Precambrian length of day and the validity of tidal rhythmite paleotidal values

Williams, George E.

doi:10.1029/97gl00234

Cited by 43 publications

(24 citation statements)

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“…If, as inferred here, Coriolis force is the key control on sinuosity, then it implies that highly sinuous submarine channels were even rarer in the past and only present in a narrower region either side of the equator, since the angular spin of the Earth was greater in the past ( Fig. 4; Sonett et al, 1996;Williams, 1997). If, however, Coriolis force is not the main mechanism, and instead climatic processes such as fl ow type and sediment type are the primary controls, then it suggests that there may be major differences in the global distribution of submarine channel sinuosity between glacially infl uenced and nonglacially infl uenced periods in Earth history, with possibly far more limited variations in nonglacially infl uenced periods.…”

Section: Implications For Sinuosity Change In Space and Timementioning

confidence: 60%

Global (latitudinal) variation in submarine channel sinuosity

Peakall

Kane

Masson

et al. 2012

Geology

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Section: Implications For Sinuosity Change In Space and Timementioning

confidence: 60%

Global (latitudinal) variation in submarine channel sinuosity

Peakall

Kane

Masson

et al. 2012

Geology

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“…In demonstrating this procedure, three independent values that have been determined directly from the Elatina-Reynella rhythmite record are used to calculate the lunar semimajor axis (mean Earth-Moon distance) at --•620 Ma [Deubner, 1990;Williams, 1990Williams, , 1997.…”

Section: Validity Of Neoproterozoic Valuesmentioning

confidence: 99%

Geological constraints on the Precambrian history of Earth's rotation and the Moon's orbit

Williams¹

2000

Reviews of Geophysics

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330

273

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Abstract. Over the past decade the analysis of sedimentary cyclic rhythmites of tidal origin, i.e., stacked thin beds or laminae usually of sandstone, siltstone, and mudstone that display periodic variations in thickness reflecting a strong tidal influence on sedimentation, has provided information on Earth's paleorotation and the evolving lunar orbit for Precambrian time (before 540 Ma). Depositional environments of tidal rhythmites range from estuarine to tidal delta, with a wave-protected, distal ebb tidal delta setting being particularly favorable for the deposition and preservation of long, detailed rhythmite records. The potential sediment load

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“…By comparing the Elatina rhythmites to two other putatively correlative rhythmite deposits in Southern Australia, the Reynella Siltstone Member and Chambers Bluff Tillite, Williams determined that the packages of laminae represent fortnightly cycles of spring-neap lunar tide deposits as a distal part of an ebbflood tidal delta (Zahnle and Walker 1987;Williams 1988). The literature since has focused on correlating rhythmite periodicities with tidal periodicities and elucidating the implications for the history of the Earth-Moon orbit (Williams 1997(Williams , 1998(Williams , 2000. Under this model, one couplet represents a semi-diurnal or diurnal depositional cycle, strictly constraining the rate of bedform migration and aggradation of the rhythmite sequences.…”

Section: Introductionmentioning

confidence: 99%

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.

show abstract

Precambrian length of day and the validity of tidal rhythmite paleotidal values

Cited by 43 publications

References 16 publications

Global (latitudinal) variation in submarine channel sinuosity

Global (latitudinal) variation in submarine channel sinuosity

Geological constraints on the Precambrian history of Earth's rotation and the Moon's orbit

The End-Cryogenian Glaciation of South Australia

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