36 resultados para peat
Resumo:
Ordos Basin is a typical cratonic petroliferous basin with 40 oil-gas bearing bed sets. It is featured as stable multicycle sedimentation, gentle formation, and less structures. The reservoir beds in Upper Paleozoic and Mesozoicare are mainly low density, low permeability, strong lateral change, and strong vertical heterogeneous. The well-known Loess Plateau in the southern area and Maowusu Desert, Kubuqi Desert and Ordos Grasslands in the northern area cover the basin, so seismic data acquisition in this area is very difficult and the data often takes on inadequate precision, strong interference, low signal-noise ratio, and low resolution. Because of the complicated condition of the surface and the underground, it is very difficult to distinguish the thin beds and study the land facies high-resolution lithologic sequence stratigraphy according to routine seismic profile. Therefore, a method, which have clearly physical significance, based on advanced mathematical physics theory and algorithmic and can improve the precision of the detection on the thin sand-peat interbed configurations of land facies, is in demand to put forward.Generalized S Transform (GST) processing method provides a new method of phase space analysis for seismic data. Compared with wavelet transform, both of them have very good localization characteristics; however, directly related to the Fourier spectra, GST has clearer physical significance, moreover, GST adopts a technology to best approach seismic wavelets and transforms the seismic data into time-scale domain, and breaks through the limit of the fixed wavelet in S transform, so GST has extensive adaptability. Based on tracing the development of the ideas and theories from wavelet transform, S transform to GST, we studied how to improve the precision of the detection on the thin stratum by GST.Noise has strong influence on sequence detecting in GST, especially in the low signal-noise ratio data. We studied the distribution rule of colored noise in GST domain, and proposed a technology to distinguish the signal and noise in GST domain. We discussed two types of noises: white noise and red noise, in which noise satisfy statistical autoregression model. For these two model, the noise-signal detection technology based on GST all get good result. It proved that the GST domain noise-signal detection technology could be used to real seismic data, and could effectively avoid noise influence on seismic sequence detecting.On the seismic profile after GST processing, high amplitude energy intensive zone, schollen, strip and lentoid dead zone and disarray zone maybe represent specifically geologic meanings according to given geologic background. Using seismic sequence detection profile and combining other seismic interpretation technologies, we can elaborate depict the shape of palaeo-geomorphology, effectively estimate sand stretch, distinguish sedimentary facies, determine target area, and directly guide oil-gas exploration.In the lateral reservoir prediction in XF oilfield of Ordos Basin, it played very important role in the estimation of sand stretch that the study of palaeo-geomorphology of Triassic System and the partition of inner sequence of the stratum group. According to the high-resolution seismic profile after GST processing, we pointed out that the C8 Member of Yanchang Formation in DZ area and C8 Member in BM area are the same deposit. It provided the foundation for getting 430 million tons predicting reserves and unite building 3 million tons off-take potential.In tackling key problem study for SLG gas-field, according to the high-resolution seismic sequence profile, we determined that the deposit direction of H8 member is approximately N-S or NNE-SS W. Using the seismic sequence profile, combining with layer-level profile, we can interpret the shape of entrenched stream. The sunken lenticle indicates the high-energy stream channel, which has stronger hydropower. By this way we drew out three high-energy stream channels' outline, and determined the target areas for exploitation. Finding high-energy braided river by high-resolution sequence processing is the key technology in SLG area.In ZZ area, we studied the distribution of the main reservoir bed-S23, which is shallow delta thin sand bed, by GST processing. From the seismic sequence profile, we discovered that the schollen thick sand beds are only local distributed, and most of them are distributary channel sand and distributary bar deposit. Then we determined that the S23 sand deposit direction is NW-SE in west, N-S in central and NE-SW in east. The high detecting seismic sequence interpretation profiles have been tested by 14 wells, 2 wells mismatch and the coincidence rate is 85.7%. Based on the profiles we suggested 3 predicted wells, one well (Yu54) completed and the other two is still drilling. The completed on Is coincident with the forecastThe paper testified that GST is a effective technology to get high- resolution seismic sequence profile, compartmentalize deposit microfacies, confirm strike direction of sandstone and make sure of the distribution range of oil-gas bearing sandstone, and is the gordian technique for the exploration of lithologic gas-oil pool in complicated areas.
Resumo:
Three soil spots were found in Grove Mountains, east Antarctica during 1999-2000, when the Chinare 16th Antarctic expedition teams entered the inland Antarctica. The characteristics of soils in Grove Mountains are desert pavement coating the surface, abundant water soluble salt, negligible organ matter, and severe rubification and salinization, scarces of liquid water, partly with dry permafrost, corresponding with the soils of McMurdo, Transantarctic. The soils age of Grove Mountains is 0.5-3.5Ma. Podzolization and redoximorphism are the main features in coastal Wilks region, in addition, there is strong enrichment of organic matter in many soils of this region. The main soil processes of Fildes Peninsula of King George Island include the intense physical weathering, decalcification and weakly biochemical processes. Peat accumulation is the main processes in Arctic because of humid and cold environment.Based on synthesis of heavy minerals, particle size, quartz grain surface textures, as well as pollen in soils, the soils parent materials of Grove Mountains derived from alluvial sediment of the weathering bedrocks around soils, and formed during the warm period of Pliocene. The detailed information is followed .l)The results of heavy minerals particle size showed the parent minerals derived form the weathering bedrocks around soils. 2)The quartz sand surface textures include glacial crushing and abrasion such as abrasive conchoidal fractures and grain edges, abrasive subparallel linear fractures and angularity, subaqueous environments produce V-shaped and irregular impact pits, polished surface, and chemical textures, such as beehive solution pits, which showed the water is the main force during the sediment of the soil parent minerals. 3)The pollen consist of 40 plant species, of which at least 5 species including Ranunculaceae, Chenopodiaceae, Artemisia, Gramineae, Podocarpus belong to the Neogene vegetation except the species from the old continent. Compared with Neogene vegetation of Transantarctic Mountains, Antarctic, we concluded that they grow in warm Pliocene.
Resumo:
泥炭作为一种地质档案,其发育形成过程中包含了丰富的古气候和古环境的变化信息。由于泥炭沉积中植物残体的碳、氧等稳定同位素组成与气候变化之间存在着密切关系,其稳定同位素时间序列已作为气候变化的代用指标逐渐用于古气候的恢复和重建,尤其是在以高时间分辨率重建全新世以来的气候环境变化方面已取得一些重要进展。 本论文通过对湖北省神农架地区大九湖泥炭中植物残体的氧、碳同位素的研究,同时以温度和湿度这两种重要的气候参数代用指标,恢复和重建全新世以来中国中部地区的气候状况。通过本论文的工作并与其它相关成果综合对比研究,对从末次冰消期晚期和全新世以来中国中部地区气候状况有如下的认识: 1. 末次冰消期晚期至全新世阶段,大九湖泥炭纤维素δ18O敏感地记录了发生在约14.67~12.89 cal. kaBP的BA暖期以及在此期间所发生的两次冷事件:Oder Dryas冷事件和Intra-Allerød冷事件;并指示随后的Allerød暖期明显较Bølling暖期偏冷;在新仙女木时期(YD),神农架地区温度较低,事件中后期温度开始回升;在11.0~9.0 cal. kaBP的早全新世时期,大九湖泥炭δ18O在波动中升高,指示了整体上的温暖气候,期间存在一系列的气候变冷事件。这些冷事件基本都是叠加在一种长期的、相对较暖的变化趋势上,有别于末次冰消期的突然变冷事件;在9.0~5.0 cal. kaBP的中全新世阶段,神农架地区总体上处于相对温暖的适宜阶段,但波动较为频繁,期间记录到了著名的“8.2ka”冷事件;约5.0 cal. kaBP开始,大九湖泥炭δ18O值持续升高,指示以一次快速的升温过程开始了晚全新世阶段并保持在一个相对较高的温度水平;在整体温暖的气候背景下也明显记录有“4.2ka”、“小冰期”等全球性冷事件;大九湖泥炭纤维素δ18O所记录的温度变化趋势与中国大陆地区其他一些气候代用指标所记录的温度变化趋势有很好的相似性,说明中国大陆地区温度变化的趋势基本一致。 2. 大九湖泥炭δ18O温度变化序列所记录到的历次突然气候变冷事件,与格陵兰冰芯和北大西洋冷事件的发生具有很好的一致性,这说明对应于北半球高纬度区域的气候变化,在中低纬度的中国地区同样存在响应和变化,并且这种响应贯穿于整个全新世阶段。 3. 大九湖泥炭纤维素δ13C敏感地记录了末次冰消期以来东亚季风的演变历史。东亚季风在整个末次冰消期至晚全新世阶段始终处于一种强弱交替的波动态势。在末次冰消期至全新世早期,其整体上表现为一种由弱转强的态势;在全新世早期和中期阶段,东亚季风活动强度整体较高,表现为整个时间序列中的高活动时段,而其中也出现了数次明显的减弱迹象;全新世晚期阶段,东亚季风的活动强度较中期和早期为弱,整体上表现出低幅的波动但没有恢复到前两个时期的活动强度。在中世纪温暖期阶段的中后期,东亚季风的活动强度开始在波动中逐渐升高。 4. 该泥炭纤维素代用指标所记录的一些东亚季风突变(增强)事件与同一时期所发生的印度季风的突变(减弱)事件具有很好的对应关系;进一步证实这两个季风系统之间所存在的反相变化关系;同时,这些突变事件与北大西洋IRD冷事件在发生时间段也具有较好的对应关系,即每当北大西洋地区气候变冷时,东亚季风都表现出增强的迹象。 5. 综合分析中国泥炭同位素古气候记录和其它研究结果,对气候驱动机制有如下认识:当太阳活动发生百年至千年时间尺度的减弱时,由大气臭氧层变化所触发的影响向大气层下部延伸,导致北半球气候变冷;同时,减弱的太阳活动可能在赤道太平洋触发类厄尔尼诺状态出现,并引发印度洋夏季风减弱和东亚夏季风增强;早全新世北半球冰盖周围大冰湖冰岸坍塌,湖中巨量体积淡水突然流入北大西洋,导致海洋温盐环流传送带运转放慢甚致停顿,通过跨赤道的温盐环流向北输送的热量大大减少,引起北半球气候变冷;由于海洋温盐环流的变化改变了全球热量的分配,暖水在地球南部积累,导致西太平洋暖池区域海表面水与深层水温度之间反差的增加,从而有利于类厄尔尼诺状态出现,同样将可能引起印度洋夏季风减弱和东亚夏季风增强。
Resumo:
泥炭以发育广泛、连续沉积好、沉积速率大(可达1mm/a甚至更大)、记录丰富等特点,正成为过去全球变化研究的良好综合地质档案.参考冰芯、黄土、深海沉积物等中矿物固体的研究思路和方法,希望能对泥炭中可能存在的火山物质和其它风粉尘进行研究.在对吉林金川西大甸子泥炭样品的处理过程中,摸索出一套泥炭样品中固体物质(如火山物质)初步的处理、分析方法;并对金川西大甸子干玛珥泥炭沉积中部一段泥砂状物质进行鉴定,首次发现火山玻璃,判断这些泥砂物为火山灰砂.目前研究表明,泥炭纤维素的δ<'13>C序列能较好地反映古气候变化,那么泥炭中胡敏酸的δ<'13>C序列可否也能反映古气候变化,该文对此作了初步研究.用碱溶酸沉淀方法从泥炭中提取出所谓的胡敏酸,用燃烧法将胡敏酸、纤维素中的碳转化为CO<,2>气体,测定它们的稳定碳同位素组成(δ<'13>C).与能较好地反映气候变化的纤维素δ<'13>C序列相比,胡敏酸的δ<'13>C序列反映气候变化不明显.
Resumo:
植物稳定同位素气候学因其具有坚实的理论基础,在古气候研究中倍受关注。同位素“语言”对气候变化的记录是一种“精确”记录。近30多年来,大量科学家不懈努力,提出并完善了植物C、H、O同位素分馏模型,为全球气候变化提供了理想的研究手段。古气候研究面临空前的机遇和挑战;不论是气候规律的发掘以及气候驱动机制的探讨,均需要大力加强。作者利用植物同位素气候学这一理想的研究“工具”,分别选取树轮和泥炭气候历史档案库作为信息载体,开展了中国全新世以来高分辨率、多时间尺度的气候信息综合辨识。我的工作表明:植物稳定同位素组成是理想的气候代用指标。树轮、泥炭档案库相结合,可以获得多尺度(年际、代际、百年以及千年时间尺度)、高分辨率气候信息,对于认识全球气候变化规律以及深入探讨全球气候动力学机制是十分重要的。1、安图红松树轮同位素气候代用记录研究(1)安图红松树轮同位素组成受多种气象因子的联合作用,因而单一地将某一同位素指标与某一气象因子做回归分析所得结果不甚理想。本论文构建了“温度一湿度”复合气候指标,取得了理想的结果。研究发现,不论是树轮δ13C还是δ18O,均与5-8月温湿复合指标显著相关。重建的气候变化与《安图县志》记录的气候变化事件大多吻合。证明这种新的研究方案是可行的,值得在以后的工作中进一步加强。(2)安图红松树轮δ13C灵敏地记录了该区过去200年来5-7月低云量变化。综合分析各种气象要素之间的相关关系以及气象要素与树轮δ13C之间的相关关系,作者认为,低云量对树轮δ13C的影响是一种间接影响。低云量非常显著地影响日照强度以及降雨量等气象因子,进而借助于日照强度及降雨量等气象因子在树轮δ13C中留下自身的变化“印记”。(3)功率谱分析证明,安图红松树轮δ13C、δ18O序列均包含了显著的准2年周期、准4年周期、准10-8年周期。分别是对东亚夏季风准两年振荡(QBO),ENSO准4年周期,太阳活动准11年周期的响应。(4)作者在传统树轮氢、氧同位素分馏模型基础上,同时引入“交换因子”和“蒸腾因子”两个新参数,改进了树轮氢、氧同位素分馏模型。改进的模型能利用树轮H、O同位素组成较准确模拟大气降水H、O同位素组成。改进的模型采用“自适应”方式,具有很大的灵活性,可望用于“用泥炭同位素组成模拟大气降水同位素组成”这项研究中。2、红原泥炭氧同位素气候代用记录研究(1)过去6000年来,红原温度变化趋势与金川、敦德温度变化趋势有很好的相似性,证明中国大多地区温度变化趋势是一致的。6000~4000aBP平均温度水平较低;4000-1500 aBP平均温度水平较高;1500aBP至今平均温度水平相对较低。4000aBP和1500aBP是近6000年温度变化序列中两个显著的转折点。(2)红原温度变化序列中记录到一系列低温突变,这些突变事件与金川、敦德、格陵兰、北大西洋,等等,广泛区域内温度突变事件具有很好的一致性。特别地,每当一次低温突变事件发生,通常有相应的社会结构重整、社会崩溃、古文明坍塌等重大历史事件与之对应。这进一步证实,气候变化(特别是气候突变)对整个社会经济和文明的冲击是十分明显的。(3)近6000年红原、金川温度变化趋势与大气14C变化趋势非常相似,暗示中国地区温度变化的主要驱动力来自太阳活动。功率谱分析进一步证实了这一结论。功率谱分析中最显著的周期信号是88-yr和123-127-yr年周期,体现了一种典型的世纪尺度温度变化特征。3、综合讨论(1)“红原-金川”平均温度变化趋势显示,近千年中国平均温度变化与经典的太阳活动极小期,如Darton极小、Maunder极小、sp6rer极小、oort极小,等等,表现一致。表明中国气温变化主要驱动力来自太阳活动。大约在1050-1250AD期间,中国温度水平较高。而同期大气14C,南极冰心10Be以及模拟的总太阳辐射等均表明太阳活动处于较高水平。大量树轮记录也表明近百年中国并无异常升温。这些资料表明,最近百年气温变化可能并未超出自然变率。(2)提出了“大洋温盐环流一季风”概念模型。这一模型能很好解释北大西洋温度突变与印度洋夏季风突变的一致性、中国东北和西南长期降雨趋势的反相性、北太平洋(温盐环流上翻区)温度记录与北大西洋温度记录的“跷跷板”效应(seesaw effect),等等。大洋温盐环流可能是主宰印度洋夏季风区、东亚夏季风区长期干湿变迁的主要因素。
Resumo:
泥炭是第四纪,特别是全新世以来的产物。它的形成和积累主要受控于气候,其次是地质、地貌、水文等因素。因此,泥炭形成过程中包含了大量的古气候、古环境演化信息。腐殖化度在国外早已用于古气候研究,国外学者将它作为湿度代用指标,用以恢复古湿度变迁。本文首次将之引入我国泥炭古气候研究,同时结合青藏高原的气候特点,及泥炭形成过程中温度、湿度对它的影响,赋予了泥炭腐殖化度新的气候内涵。即泥炭的腐殖化度高,指示气候温暖湿润;泥炭的腐殖化度低,指示气候干燥寒冷。本文通过对青藏高原东北部红原泥炭的腐殖化度研究,并与其它研究成果对比,得出如下结论:(1)红原泥炭腐殖化度记录了过去12000年以来当地气候干湿冷暖的变化。其气候变化大致可分为3个阶段:11.8-11.2 kaBP,气候干燥寒冷;11.2-5.5 ka BP,气候温暖湿润;5.5-0 ka BP,当地气候由早中全新世温暖湿润的气候向干燥寒冷的气候波动。红原泥炭腐殖化度记录的气候变化与高原青海湖沉积物、松西错沉积物、敦德冰芯、古里雅冰芯记录的气候变化相似,表明青藏高原12000年以来可能受同一气候系统影响,其气候变化的共同特点为干冷与暖湿交替。(2)泥炭腐殖化度记录了12000年以来印度西南季风在高原的强弱演化。新仙女木期(11.8-11.2kaBP),季风强度最弱;从11.2kaBP到10.8kaBP季风强度快速增强;在10.8ka即到5.5 ka BP,季风强度一直处于强势阶段;从5.5 ka BP开始,印度西南季风强度逐渐减弱,这期间腐殖化度同时记录了百年一千年尺度印度西南季风增强事件,但总体减弱的趋势不变。(3)泥炭腐殖化度记录的百年一千年气候突然变化事件与北大西洋浮冰事件存在遥相关。对应8次浮冰事件,红原地区气候同时变得干冷,而印度西南季风强度也减弱,这表明不但末次冰期印度西南季风与北大西洋气候密切相关,而且在全新世,这种相关性同样存在。(4)泥炭腐殖化度距平值较好的反映了西太平洋副热带高压近5000年来的活动变化。腐殖化度代用指标能很好地记录较长时间西太平洋副热带高压的变化,而对西太平洋副热带高压数十年到百年的频繁波动,则记录不明显。(5)泥炭腐殖化度时间序列的功率谱分析表明,太阳活动对红原地区气.候演化有重要影响,同时太阳活动通过影响全球水循环,进而驱动温盐环流的变化,进一步影响全球气候变化。(6)泥炭腐殖化度能同时记录温度、湿度的变化,并且测定方法简便、快捷,值得进一步研究。