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Address : Peking University, China
Celebration date : 20 Saturday September 2008
Author name : Shao, Ji’an

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  • Article title : Space-time distribution of the Mesozoic-Cenozoic volcanic activities in the Liao-Meng Geotraverse, China
    Article type : Tectonic & Seismotectonic
    Location : International Geological Congress,oslo 2008

    Fulltext :

    It has already been indisputable that the oceanic plates have been spreading since the Mesozoic. This spreading is suggested to be controlled by convection of the underlying asthenosphere. It is, there, interesting whether there is convection of asthenosphere beneath the continental lithosphere and what would be the consequence of this. The Liao-Meng Geotraverse is selected and investigated on its chronology (ages of 183 samples are used) and tectonic background in this paper. The west Liaoning Province is located in the centre of this 800 km long and nearly east-west oriented traverse. The studies reveal and identify that the distribution of volcanic rocks in this area forms a symmetrical space-time pattern with the older Mesozoic (since 130 Ma) in the center and the younger Cenozoic in the periphery. Unlike the oceanic lithosphere, the craton continental lithosphere in the North China would not be able to easily split and create new crust directly by convection of the asthenospheric materials, but to generate the symmetric older-in-the-center-and-younger-outside volcanic-rock belt by the up-surging asthenospheric diapiris. A similar case of the symmetric spreading is seen in the the Basin-Range Province, U.S.A.. This consists of, at least, a form of spreading of the continental lithospheres, which is much more complicated than that of the oceanic crusts and may involve various extensional deformations within the continental crusts. Spreading of the continental lithosphere in this area since 100 Ma is a response to the rising and convection of the asthenospheric materials from the depth, and the latter is in turn related to activation of the North China Craton in the Mesozoic and also contributes to thinning of the North China lithosphere. Spreading and thinning of the lithosphere here reaches the maximum in the Paleogene (45¨C23 Ma).

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