Sedimentary Setting and Ore-Forming Model in the Songtao Manganese Deposit, Southwestern China: Evidence from Audio-Frequency Magnetotelluric and Gravity Data

The break-up of the supercontinent Rodinia in the late Neoproterozoic led to the formation of the Nanhua rift basin within the South China Block. The Datangpo-type manganese deposit, which developed in the Nanhua rift basin, is one of the most important types of manganese deposits in South China. Although it is widely accepted that deep sedimentary structures significantly affect the manganese ore system, the relationship between the manganese deposits in South China and the Nanhua rifting process is still unclear. The origin of the manganese ore layer remains controversial. In this paper, we integrated the audio-frequency magnetotelluric (AMT) data, gravity data, and comprehensive geological and borehole data analysis to characterize the structure of the Datangpo-type manganese deposit in Songtao, Guizhou Province. The resistivity and density models produced an inclined layered structure, which correlated well with the coeval sediment strata of the Nanhua rift basin. A high-resistivity cap was observed from the surface to a depth of 800 m, corresponding to the Cambrian Loushanguan (ϵ3−4ls) and Palang dolomite formation (ϵ2p), which has helped the storage of the manganese ore. The most significant low-resistivity anomaly (25–40 Ω·m) resides at a depth of 1400 m in the Nantuo (Nh3n) gravel sandstone and Datangpo (Nh2d) silty and carbonaceous shale, corresponding to the ore-forming layer. This distinct low-resistivity layer was possibly produced by aqueous fluids and pyrite in the syn-sedimentary fault and alteration zone. The accumulations of sulfide minerals in the rock samples suggest a possible anoxic-euxinic deposition environment during the manganese mineralization and precipitation. The fault revealed in the resistivity models is perhaps a previous fault zone produced by extension in the Nanhua rifting process, which provided migration and upwelling channels for ore-forming minerals. Based on our resistivity models, density models, and geological survey, the manganese ore-forming model was derived, which can help to provide geophysical evidence for the origin of the Datangpo-type manganese deposit.

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Geophysical characterization of the Menengai volcano, Central Kenya Rift from the analysis of magnetotelluric and gravity data

Geophysics ◽

10.1190/geo2011-0419.1 ◽

2013 ◽

Vol 78 (4) ◽

pp. B187-B199 ◽

Cited By ~ 2

Author(s):

Antony Munika Wamalwa ◽

Kevin L. Mickus ◽

Laura F. Serpa

Keyword(s):

Gravity Data ◽

Gravity Models ◽

High Resistivity ◽

Geothermal System ◽

Low Density ◽

Fracture Density ◽

Density Region ◽

Magnetotelluric Data ◽

Low Resistivity ◽

2D Resistivity

In this study, we qualitatively analyze detailed gravity and broadband magnetotelluric data in and surrounding the Menengai volcano of the East African rift in Kenya to assess geothermal potential of the region. Three-dimensional gravity models obtained by inverting residual gravity anomalies and 2D resistivity models obtained by inverting the transverse electric and transverse magnetic magnetotelluric modes show several common features. Our models show that a low-resistivity zone above a higher resistivity zone correlates with a low-density region located 1–4 km beneath the volcano. These zones may be related to a high temperature gradient or hydrothermally altered, fractured rocks. Additionally, a low-resistivity ([Formula: see text]) and a low-density region located approximately 4–6 km below the volcano may be related to molten material that is the source of heat for the geothermal system. The low-resistivity ([Formula: see text]) regions that correlated with a denser ([Formula: see text]) region within the caldera are bounded by high-resistivity ([Formula: see text]), high-density ([Formula: see text]) volcanic units implying that the dense and electrically resistive volcanic material is relatively cool and lacks significant fluid content that can lower resistivity. At shallow depths, 0.5–1.5 km below the caldera, a low-resistivity and low-to-moderate density region is interpreted as a zone with high fracture density that consists of clay minerals resulting from hydrothermal alteration. These results agree well with the results from previous seismic studies on the depth of the suggested molten rocks.

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Geochronology and paleoenvironment of the pre-Sturtian glacial strata: Evidence from the Liantuo Formation in the Nanhua rift basin of the Yangtze Block, South China

Precambrian Research ◽

10.1016/j.precamres.2013.04.012 ◽

2013 ◽

Vol 233 ◽

pp. 118-131 ◽

Cited By ~ 26

Author(s):

Qiuding Du ◽

Zhengjiang Wang ◽

Jian Wang ◽

Yansheng Qiu ◽

Xinsheng Jiang ◽

...

Keyword(s):

South China ◽

Rift Basin ◽

Yangtze Block ◽

Nanhua Rift

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Metallogenic mechanism of large manganese deposits from Permian manganese ore belt in western South China Block: New mineralogical and geochemical evidence

Ore Geology Reviews ◽

10.1016/j.oregeorev.2021.103993 ◽

2021 ◽

pp. 103993

Author(s):

Hai Xu ◽

Junbo Gao ◽

Ruidong Yang ◽

Kangning Feng ◽

Longbo Wang ◽

...

Keyword(s):

South China ◽

Manganese Ore ◽

South China Block ◽

Geochemical Evidence ◽

Manganese Deposits ◽

Metallogenic Mechanism

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SPECTRAL ANALYSIS WITH PIECEWISE REGRESSION APPROACH (SAPRA) OF GRAVITY DATA FOR LITHOSPHERIC STRUCTURE IMAGING: THE LAKE TURKANA RIFT BASIN OF THE EAST AFRICAN RIFT SYSTEM

10.1130/abs/2020am-359495 ◽

2020 ◽

Author(s):

Luelseged Emishaw ◽

◽

Kevin L. Mickus ◽

Mohamed G. Abdelsalam

Keyword(s):

Gravity Data ◽

Rift System ◽

Lithospheric Structure ◽

Rift Basin ◽

East African Rift System ◽

East African ◽

Lake Turkana ◽

Piecewise Regression ◽

Regression Approach ◽

African Rift

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Studying the Depth Structure of the Kyrgyz Tien Shan by Using the Seismic Tomography and Magnetotelluric Sounding Methods

Geosciences ◽

10.3390/geosciences11030122 ◽

2021 ◽

Vol 11 (3) ◽

pp. 122

Author(s):

Irina Medved ◽

Elena Bataleva ◽

Michael Buslov

Keyword(s):

Seismic Tomography ◽

High Velocity ◽

Fault Zones ◽

Magnetotelluric Sounding ◽

Tien Shan ◽

High Resistivity ◽

Low Velocity ◽

Low Resistivity ◽

Velocity Models ◽

Fluid Saturation

This paper presents new results of detailed seismic tomography (ST) on the deep structure beneath the Middle Tien Shan to a depth of 60 km. For a better understanding of the detected heterogeneities, the obtained velocity models were compared with the results of magnetotelluric sounding (MTS) along the Kekemeren and Naryn profiles, running parallel to the 74 and 76 meridians, respectively. We found that in the study region the velocity characteristics and geoelectric properties correlate with each other. The high-velocity high-resistivity anomalies correspond to the parts of the Tarim and Kazakhstan-Junggar plates submerged under the Tien Shan. We revealed that the structure of the Middle Tien Shan crust is conditioned by the presence of the Central Tien Shan microcontinent. It manifests itself as two anomalies lying one below the other: the lower low-velocity low-resistivity anomaly, and the upper high-velocity high-resistivity anomaly. The fault zones, limiting the Central Tien Shan microcontinent, appear as low-velocity low-resistivity anomalies. The obtained features indicate the fluid saturation of the fault zones. According to the revealed features of the Central Tien Shan geological structure, it is assumed that the lower-crustal low-velocity layer can play a significant role in the delamination of the mantle part of the submerged plates.

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Mineralogy and crystal structure studies of the manganese oxide in Xiangtan manganese deposit, South China and its preliminary application on absorption and catalysis of formaldehyde

10.7185/gold2021.5674 ◽

2021 ◽

Author(s):

Liqun Zhao ◽

Sida Niu ◽

Lei Li ◽

Xianglong Niu ◽

Huaying Wu ◽

...

Keyword(s):

Crystal Structure ◽

Manganese Oxide ◽

South China ◽

Manganese Deposit ◽

Preliminary Application

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The Effects of Current Leakage on Electroadhesion Forces in Rolling Friction and Magnetic Flux Density Distribution on the Surface of Rolling Element Bearings

Journal of Tribology ◽

10.1115/1.3261649 ◽

1988 ◽

Vol 110 (3) ◽

pp. 448-455 ◽

Cited By ~ 18

Author(s):

Har Prashad

Keyword(s):

Magnetic Flux ◽

Flux Density ◽

Rolling Friction ◽

High Resistivity ◽

Magnetic Flux Density ◽

Rolling Element Bearings ◽

Electrical Fields ◽

Low Resistivity ◽

Pure Rolling ◽

Rolling Element

The present work deals with the investigations carried out on the various rolling element bearings after being operated under the influence of electric fields, and pure rolling friction on the roller bearing test machine. The significant magnetic flux density was detected on surfaces of the bearings lubricated with low-resistivity grease under the influence of electrical fields. No such phenomenon was observed either on bearings using high or low-resistivity greases under pure rolling friction or on bearings lubricated with high-resistivity grease under the influence of electrical fields. New bearing surfaces do not show significant magnetic flux density but it has been detected after long operation on different motor bearings, lubricated with low resistivity greases. The electroadhesion forces in the bearings using low-resistivity greases increase under the influence of electrical fields in contrast to those with high resistivity greases. Under pure rolling friction resistivity of greases do not affect the electroadhesion forces. The investigations reported in this paper along with the study of damaged/corrugated surfaces, and deterioration of the used greases [1, 2, 3], the leakage of current leading to failure of the noninsulated motor bearings can be established.

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The Role of Hydrothermal Activity in the Formation of Karst-Hosted Manganese Deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa

Minerals ◽

10.3390/min9070408 ◽

2019 ◽

Vol 9 (7) ◽

pp. 408

Author(s):

Brenton J. Fairey ◽

Martin J. Timmerman ◽

Masafumi Sudo ◽

Harilaos Tsikos

Keyword(s):

Hydrothermal Fluid ◽

Hydrothermal Activity ◽

Ore Deposits ◽

Manganese Ore ◽

High Grade ◽

Ore Formation ◽

Manganese Ores ◽

Manganese Deposits ◽

Northern Cape

The Postmasburg Manganese Field (PMF), Northern Cape Province, South Africa, once represented one of the largest sources of manganese ore worldwide. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes and metasomatic alteration towards ore formation has not been adequately discussed. Here we report an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in Mn ores of the PMF, indicative of hydrothermal influence. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for most samples analysed through bulk-rock techniques. The presence of As-rich tokyoite also suggests the presence of As and V in the hydrothermal fluid. The fluid was likely oxidized and alkaline in nature, akin to a mature basinal brine. Various replacement textures, particularly of Na- and K- rich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as ore-minerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and their deviation from the strict classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. New Ar-Ar ages for K-feldspars suggest a late Neoproterozoic timing for hydrothermal activity. This corroborates previous geochronological evidence for regional hydrothermal activity that affected Mn ores at the PMF but also, possibly, the high-grade Mn ores of the Kalahari Manganese Field to the north. A revised, all-encompassing model for the development of the manganese deposits of the PMF is then proposed, whereby the source of metals is attributed to underlying carbonate rocks beyond the Reivilo Formation of the Campbellrand Subgroup. The main process by which metals are primarily accumulated is attributed to karstification of the dolomitic substrate. The overlying Asbestos Hills Subgroup banded iron formation (BIF) is suggested as a potential source of alkali metals, which also provides a mechanism for leaching of these BIFs to form high-grade residual iron ore deposits.

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