Terrestrial Impact Craters Research Articles

The Holleford structure: Insights into the pre- and post-impact geology of the Frontenac Terrane, Canada

A multi-chronometric investigation has been conducted on the ∼2.0-km-diameter Holleford impact structure of Ontario, Canada. In situ triple quadrupole laser ablation−inductively coupled−mass spectrometry U-Pb and Rb-Sr geochronology, along with (U-Th)/He thermochronology, have been applied to multiple mineral phases from impact melt-bearing breccias and overlying sedimentary units. Impact-induced resetting is absent in all three isotopic systems. While Holleford’s small size resulted in insufficient heating to reset geochronometers during impact, our investigation has defined a more detailed pre- and post-impact geologic setting within the Precambrian basement and overlying Paleozoic lithologies. Target rock age determinations include those associated with the Proterozoic Frontenac Terrane. These are manifest as the Rigolet (1004 ± 5 Ma, U-Pb apatite dating) and Ottawan (1074 ± 12 Ma, Rb-Sr biotite dating) phases of the Grenville Orogeny. Pre-Grenville ages associated with the Penokean (1806 ± 46 Ma, apatite dating) and the Shawinigan (1184 ± 8 Ma, U-Pb titanite dating; 1134 ± 21 Ma, U-Pb zircon dating) orogenies are also retained. A Paleoproterozoic age records Superior Province tectonometamorphism (2421 ± 97 Ma, U-Pb zircon dating). Dated post-impact events include dolomitization associated with Silurian marine transgression (430 ± 14 Ma, U-Pb dolomite dating) and regional K-metasomatism of Mississippian age (346 ± 5 Ma, U-Pb titanite dating). Extremely young (U-Th)/He ages (27−3 Ma) were obtained from planar fractured and recrystallized apatite, which we interpret to be the result of impact-induced diffusion domain reduction. This, combined with low-temperature heating due to burial, significantly limited He retention. Stratigraphic constraints place the Holleford impact event at ca. 458 Ma, close to the Darriwilian−Sandbian boundary of the Ordovician. This age indicates that Holleford may be part of the Late Ordovician group of terrestrial impact craters related to L-chondrite parent breakup.

Impact Craters on Earth with a Diameter of More than 200 km: Numerical Modeling

The three largest impact craters, the remains of which have been found on Earth to date, had diameters of about 200 km immediately after formation. The search for traces of larger impact structures continues. This paper presents the results of numerical modeling of the formation of terrestrial impact craters larger than those already found. It is shown that the inferred geothermal gradient significantly influences the initial geometry of the impact melt region, which may facilitate the search for the remains of deeply eroded ancient impact structures.

Martian Impact Fracturing Pervasively Influences Habitability

AbstractOn Mars, the lack of either plate tectonics or a prominent erosional hydrological cycle since the Noachian means geological changes caused by asteroid and comet impact events have been preserved. On Earth, surviving impact‐induced fractures are localized to the relatively few preserved craters on the planet. We estimate that the shell of impact‐fractured rock on Mars (the “impact‐sphere”) could provide between 9,200 times the surface area of a Mars radius sphere and up to 100 times this value, depending on the assumptions made, as potential microbially accessible space. Although >93% of craters we consider are smaller than 10 km in diameter, they contribute only about 5% of the total fracture surface area generated by all craters, making complex craters the dominant process for potential habitat formation. Microbiological data from terrestrial impact craters suggest that these fractures could have significantly enhanced local habitability by providing pathways for fluid flow, and thus nutrients and energy. However, unlike on Earth, the geological history of Mars means that pervasive impact fractures may also have provided pathways for Hesperian and Amazonian brines to infiltrate the subsurface and locally reduce habitability. Combining the fracture data with previous microbiological observations provides testable hypotheses for Martian drilling missions.

New high-pressure polymorphs of magnetite, ilmenite, olivine, pyroxenes and feldspars

The new high-pressure shock-produced minerals discovered in meteorites can be considered as the possible components of the deep-seated geospheres. The structure peculiarities of the recently discovered minerals of this genetic type and of the geophysical interest are discussed in the paper. The special attention is addressed on the structure transformation under high pressure of the (Fe,Ti)-oxides and the new HP-polymorphs of ilmenite, post-spinel phases, magnetite, olivine, pyroxene and feldspars. The high-pressure polymorphs of these minerals are thought to be the constituent of the deep Earth’s interior. The crystal structures and composition of new НР-minerals discovered in meteorites and in the rocks near terrestrial impact craters provide the richer information on the complicate petrology of deep-seated geospheres which cannot be obtained on the base of laboratory experiments. On this basis it is also possible to predict their role as potentially important carriers of large ion lithophile elements in the Earth’s mantle and, hence, important contributors to the Earth’s heat budget.

Maskelynite- as seen in shocked Lonar target basalt, India, and martian and lunar meteorites

In this study, we investigate the mineralogical and petrochemical characteristics of maskelynite occurring in a shocked basalt boulder from a terrestrial impact crater on a basaltic target – the Lonar impact crater in India, and the martian and lunar meteorites. The majority of Lonar maskelynite experienced solid-state transformation and maintained almost a uniform chemical composition, consistent with the unshocked feldspar. The locally flow-like texture and marginal vesiculation in feldspathic glass are needed in interaction with the impact-melt. The vesiculated melt occasionally occurring at the margins of maskelynite is characterised by Na-loss due to the shock-induced volatility. A shock pressure of ≤42 GPa and at a temperature of ≤1000 °C appear consistent for the formation of Lonar vesiculated melt/ feldspathic glass. Under the impact-induced shock metamorphism, maskelynite samples from the moon retain both the crystalline and amorphous domains with a distinct chemical heterogeneity attributed to different shock metamorphism effects of the plagioclase. In contrast, the martian maskelynites exhibit a smooth, homogeneous composition. The estimated shock pressure is relatively higher at ∼42–45 GPa based on experiments and models. The difference in Si/Al ratio in lunar (1–1.3) and martian maskelynite (1.5–1.9) suggests its inherent difference in composition of the crust, whereas the Lonar maskelynite shows overlapping composition with the martian maskelynite contending Lonar basalt as a potential terrestrial analogue to the martian crust.

Understanding the Ries impact structure subsurface from high-resolution seismic data

Abstract The Ries impact structure (southern Germany) formed ca. 15 Ma and is 22–26 km in diameter, making it one of the youngest and best-preserved mid-size terrestrial impact craters, yet the subsurface has not been studied with modern geophysics. We present the first high-resolution seismic profiles of the Ries impact structure; the profiles show discontinuous intra-basement reflectors and a central crater floor without a significant central topographic high. The inner crystalline ring sits adjacent to, not on top of, the crater terrace zone. These morphologies indicate that during the crater modification stage, the rebounding central uplift at Ries rose and then collapsed without the continued outward motion required to form a fully developed peak ring. The Ries impact structure may be best considered a transitional complex crater form between a central-peak crater and a peak-ring crater as documented on the Moon and other rocky planets. A series of high-amplitude, discontinuous, topographically influenced reflectors overlying the basement implies that the suevite within the crater basin was emplaced via lateral transport.

Structural Transformations of Minerals in the Earth’s Mantle: the New High Pressure Polymorphous Modifications of Olivine and Wollastonite

There are reviewed important results obtained in the studies of HP-minerals during 2018–2022 years. The emphasis is made on the characterization of HP-polymorphs modifications of olivine (asimovite, poirierite) and wollastonite (breyite and davemaoite) discovered in this period. The structure of poirierite (ε-Mg2SiO4) contains the unique silicate chain Si3O9 with one tetrahedron in its period. Consequently its structural formula is Mg2[SiO3]O, and its intergrowth with wadsleyite/ringwoodite in shocked chondrites support the idea that transformations of olivine into ringwoodite becomes via forming of poirierite. The close ratio of cell parameters in wollastonite (1T) at 8.9 GPa and its synthetic analogue CaGeO3 exhibits the similarity of their structures. The HP/HT data confirm the stability of the wollastonite polymorph (1T, 2M, pseudowollastonite and synthetic analogue of breyite) at the upper mantle conditions. The crystal structures and composition of new НР-minerals discovered as inclusions in diamonds, in meteorites and in the rocks near terrestrial impact craters provide the richer information on the complicate petrology of deep-seated geospheres which cannot be obtained on the base of laboratory experiments.

Object-Oriented Remote Sensing Approaches for the Detection of Terrestrial Impact Craters as a Reconnaissance Survey

The purpose of this study is to employ a remote sensing reconnaissance survey based on optimal segmentation parameters and an object-oriented random forest approach to the identification of possible terrestrial impact craters from the global 30-m resolution SRTM DEM. A dataset consisting of 94 confirmed and well-preserved terrestrial impact craters, 104 volcanic calderas, and 124 valleys were extracted from real-world surface features. For craters with different sizes, eight optimal scale parameters from 80 to 3000 have been identified using multi-resolution segmentation, where the scale parameters have a positive correlation (R2 = 0.78) with the diameters of craters. The object-oriented random forest approach classified the tested impact craters, volcanic calderas, and valleys with an overall accuracy of 88.4% and a Kappa coefficient of 0.8. The investigated terrestrial impact craters, in general, have relatively lower rim circularity, higher length-to-width ratio, and lower relief, slope, and elevation than volcanic calderas. The topographic characteristics can be explained by geological processes associated with the formation and post-deformation of impact craters. The excavation and ejection by initial impact and rebound of excavated materials contribute to low elevation. The post-impact deformation, including inward collapse and slump of unstable rims, weathering, erosion, and sediment deposition, further reduces elevation and relief and modifies shapes resulting in lower circularity and higher length-to-width ratio. Due to the resolution limitation of the source DEM data and the number of real-world samples, the model has only been validated for craters of 0.88 to 100 km in diameter, which can be generalized to explore undiscovered terrestrial impact craters using cloud computing with global datasets provided by platforms such as Google Earth Engine and Microsoft Planetary Computer.

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

Event- and biostratigraphic evidence for two independent Ries and Steinheim asteroid impacts in the Middle Miocene

For decades, the Nördlinger Ries and Steinheim Basin in southern Germany have been regarded as a textbook example of a terrestrial impact crater doublet, although the oldest crater lake deposits in both craters suggest a biostratigraphic age difference of ~ 0.5 to 1 Myr. We previously presented stratigraphic arguments that challenged the double impact scenario and favoured a model of two temporally independent impact events in the Mid-Miocene. We here present, for the first time, four localities within a distance of ~ 50–100 km from the Ries and ~ 50–70 km from the Steinheim crater that expose two independent seismite horizons, together unique within the Upper Freshwater Molasse of the North Alpine Foreland Basin, each one featuring impressive water escape structures. The seismite horizons are separated by ~ 10 to 15 m of undisturbed Molasse deposits and, biostratigraphically, by an entire European Land Mammal Zone, thus providing evidence for two independent major seismic events within a time span of ~ 0.5–1 Myr. Both the lower and the upper seismite horizons can be correlated litho- and biostratigraphically with the basal crater lake sediments at the Ries and Steinheim craters, respectively, deposited immediately after the impacts. From a biostratigraphic point of view, the impact event that formed the Steinheim Basin probably occured around 14 Ma, some 0.8 Myr after the ~ 14.81 Ma Ries impact event.

Meteorite impact crater positions based on paleo-positions and its unrestrained latitudinal distribution

The paleo-positions of terrestrial meteorite impact craters along with distance and displacement registered since formation due to plate tectonics were deciphered using GPlates, an interactive GIS-based plate tectonic reconstruction and modeling software. The results of the study are intriguing as several craters have traversed across the globe, both from the Eastern to Western hemisphere and from the Southern to Northern hemisphere, and vice versa. The oldest crater studied was Foelsche, which traversed from the Southern to Northern hemisphere and from the Western to Eastern hemisphere while covering a distance of 39080 ​km in the past 981 million years and recording a relatively shorter displacement of 10470 ​km. On the other hand, Jänisjärvi and Suvasvesi South have traveled longer distances (27781 and 29050 ​km, respectively) and are among the most displaced craters (17400 and 16988 ​km, respectively). Similarly, the paleo-position, distance, and displacement for all craters, with ages <1100 ​Ma, were computed in the study. Based on the derived paleo-position, we have accessed the possibility of any selective distribution of craters across different latitudinal segments. As Earth is a planet that recorded dynamic variations in the terrestrial surface area across different geological ages, calculating the same was an arduous task. The land area within each of the three latitudinal segments, viz. 0–30°, 30–60°, and 60–90°, in which a crater formed was calculated for the geological time corresponding to an impact cratering event. This calculated land area within the respective latitudinal zone at each instance of a crater's formation was then compared with the total land area on Earth. The results showed that 0–30° and 30–60° segments have equal crater frequencies whereas the 60–90° segment has a lesser frequency. The latitudinal crater distribution on Earth was then compared with Moon and Mars. The results revealed that there is a non-selective distribution of terrestrial impact craters across different latitudinal segments, indicating a non-perceivable latitudinal dependency for impact events. • 192 Earth impact craters, formed after 1100 ​Ma, were reconstructed to its paleo-position. • The distance and displacement recorded by the craters due to plate tectonics is computed. • Latitudinal distribution of craters was studied and showed no major dependency on latitudes. • The latitudinal distribution was correlated with Moon and Mars.

Application of Raman Spectroscopy for Studying Shocked Zircon from Terrestrial and Lunar Impactites: A Systematic Review

A highly resistant mineral, zircon is capable of preserving information about impact processes. The present review paper is aimed at determining the extent to which Raman spectroscopy can be applied to studying shocked zircons from impactites to identify issues and gaps in the usage of Raman spectroscopy, both in order to highlight recent achievements, and to identify the most effective applications. Method: Following PRISMA guidelines, the review is based on peer-reviewed papers indexed in Google Scholar, Scopus and Web of Science databases up to 5 April 2022. Inclusion criteria: application of Raman spectroscopy to the study of shocked zircon from terrestrial and lunar impactites. Results: A total of 25 research papers were selected. Of these, 18 publications studied terrestrial impact craters, while 7 publications focused on lunar breccia samples. Nineteen of the studies were focused on the acquisition of new data on geological structures, while six examined zircon microstructures, their textural and spectroscopic features. Conclusions: The application of Raman spectroscopy to impactite zircons is linked with its application to zircon grains of various terrestrial rocks and the progress of the electron backscatter diffraction (EBSD) technique in the early 2000s. Raman spectroscopy was concluded to be most effective when applied to examining the degree of damage, as well as identifying phases and misorientation in zircon.

Terrestrial impact craters track the voyage of lithospheric plates

The paradigm of plate tectonics has aided in the identification of the journey of continents on the globe, their assembly into supercontinents, disruption, and re‐assembly. Here, we use meteorite impact craters as proxies for tracking the voyage of lithospheric plates. Employing the provisions in GPlates, an interactive geographic information system‐based plate tectonic reconstruction model, we were able to identify the palaeo‐position, and velocity of the 174 terrestrial impact craters, formed after 1,100 Ma, across the globe. These parameters of craters were evaluated for independent tectonic plates and were correlated with global tectonic events. For example, the similarity in the velocity of Beaverhead (900 Ma) and Holleford (550 Ma) craters since 550 Ma is traced to the connection between the Eastern Basin and North America Craton commencing 1,100 Ma, and through the South Basin and Range. Likewise, the drastic reduction in the velocity of Spider Crater (700 Ma) in Australia after 600 Ma can be attributed to the subduction between east and west Gondwana. The accelerated motion of the Indian Plate at 63 Ma, when the lithosphere was hovering over the Réunion hotspot, is also explained. With the advent of more improved plate tectonic models and the discovery of more impact craters, improvised interpretations will be possible.

Meteorite impact craters as hotspots for mineral resources and energy fuels: A global review

The ever-increasing recovery rate of natural resources from terrestrial impact craters over the last few decades across the globe offers new avenues for further exploration of mineral and hydrocarbon resources in such settings. As of today, 60 of the 208 terrestrial craters have been identified to host diverse resources such as hydrocarbons, metals and construction materials. The potential of craters as plausible resource contributors to the energy sector is therefore, worthy of consideration, as 42 (70%) of the 60 craters host energy resources such as oil, gas, coal, uranium, mercury, critical and major minerals as well as hydropower resources. Among others, 19 craters are of well-developed hydrocarbon reserves. Mineral deposits associated with craters are also classified similar to other mineral resources such as progenetic, syngenetic and epigenetic sources. Of these, the progenetic and syngenetic mineralization are confined to the early and late excavation stage of impact crater evolution, respectively, whereas epigenetic deposits are formed during and after the modification stage of crater formation. Thus, progenetic and syngenetic mineral deposits (like Fe, Ni, Pb, Zn and Cu) associated with craters are formed as a direct result of the impact event, whereas epigenetic deposits (e.g. hydrocarbon) are hosted by the impact structure and result from post-impact processes. In the progenetic and syngenetic deposits, the shock-wave induced fracturing and melting aid the formation of deposits, whereas in the epigenetic deposits, the highly fractured lithostratigraphic units of higher porosity and permeability, like the central elevated area (CEA) or the rim, act as traps. In this review, we provide a holistic view of the mineral and energy resources associated with impact craters, and use some of the remote sensing techniques to identify the mineral deposits as supplemented by a schematic model of the types of deposits formed during cratering process.

The remanent magnetisation recorded in the Chesapeake Bay impact crater, Virginia

During impact events, planetary crusts experience high pressures that can impart rocks with shock remanent magnetisation (SRM) if an ambient magnetic field or demagnetise rocks if a field is absent. If rocks experience substantial impact heating or are pressurised above ~40 GPa (inducing melting and recrystallisation) they may instead record a thermo-viscous remanent magnetisation (TVRM) as they cool below their Curie temperatures. Understanding impact re-magnetisation is crucial for studying terrestrial impact craters, but also unraveling the history of long-lived core dynamo fields on other planetary bodies. In this research we studied impact-related re-magnetisation recorded in natural rock samples from the Chesapeake Bay impact crater, Virginia. As a case study, here we discuss the natural remanent magnetisation (NRM) of two samples of different rock types: a suevite (sample I9-UI, depth 1.40 km beneath the ground) and a schist (sample S32, depth 1.67 km beneath the ground) using thermal and alternating field demagnetisation. The suevite represents a sample that contains material that experience impact remelting, whereas the schist represents an unmelted rock. From the NRM spectra, we found that the sample ITH9-UI was remagnetised by TVRM due to impact-related heating, while the sample STH32 shows the indication of shock deformation of magnetic minerals.

Orientations of planar cataclasite zones in the Chicxulub peak ring as a ground truth for peak ring formation models

Hypervelocity impact cratering is an important geologic process but the rarity of large terrestrial impact craters on Earth and the limited technical options to study cratering processes in the laboratory hinders our understanding of large-scale impact processes. Drill core recovered from the peak ring of the Chicxulub impact crater during International Ocean Discovery Program (IODP)/International Continental scientific Drilling Program (ICDP) Expedition 364 provides an opportunity to examine target rock deformation and thus, to assess cratering models in this regard. Using oriented computer tomography (CT) scans and line scan images of the core, we present the orientations of mm-to-cm-scale planar cataclasite and ultracataclasite zones in the deformed granitoid target rock of the peak ring. In the upper 470 m of the target rock, the cataclasite zones dip towards the crater center, whereas the dip directions for the ultracataclasite zones are approximately tangential to the peak ring. These two orientations are consistent with deformation expected from hydrocode-modeled principal stress directions for the outward movement of rocks as the transient crater develops, and the inward movement of rocks associated with collapse of the transient crater. Near the base of the core is a 96 m-thick interval of highly-deformed target rock with impact melt rock and rock fragments not observed elsewhere in the core; this interval has previously been interpreted as an imbricate thrust zone within the peak ring. The cataclasite zones below this thrust zone have different orientations than those in the 470 m-thick block above. This observation implies a differential rotation from the overlying block during the final stages of peak-ring formation. Our results support an acoustic fluidization process, wherein blocks that vibrate or slide relative to each other allow the target rock to flow during transient crater collapse, and that the size of coherent rock blocks increases over the course of crater modification as the target rock regains its cohesive strength and acoustic fluidization decreases.

The terrestrial impact crater record: A statistical analysis of morphologies, structures, ages, lithologies, and more

AbstractThe number of newly discovered and confirmed impact structures on earth is growing continuously. In this review paper, the main attributes of 198 confirmed impact structures and 10 further structures, for which final confirmation based on the identification of shock features is not yet entirely satisfying, are presented. The impact craters are compared statistically, with regard to their morphology, structure, and status of erosion or burial. The size– and age–frequency distributions of terrestrial impact structures are presented. Additional aspects concern target petrography and shock effects found in the craters. Based on the discovery statistics of presently known crater structures, an estimate can be made of the number of craters that await discovery. The paper is complementary to the recently published atlas of terrestrial impact structures by Gottwald et al. (2020).

Are Impact Craters and Extinction Episodes Periodic? Implications for Planetary Science and Astrobiology

A review of the results of published spectral analyses of the ages of terrestrial impact craters (58 analyses) and biotic extinction events (35 analyses) reveals that about 60% of the crater trials support a statistically significant cycle averaging ∼29.7 million years (My), and about 67% of the trials of extinction episodes found a significant cycle averaging ∼26.5 My. Cross-wavelet transform analysis of the records of craters and extinctions over the past 260 My shows a mutual ∼26 My cycle and a common phase, suggesting a connection. About 50% of the best-dated impact craters seem to occur in approximately nine pairs or clusters in the past 260 My, apparently carrying the signal of an ∼26- to 30-My cycle. It has been suggested that periodic modulation of impacts and extinctions might be related to periodic comet storms that follow the solar system's oscillations in and out of the galactic mid-plane. Problems arise, however, with regard to the compatibility of such periodic pulses of comet flux with the makeup of the steady-state Near Earth Object (NEO) population, the estimated long-term NEO cratering rates on the terrestrial planets, and the predicted small contribution of Oort Cloud-derived comets to the terrestrial cratering record. Asteroid storms may be possible, but at present there are no accepted mechanisms for creating an ∼30-My period in asteroid breakup events and impacts. Astrobiological implications arise if extra-solar habitable planets suffer similar cyclical or episodic catastrophic bombardment episodes affecting long-term biotic evolution on those planets. Other planetary systems might commonly have comet reservoirs, but they are less likely to contain an asteroid belt in the proper orbital position. Further, frequent impacts of ∼1-km diameter comets and asteroids could affect the establishment and longevity of technological civilizations, including our own.

Exploration of the hypothetical impact ejecta layer around the Maâdna structure (Talemzane, Algeria) using georadar technique

The Maâdna structure (Talemzane, Algeria) is located approximately 400 km south of Algiers and is formed within Upper-Cretaceous to Eocene limestones from the Saharan Platform. It is a bowl-shaped crater roughly 1.7 km in diameter. The present-day crater rim is 60 m higher than the bottom of the depression, and is raised slightly compared to the surrounding terrain. So far, several aspects of Maâdna structure cratering process remain poorly known. Recent study, geological and geophysical investigation, do not support an impact origin for this structure but suggest an alternative dissolved diapir with inverted relief. At present, geophysical studies revealed many interesting features of known terrestrial impact craters. In particular, observed signatures yielded useful information on the impact-induced physical changes in targeted rocks. These observations motivated our investigation of Maâdna crater, which uses several different geophysical surveys with particular emphasis on the GPR technique. This later is used as a valuable tool for near surface explorations. Although GPR technique has a limited use in case of impact structures, it is used in this study to discriminate between electromagnetic signatures of supposed ejectas, which were widely used to describe Maâdna structure origin. Typical GPR antennas were used to test a survey protocol in several situations during the GPR field deployment stage. In order to characterize the target thin and shallower layer, most of the common profiles were acquired using a 500 MHz shielded antenna. Otherwise, to ensure maximum waves penetration depths, “NS & EW” profiles were also acquired using a lowest frequency 30 MHz unshielded rough terrain antenna (RTA) system with a flexible “snake-like” design. Moreover, the ensued GPR characterization is then used to constrain occurred cratering process. Our GPR survey results helped us to improve our knowledge of the structure subsurface features expression. A suitable post-acquisition processing and analyses of the collected data lead us to reject the existence of any electromagnetic signature that may be attributed to the presence of any atypical materials, such as melted iron-rich material or those with distinctive physico-chemical properties, which induces electromagnetic signal modification or dissipation. Besides, our different scans could help truthful geological interpretation linked to Maâdna structure. For example, scans operated on the prevailing structural unit surrounding the Maâdna crater show clearly the most documented structural features at this crater, such as bedrocks fracturation, locally collapses, overturned and/or vertical movement of strata, etc. Specifically, the topographically corrected scans are presently interpretative against the alternative scenario of the cratering process at Maâdna, since our various analyses do not support any meteoritic evidence. As a result, valuable insights into the hypothetic diapiric piercement have been then gained from this analysis. This leads us to conclude that GPR data can be used to build another strong argument in favor of the diapiric origin at Maâdna crater.

The Importance of Silali Basin (Kenya) as an Extra Terrestrial Impact Crater

Impact cratering by extra-terrestrial bodies including; asteroids, comets and meteorites; is an important geologic process, not only for the minerals that it forms, but also because of the knowledge that it is dangerous to mankind and life on earth. There is also the fact that extra-terrestrial impact cratering is a continuous process that may be going on even this very minute, somewhere in the universe. Consequently, the earth, just like other members of the solar system, is targeted by extra-terrestrial falling objects. Silali basin is a depression that is found to the north of Lake Baringo; around Kapedo town. It is suspected to be an Extra –Terrestrial Impact Crater (ETIC). The objective of the study is to assess the importance of Silali basin as an extra-terrestrial impact crater (ETIC) besides describing the basin’s ETIC characteristics. Data was collected using various research methods and has been presented in the form of analyzed satellite images, ground pictures, tables, a Digital Elevation Model, an aerial photograph, a cross section, maps and discussions. The socio-economic significance of the crater has been cited and include tourism, paragliding, quarrying of breccias and geothermal power harvesting. Notably, this is the first study on extra-terrestrial impact cratering and ETICs in Kenya. Consequently, Silali basin, as an ETIC, is a virgin field hence more scientific studies are recommended; for the basin and the surrounding area.