ORCID Profile
0000-0002-6087-6149
Current Organisation
Imperial College London
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Planetary Science (excl. Extraterrestrial Geology) | Geology | Extraterrestrial Geology
Expanding Knowledge in the Earth Sciences | Emerging Defence Technologies | Integrated Systems |
Publisher: Wiley
Date: 02-01-2023
DOI: 10.1111/MAPS.13937
Abstract: Fusion crusts form during the atmospheric entry heating of meteorites and preserve a record of the conditions that occurred during deceleration in the atmosphere. The fusion crust of the Winchcombe meteorite closely resembles that of other stony meteorites, and in particular CM2 chondrites, since it is dominated by olivine phenocrysts set in a glassy mesostasis with magnetite, and is highly vesicular. Dehydration cracks are unusually abundant in Winchcombe. Failure of this weak layer is an additional ablation mechanism to produce large numbers of particles during deceleration, consistent with the observation of pulses of plasma in videos of the Winchcombe fireball. Calving events might provide an observable phenomenon related to meteorites that are particularly susceptible to dehydration. Oscillatory zoning is observed within olivine phenocrysts in the fusion crust, in contrast to other meteorites, perhaps owing to temperature fluctuations resulting from calving events. Magnetite monolayers are found in the crust, and have also not been previously reported, and form discontinuous strata. These features grade into magnetite rims formed on the external surface of the crust and suggest the trapping of surface magnetite by collapse of melt. Magnetite monolayers may be a feature of meteorites that undergo significant degassing. Silicate warts with dendritic textures were observed and are suggested to be droplets ablated from another stone in the shower. They, therefore, represent the first evidence for intershower transfer of ablation materials and are consistent with the other evidence in the Winchcombe meteorite for unusually intense gas loss and ablation, despite its low entry velocity.
Publisher: Copernicus GmbH
Date: 22-07-2021
DOI: 10.5194/EPSC2021-570
Abstract: & & An increasing number of newly formed impact craters on Mars have been detected in the last 15 years. These small craters are normally identified via dark spots in lower resolution images that formed during the impact process, presumably through the removal or disturbance of bright surface material [1]. Later higher resolution images revealed single craters or crater clusters, which form when impactors fragment in the atmosphere, within those halos [1,2]. Due to this detection method, most of the new impact sites found are in dusty regions, which imposes an observational bias [3]. Newly formed clusters consist of two to thousands of in idual craters and can be tightly clustered or spread out over hundreds of meters [2]. Since the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed on Mars in 2018 [4], the search for newly formed impact craters has become even more important, because identifying impacts in seismic signals could provide further constraints on both the atmospheric and solid-body effects of impact cratering process on Mars, as well as help place further constraints on the properties of the uppermost layer of the crust. As one of InSight& #8217 s mission goals is to estimate the current impact rate on Mars, the seismic detection of impacts is also crucial [4].& & & & The aim of this new study is to describe the properties of the complete catalog of known newly formed craters on Mars and examine correlations between different crater cluster properties. We investigated 559 crater clusters and 493 single craters detected between 2008 and 2020 using 25 cm x HiRISE images. The locations and diameters were noted for each single crater, as well as for every in idual crater within a cluster down to 1 m diameter. This was done using ArcMap (ArcGIS) software with the three-point method of the CraterTools add-in [5]. We describe the cluster characteristics, such as the number of craters within a cluster, largest crater in a cluster, cluster effective diameter, cluster dispersion, elevation of the impact sites, and the variation in sizes of craters within a cluster.& & & & More than half of the new impact sites form as clusters. We did not find any differences between the spatial distribution of single and crater clusters across Mars. The mapped crater clusters from this study consist of 2 to 2334 in idual craters. More than half of all clusters (58%) consist of 10 craters or less. Crater clusters containing more than 100 craters are rare. With regard to the sizes of craters within crater clusters, we found that for highly populated clusters, the majority of craters are very small, and clusters with few craters have a tendency for craters that are more equal in size. Clusters having large effective diameters contain more equally sized craters. Our results show the full range of parameter spaces that are possible for cluster properties, which can help validate theoretical atmospheric fragmentation models.& & & & & strong& References:& /strong& & & & & [1] Malin M. C. et al. (2006) Science, 314, 1573-1577.& & & & [2] Daubar I. J. et al. (2019) JGR, 124, 958-969.& & & & [3] Daubar I. J. et al. (2013) Icarus, 225, 506-516.& & & & [4] Banerdt B. W. et al. (2020) Nature, 13, 183-189.& & & & [5] Kneissl T. et al. (2011) Planet. Space Sci., 59, 1243-1254.& &
Publisher: AIP
Date: 2012
DOI: 10.1063/1.3686416
Publisher: Wiley
Date: 10-05-2023
DOI: 10.1111/MAPS.13977
Abstract: On February 28, 2021, a fireball dropped ∼0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South‐West England near the town of Winchcombe. We reconstruct the fireball's atmospheric trajectory, light curve, fragmentation behavior, and pre‐atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive (∼13 kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure (∼0.6 MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km s −1 ). A near‐catastrophic fragmentation at ∼0.07 MPa points to the body's fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near‐Earth region ∼0.08 Myr ago and it never had a perihelion distance smaller than ∼0.7 AU, while other CM2 meteorites with known orbits approached the Sun closer (∼0.5 AU) and were heated to at least 100 K higher temperatures.
Publisher: Elsevier BV
Date: 10-2016
Publisher: American Geophysical Union (AGU)
Date: 07-2022
DOI: 10.1029/2021JE007149
Abstract: The current rate of small impacts on Mars is informed by more than one thousand impact sites formed in the last 20 years, detected in images of the martian surface. More than half of these impacts produced a cluster of small craters formed by fragmentation of the meteoroid in the martian atmosphere. The spatial distributions, number and sizes of craters in these clusters provide valuable constraints on the properties of the impacting meteoroid population as well as the meteoroid fragmentation process. In this paper, we use a recently compiled database of crater cluster observations to calibrate a model of meteoroid fragmentation in Mars' atmosphere and constrain key model parameters, including the lift coefficient and fragment separation velocity, as well as meteoroid property distributions. The model distribution of dynamic meteoroid strength that produces the best match to observations has a minimum strength of 10–90 kPa, a maximum strength of 3–6 MPa and a median strength of 0.2–0.5 MPa. An important feature of the model is that in idual fragmentation events are able to produce fragments with a wide range of dynamic strengths as much as 10 times stronger or weaker than the parent fragment. The calibrated model suggests that the rate of small impacts on Mars is 1.5–4 times higher than recent observation‐based estimates. It also shows how impactor properties relevant to seismic wave generation, such as the total impact momentum, can be inferred from cluster characteristics.
Publisher: Copernicus GmbH
Date: 22-07-2021
DOI: 10.5194/EPSC2021-710
Abstract: & & & & & strong& Introduction: & /strong& A possible source of seismic activity on Mars is meteoroid impacts [5]. Nevertheless, in the first Martian year of the the NASA InSight Mission [2] no signal has been unambiguously associated with an impact event [4]. This calls for further investigation of meteorite strikes and the relationship between impact conditions and the seismic signals they generate. One of the ways to understand the seismic signature of meteoroid impacts is to analyze already existing data from other planetary bodies.& & & & During the Apollo era, over one thousand seismic signals were recorded on the Moon [e.g. 12]. Part of the Apollo seismic experiments were artificial impacts of Lunar modules (LM) and Saturn booster drops (S-IVB). Artificial impacts are considered large scale controlled experiments, because the exact position of the crater and the impactor parameters that made it are known. In this work, we model S-IVB artificial impacts on the Moon, using the iSALE-2D shock physics hydrocode [e.g., 1, 3, 21]. We simulated both the crater formation and the pressure wave propagation and attenuation. We examined size of the crater, cratering efficiency, impact momentum transferred to the target and two seismic parameters: seismic efficiency and seismic moment, and compared these measurements to the existing data [e.g., 10, 8, 7].& & & & One challenge with modelling the S-IVB artificial impacts is the realistic presentation of the projectile. The Apollo S-IVB boosters were hollow aluminum cylinders, with a very low bulk density of 23 gcm& em& & sup& & #8722 & /sup& & /em& & sup& & /sup& and mass of 14 t. The booster was 17.8 m long and 6.6 m in radius. The impact speed at the ground level was 2.54-2.66 kms& em& & sup& & #8722 & /sup& & /em& & sup& & /sup& . The drop angle was reported to be between 13.2& em& & sup& & #9702 & /sup& & /em& & em& & /em& and 35& em& & sup& & #9702 & /sup& & /em& & em& & /em& from vertical. [e.g., 14, 19]. There were five such impacts, and they all impacted into mare basalts and made elliptical craters (long and short axis in between 29.71 m and 38.7 m) with a central mound (crater depth was roughly estimated to 2-3 m) [e.g., 14].& & & & & strong& Numerical modelling: & /strong& All simulations in this work used the iSALE-2D shock physics hydrocode [e.g., 1, 3, 21]. To exclude any influence of target properties, all simulations used the same uniform target model of a 44% porous basaltic regolith [20, 15]. The mass and impact velocity of the projectile in our simulations were the same in all simulations and consistent with the experi- ments. Given the axial symmetry of the mesh geometry employed, we investi- gated five simplified representations of the irregularly shaped projectile. Three cases had a geometry of right-cylinder, with 90% porosity and different dimen- sions: 1. 11.7 m radius and height 0.5 m 2. 5.8 m radius and 2 m height 3. 0.992 m radius and 16.7 m height. The last two cases were spheroids: one was non-porous aluminum sphere with 1.06 m radius and the other one was 90% porous and had a radius of 2.3 m [13,21]. To calculate momentum transfer, the vertical component of the seismic moment and seismic efficiency we use approaches described extensively in previous studies [9, 7, 20, 15].& & & / & & & Here, we focus only on the vertical component of the seismic moment Mz [11, 7, 20]. To calculate seismic efficiency we used the same approach described in numerous previous work [e.g., 9, 20, 15].& & & & & strong& Results: & /strong& The shape of the projectile has a substantial effect on crater for- mation but little effect on the seismic signature of the impact. The largest crater was formed in Case 3, while the best agreement with observed crater properties was provided by Case 1 (for depth) and Case 5 (diameter). The porosity of the projectile affected the size of the mound at the bottom of the crater, which supports the idea that the observed central mounds at the bottom of the ob- served craters are projectile remenants [14]. The seismic efficiency & em& k & /em& & em& & sup& & #8722 & /sup& & /em& & sup& & /sup& and seismic moment & em& M& sub& z& /sub& & /em& 10& sup& & /sup& Nm were of the same order of magnitude for all cases. This seismic efficiency is in agreement with lower estimates of [10], and the seismic moment is consistent with the scaling proposed in [17, 16, 20, 6].& & & & & strong& Conclusion: & /strong& We have successfully replicated the S-IVB artificial impacts on the moon with iSALE2D, producing craters that are consistent with obser- vations in their approximate dimensions and morphology. The simulations also constrain the seismic efficiency and seismic moment of the artificial impacts, which are relatively insensitive to the density and shape of the impactor. The low seismic efficiency determined here for artificial impacts on the Moon may help explain the non-detection of impacts by InSight in the first Martian year of operating. Moreover, the insensitivity of seismic moment to impactor density and shape suggests that results from the Apollo seismic experiment of these artificial impacts are useful analogs for small impacts on Mars that can be used to better inform their detectability by InSight [17, 16, 20, 6].& & & & & & [1]& & Amsden A.A. et al. 1980. Technical report.& & & / & & & [2] Banerdt B.W. et al. 2020. & em& Nature Geoscience& /em& , pages 1& #8211 .& & & & [3] Collins G.S. et a. 2004. & em& Meteoritics & Planetary Science& /em& , 39(2):217& #8211 & & & & [4] Daubar I.J. et al. 2020. & em& Journal of Geophysical Resear& /em& & em& ch: Planets& /em& 125(8).& & & & [5] Daubar I.J. et al. 2018. & em& Space Science Reviews& /em& , 214(8):1& #8211 .& & & & [6] Fernando B. et al. 2020& em& Journal of Geophys& /em& & em& ical Research: Planets& /em& .& & & & [7] Gudkova T. et al. 2015. & em& Earth and Planetary Science Letters& /em& , 427:57& #8211 .& & & & [8] Gudkova TV et al. 2011. & em& Icarus& /em& , 211(2):1049& #8211 .& & & & [9] Guldemeister & Wunnemann K.2017. & em& Icarus& /em& , 296:15& #8211 .& & & & [10] Latham G. et al. 1970. & em& Science& /em& , 170(3958):620& #8211 .& & & & [11] Lognonne P. et al. 2009. & em& Journal of & /em& & em& Geophysical Research: Planets& /em& , 114(E12).& & & & [12] Lognonne & & Mosser B.1993. & & em& Surveys& /em& & em& & /em& & em& in & /em& & em& Geophysics& /em& , 14(3):239& #8211 .& & & & [13] Lundborg N. 1968. & em& International Journal of & /em& & em& Rock Mechanics and Mining Sciences & Geomechanics Abstracts& /em& , volume 5, pages 427& #8211 .& & & & [14] Plescia J.B. et al. 2016. & em& Planetary and Space Science& /em& , 124:15& #8211 .& & & & [15] Rajsic A., et al. 2021. & em& Journal of Geophysical Research: Planets& /em& .& & & & [16] Teanby N.A. 2015. & em& Icarus& /em& , 256:49& #8211 .& & & & [17] Teanby N.A. & Wookey J. 2011. & em& Physics of the Earth and Planetary Interiors& /em& , 186(1-2):70& #8211 .& & & & [18] Tillotson J.H. Technical report.& & & & [19] Wagner RV., et al. 2017. & em& Icarus& /em& , 283:92& #8211 ,& & & & [20] Wojcicka N. et al. 2020. & em& Journal of Geophys& /em& & em& ical Research: Planets& /em& . 125(10)& & & & [21] Wunnemann K., et al. 2006. & em& Icarus& /em& 180(2).& &
Publisher: Copernicus GmbH
Date: 21-07-2021
DOI: 10.5194/EPSC2021-459
Abstract: & & The crust on Mars has been structurally affected by various geologic processes such as impacts, volcanism, mantle flow and erosion. Previous observations and modelling point to a dynamically active interior in early Martian history, that for some reason was followed by a rapid drop in heat transport. Such a change has significantly influenced the geological, geophysical and geochemical evolution of the planet, including the history of water and climate. Impact-induced seismic signature is dependent on the target properties (conditions in the planetary crust and interior) at the time of crater formation Thus, we can use simulations of impact cratering mechanics as a tool to probe the interior properties of a planet.& & & & Contrary to large impacts happening in Mars& #8217 early geologic history, the present-day impact bombardment is limited to small meter-size crater-forming impacts (in the atmosphere and on the ground), which are also natural seismic sources (Daubar et al., 2018, 2020 Neidhart et al., 2020). Impact simulations, in tandem with NASA InSight seismic observations (Benerdt et al., 2020, Giardini et al., 2020), can help understand the crustal properties over the course of Mars& #8217 evolution, including the state of Mars& #8217 crust today. Our most recent numerical investigations include: estimating the seismic efficiency and moment from small meter-size impact events, tracking pressure propagation from the impact point into far field, transfer of impact energy into seismic energy, etc (Rajsic et al., 2020, Wojcicka et al., 2020). Understanding coupling between impact crater formation process with the generation and progression of seismic energy can help identify small impact everts in seismic data on Mars. We also looked at the same process on the Earth (Neidhart et al., 2020) and the Moon (Rajsic, et al., this issue).& & & & Since the landing of the NASA InSight mission on Mars, there was a dozen known new impacts (Miljkovic et al., 2021). However, all but one impact occurred much too far away (3000 to 8400 km distance from the InSight lander) to be within the detectability threshold estimates (Teanby et al., 2015 Wojcicka et al., 2020). About 50% of the observed craters were likely single impacts and the other 50% were evidently cluster craters with less than 40 in idual craters in the largest cluster. The largest single crater was ~14 m in diameter, and the largest crater in a cluster was ~13 m (Neidhart et al., this issue), consistent with crater cluster observations (Daubar et al., 2013). The one impact that had a possibility of being detected by SEIS was 1.5 m in diameter at 37 km distance (Daubar et al. 2020).& & & & Considering that orbital imaging is limited in space and time, these known new impacts represent only a fraction of the total number of impacts that have occurred on Mars in the last ~2 years. According to impact flux calculations (Teanby and Wookey, 2011), there should have been ~3000 detectable craters, larger than 1 m in diameter, formed on Mars since InSight landed. If any of these unobserved impacts have been large enough and close enough to InSight to detect seismically, we have not yet discerned them in the seismic data.& & & & References:& & & & Banerdt, W.B. et al. (2020) & em& Nature Geosci. & /em& , 183-189.& & & & Giardini, D. et al. (2020) & em& Nature Geosci. & /em& , 205-212.& & & & Daubar, I.J. et al. (2020) & em& J. Geophys. Res. Planets& /em& , 125: e2020JE006382.& & & & W& #243 jcicka, N. et al. (2020) & em& J. Geophys. Res. Planets& /em& , 125, e2020JE006540.& & & & Raj& #353 i& #263 et al. (2021) & em& J. Geophys. Res. Planets& /em& , 126, e2020JE006662.& & & & Daubar et al. (2013) & em& Icarus& /em& 225, 506-516.& & & & Teanby, N.A. & Wookey, J. (2011) & em& PEPI& /em& 186, 70-80.& & & & Neidhart, T. et al. (2020) & em& PASA& /em& , 38, E016.& & & & Teanby, N.A. et al. (2015) & em& Icarus& /em& 256, 46-62.& & & & Miljkovic, K. et al. (2021) & em& LPSC& /em& , LPI Contribution No. 1758.& &
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-10-2022
Abstract: Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.
Publisher: American Geophysical Union (AGU)
Date: 04-2023
DOI: 10.1029/2022JE007698
Abstract: Seismic activity generated by impacts depends on impact conditions and properties of the impact site. Here, we combined mapping of the regolith thickness with numerical impact simulations to better estimate the seismic efficiency and seismic moment generated in small impact events in the uppermost crust on Mars. We used mapping of crater morphology to determine the regolith thickness that craters formed in. We found that local regolith thickness in the late Amazonian units is between 4 and 9 m. Combined with previous estimates for the NASA InSight landing site, we composed a more realistic uppermost crust analog and implemented it in numerical impact simulations. We estimated the seismic efficiency and seismic moment for small craters on Mars impacting a non‐porous or fractured bedrock overlaid by 5, 10, or 15 m thick regolith. Seismic energy showed more dependence on target properties. Three orders of magnitude more energy were produced in stronger targets. The seismic moment does not depend on target properties, and we confirm that seismic moment is almost proportional to impact momentum. The resulting seismic moment is in agreement up to a factor of 4 between different target types. We improved the scaling relationships developed from numerical simulations used in seismic moment approximations by constraining its dependence on more realistic target properties.
Publisher: American Geophysical Union (AGU)
Date: 29-03-2023
DOI: 10.1029/2022JE007611
Abstract: We investigated 634 crater clusters on Mars detected between 2007 and 2021, which represent more than half of all impacts discovered in this period. Crater clusters form when meteoroids in the 10 kg–10 ton mass range break up in Mars' atmosphere to produce a few to a few hundred fragments that hit the ground. The properties of the clusters can inform our understanding of meteoroid properties and the processes that govern their fragmentation. We mapped in idual craters m within each cluster and defined a range of cluster properties based on the spatial and size distributions of the craters. The large data set, with over eight times more cluster observations than previous work, provides a more robust statistical investigation of crater cluster parameters and their correlations. Trends in size, dispersion, and large crater fraction with elevation support weak atmospheric filtering of material. The ersity in the number of in idual craters within a cluster, and their size‐frequency distributions, may reflect either a ersity in fragmentation style, fragility, or internal particle sizes.
Publisher: American Geophysical Union (AGU)
Date: 07-2022
DOI: 10.1029/2021JE007145
Abstract: We present a catalog of new impacts on Mars. These craters formed in the last few decades, constrained with repeat orbital imaging. Crater diameters range from 58 m down to m. For each impact, we report whether it formed a single crater or a cluster (58% clusters) albedo features of the blast zone (88% halos 64% linear rays 10% arcuate rays majority dark‐toned 4% light‐toned 14% dual‐toned) and exposures of ice (4% definite 2% possible). We find no trends in the occurrences of clusters with latitude, elevation, or impact size. Albedo features do not depend on atmospheric fragmentation. Halos are more prevalent at lower elevations, indicating an atmospheric pressure dependence and around smaller impacts, which could be an observational bias. Linear rays are more likely to form from larger impacts into more consolidated material and may be enhanced by lower atmospheric pressure at higher elevations. Light‐ and dual‐toned blast zones occur in specific regions and more commonly around larger impacts, indicating excavation of compositionally distinct material. Surfaces covered with bright dust lacking cohesion are favored to form detectable surface features. The slope of the cumulative size frequency distribution for this data set is 2.2 for diameters m (differential slope 2.9), significantly shallower than the slope of new lunar craters. We believe that no systematic biases exist in the Martian data set sufficient to explain the discrepancy. This catalog is complete at the time of writing, although observational biases exist, and new discoveries continue.
Publisher: American Geophysical Union (AGU)
Date: 09-2016
DOI: 10.1002/2016JE005038
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 07-2020
Publisher: Elsevier BV
Date: 02-2013
Publisher: American Association for the Advancement of Science (AAAS)
Date: 18-11-2022
Abstract: Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid. Recovered only hours after falling, the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment. It contains abundant hydrated silicates formed during fluid-rock reactions, and carbon- and nitrogen-bearing organic matter including soluble protein amino acids. The near-pristine hydrogen isotopic composition of the Winchcombe meteorite is comparable to the terrestrial hydrosphere, providing further evidence that volatile-rich carbonaceous asteroids played an important role in the origin of Earth’s water.
Publisher: American Geophysical Union (AGU)
Date: 29-11-2021
DOI: 10.1029/2021EA001887
Abstract: The third stage of the Saturn IV rocket used in the five Apollo missions made craters on the Moon ∼30 m in diameter. Their initial impact conditions were known, so they can be considered controlled impacts. Here, we used the iSALE‐2D shock physics code to numerically simulate the formation of these craters, and to calculate the vertical component of seismic moment (∼4 × 10 10 Nm) and seismic efficiency (∼10 −6 ) associated with these impacts. The irregular booster shape likely caused the irregular crater morphology observed. To investigate this, we modeled six projectile geometries, with footprint area between 3 and 105 m 2 , keeping the mass and velocity of the impactor constant. We showed that the crater depth and diameter decreased as the footprint area increased. The central mound observed in lunar impact sites could be a result of layering of the target and/or low density of the projectile. Understanding seismic signatures from impact events is important for planetary seismology. Calculating seismic parameters and validating them against controlled experiments in a planetary setting will help us understand the seismic data received, not only from the Moon, but also from the InSight Mission on Mars and future seismic missions.
Publisher: Proceedings of the National Academy of Sciences
Date: 09-09-2019
Abstract: Highly expanded Cretaceous–Paleogene (K-Pg) boundary section from the Chicxulub peak ring, recovered by International Ocean Discovery Program (IODP)–International Continental Scientific Drilling Program (ICDP) Expedition 364, provides an unprecedented window into the immediate aftermath of the impact. Site M0077 includes ∼130 m of impact melt rock and suevite deposited the first day of the Cenozoic covered by m of micrite-rich carbonate deposited over subsequent weeks to years. We present an interpreted series of events based on analyses of these drill cores. Within minutes of the impact, centrally uplifted basement rock collapsed outward to form a peak ring capped in melt rock. Within tens of minutes, the peak ring was covered in ∼40 m of brecciated impact melt rock and coarse-grained suevite, including clasts possibly generated by melt–water interactions during ocean resurge. Within an hour, resurge crested the peak ring, depositing a 10-m-thick layer of suevite with increased particle roundness and sorting. Within hours, the full resurge deposit formed through settling and seiches, resulting in an 80-m-thick fining-upward, sorted suevite in the flooded crater. Within a day, the reflected rim-wave tsunami reached the crater, depositing a cross-bedded sand-to-fine gravel layer enriched in polycyclic aromatic hydrocarbons overlain by charcoal fragments. Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record. The high-resolution section provides insight into the impact environmental effects, including charcoal as evidence for impact-induced wildfires and a paucity of sulfur-rich evaporites from the target supporting rapid global cooling and darkness as extinction mechanisms.
Publisher: Elsevier BV
Date: 11-2014
Publisher: Springer Science and Business Media LLC
Date: 09-2011
Publisher: Springer Science and Business Media LLC
Date: 19-09-2022
Publisher: Elsevier BV
Date: 08-2011
Publisher: American Geophysical Union (AGU)
Date: 10-2020
DOI: 10.1029/2020JE006540
Publisher: Wiley
Date: 08-12-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 08-11-2013
Abstract: The far- and nearsides of the Moon are geologically different. Using high-precision crustal thickness maps derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, Miljković et al. (p. 724 ) show that the distribution of lunar impact basins is also highly asymmetrical. Numerical simulations of impact basin formation coupled with three-dimensional simulations of the Moon's asymmetric thermal evolution suggest that lateral variations in temperature within the Moon's crust have a large effect on the final size of an impact basin.
Publisher: American Geophysical Union (AGU)
Date: 08-2020
DOI: 10.1029/2020JE006382
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2017
End Date: 06-2020
Amount: $437,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2017
End Date: 06-2019
Amount: $780,000.00
Funder: Australian Research Council
View Funded Activity