Ancient atmospheric gas concentrations from fluid inclusions in surficial minerals
The current proxies for the composition of the ancient atmosphere are imprecise and inaccurate, yet these planetary boundary conditions set Earth’s climate state and dictate habitability. Our group has developed a unique method to directly measure the composition of the ancient atmosphere from actual samples of ancient air trapped in tiny fluid inclusions in minerals from surficial environments. Example shown is a 1.4 Billion year old halite sample containing inclusions of Mesoproterozoic air and water that formed in an environment similar to modern day Death Valley (image credit Justin Park). See Pettitt and Schaller 2020; Park and Schaller 2025. MAGPI Code for gas-aqueous partitioning of fluid inclusion volatiles (Park and Schaller, 2025) is available here.
Massive and widespread wildfires during a period of ancient climate change
Our group has uncovered evidence of widespread wildfires at a climate warming event that occurred 56 million years ago at the Paleocene-Eocene boundary, an episode that is widely regarded as an analog for anthropogenic climate change (the Paleocene-Eocene Thermal Maximum or PETM). Microscopic pieces of charcoal are found in a distinct stratigraphic level coincident with the warming across a 250 km swath of the Atlantic coastal plain (image credit Megan Fung). These efforts will be part of the recently funded PEP-US drilling project through the International Continental Drilling Program.
Extraterrestrial impact at the Paleocene Eocene boundary
Along with collaborator Megan Fung, we discovered impact ejecta (microtektites) coincident with the warming event at the Paleocene Eocene boundary along the Atlantic coastal plain. This finding suggests that there was an extraterrestrial impact associated with the warming and wildfires 56 million years ago, making it a potential trigger for the climate event. In subsequent work we radiometrically dated the material and are now working to define the boundaries of the impact strewn field and recover material from a newly dated crater.
Modern soil gas and carbon isotope dynamics
A problem with soil-based proxies for the concentration of CO2 in the ancient atmosphere is the unknown concentration of CO2 within an ancient soil. Because the present is the key to the past, we are using the bulk gas and isotope dynamics within modern soils to understand their ancient counterparts. Specifically, we are comparing the results of soil gas monitoring wells installed on test soils in Texas to the measured volatile content of fluid inclusions in contemporaneous carbonate minerals formed in those soils (image credit Todd Knobbe).
Planetary scale eruption of Large Igneous Provinces and mass extinction
Schaller produced the first observations of the direct atmospheric pCO2 effect of the eruption of a Large Igneous Province (LIP) un-hindered by stratigraphic uncertainty (see Schaller et al 2011 and 2012). The temporal association of the eruption of the Central Atlantic Magmatic Province makes it a likely trigger for the End-Triassic Mass Extinction, although the kill mechanism may ultimately have been SO2 induced volcanic winters. Refinement of this record using newly developed techniques that can determine the bulk volatile contents of contemporaneous fluid inclusions in environments like the deep ocean is an area of ongoing research.