The Upper Mantle Flow Beneath the North China Platform

Author(s):  
Rong-Shan Fu ◽  
Jian-Hua Huang ◽  
Zhe-Xun Wei
1996 ◽  
Vol 146 (3-4) ◽  
pp. 649-659 ◽  
Author(s):  
Rong-Shan Fu ◽  
Jian-Hua Huang ◽  
Zhe-xun Wei

1991 ◽  
Vol 55 (379) ◽  
pp. 263-276 ◽  
Author(s):  
Sang Longkang

AbstractBased on geological studies, 141 rock analyses and 5 trace element analyses of metabasites, the present paper deals with the rock association, chemical features, protolith formation and the original tectonic settings upwards through the Lower Proterozoic metamorphic strata in the Dabieshan-Lianyungang area, in the south-east of the North China Platform. The results of the study indicate that the lower and middle parts of the metamorphic strata comprise terrigenous clastics, phosphoritic and aluminous sedimentary formations which formed under stable continental margin conditions. In the middle-upper part a calc-alkaline volcano-sedimentary formation under the active continental margin was developed. The Lower Proterozoic meta-strata of sedimentary-volcanosedimentary origin from bottom upwards suggest that the tectonic evolution of the south-eastern margin of the North China Platform is a process from stabilization to mobilization. This process suggests a northward subduction of the Yangtze Plate under the North China Plate during the later part of the early Proterozoic.


Geology ◽  
2020 ◽  
Vol 48 (6) ◽  
pp. 584-588 ◽  
Author(s):  
Jun-Bo Zhang ◽  
Yong-Sheng Liu ◽  
Mihai N. Ducea ◽  
Rong Xu

Abstract Here, we present coupled geochemical and Sr-Nd-Pb-S isotopic data of Early Cretaceous primitive gabbros from the North China craton. Strikingly, these rocks have highly unradiogenic lead compositions (206Pb/204Pb = 16.58 ± 0.24) and anchor one extreme end member (low 206Pb/204Pb and 143Nd/144Nd) in the global array of oceanic-island volcanics. Our study shows that they originated from an Archean fluid-metasomatized refractory peridotite source, in which highly unradiogenic lead was preferentially released with subducted Archean seawater and sequestered into recrystallized sulfides at shallow mantle depths. Sulfide/silicate partition coefficients for lead show a negative pressure dependence: Lead is more enriched in sulfide with decreasing pressure. Sulfide-bearing and iron-poor harzburgite as well as dunite residues at shallow mantle are expected to develop low U/Pb (and thereby low time-integrated 206Pb/204Pb) relative to a deeper upper-mantle source. Our preferred interpretation is that an Archean, highly unradiogenic lead reservoir may be stored in the spinel-facies refractory cratonic mantle.


2020 ◽  
Author(s):  
Yan Cai ◽  
Jianping Wu

<p>North China Craton is the oldest craton in the world. It contains the eastern, central and western part. Shanxi rift and Taihang mountain contribute the central part. With strong tectonic deformation and intense seismic activity, its crust-mantle deformation and deep structure have always been highly concerned. In recent years, China Earthquake Administration has deployed a dense temporary seismic array in North China. With the permanent and temporary stations, we obtained the crust-mantle S-wave velocity structure in the central North China Craton by using the joint inversion of receiver function and surface wave dispersion. The results show that the crustal thickness is thick in the north of the Shanxi rift (42km) and thin in the south (35km). Datong basin, located in the north of the rift, exhibits large-scale low-velocity anomalies in the middle-lower crust and upper mantle; the Taiyuan basin and Linfen basin, located in the central part, have high velocities in the lower crust and upper mantle; the Yuncheng basin, in the southern part, has low velocities in the lower crust and upper mantle velocities, but has a high-velocity layer below 80 km. We speculate that an upwelling channel beneath the west of the Datong basin caused the low velocity anomalies there. In the central part of the Shanxi rift, magmatic bottom intrusion occurred before the tension rifting, so that the heated lithosphere has enough time to cool down to form high velocity. Its current lithosphere with high temperature may indicate the future deformation and damage. There may be a hot lithospheric uplift in the south of the Shanxi rift, heating the crust and the lithospheric mantle. The high-velocity layer in its upper mantle suggests that the bottom of the lithosphere after the intrusion of the magma began to cool down.</p>


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