Extrusion tectonics of the Okhotsk Plate, northeast Asia

Riegel, S. A.; Fujita, Kazuya; Козьмин, Б. М.; Imaev, V. S.; Cook, David B.

doi:10.1029/93gl00267

Cited by 61 publications

(58 citation statements)

References 10 publications

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“…K-Ar isotope age dating of dredged igneous samples indicates that the basement was formed no later than the Cretaceous [Gnibidenko and Khvedchuk, 1982]. As for the tectonic identity of the Okhotsk block, there has been no consensus on whether it involves an independent plate [Cook et al, 1986;Riegel et al, 1993] or it is in fact part of the North American Plate [Chapman and Solomon, 1976;DeMets, 1992;Seno et al, 1996].…”

Section: Tectonic Settingmentioning

confidence: 99%

Low V_p/V_s ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic p_MP, s_MP, and s_MS underside reflections from the Moho

Zheng

Lay

2006

J. Geophys. Res.

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[1] Teleseismic ground motion recordings of deep earthquakes often contain clear seismic wave reflections from the free surface above the source (pP, sP, sS), with isolated precursors (p M P, s M P, and s M S) produced by underside reflections from the Moho (the crust-mantle boundary) below the free surface reflection points. The waveforms of the depth phases and their precursors are readily modeled, providing constraints, for steep angles of incidence, on integrated two-way crustal travel times and Moho shear and compressional impedance contrasts above deep earthquake source regions. We model surface reflection waveforms in stacks of three-component, long-period WWSSN and digital broadband seismograms for signals traversing the crust and upper mantle beneath the Sea of Okhotsk, which overlies deep earthquakes in the subducted Kurile slab. The crust beneath most of the Sea of Okhotsk is 19-25 km thick, indicating a submerged continental margin, with minor crustal thinning toward the Kuril back-arc basin, where thin oceanic crust is found. Modeling p M P and s M S phases that sample the same subregion provides tight constraints on the V p /V s ratio in the crust and uppermost mantle (assuming common density structure and consistent crustal thickness for P and S waves); the absolute velocities are not constrained by the data. We find unusually low V p /V s ratios in the range 1.6-1.7 for the uppermost mantle under the Sea of Okhotsk and comparably low average V p /V s ratios for the crust in several regions. The presence of fluids and extensive silica enrichment, possibly involving low-temperature veining, are viable explanations for the anomalous V p /V s ratios; this may represent an important process of continentalization taking place landward from the volcanic arc in subduction zones.Citation: Zheng, Y., and T. Lay (2006), Low V p /V s ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic p M P, s M P, and s M S underside reflections from the Moho,

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Section: Tectonic Settingmentioning

confidence: 99%

Low V_p/V_s ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic p_MP, s_MP, and s_MS underside reflections from the Moho

Zheng

Lay

2006

J. Geophys. Res.

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“…Plate geometry in this northwest "corner" is currently under debate [e.g. Riegel et al, 1993;Mackey et al, 1997;McElfresh et al, 2002;Bourgeois et al, 2006]. Some authors treat Kamchatka as a part of the North American plate [e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Park et al, 2002], while others locate it on a smaller Okhotsk block (or microplate) [e.g. Zonenshain and Savostin, 1979;Riegel et al, 1993] and add a Bering block east of it [e.g. Lander et al, 1994;Mackey et al, 1997].…”

Section: Introductionmentioning

confidence: 99%

Late Pleistocene-Holocene volcanism on the Kamchatka Peninsula, Northwest Pacific Region

Пономарева¹,

Мелекесцев²,

Braitseva³

et al. 2007

Volcanism and Subduction: The Kamchatka Region

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Late Pleistocene-Holocene volcanism in Kamchatka results from the subduction of the Pacific Plate under the peninsula and forms three volcanic belts arranged in en echelon manner from southeast to northwest. The cross-arc extent of recent volcanism exceeds 250 km and is one of the widest worldwide. All the belts are dominated by mafic rocks. Eruptives with SiO 2 >57% constitute ~25% of the most productive Central Kamchatka Depression belt and ~30% of the Eastern volcanic front, but <10% of the least productive Sredinny Range belt.All the Kamchatka volcanic rocks exhibit typical arc-type signatures and are represented by basalt-rhyolite series differing in alkalis. Typical Kamchatka arc basalts display a strong increase in LILE, LREE and HFSE from the front to the back-arc. La/Yb and Nb/Zr increase from the arc front to the back arc while B/Li and As, Sb, B, Cl and S concentrations decrease. The initial mantle source below Kamchatka ranges from N-MORB-like in the volcanic front and Central Kamchatka Depression to more enriched in the back arc. Rocks from the Central Kamchatka Depression range in 87 Sr/ 86 Sr ratios from 0.70334 to 0.70366, but have almost constant Nd isotopic ratios ( 143 Nd/ 144 Nd 0.51307-0.51312). This correlates with the highest U/Th ratios in these rocks and suggest the highest fluid-flux in the source region.Holocene large eruptions and eruptive histories of individual Holocene volcanoes have been studied with the help of tephrochronology and 14 C dating that permits analysis of time-space patterns of volcanic activity, evolution of the erupted products, and volcanic hazards.

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“…As shown in Figure 4, the CSB ex tends from the Arctic Mid-Ocean ridge, through the Laptev Sea, and into the conti nent, where the stress regime changes to transpression. The CSB then splits into two main branches, a northern left-lateral transpressional zone extending to Kamchatka, and a southern, right-lateral, transpressional zone extending to Sakhalin [Riegel et al, 1993]. This geometry and stress regime is consis tent with the southeastward extrusion of the Okhotsk plate.…”

Section: Present-day Seismicity and Tectonicsmentioning

confidence: 97%

Cooperative program helps decipher tectonics of northeastern Russia

Fujita¹,

Stone²,

Layer³

et al. 1997

EoS Transactions

Self Cite

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Recently obtained paleomagnetic, geochronologic, and seismic data are greatly improving our understanding of the tectonics of northeastern Russia, which lies in an accretionary zone between the stable platforms of the North American and Eurasian plates. In particular, the present‐day plate boundaries and motions have been clarified and a model has been developed for the accretionary history of the poorly understood Mesozoic fold belts of northeastern Russia. The evolution of northeastern Russia appears to be similar to that of Alaska and the Canadian Cordillera, and many similar tectonic and stratigraphic features can be identified in all three regions.

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Extrusion tectonics of the Okhotsk Plate, northeast Asia

Cited by 61 publications

References 10 publications

Low V_p/V_s ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic p_MP, s_MP, and s_MS underside reflections from the Moho

Low V_p/V_s ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic p_MP, s_MP, and s_MS underside reflections from the Moho

Late Pleistocene-Holocene volcanism on the Kamchatka Peninsula, Northwest Pacific Region

Cooperative program helps decipher tectonics of northeastern Russia

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Extrusion tectonics of the Okhotsk Plate, northeast Asia

Cited by 61 publications

References 10 publications

Low Vp/Vs ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic pMP, sMP, and sMS underside reflections from the Moho

Low Vp/Vs ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic pMP, sMP, and sMS underside reflections from the Moho

Late Pleistocene-Holocene volcanism on the Kamchatka Peninsula, Northwest Pacific Region

Cooperative program helps decipher tectonics of northeastern Russia

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Product

Resources

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Low V_p/V_s ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic p_MP, s_MP, and s_MS underside reflections from the Moho

Low V_p/V_s ratios in the crust and upper mantle beneath the Sea of Okhotsk inferred from teleseismic p_MP, s_MP, and s_MS underside reflections from the Moho