Creationism in Crisis - Scientists Identify a Possible Cause of a Mass Extinction - 201 Million Years Before 'Creation Week'

An algal bloom

Ichthyosaurs, marine reptiles that went extinct during the Triassic–Jurassic mass extinction.

Deoxygenation levels similar to today’s played key role in marine extinctions during major past climate change event - News & Events | Trinity College Dublin

201 million years before creationists believe Earth was created, something happened to cause one of the pivotal moments in Earth's long 'pre-Creation' history, when very many species went extinct, providing the opportunity for the few survivors to evolve to occupy the vacant niches, so putting the evolutionary trajectory of Earth's ecosystems on a course that led us to where we are today.

This was the Triassic–Jurassic mass extinction.

Tell me all about the Triassic–Jurassic mass extinction. The Triassic-Jurassic mass extinction, which occurred approximately 201 million years ago, marked the transition between the Triassic and Jurassic periods during the Mesozoic Era. This event was one of the several major mass extinctions in Earth's history and had significant impacts on terrestrial and marine ecosystems. Here are some key aspects of the Triassic-Jurassic mass extinction:

Causes:

1. Volcanic Activity: The eruption of the Central Atlantic Magmatic Province (CAMP) is considered a primary cause of the extinction event. Massive volcanic activity released large amounts of greenhouse gases, such as carbon dioxide and sulfur dioxide, into the atmosphere, leading to global warming and changes in climate.
2. Climate Change: The volcanic emissions contributed to a greenhouse effect, causing a rise in temperatures and shifts in climate patterns. These environmental changes likely had cascading effects on ecosystems, affecting both terrestrial and marine life.

Environmental Changes:

1. Global Warming: The increased greenhouse gases led to a warming of the planet. This rise in temperature may have disrupted ecosystems and affected the distribution of species.
2. Sea Level Changes: The volcanic activity could have also caused changes in sea levels, impacting marine environments and coastal ecosystems.

Effects on Life:

1. Terrestrial Extinctions: The Triassic-Jurassic mass extinction significantly affected terrestrial ecosystems. Many reptile groups, including some large archosaurs (such as rauisuchians), experienced declines, while some smaller dinosaurs and mammals survived and diversified in the Jurassic period.
2. Marine Extinctions: Marine life was also profoundly affected. The extinction event had a significant impact on marine reptiles, such as ichthyosaurs and placodonts. Some groups of ammonites and bivalves also suffered losses.
3. Opportunity for Evolution: While many species went extinct, the extinction event also created opportunities for the evolution and diversification of surviving organisms. Some groups that managed to survive experienced adaptive radiations and expanded into vacant ecological niches.

Duration and Recovery:

1. Duration: The Triassic-Jurassic mass extinction was relatively gradual, taking place over a span of several hundred thousand years.
2. Recovery: Following the extinction event, the Jurassic period witnessed the diversification of various groups, including dinosaurs, marine reptiles, and mammals. The Jurassic is often considered an era of recovery and the beginning of the dominance of dinosaurs.

In summary, the Triassic-Jurassic mass extinction was a pivotal event in Earth's history, leading to significant changes in terrestrial and marine ecosystems and paving the way for the dominance of certain groups in the Jurassic period. The complex interplay of volcanic activity, climate change, and associated environmental disruptions contributed to this mass extinction event.

Exactly what caused it has been a matter for speculation and competing theories, but now, an international research team led by scientists from Royal Holloway (UK), and including scientists from Trinity College Dublin’s School of Natural Sciences (Ireland) as well as from Utrecht University (Netherlands), believe they have identified the cause. They did this by using chemical data from ancient mudstone deposits obtained from drill-cores in Northern Ireland and Germany.

They found evidence of pulses of local marine deoxygenation along the edges of continental shelves which disrupted ecosystems locally, leading to a wider collapse of marine ecosystems.

The team have published their findings in Nature Geoscience. A press release from Trinity College Dublin, explains the research:

Newly published research serves as a further warning that present day marine ecosystem stability is likely more fragile than apparent. And marine deoxygenation is projected to significantly increase in response to global warming and increased nutrient run-off from continents.

Scientists have made a surprising discovery that sheds new light on the role that oceanic deoxygenation (anoxia) played in one of the most devastating extinction events in Earth’s history. Their finding has implications for current day ecosystems – and serves as a warning that marine environments are likely more fragile than apparent.

New research, published today in leading international journal Nature Geosciences, suggests that oceanic anoxia played an important role in ecosystem disruption and extinctions in marine environments during the Triassic–Jurassic mass extinction, a major extinction event that occurred around 200 million years ago.

Surprisingly however, the study shows that the global extent of euxinia (an extreme form of de-oxygenated conditions) was similar to the present day.

Earth’s history has been marked by a handful of major mass extinctions, during which global ecosystems collapsed and species went extinct. All past extinction events appear to have coincided with global climatic and environmental perturbance that commonly led to ocean deoxygenation.

Because of this, oceanic anoxia has been proposed as a likely cause of marine extinctions at those times, with the assumption that the more widespread occurrence of deoxygenation would have led to a larger extinction event.

Using chemical data from ancient mudstone deposits obtained from drill-cores in Northern Ireland and Germany, an international research team led by scientists from Royal Holloway (UK), and including scientists from Trinity College Dublin’s School of Natural Sciences (Ireland) as well as from Utrecht University (Netherlands), was able to link two key aspects associated with the Triassic–Jurassic mass extinction.

Samples of the Carnduff cores (here studied), which were drilled in the Larne Basin, Northern Ireland.

The team discovered that pulses in deoxygenation in shallow marine environments along the margins of the European continent at that time directly coincided with increased extinction levels in those places.

On further investigation – and more importantly – the team also found that the global extent of extreme deoxygenation was rather limited, and similar to the present day.

Scientists have long suspected that ocean deoxygenation plays an important role in the disturbance of marine ecosystems, which can lead to the extinction of species in marine environments. The study of past time intervals of extreme environmental change indeed shows this to be the case, which teaches us important lessons about potential tipping points in local, as well as global ecosystems in response to climatic forcing.

Crucially however, the current findings show that even when the global extent of deoxygenation is similar to the present day, the local development of anoxic conditions and subsequent locally increased extinction rates can cascade in widespread or global ecosystem collapse and extinctions, even in areas where deoxygenation did not occur.

It shows that global marine ecosystems become vulnerable, even when only local environments along the edges of the continents are disturbed. Understanding such processes is of paramount importance for assessing present day ecosystem stability, and associated food supply, especially in a world where marine deoxygenation is projected to significantly increase in response to global warming and increased nutrient run-off from continents.

Professor Micha Ruhl, co-author
Assistant Professor
Trinity’s School of Natural Sciences
Trinity College, Dublin, Ireland.

A core sample of ~201 million year old sediments obtained from the Carnduff-2 core, drilled in the Larne Basin (Northern Ireland), showing the shell of an animal that lived on the seabed shortly after the Triassic–Jurassic global mass extinction.

The study of past global change events, such as at the transition between the Triassic and Jurassic periods, allows scientists to disentangle the consequences of global climatic and environmental change and constrain fundamental Earth system processes that control tipping points in Earth’s ecosystems.

Technical detail is given in the paper published in Nature Geoscience:

Abstract

One of the most severe extinctions of complex marine life in Earth’s history occurred at the end of the Triassic period (~201.4 million years ago). The marine extinction was initiated by large igneous province volcanism and has tentatively been linked to the spread of anoxic conditions. However, the global-scale pattern of anoxic conditions across the end-Triassic event is not well constrained. Here we use the sedimentary enrichment and isotopic composition of the redox-sensitive element molybdenum to reconstruct global–local marine redox conditions through the extinction interval. Peak δ⁹⁸Mo values indicate that the global distribution of sulfidic marine conditions was similar to the modern ocean during the extinction interval. Meanwhile, Tethyan shelf sediments record pulsed, positive δ⁹⁸Mo excursions indicative of locally oxygen-poor, sulfidic conditions. We suggest that pulses of severe marine de-oxygenation were restricted largely to marginal marine environments during the latest Triassic and played a substantial role in shallow-marine extinction phases at that time. Importantly, these results show that global marine biodiversity, and possibly ecosystem stability, were vulnerable to geographically localized anoxic conditions. Expanding present-day marine anoxia in response to anthropogenic marine nutrient supply and climate forcing may therefore have substantial consequences for global biodiversity and wider ecosystem stability.

Bond, A.D., Dickson, A.J., Ruhl, M. et al.
Globally limited but severe shallow-shelf euxinia during the end-Triassic extinction.
Nat. Geosci. (2023). https://doi.org/10.1038/s41561-023-01303-2

Copyright: © 2023 The authors.
Published by Springer Nature Ltd. Open access
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

Perhaps this warrants a brief explanation of how molybdenum isotopes can be used as a historic record of marine oxygenation:

How is molybdenum used to reconstruct global–local marine redox conditions? Molybdenum (Mo) is an element that can be used as a proxy to reconstruct past marine redox conditions, specifically in the context of paleoceanography and sedimentary geology. The redox conditions refer to the prevailing oxidation-reduction states of the environment, particularly in marine sediments. The concentration and isotopic composition of molybdenum in sedimentary rocks and marine sediments can provide valuable information about the history of oxygen availability in Earth's oceans. Here's how molybdenum is used in reconstructing global-local marine redox conditions:

1. Molybdenum Concentrations:
   • Low Oxygen Conditions: Molybdenum is often associated with low-oxygen or anoxic conditions in marine environments. In the absence of oxygen, molybdenum is more soluble and tends to accumulate in sediments. Therefore, higher concentrations of molybdenum in sedimentary rocks may indicate periods of low oxygen or anoxia in the past.
   • Pyrite Formation: Molybdenum is also linked to the formation of pyrite (iron sulfide) in sediments. Under low-oxygen conditions, pyrite can form, and molybdenum is often incorporated into pyrite crystals. Thus, the presence of molybdenum in pyrite is indicative of reducing (low-oxygen) conditions.
2. Molybdenum Isotopes:
   • Isotopic Fractionation: Isotopic analysis of molybdenum can provide information about the redox state of the environment. Molybdenum isotopes can be fractionated under different redox conditions, and variations in isotopic composition can be used to infer changes in oxygen availability.
   • Oxidation States: Molybdenum exists in multiple oxidation states (from Mo(II) to Mo(VI)), and the ratio of different isotopes (such as ⁹⁸Mo/⁹⁵Mo) can be sensitive to the oxidation state of the environment. Changes in isotopic ratios can be interpreted as variations in marine redox conditions over time.
3. Paleoredox Indicators:
   • Black Shales: Molybdenum is often associated with the formation of black shales, which are organic-rich sediments deposited under low-oxygen conditions. Black shales can serve as a geological record of past anoxic events, and the presence of molybdenum is one of the indicators used to identify these conditions.
   • Sulfur Isotopes: Combined with sulfur isotopic analysis, molybdenum data can help in understanding the dynamics of marine redox conditions and the presence of specific microbial processes.

In summary, the concentration and isotopic composition of molybdenum in sedimentary rocks and marine sediments are powerful tools for reconstructing past marine redox conditions. By studying molybdenum patterns, researchers can gain insights into the history of oxygen availability in Earth's oceans and the factors influencing marine ecosystems over geological time scales. This information is crucial for understanding past climate dynamics, oceanic circulation, and the evolution of marine life.

How does oxidation of molybdenum change the isotope ratios?

The oxidation of molybdenum can lead to changes in its isotope ratios, and these variations are often used as indicators of redox conditions in the environment. Molybdenum exists in multiple oxidation states, including Mo(II), Mo(IV), and Mo(VI), and the isotope ratios can be sensitive to the oxidation state. Here's a simplified explanation of how the oxidation of molybdenum affects its isotope ratios:

1. Molybdenum Isotopes:
   • Molybdenum has several isotopes, with ⁹⁸Mo and ⁹⁵Mo being the most relevant for paleoredox studies.
   • The stable isotopes ⁹⁸Mo and ⁹⁵Mo can undergo fractionation, meaning that the relative abundance of these isotopes can vary in different geochemical processes.
2. Oxidation States and Isotope Fractionation:
   • Different oxidation states of molybdenum exhibit different preferences for isotopic fractionation. Isotopic fractionation refers to the preferential enrichment or depletion of certain isotopes during chemical processes.
   • Generally, lighter isotopes tend to be preferentially incorporated into oxidized forms of molybdenum, while heavier isotopes are enriched in reduced forms.
3. Reduction and Enrichment:
   • Under reducing (low-oxygen) conditions, molybdenum tends to be in its reduced forms (e.g., Mo(IV) or Mo(II)). During reduction processes, the lighter ⁹⁸Mo isotope may be preferentially incorporated into molybdenum compounds, leading to a relatively lower ⁹⁸Mo/⁹⁵Mo ratio.
   • Conversely, under oxidizing (high-oxygen) conditions, molybdenum tends to be in its oxidized forms (e.g., Mo(VI)). In oxidizing environments, the lighter ⁹⁸Mo isotope may be preferentially released or enriched, leading to a higher ⁹⁸Mo/⁹⁵Mo ratio.
4. Recording Redox Conditions:
   • The variations in the ⁹⁸Mo/⁹⁵Mo ratio can be used as a proxy for redox conditions in ancient environments. Anomalously high or low ⁹⁸Mo/⁹⁵Mo ratios in sedimentary rocks or marine sediments can indicate periods of oxygen depletion or enrichment in the Earth's past.
5. Applications in Paleoredox Studies:
   • Researchers use molybdenum isotope ratios in conjunction with other geochemical proxies to reconstruct past redox conditions in marine environments. This information helps in understanding the dynamics of oxygen availability, ocean circulation, and the evolution of marine ecosystems over geological time scales.

In summary, the oxidation of molybdenum can lead to variations in its isotope ratios, and these variations are indicative of past redox conditions in marine environments. Analyzing the isotopic composition of molybdenum in sedimentary rocks and marine sediments provides valuable insights into the history of oxygen availability in Earth's oceans and the environmental changes that occurred over geological time.

Creationists should note that this has nothing to do with radiometric dating or radioactive decay rates, so the question is, why do these changing ratio of ⁹⁸Mo/⁹⁵Mo form discrete bands in local mudstone deposits if, as creationist superstition dictates, all sedimentary deposits were laid down in a year, about 4,000 years ago during a global flood, when, if it had happened, these isotopes would have been evenly distributes both geographically and stratigraphically?

They weren't formed is a single flood event of course, but over time on continental shelves, in conditions in which oxygen levels changed locally.

The question creationists need to answer is why changes in marine oxygenation left this isotopic record 201 million years before 'Creation Week' and why deoxygenation led to a mass extinction of so many species that, according to creationism, hadn't be magicked into existence at that point in Earth's long 'pre-Creation' history.

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