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91.
Takeshi Naganuma Masanori Kyo Tatsuhiko Ueki Kazuhiko Takeda Jun-ichiro Ishibashi 《Journal of Oceanography》1998,54(3):241-246
A new hydrothermal fluid sampler has been developed to provide more maneuverability in underwater operation. The sampler characteristically
employs a shape-memory alloy, which senses high temperature and actuates the suction mechanism. A shape-memory alloy is also
used to switch the intake valve of the sampler, the intention being to avoid missampling when the inlet is in low temperature
water. Prototype samplers were designed to collect the fluids hotter than 80°C. Test sampling was performed at hydrothermal
vents (1372–1374 m deep) in the submarine volcano, Suiyo Seamount, Izu-Bonin Arc, northwestern Pacific. Observed fluid temperature
was between 138 and 298°C, while the ambient seawater temperature was 3.1°C. Each prototype collected about 100 ml fluid as
designed. The magnesium concentration in the samples indicated a seawater content of 47.5–90.8%, which indicates the entrainment
of ambient seawater. Microscopic observatinn revealed the occurrence of microorganisms in the sample fluids at a population
density of 105 to 106 cells ml−1, which is 2–3 orders of magnitude higher than those in seawater at that depth. The use of the newly developed fluid sampler
will greatly facilitate the collection of vent-associated microorganisms, which are of potential biological and biotechnological
interest. 相似文献
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针对我国西南印度洋合同区热液硫化物矿快速、有效以及便捷地质勘探装备的要求,研发了由甲板控制系统、万米光电复合缆、仪器舱拖体和天线拖体组成的深海6000 m拖曳式瞬变电磁系统.为了便于拖体布放和快速发现异常,选择重叠回线收发装置类型;采用理论数值计算确定了在拖曳高度不大于50 m的前提下,观测1～100ms窗范围内的二次场响应,可以发现近海底深海热液硫化物矿堆;另外,通过不同拖延深度海上试验,研究了拖曳深度对瞬变电磁的影响规律及仪器性能.大洋第30航次第二航段在西南印度洋脊热液区,应用该系统发现了明显的瞬变电磁异常.印证了系统的有效性. 相似文献
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The Sha-3-5 Submember of the Shahejie Formation in the Tanggu area of the Huanghua Depression contains analcime-bearing dolomite, indicating salinization of an ancient lake during deposition. Solar evaporation and hydrothermal salinization have both been proposed as ways to generate these saline conditions. Based on a comprehensive analysis of core data, thin sections, spore and pollen data, elemental geochemistry, pyrolysis results, and vitrinite reflectance, we assessed the mechanisms driving salinization in light of provenance evolution, geothermal evolution, paleoclimate, mineral responses to evaporation, and the relationship between fluid temperature and salinity. The vertical profiles of ΣREE, Eu/*Eu, and Tmax exhibit little variation, and the maximum paleotemperatures attained by organic matter are comparable to present-day drill hole temperature. No major changes in provenance or paleotemperature and no petrological fabrics that would indicate a hydrothermal input are observed in the studied section. However, evidence for a semi-humid to semi-arid climate, primary evaporitic textures and structures, and a positive relationship between fluid temperature and salinity all support evaporation as the primary mechanism driving rising salinity. Solar evaporation, rather than hydrothermal eruption, appears to have been the primary factor driving lake salinization during middle Eocene deposition of the dolomitic Sha-3-5 Submember. 相似文献
97.
Research on the fault controlling mechanism of geothermal water in Zhangzhou Basin 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Fault has an important influence on the storage and movement of geothermal water. The Zhangzhou Basin is wholly located in a granodiorite rock mass. Due to the low permeability of granodiorite, faulted structure has an evident control action on the hydrothermal activity of geothermal fields. Hot springs in Zhangzhou Basin crack along Pingtan-Dongshan Fault to the northeastern direction and emerge along Fu’an-Nanjing Fault. Through measurement of the temperature of several hot springs in the Basin, we found the temperature along the northwestern direction of Zhangzhou-Tianbao Fault is high and the temperature gap between the two sides of Yangxi-Yuanshan Fault is huge; the estimation of geothermal reservoir temperature of geothermal water through quartz geothermometer indicates that the geothermal reservoir temperature of the northern area of Nanjing-Xiamen Fault is obviously higher than that of southern area. Such result indicates that Fault obviously obstructs underground heat source. Under the condition that the average geothermal gradient of the Zhangzhou Basin is set, the circulation depth of the geothermal water of the Zhangzhou Basin measured by geothermal reservoir temperature is 3 550-5 200 m and the circulation depth of the geothermal water of the north of Nanjing-Xiamen Fault is deeper than that of the South. 相似文献
98.
G. P. Glasby 《Marine Georesources & Geotechnology》2013,31(2):161-176
The first attempt to exploit deep-sea manganese nodules ended in failure as a result of the collapse of world metal prices, the onerous provisions imposed by the U.N. Convention on the Law of the Sea (UNCLOS), and the overoptimistic assumptions about the viability of nodule mining. Attention then focused on Co-rich manganese crusts from seamounts. Since the mid-1980s, a number of new players have committed themselves to long-term programs to establish the viability of mining deep-sea manganese nodules. These programs require heavy subsidy by the host governments. Au-rich submarine hydrothermal deposits located at convergent plate margins are now emerging as a more promising prospect for mining than deep-sea manganese deposits. 相似文献
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Modern seafloor hydrothermal systems provide important insights into the formation and discovery of ancient volcanic-hosted massive sulfide (VHMS) deposits. In 2010, Integrated Ocean Drilling Program (IODP) Expedition 331 drilled five sites in the Iheya North hydrothermal field in the middle Okinawa Trough back-arc basin, Japan. Hydrothermal alteration and sulfide mineralization is hosted in a geologically complex, mixed sequence of coarse pumiceous volcaniclastic and fine hemipelagic sediments, overlying a dacitic to rhyolitic volcanic substrate. At site C0016, located adjacent to the foot of the actively venting North Big Chimney massive sulfide mound, massive sphalerite-(pyrite-chalcopyrite ± galena)-rich sulfides were intersected (to 30.2% Zn, 12.3% Pb, 2.68% Cu, 33.1 ppm Ag and 0.07 ppm Au) that strongly resemble the black ore of the Miocene-age Kuroko deposits of Japan. Sulfide mineralization shows clear evidence of formation through a combination of surface detrital and subsurface chemical processes, with at least some sphalerite precipitating into void space in the rock. Volcanic rocks beneath massive sulfides exhibit quartz-muscovite/illite and quartz-Mg-chlorite alteration reminiscent of VHMS proximal footwall alteration associated with Kuroko-type deposits, characterized by increasing MgO, Fe/Zn and Cu/Zn with depth. Recovered felsic footwall rocks are of FII to FIII affinity with well-developed negative Eu anomalies, consistent with VHMS-hosting felsic rocks in Phanerozoic ensialic arc/back-arc settings worldwide.Site C0013, ∼100 m east of North Big Chimney, represents a likely location of recent high temperature discharge, preserved as surficial coarse-grained sulfidic sediments (43.2% Zn, 4.4% Pb, 5.4% Cu, 42 ppm Ag and 0.02 ppm Au) containing high concentrations of As, Cd, Mo, Sb, and W. Near surface hydrothermal alteration is dominated by kaolinite and muscovite with locally abundant native sulfur, indicative of acidic hydrothermal fluids. Alteration grades to Mg-chlorite dominated assemblages at depths of >5 mbsf (metres below sea floor). Late coarse-grained anhydrite veining overprints earlier alteration and is interpreted to have precipitated from down welling seawater as hydrothermal activity waned. At site C0014, ∼350 m farther east, hydrothermal assemblages are characterized by illite/montmorillonite, with Mg-chlorite present at depths below ∼30 mbsf. Recovered lithologies from distal, recharge site C0017 are unaltered, with low MgO, Fe2O3 and base metal concentrations.Mineralization and alteration assemblages are consistent with the Iheya North system representing a modern analogue for Kuroko-type VHMS mineralization. Fluid flow is focussed laterally along pumiceous volcaniclastic strata (compartmentalized between impermeable hemipelagic sediments), and vertically along faults. The abundance of Fe-poor sphalerite and Mg-rich chlorite (clinochlore/penninite) is consistent with the lower Fe budget, temperature and higher oxidation state of felsic volcanic-hosted hydrothermal systems worldwide compared to Mid Ocean Ridge black smoker systems. 相似文献