Application of Principal Component Analysis to ASTER Data for Hydrothermal Alteration Mapping in the Gümüşhane–Aktutan Region

Abstract

Hydrothermal alteration mapping plays a fundamental role in mineral exploration and geological interpretation, particularly in regions with complex tectonic and mineralization settings. This study applies Principal Component Analysis (PCA) to Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data for delineating hydrothermal alteration zones in the Gümüşhane–Aktutan area, Northeastern Turkey. The workflow included radiometric calibration, atmospheric correction using the IAR Reflectance Correction method, and band stacking of VNIR, SWIR, and TIR datasets. Alteration indices were generated through band ratio techniques, followed by PCA to enhance spectral signatures of key minerals such as quartz, sericite, kaolinite, and advanced argillic phases. Eigenvalue analysis guided the selection of optimal band combinations, which were visualized using RGB composites to characterize alteration patterns. The results highlight PCA’s effectiveness in differentiating overlapping spectral responses, enabling the identification of mixed alteration zones where multiple minerals coexist. This research demonstrates that PCA-based integration of multispectral ASTER data provides a reliable and cost-efficient approach for hydrothermal alteration mapping in geologically intricate terrains. The study offers an original case-specific implementation of selective PCA, presenting novel insights into the mineralogical framework of the Gümüşhane–Aktutan region. Beyond confirming the potential of ASTER data for hydrothermal system detection, the findings emphasize the value of multivariate statistical methods in refining alteration mapping. Future work will integrate hyperspectral datasets, field validation, and machine learning-based classification to further enhance mapping precision. The originality of this contribution lies in adapting PCA methodology to ASTER data in a mineral-rich yet underexplored area, offering significant implications for regional exploration strategies and remote sensing applications in geology..

Keywords

• ASTER
• Principal Component Analysis (PCA)
• Hydrothermal Alteration
• Remote Sensing
• Complex Tectonic Terrains

Gümüşhane-Aktutan Bölgesinde Hidrotermal Alterasyon Haritalaması için ASTER Verilerine Temel Bileşen Analizi Uygulaması

Abstract

Hidrotermal alterasyon haritalaması, özellikle karmaşık tektonik ve mineralizasyon ortamlarına sahip bölgelerde, mineral arama ve jeolojik yorumlamada temel bir rol oynamaktadır. Bu çalışma, Kuzeydoğu Türkiye'deki Gümüşhane-Aktutan bölgesinde hidrotermal alterasyon bölgelerini belirlemek için Gelişmiş Uzay Tabanlı Termal Emisyon ve Yansıma Radyometresi (ASTER) verilerine Temel Bileşen Analizi (PCA) uygulamaktadır. İş akışı, radyometrik kalibrasyon, IAR Yansıma Düzeltme yöntemi kullanılarak atmosferik düzeltme ve VNIR, SWIR ve TIR veri setlerinin bant istiflemesini içermektedir. Alterasyon indeksleri, bant oranı teknikleri kullanılarak oluşturulmuş, ardından kuvars, serisit, kaolinit ve gelişmiş arjilik fazlar gibi temel minerallerin spektral imzalarını geliştirmek için PCA uygulanmıştır. Özdeğer analizi, alterasyon desenlerini karakterize etmek için RGB kompozitleri kullanılarak görselleştirilen optimal bant kombinasyonlarının seçimine rehberlik etmiştir. Sonuçlar, PCA'nın örtüşen spektral yanıtları ayırt etmedeki etkinliğini vurgulayarak, birden fazla mineralin bir arada bulunduğu karışık alterasyon bölgelerinin tanımlanmasını sağlamaktadır. Bu araştırma, çok spektrumlu ASTER verilerinin PCA tabanlı entegrasyonunun, jeolojik olarak karmaşık arazilerde hidrotermal alterasyon haritalaması için güvenilir ve uygun maliyetli bir yaklaşım sağladığını göstermektedir. Çalışma, seçici PCA'nın özgün bir vakaya özgü uygulamasını sunarak, Gümüşhane-Aktutan bölgesinin mineralojik çerçevesine dair yeni bilgiler ortaya koymaktadır. Bulgular, ASTER verilerinin hidrotermal sistem tespiti potansiyelini doğrulamanın ötesinde, alterasyon haritalamasının iyileştirilmesinde çok değişkenli istatistiksel yöntemlerin değerini vurgulamaktadır. Gelecekteki çalışmalar, haritalama hassasiyetini daha da artırmak için hiperspektral veri kümelerini, saha doğrulamasını ve makine öğrenimi tabanlı sınıflandırmayı entegre edecektir. Bu katkının özgünlüğü, PCA metodolojisini mineral bakımından zengin ancak yeterince araştırılmamış bir alanda ASTER verilerine uyarlamakta ve bölgesel arama stratejileri ve jeolojide uzaktan algılama uygulamaları için önemli sonuçlar sunmaktadır.

Keywords

• ASTER
• Temel Bileşen Analizi
• Hidrotermal Alterasyon
• Uzaktan Algılama
• Kompleks Tektonik Araziler

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