Early Neoproterozoic (Tonian) Patch Reef Complexes, Victoria Island, Arctic Canada

Narbonne, Guy M.; James, Noël P.; Rainbird, Rob; Morin, Jens

doi:10.2110/pec.00.67.0163

Cited by 9 publications

(13 citation statements)

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“…Biogenic cell‐like structures (<30 μm) in laminated facies have been reported by Kellerhals & Matter (2003). Although stromatolite growth in the Neoproterozoic was not restricted to any specific palaeoenvironment, m‐scale stromatolite mounds are commonly associated with tidal or shallow marine deposits (Grotzinger, 1989; Clough & Goldhammer, 2000; Narbonne et al , 2000). Elongation of stromatolites is supportive of a shallow marine interpretation, as it requires sustained current activity parallel to the elongated axis of the mound (e.g.…”

Section: Cap Carbonatementioning

confidence: 95%

A Neoproterozoic glacially influenced basin margin succession and ‘atypical’ cap carbonate associated with bedrock palaeovalleys, Mirbat area, southern Oman

et al. 2006

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The Ayn Formation of the Neoproterozoic Mirbat Group comprises <400 m of little‐deformed, glacially influenced basin margin deposits. These deposits are preserved in several palaeovalleys eroded in crystalline basement and overlain by a discontinuous cap carbonate. The Ayn Formation and the cap carbonate, which are superbly exposed along a 20 km SW–NE‐striking escarpment in south Oman, provide important insights into the processes operating on a basin margin during a Neoproterozoic glaciation and its demise. The Ayn Formation comprises units of glacimarine rain‐out diamictite and sediment gravity flow deposits, alternated with units of fluvial and deltaic sandstones and conglomerates, which may have formed by proglacial outwash. The stratigraphic evolution of the Ayn Formation indicates a highly active hydrological cycle during a phase of overall (glacio‐eustatic?) low stand when glaciers advanced into and receded upon bedrock valleys. The transgressive cap carbonate was deposited primarily in shallow marine or shallow lacustrine environments over palaeohighs during the deglaciation, and was partly reworked into deeper parts of the basin through sediment gravity flow processes. Locally, the cap carbonate transgresses over crystalline basement containing a network of fissures filled with carbonate originating from the cap. The δ13C isotopic composition of the cap carbonate varies systematically between −3.5 and +5.8‰ Pee Dee Belemnite standard, in common with other older Cryogenian examples.

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Section: Cap Carbonatementioning

confidence: 95%

A Neoproterozoic glacially influenced basin margin succession and ‘atypical’ cap carbonate associated with bedrock palaeovalleys, Mirbat area, southern Oman

et al. 2006

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“…Synoptic relief of individual layers is commonly a few millimetres up to approximately 1 cm, but stromatolite columns grew up to tens of centimeters high. Stromatolites most closely resemble the form genus Tungussia, Acaciella, Baicalia, Jurusania and Tilemsina (Walter 1972;Narbonne, et al 2000;Kah, et al 2009 Formation (Narbonne et al, 2000) and from the correlative Little Dal Group in the northern Cordillera (Batten, et al 2004).…”

Section: Columnar Stromatolite Facies (F13)mentioning

confidence: 86%

“…In the lower Shaler Supergroup of the Minto Inlier, the Boot Inlet Formation (Fig. 1) is a ~500 m thick carbonate unit, which is also interpreted to have accumulated on a stormdominated carbonate ramp (Young and Jefferson, 1975;Young and Long, 1977;Morin and Rainbird, 1993;Rainbird et al, 1994;Narbonne et al, 2000). There are, however, two prominent differences between the formations.…”

Section: Comparison Of Sedimentary Patternsmentioning

confidence: 99%

“…Long et al (2008), further subdivided sequence B into five subsequences that correlate across northern Canada. Sequence stratigraphic analysis and sedimentological descriptions of the reefs in the Boot Inlet Formation was preformed by Narbonne and James (2000). Rainbird (1993) interpreted four T-R cycles for the Kilian and Kuujjua formations.…”

Section: Previous Workmentioning

confidence: 99%

“…There are, however, two prominent differences between the formations. First, unlike stromatolitic buildups within the Wynniatt Formation, which typically formed tabular (biostromal) bodies that can be correlated across Minto Inlier, the Boot Inlet Formation preserves a variety of more isolated (biohermal) reef morphotypes, which include: patch reefs, table reefs, and large concentric-sheet bioherms that are up to 60 m in diameter (Narbonne et al, 2000).…”

Section: Comparison Of Sedimentary Patternsmentioning

confidence: 99%

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Neoproterozoic Carbonate Ramp Development in the Canadian Arctic (Shaler Supergroup): Sedimentology, Sequence Stratigraphy, and Chemostratigraphy

Thomson¹

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This study describes Tonian-Cryogenian pre-rift strata of the upper Shaler Supergroup, deposited in the Amundsen Basin (Victoria Island, Canada). The Wynniatt Formation, part of the upper Shaler Supergroup, consists of three carbonate ramp successions separated by regional unconformities. Each cycle represents part of a distally steepened, storm-dominated carbonate ramp. Temporal changes in carbonate facies record depositional environments spanning from supratidal to outer ramp settings. Interpretation of an intertidal mudflat depositional environment for the Tawuia-Chuaria assemblage zone provides depositional context for interbasinal biostratigraphic correlation. Correlation between the Amundsen and Fifteenmile (Yukon) basins is complicated by differing rates and regimes of subsidence, with the exception of a regional basin-deepening event. Contrary to previous correlations, it is proposed that the upper Shaler Supergroup and Little Dal Group of the Mackenzie Mountains Supergroup (Mackenzie Basin) are equivalent to the entire Fifteenmile Group. Five transgressive-regressive (T-R) cycles were identified in the Jago Bay, Minto Inlet, and Wynniatt formations. Three tectonostratigraphic units for the upper Shaler Supergroup record an initial sag basin, followed by early extension and thermal doming, and finally rifting of the Amundsen Basin. Neoproterozoic successions of northwest Laurentia are an example where rift and intracontinental basins are spatially and temporally related. Subsidence possibly was related to multiple cycles of intra-plate extension that complemented coeval fault-controlled subsidence. An improved δ 13 C carb curve paired with δ 13 C org values provides support for correlation of a significant negative δ 13 C excursion that has been linked to the Bitter Springs stage. In the Amundsen Basin, δ 13 C carb values drop to markedly negative values (>-14 ‰), which is attributed to local overprints whereby isotopically light carbon in pore waters was precipitated as authigenic carbonate cement fuelled by oxidation of methane or organic matter during sulphate and iron reduction. Redox proxies indicate local basin euxinia and anoxia. Pronounced Mo, V, and U enrichments in euxinic black shales suggest that the Bitter Springs stage was a transitional time, where the global oceans became more oxygenated relative to preceding portions of the mid-Proterozoic, but remained more reducing compared to the Phanerozoic. PREFACE Method of Presentation This thesis is presented as five chapters: an introduction, conclusion, and three stand-alone manuscripts addressing specific geological problems. While there may be some overlap given the focused nature of this project, redundancies are generally restricted to the introductory portions of the chapters. The order of the manuscripts follows the order of publication given that later manuscripts build upon the framework provided by earlier manuscripts. At the time of this submission, chapter two is published in Sedimentary Geology (

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Exceptional preservation in Quaternary Atacama Desert Tufas: Evidence for increased groundwater and surface water in the Calama Basin, Atacama, Chile

Wet

Driscoll

Wet

et al. 2023

The Depositional Record

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Exceptionally well‐preserved tufas located west of Calama, Atacama Desert, Chile, designated Santa Juana tufas, record episodic wetter conditions, relative to today, over the past 500,000 years. Globally, tufa architecture and depositional details are poorly understood as most described tufas have been degraded by weathering and erosion. In the hyperarid Atacama, post‐depositional alteration is negligible, therefore, the exceptional preservation of Santa Juana tufas documented in this study provides new information about tufa facies and their complex interactions. Santa Juana facies include microbial stromatolites, phytoherms, cascadestone, flowstone and porous limestone. Phytoherms, consisting of former plant stems coated with calcite, developed in channels, within pools, and along spring discharge aprons. Cascadestone, representing former waterfalls, preserves microbial filaments and delicate V‐shaped calcite crystals. Flowstone lines shallow subvertical to subhorizontal channels, representing sites of rapidly sluicing water flow. Porous limestone, containing sparse calcite and/or gypsum and anhydrite cement crystals, represents detrital accumulations. Stable isotope results, coupled with U/Th ages, show that by the Quaternary, relative to the Neogene, groundwater was less supercharged with volcanogenic CO2 so degassing was moderated. The δ18O ratios from Miocene–Pliocene palustrine and lacustrine freshwater carbonates that underlie Santa Juana tufas indicate significant evaporation, but the tufa δ18O signal indicates a less evaporative trend due to shorter atmosphere exposure time. Biological fractionation in δ13C is largely masked by the region's volcanogenic carbon footprint, although tufa petrography shows well‐preserved microbial filaments and laminations. The range of tufa ages in this study shows that there were wetter time periods within the drainage basin headwater area in the Quaternary, but that by the late Pleistocene to early Holocene, aridity to hyperaridity became established. The lack of diagenesis or alteration within the Santa Juana tufas indicates that there has been minimal rainfall since their deposition.

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Early Neoproterozoic (Tonian) Patch Reef Complexes, Victoria Island, Arctic Canada

Cited by 9 publications

References 0 publications

A Neoproterozoic glacially influenced basin margin succession and ‘atypical’ cap carbonate associated with bedrock palaeovalleys, Mirbat area, southern Oman

A Neoproterozoic glacially influenced basin margin succession and ‘atypical’ cap carbonate associated with bedrock palaeovalleys, Mirbat area, southern Oman

Neoproterozoic Carbonate Ramp Development in the Canadian Arctic (Shaler Supergroup): Sedimentology, Sequence Stratigraphy, and Chemostratigraphy

Exceptional preservation in Quaternary Atacama Desert Tufas: Evidence for increased groundwater and surface water in the Calama Basin, Atacama, Chile

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