Variations of Stable Isotope Ratios in Nature

Hoefs, Jochen

doi:10.1007/978-3-030-77692-3_3

Cited by 3 publications

(1 citation statement)

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“…By substituting actual clumped isotope temperatures (T[Δ 47 ]) for an assumed environmental temperature (cf., Section 5.3.2), we can calculate source water (δ 18 O sw ) values for these spar‐formation fluids, which range from −2.1 to −5.2‰ (VSMOW). These values are significantly enriched in 18 O relative to estimated environmental/meteoric waters for the region during the Paleogene (e.g., Jahren & Sternberg, 2008; Tripati et al., 2001), suggesting source fluids for spar components were either dominantly metamorphic (e.g., Hoefs, 2021) or were hydrothermal fluids undergoing significant water‐rock interactions in the subsurface (see above; see also Ferry & Gerdes, 1998; Taylor & Epstein, 1962). Localized impacts of hydrothermal fluids in these sediments are unsurprising, given the regional gradient in deformation across the basin (e.g., Figure 1b; Embry & Beauchamp, 2008).…”

Section: Discussionmentioning

confidence: 95%

Paleogene Paleohydrology of Ellesmere and Axel Heiberg Islands (Arctic Canada) From Palustrine Carbonates

Padgett,

Hyland,

West

et al. 2023

Paleoceanog and Paleoclimatol

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Ancient greenhouse periods are useful analogs for predicting effects of anthropogenic climate change on regional and global temperature and precipitation patterns. A paucity of terrestrial data from polar regions during warm episodes challenges our understanding of polar climate responses to natural/anthropogenic change and therefore our ability to predict future changes in precipitation. Ellesmere and Axel Heiberg Islands in the Canadian Arctic preserve terrestrial deposits spanning the late Paleocene to middle Eocene (59–45 Ma). Here we expand on existing regional sedimentology and paleontology through the addition of stable (δ13C, δ18O) and clumped (Δ47) isotope analyses on palustrine carbonates. δ13C isotope values range from −4.6 to +12.3‰ (VPDB), and δ18O isotope values range from −23.1 to −15.2‰ (VPDB). Both carbon and oxygen isotope averages decrease with increasing diagenetic alteration. Unusually enriched carbon isotope (δ13C) values suggest that analyzed carbonates experienced repeated dissolution‐precipitation enrichment cycles, potentially caused by seasonal fluctuations in water availability resulting in summer carbonate dissolution followed by winter carbonate re‐precipitation. Stable isotopes suggest some degree of precipitation seasonality or reduction in winter water availability in the Canadian Arctic during the Paleogene. Clumped (Δ47) temperature estimates range from 52 to 121°C and indicate low temperature solid‐state reordering of micritic samples and diagenetic recrystallization in sparry samples. Average temperatures agree with vitrinite reflectance data for Eureka Sound Group and underlying sediments, highlighting structural complexity across the region. Broadly, combined stable and clumped isotope data from carbonates in complex systems are effective for describing both paleoclimatic and post‐burial conditions.

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