Revis[(! Espail0/a de Micropaleontulog!a, 32(3), 2000, pp. 371-3X3 © Instituto Tccnol6gico Geominero de Espafi<l ISSN: 0556-655X NATURE AND TIMING OF MARINE POST-CRISIS FORAMINIFERAL REPOPULATION (MESSINIAN EVENT; LATE TERTIARY) IN THE LORCA BASIN, SE SPAIN J. STEFFAHN & D. MICHALZIK lnstitut flir Geologie, Ruhr-Universitat Bochum, Universitatsstr. 150, 44801 Bochum, Germany E-mail: jens.steffahn@ruhr-uni-bochum.de;dieter.michalzik@ruhr-uni-bochum.de Abstract The examination of post-evaporitic sections in the central part of the Lorca Basin reveals rewor- ked but also indigenous foraminiferal assemblages. This implies that after an episode of restricted hostile evaporite or even partly continental conditions marine environments were re-established in the central part of the basin still during Messinian time. This re-establishment of marine ecosystems seems to have been a remarkably rapid event. Intermediate deep water foraminiferal faunas appear very soon after the initiation of post-evaporitic sedimentation. A renewed shallowing or strong effects of continental interference are not obvious in the central part of the basin until the Early Pliocene. The Miocene/Pliocene transition has been ascertained with some reservation in the upper parts of the two studied sections about 15 m above the evaporite sequence. Key words: Foraminifera, post-crisis repopulation, Miocene (Messinian) - Pliocene, Lorca Basin, SE Spain. Resumen La revision de la serie postevaporftica de la parte central de la cuenca de Lorca revela la presen- cia de foraminfferos retrabajados pero tambien de asociaciones indfgenas. Esto implica que, tras un episodio de condiciones hostiles, evaporfticas e incluso parcialmente continentales, las condiciones marinas se restablecieron en la parte central de la cuenca, aun durante el Messiniense. Este restable- cimiento de los ecosistemas marinos fue un even to nipido. Los foraminfferos de aguas profundas intermedias aparecieron inmediatamente despues del inicio de la sedimentacion postevaporftica. Una nueva regresion 0 los fuertes efectos de interferencias continentales no son patentes en la parte cen- tral de la cuenca hasta el Plioceno temprano. La transicion del Mioceno al Plioceno ha sido compro- bada, con algunas reservas, en la parte superior de las dos secciones estudiadas, unos 15 m por enci- ma de la secuencia evaporftica. Palabras clave: Foraminfferos, repoblacion post-crisis, Mioceno (Messiniense) - Plioceno, cuen- ca de Lorca, Sureste de Espafia. INTRODUCTION Two post-evaporitic sedimentary sections in the central part of the Lorca Basin have been investigated regarding their foraminiferal content. The study was carried out within the scope of the project "Lithofacies and biofacies development of marine Mediterranean ecosystems after the Messinian salinity crisis", funded by the Deutsche Forschungs- gemeinschaft. The aim of this study is to elucidate the post-crisis sedimentary and paleoecologic history by means of foraminiferal distribution patterns and tap- honomical inquiry. Biostratigraphic correlation is based on planktic foraminifera. Concerning the Lorca Basin and other Neogene basins of SE Spain a major controversy has evolved 371