Satellite-derived mineral mapping and monitoring of weathering, deposition and erosion

Abstract

The Earth’s surface comprises minerals diagnostic of weathering, deposition and erosion. The first continental-scale mineral maps generated from an imaging satellite with spectral bands designed to measure clays, quartz and other minerals were released in 2012 for Australia. Here we show how these satellite mineral maps improve our understanding of weathering, erosional and depositional processes in the context of changing weather, climate and tectonics. The clay composition map shows how kaolinite has developed over tectonically stable continental crust in response to deep weathering during northwardly migrating tropical conditions from 45 to 10 Ma. The same clay composition map, in combination with one sensitive to water content, enables the discrimination of illite from montmorillonite clays that typically develop in large depositional environments over thin (sinking) continental crust such as the Lake Eyre Basin. Cutting across these clay patterns are sandy deserts that developed <10 Ma and are well mapped using another satellite product sensitive to the particle size of silicate minerals. This product can also be used to measure temporal gains/losses of surface clay caused by periodic wind erosion (dust) and rainfall inundation (flood) events. The accuracy and information content of these satellite mineral maps are validated using published data.

Visible and Near-Infrared Reflectance Spectroscopy for Investigating Soil Mineralogy: A Review

“…ese absorption bands are caused by vibrational transitions and commonly display sharp and narrow features ( Figure 4). e diagnostic bands are mainly focused on ∼1400 nm (overtones caused by OH), ∼1900 nm (overtones caused by molecular water), and ∼2200 nm (combination tones caused by Al-OH [50,51]).…”

“…e geometric features of the spectra are more suitable for monitoring the molecular structural changes of soil minerals, since the variations of the absorption bands are caused by electron transitions (e.g., Fe 2+ to Fe 3+ ) and molecular vibration (e.g., Al-OH versus H 2 O). us, spectral measurement is widely and successfully applied to (1) measure mineral physicochemistry that is sensitive to changes in metamorphic grade [53,81], (2) map and monitor mineral erosion, deposition, and weathering of minerals [24,51], and (3) explore water and potential life on extraterrestrial objects [10,21]. Chemometric methods are more often used in monitoring overall soil properties, since almost all of the signals in the VNIR domain are involved in the modeling process.…”

Satellite ASTER Mineral Mapping the Provenance of the Loess Used by the Ming to Build their Earthen Great Wall

“…ASTER's publicly available, global data archive presents us with the future opportunity to extend our mapping and understanding of loess-related mineral transport pathways beyond our current study area (Figure 1a), especially northwards across the Ulan Buh and Gobi Deserts, westwards towards the Taklamakan Desert, and southwestwards over Tibetan Plateau and Qaidam Basin. It also provides the wider geoscience community with the unprecedented opportunity to map and understand a range of other earth science challenges, including temporal monitoring of soil loss and the related process of desertification [98][99][100][101].…”

Satellite Monitoring the Spatial-Temporal Dynamics of Desertification in Response to Climate Change and Human Activities across the Ordos Plateau, China

“…Particularly, the fraction of green vegetation cover, which can be calculated by the normalized difference vegetation index (NDVI), is now one of the two global indicators required for reporting by governments, according to the United Nations Convention to Combat Desertification (UNCCD) [18]. Landsat and similar satellite instruments can be used to measure and map NDVI, but their spectral bands are less suited for measuring both dry vegetation and bare soil components [19] which are more common surface components in dryland regions such as the Ordos Plateau. Thus, monitoring or assessing desertification using NDVI time series alone in dryland regions is problematic [20].…”