关键词: 腊玛与西瓦古猿;古气候

Abstract: This paper deals with the reeostruetion of the late Miocene paleoelimate by meaus of sedimentary analyses of the stratum containing Ramapithecus fossils. The analyses include: differential thermal analysis, X-ray diffraction, heavy mineral content, pH value, organic substances, sporo-pollens and identification of aquatie plant maero-fossils.
The paleoclimate of the late Miocene gradually changed along with the uplifting of the highlands of Qinghai-Xizang (Tibet) and the Hengduan mountains. The geological section containing Ramapithecus fossils can be divided into five different depositional stages, from bottom to top:
The first stage— (the First Member of Shihuiba Formayion) The climate in this stage is drier and cooler than in the second one.
The second stage- (the Second Member of Shihuiba Formation) The climate is charaterized by a warm and wet perind.
The third stage—includes the early deposits of deep lacustrine and lacustrine-swamp environments in the basin. It indicates a hot, wet elimatic character, typical of the South Asian tropical zone.
The fourth stage—repersents the later lacustrine-swamp deposits of the middle and upper parts of the basin. The climate during this stage is different from that of the first—It indicates a climate that alternates between wet and dry and hot and wet. It demonstrates the periodie return of wet and dry eonditions, and is similar to that of the Sino-India tropical monsoon climate of South Asia. This climatic change is pro- bobly related to the uplifting of the Qinghai-Xizang (Tibet) plateau and the orogeny which produced the Himalayas and the Hengduan mountains.
The fifth stage includes the deposits of shallow lakes or rivers above the erosional surface in the geological section bearing Ranapithecus fossils. Here, substantial climatic change is indieated. Following the uplifting of the Qinghai-Xizang (Tibet) plateau, the Lufeng lacustrine-swamp environment faded away, and a very dry elimate is suggested. Finally one withesses the return of a rather warm and wet sub-tropical climate.

Key words: Ramapithecus and Sivapithecus; Paleoclimate