## 1 Introduction  
Ophiolite hosts economic minerals such as chromium, which explains why chromite deposit exploration attempts for ore resources have resulted in much research interest by scientists and exploration geologists across the world. Ophiolitic ultramafic rocks are the hosts of podiform chromite deposits. Chromitite is closely associated with mantle peridotite in ophiolitic complexes [1]. Ophiolite zones in Tibet are widespread and are often found in different locations with varying geologic and tectonic settings. The Luobusa ophiolite is one of the most promising areas for prospecting chromite deposits because of the extensive outcrops of mantle peridotites [2]. Dozens of chromite deposits have been identified in mantle peridotite. These chromite occurrences have lenticular, tubular, and vein-like shapes, a few meters or tens of meters in length, which are hosted in peridotites. These bodies are individually small, but, where abundant, they form large-scale chromitite deposits [3]. Accordingly, the discrimination and mapping of mantle peridotites in ophiolitic complexes are quite interesting for chromite exploration plans. The Luobusa chromite deposit is a typical ophiolite-type or alpine-type chromite deposit, also known as a podiform chromite deposit due to its production characteristics. It is the largest and highest-quality chromite deposit in China [4,5]. Although its cumulative reserves of more than 500 \(\times\) 10\({}^{4}\) t still cannot compare with the known super-large chromite deposits in the world (100 Mt), such as Bushveld in South Africa and Kempirisai in the Southern Urals, its prospects should not be underestimated [2,6]. Moreover, the ore quality (grade) of the Luobusa chromite deposit is excellent, with the content of Cr\({}_{2}\)O\({}_{3}\) in the ore generally as high as 50%, and Cr\({}_{2}\)O\({}_{3}\)/FeO \(>\) 4 [7, 8, 9]. Therefore, due to the great extent of ultramafic rocks, which are the host of chromite deposits in the Luobusa ophiolite, the possibility of discovering new chromite deposits is high, and more exploration and investigation is needed. There is reason to believe that its reserves can be increased through continued exploration [2,9,10]. However, most Tibet ophiolitic zones are located in mountainous and inaccessible regions. Thus, given that the outcrop scale of ophiolite is often large, and traditional geological surveys are more expensive, time-consuming, and inefficient, especially for geological environments with high altitudes and harsh conditions that make it difficult to form a comprehensive understanding, new exploration methods such as the remote sensing method can be useful for this purpose [11, 12, 13]. Remotely sensed data have been extensively used for the delineation of lithological units and geological mapping. In contrast to conventional field surveying, remote sensing, with its macro, comprehensive, multi-scale, and multi-level characteristics, has become an effective tool for lithology mapping and has been widely used in geological work at different spatial scales [14, 15, 16, 17, 18, 19]. Each multispectral band records unique energy interactions with a surface, and geological features are enhanced spectrally (such as band ratio (BR), principal component analysis (PCA), independent component analysis (ICA), minimum noise fraction (MNF), and RGB color combinations) and spatially (such as image fusion and filtering), thereby improving their tones, hues, image texture, fracture patterns, lineaments, and trends to distinguish the different lithologic units. Image-enhancement methods produce new images with detailed information from the highly correlated bands. In different countries and regions, previous studies have performed a lot of work using remote-sensing technology for ophiolite delineation [15, 20, 21, 22, 23, 24, 25]. Currently, geological mapping techniques have combined with machine learning, such as a support vector machine (SVM).