3D structure and physical properties of the Kuhmo Greenstone Belt (eastern Finland): Constraints from gravity modelling and seismic data and implications for the tectonic setting

Silvennoinen, Hanna; Kozlovskaya, Elena

doi:10.1016/j.jog.2006.09.018

Cited by 12 publications

(10 citation statements)

References 16 publications

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“…Although we cannot distinguish whether such high values are due to seismic anisotropy or eclogitic composition, both these explanations suggest that this zone was formed as a result of plate-tectonic processes. This agrees also with the recent study by Silvennoinen & Kozlovskaya (2007), who demonstrated that the Kuhmo greenstone belt most probably was formed as a result of plate-tectonic processes.…”

Section: Discussionsupporting

confidence: 93%

Structure and composition of the crust and upper mantle of the Archean-Proterozoic boundary in the Fennoscandian shield obtained by joint inversion of receiver function and surface wave phase velocity of recording of the SVEKALAPKO array

Kozlovskaya¹,

Kosarev

Aleshin

et al. 2008

Geophysical Journal International

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S U M M A R YWe present a 3-D model of absolute values of S-wave velocities and V P /V S ratios in the crust and upper mantle beneath the SVEKALAPKO temporary seismic array that covered the transition zone between Archean and Proterozoic domains in the Precambrian Fennoscandian Shield. The model was obtained using joint inversion of P-wave receiver functions, Rayleigh phase velocities and traveltimes of waves converted from the 410 km discontinuity. P-wave receiver functions and traveltimes of Ps waves converted from the 410 km boundary were estimated for 30 broad-band stations of the SVEKALAPKO array and short-period, smallaperture RUKSA array in Russian Karelia. The phase velocities of Rayleigh waves were taken from previous surface wave studies (Bruneton et al. 2004a,b). For each station, the different data sets were merged and inverted by simulated annealing method. After that, a 3-D S-wave velocity model and distribution of V P /V S ratio was obtained from 1-D velocity models, using special interpolation technique. The new 3-D seismic model demonstrates pronounced lateral variations of values of V S and V P /V S ratio in the crust and uppermost mantle. The depth to the Moho boundary varies from 51 to 63 km in our model, which agrees with the results of previous controlled-source seismic studies in the region. The Moho boundary is overlain by a high-velocity lower crust (HVLC), with high V S , which is non-uniform in composition and origin. Our study showed no systematic correlation between the lithosphere structure and tectonothermal age of Archean and Proterozoic crustal terrains in the study area. The exposed Archean-Proterozoic suture (so-called Ladoga-Bothnian Bay Zone) is not observed as a mega-scale structure in the crust and upper mantle. Generally, the Archean-Proterozoic transition occupies a larger area in the lithosphere than it was thought earlier. It is marked by a Moho depression stretching to the North and by a zone of high V P and high V P /V S in the mantle. Our results supports the theory that the Fennoscandian Shield was assembled as a result of extensive collisional accretion of island arcs and microcontinental blocks and shows that these processes were working both in Archean and Proterozoic.

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Section: Discussionsupporting

confidence: 93%

Structure and composition of the crust and upper mantle of the Archean-Proterozoic boundary in the Fennoscandian shield obtained by joint inversion of receiver function and surface wave phase velocity of recording of the SVEKALAPKO array

Kozlovskaya¹,

Kosarev

Aleshin

et al. 2008

Geophysical Journal International

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“…8, our SNR-stacking algorithm has selected only EGFs with group velocity of about 3400 m s −1 . This velocity is close to the minimal value from all group velocities, and it is in agreement with group velocities of surface waves and S-wave velocities in the uppermost part of the bedrock in Fennoscandia (Kobranova, 1986;Dortman, 1992;Silvennoinen and Kozlovskaya, 2007;Janik et al, 2009;Poli et al, 2013, etc.). Therefore, after applying our stacking method, we can retrieve EGFs with true group velocity and a maximum SNR.…”

Section: Empirical Green's Functions Estimationsupporting

confidence: 83%

“…As an example of an area with a low level of anthropogenic seismic noise, we selected an area located in the Kuusamo Greenstone Belt (KuGB), Finland, because of numerous previous geological and geophysical studies there (Silvennoinen, 1991;Bruneton et al, 2004;Yliniemi et al, 2004;Silvennoinen and Kozlovskaya, 2007;Poli et al, 2012b;Pedersen et al, 2013;Silvennoinen et al, 2014;Tiira et al, 2014;Vinnik et al, 2014, etc.). Moreover, Weihed et al (2005) and Lehtonen and O'Brien (2009) have shown that this area is prospective for gold-and diamond deposits.…”

Section: Kuusamo Greenstone Belt Areamentioning

confidence: 99%

Improving the quality of empirical Green's functions, obtained by cross-correlation of high-frequency ambient seismic noise

et al. 2019

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Abstract. Studying the uppermost structure of the subsurface is a necessary part of solving many practical problems (exploration of minerals, groundwater studies, geoengineering, etc.). The practical application of active seismic methods for these purposes is not always possible for different reasons, such as logistical difficulties, high cost of work, and a high level of seismic and acoustic noise. That is why developing and improving passive seismic methods is one of the important problems in applied geophysics. In our study, we describe a way of improving the quality of empirical Green's functions (EGFs), evaluated from high-frequency ambient seismic noise, by using the advanced technique of cross-correlation function stacking in the time domain (in this paper we use term “high-frequency” for frequencies higher than 1 Hz). The technique is based on the global optimization algorithm, in which the optimized objective function is a signal-to-noise ratio of an EGF, retrieved at each iteration. In comparison to existing techniques, based, for example, on weight stacking of cross-correlation functions, our technique makes it possible to significantly increase the signal-to-noise ratio and, therefore, the quality of the EGFs. The technique has been tested with the field data acquired in an area with a high level of industrial noise (Pyhäsalmi Mine, Finland) and in an area with a low level of anthropogenic noise (Kuusamo Greenstone Belt, Finland). The results show that the proposed technique can be used for the extraction of EGFs from high-frequency seismic noise in practical problems of mapping of the shallow subsurface, both in areas with high and low levels of high-frequency seismic noise.

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“…This study aims to implement the vertical and horizontal derivatives as an interpretation technique to improve the linear trend of the gravity data. In order to delineate the fault geometry in the subsurface, 3D gravity was inverted using the Singular Value Decomposition (SVD) and Occam modeling [24]. To solve the ambiguity of gravity inversion, the models were combined with the geological fault structure obtained from several previously published studies in the areas stretching from Sumatera to the Andaman Sea as a constraints model [6], [25], [26].…”

Section: Introductionmentioning

confidence: 99%

Continuity of Great Sumatran Fault in the Marine Area Revealed by 3d Inversion of Gravity Data

et al. 2020

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The Great Sumatran Fault (GSF) is a 1900-km-long fault extending from Lampung, Indonesia, to India's Andaman Islands. The fault location is not only on the land but also in the marine area. Previous studies were only focused on the land area of Sumatra and Andaman Islands even though the marine fault has also impacted earthquakes and tsunamis such as in 2004. As an effort to disaster risk mitigation, this study used the gravity method to map and study the continuity of the GSF in the marine area from the Aceh Province, Indonesia, to the Andaman Islands, India. The gravity data were obtained from Topex with a resolution of 1.85 km/px. Based on the Bouguer data, the subduction zone in the western part of the Indian Ocean is observed with the anomaly of 500–700 mGal, while the residual structure of GSF, relative to the subduction zone, only comes to clarity through a horizontal derivative transformation with anomaly 130-250 mGal. To delineate the fault's geometry, the data were inverted by GRABLOX 1.6 using Singular Value Decomposition and Occam methods. The 3D modeling results also clearly show the contrast density between regional faults such as subduction zones on the Westside of the West Andaman Fault (WAF). The GSF faults can also be well demonstrated at 50 km depth. Based on these results, the gravity Topex is potentially used as a preliminary study of the GSF activity in the marine area.

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3D structure and physical properties of the Kuhmo Greenstone Belt (eastern Finland): Constraints from gravity modelling and seismic data and implications for the tectonic setting

Cited by 12 publications

References 16 publications

Structure and composition of the crust and upper mantle of the Archean-Proterozoic boundary in the Fennoscandian shield obtained by joint inversion of receiver function and surface wave phase velocity of recording of the SVEKALAPKO array

Structure and composition of the crust and upper mantle of the Archean-Proterozoic boundary in the Fennoscandian shield obtained by joint inversion of receiver function and surface wave phase velocity of recording of the SVEKALAPKO array

Improving the quality of empirical Green's functions, obtained by cross-correlation of high-frequency ambient seismic noise

Continuity of Great Sumatran Fault in the Marine Area Revealed by 3d Inversion of Gravity Data

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