Carbon dioxide levels in Earth’s atmosphere—and, consequently, ocean temperatures—are rising. How high and how fast ocean temperatures can rise can be learned from temperature measurements of ancient oceans. At the same time, energy exploration also relies on knowing the thermal history of oil and gas source rocks, which is often difficult to determine.
One of the most promising techniques for measuring ancient ocean temperatures and basin thermal histories relies on the co-enrichment of rare heavy oxygen and heavy carbon in the calcium carbonate compound found at the bottom of the ocean. This enrichment, termed clumped isotopes, is commonly measured using fossil shells and limestones to determine the temperatures at the time when sediments became deposited on the sea floor.
However, there’s a catch: Clumped isotope temperatures can be reset by the very process of sediments being buried, causing those sediment temperatures to rise as they create the same conditions responsible for converting organic matter in sedimentary rocks to oil.
Such complex problems require interdisciplinary approaches—a collaborative mindset that thrives in the Texas A&M University College of Arts and Sciences, where a team of geologists and chemists has taken the quest to the atomic level to more accurately measure ancient ocean temperatures.
The team, led by Dr. Ethan Grossman in the Department of Geology and Geophysics and Dr. Sarbajit Banerjee in the Department of Chemistry, recently used a combination of supercomputing and density functional theory to model the process responsible for setting and resetting clumped isotope compositions, a phenomenon known as reordering.
2023-08-01 18:48:02
Source from phys.org