Sentinel-1 and ALOS data for lineament extraction: a comparative study

Abstract

GREENPEG is a H2020 project developing exploration toolsets for critical materials in pegmatites. Lineament mapping is a powerful tool to identify geological structures at different scales, which is commonly applied in mineral exploration. To extract lineament information, different types of data can be employed, namely: (i) optical remote sensing data, (ii) radar remote sensing data, and (iii) digital elevation models (DEMs). All these data have been used by GREENPEG, where image processing of Sentinel-1 and ALOS (DEM) datasets were evaluated to identify regional-scale tectonic structures, such as faults, that may have controlled pegmatite melt emplacement. Automated geomatics methods to extract lineament information and perform lineament mapping were employed and the mean direction of the extracted lineaments was evaluated through rose diagrams. In general, the results of the radar image processing were affected by noise in the coastal areas and by the topography of the region. ALOS data presented some advantages, due to less influence from topography and human structures (saving time in the visual inspection of the results). Moreover, even though higher thresholds for the minimum length to consider as a lineament were applied to Sentinel-1 images, ALOS-derived lineaments were longer. The main trend of the extracted lineaments is in agreement between the two datasets, although specific trends are clearer in the ALOS-derived lineaments because the shaded reliefs produced already filtered the azimuth of lineaments to be extracted according to light incidence angle. For all three project demonstration sites (Leinster, Ireland; Wolfsberg, Austria; and Tysfjord, Norway) it was possible to identify lineaments that may relate to structures that controlled pegmatite emplacement. This study demonstrates the usefulness of different satellite data in structural mapping and mineral exploration.

Automated lineament extraction applied to high-resolution imagery Worldview-3 and LiDAR data for pegmatite mineral exploration

“…The Sentinel 2 and WV3 had similar results concerning the main orientation (E-W), followed by a ENE-WSW trend (Figure 6 b), while the less expressive orientation for Sentinel 2, was SSE-NNW (Figure 6 c). Analysing the results, it is noticeable that the lineaments have an orientation pattern for E-W, ENE-WSW population in line with the results presented by Cardoso-Fernandes et al 13 . The results also show us a smaller orientation pattern corresponding to a N-S, NNE-SSW population, also highlighted by the same authors, that could match potential emplacement structures for Caledonian pegmatites.…”

“…The Svecofennian pegmatites derived from residual melts and underwent multiple deformation phases resulting in large-scale shearing of the pegmatite bodies, while the Caledonian pegmatites derived from partial melting of the Tysfjord granitic gneiss during late Caledonian events 11 . These younger pegmatites generally show a N-S strike parallel to inherited ancient Precambrian structures that were reactivated during the Caledonian orogeny and that could have served for pegmatite melt emplacement 12,13 . In the Tysfjord area, about 20 pegmatites were emplaced along several parallel or diverging structures in a 4 km long array which was presumably ductile during melt emplacement.…”

Mapping hydrothermal alterations and lineaments associated with epithermal and massive sulphides deposits of Tifraouine (northwest Algerian coast): Use of Landsat 8 OLI data and remote sensing

“…Geological mapping involved using typical absorption characteristics of chemical elements that compose minerals through spectral signatures in the spectral range (Pour and Hashim, 2015), that allows their detection and recognition. For example, montmorillonite shows absorptions around ~1413 nm and ~1911 nm, with the Al-OH features at ~2206 nm (Pontual et al, 2008;Clark et al, 1990), lower than ~1911 nm, and a slight inflection around ~1467 nm (Cardoso-Fernandes et al, 2022). Three bands can be effective in the mineral determination process.…”

Sentinel data for critical raw materials (CRM) exploration: first results of the S34I project

“…More recently, Earth Observation (EO) data from Copernicus satellite sensors, such as Sentinel-2, played an increasingly significant role in mineral mapping 4 . SAR data (such as Sentinel-1) are typically used to map structural elements 5 , but SAR can also be used for lithological mapping due to variations in outcrop patterns and the size and frequency of coarse rock detritus 6 . Thus, this works presents a preliminary attempt to use Copernicus Sentinel data to identify potential areas for CRM deposits, namely Co in the Aramo area (Spain) and metallic placers in Rias Baixas (Spain).…”