Acta Geologica Sinica, ( ISI ), Volume (90), No (5), Year (2016-10) , Pages (1572-1597)

Title : ( Depositional Controls on the Ichnology of Ordovician Wave‐dominated Marine Facies: New Evidence from the Shirgesht Formation, Central Iran )

Authors: Aram BAYET-GOLL , Paul M. MYROW , F. ACEÑOLAZA , Sayyed Reza Moussavi Harami , Asadollah Mahboubi ,

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Abstract

The Lower Ordovician Shirgesht Formation in central Iran is composed of siliciclastic and carbonate rocks deposited in diverse coastal and marine shelfal environments (tidal flat, lagoon, shoreface, offshore-shelf and carbonate ramp). Five facies associations contain diverse ichnofossil assemblages that show distinct proximal to distal trends formed in a wide range of physical-chemical conditions. The ethological groups of trace fossils in the Shirgesht Formation reflect a gradient of depositional stress conditions across a wave-influenced shoreline and shelf. Deposits of waveinfluenced environments make up a significant component of the geological record of shallow marine settings, and the ability to determine paleoenvironments in detail in such successions is critical for reconstruction of depositional histories and sequence-stratigraphic interpretation. The Cruziana ichnofacies of the study shows highly diverse suites that record the establishment of a benthic community under stable conditions and a long-term colonization window. The Skolithos ichnofacies recognized is a low diversity opportunistic ichnocommunity suite that resulted from colonization after tempestite deposition in a stressed environment. The strata record an onshore to offshore replacement of the Cruziana ichnofacies (with abundant feeding traces of deposit-feeders) by the Skolithos ichnofacies (dominated by suspension-feeders and predators). A transitional zone between the two ichnofacies coincides with the offshore-transition/distal lower-surface deposits. The distribution of ichnofacies, the diversity and range of ethological characteristics reflected by the ichnogenera, and the wide range of wave-dominated coastal facies demonstrate the potential to use individual trace fossils and ichnofacies for significantly refined palaeoenvironmental analysis of wavedominated coastal settings, particularly in Ordovician successions.

Keywords

, Shirgesht Formation, Ordovician, facies associations, sedimentology, iconology, ichnofacies
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@article{paperid:1059588,
author = {Aram BAYET-GOLL and Paul M. MYROW and F. ACEÑOLAZA and Moussavi Harami, Sayyed Reza and Mahboubi, Asadollah},
title = {Depositional Controls on the Ichnology of Ordovician Wave‐dominated Marine Facies: New Evidence from the Shirgesht Formation, Central Iran},
journal = {Acta Geologica Sinica},
year = {2016},
volume = {90},
number = {5},
month = {October},
issn = {1000-9515},
pages = {1572--1597},
numpages = {25},
keywords = {Shirgesht Formation; Ordovician; facies associations; sedimentology; iconology; ichnofacies},
}

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%0 Journal Article
%T Depositional Controls on the Ichnology of Ordovician Wave‐dominated Marine Facies: New Evidence from the Shirgesht Formation, Central Iran
%A Aram BAYET-GOLL
%A Paul M. MYROW
%A F. ACEÑOLAZA
%A Moussavi Harami, Sayyed Reza
%A Mahboubi, Asadollah
%J Acta Geologica Sinica
%@ 1000-9515
%D 2016

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