Remote Sensing Study of Sittampundi Anorthosite Complex, India

Abstract

In the present study, The Landsat 7 ETM satellite data was collected for the Sittampundi anorthosites complex and digital image analysis was carried out. The anorthositic rocks available at Sittampundi complex is considered as an equivalent of lunar highland rocks. Hence, a remote sensing study comprises of image analysis and spectral profile analysis was carried out. The satellite data was digitally processed and generated various outputs like band combinations, color composites, stretched outputs, and PCA. The suitable processed outputs were identified for delineating the anorthosite complex. The diagnostic absorption features of reflectance spectra are the sensitive indicators of mineralogy and chemical composition of rocks, which are interest to the planetary scientists. The spectral profile of Landsat ETM plotted for pure and mixed anorthosite pixels and compared with the field and lab reflectance spectra. The percentages of image spectra vary from 30% to 60% for Sittampundi anorthosite. The spectral bands 2, 4 and 6 have low reflectance and bands 3 and 5 have high reflectance. The spectral range of bands 2,3,4,5 and 6 are 525 nm-605 nm, 630 nm-690 nm, 750 nm-900 nm, 1550 nm-1750 nm and 10400 nm-12500 nm respectively. The field spectral curve has weak absorptions at 650 nm and 1000 nm due to the iron transition absorption and low ca-pyroxene respectively available in the anorthosite, matching with the image spectra. However, hyperspectal image with narrow bandwidth could be more useful in selecting the suitable spectrum for remotely mapping the anorthosite region, as equivalent test site for lunar highland region.

Experimental validation of XRF inversion code for Chandrayaan-1

“…• Sittampundi rock : This sample is taken from the anorthositic rocks available at Sittampundi (near Salem, Tamil Nadu), India, which are considered close to lunar highland rocks in composition. The plagioclase in these rock samples exhibit an anorthite content in the range An 80−100 (Anbazhagan et al, 2012) in comparison to that in Apollo returned samples which has an anorthite content of ≈ An 95 on average. Pure calcic-anorthite and labradorite are the dominant minerals in this sample.…”

“…They are pulverized to a grain size of about 100 µm or smaller. Detailed studies on the rocks of this site are reported by (Anbazhagan et al, 2012;Aarthy et al, 2009).…”

“…• Sittampundi rock : This sample is taken from the anorthositic rocks available at Sittampundi (near Salem, Tamil Nadu), India, which are considered close to lunar highland rocks in composition. The plagioclase in these rock samples exhibit an anorthite content in the range An 80−100 (Anbazhagan et al, 2012) Pellets of these samples were made after crushing them manually and compressing it with a pelletizer. We assume that the pellets are a close representation of flat and homogeneous sample.…”

Satellite data based abundance mapping of mafic and ultramafic rocks in Mettupalayam, Tamil Nadu, India

“…Principal Component Analysis (PCA) is an image enhancement technique used to utilize the maximum spectral contrast of all bands of multispectral data, and it is more reliable than the original image (Anbazhagan et al 2012, Arivazhagan & Anbazhagan 2017. In another sense, PCA is a statistical analysis approach used to reduce irradiance in the bands, so each band can represent particular features, and a combination of this can be interpreted as more valuable information (Ge et al 2018).…”

ASTER Data Analyses for Lithological Discrimination of Sittampundi Anorthositic Complex, Southern India

“…The Sittampundi Anorthositic Complex is one of the geological interested provinces, since it is bearing chromite (Ghosh and Konar, 2011) and also considered as occurrence of Platinum Group Elements (PGE) (Balaram, 2006). Beyond this, the mineralogy and the relative percentage of major oxides of Sittampundi anorthsoite is considered as an equivalent of lunar highland anorthositic rock (Anbazhagan and Arivazhagan 2010; Anbazhagan et al, 2012). Hence, the development of a suitable methodology to map and discriminate the different lithology in the anorthosite region, could be applicable to the remote sensing study of lunar surface.…”