Triple oxygen isotope measurements in chert: insights into the Snowball Earth glaciations

Snowball Earth events represent a critical component of the history of the planet, particularly for the trajectory of life, atmospheric oxygen, and planetary habitability. There remains a myriad of questions about the dynamics of these global glaciations, especially regarding the relationship between the cryosphere and hydrosphere during this time. This study analyzes silica precipitates within a carbonate sequence immediately underlying a Cryogenian diamictite to better understand this relationship, particularly the chemistry of subglacial meltwater. Using triple oxygen isotope measurements, clumped isotope palaeothermometry, uranium-lead geochronology, and SEM/EDS and XRD analyses, we present interpretations of both the host rock and possible scenarios for the geochemistry of the precipitating fluid(s) responsible for these silica cements. We posit that these cherts are precipitates either from syn-glacial, sub-ice meltwaters or deglacial fluids from the end of the Marinoan glaciation, providing useful insights into the chemical composition of these source waters and demonstrating the utility of chemical precipitates as a record of ancient sub-ice conditions.

Name thesis:degree_name

Bachelor

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2025

Author dc:creator

• Freudenburg-Puricelli, Markey

Advisor dc:contributor.advisor

• Bergmann, Kristin

Statement dc:rights

• In Copyright - Educational Use Permitted
• Copyright retained by author(s)

Licence dc:rights.uri

• https://rightsstatements.org/page/InC-EDU/1.0/

Handle dc:identifier.uri

https://hdl.handle.net/1721.1/159903

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/159903