Electronic Theses and Dissertation

Daerah beutong, kabupaten nagan raya, provinsi aceh merupakan salah satu wilayah yang memiliki potensi endapan emas sekunder (placer) yang ditunjukkan oleh aktivitas penambangan tradisional dan kondisi geologi yang kompleks. penelitian ini bertujuan untuk mengetahui kondisi geologi daerah penelitian, menganalisis karakteristik geokimia sedimen sungai berdasarkan analisis x-ray fluorescence (xrf), serta menganalisis asosiasi unsur geokimia sebagai indikasi potensi emas sekunder. hasil penelitian menunjukkan bahwa daerah penelitian tersusun atas tiga satuan geomorfologi, yaitu satuan geomorfologi bergelombang sedang hingga kuat (s2), satuan geomorfologi perbukitan hingga pegunungan (s4), dan satuan geomorfologi badan atau dasar sungai (f1), dengan pola aliran sungai sub-dendritik dan paralel. stratigrafi daerah penelitian terdiri atas delapan satuan batuan, yaitu serpentinit (muws), filit (muwf), metabatulanau (muwsl), andesit (muwa), serpentinite (tuses), konglomerat (qttc), batupasir (qtts), endapan aluvial (qpmsl). struktur geologi yang berkembang berupa kekar dengan orientasi dominan barat laut-tenggara yang dikontrol oleh sistem sesar sumatra. hasil analisis xrf menunjukkan bahwa unsur fe memiliki konsentrasi tertinggi, diikuti oleh cr, ni, cu, dan zn, sedangkan unsur au tidak terdeteksi pada seluruh sampel. pengayaan unsur ni dan cr mengindikasikan kontribusi batuan mafik ultramafik, khususnya serpentinit, sedangkan cu dan zn berasosiasi dengan mineral sulfida. analisis korelasi pearson menunjukkan hubungan positif sangat kuat antara ni dan cr, yang mengindikasikan kesamaan batuan sumber. meskipun unsur au tidak terdeteksi, keberadaan butiran emas placer yang ditemukan di lapangan serta asosiasi unsur fe, cu, cr, ni, dan zn mendukung interpretasi adanya potensi endapan emas sekunder di daerah penelitian. kata kunci: beutong, geokimia sedimen sungai, x-ray fluorescence (xrf), asosiasi unsur geokimia, emas sekunder.

The Beutong area in Nagan Raya Regency, Aceh Province, is a region with potential for secondary (placer) gold deposits, as evidenced by traditional mining activities and complex geological conditions. This study aims to determine the geological conditions of the research area, analyze the geochemical characteristics of river sediments using X-Ray Fluorescence (XRF) analysis, and examine geochemical element associations as indicators of secondary gold potential. The results indicate that the research area comprises three geomorphological units: Moderately to Strongly Undulating (S2), Hilly to Mountainous (S4), and Riverbed/Channel (F1), featuring sub-dendritic and parallel drainage patterns. The stratigraphy consists of eight rock units: serpentinite (Muws), phyllite (Muwf), metasiltstone (Muwsl), andesite (Muwa), serpentinite (Tuses), conglomerate (QTtc), sandstone (QTts), and alluvial deposits (Qpmsl). Geological structures present include joints with a dominant northwest-southeast orientation, controlled by the Sumatra Fault System. XRF analysis reveals that Fe has the highest concentration, followed by Cr, Ni, Cu, and Zn, while Au was not detected in any of the samples. Enrichment in Ni and Cr indicates a contribution from mafic-ultramafic rocks—specifically serpentinite—whereas Cu and Zn are associated with sulfide minerals. Pearson correlation analysis shows a very strong positive relationship between Ni and Cr, indicating a common source rock. Although the element Au was not detected, the presence of placer gold grains found in the field, along with the association of Fe, Cu, Cr, Ni, and Zn, supports the interpretation of potential secondary gold deposits in the study area. Keywords: Beutong, Stream Sediment Geochemistry, X-Ray Fluorescence (XRF), Geochemical Element Association, Secondary Gold.