Late Cretaceous Foraminiferal Faunas from the Saiqu “mélange” in Southern Tibet

As one of the mélanges in the southern side of the Yarlung-Zangbo suture zone, the Saiqu mélange in southern Tibet is important for understanding the evolution of the Neo-Tethys ocean. The age of the Saiqu mélange, however, has been debated due to the lack of reliable fossil evidence in matrix strata. Based on lithological similarities with platform strata in southern Tibet and limited fossils from exotic blocks, previous studies variously ascribed the Saiqu mélange to be Triassic in general, Late Triassic, or Late Cretaceous. Here we reported planktonic foraminiferal faunas from the matrix strata of the Saiqu mélange. The new fossils yield a Late Cretaceous age, which is so far the best age constraint for the mélange. Regional stratigraphic correlation indicates that the Cretaceous Oceanic Red Beds (CORBs) in Saiqu may be time equivalent to the CORBs of the Zongzhuo Formation in neighboring regions. Thus the Saiqu mélange should be correlated to the Upper Cretaceous Zongzhuo Formation rather than the Triassic Xiukang Group, as previously suggested.     

Unification and Harmonization in True Color Image City Map

True color image city map is a sort of new-style map which combines the high resolution image and map symbols and shows both advantages in visualization. At the same time, the map unification and harmonization should be taken into account dur-ing the design process, since some visual conflicts appear when map symbols overlaid on the true color image. The objective of this research is to explore the rules in the process of true color image city map design based on chromatic and aesthetic knowledge. At the end, taking the Image Atlas of Guangzhou as an example, image color adjustment, road network presentation, and symbol de-signing issues will be discussed in the application.     

长时间序列Radarsat图像的神经网络模拟及土地覆盖变化的快速检测

土地覆盖的短期时空变化模式研究,对土地覆盖的快速、动态监测具有重要意义,也是遥感研究的新热点。本文利用2000—2001年的时间序列Radarsat图像,采用功率谱分析方法,对土地覆盖的短期时—空变化的周期特征进行了分析,由此建立了基于时间序列影像分析的神经网络预测模型,从植被主要生长季节的时间序列雷达卫星影像获取训练样本,对研究区域的典型土地覆盖的短期动态变化过程进行了学习。学习后的模型能够利用多个时间序列的Radarsat影像对下一时刻的影像进行模拟,并进一步检测变化。在模拟结果基础上,定义相对变化距离函数和检测门限,对模拟影像及实际影像中的变化区域进行了检测。检测精度范围在66.67%(农村居民点)—91.67%(水体)之间,平均检测精度为81.66%。由于时间序列信号的引入,神经网络模型能够较好地获取土地覆盖的短期动态变化信息。     

Distribution of lipids in modern soils from various regions with continuous climate (moisture-heat) change in China and their climate significance

Total 26 modern soil samples were collected from various regions under different climate conditions from tropical to arid temperate in China and systematically analyzed for their organic matters by GC/MS in order to evaluate climatic impacts on soil organic components. Abundant lipids molecules were recognized, including n-alkanes, n-alkenones, and long-chain branched alkanes. We find the predominance of main peaks of long-chain n-alkanes (nC29,nC31,nC33) and short-chain ones(nC16,nC17,nC18) records information of soil generation in warm-humid and cold-dry regions. The proportion of n-alkanes(nC16 nC17 nC18)to(nC29 nC31 nC33)varies in good agreement with moisture-heat conditions and thus probably can serve as a new index for climate change. The ratios of C21-/nC22 ,nC17/nC31 and (nC15 nC17 nC19)/(nC27 nC29 nC31)of n-alkanes, indicating respectively input ratios of lower bacterial alga, aquatic organisms, and higher plants and terraneous organisms, co-vary well in different climate regions from forest to grassland and desert, suggesting that they have also reflected the difference of climates between monsoon region and inland one. The C21-/C22 ratio of n-alkan-2-one records largely the discrepancy of temperature from north to south of China bordered by the Qinling Mountains, but less humidity. The C21-/C22 ratio of n-alkan-3-ones changes well with climatic factors, such as temperature and humidity. The biogenic source of series A-D long-chain branched alkanes may be derived from some kinds of special epiphyte that most likely live in weak oxic-anoxic and moisture-heat environments, suggesting their distribution record as well some information on climatic change. All these researches demonstrate that the distributions of lipids molecules in modern soils in China record well signals of climates from quite different climatic regions, and can serve as important climatic proxies to reveal climatic change over China.     

Analysis of the spectral response of flourishing-withering vegetation changes based on ground spectral measurements

A structural mode was used to characterize vegetation composition at the plant leaf level and a flourishing-withering ratio was developed. The spectral responses of vegetation with different flourishing-withering ratios were analyzed, the change rates of the chlorophyll and moisture content indices of vegetation with different flourishing-withering ratios were compared, and correlations between the chlorophyll and moisture content indices were analyzed. The results reveal that leaves with an intermediate flourishing-withering ratio can increase the absorption signatures of vegetation and that band ranges of 570–700 nm and 1300–1540 nm can play a role in indicating changes in the flourishing-withering ratios of vegetation; NPQI, NPCI, R₆₉₅/R₄₂₀, R₆₉₅/R₇₆₀, R₇₅₀/R₇₀₀, the peak-value area of red selvedge, the red selvedge amplitude, the ratio between the red selvedge amplitude and the minimum amplitude, and the NDVI of vegetation change regularly with the change in flourishing-withering ratios, and these nine vegetation indices are highly related to the chlorophyll content. Vegetation indexes of NDWI and PRI are very sensitive to the flourishing-withering change in vegetation and are closely related to the moisture content, and the correlation coefficient is higher than 0.9. The derivative of the spectra is more effective in describing changes in the structural mode of vegetation with different flourishing-withering ratios, especially at band ranges of 552–628 nm and 630–686 nm, and it is more sensitive to the mixed flourishing-withering ratios of leaves rather than to the vegetation indices. The red selvedge position in the spectrum is highly related to the chlorophyll content and is not sensitive to changes in the structural mode of mixed flourishing-withering leaves. The red selvedge parameters are sensitive to changes in the flourishing-withering ratio at the peak-value area of the red selvedge amplitude and the ratio between the red selvedge amplitude and the minimum amplitude. The effect of a sand background on the spectrum of withering leaves is higher than that of flourishing leaves; the effect of a sand background increases with increasing proportions of withering leaves, the superposition effect of the sand background on mixed flourishing-withering leaves is about 7% at visible light bands of 400–700 nm and 1300–1540 nm, and is over 10% at the near infrared band range of 700–1300 nm.     

Features and trends of the environmental change in the arid areas in Central Asia

RS-monitoring index systems of ecological environment changes at a large scale, based on empirical data and trends in environmental change in Central Asia, are developed using NOAA and MODIS data. Moreover, with the help of mathematical statistics and GIS spatial analysis, the degrees, hazards and distribution extent of various possible ecological problems are discussed, environmental changes in Central Asia in 1990 and 2005 are separately evaluated, and dynamic changes in the environment in Central Asia over a 15-year period are analyzed. The results reveal that during the 15-year period from 1990 to 2005, areas of degenerated vegetation in Kazakhstan, Uzbekistan, Turkmenistan, Kirghizstan and Tadzhikistan were enlarged by 0.069×10⁵ km², 0.081×10⁵ km², 0.296×10⁵ km², 0.022×10⁵ km² and 0.112×10⁵ km², respectively. The ecological environment in Central Asia was in the state of significant degeneration and even deterioration. This study proves that NOAA and MODIS data can be used to successfully monitor the environment and provide useful results.     

Regional Tectonic Deformation Background and Medium- and Short-Term Precursors to the Minle-Shandan Earthquakes

INTRODUCTIONOnOctober 2 5,2 0 0 3,twoearthquakesofMS6 .1andMS5.8hitMinleandShandanofGansuProvinceinsuccession (at 38.4°N ,1 0 1 .2°E ;and 38.4°N ,1 0 1 .1°E) .Theseismicfaultisthrustandleft lateraltheMinle DamayingfaultwhichstrikesEWandisaffiliatedtot…     

景泰5．9级地震前后的重力变化研究

通过对河西地区重力复测资料进行系统分析,从动态的观点研究了2000年6月6日景泰5．9级地震孕育过程中的重力场演化特征。重力动态图像较清晰地反映了本区重力场的准均匀态→地震孕育的非均匀态→发震的演化过程,还分析研究了特征重力变化与强震活动原关系。