The Albian of Central Tunisia in the Kalaat Senan-Jérissa area: planktonic foraminifera and ammonite faunas in an expanded section

Abstract

An investigation of expanded sections spanning the upper Aptian to lower Cenomanian interval in the Kalaat Senan-Jérissa area of eastern central Tunisia demonstrates that the base of the Albian, defined by the first occurrence of the planktonic foraminiferan Microhedbergella renilaevis Huber and Leckie, 2011, lies above the successive ammonite zones of Mellegueiceras chiaouiae, ‘Hypacanthoplites’ paucicostatus, Mellegueiceras ouenzaensis, and part or all of the ‘Hypacanthoplites’ buloti Zone of previous authors, which are thus Aptian in age. A major hiatus, of approximately 1 myr duration, is present between the uppermost Aptian and lowermost Albian, which encompasses the lower Albian Microhedbergella renilaevis, Ticinella rischi and Ticinella madecassiana planktonic foraminiferan zones. Absence of an ammonite record extending from the lower (but not lowest) middle Albian to the lower (but not lowest) upper Albian indicates the presence of a further hiatus, including most of the middle Albian and the lower part of the upper Albian (Dipoloceras cristatum Zone). Recorded by previous authors, the extent of this hiatus is now precisely dated. The upper Albian Pervinquieria (Pervinquieria) inflata, Pervinquieria (Pervinquieria) fallax and Pervinquieria (Subschloenbachia) rostrata ammonite zones are also absent, as a result of either non-preservation, hiatus or condensation. This is the first precise dating of the major intra-Cretaceous hiatuses which extend across North Africa.