25-7 Integrative Stratigraphy and Detrital Zircon Provenance for Cambrian Strata in Southeastern Arizona

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

Presenting Author:

Jason Muhlbauer

Authors:

Muhlbauer, Jason G.¹, Schmitz, Mark D.², Mohr, Michael T.³, Sundberg, Frederick A.⁴, Dehler, Carol M.⁵, Karlstrom, Karl E.⁶, Hagadorn, James W.⁷

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 Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7747

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