scholarly journals Comparison of 3D, 2D, and 1D Magnetotelluric Inversion Results on the Example of Data from Fore-Sudetic Monocline

2022 ◽  
Vol 2022 ◽  
pp. 1-19
Author(s):  
Szymon Oryński ◽  
Waldemar Jóźwiak ◽  
Krzysztof Nowożyński ◽  
Wojciech Klityński
Keyword(s):  
Upper Mantle ◽  
Data Interpretation ◽  
3D Inversion ◽  
Geological Structures ◽  
Magnetotelluric Data ◽  
Crust And Upper Mantle ◽  
Upper Mantle Structure ◽  
Magnetotelluric Inversion ◽  
Different Origins ◽  
2D And 3D

This study’s main objective is to better define and understand results for the most commonly used inversion algorithms in magnetotelluric data interpretation as part of geological exploration of the region of the Dolsk fault and the Odra fault. The data obtained from the eastern part of Fore-Sudetic Monocline measurements were used to describe the boundaries of lithospheric blocks (terranes) and recognize their origin. The magnetotelluric (MT) soundings were carried out to achieve this goal. There were conducted 51 soundings on five quasiparallel profiles. That allows constructing a quasiregular mesh in the area of the Fore-Sudetic Monocline. This arrangement of the measuring grid allowed reducing the influence of the largest sources of disturbances on MT data. 1D and 2D models were created by using the inverse algorithms. The models were prepared for each profile separately. Further, parallel (ModEM) 3D inversion codes were applied. The area where the investigation was done involves the region of the Dolsk fault and the Odra fault. These zones are essential geologic borders of a regional nature, and they pull apart the crust blocks with different origins. It was vitally needed to correctly identify the crust and upper mantle structure around a part of the Fore-Sudetic Monocline. The paper shows how these key features of the geological structures are revealed using 1D, 2D, and 3D algorithms.

Deep electrical structure of northern Alberta (Canada): implications for diamond exploration

2009 ◽  
Vol 46 (2) ◽  
pp. 139-154 ◽  
Author(s):  
Erşan Türkoğlu ◽  
Martyn Unsworth ◽  
Dinu Pana
Keyword(s):  
Subduction Zone ◽  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Three Dimensional ◽  
Diamond Formation ◽  
Magnetotelluric Data ◽  
Diamond Exploration ◽  
Upper Mantle Structure ◽  
Resistivity Model ◽  
Northern Alberta

Geophysical studies of upper mantle structure can provide constraints on diamond formation. Teleseismic and magnetotelluric data can be used in diamond exploration by mapping the depth of the lithosphere–asthenosphere boundary. Studies in the central Slave Craton and at Fort-à-la-Corne have detected conductors in the lithospheric mantle close to, or beneath, diamondiferous kimberlites. Graphite can potentially explain the enhanced conductivity and may imply the presence of diamonds at greater depth. Petrologic arguments suggest that the shallow lithospheric mantle may be too oxidized to contain graphite. Other diamond-bearing regions show no upper mantle conductor suggesting that the correlation with diamondiferous kimberlites is not universal. The Buffalo Head Hills in Alberta host diamondiferous kimberlites in a Proterozoic terrane and may have formed in a subduction zone setting. Long period magnetotelluric data were used to investigate the upper mantle resistivity structure of this region. Magnetotelluric (MT) data were recorded at 23 locations on a north–south profile extending from Fort Vermilion to Utikuma Lake and an east–west profile at 57.2°N. The data were combined with Lithoprobe MT data and inverted to produce a three-dimensional (3-D) resistivity model with the asthenosphere at 180–220 km depth. This model did not contain an upper mantle conductor beneath the Buffalo Head Hills kimberlites. The 3-D inversion exhibited an eastward dipping conductor in the crust beneath the Kiskatinaw terrane that could represent the fossil subduction zone that supplied the carbon for diamond formation. The low resistivity at crustal depths in this structure is likely due to graphite derived from subducted organic material.

Crust and Upper Mantle Structure Beneath the Eastern United States

2021 ◽  
Author(s):  
Chengping Chai ◽  
Charles Ammon ◽  
Monica Maceira ◽  
Herrmann B. Robert
Keyword(s):  
United States ◽  
Upper Mantle ◽  
Mantle Structure ◽  
Eastern United States ◽  
Crust And Upper Mantle ◽  
Upper Mantle Structure

Crust and upper mantle structure along the flank of Kōko Seamount

1980 ◽  
Vol 70 (4) ◽  
pp. 1161-1169
Author(s):  
K. Furukawa ◽  
J. F. Gettrust ◽  
L. W. Kroenke ◽  
J. F. Campbell
Keyword(s):  
Upper Mantle ◽  
Seismic Refraction ◽  
Crustal Thickness ◽  
Mantle Structure ◽  
Crust And Upper Mantle ◽  
Velocity Gradients ◽  
Upper Mantle Structure ◽  
Hawaiian Ridge ◽  
Seamount Chain ◽  
Emperor Seamount Chain

abstract Inversion of an 80-km-long reversed seismic refraction profile near the northwestern flank of Kōko Seamount indicates that the crust adjacent to the southern end of the Emperor Seamount chain is approximately 9-km thick with no dip in the refracting horizons. These data require positive P-velocity gradients in the crust and upper mantle to fit the observed amplitudes. The crustal refractor P velocities and crustal thickness found are in general agreement with those found previously for the Emperor chain and near the Hawaiian Ridge. It is inferred from our data that the tectonic mechanism which created the Emperor and Hawaiian chains was highly localized.

Azimuth and slowness anomalies of seismic waves measured on the central California seismographic array. Part I. Observations

1966 ◽  
Vol 56 (1) ◽  
pp. 223-239 ◽  
Author(s):  
Michio Otsuka
Keyword(s):  
Upper Mantle ◽  
Measurement Errors ◽  
Seismic Waves ◽  
Crust And Upper Mantle ◽  
Arrival Times ◽  
Central California ◽  
The North ◽  
Upper Mantle Structure ◽  
Coast Ranges ◽  
The University

abstract Arrays of seismographs are usually considered to be detectors which give enhanced signals from distant earthquakes. They also provide, however, a new way of learning more about the structure of the crust and upper mantle. The deviation of the seismic-wave surface from its expected configuration may be regarded as a consequence of non-homogeneous and anisotropic conditions in the earth. The operations of the University of California network of telemetry stations in the Coast Ranges of California provides an opportunity to discover the practicality of this approach. The situation of this network near the continental margin gives the study particular interest. The differences in arrival-times between array elements of coherent peaks or troughs of P and pP phases from 28 teleseisms in the period of 1963-1964 were read from the telemetry records of the central California seismographic array. The direction of approach and velocities of the wave fronts were then determined and compared with the great circle azimuths and with the apparent velocities calculated from the Jeffreys-Bullen tables. The observed anomalies in direction of approach and apparent velocites are found to be cyclic functions of the direction of the source. The amplitudes of these functions are almost 10 degrees in azimuth anomaly and 1.0 sec/deg in slowness anomaly. Error analyses show that the anomaly functions cannot be attributed to the measurement errors. The derived anomaly functions provide a powerful means of examining crustal and upper mantle structure under the array and perhaps at the source. Variations between subsets of the array indicate significant differences in structure between portions of the Coast Ranges to the north and to the south of Hollister.

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