scholarly journals The Boltysh impact structure: An early Danian impact event during recovery from the K-Pg mass extinction

2021 ◽  
Vol 7 (25) ◽  
pp. eabe6530
Author(s):  
Annemarie E. Pickersgill ◽  
Darren F. Mark ◽  
Martin R. Lee ◽  
Simon P. Kelley ◽  
David W. Jolley
Keyword(s):  
Mass Extinction ◽  
Crater Lake ◽  
Temporal Association ◽  
Earth System ◽  
Impact Event ◽  
The Earth ◽  
Relationship Of ◽  
Chicxulub Impact ◽  
The Impact ◽  
Impact Events

Both the Chicxulub and Boltysh impact events are associated with the K-Pg boundary. While Chicxulub is firmly linked to the end-Cretaceous mass extinction, the temporal relationship of the ~24-km-diameter Boltysh impact to these events is uncertain, although it is thought to have occurred 2 to 5 ka before the mass extinction. Here, we conduct the first direct geochronological comparison of Boltysh to the K-Pg boundary. Our 40Ar/39Ar age of 65.39 ± 0.14/0.16 Ma shows that the impact occurred ~0.65 Ma after the mass extinction. At that time, the climate was recovering from the effects of the Chicxulub impact and Deccan trap flood volcanism. This age shows that Boltysh has a close temporal association with the Lower C29n hyperthermal recorded by global sediment archives and in the Boltysh crater lake sediments. The temporal coincidence raises the possibility that even a small impact event could disrupt recovery of the Earth system from catastrophic events.

scholarly journals Globally distributed iridium layer preserved within the Chicxulub impact structure

2021 ◽  
Vol 7 (9) ◽  
pp. eabe3647
Author(s):  
Steven Goderis ◽  
Honami Sato ◽  
Ludovic Ferrière ◽  
Birger Schmitz ◽  
David Burney ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Depositional Environment ◽  
Hypervelocity Impact ◽  
Impact Structure ◽  
Impact Event ◽  
Post Impact ◽  
Temporal Horizon ◽  
Chicxulub Impact ◽  
The Impact ◽  
Globally Distributed

The Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of iridium, emplaced by a hypervelocity impact event 66 million years ago. Here, we report new data from four independent laboratories that reveal a positive iridium anomaly within the peak-ring sequence of the Chicxulub impact structure, in drill core recovered by IODP-ICDP Expedition 364. The highest concentration of ultrafine meteoritic matter occurs in the post-impact sediments that cover the crater peak ring, just below the lowermost Danian pelagic limestone. Within years to decades after the impact event, this part of the Chicxulub impact basin returned to a relatively low-energy depositional environment, recording in unprecedented detail the recovery of life during the succeeding millennia. The iridium layer provides a key temporal horizon precisely linking Chicxulub to K-Pg boundary sections worldwide.

scholarly journals Seasonal calibration of the end-cretaceous Chicxulub impact event

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Robert A. DePalma ◽  
Anton A. Oleinik ◽  
Loren P. Gurche ◽  
David A. Burnham ◽  
Jeremy J. Klingler ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Insect Behavior ◽  
Global Scale ◽  
Impact Event ◽  
Growth Band ◽  
Isotopic Analyses ◽  
Timing Data ◽  
Post Impact ◽  
Chicxulub Impact ◽  
The Impact

AbstractThe end-Cretaceous Chicxulub impact triggered Earth’s last mass-extinction, extinguishing ~ 75% of species diversity and facilitating a global ecological shift to mammal-dominated biomes. Temporal details of the impact event on a fine scale (hour-to-day), important to understanding the early trajectory of mass-extinction, have largely eluded previous studies. This study employs histological and histo-isotopic analyses of fossil fish that were coeval with a unique impact-triggered mass-death assemblage from the Cretaceous-Paleogene (KPg) boundary in North Dakota (USA). Patterns of growth history, including periodicity of ẟ18O and ẟ13C and growth band morphology, plus corroborating data from fish ontogeny and seasonal insect behavior, reveal that the impact occurred during boreal Spring/Summer, shortly after the spawning season for fish and most continental taxa. The severity and taxonomic symmetry of response to global natural hazards are influenced by the season during which they occur, suggesting that post-impact perturbations could have exerted a selective force that was exacerbated by seasonal timing. Data from this study can also provide vital hindsight into patterns of extant biotic response to global-scale hazards that are relevant to both current and future biomes.

The Kara astrobleme size, age and potential paleo-ecological effects of the impact event (European Arctic Zone, Russia)

2021 ◽  
Author(s):  
Tatyana Shumilova
Keyword(s):  
Mass Extinction ◽  
Black Shales ◽  
Ecological Effects ◽  
Impact Event ◽  
Arctic Zone ◽  
Russian Science ◽  
Future Possibility ◽  
Impact Melt ◽  
European Arctic ◽  
The Impact

<p>The Kara astrobleme is one of the biggest meteoritic craters which is set at the Baydarata Bay of the Kara sea (European Arctic Zone, Russia). It is a result of the catastrophic impact event occurred close to the K/Т extinction. The Kara astrobleme is the largest European crater at the modern erosion level.  At present it is estimated with the diameter from rim to rim about 65 km. While, some scientists have proposed its larger initial size – up to 120 km diameter, but no any well presented proof has been provided for the hypothesis. In 2015-2019 we have provided wide geological observations at the Kara crater and the near-set Ust`-Kara area (UKA) impactites. We have found for the first time that the UKA impactites, described in earlier Russian scientists publications as a synchronic independent crater of the same bolide, can be presented with bottom-flow impactites from the Kara crater (Shumilova et al., 2020). The found bottom-flow impactites abundant with belt-like impact melt bodies enriched in coesite and liquation structures similar to the Kara UHPHT vein and vein-like melt bodies with UHPHT impact glasses. Thus, they belong to UHPHT impactites. According to our air-bird view observations and impactites outcrops description at the UKA we support the hypothesis of the larger Kara crater getting 100-120 km in diameter of the initially originated size. Such giant meteorite event should be followed by catastrophic effects at the planet level, such as mass extinction. The present accepted Kara impact event age followed by the most recent measurements by <sup>40</sup>Ar-<sup>39</sup>Ar method is equal to 70.3 ± 2.2 Ma (Trieloff et al., 1998), that is a bit earlier than the Cretaceous/Tertiary boundary (K/Т) mass extinction at 66 Ma. But, previously, Kara age has been proposed by 65.7 Ma as a probable K/T impact (Kolesnikov et al., 1988; Nazarov et al., 1992). According to different data, the Kara event age lies within the range from 60 to 81 Ma (Masaitis & Mashchak, 1982; Nazarov et al., 1989; Kolesniov et al., 1990; Koeberl et al., 1990). It is clear that the accuracy of the age measurements depend on the quality of the studied samples, including their crystallinity, velocity of impact melt cooling and alteration, and from the used type of a method. By the moment, we have found out “in situ” crystallized zircons within the just discovered real UHPHT impact melt glasses (Shumilova et al., 2018, 2020). The UHPHT glasses do not have any alteration, thus, they can be used for accurate age measurements. Taking a future possibility for more accurate age analysis in the nearest future we can propose a correct vision of the possibility of the giant Kara influence to K-T mass extinction or other ecological effects. In any case following to the giant size of the Kara event touched the sedimentary rocks abundant with black shales and carbonates, which should be a result of essential atmospheric changes. The study has been supported by the Russian Science Foundation project #17-17-01080.</p>

scholarly journals Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact

2019 ◽  
Vol 116 (45) ◽  
pp. 22500-22504 ◽  
Author(s):  
Michael J. Henehan ◽  
Andy Ridgwell ◽  
Ellen Thomas ◽  
Shuang Zhang ◽  
Laia Alegret ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Ocean Acidification ◽  
Carbon Isotope ◽  
Primary Productivity ◽  
Deep Sea ◽  
Mass Extinction ◽  
System Modeling ◽  
Earth System ◽  
Ph Gradients ◽  
Chicxulub Impact

Mass extinction at the Cretaceous–Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as a mechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.

scholarly journals Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM): comparison with measurements and model simulations

2020 ◽  
Vol 20 (2) ◽  
pp. 829-863 ◽  
Author(s):  
Adeyemi A. Adebiyi ◽  
Jasper F. Kok ◽  
Yang Wang ◽  
Akinori Ito ◽  
David A. Ridley ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Global Model ◽  
Earth System ◽  
Atmospheric Dust ◽  
Global Models ◽  
Model Simulations ◽  
Extinction Efficiency ◽  
Dust Size Distribution ◽  
The Earth ◽  
Mass Extinction Efficiency

Abstract. Mineral dust is the most abundant aerosol species by mass in the atmosphere, and it impacts global climate, biogeochemistry, and human health. Understanding these varied impacts on the Earth system requires accurate knowledge of dust abundance, size, and optical properties, and how they vary in space and time. However, current global models show substantial biases against measurements of these dust properties. For instance, recent studies suggest that atmospheric dust is substantially coarser and more aspherical than accounted for in models, leading to persistent biases in modelled impacts of dust on the Earth system. Here, we facilitate more accurate constraints on dust impacts by developing a new dataset: Dust Constraints from joint Observational-Modelling-experiMental analysis (DustCOMM). This dataset combines an ensemble of global model simulations with observational and experimental constraints on dust size distribution and shape to obtain more accurate constraints on three-dimensional (3-D) atmospheric dust properties than is possible from global model simulations alone. Specifically, we present annual and seasonal climatologies of the 3-D dust size distribution, 3-D dust mass extinction efficiency at 550 nm, and two-dimensional (2-D) atmospheric dust loading. Comparisons with independent measurements taken over several locations, heights, and seasons show that DustCOMM estimates consistently outperform conventional global model simulations. In particular, DustCOMM achieves a substantial reduction in the bias relative to measured dust size distributions in the 0.5–20 µm diameter range. Furthermore, DustCOMM reproduces measurements of dust mass extinction efficiency to almost within the experimental uncertainties, whereas global models generally overestimate the mass extinction efficiency. DustCOMM thus provides more accurate constraints on 3-D dust properties, and as such can be used to improve global models or serve as an alternative to global model simulations in constraining dust impacts on the Earth system.

In-situ observation of damage evolution in polycarbonate subjected to hypervelocity impact

2019 ◽  
Author(s):  
Nobuaki Kawai ◽  
Mikio Nagano ◽  
Sunao Hasegawa ◽  
Eiichi Sato
Keyword(s):  
Real Time ◽  
Stress Wave ◽  
Damage Evolution ◽  
Impact Damage ◽  
Hypervelocity Impact ◽  
The Other ◽  
Impact Event ◽  
Real Time Imaging ◽  
The Impact ◽  
Impact Events

Abstract In the fields of space engineering and planetary science, hypervelocity impact phenomena have been studied as they relate to the space debris problem and planetary impact. With regard to hypervelocity-impact-induced damage, many studies focus on the evaluation of impact-damage geometry and morphology, for example, to construct the ballistic limit equations and/or penetrating equations for space structures, and to predict the size and shape of crater and fragments generated by planetary impact [1-4]. While the final state or late stage of an impact event are of primal interest, damage accumulation at early stages affect the overall outcome of the impact event. The understanding of hypervelocity-impact-damage processes lead to improvement of material-response models for hypervelocity impact and higher fidelity simulations of hypervelocity impact events. Under such a background, we have performed real-time imaging of hypervelocity-impact events on transparent materials to investigate the impact-damage formation and evolution processes [5-7]. In our previous work, the stress-wave-propagation behavior and damage evolution were observed by means of a transmitted light shadowgraph. In these measurements, the shape of the longitudinal-stress-wave front, crater and spall fracture were successfully visualized. On the other hand, these shadowgraph images provide little information about damage microstructure. The shadowgraph has difficulty in visualizing ramped waves, such as the release wave, and also for the shear wave which is not accompanied by the change of volumetric strain. Those play important role in initiating damage. This occurs because the intensity of the shadowgraph image depends on the second spatial derivative of the refractive index. In this study, we try two types of real-time imaging of impact events. One is imaging by using scattered light on the impacted target to visualize the microstructure of the impact-induced damage, the other is a shadowgraph using polarized light to visualize propagation of the impact-induced stress field.

scholarly journals Labor as Action: the Human Condition in the Anthropocene

2020 ◽  
Vol 50 (2) ◽  
pp. 240-260
Author(s):  
Ari-Elmeri Hyvönen
Keyword(s):  
Political Thought ◽  
Current Knowledge ◽  
Human Condition ◽  
Ecological Safety ◽  
Earth System ◽  
The Earth ◽  
Capacity To Act ◽  
Gravitational Pull ◽  
The Impact ◽  
The Human Condition

Abstract The Anthropocene has become an umbrella term for the disastrous transgression of ecological safety boundaries by human societies. The impact of this new reality is yet to be fully registered by political theorists. In an attempt to recalibrate the categories of political thought, this article brings Hannah Arendt’s framework of The Human Condition (labor, work, action) into the gravitational pull of the Anthropocene and current knowledge about the Earth System. It elaborates the historical emergence of our capacity to “act in the mode of laboring” during fossil-fueled capitalist modernity, a form of agency relating to our collectively organized laboring processes reminiscent of the capacity of modern sciences to “act into nature” discussed by Arendt. I argue that once read from an energy/ecology-centric perspective, The Human Condition can help us make sense of the Anthropocene predicament, and rethink the modes of collectively organizing the activities of labor, work, and action.

scholarly journals Potential of Virtual Earth Observation Constellations in Archaeological Research

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4066 ◽  
Author(s):  
Agapiou ◽  
Alexakis ◽  
Hadjimitsis
Keyword(s):  
Satellite Images ◽  
Earth Observation ◽  
Archaeological Research ◽  
Earth System ◽  
Ground Segment ◽  
The Earth ◽  
Integrated Optical ◽  
Earth Observation Satellites ◽  
The Impact ◽  
Research World

Earth observation sensors continually provide datasets with different spectral and spatial characteristics, while a series of pre- and postprocessing techniques are needed for calibration purposes. Nowadays, a variety of satellite images have become accessible to researchers, while big data cloud platforms allow them to deal with an extensive number of datasets. However, there is still difficulty related to these sensors meeting specific needs and challenges such as those of cultural heritage and supporting archaeological research world-wide. The harmonization and synergistic use of different sensors can be used in order to maximize the impact of earth observation sensors and enhance their benefit to the scientific community. In this direction, the Committee on Earth Observation Satellites (CEOS) has proposed the concept of virtual constellations, which is defined as “a coordinated set of space and/or ground segment capabilities from different partners that focuses on observing a particular parameter or set of parameters of the Earth system”. This paper provides an overview of existing and future earth observation sensors, the various levels of interoperability as proposed by Wulder et al., and presents some preliminary results from the Thessalian plain in Greece using integrated optical and radar Sentinel images. The potential for archaeolandscape studies using virtual constellations is discussed here.

Deposition and age of Chicxulub impact spherules on Gorgonilla Island, Colombia

2019 ◽  
Vol 132 (1-2) ◽  
pp. 215-232
Author(s):  
Paula Mateo ◽  
Gerta Keller ◽  
Thierry Adatte ◽  
André M. Bitchong ◽  
Jorge E. Spangenberg ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Tectonic Activity ◽  
Sea Level Fluctuations ◽  
Variable Extent ◽  
Stratigraphic Position ◽  
Radiolarian Biostratigraphy ◽  
Absolute Age ◽  
Chicxulub Impact ◽  
The Impact ◽  
Primary Impact

AbstractThe end-Cretaceous mass extinction (66 Ma) has long been associated with the Chicxulub impact on the Yucatan Peninsula. However, consensus on the age of this impact has remained controversial because of differing interpretations on the stratigraphic position of Chicxulub impact spherules relative to the mass extinction horizon. One side argues that the impact occurred precisely at the Cretaceous-Paleogene boundary, thus coinciding with the mass extinction; the other side argues that the impact predated the Cretaceous-Paleogene boundary, based on the discovery of primary impact spherules deposits in NE Mexico and Texas near the base of planktic foraminiferal zone CF1, dated at 170 k.y. before the Cretaceous-Paleogene boundary. A recent study of the most pristine Chicxulub impact spherules discovered on Gorgonilla Island, Colombia, suggested that they represent a primary impact deposit with an absolute age indistinguishable from the Cretaceous-Paleogene boundary. Here, we report on the Gorgonilla section with the main objective of evaluating the nature of deposition and age of the spherule-rich layer relative to the Cretaceous-Paleogene boundary.The Gorgonilla section consists of light gray-yellow calcareous siliceous mudstones (pelagic deposits) alternating with dark olive-brown litharenites (turbidites). A 3-cm-thick dark olive-green spherule-rich layer overlies an erosional surface separating Maastrichtian and Danian sediments. This layer consists of a clast-supported, normally graded litharenite, with abundant Chicxulub impact glass spherules, lithics (mostly volcanic), and Maastrichtian as well as Danian microfossils, which transitions to a calcareous mudstone as particle size decreases. Mineralogical analysis shows that this layer is dominated by phyllosilicates, similar to the litharenites (turbidites) that characterize the section. Based on these results, the spherule-rich layer is interpreted as a reworked early Danian deposit associated with turbiditic currents. A major hiatus (>250 k.y.) spanning the Cretaceous-Paleogene boundary and the earliest Danian is recorded at the base of the spherule-rich layer, based on planktic foraminiferal and radiolarian biostratigraphy and carbon stable isotopes. Erosion across the Cretaceous-Paleogene boundary has been recorded worldwide and is generally attributed to rapid climate changes, enhanced bottom-water circulation during global cooling, sea-level fluctuations, and/or intensified tectonic activity. Chicxulub impact spherules are commonly reworked and redeposited into younger sediments overlying a Cretaceous-Paleogene boundary hiatus of variable extent in the Caribbean, Central America, and North Atlantic, while primary deposits are rare and only known from NE Mexico and Texas. Because of their reworked nature, Gorgonilla spherules provide no stratigraphic evidence from which the timing of the impact can be inferred.

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