Karakteristik Geologi Daerah Hulawa, Kecamatan Buntulia, Kabupaten Pohuwato, Provinsi Gorontalo

Yospin Saka (Program Studi Teknik Geologi, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Negeri Gorontalo)
Yayu Indriati Arifin (Program Studi Teknik Geologi, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Negeri Gorontalo)
Ninasafitri Ninasafitri (Program Studi Teknik Geologi, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Negeri Gorontalo)

Jurnal Riset dan Pengabdian Interdisipliner

Artisanal gold-mining activity in Hulawa Village, Buntulia District, Pohuwato Regency, has exposed a geological record worth further investigation. This study characterizes the local geology by integrating geomorphological, stratigraphic, petrographic, and structural analyses. Geomorphological mapping divides the area into Alluvial Plain and Volcanic Hills units. Stratigraphically, the area comprises three units ranging from Pliocene to Holocene: the Bumbulan Granodiorite, the Dacite of the Pani Volcanic Formation, and Alluvium. Petrographic analysis shows the Granodiorite has a holocrystalline-phaneritic texture with quartz, plagioclase, and chloritized biotite, while the Dacite exhibits a hypocrystalline-porphyritic texture with plagioclase phenocrysts in an aphanitic groundmass; both display propylitic alteration with disseminated opaque minerals. Analysis of 53 joint measurements identifies a tension-joint system trending dominantly NW–SE, with a main joint plane at N281°E/23°, consistent with the Granodiorite–Dacite contact orientation. This alignment indicates the area's structure and lithology were controlled by a single regional stress regime, and are associated with an ancient hydrothermal fluid-migration system once active in the region.