The benefits of reflection seismic in mineral exploration

Reflection seismic, akin to an ultrasound of the Earth’s subsurface, is a powerful tool for uncovering valuable resources deep underground. With the right technology, it provides low-cost, rapid, and reliable data that helps guide the future development of exploration projects with precision and efficiency.

What is the reflection seismic method?

The reflection seismic method is a geophysical technique that generates detailed images of subsurface structures by sending controlled energy pulses into the ground and recording the returning ‘echoes’ using seismic recording devices, known as Nodes. These ‘echoes’ are produced where significant contrasts in rock properties, such as density and seismic velocity, exist.

In mineral exploration, this method is invaluable for identifying key geological features like fault zones, ore bodies, and underground developments. Whether in two dimensions (2D) or three dimensions (3D), seismic data delivers unmatched resolution, even at depths exceeding 2000 m, where other methods struggle to provide clear results.

What can seismic imaging reveal?

Seismic imaging is exceptionally versatile, capable of detecting:

• Lithological contacts: Key to understanding rock formations and mineral distributions.
• Faults and shear zones: Often associated with mineralisation and ore deposition.
• Massive sulfide bodies: Potential ore targets in mining.
• Lithium-bearing pegmatite dykes: Critical for lithium extraction in battery production.
• Alteration zones: Indicate areas of mineral alteration, which can be linked to mineralisation.
• Existing underground infrastructure: Useful for mapping tunnels, old mine workings, or other man-made structures.

What sets reflection seismic apart is its ability to maintain its resolution at greater depths, making it the best method for detecting deep-seated targets. Whether you are exploring for gold, copper, nickel, or lithium, seismic imaging allows you to look deeper and more accurately, often reducing the need for costly exploratory drill holes or wasted budget using traditional, and ineffective ambient noise tomography (ANT) techniques.

The seismic advantage in mineral exploration

Unlike other geophysical methods, such as ANT studies or gravity magnetics surveys, reflection seismic data retains the detail required to make informed decisions. This makes it an invaluable tool, especially when exploring for deep targets that may be concealed beneath known deposits.

At the regional scale, 2D seismic data helps with tenement selection by identifying large, fertile structures. At the project scale, it supports more accurate interpretations of other geophysical data, and at the mine scale, 3D seismic data is highly effective at locating additional resources near existing infrastructure. This extends a mine’s productive life by identifying further drill targets while minimising waste.

How seismic enhances mining exploration workflows

The integration of seismic data into a mineral exploration workflow amplifies the value of existing datasets. For instance, seismic images provide the depth context for data from magnetic or gravity surveys, helping geologists map subsurface structures more accurately.

Seismic data also brings enormous value during the resource definition phase of a project. A detailed 3D seismic survey can raise the confidence level of a resource estimate, potentially upgrading a mineral resource classification from inferred to indicated or even measured.

At the latter stages of a project’s life, when near-mine exploration options begin to dwindle, 3D seismic data can unlock new possibilities, identifying previously hidden structural settings for further mineralisation.

Can seismic data reduce exploration costs?

Compared to traditional exploration methods like borehole drilling, seismic surveys offer significant cost savings. A typical 20-hole drilling program can cost around US$10 million. By investing just a fraction of this into a seismic survey, drill targeting can be optimised, reducing the number of unnecessary drill holes and dramatically lowering overall exploration costs.

In many cases, the savings from avoiding just a few misplaced boreholes can make seismic surveys pay for themselves.

Additionally, seismic data accelerates decision-making by enabling a ‘fail fast’ approach. If a project shows low viability, the detailed insights from seismic surveys allow exploration teams to make informed decisions early on, whether to proceed or divest. This agility helps save both time and resources by focusing efforts on the most promising opportunities and avoiding costly, prolonged exploration of less viable prospects.

Why reflection seismic beats ANT methods

There is a growing misconception that ANT or passive seismic methods can deliver results comparable to reflection seismic data. While passive seismic methods can be cheaper, they are not substitutes for reflection seismic in mineral exploration. These methods work best for mapping large-scale features, such as depth to bedrock, but lack the resolution needed to target mineral systems accurately.

Reflection seismic, on the other hand, is custom-tailored to the investigation, designed to answer specific geological questions with precision. The high-resolution data it provides is unmatched, particularly when investigating deep or complex mineral systems.

In a competitive market where shallow mineral targets grow scarce and drilling budgets are tight, can exploration projects afford to overlook the power of reflection seismic data?

Read the article online at: https://www.globalminingreview.com/mining/06112024/the-benefits-of-reflection-seismic-in-mineral-exploration/