CAJ | 학술논문

新疆吐哈盆地北缘中侏罗世早期的三道岭植物群中包含大量的银杏类和茨康类植物,从银杏类中选择一种似银杏属植物(似银杏(未定种)),同时从茨康类中选择两种拟刺葵属植物(华丽拟刺葵和狭叶拟刺葵)分析角质层特征,获取3种植物的气孔参数值.似银杏属的气孔指数为4.1%,而华丽拟刺葵和狭叶拟刺葵的气孔指数非常接近,分别为4.8%,4.7%.利用似银杏属和拟刺葵属植物的气孔指数(平均值分别为4.10%,4.75%)开展气孔指数法和气孔比率法重建新疆吐哈盆地中侏罗世早期的古大气CO2体积分数.气孔指数法获得的CO2体积分数分别为4.510×10-3,3.523×10-3,均落在GEOCARBⅢ可信误差范围之外.气孔比率法重建的CO2体积分数分别为1.770×10-3,1.530×10-3,处于GEOCARB Ⅲ可信误差范围之内,说明对于恢复侏罗纪的CO2体积分数而言,气孔比率法比气孔指数法更加可靠.比较气孔比率法获得的两个CO2体积分数,发现1.770×10-3比1.530×10-3更接近GEOCARBⅢ的最佳拟合线,表明银杏类植物化石获得的古大气CO2体积分数更加准确.最后,确定出新疆吐哈盆地中侏罗世阿连期到巴柔期的CO2体积分数为1.770×10-3.
신강토합분지북연중주라세조기적삼도령식물군중포함대량적은행류화자강류식물,종은행류중선택일충사은행속식물(사은행(미정충)),동시종자강류중선택량충의자규속식물(화려의자규화협협의자규)분석각질층특정,획취3충식물적기공삼수치.사은행속적기공지수위4.1%,이화려의자규화협협의자규적기공지수비상접근,분별위4.8%,4.7%.이용사은행속화의자규속식물적기공지수(평균치분별위4.10%,4.75%)개전기공지수법화기공비솔법중건신강토합분지중주라세조기적고대기CO2체적분수.기공지수법획득적CO2체적분수분별위4.510×10-3,3.523×10-3,균락재GEOCARBⅢ가신오차범위지외.기공비솔법중건적CO2체적분수분별위1.770×10-3,1.530×10-3,처우GEOCARB Ⅲ가신오차범위지내,설명대우회복주라기적CO2체적분수이언,기공비솔법비기공지수법경가가고.비교기공비솔법획득적량개CO2체적분수,발현1.770×10-3비1.530×10-3경접근GEOCARBⅢ적최가의합선,표명은행류식물화석획득적고대기CO2체적분수경가준학.최후,학정출신강토합분지중주라세아련기도파유기적CO2체적분수위1.770×10-3.
Ginkgoales and Czekanowskiales were dominant among middle jurassic Sandaoling flora on the northern margin of Turpan-Hami Basin, Xinjiang. Here, one species of Ginkgoites identified as Ginkgoites sp. was selected from Ginkgoales. Simultaneously, two species of Phoenicopsis identified as Phoenicopsis angustifoli a Samylina and Phoenicopsis speciosa Heer were selected from Czekanowskiales. The stomatal parameters of these three fossil leaves were obtained through a cuticular analysis. The stomatal index value of Ginkgoites sp. was 4.1%, while SI were similar between Phoenicopsis speciosa and Phoenicopsis angustifolia, which were 4.8%and 4.7%. The two methods of stomatal index and stomatal ratio wereperformed to reconstruct paleoatmospheric CO2 levels of early middle jurassic Turpan-Hami Basin based on the average SI values of Ginkgoites and Phoenicopsis, which were 4.10% and 4.75%, respectively. Accordingly, paleo-CO2 levels were reconstructed as 4.510×10-3 and 3.523×10-3 , respectively, by the stomatal index method, which was out of the error range of CO2 confidence from GEOCARB Ⅲ. However, the values of paleo-CO2 were obtained as 1.770×10-3 and 1.530×10-3 , respectively, by using the method of stomatal ratio, which was plotted within the error range of CO2 confidence. The two results indicated that the stomatal index method is more reliable than the stomatal ratio method in reconstructing jurassic CO2 concentration. For the two paleo-CO2 values obtained from stomatal ratio method, 1.770×10-3 reconstructed from Ginkgoites is more adjacent to the optimum line of GEOCARBⅢthan 1.530×10-3 reconstructed from Phoenicopsis, suggesting that paleo-CO2 level reconstructed from Ginkgoales fossils is more precise. As a result, the paleoatmospheric CO2 level of Turpan-Hami Basin from Aalenian to Bajocian in the middle jurassic is ascertained to be 1.770×10-3.