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"Penelitian ini bertujuan untuk mengkaji hubungan antara kondisi geomorfologi, geokimia batuan, dan distribusi endapan nikel laterit di Daerah X, Kabupaten Halmahera Tengah, Provinsi Maluku Utara. Wilayah ini secara geologi berada dalam Mandala Halmahera Timur yang tersusun atas kompleks ofiolit dan batuan ultrabasa seperti harzburgit, lherzolit, dan dunite yang berperan sebagai batuan induk pembentuk laterit. Metode yang digunakan meliputi analisis geomorfologi berbasis data topografi dan klasifikasi bentuk lahan geomorphon, analisis geokimia batuan dasar menggunakan data X-Ray Fluorescence (XRF), serta pemetaan distribusi kadar dan ketebalan endapan laterit melalui interpolasi Inverse Distance Weighting (IDW). Hasil penelitian menunjukkan bahwa bentuk lahan seperti ridge, spur, dan shoulder pada kemiringan 2°–15° serta elevasi antara 700–900 meter cenderung memiliki ketebalan laterit yang lebih besar dan kadar nikel yang lebih tinggi, menjadikannya zona prospektif utama. Zona saprolit memiliki kadar Ni tertinggi, mencapai lebih dari 2,5%, dengan komposisi geokimia yang mengindikasikan tipe laterit Hydrous Magnesium Silicate (HMS). Hubungan negatif antara kemiringan lereng dan ketebalan limonit mengindikasikan peran penting topografi terhadap intensitas pelapukan dan pelindian unsur. Selain itu, analisis geokimia batuan menunjukkan bahwa harzburgit merupakan litologi dominan dengan sebaran kadar Ni yang luas, sedangkan kadar tertinggi tercatat pada litologi dunite dan lherzolit meskipun dengan jumlah data yang terbatas. Temuan ini memperkuat peran faktor geomorfologi dan komposisi kimia batuan dalam pengendalian pembentukan serta sebaran endapan nikel laterit, dan dapat dijadikan acuan dalam eksplorasi tahap awal di wilayah studi.

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This study aims to examine the relationship between geomorphological conditions, bedrock geochemistry, and the distribution of lateritic nickel deposits in Area X, Central Halmahera Regency, North Maluku Province. Geologically, the study area lies within the Eastern Halmahera Belt, characterized by ophiolitic complexes and ultramafic rocks such as harzburgite, lherzolite, and dunite, which serve as the primary protoliths for lateritization. The research methodology includes geomorphological analysis based on topographic data and geomorphon-based landform classification, geochemical analysis of bedrock using X-Ray Fluorescence (XRF), and spatial distribution modeling of nickel grade and laterite thickness using the Inverse Distance Weighting (IDW) interpolation method. The results indicate that landforms such as ridges, spurs, and shoulders with slope gradients between 2°–15° and elevations ranging from 700 to 900 meters above sea level tend to exhibit thicker lateritic profiles and higher nickel concentrations, marking them as highly prospective zones. The saprolite zone shows the highest nickel content, exceeding 2.5%, with geochemical characteristics indicative of the Hydrous Magnesium Silicate (HMS) laterite type. A negative correlation between slope angle and limonite thickness suggests that topography significantly influences leaching intensity and elemental accumulation. Furthermore, bedrock geochemical analysis reveals harzburgite as the dominant lithology with a wide range of Ni content, while the highest Ni grades are found in samples identified as dunite and lherzolite, although data for these rock types are limited. These findings highlight the crucial roles of geomorphology and geochemical composition in controlling the formation and spatial distribution of lateritic nickel deposits, offering valuable insights for early-stage mineral exploration in the study area."

"Pulau Sumatra berada di zona subduksi antara Lempeng Indo-Australia dan Lempeng Eurasia, menghasilkan tubuh-tubuh granit di sepanjang pesisir barat pulau. Kompleks Granit Sibolga diketahui mengandung UTJ, khususnya jenis LREE, yang penyebarannya dikontrol oleh tipe batuan, evolusi magma, hingga proses deformasi tektonik. Untuk memahami mekanisme deformasi yang bekerja pada daerah penelitian, dilakukan analisis data struktural di lapangan, mikrostruktur batuan melalui metode petrografi, serta analisis fabrik mineral magnetik menggunakan metode Anisotropy of Magnetic Susceptibility (AMS). Mikrostruktur mineral menyimpan rekaman deformasi yang terjadi sejak tahap magmatik hingga solid-state, sedangkan fabrik magnetik dari analisis AMS merepresentasikan orientasi strain yang bekerja. Penelitian ini bertujuan untuk mengungkap mekanisme deformasi yang berkembang pada Kompleks Granit Sibolga. Hasilnya ditemukan fabrik primer yang terekam pada lineasi magnetik, dan fabrik sekunder pada foliasi makroskopis dan foliasi magnetik. Deformasi pada KGS terjadi pada fase syn-emplacement dengan mekanisme piecemeal subsidence, menyebabkan intrusi terjadi secara bertahap. Sementara pada fase post-emplacement terjadi pada kondisi brittle pasca pengangkatan batuan, membentuk struktur berupa sesar, boudinage, kekar, microfracture, dan veinlet.

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The island of Sumatra lies within a subduction zone between the Indo-Australian Plate and the Eurasian Plate, resulting in the formation of granitic bodies along the island’s western margin. The Sibolga Granite Complex is known to contain REEs, particularly Light Rare Earth Elements (LREEs), whose distribution is controlled by rock type, magmatic evolution, and tectonic deformation processes. To understand the deformation mechanisms operating in the study area, this research employs structural data analysis in the field, petrographic analysis of rock microstructures, and magnetic mineral fabric analysis using the Anisotropy of Magnetic Susceptibility (AMS) method. Mineral microstructures preserve records of deformation spanning from the magmatic to the solid-state stages, while magnetic fabrics derived from AMS analysis represent the orientation of the strain experienced. This study aims to reveal the deformation mechanisms that developed within the Sibolga Granite Complex. The results indicate the presence of primary fabric recorded in magnetic lineation and secondary fabric observed in macroscopic and magnetic foliation. Deformation within the complex occurred during the syn-emplacement phase through a piecemeal subsidence mechanism, resulting in a gradual intrusion process. Meanwhile, the post-emplacement phase was characterized by brittle deformation following rock uplift, leading to the formation of structures such as faults, boudinage, joints, microfractures, and veinlets."