Red Devonian trilobites with green eyes from Morocco and the silicification of the trilobite exoskeleton

• Autorzy: Klug C , Schulz H. , De Baets K.
• Języki publikacji: EN

Abstrakty

EN

Latest Emsian (Early Devonian) sediments at the famous mud−moundand trilobite−locality Hamar Laghdad (Tafilalt, Morocco) yielded some red−coloured remains of phacopid trilobites. Closer examination revealed that the eyes of these phacopids are often greenish in colour. EDX−analyses showed that the lenses retained their original calcitic composition, possibly greenish due to Feand Mn−impurities, while most of the exoskeleton was silicified. The silicified parts contain elevated concentrations of iron which causes the red colour. This phenomenon is explained by the porosity of the exoskeleton in contrast to the homogeneous and massive construction of the lenses and their Mg−content. These incompletely silicified trilobites enabled a reconstruction of the silicification process in trilobites. Their diagenetic alteration probably occurred as a result of events associated with the Cretaceous transgression.

Słowa kluczowe

EN

trilobite; silicification; diagenesis; Trilobita; Morocco; paleontology; mud mound; taphonomy; exoskeleton; transgression; Devonian

• Wydawca: -
• Czasopismo: Acta Palaeontologica Polonica
• Rocznik: 2009
• Tom: 54
• Numer: 1
• Opis fizyczny: p.117-123,fig.,ref.

Twórcy

autor

Klug C

• Palaontologisches Institut und Museum der Universitat Zurich, Karl Schmid-Str.4, CH-8006 Zurich, Switzerland

autor

Schulz H.

autor

De Baets K.

Bibliografia

• Alberti, G.K.B. 1969. Trilobiten des jüngeren Siluriums sowie des Unter− und Miteldevons. I. Mit Beiträgen zur Silur−Devon−Stratigraphie einiger Gebiete Marokkos und Oberfrankens. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft 520: 1–692.
• Alberti, G.K.B. 1980. Neue Daten zur Grenze Unter−/Mittel−Devon, vornehmlich aufgrund der Tentaculiten und Trilobiten im Tafilalt (SE−Marokko). Neues Jahrbuch für Geologie und Paläontologie, Monatshefte 1980 (10): 581–594.
• Alberti, G.K.B. 1982. Der Hamar Laghdad (Tafilalt, SE Marokko), eine bedeutende Fundstelle devonischer Trilobiten. Natur & Museum 112: 172–182.
• Aitken, S.A., Colom, J.C., Henderson, C.M., and Johnston, P.A. 2002. Stratigraphy, paleoecology, and origin of Lower Devonian (Emsian) carbonate mud buildups, Hamar Laghdad, eastern Anti−Atlas, Morocco, Africa. Bulletin of Canadian Petroleum Geology 50: 217–243.
• Barrande, J. 1865. Systême Silurien du centre de la Bohême. I. Vol. II. Cephalopodes. 107 plates. By the author, Praha.
• Belka, Z. 1994. Dewońskie budowle węglanowe (Carbonate buildups) Sahary Środkowej i ich związek z podmorskimi źródłami termalnymi (Carbonate mud buildups in the Devonian of the Central Sahara: evidences for submarine hydrothermal venting). Przegląd Geologiczny 5: 341–346.
• Belka, Z. 1998. Early Devonain Kess−Kess carbonate mud mounds of the eastern Anti−Atlas (Morocco), and their relation to submarine hydrothermal venting. Journal of Sedimentary Research 68: 368–377.
• Belka, Z., Klug, C., Kaufmann, B., Korn, D., Döring, S., Feist, R., and Wendt, J. 1999. Devonian conodont and ammonoid succession of the eastern Tafilalt (Ouidane Chebbi section), Anti−Atlas, Morocco). Acta Geologica Polonica 49: 1–23.
• Berkowski, B. 2006. Vent and mound rugose coral associations from the Middle Devonian of Hamar Laghdad (Anti−Atlas, Morocco). Geobios 39: 155–170.
• Brachert, T., Buggisch, W., Flügel, E., Hüssner, H., Joachimski, M.M., and Tourneur, F. 1992. Controls of mud mound formation: the Early Devonian Kess−Kess carbonates of the Hamar Laghdad, Antiatlas, Morocco. Geologische Rundschau 81: 15–44.
• Bruton, D.L. and Haas, W. 2003. The puzzling eye of Phacops. In: P.D. Lane, D.J. Siveter, and R.A. Fortey (eds.), Trilobites and Their Relatives. Special Papers in Palaeontology 70: 349–361.
• Buch, L. von 1832. Über Goniatiten. Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin, Physikalische Klasse 1830: 159–187.
• Bultynck, P. and Walliser, O.H. 2000. Emsian to Middle Frasnian sections in the northern Tafilalt. In: A. El Hassani and A. Tahiri (eds.), Moroccan Meeting of the Subcommision on Devonian Stratigraphy (SDS)—IGCP 421 Excursion Guidebook. Notes et Mémoires du Service Géologique du Maroc 399: 11–20.
• Cavalazzi, B., Barbieri, R., and Ori, G.G. 2007. Chemosynthetic microbialites in the Devonian carbonate mounds of Hamar Laghdad (Anti−Atlas, Morocco). Sedimentary Geology 200: 73–88.
• Chatterton, B., Fortey, R. Brett, K., Gibb, S., and McKellar, R. 2006. Trilobites from the upper Lower to Middle Devonian Timrhanrhart Formation, Jbel Gara el Zguilma, southern Morocco. Palaeontographica Canadiana 25: 1–177.
• Chlupáč, I. and Turek, V. 1983: Devonian goniatites from the Barrandian area, Czechoslovakia. Rozpravy Ústredního ústavu geologického 46: 1–159.
• Clarkson, E.N.K. and Levi−Setti, R. 1975. Trilobite eyes and the topics of Des Cartes and Huygens. Nature 254: 663–667.
• Dalingwater, J.E., Hutchinson, S.J., Mutvei, H., and Siveter D.J. 1991. Cuticular ultrastructure of the trilobiteEllipsocephalus polytomusfrom the Middle Cambrian of Öland, Sweden. Palaeontology 34: 205–217.
• Dalingwater, J.E., Siveter D.J., and Mutvei, H. 1993. Cuticular ultrastructure of some Silurian calymenid trilobites from the Welsh Borderland and Gotland. Palaeontolographica A 229: 37–49.
• Dalingwater, J.E., Siveter D.J., and Mutvei, H. 1999. Cuticular microstructure of some Silurian homalonotid trilobites from Sweden. Journal of Paleontology 73: 256–262.
• Dick, V. and Brett, C.E. 1986. Petrology, taphonomy and sedimentary environments of pyritic fossil beds from the Hamilton Group (Middle Devonian) of western New York. In: C.E. Brett (ed.), Dynamic Stratigraphy and Depositional Environment of the Hamilton Group (Middle Devonian) in New York State. Part 1. New York State Museum Bulletin 457: 102–128.
• Erben, H.K. 1953. Goniatitacea (Ceph.) aus dem Unterdevon und Unterem Mitteldevon. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 98: 175–225.
• Fortey, R. and Chatterton, B. 2003. A Devonian trilobite with an eye−shade. Science 301: 1689.
• Hassan, F. 1978. Impurity−related centers in a pale green calcite crystal. American Mineralogist 63: 732–736.
• Hollard, H. 1974. Recherches sur la stratigraphie des formations du Dévonien moyen, de l’Emsien supérieur au Frasnien, dans le Sud du Tafilalt et dans le Ma’der (Anti−Atlas oriental).Notes et Mémoires du Service Géologique du Maroc 264: 7–68.
• Kaufmann, B. 1997. Diagenesis of Middle Devonian Carbonate mounds of the Mader Basin (eastern Anti−Atlas, Morocco). Journal of Sedimentary Research 67: 945–956.
• Kaufmann, B. 1998. Facies, stratigraphy and diagenesis of Middle Devonian reef− and mud−mounds in the Mader (eastern Anti−Atlas, Morocco). Acta Geologica Polonica 48: 43–106.
• Kaufmann, B. 2006. Calibrating the Devonian Time Scale: A synthesis of U−Pb ID−TIMS ages and conodont stratigraphy. Earth Science Reviews 76: 175–190.
• Klug, C. 2002. Quantitative stratigraphy and taxonomy of late Emsian and Eifelian ammonoids of the eastern Anti−Atlas (Morocco). Courier Forschungsinstitut Senckenberg 238: 1–109.
• Klug, C. 2007. Healed injuries on the shells of Early Devonian cephalopods from Morocco. Acta Palaeontologica Polonica 52: 799–808.
• Klug, C., Meyer, E., Richter, U., and Korn, D. 2008. Soft−tissue imprints in fossil and Recent cephalopod septa and septum formation. Lethaia 41: 477–492.
• Lee, M.R., Torney, C., and Owen, A.W. 2007. Magnesium−rich intralensar structures in schizochroal trilobite eyes. Palaeontology 50: 1031–1037.
• Massa, D., Combaz, A., and Manderscheid, G. 1965. Observations sur les séries Siluro−Dévoniennes des confins Algéro−Marocains du Sud. Notes et Mémoires, Compagnie FranVaise des Pétroles 8: 1–187.
• McAllister, J.E. and Brand, U. 1989. Primary and diagenetic microstructures in trilobites. Lethaia 22: 101–111.
• Roch, E. 1934. Sur des phénomènes remarquables observés dans la région d’Erfoud (confins algéro−marocains du Sud). Association Études de la Géologie Méditerranéenne Occidentale 5: 1–10.
• Teigler, D.J. and Towe, K.M. 1975. Microstructure and composition of the trilobite exoskeleton. Fossils and Strata 4: 137–149.
• Töneböhn, R. 1991. Bildungsbedingungen epikontinentaler Cephalopodenkalke (Devon, SE−Marokko). Göttinger Arbeiten zur Geologie und Paläontologie 47: 1–114.
• Wendt, J. 1993. Steep−sided carbonate mud mounds in the Middle Devonian of the eastern Anti−Atlas, Morocco. Geological Magazine 130: 69–83.