Terrane Accretion, Production, and Continental Growth: a Perspective Based on the Origin and Tectonic Fate of the Aleutian-Bering Sea Region

Downloaded from geology.gsapubs.org on February 1, 2015

Terrane accretion, production, and continental growth: A perspective based on the origin and tectonic fate of the Aleutian-Bering Sea region

David W. Scholl, Tracy L. Vallier, Andrew J. Stevenson U.S. Geological Survey, Menlo Park, California 94025

ABSTRACT Orogenesis in the Aleutian-Bering Sea region would create an expansive new area of Pacific-rim mountain belts. The region itself formed about 55 Ma as a consequence of the suturing of a single exotic fragment of oceanic crust—Aleutia—to the Pacific's Alaskan- Siberian margin. A massive overlap assemblage of the igneous crust of the Aleutian Arc and the thick sedimentary masses of the Aleutian Basin have since accumulated above the captured basement terrane of Aleutia. Future closure of the Aleutian-Bering Sea region, either northward toward the continent or southward toward the Aleutian Arc, would structurally mold new continental crust to the North American plate. The resulting "Beringian orogen" would be constructed of a collage of suspect terrenes. Although some terrenes would include exotic crustal rocks formed as far as 5000 km away, most terrenes would be kindred or cotsctonic blocks composed of the overlap assemblage and of relatively local (100-1000 km) derivation. The Aleutian-Bering Sea perspective bolsters the common supposition that, although disrupted and smeared by transcurrent faulting, examples of kindred assemblages should exist, and perhaps commonly, in ocean-rim mountain belts.

INTRODUCTION In this paper we emphasize that the actualis- Aleutian subduction zone and arc (Fig. 2A). Suspect tectonostratigraphic terranes are the tic example of the Aleutian-Bering Sea region The older subduction zone at the base of the principal structural units of lengthy sectors of (Fig. 1A) can be called upon to visualize a tec- Alaskan-Siberian margin was thereby aban- Pacific mountain belts (Jones et al., 1983; tonic setting capable of producing continental doned and converted to a suture binding Aleu- Coney et al., 1980; Saleeby, 1983; Schermer et crust fabricated largely of kindred rather than tia and North American crust (Fig. 2B). al., 1984). The ocean-rim processes that accrue exotic terranes. The setting itself was created by Formation of the Aleutian Basin by the cap- allochthonous blocks are therefore major causes the single-event accretion of a large sector of ture of Aleutia is based on regional relations of continental growth. oceanic lithosphere to that of North America. implying that the basin's oceanic crust was not Geologists interested in crustal evolution by formed by backarc spreading. Evidence for a the accretion of terranes are equally concerned TERRANE ACCRETION nonspreading or capture origin includes the ob- with determining their travel paths, formative AND FORMATION OF servations that (1) the crust of the Eocene is- environments, and places of origin (Helwig, THE BERING SEA REGION land arc (Eocene) is younger than the indirectly 1974; Saleeby, 1983). For example, at one ex- Global plate movements specify that since estimated age for the basin (Cretaceous; Fig. 2); treme, the terranes may constitute a tectonic early Mesozoic time thousands of kilometres of (2) the basin's magnetic anomalies (Fig. 1A) collage of mostly far-traveled and genetically oceanic lithosphere have underthrust the Paci- strike northward away from the arc, or in a di- unrelated or exotic blocks, or alternatively, they fic's northern or Alaskan-Siberian rim (Grow rection opposite that expected of a basin open- may be mostly tectonically related or kindred and Atwater, 1970; Woods and Davies, 1982; ing behind a southward migrating arc (Cooper fragments displaced only slightly (100-1000 Rea and Dixon, 1983; Engebretson et al., et al., 1976a; 1976b); (3) paleomagnetic data km) from their site of origin. 1984). Evidence has been recognized that attest that the arc formed in situ (Harbert et al., Silver and Smith (1983) recently emphasized a roughly 1000-km-wide terrane of the 1984); and (4) marine seismic sections indicate that the greater Indo-Pacific region, where an northward-moving oceanic crust accreted to the that since the formation of the arc the dimen- exceedingly complex fabric of colliding terranes Alaskan-Siberian margin in early Tertiary time. sions of the basin have not increased in re- is being assembled (Hamilton, 1979), is not Accretion of this sector of oceanic plate— sponse to spreading (Cooper et al., 1981). only an actualistic example of continental ex- termed the Aleutia terrane by Marlow and Terrane capture is placed in early Eocene pansion by the aggregation of disparate as well Cooper (1983)—to North American litho- time, 55-50 Ma, based on the southward shift as kindred terranes but also a large-scale model sphere formed the basement of the Bering Sea's of subduction-related igneous and deforma- for visualizing the Mesozoic evolution of the Aleutian Basin (Fig. 1A; Scholl et al., 1975; tional processes from the continental margin of North American Cordillera. Saleeby (1983) has Cooper et al., 1976b; Ben-Avraham and the Beringian and Koryak region lying north of drawn a similar analogy between the tectonic Cooper, 1981). the Aleutian Arc (Figs. 1A, IB, and 2B; Patton evolution of the vast Melanesian region of arcs The terrane-capture concept of Aleutia re- et al., 1976; Aleksandrov et al., 1976; McLean, and backarc basins and that of the Western quires that for problematic reasons a sector of 1979; Zinkevich et al., 1983; Wallace and En- Cordillera, but he also has stressed the impor- oceanic lithosphere being consumed at the gebretson, 1984), to the region of the arc itself tance of tectonic separation of related terranes Alaskan-Siberian margin buckled offshore and (Scholl et al., 1983a, 1983b; Rubenstone, 1984; by lateral transport. initiated the formation of the intra-oceanic Vallier et al., 1987).

GEOLOGY, v. 14, p. 43-47, January 1986 43 Downloaded from geology.gsapubs.org on February 1, 2015

If Aleutia was captured at 55 Ma, it proba- Pacific lithosphere. Diagram 1C depicts a time CONTINENTALIZATION OF THE bly was a fragment of the Kula plate, which approximately 30 m.y. later when the growth ALEUTIAN-BERING SEA REGION was created about 82-85 Ma by the breakup of of the Aleutian Arc and the accretion of Shor (1964) was the first to visualize that the the Mesozoic lithosphere of the Farallon and Aleutia—the northern sector of the Kula sedimentary and igneous filling of the Aleutian Izanagi (or Bering) plates (Fig. 1; Woods and plate—took place. Basin was effectively a process of creating new Davies, 1982; Rea and Dixon, 1983; Engebret- The terrane-capture origin of the Aleutian- continental crust. The areal size of this infilling son et al, 1984). Figure IB schematically par- Bering Sea region is probably duplicated in the basin and flanking arc (1.5 x 106 km2) is about trays the North Pacific at 80 Ma, just after the neighboring Sea of Okhotsk, the western Phil- equal to that of the Western Cordillera of the Kula plate formed by the splitting of North ippine Sea, and possibly the Arctic Ocear. United States. After the accretion of Aleutia, (Ben-Avraham and Uyeda, 1983).

Figure 1. A: Index map of Aleutian-Bering Sea region. Heavy numbered or lettered line.'» show trends of identified magnetic anomalies. Pacific anomalies south of Aleutian Ridge are of Paleocene age; those north of ridge in Aleutian Basin are provisionally identified Early Cretaceous M- anomalies of Cooper et al. (1976a, 1976b). Large arrows indicate present relative direction of convergence of Pacific and North American plates at Aleutian Trench. B: Late Cretaceous North Pacific paleogeography just after fragmentation of two North Pacific oceanic plates formed rapidly northward-moving Kula plate. C: Early Eocene capture of Lower Cretaceous sector of Kula plate in Bering Sea north of evolving Aleutian Ridge (see Fig. 2). B and C are contrived to (1) place eastward-younging crust of Early Cretaceous age in Aleutian Basin region at 55 Ma and (2) sep- arate this crust from older lithosphere lying south of hypothetical east-west fracture zone, a circumstance presumed to have determined offshore location for Aleutian subduction zone (Hilde et al., 1977; Ben Avraham and Uyeda, 1980). Drawings are schematic representations based on pro- jections supplied by Engebretson (1984, personal commun.) and plate models by Grow and Atwater (1970), Woods and Davies (1982), Rea and Dixon (1983), and Engebretson et al. (1984, 1985).

44 GEOLOGY, Januaiy 1986 Downloaded from geology.gsapubs.org on February 1, 2015

the newly formed Aleutian Arc provided vol- subduction zone, and the relative motion be- (1) miogeoclinal platform and basinal deposits canogenic sediment to the Aleutian Basin, but tween the North American and Eurasian plates over the outer Beringian shelf and upper slope, more important, the arc served as an obstacle is slow and, in this area, ill-defined (Savostin et (2) deeper water deposits of the lower slope to the southward movement of terrigenous sed- al., 1983), most of the Aleutian-Bering Sea re- and rise apron, and (3) the generally less thick iment shed by Alaskan and Siberian drainages. gion has evolved in a nearly passive tectonic (3-4 km) but more voluminous basin-plain Since the addition of Aleutia to North Amer- setting (Marlow et al., 1982). deposits of the Aleutian Basin. In addition, the ica, the Aleutian Basin and its flanking arc have Figure 2B shows that the postaccretion over- overlap assemblage includes (4) the roughly 24- been part of the North American plate. Because lap assemblage includes exceptionally thick (12 km-thick igneous and sedimentary massif of the convergence between the Pacific and North km) sedimentary sequences. As designated on Aleutian Arc, and (5) the 6-8-km-thick (or American plates occurs largely at the Aleutian this figure, and also on Figure 3B, these include thicker) subduction complex that was accreted to the arc's landward trench slope probably in late Cenozoic time (Fig. 2B; McCarthy et al., NATAL BERINGIAN 1984; McCarthy and Scholl, 1985). ALEUTIAN ARC and MARGIN SUBDUCTION ZONE 55 Ma YOUNGEST KNOWN A BERINGIAN OROGEN COMPOSED OLDEST KNOWN ARC ROCKS ARC ROCKS 60-55 Ma MOSTLY OF KINDRED TERRANES OLD F.Z .550 Ma Orogenesis of the Aleutian Basin can be af- fected by nullifying the plate boundary conditions that currently protect it from interaction with the Pacific and Eurasian plates. New boundary conditions could crush and sliver the igneous and sedimentary rocks of the overlap assemblage and its basement framework and produce a diverse array of lithologically distinct tectonic blocks or terranes. The areal arrange- ment of preorogenic basement-type rocks and age-equivalent or younger depositional se- MATURE PRESENT ARC MASSIF ALEUTIAN BASIN quences (numbered on Fig. 2B) are shown, respectively, in Figures 3A and 3B. Although many tectonic scenarios can be imagined, we select here a regional deformation mechanism set in motion by a shift of the subduction zone from the Aleutian Trench to the Aleutian Basin; in effect, to a "backarc" setting. Backarc subduction requires the renewed underthrusting of the exotic Aleutia terrane beneath bordering massifs of thicker continental Figure 2. A: Schematic S-N section (see Fig. 3 for location) of Aleutian-Bering Sea region illus- or Aleutian Arc crust. The Aleutian Arc is an trating its origin at about 55 Ma as consequence of offshore buckling of Kula plate at a fracture autochthonous body relative to older rocks of zone (see Fig. 1). This circumstance created offshore Aleutian subduction zone and arc and Alaskan and Siberian continental crust, but this entrapped Lower Cretaceous fragment of Kula crust—Aleutia—in Aleutian Basin of Bering crust is constructed of numerous terranes, some Sea. B: Section shows that accumulation of postcapture overlap assemblage (composed of igneous rock and sedimentary bodies numbered 1 through 5, explained in text), currently as exotic to Alaska (see caption, Fig. 3). thick as 12-24 km, is "continentalizing" Aleutian-Bering Sea region. The hypothetical consequences of renewed

Figure 3. Schematic maps showing distribution of (A) major bedrock-type • YOUNG CONT^ENJAL rock masses and (B) co- eval and overlying sedimentary masses of Aleutian-Bering Sea region. These igneous and sedimentary bodies rep- resent starting rock framework that would in- fluence structural style of hypothetical Beringian orogen and determine sequences of rocks exposed in its structural units or terranes (see Fig. 4). Large arrows show direction of present Pacific-North American convergence, which is largely accommodated at Aleutian Trench. Mesozoic continental crust north of Aleutian Basin is itself largely composed of far-traveled or exotic terranes (chiefly Peninsular terrane) that docked prior to capture of Aleutia (Scholl et al., 1975; McGeary and Ben-Avraham, 1981; Marlow and Cooper, 1983; Fujita and Newberry, 1983). Conceivably, Bowers and Shirshov ridges (Fig. 1) are also exotic blocks (Ben-Avraham and Cooper, 1981).

44 GEOLOGY, Januaiy 1986 Downloaded from geology.gsapubs.org on February 1, 2015

subduction northward beneath the Beringian- rocks of the sheared Aleutian massif might also BERING SEA PERSPECTIVE Koryak margin are shown on Figure 4A, a cir- be carried to high structural levels. Deforma- The Bering Sea perspective emphasizes that cumstance that causes a prominent southward tion causing northward vergence would seem- a tectonic continuum can be involved in the structural vergence of telescoped sedimentary ingly provide ample opportunities to unravel process of terrane accretion and production. masses offscraped from Aleutia. Southward the geologic evolution of the Beringian orogen This continuum begins with a single terrane- overthrusting, and subsidence effected by load- and its original structural setting. accretion event that drastically alters the tec- ing, tectonically buries the Aleutian Arc. Thus, Although not diagrammed in the sections of tonic setting of a sector of convergent ocean except for clues provided by the composition Figure 4, we stress that "backarc" subduction margin, a change that allows for the accumula- and depositional environment of associated sed- would involve oblique underthrusting relative tion of a massive overlap assemblage in a tec- imentary bodies, direct evidence of the exist- to the bedrock framework exhibited on i:he tonically protected region. The continuum ence of the offshore structural dam that Figure 3 A. The hypothesis of the Beringan or- progresses and results in the eventual disruption permitted the accumulation of a massive sedi- ogen therefore requires that many of the thrust- of the overlap assemblage and its basement mentary body is not exhibited. Instead, and bordered terranes shown in Figure 4 are framework in response to a subsequent and for perverse reasons, an exotic fragment of subsequently (and syndeformationally) slivered, equally major change in regional tectonic set- Aleutia—a detached Mesozoic seamount of the transported, and deformed by transpressive and ting. Orogenesis produces a new set of terranes Kula plate—is shown structurally perched atop transtensional processes, probably in the fash- spawned inside the tectonic brood chamber the tectonically buried massif of the island arc. ions described by Taira et al. (1983) and Sa- formed by the original capture event. Only ophiolite fragments of Aleutia, which leeby (1983). A second major focus of the perspective is would be the oldest rock sequences exposed in Because the Aleutian-Bering Sea region is that although aidjacent terranes in an ocean-rim the central part of the Beringian orogen, would dimensionally large, blocks displaced even on orogen may exhibit dissimilar depositional and provide the critical evidence needed to recon- the order of 1000 km would remain within tectonic histories and evidence of large-scale struct the origin of the Aleutian-Bering Sea. their formative structural setting. But, as absolute and differential movements, these cir- region. stressed by Saleeby (1983), transcurrent disrup- cumstances do not require that most of the ter- Figure 4B calls for a large oceanic plateau tion of the evolving orogen could create :;uch a ranes are necessarily tectonic strangers to either (for example, Hess Rise) to collide with the structurally complex aggregate of terrane;; of their neighbors or the region. The Aleutian-Ber- Aleutian Arc and, as a consequence, initiate contrasting tectonic and formative histories that ing Sea story stresses that the orogenic phase of southward subduction beneath the Aleutian the impression would be gained that the collage continental growth can be effected in part or Arc. A prominent northward vergence of com- was a grouping of mostly unkindred blocks, es- wholly by the jumbling and stacking of mostly pressional structures evolves, and crustal short- pecially so because the truly exotic block!; of regionally derived terranes. ening exposes old rocks of the Aleutia ophiolite Aleutia and the old framework rocks of the We are unaware of any ocean-rim orogen as well as equivalently old ophiolite of the Pa- Beringian margin would probably first attract that is an example of continental growth condi- cific plate that preceded the oceanic plateau the attention of the field geologists. tioned by the singular capture of a wandering into the abandoned Aleutian subduction zone. We recognize that the mechanics controlling sector of oceanic crust and later matured by the Ophiolite-type rock assemblages of the core the movement of terranes do not require that in-place tectonic hammering of its overlap as- those created in the Beringian orogen remain semblage and framework rocks. However, there. Beringian terranes could eventually be evolutionary schemes for the Paleozoic and Figure 4. General structu- transferred to distant sectors of the Pacific rim, Mesozoic "eugeosynclinal" regions of the North ral style of hypothetical a likelihood that could tectonically greats re- American Cordillera that involve locally Beringian orogen created by compressional defor- duce or even destroy the Beringian orogen. formed backarc basins and cotectonic island mation and transcurrent

dismemberment of struc- CENOZOIC ALEUTIAN tural section shown in Figure 2B. Orogenesis is effected by oblique subduction of exotic Aleutia basement terrane northward relative to trend of continental crust of North American plate (A) and southward relative to strike of Aleutian Arc (B). Although not dia- INDICATES EXOTIC TERRANE OR CRUSTAL FRAGMENT grammed subduction 50 -1 Km. oblique to region's crustal framework (see Fig. 3A) CENOZOIC CENOZOIC ALEUTIAN CENOZOIC BACKARC would cause shearing -ARC MASSIF MESOZOIC BASIN DEPOSITS FRAGMENT OF ALEUTIAN KULA OPHIOLITE • and lateral displacement MESOZOIC . . SUBDUCTION N of major thrust blocks " COMPLEX and create a complex of transported tectonostratigraphic terranes within Beringian orogen. These blocks could be relatively shuffled at least 1000 km without leaving structural framework of original Aleutian-Bering Sea iregion.

44 GEOLOGY, Januaiy 1986 Downloaded from geology.gsapubs.org on February 1, 2015 arcs (Burchfiel and Davis, 1972; Churkin and Fujita, K, and Newberry, J.T., 1983, Accretionary Saleeby, J.B., 1983, Accretionary tectonics of the McKee, 1974; Saleeby, 1983) resemble that of terranes and tectonic evolution of northeastern North American Cordillera: Annual Reviews of the Aleutian-Bering Sea region and, more im- Siberia, in Hashimoto, M., and Uyeda, S., eds., Earth and Planetary Sciences, v. 15, p. 45-73. Advances in earth and planetary sciences: Savostin, L., Zonenshain, L., and Baranov, B., 1983, portant, stress terrane kindredness rather than Tokyo, Terra Scientific Publishing Co., Geology and plate tectonics of the Sea of Ok- strangeness. p. 43-57. hotsk, in Hilde, T.W.C., and Uyeda, S., eds., A broader view derived from these as well as Grow, J.A., and Atwater, T., 1970, Mid-Tertiary tec- Geodynamics of the western Pacific-Indonesian the Bering Sea perspectives is that the orogenic tonic transition in the Aleutian Arc: Geological region: American Geophysical Union Geody- Society of America Bulletin, v. 81, namic Series, v. 11, p. 189-221. deformation of any thickly sedimented margin- p. 3715-3722. Schermer, E.R., Howell, D.G., and Jones, D.L., al basin—whether underlain by MORB-type Hamilton, W., 1979, Tectonics of the Indonesian re- 1984, The origin of allochthonous terranes: oceanic crust (e.g., Gulf of Mexico, Gulf of Cal- gion: U.S. Geological Survey Professional Paper Perspectives on the growth and shaping of con- ifornia, and Caribbean Basin) or backarc crust 1078, 345 p. tinents: Annual Reviews of Earth and Planetary (e.g., Sea of Japan and South Fiji Basin)— Harbert, W.P., Cox, A., and McLean, H., 1984, Pa- Sciences, v. 12, p. 107-131. leomagnetism of Starr Point and Driftwood Scholl, D.W., Buffington, E.C., and Marlow, M.S., could produce new continental crust tectonized Bay, Umnak Island, Alaska: EOS (American 1975, Plate tectonics and the structural evolu- at least initially into a collage of mostly kindred Geophysical Union Transactions), v. 65, p. 869. tion of the Aleutian-Bering Sea region, in terranes. The concept of the Beringian orogen Helwig, J., 1974, Eugeosynclinal basement and a col- Forbes, R.B., ed., Contributions to the geology bolsters the common supposition that some, lage concept of orogenic belts, in Dott, R.H., Jr., of the Bering Sea Basin and adjacent regions: Geological Society of America Special Paper and perhaps many, ocean-rim mountain belts and Shaver, R.H., eds., Modern and ancient géosynclinal sedimentation: Society of Eco- 131, p. 1-31. may prove to be recognizable, though smeared, nomic Paleontologists and Mineralogists Special Scholl, D.W., Vallier, T.L., and Stevenson, A.J., aggregates of mostly tectonically related ter- Publication 19, p. 359-376. 1983a, Arc, forearc, and trench sedimentation ranes. If true, then attempts to restore the crust- Hilde, T.W.C., Uyeda, S., and Kroenke, L., 1977, and tectonics; Amlia corridor of the Aleutian al pieces to their place of origin could be Evolution of the western Pacific and its margins: Ridge, in Watkins, J.S., and Drake, C.L., eds., Studies in continental margin geology: Ameri- successful, and a greatly improved understand- Tectonophysics, v. 38, p. 145-165. Jones, D.L., Howell, D.G., Coney, P.J., and Monger, can Association of Petroleum Geologists Mem- ing of the evolution of ocean margins would be J.W.H., 1983, Recognition, character, and anal- oir 34, p. 413-439. gained. ysis of tectonostratigraphic terranes in western 1983b, Geological evolution of the Aleutian North America, in Hashimoto, M., and Uyeda, Ridge—Implications for petroleum resources: S., eds., Advances in earth and planetary sci- Alaska Geological Society Journal, v. 3, REFERENCES CITED ences: Tokyo, Terra Scientific Publishing Co., p. 33-46. Aleksandrov, A.A., et al., 1976, New data on the tec- p. 31-35. Shor, G.G., Jr., 1964, Structure of the Bering Sea and tonics of the Koryak highlands: Geotectonics, Marlow, M.S., and Cooper, A.K., 1983, Wandering the Aleutian Ridge: Marine Geology, v. 1, v. 9, p. 292-299. terranes in southern Alaska; the Aleutia micro- p. 213-219. Ben-Avraham, Z., and Cooper, A.K., 1981, Early plate and implications for the Bering Sea: Jour- Silver, E.A., and Smith, R.B., 1983, Comparison of evolution of the Bering Sea by collision of oce- nal of Geophysical Research, v. 88, terrane accretion in modern Southeast Asia and anic rises and North Pacific subduction zones: p. 3439-3446. the Mesozoic North American Cordillera: Geol- Geological Society of America Bulletin, v. 92, Marlow, M.S., Cooper, A.K., Scholl, D.W., and ogy, v. 11, p. 198-202. p. 485-495. McLean, H., 1982, in Leggett, J.K., ed., Trench- Taira, A., Saito, Y., and Hashimoto, M., 1983, The Ben-Avraham, Z., and Uyeda, S., 1983, Entrapment forearc geology; sedimentation and tectonics on role of oblique subduction and strike-slip tecton- origin of marginal seas, in Hilde, T.W.C., and modern and ancient active plate margins: Geo- ics in the evolution of Japan, in Hilde, T.W.C., Uyeda, S., eds., Geodynamics of the western logical Society of London Special Publication and Uyeda, S., eds., Geodynamics of the west- Pacific-Indonesian region: American Geophysi- 10, p. 201-211. ern Pacific-Indonesian region: American Geo- cal Union Geodynamic Series, v. 11, p. 91-104. McCarthy, J., and Scholl, D.W., 1985, Mechanisms physical Union Geodynamic Series, v. 11, Burchfiel, B.C., and Davis, G.A., 1972, Structural of subduction accretion along the central Aleu- p. 303-316. framework and evolution of the southern part of tian Trench: Geological Society of America Bul- Vallier, T.L., Scholl, D.W., Fisher, M.A., von Huene, the cordilleran orogen, western United States: letin, v. 96, p. 691-701. R., and Bruns, T.R., 1987, Geological frame- American Journal of Science, v. 272, p. 97-118. McCarthy, J., Stevenson, A.J., Scholl, D.W., and work of the Aleutian Arc, in Plafker, G., and Churkin, M., Jr., and McKee, E.H., 1974, Thin and Vallier, T.L., 1984, Speculations on the petro- Jones, D.L., eds., Cordilleran orogen, Alaska: layered subcontinental crust of the Great Basin, leum geology of the accretionary body: An ex- Geological Society of America Decade of North western North America, inherited from Paleo- ample from the central Aleutians: Marine and American Geology Volume G-l (in press). zoic marginal ocean basins: Tectonophysics, Petroleum Geology, v. 12, p. 151-167. Wallace, W.K., and Engebretson, D.C., 1984, Rela- v. 23, p. 1-15. McGeary, S.E., and Ben-Avraham, Z., 1981, Al- tionships between plate motions and Late Coney, P.J., Jones, D.L., and Monger, J.W.H., 1980, lochthonous terranes in Alaska: Implications for Cretaceous to Paleocene magmatism in Cordilleran suspect terranes: Nature, v. 288, the structure and evolution of the Bering Sea southwestern Alaska: Tectonics, v. 3, p. 329-333. shelf: Geology, v. 9, p. 608-614. p. 295-315. Cooper, A.K., Marlow, M.S., and Scholl, D.W., McLean, H., 1979, Review of petroleum geology of Woods, M.T., and Davies, G.F., 1982, Late Creta- 1976a, Mesozoic magnetic lineations in the Ber- Anadyr and Khatyrka Basins, USSR: American ceous genesis of the Kula plate: Earth and ing Sea marginal basin: Journal of Geophysical Association of Petroleum Geologists Bulletin, Planetary Science Letters, v. 58, p. 161-166. Research, v. 81, p. 1916-1934. v. 63, p. 1467-1477. Zinkevich, V.P., Kazimirov, A.D., and Peyve, A.A., Cooper, A.K., Scholl, D.W., and Marlow, M.S., Patton, W.W., Jr., Lanphere, M.A., Miller, T.P., and 1983, Tectonics of the continental margins of 1976b, Plate tectonic model for the evolution of Scott, R.A., 1976, Age and tectonic significance the Bering Sea: Geotectonics, v. 17, p. 513-525. the Bering Sea Basin: Geological Society of of volcanic rocks on St. Matthew Island, Bering ACKNOWLEDGMENTS America Bulletin, v. 87, p. 1119-1126. Sea, Alaska: U.S. Geological Survey Journal of We especially thank our colleagues Eli Silver, Cooper, A.K., Marlow, M.S., and Ben-Avraham, Z., Research, v. 4, p. 67-73. Jason Saleeby, David Stone, and David Engebretson 1981, Multichannel seismic evidence bearing Rea, D.K., and Dixon, J.M., 1983, Late Cretaceous for reading initial drafts of our manuscript and pro- on the origin of Bowers Ridge, Bering Sea: and Paleogene tectonic evolution of the North viding guidance and counsel needed to improve its Geological Society of America Bulletin, v. 92, Pacific Ocean: Earth and Planetary Science Let- science content and sharpen its thematic focus. The p. 474-484. ters, v. 65, p. 145-166. illustrations were crafted and in part designed by Engebretson, D.C., Cox, A., and Gordon, R.G., Rubenstone, J.L., 1984, Geology and geochemistry of our associate Gary Mann. 1984, Relative motions between ocean plates of early Tertiary submarine volcanic rocks of the the Pacific Basin: Journal of Geophysical Re- Aleutian Islands, and their bearing on the devel- Manuscript received May 6,1985 search, v. 89, p. 10,291-10,310. opment of the Aleutian Island Arc [Ph.D. the- Revised manuscript received September 13, 1985 1985, Relative motions between oceanic and sis]: Ithaca, New York, Cornell University. Manuscript accepted October 1,1985 continental plates in the Pacific Basin: Geologi- cal Society of America Special Paper (in press).

GEOLOGY, January 1986 Printed in U.S.A. 47 Downloaded from geology.gsapubs.org on February 1, 2015

Geology

Terrane accretion, production, and continental growth: A perspective based on the origin and tectonic fate of the Aleutian−Bering Sea region

David W. Scholl, Tracy L. Vallier and Andrew J. Stevenson

Geology 1986;14;43-47 doi: 10.1130/0091-7613(1986)14<43:TAPACG>2.0.CO;2

Email alerting services click www.gsapubs.org/cgi/alerts to receive free e-mail alerts when new articles cite this article Subscribe click www.gsapubs.org/subscriptions/ to subscribe to Geology Permission request click http://www.geosociety.org/pubs/copyrt.htm#gsa to contact GSA Copyright not claimed on content prepared wholly by U.S. government employees within scope of their employment. Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms to further education and science. This file may not be posted to any Web site, but authors may post the abstracts only of their articles on their own or their organization's Web site providing the posting includes a reference to the article's full citation. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society.

Notes

Geological Society of America