Tethys: Marine Geosciences

Şengör, A. M. Celâl

doi:10.1007/978-94-007-6644-0_205-2

Cited by 1 publication

(2 citation statements)

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“…It is often assumed that the northern boundary of Tethys was active and the southern one passive. This is wrong as the southern margin of the Paleo‐Tethys was active as well as the northern one, but both were roughly equidistant from the equator (Şengör, ). Pangea was assembled by the progressive collision of Gondwana‐Land and Laurasia, near the end of Devonian, in the Huastecan/Appalachian/Hercynian collisional system.…”

Section: Pangea and The Tethyan Realmmentioning

confidence: 99%

“…The continents above 2‐km water depth cover at present 40.6% of the surface of the Earth, with an average height of 453 m and an average crustal thickness of 32.6 km, a little bit less than half the surface of the Earth, as discussed by Le Pichon and Huchon (). Assuming that the surface of the continents has not significantly changed since, the remaining 20% of the surface of the hemisphere were occupied by the Tethyan Realm, as defined by the Palaeo‐ and the Neo‐Tethyan ocean floors at any one time plus their continental margins (Şengör, ; Şengör & Atayman, ). It is important to note that the Tethyan Realm was occupied successively by the Paleo‐Tethys and then by the Neo‐Tethys, the latter one growing at the expense of the former one.…”

Section: Pangea and The Tethyan Realmmentioning

confidence: 99%

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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 The Tethyan Realmmentioning

confidence: 99%

Section: Pangea and The Tethyan Realmmentioning

confidence: 99%