Isotopic evidence from a Brazos River (Texas, USA) Cretaceous/Paleogene boundary section consistent with a pulse of greenhouse warming shortly after the Chicxulub impact
MacLeod, K. G., Huber, B. T., Tabor, C., Mitra, S., Wheatley, R., et al. (2025). Isotopic evidence from a Brazos River (Texas, USA) Cretaceous/Paleogene boundary section consistent with a pulse of greenhouse warming shortly after the Chicxulub impact. Global and Planetary Change, doi:https://doi.org/10.1016/j.gloplacha.2025.104924
| Title | Isotopic evidence from a Brazos River (Texas, USA) Cretaceous/Paleogene boundary section consistent with a pulse of greenhouse warming shortly after the Chicxulub impact |
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| Genre | Article |
| Author(s) | K. G. MacLeod, B. T. Huber, C. Tabor, S. Mitra, R. Wheatley, C. Harrison, M. Tessler, Charles Bardeen, N. S. Lovenduski, J. Sepúlveda, J. Coupe, S. Hu |
| Abstract | Stable isotopic analyses of individual specimens of the benthic foraminifera Lenticulina show an ∼1 ‰ decrease in δ18O values beginning 170 cm above the K/Pg boundary at the Brazos River ‘River Bank South’ Cretaceous/Paleogene (K/Pg) outcrop. This negative δ18O shift is most rigorously documented by analyses of visually screened fragments of gently crushed specimens. Scanning electron microscope images of broken specimens confirm that excellent test preservation is present throughout the section. Parallel δ18O analyses of other separates (specimens infilled with secondary carbonate, isolated secondary carbonate, and test fragments that failed visual screening) are offset by −1 ‰ to −3 ‰ from the clean fragments reinforcing arguments that clean foraminiferal fragments preserve depositional values.The negative δ18O excursion begins within the P0 planktonic foraminiferal zone, which spans the interval from the K/Pg boundary to 270 cm above the boundary where Parvularugoglobigerina eugubina, the zonal marker for the base of the overlying Pα Zone, first appears. Thus, the ∼5 °C warming pulse suggested by the 1 ‰ decrease in δ18O values would have started during the first few millennia after the Chicxulub impact. A number of events and excursions documented in Brazos River K/Pg sections further suggest sedimentation rates were very high during deposition of the lowest 1.5 to 2 m of strata above the K/Pg boundary at the River Bank South locality. Such high accumulation rates allow the possibility that the warming pulse began within decades of the impact. |
| Publication Title | Global and Planetary Change |
| Publication Date | Oct 1, 2025 |
| Publisher's Version of Record | https://doi.org/10.1016/j.gloplacha.2025.104924 |
| OpenSky Citable URL | https://n2t.net/ark:/85065/d7cj8jxt |
| OpenSky Listing | View on OpenSky |
| NCAR Affiliations | ACOM, ACOMVISITORS |