Aeronian and Telychian chitinozoans from Central Saudi Arabia. - INSU - Institut national des sciences de l'Univers Access content directly
Conference Papers Year : 2008

Aeronian and Telychian chitinozoans from Central Saudi Arabia.

Florentin Paris
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Merrell Miller
  • Function : Author
Sa'Id Al-Hajri
  • Function : Author
Jan Zalasiewicz
Mark Williams


A total of 58 core samples from three shallow core holes (Qusaiba-1, Baq'a-3 and Baq'a-4) penetrating the Qalibah Formation in Central Saudi Arabia have been investigated. The core samples are grey-greenish hemipelagic shale or silty-shale and yield very well-preserved and abundant Early Silurian chitinozoans. Most of the recorded chitinozoan assemblages are highly diverse and include several new taxa coexisting with well-known species. Five chitinozoan biozones ranging from the Aeronian to the Telychian, and considered of regional value at the scale of Northern Gondwana regions, are identified. From the oldest to the youngest they are the: Conochitina alargada, Angochitina hemeri, Angochitina maclurei, Tanuchitina obtusa and Euconochitina silurica biozones. The three older regional biozones have been already reported in Saudi Arabia (Paris et al. 1995) whereas the two youngest ones are documented for the first time in the Arabian Peninsula. Their eponymous index species were described from the subsurface of the Algerian Sahara. Several sub-biozones of at least local application are also defined. The fairly closely spaced and regular sampling permits the total range of several highly diagnostic forms to be better constrained and thus the interval of uncertainty between biozones is reduced. Beside abundant chitinozoans and acritarchs, sporadic occurrences of scolecodonts and of eurypterid cuticle fragments are also noted in the organic residues. The presence of eurypterids suggests a shallowing trend in the sedimentary record, which is consistent with the distribution of the graptolites sicula and/or rhabdosomes. Indeed, the graptolites are frequent through the Qusaiba Member, except in the youngest examined samples where shallower environments like those in the Sharawra Member begin. Recently, Zalasiewicz et al. (2007) studied in detail the range of the graptolites in the three shallow cores. These graptolite data provide independent chronostratigraphical control refining previous age assignments. The alargada and the hemeri chitinozoan biozones correspond to the mid-Aeronian convolutus graptolite biozone whereas the maclurei chitinozoan biozone extends through the early Telychian guerichi and turriculatus graptolite biozones. The obtusa and the silurica chitinozoan biozones occur in an interval devoid of graptolites are referred to the mid-late Telychian as they do not contain yet typical Sheinwoodian species.
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insu-00376429 , version 1 (17-04-2009)


  • HAL Id : insu-00376429 , version 1


Florentin Paris, Merrell Miller, Sa'Id Al-Hajri, Jan Zalasiewicz, Mark Williams. Aeronian and Telychian chitinozoans from Central Saudi Arabia.. IPC, Sep 2008, Bonn, Germany. pp.215. ⟨insu-00376429⟩
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