Spore Assemblages from a Silurian Sequence in Borehole Hawiyah-151 from Saudi Arabia
Published:January 01, 2000
Charles H. Wellman, Ken T. Higgs, Philippe Steemans, 2000. "Spore Assemblages from a Silurian Sequence in Borehole Hawiyah-151 from Saudi Arabia", Stratigraphic Palynology of the Palaeozoic of Saudi Arabia, Sa’id Al-Hajri, Bernard Owens
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Spore assemblages are described from three cored intervals in the Silurian sequence in borehole Hawiyah-151 from central Saudi Arabia. Those from the oldest cored interval are correlated with the Imperfectotriletes spp.-Laevolancis divellomedia spore Assemblage Biozone [divellomedia Interval Biozone (α Subzone)], suggesting a Rhuddanian (possibly early Aeronian) age. The older samples from the middle cored interval are correlated with the Imperfectotriletes spp.-Laevolancis divellomedia spore Assemblage Biozone [divellomedia Interval Biozone (β Subzone)], suggesting a late Aeronian-early Telychian age, but the younger samples from this interval are correlated with the chulus-nanus spore Assemblage Biozone, suggesting a late Telychian-early Homerian age. Samples from the youngest cored interval are correlated with the brevicosta-verrucatus spore Assemblage Biozone, suggesting an early (but not earliest) Homerian-?earliest Gorstian age. Palynofacies analysis indicates that the deposits of the oldest and middle cored interval accumulated in a nearshore marine environment, but those of the youngest cored interval were deposited during a nearshore marine to non-marine regressive sequence. In the middle cored interval, the abundance of chitinozoans coupled with the paucity of acritarchs is intriguing. The sequence of Silurian spore assemblages in Saudi Arabia is clearly different to that reported in Laurentia, Avalonia and probably also Baltica. In Saudi Arabia, trilete spores and ornamented hilate cryptospores appear to make their inception earlier, and envelope-enclosed cryptospores persist in relative abundance for longer.