Magnetotelluric imaging of a fossil oceanic plate in northwestern Xinjiang, China

Geology ◽  
2020 ◽  
Vol 48 (4) ◽  
pp. 385-389 ◽  
Author(s):  
Y.X. Xu ◽  
B. Yang ◽  
A.Q. Zhang ◽  
S.C. Wu ◽  
L. Zhu ◽  
...  
Keyword(s):  
Subcontinental Lithospheric Mantle ◽  
Oceanic Plate ◽  
Continental Lithosphere ◽  
Magnetotelluric Data ◽  
Long Period ◽  
Continental Plate ◽  
Formation And Evolution ◽  
Magnetotelluric Imaging ◽  
Plate Subduction ◽  
Continental Accretion

Abstract Because an oceanic plate colliding with a continental plate will usually be subducted and recycled into the deep mantle, a fossil oceanic plate after the closure of an ancient ocean has rarely been imaged in the subcontinental lithospheric mantle. This has led to a long-standing debate about the fate of subducted ocean plates. The problem can be addressed by imaging the lithosphere in a continental accretion zone with past ocean subduction. We present a study using long-period magnetotelluric data that reveals a large shallow-mantle conductor in a Phanerozoic accretion area in northwestern Xinjiang, China. This conductor extends >300 km laterally at depths from 120 to 220 km and resembles a segment of a fossil oceanic plate. The reduced resistivity is ascribed to the volatile-bearing metasomatic minerals, based on its relatively fertile nature and low temperature. Our results demonstrate that an oceanic plate can be trapped in continental lithosphere, underscoring the significance of oceanic plate subduction to continental accretion, and shedding new light on our understanding of continental formation and evolution.

PERBANDINGAN SIMPANGAN GEDUNG LANTAI RENDAH DENGAN MENGGUNAKAN 2 TIPE BRESING

EXTRAPOLASI ◽  
2020 ◽  
Vol 17 (2) ◽  
pp. 35-44
Author(s):  
Nurul Rochmah
Keyword(s):  
Pacific Ocean ◽  
Steel Structure ◽  
Steel Structures ◽  
Oceanic Plate ◽  
Lateral Loads ◽  
Continental Plate ◽  
Eurasian Continent ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Eccentric Bracing

AbstractIndonesia is one of the areas where earthquakes often occur, one reason is that Indonesia is located on the border of the oceanic plate, namely the pacific ocean and the continental plate, namely the Eurasian continent. Where in these areas plate shifts often occur which cause frequent earthquakes.In minimizing casualties due to building failure due to earthquakes, one of them is necessary to make a building that has sufficient ductility so that in this study using a steel structure building.In steel structures, to make the structure more resistant to lateral loads, it is necessary to apply bracing. In this study, we try to compare the eccentric and concentric bracing displacement in steel structure buildings.Based on the results obtained from the comparison of these displacements, it is found those displacements due to eccentric bracing is smaller than the concentric bracing  AbstrakIndonesia termasuk daerah yang sering terjadi gempa, salah sebabnya karena wilayah Indonesia terletak di daerah perbatasan lempeng samudera yaitu samudera pasisfik dan lempeng benua yaitu benua Eurasia. Dimana di daerah tersebut sering terjadi pergeseran lempeng yang menyebabkan sering terjadi gempa.Dalam meminimalisir korban akibat kegagalan bangunan akibat gempa salah satunya perlu membuat suatu bangunan yang mempunyai daktilitas yang cukup sehingga dalam penelitian ini memakai gedung struktur baja.Pada Struktur baja untuk lebih membuat struktur bisa tahan terhadap beban lateral maka perlu diberi bresing. Dalam penelitian ini mencoba untuk membandingkan simpangan bresing eksentrik dan konsentrik pada gedung struktur baja.Berdasarkan hasil yang diperoleh dari perbandingan simpangan tersebut, maka diperoleh simpangan akibat bresing eksentrik lebih kecil di banding bresing konsentrik.

Formation and evolution of Precambrian continental lithosphere in South China

2013 ◽  
Vol 23 (4) ◽  
pp. 1241-1260 ◽  
Author(s):  
Shao-Bing Zhang ◽  
Yong-Fei Zheng
Keyword(s):  
South China ◽  
Continental Lithosphere ◽  
Formation And Evolution

Oceanic plate subduction history in the western Pacific Ocean: Constraint from late Mesozoic evolution of the Tan-Lu Fault Zone

2018 ◽  
Vol 61 (4) ◽  
pp. 386-405 ◽  
Author(s):  
Guang Zhu ◽  
Cheng Liu ◽  
Chengchuan Gu ◽  
Shuai Zhang ◽  
Yunjian Li ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Fault Zone ◽  
Western Pacific ◽  
Western Pacific Ocean ◽  
Oceanic Plate ◽  
Late Mesozoic ◽  
The Western Pacific ◽  
Plate Subduction

Seismogenic structures in western Yunnan revealed by three-dimensional magnetotelluric imaging

2020 ◽  
Author(s):  
Qinghua Huang ◽  
Tao Ye ◽  
Xiaobin Chen
Keyword(s):  
Three Dimensional ◽  
Magnetotelluric Data ◽  
Block Boundary ◽  
Strong Earthquakes ◽  
Yunnan Region ◽  
Continental Block ◽  
Western Yunnan ◽  
Resistivity Model ◽  
Seismogenic Structures ◽  
Magnetotelluric Imaging

<p>Influenced by the extrusion of Tibetan blocks and Indo-Burmese collision, the region in western Yunnan is associated with active seismicity and Quaternary volcanoes. Based on broadband magnetotelluric data collected in western Yunnan, we obtain a three-dimensional crustal electrical resistivity model after various data processing and three-dimensional inversion test. The above resistivity model reveals the seismogenic structures of the moderate and strong earthquakes in this tectonic region. We investigate the possible relationship between the seismicity and the electrical structure in western Yunnan region. The results indicate that earthquakes in this region tend to occur in the transition zone between the resistive and conductive structures. Our results also show that one resistive body imaged at the mid-lower crust may have blocked the previously proposed crustal channel flow along this intra-continental block boundary to the east of Tibetan Plateau. Our resistivity model suggests a bifurcation of the crustal flow in western Yunnan. This bifurcated crustal flow structure may play an important dynamical role in the seismogenesis of the earthquakes in western Yunnan.</p>

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