A Neoproterozoic fringing stromatolite reef complex, Flinders Ranges, South Australia

Lemon, Nicholas M.

doi:10.1016/s0301-9268(99)00071-6

Cited by 27 publications

(23 citation statements)

References 7 publications

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“…(Lemon 2000). Thickening of these formations towards the diapir in the central Flinders Ranges, which is particularly evident at the northern fold axis of the central anticline, shows that this interval was a time of active salt withdrawal and diapir growth (Lemon 2000;Fig. 1a).…”

Section: Stratigraphy Of the Adelaide Rift Complexmentioning

confidence: 97%

“…and much of the Enorama Fm. are thought to be responsible for entraining brecciated blocks of the underlying stratigraphy and bringing them to the surface (Lemon 1985;Lemon and Gostin 1990;Lemon 2000). In map view, many of the diapirs cross-cut the Etina Fm.…”

Section: Subglacial Erosionmentioning

confidence: 99%

“…and the lower two-thirds of the Enorama Fm. in the central region (Lemon 2000), whilst in the north they impinge on the lowermost ~50 metres of the Trezona Fm. Despite the small Oratunga diapir in the central region that cross-cuts the Umberatana Group stratigraphy, for the most part diapirs were emergent and most active before deposition of the Trezona Fm.…”

Section: Subglacial Erosionmentioning

confidence: 99%

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The End-Cryogenian Glaciation of South Australia

Rose

Maloof

Schoene

et al. 2013

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The Elatina Fm. records the younger Cryogenian ice age in the Adelaide Rift Complex (ARC) of South Australia, which has long-held the position as the type region for this low-latitude glaciation. Building upon a legacy of work, we document the pre- and syn-glacial sedimentary rocks to characterize the dynamics of the glaciation across the ARC. The Elatina Fm. records an array of well-preserved glacial facies at many different water depths across the basin, including ice contact tillites, fluvioglacial sandstones, dropstone intervals, tidal rhythmites with combined-flow ripples, and turbidites. The underlying Yaltipena Fm. records the pro-glacial influx of sediment from encroaching land-based ice sheets. The onset of the glaciation is heralded by the major element ratios (Chemical Index of Alteration) of the pre-glacial facies across the platform that show a reduction in chemical weathering and a deterioration in climate towards the base of the Elatina Fm. The advancing ice sheets caused soft-sediment deformation of the beds below the glacial diamictite, including sub-glacial push structures, as well as sub-glacial erosion of the carbonate unit beneath. Measured stratigraphic sections across the basin show glacial erosion up to 130 m into the carbonate platform. However, δ13C measurements of carbonate clasts within the glacial diamictite units were used to assess provenance and relative timing of δ13C acquisition, and suggest that at least 500 m of erosion occurred somewhere in the basin. Detrital zircon provenance data from the Elatina Fm. suggest that glacial sediment may have been partially sourced from the cratons of Western Australia and that the Whyalla Sandstone, even if stratigraphically correlative, was not a sediment source. The remainder of the Elatina Fm. stratigraphy mostly records the deglaciation and can be divided into three facies: a slumped sandstone, dropstone diamictite, and current-reworked diamictite. The relative sea level fall within the upper Elatina Fm. requires that regional deglaciation occurred on the timescale of ice sheet – ocean gravitational interactions (instant) and/or isostatic rebound (~104 years). Structures previously interpreted as soft-sediment folds within the rhythmite facies that were used to constrain the low-latitude position of South Australia at the time of the Elatina glaciation are re-interpreted as stoss-depositional transverse ripples with superimposed oscillatory wave ripples. These combined-flow ripples across the ARC attest to open seas with significant fetch during the initial retreat of local glaciers. In addition, this interpretation no longer requires that the magnetization be syn-depositional, although we have no reason to believe that the low-latitude direction is a result of remagnetization, and positive reversal tests and tectonic fold tests are at least consistent with syn-depositional magnetization. Together, these paired sedimentological and chemostratigraphic observations reveal the onset of the glaciation and advance of the ice sheet from land to create a heavily glaciated terrain that was incised down to at least the base of the pre-glacial Trezona Fm.SOMMAIRELa Formation d’Elatina représente la phase précoce de l’âge glaciaire du Cryogénien de l’Adelaide Rift Complex (ARC) dans le sud de l’Australie, région qui a longtemps été la région type de cette glaciation de basse latitude. À partir d’un legs de travaux, nous nous sommes appuyés sur l’étude des roches sédimentaires préglaciaires et synglaciaires pour caractériser la dynamique de la glaciation à travers l’ARC. La Formation d’Elatina renferme une gamme de faciès glaciaires bien préservés correspondant à différentes profondeurs d’eau à travers le bassin, dont des tillites de contact glaciaire, des grès fluvioglaciaires, des intervalles à galets de délestage, des rythmites tidales avec des combinaisons de rides d’écoulement, et des turbidites. La Formation sous-jacente de Yaltipena est constituée de sédiments proglaciaires provenant de lentilles de glace en progression. Le début de la glaciation est reflété dans les ratios des éléments majeurs (indice d’altération chimique) des faciès préglaciaires de la plateforme qui montre une réduction de l’altération chimique et une détérioration du climat à l’approche de la base de la Formation d’Elatina. La progression des nappes de glace a entraîné une déformation des lits de sédiments meubles sous la diamictite glaciaire, montrant entre autres des structures de poussée sous-glaciaires ainsi que de l’érosion sous-glaciaire de l’unité de carbonate sous-jacente. Les mesures de coupes stratigraphiques à travers le bassin montrent que l’érosion glaciaire a enlevé jusqu’à 130 m du carbonate de la plateforme. Toutefois, les signatures isotopiques δ13C de fragments de carbonate dans les unités de diamictites glaciaires utilisées pour établir la provenance et la chronologie d’acquisition relative de la signature δ13C des fragments, permet de penser qu’il y a eu au moins 500 m d'érosion quelque part dans le bassin. Les données de provenance sur zircons détritiques de la Formation d’Elatina permettent de penser que les sédiments glaciaires provenaient partiellement des cratons de l'Australie occidentale et que le grès de la Formation de Whyalla, bien que stratigraphiquement corrélé, n'a pas été une source de sédiments. Ce qui reste de la stratigraphie de la Formation d’Elatina représente principalement la déglaciation, laquelle peut être divisée en trois faciès : un grès plissé, une diamictite à galets de délestage, et une diamictite remaniée par des courants. La baisse du niveau relatif de la mer dans la partie supérieure de la Formation d’Elatina suppose une déglaciation régionale sur une échelle de temps de l’ordre de celle de la nappe de glace – interactions gravitationnelles de l’océan (instantanées) et/ou rebond isostatique (~ 104 ans). Des structures décrites précédemment comme des plis de sédiments mous dans des faciès de rhythmites qui impliquait une position de basse latitude pour l'Australie du Sud à l'époque de la glaciation Elatina, sont réinterprétées comme des rides sédimentaires transverses asymétriques avec des rides de vagues oscillatoires superposées. Ces combinaisons de rides d’écoulement à travers l’ARC confirment l’existence d’un milieu marin ouvert d’une ampleur certaine au moment de la retraite initiale des glaciers locaux. En outre, cette interprétation ne nécessite plus que la magnétisation soit synsédimentaire, bien que nous n'ayons aucune raison de penser que l’orientation magnétique de basse latitude soit le résultat d’une ré-aimantation, et que les tests de réversibilité positifs et les tests de plissement tectonique sont au minimum conformes à une magnétisation synsédimentaire. Ensemble, ces observations sédimentologiques et chimiostratigraphiques mettent en lumière le début de la glaciation et l'avancée du couvert de glace continental menant à une région fortement englacée qui a été incisée jusqu'à à la base de la Formation préglaciaire de Trezona.

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Section: Stratigraphy Of the Adelaide Rift Complexmentioning

confidence: 97%

Section: Subglacial Erosionmentioning

confidence: 99%

Section: Subglacial Erosionmentioning

confidence: 99%

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The End-Cryogenian Glaciation of South Australia

Rose

Maloof

Schoene

et al. 2013

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“…In contrast, decreasing accommodation space driven by tectonic uplift, depositional filling of available accommodation space, or sea-level fall, commonly results in progradation of the reef over basinal sediments and the eventual infilling and subaerial exposure of the reef top. Proterozoic stromatolitic and calcimicrobial reef architectures exhibit comparable relationships between large-scale changes in reef geometry and changes in relative sea level (Grotzinger 1989;Narbonne and James 1996;Turner et al 1997;Lemon 2000). In particular, several Mesoproterozoic (Narbonne and James 1996) and Neoproterozoic (Turner et al 1997;Lemon 2000) reefal deposits reveal vertical stacking of reef packages that record expansion, contraction, progradation, backstepping, and subaerial exposure of the reef system in response to major fluctuations in relative sea level.…”

Section: Introductionmentioning

confidence: 99%

“…Proterozoic stromatolitic and calcimicrobial reef architectures exhibit comparable relationships between large-scale changes in reef geometry and changes in relative sea level (Grotzinger 1989;Narbonne and James 1996;Turner et al 1997;Lemon 2000). In particular, several Mesoproterozoic (Narbonne and James 1996) and Neoproterozoic (Turner et al 1997;Lemon 2000) reefal deposits reveal vertical stacking of reef packages that record expansion, contraction, progradation, backstepping, and subaerial exposure of the reef system in response to major fluctuations in relative sea level. In these cases, coeval facies changes in off-reef strata support reconstructions of reef growth in response to changing sea level.…”

Section: Introductionmentioning

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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Reinterpreting a Proterozoic Enigma:Conophyton‐JacutophytonStromatolites of the Mesoproterozoic Atar Group, Mauritania

Kah

Bartley

Stagner

2009

Perspectives in Carbonate Geology

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The Mesoproterozoic Atar Group, Taoudeni Basin, Mauritania, preserves a spectacular diversity of stromatolite morphologies, including stromatolitic biostromes comprised of the conical form Conophyton, the enigmatic branching conical form Jacutophyton, and a variety of irregularly branching forms, including Tilemsina and Baicalia. Until now, the peculiar juxtaposition of high and low-relief stromatolite morphologies has posed a conundrum for environmental interpretation of stromatolite forms, and has led to interpretations of strict biological control over stromatolite morphology. Careful assessment of superpositional relationships among stromatolite elements, however, suggests that the diversity of stromatolite morphologies in the Atar Group can be readily explained via parasequence-scale sea-level changes and the incomplete and laterally discontinuous filling of accommodation space. In the Atar Group, biostrome growth initiates during relative rises in sea level with the widespread, subtidal nucleation of Conophyton. Exposure of Conophyton to wave energy during falls in relative sea level result in disruption of stromatolitic laminae, generation of interstromatolitic debris, and development of both superimposed and laterally adjacent branching stromatolite forms. In this scenario, the enigmatic stromatolite form Jacutophyton represents stromatolite growth through a complete depositional parasequence, and the unusual juxtaposition of stromatolite forms reflects growth of different forms that is separated by time and depositional environment. With subsequent rises in sea level, nucleation of new Conophyton in subtidal regions, and continued growth of branching forms and aggradation of the depositional substrate in intertidal regions, results in continued modification of sea floor topography. In the model presented here, stratigraphic time is partitioned both vertically and laterally during biostrome growth, resulting in a complex internal architecture that is not readily discerned in outcrop. In 3 connecting hydrodynamic variables to stromatolite morphology, this model provides a more comprehensive understanding of Atar Group stromatolites in terms of basin geometry, relative sea level, and carbonate production.

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A Neoproterozoic fringing stromatolite reef complex, Flinders Ranges, South Australia

Cited by 27 publications

References 7 publications

The End-Cryogenian Glaciation of South Australia

The End-Cryogenian Glaciation of South Australia

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

Reinterpreting a Proterozoic Enigma:Conophyton‐JacutophytonStromatolites of the Mesoproterozoic Atar Group, Mauritania

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