Assessment of soil <i>n</i>-alkane δ<i>D</i> and branched tetraether membrane lipid distributions as tools for paleoelevation reconstruction

Abstract

Abstract. δ 18 O values of pedogenic minerals forming from soil water are commonly used to reconstruct paleoelevation. To circumvent some of the disadvantages of this method, soil n-alkane δD values were recently proposed as a new tool to reconstruct elevation changes, after showing that soil nalkane δD values track the altitude effect on precipitation δD variations (r 2 =0.73 along Mt. Gongga, China). To verify the suitability of soil n-alkane δD values as a paleoelevation proxy we measured the δD of soil n-alkanes along Mt. Kilimanjaro (Tanzania). At midslope, soil n-alkane δD values are possibly influenced by the present precipitation belt, causing D-depletion in precipitation, and hence in the soil n-alkanes. Consequently, soil n-alkane δD values do not linearly relate with altitude (r 2 =0.03), suggesting that, in this case, they can not serve as an unambiguous proxy to infer past elevation changes. In contrast, it was recently shown that the MBT/CBT temperature proxy, which is based on the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids, is linearly related with MAT, and thus altitude (r 2 =0.77), at Mt. Kilimanjaro. This suggests that this proxy may be more suitable for paleoelevation reconstruction for this region. However, application of the MBT/CBT proxy on the altitude gradient along Mt. Gongga showed that, although the MBT/CBT-derived temperature lapse rate (−5.9 • C/1000 m) resembles the measured temperature lapse rate (−6.0 • C/1000 m), there is a relatively large degree of scatter (r 2 =0.55). Our results thus show that both Correspondence to: F. Peterse (francien.peterse@nioz.nl) proxies can be subject to relatively large uncertainties in their assessment of past elevation changes, but that a combination of the soil n-alkane δD and MBT/CBT proxies can likely result in a more reliable assessment of paleoelevation.

Tracing tetraether lipids from source to sink in the Rhône River system (NW Mediterranean)

“…In the Fiesch soil transect in the upper Rhône River basin (1188-2848 m altitude, -2.8 to 6.5 • C MAAT, and 1203-2085 mm MAP), we also did not observe a positive relationship between the CL MBT' and MAAT ( Figure 8D). Hence, it is not surprising that the Fiesch transect dataset also showed no altitudinal trend of the reconstructed MAAT (data not shown) in contrast to other similar studies (e.g., Sinninghe Damsté et al, 2008;Peterse et al, 2009b;Ernst et al, 2013;Coffinet et al, 2014). We do not understand why the Fiesch transect data are different to other altitudinal transect data for the moment.…”

Paleoaltimetry Potentiality of Branched GDGTs From Southern Tibet

“…Jianfengling in southern China and Mts. This correlation has also been observed on the southeastern TP (Deng et al, 2016;Peterse et al, 2009) and in southwestern China (Wang et al, 2017). This correlation has also been observed on the southeastern TP (Deng et al, 2016;Peterse et al, 2009) and in southwestern China (Wang et al, 2017).…”

“…As also seen on a global scale, substantial scatter has been observed at a regional/local scale, including for calibrations based on the abovementioned altitudinal transects (R 2 5 0.55 and R 2 5 0.28, from Peterse et al, 2009 andZhuang et al, 2015, respectively). Some of this scatter appears to be due to other factors such as pH, aridity, length of growing season, soil type, and topography (Davtian et al, 2016;Nieto-Moreno et al, 2016;Peterse et al, 2012;Sinninghe Damst e et al, 2008;Wang et al, 2017).…”

“…(Sun et al, 2011) TEX 86 Regional lake (Pearson et al, 2011;Zink et al, 2010) Geochemistry, Geophysics, Geosystems (Dang et al, 2016;Yang et al, 2015aYang et al, , 2015b. Thus, 6-methyl brGDGTs may affect the altitudinal effect of the MBT/CBT-derived temperature and cause the large scatter seen in MBT 0 or MBT 0 /CBT-MAT estimates (Deng et al, 2016;Peterse et al, 2009;Yang et al, 2015a). Shennongjia, China (Yang et al, 2015b).…”

“…Contrary to the classic MBT 0 index, MBT 0 5ME indices appear well correlated with MAT/altitude at Mt. With specific reference to the TP, 6-methyl brGDGTs have not been separated and evaluated with reference to soil pH in regional calibrations between brGDGT distribution and MAT/altitude for TP (Deng et al, 2016;Liu et al, 2013;Peterse et al, 2009). Thus, 6-methyl brGDGTs may affect the altitudinal effect of the MBT/CBT-derived temperature and cause the large scatter seen in MBT 0 or MBT 0 /CBT-MAT estimates (Deng et al, 2016;Peterse et al, 2009;Yang et al, 2015a).…”