碳酸盐旋回地层研究现状

碳酸盐旋回地层研究现状陈代钊（中国科学院地质研究所）地层纪录中的韵律性很早就引起了人们的关注，本世纪６０年代此项研究曾形成了一个小的热潮（Ｍｅｒｉａｍ，１９６４）［１］，但直到７０年代随着ＤＳＤＰ计划的实施，通过大量深海沉积纪录与米兰柯维奇气候韵律的...     

旋回地层学研究现状和新进展

旋回地层学作为一门独立的地层分支学科诞生于20世纪80年代,它以米兰科维奇天文轨道旋回为理论基础,以露头剖面、岩心等为研究对象,应用地球化学、光谱分析和时间序列分析等方法,研究天文轨道参数周期性变化在地层记录中的沉积响应.旋回地层学的基本地层单位米级旋回,相当于层序地层概念体系中的准层序,二者相互联系又存在差异."天文地质年代表"的提出和"国际地质年表"把天文轨道因素作为确定地质年代的一种重要方法,突出显示旋回地层学在定量确定地质年代方面的优势.近年来在地层记录中识别出时间分辨率更高的亚米兰科维奇旋回信号不仅是该学科最新进展,也是沉积学和地层学新的生长点.     

港东油田二区一断块高分辨率层序地层

高分辨率层序地层为建立高分辨的年代地层格架提供了一种有效的方法。港东油田二区一断块的储油层段主要为明化镇组下段曲流河沉积 ,通过运用沉积基准面原理对研究区内岩芯、测井资料的综合分析 ,识别出了曲流河沉积短期、中期地层旋回及其特征 ,短期地层旋回可能主要为河流作用形成的自旋回 ,无法确定与基准面变化的关系 ;中期地层旋回则完全是由沉积基准面变化形成 ,由不同类型的短期地层旋回构成 ,并发现不同的短期旋回出现在中期基准面旋回的不同位置 ,相同的微相在中期基准面旋回的不同位置具有不同的结构特征 ,弄清了中期基准面对作为主要储层的河道砂体的侧向连通性和内部非均质性的控制作用。根据这些特征 ,建立了工区二维高分辨率地层对比格架 ,并在此基础上对工区的储层分隔间进行了预测     

基准面旋回与沉积旋回的对比方法探讨

建立高精度的等时地层格架、定量研究储层成因单元划分对比、为油田开发小尺度流动单元提供基础,是开发地质研究的目标,本文指出目前面临两种储层划分对比方法-基准面旋回与沉积旋回,说明高分辨率层序划分对比的精髓是基准面旋回的对比,大庆油田储层描述对比的关键是沉积旋回的对比,从而阐述了二者在划分对比的原则、方法及理论上异同。研究表明,这两种地层划分方法的理论基础皆为旋回 (自旋回或异旋回 )和层次、研究目标皆为地层格架及沉积地层单元的规模尺度。基准面旋回对比关键是旋回的组合分析,其方法在湖相 (异旋回 )中可行,在冲积相 (自旋回 )中基准面旋回划分困难,而且随意性很大;沉积旋回对比方法在河湖相对比中存在穿时现象,但应用广泛。不同级别基准面周期性的运动,使沉积旋回在周期性和规模上产生不同,形成层序的分级现象,所以说,沉积旋回和基准面旋回地层对比方法是从不同的角度对同一事物进行研究。进而讨论了旋回对比的两个关键问题-层次和界面,提出了存在的问题,对流动单元和剩余油分布研究具重大意义。     

雾迷山旋回层:米级旋回的一个特例

作为地层堆积作用的"间断—加积旋回"机制的产物,"米级旋回"的完整定义代表了旋回地层学进入地层学实践的主流,因为米级旋回的形成可以运用米兰柯维奇旋回得到合理的解释。作为特殊的环潮坪型碳酸盐米级旋回——"雾迷山旋回层",因其罕见的近似对称的相序组构可以替代"洛菲尔旋回层(Lofer cyclothem)",成为旋回性碳酸盐沉积作用的表征,从而进一步成为前寒武纪巨厚叠层石碳酸盐序列中地层结构的标志。因此,"雾迷山旋回层"不但作为碳酸盐米级旋回的特别实例,而且蕴含着较为明显的米兰柯维奇旋回属性,同时进一步说明了米级旋回可以成为层序地层学概念体系中欠完整性的"副层序"的替代物。     

旋回地层学：地层学解读时间的第三里程碑

围绕对地质时间的认识,地层学取得了从岩石地层学、生物地层学和旋回地层学3次里程碑性的重大进展.以生物地层学为基础并与放射性同位素定年技术相结合建立的、以百万年为计时单位的地质年代表既创造了地层学的辉煌,也在一定程度上降低了地质学对精确数字定年的不懈追求和为人类社会服务的功能.本文以时间为线索,简要回顾了地层学解读时间的漫长过程,阐述了旋回地层学概念的起源、形成和发展,以及旋回地层学与层序地层学在科学目标、研究内容和研究方法上的异同.以广西晚泥盆世弗拉期-法门期之交海相碳酸盐地层为例,从理论与实践的结合上剖析了旋回地层学的研究方法以及在岩石地层学和生物地层学基础上构建高分辨率,并能与人类社会时间接轨的地质时间坐标的广阔前景和科学意义.     

恭城地区法门期地层高频旋回的划分及特征

文章以恭城县西岭乡挖掘沟村晚泥盆世法门期地层为例,应用层序地层学理论,进行高频旋回地层研究,将其详细地划分出五级旋回９４个,四级旋回３６个,初步总结了各种旋回地层的空间叠复关系,强调指出高频旋回地层出现的原因很可能与地球轨道变化周期有关。     

杭嘉湖平原第四纪地层高精度对比方法研究

通过标准孔古气候旋回宏观识别标志的研究,并运用高分辨率层序地层理论,解决了杭嘉湖平原第四纪地层划分和200余个钻孔的等时对比问题,在此基础上制作了高精度对比的剖面图及准瞬时岩相古地理图,为研究杭嘉湖平原第四纪地层划分、古地貌变迁提供了更为精确的资料。运用“基准面旋回”作为层序地层的划分依据,以古土壤层及其可与之对比的暴露面和河流冲刷面为边界,将平原第四系划分为9个亚层序,并发现亚层序与气候旋回呈耦合关系。     

层序地层旋回地层与多重地层划分

以现代地层学理论为指导，分析了多重地层划分单位的涵义，属性及划分标准；重点探讨了层序地层，旋回地层与传统地层单位的关系；以京西，冀北古生界为例说明了层序地层，旋回地层及多重地层划分理论的具体应用。     

层序地层旋回地层与多重地层划分———以京西冀北下古生界为例

以现代地层学理论为指导，分析了多重地层划分单位的涵义、属性及划分标准；重点探讨了层序地层、旋回地层与传统地层单位的关系；以京西、冀北古生界为例说明了层序地层、旋回地层及多重地层划分理论的具体应用     

地球轨道旋回沉积节律研究进展——兼论轨道旋回的沉积学特征、年代学意义和研究方法

地球轨道旋回是古代沉积记录中常见的由地球轨道参数变动控制的沉积节律,它不仅自身表现显著的节律性,而且通过反馈体系强烈影响着沉积作用。同时,轨道旋回节律在不同的沉积背景下以不同的沉积特征显现和规则性叠加。地球轨道旋回赋有的规则频率变化特征又使其具有年代学意义和应用价值,它是天文地质学、地层学及沉积学研究的重点内容。根据国内外资料综述了这些方面的研究进展,并探讨了地球轨道旋回的研究方法。     

从准层序到米级旋回——层序地层学与旋回地层学相互交融的纽带

层序地层学的基本单位是层序。准层序和准层序组构成了层序的基本结构单元,它们在层序内有规律的空间叠置样式是识别体系域的客观标准。准层序被定义为以海泛面为界的向上变浅序列,但是准层序是一个比较松散的概念,存在问题是对其成因机制研究不足。米级旋回作为旋回地层学的基本单位,定义为数厘米至数米厚的向上变浅的岩相序列,是高频率海平面升降变化的产物,其形成时限为相应的米兰柯维奇天文旋回周期。作为旋回地层学的基本单位,米级旋回以其明确的沉积学涵义和有规律的天文成因机制,是对层序地层学概念体系中的"准层序"的良好补充,对其进行深入研究具有重要的理论意义和应用价值。从准层序到米级旋回这一概念体系的演变,代表了层序地层学与旋回地层学相互交融的纽带。最后介绍旋回地层学的最新进展亚米兰柯维奇旋回,它对精确数字定年具有重大意义。     

Whither stratigraphy?

There have been three revolutions in sedimentary geology. The first two began in the 1960s, consisting of the development of process-response sedimentary models and the application of plate-tectonic concepts to large-scale aspects of basin analysis. The third revolution, that of sequence stratigraphy, began in the late 1970s and helped to draw together the main results of the first two: the knowledge of autogenic processes learned through facies analysis, and the understanding of tectonism implicit in the unravelling of regional plate kinematics. Developments in the use of seismic-reflection data and the evaluation of a hypothesis of global eustasy provided considerable stimulation for stratigraphic research.Current developments in the field of sequence stratigraphy are focusing on three areas. (1) Elaboration of the sequence-architecture models for various configurations of depositional environment and sea-level history. (2) Exploration of various mechanisms for sequence generation, especially tectonism and orbital forcing. (3) Attempts to improve the level of precision in stratigraphic correlation and to refine the geological time scale, as a means to test the model of global eustasy.The growth in the power of computers and our knowledge of physical and chemical processes has led to the evolution of an entirely new way of evaluating earth history, termed quantitative dynamic stratigraphy. Mathematical modelling and numerical simulation of complex earth processes are now possible, and require the collection and integration of a wide array of quantitative and qualitative data sets. Applications include the study of the geodynamic evolution of sedimentary basins, modelling of stratigraphic sequences and global climates, studies of Milankovitch cycles (cyclostratigraphy) and simulation of fluid flow through porous media. The Global Sedimentary Geology Program has brought many of these areas of study together in multidisciplinary, global-scale studies of the sedimentary history of the earth. The results of these studies have wide application to many problems of importance to the human condition, including the past history of global climate change and other environmental concerns. The study of stratigraphy is at the centre of the new view of the earth, termed earth-systems science, which views earth as an ‘organic’ interaction between the lithosphere, biosphere, hydrosphere, and atmosphere.     

天文古气候理论及其进展—从米兰柯维奇到贝尔杰

扼要介绍了天文古气候学的创立和发展简史。太阳是地球大气运动的第一驱动力，地球气候的长期演变在很大程度上受到入射太阳辐射变化的影响。入射太阳辐的变化主要和三个地球轨道参数有关，即地球绕太阳运行的椭圆轨道偏心率，地球自转轴倾角及岁差。太阳辐射的长期振荡主要集中在与这三个参数有关的频率上，这些频率通常被称为米兰柯维奇频率，数值模拟和地学记录都证实地质时间尺度的古气候的演化大多位于米兰柯维奇频率带上。     

Platform-to-basin correlation by high-resolution sequence stratigraphy and cyclostratigraphy (Berriasian, Switzerland and France)

Based on detailed analyses of facies evolution and stacking pattern of Berriasian carbonate-dominated sections in the Swiss Jura Mountains, the Swiss Ultrahelvetic and the French Vocontian Trough, a high-resolution platform-to-basin correlation is proposed. Biostratigraphical tie points are furnished by ammonites, dinoflagellates, calpionellids, and ostracod-charophyte assemblages. The hierarchical stacking of small-scale depositional sequences reflects Milankovitch cyclicity: sequences corresponding to the 20-, 100-, and, locally, 400-ka orbital cycles can be identified. Elementary (20 ka) sequences on the platform generally consist of one bed of shallow subtidal to intertidal, high- or low-energy carbonate facies, whereas on the slope and in the basin they are commonly developed as limestone-marl couplets. These elementary sequences group into small-scale composite sequences reflecting the first orbital eccentricity cycle (100 ka), which in turn build up large-scale (3rd-order) composite sequences. One 3rd-order sequence has been analysed in detail: according to the cyclostratigraphic interpretation, it took ?2 Myr to form, which is in accordance with the duration of the corresponding ammonite subzones. Sequence-stratigraphic and cyclostratigraphic platform-to-basin correlation shows that for about 900 ka the platform was exposed or only partly flooded, whereas on the slope and in the basin, lowstand deposits with channel fills and slumps accumulated. With rising sea level, accommodation space gradually increased on the platform and a thickening-upward sequential pattern with transgressive facies developed, while in the basin the facies still had lowstand characteristics with thick and nodular limestone beds. This situation lasted about 700 ka. The following 300 ka were characterized by sediment starvation and increased bioturbation on the platform, and by more marly, transgressive sediments on the slope and in the basin. The maximum-flooding phase is more or less isochronous on the platform and in the basin, although the surface with the best-developed maximum-flooding features may be displaced by one or two small-scale composite sequences because of superimposed high-frequency sea-level fluctuations, and/or local variations in substrate morphology and sediment distribution. Third-order highstand conditions prevailed for only about 100 ka. The combination of cyclostratigraphy and high-resolution sequence stratigraphy, constrained by good biostratigraphy, is thus a powerful tool for detailed stratigraphical correlation over long distances and from one sedimentary environment to another.     

From platform to basin to swell: orbital control on sedimentary sequences in the Oxfordian, Spain

Climatic, oceanographic and ecological changes that control the formation and deposition of sediment in shallow and deep depositional environments commonly occur with periodicities of a few 10 000 years. Consequently, in order to interpret sedimentary sequences in the geological past, high time resolution is required. This is best obtained by cyclostratigraphy. Three sections have been studied in the Oxfordian of north-eastern Spain: one represents a shallow, siliciclastic-carbonate platform with repetitive subaerial exposures, one an intraplatform basin with sponge bioherms, and one a swell where iron ooids and glauconite formed. The platform section displays a well-defined stacking pattern of depositional sequences; the deeper-water sections are well dated by ammonites. The correlation between the three sections is a best-fit solution integrating biostratigraphy, sequence stratigraphy and cyclostratigraphy. It is concluded that the small-scale depositional sequences formed in tune with the 100-ka orbital eccentricity cycle. An additional factor was differential subsidence that ruled basin morphology.     

Orbital forcing recorded in subtidal cycles from a Lower Miocene siliciclastic–carbonate ramp system (Central Italy)

Metre-scale siliciclastic–carbonate cycles are the basic depositional motif of the lower Miocene Guadagnolo Formation outcropping in the central Apennines. The mechanisms which formed the mixed-lithology cycles are still a matter of debate. The mixed siliciclastic–carbonate system discussed in this paper provides a new case study to illustrate the role of orbital forcing in controlling the facies evolution and cyclic stacking of small-scale sequences deposited on the outer sector of a ramp. Two sections are discussed that display mixed siliciclastics and carbonates arranged in upward-shallowing cycles. Each cycle shows an upward decrease in the terrigenous input and a parallel increase in benthic fauna. Time-series analyses indicate the cyclic carbonate-terrigenous pattern to be largely controlled by orbital forcing in the Milankovitch frequency band. Coupling of climate change and sea-level fluctuations in tune with orbital cycles are proposed as driving mechanisms.     

辽河新开油田开38、39井区沙河街组层组划分

根据层序地层学理论,综合应用录井、测井、露头、岩芯等资料作了开38、39井区沙河街组地层成因单元分析及沉积旋回特征,进行了层组划分对比。通过分析得出研究区发育的三种沉积体系及分布。     

米兰科维奇旋回时间序列分析法研究进展

时间序列分析法是米兰科维奇旋回（米氏旋回）研究的主要方法。它利用数学变换对地层数据序列进行定量分析,从而识别地质记录中天文驱动形成的旋回信号,为年代校准、地层划分和古气候研究等提供重要依据。针对米氏旋回研究中时间序列分析法的主要步骤,分别从地层序列的数据类型、天文检验及天文调谐等三方面,阐述了现有方法的基本原理,并总结了其优势和局限性。在基于时间序列分析的米氏旋回研究中,不同地层序列数据对天文轨道驱动和非天文噪声的响应具有差异性,综合利用多种数据指标中蕴含的地质信息有助于减小旋回分析中的不确定性;近年来涌现的新型天文检验和调谐方法促进了米氏旋回分析向定量化方向发展,但这些新方法仍需要进一步验证及改进。未来的工作中,地层数据序列的定量评价、多数据类型的信息优化等方面仍值得深入研究;面对多种时间序列分析方法,有效整合现有方法的同时,也需要引入新方法和新思路。     

认识偏心率周期的地层古气候意义

介绍了偏心率周期在地层和古气候研究方面的新发展.现有地球轨道模式对250Ma以来的轨道运算误差能控制在0.2%之内, 使基于偏心率周期来划分地层年代成为可能.新的国际标准地层年代表以405ka长偏心率周期为基础来划分主要地层界线.新生代将包括E1-E162偏心率长周期, 底界年龄(65.5±0.3) Ma.这一地层年代表的建立, 标志着轨道地层学时代的到来.偏心率的100ka短周期和405ka长周期在诸多地质记录中都有反映, 特别是来自深海钻孔的物理化学古气候指标.很多古气候重大事件往往发生在偏心率周期的弱振幅时期, 表明弱振幅时期易受其他因素的干扰影响, 这些因素包括碳储库、冰盖和海平面变化、电磁场, 以及区域构造重组等等.越来越多的研究发现碳同位素在偏心率周期上与地球轨道驱动相关, 且常领先于氧同位素的变化, 表明热带碳循环过程是影响全球气候变化的关键因素之一.