| 1. |
- Deegan, Frances, et al.
(författare)
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Driving Global Change One LIP at a Time
- 2023
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Ingår i: Elements. - : Mineralogical Society of America. - 1811-5209 .- 1811-5217. ; 19:5, s. 269-275
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Tidskriftsartikel (refereegranskat)abstract
- Earth's history has been punctuated by extraordinary magmatic events that produced large igneous provinces (LIPs). Many LIPs induced global changes, including millennial-scale warming, terrestrial and oceanic mass extinctions, oceanic anoxic events, and even glaciations. Research over the past 20 years has shown that shallow crustal degassing is an important factor contributing to the environmental impact of LIPs. Contact metamorphism in sedimentary basins can generate huge gas volumes, and operates as a function of magma volume and the architecture of LIP plumbing systems. Numerous open questions remain concerning the role of LIPs in triggering rapid and lasting changes, whose answers require collaboration across geoscientific disciplines. In this issue, we present the status of five key research themes and discuss potential ways forward to better understanding these large-scale phenomena.
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| 2. |
- Downs, Robert T.
(författare)
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Determining Mineralogy on Mars with the CheMin X-Ray Diffractometer
- 2015
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Ingår i: Elements. - : Mineralogical Society of America. - 1811-5209 .- 1811-5217. ; 11:1, s. 45-50
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Tidskriftsartikel (refereegranskat)abstract
- The rover Curiosity is conducting X-ray diffraction experiments on the surface of Mars using the CheMin instrument. The analyses enable identification of the major and minor minerals, providing insight into the conditions under which the samples were formed or altered and, in turn, into past habitable environments on Mars. The CheMin instrument was developed over a twenty-year period, mainly through the efforts of scientists and engineers from NASA and DOE. Results from the first four experiments, at the Rocknest, John Klein, Cumberland, and Windjana sites, have been received and interpreted. The observed mineral assemblages are consistent with an environment hospitable to Earth-like life, if it existed on Mars.
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| 3. |
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| 4. |
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| 5. |
- Gellert, R., et al.
(författare)
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In Situ Compositional Measurements of Rocks and Soils with the Alpha Particle X-ray Spectrometer on NASA's Mars Rovers
- 2015
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Ingår i: Elements. - : Mineralogical Society of America. - 1811-5209 .- 1811-5217. ; 11:1, s. 39-44
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Tidskriftsartikel (refereegranskat)abstract
- The Alpha Particle X-ray Spectrometer (APXS) is a soda can–sized, arm-mounted instrument that measures the chemical composition of rocks and soils using X-ray spectroscopy. It has been part of the science payload of the four rovers that NASA has landed on Mars. It uses 244Cm sources for a combination of PIXE and XRF to quantify 16 elements. So far, about 700 Martian samples from about 50 km of combined traverses at the four landing sites have been documented. The compositions encountered range from unaltered basaltic rocks and extensive salty sandstones to nearly pure hydrated ferric sulfates and silica-rich subsurface soils. The APXS is used for geochemical reconnaissance, identification of rock and soil types, and sample triage. It provides crucial constraints for use with the mineralogical instruments. The APXS data set allows the four landing sites to be compared with each other and with Martian meteorites, and it provides ground truth measurements for comparison with orbital observations.
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| 6. |
- Grady, Moniqa M, et al.
(författare)
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The Rosetta mission and the chemistry of organic species in comet 67P/Churyumov-Gerasimenko
- 2018
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Ingår i: Elements. - : Mineralogical Society of America. - 1811-5209 .- 1811-5217. ; 14:2, s. 95-100
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Tidskriftsartikel (refereegranskat)abstract
- Comets are regarded as probably the most primitive of solar system objects, preserving a record of the materials from which the solar system aggregated. Key amongst their components are organic compounds - molecules that may trace their heritage to the interstellar medium from which the protosolar nebula eventually emerged. The most recent cometary space mission, Rosetta, carried instruments designed to characterize, in unprecedented detail, the organic species in comet 67P/Churyumov-Gerasimenko (67P). Rosetta was the first mission to match orbits with a comet and follow its evolution over time, and also the first mission to land scientific instruments on a comet surface. Results from the mission revealed a greater variety of molecules than previously identified and indicated that 67P contained both primitive and processed organic entities.
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| 7. |
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| 8. |
- Grotzinger, John P., et al.
(författare)
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Curiosity's Mission of Exploration at Gale Crater, Mars
- 2015
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Ingår i: Elements. - : Mineralogical Society of America. - 1811-5209 .- 1811-5217. ; 11:1, s. 19-26
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Tidskriftsartikel (refereegranskat)abstract
- Landed missions to the surface of Mars have long sought to determine the material properties of rocks and soils encountered during the course of surface exploration. Increasingly, emphasis is placed on the study of materials formed or altered in the presence of liquid water. Placed in the context of their geological environment, these materials are then used to help evaluate ancient habitability. The Mars Science Laboratory mission—with its Curiosity rover—seeks to establish the availability of elements that may have fueled microbial metabolism, including carbon, hydrogen, sulfur, nitrogen, phosphorus, and a host of others at the trace element level. These measurements are most valuable when placed in a geological framework of ancient environments as interpreted from mapping, combined with an understanding of the petrogenesis of the igneous rocks and derived sedimentary materials. In turn, the analysis of solid materials and the reconstruction of ancient environments provide the basis to assess past habitability.
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| 9. |
- Hassellöv, Martin, 1970, et al.
(författare)
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Iron Oxides as Geochemical Nanovectors for Metal Transport in Soil-River Systems
- 2009
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Ingår i: Elements. - : Mineralogical Society of America. - 1811-5209 .- 1811-5217. ; 4:6, s. 401-406
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Tidskriftsartikel (refereegranskat)abstract
- Topsoils are often contaminated by trace metals, and it is important to understand how different processes govern the transport of such metals to fresh and marine waters. This paper presents measurements of natural nanoparticles and colloidal organic matter in soil and river samples from Germany and Sweden. In our analytical approach, a nanoparticle separation technique is combined with multielement detection and applied to soil and river samples to link the macroscale field observations with detailed molecular studies in the laboratory. It was determined that lead is associated with iron oxide colloids, which are ubiquitous nanoparticles that can be efficiently transported. Eventually both iron oxides and lead are removed by flocculation under conditions of estuarine mixing. Iron-rich nanoparticles compete efficiently with natural organic matter (NOM) complexation for lead binding in both the soil and river systems studied.
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