Measurements of sea level from the past tell us how ice sheets and the solid earth respond to climate change. Even regions far from ice sheets experience meters of subsidence or uplift from glacial isostatic adjustment (GIA), and these adjustments complicate the interpretation of paleo sea-level measurements. I work on combining photogrammetry, differential GPS, and high resolution carbonate stratigraphy of exposed coastal sedimentary rocks to constrain the predictive GIA models and provide greater certainty on paleo sea-level.
Periodic environmental change may create cyclicity in a sedimentary succession, and the frequency and nature of that cyclicity is important for understanding Earth system dynamics. However, the sedimentary system also is sensitive to internal thresholds that may turn on and off sedimentation without a periodic external forcing. I am developing new tools to read the environmental signals recorded by sedimentary sequences to aid in distinguishing between these two sources of cyclicity. For example, we can use maps of carbonate environments in the modern ocean to learn about the relationship between water depth and carbonate sedimentation. Building dynamic Bayesian networks from this modern sedimentological data allows us to extract quantitative signals of water depth change from ancient stratigraphic sequences.
THE LATE PALEOZOIC ICE AGE
At the end of the Paleozoic, Earth plunged into a long ice house interval with vast ice sheets in the southern hemisphere. Insight into the major feedbacks regulating our climate system can be gained by studying the rates of ice house initiation and collapse, as well as the high frequency glacial interglacial pacing during this ancient cold period.
The carbon isotopic record of ancient carbonates provides an indirect observation of the ancient carbon cycle, and the carbon cycle is intricately tied to climate and the history of oxygen on Earth. However, interpreting this carbon isotopic record can be complicated by diagenesis of samples, and perhaps by the transient effect global diagenetic events may have on the ocean.
Meteoric diagenesis occurs when carbonate rocks are infiltrated with fresh water over long periods of time. These reactions result in phase changes and isotopic exchange between fluids and minerals. The carbon and calcium isotopic fingerprint of meteoric diagenesis encodes information about the ancient terrestrial system that can be extracted through a merger of probabilistic predictive models and data.
Diagenesis Code (coming soon)
Lamont-Doherty Earth Observatory, Columbia University
61 Route 9W, Palisades, NY, 10964, USA
blake.c.dyer at gmail.com