According to buried depth, the Yellow Rver's Paleochannels can be divided into ground Paleochannels (buried depth 0-8m) and shallowburied Paleochannels theried depth 8-50m). Each of them can be roughly divided int...According to buried depth, the Yellow Rver's Paleochannels can be divided into ground Paleochannels (buried depth 0-8m) and shallowburied Paleochannels theried depth 8-50m). Each of them can be roughly divided into three major Paleochannel belts, stretching Parallel with each other from SW to NE. Sedimentary layers of the paleochannels were mainly made up by sand levee of meanders or natural leavee deposits, and the flooding sedments were found bebeen the layers. The paleochannels in North Shadong Plain were formed in three stags; stage I (buried depth 50-15m) in later period of late Pleistocene-early period of Holocene, stag II (20-8m) in earlymiddle period of HOlocene; and stag III (8-0m) in midddle-late period of Holocene.展开更多
High-pressure （HP） granulites widely occur as enclaves within tonalite-trondhjemite- granodiorite （TTG） gneisses of the Early Precambrian metamorphic basement in the Shandong Peninsula, southeast part of the North...High-pressure （HP） granulites widely occur as enclaves within tonalite-trondhjemite- granodiorite （TTG） gneisses of the Early Precambrian metamorphic basement in the Shandong Peninsula, southeast part of the North China Craton （NCC）. Based on cathodoluminescence （CL）, laser Raman spec- troscopy and in-situ U-Pb dating, we characterize the zircons from the HP granulites and group them into three main types： inherited （magmatic） zircon, HP metamorphic zircon and retrograde zircon. The inher- ited zircons with clear or weakly defined magmatic zoning contain inclusions of apatites, and 207pb/206pb ages of 2915--2890 Ma and 2763--2510 Ma, correlating with two magmatic events in the Archaean base- ment. The homogeneous HP metamorphic zircons contain index minerals of high-pressure metamor- phism including garnet, clinopyroxene, plagioclase, quartz, rutile and apatite, and yield 207pb/2066pb ages between 1900 and 1850 Ma, marking the timing of peak HP granulite facies metamorphism. The retrograde zircons contain inclusions of orthopyroxene, plagioclase, quartz, apatite and amphibole, and yield the youngest 207pb/206pb ages of 1840-1820 Ma among the three groups, which we correlate to the medium to low-pressure granulite facies retrograde metamorphism. The data presented in this study suggest subduction of Meso- and Neoarchean magmatic protoliths to lower crust depths where they were subjected to HP granulite facies metamorphism during Palaeoproterozoic （1900-1850 Ma）. Subse- quently, the HP granulites were exhumated to upper crust levels, and were ovel-printed by medium to low-pressure granulite and amphibolite facies retrograde event at ca. 1840--820 Ma.展开更多
Based on conventional observation data,wind profile radar data and data obtained by a microwave radiometer,the formation mechanisms of two hailstorm processes accompanied with weak precipitation in the north of Shando...Based on conventional observation data,wind profile radar data and data obtained by a microwave radiometer,the formation mechanisms of two hailstorm processes accompanied with weak precipitation in the north of Shandong Province on June 8 and July 1 in 2014 were analyzed. The results showed that energy accumulated before the occurrence of two hailstorm processes. That is,the height of 0 ℃ and-20 ℃ layer dropped rapidly in the period of hailing,and the height of 0 ℃ layer was around 2. 2 km. Echo clusters producing hail still belonged to meso-γ scale-meso-β scale,and the intensity of reflectivity factor exceeded 50 dBz; echo top was at 12-14 km,and vertically integrated liquid water content was over 30 kg/m^2; in the two processes,water accumulation zones were distributed at 0. 6-2. 0 km. In addition,the water vapor conditions of low-level environmental fields were poor,which resulted in small rainfall in the two processes. However,there were significant differences between the two processes in terms of influencing systems,motion path of hail,changes of ground meteorological elements and disasters. The influencing systems of the " 608" process were the cold vortex,transverse trough and cold front. Convective clouds moved from the northwest to the southeast,and ground temperature dropped,while dew point and ground pressure rose; wind direction changed suddenly with the movement of cold front,and there was no disaster. The influencing systems of the " 701" process were the upper trough,shear line and convergence line. Convective clouds moved from the south to the north. When convective clouds moved to the station,ground temperature dropped,and there was no obvious change in dew point; ground pressure declined sharply,and wind speed was small,but wind direction was changeable,so that the local direct economic loss was up to about 0. 2 billion yuan.展开更多
U-Pb zircon age, geochemical, and Sr-Nd-Pb isotopic data of mafic dykes from eastern Shandong Province, eastern China is reported herein. Laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） U-Pb ...U-Pb zircon age, geochemical, and Sr-Nd-Pb isotopic data of mafic dykes from eastern Shandong Province, eastern China is reported herein. Laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） U-Pb zircon analyses of two samples from the investigated mafic dykes yield consistent ages ranging from 121.9 Ma ± 0.47 Ma to 122.9 Ma ± 0.61 Ma. The mafic dykes are characterized by high （87Sr/86Sr） i ranging from 0.7087 to 0.7089, low εNd（t） values ranging from -16.9 to -17.8, 206Pb/204Pb = 17.15 to 17.17, 207Pb/204Pb = 15.45 to 15.47, and 208Pb/204Pb = 37.59 to 37.68. Results from the current study suggest that the mafic dykes are derived from partial melting of ancient lithospheric mantle that was variably hybridized by melts derived from foundered lower crustal eclogite. The mafic dykes may have been generated through subsequent insignificant crystal fractionation and very minor crustal contamination during magma ascent. Combined with previous studies, the current findings provide new evidence that the intense lithospheric thinning beneath the eastern Shandong Province of eastern China occurred at ~120 Ma, and that this condition was caused by the removal of the lower lithosphere （mantle and lower crust）.展开更多
文摘According to buried depth, the Yellow Rver's Paleochannels can be divided into ground Paleochannels (buried depth 0-8m) and shallowburied Paleochannels theried depth 8-50m). Each of them can be roughly divided into three major Paleochannel belts, stretching Parallel with each other from SW to NE. Sedimentary layers of the paleochannels were mainly made up by sand levee of meanders or natural leavee deposits, and the flooding sedments were found bebeen the layers. The paleochannels in North Shadong Plain were formed in three stags; stage I (buried depth 50-15m) in later period of late Pleistocene-early period of Holocene, stag II (20-8m) in earlymiddle period of HOlocene; and stag III (8-0m) in midddle-late period of Holocene.
基金supported by National Program on Key Basic Research Project(973 Program) (Grant No.2012CB416603)the National Natural Science Foundation of China(Grant Nos.40725007 and 40921001)the China Geological Survey Program(Grant Nos.1212011120150 and 1212010811065)
文摘High-pressure （HP） granulites widely occur as enclaves within tonalite-trondhjemite- granodiorite （TTG） gneisses of the Early Precambrian metamorphic basement in the Shandong Peninsula, southeast part of the North China Craton （NCC）. Based on cathodoluminescence （CL）, laser Raman spec- troscopy and in-situ U-Pb dating, we characterize the zircons from the HP granulites and group them into three main types： inherited （magmatic） zircon, HP metamorphic zircon and retrograde zircon. The inher- ited zircons with clear or weakly defined magmatic zoning contain inclusions of apatites, and 207pb/206pb ages of 2915--2890 Ma and 2763--2510 Ma, correlating with two magmatic events in the Archaean base- ment. The homogeneous HP metamorphic zircons contain index minerals of high-pressure metamor- phism including garnet, clinopyroxene, plagioclase, quartz, rutile and apatite, and yield 207pb/2066pb ages between 1900 and 1850 Ma, marking the timing of peak HP granulite facies metamorphism. The retrograde zircons contain inclusions of orthopyroxene, plagioclase, quartz, apatite and amphibole, and yield the youngest 207pb/206pb ages of 1840-1820 Ma among the three groups, which we correlate to the medium to low-pressure granulite facies retrograde metamorphism. The data presented in this study suggest subduction of Meso- and Neoarchean magmatic protoliths to lower crust depths where they were subjected to HP granulite facies metamorphism during Palaeoproterozoic （1900-1850 Ma）. Subse- quently, the HP granulites were exhumated to upper crust levels, and were ovel-printed by medium to low-pressure granulite and amphibolite facies retrograde event at ca. 1840--820 Ma.
基金Supported by Special Project for Forecasters of China Meteorological Administration(CMAYBY2015-042)
文摘Based on conventional observation data,wind profile radar data and data obtained by a microwave radiometer,the formation mechanisms of two hailstorm processes accompanied with weak precipitation in the north of Shandong Province on June 8 and July 1 in 2014 were analyzed. The results showed that energy accumulated before the occurrence of two hailstorm processes. That is,the height of 0 ℃ and-20 ℃ layer dropped rapidly in the period of hailing,and the height of 0 ℃ layer was around 2. 2 km. Echo clusters producing hail still belonged to meso-γ scale-meso-β scale,and the intensity of reflectivity factor exceeded 50 dBz; echo top was at 12-14 km,and vertically integrated liquid water content was over 30 kg/m^2; in the two processes,water accumulation zones were distributed at 0. 6-2. 0 km. In addition,the water vapor conditions of low-level environmental fields were poor,which resulted in small rainfall in the two processes. However,there were significant differences between the two processes in terms of influencing systems,motion path of hail,changes of ground meteorological elements and disasters. The influencing systems of the " 608" process were the cold vortex,transverse trough and cold front. Convective clouds moved from the northwest to the southeast,and ground temperature dropped,while dew point and ground pressure rose; wind direction changed suddenly with the movement of cold front,and there was no disaster. The influencing systems of the " 701" process were the upper trough,shear line and convergence line. Convective clouds moved from the south to the north. When convective clouds moved to the station,ground temperature dropped,and there was no obvious change in dew point; ground pressure declined sharply,and wind speed was small,but wind direction was changeable,so that the local direct economic loss was up to about 0. 2 billion yuan.
基金supported by Opening Project(201206)of the State Key Laboratory of Ore deposit Geochemistry,Chinese Academia of Sciencesthe National Nature Science Foundation of China(40773020,40972071,90714010,and 40634020)
文摘U-Pb zircon age, geochemical, and Sr-Nd-Pb isotopic data of mafic dykes from eastern Shandong Province, eastern China is reported herein. Laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） U-Pb zircon analyses of two samples from the investigated mafic dykes yield consistent ages ranging from 121.9 Ma ± 0.47 Ma to 122.9 Ma ± 0.61 Ma. The mafic dykes are characterized by high （87Sr/86Sr） i ranging from 0.7087 to 0.7089, low εNd（t） values ranging from -16.9 to -17.8, 206Pb/204Pb = 17.15 to 17.17, 207Pb/204Pb = 15.45 to 15.47, and 208Pb/204Pb = 37.59 to 37.68. Results from the current study suggest that the mafic dykes are derived from partial melting of ancient lithospheric mantle that was variably hybridized by melts derived from foundered lower crustal eclogite. The mafic dykes may have been generated through subsequent insignificant crystal fractionation and very minor crustal contamination during magma ascent. Combined with previous studies, the current findings provide new evidence that the intense lithospheric thinning beneath the eastern Shandong Province of eastern China occurred at ~120 Ma, and that this condition was caused by the removal of the lower lithosphere （mantle and lower crust）.
