Detrital zircon U-Pb and Lu-Hf data for a kinzigitic gneiss (Jequitinhonha Complex, Araçuaí Orogen, SE Brazil) constrain the age of a huge storage of Ediacaran carbon

Pacheco, Fernando Estevão Rodrigues Crincoli; Caxito, Fabrício de Andrade; Pedrosa-Soares, Antônio Carlos; Dussin, Ivo; Gonçalves-Dias, Tatiana

doi:10.1016/j.jsames.2020.102709

Cited by 10 publications

(2 citation statements)

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“…Alternative factors might have contributed to the MIBE, such as a change in total carbon input from the weathering of older carbonate rocks with high δ 13 C carb 23 , 41 and a third authigenic carbonate sink 32 , but are unlikely to have acted alone in maintaining a 13 C-enriched DIC throughout the basin 32 . A giant Ediacaran graphite deposit interleaved in paragneisses of the Araçuaí Orogen 50 was proposed to potentially represent at least part of the organic carbon buried to generate the MIBE 32 , but there is a seeming mismatch in the constrained ages of the two events, as the graphite deposit was metamorphosed to high-grade at ca. 585–560 Ma 50 and the MIBE would only have started after the beginning of the Cloudina sp.…”

Section: Discussionmentioning

confidence: 99%

“…A giant Ediacaran graphite deposit interleaved in paragneisses of the Araçuaí Orogen 50 was proposed to potentially represent at least part of the organic carbon buried to generate the MIBE 32 , but there is a seeming mismatch in the constrained ages of the two events, as the graphite deposit was metamorphosed to high-grade at ca. 585–560 Ma 50 and the MIBE would only have started after the beginning of the Cloudina sp. biozone, i.e.…”

Section: Discussionmentioning

confidence: 99%

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Goldilocks at the dawn of complex life: mountains might have damaged Ediacaran–Cambrian ecosystems and prompted an early Cambrian greenhouse world

Caxito

Lana

Uhlein

et al. 2021

Sci Rep

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We combine U–Pb in-situ carbonate dating, elemental and isotope constraints to calibrate the synergy of integrated mountain-basin evolution in western Gondwana. We show that deposition of the Bambuí Group coincides with closure of the Goiás-Pharusian (630–600 Ma) and Adamastor (585–530 Ma) oceans. Metazoans thrived for a brief moment of balanced redox and nutrient conditions. This was followed, however, by closure of the Clymene ocean (540–500 Ma), eventually landlocking the basin. This hindered seawater renewal and led to uncontrolled nutrient input, shallowing of the redoxcline and anoxic incursions, fueling positive productivity feedbacks and preventing the development of typical Ediacaran–Cambrian ecosystems. Thus, mountains provide the conditions, such as oxygen and nutrients, but may also preclude life development if basins become too restricted, characterizing a Goldilocks or optimal level effect. During the late Neoproterozoic-Cambrian fan-like transition from Rodinia to Gondwana, the newborn marginal basins of Laurentia, Baltica and Siberia remained open to the global sea, while intracontinental basins of Gondwana became progressively landlocked. The extent to which basin restriction might have affected the global carbon cycle and climate, e.g. through the input of gases such as methane that could eventually have collaborated to an early Cambrian greenhouse world, needs to be further considered.

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