Tectonics of the Soviet Far East

Kosygin, Yu. A.; Parfenov, Leonid M.

doi:10.1007/978-1-4757-1248-3_8

Cited by 15 publications

(6 citation statements)

References 6 publications

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“…Intracontinental faulting, mostly strike-slip and normal, thus appears to have characterized the Triassic and Jurassic periods over much of the Tien Shan and Dzungaria. Such deformation may have been a consequence of greater coeval movements along the boundaries of the Central Asian plate, particularly in northern Mongolia and southeastern Siberia, in keeping with mounting geological and paleomagnetic evidence that welding of that plate with the Angaran continent was completed only in the upper-middle Jurassic period [Kosygin and Parfenov, 1981;Khramov, 1987;Enkin eta/., 1992].…”

Section: Tectonic Historymentioning

confidence: 74%

Active thrusting and folding along the northern Tien Shan and Late Cenozoic rotation of the Tarim relative to Dzungaria and Kazakhstan

Avouac¹,

Tapponnier²,

Bai³

et al. 1993

J. Geophys. Res.

670

604

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We have studied geometries and rates of late Cenozoic thrust faulting and folding along the northern piedmont of the Tien Shan mountain belt, West of Urumqi, where the M=8.3 Manas earthquake occurred on December 23, 1906. The northern range of the Tien Shan, rising above 5000 m, overthrusts a flexural foredeep, filled with up to II ,000 m of sediment, of the Dzungarian basement. Our fieldwork reveals that the active thrust reaches the surface 30 km north of the range front, within a 200-km-long zone of NeogeneQuaternary anticlines. Fault scarps are clearest across inset terraces within narrow valleys incised through the anticlines by large rivers flowing down from the range. In all the valleys, the scarps offset vertically the highest terrace surface by the same amount (10.2±0.7 m). Inferring an early Holocene age (10±2 kyr) for this terrace, which is continuous with the largest recent fans of the piedmont, yields a rate of vertical throw of 1.0±0.3mm/yr on the main active thrust at the surface. A quantitative morphological analysis of the degradation of terrace edf,es that are offset by the thrust corroborates such a rate and yields a mass diffusivity of 5.5±2.5 m /kyr. A rather fresh surface scarp, 0.8±0.15 m high, that is unlikely to result from shallow earthquakes with 6 < M < 7 in the last 230 years, is visible at the extremities of the main fold zone. We associate this scarp with the 1906 Manas earthquake and infer that a structure comprising a deep basement ramp under the range, gently dipping flats in the foreland, and shallow ramps responsible for the formation of the active, fault propagation anticlines could have been activated by that earthquake. If so, the return period of a 1906 type event would be 850 ± 380 years. The small size of the scarp for an earthquake of this magnitude suggests that a large fraction of the slip at depth ( ""2/3) is taken up by incremental folding near the surface. Comparable earthquakes might activate flat detachments and ramp anticlines at a distance from the front of other rising Quaternary ranges such as the San Gabriel mountains in California or the Mont Blanc-Aar massifs in the Alps. We _,:stimate the finite Cenozoic shortening of the folded Dzungarian sediments to be of the order of 30 km and the Cenozoic shortening rate to have been 3 ± 1.5 mrnlyr. Assuming comparable shortening along the Tarim piedmont and minor additional active thrusting within the mountain belt, we infer the rate of shortening across the Tien Shan to be at least 6±3 mm/yr at the longitude of Manas (""85.5°E). A total shortening of 125±30 km is estimated from crustal thickening, assuming local Airy isostatic equilibrium. Under the same assumption, serial N-S sections imply that Cenozoic shortening across the belt increases westwards to 203±50 km at the longitude of Kashgar ( ""76°E), as reflected by the westward increase of the width of the belt. This strain gradient implies a clockwise rotation of Tarim relative to Dzungaria and Kazakhstan of 7 ± 2.5 • around a pole located near the eastern extr...

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Section: Tectonic Historymentioning

confidence: 74%

Active thrusting and folding along the northern Tien Shan and Late Cenozoic rotation of the Tarim relative to Dzungaria and Kazakhstan

Avouac¹,

Tapponnier²,

Bai³

et al. 1993

J. Geophys. Res.

670

604

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“…1, 12). Parallel belts of Mesozoic marine strata and igneous and metamorphic rocks trending northeast from Ulaanbaatar through Siberia to the modern Sea of Okhotsk record the western end of the Mongol-Okhotsk Seaway (Kosygin and Parfenov, 1981;Zonenshain et al, 1990;Figs. 1, 12).…”

Section: Drivers Of Late Mesozoic Extensionmentioning

confidence: 99%

Sedimentary record and tectonic implications of Mesozoic rifting in southeast Mongolia

Graham

Hendrix

Johnson

et al. 2001

Geological Society of America Bulletin

273

250

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The East Gobi basin of Mongolia is a poorly described Late Jurassic-Early Cretaceous extensional province that holds great importance for reconstructions of Mesozoic tectonics and paleogeography of eastern Asia. Extension is especially well recorded in the structure and stratigraphy of the Unegt and Zuunbayan subbasins southwest of Saynshand, Mongolia, where outcrop and subsurface relationships permit recognition of prerift, synrift, and postrift Mesozoic stratigraphic megasequences. Within the synrift megasequence, three sequences developed in response to climatic and rift-related structural controls on sedimentation. Where best exposed along the

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“…fractures arranged as concentric systems. … The fractures …., probably, formed concurrently with the downwarping … of the Tunguska syneclise" [44].…”

Section: Trappean Magmatism Areasmentioning

confidence: 99%

“…9 (from [43], with changes) shows associations of relatively small ringed objects (defined in [43] as volcano structures, superstructures, single-and multi-focus ringed complexes). The syneclise originated on the site of an isometric dome elevation [44], and is tightly connected with trappean magmatism. The trappean magmatism is characterized by "adjacency of the trappean intrusions to curved ….…”

Section: Trappean Magmatism Areasmentioning

confidence: 99%

Origination and development mechanics of the Earth’s morphostructures. Part II: The nature of diatreme, karst and trappean formations, and the chicxulub crater origin

Stazhevsky

2012

J Min Sci

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The article analyzes genesis of representative morphostructures of the Earth, and substantiates that their origin, similarly to the Patomsky crater, is associated with the hydrogen outgassing and pipe formation in the internal part of the Earth, or, to put it otherwise, with the development of different diameter ring shape structures in the hard shell of the planet. Evolution of all the structures can be described with the dilatancy-explosion model, independent of their dimension. The author explains the billions years history of integration of these endogenous structures into great families of different scale, age and depth ring structures. It is shown that this global process is based on the plume-tectonics.A "kimberlite diatreme" origination involves pipe formation and eruption, similarly to the genesis of the Patomsky ring structure (ring structure are hereinafter put as RS) [1], though the mechanism of these processes remains unclear [2]. According to [1], the pipe formation process provides degassing of the subsoil having the solid outer jacket, and the eruption is associated with the presence of explosive gases, such as Н 2 , СН 4 , СО etc., during the outgassing. These notions make up the basis for a dilatancy and explosion model of cratering (or an RS formation) that allowed explaining the Patomsky crater genesis. Figure 1 shows experimental results with sand to simulate pipe formation in the subsoil. The pipe formation phenomenon is a result of deep-level processes, it starts with a focal zone and goes on as subsequent localized shears along conical and cylindrical rupture lines (RL1 and RL2, respectively, in Fig. 1) with a step l governed by a diameter 0 d of the "focus" and the strength of surrounding rocks. Localized deformation surfaces form a cylinder channel in geo-environment, the channel is filled with a granular block-structured medium. The rupture lines act as the maximum softening zones in the substrata and turn into conductor tracks for fluids toward the earth surface.The Patomsky crater originated as a result of collision and mix of juvenile gas and free air at depth 0 0in the said channel, followed with eruption and rock column displacement from the depth 0 h to the surface, and ended with the fall of rocks back into the formed hollow pipe with the height 0 h [1]. The other consequences of the Patomsky RS are (1) a trough-like depression, coaxial with the crater but with larger diameter, with a "root" as the long-living downward-tapered softening zone; (2) concentration of fluids in the softening zone, including waters; (3) increase in the content of these fluid from the said zone periphery to its center; (4) alteration of geophysical fields in radial direction in this zone; (5) appearance of mixed broken crustal rocks, local soil and vegetation at the top near the zone axis.

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Tectonics of the Soviet Far East

Cited by 15 publications

References 6 publications

Active thrusting and folding along the northern Tien Shan and Late Cenozoic rotation of the Tarim relative to Dzungaria and Kazakhstan

Active thrusting and folding along the northern Tien Shan and Late Cenozoic rotation of the Tarim relative to Dzungaria and Kazakhstan

Sedimentary record and tectonic implications of Mesozoic rifting in southeast Mongolia

Origination and development mechanics of the Earth’s morphostructures. Part II: The nature of diatreme, karst and trappean formations, and the chicxulub crater origin

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