Structurally bonded water in sediment soil samples from the Atacama Desert, Chile
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| Title: | Main Title: Structurally bonded water in sediment soil samples from the Atacama Desert, Chile |
| Description: | Abstract: In the hyperarid core of the Atacama Desert soil waters consist mainly of structurally bonded water of hydrated minerals such as gypsum (CaSO4 · 2H2O). Their oxygen and hydrogen isotopic composition may yield information about hydrological processes, water sources and possibly (paleo-)humidity. We have investigated sediment samples from two depth profiles (Yungay: 24°6’6.1”S 70°1’5.8”W; Pisagua: 19°36’27.4”S 70°6’9.9”W) and an altitudinal transect along an alluvial fan (Quebrada Aroma). The samples were characterized in terms of their mineral composition by XRD. Water extracted from those samples was analyzed by dual-inlet IRMS (δ18O, δ17O) and continuous flow (δ18O, δD). Studied samples represent mixtures of two different mineral suites. The silicate suite (quartz, feldspars, muscovite) is probably derived from local weathering of Andean bedrock, while the salt suite (mainly gypsum, anhydrite, halite and nitratite) originates from aeolian redeposition of material from salars and local soil evaporation as well as – when preserved – atmospheric deposition. Samples from the alluvial fan surface are dominated by minerals from the silicate suite, while samples from the soil profiles contain various proportions from both suites. The isotopic signatures of the extracted waters seem to represent mixtures of adsorbed water and structurally bonded water in gypsum with a possible contribution from water adsorbed onto clays. δ18O and δD mostly represent heavy evaporitic waters. Back extrapolation to the MWL gives δ18O between -15 and -30‰ and δD between -100 and -200‰, which indicate light atmospheric water sources rather than local meteoric waters. Several water samples especially from the deeper parts of the soil profiles comprise strongly elevated 17O-excess values. These represent most likely mass-independent signatures. Pending further tests, these could indicate either an atmospheric origin of the extracted water – and thus the gypsum – or derive from interaction between soil moisture and present nitrates known to carry a mass-independent signature. |
Responsible Party
| Creators: | Claudia Voigt (Author), Daniel Herwartz (Author), Michael Staubwasser (Author) |
| Funding Reference: | Deutsche Forschungsgemeinschaft (DFG): CRC 1211: Earth - Evolution at the Dry Limit |
| Publisher: | CRC1211 Database (CRC1211DB) |
| Publication Year: | 2018 |
Topic
| CRC1211 Topic: | Climate |
| Related Subproject: | D3 |
| Subjects: | Keywords: Stable Isotope Geochemistry, Paleoclimate Proxies |
File Details
| Filename: | 2017_Goldschmidt_poster.pdf |
| Data Type: | Text - Text |
| File Size: | 10.1 MB |
| Date: | Issued: 15.08.2017 |
| Mime Type: | application/pdf |
| Data Format: | |
| Language: | English |
| Status: | Completed |
Constraints
| Download Permission: | Only Project Members |
| General Access and Use Conditions: | According to the CRC1211DB data policy agreement. |
| Access Limitations: | According to the CRC1211DB data policy agreement. |
| Licence: | [CRC1211DB] Data policy agreement |
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Specific Information - Presentation
| Presentation Date: | 15th of August, 2017 |
| Presentation Type: | Poster |
| Event: | Goldschmidt Conference |
| Event Type: | Conference |
| Event Location: | Paris, France |
| Event Duration: | 13th of August, 2017 - 18th of August, 2017 |
| Event Website: | https://goldschmidt.info/2017/ |
Metadata Details
| Metadata Creator: | Claudia Voigt |
| Metadata Created: | 26.01.2018 |
| Metadata Last Updated: | 26.01.2018 |
| Subproject: | D3 |
| Funding Phase: | 1 |
| Metadata Language: | English |
| Metadata Version: | V50 |
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| Page Visits: | 273 |
| Metadata Downloads: | 0 |
| Dataset Downloads: | 7 |
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