T158 Life's Innovations from the Early Earth to the Search on Modern Mars: Honoring the Career of Andrew H. Knoll (Posters)

Tuesday, 12 October 2021
9:00 AM - 1:00 PM
Exhibit Hall A

TUBULAR FOSSILS FROM THE LATE EDIACARAN LA CIÉNEGA FORMATION, SONORA, MEXICO

Paper number: T158-5
Program: Technical Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

The terminal Ediacaran Period hosts a diversity of cloudinomorphic and other millimeter-scale tubular fossils, which are thought to be among the earliest biomineralizing metazoans. Selectively to fully silicified cloudinomorph and tubular fossils are preserved as dense polytaxic packstone/wackestone accumulations in a <5-meter interval of cross-bedded dolostone within the terminal Ediacaran La Ciénega Formation in Sonora, Mexico. Samples of this unit were dissolved in dilute acetic acid and the residues were imaged using a scanning electron microscope. Block samples were also volume imaged using x-ray tomographic microscopy. Over 100 extracted specimens of tubular fossils and fragments were examined and sorted into groups by morphology. Specimens which had blunt or flared nested funnels (n = 27 and 26, respectively) are tentatively grouped as two distinct morphologies of Cloudina, and annulated tubes (n = 35) were grouped as probable Sinotubulites. Other specimens were smooth-walled and appear similar to Cambrotubulus, which were grouped into either straight or curved morphologies (n = 20 and 11, respectively). Additionally, there were at least 25 ambiguous samples that we could not assign to any generic group. Specimens grouped as Cloudina- and Sinotubulites-like occasionally demonstrated twisted and compressed structures as well as elliptical cross sections, which we interpret as plastic deformation prior to taphonomic silicification, suggesting that these tubes were likely flexible in vivo.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-365438

© Copyright 2021 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.