重庆市垫江县水土流失及防治建议     

陈运东 《地质灾害与环境保护》1997,8(4):59-63

概略介绍了重庆市垫江县区境内的水土流失现状，影响因素，并在此基础上了防治建议。  相似文献   

利用近地表化探资料研究油气藏的保存条件及埋藏深度     

许卫平  郭旭升  孙剑  陈柱泽 《物探与化探》1996,20(2):99-103

利用地面化探资料能够有效地圈定出化探异常,指出烃类垂向运移发生的范围。但对于油、气勘探的需要,这仅仅是最基本的,是远远不够的。本文通过对垂向化探资料及地面游离烃化探资料的分析,对利用地化动力学指标判断油、气藏的保存条件及埋藏深度进行了初步的探讨。  相似文献   

保护多年冻土路基中存在的问题和对策     

V. G. Kondratjev 《冰川冻土》2004,26(Z1):8-11

Ways of strengthening railway embankment basis on ice-rich permafrost are characterized by regulating cooling and warming factors for preservation of the basis in constantly frozen condition (with the help of snow removal, painting, sun-precipitation shed, cross-section cooling pipes, the film cover,and the longitudinal cooling device) or removing icy masses preventively from the basis and filling the cavities simultaneously with not subsiding soils (with use of jet geotechnology). Skilled-experimental development are shined on the basis of new ways of strengthening embankment basis on ice-rich frozen soils.  相似文献   

石西油田石炭系水动力特征及其与含油性关系   总被引：1，自引：0，他引：1  

朱玉双  王震亮  林艳萍  高红 《地球化学》2003,32(4):387-392

利用油层流体的物化参数对油藏所处的水动力环境、油气运移方向及断层的封闭性进行了分析判断。研究结果表明，石西油田供水区在石007井东断裂西侧，并且由西向东渗人；石007井东断裂具有良好的封闭性，断裂东侧较西侧封闭，水动力也较西侧弱，使东断块油气较西侧易于保存，东断块含油显示也明显好于西断块。石西油田原油的物理性质与水动力环境有一定关系，但在平面上原油性质的变化主要受油气运移层析效应的控制。西断块水动力强，原油性质变化速率大；东断块水动力弱，原油性质变化速率小。油气运移方向为东、东北向西、西南，原油性质也沿该方向降低。  相似文献   

煤层气与地下水的赋存及运动特征对比   总被引：3，自引：0，他引：3  

刘阳华  曹立刚等 《中国煤田地质》2002,14(2):31-33

根据煤层气储存体与含水层体地质参数的对比,结合地下运动原理,认为煤层气产出过程中的运动要素与地下水体运动要素基本相近,在考虑气体的压缩性和粘滞性的情况下,亦可用类似描述地下水非稳定运动的微分方程和边界条件求解析解或数值法求解。  相似文献   

Preservation of aeolian genetic units by lava flows in the Lower Cretaceous of the Paraná Basin, southern Brazil     

Claiton M. S. Scherer 《Sedimentology》2002,49(1):97-116

The Lower Cretaceous geological record of the intracratonic Paraná Basin in southern Brazil comprises a thick succession of aeolian sandstones and volcanic rocks. The intercalation between aeolian sandstone and volcanic floods allowed the preservation of distinct aeolian genetic units. Each genetic unit represents an accumulation episode, bounded by supersurfaces, that coincides with the base of lava flood events. The entire package can be subdivided into a Lower Genetic Unit, which corresponds to aeolian sandstones preserved below the initial lava flows (Botucatu Formation), and an upper set of genetic units, which comprises interlayered aeolian deposits and lava floods (Serra Geral Formation). The Lower Genetic Unit is up to 100 m thick. Its base is composed of ephemeral stream and aeolian sand sheet deposits that are overlain by cross‐bedded sandstones whose origin is ascribed to simple, locally composite, crescentic and complex linear aeolian dunes. Aeolian accumulation of the lower unit was possible as a result of the existence of a wide topographic basin, which caused wind deceleration, and a large sand availability that promoted a positive net sediment flux. The Upper Genetic Units comprise isolated sand bodies that occur in two different styles: (1) thin lenses (<3 m thick) formed by aeolian sand sheets; and (2) thick sand lenses (3–15 m) comprising cross‐bedded cosets generated by migration and climbing of simple to locally composite crescentic aeolian dunes. Accumulation of the aeolian strata was associated with wind deceleration within depressions on the irregular upper surface of the lava floods. The interruption of sedimentation in the Lower and Upper Genetic Units, and related development of supersurfaces, occurred as a result of widespread effusions of basaltic lava. Preservation of both wind‐rippled topset deposits of the aeolian dunes and pahoehoe lava imprints indicates that lava floods covered active aeolian dunes and, hence, protected the aeolian deposits from erosion, thus preserving the genetic units.  相似文献   

论盐类保存条件研究对四川盆地三叠系找钾工作的重要性   总被引：1，自引：0，他引：1       下载免费PDF全文

林耀庭  许祖霖 《盐湖研究》2009,17(1):6-12

四川盆地三叠系T1j4、T1j5成盐期卤水浓缩程度较高,已达钾盐沉积阶段,然而人们至今并未找到固相可溶性钾矿层。究其原因,乃盆地T1j4、T1j5盐类形成以来经历了沉积成岩—古剥蚀淋滤—深埋封闭—再次剥蚀淋滤等4个地质及水文地质发展阶段,可能导致固相盐类乃至钾矿层的溶滤破坏,因此加强对盐类成盐期极其以后地质历史发展阶段保存条件的研究极其重要,应予重视。  相似文献   

舟山近海环境DNA保存方法的建立及优化   总被引：1，自引：0，他引：1  

陈治  陈建威  王晓艳  高天翔  刘岩 《海洋与湖沼》2019,50(5):1098-1107

近年来,环境DNA(environmentalDNA,eDNA)技术开始被广泛应用于水生生物多样性研究。本文通过绝对定量和高通量测序技术对舟山近海高浊度水样eDNA的保存方法进行了建立和优化。研究结果如下:(1)"酒精+低温"保存法的eDNA获得量是"酒精+常温"保存法的0.78—1.06 (7d)、0.89—1.80 (15d)、1.05—2.75 (30d)和2.69 (60d)倍;(2)酒精保存法(低温、常温)存在eDNA富集物渗漏及滤膜黏附现象;(3)短期内冷冻保存样品的eDNA获得量是酒精保存样品获得量的1.25—1.59倍(7d)和1.07—1.20倍(15d);(4)酒精保存法的eDNA降解速率慢于冷冻保存法,长期内酒精保存样品的eDNA获得量是冷冻保存样品获得量的1.99—2.10倍(30d)和2.84—7.64倍(60d);(5)二次富集(过滤)能显著提高eDNA获得量,富集组eDNA浓度是未富集组浓度的1.60—4.95倍("酒精+低温")和1.21—2.04倍("酒精+常温");(6)"酒精+低温"保存的样品在高通量测序总丰度、各鱼种分丰度、物种多样性指数等多个方面优于冷冻保存样品;(7)微生物(micro-organism)的eDNA降解速率慢于大生物(macro-organism),不同界(Kingdom)的eDNA最优保存方法可能并不相同。本研究首次建立了舟山近海高浊度水样eDNA最适保存方法,为相似水域的eDNA保存提供了借鉴参考。  相似文献   

Cyclic fluctuations of anoxia during Cretaceous time in the South Atlantic Ocean   总被引：1，自引：0，他引：1  

T. Jacquin  P.Ch. de Graciansky 《Marine and Petroleum Geology》1988,5(4)

The holes of the DSDP-IPOD program in the South Atlantic Ocean document two major anoxic events during Oxfordian to middle Albian times and secondly from late Cenomanian to Santonian times. The black shales formed during these two anoxic events differ in their rhythmicity and origin.During Lower Cretaceous time, the anoxic conditions resulted from the confined, euxinic nature of the basins. The rhythmicity of these black shales probably does not result from a global phenomenon (climatic or tectono-eustatic), but from local conditions resulting from the slender dimensions of the young ocean basin(s). The diversity and the diachroneity of the deposits from the south to the north precisely reflect the dynamics of the oceanic spreading.During Upper Cretaceous time, the anoxic conditions fluctuated in relation to a mid-water oxygen-minimum zone. The rhythmicity of black shale deposition seems to result from a global phenomenon, because of the widespread occurrence of the event. In the South Atlantic ocean, the cyclic fluctuations of anoxia were due to cyclic variations in the depth of the mid-water oxygen-minimum zone. There is no simple process to explain such rhythmicity. It probably results from the interplay of the three main variables which characterize the oceans at the time of the Cenomanian-Turonian boundary: the increased rate of sea floor spreading, high sea-levels and low water-circulation.  相似文献   

Preservation of the last aggradation phase in climate-driven terraces: Evidence from Late Quaternary reach-specific fluvial dynamics of the Allier River (France)     

A. Veldkamp  J.M. Schoorl  L. Claessens  A.J.A.M. Temme  A.G.M. Broers  T.L. van Orsouw  M.T.C.M. Voesten  T. Reimann 《地球表面变化过程与地形》2020,45(13):3381-3395

There is limited knowledge about the preservation of aggradation phases in Quaternary fluvial records. Previous numerical modelling of erosion and deposition in Late Quaternary Allier River (France) generated the prediction that this river has reach-specific fluvial dynamics related to climate-driven tributary sediment-flux dynamics. To test this prediction, new optically stimulated luminescence (OSL) samples were collected of the Late Quaternary Fx terrace at five locations along a stretch of 60 km. OSL dates of both quartz and feldspar sand grains indicate that all relatively basalt-poor sediments display significantly different ages for each reach (ranging from 36.3 ± 2.0 to 21.1 ± 2.3 ka). The more basalt-rich terrace body consistently yields ages in the range 21.1 ± 1.7 to 16.1 ± 1.5 ka, suggesting contemporaneous aggradation along the whole studied Allier reach during this interval. Our own new OSL date of a Tartaret eruption around 16.8 ± 2.5 ka also fits this time window, suggesting a direct link with volcanic activity. However, there are many more dated volcanic events that coincide with the older basalt-poor units, making it less likely that a direct link between terrace-sediment basalt content and volcanic activity exists. The timings of the dated depositional events in MIS 3 and 2 all match with simulated climate drivers and published landscape erosion rates. Counterintuitively, the volcanic Chaîne des Puys area supplied more sediment during the cold and dry Last Glacial Maximum. Basalt content in the Allier terrace sediments reflects climate-related sediment-flux dynamics upstream. The scarcity of older basalt-poor sediment bodies from MIS 4 and 3 in the Fx terrace suggests that less sediment was supplied and/or the intermittent erosional phases in the Allier were very effective at removing them. We hypothesize that this observation of predominant preservation of the last aggradation phase could be a common phenomenon in most climate-driven terraces. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献