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71.
Zhaodong Liu Ran Liu Yucheng Shang Fangren Shen Luyao Chen Xuyuan Hou Mingguang Yao Tian Cui Bingbing Liu Tomoo Katsura 《地学前缘(英文版)》2021,12(2):929-935
The temperature dependence of the Al2O3 solubility in bridgmanite has been determined in the system MgSiO3–Al2O3at temperatures of 2750–3000 K under a constant pressure of 27 GPa using a multi-anvil apparatus.Bridgmanite becomes more aluminous with increasing temperatures.A LiNbO3-type phase with a pyrope composition(Mg3Al2Si3O12)forms at 2850 K,which is regarded as to be transformed from bridgmanite upon decompression.This phase contains 30 mol%Al2O3at 3000 K.The MgSiO3 solubility in corundum also increases with temperatures,reaching 52 mol%at 3000 K.Molar volumes of the hypothetical Al2O3bridgmanite and MgSiO3corundum are constrained to be 25.950.05 and 26.24±0.06 cm3/mol,respectively,and interaction parameters of non-ideality for these two phases are 5.6±0.5 and 2.2±0.5 KJ/mol,respectively.The increases in Al2O3and MgSiO3contents,respectively,in bridgmanite and corundum are caused by a larger entropy of Al2O3bridgmanite plus MgSiO3corundum than that of MgSiO3bridgmanite plus Al2O3corundum with temperature,in addition to the configuration entropy.Our study may help explain dynamics of the top lower mantle and constrain pressure and temperature conditions of shocked meteorites. 相似文献
72.
中国四川2008年5月12日汶川地震的地质与地球物理背景 总被引:2,自引:0,他引:2
2008年5月12日, 在青藏高原东缘的龙门山, 发生了MW7.9地震. 这一地震是在青藏高原长期隆升和向东推挤的背景下形成的. 发生地震的区域有以下典型的地质特征: 不是陡峭山前的活动汇聚造山带(包括地形起伏大于4 km的情况), 而是缺少高活动强度的低角度逆冲断层;虽拥有年轻的高地形(距今15 Ma)和加厚的地壳, 但是却只有低的GPS缩短率(小于3 mm/a), 并且缺少同时代的前陆沉积. 在我们看来, 青藏高原东部下面的地壳加厚不是因为上部地壳的大范围缩短, 而是由于位于软弱层(低速层)中的深部地壳的韧性增厚. 横跨龙门山的晚新生代缩短量可能仅有10~20 km, 且伴有主要造成青藏高原和四川盆地差异抬升的褶皱和断裂. 5月12日的地震可能反映了青藏高原东部相对四川盆地的带有缓慢的汇聚和右旋走滑的长期抬升. 5月12日地震邻区内GPS确定的速率表明, 该地震的平均复发间隔大约为2 000~10 000年. 相似文献
73.
Jin-Chen Jiang Wei-Yang Wang Heng Xu Jiang-Wei Xu Chun-Feng Zhang Bo-Jun Wang De-Jiang Zhou Yong-Kun Zhang Jia-Rui Niu Ke-Jia Lee Bing Zhang Jin-Lin Han Di Li Wei-Wei Zhu Zi-Gao Dai Yi Feng Wei-Cong Jing Dong-Zi Li Rui Luo Chen-Chen Miao Chen-Hui Niu Chao-Wei Tsai Fa-Yin Wang Pei Wang Ren-Xin Xu Yuan-Pei Yang Zong-Lin Yang Ju-Mei Yao Mao Yuan 《天文和天体物理学研究(英文版)》2022,(12):84-101
As the third paper in the multiple-part series, we report the statistical properties of radio bursts detected from the repeating fast radio burst(FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode between the 25th and 28th of September 2021(UT). We focus on the polarization properties of536 bright bursts with S/N > 50. We found that the Faraday rotation measures(RMs) monotonically dropped from-579to-605 rad m-2 相似文献
74.
Glaciers in the upstream Manla Reservoir in the Nianchu River Basin are crucial for agriculture and hydropower in the "One River and Two Streams" area. Rising temperature has caused widespread retreat of glaciers on the Tibetan Plateau during the last few decades. In this study, glacier variations under climate change in the Nianchu River Basin are quantified and their influence are evaluated by analyzing 1980 aerial topographic maps, 1990 Landsat TM, 2000 Landsat ETM+, and 2005 CBERS remotely sensed images. It is found that from 1980 to 2005, the debris-free glacier area shrank by 7.3% (13.42 km2). Glacier shrinkage will have a positive effect on agriculture, hydropower and eco-environment in the near future. However, because the large number of small glaciers (<2 km2) will rapidly retreat and disappear in future years, melt water will decrease, ultimately resulting in a long term water shortage. Glacial lakes exhibited rapid expansion due to accelerating glacier retreat during 1980–2005, increasing the possibility of glacial lake outburst floods. 相似文献
75.
HalophilicVibriosinthewatersofXiamenHarborandDayaBay¥NiChunzhi;YeDezan;LinYanshun;ZhouZongcheng;YaoRuimeiandGuJingyu(ThirdIns... 相似文献
76.
DivisionofhydroclimaticareaoverChinaseas──Ⅰ.Principalcomponentanalysis¥ChenShangjiandYaoShiyu(ReceivedAugust1,1993;acceptedSe... 相似文献
77.
A DEEP SEISMIC REFLECTION PROFILE ACROSS ALTUN FAULT BELT 总被引:1,自引:0,他引:1
A DEEP SEISMIC REFLECTION PROFILE ACROSS ALTUN FAULT BELTtheNationalkeyfoundationresearchanddevelopmentplanfund(G19980 40 80 0 ) 相似文献
78.
生态空间控制是城市总体规划的重要内容,也是构建生态城市的必然要求;数字城市规划以空间信息技术应用与空间定量分析为突出特征,探讨生态敏感信息图谱构建的信息技术方法是数字城市总体规划需要开展研究的领域。以A市城市总体规划为例,探讨基于GIS空间分析技术的生态敏感信息图谱构建方法,包括基础数据处理、生态因子确定、评价方法选择、生态敏感性评价、信息图谱构建等几个方面。实践结果表明基于G1S的城市总体规划生态敏感信息图谱构建的技术方法是可行的,可以为数字城市总体规划方案的编制提供科学依据。 相似文献
79.
SHI Danian Lü Qingtian SHEN Yang XU Xiaoming ZHANG Yongqian XU Yao ZHAO Jinhu GU Yumin SHI Jianyu CHEN Changxin 《《地质学报》英文版》2023,97(4):1243-1251
A great amount of new S-wave data has been combined to image the mantle structure down to lower mantle depth near the southeastern margin of Eurasia and understand the tectonics in South China since the Mesozoic. Our results reveal a large-scale structure beneath the South China Sea, with a prominent, broad low-velocity feature of at least 1500-km wide in and below the mantle transition zone(MTZ) and a pronounced low-velocity feature of nearly 500-km wide in the lowermost mantle. Together these ... 相似文献
80.
Long-term changes of composition,sources and burial fluxes of TOC(total organic carbon) in sediments of the central Yellow Sea mud area and their possible affecting factors are discussed in this paper.Firstly,similarity analysis is employed to confirm that the carbon burial features resulted from two collected cores are typical in the central Yellow Sea mud area where YSWC(Yellow Sea Warm Current) is prevalent.On this basis,the burial flux of TOC here was considered to be 235.5–488.4 μmol/(cm2?a) since the first industrial revolution,accounting for about 70%–90% among burial fluxes of TC(total carbon) in the sediments.Compared TOC/TC ratio in the two cores with that in other marine sediments worldwide,we suggest that the growth of calcareous/non-calcareous organisms and dissolution of IC(inorganic carbon) are important factors controlling the TOC/TC ratio in sediment.Results of two-end mixed model based on δ13C data indicate that marine-derived organic carbon(OCa)is the main part among total burial organic carbon which accounts for a ratio over 85%.Due to the high TOC/TC ratio in the two cores,TC in the sediments also mainly exists as OCa,and the proportion of OCa is about 60%–80%.Away from the shore and relatively high primary production in upper waters are the main reasons that OCa is predominant among all burial OC in sediments of the central Yellow Sea mud area.Burial of OC in this mud area is probably mainly influenced by the human activities.Although the economic development during the late 19 th century caused by the first industrial revolution in China did not obviously increase the TOC burial fluxes in the sediments,the rise of industry and agriculture after the founding of new China has clearly increased the TOC burial flux since 1950 s.Otherwise,we also realize that among TC burial fluxes,TIC account for about 10%–30% in sediments of the central Yellow Sea mud area,so its burial could not be simply ignored here.Distinct from TOC burial,long-term TIC burial fluxes variations relate with climate changes more closely:the East Asian summer monsoon may influence the strength of the Huanghe River(Yellow River) flood,which could further affect the transport of terrestrial IC from land to the central Yellow Sea as well as the burial of these IC in the sediments. 相似文献