新疆沙尔湖中侏罗世狭叶拟刺葵（Phoenicopsis angustifolia Heer）的古环境意义

新疆沙尔湖煤田中侏罗统西山窑组产出大量茨康类植物化石.通过选取4块狭叶拟刺葵Phoenicopsis angustifolia Heer化石作为研究对象，在详细揭示其角质层微细构造、统计气孔参数并测定其碳同位素组成的基础上，定量重建研究区中侏罗世早期阿林期至巴柔期古大气CO₂浓度、古温度、古海拔高度，测算该植物的水分利用率.结果表明，狭叶拟刺葵平均气孔指数值5.90%，基于气孔比率法获得的古大气CO₂浓度为（1240.16±122.75）×10-6，该值处于GEOCARB Ⅲ碳平衡模型可信误差范围内.测得植物化石角质层碳同位素δ13C_p平均值-23.07‰，计算出该植物水分利用效率272.06 mmol/mol，重建沙尔湖中侏罗世早期平均温度16.8~20.7℃，古海拔高度196.7 m.整体而言，新疆沙尔湖地区在中侏罗世早期属于一种高CO₂浓度、气候温暖湿润的环境. 

Paleoenvironmental Implications of the Middle Jurassic Phoenicopsis angustifolia Heer in Shaerhu,Xinjiang

The Middle Jurassic Xinshanyao Formation yields abundant and diverse fossil Ginkgophytes in the Shaerhu Coalfield of Xinjiang, NW China. Four leaf compression fossil of Phoenicopsis angustifolia Heer were selected from this horizon for calculating the epidermal stomatal parameters and their isotope carbon composition of leaf cuticles. On this basis, the Middle Jurassic （Aalenian-Bajocian） paleo-atmospheric CO₂ concentration, paleo-temperature, and paleo-altitude of Shaerhu region of were tentatively reconstructed. Additionally, the water use efficiency of the current Ph. angustifolia was also calculated. The results show that the average stomatal index （SI） of Phoenicopsis angustifolia Heer is 5.90%. The paleo-atmospheric CO₂ concentration obtained by the stomatal ratio method is （1 240.16±122.75）×10-6, which is within the credible error range of the GEOCARB Ⅲ. The average value of the stable carbon isotope δ13C_p of plant fossils is -23.07‰, and its water use efficiency （WUE） is calculated to be 272.06 mmol/mol. The paleo-average temperature of Shaerhu is about 16.8~20.7℃, the paleo-altitude is 196.7 m, which generally reflects Shaerhu Coalfield was a kind of environment with high CO₂ concentration, warm and humid climate in the early Middle Jurassic.