Abstract Dolerite intrusions in the Chamyal Valley of northern Pakistan are emplaced as dykes and sills within the Cambrian Mansehra Granite and are associated with Permian rifting during the breakup of Gondwana. The valley, situated within the northern Hazara Ranges of the Lesser Himalayas, is structurally bounded by the Panjal Fault, Main Mantle Thrust (MMT), Main Boundary Thrust (MBT), and the Indus River. This study integrates geological field mapping, ground penetrating radar (GPR), and drone-based remote sensing to investigate the structural emplacement and 3D geometry of the dolerite bodies. Mapping at a 1:10,000 scale reveals that the intrusions trend NE–SE and dip at 30°–40°, with localized variations due to erosional exposure of the host granite. GPR profiles identify structural discontinuities, including inclined and intense fractures extending up to 10 m depth, characterized by strong electromagnetic reflectors. A 3D geological model developed using Move software estimates the total geocellular volume of dolerite at ~13 million m3. The model aids in delineating subsurface geometry, optimizing quarry planning, and reducing initial exploration costs. It further enables identifying zones containing high-quality dolerite, minimizing the need for explosives and improving block extraction efficiency. The study demonstrates the value of integrating structural analysis, geophysics, and remote sensing for understanding emplacement dynamics and resource evaluation of mafic intrusions in tectonically active settings. Research Highlights <UnorderedList Mark="Bullet"> <ItemContent> Dolerite intrusions in Chamyal Valley trend NE–SE and dip 30°–40° to the northeast. </ItemContent> <ItemContent> GPR imaging distinguishes fractured (high reflectivity) and massive (low reflectivity) zones. </ItemContent> <ItemContent> 3D Move modelling estimates ~13 million m³ of dolerite with steeper dips at depth. </ItemContent> <ItemContent> Integrated mapping and GPR improve quarry planning and block extraction efficiency. </ItemContent> <ItemContent> Future integration of ERT, seismic, and coring will enhance subsurface characterization. </ItemContent> </UnorderedList>

Structural setup of dolerite intrusions in granite: A case study of Chamyal Valley, District Mansehra, Pakistan

期刊论文
发表日期：

2025年11月14日

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Noor Ul Islam,
Sarfraz Khan,
Gohar Rehman,
Liang Qiu,
Taqweem Ul Haq Ali,
Rafique Ahmad,
Hussain Ahmed

摘要

Abstract

Dolerite intrusions in the Chamyal Valley of northern Pakistan are emplaced as dykes and sills within the Cambrian Mansehra Granite and are associated with Permian rifting during the breakup of Gondwana. The valley, situated within the northern Hazara Ranges of the Lesser Himalayas, is structurally bounded by the Panjal Fault, Main Mantle Thrust (MMT), Main Boundary Thrust (MBT), and the Indus River. This study integrates geological field mapping, ground penetrating radar (GPR), and drone-based remote sensing to investigate the structural emplacement and 3D geometry of the dolerite bodies. Mapping at a 1:10,000 scale reveals that the intrusions trend NE–SE and dip at 30°–40°, with localized variations due to erosional exposure of the host granite. GPR profiles identify structural discontinuities, including inclined and intense fractures extending up to 10 m depth, characterized by strong electromagnetic reflectors. A 3D geological model developed using Move software estimates the total geocellular volume of dolerite at ~13 million m³. The model aids in delineating subsurface geometry, optimizing quarry planning, and reducing initial exploration costs. It further enables identifying zones containing high-quality dolerite, minimizing the need for explosives and improving block extraction efficiency. The study demonstrates the value of integrating structural analysis, geophysics, and remote sensing for understanding emplacement dynamics and resource evaluation of mafic intrusions in tectonically active settings.

Research Highlights

Dolerite intrusions in Chamyal Valley trend NE–SE and dip 30°–40° to the northeast.

GPR imaging distinguishes fractured (high reflectivity) and massive (low reflectivity) zones.

3D Move modelling estimates ~13 million m³ of dolerite with steeper dips at depth.

Integrated mapping and GPR improve quarry planning and block extraction efficiency.

Future integration of ERT, seismic, and coring will enhance subsurface characterization.