Saqqar: A 34 km diameter impact structure in Saudi Arabia

Thomas Kenkmann*, Abdulkader M. Afifi, Simon A. Stewart, Michael H. Poelchau, Douglas J. Cook, Allen S. Neville

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Here we present the first proof of an impact origin for the Saqqar circular structure in northwestern Saudi Arabia (Neville et al.), with an apparent diameter of 34 km, centered at 29°35′N, 38°42′E. The structure is formed in Cambrian-Devonian siliciclastics and is unconformably overlain by undeformed Cretaceous and Paleogene sediments. The age of impact is not well constrained and lies somewhere between 410 and 70 Ma. The subsurface structure is constrained by 2-D reflection seismic profiles and six drilled wells. First-order structural features are a central uplift that rises approximately 2 km above regional datums, surrounded by a ring syncline. The crater rim is defined by circumferential normal faults. The central uplift and ring syncline correspond to a Bouguer gravity high and an annular ring-like low, respectively. The wells were drilled within the central uplift, the deepest among them exceed 2 km depth. Sandstone core samples from these wells show abundant indicators of a shock metamorphic overprint. Planar deformation features (PDFs) were measured with orientations along (0001), {1013}, and less frequently along {1011} and {1014}. Planar fractures (PFs) predominantly occur along (0001) and {1011}, and are locally associated with feather features (FFs). In addition, some shocked feldspar grains and strongly deformed mica flakes were found. The recorded shock pressure ranges between 5 and 15 GPa. The preserved level of shock and the absence of an allochthonous crater fill suggest that Saqqar was eroded by 1-2 km between the Devonian and Maastrichtian. The documentation of unequivocal shock features proves the formation of the Saqqar structure by a hypervelocity impact event.

Original languageEnglish (US)
Pages (from-to)1925-1940
Number of pages16
JournalMeteoritics and Planetary Science
Volume50
Issue number11
DOIs
StatePublished - Nov 1 2015

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Saqqar: A 34 km diameter impact structure in Saudi Arabia'. Together they form a unique fingerprint.

Cite this