Manfred Gottwald, Thomas Kenkmann, and Wolf Uwe Reimold Impact cratering is one of the fundamental processes in the solar system and, with all certainty, beyond. This process played a major role when the planets and their moons began to form from the TERRESTRIAL IMPACT STRUCTURES protoplanetary disk, and throughout planetary evolution since then. On Earth, impacts of certain size even affected the evolution of life. The TanDEM-X Atlas Lunar and interplanetary spaceflight over the past 50 years has provided us with detailed maps of the old, impact-crater covered surfaces of our Solar System neighbors. For Earth, the global impact crater record only represents a fraction of the bombardment that our 1 2 planet has had to endure. Tectonic activity, erosion and weathering, and post-impact burial under sedimentary covers have erased most Africa, North/Central America, Asia, Australia, of the terrestrial impact history. Many of the remaining recognized crater structures have either been modified almost beyond recogni- South America Europe tion, or are buried entirely. Preface (p. 7) 7.4 Asia [24 impact structures] (p. 311) Mapping what is left of the terrestrial impact record from a satellite 1. Small Bodies in the Solar System (p. 9) 7.5 Australia [30 impact structures] (p. 373) platform in low-earth orbit is often obscured by dense clouds and 2. Impacts (p. 11) dust-laden air layers in our atmosphere; or even the lack of solar 7.6 Europe [52 impact structures] (p. 449) illumination prevents us to see the bare ground. Remote sensing 3. Terrestrial Impact Structures (p. 19) Geologic Timescale (p. 573) methods developed in the past decades have given us tools, how- 4. Radar Remote Sensing (p. 23) Selected References (p. 575) ever, to tackle the challenge of mapping the Earth’s surface with high precision. 5. The TanDEM-X Mission (p. 26) Glossary (p. 593) 6. TanDEM-X Maps of Impact Structures (p. 30) Chemical Elements (p. 599) Between 2010 and 2016 the German TanDEM-X radar X-band mission, operated and managed by DLR, the German Aerospace 7. The Atlas (p. 33) Abbreviations and Acronyms (p. 599) Center, generated the first global space-borne terrestrial digital 7.1 Africa [21 impact structures] (p. 35) Impact Geology Index (p. 601) elevation model of high resolution, based on Synthetic Aperture 7.2 North/Central America [64 impact structures] (p. 100) Cartographic Index (p. 604) Radar interferometric measurements. We have used these data and 7.3 South America [14 impact structures] (p. 257) Authors (p. 607) produced the first topographic atlas of all currently confirmed ter- Geologic Timescale (p. 304) restrial impact structures. This book provides the readership with the basic principles of impact cratering, of radar remote sensing, and ISBN 978-3-89937-261-8 of the TanDEM-X mission. It addresses the updated terrestrial impact crater record with more than 200 high-resolution maps, supplemented Two volumes in slipcase, 608 pages, hard cover, 32.6 × 24.5 cm, 435 coloured figures, 205 physical maps by geological descriptions and a plethora of field photographs for 128 Euro most structures. Thus, our atlas provides a comprehensive overview plus shipping costs / free within Germany of the impact crater record for each continent.

7.3 South America – Serra da Cangalha, Brazil 7.2 North/Central America – La Moinerie, Quebec, Canada / Manicouagan, Quebec, Canada 7.6 Europe – Lappajärvi, Finland

/ Aerial photograph of the so-called “collar” of the central uplift of the Serra Serra da Cangalha Selected References Manicouagan Lappajärvi da Cangalha impact structure. View towards the south (image courtesy: Lappajärvi A. Bartorelli, provided by A. Crósta). Brazil Bottomley, R. J., York, D., and Grieve, Quebec / Canada Finland R. A. F. (1990). 40Argon-39Argon Finland latitude = 08°04‘45“ S / longitude = 46°51‘25“ W / diameter = 13.7 km / age = < 300 Myr dating of impact craters. Pro- latitude = 51°23‘ N / longitude = 68°41‘ W / diameter = 100 km / age = 214 Myr Thomas Kenkmann latitude = 63°08‘26“ N / longitude = 23°41‘04“ E / diameter = 23 km / age = 77.80 ± 0.78 Myr anomaly over the annular basin around the central uplift. An estimation ceedings of the 20th Lunar and of the average depth to basement, based on regional aeromagnetic Planetary Science Conference, The 23 km diameter Lappajärvi impact structure is to a large extent data, yielded a depth of 2.4 km. High resolution magnetic data Houston, Texas, Cambridge Uni- located beneath Lake Lappajärvi, whose north-south elongated shape indicated magnetic sources at 200-500 m depth below the center versity Press, pp. 421-431. is the result of glacial overprint. The lake bed was excavated due 46°55‘ 46°47‘ Gold, D. P., Tanner, J. G., and Halliday, 69°20‘ 69°00‘ 68°40‘ 68°20‘ 68°00‘ 23°20‘ 23°35‘ 23°50‘ 24°05‘ of the structure, and even deeper magnetic sources below the entire to the low resistance of crater fill breccias and shattered bedrock to structure, at around 1.9 km depth. The Bouguer gravity anomaly D. W. (1978). The Lac La Moinerie crater: A probable impact site in glacial erosion. The center of the geophysically mapped impact crater map is characterized by a weakly positive anomaly of +1 mGal New Quebec. Geological Society is close to the eastern shore of the north-central island Kärnänsaari. over the central area, and a low gravity signature of -2 mGal at the of America, Vol. 10, pp. 44. The gravity low associated with the crater has a diameter of 17 km. northwestern rim. Gravity modeling suggested disturbed basement Grieve, R. A. F. (2006). Impact Struc- The bathymetry of the lake indicates two major troughs: one is close in the innermost part of the structure to a depth of 2-3 km. tures in Canada. Geological As- to the eastern shore and the other close to the western shore of the Shock deformation features include shatter cones in coarse-grained sociation of Canada, GeoText lake. These troughs represent fractures of tectonic origin that have still sandstone from two locations in the central depression. The shatter No. 5, 210 pp. been active since the impact, as verified by repeated land levelling cones are smaller than 1 decimeter in size. The sandstone likely belongs and recent earthquakes. The lake is surrounded by a rim of forested to the Longá Formation. Also at hills that is considered a relic of the original crater rim. 51°45‘ 51°45‘ a few locations in the central 07°57‘ 07°57‘ Target rocks are 1750-1900 Myr old Svecofennian gneisses and depression and in the periphery schists, with subordinate granite and granite pegmatite, granodiorite, of the central uplift rare mono- and amphibolite, which are mostly covered by Quaternary till. The mict and polymict breccias have Campos Lindos main impact-generated rock type occurring on the central island been found. Feather features (FFs) were reported in quartz grains 63°17‘ of sandstones from the Longá and Poti formations, including 63°17‘ some quartz grains from shatter cones. Planar fractures (PFs) were An about 25 cm wide slab of suevite from the Lappajärvi impact structure. described in quartz grains from The grey, variably bent or fluidal-structured bodies in this light-brownish the same stratigraphic units, in altered, polymict impact breccia are all small, plastically deformed bodies polymict breccias and in shatter of impact melt. In contrast, the matrix is composed of both small impact Lappajärvi melt particles and clastic mineral and lithic particles (Photo: W. U. Reimold). cones; whilst planar deformation Mont de Babel features (PDFs) occur in coarse 51°25‘ 51°25‘ Rio Manuel Alves Grande sandstone from the drill cores The La Moinerie impact structure is a fine-grained melt rock of dacitic composition that is known as through Longá Formation in the with the ice-covered homonymous kärnäite – named after the large island Kärnänsaari in the northern central depression, and in shatter lake on May 13, 2019 as a compos- part of the lake. The melt rock represents the remnant of an impact Vimpeli cones. Based on the preserved ite image based on TanDEM-X DEM René-Levasseur Island melt rock complex that is made up of both clast-rich and clast-poor and Copernicus Sentinel-2 (channel shock features in the central uplift 5 km varieties. Other impact lithologies include suevite and lithic impact 08°05‘ 08°05‘ N 2/3/4) data. that suggest peak shock pres- breccia. Boulders of these various impactites are also found in glacial sures of not more than 10 GPa, till in eskers to the south and southeast of the lake. and the apparent lack of alloch- Geochemical analyses of the impact melt rock showed that traces thonous breccia fill in the crater Lappajärvi Lac Manicouagan of the impactor were admixed into the impact melt. Trace element moat, Thomas Kenkmann and co- analysis favored a projectile of H-chondritic composition. 40Ar-39Ar workers estimated about 500 m of Manicouagan dating of impact melt rock and recrystallized K-feldspar melt particles Strata of the collar of Serra da Cangalha show prominent radial folding. The fold axis plunges steeply towards erosion since the time of impact. of the Lappajärvi impact structure provided a weighted mean age the outside in its lower part and bends to an overturned orientation in its upper part (photo: T. Kenkmann). The age of Serra da Cangalha Quebec, Canada for the impact of 76.2 ± 0.29 Myr, whereas recent U-Pb dating on Wolf Uwe Reimold has been delimited to less than 51°05‘ 51°05‘ shock metamorphosed zircon supports an age of 77.85 ± 0.78 Myr. 270 Myr, the age of the young- The impact melt rock was originally thought to be of volcanic The Manicouagan structure with a variably referred diameter of 90- tured zone is generally taken as the diameter of the impact structure. est strata from the mid-Permian origin. Kurt Fredriksson and Frans E. Wickman proposed an impact 100 km is one of the largest known impact structures on Earth. The The outer limit is accentuated on the western side of the structure affected by the formation of the origin for this structure already in 1963. Extensive evidence for an 63°02‘ structure is located in remote northern Quebec, 180 km northwest of by a series of annular-trending lakes. The inner plateau rises out structure. impact origin of the Lappajärvi structure was presented by Nils Bertil the town of Sept-Îles. The impact occurred around 214 Myr ago, and of the annular reservoir in the form of steep cliffs or steep inclines. The discovery of the Serra da Svensson in 1968 and Martti Lehtinen in 1976, who identified shock- 63°02‘ it has been debated whether this large-scale catastrophic event could The innermost part is a topographically slightly depressed area with Cangalha structure dates back metamorphosed rocks. to the early 1970’s. As part of a have been part of a Late Triassic multi-impact event – other structures a 500 m high central elevation – formed by anorthosite – that is of similar age are Rochechouart in France and Saint Martin, also in known as Mont de Babel. The somewhat more complex topography regional exploration program for Alajärvi industrial diamonds, three bore- Canada – that might have caused or contributed to the minor mass of the innermost zone has been tentatively discussed as perhaps Location/Access holes were drilled at the center extinction at the Triassic-Jurassic boundary. indicating a peak-ring structure rather than a typical central peak; of this circular structure in order 08°13‘ 08°13‘ The structure is named after the homonymous Lac Manicouagan, alternatively, erosional processes may be invoked for the formation The Lappajärvi structure is located in western Finland, roughly 350 km to investigate its possible igneous one of a two-lake assembly (the other lake is called Lac Mouchalagne) of this complex morphology. The plateau is incised by a number of north of Helsinki and 100 km east of Vaasa at Finland’s west coast. intrusive origin – the structure was that partially surrounded the central part of the impact structure. The radial and annular trending valleys. Vaasa has an airport. Highways 18 and 16 lead directly from Vaasa lake basins were flooded by the construction of the Daniel-Johnson The target rocks at Manicouagan were 1170-1700 Myr old an- to the southern tip of Lake Lappajärvi. Outcrops of impact lithologies suspected to represent a possible 50°45‘ 50°45‘ kimberlite. First reference to a pos- hydroelectric dam in the 1960s. The Manicouagan Reservoir now orthosite, mangerite, charnockite, and granites, and other associated can be found along the shore of Lake Lappajärvi, in particular on forms an annular lake within the impact structure. igneous rocks, as well as minor supracrustal rocks. In the western the island of Kärnänsaari. At the Hotelli Kivitippu, a small museum Manicouagan’s prominent morphology is obvious on topographic sector occur grey gneisses. All these lithologies were metamorphosed provides further information about the Lappajärvi impact and the / Gently inward dipping beds of the maps. The outer diameter of the Manicouagan Reservoir measures to amphibolite to granulite facies, and locally eclogite facies, as well impact cratering process in general. Piauí Formation of the Serra da Can- 65 km and the reservoir has a width of about 10 km. Outside of the as deformed during the 900-1200 Myr Grenville orogeny. Schematic geological map of the Lappajärvi impact structure, underlain galha impact structure. The strata reservoir occurs a zone of fractured basement. Inside of the reservoir After peak metamorphic conditions at 1000-1100 Myr, crust was Daniel-Johnson dam by a TanDEM-X DEM (modified after Kenny et al., 2019). are gently folded at the meter scale. follows an inner plateau that is covered by a thick mass of coherent rapidly exhumed. Remnants of Middle Ordovician limestones and Viewing direction is from the north- impact melt rock. And the centermost area is occupied by a 25 km dolomites, as well as silt- and mudstones of the Trenton Group (also western crater syncline towards the 46°55‘ 46°47‘ wide remnant of the central uplift. The maximum extent of the frac- of this age) occur in the area of the reservoir. These supracrustals, 69°20‘ 69°00‘ 68°40‘ 68°20‘ 68°00‘ 23°20‘ 23°35‘ 23°50‘ 24°05‘ central uplift (photo: T. Kenkmann).

2 2 2 scale = 1 : 190 000 / scene = 34.2 × 45.5 km scale = 1 : 647 000 / scene = 116.6 × 155.5 km scale = 1 : 262 000 / scene = 47.2 × 63.0 km 286 287 172 173 496 497 0 1.90 9.50 km N 195 meter 660 0 6.47 32.35 km N 145 meter 1105 0 2.62 13.10 km N 40 meter 225