Ph.D. Research
Field spectrometer collected reflectance spectra of discrete spots in the visible to near-infrared wavelengths.
I did my Ph.D. at the University of Colorado at Boulder (Dept. of Geological Sciences/Laboratory for Atmospheric and Space Physics). In my Ph.D. I was interested in understanding the reaction pathways and mineral products of acid-sulfate weathering in a hydrothermal, volcanic environment. I used the young volcano Cerro Negro in Nicaragua as an analog to early Mars. Cerro Negro was originally proposed to be an analog for possible early Mars environments with implications for astrobiological potential by Drs. Brian Hynek and Tom McCollom (Ph.D. advisor and committee member, respectively). For my contribution to the larger body of work on this site, I focused on understanding the influence of initial parameters. In particularly, I ran several experiments reacting sulfuric acid with different rock components at varying high temperatures and fluid:rock ratios to observe the change in alteration products between components, as well as, over time. I used XRD and SEM analysis techniques to examine the experimental products and collected field samples. To aid in interpretation of experiment and field results, I used Geochemist’s Workbench to replicate the experiments in model form, as well, as explore a larger parameter space than is accessible in the experiments. In the last year of my graduate work, I had the chance to visit Cerro Negro, as well as three other nearby sites. In addition to collecting samples, I used ASD’s TerraSpec4 to do in-situ reflectance spectroscopy. We applied the knowledge gained from experiments, models, and fieldwork to potential sites of hydrothermal alteration on Mars using CRISM, HiRISE, CTX, and THEMIS data. I received a NASA Earth and Space Science Fellowship to conduct this work.
Fieldwork in Nicaragua
Cerro Negro is a young (~150 years old) cinder cone in western Nicaragua outside of León. The area is protected (small fee to enter) and is popular for cinder-boarding.
Momotombo Volcano is a traditional stratovolcano, a few hundred years old and ~1300 m tall (4,300 ft). We each the summit caldera by climbing up an old lava channel, which took about 3 hours (just as long coming down too!).
To the left is the fresh black basalt of the current cone. The light area on the right is the highly weathered inside flank of an older eruption cone. The flat middle area (pinkish) is an outwash basin or drainage area.
At the time we were there in 2012, the last major eruption of Momotombo had been in 1905. Despite the 100 year gap in eruption, the summit caldera was very active with some areas reaching 800°F and dense sulfur-gases.
Experiments
Ground up minerals were sealed in Teflon containers with varying amounts of sulfuric acid and heated at a range of temperatures and for up to 6 months.
The orange color of the alteration products of iron-rich forsterite (olivine) indicated iron oxidation, although few iron secondary minerals were detected with analytical methods. A thick Si-rich gel formed at the surface.
The most dominant secondary minerals formed were Ca-sulfate, either anhydride or the hydrated form gypsum. The macroscopic crystals took needle-like forms (different lengths and thicknesses) and dried white.
More details of the work can be found in the following publications:
Marcucci, E.C. and B.M. Hynek (2014) Laboratory simulations of acid-sulfate weathering under volcanic hydrothermal conditions: Implications for early Mars, J. Geophys. Res. Planets 119, doi:10.1002/2013JE004439
Marcucci, E.C., B.M. Hynek, K.S. Kierein-Young, and K.L. Rogers (2013) Visible-near infrared reflectance spectroscopy analysis of acid-sulfate alteration in volcanic systems in Nicaragua: Analogs for early Mars, J. Geophys. Res. Planets 118, doi: 10.1002/jger.20159.
Hynek, B.M., T.M. McCollom, E.C. Marcucci, K. Brugman, and K.L. Rogers (2013) Assessment of environmental controls on acid-sulfate alteration at active volcanoes in Nicaragua: Applications to relic hydrothermal systems on Mars, J. Geophys. Res. Planets 118, 2083-2104.