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251.
丘陵草坡土壤10Be分布特征及土壤生成速率 总被引:2,自引:0,他引:2
以位于广东省境内的中国科学院鹤山丘陵综合试验站草坡集水区土壤剖面为对象, 对土壤样品进行了大气成因10Be测定, 对基岩以及风化岩石样品进行了就地(in-situ)宇宙成因10Be测定. 基于土壤层大气成因10Be测定, 参考土壤层底界14C表观年龄, 估算出草坡地区3800年以来大约有34%的成土物质被侵蚀掉; 基于风化岩石间隙土大气成因10Be测定, 估算得到基岩之上90 cm厚的风化岩石层至少经历了1.36 Ma, 平均侵蚀速率约为1.26×10-4 cm/a. 表面风化岩石和基岩就地成因10Be浓度分别为10.7×104 atoms/g和 8.31×104 atoms/g, 据此估算得到: 土壤生成速率为8.8×10-4 cm/a; 表层风化岩石以及基岩宇宙射线暴露时间分别约为7.2×104和2.3×105a. 土壤生成速率大于侵蚀速率, 自然地貌状况稳定. 相似文献
252.
晚冰期以来青海湖沉积物多指标高分辨率的古气候演化 总被引:41,自引:3,他引:41
通过青海湖沉积物孢粉、碳酸盐、有机C, N和有机δ13C等多项指标的综合分析, 建立了青海湖晚冰期以来的高分辨率古气候演化序列. 结果表明, 18.2 cal. ka BP左右为末次冰期盛冰阶进入晚冰期的界限, 自15.4 cal. ka BP起气候开始向暖湿化发展, 7.4 cal. ka BP时达到了暖湿组合的鼎盛期, 4.5 cal. ka BP以后气候又逐步转入冷干. 晚冰期向全新世转换期间气候的冷暖干湿波动十分频繁, 其特征与北大西洋深海沉积、格陵兰冰芯、欧洲地区湖泊沉积以及中国黄土、古里雅冰芯等记录的古气候具有一定的可对比性. 青海湖地区晚冰期以来的古气候演化特征揭示了万年尺度上东亚季风的源驱动力同太阳辐射有关. 相似文献
253.
俄罗斯远东金属矿床形成条件的古地球动力学分析 总被引:1,自引:0,他引:1
根据本区地质构造的新资料,提出了区域板块构造模型。研究了从俯冲到加利福尼亚型转换和由后者又到俯冲的古地球动力学环境更替的意义。这种更替发生在对本区最重要的中—新生代历史时期,对区域成矿带整体乃至一些金属矿床的形成具有重要影响。论证了一些地体性质,尤其是俯冲-增生杂岩对矿床形成的重要意义。 相似文献
254.
GEOCHEMICAL CHARACTERISTICS OF GRANITES AND ITS STRUCTURAL GENETIC ENVIRONMENT IN THE NANDAN-HECHI METALLOGENETIC BELT, NORTHWEST GUANGXI 总被引:3,自引:0,他引:3
The Nandan-Hechi metallogenetic belt is the most important tin-polymetallic producing district in China, and is the location of the Dachang super-large tin deposit. Based on the detailed field investigation and isotopic data, the stages of magmatic activity in the Nandan-Hechi metallogenetic belt have been lined out in this paper. Through the study about the geochemical characteristics of different granites, and by using ω(Al2O3)-ω(SiO2), ω(TFeO)/[ω(TFeO) ω(MgO)]-ω(SiO2), AFM, ACF and Rb-Yb Ta, Rb-Y Nb,Ta-Yb, Nb-Y discrimination diagrams in combination with regional geological setting analysis, the authors carried out analyses about the structural environment for the formation of the granites, and discussed the structural environment and dynamic setting for the large scale mineralization in this area. Our study indicates that the majority of the granites in Nandan-Hechi metallogenetic belt belong to the POG type,while the later stage alaskite belongs to the RRG CEUG type. The granites were formed at the stage of structural transformation from postorogenic phase to intraplate setting. But the major structural environment is characterized by steady regional extension. The formation age for the granites coincides with the time for this transformation, and this translation environment is favored for large-scale metallogenesis. 相似文献
255.
As one of the most powerful tools to reduce the earthquake loss, the Earthquake Disaster Management [EDM] and Insurance [EI] have been highlighted and have had a great progress in many countries in recent years. Earthquake disaster management includes a series of contents, such as earthquake hazard and risk analysis, vulnerability analysis of building and infrastructure, earthquake aware training, and building the emergency response system. EI, which has been included in EDM after this practice has been done for many years, include these contents: insurance model, financing. This paper presents the development of china in EDM and EI. The main contents include: (1) the statue and trend of earthquake disaster management and insurance in china; (2) the progresses and new methods about the seismic risk zonation and vulnerability analysis, and the future developing trend, the application of GIS in earthquake disaster assessment is introduced; (3) the way and illustration in building the earthquake disaster e 相似文献
256.
LIU Shu-hua~ 《地球科学进展》2004,(Z1)
Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth‘s surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas... 相似文献
257.
DENG Tian-long~ 《地球科学进展》2004,(Z1)
In this paper, the sequential extraction procedure was used for the selection of fractions of lead in seven stages corresponding to lead exchangeable, lead bounded to carbonates, to manganese oxides, to organic matters, to amorphous iron, and lead associated to crystallized iron, and to residuals. The vertical distributions of lead species were carried out in the soils related to good agriculture progress (GAP) of Chinese medical materials of Ligusticum chuanxiong Hort in Dujiangyan city and Wenchuan County, Sichuan Province. Based on those researches, it is found that the plant of Glycine Max (L.) Merr. has the character of lead enrichment and sorption, which is not reported in the literature. Using Glycine Max (L.) Merr. alternate planting with Ligusticum chuanxiong Hort is a valuable recommended in order to produce a high quality Chinese medical materials in order to eliminate the barrier on the beyond the lead limit for the import and export of Ligusticum chuanxiong Hort. 相似文献
258.
B. C. Burchfiel 《沉积与特提斯地质》2004,24(4):89-95
新技术应用到地学领域所获取的新的科学数据有助于我们加深对地质过程的理解。同时,我们解释地质过程的研究方法也受到新技术资料的挑战,从而迫使我们用新的或不同的方法来研究这些地质过程。在此.我想对某些资料进行讨论,这些都是热门的研究领域。当然.作为一个野外地质工作者,我的理解有限。工作的确尚在进行之中,其潜在的结果将促使我们通过新方法着眼于浅部地壳结构及其与深部岩石圈过程的关系。 相似文献
259.
华南石炭纪岩关-大塘界线期牙形石地层分带 总被引:4,自引:0,他引:4
系统采集不同沉积相区和连续沉积的剖面,即浅海台地相广西柳江龙殿山剖面、台缘缓坡相云南施甸鱼硐剖面和台内盆地相广西柳州碰冲剖面,运用数理统计方法,研究了华南岩关一大塘界线过渡期牙形石的产出丰度和相分布,在恢复生物演化序列的基础上,对各剖面首先详细分带,再进一步综合成系统的5个牙形石带,即Gnathodus typicus—G.cuneiformis带、Gnathodus typicus—Protognathodus cordiformis带、Scaliognathus anchoralis—Gnathodus pseu-dosemiglaber带、Gnathodus praebilineatus带和Paragnathodus horrtopunctatus带。以生物系统发生为标准,严格限定各带的界线,并与北美、西欧同期地层进行精确对比,为建立杜内阶一维宪阶界线的全球层型(GSSP)提供可靠依据。 相似文献
260.
Igor E. Guryanov 《冰川冻土》2004,26(Z1):70-75
The paper discusses the distinctive features of grain size distribution of permafrost soils formed under conditions of continental lithogenesis and cryogenic weathering of rocks. As a functional consequence of surface erosion of mineral particles, the log-normal distribution of the density function of grain size is derived confirmed for any conditions and sediment types. 相似文献