SOME NEW UNDERSTANDINGS OF LAND-SURFACE PROCESSES IN ARID AREA FROM THE HEIFE^*          下载免费PDF全文

Hu Yinqiao  Gao Youxi 《Acta Meteorologica Sinica》1996,10(2):233-246

The survey for the HEIFE(Atmosphere-Land Surface Processes Experiment at Heihe River Basin,Western China) is given in the paper.The following basic subjects for land-surface processes in arid areas are studied:(1) the general characteristics of the energy budget on ground surface in arid areas;(2) the parameterization of the land surface processes;(3) the interaction between oasis and its desert circumstances,a special phenomenon in arid areas.The analysis shows that the sensible heat flux in the surface energy budget is in the majority,and the latent heat flux may be neglected.The influence of atmospheric stratification stability on the turbulent transfer of energy and substance must be considered in parameterization of land surface processes in arid areas.The "cold island effect" phenomenon in oasis and the "humidity inversion" phenomenon in desert near oasis are the result of the interaction between them.The results would improve the understanding of land surface processes in arid areas.  相似文献   

Oil and gas resource assessment: The linkage between geological analysis and discovery process model results     

Lawrence J. Drew  John H. Schuenemeyer 《Natural Resources Research》1996,5(1):33-42

Two widely-used techniques to estimate the volume of remaining oil and gas resources are discovery process modeling and geologic assessment. Both were used in a recent national assessment of oil and gas resources of the United States. Parallel estimates were obtained for 27 provinces. Geological-based estimates can typically see into areas not available to discovery process models (that is areas with little or no exploration history) and thus, on average, yield higher estimates. However, a linear relation does exist between the mean estimates obtained from these two methods. In addition, other variables were found in a multiple regression model that explained much of the difference. Thus, it is possible to perform discovery process modeling and adjust the estimates to yield results that might be expected from geological-based assessments.  相似文献   

Rupture process of large earthquakes in the northern Mexico subduction zone     

Larry J. Ruff  Angus D. Miller 《Pure and Applied Geophysics》1994,142(1):101-172

The Cocos plate subducts beneath North America at the Mexico trench. The northernmost segment of this trench, between the Orozco and Rivera fracture zones, has ruptured in a sequence of five large earthquakes from 1973 to 1985; the Jan. 30, 1973 Colima event (M _s 7.5) at the northern end of the segment near Rivera fracture zone; the Mar. 14, 1979 Petatlan event (M _s 7.6) at the southern end of the segment on the Orozco fracture zone; the Oct. 25, 1981 Playa Azul event (M _s 7.3) in the middle of the Michoacan gap; the Sept. 19, 1985 Michoacan mainshock (M _s 8.1); and the Sept. 21, 1985 Michoacan aftershock (M _s 7.6) that reruptured part of the Petatlan zone. Body wave inversion for the rupture process of these earthquakes finds the best: earthquake depth; focal mechanism; overall source time function; and seismic moment, for each earthquake. In addition, we have determined spatial concentrations of seismic moment release for the Colima earthquake, and the Michoacan mainshock and aftershock. These spatial concentrations of slip are interpreted as asperities; and the resultant asperity distribution for Mexico is compared to other subduction zones. The body wave inversion technique also determines theMoment Tensor Rate Functions; but there is no evidence for statistically significant changes in the moment tensor during rupture for any of the five earthquakes. An appendix describes theMoment Tensor Rate Functions methodology in detail.The systematic bias between global and regional determinations of epicentral locations in Mexico must be resolved to enable plotting of asperities with aftershocks and geographic features. We have spatially shifted all of our results to regional determinations of epicenters. The best point source depths for the five earthquakes are all above 30 km, consistent with the idea that the down-dip edge of the seismogenic plate interface in Mexico is shallow compared to other subduction zones. Consideration of uncertainties in the focal mechanisms allows us to state that all five earthquakes occurred on fault planes with the same strike (N65°W to N70°W) and dip (15±3°), except for the smaller Playa Azul event at the down-dip edge which has a steeper dip angle of 20 to 25°. However, the Petatlan earthquake does prefer a fault plane that is rotated to a more east-west orientation—one explanation may be that this earthquake is located near the crest of the subducting Orozco fracture zone. The slip vectors of all five earthquakes are similar and generally consistent with the NUVEL-predicted Cocos-North America convergence direction of N33°E for this segment. The most important deviation is the more northerly slip direction for the Petatlan earthquake. Also, the slip vectors from the Harvard CMT solutions for large and small events in this segment prefer an overall convergence direction of about N20°E to N25°E.All five earthquakes share a common feature in the rupture process: each earthquake has a small initial precursory arrival followed by a large pulse of moment release with a distinct onset. The delay time varies from 4 s for the Playa Azul event to 8 s for the Colima event. While there is some evidence of spatial concentration of moment release for each event, our overall asperity distribution for the northern Mexico segment consists of one clear asperity, in the epicentral region of the 1973 Colima earthquake, and then a scattering of diffuse and overlapping regions of high moment release for the remainder of the segment. This character is directly displayed in the overlapping of rupture zones between the 1979 Petatlan event and the 1985 Michoacan aftershock. This character of the asperity distribution is in contrast to the widely spaced distinct asperities in the northern Japan-Kuriles Islands subduction zone, but is somewhat similar to the asperity distributions found in the central Peru and Santa Cruz Islands subduction zones. Subduction of the Orozco fracture zone may strongly affect the seismogenic character as the overlapping rupture zones are located on the crest of the subducted fracture zone. There is also a distinct change in the physiography of the upper plate that coincides with the subducting fracture zone, and the Guerrero seismic gap to the south of the Petatlan earthquake is in the wake of the Orozco fracture zone. At the northern end, the Rivera fracture zone in the subducting plate and the Colima graben in the upper plate coincide with the northernmost extent of the Colima rupture zone.  相似文献   

热液脉动与岩浆涌动控制机理浅论     

易顺化  李同林  李珍 《地质科技情报》1994,(1)

热液脉动与岩浆涌动的控制机理,是基础地质理论所涉及的两个重要议题。本文首先对当今流行的构造控制机理提出了质疑,其后借助＂间歇喷泉＂原理和＂吹气球＂机制,分别对热浪的脉动和岩浆的涌动进行了必要的探讨。  相似文献   

钾霞石制备体系碱性滤液的利用技术     

路华龙  霍光祥  段永华  勾明雷  刘军娜  刘晨 《岩石矿物学杂志》2024,43(1):125-130

为处理钾长石水热制备钾霞石所产生的碱性滤液,本文采用水热法,考察了氢氧化铝溶解时间、晶化时间、晶化温度、水碱比对钾霞石产率和白度的影响,并对合成钾霞石物相进行了表征。结果表明,合成钾霞石的最佳条件为,氢氧化铝溶解时间为1.5 h,晶化时间为4 h,晶化温度280℃,水碱比为1.8。XRD结果表明,产物为钾霞石粉体。傅里叶变换红外光谱表明,Al(OH)₃中的Al在水热条件下进入到Si—O骨架中形成了Si—O—Al官能团,从而印证了钾霞石的合成。差热分析结果表明,合成钾霞石具有良好的热稳定性。氮气吸附结果表明,合成钾霞石比表面积为5.18 m²/g,平均孔径为32.98 nm。实现了钾长石水热制备钾霞石所剩碱性滤液的资源化利用,并为钾长石水热制备钾霞石提供了一种母液循环的思路,使水热制备钾霞石工业化成为一种可能。  相似文献   

Multi-stage metallogeny in the southwestern part of South China,and paleotectonic and climatic implications: A high precision geochronologic study     

《地学前缘(英文版)》2023,14(3):101536

The South China Block (SCB) is among the large-scale W-Sn mineralized regions of the globe. The Laojunshan W-Sn-dominant ore area (LOA) in the western part of the SCB preserves the records of the tectonic history of the Tethys realm extending through North Vietnam, and Yangtze to Cathaysia blocks, with coeval formation of giant metallic deposits. The prolonged tectonic activities and their control on the genesis and spatio-temporal distribution of giant metallic deposits in the LOA provide a window for a holistic understanding of the tectono-metallogenesis of the SCB. In this study, we present results from a multi-chronologic study to determine the timing of formation of the cassiterite-wolframite-scheelite mineralization. The results suggest three distinct tectono-metallogenic periods in the LOA during the geodynamic evolution of the surrounding tectonic units. The opening of the Proto-Tethys Ocean between the Yangtze-Indochina blocks and the westward Paleo-Pacific subduction beneath the Cathaysia block (420–380 Ma) jointly contributed to the Silurian to early Devonian intracontinental orogeny in the middle of the SCB that involved top-to-the-north thrusting along NE-striking shear zones. This event generated the Dulong-Song Chay granitoids, together with the formation of Xinzhai Sn deposit related to sheared mylonitic granites (ca. 419 Ma) and pegmatites (ca. 389 Ma), which include the early-stage Sn-sulfide skarn (ca. 418 Ma) and the late-stage Sn-bearing schist (ca. 389 Ma). During the Late Permian to Late Triassic (260–220 Ma), with the closure of the Proto-Tethys oceans in the west and ongoing Paleo-Pacific westward subduction in the east, the SCB and Indochina Block (IB) were amalgamated which also marks the time of formation of the Nanwenhe scheelite skarn deposit. The subducted Paleo-Tethys oceanic crust was likely entrained by the nearby rising Emeishan mantle plume (270–259 Ma), which formed the Maguan diabase (ca. 260 Ma) that shows significantly older Re-Os model age of ca. 268 Ma, suggesting that the Nanwenhe mineralization is potentially derived from ca. 260 Ma source. Furthermore, the intraplate shortening induced thin skinned crustal deformation and low grade metamorphism (ca. 230 Ma), with the main stage of scheelite-Sn-Mo mineralization (229.9, 229.8 and 219 Ma) and contemporary formation of the pegmatite (230.7 Ma). The Late Cretaceous involved two episodes of alternate extension and shortening, driven by the subduction polarity change from northwestward subduction of the Okhotomorsk block to northward subduction of the NeoTethys seafloor. The evolution of the LOA consists of the NW–SE transpression ending ca. 100 Ma, the WNW–ESE extension in the earlier episode lasting from 100 Ma to 86 Ma, the WNW–ESE transpression beginning at ca. 85 Ma and the NS extension in the later episode during the latest Cretaceous, which produced the extension-related three periods of Laojunshan granitic magmatism and coeval Sn-W mineralization, with ages in the range of 90–89 Ma, 87–85 Ma and 83–79 Ma. We also evaluate the implications of magmatic-metamorphic-metallogenic degassing on the regional paleoclimatic history.  相似文献   

甘孜- 理塘洋可能存在北向俯冲：来自松潘- 甘孜道孚- 炉霍岩浆岩的证据     

卢雨潇  杨经绥  许志琴  连东洋 《地质学报》2022,96(7):2380-2402

松潘- 甘孜造山带巨厚的三叠系复理石沉积盖层给探讨其基底性质、俯冲- 碰撞过程和深部岩浆作用增添了难度，使得带内广泛出露的花岗质岩体和少量镁铁质岩体成为解开松潘- 甘孜造山带构造演化谜团的重要研究对象。锆石U- Pb定年结果表明道孚花岗闪长岩形成于223. 5~217. 4 Ma，炉霍二长岩结晶年龄为219. 4 Ma，辉长岩为218. 9 Ma，均属于晚三叠世岩浆活动的产物。化学成分研究结果表明，花岗质岩石都表现出I型花岗岩特征，其中炉霍二长岩具有较高的Ba、Sr含量，相对较高且均一的εHf(t)值（-3. 69~-1. 65），表明其可能来源于富集玄武质新生下地壳的熔融。道孚花岗闪长岩具有分散的εHf(t)值（-13. 51~0. 41），野外和地球化学特征指示其形成于幔源熔体与古老壳源熔体的混合。辉长岩在微量元素蜘蛛图上具有类似的模式，不同程度富集Ba、Sr、Pb、Th和U元素，出现Nb、Ta、Ti元素亏损，具有岛弧玄武岩的特征，来源于流/熔体交代的地幔楔部分熔融。综合区域已有资料，我们对甘孜- 理塘洋的演化历史提出新的认识，认为甘孜- 理塘洋不仅仅存在向南俯冲的可能性，同时也具有北向俯冲的历史，晚三叠世道孚- 炉霍岩浆岩的形成受控于甘孜- 理塘洋向北边松潘- 甘孜地块俯冲的背景之下。  相似文献   

Research on temporal and spatial distribution, evolutionary character and mechanism of crustal deformation field before and after the Tangshan earthquake   总被引：2，自引：0，他引：2  

周硕愚  施顺英  帅平 《地震学报(英文版)》1997,10(6):693-701

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硫铅酸盐“S”型瞬凝水泥干法护壁堵漏技术研究          下载免费PDF全文

彭振斌 《探矿工程》1995,(2):41-42,60

介绍了硫铝酸盐“Ｓ”型瞬凝水泥干法者漏时使用的配方,阐述了输送工具和扫孔钻具的设计以及灌注工艺技术。  相似文献   

MODERNIZATION PROCESS IN HISTORICAL ASIAN CITIES AND THEIR CHARACTERISTICS: A COMPARATIVE STUDY ON SEOUL, TOKYO AND BEIJING     

Li Wenyan 《地理学报(英文版)》1995,(2)

Thspaperwaspresatedatthe"94SeoulIntemationalSyInPosiumonCityandffistory"heldonOCtober27to28,l994andthenpublishedinTheJoumaIofSeouIShndesVo.IV.Thepresentvisionhasbeenslighlyrevised.Bejing,SeoulandTokyoarecapitalsofthreeneighbouringcoUnnesinNortheastAsia,wh…  相似文献