THE RUSSIAN PLATFORM AS A KEY REGION FOR VOLGIAN/TITHONIAN CORRELATION: A REVIEW OF THE MEDITERRANEAN FAUNAL ELEMENTS AND AMMONITE BIOSTRATIGRAPHY OF THE VOLGIAN STAGE

Abstract

<p class="abstract-testo">A review of the ammonite faunas and biostratigraphy of the uppermost Kimmeridgian - lowermost Middle Volgian of Central Russia is presented. The major role of the Sub-mediterranean ammonites in the Volgian assemblages is described, providing additional detail to the existing scheme of Tithonian-Volgian correlations. The base of the Tithonian and the base of the Volgian are coincident, based on the association of <em>Neochetoceras steraspis-Lingulaticeras solenoides</em>. The Klimovi Zone corresponds to most of the Hybonotum Zone. However, the top of the Hybonotum Zone, based on the distribution of <em>Paralingulaticeras</em>, falls within the Sokolovi Zone. The allocation of a Tenuicostata Subzone (with two horizons: <em>neoburgense</em> and <em>puschi</em>) in the Pseudoscythica Zone is proven. The <em>neoburgense</em> horizon may be correlated with the <em>ciliata</em> and <em>penicillatum</em> horizons of Neuburg and, probably, with the Semiforme Zone. The findings of <em>Lingulaticeras blaschkei</em>, <em>Pseudolissoceras,</em> and <em>Sutneria</em> in the Panderi Zone of the Middle Tithonian suggest that the base of the Middle Volgian may not be younger than the Middle Tithonian Fallauxi Zone.</p><p class="abstract-testo"></p>