4 High latitude paleoceanographic discoveries from Scientific Ocean Drilling (IODP, ODP, DSDP)

Scientific Ocean Drilling has retrieved thousands of meters of sediment cores from the high latitude oceans.  This session provides the opportunity to present the results of work to understand Cenozoic climate and oceanographic changes.

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Room 27

Investigation of Ages and Petrographic Context of Glauconite and Celadonite at IODP Site U1564

Paper number: 4-1
Program: Technical Sessions
Time: 8:05 AM – 8:25 AM

Authors

Abstract

Extensive occurrences of glauconite within Miocene and Oligocene sediments and celadonite within Oligocene basalt basement were recovered at IODP Site U1564 (59°51.0363′N, 23°15.9840′W, 2208.1 mbsl). Glauconite is thought to form in place at the sediment-seawater interface over 105-106 years, commonly from a fecal pellet or foraminifera substrate, while celadonite occurs as a secondary product within hydrothermally altered ocean crust, filling in basalt fractures and vesicles. Glauconite formation mechanisms in deep-sea settings are poorly constrained. In addition to using a combination of petrographic and geochemical characterization and electron x-ray probe micro-analysis, we are employing K/Ar geochronology on the glauconite pellets collected from sediment samples and celadonite from basalt samples from IODP Hole U1564F. This study will constrain the timing of these green, Fe- and K-rich minerals that share the same chemical make-up, as well as examine their context and composition to evaluate their formation mechanisms. Based on preliminary K/Ar dates for each occurrence’s formation, revealing similar and younger ages than the surrounding sediment and basalt, we suggest that not only did glauconite form in place in deep water along the eastern flank of the Reykjanes Ridge, but likely formed through a hydrothermal alteration mechanism, similar to how celadonite precipitates. This initial finding likely reflects increased circulation of seawater through the region sometime within the Oligocene to Miocene, resulting in the precipitation of these K- and Fe-rich minerals. 

This study seeks to further characterize the formation mechanisms contributing to glauconite and celadonite occurrences throughout the sediment and basalt sequences at U1564 by collecting more robust K/Ar ages of these minerals. Additionally, by continuing to interpret the mineralogical composition of glauconite and celadonite through x-ray diffraction, this study aims to understand the maturity of these minerals and potential substrates for their formation, providing a deeper understanding of authigenic minerals in their role of element cycling and connections to past climate.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411143

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