Pb, O, and C isotopes in silicified Mooidraai dolomite (Transvaal Supergroup, South Africa): implications for the composition of Paleoproterozoic seawater and ‘dating’ the increase of oxygen in the Precambrian atmosphere

Bau, Michael; Romer, Rolf L.; Lüders, Volker; Beukes, Nicolas J.

doi:10.1016/s0012-821x(99)00261-7

Cited by 134 publications

(77 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This correlation is now shown to be incorrect based on the 2,426 ± 3 Ma age constraint provided by the Ongeluk Formation volcanic rocks and associated intrusions. In addition, lithologic and chemostratigraphic data for the Duitschland and Rooihoogte formations (15,18,23,24,31) coupled with recent age constraints (9,11,25) and arguments relying on basin architecture (16) indicate that the Duitschland and Rooihoogte formations are younger than the Postmasburg Group (Fig. 1).…”

Section: Discussionmentioning

confidence: 99%

“…1). Pb-Pb and U-Pb dating of the Mooidraai Formation carbonates has yielded dates of 2,394 ± 26 and 2,392 ± 23 Ma (15,20), respectively, in conflict with the 2,222 ± 13 Ma Pb-Pb date on the stratigraphically…”

Section: Transvaal Supergroupmentioning

confidence: 99%

“…Paleomagnetic data for the Ongeluk Formation, which conformably overlies and interfingers with the Makganyene Formation, indicate that these glacial sedimentary rocks were deposited at low latitude, implying a glacial event of global extent (6,7). The age of the Ongeluk Formation basalts has long been accepted at 2,222 ± 13 Ma based on a whole-rock Pb-Pb isochron date (14) and correlation with the noncontiguous basalts of the ≤2,250-2,240 Ma Hekpoort Formation in the Transvaal subbasin (11,12,14,18), although this correlation has been questioned recently (15,16,19). The Ongeluk Formation is overlain by banded iron and manganese deposits of the Hotazel Formation, which in turn, are followed by carbonate rocks of the Mooidraai Formation (Fig.…”

Section: Transvaal Supergroupmentioning

confidence: 99%

“…2,310 Ma (9) but requires a fourth glaciation at ≤2,250-2,240 Ma (9,11) before the development of the oldest widely accepted oxygenated paleosols (12) and red-bed sandstones (13). Discrepancies in correlations between these glacially influenced stratigraphic successions and the age of the GOE hinge on a disputed age for the Ongeluk Formation basalts (14)(15)(16). By using high-resolution in situ secondary ion mass spectrometry (SIMS) on microbaddeleyite grains coupled with precise isotope dilution thermal ionization mass spectrometry (ID-TIMS) and paleomagnetic studies, we resolve these uncertainties by obtaining accurate and precise ages for the volcanic Ongeluk Formation and related intrusions in South Africa.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Timing and tempo of the Great Oxidation Event

Gumsley

Chamberlain

Bleeker

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

410

274

View full text Add to dashboard Cite

The first significant buildup in atmospheric oxygen, the Great Oxidation Event (GOE), began in the early Paleoproterozoic in association with global glaciations and continued until the end of the Lomagundi carbon isotope excursion ca. 2,060 Ma. The exact timing of and relationships among these events are debated because of poor age constraints and contradictory stratigraphic correlations. Here, we show that the first Paleoproterozoic global glaciation and the onset of the GOE occurred between ca. 2,460 and 2,426 Ma, ∼100 My earlier than previously estimated, based on an age of 2,426 ± 3 Ma for Ongeluk Formation magmatism from the Kaapvaal Craton of southern Africa. This age helps define a key paleomagnetic pole that positions the Kaapvaal Craton at equatorial latitudes of 11°± 6°at this time. Furthermore, the rise of atmospheric oxygen was not monotonic, but was instead characterized by oscillations, which together with climatic instabilities may have continued over the next ∼200 My until ≤2,250-2,240 Ma. Ongeluk Formation volcanism at ca. 2,426 Ma was part of a large igneous province (LIP) and represents a waning stage in the emplacement of several temporally discrete LIPs across a large low-latitude continental landmass. These LIPs played critical, albeit complex, roles in the rise of oxygen and in both initiating and terminating global glaciations. This series of events invites comparison with the Neoproterozoic oxygen increase and Sturtian Snowball Earth glaciation, which accompanied emplacement of LIPs across supercontinent Rodinia, also positioned at low latitude.Great Oxidation Event | Snowball Earth | Paleoproterozoic |

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Transvaal Supergroupmentioning

confidence: 99%

Section: Transvaal Supergroupmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Timing and tempo of the Great Oxidation Event

Gumsley

Chamberlain

Bleeker

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

410

274

View full text Add to dashboard Cite

show abstract

“…Some of these O 2 indicators are discussed further below. Very strong evidence for an increase in atmospheric O 2 at this time comes from the first large-scale appearance of oxidized (and thus insoluble) manganese in the Kalahari Mn Field of South Africa (Bau et al 1999;Kirschvink et al 2000). The most precise data, however, come from an 'unconventional' source, namely, mass-independent fractionation (MIF) of sulphur isotopes.…”

Section: Sulphur Isotopes and Their Implications For Atmospheric Omentioning

confidence: 98%

Palaeoclimates: the first two billion years

Kasting

Ono

2006

Phil. Trans. R. Soc. B

124

View full text Add to dashboard Cite

Earth's climate during the Archaean remains highly uncertain, as the relevant geologic evidence is sparse and occasionally contradictory. Oxygen isotopes in cherts suggest that between 3.5 and 3.2 Gyr ago (Ga) the Archaean climate was hot (55-85 8C); however, the fact that these cherts have experienced only a modest amount of weathering suggests that the climate was temperate, as today. The presence of diamictites in the Pongola Supergroup and the Witwatersrand Basin of South Africa suggests that by 2.9 Ga the climate was glacial. The Late Archaean was relatively warm; then glaciation (possibly of global extent) reappeared in the Early Palaeoproterozoic, around 2.3-2.4 Ga.Fitting these climatic constraints with a model requires high concentrations of atmospheric CO 2 or CH 4 , or both. Solar luminosity was 20-25% lower than today, so elevated greenhouse gas concentrations were needed just to keep the mean surface temperature above freezing. A rise in O 2 at approximately 2.4 Ga, and a concomitant decrease in CH 4 , provides a natural explanation for the Palaeoproterozoic glaciations. The Mid-Archaean glaciations may have been caused by a drawdown in H 2 and CH 4 caused by the origin of bacterial sulphate reduction. More work is needed to test this latter hypothesis.

show abstract

Trace element and Sr isotope records of multi‐episode carbonatite metasomatism on the eastern margin of the North China Craton

Deng

Liu

Zong

et al. 2017

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Lherzolite xenoliths entrained in the Changle Cenozoic basalts were analyzed to infer mantle process beneath the eastern block of the North China Craton. These xenoliths were classified into two types. Clinopyroxenes (Cpx) in the type-1 xenoliths are strongly enriched in large ion lithophile elements and light rare earth elements (LREE) but depleted in high field-strength elements and heavy rare earth elements, and show high Ca/Al, Zr/Hf, and (La/Yb) N ratios but low Ti/Eu ratios. These features indicate that they were crystallized from a carbonatitic melt. Cpx in the type-2 xenoliths are mostly characterized by a chemical zonation, that is, LREE and Sr contents and (La/Yb) N and Eu/Ti ratios gradually increase from the cores to the rims. Some fresh cores preserve the original signatures of the depleted mantle. These observations indicate partial modification of pre-existing Cpx by carbonatite metasomatism. Two episodes of metasomatism were identified based on Sr isotopic compositions of Cpx and carbonate inclusions within olivines. Both the carbonate inclusions and Cpx cores in the type-2 xenoliths have relatively high 87 Sr/ 86 Sr ratios (>0.7033), suggesting metasomatism due to CO 2 -rich silicate melt derived from the recycled oceanic crust. However, low 87 Sr/ 86 Sr ratios of Cpx rims in the type-2 xenoliths suggest a late stage of metasomatism by a low-87 Sr/ 86 Sr carbonatitic melt (<0.7024), which might have been caused by upwelling of the asthenosphere mantle. Such multiple metasomatism could have played an important role in changing the chemical composition of mantle from refractory and depleted to fertile and enriched.

show abstract

Pb, O, and C isotopes in silicified Mooidraai dolomite (Transvaal Supergroup, South Africa): implications for the composition of Paleoproterozoic seawater and ‘dating’ the increase of oxygen in the Precambrian atmosphere

Cited by 134 publications

References 36 publications

Timing and tempo of the Great Oxidation Event

Timing and tempo of the Great Oxidation Event

Palaeoclimates: the first two billion years

Trace element and Sr isotope records of multi‐episode carbonatite metasomatism on the eastern margin of the North China Craton

Contact Info

Product

Resources

About