The mapping of shallow upper mantle discontinuities using teleseismic P-wave autocorrelation

IF 1.3 4区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Earth System Science Pub Date : 2024-07-12 DOI:10.1007/s12040-024-02338-8

Suman Basak, Alolika Chakraborty, Kajaljyoti Borah

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引用次数: 0

Abstract

Crust and upper mantle discontinuities play a key role in understanding continental formation and evolution. The most prevalent seismic techniques, like receiver function, surface wave tomography, etc., face problems of multiples from shallow crustal discontinuities and low vertical resolution, respectively, which makes it difficult to image deeper discontinuities. To get the better of these complications and image the deeper discontinuities with greater accuracy, the P-wave autocorrelation method has been used for the teleseismic data recorded at Hyderabad station (HYB) in south India. This method has efficiently identified the major shallow upper mantle discontinuities down to 250 km depth. The Moho, mid-lithospheric discontinuity, Hales discontinuity, lithosphere–asthenosphere boundary and Lehmann discontinuity were observed at 30.37, 92.17, 123.43, 140.50 and ~201 km, respectively. We also achieved a very high vertical resolution (<0.6 km) for all the shallow upper mantle discontinuities. Further, we also proposed an iterative method to calculate the \({v}_{p}/{v}_{s}\) ratio of the crust, using the arrival times of Moho reflected \(2p\) and \(p+s\) phase. Unlike other seismic methods, this iterative method is independent of any constraint on \({v}_{p}\) and \({v}_{s}\). The \({v}_{p}/{v}_{s}\) is found to be 1.744, suggesting the crust beneath HYB is felsic in nature.

Research highlights

Shallow upper mantle discontinuities imaged beneath Hyderabad (HYB) station with high vertical resolution (<0.6 km)
A thin crust (30 km) and felsic composition (\({v}_{p}/{v}_{s}\sim 1.744)\) beneath HYB.
Distinct MLD and LAB signatures at ~92 km and ~140 km, respectively, beneath HYB.
A diffused Hales discontinuity (123 km) and Lehmann Discontinuity (201 km) are also observed.

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利用远震 P 波自相关性绘制浅层上地幔不连续面图

摘要地壳和上地幔不连续面在了解大陆形成和演化方面起着关键作用。目前最流行的地震技术，如接收函数、面波层析成像等，分别面临着浅层地壳不连续面的多重性和垂直分辨率低的问题，难以对深层不连续面成像。为了更好地解决这些问题，更准确地对深部不连续面进行成像，对印度南部海得拉巴站（HYB）记录的远震数据采用了 P 波自相关法。这种方法有效地确定了深度达 250 千米的主要浅层上地幔不连续面。在 30.37、92.17、123.43、140.50 和 ~201 千米处分别观测到了莫霍面、岩石圈中层不连续面、海尔斯不连续面、岩石圈-岩石圈边界和雷曼不连续面。我们还实现了所有浅层上地幔不连续面的极高垂直分辨率（0.6 千米）。此外，我们还提出了一种迭代法，利用莫霍反射（2p）和（p+s）相的到达时间计算地壳的（{v}_{p}/{v}_{s}）比值。与其他地震方法不同的是，这种迭代法与 \({v}_{p}\) 和\({v}_{s}\) 的任何约束无关。研究重点以高垂直分辨率（<0.HYB 下有薄地壳（30 公里）和长石成分（\({v}_{p}/{v}_{s}\sim 1.744)）。在 HYB 下 ~92 公里处和 ~140 公里处分别有明显的 MLD 和 LAB 特征。

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来源期刊

Journal of Earth System Science Earth and Planetary Sciences-General Earth and Planetary Sciences

CiteScore

3.20

自引率

5.30%

发文量

226

期刊介绍： The Journal of Earth System Science, an International Journal, was earlier a part of the Proceedings of the Indian Academy of Sciences – Section A begun in 1934, and later split in 1978 into theme journals. This journal was published as Proceedings – Earth and Planetary Sciences since 1978, and in 2005 was renamed ‘Journal of Earth System Science’. The journal is highly inter-disciplinary and publishes scholarly research – new data, ideas, and conceptual advances – in Earth System Science. The focus is on the evolution of the Earth as a system: manuscripts describing changes of anthropogenic origin in a limited region are not considered unless they go beyond describing the changes to include an analysis of earth-system processes. The journal''s scope includes the solid earth (geosphere), the atmosphere, the hydrosphere (including cryosphere), and the biosphere; it also addresses related aspects of planetary and space sciences. Contributions pertaining to the Indian sub- continent and the surrounding Indian-Ocean region are particularly welcome. Given that a large number of manuscripts report either observations or model results for a limited domain, manuscripts intended for publication in JESS are expected to fulfill at least one of the following three criteria. The data should be of relevance and should be of statistically significant size and from a region from where such data are sparse. If the data are from a well-sampled region, the data size should be considerable and advance our knowledge of the region. A model study is carried out to explain observations reported either in the same manuscript or in the literature. The analysis, whether of data or with models, is novel and the inferences advance the current knowledge.

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