Reliability of Lunar orbital periods extracted from ancient cyclic tidal rhythmites
Reliability of Lunar orbital periods extracted from ancient cyclic tidal rhythmites
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DOI：
10.1016/0012-821x(96)00063-5
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发表时间：
1996-06-01
影响因子：
5.3
通讯作者：
Archer, AW
中科院分区：
文献类型：
--
作者：
Archer, AW
从地质记录中提取的古代潮汐周期对约束和校准地月系统演化的理论模型是有用的。对包含这种潮汐周期性的岩石（称为周期韵律岩）的分析往往集中在长系列上，并集中在更明显的周期上。例如，小潮-春季周期是最广泛讨论的，这些信息可以从横向吸积潮束和垂直吸积潮纹层内测量的底形厚度系列中可靠地提取出来。其他月球轨道数据也被编码在周期韵律层中，但是这些额外的信息在地月模型中的应用要少得多。在这里，形成良好的周期韵律的短片段进行检查，以确定如何可靠的各种潮汐周期可以通过谐波分析提取。这里分析的韵律系列表现出良好的小潮-大潮期，也表现出突出的两周不等或连续大潮高度的变化。这种不平等是有关的椭圆性质的月球轨道（economist月），它表明，这一时期也可以可靠地提取周期rhythmite.Tropical期间，反映了变化的月球decades发生在一个热带的一个月，也有报道从周期rhythmites。与会合周期和周期不同，从某些周期韵律中提取的表观热带周期并不总是与预期值准确对应。只有在少数情况下，才能从周期性潮汐韵律数据的短片段中可靠地提取出这一周期。这一时期通常只在韵律层中编码得很差，因为：（1）它往往被更高振幅的会合周期所掩盖，（2）它在主要的半日潮汐系统中没有很好的表达。从元古宙和古生代中选择的样本往往在地质时代的特定间隔中更常见。这些间隔的特点是冰川海平面变化通量，在某些情况下，由独特的大陆配置。了解这些基本控制节奏石的发生应有助于发现更多的例子。
Ancient tidal periods extracted from the geologic record are useful to constrain and calibrate theoretical models of the evolution of the earth-moon system. Analysis of rocks that contain such tidal periodicities, termed cyclic rhythmites, have tended to concentrate on long series and have focused on the more obvious periods. For example, neap-spring periods have been the most widely discussed; such information can be reliably extracted from bedform thickness series measured within laterally accreted tidal bundles and vertically accreted tidal laminae.Other lunar orbital data is also encoded in cyclic rhythmites; however this additional information has been much less extensively applied to earth-moon models. Herein, short segments of well-formed cyclic rhythmites are examined to determine how reliably the various tidal periods can be extracted via harmonic analysis. Rhythmite series analyzed here exhibit well-formed neap-spring tidal periods and also exhibit a prominent fortnightly inequality or a variation in the height of successive spring tides. This inequality is related to the elliptical nature of the lunar orbit (anomalistic month) and it is demonstrated that this period can also be reliably extracted from cyclic rhythmites.Tropical periods, which reflect the changing lunar declination that occurs during a tropical month, have also been reported from cyclic rhythmites. Unlike synodic and anomalistic periods, the apparent tropical periods extracted from some cyclic rhythmites do not always accurately correspond to the expected values. In only a few cases can this period be reliably extracted from short segments of cyclic tidal-rhythmite data. This period is commonly only poorly encoded in rhythmites because: (1) it tends to be masked by higher amplitude synodic periods, and (2) it is not well expressed within predominantly semidiurnal tidal systems.Samples selected from the Proterozoic and Phanerozoic tend to be more common during specific intervals of geologic time. These intervals were characterized by glacio-eustatic flux and, in some cases, by unique continental configurations. Understanding these basic controls on rhythmite occurrences should aid in the discovery of additional examples.