Aeolian grains show the typical frosted surface texture under the SEM. The morphology or shape of grains (e.g. angularity) is not diagnostic but strongly depends on the lithology and cannot used to distinguish fluvial from aeolian grains. What migh help you is the grain size of aeolian grains which due to the rather homogeneous wind speed fall into a narrow particle range. If you have the chance to measure the angle of cross-bed-sets you will see that dry aeolian sands have a angle of repose of about 34 ° in dunes and sand sheets.

Regards

H.G.Dill

The eolian Miocene siltstone of eastern Arabia has the following visual characters:

1. Purple, red or brown color

2. Very fine if yoy mix it with water it becomes jellylike

3. No bedding but there are some bioturbation features

4. Plant roots and other organic structures

5. Gypsum or anhydrite nodules

If use SEM then you can see the usual frost features and the rounded grains

Aeolian sediments magnetically show round and matte quartz grains whereas aquatic quartz grains are blunted blunting At the SEM they show a lot of shock in the form of V! In the field, they show structures with high angle (about 45 °)

Since the deposits are both silt-sized, the difference will be in the depositional structures. Dunes will be high angled while fluvial silts will be low-angled to parallel bedded.Other inclusions like rootlets, leaf impressions and carbonaceous matter may be contained in fluvial deposits.

Obianuju P. Umeji

- Aeolian silt and sand grains have frosted surfaces due to the the abrasion that they suffered when impacted to each other's.

- Aeolian silt might be better sorted than fluvial silts, while fluvial silts tend to be mixed with fine sand and clays and often have organic matter content.

-In a fluvial system, silts and finer sediments are related to flooding plains, so when the river level grows up and cover the plains around the river, after the energy decreases, the silts, clays and organic matter particles deposit on the flooding plain. Silts also occur in abandoned channels in meandering river systems.

I am interesting to read your valuable explanations.

I think that surface texture would by a key tool to distinguish between mineral grains mainly quartz in both fluvial (subaqueous) and aeolian coarse grained silts. Conchoidal fracturing is frequent in river system. Water laid sediment have clear translucent sediment and possibly crescent impact marks. Aeolian sediment are usually dull, frosted and show upturned plates oriented at some angle to grain surface.

In addition to my post above:

I plotted in a new paper the TiO2*10/(TiO2*10+Fe2O3)*100 ratio vs. the median and the heavy mineral (totals) in ppm expressed through the elements Ce, Y, Zr ......vs. sorting (quartil 75/ quartil 25). You can also use the square root of the ratio. You can distinguish the aeolian and fluvial environments and deposits from each other.

Read: DILL, H.G., and BUZATU, A. (2021) From the aeolian landform to the aeolian mineral deposit in the present and its use as an ore guide in the past. Constraints from mineralogy, chemistry and sediment petrography.- Ore Geology Reviews (on-line).

HGD

The difficulty to distinguish fluvial silts from aeolian counterparts is the lithified specimen in vision. Different from fluvial siltstones, aeolian siltstone are mostly possible blocky without or with few cross-bedding (ripples) and express the red claystone or loess.