塔里木盆地西南缘中生代沉积古环境恢复   总被引：1，自引：0，他引：1  

廖林  程晓敢  王步清  陈汉林  罗俊成  师骏 《地质学报》2010,84(8):1195-1207

对塔里木盆地西南缘中生代沉积相和沉积环境的研究,不仅可以了解晚三叠世—晚白垩世塔里木板块南缘活动大陆边缘的历次碰撞事件,也为研究新生代中亚地区强烈的陆内变形活动提供了重要信息。本文利用野外地质调查结果和地球物理资料,在沉积相和地震相分析基础上,重建中生代沉积体系和沉积环境。结果表明:塔里木盆地西南缘中生界的原始分布受晚三叠世弧后前陆冲带冲断作用和造山后伸展作用形成的古地形控制。早侏罗世发育了一系列独立分割的小断陷,以巨厚的冲积扇、辫状河三角洲沉积为特征,其受控于NWW—SEE走向的正断层,而非NW—SE走向的古塔拉斯-费尔干纳右旋走滑断裂;早侏罗世晚期—中侏罗世广泛发育滨浅湖和河流-沼泽相沉积,可能存在一个连通了塔里木盆地南缘、吐拉以及柴达木盆地西缘的统一沉积坳陷;至晚侏罗世,冲积环境再次出现,发育的粗粒碎屑岩为早白垩世湖盆扩张前的产物;早白垩世,丰富的陆源碎屑在古昆仑山前形成多个相互叠置的冲积扇—扇三角洲—扇三角洲平原沉积体;晚白垩世,随着海水自西向东侵入,塔里木盆地西南缘陆相碎屑沉积向东逐渐退却,海相沉积占有优势。  相似文献   

Reconstruction of pH in the Surface Seawater over the North Pacific Basin for All Seasons Using Temperature and Chlorophyll-<Emphasis Type="Italic">a</Emphasis>     

Yoshiyuki?NakanoEmail author  Yutaka?W.?Watanabe 《Journal of Oceanography》2005,61(4):673-680

We found a simple function of pH that relates to sea surface temperature (SST, K) and chlorophyll-a (Chl, µg l⁻¹) using measured surface seawater pH, SST and Chl data sets over the North Pacific: pH (total hydrogen scale at 2°C) = 0.01325 SST − 0.0253 Chl + 4.150 (R² = 0.95, p < 0.0001, n = 483). Moreover, evaluating the seasonal variation of pH based on this algorithm, we compared the measured pH with the predicted pH at the observational time series stations in subpolar and subtropical regions. The average of ΔpH (measured - predicted, n = 52) was 0.006 ± 0.022 pH. Therefore, the combination of SST and Chl can allow us to determine the spatiotemporal distribution of pH over the North Pacific. Using the climatological data sets of SST and Chl with our pH algorithms, we have described the seasonal distributions of pH at 25°C (pH₍₂₅₎) and pH in situ temperature (pH_(T)) over the North Pacific surface water.  相似文献   

Large-scale P-velocity structures in the Euro-Mediterranean area     

M. Granet  J. Trampert 《Geophysical Journal International》1989,99(3):583-594

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On the affinity of Chuaria–Tawuia complex: A multidisciplinary study     

Mukund Sharma  Sanjay Mishra  Suryendu Dutta  Santanu Banerjee  Yogmaya Shukla   《Precambrian Research》2009,173(1-4):123

In this study, biometric and structural engineering tool have been used to examine a possible relationship within Chuaria–Tawuia complex and micro-FTIR (Fourier Transform Infrared Spectroscopy) analyses to understand the biological affinity of Chuaria circularis Walcott, collected from the Mesoproterozoic Suket Shales of the Vindhyan Supergroup and the Neoproterozoic Halkal Shales of the Bhima Group of peninsular India. Biometric analyses of well preserved carbonized specimens show wide variation in morphology and uni-modal distribution. We believe and demonstrate to a reasonable extent that C. circularis most likely was a part of Tawuia-like cylindrical body of algal origin. Specimens with notch/cleft and overlapping preservation, mostly recorded in the size range of 3–5 mm, are of special interest. Five different models proposed earlier on the life cycle of C. circularis are discussed. A new model, termed as ‘Hybrid model’ based on present multidisciplinary study assessing cylindrical and spherical shapes suggesting variable cell wall strength and algal affinity is proposed. This model discusses and demonstrates varied geometrical morphologies assumed by Chuaria and Tawuia, and also shows the inter-relationship of Chuaria–Tawuia complex.Structural engineering tool (thin walled pressure vessel theory) was applied to investigate the implications of possible geometrical shapes (sphere and cylinder), membrane (cell wall) stresses and ambient pressure environment on morphologically similar C. circularis and Tawuia. The results suggest that membrane stresses developed on the structures similar to Chuaria–Tawuia complex were directly proportional to radius and inversely proportional to the thickness in both cases. In case of hollow cylindrical structure, the membrane stresses in circumferential direction (hoop stress) are twice of the longitudinal direction indicating that rupture or fragmentation in the body of Tawuia would have occurred due to hoop stress. It appears that notches and discontinuities seen in some of the specimens of Chuaria may be related to rupture suggesting their possible location in 3D Chuaria.The micro-FTIR spectra of C. circularis are characterized by both aliphatic and aromatic absorption bands. The aliphaticity is indicated by prominent alkyl group bands between 2800–3000 and 1300–1500 cm⁻¹. The prominent absorption signals at 700–900 cm⁻¹ (peaking at 875 and 860 cm⁻¹) are due to aromatic CH out of plane deformation. A narrow, strong band is centred at 1540 cm⁻¹ which could be COOH band. The presence of strong aliphatic bands in FTIR spectra suggests that the biogeopolymer of C. circularis is of aliphatic nature. The wall chemistry indicates the presence of ‘algaenan’—a biopolymer of algae.  相似文献   

川藏公路地质环境与整治改建方案的思考   总被引：3，自引：0，他引：3  

崔建恒 《工程地质学报》2003,11(1):100-104

川藏公路由于地质环境复杂、建设标准低、后遗病害多,抗灾能力差,泥石流、滑坡、山崩、雪害、水毁等自然灾害频繁发生,公路阻车断道严重。国家投入巨资进行整治改建,并取得了明显的效果,但由于自然环境特殊、影响因素复杂,许多特大型、大型工程地质病害问题还没有可行、可靠的解决方案。本文通过分析川藏公路沿线的地质环境和灾害特点,总结历年整治改建和经验的教训,提出川藏公路建设的途径、可能达到的目标和应采用的原则。  相似文献   

A finite volume upwind scheme for the solution of the linear advection–diffusion equation with sharp gradients in multiple dimensions     

Fabiola Badrot-Nico  François Brissaud  Vincent Guinot 《Advances in water resources》2007

A finite volume upwind numerical scheme for the solution of the linear advection equation in multiple dimensions on Cartesian grids is presented. The small-stencil, Modified Discontinuous Profile Method (MDPM) uses a sub-cell piecewise constant reconstruction and additional information at the cell interfaces, rather than a spatial extension of the stencil as in usual methods. This paper presents the MDPM profile reconstruction method in one dimension and its generalization and algorithm to two- and three-dimensional problems. The method is extended to the advection–diffusion equation in multiple dimensions. The MDPM is tested against the MUSCL scheme on two- and three-dimensional test cases. It is shown to give high-quality results for sharp gradients problems, although some scattering appears. For smooth gradients, extreme values are best preserved with the MDPM than with the MUSCL scheme, while the MDPM does not maintain the smoothness of the original shape as well as the MUSCL scheme. However the MDPM is proved to be more efficient on coarse grids in terms of error and CPU time, while on fine grids the MUSCL scheme provides a better accuracy at a lower CPU.  相似文献   

中国历史文献档案中的古环境记录   总被引：14，自引：1，他引：14  

张德二 《地球科学进展》1998,13(3):273-277

我国的历史文献记录是古气候、古环境信息的重要来源，对古全球变化（PAGES）研究计划的目标时段——近2000年（人文记录和自然记录并存的时段）来说，尤其具有重要的科学价值。介绍了我国古文献中的古气候、古环境记录的概况和各项记录如水、旱、雨、雪等的数量统计，综述了这些记录被用于重建定量的气候序列、绘制历史气候复原图、编制古环境事件年表、获取高分辨率的古气候信息诸方面的主要进展。  相似文献   

Reconstruction of the rainfall in rainy season based on historical drought/ flood grades     

Xiong Anyuan  Wu Yijin  Cai Shuming 《大气科学进展》1999,16(1):147-153

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中国三大地块的碰撞拼合与古欧亚大陆的重建   总被引：26，自引：4，他引：26  

马醒华  杨振宇 《地球物理学报》1993,36(4):476-488

根据最新取得的华北地块的古地磁数据,并与目前收集到的按一定判据经过筛选的华南地块、塔里木地块、蒙古褶皱带与中亚褶皱带、西伯利亚板块以及稳定欧亚大陆的数据对比分析,对中国三大地块--华北、华南、塔里木地块的碰撞、拼合及其与北邻的西伯利亚板块的构造关系,进行了初步的讨论,并尝试作了古欧亚大陆的重建.  相似文献   

聊城市四河头渡槽改建工程浅析     

袁捍卫  王怀国  崔绍峰  赵长征 《地下水》2005,27(4):308-309

山东省聊城市四河头渡槽始建于1970年,是位山同灌区二干渠徒骇河的交叉输水建筑物.现该工程已严重老化,多年带病工作,渡管漏水严重.这些因素对位山灌区引黄灌溉、徒骇河防汛行洪造成了严重威胁,也阻碍了城市建设湖河相连通航.2003年,国家计划与发展改革委员会、水利部将四河头渡槽改建工程列入全国大型灌区续建配套与节水改造投资计划,同意将四河头渡槽由移动渡管型式改建为倒虹吸型式.本文针对工程设计中的有关问题进行了研究,并提出了适合本工程的方案.  相似文献