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This study investigated the multispectral remote sensing techniques including ASTER, Landsat 8 OLI, and Sentinel 2A data in order to distinguish different lithological units in the Alagbayan area of Dornogobi province, Mongolia. Therefore, Principal component analysis (PCA), Band ratio (BR), and Support Vector Machine (SVM), which are widely used image enhancement methods, have been applied to the satellite images for lithological mapping. The result of supervised classification shows that Landsat data gives a better classification with an overall accuracy of 93.43% and a kappa coefficient of 0.92 when the former geologic map and thin section analysis were chosen as a reference for training samples. Moreover, band ratios of ((band 7 + band 9)/band 8) obtained from ASTER corresponds well with carbonate rocks. According to PCs, PC4, PC3 and PC2 in the RGB of Landsat, PC3, PC2, PC6 for ASTER data are chosen as a good indicator for different lithological units where Silurian, Carboniferous, Jurassic, and Cretaceous formations are easily distinguished. In terms of Landsat images, the most efficient BR was a ratio where BRs of 5/4 for alluvium, 4/7 for schist and 7/6 to discriminate granite. In addition, as a result of BR as well as PCA, Precambrian Khutag-Uul metamorphic complex and Norovzeeg formation can be identified but granite-gneiss and schist have not given satisfactory results.

At present, geochemical data are widely used for reconstructing geodynamic settings, especially, volcanic rocks of mafic composition, i.e., basalts, because they are widespread in many orogenic belts and are indicative of different geodynamic environments. In general, we propose the reconstruction of the tectonic settings of basalts according to their relationships with associated ocean plate stratigraphy (OPS) sediments, their petrogenesis and their geochemical features.In this paper, we present new data on geochemistry of basalts from the Tsoroidog and Bumbattolgoi formations in the Tsetserleg accretionary wedge terrane in southwestern part of the Khangai-Khentey orogenic system [Tomurtogoo, 2012], which have been identified as the key region in the Central Asian Orogenic Belt (CAOB), the world largest accretionary orogeny. Detailed study of their geochemistry of volcanic rocks allowed us to recognize two types of chert-basalt association.Middle Silurian -Lower Devonian Tsoroidog formation is mainly composed of basaltic rocks with thin layers/lenses of thin-bedded, red-whitish color chertquartzite and slates. Basaltic rocks are characterized by medium TiO2 and high Zr/Nb ratio, Mg#=36-47, which is depleted in REE, Nb and Ti. Concentrations of TiO 2 , Fe 2 O 3 and P 2 O 5 decrease when MgO is increased in the binary diagram, whereas Al 2 O 3 is normal, furthermore, Nb, La and Sm decrease when MgO increases to compare with the rare elements. Nb is relatively less than La and Th. (Nb/La) PM value less than 1 is generally indicated in the MORB [Haase, 2002].Lower Devonian Bumbattolgoi formation mainly consists of basaltic rocks associated with shale, sandstone and red color cherts, which is represented by

The study area is located in the central part of Tsetserleg terrane in the southwestern margin of the Khangai-Khentey orogenic system. The paper presents new data on geochemistry and geochronology of sedimentary rocks The SiO 2 content of the Shar Khutul area sandstones ranges from 63.85 to 67.95 wt.% and the average content of TiO 2 is 0.72 wt.% and Al 2 O 3 content is 14.38 wt.%. The Chemical Index of Alteration (CIA) value ranges from 48.71 to 56.94 and the range of Index of compositional variations (ICV) is from 0.98 to 1.24. Moreover, the samples studied show that most of the sandstones are generally immature and were derived from weakly weathered source rocks. The ratios of Eu/Eu* (0.83), La/Sc (3.81), La/Co (5.30), and Cr/Th (13.81) indicate that the derivation of the Shar Khutul area sandstones from felsic rock sources and confirm the signatures of a felsic igneous provenance and suggest an active continental margin tectonic setting of the source area. The clastic zircons from the medium grained sandstone (Erdenetsogt formation) yield ages between 2.5 Ga and 236 Ma and the detrital zircons exhibit four peak ages at 1. .