THE MAIN EVOLUTION PATTERN OF PHANEROZOIC MANTLE IN THE EASTERN CHINA: THE “MUSHROOM CLOUD” MODEL
THE MAIN EVOLUTION PATTERN OF PHANEROZOIC MANTLE IN THE EASTERN CHINA: THE “MUSHROOM CLOUD” MODEL
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作者：
Lu Feng
本文根据中国东部三大地幔域的划分、地球物理资料和地幔岩石学研究，提出了中国东部中生代地幔演化模式：古老的岩石圈地幔主要由难熔低密度橄榄岩组成，同时还必须考虑相对于软流圈的浮力和老地幔的稳定性。（亚大陆岩石圈地幔）在晚白垩世不能被重力作用拆沉-新生代SCLM成分丰富，二辉橄榄岩明显不同于老SCLM，热地幔物质呈蘑菇云状隆起，与老地幔残留物的边界陡倾，这是新生代SCLM地幔演化的主要模式。中国东部中生代，中国东部大部分地区地幔地温升高，高于老岩石圈地幔和新生代地幔，中生代地壳厚度可能大于老和新生代。老地幔中低速低阻物质为流体，熔融性低的熔体以脉状和/或脉状产出。或透镜体新生代地幔中的物质是热的软流圈，呈蘑菇状，中生代则可能富含玄武质岩浆，形成蘑菇状平流层。中生代壳幔之间发生了最重要的相互作用，而在老的和新生代，则在岩石圈和软流圈之间
According to the discrimination of three mantle domains, geophysical data and the research on petrology of mantle in Eastern China, the evolution pattern of Phanerozoic mantle is proposed in this paper The old lithospheric mantle is mainly composed of refractory low density peridotites, while the buoyancy relative to the asthenosphere and the stability of old mantle must also be taking into account Therefore the old SCLM (sub continental lithosphere mantle)can not be delaminated by gravitation processes In Late Cretaceous—Cenozoic the composition of SCLM is fertile in lherzolite that is different evidently from the old SCLM These hot mantle materials uplifted as several mushroom cloud and their boundaries with old mantle relicts were steeply inclined This is the main evolution pattern of mantle in the eastern China In Mesozoic, the geotherm of mantle was raised in most regions of the eastern China and was hotter than that of the old lithospheric mantle and than that of Cenozoic one The thickness of the crust in Mesozoic may be thicker than that in the older and Cenozoic The low velocity/low resistance materials in the old mantle were fluids and melts with low meltability occurred as veins and/or lenses Those materials in Cenozoic mantle were hot asthenospheric and presented as several mushrooms and those in Mesozoic may be abounded in basaltic magmas, as forming mushroom advective stratosphere In Mesozoic, the most important interaction occurred between the crust and the mantle, whereas in the older and Cenozoic it did between the lithosphere and the asthenosphere