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1.
华南上奥陶统宝塔组天文年代格架及其地质意义 总被引：1，自引：0，他引：1
对华南四川盆地及周缘地区的四川省南江县桥亭剖面、重庆市南川区三泉剖面和贵州省习水县良村剖面上奥陶统宝塔组高分辨率磁化率(MS)数据进行了旋回地层学分析,识别出405 ka长偏心率、100 ka短偏心率、30 ka斜率和20 ka岁差沉积旋回,其中偏心率和岁差旋回信号最强。利用405 ka长偏心率旋回进行天文调谐后得出三条剖面宝塔组的沉积时限分别为4.17 Ma、5.64 Ma和5.05 Ma,平均沉积速率分别为7.67 m·Ma-1、4.68 m·Ma-1 和6.37 m·Ma-1,呈现出从北往南沉积时限变长,沉积速率变小的趋势,指示了北部接受沉积时间要比南部更晚,海侵从南向北推进。良村剖面宝塔组中所产牙形石Hamarodus brevirameus带和Protopanderodus insculptus带的延续时限分别为3.62 Ma和1.43 Ma;桥亭剖面三叶虫Niuchangella angustilimbata间隔带、Dislobosaspis xixiangensis延限带和未建带的延续时限分别是2.83 Ma、0.41 Ma和0.81 Ma。 相似文献
2.
新生代至前寒武纪海相和陆相沉积记录显示,405 ka长偏心率周期贯穿整个地质历史,从陆地季风降水到大洋碳循环都有表现,是地球表层系统中水循环和碳循环的基本节拍,不仅可用作基本的地质计时单位,还是低纬过程的重要特征之一.现有的地质记录表明405 ka长偏心率周期存在被隐匿或被破坏的现象,火山岩浆活动释放CO2、生物圈重大变革和冰盖增大事件等都可以造成405 ka长偏心率周期的隐匿,这为揭示地球表层系统重大变化提供了一个新的切入点.通过研究405 ka长偏心率周期的演变特征和破坏机制,可望穿越暖室和冰室期,建立起完整的气候演变理论.最后对我国开展天文旋回研究力争走到世界前列提出了建议和展望. 相似文献
3.
认识偏心率周期的地层古气候意义 总被引：15，自引：0，他引：15
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. 相似文献
4.
旋回地层学的研究对象由海相地层逐渐转移到陆相深水地层.为了探究通过旋回地层学研究方法在陆相浅水湖盆建立高频层序格架的可能,采用频谱分析、天文调谐、“米氏”沉积速率拾取等手段对东海陆架盆地西湖凹陷黄岩区渐新统坳陷湖盆的岩相敏感曲线-GR数据开展研究.频谱分析结果显示黄岩区花港组受405 ka长偏心率周期（E）、121 ka和97 ka短偏心率周期（e）、28 ka斜率周期（O）以及约22 ka岁差周期（P）的调控.在浅水湖泊环境的富泥区,以La2004天文解决方案给出的65°N平均日照序列为参照进行天文调谐,建立了浮动天文年代标尺;在浅水三角洲环境的富砂区,通过滑动窗口频谱分析得到“米氏”沉积速率曲线,结合锆石铀铅测年资料的校验和岩石组合类型联合约束,完成高频层序格架划分.研究表明:黄岩区花港组持续时间约为10.9 Ma,可识别出27个405 ka长偏心率周期,根据偏心率滤波曲线和日照量各级次包络面的对应关系共划分11个四级层序,27个五级层序,分别对应着0.8~1.6 Ma和0.4 Ma的基准面旋回,每个旋回在沉积速率曲线上表现为高?低?高的特征.本次研究提供了一种利用“米氏”沉积速率进行高频层序格架搭建及层序?时间单元拾取的新方法,拓宽了旋回地层学的应用范围. 相似文献
5.
新近纪海相生物地层事件年龄新编 总被引：14，自引：2，他引：12
介绍新近纪海相生物地层研究的新进展。2004年新的"国际地质年代表"以405ka偏心率长周期为基础来划分新近纪的主要地层界线,标志着轨道地层学时代的到来。新生代包括E1—E162偏心率长周期,底界的年龄为65.5±0.3Ma,其中新近纪有E1—E58周期,底界年龄为23.03Ma,并且根据天文调谐得出一系列新的古地磁年龄和生物事件年龄。由于这些新年龄,特别是接近新近纪底部的年龄与早期结果相差0.5Ma或更大,所以将其汇总介绍,以求与当前国际研究保持同步衔接,增强海洋新近纪高分辨率地层工作的准确性。 相似文献
6.
山东东营凹陷新生代天文地层表简介 总被引：6，自引：0，他引：6
YAO Yi-min ) XU Dao-yi ) ZHANG Hai-feng ) HAN Yan-ben ) ZHANG Shou-peng ) YIN Zhi-qiang ) LI Bao-li ) HE Qing-fang ) BIAN Xue-mei ) ) Geological Scientific Research Institute of Shengli Oilfield Company SINOPEC Dongying ) Institute of Geology China Earthquake Administration Beijing ) National Astronomical Observatories Chinese Academy of Sciences Beijing 《地层学杂志》2007,(Z2)
综合山东东营凹陷郝科1等6口井的天文地层研究结果提出"东营凹陷新生代天文地层表",表中列出的是"国际地层表(2004)"、"中国区域年代地层表(2000)"和0—65Ma期间天文偏心率405ka周期编号以及东营凹陷孔店组(顶部)至平原组各组的年龄以及东营凹陷新生代51Ma以来3个大的地层不整合:1)沙河街组二段下部,大约33.8—33.4Ma期间405ka周期振幅不明显、100ka周期较强,与南大西洋33.4—33.7Ma和热带太平洋33.6—33.7Ma期间沉积物中显著转折等特征可作对比;2)东营组-馆陶组界线上下,东营组三角洲顶面最后萎缩时间约为24.467Ma,推测由此至渐新世末(23.03Ma),大约近1.5Myr期间本区没有大的湖泊,而是冲积—河流相沉积,中新世初(23.03Ma)快速隆起,直到约18—16Ma开始馆下段的上部沉积,这一区域性角度不整合面形成大约持续5—7Myr;3)上新统-更新统界线上下,根据本区东辛2-4井古地磁和天文地层研究,测出布容、松山、高斯和吉尔伯特等4个极性时,求出2.546Ma—1.806Ma期间[明上(上)亚段顶]可能沉积并剥蚀过的地层厚度为129m;1.806—0.908Ma期间,因构造活动本区上升成为高山,第四系平一段底部形成了大的不整合面。 相似文献
7.
显生宙沉积旋回会受到地球轨道参数偏心率、地轴斜率和岁差的周期性变化(米兰科维奇旋回)的控制,但目前对前寒武系的相关研究较为薄弱。天津蓟县剖面中元古界洪水庄组-铁岭组为一套潟湖-潮坪相沉积,主要呈砂岩-页岩互层的韵律性产出。为探索这种岩性韵律是否与轨道旋回有关,对其进行了高分辨率的岩性刻画,并以磁化率和伽马能谱数据作为古气候-古环境替代性指标,通过频谱分析等方法进行旋回地层学分析。结果表明各指标均记录了完整的米兰科维奇旋回。铁岭组一段下部由短偏心率、斜率和岁差控制的地层旋回厚度分别为1.2~1.5 m、0.4 m和0.17~0.19 m,其中0.1 m的半岁差周期也较明显;洪水庄组二段顶部由长偏心率、短偏心率、斜率和岁差控制的地层旋回厚度分别为1.1~1.8 m、0.34~0.54 m、0.14~0.16 m和0.08~0.09 m。以识别出的稳定长偏心率周期405 ka旋回对洪水庄组进行了天文年代校准,并估计出当时的短偏心率、斜率以及岁差周期分别为100 ka、22~24 ka和15 ka。在洪水庄组中记录的偏心率振幅变化周期为~2 Ma,比现今~2.4 Ma的周期略短。 相似文献
8.
针对应用常规方法进行高频层序划分和对比容易受人为因素影响,所建立的高级别层序地层格架具有多解性等问题,本文引入天文地层学中气候旋回受天文周期驱动的理论,选择涠西南凹陷WZ11-4N油田4口钻井中的流一段地层为研究对象,进行米兰科维奇旋回特征分析。对自然伽马数据进行频谱分析的结果显示,在不同钻井中,流一段地层主要受偏心率周期(401ka、125 ka和95 ka)控制。对该周期滤波分析后,选择控制流一段发育的主要米兰科维奇周期曲线,建立了该区的高分辨率天文年代标尺。最后以偏心率125 ka周期曲线作为6级层序划分的参考曲线,对流一段层序进行高频旋回地层划分与对比。在此基础上,最终实现高频地层格架下沉积相的精细对比。 相似文献
9.
Shallow lacustrine carbonate microfacies document orbitally paced lake-level history in the Miocene Teruel Basin (North-East Spain) 总被引：1，自引：0，他引：1
Results are presented of a detailed carbonate petrographic study of an Upper Miocene lacustrine mixed carbonate–siliciclastic succession in the Teruel Basin (Spain) with the aim of constraining lake‐level variability at different stratigraphic scales. Regular alternations of red to green mudstone and lacustrine limestone, termed the ‘basic cycle’, reflect lake‐level variations at the metre‐scale. In an earlier study, the basic cycle was shown to be controlled by the climatic precession cycle. Petrographic analysis made it possible to distinguish two main carbonate microfacies groups characteristic of very shallow transient and shallow permanent lake environments, respectively. In addition to the basic cyclicity, the microfacies analysis reveals lake‐level variations on a larger scale. As a consequence, the astronomical forcing hypothesis of the cyclicity in the Cascante section is explored further. A climate modelling study of orbital extremes indicates that high lake levels could relate to enhanced net winter precipitation and runoff during precession minima, consistent with Mediterranean geological data. Using this phase relationship, an astronomical tuning of the cycles is established starting from astronomical ages of magnetic reversal boundaries. Subsequently, successive basic cycles are correlated to precession minima. The tuning reveals an identical number of basic cycles in the Cascante section as precession‐related sapropel cycles in the deep marine succession at Monte dei Corvi (Italy), corroborating the precessional control of the basic cycles at Cascante. Lake‐level highstands in the large‐scale cycle identified by the microfacies analysis relate to maxima in both the ca 100 and 405 kyr eccentricity cycles, again consistent with Mediterranean geological data. Subtraction of the identified astronomically related (lake‐level) variations from the palaeoenvironmental record at Cascante indicates a shift to deeper and more permanent lacustrine environments in the upper half of the section. The cause of this shift remains unclear, but it may be linked to tectonics, non‐astronomical climate, long‐period astronomical cycles or autogenic processes. 相似文献
10.
A stratigraphical and palaeoenvironmental analysis with organic‐walled palynomorphs of the Bolderberg and Diest formations provides new insights in the depositional history during Miocene times at the southern border of the North Sea Basin. The Neogene transgression invaded Belgium from a north–northwestern direction and fully marine sediments were deposited in the northern part of Belgium. The age and the palaeoenvironment of the deposits at the very border of the southern North Sea Basin remained till a few decades ago incomplete. The recovered dinoflagellate cysts, acritarchs and green algae from the Bolderberg Formation in the Wijshagen Borehole indicate a marginal marine depositional environment during late Burdigalian and Langhian times in the eastern Campine area, in contrast to the deeper marine conditions prevailing to the north–northwest. The relative dating of the Bolderberg Formation confirms that maximum flooding occurred during Langhian to early Serravallian times. Deposition apparently took place during the Middle Miocene Climatic Optimum, and ended when the climatic deterioration set in at around 14 Ma. A hiatus spanning ca. 2 Ma separates the Middle Miocene Bolderberg Formation from the Upper Miocene Diest Formation in the eastern Campine area at the border of the North Sea Basin. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
11.
Metre‐scale cycles are a common feature in Precambrian and Phanerozoic shallow water carbonate successions, and astronomically forced changes in sea‐level (Milankovitch cycles) may have been an important driver controlling their deposition. Nevertheless, the degree to which potentially low amplitude astronomically paced sea‐level oscillations may have controlled carbonate accumulation in deep time is unclear. In this study, a stochastic model of carbonate accumulation demonstrates how metre‐scale exposure‐bound sequences can be generated under conditions of random sea‐level change. These sequences have characteristic durations close to Milankovitch cycles, despite the absence of any astronomical control on their formation. Metre‐scale sequences with sub‐Milankovitch (millennial‐scale) durations can also be generated by the model, potentially shedding light on the origin of sub‐Milankovitch sequences such as those recorded on the Middle Triassic Latemar platform of Northern Italy. Sensitivity tests demonstrate how shallow water carbonates may be very sensitive to weak (i.e. low amplitude) astronomically forced sea‐level oscillations. Notably, strong statistical evidence (P < 0·01) for astronomical cycles can be preserved in modelled successions even when astronomical forcing contributes <1% of the sea‐level variance on million year timescales. Taken together, metre‐scale cycles with Milankovitch‐scale durations in ancient carbonate successions may reveal very little about the amplitude, or even the existence, of astronomical forcing as a sea‐level driver. 相似文献
12.
根据秦皇岛石门寨亮甲山奥陶系剖面的化学地层和岩石地层特征,将亮甲山组(O1l)细分为下、中、上段。选取Fe/Ca、Ti/Ca作为古气候替代指标,开展时间序列分析。通过多窗谱法(MTM)和傅里叶变换法(FT),从Fe/Ca、Ti/Ca比值中共提取出两个明显的米兰科维奇旋回：长偏心率405 ka和短偏心率90 ka。基于长偏心率周期建立的天文年代标尺表明,亮甲山组沉积时长为6.2 Ma,平均沉积速率为14.68 m/Ma,其中亮甲山组下段(0.00~48.00 m)和中上段(48.00~91.00 m)的沉积速率分别为12.00 m/Ma和19.55 m/Ma;马家沟组下部的沉积速率为18.00 m/Ma。奥陶纪生物大辐射可能直接导致碳酸盐生产模式由以灰泥生产为主转变为以生物碎屑生产为主,并使亮甲山组下段与中上段之交碳酸盐沉积速率大幅增加。旋回地层分析显示,早、中奥陶世之交天文轨道周期变化引起的地球气候改变可能对奥陶纪生物大辐射有重要的调控作用。 相似文献
13.
《地学前缘(英文版)》2023,14(4):101558
We present a detailed magnetostratigraphic and cyclostratigraphic profile through the Riphean (Tonian) Katav Formation in the southern Urals. The study confirms the primary nature of the magnetization in these rocks. The cyclostratigraphic study identified several orbital periods including the 405 ka long eccentricity. This allows us to quantify the reversal frequency in the Katav and our estimates range of 7–12 reversals per million years. Based on our study, we identify an interval of magnetic field reversal hyperactivity in the Neoproterozoic interval. Age estimates for the Katav are contentious and range somewhere between 800 Ma and 900 Ma based on carbonate Pb-Pb ages and stable isotope correlations. The paleomagnetic poles obtained in this study of the Katav (and overlying Inzer) Formation do not fit anywhere on the Baltica apparent polar wander path between 1100 Ma and 900 Ma. Furthermore, they lie 90° away from the 900 Ma segment of the path. We tentatively estimate their age to be closer to 800 Ma and perhaps confirm a previously hypothesized pulse of rapid true polar wander between 825 Ma and 790 Ma. 相似文献
14.
Slah Boulila Bruno Galbrun Linda A. Hinnov Pierre-Yves Collin 《Sedimentary Geology》2008,203(1-2):54-63
High-resolution magnetic susceptibility (MS) analysis was carried out on a Lower Kimmeridgian alternating marl–limestone succession of pelagic origin that crops out at La Méouge (Vocontian Basin, southeastern France). The aim of the study was to characterize the strong, dm-scale sedimentary cyclicity of the succession at a very high resolution, and to analyze the cycles for evidence of astronomical forcing. From marl to limestone, MS varies progressively and closely tracks the highest frequency cyclicity corresponding to the basic marl–limestone couplets. Long-term wavelength cycling modulates the high-frequency cyclicity (couplets), and appears to be controlled by clay content. Spectral analysis of the MS record reveals the presence of the complete suite of orbital frequencies in the precession, obliquity, and eccentricity (95–128 ka and 405 ka) bands with very high amplitude of the precession index cycles originating from dm-scale couplets. 405 ka-eccentricity cycles are very pronounced in the MS maxima of the marl members of the couplets, suggesting eccentricity-driven detrital input to the basin. 405 ka-orbital tuning of the MS maxima further sharpens all of the orbital frequencies present in the succession. These results are similar to those of previous studies at La Méouge that used carbonate content observed in field. Our results are also in accordance with cyclostratigraphic studies in Spain and Canada that report dominant precession index forcing. By contrast, in the Kimmeridge Clay (Dorset, UK), obliquity forcing dominates cyclic sedimentation, with weaker influence from the precession index. Ammonite zone duration estimates are made by counting the interpreted precession cycles, and provide an ultra-high resolution assessment of geologic time. In sum, this study demonstrates the power of the MS as a proxy in characterizing the high-resolution cyclostratigraphy of Mesozoic sections, particularly in alternating marl–limestone successions, and for high-resolution correlation and astronomical calibration of the geologic time scale. 相似文献
15.
对珠江口盆地珠一坳陷惠州凹陷北部HZ0811井和惠陆低凸起HZ1811井中中新世-上新世的韩江组、粤海组和万山组自然伽马测井曲线进行频谱分析和小波分析, 识别出显著的米兰柯维奇沉积旋回.通过对短偏心率旋回进行高斯带通滤波, 建立了HZ0811井和HZ1811井的"浮动"天文年代标尺.两口井的万山组、粤海组和韩江组分别记录了35个、56个和64个短偏心率旋回, 据此估计出万山组沉积时限约为3.5 Ma, 粤海组沉积时限约为5.6 Ma, 韩江组沉积时限约为6.4 Ma.根据天文年代标尺计算出HZ0811井和HZ1811井韩江组-万山组的沉积速率, 结果表明沉积速率变化显示出明显的1.0 Ma和0.4 Ma的旋回性, 可能与长偏心率周期(1.0 Ma和0.4 Ma)控制的海平面变化有关. 相似文献
16.
上二叠统记录了地质历史时期最大规模的生物灭绝事件和最深刻的环境变化。对上二叠统的层序地层格架进行精细
描绘，建立高分辨率的地层序列，是深入了解此次事件及其演化的基础和关键。基于钻测井、岩心观测及地球化学分析测
试结果等资料综合分析，并运用小波分析技术，对黔西盘县上二叠统煤系进行了米氏旋回的识别和划分，结果表明，研究
区上二叠统煤系记录了稳定的米兰科维奇旋回，天文轨道周期对其沉积过程具有明显影响，由长、短偏心率、地轴斜率和
岁差周期引起的地层旋回厚度分别为16.06~17.24 m、5.39~5.70 m、2.11~2.15 m、1.12~1.21 m，长偏心率周期对地层中沉积
旋回的控制和影响最强。对长、短偏心率周期进行滤波分析后，建立了上二叠统煤系“浮动”天文年代标尺，为约束同沉
积火山事件层（Tonstein） 的形成及其持续时限提供了年代学依据。以区域等时对比效果明显的长偏心率旋回为标尺，并结
合旋回沉积序列、旋回界面特征等，将上二叠统煤系划分为4个三级层序，并进一步划分为16个四级层序（对应于中期旋
回），建立了研究区高频层序地层格架。 相似文献
17.
上二叠统记录了地质历史时期最大规模的生物灭绝事件和最深刻的环境变化。对上二叠统的层序地层格架进行精细
描绘,建立高分辨率的地层序列,是深入了解此次事件及其演化的基础和关键。基于钻测井、岩心观测及地球化学分析测
试结果等资料综合分析,并运用小波分析技术,对黔西盘县上二叠统煤系进行了米氏旋回的识别和划分,结果表明,研究
区上二叠统煤系记录了稳定的米兰科维奇旋回,天文轨道周期对其沉积过程具有明显影响,由长、短偏心率、地轴斜率和
岁差周期引起的地层旋回厚度分别为16.06~17.24 m、5.39~5.70 m、2.11~2.15 m、1.12~1.21 m,长偏心率周期对地层中沉积
旋回的控制和影响最强。对长、短偏心率周期进行滤波分析后,建立了上二叠统煤系“浮动”天文年代标尺,为约束同沉
积火山事件层（Tonstein） 的形成及其持续时限提供了年代学依据。以区域等时对比效果明显的长偏心率旋回为标尺,并结
合旋回沉积序列、旋回界面特征等,将上二叠统煤系划分为4个三级层序,并进一步划分为16个四级层序（对应于中期旋
回）,建立了研究区高频层序地层格架。 相似文献
18.
High resolution(939 samples)total organic carbon content(TOC)analyses were conducted on the Shuanghe Section of^152.6 m in the Changning area,Sichuan Basin.The sampling section was divided into two units considering the distinct-different deposit environment and sediments accumulation rate.The lower part(Unit 1)and the peer part(Unit 2)with high resolution sample spacing(0.08–0.4 m)enables the identification of the precession cycle in two sedimentary sequences with distinct different sedimentary accumulation rate.MTM Power spectral analyses on untuned TOC series reveals significant peaks exceeding above the 95%confidence level and shows that both Unit 1 and Unit 2 have recorded Milankovitch cycles of 405 kyr long eccentricity,short eccentricity,obliquity and precession.The floating astronomical time scale(ATS)was constructed on the Shuanghe Section in the Early Silurian(~439.673–444.681 Ma),and which was calibrated by 405 kyr long eccentricity cycles.The total duration of the Wufeng and Longmaxi shales is 5.01 Myr.The floating ATS used for estimating the duration of the graptolite zones and each stage in the study interval.Finally,we postulated two models that could verify the linkage between orbital cycle and organic accumulation.To make sure whether productivity or preservation is the main factor that under long eccentricity control,the phase correlation between the obtained filtered signal and the theoretical orbital solution should be made clear in the further research. 相似文献
19.
Edwin J. Anderson 《Sedimentology》2004,51(3):455-477
The lowermost Cretaceous (Berriasian) Sierra del Pozo Formation is divisible into metre‐scale cycles that are bundled in a four‐tiered hierarchy of cycles and cyclic sequences. At the smallest scale, sixth‐order cycles, thought to be the product of precessionally forced sea‐level fluctuations (c. 20 ka), average less than a metre in thickness, shallow upward and are bounded by surfaces where deeper facies abruptly overlie shallower facies. Bundles of sixth‐order cycles, called fifth‐order sequences, are recognized by two types of asymmetric patterns in facies distribution. First, more pronounced facies changes occur at sixth‐order cycle boundaries lower in a sequence, whereas smaller facies changes occur at cycle boundaries higher in a sequence. Secondly, subtidal marine limestones (i.e. biomicrites and biosparites) are the dominant facies lower in a cyclic sequence, whereas more restricted or shallower water facies (i.e. mud‐cracked microbial laminites, dolomites, shale and clay) are more predominant higher in a cyclic sequence. The bundling of sixth‐order cycles is explained as a product of periodic change (100 ka) in the eccentricity of the earth's orbit. The degree of orbital eccentricity modulates the magnitude of precessional sea‐level fluctuations, which in turn determine the relative facies contrasts at sixth‐order cycle boundaries. Larger scale fourth‐ and third‐order sequences are defined by similar patterns in facies contrast at successive sequence boundaries and by a change in predominant facies type from bottom to top. These patterns are explained as the product of 400 ka and 2 Ma periodic variations in the eccentricity of the earth's orbit. In summary, the strength of the precessional signal varies in consort with periodic changes in orbital eccentricity at three time scales producing a stacked hierarchy of cycles and sequences of cycles. Change in obliquity of the earth's axis may modulate the effects of the precessional signal and thereby modify patterns of preserved cyclic structure. This interpretation of cyclicity in the Sierra del Pozo section is markedly different from that of Jiménez de Cisneros & Vera (1993), who attributed all rock cycles to a single process (obliquity) even though the cycles they described varied in thickness from less than 1 m to more than 4 m. The cycles they described are shown here to be either precessional cycles or composite sets of precessional cycles (100 ka sequences). In this new hierarchical interpretation, ninety‐six 100 ka and twenty‐four 400 ka sequences are recognized, extending the time of deposition of the Sierra del Pozo section to more than 9·6 Ma. 相似文献
20.
YIN Zhi-qiang ) HAN Yan-ben ) XU Dao-yi ) YAO Yi-Min ) HAN Yong-gang ) ) National Astronomical Observatories Chinese Academy of Sciences Beijing ) Institute of Geology China Earthquake Administration Beijing ) Geological Scientific Research Institute of Shengli Oilfield Company SINOPEC Dongying 《地层学杂志》2007,(Z2)
地球轨道要素的变化已作为确定地质年表的一种重要依据。应用地球轨道参数变化理论计算值来进行小波分析,结果清楚地展示出偏心率值约100ka、405ka、1Myr和2.3Myr等周期成份的随时间变化特征,100ka和405ka周期的振幅强度的变化成反相位关系,2.3Myr周期对100ka和405ka周期成份有调制作用。0—51Ma范围内变化较为稳定的地球轨道偏心率值的变化分析可以为地质年龄的划分和对比提供一定的参考。 相似文献