Evidence for partial melting and alkali-rich fluids in the crust from a 3-D electrical resistivity model in the vicinity of the Coqen region, western Lhasa terrane, Tibetan Plateau

Sheng, Yue; Jin, Sheng; Comeau, Matthew J.; Hou, Zhenshan; Becken, Michael; Dong, Hui; Zhang, Letian; Wei, Wenbo; Ye, Gaofeng

doi:10.1016/j.epsl.2023.118316

Cited by 4 publications

(3 citation statements)

References 57 publications

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“…However, some variations in rock composition (e.g., chemistry) may influence only one parameter. For example, an increase in the sodium content of a partial melt (e.g., Comeau et al., 2016), miniscule amounts of saline fluids in the crust (e.g., Sheng et al., 2023), or magmatic‐hydrothermal fluid flow that causes hydrothermal alteration and sulfide enrichment will strongly decrease the electrical resistivity but will not affect the velocity in a measurable way (Unsworth & Rondenay, 2012).…”

Section: Resultsmentioning

confidence: 99%

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Insights Into the Structure of the Mongol‐Okhotsk Suture Zone, Adaatsag Ophiolite, and Tectonic Boundaries of the Central Asian Orogenic Belt (Mongolia) From Electrical Resistivity Imaging and Seismic Velocity Models

Comeau,

Rigaud,

Batmagnai

et al. 2024

JGR Solid Earth

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The Mongol‐Okhotsk suture and the Adaatsag ophiolite belt are associated with the closure of the Mongol‐Okhotsk paleo‐ocean and are located within the Central Asian Orogenic Belt (CAOB) and Mongolia. The suture zone is flanked by volcanic‐plutonic belts that host significant metallogenic zones, containing deposits of copper and gold. The tectonic evolution of this region is not fully understood and the lithospheric structure has been poorly studied. We analyze magnetotelluric data and generate a model of the electrical resistivity distribution across this region. Whereas the northern segment has a sharp transition from a high‐resistivity upper crust to a low‐resistivity lower crust, as observed beneath the Hangai Dome, the southern segment does not show this transition. A wide, low‐resistivity zone (1–100 Ωm) imaged in the crust and lithospheric mantle is coincident with the Mongol‐Okhotsk suture and ophiolite, revealing a clear and significant lithospheric‐scale feature. Across the profile, numerous narrow, vertically oriented, low‐resistivity features (1–100 Ωm) are spatially associated remarkably well with the proposed boundaries of tectonic domains. These results confirm ideas about the development of the CAOB. Some of these low‐resistivity features are beneath the surface locations of large mineral zones, and likely represent fossil fluid pathways. We show congruent seismic velocity models for comparison and the results show a large‐scale low‐velocity anomaly (decrease of 2%–3%) that correlates with the location of the low‐resistivity anomaly below the Mongol‐Okhotsk suture. The geophysical results, combined with geological and geochemical data, provide insights into the structure of this region and help shed light on unanswered questions.

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Section: Resultsmentioning

confidence: 99%

“…Therefore, this interpretation does not adequately satisfy both geophysical anomalies. However, the addition of a minuscule amount of saline fluids can reduce the amount of partial melt required (e.g., Sheng et al., 2023; Unsworth & Rondenay, 2012).…”

Section: Discussionmentioning

confidence: 99%

Insights Into the Structure of the Mongol‐Okhotsk Suture Zone, Adaatsag Ophiolite, and Tectonic Boundaries of the Central Asian Orogenic Belt (Mongolia) From Electrical Resistivity Imaging and Seismic Velocity Models

Comeau,

Rigaud,

Batmagnai

et al. 2024

JGR Solid Earth

Self Cite

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“…Furthermore, the alkali-rich, volatile-rich and/or water-rich melts (e.g., anatexis in the crust) also contribute to most types of ore deposits [6,[53][54][55][56][57][58][59]. During or after mineralization, these volatile residues may form a chlorate, sulfide and/or graphite film under specific temperature and pressure conditions, which can increase the conductivity of the rock system [13,14,60]. The ore deposits form in a specific geological time and the metallogenic events are transient; however, the most important features of metallogenic systems are shaped before the mineralization or a long period after the metallogenic event, and the evolution of metallogenic systems may be preserved for hundreds of millions to billions of years [2,12].…”

Section: Connecting the Electrical Resistivity Model Of Lithosphere A...mentioning

confidence: 99%

A Review of Relationship between the Metallogenic System of Metallic Mineral Deposits and Lithospheric Electrical Structure: Insight from Magnetotelluric Imaging

Jin,

Sheng,

Liu

et al. 2024

Minerals

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In development over 70 years, magnetotelluric (MT) sounding, a high-resolution technique for subsurface electrical resistivity imaging, has been widely applied in resource exploration in the Earth. The key factors of the metallogenic system of metallic mineral deposits can be closely correlated to the electrical anomalies of the lithosphere. In this paper, we review the relationship between the electrical resistivity model of the lithosphere and the metallogenic system. At the beginning, we indicate why the electrical parameters relate to the metallogenic system in all geophysical parameters. The advantage of MT sounding in sketching an electrical resistivity model of the lithosphere is subsequently discussed, and some methods of data processing, analysis and inversion are also introduced. Furthermore, we summarize how to bridge the relationship between the electrical resistivity model of the lithosphere and metallogenic system, and analyze the influence of the rheological variation estimated from conductivity in the lithosphere on mineralization. In the end, we list some typical cases of the application of MT sounding in mineral exploration, and also give some suggestions for future work. This study is aimed at providing guidance in discussing the metallogenic system using an electrical resistivity model.

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Lateral electrical conductivity variations along the Main Himalayan thrust in the northwestern Himalayas: Insights from 3D Magnetotelluric forward modeling

Dhamodharan,

Raju,

Patro

2024

Physics of the Earth and Planetary Interiors

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Evidence for partial melting and alkali-rich fluids in the crust from a 3-D electrical resistivity model in the vicinity of the Coqen region, western Lhasa terrane, Tibetan Plateau

Cited by 4 publications

References 57 publications

Insights Into the Structure of the Mongol‐Okhotsk Suture Zone, Adaatsag Ophiolite, and Tectonic Boundaries of the Central Asian Orogenic Belt (Mongolia) From Electrical Resistivity Imaging and Seismic Velocity Models

Insights Into the Structure of the Mongol‐Okhotsk Suture Zone, Adaatsag Ophiolite, and Tectonic Boundaries of the Central Asian Orogenic Belt (Mongolia) From Electrical Resistivity Imaging and Seismic Velocity Models

A Review of Relationship between the Metallogenic System of Metallic Mineral Deposits and Lithospheric Electrical Structure: Insight from Magnetotelluric Imaging

Lateral electrical conductivity variations along the Main Himalayan thrust in the northwestern Himalayas: Insights from 3D Magnetotelluric forward modeling

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