{"id":57310,"date":"2025-09-23T03:59:29","date_gmt":"2025-09-23T00:59:29","guid":{"rendered":"https:\/\/geoconversation.org\/geophysics-found-ore-at-a-depth-of-1000-m-seriously\/"},"modified":"2026-05-04T18:32:49","modified_gmt":"2026-05-04T15:32:49","slug":"geophysics-found-ore-at-a-depth-of-1000-m-seriously","status":"publish","type":"post","link":"https:\/\/geoconversation.org\/en\/geophysics-found-ore-at-a-depth-of-1000-m-seriously\/","title":{"rendered":"Geophysics found ore at a depth of 1000 m. Seriously?"},"content":{"rendered":"\n

Deposits are becoming deeper, and their geological conditions more complex, necessitating new technologies for their discovery. However, the conversation often ends there: what exactly is meant by “new technologies” is almost never explained. For instance, in geophysics, geologists and subsoil users often develop unrealistic expectations, especially when presented with a “new method” at a conference. Some begin to perceive geophysics as a magic button that will instantly solve all problems. Others, conversely, are convinced that such technologies are unsubstantiated. <\/p>\n\n

In this article, I want to use examples from my work in British Columbia to demonstrate a specific methodology that allows for the investigation of depths up to 1000 meters. The method is based on established principles of electromagnetic surveys but is implemented in a way that overcomes the limitations of classic ground and airborne surveys. I will discuss its physical basis, operational organization, and provide a case study from a known deposit. <\/p>\n\n

Finally, this article will focus not on marketing promises, but on specifics: what exactly lies behind the words “new technologies in geophysics” and how they work in practice.<\/p>\n\n

The Physics That Helps Find Ore<\/h2>\n\n

Before delving into practice, let’s briefly return to “school” and recall one of the basic principles of geophysics \u2014 electromagnetic surveying<\/strong>. This physical law directly applies to our task: the search for and exploration of mineral deposits. <\/p>\n\n

The methodology in question is based on the phenomenon of electromagnetic induction: when a magnetic field changes, an electric field arises\u2014and vice versa. The geophysicist’s task is to orchestrate such field changes that a secondary field is generated in conductors at depth\u2014for example, in massive sulfide bodies\u2014which is then detectable. <\/p>\n\n

How does this work in practice? A loop is laid out on the ground and connected to a current source. When the current in the loop is abruptly switched off, a rapid change in the magnetic field occurs, inducing eddy currents in the host rocks. These currents create their own\u2014secondary\u2014magnetic field, which is then recorded by the receiver. <\/p>\n\n

The depth of investigation in such a method is determined by several factors. Loop size<\/strong>: the larger it is, the deeper the primary field penetrates, and the deeper the response that can be obtained. Current strength<\/strong>: the higher the current, the stronger the signal and the more reliable its registration. Frequency<\/strong>: the pause after current shutdown determines the time during which decaying responses are recorded, thereby defining the depth of “visibility.”<\/p>\n\n

\"Electromagnetic<\/a>
Principle of electromagnetic surveys: primary magnetic field, induced eddy currents in the conductor, and secondary field recorded by the receiver<\/figcaption><\/figure>\n\n

What Classic Electromagnetic Methods Offer<\/h2>\n\n

Electromagnetic (EM) surveys are particularly in demand where other methods are difficult to apply. For example, in rocky areas, scree slopes, or during winter, when it’s impossible to properly ground electrodes for classic electrical resistivity surveys. EM surveys also work well when conductors\u2014massive sulfide ores\u2014are expected in the subsurface. <\/p>\n\n

Two operational approaches are possible here. The first is ground-based<\/strong>: the loop is laid out on the surface, and measurements are taken nearby. This provides a good signal and depth of investigation but requires significant physical effort and severely limits work speed. The second is airborne<\/strong>: equipment is lifted by helicopter, allowing hundreds of linear kilometers to be surveyed in a single flight. However, the loop size in this case is limited to tens of meters, and the depth is usually no more than 150\u2013200 m. <\/p>\n\n

Both approaches are effective and still used today, each for its specific task. However, the main drawback of the ground-based method is its laboriousness and low productivity, while aerogeophysics suffers from limited depth penetration. This is precisely why a new method emerged, combining the advantages of both approaches while overcoming their limitations.<\/strong><\/p>\n\n

A New Approach: Airborne Speed and Ground-Based Depth<\/h2>\n\n

This is where the new approach\u2014the HeliSAM method<\/strong><\/a>\u2014comes in. It combines the speed of aerogeophysics with the depth of ground-based surveys, eliminating the weaknesses of each. How does it work? First, a helicopter lays out a large transmitting loop on the ground, through which current is pulsed with pauses. Unlike classic airborne electromagnetic surveys, where loop size is limited to tens of meters, here kilometer-scale loops are used\u2014for example, 1\u00d71 km or even 2\u00d72 km. Laying such a loop takes about 40 minutes. After this, the helicopter takes off for the survey. <\/p>\n\n

\n
\"HeliSAM:<\/a><\/figure>\n\n\n\n
\"Electromagnetic<\/a><\/figure>\n
Left: Helicopter with a spool for laying out the transmitting loop. This allows the wire to be quickly and evenly deployed on the ground before electromagnetic measurements begin. Right: Geophysicist tying the wire to a ground anchor before starting work. After this, the helicopter lifts the spool and begins unwinding the wire, forming the transmitting loop. <\/figcaption><\/figure>\n\n

The survey is performed using a magnetic sensor suspended on a 30\u201350 meter cable, flying approximately 30 m above the ground. In geophysical practice, this sensor is called a “bird.” It is a quantum magnetometer that records changes in magnetic and electromagnetic fields; signals from it are transmitted via cable to a receiver installed in the helicopter itself. The magnetometer’s operation is based on the oscillations of cesium atoms, ensuring very high sensitivity. <\/p>\n\n

\"HeliSAM:<\/a>
Suspended unit (“bird”) with a quantum magnetometer. It flies on a cable beneath the helicopter and records changes in the electromagnetic field. <\/figcaption><\/figure>\n\n

This arrangement eliminates interference from the helicopter itself and allows measurements to be taken as close to the surface as possible. The magnetometer records tens of thousands of values per second, and then the data are averaged into uniform intervals: approximately every 5 m for magnetic measurements and about 20 m for electromagnetic channels. <\/p>\n\n

For those unfamiliar with geophysics, this can be compared to a ground survey where a geophysicist manually takes measurements<\/a> at the same distances. The detail of the results is comparable to “manual” work, but they are collected at helicopter flight speed and over large areas. <\/p>\n\n

As a result, we achieve the productivity of aerogeophysics\u2014tens and hundreds of kilometers of profiles per day\u2014and the depth of ground-based systems. The method allows for mapping conductive bodies at depths of up to 1000 m. <\/p>\n\n

\n
\"Electromagnetic<\/a><\/figure>\n\n\n\n
\"<\/a><\/figure>\n
Left: After completing measurements, the helicopter delivers empty spools for winding up the wire. Right: To reduce heavy field work, the team devised a “cutter” \u2013 an attachment that allows the helicopter to cut the wire and immediately bring it to the collection point. <\/figcaption><\/figure>\n\n

How does this work at a real deposit? Let’s look at a case study from the Lalor volcanogenic massive sulfide (VMS) deposit in Manitoba, Canada. <\/p>\n\n

Case Study: Lalor VMS Deposit, Canada<\/h2>\n\n

The Lalor<\/strong> deposit is located in Manitoba and is known for its copper-zinc-gold mineralization. Its ore bodies are situated at depths of 700\u20131000 m<\/strong> and were discovered<\/a> in 2007 using ground-based electromagnetic surveys. <\/p>\n\n

To test the HeliSAM methodology, a large transmitting loop of approximately 1.7 \u00d7 1.7 km<\/strong> was deployed. Deployment took less than an hour. The helicopter performed flights with a suspended sensor\u2014the so-called “bird,” which houses a quantum magnetometer. The flight altitude was around 30\u201340 m above the surface<\/strong>, and the cable length was 30\u201350 m<\/strong>. <\/p>\n\n

In a single flight, data were collected along profiles totaling approximately 93 km<\/strong>. The sampling interval was about 5 m for magnetic measurements and 20 m for electromagnetic measurements. This is comparable to the detail of a ground survey, but the coverage area was tens of times larger. <\/p>\n\n

\"Generator<\/a>
Generator set supplying current to the loop: a gasoline generator provides 220 V\/50 Hz, a converter (transmitter) reduces the frequency to 5 Hz and provides 20 A current. Equipment for controlling generation and measurements is also located here.<\/figcaption><\/figure>\n\n

The results showed an anomaly coinciding with the known ore body. A response corresponding to the mineralized body at a depth of up to one kilometer was observed on the time channels. Additional modeling allowed for refining the size and orientation of the conductor, and these parameters matched the geological data. <\/p>\n\n

Thus, the method confirmed its ability to map conductive bodies at depths typically considered unattainable for aerogeophysics.<\/p>\n\n

\n
\"HeliSAM:<\/a><\/figure>\n\n\n\n
\"HeliSAM<\/a><\/figure>\n
Left: Loop position diagram and survey specifications. Right: Survey results: maps of electromagnetic anomalies by time channels and total magnetic intensity (TMI) map. <\/figcaption><\/figure>\n\n

How to Distinguish Promises from Working Technologies<\/h2>\n\n

The geophysical services market still has plenty of “magic boxes” and grand promises. It’s easy to make a mistake in such a situation\u2014and that’s normal. Geologists and investors are not obligated to understand the intricacies of sensors or the nuances of signal processing. But precisely for this reason, it’s important to have simple guidelines for distinguishing a working method from an attractive gimmick. <\/p>\n\n

New technologies in geophysics do not arise from unknown physical effects. They evolve through already proven principles\u2014via new generations of sensors, more advanced instruments, and modern processing algorithms. Each new gravimeter detects small field changes better than the previous one<\/a>. The same applies to magnetometers and electromagnetic systems: they allow for recording weaker signals or extracting useful signals from noise. Interpretation has also advanced: artificial intelligence and specialized software transform an “anomaly spot” into a body model with specific dimensions and depth. <\/p>\n\n

\n
\"Comparison<\/a><\/figure>\n\n\n\n
\"Modeling<\/a><\/figure>\n
The electromagnetic response can be modeled to determine the conductor’s position, size, and orientation.<\/figcaption><\/figure>\n\n

Therefore, the main advice for those choosing a methodology is: do not expect miracles from a trendy name<\/strong>. Start with geology: determine the type of deposit, the conditions of ore body occurrence, and their physical properties. It is important to understand how these properties differ from the host rocks\u2014conductivity, magnetic susceptibility, density. This should determine the choice of geophysical method<\/a>. If it’s about massive sulfides at depths of 500\u20131000 m, as in my project in British Columbia, then it makes sense to use a deep and more expensive helicopter-borne method. But if the goal is shallow horizons, completely different solutions will be appropriate. <\/p>\n\n

Another important criterion is transparency and practical application. A reputable contractor should be able to demonstrate where the method has already been applied and what results it yielded<\/a>. It should be clear that the company possesses the equipment, specialists, and software for data processing and interpretation. <\/p>\n\n

I would add: for me, this was a unique opportunity\u2014to work with HeliSAM, a system that only recently entered the market in 2022. It showed how geophysics is evolving: not just in software and algorithms, but also in hardware, in the organization of field operations, and in the methodology itself. And this development opens new horizons for finding deposits that seemed unattainable just ten years ago. <\/p>\n\n

The material was prepared with the support of the Russian Ministry of Education and Science within the framework of the Decade of Science and Technology.<\/p>\n","protected":false},"excerpt":{"rendered":"

Deposits are becoming deeper, and their geological conditions more complex, necessitating new technologies for their discovery. However, the conversation often ends there: what exactly is meant by “new technologies” is almost never explained. For instance, in geophysics, geologists and subsoil users often develop unrealistic expectations, especially when presented with a “new method” at a conference. […]<\/p>\n","protected":false},"author":2,"featured_media":57311,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_seopress_robots_primary_cat":"none","_seopress_titles_title":"Geophysics: Exploring Deposits at 1000 Meters Depth","_seopress_titles_desc":"New Technologies in Geophysics: The HeliSAM Method Enables Mapping Ore Bodies at Depths of up to 1000 m. A Case Study from a Canadian Deposit","_seopress_robots_index":"","footnotes":""},"categories":[560,559],"tags":[563,561],"tag-cat":[595,596],"class_list":{"0":"post-57310","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-exploration","8":"category-geophysics","9":"tag-electrical-exploration","10":"tag-geophysical-exploration-methods","11":"tag-cat-exploration","12":"tag-cat-geology-and-geophysics"},"acf":[],"pbg_featured_image_src":{"full":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855.jpg",1920,1536,false],"thumbnail":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-150x150.jpg",150,150,true],"medium":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-300x240.jpg",300,240,true],"medium_large":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-768x614.jpg",768,614,true],"large":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-1024x819.jpg",1024,819,true],"1536x1536":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-1536x1229.jpg",1536,1229,true],"2048x2048":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855.jpg",1920,1536,false],"bricks_large_16x9":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-1200x675.jpg",1200,675,true],"bricks_large":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-1200x960.jpg",1200,960,true],"bricks_large_square":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-1200x1200.jpg",1200,1200,true],"bricks_medium":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-600x480.jpg",600,480,true],"bricks_medium_square":["https:\/\/geoconversation.org\/wp-content\/uploads\/2025\/09\/img_6855-600x600.jpg",600,600,true]},"pbg_author_info":{"display_name":"\u041c\u0430\u0440\u0438\u044f \u041a\u043e\u0441\u0442\u0438\u043d\u0430","author_link":"https:\/\/geoconversation.org\/en\/author\/marusyaparma\/","author_img":false},"pbg_comment_info":" No Comments","pbg_excerpt":"Deposits are becoming deeper, and their geological conditions more complex, necessitating new technologies for their discovery. However, the conversation often ends there: what exactly is meant by “new technologies” is almost never explained. For instance, in geophysics, geologists and subsoil users often develop unrealistic expectations, especially when presented with a “new method” at a conference.…","_links":{"self":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/posts\/57310","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/comments?post=57310"}],"version-history":[{"count":3,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/posts\/57310\/revisions"}],"predecessor-version":[{"id":57323,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/posts\/57310\/revisions\/57323"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/media\/57311"}],"wp:attachment":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/media?parent=57310"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/categories?post=57310"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/tags?post=57310"},{"taxonomy":"tag-cat","embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/tag-cat?post=57310"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}