The present study applies a space-time filter to identify three dominant types of tropical waves: Madden-Julian oscillations (MJOs), equatorial Rossby (ER) waves, and tropical depression (TD)-type disturbances. The im...The present study applies a space-time filter to identify three dominant types of tropical waves: Madden-Julian oscillations (MJOs), equatorial Rossby (ER) waves, and tropical depression (TD)-type disturbances. The impacts of these waves on tropical cyclones (TCs) were investigated based on 131 observations during the period 2000 07. The results suggest that 72% of TC geneses were related to the joint impacts of more than one type of wave. The composites for cases in different categories reveal that TCs related to the concurrence of the three types of waves have strong and large initial vortices at the time of TC genesis. In the absence of the MJO, ERand TD-related TC genesis, embedded in easterly flow, exhibits a relatively fast initiation process and gives rise to a relatively small scale vortex. In contrast, without the ER wave contribution, TCs associated with ER and TD waves did not require strong convection at the time of genesis because an initial vortex can rapidly develop in the MJO active phase through persistent energy transfer. The MJO-related TC geneses were scattered in geographic distribution, as opposed to the clustered and eastward shift observed for genesis cases without contributions from MJOs.展开更多
In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatia...In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatial extent of the influence of the Mongol-Okhostsk ocean tectonic regime and the collision between the Jiamusi Massif and Songliao Terrane. New zircon laser-ablation inductivity coupled plasma mass spectrometry （LA-ICP-MS） U-Pb data indicated that the monzogranites in the studied area were emplaced in the Early Jurassic （～ 180 Ma）. These rocks were characterized by unusally high SiO2 （≥67.49）, and Sr （461-759 ppm）, but strikingly low Y （4.63-8.06 ppm） and HREE （∑HREE = 3.83-6.49 ppm, Yb = 0.5-0.77 ppm） contents, with therefore high Sr/Y （67.2-119） and （La/Yb）N （29.7-41.5） ratios, showing the geochemical characteristics of C type adakitic granite. The data displayed negligible Eu anomalies （Eu/Eu^＊ =0.77-1.08）, LREE-enriched and pronounced negative Nb and Ta anomalies. The C-type adakites in the studied area were most likely derived from the partial melting of a thickened lower continental curst. The magma source is most likely dominated by amphibolites and garnet amphibolites. In combination with previously-reported data from igneous rocks from the Mesozoic in NE China, we conclude that the Xing＇ an block was influenced by the Mongol-Okhotsk subduction tectonic system, and experiences compressive settings from the amalgamation of the Jiamusi block in the east of the CAOB.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 40905024 and 40921160379)Special Scientific Research Project for Public Interest (Grant No. GYHY200806009)
文摘The present study applies a space-time filter to identify three dominant types of tropical waves: Madden-Julian oscillations (MJOs), equatorial Rossby (ER) waves, and tropical depression (TD)-type disturbances. The impacts of these waves on tropical cyclones (TCs) were investigated based on 131 observations during the period 2000 07. The results suggest that 72% of TC geneses were related to the joint impacts of more than one type of wave. The composites for cases in different categories reveal that TCs related to the concurrence of the three types of waves have strong and large initial vortices at the time of TC genesis. In the absence of the MJO, ERand TD-related TC genesis, embedded in easterly flow, exhibits a relatively fast initiation process and gives rise to a relatively small scale vortex. In contrast, without the ER wave contribution, TCs associated with ER and TD waves did not require strong convection at the time of genesis because an initial vortex can rapidly develop in the MJO active phase through persistent energy transfer. The MJO-related TC geneses were scattered in geographic distribution, as opposed to the clustered and eastward shift observed for genesis cases without contributions from MJOs.
基金supported by the regional geology and mineralization research program of Heilongjiang province (HLJKD201417)
文摘In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatial extent of the influence of the Mongol-Okhostsk ocean tectonic regime and the collision between the Jiamusi Massif and Songliao Terrane. New zircon laser-ablation inductivity coupled plasma mass spectrometry （LA-ICP-MS） U-Pb data indicated that the monzogranites in the studied area were emplaced in the Early Jurassic （～ 180 Ma）. These rocks were characterized by unusally high SiO2 （≥67.49）, and Sr （461-759 ppm）, but strikingly low Y （4.63-8.06 ppm） and HREE （∑HREE = 3.83-6.49 ppm, Yb = 0.5-0.77 ppm） contents, with therefore high Sr/Y （67.2-119） and （La/Yb）N （29.7-41.5） ratios, showing the geochemical characteristics of C type adakitic granite. The data displayed negligible Eu anomalies （Eu/Eu^＊ =0.77-1.08）, LREE-enriched and pronounced negative Nb and Ta anomalies. The C-type adakites in the studied area were most likely derived from the partial melting of a thickened lower continental curst. The magma source is most likely dominated by amphibolites and garnet amphibolites. In combination with previously-reported data from igneous rocks from the Mesozoic in NE China, we conclude that the Xing＇ an block was influenced by the Mongol-Okhotsk subduction tectonic system, and experiences compressive settings from the amalgamation of the Jiamusi block in the east of the CAOB.
