Figure 2

USGS Portland-1 core lithologic section, carbon isotope profile and RockEval data. Facies Explanation: 1. Peloidal/foraminiferal, packstone/grainstone; 2. Bioturbated peloidal packstone; 3. Bioturbated peloidal wackestone; 4. Skeletal grainstone; 5. Rippled mudstone; 6. Silty laminated mudstone; 7. Diffusely laminated mudstone; 8. Massive mudstone; 9. Bentonite. Samples were limited to facies 7 and 8. The occurrence of bioturbated peloidal carbonates during the OAE2 CIE indicates that the environment at the time of deposition was oxygenated and supported a diversity of tropical marine life. Note that the core is measured in imperial units as the Portland-1 core and core photos are curated with imperial measurements. This reference is preserved here in the case that the reader wishes to cross-reference these results to the Portland-1 core. Radioisotopic measurements from bentonites A, B, and C, along with biostratigraphy and correlation of depositional cycles to orbital timescales have produced an average sedimentation rate of 0.93 cm/kyr during the OAE2 CIE^19,20,21. The interval of samples with the greatest flux in measured biomarker concentration occurs from ca. 473 feet to ca. 479 feet, in the central portion of the OAE2 CIE. Sample spacing in this interval is somewhat irregular in order to stay within the same depositional facies, but varies between 3 and 12 cm indicating that rapid flux in organic geochemical composition of analyzed sediments over periods approximately 3–15 kyr. The carbon isotopic excursion (CIE) that defines OAE2 is shown on the δ¹³C track and highlighted in blue on all compound tracks²⁰. Hydrogen Index (HI) is generally negatively correlated with depositional environment oxygen concentrations, thus supporting the trend of OAE 2 CIE oxygenation. Oxygen Index (OI) generally correlates positively with depositional environment oxygen concentrations, and again provides evidence for oxygenation during the OAE2 CIE.