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Discussion of ‘Reply to “Uppermost Cambrian carbon chemostratigraphy: the HERB and undocumented TOCE events are not synonymous”’

Published online by Cambridge University Press:  02 November 2021

ED Landing Open the ORCID record for ED Landing [Opens in a new window] ,
Robert L. Ripperdan  and
Gerd Geyer Open the ORCID record for Gerd Geyer [Opens in a new window]
ED Landing*
Affiliation:
New York State Museum, 222 Madison Avenue, Albany, NY 12230, USA Montgomery County Public Schools, Montgomery City, MO 63361, USA
Robert L. Ripperdan
Affiliation:
Montgomery County Public Schools, Montgomery City, MO 63361, USA
Gerd Geyer
Affiliation:
Lehrstuhl für Geodynamik und Geomaterialforschung, Institut für Geographie und Geologie, Bayerische Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
*
Author for correspondence: Ed Landing, Email: [email protected]
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Abstract

No basis for controversy exists in the naming of a global, strongly negative, uppermost Cambrian carbon isotope (δ13C) excursion. The HERB Event (HERB) has met the standards for chemostratigraphic units (i.e. consistent biostratigraphic brackets, content and concept) since 1992. By comparison, the TOCE excursion morphed through four temporally distinct δ13C events with spike-like nadirs that shifted temporally through the uppermost Cambrian until its synonymization with HERB (2006–12). In 2018, TOCE became a prolonged interval with very early onset and enveloped HERB – meaning five TOCE homonyms have been unambiguously defined and figured. HERB lies in the high-diversity ptychaspid biomere (trilobites) and below the ptychaspid extinction. But, data on it were used in TOCE’s 2006 proposal and in later iterations (2008, 2012) to show it (1) higher, both at and above the ptychaspid extinction; (2) at the level of HERB (2012, 2018); and (3) even extending well below HERB (2018). TOCE fails the recommendations for a formal chemostratigraphic unit. Its relationship to latest Cambrian biotic turnover includes equation with extinction and high-diversity intervals. One TOCE homonym is a synonym, albeit junior, of HERB.

Keywords

Cambriancarbon isotope excursionsHERB excursion“TOCE”
Type
Discussion - Reply
Information
Geological Magazine , Volume 159 , Issue 1 , January 2022 , pp. 173 - 176
Copyright
© The Author(s), 2021. Published by Cambridge University Press

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