Abstract

A gap corresponding to several conodont and chitinozoan zones occurs in the Llandovery-Wenlock boundary interval in some sections in the western coastal region of Estonia and on islands in the Muhu Strait. New data from the Suigu (S-3) core section demonstrate that the gap has geographically wider distribution in western continental Estonia. Detailed study of faunas from that section revealed that here the gap corresponds to at least four conodont zones (from below): the Lower and Upper Pseudooneotodus bicornis and Lower and Upper Pterospathodus pennatus procerus zones, but probably also the upper(most) Upper Pt. amorphognathoides amorphognathoides Subzone and the Lower Kockelella ranuliformis Zone (or part of it) are missing. In sense of chitinozoan biostratigraphy, the gap correlates with most of the Margachitina margaritana Zone. Only the uppermost part of this zone is represented in the section. However, although the gap in the Suigu (S-3) core section is distinct and well dated biostratigraphically, the δ 13 C curve demonstrates no evidence of it. Causes of this controversy are still waiting to be revealed. Our data indicate that changes in sedimentation in the Llandovery-Wenlock boundary interval occurred earlier in the distal graptolite-bearing and later in the proximal environments. Most probably, sedimentation in the Baltic Palaeobasin in the late Telychian and early Sheinwoodian was strongly affected by tectonic evolution of the Baltoscandian foreland basin.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.