Ocean Island Basalts- My Ph.D. dissertation research was focused on determining the sulfur isotope composition of various mantle reservoir that are sampled by mantle plumes. For the dissertation I made bulk sulfur isotope measurements on sulfide inclusions in mineral separates from Mangaia (a type locality for HIMU) and whole rocks from the Samoan islands (the type locality for EM II). With the high precision analyses, I am able to identify distinct sulfur sources that are contributed to the respective plumes. Image is a snip from figure 28 in the Dottin III, 2020 dissertation. The figure shows shows mixing between primordial and recycled sulfur in the Samoan mantle plume.
Mars- My M.Sc. thesis research and ongoing collaborations have focused on the dynamic interplay between sulfur in the Martian atmosphere, on its surface, and the subsurface. My master’s thesis research focused on the S-isotope composition of paired Nakhlites (MIL090030/32/136). These Nakhlites are highly oxidized, showing evidence of late-stage, intercumulus, skeletal magnetite grains and sulfides. The S-isotope compositions of the intercumulus sulfides collected via Secondary Ion Mass Spectrometry (SIMS) reveal a fractionated atmospheric signal from an assumed sulfate precursor. Through modal analysis, I determine that the amount of Titano-magnetite and sulfide can account for the highly oxidized state of the meteorites through a process of assimilation of 10’s of centimeters of Martian sediment with sulfate by an overriding lava and subsequent sulfate reduction that penetrates ~1 m into the flow from the surface. Image is a snip of figure 4 from Dottin et al. 2018 that demonstrates the use of image analysis to determine modes of various phases.
Primitive meteorites- A portion of my research has been grounded in studying the S-isotope composition of early formed meteorites to understand the nature of sulfur in the primitive solar system. Questions of interest have been: Where in the solar system did the sulfur form? How has it been processed prior to planetary accretion? How has it been processed post-planetary accretion? Can we use sulfur to link meteorite groups to specific parent bodies in the solar system? My work published on the S-isotope composition of Main Group Pallasites (assumed representatives of the core-mantle boundary of differentiated meteorites) shows that Pallasites host sulfur that has been mass-independently fractionationed in the early solar nebula and incorporated into the interior of the parent body. Furthermore, I show that the S-isotope signal is similar to that of IIIAB iron meteorites, further supporting a genetic link between the two meteorite groups. The image shown is a snip of figure 1 from Dottin et al. (2018) which highlights a commonality in the S-isotope compositions of IIIAB iron meteorites and Main Group pallasites, suggesting they are linked.