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Us Department of the Interior Us Geological Survey Phanerozoic Tectonic Evolution of the Circum-North Pacific

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Us Department of the Interior Us Geological Survey Phanerozoic Tectonic Evolution of the Circum-North Pacific U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY PHANEROZOIC TECTONIC EVOLUTION OF THE CIRCUM-NORTH PACIFIC By Warren J. Nokleberg1, Leonid M. Parfenov2, James W.H. Monger3, lan O. Norton4, Alexander I. Khanchuk2, David B. Stone5, David W. Scholl1, and Kazuya Fujita6 OPEN-FILE REPORT 98-754 PREPARED IN COLLABORATION WITH: RUSSIAN ACADEMY OF SCIENCES GEOLOGICAL SURVEY OF CANADA EXXON EXPLORATION COMPANY UNIVERSITY OF ALASKA MICHIGAN STATE UNIVERSITY 1 - U.S. Geological Survey 2 - Russian Academy of Sciences 3 - Geological Survey of Canada 4 - Exxon Exploration Company 5 - University of Alaska 6 - Michigan State University This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 1998 ABSTRACT The accretions resulted in the substantial growth of the North Asian and North American continents. And sixth, The Phanerozoic tectonic evolution of the Circum- in the middle and late Cenozoic, oblique to orthogonal North Pacific is recorded mainly in the erogenic collages convergence between the Pacific Plate, with respect to of the Circum-North Pacific mountain belts that separate Alaska and Northeast Asia, resulted in formation of the the North Pacific from the eastern North Asian and modern-day ring of volcanoes around the Circum-North western North American Cratons. The collages consist of Pacific. Oblique convergence between the Pacific Plate tectonostratigraphic terranes, composed of fragments of and Alaska also resulted in major dextral-slip faulting in igneous arcs, accretionary-wedge and subduction-zone Interior and Southern Alaska, and along the western part complexes, passive continental margins, and cratons, of the Aleutian-Wrangell arc. Associated with dextral- that are overlapped by continental margin arc and slip faulting was crustal extrusion of terranes from sedimentary basin assemblages. The geologic history of Western Alaska into the Bering Sea. terranes and overlap assemblages is highly complicated because of post-accretion dismemberment and INTRODUCTION translation during strike-slip faulting that occurred subparallel to continental margins. A Phanerozoic tectonic model for the Circum- The complex tectonics of this region is analyzed by North Pacific region is interpreted for the orogenic the following steps. (1) Tectonic environments for the collage that occurs along the margins of the eastern erogenic collage are assigned from regional compilation North Asian and western North American Cratons. The and synthesis of stratigraphic and faunal data. The orogenic collage is composed of tectonostratigraphic tectonic environments include cratonal, passive terranes and overlap assemblages. The continental margin, metamorphosed continental margin, tectonostratigraphic terranes consist mainly of accreted continental-margin arc, island arc; oceanic crust, fragments of igneous arcs, accretionary-wedge and seamount, and ophiolite, accretionary wedge and subduction-zone complexes, passive continental subduction zone, turbidite basin, and metamorphic. (2) margins, and cratons. The overlap assemblages are Correlations are made between terranes. (3) Coeval sequences of mainly late Mesozoic and Cenozoic terranes are grouped into a single tectonic origin, i.e., a continental margin arc and sedimentary basin single island arc or subduction zone. (4) Igneous arc and assemblages that were deposited on subjacent subduction zone terranes, that are interpreted as being tectonostratigraphic terranes, or on terranes and tectonically linked, are grouped into coeval, curvilinear subjacent craton margin assemblages. arc-subduction zone complexes. (5) By use of geologic, The basic data for the tectonic model are from a faunal, and paleomagnetic data, the original positions of regional compilation and synthesis of a new tectono­ terranes are interpreted. And (6) the paths of tectonic stratigraphic terrane map for Circum-North Pacific migration are constructed. including the Russian Far East, northern Japan, Alaska, Six processes overlapping in time were responsible Canadian Cordillera, and U.S.A. Pacific Northwest, the for most of the complexities of the collage of terranes North Pacific Ocean, and the Arctic Ocean (Nokleberg and overlap assemblages around the Circum-North and others, 1994a, 1997a, b). This synthesis, including Pacific. First, in the Late Proterozoic, and the Late stratigraphic, faunal, and structural data, enables Devonian and Early Carboniferous, major periods of correlation of terranes that were tectonically displaced rifting occurred along the margins of Northeast Asia and from one another, grouping of coeval terranes into a northwestern part of the North American Cordillera. The single tectonic origin (e.g., a single island arc or rifting resulted in fragmentation and formation of subduction zone), tectonic reconstruction of original cratonal and passive continental margin terranes from positions, reconstruction of paths of tectonic migration, each continent that eventually migrated and accreted to and the tectonic setting of overlap assemblages, mainly other sites along the evolving margins of the original or continental-margin igneous arcs in the Phanerozoic. adjacent continents. Second, from about the Late This paper reviews what is known and what Triassic through the mid-Cretaceous, a succession of reasonably can be inferred about the geology and island arcs and tectonically paired subduction zones tectonic evolution of the onshore areas of the Circum- formed near continental margins. Third, from about North Pacific. This paper consists of three parts: (1) an mainly the mid-Cretaceous through the Present, a introduction and discussion of terms and concepts succession of igneous arcs and tectonically paired applied to the components of the Circum-North Pacific subduction zones formed along the continental margins. orogenic collage; (2) descriptions and interpretations of Fourth, from about the Jurassic to the Present, oblique the origins of terranes and overlap assemblages within convergence and rotations caused orogen-parallel the collage; and (3) a model for the Phanerozoic tectonic sinistral and then dextral displacements within the upper evolution of the Circum-North Pacific. This paper plate margins of Northeast Asia and the North American concentrates on the onshore geology and tectonics of Cordillera. The oblique convergences and rotations major terranes and overlap assemblages that can be resulted in the fragmentation, displacement, and related to igneous arcs and to subduction zones. Because duplication of formerly more-continuous arcs, of a lack of comparable geologic data, the details of the subduction zones, and passive continental margins. geology and tectonics of offshore areas, principally the These fragments were subsequently accreted along the Arctic Ocean including the Canada Basin, the Bering margins of the expanding continental margins. Fifth, Sea, and the Sea of Okhotsk, are only briefly from the Early Jurassic through Tertiary, movement of summarized herein. For craton and craton margins, this the upper continental plates towards subduction zones paper only summarizes the important tectonic features of resulted in strong plate coupling and accretion of the those units and terranes derived from those units. No former island arcs and subduction zones to continental attempt is made herein to provide complete references margins. Accretions were accompanied and followed by because the literature is enormous, and abundant data crustal thickening, anatexis, metamorphism, and uplift. and interpretations are incorporated in numerous, excellent recent syntheses (e.g., Plafker and others, this vast and geologically complicated region of the 1989, Oldow and others, 1989; Gabrielse and Yorath, earth. The project consists of a number of geologists 1991; Burchfiel and others, 1993; Monger, 1993; Moore who have each gathered field data and observations in and others, 1994; Monger and others, 1994, and Plafker their respective parts of the Russian Far East, Alaska, and Berg, 1994; Monger and Nokleberg, 1996). This and the Canadian Cordillera over many years, and who paper draws on these syntheses, and also includes have been able to work together in a large international previously unpublished data that were jointly compiled team to compile, synthesize, and publish basic data, and interpreted by the Russian and North American geologic and mineral resource maps, and interpretative coauthors. Companion papers that present parts of this articles. tectonic model are by Parfenov and others (1993 a, b), Three groups of figures provide important Natal'in (1993), Parfenov and others (1993a, b), illustrations for this paper. (1) The first group consists Monger and Nokleberg (1996), and Parfenov (1997). of four generalized geologic/tectonic maps for the Previous oral versions of the paper were presented by region that are page-size simplifications of more Monger and Nokleberg (1995), Nokleberg and others detailed maps of major terranes, overlap assemblages, (1995a, b, c), Parfenov (1995a, b), and Monger and oceanic plates, rifts, and major faults, and other major others (1996). geologic features of the Circum-North Pacific (Figures This paper is the result of interpretation of 1-4). These figures are adapted from Nokleberg and extensive geologic mapping and associated tectonic others,
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