Research Paper GEOSPHERE Tectonic evolution of the Mesozoic South Anyui suture zone, GEOSPHERE; v. 11, no. 5 eastern Russia: A critical component of paleogeographic doi:10.1130/GES01165.1 reconstructions of the Arctic region 18 figures; 5 tables; 2 supplemental files; 1 animation Jeffrey M. Amato1, Jaime Toro2, Vyacheslav V. Akinin3, Brian A. Hampton1, Alexander S. Salnikov4, and Marianna I. Tuchkova5 1Department of Geological Sciences, New Mexico State University, MSC 3AB, P.O. Box 30001, Las Cruces, New Mexico 88003, USA CORRESPONDENCE: [email protected] 2Department of Geology and Geography, West Virginia University, 330 Brooks Hall, P.O. Box 6300, Morgantown, West Virginia 26506, USA 3North-East Interdisciplinary Scientific Research Institute, Far East Branch, Russian Academy of Sciences, Magadan, Portovaya Street, 16, 685000, Russia CITATION: Amato, J.M., Toro, J., Akinin, V.V., Hamp- 4Siberian Research Institute of Geology, Geophysics, and Mineral Resources, 67 Krasny Prospekt, Novosibirsk, 630091, Russia ton, B.A., Salnikov, A.S., and Tuchkova, M.I., 2015, 5Geological Institute, Russian Academy of Sciences, Pyzhevskii per. 7, Moscow, 119017, Russia Tectonic evolution of the Mesozoic South Anyui su- ture zone, eastern Russia: A critical component of paleogeographic reconstructions of the Arctic region: ABSTRACT INTRODUCTION Geosphere, v. 11 no. 5, p. 1530–1564, doi: 10 .1130 /GES01165.1. The South Anyui suture zone consists of late Paleozoic–Jurassic ultra- The South Anyui suture zone (Fig. 1) is a remnant of a Mesozoic ocean Received 19 December 2014 mafic rocks and Jurassic–Cretaceous pre-, syn-, and postcollisional sedimen- basin that separated the Arctic Alaska–Chukotka microplate from Siberia Revision received 2 July 2015 tary rocks. It represents the closure of a Mesozoic ocean basin that separated and from the arcs and continental blocks that eventually formed the Kolyma- Accepted 22 July 2015 two microcontinents in northeastern Russia, the Kolyma-Omolon block and Omolon block of northeastern Russia (Seslavinsky, 1979; Parfenov, 1984). It is a Published online 27 August 2015 the Chukotka block. In order to understand the geologic history and improve key tectonic boundary for paleogeographic reconstructions of the Arctic region our understanding of Mesozoic paleogeography of the Arctic region, we ob- prior to the opening of the Amerasia Basin. Although its western termination is tained U-Pb ages on pre- and postcollisional igneous rocks and detrital zircons not clear (Franke et al., 2008; Kuzmichev, 2009), it can be traced eastward using from sandstone in the suture zone. We identified four groups of sedimentary outcrops of accretionary complexes, ophiolitic rocks, and magnetic anomalies rocks: (1) Triassic sandstone deposited on the southern margin of Chukotka; from the New Siberian Islands (Fig. 1) in the west to at least as far as central (2) Middle Jurassic volcanogenic sandstone that was derived from the Oloy Chukotka and, more speculatively, to northern Alaska, where it has been cor- arc, a continental margin arc, along the Kolyma-Omolon block, south of the related with the Angayucham suture zone (Churkin and Trexler, 1981; Nokle- Anyui Ocean, a sample of which yielded no pre-Jurassic zircons and a single berg et al., 2000; Amato et al., 2004). peak at 164 Ma; (3) suture zone sandstone that yielded Late Jurassic maximum The South Anyui–Angayucham suture has been used to define the pres- depositional ages and likely predated the collision; and (4) a Mid-Cretaceous ent-day southern boundary of the Arctic Alaska–Chukotka microplate (e.g., syncollisional sandstone that had a maximum depositional age of 125 Ma. Fujita, 1978; Silberling et al., 1994), a continental block with an area compara- These rocks were intruded by postkinematic plutons and dikes with ages of ble to that of Greenland. It was displaced by the initial opening of the Arctic 109 Ma and 101 Ma that postdate the collision. We present a seismic-reflection basin in Early Cretaceous time (Grantz et al., 1990). Although Arctic Alaska– line through the South Anyui suture zone that indicates south-vergence of Chukotka translated across the Arctic to its present location, its initial geom- thrusting of the Chukotka block over the Kolyma-Omolon block, opposite etry, initial position, and the kinematics of its trajectory remain elusive. A host of most existing models and opposite of the vergence in the Angayucham of competing models have been proposed through the years (e.g., Lane, 1997; suture zone, the postulated along-strike equivalent in Alaska. This suggests Lawver et al., 2002; Miller et al., 2006; Kuzmichev, 2009; Shephard et al., 2013). that Chukotka and Arctic Alaska may have different pre-Cretaceous histories, The Mississippian to Triassic stratigraphy of the North Slope basin of Alaska which could solve space problems with existing reconstructions of the Arctic matches that of the Canadian Arctic Islands, so that restoring Arctic Alaska region. We combine our detrital zircon data and interpretations of the seismic to the Canadian Arctic creates an alignment of the basin’s depocenters and line to construct a new GPlates model for the Mesozoic evolution of the region produces a reasonable alignment of facies belts (Toro et al., 2004). Also, both that decouples Chukotka and Arctic Alaska to solve space problems with pre- margins experienced a simultaneous rift event in the Early Cretaceous Period vious Arctic reconstructions. (Grantz et al., 1990), but it is not clear where to restore Chukotka. A signifi- For permission to copy, contact Copyright Permissions, GSA, or [email protected]. © 2015 Geological Society of America GEOSPHERE | Volume 11 | Number 5 Amato et al. | Tectonic evolution of the Mesozoic South Anyui suture zone, eastern Russia Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/5/1530/3336239/1530.pdf 1530 by guest on 28 September 2021 Research Paper 120°E 160°E 160°W 120°W 100°W 6 Siberia SvB NSI ge Ran Amerasia Basin 1 sk n 3 CAA Figure 1. Tectonic map of northern Pacific a y o and eastern Arctic regions (after Akinin, h k r 2013; compiled using data from Klemperer e V et al., 2002; Nokleberg et al., 1994). DZ—de- 2 trital zircon; NSI—New Siberian Islands; 70°N WI—Wrangel Island; OCVB—Okhotsk-Chu- Fig. 3 kotka volcanic belt; SP—Seward Peninsula; WI NSB—North Slope of the Brooks Range; BR—Brooks Range; ASZ—Angayucham 4 NSB suture zone; CAA—Canadian Arctic Islands; BR SvB—Sverdrup Basin. Red inset box shows OCVB Chukotka 5 Laurentia location of Figure 3. Regional detrital zircon ASZ (DZ) data sets are: (1) West Verkhoyansk SP ( Prokopiev et al., 2008); (2) Indigirka River, Moma Basin; (3) New Siberian Islands Omolon (Miller et al., 2008); (4) Rauchua Basin Terrane TypesPost Accretionary Rocks (Miller et al., 2008); (5) Brooks Range fore- Craton Cenozoic land (Moore et al., 2015); (6) Sverdrup Basin (Omma et al., 2011). Craton Margin OCVB Arctic Alaska- 50°N Accretionary Prism Cretaceous deposits Chukotka microplate Seismic lines Jurassic deposits Oceanic Kolyma-Omolon 2DV Island Arc Mesozoic plutons South Anyui Zone Franke et al. 2008 500 km Metamorphic Cenozoic plutons 1 Regional DZ data sets cant problem is that the Arctic Alaska–Chukotka microplate is too long to fit in the context of the Mesozoic evolution of the Arctic region, and we use them com forta bly in the Arctic reentrant without considerable overlap of continental to create a new plate-tectonic model developed using the GPlates program of crust. Thus, it is likely that Arctic Alaska–Chukotka underwent considerable in- Williams et al. (2012). ternal defor ma tion during translation (e.g., Miller et al., 2006; Shephard et al., 2013). Miller et al. (2006) used detrital zircon data from Triassic sandstone of the circum-Arctic to show that the samples from Chukotka and Wrangel Island REGIONAL GEOLOGY have provenance signatures from Taimyr, Siberian Traps, and/or the Polar Urals, all regions of current Siberia. Because these detrital zircon data are in Crustal Blocks sharp contrast with samples from the Canadian Arctic and from northeastern Alaska, which have clear Laurentian affinities, Miller et al. (2006) concluded The geologic framework of northeastern Russia (Fig. 1) is the result of that Chukotka should be restored adjacent to the Taimyr and North Verk- multistage accretion of arcs and continental fragments to the ancient Siberian hoyansk, east of the Polar Urals of Russia. craton. Relevant reviews of the regional geology include Zonenshain et al. We obtained detrital zircon ages from nine samples of Triassic through (1990), Nokleberg et al. (2000), and Shephard et al. (2013). The Siberian (or Cretaceous sedimentary rocks of the South Anyui suture zone. In these sam- North Asian) craton (Fig. 2) is made of several large Archean (ca. 3.2–2.7 Ga) ples, we observe a change in the detrital zircon signature from Triassic to Late granite-greenstone blocks assembled during an orogenic event at 2.1–1.8 Ga Jurassic rocks that coincides temporally with convergence along the margin (Rosen et al., 1994; Gladkochub et al., 2006). Most of the Siberian craton is blan- of the South Anyui Ocean. We also interpret the crustal-scale structure of the keted by a thick and largely flat-lying Neoproterozoic cover succession (Fig. 2), region visible in the 2DV deep-crustal seismic line. The seismic data show, con- with the exception of the southern part, where there was a long-lived active trary to previous models, that the South Anyui suture zone is a south-vergent margin with abundant Neoproterozoic (1.8 Ga), early Paleozoic (494–482 Ma), structural wedge, i.e., the opposite of the coeval Angayucham–Brooks Range and late Paleozoic (315–290 Ma) granite batholiths (Prokopiev et al., 2008) that orogen of Alaska. Our data from the South Anyui suture zone are interpreted characterize the detrital zircon populations of sediment derived from Siberia.