Ediacaran life close to land: coastal and shoreface habitats of the Ediacaran macrobiota in the central and southern Flinders Ranges, South Australia

McMahon, William and Liu, Alexander G. and Tindal, Benjamin and Kleinhans, Martin (2020) Ediacaran life close to land: coastal and shoreface habitats of the Ediacaran macrobiota in the central and southern Flinders Ranges, South Australia. Journal of Sedimentary Research. ISSN 1527-1404 DOI https://doi.org/10.2110/jsr.2020.029

[img] Text
i1527-1404-90-11-1463.pdf - Published Version
Available under License Creative Commons Attribution.

Download (9MB)
[img] Text
JSR_029_Cpdf.pdf - Accepted Version
Restricted to Repository staff only

Download (9MB) | Request a copy
Official URL: https://pubs.geoscienceworld.org/sepm/jsedres/arti...


The Rawnsley Quartzite of South Australia hosts some of the world's most diverse Ediacaran macrofossil assemblages, with many of the constituent taxa interpreted as early representatives of metazoan clades. Globally, a link has been recognized between the taxonomic composition of individual Ediacaran bedding-plane assemblages and specific sedimentary facies. Thorough characterization of fossil-bearing facies is thus of fundamental importance for reconstructing the precise environments and ecosystems in which early animals thrived and radiated, and distinguishing between environmental and evolutionary controls on taxon distribution. This study refines the paleoenvironmental interpretations of the Rawnsley Quartzite (Ediacara Member and upper Rawnsley Quartzite). Our analysis suggests that previously inferred water depths for fossil bearing facies are overestimations. In the central regions of the outcrop belt, rather than shelf and submarine canyon environments below maximum (storm-weather) wave base, and offshore environments between effective (fair-weather) and maximum wave base, the succession is interpreted to reflect the vertical superposition and lateral juxtaposition of unfossiliferous non-marine environments with fossil-bearing coastal and shoreface settings. Facies comprise: 1 and 2) Amalgamated channelized and cross-bedded sandstone (major and minor tidally influenced river and estuarine channels, respectively); 3) Ripple cross-laminated heterolithic sandstone (intertidal mixed-flat); 4) Silty-sandstone (possible lagoon); 5) Planar-stratified sandstone (lower shoreface); 6) Oscillation-ripple facies (middle shoreface); 7) Multi-directed trough- and planar-cross-stratified sandstone (upper shoreface); 8) Ripple cross-laminated, planar-stratified rippled sandstone (foreshore); 9) Adhered sandstone (backshore); and 10) Planar-stratified and cross-stratified sandstone with ripple cross-lamination (distributary channels). Surface trace fossils in the foreshore facies represent the earliest known evidence of mobile organisms in intermittently emergent environments. All facies containing fossils of the Ediacaran macrobiota remain definitively marine. Our revised shoreface and coastal framework creates greater overlap between this classic �White Sea� biotic assemblage and those of younger, relatively depauperate �Nama�-type biotic assemblages located in Namibia. Such overlap lends support to the possibility that the apparent biotic turnover between these assemblages may reflect a genuine evolutionary signal, rather than the environmental exclusion of particular taxa.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 04 - Palaeobiology
07 - Sedimentary Geology
Divisions: 04 - Palaeobiology
08 - Green Open Access
11 - Sedimentary Geology
Journal or Publication Title: Journal of Sedimentary Research
Identification Number: https://doi.org/10.2110/jsr.2020.029
Depositing User: Sarah Humbert
Date Deposited: 23 Dec 2020 21:01
Last Modified: 13 Jan 2021 17:12
URI: http://eprints.esc.cam.ac.uk/id/eprint/5977

Actions (login required)

View Item View Item

About cookies