青藏高原东缘表土正构烷烃δD高度效应及其分馏值的高程变化

发布时间：2018-12-26 12:29

【摘要】：稳定同位素高度计极大地促进了全球较大山体隆升历史的研究,然而,古土壤氢氧同位素古高度计获得的古高度结果一般比通过古生物化石获得的要高得多.因此,需要在不同地区深入评估其现代高度关系及其影响因素,借此探讨稳定同位素古高度重建方法的校正.本研究测定了青藏高原东部东亚季风区龙门山29个表土叶蜡正构烷烃氢同位素值(δD_(wax))、22个土壤水氢同位素值(δD_(sw)),以及贡嘎山47个河水氢同位素值(δD_(rw))、55个泉水的氢同位素值(δD_(springw))和2个水文观测站的夏季降水氢同位素值(δD_(p)).龙门山断面表土δD_(wax)值分布在.160~.219‰(其δD_(wax)高程递减率为.18‰km.1(R2=0.83;p0.0001;n=29),比贡嘎山断面整体上偏正约40‰.气候和水汽来源的区域差异性可能导致了两个地区δD_(rw)值、表土δD_(wax)和ε_(wax)/p值的不同.另外,本研究发现两个断面表土δD_(wax)相对δD_(rw)、δD_(p)和δD_(sw)的分馏值(ε_(wax)/_(rw)、ε_(wax)/p和ε_(wax)/_(sw))整体上随海拔高度的升高而增加(两个断面分别高达34‰和50‰).通过这两个高程断面的表土δD_(wax)、δD_(p)、δD_(rw)(δD_(springw))和δD_(sw)的对比研究,讨论了水汽再循环、冰川融水、蒸散发、植被类型、纬度和山形等因素对ε_(wax)/p值随高程变化的综合影响.因此,在估算高海拔处的古高度时,如果仍然参考有些低海拔处估算的植物的ε_(wax)/p值,那么,以此推导的古降水δD_(p)偏负于实际值,因而高估古高度.
[Abstract]:The stable isotope altimeter has greatly promoted the study of the uplift history of the world's larger mountain bodies. However, the paleoheight obtained by the paleosol hydrogen and oxygen isotopic altimeters is generally much higher than that obtained by paleontological fossils. Therefore, it is necessary to evaluate the modern height relationship and its influencing factors in different regions, so as to discuss the correction of the reconstruction method of stable isotopic paleoheight. The hydrogen isotope values of normal alkanes (未 D _ (wax),) in 29 topsoil of Longmen Mountain in East Asian monsoon region of the eastern Qinghai-Xizang Plateau (未 D _ (wax), 22) have been determined. The hydrogen isotope values (未 D _ (springw) of 47 river water (未 D _ (rw),) and summer precipitation hydrogen isotopic values (未 D _ (p).) of 45 springs in Gongga Mountain are also given. The 未 D _ (wax) value of the surface soil of Longmen Mountain section is distributed in the range of .160 ~ 0.219 鈥，

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