Research areas and interests
Organic Molecules and Water in Primitive Meteorites
On January 18, 2000 a unique, carbon-rich meteorite fell on the frozen surface of Tagish Lake in northern B.C. The first specimens were picked up without direct hand contact a few days later, and kept frozen. Acquisition of these pristine Tagish Lake meteorite specimens in 2006 enabled a systematic study of the degree of variation in the mineralogy, petrology, geochemistry and organic chemistry. Several specimens were selected based on variations in macroscopic characteristics, with the prediction that these variations would reflect lithological variations and thus differences in the geologic conditions on the asteroid parent body. We demonstrated that the degree of parent body aqueous alteration corresponds to the degree of modification of organic matter (Herd et al. 2011; Glavin et al. 2012), a result that has had a significant impact on current science in the field. Hydrogen isotopic compositions of organic matter and clays in Tagish Lake have also contributed to understanding the sources of volatiles in the terrestrial planets (Alexander et al. 2012).
Meteorites from Mars
The work that I initiated during my Ph.D. demonstrated that oxygen fugacity, which is a measure of the redox potential, varies significantly in Martian meteorites and that the correlation between oxygen fugacity and radiogenic isotopic composition is best explained by the characteristics of the mantle of Mars that were established during planetary formation and differentiation by 4.5 Ga, yet are nevertheless recorded in young (200-600 Ma) basalts (Herd, 2003). I have contributed oxygen fugacity estimates to studies of many different martian meteorites, and have gained insights into the impact shock effects recorded in these meteorites (collaborations with E. Walton, MacEwan University), and alteration processes. I co-authored the first paper on the Tissint meteorite (martian meteorite which fell July 18, 2011; Aoudjehane et al. (2012)), and led a consortium study of the Northwest Africa 8159 meteorite, a unique sample of Mars (Herd et al., 2017). I have also contributed to the geochronology of martian meteorites through application of ion probe methods to the U-Pb dating of baddeleyite (Zhou et al. 2013), and to a recent review paper on Mars as an Earth-like world (Ehlmann et al. 2017).
Meteorites and Small Impact Craters
In part due to my role as curator of the University of Alberta Meteorite Collection, my research program includes meteorites of many different types. As curator, I receive dozens of inquiries from members of the public every year regarding potential meteorites; one such inquiry in 2007 resulted in the discovery of the < 1100 year old Whitecourt Meteorite Impact Crater, the youngest impact crater in Canada and one of only 15 worldwide with associated meteorites. This crater formed the basis of novel research into small craters (Herd et al. 2008; Kofman et al. 2010; Newman and Herd 2015), and the addition of many 10s of kg in the form of hundreds of meteorites to the Collection. Expansion of the Meteorite Collection has also taken place through classification of new meteorites from Canada and elsewhere: the collection has expanded by 60% since 2006. The Meteorite Collection represents countless potential research projects for students.