Stable isotope variations (δ18O and δD) in modern waters across the Andean Plateau

Abstract

28Environmental parameters that influence the isotopic composition of meteoric water (δ 18 O and δD) are 29 well characterized up the windward side of mountains, where orographic precipitation results in a 30 predictable relationship between the isotopic composition of precipitation and elevation. The topographic 31 and climatic evolution of the Andean Plateau and surrounding regions has been studied extensively by 32 exploiting this relationship through the use of paleowater proxies. However, interpretation on the plateau 33 itself is challenged by a poor understanding of processes that fractionate isotopes during vapor transport 34 and rainout, and by the relative contribution of unique moisture sources. Here, we present an extensive 35 dataset of modern surface water samples for the northern Andean Plateau and surrounding regions to 36 elucidate patterns and causes of isotope fractionation in this continental environment. These data show a 37 progressive increase in δ 18

Controls on Deuterium Excess across Asia

“…For example, north of the Tibetan Plateau in the Tarim Basin, d-excess values of precipitation are <10‰ (Figure 1), likely due to enhanced subcloud evaporation of raindrops in this arid region [21]. This is consistent with low d-excess values of precipitation due to subcloud evaporation in the rain shadow of the Eastern Cordillera of South America, on the arid Andean Plateau [22].…”

“…On the southern flank of the Tian Shan in the northern Tarim Basin (not shown in Figure 5), subcloud evaporation of raindrops was shown to average as much as 40%, resulting in a~40‰ decrease in d-excess [21]. A similar trend is observed in precipitation samples down the western flank of the Andean Plateau into the hyperarid Atacama Desert of northern Chile [22,41].…”

Identifying evaporation fractionation and streamflow components based on stable isotopes in the Kaidu River Basin with mountain–oasis system in north‐west China

“…However, the altitude effect was not significant (Figure ). This was very similar to other glacial rivers, including the Urumqi River on the northern slope of the Tienshans (Sun, Chen, Li, Li, & Yang, ), the Akesu River on the southern slope of the Tienshans (Sun, Chen, Li, & Li, ), the Heihe River in the Qilian Mountains (Li et al, ), and rivers in the Andean Plateau (Bershaw, Saylor, Garzione, Leier, & Sundell, ). The Kaidu River flows through the Little Youerdusi Basin and the Big Youerdusi Basin.…”

Spatial and temporal variability of stable isotopes (δ18O and δ2H) in surface waters of arid, mountainous Central Asia

“…In contrast, the leeward side is generally affected by dry air masses and higher isotopic values in modern water (Huyghe et al, ; Quade, Breecker, Daëron, & Eiler, ). The large deviation from Rayleigh distillation isotopic patterns is also observed in the TP and Asian interior, resulting in large uncertainties in paleoaltitude reconstructions (Bershaw, Saylor, Garzione, Leier, & Sundell, ; Li & Garzione, ; Mulch, ). Future field observations of both δ 18 O and δ 2 H in event‐based precipitation across Kyrgyzstan are necessary to integrate numerical simulation efforts with stable isotope‐based paleoaltimetry.…”

“…(Huyghe et al, 2018;Quade, Breecker, Daëron, & Eiler, 2011). The large deviation from Rayleigh distillation isotopic patterns is also observed in the TP and Asian interior, resulting in large uncertainties in paleoaltitude reconstructions (Bershaw, Saylor, Garzione, Leier, & Sundell, 2016;Li & Garzione, 2017;Mulch, 2016).…”