Global Cambrian correlation-ca. 517.5 Ma Coleoloides typicalis griotte at the CARE excursion (Series 2) caps the "subtrilobitic" Lower Cambrian across "west" and "east" (North American and British) Avalonia
Landing, E.; Geyer, G.; Pas, D. (2026). Global Cambrian correlation-ca. 517.5 Ma Coleoloides typicalis griotte at the CARE excursion (Series 2) caps the "subtrilobitic" Lower Cambrian across "west" and "east" (North American and British) Avalonia. Earth-Sci. Rev. 280: 105556. https://dx.doi.org/10.1016/j.earscirev.2026.105556
In: Earth-Science Reviews. Elsevier: Amsterdam; Lausanne; London; New York; Oxford; Shannon. ISSN 0012-8252; e-ISSN 1872-6828, meer
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| Author keywords |
Avalonia paleocontinent;Cambrian;Coleoloides griotte;"Subtrilobitic" Cambrian;Atlantic Canada;English Midlands;EAREZE excursion;small shelly fossils;chapel island formation;mainland nova-scotia;placentian series;detrital zircon;stratigraphy;platform;faunas;terranes;paleoenvironments |
| Auteurs | | Top |
- Landing, E.
- Geyer, G.
- Pas, D., meer
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| Abstract |
Nodular red limestones (griotte) packed with in situ "worm tubes" (Coleoloides typicalis) occur in the uppermost "subtrilobitic" Lower Cambrian along the Avalonia terrane of the Appalachian-Caledonian orogen. The C. typicalis beds are younger than the Series 2-3 boundary marked by the EAREZE excursion (ca. 520 Ma) peak and record the CARE excursion (lower Series 3, ca. 517.5 Ma). The shallow water griotte occurs for ca. 1600 km (Atlantic Canada-English Midlands), links "west" and "east" Avalonia into one paleocontinent, is a time-specific litho-and biofacies of the Avalonian inner platform and inner-marginal platform transition, and is absent in shallower facies immediately SE. Eurytopic C. typicalis ranged from offshore mudstone to peritidal limestone in its long Lower Cambrian range. It became more abundant than the orthothecid "Ladatheca" cylindrica (also known from vertical, in situ conchs) higher in the Lower Cambrian. In situ "L." cylindrica and C. typicalis in mud mounds were temperate latitude, ecologic analogs to coeval, tropical archaeocyath buildups. The C. typicalis griotte is below a ca. 0.3 Ma hiatus with the trilobite-bearing Lower Cambrian (Callavia broeggeri Zone) at the Avalonian depositional sequence 3-4 unconformity. Aragonitic C. typicalis tubes have longitudinal ridges and an adventitious lengthwise slit which probably allowed flexing and twisting in waves and currents. Their closely spaced conchs suggest little inter-individual competition and asexual budding. Coleoloides and other vertically embedded phosphatic and aragonitic forms (Hyolithellus, several orthothecids) persisted into the onset of a calcitic ocean with mineralized trilobites and echinoderms. |
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