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91.
92.
河流相沉积中准层序与短期基准面旋回对比研究——以四川中部须家河组为例 总被引:3,自引:1,他引:3
通过详细分析曲流河沉积动力学特点,在四川中部须家河组建立了河流相沉积的准层序模式。曲流河沉积中可发育粒级向上变细准层序,也可以发育粒级向上变粗的准层序。辫状河准层序表现为粒级向上变细、河道水体向上变浅的准层序,而粒级向上变粗的准层序不发育。河流相准层序界面是河道砂体底部的冲刷侵蚀面,在粒级向上变粗的泛滥平原-决口扇或决口河道沉积中,准层序界面为暴露过泥岩与上部洪水期的暗色泥岩间的界面。将河流相准层序与短期基准面旋回进行精细的分析与对比认为,二者在层序地层学级次划分中时限相当,发育时间为0.01~0.05Ma;二者的界面是相同的,均为河道砂体底部的冲刷侵蚀面或者是暴露过泛滥平原泥岩、根土岩等。河流相中准层序与短期基准面旋回其实是相同时间内沉积的一套相同的沉积体,二者的不同只是分析的角度不同,其实质内容是一致的,即在曲流河短期基准面升降变化过程中,所保留下来的沉积物总是相对河水位是向上变浅的,由位于河水面以下的河道或边滩砂体向上变浅至河水面之上的天然堤、泛滥平原泥岩,此相序特征也正与准层序向上变浅的定义相同。 相似文献
93.
DENG Jun YANG Liqiang SUN Zhongshi WANG Jianping WANG QingfeiXIN Hongbo LI Xinjun Key Laboratory of Lithospheric Tectonics Exploration. China University of Geosciences Ministry of Education Beijing Institute of Geology Geophysics Chinese Academy of Sciences Beijing Faculty of Earth Sciences Jilin University Changchun Jilin 《《地质学报》英文版》2003,77(4):537-546
An analysis of trace elements and isotopic geochemistry suggest that the ore-forming materials of gold deposits in the Jiaodong granite-greenstone belt have multiple sources, especially the mantle source. Seismic wave, magnetic and gravity fields show that the crust-mantle structure and its coupling mechanism are the fundamental dynamic causes for the exchange and accumulation of materials and energy in the metallogenic system. Considering the evolution history of the structural setting, the tectono-metallogenic dynamics model of the area can be summarized as follows: (1) occurrence of the greenstone belt during the Archean-Proterozoic-the embryonic form of Au-source system; (2) stable tectonic setting in the Paleozoic-an intermittence in gold mineralization; (3) intensive activation and reformation of the greenstone belt in the Mesozoic-tectono-mineralization and tectono-diagensis; (4) posthumous structural activity in the Cenozoic-destruction of orebodies in the later stage. In the middle and late Ind 相似文献
94.
95.
加强埃达克岩研究,开创中国Cu、Au等找矿工作的新局面 总被引:36,自引:27,他引:36
埃达克岩与浅成低温热液Au-Ag及斑岩型Cu、Cu-Au矿床有密切的关系,环太平洋地区多数大型和世界级的斑岩铜矿均与埃达克岩有关。埃达克岩有利于成矿的关键因素与埃达克岩形成时角闪石转变为石榴石的脱水作用有关,而水能萃取出在地幔和基性岩中富集的金属元素。因此,埃达克岩集中分布的地区有利于铜、金等矿化的聚集。中国铜矿资源严重不足,解决这个紧迫问题的出路在寻找斑岩铜矿。全球铜矿主要分布在环太平洋地区,中国与环太平洋类似的地区不是中国东部,而是古亚洲洋造山带、东北吉黑东部和西藏冈底斯。从国家目标出发,建议实施铜、金等找矿工作的战略转移,把浅成低温热液和斑岩型Au、Cu、Ag等矿床找矿的重点放在古生代的古亚洲洋造山带、晚古生代-中生代的吉黑东部和中-新生代的冈底斯地区。古亚洲洋造山带首选阿尔泰西南缘-东准噶尔、东天山和内蒙古中部3个地区。埃达克岩可以作为找矿标志来使用,因此,在找矿思路上也应当有一个变化,即:先找埃达克岩,再找矿。 相似文献
96.
In a barotropic atmosphere, new Reynolds mean momentum equauons including turbulent viscosit,dispersion, and instability are used not only to derive the KdV-Burgers-Kuramoto equation but also to analyze the physical mechanism of the cascades of energy and enstrophy. It shows that it is the effects of dispersion and instability that result in the inverse cascade. Then based on the conservation laws of the energy and enstrophy, a cascade model is put forward and the processes of the cascades are described. 相似文献
97.
1. Introduction The observed facts show that the ENSO cycle has obvious phase-locking and oscillates irregularly (An and Wang, 2001; Kaplan et al., 1998). Based on Zibiak and Cane's (1987) model (hereafter, the Z-C model) and simple, coupled ocean-atmosph… 相似文献
98.
The absorption properties of the water vapor continuum and a number of weak bands for H2O, O2, CO2, CO, N2O, CH4, and O3 in the solar spectrum are incorporated into the Fu-Liou radiation parameterization program by using the correlated k-distribution method (CKD) for the sorting of absorption lines. The overlap absorption of the H2O lines and the H2O continuum (2500-14500 cm-1) are treated by taking the two gases as a single-mixture gas in transmittance calculations. Furthermore, in order to optimize the computation efforts, CO2 and CH4 in the spectral region 2850-5250 cm-1 are taken as a new single-mixture gas as well. For overlap involving other absorption lines in the Fu-Liou spectral bands, the authors adopt the multiplication rule for transmittance computations under which the absorption spectra for two gases are assumed to be uncorrelated. Compared to the line-by-line (LBL) computation, it is shown that the errors in fluxes introduced by these two approaches within the context of the CKD method are small and less than 0.48% for the H2O line and continuum in the 2500-14500 cm-1 solar spectral region, -1% for H2O (line) H2O (continuum) CO2 CH4 in the spectral region 2850-5250 cm-1, and -1.5% for H2O (line) H2O (continuum) O2 in the 7700-14500 cm-1 spectral region. Analysis also demonstrates that the multiplication rule over a spectral interval as wide as 6800 cm-1 can produce acceptable errors with a maximum percentage value of about 2% in reference to the LBL calculation. Addition of the preceding gases increases the absorption of solar radiation under all sky conditions. For clear sky, the increase in instantaneous solar absorption is about 9%-13% (~12 W m~2) among which the H2O continuum produces the largest increase, while the contributions from O2 and CO2 rank second and third, respectively. In cloudy sky, the addition of absorption amounts to about 6-9 W m-2. The new, improved program with the incorporation of the preceding gases produces a smaller solar absorption in clouds due to the reduced solar flux reaching the cloud top. 相似文献
99.
野外调查表明 ,西藏东南部的嘉黎断裂带从那曲到嘉黎由三段呈雁行排列 ,大致沿N60°W方向延伸 ,其东南段在波密附近向南转折 ,沿贡日嘎布曲向南南东过上察隅和下察隅后转为近南北向延入缅甸境内与什阶断裂相连。嘉黎断层全新世以来活动性不强 ,其第四纪以来的平均滑动速率约为 4mm/a。一个有趣的现象是 ,虽然总体上嘉黎断裂的新活动不强 ,但在局部与张性盆地相邻的地段表现出较强的活动性 ,在这些段上沿断裂发育晚第四纪地表破裂 ,横跨断层的冲沟和河流被错断 ,其晚第四纪以来的平均滑动速率达到 15mm/a。但是这种现象的存在只局限在盆地中 ,盆地以外则截然终止 ,不复存在。从上述事实看 ,嘉黎断裂的走滑活动似乎是伴随张性活动而产生的 ,在断层几何和活动特征上类似于横切大洋中脊的转换断 相似文献
100.
Ran Yongkang Fang Zhongjing Li Zhiyi Wang Jingbo and Li RuchengInstitute of Geology SSB Beijing China 《中国地震研究》1995,(1)
The northern boundary fault of Huailai-Zhuolu basin,Hebei Province,has a total length of 58 km and a general strike of NE.The geometry and feature of activity of the 5 segments of the fault greatly differ from each other.17 paleoseismic events have been recognized within 11 trenches excavated along the different segments of the fault.It is found that each segment is characterized by its distinct recurrence of paleoearthquakes.The recurrence intervals of strong earthquakes for each segment are 3500-7000 a for the shortest and 17,000-20,500 a for the longest.However,the recurrence interval of strong earthquakes for whole fault ranges between 750-8500 a.The boundary of the segments can be recognized as the junction,gap,bending,jog and salient of the fault.The length of the segment ranges between 7.5-14 km. 相似文献