Rosa Rubicondior: Refuting Creationism - How Sealife Recovered From Disaster

Refuting Creationism

How Sealife Recovered From Disaster
66 Million Years Before 'Creation Week'

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Life Recovered Rapidly at Site of Dino-Killing Asteroid. A Hydrothermal System May Have Helped. | Jackson School of Geosciences | The University of Texas at Austin

A figure showing a hypothesized semi-enclosed environment created by post-impact hydrothermal activity.

Credit: Sato et al.

A recurring point in this blog is that 99.9975% of Earth's history occurred before the time creationists claim the Earth was magically created out of nothing by an immaterial deity. It is strange how, despite the overwhelming evidence contradicting their viewpoint and a notable absence of credible supporting evidence, creationism endures as a belief system.

This requires either a profound lack of scientific knowledge and understanding, or extraordinary mental gymnastics, to cope with the cognitive dissonance and dismiss the abundant contrary evidence. Advocates of creationism frequently attempt to rationalise away this evidence, attributing it to errors, falsifications, or even alleging a global conspiracy within the scientific community.

Recently, another piece of evidence undermining creationist claims emerged with the publication of a study in Nature Communications. The paper documents how marine life rapidly recovered at the site of the dinosaur-killing Chicxulub asteroid impact in the Gulf of Mexico, 66 million years before creationism's mythical 'Creation Week'.

This rapid recovery was facilitated by nutrient-rich waters resulting from hydrothermal activity triggered by the asteroid collision.

Creationists might not want to hear this because they have well-rehearsed excuses for dismissing radiometric dating, but the study depended on analyzing the ratios of stable osmium isotopes in sediments at the Chicxulub impact site. This analysis is not a form of radiometric dating; rather, it involves comparing the naturally occurring ratios of these isotopes from terrestrial and meteoritic sources to trace their origin. By correlating these isotopic variations with sediment depth, researchers have inferred the contribution of meteoritic material over time.

The timing of the Chicxulub impact has been corroborated through multiple independent methods, including high-precision uranium-lead (U-Pb) dating of zircon crystals. These zircons, found in impact-related deposits, provide robust age constraints that align with the established date of the event.

Can you explain the significance of the ¹⁸⁷Os/¹⁸⁸Os ratio in determining the contribution of the steroid Os to sea water at the impact site over time?

The ¹⁸⁷Os/¹⁸⁸Os ratio refers to comparing two isotopes of the metal osmium (Os) — osmium-187 and osmium-188. This ratio is valuable to scientists because it acts like a chemical fingerprint, helping them track where osmium in seawater originated.

Why osmium?
Osmium is present in rocks, particularly deep within the Earth's mantle, and has a very specific isotopic signature there (low ¹⁸⁷Os/¹⁸⁸Os ratio). Meanwhile, osmium from Earth's crust or from space (like a meteorite impact) typically has a different signature (often higher in ¹⁸⁷Os).
What does this tell us about the Chicxulub impact?
When the asteroid hit Chicxulub (Gulf of Mexico), it caused massive heating and geothermal activity. This event brought mantle rocks and the osmium they contained up to the ocean floor. By measuring changes in the ¹⁸⁷Os/¹⁸⁸Os ratio in sediments and water at the impact site, scientists can distinguish between osmium originating from deep Earth processes (hydrothermal activity) and osmium introduced from the meteorite itself.
Why does this matter?
Tracking how the osmium ratio changed over time helps researchers reconstruct the history of geological and biological recovery after the impact. An increase in mantle-derived osmium (distinct low ratios) indicates periods when nutrient-rich waters from geothermal activity surged into the ocean. These nutrient-rich waters supported rapid recovery of marine life, accelerating ecological regeneration after the catastrophic extinction event.
In short, the ¹⁸⁷Os/¹⁸⁸Os ratio acts like a natural tracer, allowing scientists to understand how quickly—and why—life rebounded in the ocean after one of Earth's most devastating impacts.

So the change in ratio is a proxy for changes in the upwelling of nutrients?

Exactly right.

The change in the ¹⁸⁷Os/¹⁸⁸Os ratio acts as a proxy—a measurable indicator—for periods when nutrient-rich waters were upwelling due to increased geothermal activity at the Chicxulub impact site. When the ratio shifts toward mantle-like values (lower ¹⁸⁷Os/¹⁸⁶Os), it signals increased hydrothermal activity, bringing nutrients from deep within the Earth to the ocean surface.

This nutrient-rich water significantly boosted biological productivity, aiding rapid ecological recovery. Thus, fluctuations in the osmium isotopic ratio directly reflect changes in nutrient supply and, consequently, ecological conditions in the aftermath of the asteroid impact.

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Additional details of this study are summarised in a news release from Texas Geosciences, the publication of the Jackson School of Geosciences at the University of Texas at Austin:

Life Recovered Rapidly at Site of Dino-Killing Asteroid. A Hydrothermal System May Have Helped.
About 66 million years ago, an asteroid slammed into the planet, wiping out all non-avian dinosaurs and about 70% of all marine species.

But the crater it left behind in the Gulf of Mexico was a literal hotbed for life enriching the overlying ocean for at least 700,000 years, according to research published today in Nature Communications.
Scientists have discovered that a hydrothermal system created by the asteroid impact may have helped marine life flourish at the impact site by generating and circulating nutrients in the crater environment.

After the asteroid impact, the Gulf of Mexico records an ecological recovery process that is quite different from that of the global ocean, as continuous hydrothermal activity has created a unique marine environment.

Assistant Professor Honami Sato, lead author.
Department of Earth and Planetary Sciences
Kyushu University, Fukuoka, Japan.

Study co-author Sean Gulick, a research professor at The University of Texas at Austin, with a core sample from the Chicxulub crater. In 2016, Gulick co-led a scientific drilling expedition to sample the crater.

Credit: The University of Texas at Austin, Jackson School of Geosciences.

Sean Gulick, a research professor at The University of Texas at Austin’s Jackson School of Geosciences, is a co-author on the study. In 2016, he co-led a scientific drilling expedition to the impact site, which is called Chicxulub, that recovered core samples from the crater.

The study is the latest discovery to come from research on the 829 meters of core retrieved by the international team of researchers.

Previous research already determined that life returned to the site of the crater within a matter of years. The new study presents evidence that a hydrothermal system created by the asteroid impact and its melt sheet buried beneath the seafloor likely played a role in its recovery and sustenance for hundreds of thousands of years.

We are increasingly learning about the importance of impact-generated hydrothermal systems for life. This paper is a step forward in showing the potential of an impact event to affect the overlying ocean for hundreds of thousands of years.

Professor Sean P. S. Gulick, co-author
Institute for Geophysics
Jackson School of Geosciences
University of Texas at Austin, Austin, TX, USA.

The research hinges on a chemical element called osmium. A particular ratio of osmium is associated with asteroid materials. The researchers found evidence that osmium from the asteroid buried kilometers beneath the impact crater was continuously released in the Gulf of Mexico due to submarine hydrothermal activity.

In other words, as hot water moved beneath the seafloor and up toward the surface, so did traces of the asteroid. As the hydrothermal fluid cooled over time, the asteroid traces exited the water and precipitated into sediment. The researchers analyzed the sediment, which was brought to the surface in the core samples, and used it to determine the extent of the hydrothermal system and how long the enrichment of osmium lasted.

The researchers also found that as the hydrothermal system ceased releasing osmium from the asteroid, the types of marine life living at the crater site changed. They found that when the hydrothermal system was releasing this osmium, the type of plankton found living in the environment were associated with high-nutrient environments. When the osmium returned to pre-impact levels, the plankton were associated with low-nutrient environments.

This finding indicates that the ecosystem was no longer being sustained by the nutrients from the hydrothermal system being released into the overlying ocean. However, beneath the seafloor the hydrothermal system continued to persist for many millions of years; it just became ever more deeply buried by millions of years of sedimentation.

This study reveals that impact cratering events, while primarily destructive, can in some cases also lead to significant hydrothermal activity. In the case of Chicxulub, this process played a vital role in the rapid recovery of marine ecosystems.

Professor Steven Goderis, co-author
Archaeology, Environmental Changes, and Geo-Chemistry
Vrije Universiteit Brussel, Brussels, Belgium.

With the demise of the dinosaurs, the Chicxulub impact is well known for its link to causing mass extinction. Gulick said that this research is important because it shows that this impact can be a catalyst for life, too. At the UT Center for Planetary Systems Habitability, Gulick is leading research on whether large impacts elsewhere in the solar system could help generate conditions that could sustain life on other planets or moons.

The science team included researchers from Kyushu University; the University of Texas at Austin’s Jackson School of Geosciences’ Department of Earth and Planetary Sciences and Institute for Geophysics; the Japan Agency for Marine-Earth Science and Technology; Vrije Universiteit Brussel, Belgium; Institute of Science Tokyo; Universidad de Zaragoza, Zaragoza, Spain; Universitat de Barcelona, Barcelona, Spain; and Imperial College London.

Abstract
The Cretaceous/Paleogene boundary asteroid impact is recorded globally as a negative ¹⁸⁷Os/¹⁸⁸Os excursion, including in sediments recovered from the IODP-ICDP drilling within the peak ring of the Chicxulub structure in the Gulf of Mexico. The reconstructed marine ¹⁸⁷Os/¹⁸⁸Os curves can be used for global age correlations on the ~10 kyr scale. However, the versatility of Os isotope clock between the proximal and distal sites remains unclear. This paper presents ¹⁸⁷Os/¹⁸⁸Os records from early Paleocene sediments deposited in the Chicxulub impact basin and Mexican sites with biochronological scales. The results for these proximal sites show a recovery timescale of ~700 kyr, which is significantly longer than that of the distal sites (~200 kyr). The interval showing the ¹⁸⁷Os/¹⁸⁸Os decline coincides with the enrichment of hydrothermally-derived Mn, implying that hydrothermal venting at the Chicxulub structure may have played a role in the marine chemistry and ecosystem of the Gulf of Mexico.

Introduction
The impact event at the Cretaceous-Paleogene (K/Pg) boundary, ~66 million years ago, formed the ~200-km diameter Chicxulub impact structure on the Yucatán Platform of the Gulf of Mexico^1,2,3,4, causing a mass extinction of over 70% of the fossil species^5,6,7. The decline and subsequent recovery of productivity in the marine ecosystem has been extensively studied in the K/Pg boundary sediments on a global scale^8,9,10,11. It has been proposed that the recovery of the global marine ecosystem, measured as primary productivity, was heterogeneous^12,13,14. Recent micropaleontological and geochemical studies of the impact site show a rapid recovery of both the local population and export production^15,16,17,18.

To understand post-impact changes in marine environments and ecosystems on a global scale, geochemical markers of the impact event, particularly highly siderophile element concentrations (HSEs: Os, Ir, Ru, Pt, Pd, and Re) and Os isotope ratios, can be used to accurately correlate K/Pg boundary sediments^5,19,20. The anomalous concentration of HSEs provides a key temporal horizon that precisely links Chicxulub to K/Pg boundary sections worldwide^7,21,22. Osmium isotope (¹⁸⁷Os/¹⁸⁸Os) records across the K/Pg boundary also constrain the time scale of the post-impact environmental recovery. Since the residence time of seawater Os (10–50 thousand years (kyr)^23,24) is longer than the time scale of modern oceanic circulation, seawater ¹⁸⁷Os/¹⁸⁸Os values are dominated by changes in whole-ocean chemistry and relatively constant throughout the global oceans. Seawater ¹⁸⁷Os/¹⁸⁸Os ratios reflect contributions to the global ocean from weathered continental crust (¹⁸⁷Os/¹⁸⁸Os = ~1.4), mantle and extraterrestrial inputs (¹⁸⁷Os/¹⁸⁸Os = ~0.12–0.13)²⁵. Detailed profiles of seawater ¹⁸⁷Os/¹⁸⁸Os ratios from the pelagic carbonate sections in the previous studies show similar Os isotope curves that drop sharply (¹⁸⁷Os/¹⁸⁸Os = ~0.17 to 0.2) at the K/Pg boundary and then recover to their original seawater values (¹⁸⁷Os/¹⁸⁸Os = ~0.4) over ~200 kyr^19,20,26. A model for the 200 kyr recovery of seawater ¹⁸⁷Os/¹⁸⁸Os in the distal sites was directly compared with age models based on biostratigraphy, magnetostratigraphy, and cyclostratigraphy, allowing independent estimates of stratigraphic time based on Os isotope analysis²⁰. The development of this Os isotope based geochemical clock²⁰ has broad implications for paleoceanographic research, providing a tool for global correlation of pelagic carbonate sequences across the K/Pg boundary, which makes it possible to elucidate the onset of biotic crisis and subsequent recovery. However, the seawater ¹⁸⁷Os/¹⁸⁸Os curve in the Gulf of Mexico has not been reported, and correlations using the K/Pg Os isotope clock between the proximal and distal sites remain unclear.

Here, Os isotope ratios are measured in the early Paleocene limestone samples obtained from the IODP-ICDP Expedition 364 at Site M0077 in the Chicxulub impact basin in the Gulf of Mexico and early Paleocene limestone, marl, and clay samples from several sections in northeastern and southeastern Mexico (El Mulato, La Lajilla, Bochil, and Guayal sections) to reconstruct the Os isotope reference curve in the Gulf of Mexico (Figs. 1, Supplementary Note 1)^22,27,28. Biostratigraphic correlations and calibrated ages between the Chicxulub site and the Mexican sections are calculated based on a biochronological scale relying on planktic foraminifera and astrochronological calibrations^29,30. The obtained HSE concentrations confirm the contribution of extraterrestrial materials in proximal sediments all around the Gulf of Mexico region. For comparison, Os isotope ratios and HSE concentrations are also analyzed in suevite (polymict melt-rich impact breccia), impact melt rock, and granitic samples underlying the Paleocene limestones at Site M0077 (Supplementary Figs. 1–3).
Fig. 1: Location map.

a Paleogeographic reconstruction for the K/Pg boundary (~66 Ma) showing the locations of the study site (IODP-ICDP Site M0077) within the Chicxulub impact basin and other pelagic sites reported for Os isotope profiles²⁰. This map is redrawn after ref. ⁶⁷ and ODSN generated at https://www.odsn.de/odsn/services/paleomap/paleomap.html. Note that this paleoreconstruction potentially represents the placement of tectonic blocks at ~66 Ma, but does not reflect sea level at the time of impact. b Geographic locations for the study site and sections within the Gulf of Mexico. Map modified after ref. ²⁸.

Sato, H., Ishikawa, A., Arenillas, I. et al.
Prolonged 187Os/188Os excursion implies hydrothermal influence after the Chicxulub impact in the Gulf of Mexico.
Nat Commun 16, 2901 (2025). https://doi.org/10.1038/s41467-025-58112-x

Copyright: © 2025 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

The evidence clearly demonstrates not only that a meteorite impact occurred approximately 66 million years ago but also that sea-life at the impact site quickly recovered and even thrived in the immediate aftermath, largely driven by hydrothermal activity generated by the event. Over the subsequent 200,000 years, biodiversity gradually returned to levels typical of the surrounding oceans.

Given the clarity and depth of evidence supporting Earth's ancient history, it is remarkable that creationist groups continue to keep their adherents unaware or in denial of such overwhelming facts. Despite this evidence, these groups persistently promote the belief that Earth is merely 6,000–10,000 years old, that all life appeared spontaneously within a single week, and has remained largely unchanged since.

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