Modeling and assessment of wavelength displacements of characteristic absorption features of common rock forming minerals encrusted by lichens

Salehi, Sara; Rogge, Derek; Rivard, Benoît; Heincke, Björn; Fensholt, Rasmus

doi:10.1016/j.rse.2017.06.044

Cited by 16 publications

(11 citation statements)

References 31 publications

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“…The amphibole group minerals have MgOH absorption features at approximately 2300 and 2380 nm and chlorite group minerals show diagnostic absorption feature around 2254 nm [91,94]. The broad red curved lines observed in the absorption feature depth maps in Søndre Strømfjord region are instrument related artifacts (Figure 8).…”

Section: Hyperspectral Classificationmentioning

confidence: 99%

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Integration of Vessel-Based Hyperspectral Scanning and 3D-Photogrammetry for Mobile Mapping of Steep Coastal Cliffs in the Arctic

et al. 2018

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Abstract:Remote and extreme regions such as in the Arctic remain a challenging ground for geological mapping and mineral exploration. Coastal cliffs are often the only major well-exposed outcrops, but are mostly not observable by air/spaceborne nadir remote sensing sensors. Current outcrop mapping efforts rely on the interpretation of Terrestrial Laser Scanning and oblique photogrammetry, which have inadequate spectral resolution to allow for detection of subtle lithological differences. This study aims to integrate 3D-photogrammetry with vessel-based hyperspectral imaging to complement geological outcrop models with quantitative information regarding mineral variations and thus enables the differentiation of barren rocks from potential economic ore deposits. We propose an innovative workflow based on: (1) the correction of hyperspectral images by eliminating the distortion effects originating from the periodic movements of the vessel; (2) lithological mapping based on spectral information; and (3) accurate 3D integration of spectral products with photogrammetric terrain data. The method is tested using experimental data acquired from near-vertical cliff sections in two parts of Greenland, in Karrat (Central West) and Søndre Strømfjord (South West). Root-Mean-Square Error of (6.7, 8.4) pixels for Karrat and (3.9, 4.5) pixels for Søndre Strømfjord in X and Y directions demonstrate the geometric accuracy of final 3D products and allow a precise mapping of the targets identified using the hyperspectral data contents. This study highlights the potential of using other operational mobile platforms (e.g., unmanned systems) for regional mineral mapping based on horizontal viewing geometry and multi-source and multi-scale data fusion approaches.

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Section: Hyperspectral Classificationmentioning

confidence: 99%

“…Wavelength positions of deepest absorption features around 2200 nm are indicative of mica group minerals [87,[91][92][93]. The amphibole group minerals have MgOH absorption features at approximately 2300 and 2380 nm and chlorite group minerals show diagnostic absorption feature around 2254 nm [91,94].…”

Section: Hyperspectral Classificationmentioning

confidence: 99%

Integration of Vessel-Based Hyperspectral Scanning and 3D-Photogrammetry for Mobile Mapping of Steep Coastal Cliffs in the Arctic

et al. 2018

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“…Other selected VNIR bands allow capturing the shape of overall spectral to map non-geological materials including rock incrusting lichens and vegetation that supress bedrock mineralogy. To capture the broad absorption features related to lichens the 1.73, 2.11, 2.30 µm are included in the selected bands (Rogge et al, 2014a;Salehi et al, 2017b).…”

Section: Resultsmentioning

confidence: 99%

“…Another important factor in using remote sensing technology for mineral exploration is the selection of the most optimal approaches for mapping based on environmental conditions. One limitation of current state-of-the-art methods is the sub-pixel spectral mixture of lichens and rocks that can have an adverse effect on identifying rocks and minerals using imaging sensor systems (Salehi et al, 2017b). Since the nineties, there have been a number of studies that have investigated the potential of using airborne and simulated spaceborne hyperspectral data for discrimination of mafic and ultramafic rocks in the Canadian north, where rocks are exposed in presence of lichens (Harris et al, 2005;Rogge et al, 2014b).…”

Section: Introductionmentioning

confidence: 99%

Mapping ultramafic complexes using airborne imaging spectroscopy and spaceborne data in Arctic regions with abundant lichen cover, a case study from the Niaqornarssuit complex in South West Greenland

Salehi

Mielke

Rogaß

2020

European Journal of Remote Sensing

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“…These patterns are often caused by the hydroxyl group and can be characteristic for the presence of lichen, which are abundant in arctic environments (Salehi et al, 2017).…”

Section: Ground-based Spectroscopy and Magnetic Susceptibilitymentioning

confidence: 99%

Drone-based magnetic and multispectral surveys to develop a 3D model for mineral exploration at Qullissat, Disko Island, Greenland

Jackisch

Heincke

Zimmermann

et al. 2021

Preprint

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Abstract. Mineral exploration in the West Greenland flood basalt province is attractive because of its resemblance to the magmatic sulphide-rich deposit in the Russian Norilsk region, but it is challenged by rugged topography and partly poor exposure for relevant geologic formations. On northern Disko Island, previous exploration efforts have identified rare native iron occurrences and a high potential for Ni-Cu-Co-PGE-Au mineralization. However, Quaternary landslide activity has obliterated rock exposure at many places at lower elevations. To augment prospecting field work under these challenging conditions, we acquire high-resolution magnetic and optical remote sensing data using drones in the Qullissat area. From the data, we generate a detailed 3D model of a mineralized basalt unit, belonging to the Asuk Member (Mb) of the Palaeocene Vaigat formation. A wide range of legacy data and newly acquired geo- and petrophysical, as well as geochemical-mineralogical measurements form the basis of an integrated geological interpretation of the unoccupied aerial system (UAS) surveys. In this context, magnetic data aims to define the location and the shape of the buried magmatic body, and to estimate if its magnetic properties are indicative for mineralization. High-resolution UAS-based multispectral orthomosaics are used to identify surficial iron staining, which serve as a proxy for outcropping sulphide mineralization. In addition, high-resolution UAS-based digital surface models are created for geomorphological characterisation of the landscape to accurately reveal landslide features. UAS-based magnetic data suggests that the targeted magmatic unit is characterized by a pattern of distinct positive and negative magnetic anomalies. We apply a 3D magnetization vector inversion model (MVI) on the UAS-based magnetic data to estimate the magnetic properties and shape of the magmatic body. By means of using constraints in the inversion, (1) optical UAS-based data and legacy drill cores are used to assign significant magnetic properties to areas that are associated with the mineralized Asuk Mb, and (2) the Earth’s magnetic and the paleomagnetic field directions are used to evaluate the general magnetization direction in the magmatic units. Our results indicate that the geometry of the mineralized target can be estimated as a horizontal sheet of constant thickness, and that the magnetization of the unit has a strong remanent component formed during a period of Earth’s magnetic field reversal. The magnetization values obtained in the MVI are in a similar range as the measured ones from a drillcore intersecting the targeted unit. Both the magnetics and topography confirm that parts of the target unit were displaced by landslides. We identified several fully detached and presumably rotated blocks in the obtained model. The model highlights magnetic anomalies that correspond to zones of mineralization and is used to identify outcrops for sampling. Our study demonstrates the potential and efficiency of using multi-sensor high-resolution UAS data to constrain the geometry of partially exposed geological units and assist exploration targeting in difficult, poorly exposed terrain.

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Modeling and assessment of wavelength displacements of characteristic absorption features of common rock forming minerals encrusted by lichens

Cited by 16 publications

References 31 publications

Integration of Vessel-Based Hyperspectral Scanning and 3D-Photogrammetry for Mobile Mapping of Steep Coastal Cliffs in the Arctic

Integration of Vessel-Based Hyperspectral Scanning and 3D-Photogrammetry for Mobile Mapping of Steep Coastal Cliffs in the Arctic

Mapping ultramafic complexes using airborne imaging spectroscopy and spaceborne data in Arctic regions with abundant lichen cover, a case study from the Niaqornarssuit complex in South West Greenland

Drone-based magnetic and multispectral surveys to develop a 3D model for mineral exploration at Qullissat, Disko Island, Greenland

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