the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 08 Jul 2026
Ice core insights into the morphology and composition of mineral dust deposited in the tropical Peruvian Andes
Abstract. Mineral dust plays an important role in governing Earth’s energy balance by scattering electromagnetic radiation back to space and by reducing the surface albedo of glaciers. However, in the tropical Andes of South America, long-term mineral dust observational records are extremely scarce and spatially limited; likewise, little has been done to characterize the morphological and mineralogical properties of dust in this region. Here we present a multidecadal mineral dust record obtained from a tropical ice core with emphasis on the size distributions, shape characteristics, and mineral compositions of single particles. We used a scanning electron microscope with energy dispersive x-ray spectrometry (SEM-EDS) to characterize 1887 individual mineral grains (<5 µm) preserved in an ice core from Nevado Huascarán (Peru) and we interpret the results in context of dust provenance. The SEM-derived particle sizes are found to follow a lognormal distribution with circularities (median 0.75) and aspect ratios (median 1.42) typical of mineral dust. Approximately 60 % of the mineral particles are consistent with clay mineralogy (e.g., illite, kaolinite, montmorillonite), indicating that the particles originate primarily from soils in distal source areas. The relative abundance of quartz, feldspar, and mica in the ice core is comparatively low and likely reflects local dust derived from granodiorites and phyllites near the glacial margins.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2026-3846', Anonymous Referee #1, 20 Jul 2026
- AC1: 'Reply on RC1', Austin Weber, 02 Aug 2026
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RC2: 'Comment on egusphere-2026-3846', Anonymous Referee #2, 04 Aug 2026
The manuscript on the evaluation and characterization of particles deposited on the Huascarán Glacier in the Cordillera Blanca, Peru, is well written and detailed. Furthermore, it provides information on the morphology and chemical composition of particulate matter from 1960-2015.
Nevertheless, detailed comments and questions are listed below:- In the first paragraph, it would be beneficial to further improve and expand the list of different effects of particulate matter in the atmosphere as an example: ocean productivity, human health, reduce solar radiation....
- Line 57: I would highly recommend to change the use of To our knowledge, to In this study,.
- On the mineral identification: Although the methodology and the references on which the mineral classification is based are cited, the manuscript does not specify the final classification criteria or the used elemental ratios to assign particles to the different mineral groups. Those ratios may be subtle to different interpretations, providing them would improve the transparency of the methodology and facilitate the reader's understanding of the final mineral classification. So, I highly recommend to attach a table in the supplementary material describing and fixing those elemental ratios for each mineral class.
- To facilitate comparison with previous work done in the topic, it would also be beneficial to complement the results and discussion sections with comparisons to other studies, highlighting similarities and differences in particle size distributions, particle shapes, and mineralogical composition. Such comparisons would strengthen the interpretation of the data and help better constrain the relative contributions of long-range transported North African dust versus locally sourced dust.
- The manuscript shows a good correlation between the abundance of kaolinite detected in the ice core, and regional deforestation rates. It would also be interesting to investigate whether the relative abundance of specific mineral groups (e.g., montmorillonite, mica, kaolinite, or oligoclase) correlates with the frequency of North African dust events affecting the region during the same period. Such an analysis could provide additional evidence supporting the contribution of long-range transported Saharan dust to the mineral assemblages identified in the ice core.
Finally, I would like to congratulate the authors on this valuable work and the results presented. This study provides important new insights into the characterization of mineral dust transported to the tropical Andes and offers valuable information that will support future studies on dust sources, transport pathways, and environmental change.
Citation: https://doi.org/10.5194/egusphere-2026-3846-RC2 - AC2: 'Reply on RC2', Austin Weber, 18 Aug 2026
Data sets
Nevado Huascarán Ice Core Dust Morphology and Mineralogy 1960-2018 CE A. M. Weber et al. https://doi.org/10.25921/1j1e-tf69
Model code and software
Code used for analysis and visualization in “Ice core insights into the morphology and composition of mineral dust deposited in the tropical Peruvian Andes” A. M. Weber https://doi.org/10.5281/zenodo.20817171
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This manuscript provides a morphological and mineralogical characterisation of dust particles found in ice cores collected in the tropical Peruvian Andes and discusses their potential sources. Overall, I found the manuscript well written, and the discussion of potential dust sources is thorough. I only have a few minor comments.
I was wondering whether it would be possible to identify or use accessory minerals that can be specifically linked to the granodiorite, tonalite, and Chicama Formation. These could provide additional constraints for source attribution.
Carbonates were not observed in the analysed particles. Could the absence of carbonates help to exclude or support specific potential dust sources?
Do the particles show any coatings or internal mixing that could support atmospheric processing during long-range transport? Since the manuscript discusses the possibility of a North African contribution, I was wondering whether the particles show any evidence of atmospheric ageing that could provide additional support for their long-range transport.
In the Introduction, the authors mention the role of iron oxides as strong light absorbers, including after deposition on glaciers. However, the iron oxide content is not really highlighted or discussed in the rest of the manuscript. If iron oxides were identified, I think it would be interesting to briefly discuss their abundance and potential implications.