Ammonites from the Curaçao lava formation, Curaçao, Caribbean

Abstract

Ammonites have been discovered for the first time in some thin pelagic intercalations in the Curaçao Lava Formation. Since this is the oldest rock unit which occurs on the island, its dating is of extreme interest. The rather poorly preserved and partly baked ammonites can be attributed to the genera Beudanticeras, Cleoniceras (Grycia), Gastroplites, ?Dipoloceras, Hysteroceras and ?Pervinquieria. The Curaçao Lava Formation is, thus, of upper Middle Albian age. This is consistent with the available equivalent K/Ar-data of 118 ± 10 and126 ± 12 M.A.b.p. (Santamaría & Schubert, 1974), since submarine extruded basalts dated by this method generally give ages somewhat too high. Paleobiogeographic relationships point to the Western Interior and Pacific faunal provinces of North America, and, to a minor degree, to the European Tethys. Moreover, this is exactly the time when Northern and Southern Atlantic became connected for the first time (WIEDMANN & NEUGEBAUER, 1978).