline extrusive rocks are dacite - ryodacite , andesite trachyandesite , hornblendandesite , basaltic andesite and trachybasalt .Studing on isotopic analyses of Nd and Sr indicate that surveyed area were contaminated with crustal rocks of Sialic composition . In isotopy geochemical studies, The Andesite samples are plotted in the limit of BSE; however, it seems that mantling rocks besides being settled in crust (esp. the upper continental crust) have been contaminated with in. The combination of BSE towards enrichment, from the proportion of 87Sr/86Sr has shifted; a sample of rocks shows this position. Spider diagrams related to trace elements of plutonic samples which are used for identifying the tectonic setting show intrusives are in the extensive regime; while the lavas don’t have a steady trend and are similar to subduction zones. This shows that the intrusives of the the investigated area are different genesis from the southern volcanic rocks.
