Document Type : Original Research Paper
Authors
1 Ph.D. Student, Faculty of Science, Department of Geology, Ferdowsi University of Mashhad, Mashhad, Iran
2 2 Assistant Professor, Faculty of Science, Department of Geology, Ferdowsi University of Mashhad, Mashhad, Iran
3 3 Assistant Professor, Department of Geosciences, University of Texas, Dallas, USA
4 M.Sc., Geological Survey of Iran, Tehran, Iran
5 Associate Professor, Faculty of Basic Sciences, Tarbiat Modares University, Tehran, Iran
Abstract
In Kermanshah Radiolarites, Jurassic to late Cretaceous in age, three sedimentary facies including tempestite, pelagic mudstone, and radiolarian wackestone-packstone were identified. Each of these sedimentary facies accompanies by ichnofacies, which reveal the depth and energy of the environment. In the tempestites (including calclithite bed, flat pebble conglomerate and hummocky cross stratification) the trace fossils with Domichnia such as Thalassinoides can be observed, which indicate the energetic conditions at the time of sedimentation. Trace fossils found in pelagic limestone units have Pascichnia and Fodinichnia. These Trace fossils include Planolites, Chondrites and Helminthopsis, which indicate distal Cruziana ichnofacies and show low energy condition. As a result of increasing of depth in siliceous deposits, the trace fossils with Pascichnia and Chemichnia including Scolicia, Helminthopsis, Gyrochorte and Chondrites, and Thalassinoides become dominant, which are indicative of the transitional zone between the distal Cruziana ichnofacies and the Zoophycos ichnofacies. The sedimentary facies and the present ichnofacies are indicative of the sedimentation of these deposits in the transitional zone between the middle and the outer ramp.
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