10. Flood Basalt Provinces of the Pangean Atlantic Rift: Regional Extent and Environmental Significance

McHone, J. Gregory; Puffer, John H.; LeTourneau, Peter M.; Olsen, Paul E.

doi:10.7312/leto11162-009

Cited by 10 publications

(6 citation statements)

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“…This was discussed by Le Pichon et al () for the fracturing preceding the CAMP event within the future North Atlantic and its prolongation within the Western Tethys. Extensional tectonics are manifest everywhere in the future CAMP area, starting about 25–30 Myr earlier within Triassic (Carnian‐Norian) as described by McHone and Puffer (). They occur along a linear extensional system without any evidence of doming.…”

Section: Pangea and Flood Basaltsmentioning

confidence: 83%

Pangea and the Lower Mantle

2019

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We show that the peripheral Pangea subduction zone closely followed a polar great circle. We relate it to the band of faster-than-average velocities in lowermost mantle. Both structures have an axis of symmetry in the equatorial plane. Assuming geologically long-term stationarity of the deep mantle structure, we propose to use the axis of symmetry of Pangea to define an absolute reference frame. This reference frame is close to the slab remnants and NNR frames of reference but disagrees with hot spot-based frames. We apply this model to the last 400 Myr. We show that a hemispheric supercontinent appeared as early as 400 Ma. However, at 400 Ma, the axis of symmetry was situated quite far south and progressively migrated within the equatorial plane that it reached at 300 Ma. From 300 to 110-100 Ma, it maintained its position within the equatorial plane. We propose that the stationarity of Pangea within a single hemisphere surrounded by subduction zones led to thermal isolation of the underlying asthenosphere and consequent heating as well as a large accumulation of hot plume material. We discuss some important implications of our analysis concerning the proposition that the succession of supercontinents and dispersed continents is controlled by an alternation from a degree 1 to a degree 2 planform.

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Section: Pangea and Flood Basaltsmentioning

confidence: 83%

Pangea and the Lower Mantle

2019

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“…CAMP magmatism is nowadays represented by remnants of intrusive (crustal underplates, layered intrusions, sills, dikes) and, less abundant, extrusive rocks (mainly lava flows) that occur in oncecontiguous parts of North and South America, north-western Africa and south-western Europe (Marzoli et al 1999;McHone & Puffer 2003). 40 Ar/ 39 Ar plateau ages of CAMP lava flows range from 201 to 191 Ma, with a main cluster at c. 198 -200 Ma (Knight et al 2004;Marzoli et al 2004;Nomade et al 2007;Verati et al 2007;Jourdan et al 2009).…”

Section: Geodynamic Contextmentioning

confidence: 99%

Morphology, internal architecture and emplacement mechanisms of lava flows from the Central Atlantic Magmatic Province (CAMP) of Argana Basin (Morocco)

Hachimi

Youbi

Madeira

et al. 2011

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The morphology, internal architecture and emplacement mechanisms of the Central Atlantic Magmatic Province (CAMP) lava flows of Argana Basin in Morocco are presented. The volcanic pile was produced by two volcanic pulses. The first, represented by the Tasguint Formation, corresponds to a succession of 3 -13 individual flows created by 1-8 eruptions; the second, Alemzi Formation, is composed of 2 -7 individual flows formed by 1-4 eruptions. These formations, geochemically distinct, are separated by thin silty or sandy horizons or by palaeosols. They include 'compound pahoehoe flows' and 'simple flows'. The first type is almost exclusive of the lower formation, while the second type dominates the upper formation. The lava flows show clear evidence of endogenous growth or 'inflation'. The characteristics of the volcanic pile suggest slow emplacement during sustained eruptive episodes and are compatible with a continental basaltic succession facies model. Earth's history has been punctuated over at least the last 3.5 billion years by episodic massive volcanic events on a scale unknown in the recent geological past. Largely unknown mechanical and dynamic processes, with unclear relationships to seafloor spreading and subduction, generated voluminous, predominantly mafic magmas that were emplaced into the Earth's crust. The resultant large igneous provinces (LIPs; Coffin & Eldholm 1994;Ernst & Buchan 2001;Sheth 2007;Bryan & Ernst 2008) were at times accompanied by catastrophic environmental changes (Rampino et al.

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“…The two models might agree better for post-basalt features, in which alluvial breccias and basement-clast conglomerates were developed in Jurassic strata along some border faults according to tectonic action soon after the volcanism (McHone and Puffer 2003). This process is indicated by paleo-talus along the northern end of the Fundy Basin (Olsen and Et-Touhami 2008), by regional tilting of all basin strata toward border faults, and by Jurassic border fanglomerates mapped in rift basins in eastern North America (Olsen 1997).…”

Section: Discussionmentioning

confidence: 99%

“…3), and they may have been contiguous before tectonic activity and erosion created the present map patterns. Discussions of related "broad terrane" vs. "closed basin" models have been presented by McHone (1996), Wade et al (1996), Olsen (1997), Pe-Piper andPiper (1999), andPuffer (2003), among others, and a related model for the Grand Manan Basin will be developed in further work on tectonic structures and basalts.…”

Section: The Fundy Basinmentioning

confidence: 99%

Triassic Basin Stratigraphy at Grand Manan, New Brunswick, Canada

McHone¹

2011

atgeol

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The island of Grand Manan (Canada) in the southwestern Bay of Fundy has the only exposed strata and basalt of the Grand Manan Basin, a mainly submerged Early Mesozoic riﬅ basin about 30 km wide by 70 km long. The basin is bounded on the southeast by the west-dipping Red Point Fault, which bisects the island, and on the northwest by a submarine border fault marked by the Murr Escarpment, a bathymetric feature that parallels the coast of Maine (USA). A fault-bounded horst of Ediacaran to Cambrian rocks separates the Grand Manan Basin from the much larger Fundy Basin to the east. The Ashburton Head, Seven Days Work, and Southwest Head members of the end-Triassic Dark Harbour Basalt cover most of western Grand Manan with a total thickness around 240 m. Up to 12 m of sub-horizontal grey mudstone and fine-grained red sandstone of the Dwellys Cove Formation are exposed along the western shoreline beneath the basalt. Coarse red arkosic sandstone a few metres thick at Miller Pond Road rests on a basement of Late Ediacaran rocks east of the basin. Exposures of the Dwellys Cove and Miller Pond Road formations are at the top and bottom, respectively, of several km (?) of sub-horizontal Late Triassic clastic basin strata, juxtaposed by the eastern border fault. Extending from beneath the Miller Pond Road sandstone, a level surface of low relief forms much of the eastern island and its archipelago, which may be interpreted as a relict Late Triassic peneplain that was beneath the Mesozoic strata. RÉSUMÉ L’île Grand Manan (Canada) au sud‑ouest de la baie de Fundy possède la seule strate et basalte qui affleure du bassin de Grand Manan, un bassin d’eﬀondrement en bonne partie submergé du début du Mésozoïque qui fait environ 30 km de large sur 70 km de long. Ce bassin est bordé au sud-est par la faille de Red Point qui présente en pend-age vers l’ouest et qui traverse l’île de part en part, et au nord‑ouest, par une faille de bordure sous‑marine marquée par l’escarpement Murr, une structure bathymétrique qui longe la côte du Maine (É.‑U.). Un horst bordé par une faille et composé de roches de la période comprise entre Ediacara et le Cambrien sépare le bassin de Grand Manan du bassin de Fundy, beaucoup plus vaste, à l’est. Les membres de Ashburton Head, de Seven Days Work et de Southwest Head de la formation de basalte de Dark Harbour, de la fin du Trias, recouvrent la plus grande partie de l’ouest de l’île Grand Manan, et leur épaisseur totale serait d’environ 240 m. Des roches de mudstone gris subhorizontal et de grès rouge à grains fins de la Formation de Dwellys Cove dont l’épaisseur peut atteindre 12 m affleurent le long du rivage occidental, sous le basalte. Une couche de grès arkosique rouge grossier de quelques mètres d’épaisseur sur Miller Pond Road repose sur un socle de roches de la fin d’Ediacara, à l’est du bassin. Des affleurements des Formations de Dwellys Cove et de Miller Pond Road sont observés respectivement au sommet et à la base de la strate subhorizontale de plusieurs kilomètres (?) d’un bassin de roches clastiques de la fin du Trias, en juxtaposition avec la faille de bordure orientale. Sous le grès de Miller Pond Road, une surface de niveau en terrain peu accidenté se prolonge et compose la plus grande portion de la partie est de l’île et de son archipel, ce qui pourrait suggérer la présence d’une ancienne pénéplaine du Trias tardif qui se trouvait sous la strate du Mésozoïque. [Traduit par la redaction]

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10. Flood Basalt Provinces of the Pangean Atlantic Rift: Regional Extent and Environmental Significance

Cited by 10 publications

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Pangea and the Lower Mantle

Pangea and the Lower Mantle

Morphology, internal architecture and emplacement mechanisms of lava flows from the Central Atlantic Magmatic Province (CAMP) of Argana Basin (Morocco)

Triassic Basin Stratigraphy at Grand Manan, New Brunswick, Canada

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