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1.
The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103°54.48'W, lat. 12°42.30'N, water depth 2655 m) on the East Pacific Rise near lat 13°N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%―1.85%) and Co (65×10?6―704×10?6) contents, and contain Co Cu Zn Ni> 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13°N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13°N are lower in ΣREE (5.44×10?6―17.01×10?6), with a distinct negative Ce anomaly (0.12 ― 0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13°N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples from the East Pacific Rise near 13°N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are lower, and their Fe, Co, and Cu contents are higher.  相似文献   
2.
米仓山隆起带西缘灯影组铅锌找矿潜力评价   总被引:1,自引:0,他引:1  
较系统全面地叙述了米仓山隆起带灯影组铅锌矿成矿地质条件,为在其西缘寻找与陕西马元铅锌矿相同矿床类型矿产的找矿潜力进行了评价。  相似文献   
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Analysis of the Pampa, Texas, multicell storms showed prestorm environmental conditions of a strong horizontal convergence of moisture, mixing ratio 12 g/kg at the 850 mb level in the Texas Panhandle areas and strong winds with shear veering with height. Rapid-scan satellite imagery showed that the clouds penetrated above the tropopause and cloud-top temperatures were at least 4 to 9° C colder than the temperature of the tropopause. This formation and collapsing of high-mass-density overshooting cloud tops above the tropopause is characteristic of tornadoes in the middle portion of the United States.  相似文献   
6.
边缘型旅游地的开发建设是中国旅游业转型升级时代面临的重要命题。随着区域经济一体化的推进和消费者消费理念的转变,一些边缘型旅游地开始逐渐成长为区域旅游发展的"潜力区",研究空间与研究意义日益凸显。以具有典型边缘性特征的宣城市为实证,从区位空间、旅游资源、旅游形象、旅游交通和旅游经济等角度剖析其多重边缘化特征,探讨边缘化形成的主要机制。地处省际交界区、地域特征典型性不足是边缘化形成的自然诱因,周边核心旅游地遮蔽效应显著是边缘化形成的空间致因,经济支撑能力薄弱是边缘化形成的经济制因,政策惠及偏少是边缘化形成的人为促因。边缘型旅游地应实施多元比附、突出个性差异、完善要素建设的发展路径。  相似文献   
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To look for gas hydrate, 22 multi-channel and 3 single-channel seismic lines on the East China Sea (ECS) shelf slope and at the bottom of the Okinawa Trough were examined. It was found that there was indeed bottom simulating reflector (BSR) occurrence, but it is very rare. Besides several BSRs, a gas seepage was also found. As shown by the data, both the BSR and gas seepage are all related with local geological structures, such as mud diapir, anticline, and fault-controlled graben-like structure. However, similar structural "anomalies" are quite common in the tectonically very active Okinawa Trough region, but very few of them have developed BSR or gas seepage. The article points out that the main reason is probably the low concentration of organic carbon of the sediment in this area. It was speculated that the rare occurrence of gas hydrates in this region is governed by structure-controlled fluid flow. Numerous faults and fractures form a network of high-permeability channels in the sediment and highly fractured igneous basement to allow fluid circulation and ventilation. Fluid flow in this tectonic environment is driven primarily by thermal buoyancy and takes place on a wide range of spatial scales. The fluid flow may play two roles to facilitate hydrate formation:to help gather enough methane into a small area and to modulate the thermal regime.  相似文献   
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The advent of ALMA is bound to improve our knowledge of OB star formation dramatically. Here, we present an overview of this topic outlining how high angular resolution and sensitivity may contribute to shed light on the structure of high-mass star forming regions and hence on the process itself of massive star formation. The impact of this new generation instrument will range from establishing the mass function of pre-stellar cores inside IR-dark clouds, to investigating the kinematics of the gas from which OB stars are built up, to assessing or ruling out the existence of circumstellar accretion disks in these objects.  相似文献   
10.
龙马溪组页岩是现阶段国内勘探的主要层位之一。川南扬子地区下古生界的龙马溪组气层存在低电阻率特征,仅从测井响应上很难与水层区别。为此,在现有常规测井、钻井取心、生产动态等资料的基础上,结合大量铸体薄片、QEMSCAN和X全岩衍射等岩心分析实验,对该地区低阻气层的成因机制进行了深入研究,结果表明:川南扬子地区下古生界的龙马溪组低阻气层的主控因素有3个:黏土矿物的附加导电性、过成熟有机质完全石墨化和有机质纹层分布形式。实际应用结果表明:研究区低阻气层的成因为发育的有机质纹层和有机质部分石墨化,即页岩气储层表现为低阻往往都是多种因素相互叠加、相互影响造成的,在分析时需要根据不同地区、不同层段分析相应地质、测井和岩心资料,并且需要利用上下层段对比和邻井对比等方法判断储层低阻的主控因素。  相似文献   
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