Volcanosedimentary Basins in the Arabian-Nubian Shield: Markers of Repeated Exhumation and Denudation in a Neoproterozoic Accretionary Orogen

Geosciences

Pete R. Johnson¹  Galen P. Halverson³  Timothy M. Kusky²  Robert J. Stern⁴ 

[1]6016 SW Haines Street, Portland, OR 97219, USA

[2]Three Gorges Research Center for Geohazards, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China

[3] E-Mail:

[4]Department of Earth and Planetary Sciences/Geotop, McGill University, Montreal, QC H3A 2A7, Canada

[5] E-Mail:

[6]Geosciences Department, University of Texas at Dallas, Richardson, TX 75080, USA

[7] E-Mail:

关键词: Arabian-Nubian Shield;    marine sediments;    terrestrial sediments;    post-amalgamation basins;    transpressional basins;    exhumation;    erosion;    subsidence;    Cryogenian;    Ediacaran;   

DOI  :  10.3390/geosciences3030389

来源: mdpi

【 摘 要 】

The Arabian-Nubian Shield (ANS) includes Middle Cryogenian-Ediacaran (790–560 Ma) sedimentary and volcanic terrestrial and shallow-marine successions unconformable on juvenile Cryogenian crust. The oldest were deposited after 780–760 Ma shearing and suturing in the central ANS. Middle Cryogenian basins are associated with ~700 Ma suturing in the northern ANS. Late Cryogenian basins overlapped with and followed 680–640 Ma Nabitah orogenesis in the eastern ANS. Ediacaran successions are found in pull-apart and other types of basins formed in a transpressive setting associated with E-W shortening, NW-trending shearing, and northerly extension during final amalgamation of the ANS. Erosion surfaces truncating metamorphosed arc rocks at the base of these successions are evidence of periodic exhumation and erosion of the evolving ANS crust. The basins are evidence of subsequent subsidence to the base level of alluvial systems or below sea level. Mountains were dissected by valley systems, yet relief was locally low enough to allow for seaways connected to the surrounding Mozambique Ocean. The volcanosedimentary basins of the ANS are excellently exposed and preserved, and form a world-class natural laboratory for testing concepts about crustal growth during the Neoproterozoic and for the acquisition of data to calibrate chemical and isotopic changes, at a time in geologic history that included some of the most important, rapid, and enigmatic changes to Earth’s environment and biota.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.