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用时域分析组合模型建立了１００万年来６０°Ｎ６月份太阳辐射量时间序列、宝鸡黄土粒度时间序列、渭南夏季风指数时间序列的动态模型．研究结果表明，时域分析组合模型较好地提取了时间序列的信息，得到的几个显著周期Ｔ＝１３３，１００，８９，４１，２３，１９ｋａ，与地球轨道三要素的变化周期接近．用组合模型拟合实测数据，精度是高的；用其预测未来气候替代性指标时间序列的变化情况，发现未来气候有向干冷方向发展的趋势．时域分析组合模型为研究气候变化趋势提供了一种定量分析、预测的方法． 相似文献
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用时域分析组合模型建立了１００万年来６０°Ｎ６月份太阳辐射量时间序列、宝鸡黄土粒度时间序列、渭南夏季风指数时间序列的动态模型．研究结果表明，时域分析组合模型较好地提取了时间序列的信息，得到的几个显著周期Ｔ＝１３３，１００，８９，４１，２３，１９ｋａ，与地球轨道三要素的变化周期接近．用组合模型拟合实测数据，精度是高的；用其预测未来气候替代性指标时间序列的变化情况，发现未来气候有向干冷方向发展的趋势．时域分析组合模型为研究气候变化趋势提供了一种定量分析、预测的方法． 相似文献
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Petrogenesis of Adakitic Porphyries in an Extensional Tectonic Setting, Dexing, South China: Implications for the Genesis of Porphyry Copper Mineralization 总被引：71，自引：0，他引：71
WANG QIANG; XU JI-FENG; JIAN PING; BAO ZHI-WEI; ZHAO ZHEN-HUAN; LI CHAO-FENG; XIONG XIAO-LIN; MA JIN-LONG 《Journal of Petrology》2006,47(1):119-144
The Dexing adakitic porphyries (quartz diorite–granodioriteporphyries), associated with giant porphyry Cu deposits, arelocated in the interior of a continent (South China). They exhibitrelatively high MgO, Cr, Ni and Sr contents, high La/Yb andSr/Y ratios, but low Yb and Y contents, similar to adakitesproduced by slab melting associated with subduction. However,they are characterized by bulk Earth-like Nd–Sr isotopecompositions (Nd(t) = –1·14 to +1·80 and(87Sr/86Sr)i = 0·7044 – 0·7047), and highTh (12·6–27·2 ppm) contents and Th/Ce (0·19–0·94)ratios, which are different from those of Cenozoic slab-derivedadakites. Sensitive High-Resolution Ion Microprobe (SHRIMP)geochronology studies of zircons reveal that the Dexing adakiticporphyries have a crystallization age of 171 ± 3 Ma.This age is contemporaneous with Middle Jurassic extension withinthe Shi-Han rift zone, and within-plate magmatism elsewherein South China, indicating that the Dexing adakitic porphyrieswere probably formed in an extensional tectonic regime in theinterior of the continent rather than in an arc setting. Theirhigh Th contents and Th/Ce ratios, and Middle Jurassic age,argue against an origin from a Neoproterozoic (1000 Ma) stalledslab in the mantle. Taking into account available data for theregional metamorphic–magmatic rocks, and the present-daycrustal thickness (31 km) in the area, we suggest that the Dexingadakitic porphyries were most probably generated by partialmelting of delaminated lower crust, which was possibly triggeredby upwelling of the asthenospheric mantle due to the activityof the Shi-Hang rift zone. Moreover, the Dexing adakitic magmasmust have interacted with the surrounding mantle peridotiteduring their ascent, which elevated not only their MgO, Cr andNi contents, but also the oxygen fugacity (fO2) of the mantle.The high fO2 could have induced oxidation of metallic sulfidesin the mantle and mobilization of chalcophile elements, whichare required to produce associated Cu mineralization. Therefore,the Cu metallogenesis associated with the Dexing adakitic porphyriesis probably related to partial melting of delaminated lowercrust, similar to the metallogenesis accompanying slab melting. KEY WORDS: adakite; lower crust; delamination; porphyry copper deposit, South China 相似文献
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