以雅鲁藏布大峡谷的羚牛为主要研究对象,讨论其牙齿珐琅质羟基磷灰石结构碳酸盐的碳、氧同位素组成与生活环境之间的关系。羚牛牙齿的碳同位素组成分布范围相当宽,且随着栖息地海拔高度的增加而变重,反映了食谱中C4植物从无到有、由少到多的变化趋势。C4植物含量最高可能达到70％。这一变化与当地自然带的划分相吻合。羚牛牙齿珐琅质结构碳酸盐的δ18O值分布范围较窄,与海拔高度之间没有明显的相关性。氧同位素分馏可能与水源和物种均有关。
This paper addresses the δ13C, δ18O values and paleoenvironmental significance of modern Asian takins(Budorcas taxicolor), yaks and cattle-yaks tooth enamel from the Yarlung Zangbo Grand Canyon, and tooth enamel of modern reindeers (Rangifer tarandus) from Svalbard, the Arctic.The Yarlung Zangbo Grand Canyon has a length of about 496.3 km and cuts its way through the eastern Himalayas.Its climate ranges from subtropical to arctic.The takin (Budorcas taxicolor) is a large ungulate belongjing to the Bovidae.There are four subspecies:B.taxicolor taxicolor, B.taxicolor bedfordi, B.taxicolor tibetana and B.taxicolor whitei.B.taxicolor taxicolor is found in the eastern Himalayas, such as the Yarlung Zangbo Grand Canyon.Stable carbon and oxygen isotopic composition of tooth enamel has been established as a valuable tool for reconstructing paleoenvironment.In this paper, tooth enamel samples were obtained from modern Asian takins, yaks, cattle-yaks and reindeers for C and O isotope analysis.δ13C values of takin tooth enamel range from -19.3‰ to -2.2‰.The takins living at an altitude of 1300 m have δ13C values ranging from -19.3‰ to -18.9‰, with an average δ13C value of -19.1‰;δ13C value of takins living at an altitude of 1700 m is -10.7‰;δ13C values of takins living at an altitude of 1830 m are from -10.7‰ to -10.3‰, with an average δ13C value of -10.5‰;takins living at an altitude of 3000 m have δ13C values of -4.6‰ to -2.2‰, with an average δ13C value of -3.4‰.There is a direct correlation between δ13C values of takin tooth enamel and the altitude, a higher altitude equaling a higher δ13C value.This could be due to an association with C4 plants.Higher δ13C values such as -3.4‰ could suggest consumption of large amounts of C4 plants by the animals.It is more likely attributed to the abundance of C4 plants in this area.The lower enamel δ13C values such as -19.1‰ indicate that the takins were feeding predominantly on C3 plants, consistent with the dominance of C3 plant in the lower elevation.δ13C values of reindeers live in Svalbard are -20.2‰ to -17.8‰, with an average δ13C value of -19.0‰, in conformity with the absence of C4 plant in the Arctic.The yak teeth have δ13C values ranging from -15.0‰ to -8.7‰.Cattle-yaks have δ13C values of -12.5‰ and -9.3‰.Maybe these domestic animals were feed with some artificial diet.δ18O values of takin tooth enamel range from -9.8‰ to -5.7‰.The takins live at an altitude of 1300 m, 1700 m, 1830 m and 3000 meters have average δ18O values of -8.1‰, -5.7‰, -6.7‰ and -6.8‰, respectively.The δ18O values of takin tooth enamel do not show a trend with increasing elevation.Average δ18O values of yak tooth enamel are -11.7‰ and -13.6‰.Average δ18O value of cattle-yak tooth enamel is -5.3‰.There are variations among the different species.
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