塔里木盆地西北缘柯坪冲断带的构造变形特征     

马德明  陈江力  曾昌民  尚新璐  师骏  张现军  敬兵 《地质力学学报》2007,13(4):340-347

柯坪冲断带位于塔里木盆地的西北缘, 是南天山南缘冲断系统的一部分。根据野外实际考察和地震剖面解释, 总结了该冲断带的构造变形特征:发育于古生界、以寒武系膏盐层为主滑脱层、叠瓦状冲断、暴露式冲断前锋、断层传播褶皱、前展式冲断、形成于上新世-第四纪。根据平衡剖面的恢复, 柯坪冲断带的构造缩短量最小为29.1%～40.7%。   相似文献   

Enzyme activities in the Delaware Estuary affected by elevated suspended sediment load     

K. Ziervogel  C. Arnosti 《Estuarine, Coastal and Shelf Science》2009

Extracellular enzyme activities were compared among surface water, bottom water, and sediments of the Delaware Estuary using six fluorescently labeled, structurally distinct polysaccharides to determine the effects of suspended sediment transport on water column hydrolytic activities. Potential hydrolysis rates in surface waters were also measured for the nearby shelf. Samples were taken in December 2006, 6 months after a major flood event in the Delaware Basin that was followed by high freshwater run-off throughout the fall of 2006. All substrates were hydrolyzed in sediments and in the water column, including two (pullulan and fucoidan) that previously were not hydrolyzed in surface waters of the Delaware estuary. At the time of sampling, total particulate matter (TPM) in surface waters at the lower bay, bay mouth, and shelf ranged between 31 mg l⁻¹ and 48 mg l⁻¹ and were 2 to 20 times higher than previously reported. The presence of easily resuspended sediments at the lower bay and bay mouth indicated enhanced suspended sediment transport in the estuary prior to our sampling. Bottom water hydrolysis rates at the two sites affected by sediment resuspension were generally higher than those in surface waters from the same site. Most notably, fucoidan and pullulan hydrolysis rates in bay mouth bottom waters were 22.6 and 6.2 nM monomer h⁻¹, respectively, and thus three and five times higher than surface water rates. Our data suggest that enhanced mixing processes between the sediment and the overlying water broadened the spectrum of water column hydrolases activity, improving the efficiency of enzymatic degradation of high molecular weight organic matter in the water with consequences for organic matter cycling in the Delaware estuary.  相似文献   

南海——我国深海研究的突破口   总被引：3，自引：1，他引：2  

汪品先 《热带海洋学报》2009,28(3):1-4

近两年来,海内外和海峡两岸的中国科学家围绕深海研究进行反复研讨,一致认为南海是我国深海研究的首选,并初步形成了“南海深部计划”的研究方案,提出以“构建边缘海的生命史”为主题,从洋壳深海盆的演化、深海沉积、生物地球化学过程三方面开展研究的建议方案。他们建议：利用现代技术重新测定南海磁异常条带,争取钻探大洋壳,系统研究火山链;观测现代深部海流和海底沉积过程,从深海沉积中提取边缘海盆演化的信息;认识海底溢出流体与井下流体的分布与影响,揭示微型生物在深海碳循环中的作用。争取在科学和技术全国性合作的基础上,在南海实现我国深海研究的突破。  相似文献   

Seasonal changes of dissolved and particulate organic carbon in Donghu Lake, China   总被引：4，自引：0，他引：4  

Liu Xue-jun  Xu Xiao-qing  Xie Ping  Noriko Takamura 《中国海洋湖沼学报》2000,18(4):372-377

Concentrations of dissolved and particulate organic carbon (DOC and POC) were documented in 1996–1997 at 4 different trophic state stations in Donghu Lake, a typical shallow eutrophic lake along the Changjiang River's middle reaches. The mean concentrations of DOC were 15.11±3.26, 15.19±4.24, 14.27±3.43, and 13.31±3.30 mg/L in Station I, II, III, and IV, respectively. The DOC concentrations of the studied area were very similar to that in other lakes along the Changjiang River's middle reaches. The POC mean of the whole lake was 5.01 mg/L due to the large amount of organic detritus of both allochthonous and autochthonous origin. Significant linear relationship was found between POC and chlorophyll a at all 4 stations, which presumably reflect that phytoplankton, its exudates and its metabolic products were the main contributors to the POC pool in the water column. The slope of such linear relationship at Station IV was significantly steeper than that at Station I, II and III. In addition, the DOC/POC ratios (mean value: 4.40) indicated that the organic detritus was the most important component of the particulate organic matter; in other works, next to organic detritus, phytoplankton dominated the particulate organic matter in Donghu Lake. Project 39770146, 39430101 supported by NSFC and the State Key Laboratory of Freshwater Ecology and Biotechnology, affiliated to the Institute of Hydrobiology, Chinese Academy of Sciences.  相似文献   

平衡剖面技术在新疆焉耆盆地断裂和圈闭研究中的应用     

陶建元  欧少佳  张永华  钟俊义 《河南国土资源》1999,(4)

简要地介绍了平衡剖面技术的基本原理及在新疆焉耆盆地断裂演化和圈闭研究中的应用。借助该项技术确定了盆地内断裂发育的时空关系及性质,指出盆地内中、新生代的断裂发育过程中有早缓晚骤、早正晚逆（ 反转） 的特征,认为盆地内的构造圈闭主要有两个形成时期,即侏罗纪末的燕山运动时期和第三纪末的喜山运动时期,并且前者形成的圈闭有效性要好于后者。  相似文献   

发展地理学视角下中国区域均衡发展   总被引：11，自引：3，他引：8  

邓祥征  梁立  吴锋  王振波  何书金 《地理学报》2021,76(2):261-276

区域差异大、发展不平衡是中国的基本国情,研究区域均衡发展问题是发展地理学领域的重大课题.本文首先回顾了中国的区域均衡发展历程,总结了各时期区域均衡发展的特征,研究指出,中国区域间发展呈现出均衡发展与非均衡发展演替的状态,每次演进使得社会的发展质量迈进新的台阶,逐渐走向高质量发展与区域均衡发展的状态.其次,本文探讨了当前...  相似文献   

金属稳定同位素示踪俯冲带挥发分循环SCIEI北大核心CSCD          下载免费PDF全文

刘盛遨 《岩石学报》2022,38(5):1512-1522

俯冲带挥发分的循环不仅深刻影响着地球各圈层之间的相互作用,而且在成矿金属元素迁移-富集以及全球气候变化等重要地质和环境过程中扮演着重要的角色。近年来,金属稳定同位素示踪俯冲带挥发分循环受到了广泛关注,取得了众多进展,但大多针对单个挥发性元素开展某个特定金属同位素的示踪研究。本文根据不同金属元素的地球化学性质差异及其与多种挥发分之间的结合形式,系统归纳了金属稳定同位素在示踪俯冲带不同挥发分循环方面的特点。整体上讲,镁和锌同位素体系示踪俯冲带碳循环最为有效;锂、镁、钾、钡、钼等金属同位素体系在示踪俯冲带水(流体)循环方面则具有各自的特点;锌同位素在示踪俯冲带硫循环方面有巨大潜力;铬同位素示踪俯冲带氯循环有独特优势;铁、铬、铜等变价金属同位素体系对挥发分的氧化还原状态较为敏感,有望示踪俯冲带氧循环。这些同位素体系对理解俯冲带挥发分循环提供了全新的视角,有望成为未来地球系统科学的重要研究方向。  相似文献   

The impacts of the district-level administrative restructuring on urban polycentricity and balanced regional development北大核心CSCD     

Chen Y.  Yu P.  Wang L.  Chen Y. 《地理科学进展》2023,(11):2084-2098

Administrative division adjustment as an institutional support for spatial governance is an important measure to optimize resource allocation, and it has profound effects on promoting balanced regional development. Based on the panel data of 272 cities in China from 2013 to 2021, this study used the spatial difference-in-differences method to explore the impact of district-level administrative restructuring, a special type of administrative division adjustment, on balanced regional development, and further analyzed the mediation mechanism of urban morphological polycentricity. The results show that district-level administrative restructuring is not only beneficial to promoting balanced regional development in local regions, but also has positive spatial spillover effects on neighboring regions. Mechanism analysis show that under the background of administrative division adjustment, urban form is an important driving factor for balanced regional development. Specifically, district-level administrative restructuring can reduce regional development inequality by improving the level of urban morphological polycentricity. Heterogeneity analysis show that the impact of district-level administrative restructuring on balanced regional development varies across regions. Compared to the western region, the positive effects of such restructuring on balanced regional development are more significant in the eastern and central regions. The restructuring has significant promotional effects in large cities and medium-sized cities, while the effects in mega-cities, super-large cities, and small cities are not significant. In the future, we should prudently carry out administrative division adjustment and urban spatial transformation according to the development conditions of different cities, and promote the construction of urban polycentricity by district-level administrative restructuring according to local conditions, in order to promote balanced regional development. © 2023, Editorial office of PROGRESS IN GEOGRAPHY. All rights reserved.  相似文献