MIOCENE BENTHIC FORAMINIFERA FROM NOSY MAHAKAMBY AND AMPARAFAKA, MAHAJANGA BASIN, NORTHWESTERN MADAGASCAR
RAMIHANGIHAJASON, Tolotra N.1, ANDRIANAVALONA, Tsiory H.1, RAZAFIMBELO, Rachel2, RAHANTARISOA, Lydia2, ALI, Jason R.3 and SAMONDS, Karen E.4, (1)Département de Paléontologie et d'Anthropologie Biologique, University of Antananarivo, Antananarivo, 101, Madagascar, (2)Département des Sciences de la Terre, Faculté des Sciences, University of Antananarivo, Antananarivo, 101, Madagascar, (3)Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, NA, (4)Department of Biological Sciences, Northern Illinois University, Dekalb, 60115, ainaramihangi@gmail.com
Madagascar is well known for its fossil deposits and hosts one of the World’s most important Upper Cretaceous terrestrial faunal sites (in the Mahajanga and Morondava Basins in the west and northwest of the island). Cenozoic marine fossils are also present on Madagascar, but these have received far less attention from the palaeontological community, with most of the work dating from the 19th and early 20thcenturies.
Our study reports a new comprehensive microfossil assemblage, results of detailed investigation of a Miocene sequence on Nosy Mahakamby, a small island off northwest Madagascar. This island is approximately 50 km west along the coast from the regional capital Mahajanga. This work was based on two field seasons carried out between 2010 and 2011.
After washing, sieving and sorting the sediments from the island (30 kg), twenty-five genera of foraminifera were identified including Quinqueloculina, Elphidium, Nonion, and Ammonia.
In association with the foraminifera, are ostracods plus a variety of others macrofossils including bivalves, gastropods, echinoids, sharks, non-diagnostics reptiles (turtles, crocodylians) and sirenians. Together, the assemblage indicates that the Nosy Mahakamby area in the late Miocene was as a tropical, near-shore environment, probably not too dissimilar to that of today.
