Geologic structures associated with gold mineralization in the Kirk Range area in Southern Malawi

Abstract In this contribution, we use a newly acquired high-resolution airborne geophysical data set and field geological investigations in the Kirk Range area in southern Malawi to understand structures that control gold mineralization. Gold in this area is alluvial, mined by artisanal miners and detailed information regarding the structures controlling primary mineralization remains sparse. Structural interpretations are afforded by in-depth investigation of airborne magnetic and radiometric data, which are then supported by ground geological mapping and by microscopic observations using X-ray computed tomography (XCT) and optical microscopy. The results show that the Kirk Range displays extensive faulting and shearing with a NE–SW trend as the prevalent structural grain of the region. Gold mineralization is hosted in NE–SW trending structures. The wall rock alteration associated with gold mineralization results in a pronounced K/Th anomaly, which is suggested as an important radiometric guide for future exploration efforts. Exploration in the Kirk Range region should focus on the NE–SW structures, which represent potential conduits for fluid flow.

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Geological mapping and mineral prospectivity using remote sensing and GIS in parts of Hamissana, Northeast Sudan

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01115-3 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1123-1138

Author(s):

Mohamed Taha AlMakki Mohamed ◽

Latifa Shaheen Al-Naimi ◽

Tochukwu Innocent Mgbeojedo ◽

Chidiebere Charles Agoha

Keyword(s):

Remote Sensing ◽

Gold Mineralization ◽

Principal Component ◽

Original Data ◽

Wall Rock ◽

Geological Mapping ◽

Landsat 8 ◽

Alteration Zones ◽

Wall Rock Alteration ◽

Rock Alteration

AbstractIn recent years, various geological activities and different mineral prospecting and exploration programs have been intensified along the Red Sea hills in order to elucidate the geological maps and to evaluate the mineral potentials. This study is therefore aimed at testing the viability of using remote sensing and geographic information system (GIS) techniques for geological mapping and prospecting for gold mineralization in the area. The study area is located in northeast Sudan and covers an area of about 1379 km2. Different digital image processing techniques were applied to Landsat 8 Operational Land Imager image in order to increase the discrimination between various lithological units and to delineate wall rock alteration which represents target zones for gold mineralization. Image sharpening was performed to enhance the spatial resolution of the images for more detailed information. Contrast stretching was applied after the various digital processing procedures to produce more interpretable images. The principal component analysis transformations yielded saturated images and resulted in more interpretable images than the original data. Several ratio images were prepared, combined together and displayed in RGB color composite ratio images. This process revealed the existence of alteration zones in the study area. These zones extend from the northeast to the southwest in the acid meta-volcanic and silica barite rocks. The enhanced satellite images were implemented in the GIS environment to facilitate the final production of the geological map at scale 1:400,000. X-ray fluorescence analyses prove that selected samples taken from the wall rock alteration zones are gold-bearing.

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Primary gold mineralization in the Lisungwe Valley area, Kirk Range, southern Malawi

South African Journal of Geology ◽

10.25131/sajg.122.0039 ◽

2019 ◽

Vol 122 (4) ◽

pp. 505-518 ◽

Cited By ~ 1

Author(s):

J. Chisambi ◽

B. von der Heyden

Keyword(s):

Gold Mineralization ◽

Regional Scale ◽

Wall Rock ◽

River Valley ◽

Geological Mapping ◽

Mobile Belt ◽

Tectonic Block ◽

South Central ◽

The Status ◽

Airborne Geophysical Data

Abstract A conspicuous paucity in gold resources in Malawi’s mineral inventory may be partially attributed to a general low resolution in the knowledge of Malawi’s geology, coupled with historical under-exploration for this important economic commodity. To address this knowledge gap, the present study focusses on developing a regional, local and microscopic understanding of the characteristics of gold occurrences in the mineralized Little Chisumbwiti river valley, located in the Kirk Range region which forms part of Southern Irumide mobile belt in southern Malawi. Regional scale interpretations are afforded by in-depth investigation of airborne geophysical data, which are then supported by ground geological mapping and by microscopic observations using optical and electron microscopy, and X-ray computed tomography (XCT). Structural mapping and regional geophysics indicate that the area has been affected by at least two periods of deformation (D1 to D2). The D1 deformation event is characterized by northwest – southeast directed crustal shortening (tentatively associated with the Southern Irumide orogeny) which produced northeast – southwest structures. Gold mineralization in the Little Chisumbwiti river valley is hosted in northeast – southwest trending quartz—sulphide vein sets, where it occurs as flakes ranging in size between 0.24 and 4 mm. The gold is associated with a paragenetically-late pyrite-chalcopyrite-sphalerite generation of sulphide precipitation, and to a lesser extent, with sericitised biotite schist wall rock. Exploration in the Kirk Range region should focus on the northeast-southwest structures, which represent potential conduits for fluid flow during the D1-related hypogene Au mineralization event, however the impacts of subsequent D2 deformation must also be considered. Locally, wall rock lithology (e.g., Fe (II)-rich biotite schists) may have an additional second order control on the siting of gold mineralization. The new insights reported in this study contribute meaningfully towards advancing the status of Malawi’s regional geology and should serve as a useful resource for future exploration efforts undertaken in the Kirk Range, and in other parts of south/central Malawi occurring within the Southern Irumide tectonic block.

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