TY  - JOUR
A1  - Sachse, Dirk
A1  - Billault, Isabelle
A1  - Bowen, Gabriel J.
A1  - Chikaraishi, Yoshito
A1  - Dawson, Todd E.
A1  - Feakins, Sarah J.
A1  - Freeman, Katherine H.
A1  - Magill, Clayton R.
A1  - McInerney, Francesca A.
A1  - van der Meer, Marcel T. J.
A1  - Polissar, Pratigya
A1  - Robins, Richard J.
A1  - Sachs, Julian P.
A1  - Schmidt, Hanns-Ludwig
A1  - Sessions, Alex L.
A1  - White, James W. C.
A1  - West, Jason B.
A1  - Kahmen, Ansgar
ED  - Jeanloz, R
T1  - Molecular Paleohydrology interpreting the Hydrogen- Isotopic Composition of Lipid Biomarkers from Photosynthesizing Organisms
JF  - Annual review of earth and planetary sciences
JF  - Annual Review of Earth and Planetary Sciences
N2  - Hydrogen-isotopic abundances of lipid biomarkers are emerging as important proxies in the study of ancient environments and ecosystems. A decade ago, pioneering studies made use of new analytical methods and demonstrated that the hydrogen-isotopic composition of individual lipids from aquatic and terrestrial organisms can be related to the composition of their growth (i.e., environmental) water. Subsequently, compound-specific deuterium/hydrogen (D/H) ratios of sedimentary biomarkers have been increasingly used as paleohydrological proxies over a range of geological timescales. Isotopic fractionation observed between hydrogen in environmental water and hydrogen in lipids, however, is sensitive to biochemical, physiological, and environmental influences on the composition of hydrogen available for biosynthesis in cells. Here we review the factors and processes that are known to influence the hydrogen-isotopic compositions of lipids-especially n-alkanes-from photosynthesizing organisms, and we provide a framework for interpreting their D/H ratios from ancient sediments and identify future research opportunities.
KW  - paleoclimate
KW  - paleoclimate proxy
KW  - deuterium
KW  - organic geochemistry
Y1  - 2012
SN  - 978-0-8243-2040-9
U6  - https://doi.org/10.1146/annurev-earth-042711-105535
SN  - 0084-6597
VL  - 40
IS  - 1
SP  - 221
EP  - 249
PB  - Annual Reviews
CY  - Palo Alto
ER  - 
TY  - JOUR
A1  - Bookhagen, Bodo
A1  - Strecker, Manfred
T1  - Spatiotemporal trends in erosion rates across a pronounced rainfall gradient: Examples from the southern Central Andes
JF  - Earth & planetary science letters
N2  - The tectonic and climatic boundary conditions of the broken foreland and the orogen interior of the southern Central Andes of northwestern Argentina cause strong contrasts in elevation, rainfall, and surface-process regimes. The climatic gradient in this region ranges from the wet, windward eastern flanks (similar to 2 m/yr rainfall) to progressively drier western basins and ranges (similar to 0.1 m/yr) bordering the arid Altiplano-Puna Plateau. In this study, we analyze the impact of spatiotemporal climatic gradients on surface erosion: First, we present 41 new catchment-mean erosion rates derived from cosmogenic nuclide inventories to document spatial erosion patterns. Second, we re-evaluate paleoclimatic records from the Calchaquies basin (66 W, 26 S), a large intermontane basin bordered by high (> 4.5 km) mountain ranges, to demonstrate temporal variations in erosion rates associated with changing climatic boundary conditions during the late Pleistocene and Holocene. Three key observations in this region emphasize the importance of climatic parameters on the efficiency of surface processes in space and time: (1) First-order spatial patterns of erosion rates can be explained by a simple specific stream power (SSP) approach. We explicitly account for discharge by routing high-resolution, satellite derived rainfall. This is important as the steep climatic gradient results in a highly non-linear relation between drainage area and discharge. This relation indicates that erosion rates (ER) scale with ER similar to SSP1.4 on cosmogenic-nuclide time scales. (2) We identify an intrinsic channel-slope behavior in different climatic compartments. Channel slopes in dry areas (< 0.25 m/yr rainfall) are slightly steeper than in wet areas (> 0.75 m/yr) with equal drainage areas, thus compensating lower amounts of discharge with steeper slopes. (3) Erosion rates can vary by an order of magnitude between presently dry (similar to 0.05 mm/yr) and well-defined late Pleistocene humid (similar to 0.5 mm/yr) conditions within an intemontane basin. Overall, we document a strong climatic impact on erosion rates and channel slopes. We suggest that rainfall reaching areas with steeper channel slopes in the orogen interior during wetter climate periods results in intensified sediment mass transport, which is primarily responsible for maintaining the balance between surface uplift, erosion, sediment routing and transient storage in the orogen.
KW  - erosion
KW  - landscape evolution
KW  - specific stream power
KW  - cosmogenic radionuclides
KW  - paleoclimate
KW  - climate-tectonic feedback processes
Y1  - 2012
U6  - https://doi.org/10.1016/j.epsl.2012.02.005
SN  - 0012-821X
VL  - 327
IS  - 8
SP  - 97
EP  - 110
PB  - Elsevier
CY  - Amsterdam
ER  -