ON THE DISCOVERY OF A QUERCUS SEMICARPIFOLIA BED IN MOUNT SHISHA PANGMA AND ITS SIGNIFICANCE IN BOTANY AND GEOLOGY
HA JEN TAO JUN-RONG SUN XIANG-JUN (Institute of Botany,Academia Sinica)
Mount Shisha Pangma,one of the high peaks of the central Himalayas,is about 8,012 m in height above the sea level.At the foot of its northern slope,there is a series of grayish yellow sandstones.Its exposed thickness is about 1,000 m. In the lower part of this sandstone series,a plant-bearing bed was discovered,in which were preserved leaves of evergreen oaks,Quercus semicarpifolia Sm.,Qu.cf. pannosa Hand.-Mzt.and Qu.cf.senecens Hand.-Mzt.,and a leaf of Cyperaceae . Under palynological investigation,a large amount of pollen grains of Cedrus(mostly of C.deodara Loud.)and Quercus has been observed,counted about 59.1% and 72.2% of the sporo-pollen contents of the upper and lower parts respectively.Besides,pollen of Abies,Picea,Pinus,Tsuga,Betula,Ericaceae,Labiatae and Cyperaceae and spores of Pteris,Polypodium and Selaginella were also observed.The sporo-pollen assemblages of the upper and lower parts of this series are quite similar.Owing to the increment of the amount of Abies pollen and the appearance of pollen grains of Picea,Pinus and some shrubby and herbaceous plants and spore of Selaginella,the flora of the later stage is more complex than that of the earlier,and the floral development of the later stage is more close to that in temperate climate rather than in subtropical.Anyway, the vegetation of that time is,as a whole,mainly represented by evergreen oak and Cedrus forests.The climate then seems to be rather mild and rainy. The flora is more close to the late Pliocene flora of Northwestern Yunnan,the middle-late Pliocene flora of south-eastern Europe and the early Pleistocene flora of Kashmir.The floral development of the said flora is quite identical with that of the Pliocene flora of Ebene(Sofia)of Bulgaria and that of the middle Pliocene flora of Cantal,southern France.The geological age of the present sandstone series is not earlier than the middle-late Pliocene. The climate of the fossil locality at present is very severe.The altitude is 5,700— 5,900 m,above the sea level.Plants can no longer live even in mid-summer.Both the macro-and micro-plant fossils indicate that the climate then was rather warm and the altitude was only 2,500 m above the sea level.Evidently,Mt.Shisha Pangma has up- lifted about 3,000 m.since late Pliocene.