Effect of the topography on tephra fall deposits for small, monogenetic volcanoes at high altitude?
Hello, I am a grad student working on my MSc/PhD thesis (it's a hybrid program so you can start your MSc and go for full PhD if that's your intention all along and meet the requirements)
I'm working on a small monogenetic volcano located in Sierra Chichinautzin, south of México City. After compiling all the stratigraphic sections of the tephra deposited by this volcano, which I produced after several comprehensive field trips, I realized that the varying thickness of the sections and average grain sizes made no sense whatsoever except in some local areas where thin sections of finer grain size where located far from the volcano as opposed by thick sections of coarser grain size located near the volcano. Apart from this areas, nothing else made sense. My sections vary wildly. I have made sure that I'm only considering fresh sections, neither reworked not eroded simultaneously to the deposition. There are no aggregates/welding of the particles. The fragmentation is very efficient since most of the deposits fall in the ash size, but at the same time, these tephra is only locally found, and since it is a young volcano (ca. 10.000 YBP) massive erosion is unlikely. One hypothesis I'm considering is the effect of topography, since Sierra Chichinautzin is full of small structures that could have affected the deposition of my tephra, along with prevalent winds (all deposits were found in a N-NE-S arc, nno deposits on the western flank). I have searched the databases and literature on how topography may affect tephra deposition is scarce, to say the best. I would appreciate immensely a nudge in the right direction. Thank everyone for their help!