Discussion of 'Reply to "Uppermost Cambrian carbon chemostratigraphy: the HERB and undocumented TOCE events are not synonymous"'. (2nd January 2022)

• Record Type: Journal Article
• Authors: Landing, ED; Ripperdan, Robert L.; Geyer, Gerd
• Is Part Of: Geological magazine. Volume 159:Number 1(2022)
• Page Start: 173
• Page End: 176
• Publication Date: 2022-01-02
• Subjects: Cambrian -- carbon isotope excursions -- HERB excursion -- "TOCE"; Geology -- Periodicals; 551.05
• DOI: 10.1017/S001675682100090X
• Languages: English
• ISSNs: 0016-7568

Abstract

Abstract: No basis for controversy exists in the naming of a global, strongly negative, uppermost Cambrian carbon isotope (δ 13 C) 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 δ 13 C 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.