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01 – The challenge
Khao Thap Khwai’s iron ore deposits are real and well documented – but knowing where the ore-bearing zones actually extend beneath a steep, hilly landscape is a different problem than knowing they exist at all.
The hill is officially designated by Thailand’s Department of Mineral Resources as Study Site No. 5, the “Khao Thap Khwai Iron Ore Deposit” – an educational field site used by students, researchers, and geologists to study the area’s geology. That makes the accuracy of any subsurface model more than a one-off concern: it feeds into how the site is understood and taught going forward.
02 – The context
A ground-based TEM2Go survey to map subsurface iron ore deposits at Khao Thap Khwai, an officially designated geological study site in Lop Buri Province, Thailand.
PARTNER
GeoTEMx Co., Ltd.
COUNTRY
Thailand, Asia
TERRAIN
Skarn, marble, magnetite ore
FIELD DAYS
<1
TECHNOLOGY
TEM2Go
YEAR
2026
Field survey and geophysical interpretation conducted by Geophysical Imaging Partners (GIP).
03 – The solution
Ground-Based Transient Electromagnetic Survey
The TEM2Go backpack system was chosen specifically for its ability to access steep terrain on foot. Survey lines were established along the foothills and surrounding areas of Khao Thap Khwai to build a comprehensive subsurface resistivity picture of the hill.
Methodology
01
Survey Planning
Lines were planned along the foothills and surrounding terrain to comprehensively cover the target area.
02
TEM2Go Acquisition
A ground-based, backpack-carried survey collected resistivity soundings across terrain too steep for towed or vehicle-based systems.
03
Resistivity Interpretation
Recorded decay-curve data was processed into resistivity models resolving variation across the surveyed area.
04
Geological Interpretation
Results were separated into three distinct units – a resistive surface layer, competent dome-shaped bedrock at depth, and low-resistivity zones – with the lowest-resistivity zones flagged as the primary iron ore targets, based on the known high conductivity of magnetite and hematite.
04 – The results
The resistivity model resolved three major geological units: a high-resistivity surface layer, dome-shaped competent bedrock at depth, and low- to very low-resistivity zones. Because iron ore minerals like magnetite and hematite are highly conductive, these low-resistivity zones – appearing as blue and light blue on the model – represent the primary targets for iron ore exploration.
100-200Ωm
Resistivity of the dry host rock surrounding the ore zones
3
Distinct geological units identified from one model
100m
Vertical depth of subsurface resolved
The Region
01
The Loei Fold Belt
Khao Thap Khwai’s iron deposits sit along Thailand’s Loei Fold Belt, where skarn deposits formed as ancient limestone came into contact with intruding volcanic rock — the same process that concentrated the magnetite being mapped here.
02
A Community Project
280,000 square metres of forest around the hill are now part of the “Khao Thap Khwai for Community” rehabilitation project, turning a former iron mine into a shared carbon sink, nature trail, and geology learning center.
03
Iron & Copper Together
The Khao Thap Khwai skarn hosts copper alongside its iron, and lead isotope studies trace the ore’s origin to a mix of mantle-derived magma and upper crust material – evidence of deep geological processes, not just surface mineralization.
04
Still an Active Reference Site
Geochemists continue to analyze magnetite trace elements from this exact deposit in ongoing published research, using it as a reference point for understanding how skarn iron deposits form globally.
05 The impact
From surface outcrop to a mapped subsurface – extending what a designated study site can teach.
Khao Thap Khwai is already studied for its surface geology by students and researchers. This survey adds a resistivity model of what’s beneath it – turning a hillside known for historical iron ore into a mapped picture of exactly where the ore-bearing zones extend underground.
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