Paleohydraulic reconstruction of a 40 ka‐old terrace sequence implies that water discharge was larger than today          下载免费PDF全文

Camille Litty  Robert Duller  Fritz Schlunegger 《地球表面变化过程与地形》2016,41(7):884-898

The evolution of landscapes crucially depends on the climate history. This is particularly evident in South America where landscape responses to orbital climate shifts have been well documented. However, while most studies have focused on inferring temperature variations from paleoclimate proxy data, estimates of water budget changes have been complicated because of a lack of adequate physical information. Here, we present a methodology and related results, which allowed us to extract water discharge values from the sedimentary record of the 40 Ka‐old fluvial terrace deposits in the Pisco valley, western Peru. In particular, this valley hosts a Quaternary cut‐and‐fill succession that we used, in combination with beryllium‐10 (¹⁰Be)‐based sediment flux, gauging records, channel geometries and grain size measurements, to quantitatively assess sediment and water discharge values c. 40 Ka ago in relation to present‐day conditions. We compare these discharge estimates to the discharge regime of the modern Pisco River and find that the water discharge of the paleo‐Pisco River, during the Minchin pluvial period c. 40 Ka ago, was c. 7–8 times greater than the modern Pisco River if considering the mean and the maximum water discharge. In addition, the calculations show that inferred water discharge estimates are mainly dependent on channel gradients and grain size values, and to a lesser extent on channel width measures. Finally, we found that the c. 40 Ka‐old Minchin terrace material was poorer sorted than the modern deposits, which might reflect that sediment transport during the past period was characterized by a larger divergence from equal mobility compared to the modern situation. In summary, the differences in grain size distribution and inferred water discharge estimates between the modern and the paleo‐Pisco River suggests that the 40 Ka‐old Minchin period was characterized by a wetter climate and more powerful flood events. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Environmental controls on 10Be‐based catchment‐averaged denudation rates along the western margin of the Peruvian Andes          下载免费PDF全文

Regina Reber  Romain Delunel  Fritz Schlunegger  Camille Litty  Andrea Madella  Naki Akçar  Marcus Christl 《地学学报》2017,29(5):282-293

We present ¹⁰Be‐based basin‐averaged denudation rates for the entire western margin of the Peruvian Andes. Denudation rates range from c. 9 mm ka^?1 to 190 mm ka^?1 and are related neither to the subduction of the Nazca plate nor to the current seismicity along the Pacific coast and the occurrence of raised Quaternary marine terraces. Therefore, we exclude a tectonic control on denudation on a millennial time‐scale. Instead, we explain >60% of the observed denudation rates with a model where erosion rates increase either with mean basin slope angles or with mean annual water discharge. These relationships suggest a strong environmental control on denudation.  相似文献   

Reliable Determination of Ge in Solid Environmental Samples Using a Chemical Preparation Procedure Developed for Si Isotopes and ICP‐MS Analysis          下载免费PDF全文

Camille Delvigne  Bernard Angeletti  Abel Guihou  Isabelle Basile‐Doelsch  Jean‐Dominique Meunier 《Geostandards and Geoanalytical Research》2018,42(1):139-149

Germanium (Ge) exists at trace levels in the Earth's crust and is a powerful geochemical tracer of the silicon (Si) cycle. This study proposes a simple and reliable method for determining Ge contents in environmental samples using ICP‐MS. As Si and Ge have very similar chemical properties, we investigated the applicability of the chemical preparation procedure developed for Si isotopes for the determination of Ge in environmental samples. Advantages of this procedure are as follows: (a) efficient removal of the matrix and main interferences affecting Ge determinations by ICP‐MS, (b) a low limit of detection (6 ng l^?1), (c) relative repeatability of approximately 3% obtained on ⁷⁴Ge and (d) robustness and accuracy based on agreement within errors with the published Ge values for rock reference materials (BHVO‐2, AGV‐2 and BCR‐2). This procedure allowed revision of the Ge values of three soil reference materials (1.67 ± 0.09 μg g^?1, 2.41 ± 0.18 μg g^?1, 1.89 ± 0.10 μg g^?1 for GBW 07401, GBW 07404 and GBW 07407, respectively) and proposal of a value for the plant reference material ERM‐CD281 (70 ± 3 μg g^?1). This method provides a convenient procedure for determining Ge mass fractions in environmental samples and opens the possibility of coupling two tracers of the Si biogeochemical cycle with a single measurement procedure.  相似文献   

Learning from environmental justice in Viet Village Versai in New Orleans     

Camille Tuason Mata 《GeoJournal》2012,77(2):249-264

This paper explores the attempt to plan and to implement pollution remediation projects in Viet Village Versai, New Orleans. The process was marred by gaps in collaboration behaviours between the stakeholders, which ultimately impeded the progress of the remediation projects and as a result, failed to transform the Viet Village Versai into a sustainable community. In drawing the link between the behavioural gaps and implementation failures, I bring attention to the crucial role that collaboration plays in helping to build sustainable communities.  相似文献