scholarly journals Various Ages of Recycled Material in the Source of Cenozoic Basalts in SE China: Implications for the Role of the Hainan Plume

2020 ◽  
Vol 61 (6) ◽  
Author(s):  
Yan-Qing Li ◽  
Hiroshi Kitagawa ◽  
Eizo Nakamura ◽  
Changqian Ma ◽  
Xiangyun Hu ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Pacific Plate ◽  
Late Cenozoic ◽  
Rock Composition ◽  
Se Asia ◽  
Time Space ◽  
The Pacific ◽  
Different Ages ◽  
Se China ◽  
Basaltic Lavas

Abstract Subduction processes introduce crustal materials into the mantle, and mantle plumes return them to the surface. However, when and how the subducted materials were recorded in the plume-related basalts remains unclear. Here we investigate geochronology, bulk-rock composition, and Sr–Nd–Pb isotopes of Cenozoic basalts from Southeast China, occurring near the west Pacific subduction zone and the seismically detected Hainan plume. Volcanism beginning in the late Oligocene in the continental margin of SE China consistently becomes younger landward. Together with a compilation of published results on the synchronous basalts from the South China Sea seamounts and the Indochina peninsula, the volcanoes close to the Pacific subduction zone exhibit more radiogenic Pb and Sr isotopes associated with less radiogenic Nd isotopes compared with those of the inland volcanoes. Such spatiotemporal variations in radiogenic isotopes imply oceanic crusts of different ages in the source, each corresponding to a different geographical volcanic belt. Major-element features such as low CaO, high TiO2 and high Fe/Mn ratios imply that pyroxenite/eclogite could serve as a source lithology of the SE China basalts. Specific trace-element signatures reveal the important roles of recycled oceanic crust along with surface sediment, which was inconsistently dehydrated during subduction. A geologically, geochemically, and geophysically plausible scenario is proposed to illustrate the time–space–source correlation of the late Cenozoic basaltic lavas in SE Asia. The Hainan plume delivered the ancient subducted crust (1·5 Ga) from the core–mantle boundary and, subsequently, the subducted Pacific plate crustal materials from the mantle transition zone to the shallow mantle as a result of mantle convection induced by continuous subduction of the Pacific plate. Such recycled materials of different ages contributed to the geographical compositional heterogeneities of the late Cenozoic basaltic lavas in SE Asia.

Late Cenozoic basaltic lavas from the Changbaishan-Baoqing Volcanic Belt, NE China: Products of lithosphere-asthenosphere interaction induced by subduction of the Pacific plate

2018 ◽  
Vol 164 ◽  
pp. 260-273 ◽  
Author(s):  
Song-Yue Yu ◽  
Yi-Gang Xu ◽  
Sheng-Hua Zhou ◽  
Jiang-Bo Lan ◽  
Lie-Meng Chen ◽  
...  
Keyword(s):  
Volcanic Belt ◽  
Pacific Plate ◽  
Late Cenozoic ◽  
Ne China ◽  
The Pacific ◽  
Basaltic Lavas

Confirming sharp bending of the Pacific plate in the northern Japan trench subduction zone by applying a traveltime mapping method

2006 ◽  
Vol 157 (1-2) ◽  
pp. 72-85 ◽  
Author(s):  
Gou Fujie ◽  
Aki Ito ◽  
Shuichi Kodaira ◽  
Narumi Takahashi ◽  
Yoshiyuki Kaneda
Keyword(s):  
Subduction Zone ◽  
Mapping Method ◽  
Pacific Plate ◽  
Japan Trench ◽  
The Pacific ◽  
Northern Japan

Mesozoic large magmatic events and mineralization in SE China: oblique subduction of the Pacific plate

2010 ◽  
Vol 53 (5-6) ◽  
pp. 704-726 ◽  
Author(s):  
Fang-Yue Wang ◽  
Ming-Xing Ling ◽  
Xing Ding ◽  
Yan-Hua Hu ◽  
Ji-Bin Zhou ◽  
...  
Keyword(s):  
Pacific Plate ◽  
Oblique Subduction ◽  
The Pacific ◽  
Se China

Age progression along the Society hotspot chain (French Polynesia) based on new unspiked K-Ar ages

2005 ◽  
Vol 176 (2) ◽  
pp. 135-150 ◽  
Author(s):  
Hervé Guillou ◽  
René C. Maury ◽  
Sylvain Blais ◽  
Joseph Cotten ◽  
Christelle Legendre ◽  
...  
Keyword(s):  
Linear Chain ◽  
Age Distribution ◽  
French Polynesia ◽  
Temporal Variations ◽  
Pacific Plate ◽  
Plate Motion ◽  
Age Progression ◽  
Plate Velocity ◽  
Time Space ◽  
The Pacific

Abstract New K-Ar dates of volcanic rocks from five of the nine islands of the Society Archipelago (Moorea, Huahine, Raiatea, Bora Bora and Maupiti), confirm a Pacific plate velocity of around 11 cm/a during the last 4.3 m.y. These new data allow us to analyse the age-distance relationship along the chain and to evaluate possible temporal variations in the activity of the Society hotspot. A clear increase of ages is observed along the linear chain away from the present Society hotspot location. The time-space relationship between Taiarapu, Tahiti-Nui and Moorea can be explained by a simple hotspot model. Nevertheless, the simple fixed hotspot model assuming constant Pacific plate velocity may need adjustments to fully explain the age progression along the Archipelago. The slight departures from a linear age distribution can be explained by changes in Pacific plate motion which occurred at 5 and 3 Ma. In addition, the contemporaneous magmatic activities in the pairs Bora-Bora/Tahaa, Raiatea/Huahine, Maiao/Moorea require additional lithospheric control on magma transport. Combined with the hotspot activity, lithospheric loading may have produced extension and triggered volcanism along already existing fractures linking paired islands. The most likely model for the Society chain, proposed by McNutt [1998], involves a plume originating from a wide deep thermally anomalous zone (the Pacific Superswell) as a rising diapir (hotspot of secondary type according to the classification of Courtillot et al. [2003]). It melted during ascent and ponded beneath the Pacific plate to form short linear island chains showing rather good age vs. distance correlations.

Seismological evidence for tearing of the Pacific plate at the northern termination of the Tonga subduction zone

Geology ◽  
1998 ◽  
Vol 26 (7) ◽  
pp. 659 ◽  
Author(s):  
David W. Millen ◽  
Michael W. Hamburger
Keyword(s):  
Subduction Zone ◽  
Pacific Plate ◽  
The Pacific ◽  
Tonga Subduction Zone

Fault tectonic analysis of aftershocks of the 2011 Tohoku, Japan, earthquake: interaction between three different tectonic domains and approximation of stress magnitude

2020 ◽  
Author(s):  
Pom-yong Choi
Keyword(s):  
Subduction Zone ◽  
Continental Crust ◽  
Focal Mechanism ◽  
Coastal Area ◽  
Pacific Plate ◽  
Japan Meteorological Agency ◽  
Vertical Load ◽  
Normal Faulting ◽  
Stress Tensors ◽  
The Pacific

<p>In order to elucidate the regional variation of stress field in the eastern part of Japan after the 2011 Tohoku earthquake of M=9.3, we tried to analyze focal mechanism data of earthquakes that occurred in 2011, presented by the Japan Meteorological Agency (JMA). Although earthquakes (aftershocks) occurred largely in the offshore area along the subduction zone of the Pacific plate under the North American and Eurasian plates, focal mechanism data presented by JMA are mainly those on land. For fault tectonic analysis, the suggested focal mechanism data are classified into appropriate populations on the basis of clusters and focal depths to reduce the bias and errors of stress tensors resulting from areal stress variation and varying vertical load. According to the results, the stress types of determined stress tensors consist of reverse, wrench and normal faulting ones. As for reverse faulting stresses in which the vertical load is the minimum principal stress axis, those of NW-SE compression prevail, which may be tightly related to northwestward movement of the Pacific plate. Those of E-W compression are determined in the continental crust deeper than about 9 km around Yamagata and in the lower part of subducting oceanic crust. In the Kanagawa and Chiba areas, determined stress tensors display NNW-SSE compression as well as NW-SE and E-W compressions. The NNW-SSE compression seems to be related to the movement of the Philippine Sea plate. Stress tensors of wrench faulting type are found in the continental crust far from the subduction zone of the Pacific plate, displaying NW-SE and E-W compressions in the shallower and deeper parts of crust, respectively. The E-W compression is presumably associated with the Himalayan tectonic domain. Determined stress tensors of normal faulting type show diverse extension directions: NW-SE extension in the coastal area, parallel to the Pacific compression, and E-W or NE-SW extension elsewhere. Especially, numerous focal mechanism data showing normal faulting stresses are present in the coastal area of Fukushima and Ibaraki, from which Poisson’s ratio of shallow crust was determined to be 0.25 to 0.27 using friction lines on Mohr’s circles and focal depths (or corresponding vertical loads). Additional horizontal stress related to the northwestward motion of the Pacific plate was estimated to be 46, 122 and 286 MPa in three groups of 0 to1.5, 1.5 to 4.5 and 3.5 to 11.5 kilometers in depth, respectively.</p>

scholarly journals Influence of the upper-mantle convective cell and related Pacific plate subduction on Arctic tectonics in the late Cretaceous–Cenozoic

2019 ◽  
pp. 27-45
Author(s):  
M. V. Kononov ◽  
L. I. Lobkovsky
Keyword(s):  
Pacific Ocean ◽  
Subduction Zone ◽  
Upper Mantle ◽  
Convective Cell ◽  
Pacific Plate ◽  
The Arctic ◽  
The Pacific ◽  
Eurasian Basin ◽  
Pacific Plate Subduction ◽  
Plate Subduction

Abstract The paper considers the history of the spreading of the Eurasian basin. The sharp deceleration of the spreading rate in the Eocene about 46 million years ago, which is fixed by the distribution of linear magnetic anomalies, is noted. That jump in velocity is clarified from the perspective of the geodynamic model but shouldnt be explained by the northern motion of Greenland. The geodynamic processes of the Pacific subduction zone generate an upper mantle convective cell with return flow dragging the Arctic continental lithosphere in the direction of the Pacific subduction zone. The geodynamic mechanism is confirmed by seismic tomographic mantle sections of the northeastern margin of Asia and the numerical model of the upper mantle convection of the active continental margin. It is the activity of the upper mantle convective return cell, which is determined by the runoff volume and, ultimately, the speed and direction of the Kula plate and Pacific plate subduction vectors in the subduction zone, affects tectonics and kinematics of the plates of the Eurasian basin. In the Middle CretaceousMiddle Eocene and for about 73 Ma the return cell has been active, since the Kula and Pacific plates move north and submerged orthogonally beneath the Central Arctic. After the Middle Eocene geodynamic reorganization about 47.5 million years ago, oceanic plates in the Pacific Ocean begin to move to the northwest. As a result, the transport of the oceanic Pacific Ocean lithospheric substance to the arctic convective return cell has practically ceased. After the restructuring, the spreading of the Eurasian basin slowed down about 46 million years ago to an ultra-slow regime. The main tectonic and geodynamic consequences of applying the proposed geodynamic model for the Arctic in the Late CretaceousCenozoic are considered.

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