論文

2014年5月

Provenance variability along the Early Ordovician north Gondwana margin: Paleogeographic and tectonic implications of U-Pb detrital zircon ages from the Armorican Quartzite of the Iberian Variscan belt

GEOLOGICAL SOCIETY OF AMERICA BULLETIN
  • J. Shaw
  • ,
  • G. Gutierrez-Alonso
  • ,
  • S. T. Johnston
  • ,
  • D. Pastor Galan

126
5-6
開始ページ
702
終了ページ
719
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1130/B30935.1
出版者・発行元
GEOLOGICAL SOC AMER, INC

Detrital zircon laser ablation-inductively coupled plasma-mass spectrometry U-Pb age data from the Lower Ordovician Armorican Quartzite (deformed passive margin strata of Gondwanan affinity) of the Iberian Massif are presented herein. The S-shaped coupled Iberian oroclines defined within these zones palinspastically restore to a 2300 km linear Variscan orogen with a paleomagnetically constrained Late Carboniferous north-south trend. Detrital zircons are used to assess paleogeography and interpreted geometry of the Iberian portion of the Gondwana passive margin. A common signature is identified by (1) Neoproterozoic (ca. 500-850 Ma), (2) Stenian-Tonian (ca. 0.9-1.1 Ga), and lesser (3) Paleoproterozoic and (4) Archean populations (ca. 1.8-2.15 and 2.5-2.7 Ga, respectively). Minor site-to-site variation in relative proportion of widely ranging age groups suggests near-uniform distribution of a highly varied detrital input. Provenance analysis reveals strong correlations with Cambro-Ordovician clastic rocks from northeast African realms. Similarity with underlying sequences suggests a common paleogeography from the Ediacaran through early Paleozoic and persistence of a provenance distinction within the autochthonous Iberian Massif. Consistent northward paleo-flow within widespread northeast African lower Paleozoic sedimentary cover suggests long-distance sedimentary transport across a North African peneplain from outlying basement terranes. We propose that the 2300-km-long Cantabrian-Central Iberian portion of the early Paleozoic Gondwana margin stretched east-west along the northern limits of the then low-lying Saharan Metacraton and Arabian-Nubian Shield. Accepting paleomagnetic constraints, a 90 degrees counterclockwise rotation is required to reorient the Iberian portion to a pre-oroclinal (Late Carboniferous) north-south trend. The mechanisms for accommodating such a rotation are unclear.

Web of Science ® 被引用回数 : 66

リンク情報
DOI
https://doi.org/10.1130/B30935.1
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000341193400006&DestApp=WOS_CPL
URL
https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84900299334&origin=inward

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