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

Abstract

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

Detrital zircon provenance of north Gondwana Palaeozoic sandstones from Saudi Arabia

“…The latter is a complex amalgamation of numerous intra-oceanic island arc terranes accreted between~630 and 870 Ma, with igneous activity extending until 565 Ma (Kröner, 1985;Stern, 1994;Johnson et al 2011;Johnson, 2014). During the late Neoproterozoic, terrestrial sedimentary basins formed in which molasse was deposited under subaerial to shallow-water conditions, and variably interlayered with volcaniclastic rocks (Johnson et al 2011(Johnson et al , 2013. The Neoproterozoic rocks of the Arabian Shield are overlain with an erosional contact by Palaeozoic sandstones (Fig.…”

An Expanding Arabian-Nubian Shield Geochronologic and Isotopic Dataset: Defining Limits and Confirming the Tectonic Setting of a Neoproterozoic Accretionary Orogen

“…Older sedimentary basins in the ANS are widespread [74] and would provide additional suitable material for detrital zircon analysis. Implementation of detrital zircon dating programs is strongly recommended because the acquisition of detrital zircon data can be achieved relatively speedily, and the results would provide crucial insights into the composition and origin of the ANS and of continental crust surrounding the shield.…”

Geochemical Constraints of the Ediacaran Volcano‐Sedimentary Succession of the Sa'al Metamorphic Complex at Wadi Zaghra, South Sinai, Egypt

“…It was formed in Late Neoproterozoic time by prolonged accretion of oceanic island arc terranes due to late Neoproterozoic continental collision during closure of the Mozambique Ocean (e.g. Bentor, 1985;Stern, 1994;Meert, 2003;Stoeser and Frost, 2006;Johnson et al, 2013) that created many suture zones intruded by ophiolites (Abdelsalam and Stern, 1996;Stern, 1994;Stern et al, 2004;Ali el al., 2010;Khalil et al, 2014).…”