Response of meteoric δ18O to surface uplift — Implications for Cenozoic Andean Plateau growth

Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes

“…In contrast, δ 18 O and δD stream-water samples along transect 1 agree with other available studies of δ 18 O and δD located north of 22 • S, where the climate is generally more humid and the tropical atmosphere regime is characterized by lower storm frequencies (Fig. 6b) (Gonfiantini et al, 2001;Insel et al, 2012). In the region of transect 1, the temperature-lapse rate with elevation drives rainout and stable-isotope fractionation, but this is not the case south of 26 • S along transect 3, which is influenced by the extra-tropical atmospheric circulation regime and increased convection (Fig.…”

“…Our results demonstrate the need for sufficiently high resolution in these models to capture regional mesoscale convective cells, which would far more accurately reflect regional stable isotope values of precipitation. Otherwise, modeled δ 18 O and δD values will substantially deviate from observation data, a phenomenon observable for the region along our transect 3, which is characterized by highly convective rainfall (Insel et al, 2012).…”

Stable isotopes of surface water across the Longmenshan margin of the eastern Tibetan Plateau

“…Thus, these river water samples should reflect an approximation of mean annual precipitation [Fritz, 1981;Garzione et al, 2000;Quade et al, 2007;Rowley and Garzione, 2007] rather than individual precipitation events. A short observation period of modern isotopic lapse rates may not represent mean climatic conditions [Insel et al, 2012] O w values ranging between 28.8& at the foot of the Longmenshan, and 213.5& at the highest elevation sites in the headwaters near the Gonggangling (Figures 2a and 3). The dD w values range between 254.6 and 294.3& (Figures 2a and 3 and Table 2).…”

“…The Zoige Basin is located on the eastern Tibetan Plateau, near the Longmenshan (Figure 1a) with an altitude of 3300-3600 m. Today, the Zoige Basin straddles the transition zone between the Asian monsoons and westerlies domains with a mean annual precipitation of 700 mm/yr and an average summer temperature of 1. The isotope-elevation relationships presented here may only be applied to predict altitudes lower than 4000 m. Paleoclimate patterns, temperature, moisture source, and oceanic water evolution must be examined and corrected before applying models for paleoelevation reconstruction to the past [e.g., Garzione et al, 2000;Rowley and Currie, 2006;DeCelles et al, 2007;Hren et al, 2009;Bershaw et al, 2012;Insel et al, 2012]. For example, without a paleotemperature correction, the reconstructed paleoelevations for the Zoige Basin would be consistently 600 m higher than the modern elevation.…”

The last deglaciation of Peru and Bolivia

“…The physiography of the Andes varies from N-S through Peru and Bolivia, assuming a series of parallel ridges getting successively wider, and ending in Southern Bolivia amidst the Altiplano proper. The uplift history is also complicated in detail but has an overall framework that is recognized, featuring continual movement of orogenic mass into the cryosphere , and with no more than 50% of the elevation attained by 10 Ma (Gregory-Wodzicki, 2000;Insel et al, 2012). This uplift history has long imprinted strongly on the resulting precipitation patterns of the region, with a distinctive rain shadow in place by 15 Ma, reinforced by subsequent orographic development (Hartley, 2003).…”