Anatomy of North America: thematic geologic portrayals of the continent

Williams, Harold; Hoffman, Paul F.; Lewry, John F.; Monger, J. W. H.; Rivers, Toby

doi:10.1016/0040-1951(91)90416-p

Cited by 229 publications

(73 citation statements)

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“…(Williams et al 1991). With the disappearance of the District of Keewatin as a political entity, Hank's cratons reverted to their synonyms, the Rae and Hearne cratons respectively (Hoffman 1988;Eglington et al 2013).…”

Section: Sommairementioning

confidence: 99%

The Origin of Laurentia: Rae Craton as the Backstop for Proto-Laurentian Amalgamation by Slab Suction

Hoffman

2014

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Proto-Laurentia (i.e. pre-Grenvillian Laurentia) is an aggregate of six or more formerly independent Archean cratons that amalgamated convulsively in geons 19 and 18 (Orosirian Period), along with non-uniformly distributed areas of juvenile Paleoproterozoic crust. Subduction polarities and collision ages have been provisionally inferred between the major cratons (and some minor ones), most recently between the Rae and Hearne cratons. The oldest Orosirian collisions bound the Rae craton: 1.97 Ga (Taltson-Thelon orogen) in the west, and 1.92 Ga (Snowbird orogen) in the southeast. All other Orosirian collision ages in proto-Laurentia are < 1.88 Ga. The Rae craton was the upper plate during (asynchronous) plate convergence at its western and, tentatively, southeastern margins. Subsequent plate convergence in the Wopmay and Trans-Hudson orogens was complex, with the Rae craton embedded in the lower plate prior to the first accretion events (Calderian, Reindeer and Foxe orogenies), but in the upper plate during major subsequent convergence and terminal collisions, giving rise to the Great Bear and Cumberland magmatic arcs, respectively. The ‘orthoversion’ theory of supercontinental succession postulates that supercontinents amalgamate over geoidal lows within a meridional girdle of mantle downwellings, orthogonal to the lingering superswell at the site of the former supercontinent. If the downwelling nodes develop through positive feedback from the descent of cold oceanic slabs, then viscous traction should contribute to drawing the cratons together over the downwelling node. Viewed in this way, the Rae craton was the first to settle over the downwelling node and became the backstop for the other cratons that were drawn towards it by subduction. It was, literally, the origin of Laurentia. Whether the Rae craton was also the origin of Nuna, the hypothetical cogenetic supercontinent, depends on ages and subduction polarities of Orosirian sutures beyond proto-Laurentia.SOMMAIRELa proto-Laurentie (c.-à-d. la Laurentie pré-grenvillienne) est un agrégat d’au moins six cratons archéens indépendants qui se sont amalgamés convulsivement durant les géons 19 et 18 (Orosirien), le long de zones de croûtes juvéniles paléoprotérozoïques réparties de manière hétérogène. Les polarités de subduction et les âges de collision entre les grands cratons (et d’autres moins grands) ont été provisoirement déduits, le plus récemment entre le craton de Rae et le craton de Hearne. Les plus anciennes collisions orosiriennes ont soudé le craton de Rae : 1,97 Ga (orogène de Taltson-Thelon) dans l’ouest, et 1,92 Ga (orogène de Snowbird) dans le sud-est. Tous les autres âges de collision en proto-Laurentie sont inférieurs à 1,88 Ga. Le craton de Rae constituait la plaque supérieure durant la convergence de plaque (asynchrone) à sa marge ouest, et peut-être aussi à ses marges sud-est. La convergence de plaque subséquente dans les orogènes de Wopmay et Trans-Hudson a été complexe, le craton de Rae étant encastré dans la plaque inférieure avant les premiers événements d’accrétion (orogènes caldérienne, de Reindeer et de Fox), puis dans la plaque supérieure durant la grande convergence subséquente et les collisions terminales, ce qui a créé les arcs magmatiques de Great Bear et de Cumberland respectivement. La théorie de « l’orthoversion » de la succession des supercontinents présuppose que les supercontinents s’amalgament au-dessus de creux géoïdaux en deça d’une gaine méridienne de convections mantéliques descendantes, à angle droit d’un super-renflement persistant au site d’un ancien supercontinent. Si le nœud de convection descendante s’établit par rétroaction positive de la descente de plaques océaniques froides, la traction visqueuse devrait contribuer à entraîner les cratons ensembles au-dessus du nœud de convection descendante. Vu de cette façon, le craton de Rae a été le premier à s’établir au-dessus du nœud de convection descendante, ce qui en a fait la butée des autres cratons entraînés par la subduction. Littéralement, telle a été l’origine de la Laurentie. Quant à savoir si c’est le craton de Rae qui a été à l’origine de Nuna, cet hypothétique surpercontinent cogénétique, cela dépend des âges et des polarités de subduction des sutures orosiriennes au-delà de la proto-Laurentie.

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Section: Sommairementioning

confidence: 99%

The Origin of Laurentia: Rae Craton as the Backstop for Proto-Laurentian Amalgamation by Slab Suction

Hoffman

2014

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“…(h) Metamorphic geothermal gradients (summarized by Brown 2007) that illustrate the distribution of two metamorphic types that are considered to characterize plate tectonic processes; granulite ultra high temperature metamorphism (G-UHTM) and medium pressure eclogite ultra high pressure metamorphism (E-UHPM). (i) The distribution of proposed supercontinents Nuna and Kenorland that mark the supercontinent cycle of the Palaeoproterozoic era (after Williams et al 1991;Bleeker 2003;Barley et al 2005). (j) Distribution of different types of ore deposits (following Groves et al 2005).…”

Section: Evolution Of the Corementioning

confidence: 99%

“…The age peaks are global in distribution, although many regions contain regional signatures, and they are best correlated to collisional accretion of cratons in North America (Hoffman 1988(Hoffman , 1989. This led to the naming of successively older pre-Pangaean supercontinents Grenvilleland, Hudsonland and Kenorland (Williams et al 1991). The younger two of these entities are most commonly given alternative names Rodinia (for recent reviews, see Evans 2009), and Nuna or Columbia (Hoffman 1997;Rogers & Santosh 2002); 'Grenvilleland' has been forgotten, and 'Hudsonland' almost so (cf.…”

Section: Supercontinentsmentioning

confidence: 99%

Palaeoproterozoic supercontinents and global evolution: correlations from core to atmosphere

Reddy

Evans

2009

115

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The Palaeoproterozoic era was a time of profound change in Earth evolution and represented perhaps the first supercontinent cycle, from the amalgamation and dispersal of a possible Neoarchaean supercontinent to the formation of the 1.9-1.8 Ga supercontinent Nuna. This supercontinent cycle, although currently lacking in palaeogeographic detail, can in principle provide a contextual framework to investigate the relationships between deep-Earth and surface processes. In this article, we graphically summarize secular evolution from the Earth's core to its atmosphere, from the Neoarchaean to the Mesoproterozoic eras (specifically 3.0-1.2 Ga), to reveal intriguing temporal relationships across the various 'spheres' of the Earth system. At the broadest level our compilation confirms an important deep-Earth event at c. 2.7 Ga that is manifested in an abrupt increase in geodynamo palaeointensity, a peak in the global record of large igneous provinces, and a broad maximum in several mantle-depletion proxies. Temporal coincidence with juvenile continental crust production and orogenic gold, massive-sulphide and porphyry copper deposits, indicate enhanced mantle convection linked to a series of mantle plumes and/or slab avalanches. The subsequent stabilization of cratonic lithosphere, the possible development of Earth's first supercontinent and the emergence of the continents led to a changing surface environment in which voluminous banded iron-formations could accumulate on the continental margins and photosynthetic life could flourish. This in turn led to irreversible atmospheric oxidation at 2.4-2.3 Ga, extreme events in global carbon cycling, and the possible dissipation of a former methane greenhouse atmosphere that resulted in extensive Palaeoproterozoic ice ages. Following the great oxidation event, shallow marine sulphate levels rose, sediment-hosted and iron-oxide-rich metal deposits became abundant, and the transition to sulphide-stratified oceans provided the environment for early eukaryotic evolution. Recent advances in the geochronology of the global stratigraphic record have made these inferences possible. Frontiers for future research include more refined modelling of Earth's thermal and geodynamic evolution, palaeomagnetic studies of geodynamo intensity and continental motions, further geochronology and tectonic syntheses at regional levels, development of new isotopic systems to constrain geochemical cycles, and continued innovation in the search for records of early life in relation to changing palaeoenvironments.

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“…This is not necessarily the age of the units within each area, but the age at which that region of crust was assembled as a unit. This is a compilation of data from numerous publications covering South America Milani and De Wit, 2008), North America (Canil, 2008;Williams et al, 1991), Europe (Gee and Stephenson, 2006), Africa and Arabia (Begg et al, 2009;Van Hinsbergen et al, 2011), Asia (Şengör and Natal'in, 1996) and Australia (Debayle and Kennett, 2003). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 …”

Section: Discussionmentioning

confidence: 99%

Basin formation by thermal subsidence of accretionary orogens

2015

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Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Response to referees of Holt et al.We thank the three referees for their extremely helpful comments on the submitted paper, and appreciate the time that must have been needed. We have paid close attention to their suggestions, and feel that the revised paper greatly benefits from the constructive criticism. We take each referee's comments in turn, below, and offer a point-by-point account of how we have addressed them in the revised version. Our responses are preceded by the # symbol and are in italics.1. Five basins were chosen for the analysis. Why were these basins chosen? The main goal of this paper is to show that a lithosphere cooling model is a fundamental process in accretionary orogens. Therefore, the choice of the case studies needs to be carefully justified to show that these are 'typical' basins (i.e., there are no special conditions that could lead to a subsidence pattern similar to that of the cooling model). This is done in places in the manuscript, but it should be more explicit. At the moment, it isn't clear if the five basins are representative of accretionary orogens or if they were chosen because they fit the cooling model. 2. The cooling model is only vaguely described and no quantitative details are provided. Perhaps there should be a separate section with a conceptual description of the cooling model -why is it expected that accretionary crust has a thin initial lithosphere, what maintains the thin lithosphere, and what happens to cause the lithosphere to start to cool? It is stated that this model is different from a mantle delamination model (top of pg 4), but the 'alternate' mechanism for creating thin lithosphere is not clearly described. #Text has been added to explain the cooling model in section 2. There is also a longer description of why accretionary crust starts with thin mantle lithosphere in the Introduction. Both of these items were first described in Holt et al (2010): the only reason they were not originally given more length in this paper is that we thought readers would prefer a terse version of the material!In addition, the actual numerical values used in the cooling model need to be given. Readers are referred to the Holt et al. (2010) paper, but it isn't clear how this method was applied to the current study. For example: Do all regions start with a 20 km thick mantle lithosphere or does this vary (as implied on pg 15, line ~18: "an unusually thin initial lithosphere…is required")? How was crustal thickness var...

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Anatomy of North America: thematic geologic portrayals of the continent

Cited by 229 publications

References 28 publications

The Origin of Laurentia: Rae Craton as the Backstop for Proto-Laurentian Amalgamation by Slab Suction

The Origin of Laurentia: Rae Craton as the Backstop for Proto-Laurentian Amalgamation by Slab Suction

Palaeoproterozoic supercontinents and global evolution: correlations from core to atmosphere

Basin formation by thermal subsidence of accretionary orogens

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