Passive seismic imaging of ore deposits using coda wave interferometry: a case study of Akanvaara V-Cr-PGE deposit in Northern Finland

IF 3.2 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Solid Earth Pub Date : 2024-09-18 DOI:10.5194/egusphere-2024-2637

Nikita Afonin, Elena Kozlovskaya, Kari Moisio, Shenghong Yang, Jouni Sarala

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Abstract

Abstract. In this study, we present an innovative method to image the inner structure of orthomagmatic ore deposits using P-wave coda of regional seismic events. We combine data processing and interpretation schemes from conventional passive seismic interferometry and teleseismic receiver function (RF) method. We hypothesize that correlation of P-wave coda recorded by three-component sensors can be used to evaluate body wave part of empirical Green's tensor, from which arrivals of reflected and converted waves could be extracted. To test our hypothesis, we installed a high-resolution seismic array (profile) with 606 seismic instruments on the Akanvaara V-Cr-PGE deposit in Northern Finland above the inclined zones of V-Cr mineralization, placed inside ultramafic intrusion. From the regional seismic catalogue, provided by the Institute of Seismology, University of Helsinki, we selected the P-wave coda of 363 regional seismic events to evaluate body wave part of empirical Green's tensor by passive seismic interferometry. Further interpretation of the tensor allowed us to identify arrivals of PS and SP waves, converted at Cr and V mineralization zones. We conducted numerical simulation of plane wave interaction with the synthetic Akanvaara deposit model compiled from geological and drilling data and found that Green's tensors evaluated from synthetic seismograms and from seismic data contain similar converted PS and SP arrivals. To calculate depths to the conversion boundaries, we obtained S-wave velocity model using MASW method. According to calculated depths and geological model compiled from drilling data we suggest that the converted arrivals correspond to continuation of the Cr and V mineralized zones. Therefore, using the empirical Green's tensor, evaluated from P-wave coda of regional seismic events can be an effective tool for orthomagmatic ore deposits exploration in both greenfield and brownfield cases. In this paper we are describing details of the passive seismic experiment, numerical simulation, data processing and interpretation.

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利用尾波干涉测量法对矿床进行被动地震成像：芬兰北部 Akanvaara V-Cr-PGE 矿床案例研究

摘要在这项研究中，我们提出了一种利用区域地震事件的 P 波尾音对正岩矿床内部结构进行成像的创新方法。我们结合了传统的被动地震干涉测量法和远震接收函数（RF）法的数据处理和解释方案。我们假设，三分量传感器记录的 P 波尾音的相关性可用于评估经验格林张量的体波部分，并从中提取反射波和转换波的到达。为了验证我们的假设，我们在芬兰北部 Akanvaara V-Cr-PGE 矿床的 V-Cr 成矿倾斜带上方安装了一个高分辨率地震阵列（剖面），其中有 606 台地震仪器，位于超基性岩侵入体内部。从赫尔辛基大学地震学研究所提供的区域地震目录中，我们选择了 363 个区域地震事件的 P 波尾音，通过被动地震干涉测量法评估经验格林张量的体波部分。通过对张量的进一步解释，我们确定了 PS 波和 SP 波的到达，并在 Cr 和 V 矿化带进行了转换。我们对平面波与根据地质和钻探数据合成的阿坎瓦拉矿床模型的相互作用进行了数值模拟，发现根据合成地震图和地震数据评估的格林张量包含相似的 PS 和 SP 波转换到达。为了计算转换边界的深度，我们使用 MASW 方法获得了 S 波速度模型。根据计算出的深度和钻探数据编制的地质模型，我们认为转换后的到达点对应于铬矿化带和钒矿化带的延续。因此，在绿地和棕地情况下，使用根据区域地震事件 P 波尾音评估的经验格林张量可以成为正岩矿床勘探的有效工具。本文将详细介绍被动地震实验、数值模拟、数据处理和解释。

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来源期刊

Solid Earth GEOCHEMISTRY & GEOPHYSICS-

CiteScore

6.90

自引率

8.80%

发文量

审稿时长

4.5 months

期刊介绍： Solid Earth (SE) is a not-for-profit journal that publishes multidisciplinary research on the composition, structure, dynamics of the Earth from the surface to the deep interior at all spatial and temporal scales. The journal invites contributions encompassing observational, experimental, and theoretical investigations in the form of short communications, research articles, method articles, review articles, and discussion and commentaries on all aspects of the solid Earth (for details see manuscript types). Being interdisciplinary in scope, SE covers the following disciplines: geochemistry, mineralogy, petrology, volcanology; geodesy and gravity; geodynamics: numerical and analogue modeling of geoprocesses; geoelectrics and electromagnetics; geomagnetism; geomorphology, morphotectonics, and paleoseismology; rock physics; seismics and seismology; critical zone science (Earth''s permeable near-surface layer); stratigraphy, sedimentology, and palaeontology; rock deformation, structural geology, and tectonics.