Decadal to millennial cyclicity in varves and turbidites from the Arabian Sea: hypothesis of tidal origin
Decadal to millennial cyclicity in varves and turbidites from the Arabian Sea: hypothesis of tidal origin
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DOI：
10.1016/s0921-8181(02)00122-4
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发表时间：
2002-11-01
影响因子：
3.9
通讯作者：
von Rad, U
中科院分区：
文献类型：
--
作者：
Berger, WH;von Rad, U
我们分析了全新世晚期的记录，该记录长达近 5000 年，由沉积在巴基斯坦附近最低氧区 (OMZ) 的变化沉积物组成。我们搜索了 varve 厚度系列（“varve”循环）、varve 厚度异常大的偏移（“搅动”循环）和浊积岩丰度（“浊积岩”循环）的周期性。我们在以下三种系列中的一种或几种中发现了以下高频旋回（周期在10到100年之间）：近12.4、14-15、16.8、18.6（强，搅动），25-26（强，浊积岩），29-31（强，搅动），39（varve），44（强，浊积岩）， 51-54（强烈，激动），56（强烈， varve）、64 年（强、浊积岩）、69 年、77 年（强、浊积岩）、82 年（非常强、搅动）和 95 年（强、varve）。低频周期集中在 99-115、125（非常强，varve）、164、177、202、242-255（强、搅动和浊积岩）、280（强、varve；加倍、浊积岩）、340-370 和 460-490 年。一些水藻厚度的周期与浊积岩频率的周期（12.3、14-15、25-26、245-255 年）相匹配，但光谱之间的相似性并不显着。然而，作为一个整体，检测到的周期序列（通过自相关和标准傅里叶分析）似乎包含大部分基本潮汐周期 4.425（月球近地点周期）和 9.3 年（月球半交点周期）的倍数。通过测试整数倍数和分数的三个分箱频谱以及整数节拍结构来支持这种印象。因此，我们认为检测到的周期性的很大一部分可以归因于潮汐作用。我们的记录还包含先前根据冰期格陵兰冰记录报告的 1470 年周期存在的证据。格陵兰循环的主要谐波可以与在变化的沉积物中看到的周期模式联系起来。我们假设潮汐作用产生了这个周期，其之所以如此长的原因是要求最大潮汐活动必须落入一个狭窄的季节窗口内才能在地质上有效。 (C) 2002 Elsevier Science B.V. 保留所有权利。
We have analyzed a Late Holocene record, almost 5000 years long, consisting of varved sediments deposited in the oxygen-minimum zone (OMZ) off Pakistan. We searched for cyclicity in the series of varve thickness ("varve" cycles), of unusually large excursions in varve thickness ("agitation" cycles), and of abundance of turbidites ("turbidite" cycles). We found the following high-frequency cycles (periods between 10 and 100 years) in one or several of the three types of series as follows: near 12.4, 14-15, 16.8, 18.6 (strong, agitation), 25-26 (strong, turbidite), 29-31 (strong, agitation), 39 (varve), 44 (strong, turbidite), 51-54 (strong, agitation), 56 (strong, varve), 64 (strong, turbidite), 69, 77 (strong, turbidite), 82 (very strong, agitation), and 95 years (strong, varve). Low-frequency cycles center around 99-115, 125 (very strong, varve), 164, 177, 202, 242-255 (strong, agitation and turbidite), 280 (strong, varve; doubled, turbidite), 340-370 and 460-490 years. Some cycles of varve thickness match the cyclicity of turbidite frequency (12.3, 14-15, 25-26, 245-255 years) but similarities between spectra are not striking. Taken as a whole, however, the sequence of cycles detected (by autocorrelation and standard Fourier analysis) seems to contain a large proportion of multiples of the basic tidal cycles 4.425 (lunar perigee cycle) and 9.3 years (lunar half-nodal cycle). This impression is supported by testing the three binned spectra for whole-number multiples and fractions as well as whole-number beat structure. We therefore propose that a large proportion of the cyclicity detected can be ascribed to tidal action. Our record also contains evidence for the presence of the 1470-year cycle previously reported from the glacial-age Greenland ice record. The main harmonics of this Greenland cycle can be tied to the pattern of periods seen in the varved sediments. We hypothesize that tidal action produces the cycle, and that the reason for its great length is the requirement that maximum tidal activity has to fall into a narrow seasonal window to be geologically effective. (C) 2002 Elsevier Science B.V. All rights reserved.