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Article: Reflectance spectroscopy applied to clay mineralogy and alteration intensity of a thick basaltic weathering sequence in Hainan Island, South China
Title | Reflectance spectroscopy applied to clay mineralogy and alteration intensity of a thick basaltic weathering sequence in Hainan Island, South China |
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Authors | |
Issue Date | 2021 |
Publisher | Elsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/clay |
Citation | Applied Clay Science, 2021, v. 201, article no. 105923 How to Cite? |
Abstract | Visible/Near Infrared Reflectance spectroscopy (350–2500 nm) is an efficient and effective tool to identify and semi-quantify clay minerals, Fe3+ (oxyhydr)oxides, and their crystal-chemistry/structure. Even so, there have been few studies systematically describing how spectroscopy can be applied to mineralogical evolution during weathering. This study investigated reflectance spectra of a long core of a thick basaltic weathering sequence in Hainan Island and a series of transformation products from montmorillonite to kaolinite to present spectral features associated with weathering trends. In combination with X-ray diffraction and geochemical results, mineralogical transitions and weathering intensity of the core samples were described from a spectroscopic perspective. Several different protoliths were spectroscopically recognized in the Hainan weathering sequence, consistent with geological observation and geochemical analysis. Overprinted on these multiple protoliths was a discernable weathering sequence observable by infrared spectroscopic methods. Clay minerals changed upwards in section from TOT type (nontronite) to TO type (kaolinite), and finally to O type (gibbsite) hydroxide clay-size particles as the result of gradual hydrolysis of silicates and leaching of mobile elements with weathering. The relative abundance of hydroxyl to interlayer water, observable by the band depth ratio of spectral absorptions around 1400 nm and 1900 nm (BD1400/BD1900), increased progressively and correlated positively with the chemical index of alteration and Al2O3 concentration. The increasing BD1400/BD1900 index value with weathering was the result of gradual leaching of interlayer cations (e. g. Na+, K+), and their water complexes within interlayers, and gradual formation of M-OH layers by hydrolysis. Owing to leaching of Mg and release of Fe, the octahedral M-OH formed by hydrolysis was gradually dominated by Al-OH. Reflectance spectroscopy is a powerful tool to identify protolith changes in weathering sequences and for studying clay mineralogical transitions and weathering intensity. This spectroscopic approach could have great value for understanding weathering related to paleoclimate on Earth or other planets using field spectroscopy and remote sensing. |
Persistent Identifier | http://hdl.handle.net/10722/306386 |
ISSN | 2023 Impact Factor: 5.3 2023 SCImago Journal Rankings: 0.998 |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Liu, J | - |
dc.contributor.author | He, H | - |
dc.contributor.author | Michalski, J | - |
dc.contributor.author | Cuadros, J | - |
dc.contributor.author | Yao, Y | - |
dc.contributor.author | Tan, W | - |
dc.contributor.author | Qin, X | - |
dc.contributor.author | Li, S | - |
dc.contributor.author | Wei, G | - |
dc.date.accessioned | 2021-10-20T10:22:51Z | - |
dc.date.available | 2021-10-20T10:22:51Z | - |
dc.date.issued | 2021 | - |
dc.identifier.citation | Applied Clay Science, 2021, v. 201, article no. 105923 | - |
dc.identifier.issn | 0169-1317 | - |
dc.identifier.uri | http://hdl.handle.net/10722/306386 | - |
dc.description.abstract | Visible/Near Infrared Reflectance spectroscopy (350–2500 nm) is an efficient and effective tool to identify and semi-quantify clay minerals, Fe3+ (oxyhydr)oxides, and their crystal-chemistry/structure. Even so, there have been few studies systematically describing how spectroscopy can be applied to mineralogical evolution during weathering. This study investigated reflectance spectra of a long core of a thick basaltic weathering sequence in Hainan Island and a series of transformation products from montmorillonite to kaolinite to present spectral features associated with weathering trends. In combination with X-ray diffraction and geochemical results, mineralogical transitions and weathering intensity of the core samples were described from a spectroscopic perspective. Several different protoliths were spectroscopically recognized in the Hainan weathering sequence, consistent with geological observation and geochemical analysis. Overprinted on these multiple protoliths was a discernable weathering sequence observable by infrared spectroscopic methods. Clay minerals changed upwards in section from TOT type (nontronite) to TO type (kaolinite), and finally to O type (gibbsite) hydroxide clay-size particles as the result of gradual hydrolysis of silicates and leaching of mobile elements with weathering. The relative abundance of hydroxyl to interlayer water, observable by the band depth ratio of spectral absorptions around 1400 nm and 1900 nm (BD1400/BD1900), increased progressively and correlated positively with the chemical index of alteration and Al2O3 concentration. The increasing BD1400/BD1900 index value with weathering was the result of gradual leaching of interlayer cations (e. g. Na+, K+), and their water complexes within interlayers, and gradual formation of M-OH layers by hydrolysis. Owing to leaching of Mg and release of Fe, the octahedral M-OH formed by hydrolysis was gradually dominated by Al-OH. Reflectance spectroscopy is a powerful tool to identify protolith changes in weathering sequences and for studying clay mineralogical transitions and weathering intensity. This spectroscopic approach could have great value for understanding weathering related to paleoclimate on Earth or other planets using field spectroscopy and remote sensing. | - |
dc.language | eng | - |
dc.publisher | Elsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/clay | - |
dc.relation.ispartof | Applied Clay Science | - |
dc.title | Reflectance spectroscopy applied to clay mineralogy and alteration intensity of a thick basaltic weathering sequence in Hainan Island, South China | - |
dc.type | Article | - |
dc.identifier.email | Michalski, J: jmichal@hku.hk | - |
dc.identifier.authority | Michalski, J=rp02225 | - |
dc.description.nature | link_to_subscribed_fulltext | - |
dc.identifier.doi | 10.1016/j.clay.2020.105923 | - |
dc.identifier.scopus | eid_2-s2.0-85096619539 | - |
dc.identifier.hkuros | 327250 | - |
dc.identifier.volume | 201 | - |
dc.identifier.spage | article no. 105923 | - |
dc.identifier.epage | article no. 105923 | - |
dc.identifier.isi | WOS:000609063400002 | - |
dc.publisher.place | Netherlands | - |