Jurassic Corals from the Shemshak Formation of the Alborz Mountains, Iran 41
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he A 46 Rei Zitteliana Series A/ An International Journal of Palaeontology and Geobiology Series A /Reihe A Mitteilungen der Bayerischen Staatssammlung für Pa lä on to lo gie und Geologie 46 An International Journal of Palaeontology and Geobiology München 2006 Zitteliana Zitteliana An International Journal of Palaeontology and Geobiology Series A/Reihe A Mitteilungen der Bayerischen Staatssammlung für Pa lä on to lo gie und Geologie 46 CONTENTS/INHALT WOLF OHMERT Radiolarien-Faunen und Obergrenze der Amden-Formation (Coniacium – Santonium) im Tölzer Helvetikum (Oberbayern) 3 DHIRENDRA K. PANDEY & FRANZ T. FÜRSICH Jurassic corals from the Shemshak Formation of the Alborz Mountains, Iran 41 THORSTEN KOWALKE Palaeoclimatic implications of continental saline and fresh water mollusc communities of the Cenozoic Iberian Peninsula 75 GÜNTER SCHWEIGERT The fi rst cycloid arthropod from the Late Jurassic 85 HELGA BÁRA BARTELS-JÓNSDÓTTIR, KAREN LUISE KNUDSEN, JOACHIM SCHÖNFELD, SUSANA LEBREIRO & FATIMA G. ABRANTES Recent benthic foraminifera from the Tagus Prodelta and Estuary, Portugal: microhabitats, assemblage composition and stable isotopes 91 SIMON SCHNEIDER & ALFRED SELMEIER A silicifi ed wood from the church of St. Laurentius in Zeholfi ng (Bavaria, Germany) – an unusual link between archeology and paleontology 105 Instructions for Authors/Hinweise für Autoren 111 Zitteliana A 46 114 Seiten München, 31.12.2006 ISSN 1612-412X Editors-in-Chief/Herausgeber: Michael Krings, Winfried Werner Production and Layout/Bildbearbeitung und Layout: Martine Focke, Manuela Schellenberger Editorial Board A. Altenbach, München B.J. Axsmith, Mobile, AL F.T. Fürsich, Würzburg K. Heißig, München H. Kerp, Münster J. Kriwet, Berlin J.H. Lipps, Berkeley, CA T. Litt, Bonn O.W.M. Rauhut, München B. Reichenbacher, München J.W. Schopf, Los Angeles, CA G. Schweigert, Stuttgart F. Steininger, Frankfurt a.M. Bayerische Staatssammlung für Paläontologie und Geologie Richard-Wagner-Str. 10, D-80333 München, Deutschland http://www.palmuc.de/zitteliana email: [email protected] Für den Inhalt der Arbeiten sind die Autoren allein ver ant wort lich. Authors are solely responsible for the contents of their articles. Copyright © 2006 Bayerische Staassammlung für Pa lä on to lo gie und Geologie, München Die in der Zitteliana veröffentlichten Arbeiten sind urheberrechtlich geschützt. Nachdruck, Vervielfältigungen auf photomechanischem, elektronischem oder anderem Wege sowie die Anfertigung von Übersetzungen oder die Nut zung in Vorträgen, für Funk und Fernsehen oder im Internet bleiben – auch auszugsweise – vorbehalten und bedürfen der schriftlichen Ge neh mi gung durch die Bayerische Staatssammlung für Paläontologie und Geologie, München. ISSN 1612-412X Druck: Gebr. Geiselberger GmbH, Altötting Cover Illustration: Coral Collignonastraea meandra (D´ORBIGNY, 1850) from the Toarcian (Lower Jurassic) of the Kuh-e-Shisui area (Iran); PIW2004III 40. For details see PANDEY & FÜRSICH: Jurassic corals from the Shemshak Formation of the Alborz Mountains, Iran, pp. 41-74 in this issue. Umschlagbild: Koralle Collignonastraea meandra (D´ORBIGNY, 1850) aus dem Toarcium (Unterjura) der Gegend um Kuh-e- Shisui (Iran); PIW2004III 40. Für weitere Infomationen siehe PANDEY & FÜRSICH: Jurassic corals from the Shemshak Formation of the Alborz Mountains, Iran, S. 41–74 in diesem Heft. 41 Zitteliana A46 41-74 3 Textfi gs, 7 Pls, 20 Tabs München, 31.12.2006 ISSN 1612-412X Jurassic corals from the Shemshak Formation of the Alborz Mountains, Iran By Dhirendra K. Pandey & Franz T. Fürsich* 1Department of Geology, University of Rajasthan, Jaipur 302004, Rajasthan, India 2Institut für Paläontologie der Universität Würzburg, Pleicherwall 1, D 97070 Würzburg, Germany Manuscript received July 17, 2006; revision accepted October 30, 2006. Abstract 1. Introduction Nineteen taxa of scleractinian corals are described and Taxonomic work on Jurassic corals from Iran is scanty. fi gured from the Toarcian-Lower Bajocian part of the Shems- FLÜGEL (1966) was the first to describe the coral fauna of a small hak Formation of the Alborz Mountains. Dominant taxa Middle Jurassic patch reef from the eastern margin of the Tabas are Isastrea, Microsolena, Trigerastraea, Periseris, and Colli- Block. He identifi ed 18 taxa based on limited material that was gnonastraea. Most of these corals occur near the top of the made available to him by STÖCKLIN. Based on extensive fi eld formation (Lower Bajocian), close to the top of a large-scale collections PANDEY & FÜRSICH (2003) described and fi gured shallowing cycle. Scattered specimens are found in transgressi- 92 taxa of scleractinian corals from east-central Iran, spanning ve lags of small-scale parasequences in the Toarcian part of the the Toarcian to Kimmeridgian time interval. The corals occur succession. Corals are very rare in the Shemshak Formation scattered or form small patch reefs, partly in association with with the exception of Rian, NE of Semnan, where strongly microbial crusts, in siliciclastic settings but are surprisingly reduced sedimentation rates facilitated the establishment of rare on the extensive carbonate platform (Esfandiar Limestone coral meadows and a patch reef in a mixed carbonate-silici- Formation) that extended along the eastern margin of the Tabas clastic setting on the crest of a tilted fault block. Block. Corals have not been recorded from the Shemshak For- mation of the Alborz Range to date because they represent a Key words: Scleractinia, Jurassic, taxonomy, Shemshak very rare element of the benthic fauna. During fi eld work in the Formation, Alborz Mountains eastern and central Alborz Mountains in the years 2002–2006, more than 100 coral specimens have been collected; they form the basis of the present study. By describing and fi guring this Kurzfassung coral fauna we contribute to the knowledge of the biota of the Shemshak Formation and close a gap in our understanding of Neunzehn Taxa der Scleractinia werden aus der Shemshak- the distribution pattern of corals along the northern margin Formation des Elburz-Gebirges beschrieben und abgebildet. of the Tethys during the Jurassic. Sie stammen aus dem Zeitraum Toarcium-unteres Bajocium und werden von den Gattungen Isastrea, Microsolena, Tri- gerastraea, Periseris, und Collignonastraea dominiert. Die 2. Geological framework meisten Korallen fi nden sich dicht unter dem Top der Forma- tion, im obersten Abschnitt eines großen Verfl achungszyklus. The Shemshak Formation (Upper Triassic–Lower Bajocian) Vereinzelt treten Korallen auch in transgressiven Ästen von of the Alborz Mountains represents a massive pile of silici- Parasequenzen des Toarcium auf. Korallen sind sehr seltene clastic sediments, which may reach up to 4000 m in thickness. Elemente der Benthosfauna der Shemshak-Formation, außer in The formation is widespread not only along the Alborz Range, Rian, nordöstlich Semnan, wo sich aufgrund stark reduzierter but also across other parts of the Iran Plate (Textfi g. 1; SEYED- Nettosedimentation am Top einer rotierten Scholle Korallen- EMAMI et al. 2001). Originally it was interpreted as the fill of rasen und Fleckenriffe auf einem gemischt karbonatisch-sili- a foreland basin that existed south of the rising Cimmerian ziklastischen Substrat etablieren konnten. mountain range (e.g., STÖCKLIN 1974; ALAVI 1996), produced by collision of the Iran Plate with the Turan Plate (part of Schlüsselwörter: Scleractinia, Jura, Taxonomie, Shemshak- Eurasia) during the early Late Triassic (the so-called Early Formation, Elburz-Gebirge Cimmerian Orogeny). New investigations produced a more *Author for correspondence; E-mail: [email protected] 42 Textfi gure 1: Distribution of the Shemshak Formation in the Alborz Mountains with position of coral localities. 1: Golbini; 2: Rian; 3: Sharif- Abad. complex scenario for the evolution of the basin in which the that persisted until the end of the Jurassic and, locally, into sediments of the Shemshak Formation were deposited (FÜRSICH the Cretaceous. It consisted of basinal and slope sediments et al. 2005, 2006). It appears that, in the northern part of the (Dalichai Formation), interspersed with carbonate platforms present-day Alborz Range, a remnant of the Palaeotethys per- (Lar Formation) and deeper, somewhat condensed glauconitic sisted during the Late Triassic. This remnant basin was deeper limestones (Shal Formation), the latter present only in the in the north where low-energy carbonates and fi ne-grained western part of the Alborz Range. argillaceous silts containing ammonites and the posidoniid The non-marine parts of the Shemshak Formation contain bivalve Halobia accumulated and shallower to the south where a rich fl ora (e.g., FAKHR 1977), whereas marine invertebrates in marginal marine, fl uvial and lacustrine conditions prevailed. the marine part are generally scarce and often poorly preserved. Towards the end of the Triassic, the basin became gradually It is solely in the Toarcian-Aalenian part of the succession that infi lled. Around the Triassic-Jurassic boundary, fi nal collision ammonites and bivalves are moderately common, associated between the two plates resulted in increased uplift in the area with rare brachiopods, serpulids, and gastropods. Corals are of the southern part of the present-day Caspian Sea. This is extremely rare and largely confi ned to the Lower Bajocian top indicated by a thick package of conglomerates (up to 1000 m part of the formation where they occur as scattered individuals thick) occurring in the northern