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1.
Measurements made when testing an interferometric system for imaging the sodium emission indicate that, between 3 and 7.5 arc min (9 and 23RJ) from Jupiter, the observed emissions can probably be attributed to terrestrial airglow. 相似文献
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阿尔金断裂带对青藏高原北部生长、隆升的制约 总被引:62,自引:3,他引:59
大量的同位素年代学证据表明(古)阿尔金断裂带可能形成于三叠纪,后又经历了侏罗纪、白垩纪的强烈左旋走滑活动,自印度板块与欧亚大陆碰撞后阿尔金断裂再次活动。主要的走滑活动发生在:(1)245~220Ma;(2)180~140Ma;(3)120~100Ma;(4)90~80Ma;(5)60~45Ma;(6)渐新世至中新世;(7)上新世至更新世以及(8)全新世。沿阿尔金断裂带,伴随左旋走滑活动形成一系列的逆冲断裂和正断裂,反映走滑过程中伴随隆升作用的存在,并且形成自北向南包括祁连山、大雪山、党河南山、柴北缘山、祁漫塔格山和昆仑山,表明阿尔金断裂带制约着青藏高原北部的生长和隆升。阿尔金断裂带东、西两端的白垩纪和新生代火山活动是断裂走滑活动的响应。 相似文献
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Landslides, avalanches, floods, and other geologic hazards impair natural resources management by jeopardizing public safety,
damaging or restricting resource utilization, and necessitating expenditures for corrective measures The negative impact of
geologic hazard events can be reduced by tailoring resources management to hazard potential of an area This requires assessment
of where and how frequently the events occur National forests and other managed wildlands often lack monitoring or historical
records to compute frequency of hazard occurrence Tree-ring analysis, based on internal growth response to external events
such as tilting and abrasion, can provide frequency data Two examples of the use of tree-ring analysis to date landslide activity
illustrate advantages and limitations of the technique An example from the Fishlake National Forest in central Utah illustrates
assessment for planning purposes An example from the Sierra National Forest in east-central California shows assessment applied
to project design Many geologic hazards in addition to landslides are suited to tree-ring analysis to establish frequency
of occurrence Hazard reduction efforts in natural resources management could be enhanced by careful application of tree-ring
analysis 相似文献
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Jerome O. Nriagu 《Geochimica et cosmochimica acta》1973,37(7):1735-1743
The reactions of secondary lead orthophosphate with approximately 10?1 M sodium fluoride and sodium bromide solutions have been investigated at 25°C. Interpretation of the solubility data resulted in solubility product constants for fluoropyromorphite and bromopyromorphite of 10?71.6 and 10?78.1, respectively. According to these constants, the stability sequence for lead pyromorphites is Pb5(PO4)3Cl > Pb5(PO4)3Br > Pb5(PO4)3OH > Pb5(PO4)3F. The derived free energy data have been used to evaluate the respective stabilities of fluoro-pyromorphite and bromopyromorphite within the systems PbF2-PbO-P2O5-H2O and PbBr2-PbO-P2O5-H2O and to predict the equilibrium behavior of the Pb5(PO4)3F-Pb5(PO4)3OH solid solution under aqueous conditions. 相似文献
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Spectrophotometry from 0.6–2.5 μm at 1.5% spectral resolution of Saturn's equator and visibly dark South Equatorial Belt near a 1980 ring-plane crossing shows substantially less absorption by methane over the equator than over the SEB. Model fits using Appleby's model atmosphere and a multiple scattering model lead to the conclusion that the pressure levels of the clouds in the two regions differ by 20%. The region of high clouds is coincident with the location of the equatorial fast jet observed by Voyager. 相似文献