Subaerial exposure surfaces in a Palaeoproterozoic 13C-rich dolostone sequence from the Pechenga Greenstone Belt: palaeoenvironmental and isotopic implications for the 2330–2060Ma global isotope excursion of 13C/12C

Melezhik, Victor A.; Fallick, Anthony E.; Grillo, Silvana Maria

doi:10.1016/j.precamres.2004.03.011

Cited by 18 publications

(15 citation statements)

References 69 publications

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“…This, in turn, increased the acidity and aggressiveness of metal‐bearing solutions with respect to surrounding carbonate rocks and thus intensified the development of karst features. Caves referred to as ‘hydrothermal’ develop when hot fluids rise through pores or along fissures, faults, brecciated zones with or without mixing with shallow meteoric waters (Melezhik et al ., ; Spötl et al ., ).…”

Section: Extensional Fracturing and Hydrothermal Dike Emplacementmentioning

confidence: 97%

Late Ediacaran syn‐rift/post‐rift transition and related fault‐driven hydrothermal systems in the Anti‐Atlas Mountains, Morocco

Álvaro

2012

Basin Research

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The syn-rift/post-rift transition of the late Ediacaran-mid Cambrian Atlas rift is characterized by the interplay of several processes, such as a widespread episode of fracturing and tilting, associated with encasement of fault-controlled vein metallic ore deposits of economic importance, and carbonate production and phosphogenesis (Taguedit Bed, Tabia Member) bordering rift-flank uplifts. A correlatable unconformity marks the end of these processes and the beginning of a thermal subsidence-dominated regime with development of a more stable, carbonate, peritidal-dominated platform (Tifnout Member). Late Ediacaran microbial carbonate production and phosphogenesis extended in discontinuous belts around the periphery of uplifted rift shoulders and flanks. Karst development is interpreted to have formed along synsedimentary faults and fractures during abrupt tectonic uplift associated with emplacement of polymetallic hydrothermal dikes (rich in Cu, Fe and subsidiary Pb, Zn). Isotopic analysis indicates that speleothem precipitation in karstic palaeocaves displays significantly lighter d 13 C and d 18 O values as compared to the host dolomite, implying calcite precipitation by terrestrial fluids rich in decomposing organic matter and/or microbial activity in the cave system.

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Section: Extensional Fracturing and Hydrothermal Dike Emplacementmentioning

confidence: 97%

Late Ediacaran syn‐rift/post‐rift transition and related fault‐driven hydrothermal systems in the Anti‐Atlas Mountains, Morocco

Álvaro

2012

Basin Research

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“…Carbonates associated with dissolution surfaces and small-scale cavities (epikarst) have also been found in the KSF (Melezhik et al, 2004), along with calcrete (caliche) and dolocrete (e.g. Melezhik et al 2004;Melezhik and Fallick, 2003). These calcrete and dolocrete instances were interpreted to have formed by capillary rise and evaporation (Melezhik et al, 2004;Melezhik and Fallick, 2003).…”

Section: Introductionmentioning

confidence: 93%

“…Melezhik et al 2004;Melezhik and Fallick, 2003). These calcrete and dolocrete instances were interpreted to have formed by capillary rise and evaporation (Melezhik et al, 2004;Melezhik and Fallick, 2003). Moreover, reported probable CaSO 4 pseudomorphs in the KSF sabkha-or playa-carbonates.…”

Section: Introductionmentioning

confidence: 96%

“…In addition to stratified dolostone and limestone, hot-spring associated travertines have previously been interpreted from the KSF (Melezhik and Fallick, 2001). Carbonates associated with dissolution surfaces and small-scale cavities (epikarst) have also been found in the KSF (Melezhik et al, 2004), along with calcrete (caliche) and dolocrete (e.g. Melezhik et al 2004;Melezhik and Fallick, 2003).…”

Section: Introductionmentioning

confidence: 97%

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Travertine precipitation in the Paleoproterozoic Kuetsjärvi Sedimentary Formation, Pechenga Greenstone Belt, NE Fennoscandian Shield

Salminen

Brasier

Karhu

et al. 2014

Precambrian Research

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Precambrian travertines, tufas and speleothems either formed rarely or they have not been identified in previous studies. In the absence of high pCO 2 soils in Paleoproterozoic, karst solution and speleothem formation occurred by processes distinct from those commonly found in present-day low temperature karst environments. However, the high pCO 2 atmosphere could itself have encouraged karst formation. The Paleoproterozoic Kuetsjärvi Sedimentary Formation of the Pechenga Greenstone Belt, NW Russia, includes abundant terrestrial carbonate precipitates. These precipitates were sampled from a drillcore representing a complete section of the ca. 120-mthick formation and were investigated for C and O isotopes, acid-soluble elemental contents and petrography. The newly obtained results were used to constrain the origins of the precipitates and to illuminate different terrestrial carbonate types. The investigated drillcore includes abundant small-scale cavities and veins, which are commonly filled with dolomite and quartz. Dolomite crusts are found both in the cavities and on 1 bedding/erosional surfaces. Dolomite cements coat uneven surfaces and surficial rock fragments. The surficial dolomite crusts form distinct and discrete layers, whereas the cements do not. The cavity and vein fills are likely post-depositional in origin, whereasthe surficial dolomite crusts and dolomite cements are likely syndepositional precipitates. The investigated precipitates often show δ 13 C values lower than those reported from their host rocks, suggesting the influence of an external carbon source. Petrographic features and geochemical data suggest dissolution and precipitation of carbonate material originating from deep-sourced CO 2-bearing fluids, likely at high earth surface temperatures.

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“…Yuan et al (2005) recently reported associations between fungal hyphae and algae or cyanobacteria in the Doushantuo formation; however, these are thought to be of marine origin. The oldest indisputable terrestrial eukaryotic microfossils are 1.2 billion years old (Horodyski & Knauth, 1994), although there is geochemical evidence for microbial activity in older soils (Watanabe et al, 2000;Prave, 2002;Watanabe et al, 2004), but see also Melezhik et al (2004). Fungi have been shown to enhance weathering of silicate rocks and leaching of nutrients (Gislason et al, 1996;Brady et al, 1999;Etienne & Dupont, 2002).…”

Section: Connecting Geology and Genomesmentioning

confidence: 99%

The Precambrian emergence of animal life: a geobiological perspective

et al. 2007

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The earliest record of animals (Metazoa) consists of trace and body fossils restricted to the last 35 Myr of the Precambrian. It has been proposed that animals arose much earlier and underwent significant evolution as a cryptic fauna; however, the need for any unrecorded prelude of significant duration has been disputed. In this context, we consider recent published research on the nature and chronology of the earliest fossil record of metazoans and on the molecular‐based analysis that yielded older dates for the appearance of major animal groups. We review recent work on the climatic, geochemical, and ecological events that preceded animal fossils and consider their portent for metazoan evolution. We also discuss inferences about the physiology and gene content of the last common ancestor of animals and their closest unicellular relatives. We propose that the recorded Precambrian evolution of animals includes three intervals of advancement that begin with sponge‐grade organisms, and that any preceding cryptic fauna would be no more complex than sponges. The molecular data do not require that more complex animals appeared well before the recognized fossil record; nor, however, do they rule the possibility out, particularly if the interval of simpler metazoan ancestors lasted no more than about 100 or 200 Myr. The geological record of abrupt changes in climate, biogeochemistry, and phytoplankton diversity can be taken to be the result of changes in the carbon cycle triggered by the appearance and diversification of metazoans in an organic carbon‐rich ocean, but as yet no compelling evidence exists for this interpretation. By the end of this cryptic period, animals would already have possessed sophisticated systems of cell–cell signalling, adhesion, apoptosis, and segregated germ cells, possibly with a rudimentary body plan based on anterior–posterior organization. The controls on the timing and tempo of the earliest steps in metazoan evolution are unknown, but it seems likely that oxygen was a key factor in later diversification and increase in body size. We consider several recent scenarios describing how oxygen increased near the end of the Precambrian and propose that grazing and filter‐feeding animals depleted a marine reservoir of suspended organic matter, releasing a microbial ‘clamp’ on atmospheric oxygen.

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Subaerial exposure surfaces in a Palaeoproterozoic 13C-rich dolostone sequence from the Pechenga Greenstone Belt: palaeoenvironmental and isotopic implications for the 2330–2060Ma global isotope excursion of 13C/12C

Cited by 18 publications

References 69 publications

Late Ediacaran syn‐rift/post‐rift transition and related fault‐driven hydrothermal systems in the Anti‐Atlas Mountains, Morocco

Late Ediacaran syn‐rift/post‐rift transition and related fault‐driven hydrothermal systems in the Anti‐Atlas Mountains, Morocco

Travertine precipitation in the Paleoproterozoic Kuetsjärvi Sedimentary Formation, Pechenga Greenstone Belt, NE Fennoscandian Shield

The Precambrian emergence of animal life: a geobiological perspective

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