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中国东部华北陆块和华南陆块的地幔包体单矿物和全岩水含量变化很大,总体低于全球其他克拉通和非克拉通岩石圈地幔包体单矿物和全岩水含量.然而,具有新生岩石圈地幔来源的莒南橄榄岩包体单矿物和全岩水含量总体高于其他中国东部岩石圈地幔包体,指示中国东部新生岩石圈地幔的初始水含量并不低.地幔包体中单矿物水含量与Mg~#之间无明显相关关系,其中的辉石缺乏水扩散环带,因此地幔包体的低水含量与包体随玄武岩岩浆上升过程的水扩散丢失无关.大陆岩石圈地幔底部受到热软流圈地幔烘烤有可能会造成水的扩散丢失,但是熔体提取也可能是引起低水含量的原因之一.通过斑晶水含量计算得到的中国东部中生代和新生代玄武岩初始熔体水含量均高于正常洋中脊玄武岩.中生代玄武岩初始熔体水含量与岛弧玄武岩类似,而新生代玄武岩初始熔体水含量则与洋岛玄武岩和弧后盆地玄武岩类似(部分地区与岛弧玄武岩类似).这些结果表明,大陆玄武岩地幔源区相对富水,指示其地幔源区曾经受到深俯冲地壳脱水所形成的富水流体/含水熔体的交代,使其水含量升高.中国东部新生代幔源巨晶、包体矿物和玄武岩斑晶的氢同位素组成变化也很大,反映中国东部新生代岩石圈地幔氢同位素组成高度不均一.新生代岩石圈地幔具有高于亏损地幔的水含量和偏离亏损地幔值的氢同位素组成,反映其受到过俯冲太平洋板片部分熔融所产生熔体的交代.俯冲大洋板片脱水熔融产生的富水流体和含水熔体对大陆岩石圈地幔底部的交代导致其水含量增加,引起底部岩石黏滞度降低,进而导致岩石强度的降低,使其容易被构造侵蚀乃至拆沉.因此,大洋俯冲隧道中的壳幔相互作用是克拉通岩石圈减薄的重要诱因.
The single-mineral and whole-rock water contents of the mantle bales in the northern China and southern China terranes in East China vary greatly, which are generally lower than those of other craton and non-cratonic lithospheric mantle enclaves in the world. However, The single mineral and whole rock water content of the pluton from the lithospheric mantle is generally higher than that from other lithospheric mantle inclusions in eastern China, indicating that the initial water content of the newborn lithospheric mantle in the eastern China is not low.The content of single minerals There is no significant correlation between water content and Mg ~ #, and the pyroxene lacks water diffusion zone, so the low water content of mantle inclusions and the loss of inclusions with the water diffusion loss of basaltic magma rise.Central lithosphere mantle bottom The mantle roasting by hot asthenosphere may result in the loss of water diffusion, but melt extraction may also be one of the causes of low water content.The Mesozoic and Cenozoic basalts from eastern China The body water content is higher than normal mid-oceanic basalts.The Mesozoic basalts have similar initial water content to island arc basalts, but the initial melt water content of Cenozoic basalts (Similar to island arc basalts in some areas) .These results indicate that the mantle source area of the continental basalt is relatively water-rich, indicating that the mantle source area was once rich in water formed by the deep subduction of the crust Fluid / water-bearing melts, causing a rise in water content.The hydrogen isotope composition of the Cenozoic mantle-derived megacrysts, inclusions and basalt porphyrocells in eastern China also varies greatly, reflecting the changes in the isotopic composition of the Cenozoic lithospheric mantle hydrogen isotopes The composition of the Cenozoic lithospheric mantle is higher than that of the depleted mantle and the isotope composition of hydrogen isotopes deviating from the depleted mantle value, indicating that it is interpreted by the melt generated by partial melting of the subducted Pacific plate. The account of the melting of the water-rich fluid and the aqueous melt on the bottom of the continental lithospheric mantle causes its water content to increase, causing a decrease in the rock viscosity at the base, which in turn leads to a decrease in rock strength and makes it susceptible to structural erosion and delamination. The crust-mantle interaction in the oceanic subduction tunnel is an important incentive for the lithospheric thinning of the craton.