Thematic Article Paleogeographic Maps of the Japanese Islands: Plate Tectonic Synthesis from 750 Ma to the Present
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The Island Arc (1997) 6, 121-142 Thematic Article Paleogeographic maps of the Japanese Islands: Plate tectonic synthesis from 750 Ma to the present SHIGENORI MARUYAMA,'YUKIO ISOZAKI,' GAKU KIMURA2 AND MASARUTERABAYASH13 'Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152, Japan, 2Department of Earth Sciences, CIAS, Osaka Prefecture University, Sakai, Osaka 593, Japan, 3Department of Earth Sciences, Kagawa University, Takamatsu, Kagawa 760, Japan Abstract A series of paleogeographic maps of the Japanese Islands, from their birth at ca 750-700 Ma to the present, is newly compiled from the viewpoint of plate tectonics. This series consists of 20 maps that cover all of the major events in the geotectonic evolution of Japan. These include the birth of Japan at the rifted continental margin of the Yangtze craton (ca 750-700 Ma), the tectonic inversion of the continental margin from passive to active (ca 500 Ma), the Paleozoic accretionary growth incorporating fragments from seamounts and oceanic plateaux (ca 480-250 Ma), the collision between Sino-Korea and Yangtze (250-210 Ma), the Mesozoic to Cenozoic accretionary growth (210 Ma-present) including the formation of the Cretaceous paired metamorphic belts (90 Ma), and the Miocene back-arc opening of the Japan Sea that separated Japan as an island arc (25-15 Ma). Key words: back arc, collision, Japan, Pacific Ocean, paleogeography, rifted margin, subduction, supercontinent, superplume, Yangtze. INTRODUCTION Continents collide to assemble a supercontinent, for the tectonic evolution of Japan (Isozaki 1996; and a supercontinent breaks up to create new Maruyama 1997), presented here is a newly re- oceans. As precisely predicted by Tuzo Wilson vised version of paleogeographic maps of Japan (1966) nearly three decades ago, recent studies and surroundings. Since the first attempt by suggest that the Earth has been involved in this Maruyama & Sen0 (1986), a series of paleogeo- business at least several times since the late graphic maps of Japan and East Asia explained in Archean (Hoffman 1991; Dalziel 1992). The Japa- terms of plate tectonics has been compiled by nese Islands originated from one such rifted conti- several workers (Taira et al. 1989; Maruyama et nental margin approx. 750-700 million years ago, al. 1989; Isozaki et al. 1990). Remarkable when the Yangtze (South China) craton rifted progress in the studies of on-land accretionary apart from the Neoproterozoic supercontinent complexes during the last decade, however, re- Rodinia to open a new superocean, the paleo- quires a drastic re-drafting of previous versions. Pacific. Since the tectonic inversion from a passive New lines of evidence, particularly from ancient continental margin to an active margin at ca accretionary complexes, constrain the spatio- 450 Ma, proto-Japan has grown asymmetrically temporal dimensions of ancient subducted oceanic oceanward for nearly 400 km across-arc in 450 plates and timings of various tectonic events. million years, through successive subduction from This map series includes 20 sheets (Figs 1-20) the Pacific side. It was in the Miocene that proto- that cover all major tectonic events in Japan from Japan converted to an island arc isolated from its birth at ca 750 Ma to the present. The pre- mainland Asia. Triassic paleogeographic maps are prepared in a In harmony with the abovementioned scenario global scale (Figs 1-7) in order to explain the long-distance journey of proto-Japan with the Accepted for publication December 1996. Yangtze block from the southern hemisphere, 122 S. Maruyama et al. across the equator, until its merge into the mid- namely, India, Congo and Kalahari, may be a part latitude part of Asia in the Early Mesozoic. It is of the supercontinent. noteworthy that Asia hardly represents a reference Underneath Rodinia, a huge mantle upwelling tectonic framework for the earlier evolution of called the Pacific Superplume (Maruyama 1994) Japan because the Yangtze and other continental developed which broke up the supercontinent at ca blocks amalgamated to form Asia mainly in the 750-600 Ma. The position of the plume center was early Mesozoic, at ca 250-200 Ma (Maruyama et somewhere in the domain of Siberia + South al. 1989), that is, long after the birth of proto- China, Australia + Antarctica, and Laurentia. A Japan at ca 750-700 Ma. On the other hand, more few associated plumes may have been present, but localized maps and schematic cross-sections of they have not yet been clearly documented. The Japan and its vicinity are provided for the Jurassic dike swarms along the expected rifted margins by and later stages (Figs 8-20) in order to depict the separation of Laurentia and Australia have detailed geotectonic features. been dated that ca 750-700 Ma (Park et al. 1995). The Proterozoic and Early Paleozoic paleogeo- The continental rifting and related sedimentation graphic reconstruction of major continents is com- started at ca 750 Ma along the western margin of piled from Scotese & McKerrow (1990), Hoffman Laurentia (Hoffman 1991), the Yangtze Craton (Li (1991), Dalziel (1992), Powell et al. (1993), Li et et al. 1995), eastern Australia (Powell et al. al. (1995), and Jurdy et al. (1995). The post- 1993), and probably Antarctica (Dalziel 1992). 180 Ma relative plate motions in the Pacific domain are based on the works by Engebretson et al. VENDIAN, 600 Ma (1985), Sen0 & Maruyama (1984) and Maruyama & Sen0 (1986). The distribution of major sedimen- The birth of the Pacific Ocean, as a surface manifes- tary basins in China and Japan is adopted from tation of the mantle upwelling, and its subsequent Wang et al. (1985) and Minato et al. (1965). For enlargement reduced the space of the unnamed further details on the Phanerozoic tectonics of previous superocean where the next super- Japan, refer to other articles in this special the- continent, Gondwana, was formed at 530 Ma matic issue. Although there are unsettled discus- (Fig. 2). A series of 700-600 Ma events, initiated by sions and debates over various tectonic events from continental rifting through the formation of the pas- different perspectives in Japan, references for the sive continental margin and ended by the formation present map compilation are limited to those sup- of oceanic lithosphere, are documented well around ported by clear evidence. In the following, we the Pacific rim; for example, the western margin of describe each map from the origin of Japan at ca North America (Isozaki & Maruyama 1992), South- 750 Ma to the present. west Japan (Isozaki & Maruyama 1991), eastern Australia, and Antarctica (Dalziel 1992). The South China block was situated between PALEOGEOGRAPHIC MAPS eastern Australia and western Canada (Laurentia), LATE PROTEROZOIC, 750-700 Ma as evidenced by stratigraphic similarities between East Gondwana and Laurentia (Li et al. 1995). The Supercontinent Rodinia (McMenamin & McMe- northwesternmost part of Southwest Japan, that namin 1990) was present in the southern hemi- is, the Oki Island in the Japan Sea and the north- sphere where most major continents were con- ernmost margin of Southwest Japan, was a part of nected, except West Africa and/or Amazonia South China, and was rifted by the Pacific Super- (Fig. 1). The presence of Rodinia in the southern plume to form a passive continental margin and hemisphere is derived from paleomagnetic evidence contiguous oceanic lithosphere (the 0-eyama ophi- in North America (Dickinson 1981) and East Gond- olite; Ishiwatari 1989; Isozaki & Maruyama 1991). wanaland (Powell et al. 1993). The paleogeo- graphic map for 750-700 Ma is largely based on EARLY CAMBRIAN, 540 Ma the reconstruction by Hoffman (1991) and Dalziel (1992), although a considerable discrepancy is As an inevitable result of the rapid and continuous present between them. All of the major continents growth of the Pacific Ocean, the previous unnamed around the present Pacific, that is, North America, superocean was consumed to form a superconti- South America, East Asia, Australia and Antarc- nent, Gondwana, on the opposite side of the Earth tica, once formed a supercontinent in the center of at 530 Ma, beyond the rotation pole of the propa- the present Pacific Ocean. The other continents, gating Pacific ridge into the previously existing Paleogeographic maps of Japan 123 continent (Fig. 3). Several microcontinents and a Pacific orogenic belts: for example, the 467- number of immature island arcs in the oceanic 482 Ma Grenrock blueschists in Australia (Fukui et domain were present in northern Africa and Saudi al. 1995), the 439-451 Ma Skookum Gulch blue- Arabia in the latest Proterozoic-Cambrian, but schists in the Klamath Mountains, North America they were amalgamated by collision and accretion (Cotkin et al. 1992), the ca 450 Ma high-P/T during the Pan-African orogeny (Gass 198 1). West schists in Japan (Isozaki & Maruyama 1991), and and East Gondwana were first amalgamated by the eclogites in Antarctica (Peacock & Goodge 1995). collision of the Baltica, Amazonia, West Africa and For details, see the review by Maruyama et al. Congo Cratons, and by the collision of Kalahari, (1996). These blueschist ages give the minimum Antarctica, Australia, South China, Tarim and age of subduction. The initiation of subduction North China, respectively. Slightly after those must have been earlier than this age, but it is not collisions, West Gondwana collided with East yet clarified by the presence of an accretionary Gondwana to form the Mozambique collisional complex older than 480 Ma; we tentatively put the orogenic belt, the suture of which runs currently value at ca 500 Ma in this paper. along the eastern margin of Africa (Hoffman 1991; The southern part of the Iapetus Ocean closed at Dalziel 1992). a later stage than the northern part by the collision of Africa during the middle Paleozoic, at ca 400- 350 Ma. By this event the southern Appalachian LATE CAMBRIAN, 500 Ma and European Hercynian, including the Bohemian Massif, the Massif Central, Ile de Groix, the Galicia The Iapetus Ocean opened some time between 570 and the Hercynide basement rocks in the Penninic and 520 Ma (Dalziel et al.