Floral data from the mid-Cenozoic of central Pakistan
Résumé
Floral remains are generally rare in the fossil record of Pakistan. We present here new discoveries of mid-Cenozoic wood and pollen of Oligocene deposits from central Pakistan. The palynological sample derives from claystone stratigraphically positioned above the wood fossils, but pollen and spores as well as the wood are all of Oligocene age. The three fossil wood samples derive from the top of the lower unit of the Chitarwata Formation, and the palynological sample comes from claystone situated in the middle unit of the formation. The wood samples are described and found to represent two species of the morphotaxon Terminalioxylon (Combretaceae): T burmense Madel-Angeliewa and Muller-Stoll [Madel-Angeliewa, E., Muller-Stoll, W.R., 1973. Kritische Studien uber fossile Combretaceen-Holzer: fiber Holzer von Typus Terminalioxylon G. Schonfeld mit einer Revision der bisher zu Evodioxylon Chiarugi gestellten Arlen. Palaeontographica 14213, 117-136.] and T sulaimanense sp. nov. These fossils are close to modem species of Terminalia, which occur in moist deciduous or semi-evergreen tropical forests. The palynological assemblage is composed of a mixture of pollen and spore types from different origins. There is a dominance of hygrophilous ferns, pines, Amaranthaceae-Chenopodiaceae-Caryophylaceae, but also the occurrence of Palmae, which are typical of tropical rainforests. This assemblage suggests that the depositional system is set in a context of nearby mountains with a minimum altitude of 2000 to 2500 m and characterized by differentiated forest belts above the tropical lowland vegetation of lower elevations. Wood, pollen and spores support the view of a fluvial environment surrounded by a tropical forested habitat. The separate stratigraphic position of the pollen assemblage above the fossil wood could explain its slightly different, more varied, palaeoenvironmental signal.