A Survey on the condition of Micro Facies , Sedimentary Environment and the Cretaceous Deposits ( With Particular Reference to Central Iran )
Micro continent of central Iran is a part of middle Iran that is bounded with ophiolithic suture zones in Sistan, Naiin, Baft, Doruneh fault and Kashmar – Sabzevar ophiolites and is classifiable into Lut block, Shotori upland, Tabas subduction, Kalmard upland, Posht Badam block, Biaze Bardsir basin and Yazd block by means of long faults which are dextral strike – slip faults and have westwards inclination. In many regions of Iran, except to Zagros, in approximate boundary of early and late Cretaceous, it is observed evidences of tectonic events which are mainly as land generating and can be compared with worldwide Austrian event, in everywhere in Iran except to rare cases (east of Tehran and Yazd). Upper Cretaceous beds in Iran do not have identical facial characteristics and it seems that in contrast to equal sedimentary condition in early Cretaceous, sedimentary basins in upper Cretaceous have been separated from each other and special condition has been dominated in each basin. As a result of that, lithostratigraphic units except to Zagros and Kopet Dagh have not been named and or have local names in upper Cretaceous of Iran. This article is an overview of the condition of Micro-facies, sedimentary environment and the Cretaceous deposits in central Iran. [Mehran Arian, Hamideh Noroozpour. A Survey on the condition of Micro Facies, Sedimentary Environment and the Cretaceous Deposits (With Particular Reference to Central Iran) ). Journal of American Science 2011;7(6):915924]. (ISSN: 1545-1003). http://www.americanscience.org.
Earth System History
PART I: MATERIALS, PROCESSES, AND PRINCIPLES Earth as a System Rock-Forming Minerals and Rocks The Diversity of Life Environments and Life Sedimentary Environments Correlation and Dating of the Rock Record Evolution and the Fossil Record The Theory of Plate Tectonics Continental Tectonics and Mountain Chains Major Chemical Cycles PART II: THE STORY OF EARTH The Hadean and Archean Eons of Precambrian Time The Proterozoic Eon of Precambrian Time The Early Paleozoic World The Middle Paleozoic World The Late Paleozoic World The Early Mesozoic World The Cretaceous World The Paleogene World The Neogene World The Holocene
Chemosymbiotic bivalves and stable carbon isotopes indicate hydrocarbon seepage at four unusual Cenozoic fossil localities
Four unusual Cenozoic fossil localities are identified here as ancient hydrocarbon seep sites using palaeontological, petrological, and stable carbon isotope data. Late Eocene carbonate-cemented sandstone bodies in the Wagonwheel Mountains in California were previously suspected to represent ancient hydrocarbon seep sites, but the relatively high δ13Ccarbonate values (−12.2 to −5.0‰) suggest oil rather than methane seepage. The Oligocene fauna of the Elmira asphalt mine, Cuba, was previously interpreted as a mix of freshwater and marine taxa, but all species are here identified as belonging to marine groups, including the bivalve families Lucinidae and Vesicomyidae, whose extant members live largely in symbiosis with chemoautotrophic endosymbionts. A carbonate concretion from this site showed δ13Ccarbonate values as low as −32.2‰, which most likely indicates methane seepage. A previously unpublished Oligocene fossil locality in Atlantico, northern Colombia, is dominated by large solemyid, mytilid, lucinid, and vesicomyid bivalves, which most likely lived with chemotrophic endosymbionts. Seepage of biogenic methane without a significant contribution of thermogenic methane is indicated by δ13Ccarbonate values as low as −51.3‰. We confirm that the Pleurophopsis-dominated sites of the Heath Shale and Lomitos Chert in northern Peru are ancient seep sites, although the previous identification of Pleurophopsis peruviana as a vesicomyid is doubtful.