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Delta asymmetry:Concepts,characteristics,and depositional models

Petroleum Science 2011年第3期8卷 278-289页

作者： Li Weiguo Janok P. Bhattacharya Wang Yingmin BP America Inc. Houston Texas77079 USA department of earth and atmospheric Sciences University of Houston Houston Texas 77204-5007 USA College of geosciences China University of Petroleum Beijing 102249 China

Delta asymmetry forms in wave-influenced settings where there is strong net longshore drift. Asymmetric deltas typically have two sediment sources and are characterized by morphology and facies asymmetry between the downdrift and the updrift sides. The downdrift, sourced primarily by the feeding river, are commonly influenced by mixed river and wave processes. Deposits on this side are muddy and consist of barrier, bar, lagoon, bay-fill, and bayhead delta facies with variable bioturbation intensity. At or near the river mouth, heterolithic river-dominated successions are more typical. Deposits are overall unburrowed （BI 0-2）, but with high burrowing spikes. Ichnogenera are characterized by horizontal, morphologically simple, and facies-crossing structures. The updrift, in contrast, is sourced by a second sediment source and typically consists of laterally continuous sandy beach and shoreface facies. Bioturbation is overall high （BI 3.6） and ichnogenera are healthy and robust, attributable to the Cruziana and Skolithos lchnofacies. Depending on shoreline trajectory and depositional history, facies characteristics of asymmetric deltas preserved in the ancient record, however, can be different from those predicted by the models. Degree of asymmetry is indicated by the asymmetry index （A）, defined as the ratio between the rate of longshore transport at the river mouth and river water discharge. The indexes in symmetric waveinfluenced deltas is less than 200, whereas those in asymmetric and deflected deltas are larger than 200. Overall the larger the index, the higher the degree of asymmetry. Delta asymmetry concepts and models challenge the traditional definition of deltas and the delta classification scheme, in a hydrocarbon exploration perspective, asymmetric deltas bear very different types of sands and, thus, reservoirs between the updrift and the downdrift. The updrift consists of wellsorted, mature, and laterally continuous homogeneous beach-shoreface reservoirs

关键词： Delta asymmetry asymmetry index longshore drift wave-influenced deltas ichnology

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Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring

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Science China earth Sciences 2006年第5期49卷 554-560页

作者： FAN Ke1,2,3.& WANG Huijun2 1. Nansen-Zhu International Research Center, Institute of atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2. department of atmospheric Science, Yunnan {3., Kunming 650091, China 3. Graduate {3. of the Chinese Academy of Sciences, Beijing 100049, China Nansen-Zhu International Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China department of atmospheric Science Yunnan University Kunming China Graduate university of the Chinese Academy of Sciences Beijing China

The interannual variability of Antarctic Oscillation (AAO) and its influence on East Asian climate during both boreal winter and spring are addressed. The results show that the positive AAO anomaly decreases the cold activity over East Asia during both boreal winter and spring. AAO-related barotropic meridional teleconnection from Antarctic to Arctic is found through analysis of mean me- ridional circulations. This meridional teleconnection is remarkable over Eurasia during boreal winter and over the Pacific Ocean during boreal spring. The results also show that zonal mean zonal wind at high latitudes in Southern Hemisphere has well positive correlation with that of Eurasia during boreal winter and has negative correlation with Pacific North American teleconnection (PNA) during boreal spring, which again display the meridional teleconnection. Thus, local meridional teleconnection is a possible linkage for interaction of circulations at mid-high latitudes between both hemispheres.

关键词： Antarctic Oscillation, Eurasian west wind, meridional teleconnection, mean meridional circulation.

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Effects of salinity on methane gas hydrate system

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Science China earth Sciences 2007年第11期50卷 1733-1745页

作者： YANG DingHui1 & XU WenYue2 1 department of Mathematical Sciences, Tsinghua university, Beijing 100084, China 2 School of earth & {3. Sciences, Georgia Institute of Technology, Atlanta, GA 3.3.2, usa department of Mathematical Sciences Tsinghua University Beijing China School of earth & atmospheric Sciences Georgia Institute of Technology Atlanta USA

Using an approximately analytical formation, we extend the steady state model of the pure methane hydrate system to include the salinity based on the dynamic model of the methane hydrate system. The top and bottom boundaries of the methane hydrate stability zone (MHSZ) and the actual methane hy-drate zone (MHZ), and the top of free gas occurrence are determined by using numerical methods and the new steady state model developed in this paper. Numerical results show that the MHZ thickness becomes thinner with increasing the salinity, and the stability is lowered and the base of the MHSZ is shifted toward the seafloor in the presence of salts. As a result, the thickness of actual hydrate occur-rence becomes thinner compared with that of the pure water case. On the other hand, since lower solubility reduces the amount of gas needed to form methane hydrate, the existence of salts in sea-water can actually promote methane gas hydrate formation in the hydrate stability zone. Numerical modeling also demonstrates that for the salt-water case the presence of methane within the field of methane hydrate stability is not sufficient to ensure the occurrence of gas hydrate, which can only form when the methane concentration dissolved in solution with salts exceeds the local methane solubility in salt water and if the methane flux exceeds a critical value corresponding to the rate of diffusive methane transport. In order to maintain gas hydrate or to form methane gas hydrate in marine sedi-ments, a persistent supplied methane probably from biogenic or thermogenic processes, is required to overcome losses due to diffusion and advection.

关键词： methane gas hydrate,solubility,stability of hydrate,salinity,phase equilibrium

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Glacial-Interglacial atmospheric CO_2 Change——The Glacial Burial Hypothesis

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Advances in atmospheric Sciences 2003年第5期20卷 677-693页

作者： Ning ZENG department of Meteorology and earth System Science Interdisciplinary Center, university of Maryland, {3. department of Meteorology and earth System Science Interdisciplinary Center University of Maryland USA

Organic carbon buried under the great ice sheets of the Northern Hemisphere is suggested to be the missing link in the atmospheric CO2 change over the glacial-interglacial cycles. At glaciation, the advancement of continental ice sheets buries vegetation and soil carbon accumulated during warmer periods. At deglaciation, this burial carbon is released back into the atmosphere. In a simulation over two glacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean carbon model forced by reconstructed climate change, it is found that there is a 547-Gt terrestrial carbon release from glacial maximum to interglacial, resulting in a 60-Gt (about 3.-ppmv) increase in the atmospheric CO2, with the remainder absorbed by the ocean in a scenario in which ocean acts as a passive buffer. This is in contrast to previous estimates of a land uptake at deglaciation. This carbon source originates from glacial burial, continental shelf, and other land areas in response to changes in ice cover, sea level, and climate. The input of light isotope enriched terrestrial carbon causes atmospheric δ13./SUP>C to drop by about 0.3. at deglaciation, followed by a rapid rise towards a high interglacial value in response to oceanic warming and regrowth on land. Together with other ocean based mechanisms such as change in ocean temperature, the glacial burial hypothesis may offer a full explanation of the observed 80–100-ppmv atmospheric CO2 change.

关键词： atmospheric CO2 ice age glacial burial hypothesis climate

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Study of ozone “weekend effect” in Shanghai

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Science China earth Sciences 2008年第9期51卷 1354-1360页

作者： TANG WenYuan1↑, ZHAO ChunSheng1, GENG FuHai1,2, PENG Li2, ZHOU GuangQiang2, GAO Wei2, XU JianMing2 & TIE XueXi2,3.1 department of atmospheric Science, School of Physics, Peking university, Beijing 100871, China 2 atmospheric Chemistry Laboratory of Shanghai Meteorological Bureau, Shanghai 20003., China 3.atmospheric Chemistry Division, NCAR, Boulder CO 803.1, usa department of atmospheric Science School of Physics Peking University Beijing China atmospheric Chemistry Laboratory of Shanghai Meteorological Bureau Shanghai China atmospheric Chemistry Division NCAR Boulder USA

Analysis of observed ozone data in 2006 from five monitoring sites (Xujiahui, Chongming, Baoshan, Pudong, Jinshan) in Shanghai reveals that ozone (O_3. concentrations in Xujiahui are higher at week-ends than those on weekdays, despite the fact that emissions of ozone precursor substances, such as oxides of nitrogen (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs) are lower at weekends than those on weekdays. The possible chemical cause of ozone "weekend effect" is that NO_2/NO ratio increases at weekends by 25.61% compared with those on weekdays. In addition, because of an average 12.13. reduction in NOx (NO + NO_2) in the early morning (05:00-09:00) at weekends compared with that on weekdays, the ozone inhibition period ends 0.5 h earlier at weekends resulting in the longer duration of ozone accumulation and the higher ozone production rate. The rate of ozone production is a function of VOCs and NOx in the atmosphere. VOCs/NOx ratio in Xujiahui is 4.55 at weekends, and 4.3. on weekdays, belonging to the "NOx-limited". The increasing VOCs/NOx ratio at weekends leads to ozone enhancement from 73.ppbv to 80 ppbv, which are consistent with ozone "weekend effect" in Xujiahui. Furthermore, combining with MICAPS cloud amount data, the fact that ozone "weekend effect" in Xujiahui weakens gradually along with the increasing of cloud amount indicates that ozone photochemical production leads to ozone "weekend effect" in Xujiahui of Shanghai.

关键词： Shanghai ozone photochemical pollution "weekend effect"

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Lithium isotopic composition of subduction-related leucogranites and associated rocks from the northern margin of the North China craton:Source tracking and tectonic implications

Lithium isotopic composition of subduction-related leucogran...

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中国矿物岩石地球化学学会第13.学术年会

作者： XIAO Yi-lin~1,XU Li-jun~1,GAO Yong-jun~2,LI Shu-guang~1, SUN He~1,GU Hai-ou~1 1.CAS Key Laboratory of Crust-Mantle Materials and Environments,School of earth and Space Sciences,university of Science and Technology of China,Hefei,23.026 2.department of earth and atmospheric Sciences,university of houston,houston,tx 772.4,usa

We report Li elemental and isotopic data for a suite of(leuco-) granitic and gneissic rocks(presumed protolith of the leucogranite) from the boundary between the North China craton(NCC) and the South China plate (SCP),which represent an important repository for understanding the Mesozoic thicken and thinning processes of the *** concentrations and isotopic compositions of leucogranites from the Bangbu area in the southern margin of the NCC show the following important characteristics:i) most samples(15 out of 19) have much lower Li concentrations but higherδ Li values compared to normal granite;ii) some samples have very low Li concentrations(around 1 ppm) but extremely heavy isotopic compositions(from 8.6 to 16.1),representing the heaviest Li isotopic compositions so far reported for granitic rocks;iii) lithium isotopic compositions of 11

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Characteristics of vertical ozone distribution in the lower troposphere in the Yangtze River Delta at Lin'an in the spring of 2001

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Science China earth Sciences 2005年第9期48卷 1519-1528页

作者： ZHENG Xiangdong1, CHAN Chuenyu2, CUI Hong2, QIN Yu3. CHAN Loyan2, ZHENG Yongguang3.& LEE Yusiang2 1. Chinese Academy of Meteorological Sciences, Beijing 100081, China 2. department of Civil and Structural Engineering, Hong Kong Polytechnic university, Hung Hom, Hong Kong, China 3. department of {3. Sciences, Peking university, Beijing 100871, China Chinese Academy of Meteorological Sciences Beijing China department of Civil and Structural Engineering Hong Kong Polytechnic University Hung Hom Hong Kong China department of atmospheric Sciences Peking University Beijing China

We analyzed vertical distributions of ozone (O3. in the lower troposphere (< 5 km above ground) at Lin’an (119.75°E, 3..3.°N), Zhejiang Province using electrochemical concen- tration cell (ECC) ozonesonde data obta... 详细信息

We analyzed vertical distributions of ozone (O3. in the lower troposphere (3..3.°N), Zhejiang Province using electrochemical concen- tration cell (ECC) ozonesonde data obtained from February 21 to April 13. 2001. The results showed that the vertical O3.distributions are controlled by metrological conditions and the char- acteristics of O3.profiles are related to those of wet bulb potential temperature and wind field. O3.below 2 km showed that the strongest variability and enhanced O3.mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the Yangtze River Delta (YRD) region. Vertical O3.profiles below 5 km can be grouped into 5 categories: (1) peak mixing ratio type, (2) well-mixed type, (3. layered-structure type, (4) episodic pollution type and (5) alti- tudinal increasing type. Vertical distributions of O3.affected by regional transport of polluted air masses were investigated. Transport of polluted air from high latitudes of northern China, ac- companying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3.at Lin’an. The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the YRD and cen- tral-eastern China also lead to regional accumulation of O3.and high O3.mixing ratio at Lin’an. Long-range transport of O3.and pollutants from the Pearl River Delta in South China and in-situ O3.formation also resulted in elevated O3.mixing ratios at around 1 km altitudes and layered O3.distribution in the lower troposphere.

关键词： vertical ozone distribution, lower troposphere, Yangtze River Delta, Lin'an.

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Two possible mechanisms for vortex self-organization

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Science China earth Sciences 2006年第2期49卷 202-211页

作者： LUO Zhexian2, ZHOU Xiuji1 & GAO Shouting3.1. Chinese Academy of Meteorological Sciences, Beijing 100081, China 2. department of Space Information Science, Nanjing university of Information Science and Technology, Nanjing 210044, China 3. Institute of atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China department of Environmental Science Nanjing University of Information Science and Technology Nanjing China Chinese Academy of Meteorological Sciences Beijing China Institute of atmospheric Physics Chinese Academy of Sciences Beijing China

The vortex self-organization is investigated in this paper by four groups of numerical experiments within the framework of quasi-geostrophic model, and based on the experimental results two types of possible mechanisms for vortex self-organization are suggested. The meso-scale to-pography may enable separated vortices to merge into a larger scale vortex; and the interaction of meso-γ and meso-β scale systems may make separated vortices to self organize a typhoon-like vor-tex circulation.

关键词： vortex, self-organization, meso-scale topography, interaction of different scales.

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Fractal and Multifractal Modeling of Hydrothermal Mineral Deposit Spectrum: Application to Gold Deposits in Abitibi Area, Ontario, Canada

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Journal of China university of Geosciences 2003年第3期14卷 199-206页

作者： Cheng Qiuming department of earth and atmospheric Science, department of Geography, York university, Toronto, Canada M3.1P3.Faculty of earth Resources, China university of Geosciences, Wuhan 43.074 department of earth and atmospheric Science Department of Geography York University Toronto Canada M3J1P3 Faculty of earth Resources China University of Geosciences Wuhan 430074

A number of fractal/multifractal methods are introduced for quantifying the mineral deposit spectrum which include a number-size model, grade-tonnage model, power spectrum model, multifractal model and an eigenvalue spectrum model. The first two models characterize mineral deposits spectra based on relationships among the measures of mineral deposits. These include the number of deposits, size of deposits, concentration and volume of mineral deposits. The last three methods that deal with the spatial-temporal spectra of mineral deposit studies are all expected to be popularized in near future. A case study of hydrothermal gold deposits from the Abitibi area, a world-class mineral district, is used to demonstrate the principle as well as the applications of methods proposed in this paper. It has been shown that fractal and multifractal models are generally applicable to modeling of mineral deposits and occurrences. Clusters of mineral deposits were identified by several methods including the power spectral analysis, singularity analysis and the eigenvalue analysis. These clusters contain most of the known mineral deposits in the Timmins and Kirkland Lake camps.

关键词： mineralization spectrum power-spectrum multifractal spectrum eigenvalue spectrum and GIS modeling

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Selection of Multifractal Scaling Breaks andSeparation of Geochemical andGeophysical Anomaly

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Journal of China university of Geosciences 2001年第1期12卷 54-59页

作者： Cheng Qiuming department of earth and atmospheric Science, department of Geography, York university, Toronto, Ontario, Canada, M3. 1P3 department of earth and atmospheric Science Department of Geography York University Toronto Ontario Canada M3J 1P3

Spatially superimposed multiple processes such as multiplicative cascade processes often generate multifractal measures possessing so-called self-similarity or self-affinity that can be described by power- law type of functions within certain scale ranges The multifractalities can be estimated by applying multifractal modeling to the measures reflecting the characteristics of the physical processes such as the element concentration values analyzed in rock and soil samples and caused by the underlying mineralization processes and the other geological processes. The local and regional geological processes may result in geochemical patterns with distinct multifractalities as wall as variable scaling ranges. Separation of these multifractal measures on the basis of both the distinct multifractalities and the scaling ranges will be significant for both theoretical studies of multifractal modeling and its applications. Multifractal scaling breaks have been observed from various multifractal patterns. This paper introduces a technique for separating multifractal measures on the basis of scaling breaks. It has been demonstrated that the method is effective for decomposing geochemical and geophysical anomalies required for mineral exploration. A dataset containing the element concentration values of potassium and phosphorus in soil samples was employed for demonstrating the application of the method for studying the fertilizer and yield optimization in agriculture

关键词： mineralization processes self-similarity geochemical anomaly separation multifractal scaling breaks.

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