Ichno-biodivesity of Mila Formation in Cambrian-Ordovician interval north Shahmirzad section, Central Alborz
Document Type : Original Article
Authors
1
University of Zanjan
2
University of Mashhad
Abstract
Biodiversity includes all diversities of biologic forms and its related, and are discussed about genetic, species and ecologic diversities. Recent biodiversity is resulted from interaction of internal and external forces of the ecologic niches through geologic time. Biodiversity trough Cambrian-Ordovician interval however is important and was discuses by many of researcher. Because of Grate Ordovician Biodiversity Event (GOBE), is greatest biodiversity in the phanerozoic and were attended by them. Mila Formation (Middle Cambrian-Early Ordovician) in the north Shahmirzad, eastern Alborz Mountains comprises dolomite, marl, crystalline limestone, bioclastic limestone, shale, sandstone and siltstone (450 m). These sediments have been divided into five members. Biodiversity studies on trace fossils created by some researchers. Trace fossils differ from body fossils in the creation and fossilization. Therefore, it may differ in biodiversity discussion trace fossils from body fossils. Environmental and ethological factors are affected on the trace fossils. Trace fossils radiations of Mila formation are main subject of this paper. Diverse trace fossils have been found in this formation that include 21 ichnogenera with 41 ichnospecies. Trace fossils show different behaviors such as grazing, dwelling, resting and feeding. The ichnodiversity of trace fossils increase to upper members of formation and show diverse behaviors. It seems that this biodiversity increase resulted from the creation of new settlements during the Cambrian to Ordovician passing.
Keywords
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