I welcome the opportunity to continue the discussion of my mass analysis methodology, and I would like to take this opportunity to acknowledge the workers who have contributed to the extensive literature on the mapping and geochemistry of Columbia River Basalt Group (CRBG) lava flows. Notably, the junior authors of the comment by Baker et al. (2019) have produced much of the formative work on CRBG chemostratigraphy over the past several decades. To each of them I express my appreciation for providing the foundation on which I have built my own research.
In their comment, Baker et al. state that careful sampling by previous workers, and sample selection through examination of numerous thin sections, have resulted in a geochemical database for samples from the Sentinel Bluffs Member of the Grande Ronde Basalt that are mostly unaffected by secondary alteration (e.g., Reidel and Valenta, 2000). Moreover, they state that their geochemical methods are “rigorous,” “well established,” and have a “long history” of application in the study of CRBG lavas. They claim, however, that my mass analysis method (see Section 3) is “flawed,” “invalid,” and “arbitrary,” and that “it seems improbable that samples with fresh outcrop appearance and commonly glassy and unaltered mineralogy in thin section could simultaneously show chemical trends resulting from considerable mineral dissolution.”
In reply, I will show that both anoxic alteration and oxic surface weathering of CRBG lavas are prevalent both east and west of the Cascade Range, that my methodology is based on quantitative techniques that have been used in the analysis of weathered rocks and soils for decades (Nesbitt, 1979; Brimhall et al., 1992; Anderson et al., 2002), and that my own careful field and laboratory sampling, as documented in Sawlan (2018), can result in an unweathered and relatively unaltered sample collection, whereas those samples previously collected in SB lavas (e.g., Reidel and Valenta, 2000) have not only experienced significant anoxic water-rock interaction with groundwater but have subsequently undergone appreciable oxic weathering at the ground surface.