25 Refining the Cambrian—Biotas, Multiproxy Correlations, Workable Global Divisions, and Paleogeography: Discussions in Honor of Fred Sundberg

Eumetazoan diversification and origin of relatively modern marine ecosystems make the Cambrian a key Phanerozoic interval. This session focuses on the correlation significance of improved chemostratigraphic, biostratigraphic, astrochronologic, atmospheric, and oceanic syntheses; geochronology; and new paleogeographic and paleoclimatologic work.

Sunday, 19 October 2025
8:00 AM - 12:00 PM
HBGCC, 305

Integrative Stratigraphy and Detrital Zircon Provenance for Cambrian Strata in Southeastern Arizona

Paper number: 25-8
Program: Technical Sessions
Time: 10:00 AM – 10:15 AM

Authors

Abstract

New trilobite biostratigraphy, chemostratigraphy and tandem in situ and isotope dilution detrital zircon U–Pb geochronology from the Bolsa Quartzite and overlying Abrigo Formation in southeastern Arizona provide insights into Cambrian depositional systems, Laurentian tectonics, and the geologic time scale. In the Whetstone Mountains at French Joe Canyon, we establish the Ehmaniella Biozone in the lowermost Abrigo Formation and the Aphelaspis Biozone in its upper member. Maximum depositional ages constrain Bolsa Quartzite deposition to ≤ 2 m. y. (502.40 ± 0.55 Ma to ~500.7 Ma) during the Topazan (Wuliuan) and the uppermost Abrigo Formation to Sunwaptan (Stage 10) or younger (≤ 488.34 ± 0.59 Ma). Primary δ13C chemostratigraphic signals in the succession appear to correspond to the global record. Cambrian detrital zircons are derived from both known (Florida Mountains granite, NM; McClure Mountain syenite, CO) and unknown Laurentian igneous sources. We test if granitic rocks without high precision geochronology in the Florida Mountains area may explain the unknown provenance of abundant c.a. 506–502 Ma detrital zircon recovered from the Bolsa Quartzite. Geochronologic results require that the Drumian Age began at ≤ 502.40 ± 0.55 Ma and that the Sauk II transgression reached southeastern Arizona ~3–7 m. y. after passing the Grand Canyon region in northern Arizona.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412852

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.