Cenozoic basin development and its indication of plateau growth in the Xunhua-Guide district

The Xunhua, Guide and Tongren Basins are linked with the Laji Mountain and the northern West Qinling thrust belts in the Xunhua-Guide district. Basin depositional stratigraphy consists of the Oligocene Xining Group, the uppermost Oligocene-Pliocene Guide Group and the Lower Pleistocene. They are divided into three basin phases by unconformities. Basin phase 1 is composed of the Xining Group, and Basin phase 2 of the Zharang, Xiadongshan, Herjia and Ganjia Conglomerate Formations in the Guide Group, and Basin phase 3 of the Gonghe Formation and the Lower Pleistocene. Three basin phases all develop lacustrine deposits at their lower parts, and alluvial-braided channel plain depositional systems at upper parts, which constitute a coarsening-upward and progradational sequence. Basin deposition, paleocurrent and provenance analyses represent that large lacustrine basin across the Laji Mountain was developed and sourced from the West Qinling thrust belt during the stage of the Xining Group (Basin phase 1), and point-dispersed alluvial fan-braided channel plain deposition systems were developed beside the thrust and uplifted Laji Mountain and sourced from it, as thrusting migrated northwards during the stage of the Guide Group (Basin phase 2). Evolution of basin-mountain system in the study area significantly indicates the growth process of the distal Tibetan Plateau. The result shows that the Tibetan Plateau expanded to the northern West-Qinling at Oligocene (29―21.4 Ma) by means of northward folded-and-thrust thickening and uplifting and frontal foreland basin filling, and across the study area to North Qilian and Liupan Mountain at the Miocene-Pliocene (20.8―2.6 Ma) by means of two-sided basement-involved-thrust thickening and uplifting and broken foreland basin filling, and the distant end of Tibetan Plateau behaved as regional erosion and intermontane basin aggradational filling during the Pliocene and early Pleistocene (2.6―1.7 Ma).     

A simple approach for determining particle size enlargement mechanisms in nickel reduction

This paper examines the active mechanisms responsible for the size enlargement of nickel metal particles during reduction by hydrogen gas. The population balance, related to particle size distribution, is discretized and solved with the method of moments to model the experimental data. This data was generated in a solution of intermittently constant supersaturation during the batch reduction in an 11,000 l of autoclave. PSD and mass distributions were determined by periodically removing suspension samples. In the proposed model, only the growth mechanism is taken into account and aggregation is ignored. Comparison of simulated and experimental PSD and mass distributions show that growth was not the only active mechanisms. Results from the plant indicate that there is an increase in particle size as the cycle progresses. The model generally underpredicts the growth shift in the PSDs' for the early and the larger densifications although it correctly predicts the growth shift in the middle densifications. Constant growth is therefore not the exclusive controlling mechanism. The findings have been confirmed by the trend of the zeroth moment as a function of time.     

Heterogeneous growth of cordierite in low P/T Tsukuba metamorphic rocks from central Japan

This paper examines the spatial statistics of matrix minerals and complex patterned cordierite porphyroblasts in the low‐pressure, high‐temperature (low P/T) Tsukuba metamorphic rocks from central Japan, using a density correlation function. The cordierite‐producing reaction is sillimanite + biotite + quartz = K‐feldspar + cordierite + water. The density correlation function shows that quartz is distributed randomly. However, the density correlation functions of biotite, plagioclase and K‐feldspar show that their spatial distributions are clearly affected by the formation of cordierite porphyroblasts. These observations suggest that cordierite growth occurred through a selective growth mechanism: quartz adjacent to cordierite has a tendency to prevent the growth of cordierite, whereas other matrix minerals adjacent to cordierite have a tendency to enhance the growth of cordierite. The density correlation functions of complex patterned cordierite porphyroblasts show power‐law behaviour. A selective growth mechanism alone cannot explain the origin of the power‐law behaviour. Comparison of the morphology and fractal dimension of cordierite with two‐dimensional sections from a three‐dimensional diffusion‐limited aggregation (DLA) suggests that the formation of cordierite porphyroblasts can be modelled as a DLA process. DLA is the simple statistical model for the universal fractal pattern developed in a macroscopic diffusion field. Diffusion‐controlled growth interacting with a random field is essential to the formation of a DLA‐like pattern. The selective growth mechanism will provide a random noise for the growth of cordierite due to random distribution of quartz. Therefore, a selective growth mechanism coupled with diffusion‐controlled growth is proposed to explain the power‐law behaviour of the density correlation function of complex patterned cordierite. The results in this paper suggest that not only the growth kinetics but also the spatial distribution of matrix minerals affect the progress of the metamorphic reaction and pattern formation of metamorphic rocks.     

Bioenergetic responses in green lipped mussels (Perna viridis) as indicators of pollution stress in Xiamen coastal waters, China

Samples of green lipped mussels (Perna viridis) were collected from three sites (Huoshao, I’Maluan and Tong’an) around Xiamen coastal waters, where levels of various trace organic pollutants have been studied. Samples were also collected at a “cleaner” reference site near Dongshan Island for comparison. Clearance rate, absorption efficiency and oxygen consumption of the mussels were measured under controlled laboratory condition; organic pollutants in their tissues were also analyzed. Scope for growth (SFG) was employed as a general biomarker to evaluate the stress of pollutants. Specimens from Tong’an site had the lowest SFG values (1.14 J/h/g); while specimens from the I’Maluan site and Huoshao site had SFG values of 5.01 and 6.72 J/h/g, respectively. Specimens from Dongshan (reference site) had a relatively high SFG value of 10.96 J/h/g. There was a significant negative correlation between the SFG of the different populations of green lipped mussels and the concentration of DDT in their tissues.     

成矿动力系统在混沌边缘分形生长——一种新的成矿理论与方法论(上)

“成矿动力系统在混沌边缘分形生长”理论是笔者将复杂性理论及非线性科学与矿床地质学相结合 ,对中国扬子古陆周缘六个矿集区的基本范式进行长期系统研究所取得的总结性成果。研究指出 ,成矿系统总体上是开放、远离平衡、时空延展的动力学系统。它们具有复杂性和自组织临界性的内禀基本属性 ,并且在混沌边缘分形生长。该理论以“地质作用与时 空结构是一切地质现象的本质与核心”的自然哲学理念作为根本立足点 ,建立起一种具有普适性的理论框架。然后进一步将其具体化为三大组成部分 ,即 ( 1)矿床的动力学属性 ,( 2 )矿床地质学场 ,( 3 )成矿系统的演化。体现了成矿作用 (其核心为成矿作用动力学 )、空间结构 (矿床地质学场 )和时间结构 (成矿系统的演化 )三位一体的整体耦合与交织 ,从而又使该理论具有包容性。在此基础上进而归纳出“成矿动力系统在混沌边缘分形生长”的 5项判定准则以及表征这些准则的 10项相应的动力学行为特征。最后笔者提出“矿质局部活化导致成矿的发生”的命题 ,拟定了“成矿的发生”的重要科学问题 ,以“元胞非线性网络”(CNN)作为复杂性的范式 ,定量揭示成矿的发生 ,并对矿床在混沌边缘作精确定位 ,对“成矿动力系统在混沌边缘”理论作进一步的延伸、深化与发展。该理论在矿?     

Influence of Climate Change on Winter Wheat Growth in North China During 1950-2000

1. IntroductionChinese agriculture has undergone tremendousstructural changes over the last decades. The averagestaple crop productivity has doubled in 25 yr while thepopulation increased by 25 % [China Statistical Year-book (CSY), 2003]. Winter wheat is one of China'smost important staple food crops, with a total farm-ing area of nearly 24 million hectares and a produc-tion exceeding 92 million ton in 2002 (CSY, 2003).Although China has been the world's largest wheatproducer since 1983 (…     

全过程沉降量预测的Logistic生长模型及适用性研究

地基的全过程沉降量与时间的关系呈S形曲线，可用Logistic生长模型来描述。目前应用的Logistic生长模型，较少考虑模型的适用范围和预测精度等问题。结合工程实例，比较了模型参数估计的三种方法，研究结果表明，采用非线性回归法估计模型参数，可取得较好的预测效果；根据混沌理论，研究了模型的适用范围和预测性能。Logistic生长模型的动态行为由参数α(瞬时沉降速率)决定，当参数α的取值范围在[0，2]之内，该模型预测的最终沉降量是稳定的。     

苏鲁超高压榴辉岩的石榴石生长成分环带及变质作用P—T轨迹

在南苏鲁东海地区，部分超高压榴辉岩中的变斑晶石榴石具有复杂的生长成分环带和多期矿物包体组合，它们记录了超高压变质岩的多阶段变质演化过程，即绿帘角闪岩相进变质、柯石英榴辉岩相峰期变质、石英榴辉岩相和角闪岩相退变质作用。运用相关的地质温、压计，使用代表最高变质温度的变斑晶石榴石慢部（具最低的Fe／Mg比值）和与其平衡的绿辉石包体成分，获得了〉900℃和4．1～4．5GPa的超高压变质务件。联合其他变质阶段的温、压条件，一个顺时针的变质作用P—T轨迹得以建立。它的特征是进变质与退变质路径近于平行，早期退变质作用为降温、降压过程．榴辉岩石榴石生长成分环带的保存说明超高压变质岩在峰期变质阶段有非常短暂的停留时间，并以很快的折返速率抬升到地壳浅部，超高压变质岩折返过程中的明显降温是石榴石生长环带得以保存的另一个有利条件，     

石河子冬小麦生长发育及产量的计算机模拟

用几种生物数学模型对冬小麦生育及产量进行了模拟 ,并运用 1996～ 1998年的实测资料对输出结果进行了对比和检验。