本文選題：風塵 + Sr-Nd同位素　； 參考：《昆明理工大學》2017年碩士論文

【摘要】：西藏高原作為世界最高的高原,其在冬夏季節(jié)分別作為陸地冷源和熱源的中心,大大加強了亞洲大陸東亞季風和南亞季風的強度,對大氣環(huán)流產生重要影響。同時,由于西藏高原高聳的海拔,冬季高空西風帶的運行受到阻礙而分為南北兩支,改變了氣流的運動軌跡。由于西藏高原地表存在荒漠化區(qū)域,其細粒碎屑物質很容易被風所攜帶,進入高空西風激流帶,在北半球高空進行遠距離傳輸,推測,理論上遠源風塵應該有來自西藏高原的貢獻,故我們選擇了這個研究項目。通過對西藏高原地表風塵物質,包括地表砂、黃土、風化物,加上河流砂樣的Sr-Nd同位素特征研究,主要依據(jù)εNd值將高原劃分了 10個同位素特征區(qū),分別為日土分區(qū)(εNd:-9.06)、獅泉河分區(qū)(εNd:-7.6)、象泉河分區(qū)(εNd:-13.3)、措尼分區(qū)(εNd:-9.4)、仲巴分區(qū)(εNd:-8.9)、申扎分區(qū)(εNd:-15.1)、日喀則分區(qū)(εNd:-7.6)、山南分區(qū)(εNd:-9.5)、拉薩分區(qū)(εNd:-5.7)和唐古拉山分區(qū)(εNd:-9.38)。這些區(qū)域在空間上并不連續(xù),因此劃為不同分區(qū)。整體而言,各分區(qū)稀土元素特征差異并不明顯,均反映出上地殼物質的稀土元素分布特征。各分區(qū)礦物組成雖然整體相似,但各分區(qū)有各自的特點。從西藏高原風塵物(包括地表砂和地表風化物質)的礦物特征分區(qū)看,與Sr-Nd同位素特征分區(qū)基本一致。礦物特征反映了西藏高原的風塵區(qū)域特征礦物以近源風化產物為主,一些區(qū)域廣泛存在過巖漿、熱液活動,區(qū)域氧化作用不強,化學風化作用較弱,局部存在蒸發(fā)作用。由西藏高原風塵物質的Sr-Nd同位素特征,結合礦物特征,在北太平洋深海沉積物和格陵蘭冰芯為代表的遠源風塵物質中,可能有部分西藏高原的物質貢獻,主要來自雅江河谷和唐古拉山區(qū)域,其它區(qū)域雖然同位素特征與遠源風塵物質相近,但由于區(qū)域風塵物質有限,被帶入高空西風帶的量也有限,因此貢獻有限。
[Abstract]:As the highest plateau in the world, Tibet Plateau is the center of land cold source and heat source in winter and summer seasons, which greatly strengthens the intensity of East Asian monsoon and South Asian monsoon on the Asian continent, and has an important influence on the atmospheric circulation. At the same time, because of the high altitude of the Tibetan Plateau, the westerly belt is divided into the north and the south, which changes the track of the airflow. Due to the existence of desertification areas on the surface of the Tibetan Plateau, its fine clastic material is easily carried by the wind and enters the upper-level westerly jet belt for long-range transport at high altitude in the Northern Hemisphere, presumably. In theory, the far source of wind and dust should have contributed from the Tibetan Plateau, so we chose this research project. Based on the study of Sr-Nd isotopic characteristics of surface wind dust materials in Tibet Plateau, including surface sand, loess, weathered materials and river sand samples, the plateau is divided into 10 isotopic characteristic areas according to 蔚 ND value. It is divided into three subzones, namely, Japan (蔚 Nd: -9.06), Shiquan River (蔚 Nd: -7.6), Xiangquan River (蔚 Nd: -13.3), Tawni (蔚 Nd-9.4), Zhongba (蔚 Ndv-8.9), Shenza (蔚 Ndv-15.1), Rikatse (蔚 Nd: -7.6), Shannan (蔚 Nd-9.5), 蔚 Nd-5.7 and 蔚 Nd-9.38. These areas are not spatially contiguous and are therefore divided into different partitions. On the whole, there is no obvious difference in the REE characteristics among the subzones, which reflects the REE distribution of the upper crust material. Although the mineral composition of each subzone is similar as a whole, each zone has its own characteristics. According to the partition of the mineral characteristics of the aeolian dust (including surface sand and surface weathering material) in the Tibetan Plateau, it is basically consistent with the Sr-Nd isotopic zoning. The mineral characteristics show that near source weathering products are the main minerals in the aeolian region of Tibet Plateau. Magma, hydrothermal activity, regional oxidation are not strong, chemical weathering is weak, and local evaporation exists in some regions. Based on the Sr-Nd isotopic characteristics of the aeolian dust materials in the Tibetan Plateau and the mineral characteristics, there may be some material contributions of the Tibetan Plateau in the far source wind dust materials represented by the deep-sea sediments in the North Pacific Ocean and the Greenland ice core. Although the isotopic characteristics of the other regions are similar to those of distant wind dust materials, the contribution of other regions is limited because of the limited amount of regional wind dust materials and the amount brought into the upper level westerly belt.
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P597

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