Canadian Journal of Earth Sciences Principles of structural geology on rocky planets Journal: Canadian Journal of Earth Sciences Manuscript ID cjes-2019-0065.R1 Manuscript Type: Article Date Submitted by the 20-Jun-2019 Author: Complete List of Authors: Klimczak, Christian; University of Georgia, Department of Geology Byrne, Paul; North Carolina State University, Department of Marine, Earth, and Atmospheric Sciences Şengör, Celâl; Istanbul Teknik �niversitesi, Solomon, Sean; Lamont-Doherty Earth Observatory Keyword: Planetary Tectonics,Draft Planetary Geology, Mercury, Mars, Venus Is the invited manuscript for Understanding tectonic processes and their consequences: A tribute to consideration in a Special A.M. Celal Sengor Issue? : https://mc06.manuscriptcentral.com/cjes-pubs Page 1 of 90 Canadian Journal of Earth Sciences 1 Principles of structural geology on rocky planets 2 Christian Klimczak1*, Paul K. Byrne2, A. M. Celâl Şengör3, Sean C. Solomon4 3 4 1 Department of Geology, University of Georgia, Athens, GA 30602, USA 5 ([email protected]) 6 2 Department of Marine, Earth, and Atmospheric Sciences, North Carolina State 7 University, Raleigh, NC 27695, USA ([email protected]) 8 3 Department of Geology, Faculty of Mines and the Eurasia Institute of Earth Sciences, 9 İstanbul Technical University, 34469 Maslak, İstanbul, Turkey ([email protected]) 10 4 Lamont-Doherty Earth Observatory,Draft Columbia University, Palisades, NY 10964, USA 11 ([email protected]) 12 13 *Corresponding Author: 14 Christian Klimczak 15 Department of Geology, University of Georgia, Athens, GA 30602, USA 16 Phone: 706-542-2977 17 Fax: 706-542-2425 18 Email: [email protected] 1 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 2 of 90 19 Abstract 20 Although the earth is the only known planet on which plate tectonics operates, many 21 small- and large-scale tectonic landforms indicate that deformational processes also occur 22 on the other rocky planets. Although the mechanisms of deformation differ on Mercury, 23 Venus, and Mars, the surface manifestations of their tectonics are frequently very similar 24 to those found on the earth. Furthermore, tectonic processes invoked to explain 25 deformation on the earth before the recognition of horizontal mobility of tectonic plates 26 remain relevant for the other rocky planets. These connections highlight the importance 27 of drawing analogies between the rocky planets for characterizing deformation of their 28 lithospheres and for describing, applyingDraft appropriate nomenclature, and understanding 29 the formation of their resulting tectonic structures. Here we characterize and compare the 30 lithospheres of the rocky planets, describe structures of interest and where we study them, 31 provide examples of how historic views on geology are applicable to planetary tectonics, 32 and then apply these concepts to Mercury, Venus, and Mars. 33 Keywords: Planetary Tectonics, Planetary Geology, Mercury, Venus, Mars 34 2 https://mc06.manuscriptcentral.com/cjes-pubs Page 3 of 90 Canadian Journal of Earth Sciences 35 Introduction 36 37 “Without a theoretical framework, such as the plate tectonic models, of the spatial 38 relations of rock bodies to one another in an orogenic belt, however wrong they may be, 39 objective criticism, fruitful deductions, and new observations would become difficult to 40 make. Identifying terranes without immediate hypothetical interpretations diminishes 41 testability (because tectonic analysis would be reduced to irrefutable singular existential 42 statements) and therefore objectivity. I conclude that the terrane concept is therefore a 43 less objective approach to orogeny than the simplistic models it criticizes and must 44 inevitably lead to scientific sterility,Draft as did the Alpine nappe concept before 1950. I argue 45 for a methodology of tectonic analysis that starts with models about spatial relations of 46 rock bodies and leads to piecemeal improvements by critical observations, a method that 47 led to the discoveries of Alpine structure and evolution and also to plate tectonics.” 48 This argument by Şengör (1990) – on the utility of the concept of terranes in the study 49 of orogenic belts – could not be more fitting to many concepts and methods used in 50 planetary structural geology and tectonics that have prevailed to the present. 51 The idea that similar processes generate similar outcomes underpins the principle of 52 uniformitarianism that has made the rise of modern geology possible. However, 53 uniformitarianism was originally invoked to explain structures that are now geologically 54 inert. On the earth (refer to Şengör (2017) for the names of the planets we employ here, 55 including our own), there was no question that a given process created similar results 56 everywhere. Curiously, this obvious point has often been overlooked in the justified 57 excitement arising from the study of geological structures on other worlds. As space 3 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 4 of 90 58 exploration revealed to us alien planetary surfaces, new designations were invented to 59 catalogue the structures seen thereon. This approach was particularly true for the many 60 shortening structures discovered on the rocky planets. Although the diversity and 61 variability of structural styles and architecture of shortening structures on the earth are 62 well documented, the nomenclature for extraterrestrial shortening landforms was 63 established with no regard to testable descriptions clearly related to crustal shortening 64 that were developed for the earth. Hence, comprehensive analogies between thrust 65 systems on ours and other rocky worlds cannot be fully drawn in planetary structural 66 geology. 67 Comparative geology as a method to study planets has long been known. Comparative 68 earth science had been practiced everDraft since Aristotle, Dikaiarchos, Eratosthenes, and 69 Strabo began describing the morphological features of our planet in terms of explanatory 70 geological models, but the honor of systematizing comparative earth sciences, geography, 71 and geology clearly belong to the two co-founders of modern geography, Carl Ritter and 72 Alexander von Humboldt. Von Humboldt combined his observations in Latin America 73 with those in the Canary Islands, Europe, and western and central Asia to characterize the 74 world’s large tectonic features such as oceans, mountain belts, and large basins (such as 75 the West Siberian or North Caspian) and to unite their description in one common 76 terminology. His publications on global stratigraphy (von Humboldt 1823a) and on 77 mountain ranges and volcanoes (von Humboldt 1823b, 1831, 1843) were aimed toward 78 that end. Carl Ritter took a more systematic approach and compared the large-scale 79 features of Asia among each other and helped to establish and expand von Humboldt’s 80 terminology in his monumental (if unfinished) “The General and Comparative 4 https://mc06.manuscriptcentral.com/cjes-pubs Page 5 of 90 Canadian Journal of Earth Sciences 81 Geography," of which only 19 volumes were published, covering Africa and almost the 82 whole of Asia (see Richter 1983). Both von Humboldt and Ritter were aided by Leopold 83 von Buch’s earlier publications (von Buch 1810, 1824) on the isostatic rise of 84 Scandinavia, the mountains of central Europe, and the volcanoes of the Canary Islands. 85 When these author’s explanatory theories were refuted, a good part of their descriptive 86 terminology survived into the time of the development of models involving substantial 87 horizontal motions (e.g., Élie de Beaumont 1829–1830, 1852; and Suess 1868, 1875, 88 1883–1909), and the new terminology, much enriched through the first three decades of 89 the twentieth century (e.g., Argand 1911, 1912, 1916, 1924, 1934; Kober 1921, 1931, 90 1942; Stille 1924, 1940; Staub 1924, 1928; Bucher 1933), proved extremely helpful in 91 describing and interpreting the large-scaleDraft structural features of our planet. However, 92 after World War II, that terminology and hypothetical world view of tectonics gradually 93 fell into desuetude, largely because of the switch of the international scientific language 94 from French and German to English alone and the rise of an unwelcome diffidence 95 towards theorizing in geology. By the time of the advent of plate tectonics theory, 96 beginning with J. Tuzo Wilson’s epoch-making paper of 1965, much of the older, rich, 97 and very apposite terminology had been forgotten. Consequently, such studies, for 98 reasons mentioned above, have been ignored in the planetary science community. 99 Here, we elaborate on some widely accepted principles and techniques of structural 100 geology devised by the earth tectonic community that can be readily applied to the study 101 of planetary tectonics, but which have not yet found widespread use for worlds beyond 102 our own. Likewise, some forgotten principles and techniques developed for the earth 103 prior to the wide scientific acceptance of plate tectonics find applicability on one-plate 5 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 6 of 90 104 planets (i.e., those with a single, continuous lithospheric shell) such as Mercury and 105 Mars. Of course, comparative planetary geology must account for differences between 106 the earth and planets, such as the presence of water, which affects mineralogical and 107 rheological aspects of tectonic