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101.
在全球第四次产业转移的背景下,重庆迅速调整产业结构并取得突破,对外贸易的地理格局发生较大变化。本文搜集整理2008~2012年海关统计数据,采用地理信息系统软件(Ar-cGIS9.3)对重庆市对外贸易伙伴的空间分布格局、商品构成状况进行研究。研究表明:①2008年以来重庆进出口商品总量增长迅速,出口集中度逐年提高,而进口集中度逐年降低;②进口贸易伙伴集中分布于亚洲、欧洲和北美洲。贸易伙伴的分布重心向东南亚倾斜。进口商品集中于电子信息产品及机械设备;③出口贸易伙伴分布更加集中于北美洲与欧洲。出口商品以计算机与通信产品、机械设备为主。其中,计算机类电子信息产品已经超过传统汽车、摩托车等产品而位居首位。最后对重庆市对外贸易发展的趋势进行了展望。 相似文献
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从野外地表露头、井下岩心及典型剖面等基础资料出发,以富有机质页岩形成地质背景及其展布特征-页岩气成藏条件-有利区预测为主线,对重庆及周缘地区下古生界页岩气成藏条件进行分析,并采用综合信息叠合法对该区有利区进行预测。指出研究区下寒武统筇竹寺组和上奥陶统五峰组—下志留统龙马溪组两套富有机质页岩普遍发育,分布广,厚度大,埋藏适中,有机质类型好,有机质含量高,具有充足的储集空间和运移通道,并且等温吸附模拟和现场解析实验也表明,这两套页岩均具有较强的气体吸附、较好的含气性能;多口井钻遇黑色页岩段气显异常普遍,也为页岩气的存在提供证据。总之,该区与美国东部典型页岩气盆地有诸多地质可比性,具有形成页岩气藏的有利地质条件,是页岩气勘探研究值得关注的重要领域。 相似文献
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本文按发育岩性(可溶岩和非可溶岩), 发育规模(如桥高、拱高、跨度等), 桥下河谷的发育特征(常年性、季节性河流和干谷), 及发育成因(地表和地下), 提出天生桥的4大分类方案, 简要介绍和概括了近年来中国发现的典型岩溶天生桥的类型、分布格局、发育规模及景观组合和对比特征。然后以重庆黔江蒲花天生桥群为例, 初步分析和探讨了它的形成与演化, 系统分析和评价了它的资源系统, 通过与黔江区、武陵山区旅游资源及国内其它相似景区的对比, 概括其资源特色为“一河两桥三窗”, 并结合其市场条件, 将旅游开发主题定格为“桥下游暗河, 桥上走天桥, 上游漂激流”, 提出“一心二带一区三环”的功能布局, 探讨不同功能区的开发思路, 划分出主导、重要和配套3个层次的旅游产品项目, 构建连通桥上桥下的三大游览环线, 设计出“河-人-桥”三位一体的灯光效果。最后, 通过对中国典型岩溶天生桥旅游开发方式的概括、对比和分析, 提出岩溶天生桥纵向分层旅游开发方式, 并概括出3大分层方式: (1)“桥下观光, 桥上保护”式; (2)“桥下桥上观光”式; (3)“桥下保护, 桥上观光”式。 相似文献
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《International Geology Review》2012,54(15):1835-1864
The Yinshan deposit is a large epithermal-porphyry polymetallic deposit, and the timing and petrogenesis of ore-hosting porphyries have been hotly debated. We present new results from geochemical, whole-rock Sr–Nd and zircon U–Pb–Hf–O isotopic investigations. Zircon U–Pb data demonstrate that the quartz porphyry, dacitic porphyry, and quartz dioritic porphyry formed at ?172.2 ± 0.4 Ma, ?171.7 ± 0.5 Ma, and ?170.9 ± 0.3 Ma, respectively. Inherited zircon cores show significant age spreads from ?730 to ?1390 Ma. Geochemically, they are high-K calc-alkaline or shoshonitic rocks with arc-like trace element patterns. They have similar whole-rock Nd and zircon Hf isotopic compositions, yet an increasing trend in ?Nd(t) and ?Hf(t) values typifies the suite. Older (inherited) zircons of the three porphyries display Hf compositions comparable to those of the Jiangnan Orogen basement rocks. In situ zircon oxygen isotopic analyses reveal that they have similar oxygen isotopic compositions, which are close to those of mantle zircons. Moreover, a decreasing trend of δ18O values is present. We propose that the ore-related porphyries of the Yinshan deposit were emplaced contemporaneously and derived from partial melting of Neoproterozoic arc-derived mafic (or ultra-mafic) rocks. Modelling suggests that the quartz porphyries, dacitic porphyries, and quartz dioritic porphyries experienced ?25%, ?10%, and ?10% crustal contaminations by Shuangqiaoshan rocks. Our study provides important constraints on mantle–crust interaction in the genesis of polymetallic mineralization associated with Mesozoic magmatism in southeastern China. 相似文献
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Groundwater from karst subterranean streams is among the world’s most important sources of drinking water supplies, and the hydrochemical characteristics of karst water are impacted by both natural environment and people. Therefore, the study of hydrochemistry and its solutes’ sources is very important to ensure the normal function of life support systems. In this paper, thirty?five representative karst groundwater samples were collected from different aquifers (limestone and dolomite) and various land use types in Chongqing to trace the sources of solutes and relative hydrochemical processes. Hydrogeochemical types of karst groundwater in Chongqing were mainly of the Ca?HCO3 type or Ca (Mg)?HCO3 type. However, some hydrochemical types of karst groundwater were the K+Na+Ca?SO4 type (G25 site) or Ca?HCO3+SO4 type (G26 and G14 site), indicating that the hydrochemistry of these sites might be strongly influenced by anthropogenic activities or unique geological characteristics. The dissolved Sr concentrations of the studied groundwater ranged from 0.57 to 15.06 μmmol/L, and the 87Sr/86Sr varied from 0.70751 to 0.71627. The δ34S?SO42? fell into a range of ?6.8‰?21.5‰, with a mean value of 5.6‰. The variations of both 87Sr/86Sr and Sr values of the groundwater samples indicated that the Sr element was controlled by the weathering of limestone, dolomite and silicate rock. However, the figure of 87Sr/86Sr vs. Sr2+/[K++Na+] showed that the anthropogenic inputs also obviously contributed to the Sr contents. For tracing the detailed anthropogenic effects, we traced the sources of solutes collected karst groundwater samples in Chongqing according to the δ34S value of potential sulfate sources. The variations of both δ34S and 1/SO42? values of the groundwater samples indicated that the atmospheric acid deposition (AAD), dissolution of gypsum (GD), oxidation of sul?de mineral (OS) or anthropogenic inputs (SF: sewage or fertilizer) have contributed to solutes in karst groundwater. The influence of oxidation of sul?de mineral, atmospheric acid deposit and anthropogenic inputs to groundwater in Chongqing karst areas was much widespread. 相似文献
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Rodrigo de Freitas Lagoon, located in the Rio de Janeiro City, receives several types of polluted discharges. The knowledge of the sediment microfauna correlated with heavy metal and organic matter concentrations could supply important data about the conditions of the lagoon. The benthic foraminiferal assemblage presented larger diversity and more abundant samples in the lagoon entrance than in the inner area. The Ammonia tepida - Elphidiumexcavatum foraminiferal assemblage is characterized by dwarf, corroded and weak organisms. Agglutinated species were found only near the entrance. Low abundance values and sterility of five samples in the inner area (north/northeast) can be caused by high levels of heavy metals and organic matter. A. tepida shows negative correlation with increasing heavy metals values. PAHs and coprostanol high indexes, and the absence or low presence of microfauna in samples around the lagoon margin confirm illegal flows from gas stations and domestic sewage. 相似文献