New Mexico Geological Society Annual Spring Meeting & Ft. Stanton Cave Conference — Abstracts

Cave formation by sulfuric acid, known as “sulfuric acid speleogenesis,” is responsible for some of the world’s largest and most spectacular caves. In actively forming caves, sulfuric acid is produced at the water table where anoxic, hydrogen sulfide (H₂S)-rich groundwaters are exposed to oxygen, usually in fresh surface waters or cave air. Because sulfide oxidation represents a rich source of chemical energy, sulfuric acid caves support robust communities of chemosynthetic microorganisms that speed up acid production and limestone dissolution, and support entire sulfide-based ecosystems that include invertebrate and sometimes even vertebrate life. Although they are rare, these “active” sulfuric acid caves are important analogues that allow us to directly observe the processes responsible for ancient sulfuric acid caves, such as those that occurred in New Mexico’s Guadalupe Mountains between 4-12 million years ago. My talk will focus on the the Frasassi cave system in central Italy, a spectacular example of an active sulfuric acid cave. I will discuss biogeochemical sulfur cycling at the cave water table, the role of microorganisms in inorganic sulfur transformation and limestone dissolution, and how the secondary minerals and passage morphologies are overprinted as cave levels are removed from the sulfidic aquifer through tectonic uplift.