scholarly journals Regional-Scale Mineral Exploration Through Joint Inversion and Geology Differentiation Based on Multiphysics Geoscientific Data in the QUEST Project Area

2021 ◽  
Author(s):  
Jae Deok Kim ◽  
Jiajia Sun ◽  
Aline Melo
Keyword(s):  
Joint Inversion ◽  
Mineral Exploration ◽  
Regional Scale ◽  
Project Area ◽  
Geoscientific Data

Karrat 97: reconnaissance mineral exploration in central West Greenland

1998 ◽  
pp. 73-80 ◽  
Author(s):  
Agnete Steenfelt ◽  
Bjørn Thomassen ◽  
Mogens Lind ◽  
Johannes Kyed
Keyword(s):  
Stream Water ◽  
Mineral Exploration ◽  
Regional Scale ◽  
Mining Industry ◽  
Mineral Resources ◽  
Field Work ◽  
Geochemical Data ◽  
Joint Project ◽  
Project Area ◽  
West Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Steenfelt, A., Thomassen, B., Lind, M., & Kyed, J. (1998). Karrat 97: reconnaissance mineral exploration in central West Greenland. Geology of Greenland Survey Bulletin, 180, 73-80. https://doi.org/10.34194/ggub.v180.5089 _______________ The Karrat 97 project aims at the acquisition of geochemical data from drainage samples and information on mineralisation within a 10 000 km2 area, which stretches from Uummannaq northwards to Prøven (i.e. from 70°30′ to 72°30′ N; Fig. 1). The project area comprises a major Palaeoproterozoic supracrustal unit, the Karrat Group, from which the project takes its name, and which hosts the abandoned Black Angel lead-zinc mine. It is a joint project between the Geological Survey of Denmark and Greenland (GEUS) and the Bureau of Minerals and Petroleum (BMP), Government of Greenland, and wholly funded by the latter. The goal of the project is to win back the interest of the mining industry to the area. The eastern part of the project area is difficult of access due to alpine topography with peaks up to 2300 m, abundant glaciers, and steep-sided, often ice-filled fjords. A somewhat more gentle topography prevails in the western parts of the area. The whole area is underlain by permafrost. Field work was carried out during seven weeks in July–August 1997 by a team of four geologists and four local prospectors. Job-training of the prospectors was an integral purpose of the project, and the manning of the teams was periodically changed so that all four prospectors were introduced to the different topographical and geological terrains in the area as well as to the methods of operation. A chartered 68 foot, 77 tons vessel – M/S Nukik – served as mobile base with accommodation and meals on board; a MD 500 E helicopter with crew chartered through Grønlandsfly A/S participated for one month. The work was carried out from five anchorages, with the helicopter stationed on the adjacent coast. The weather was relatively unstable in the field period, but only five days of work were lost due to bad weather. The field work comprised regional-scale systematic drainage sampling, and detailed mineral exploration at selected sites. The sampling of stream sediment and stream water supplements the geochemical mapping programme of Greenland undertaken jointly by GEUS and BMP (Steenfelt 1993, 1994), the aim of which is to provide systematic, quality controlled geochemical data. The data are used together with geological and geophysical information in the evaluation of the potential for economic mineral resources. Samples were collected by two teams, transported by helicopter or small boats. All ice-free, near-coastal localities were sampled by the boat team, whereas all other localities were sampled by the helicopter team. The results of this work have been reported on by Steenfelt et al. (1998). The detailed mineral exploration was follow-up work on previously outlined indications and anomalies. It was carried out by two teams on daily trips by rubber dinghy or helicopter, or by foot traverses from field camps. This part of the project has been reported on by Thomassen & Lind (1998).

Lineaments Revisited

SEG Discovery ◽  
2000 ◽  
pp. 1-20
Author(s):  
JEREMY P. RICHARDS
Keyword(s):  
Large Scale ◽  
Mineral Exploration ◽  
Porphyry Copper ◽  
Regional Scale ◽  
Tectonic Events ◽  
Magma Reservoirs ◽  
Magma Supply ◽  
Magmatic History ◽  
Lithospheric Stress ◽  
Crustal Magma

ABSTRACT Large-scale crustal lineaments are recognized as corridors (up to 30 km wide) of aligned geological, structural, geomorphological, or geophysical features that are distinct from regional geological trends such as outcrop traces. They are commonly difficult to observe on the ground, the scale of the features and their interrelationships being too large to map except at a regional scale. They are therefore most easily identified from satellite imagery and geophysical (gravity, magnetic) maps. Lineaments are believed to be the surface expressions of ancient, deep-crustal or trans-lithospheric structures, which periodically have been reactivated as planes of weakness during subsequent tectonic events. These planes of weakness, and in particular their intersections, may provide high-permeability channels for ascent of deeply derived magmas and fluids. Optimum conditions for magma penetration are provided when these structures are placed under tension or transtension. In regions of subduction-related magmatism, porphyry copper and related deposits may be generated along these lineaments because the structures serve to focus the ascent of relatively evolved magmas and fluid distillates from deep-crustal magma reservoirs. However, lineament intersections can only focus such activity where a magma supply exists, and when lithospheric stress conditions permit. A comprehensive understanding of regional tectono-magmatic history is therefore required to interpret lineament maps in terms of their prospectivity for mineral exploration.

Geophysics introduces new section on multiphysics and joint inversion

2020 ◽  
Vol 39 (10) ◽  
pp. 753-754
Author(s):  
Jiajia Sun ◽  
Daniele Colombo ◽  
Yaoguo Li ◽  
Jeffrey Shragge
Keyword(s):  
Big Data ◽  
Joint Inversion ◽  
Effective Means ◽  
Added Value ◽  
Data Sets ◽  
Computational Power ◽  
Sources Of Information ◽  
Multiple Sources ◽  
Data Types ◽  
Geoscientific Data

Geophysicists seek to extract useful and potentially actionable information about the subsurface by interpreting various types of geophysical data together with prior geologic information. It is well recognized that reliable imaging, characterization, and monitoring of subsurface systems require integration of multiple sources of information from a multitude of geoscientific data sets. With increasing data volumes and computational power, new data types, constant development of inversion algorithms, and the advent of the big data era, Geophysics editors see multiphysics integration as an effective means of meeting some of the challenges arising from imaging subsurface systems with higher resolution and reliability as well as exploring geologically more complicated areas. To advance the field of multiphysics integration and to showcase its added value, Geophysics will introduce a new section “Multiphysics and Joint Inversion” in 2021. Submissions are accepted now.

scholarly journals Acquisition and Processing of Wider Bandwidth Seismic Data in Crystalline Crust: Progress with the Metal Earth Project

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 145 ◽  
Author(s):  
Mostafa Naghizadeh ◽  
David Snyder ◽  
Saeid Cheraghi ◽  
Steven Foster ◽  
Samo Cilensek ◽  
...  
Keyword(s):  
Seismic Data ◽  
Early Stage ◽  
Mineral Exploration ◽  
Regional Scale ◽  
Waveform Inversion ◽  
Active Sensors ◽  
Full Waveform ◽  
Time Migration ◽  
Petroleum Sector ◽  
Seismic Reflection Profiles

The Metal Earth project acquired 927 km of deep seismic reflection profiles from August to November of 2017. Seismic data acquired in this early stage of the Metal Earth project benefited greatly from recent advances in the petroleum sector as well as those in mineral exploration. Vibroseis acquisition with receivers having a 5 Hz response (10 dB down) generated records from a sweep signal starting at 2 Hz, sweeping up to 150 Hz or 200 Hz. Not only does this broadband signal enhance reflections from the deepest to the shallowest crust, but it also helps the use of full waveform inversion (e.g., to mitigate cycle-skipping) and related techniques. Metal Earth regional-scale transects using over 5000 active sensors target mineralizing fluid pathways throughout the crust, whereas higher spatial-resolution reflection and full-waveform surveys target structures at mine camp scales. Because Metal Earth was proposed to map and compare entire Archean ore and geologically similar non-ore systems, regional sections cover the entire crust to the Moho in the Abitibi and Wabigoon greenstone belts of the Superior craton in central Canada. Where the new sections overlap with previous Lithoprobe surveys, a clear improvement in reflector detection and definition is observed. Improvements are here attributed to the increased bandwidth of the signal, better estimates of refraction and reflection velocities used in processing, and especially the pre-stack time migration of the data.

Understanding Geologic Uncertainty in Mining Studies

SEG Discovery ◽  
2019 ◽  
pp. 21-29
Author(s):  
Roderick Carlson
Keyword(s):  
Feasibility Study ◽  
Mineral Exploration ◽  
Feasibility Studies ◽  
Early Career ◽  
International Standards ◽  
Measurement Technology ◽  
Data Types ◽  
Social License ◽  
Geologic Uncertainty ◽  
Geoscientific Data

Editor’s note: The Geology and Mining series, edited by Dan Wood and Jeffrey Hedenquist, is designed to introduce early-career professionals and students to a variety of topics in mineral exploration, development, and mining, in order to provide insight into the many ways in which geoscientists contribute to the mineral industry. Abstract The role of geology in advanced mining studies, such as feasibility studies, is commonly dwarfed by the technical inputs from mining, metallurgical, and social license issues. Understanding and planning for geologic risk in the feasibility process is often overlooked for the higher-profile aspects required to establish an ore reserve. If the geologic model of a deposit cannot be reliably forecast, then there will be lower confidence in many of the modifying factors (which include mining, processing, environmental, social, governmental, and economic factors that influence the conversion of identified mineral resources into economic reserves). Understanding geologic risk requires characterization of all the chemical, physical, and spatial properties of mineralization and waste that form part of the mined material. It is essential to understand the scope of the professionals who use geoscientific data in order to assist the outcomes of the study, with the data types first identified, then collected in a comprehensive manner, and finally interpreted at the appropriate time to contribute to the outcomes of the study. If the study is not comprehensive, remedial collection of data is required at a cost to development timeline and budget; a worse scenario is that the development fails economically after it is built. Developing projects to a construction stage after a mining study typically involves international standards of assessment and verification, although the standards of geoscientific data collection differ between companies and countries. For this reason, recent efforts by international bodies such as the Committee for Mineral Reserves International Reporting Standards (CRIRSCO) are assisting many countries to work toward a standardized terminology in a feasibility study. There are many examples where the mining outcomes have not met the feasibility study forecast, with variable causes for a failure to deliver to plan; geoscientific data shortfalls often contribute significantly to these negative outcomes. Examination of case histories, knowledge of international standards for risk reporting, advances in measurement technology, and an understanding of the end users of geoscientific data will help geologists to better prepare the scope of a feasibility study for a potential mine, in order to deliver a product with lower risk related to geologic uncertainty.

scholarly journals Advanced Methods of Joint Inversion of Multiphysics Data for Mineral Exploration

Geosciences ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 262
Author(s):  
Michael S. Zhdanov ◽  
Michael Jorgensen ◽  
Leif Cox
Keyword(s):  
Joint Inversion ◽  
Mineral Exploration ◽  
A Priori ◽  
Geophysical Methods ◽  
Physical Property ◽  
Model Parameters ◽  
Time Inversion ◽  
Structural Constraints ◽  
Considerable Uncertainty ◽  
Additional Information

Different geophysical methods provide information about various physical properties of rock formations and mineralization. In many cases, this information is mutually complementary. At the same time, inversion of the data for a particular survey is subject to considerable uncertainty and ambiguity as to causative body geometry and intrinsic physical property contrast. One productive approach to reducing uncertainty is to jointly invert several types of data. Non-uniqueness can also be reduced by incorporating additional information derived from available geological and/or geophysical data in the survey area to reduce the searching space for the solution. This additional information can be incorporated in the form of a joint inversion of multiphysics data. This paper presents an overview of the main ideas and principles of novel methods of joint inversion, developed over the last decade, which do not require a priori knowledge about specific empirical or statistical relationships between the different model parameters and/or their attributes. These approaches are designated as follows: (1) Gramian constraints; (2) Gramian-based structural constraints; (3) localized Gramian constraints; and (4) joint focusing constraints. We provide a short description of the mathematical foundations of each of these approaches and discuss the practical aspects of their applications in mineral exploration.

Joint inversion of converted and surface waves for characterization of geothermal fields

2021 ◽  
Author(s):  
Ivan Granados Chavarria ◽  
Marco Calò ◽  
Thomas Bodin ◽  
Angel Figueroa Soto
Keyword(s):  
Group Velocity Dispersion ◽  
Joint Inversion ◽  
Seismic Station ◽  
Regional Scale ◽  
Geothermal Field ◽  
Horizon 2020 ◽  
Geothermal Fields ◽  
Converted Phases ◽  
Converted Waves

<p>Joint inversion of surfaces and teleseismic converted waves is commonly used to retrieve seismic structures beneath a seismic station. Currently, this approach is routinely applied at global and regional scale to probe the structures of the mantle and the lower-crust. However, the difficulty to retrieve reliable converted waves at high frequencies (> 1 Hz) makes challenging to apply this technique to resolve structures at shallow depths (<20 km). Here we explore the feasibility of using a trans-dimensional Bayesian scheme based on a reversible jump Markov Chains Monte Carlo method, to resolve shallow structure at local scale. We use phase and group velocity dispersion curves for Love and Rayleigh waves, from 0.5 to 10 s and tele-seismic converted waves in a distance range from 30<sup>o</sup> to 95<sup>o</sup>. We explore the ability of different approaches to retrieve high frequency converted phases that will be used in the framework of the Bayesian inversion. We present preliminary tests of the reliability of the method and applications to experimental data collected in the super-hot geothermal field of Los Humeros, México. This work is performed in the framework of the Mexican European consortium GeMex (Cooperation in Geothermal energy research Europe-Mexico, PT5.2 N: 267084 funded by CONACyT-SENER: S0019, 2015-04, and Horizon 2020, grant agreement No. 727550).</p>

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