The Narakay Volcanic Complex: Mafic Volcanism in the Helikian Hornby Bay Group of Dease Arm, Great Bear Lake: a Preliminary Report On Depositional Processes and Tectonic Significance

Ross, G M

doi:10.4095/111296

Cited by 8 publications

(4 citation statements)

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“…The age of the Dismal Lakes Group is reasonably well constrained. U‐Pb zircon ages of 1663 ± 8 Ma (Bowring & Ross, ) for rocks of the Narakay Volcanic Complex, extruded during deposition of the Hornby Bay Group (Ross, ), and U‐Pb baddeleyite ages of 1590 ± 3 on the Western Channel Diabase (Hamilton & Buchan, ) that cuts the uppermost East River and Kaertok formations of the Hornby Bay Group (Ross & Kerans, ), provide a maximum age for deposition of the Dismal Lakes Group. The minimum age is constrained by the emplacement of the ca.…”

Section: Geologic Settingmentioning

confidence: 99%

“…The Leith Line (Fig. ) is a north–south trending structural hinge that corresponds to the western edge of the Great Bear Magmatic Zone and may represent reactivation of a deep‐seated basement suture originating during the earlier Wopmay Orogen (Hoffman, ; Hoffman & St‐Onge, ; Ross, ). Ultimately, deposition of Hornby Bay carbonate platform facies was terminated by uplift east of the Leith Line, in the Teshierpi fault zone, resulting in erosion of exposed East River Formation and fluvial deposition (Kaertok Formation) west of the Teshierpi uplift (Ross, ; Hahn et al ., ).…”

Section: Geologic Settingmentioning

confidence: 99%

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Deep‐water microbialites of the Mesoproterozoic Dismal Lakes Group: microbial growth, lithification, and implications for coniform stromatolites

et al. 2014

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Offshore facies of the Mesoproterozoic Sulky Formation, Dismal Lakes Group, arctic Canada, preserve microbialites with unusual morphology. These microbialites grew in water depths greater than several tens of meters and correlate with high-relief conical stromatolites of the more proximal September Lake reef complex. The gross morphology of these microbial facies consists of ridge-like vertical supports draped by concave-upward, subhorizontal elements, resulting in tent-shaped cuspate microbialites with substantial primary void space. Morphological and petrographic analyses suggest a model wherein penecontemporaneous upward growth of ridge elements and development of subhorizontal draping elements initially resulted in a buoyantly supported, unlithified microbial form. Lithification began via precipitation within organic elements during microbialite growth. Mineralization either stabilized or facilitated collapse of initially neutrally buoyant microbialite forms. Microbial structures and breccias were then further stabilized by precipitation of marine herringbone cement. During late-stage diagenesis, remaining void space was occluded by ferroan dolomite cement. Cuspate microbialites are most similar to those found in offshore facies of Neoarchean carbonate platforms and to unlithified, buoyantly supported microbial mats in modern ice-covered Antarctic lakes. We suggest that such unusual microbialite morphologies are a product of the interaction between motile and non-motile communities under nutrient-limiting conditions, followed by early lithification, which served to preserve the resultant microbial form. The presence of marine herringbone cement, commonly associated with high dissolved inorganic carbon (DIC), low O2 conditions, also suggests growth in association with reducing environments at or near the seafloor or in conjunction with a geochemical interface. Predominance of coniform stromatolite forms in the Proterozoic--across a variety of depositional environments--may thus reflect a combination of heterogeneous nutrient distribution, potentially driven by variable redox conditions, and an elevated carbonate saturation state, which permits preservation of these unusual microbialite forms.

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Section: Geologic Settingmentioning

confidence: 99%

Section: Geologic Settingmentioning

confidence: 99%

Deep‐water microbialites of the Mesoproterozoic Dismal Lakes Group: microbial growth, lithification, and implications for coniform stromatolites

et al. 2014

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“…The Narakay volcanic complex, the offshore equivalent of the upper Hornby Bay Group (Ross 1982), contains 1662 ± 8 Ma feldspar-phyric dykes and volcanic breccias (U-Pb zircon ; Bowring and Ross 1985), and it constrains the maximum age of the Dismal Lakes Group. However, the identification of subsurface strata west of the exposed outcrop belt (Aitken and Pugh 1984;Cook and Taylor 1991) suggests that the Hornby Bay -Dismal Lakes contact is regionally unconformable.…”

Section: Regional Geologic Setting and Agementioning

confidence: 99%

Reconstructing sea-level change from the internal architecture of stromatolite reefs: an example from the Mesoproterozoic Sulky Formation, Dismal Lakes Group, arctic Canada

Kah¹,

Bartley²,

Frank³

et al. 2006

Can. J. Earth Sci.

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The Mesoproterozoic Dismal Lakes Group, arctic Canada, contains a relatively thin, yet regionally extensive stromatolitic reef complex that developed subtidally during a major transgression, shoaled to sea level, and was overlain by intertidal to supratidal carbonate and evaporite strata. The September Lake reef complex exhibits a complex internal architecture that records the interaction between stromatolite growth and changes in accommodation space derived from both higher order (4th- or 5th-order, parasequence-scale) changes in sea level and the variable bathymetry of the sea floor. Reef growth, which was initiated during three sea-level cycles, records progressive marine transgression over depositional lows that were formed during pre-reef subaerial exposure and erosion of the underlying strata. A fourth sea-level cycle, represented by spectacular coniform stromatolites with >10 m of synoptic relief, marks a more dramatic rise in sea level and establishment of the main reef complex. Aggradation and eventual shoaling of the reef complex occurred over an additional six sea-level cycles. Only basinward regions of the September Lake reef complex preserve vertical stacking of reefal packages in response to sea-level fluctuations. In contrast, in the main reef core, sea-level fluctuations resulted in subaerial exposure of the reef top, variable karst development, and the progressive infilling of reef topography by progradational reef elements. Assessment of stromatolite growth patterns reveals the complex nature of the reef architecture and permits the determination of higher order changes in relative sea level that were responsible for reef development.

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“…The age of the Dismal Lakes Group is constrained by geochronological data derived from: (1) the underlying Narakay Volcanic Complex and (2) the Coppermine River Group, including flood basalts that cap the upper Greenhorn sequence. The Narakay Volcanic Complex, composed of marine strata and interbedded/crosscutting bimodal volcanic rocks, represents the offshore equivalent of the upper Hornby Bay Group (Ross, 1982). Zircons from feldspar-phyric dykes and volcanic breccias associated with the final stage of felsic volcanism in the Narakay complex yield an age of 1662 ± 8 Ma (Bowring & Ross, 1985).…”

Section: C Age Of the Dismal Lakes Groupmentioning

confidence: 99%

Changes in organic matter production and accumulation as a mechanism for isotopic evolution in the Mesoproterozoic ocean

2003

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Mesoproterozoic marine successions worldwide record a shift in average δ13C values from 0 to +3.5‰, with the latter value evident in successions younger than 1250 Ma. New carbon isotope data from the ∼1300 to 1270 Ma Dismal Lakes Group, Arctic Canada, provide further insight into this fundamental transition. Data reveal that the shift to higher δ13C values was gradual and marked by occasional excursions to values less than 0‰. When compared to records from older and younger marine successions, it is evident that the difference between isotopic minima and maxima increased with time, indicating that the marine system evolved to become isotopically more variable. We interpret these patterns to record an increase in the crustal inventory of organic carbon, reflecting eukaryotic diversification and a change in the locus of organic carbon burial to include anoxic deep marine sites where preservation potential was high. We speculate that the release of O2 to Earth's surface environments associated with increased organic carbon storage induced irreversible changes in the Mesoproterozoic biosphere, presaging the more extreme environmental and evolutionary developments of the Neoproterozoic.

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The Narakay Volcanic Complex: Mafic Volcanism in the Helikian Hornby Bay Group of Dease Arm, Great Bear Lake: a Preliminary Report On Depositional Processes and Tectonic Significance

Cited by 8 publications

References 0 publications

Deep‐water microbialites of the Mesoproterozoic Dismal Lakes Group: microbial growth, lithification, and implications for coniform stromatolites

Deep‐water microbialites of the Mesoproterozoic Dismal Lakes Group: microbial growth, lithification, and implications for coniform stromatolites

Reconstructing sea-level change from the internal architecture of stromatolite reefs: an example from the Mesoproterozoic Sulky Formation, Dismal Lakes Group, arctic Canada

Changes in organic matter production and accumulation as a mechanism for isotopic evolution in the Mesoproterozoic ocean

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