التفاصيل البيبلوغرافية
| العنوان: |
Sorting and Weathering Trends of Soil at Gale Crater, Mars: Implications for Regional Pedological Processes. |
| المؤلفون: |
Shi, Yutong, Zhao, Siyuan, Karunatillake, Suniti, Cousin, Agnes, Zhao, Jiannan, Xiao, Long |
| المصدر: |
Journal of Geophysical Research. Planets; Dec2024, Vol. 129 Issue 12, p1-28, 28p |
| مصطلحات موضوعية: |
GALE Crater (Mars), MINERAL dusts, DUST, WEATHERING, CHEMICAL processes, CHEMICAL weathering |
| مستخلص: |
Detailed soil characterization at Gale crater based on in situ observations has revealed compositional trends within soils, while the physical and chemical processes underlying the compositional trends remain to be evaluated. Here we use the grain‐morphometrical and geochemical trends across the Wentworth‐classes of 48 in situ soil targets at Gale crater to evaluate underlying pedological processes and potential chemical weathering signatures. The concentration of olivine minerals within the ∼250 to ∼500 μm size range indicates the prevalence of heavy mineral sorting in a granulometric sense in Gale soils that surpasses the possible effect of the cratering‐induced mixing processes. The extent of olivine sorting in soils varies spatially and is influenced by the targets' aeolian setting. The finest portion of Gale soils (<125 μm) is likely a mixture of allochthonous sediment, globally sourced from atmospheric suspension, and autochthonous counterparts from the weathering of local rocks, while the coarser soils (>125 μm) are mostly sourced from local rocks, with possible inputs from both the unaltered parent rock of the Stimson formation and the bedrocks that have undergone diagenetic alteration. If applicable globally, this would reinforce prior inferences that even dust‐mantled regions are geochemically heterogeneous owing to a substantial fraction of soils derived from underlying lithology. The low chemical weathering intensity and coupling of mobile elements in soils suggest localized, low pH and low water‐to‐rock ratio aqueous weathering conditions under predominantly cold and arid climates, which may occur either during post‐pedogenetic alteration in soils or during the acidic alteration of source rocks. Plain Language Summary: The Mars Science Laboratory rover Curiosity has provided excellent materials to study the physical and chemical properties of in situ Martian soils, as well as the underlying pedological processes. Here we select 48 soil targets along the Curiosity traverse that have spatially corresponding microscopic images and bulk chemistry data and measure their grain size and shape using a software capable of grain identification. We find evidence of physical sorting of olivine in soils along the rover's traverse; the degree of sorting is related to the sample's aeolian setting. The finest soils (<125 μm) have a mixed source of both local rocks and atmospheric dust, while the other coarser soils are mostly sourced from local bedrock. All the soil targets have experienced minimal chemical weathering. The coupling of elements with different enriching pathways in soils is consistent with an acidic environment and possibly water‐related mixing processes, which may represent the weathering regime of the source rocks if the soils underwent only mechanical weathering. Together, our observations suggest that the forming and subsequent weathering of Gale soils likely happened in a water‐limited acidic condition, for example, acidic playa or volcanogenic acid‐fog, under a cold and arid climate. Key Points: The concentration of olivine minerals within the medium‐sized (∼250–500 microns) soils indicates pervasive heavy mineral sortingThe finest soils are sourced from both air‐sampled dust and local rocks, while the coarser soils are largely sourced from local rocksSoil chemistry suggests pedogenesis at Gale that may include a localized, low pH, low water‐to‐rock ratio aqueous weathering condition [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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