Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
A geochemical study of the Ediacaran discoidal fossil Aspidella preserved in limestones : Implications for its taphonomy and paleoecology. / Bykova, N.; Gill, B. C.; Grazhdankin, D. и др.
в: Geobiology, Том 15, № 4, 01.07.2017, стр. 572-587.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
}
TY - JOUR
T1 - A geochemical study of the Ediacaran discoidal fossil Aspidella preserved in limestones
T2 - Implications for its taphonomy and paleoecology
AU - Bykova, N.
AU - Gill, B. C.
AU - Grazhdankin, D.
AU - Rogov, V.
AU - Xiao, S.
N1 - © 2017 John Wiley & Sons Ltd.
PY - 2017/7/1
Y1 - 2017/7/1
N2 - The Ediacara biota features the rise of macroscopic complex life immediately before the Cambrian explosion. One of the most abundant and widely distributed elements of the Ediacara biota is the discoidal fossil Aspidella, which is interpreted as a subsurface holdfast possibly anchoring a frondose epibenthic organism. It is a morphologically simple fossil preserved mainly in siliciclastic rocks, which are unsuitable for comprehensive stable isotope geochemical analyses to decipher its taphonomy and paleoecology. In this regard, three-dimensionally preserved Aspidella fossils from upper Ediacaran limestones of the Khatyspyt Formation in the Olenek Uplift of northern Siberia offer a rare opportunity to leverage geochemistry for insights into their taphonomy and paleoecology. To take advantage of this opportunity, we analyzed δ13Ccarb, δ18Ocarb, δ13Corg, δ34Spyr, and iron speciation of the Khatyspyt Aspidella fossils and surrounding sediment matrix in order to investigate whether they hosted microbial symbionts, how they were fossilized, and the redox conditions of their ecological environments. Aspidella holdfasts and surrounding sediment matrix show indistinguishable δ13Corg values, suggesting they did not host and derive significant amount of nutrients from microbial symbionts such as methanogens, methylotrophs, or sulfide-oxidizing bacteria. δ13Ccarb, δ18Ocarb, and δ34Spyr data, along with petrographic observations, suggest that microbial sulfate reduction facilitated the preservation of Aspidella by promoting early authigenic calcite cementation in the holdfasts before matrix cementation and sediment compaction. Iron speciation data are equivocal, largely because of the low total iron concentrations. However, consideration of published sulfur isotope and biomarker data suggests that Aspidella likely lived in non-euxinic waters. It is possible that Aspidella was an opportunistic organism, colonizing the seafloor in large numbers when paleoenvironments were favorable. This study demonstrates that geochemical data of Ediacaran fossils preserved in limestones can offer important insights into the taphonomy and paleoecology of these enigmatic organisms living on the eve of the Cambrian explosion.
AB - The Ediacara biota features the rise of macroscopic complex life immediately before the Cambrian explosion. One of the most abundant and widely distributed elements of the Ediacara biota is the discoidal fossil Aspidella, which is interpreted as a subsurface holdfast possibly anchoring a frondose epibenthic organism. It is a morphologically simple fossil preserved mainly in siliciclastic rocks, which are unsuitable for comprehensive stable isotope geochemical analyses to decipher its taphonomy and paleoecology. In this regard, three-dimensionally preserved Aspidella fossils from upper Ediacaran limestones of the Khatyspyt Formation in the Olenek Uplift of northern Siberia offer a rare opportunity to leverage geochemistry for insights into their taphonomy and paleoecology. To take advantage of this opportunity, we analyzed δ13Ccarb, δ18Ocarb, δ13Corg, δ34Spyr, and iron speciation of the Khatyspyt Aspidella fossils and surrounding sediment matrix in order to investigate whether they hosted microbial symbionts, how they were fossilized, and the redox conditions of their ecological environments. Aspidella holdfasts and surrounding sediment matrix show indistinguishable δ13Corg values, suggesting they did not host and derive significant amount of nutrients from microbial symbionts such as methanogens, methylotrophs, or sulfide-oxidizing bacteria. δ13Ccarb, δ18Ocarb, and δ34Spyr data, along with petrographic observations, suggest that microbial sulfate reduction facilitated the preservation of Aspidella by promoting early authigenic calcite cementation in the holdfasts before matrix cementation and sediment compaction. Iron speciation data are equivocal, largely because of the low total iron concentrations. However, consideration of published sulfur isotope and biomarker data suggests that Aspidella likely lived in non-euxinic waters. It is possible that Aspidella was an opportunistic organism, colonizing the seafloor in large numbers when paleoenvironments were favorable. This study demonstrates that geochemical data of Ediacaran fossils preserved in limestones can offer important insights into the taphonomy and paleoecology of these enigmatic organisms living on the eve of the Cambrian explosion.
KW - Aspidella
KW - carbon isotopes
KW - Ediacaran fossils
KW - iron speciation
KW - Siberia
KW - sulfur isotopes
KW - NORTHWESTERN CANADA
KW - ARCTIC SIBERIA
KW - TRACE FOSSILS
KW - CAMBRIAN BOUNDARY
KW - OCEAN OXYGENATION
KW - SULFATE REDUCTION
KW - OLDEST EVIDENCE
KW - SOUTH CHINA
KW - SULFUR ISOTOPE FRACTIONATION
KW - MICROBIAL MATS
KW - Calcium Carbonate/chemistry
KW - Oxidation-Reduction
KW - Biota
KW - Fossils
KW - Animals
KW - Geologic Sediments/chemistry
UR - http://www.scopus.com/inward/record.url?scp=85017661253&partnerID=8YFLogxK
U2 - 10.1111/gbi.12240
DO - 10.1111/gbi.12240
M3 - Article
C2 - 28397387
AN - SCOPUS:85017661253
VL - 15
SP - 572
EP - 587
JO - Geobiology
JF - Geobiology
SN - 1472-4677
IS - 4
ER -
ID: 10263821