Constraining the onset and environmental setting of metazoan biomineralization: The Ediacaran Nama Group of the Tsaus Mountains, Namibia

Bowyer, Fred T.; Uahengo, Collen-Issia; Kaputuaza, Kavevaza; Ndeunyema, Junias; Yilales, Mariana; Alexander, Ruaridh D.; Curtis, Andrew; Wood, Rachel A.

doi:10.1016/j.epsl.2023.118336

Cited by 11 publications

(28 citation statements)

References 42 publications

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“…575-565 Ma; Rooney et al, 2020;Yang et al, 2021) but pre-date the 1n/BACE. Therefore, if the BANE is distinct from the Shuram excursion, as suggested by current global chemostratigraphic age models (Bowyer et al, 2022;Bowyer, Uahengo, et al, 2023;Rooney et al, 2020;Yang et al, 2021), then the magnitude of the BANE may reflect regional amplification of negative δ 13 C carb values associated with local meteoric diagenesis.…”

Section: δ 13 C and δ 18 O Covariation And Potential Meteoric Influencementioning

confidence: 97%

“…Strata within both sub-basins have been correlated using litho-and chemostratigraphy, and correlation of stratal stacking patterns have informed sequence stratigraphy (figs. 1 and 2; e.g., Bowyer, Uahengo, et al, 2023;Germs, 1983;Nelson et al, 2022;Saylor et al, 1995Saylor et al, , 1998Wood et al, 2015). Intervals of the Nama Group succession have also been accurately age-calibrated via U-Pb zircon geochronology of interbedded tuff deposits (fig.…”

Section: Geological Setting Of the Nama Groupmentioning

confidence: 99%

“…This is supported not only by lithostratigraphic and sequence stratigraphic correlation, but also by observations of δ 13 C carb chemostratigraphy and associated preliminary biostratigraphic considerations in both subbasins (fig. 2; Bowyer, Uahengo, et al, 2023;Maloney et al, 2020;Saylor et al, 1995Saylor et al, , 1998O. Smith, 1999;Wood et al, 2015).…”

Section: δ 13 C and δ 18 O Covariation And Potential Meteoric Influencementioning

confidence: 99%

“…Smith, 1999). Alternatively, the observed differences in trend and magnitude of δ 13 C carb between these sections may record lateral differences in section completeness associated with increasing paleodepth and accommodation space from southeast to northwest within the Zaris Sub-basin (for more information, see supplementary correlation chart of Bowyer, Uahengo, et al, 2023).…”

Section: δ 13 C and δ 18 O Covariation And Potential Meteoric Influencementioning

confidence: 99%

“…≤533 Ma (Nelson et al, 2023), numerous uncertainties remain in the precise age of the 1n/BACE onset (reviewed in Bowyer et al, 2022), and the sequence of regional and global biotic first appearances across the 1n/ BACE (e.g., Bowyer, Zhuravlev, et al, 2023;Topper et al, 2022). The 1n/BACE has been recorded in multiple successions globally (e.g., Bowyer, Uahengo, et al, 2023;Hodgin et al, 2021;Kouchinsky et al, 2007;Maloof et al, 2010;E. F. Smith, Nelson, et al, 2016;Topper et al, 2022;Zhu et al, 2019), but is notably absent from the Nama Group (Nelson et al, 2022;Saylor et al, 1998;Wood et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Insights Into the Terminal Ediacaran Marine Carbonate Record From Shale-Hosted Carbonate Carbon Isotopes

Bowyer,

Yilales,

Wood

et al. 2023

American Journal of Science

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The marine carbon isotope record (δ13C) used for chemostratigraphy and reconstruction of carbon cycle dynamics is commonly assembled using carbonate rocks. There is, however, evidence that carbonate cements hosted within fine-grained clastics (shales and mudstones) in some settings may also express δ13C trends that covary with the record from carbonates. We present new carbon and oxygen isotopic data from shale-hosted carbonate cements (herein termed δ13Ccarb-sh and δ18Ocarb-sh, n = 107, <16 wt% CaCO3) of the terminal Ediacaran Nama Group, Namibia (≥550.5 to <539.6 Million years ago; Ma). These data are compared with the published carbon and oxygen isotopic record from coeval carbonates (δ13Ccarb and δ18Ocarb, n = 1611) and total organic carbon (TOC) concentrations. We show that, in the Nama Group, δ13Ccarb-sh compositions in samples of intermediate to high CaCO3/TOC (>0.4) can approximate contemporaneous δ13Ccarb in open marine mixed carbonate-clastic settings. By contrast, δ13Ccarb-sh values in samples with low CaCO3/TOC (<0.4) that were deposited in clastic settings distant from the locus of carbonate deposition are more negative than contemporaneous δ13Ccarb. These data suggest that δ13Ccarb-sh may approach seawater composition in samples with low TOC when deposited in settings characterized by high CO32- concentration, where carbonate can rapidly precipitate from seawater during early diagenesis. However, the use of δ13Ccarb-sh to infill gaps in the existing δ13Ccarb record remains uncertain, even when these criteria are fulfilled. Intervals of δ13C-δ18O co-variability in the Nama Group succession appear to correlate with units where seawater mixing with meteoric fluids was more likely during early diagenesis, such as clastic-dominated settings, which also show significant decreasing δ18O through time with gradual sub-basin infill. We further consider uncertainties in lithostratigraphic correlation of the upper Urusis Formation of the Nama Group that enable three new possible correlations to be proposed for δ13Ccarb-sh data within the terminal Ediacaran to lower Cambrian (<542.65 Ma to >532 Ma) regional and global δ13Ccarb records.

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Section: δ 13 C and δ 18 O Covariation And Potential Meteoric Influencementioning

confidence: 97%

Section: Geological Setting Of the Nama Groupmentioning

confidence: 99%

Section: δ 13 C and δ 18 O Covariation And Potential Meteoric Influencementioning

confidence: 99%

Section: δ 13 C and δ 18 O Covariation And Potential Meteoric Influencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Insights Into the Terminal Ediacaran Marine Carbonate Record From Shale-Hosted Carbonate Carbon Isotopes

Bowyer,

Yilales,

Wood

et al. 2023

American Journal of Science

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Interglacial dust, ocean fertilisation and Neoproterozoic earth oxygenation

DaSilva,

Pufahl,

James

2024

The Depositional Record

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Feedback processes that drove Earth's second major increase in ocean–atmosphere oxygen levels during the Neoproterozoic are poorly constrained. Variability in seawater redox over geological timescales is commonly linked to changes in the biogeochemical cycling of P and thus the rate of primary production and generation of photosynthetic oxygen. In the modern surface ocean, an important source of bioessential P and micronutrients (Fe, Cu, Co, Zn, Mo, Cr and Ni) is aeolian dust derived from deserts and arid, post‐glacial landscapes. It is interpreted herein that glacial retreat following the Sturtian (ca 717 to 660 Ma) and Marinoan (ca 650 to 635 Ma) snowball glaciations provided copious dust to the global ocean. Correlation of interglacial siltstone successions in palaeogeographical context suggests that such dust accumulation was diachronous and concentrated in the palaeo‐horse latitudes (30° N and 30° S). Delivery of this dust from continents is likely reflected in the steep increase in global radiogenic Sr isotope values (87Sr/86Sr) in post‐Sturtian carbonates, and changes in the δ18O signatures of Cryogenian zircons derived from subducted marine sediments. Accumulation of sedimentary organic matter also peaked during interglacial periods, suggesting a causal link between glaciation, aeolian dust and primary production. This relationship implies windblown dust was an important source of P and micronutrients for an evolving biological pump that stimulated primary production, enhanced burial of organic carbon and increased ocean–atmosphere oxygen concentrations. Thus, delivery of aeolian dust to the global ocean was likely critical for sustaining Earth's second major increase in oxygen. Sequestration of atmospheric CO2 in organic‐rich siltstones and shales is also interpreted to have been an important negative feedback process, which together with silicate weathering, prevented runaway greenhouse conditions during interglacial periods. The oxygen produced by this aeolian marine biological pump may have helped pave the way for the evolution of multicellular animals in the Ediacaran.

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Invertebrates Are Heavy Metal: An Overview of Armor, Weapons, and Other Cuticular Adaptations of Diverse Lineages

Lehnert

2024

Biologically-Inspired Systems

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Constraining the onset and environmental setting of metazoan biomineralization: The Ediacaran Nama Group of the Tsaus Mountains, Namibia

Cited by 11 publications

References 42 publications

Insights Into the Terminal Ediacaran Marine Carbonate Record From Shale-Hosted Carbonate Carbon Isotopes

Insights Into the Terminal Ediacaran Marine Carbonate Record From Shale-Hosted Carbonate Carbon Isotopes

Interglacial dust, ocean fertilisation and Neoproterozoic earth oxygenation

Invertebrates Are Heavy Metal: An Overview of Armor, Weapons, and Other Cuticular Adaptations of Diverse Lineages

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