Rock alteration mapping in and around fossil shallow intrusions at Mt. Ruapehu New Zealand with laboratory and aerial hyperspectral imaging

Douglas, Abbey; Keresztúri, Gábor; Schaefer, Lauren N.; Kennedy, Ben

doi:10.1016/j.jvolgeores.2022.107700

Cited by 6 publications

(1 citation statement)

References 88 publications

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“…The instrument's data was calibrated using a White Diffuse Reflectance Standard [39] ,and 15-20 points measurements were measured each sample using a contact probe. It has the advantages of simple operation, low noise, high response speed, and high accuracy.…”

Section: End-member Extraction By Laboratory Spectral Measurementsmentioning

confidence: 99%

Hydromagnesite determination method based on Landsat8 and ZY1-02D data: A case study of the Jiezechaka Salt Lake in Tibet

Zhao,

Dai,

Zhao

et al. 2023

Preprint

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Hydromagnesite is a natural carbonate mineral that is widely distributed, but large sedimentary hydromagnesite deposits with industrial exploitation value are rare globally. In China, hydromagnesite is mainly distributed in the salt lake area of Qinghai-Tibet Plateau. Because of the harsh environment, it is difficult to use the traditional method to search for ore. Remote sensing technology has been successfully applied to research skarn, pegmatite lithium-beryllium, porphyry-epithermal, salt lake lithium, magmatic nickel-chromium, and orogenic gold deposits; however, research regarding remote sensing determination of hydromagnesite from salt lakes is lacking. We determined the mineral composition and content of hydromagnesite samples in the Jiezechaka area by X-ray diffraction (XRD), and the reflection spectral curve of the hydromagnesite samples was measured using an ASD FieldSpec4 short-wave infrared spectrometer. The analysis indicated three and seven absorption valleys with high and low absorption intensities, respectively, in the reflectance spectral curves of the hydromagnesite samples in the Jiezechaka area. Then, on this basis, we used Landsat8 OLI and ZY1-02D AHSI data, with the mixture tuned matched filtering (MTMF) method to extract hydromagnesite information around Jiezechaka Salt Lake in Tibet. A confusion matrix operation was used to compare the determination results of the two types of data. Among them, the overall accuracy of the extraction results based on Landsat8 data was > 67%, and the kappa coefficient was 0.668. The overall accuracy of the extraction results based on ZY1-02D data was > 72%, and the kappa coefficient was 0.743. Finally, using overlay analysis of the two kinds of data determination results, we concluded that hydromagnesite outcrops in the Jiezechaka area are mainly distributed in the northwestern and southeastern regions of the lake. This study provides a rapid assessment technique for measuring hydromagnesite information from salt lakes.

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Section: End-member Extraction By Laboratory Spectral Measurementsmentioning

confidence: 99%

Hydromagnesite determination method based on Landsat8 and ZY1-02D data: A case study of the Jiezechaka Salt Lake in Tibet

Zhao,

Dai,

Zhao

et al. 2023

Preprint

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Characterizing lithological, weathering, and hydrothermal alteration influences on volcanic rock properties via spectroscopy and laboratory testing: a case study of Mount Ruapehu volcano, New Zealand

et al. 2023

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The geomechanical characterization of volcanic material has important implications for geothermal and mineral exploration, engineering design, geophysical signals of volcano unrest, and models of instability and mass flows. Chemical weathering and hydrothermal systems can alter the host rock, leading to changes in mechanical behavior and failure mode. Here, we compare the physical and mechanical properties of lava, autoclastic breccia, and pyroclastic (scoria) rocks from Mount Ruapehu volcano (Ruapehu) in New Zealand to mineralogical composition determined via infrared spectroscopy and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). We use correlation matrices, principal component analysis, and parametric analysis to determine which parameters can be used to predict physical and mechanical properties and form the basis for transfer functions. Laboratory-based spectroscopy shows that the samples contain absorption features indicative of Al- and Mg-rich hydrous phyllosilicates (e.g., kaolinite, halloysite, montmorillonite), Fe- oxides (e.g., goethite), and sulfates attributed to surface weathering, supergene, and steam-heated alteration. We find that porosity and primary lithology are the predominant control on physical and mechanical properties, followed by the pervasiveness of weathering/alteration, and then mineralogical composition. Several properties, such as porosity, uniaxial compressive strength, P-wave seismic velocity, density, and Young’s modulus, show strong correlations with other properties, indicating the potential for transfer functions between these properties. Hydrothermally altered rocks near the vent complex (up to ~ 400 m depth beneath the crater lake) with high-intensity hydrothermal alteration do not follow typical physical and mechanical property trends due to high clay content, low permeability, and low strength. The presence of these rocks within the edifice at Ruapehu implies local barriers to fluid flow and subsequent pore pressure variations. Additionally, they may have less than half the strength than would be dictated by typical porosity-strength trends for surface rocks, increasing the likelihood of structural failure. Trends in the pervasiveness of weathering with physical and mechanical properties, along with shifts in the position of spectral absorption peaks as hydrothermal/weathering alteration increases, suggest that it may be possible to extrapolate properties from imaging spectroscopy.

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MTMF Method for Hydromagnesite Determination Based on Landsat8 and ZY1-02D Data: A Case Study of the Jiezechaka Salt Lake in Tibet

Zhao,

Dai,

Zhao

et al. 2024

Aquat Geochem

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Rock alteration mapping in and around fossil shallow intrusions at Mt. Ruapehu New Zealand with laboratory and aerial hyperspectral imaging

Cited by 6 publications

References 88 publications

Hydromagnesite determination method based on Landsat8 and ZY1-02D data: A case study of the Jiezechaka Salt Lake in Tibet

Hydromagnesite determination method based on Landsat8 and ZY1-02D data: A case study of the Jiezechaka Salt Lake in Tibet

Characterizing lithological, weathering, and hydrothermal alteration influences on volcanic rock properties via spectroscopy and laboratory testing: a case study of Mount Ruapehu volcano, New Zealand

MTMF Method for Hydromagnesite Determination Based on Landsat8 and ZY1-02D Data: A Case Study of the Jiezechaka Salt Lake in Tibet

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