A stratified redox model for the Ediacaran ocean.
The Ediacaran Period (635 to 542 million years ago) was a time of fundamental environmental and evolutionary change, culminating in the first appearance of macroscopic animals. Here, we present a detailed spatial and temporal record of Ediacaran ocean chemistry for the Doushantuo Formation in the Nanhua Basin, South China. We find evidence for a metastable zone of euxinic (anoxic and sulfidic) waters impinging on the continental shelf and sandwiched within ferruginous [Fe(II)-enriched] deep waters. A stratified ocean with coeval oxic, sulfidic, and ferruginous zones, favored by overall low oceanic sulfate concentrations, was maintained dynamically throughout the Ediacaran Period. Our model reconciles seemingly conflicting geochemical redox conditions proposed previously for Ediacaran deep oceans and helps to explain the patchy temporal record of early metazoan fossils.
Department of Earth Sciences, University of California, Riverside, CA 92521, USA. chaoli@ucr.edu
Chao
C
Li
Gordon D
GD
Love
Timothy W
TW
Lyons
David A
DA
Fike
Alex L
AL
Sessions
Xuelei
X
Chu
D000818:Animals; D005075:Biological Evolution; D002254:Carbonates / Q000032:analysis; D002681:China; D005296:Ferrous Compounds / Q000032:analysis; D005580:Fossils; D019015:Geologic Sediments / Q000737:chemistry*; D006862:Hydrogen Sulfide; D007501:Iron; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis*; D012623:Seawater / Q000737:chemistry*; D013431:Sulfates / Q000032:analysis
D002254:Carbonates; D005296:Ferrous Compounds; D013431:Sulfates; D007501:Iron; D010100:Oxygen; D006862:Hydrogen Sulfide