塔里木盆地东北缘吐格尔明背斜和阳北断裂带构造分析

吐格尔明背斜和阳北断裂位于塔里木盆地北缘,南天山山前库车褶皱冲断带的东段,两者均为基底卷入型构造。阳北断裂是一个反转构造,其变形历史可以追溯到侏罗纪—白垩纪的正断层;新生代构造反转,发生了多期冲断变形加速期,分别发生于白垩纪末—古近纪初、古近纪末—新近纪初、中新世早期、上新世和第四纪。吐格尔明背斜构造带是阳北断裂中新世早期及以后的冲断作用派生出来的一个次级基底卷入型构造变形带。它由吐格尔明背斜及其南、北两条呈背冲关系的逆冲断层组成。背斜核部元古宇变质岩出露地表;中、新生界直接不整合于变质岩之上,缺失全部古生界,说明研究区可能属于一个长期存在的古生代古隆起。

     

Chemical composition and physical properties of lithium-iron micas from the Krušné hory Mts. (Erzgebirge)

Compositions of natural lithium-iron micas are approximated best by the sidero-phyllite-polylithionite join. These micas contain little or no magnesium and manganese. Their octahedral sheets contain close to two trivalent cations (mainly aluminum) in small crystallographic sites and a variable quantity of lithium and R⁺² (mainly iron) in large sites. Octahedral vacancies are situated mostly in large sites. Lithium and R⁺² approach a 44 replacement relationship in micas with octahedral occupancy close to six. Lithium and fluorine show a good positive correlation (small excess of fluorine over lithium), which indicates a crystallochemical association between them. There is a less distinct positive correlation between lithium and R⁺⁴.Based on simplifications, a calculation shows that about two-thirds of octahedral vacancies are caused by substitutions within the octahedral sheet, one-third, by tetrahedral substitutions. Different methods of calculating the crystallochemical formula yield slightly different numbers of octahedral vacancies, but do not affect the mica's position in plots of physical parameters against composition. If a crystallochemical formula is calculated from analysis of a mica contaminated with quartz, topaz, or feldspar, the apparent number of octahedral vacancies increases; such a formula exhibits unusual behavior in composition plots.     

西藏阿里札达盆地早更新世早期沉积及其古气候与古环境变化

综合分析了西藏阿里札达盆地早更新世早期的多种与气候环境变化密切相关的地质记录，结果表明该区早更新世早期的沉积可划分为3种不同的沉积相和4个岩性段；古气候与古环境变化可划分为4个阶段：（1）2．68-2．45Ma。为冲洪积相沉积。冻融褶皱开始出现，植被以乔木为主，主要为松、藜、蒿，属山地寒温气候；（2）2．45-2．11Ma，为冲洪积相，地层中冻融褶皱多呈扭曲状，草本植物迅速上升，显示出灌木草原气候特征，气候变得凉爽干燥；（3）2．11-1．49Ma，沉积相为冲洪积相-冰缘沉积相，以冰缘沉积相为主，冻融褶皱层开始增多，出现了喜凉的介形类化石。草本植物数量和种类达到最大，灌木也相对增加，显示气候进一步趋于干旱；（4）1．49-1．36Ma，为冰湖沉积相。地层中普遍出现冻融褶皱，喜凉的介形类化石丰度很高，草本植物有小幅下降，但蕨类植物增加幅度较大，显示了干冷草原气候特征。气候干旱寒冷。     

二元同位素测温技术及其在白云岩储层成因研究中的应用——以塔里木盆地中下寒武统为例

作为近年来新兴的实验技术,二元同位素(D47)测温技术已被应用于碳酸盐岩成岩环境的研究中。简要介绍了二元同位素测温技术的原理及应用方法,并以塔里木盆地中下寒武统白云岩为例,优选11块样品,测试其D47值和白云石的碳氧同位素,并计算出样品的成岩温度和古流体的δ~(18)O值。综合分析认为:样品中,颗粒白云岩形成于低温准同生—浅埋藏环境,成岩流体为海水;细晶白云岩为深埋藏成岩环境中原岩受到了高温重结晶作用的改造,成岩流体为地下热卤水;孔缝中的白云石胶结物是深埋藏成岩环境富镁热卤水沉淀作用的产物。研究证明二元同位素测温技术可以较好地恢复白云岩的成岩温度,减少储层成因的多解性,它为今后储层成因研究提供了一种新的手段和依据。     

KT178型取心钻具在共和干热岩钻井中的应用

共和干热岩资源富集于花岗岩地层,硬度高,研磨性强,部分层段裂隙发育,取心困难。针对干热岩地层和取心需求特点,研制一套KT178取心钻具,并配套设计了孕镶金刚石取心钻头。该钻具为单动双管取心钻具,可配套井底动力钻具使用,设计中注重对钻具外管、卡簧等关键部件的强度校核。在GH-01井和GH-02井中,经过两轮实验和优化,钻具逐渐成熟,获取了较完整的岩心样本,满足干热岩勘探取心要求,具备了向页岩气、水资源勘察等具有间断取心需求的同类工程推广应用的条件。     

Climatic change during the last 4000 years in the southern Tarim Basin,Xinjiang, northwest China

In this study, a ca. 4000 cal. yr ancient lacustrine (or wetland) sediment record at the southern margin of Tarim Basin is used to reconstruct the history of climate change. Six radiocarbon dates on organic matter were obtained. δ¹⁸O and δ¹³C of carbonate, pollen and sediment particle size were analysed for climate proxies. The proxies indicate that a drier climate prevailed in the area before ca. 1010 BC and during period 1010 BC–AD 500 climate then changed rapidly and continuously from dry to moist, but after about AD 500 climate generally shows dry condition. Several centennial‐scale climatic events were revealed, with the wettest spell during AD 450–550, and a relatively wetter interval between AD 930–1030. Pollen results show that regional climate may influence human agricultural activities. Spectral analysis of mean grain size (MGS) proxy reveals statistically pronounced cyclic signals, such as ca. 200 yr, ca. 120 yr, ca. 90 yr, ca. 45 yr and ca. 33 or 30 yr, which may be associated with solar activities, implying that solar variability plays an important role in the decadal‐ and centennial‐scale climate variations in the study area. Copyright © 2007 John Wiley & Sons, Ltd.     

山西宁武吕梁山北段第四纪冰川遗迹的发现及意义

山西宁武吕梁山北段,平均海拔约2000米,相对高差数百米至千米左右,属中山区。第四纪冰川遗迹十分发育,类型多种多样,特征明显。冰川遗迹有:U形谷、刃脊、角峰、冰斗、冰窖及分布于U形谷中的大量冰川漂砾、冰碛、冰水堆积、冰臼、变形砾石、条痕石等。该区古冰川遗迹的大量发现,不仅证明了我国东部中低山区有大量第四纪冰川运动存在,而且冰川规模之大完全出乎人们意料之外。为研究该区古气候、古环境演化提供重要依据,为我国第四纪冰期划分和对比提供重要资料和证据。      

含富锂(钾)卤水断陷盆地的深部构造特征: 以中国华南吉泰盆地为例

中国华南吉泰盆地在白垩纪?古近纪发育大量蒸发岩,其中含富锂卤水矿床,由于盆地深部构造特征认识不清,导致富锂卤水矿勘查评价明显滞后.基于盆地东北部泰和坳陷二维地震数据和钻孔资料,经过精细保幅处理和综合构造解释,总结了含富锂卤水矿断陷盆地的深部构造特征.地震剖面和构造属性表明,盆地深部发育错断白垩系的NE-SW走向、NW倾...     

A Critical Comparison of Three Methods for Time-Lapse Time-Shift Calculation

Time-shift, one of the most popular time-lapse seismic attributes, has been widely used in dynamic reservoir characterization by linking it with pressure and geomechanical changes. Therefore, it is important to select appropriate calculation methods according to different time-lapse seismic data quality and time-shift magnitude. To date, there have been various published works comparing different time-shift calculation methods and discussing their advantages and disadvantages. However, most of these comparisons are based only on synthetic tests or single field applications. As the quality of time-lapse seismic data and time-shift magnitude can vary in different fields, one method may not work consistently well for each case. In this paper, a critical comparison of three different time-shift calculation techniques (Hale’s fast cross-correlation, Rickett’s non-linear inversion, and Whitcombe’s correlated leakage method) is provided. The three methods are applied to a set of synthetic data sets that are designed to account for various seismic noise and time-shift magnitudes. They are also applied to four real time-lapse seismic data sets from three North Sea fields. The calculated time-shift results are compared with the input (in synthetic tests) or the real observations from information such as seabed subsidence and compaction (in field applications). Both qualitative and quantitative comparisons are performed. At the end, each of the time-shift methods is evaluated based on different aspects, and the most appropriate method is suggested for each data scenario. All three time-shift methods are found to successfully measure time-shifts. However, Rickett’s non-linear inversion is the most outstanding method, as it gives smooth time-shifts with relatively good accuracy, and the derived time strains are more stable and interpretable.