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Basement Fragments, Accreted Tectonostratigraphic Terranes, and Overlap Sequences: Elements in the Tectonic Evolution of The Arabian Shield

Johnson, Peter R ; Scheibner, Erwin ; Smith, E. Alan Leitch, Evan C ; Scheibner, Erwin

Terrane Accretion and Orogenic Belts, 1987, p.323-343 [Periódico revisado por pares]

Washington, D. C: American Geophysical Union

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  • Título:
    Basement Fragments, Accreted Tectonostratigraphic Terranes, and Overlap Sequences: Elements in the Tectonic Evolution of The Arabian Shield
  • Autor: Johnson, Peter R ; Scheibner, Erwin ; Smith, E. Alan
  • Leitch, Evan C ; Scheibner, Erwin
  • Assuntos: Geology, Structural ; Orogeny
  • É parte de: Terrane Accretion and Orogenic Belts, 1987, p.323-343
  • Descrição: The layered rocks of the Arabian Shield comprise stratotectonic units that are diagnostic of particular tectonic events contributory to Proterozoic crustal growth in Arabia, and constitute stages in the tectonic evolution of the Shield. Middle Proterozoic or older (2000 to 1630 Ma) paraschist, paragneiss, and correlative metagranitic rocks, which underlie parts of the central Shield, represent an initial “basement” stage. The rocks form basement fragments; they probably originated by extension and dispersion of a pre‐existing craton, and were incorporated as allochthonous microplates into younger tectonostratigraphic units. Volcanic complexes, ophiolitic complexes, and marginal‐basin and fore‐arc stratotectonic units deposited between 950 to 670 Ma form a “precratonic” stage in Shield evolution. The rocks accumulated in the intraoceanic to continental‐marginal environments which resulted from crustal dispersion subsequent to the basement stage. The precratonic rocks constitute as many as ten tectonostratigraphic terranes, which accreted between 770 and 620 Ma to form a neocraton on which younger rocks were deposited. Volcanosedimentary overlap sequences deposited (760‐570 Ma) in downwarp basins and in ensialic successor basins constructed above the joins between older terranes represent the succeeding “transitional‐tectonic” stage. Volcanosedimentary rocks deposited in pull‐apart basins which resulted from intraplate movements associated with the formation of transcurrent faults of the Najd system, constitute a “reactivation‐tectonic” stage (670–570 Ma). By about 550 Ma, these events had resulted in the formation of a stable block of continental lithosphere. Phanerozoic sedimentary and Cenozoic volcanic rocks, deposited during an “epicratonic” stage of tectonic evolution, partly cover the continental block. It is currently being dispersed by oceanfloor spreading in the Red Sea, an event that may mark the onset of a new cycle of crustal growth.
  • Editor: Washington, D. C: American Geophysical Union
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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