Electronic Theses and Dissertation

Formasi Tangla merupakan salah satu satuan batuan utama yang tersingkap di Kecamatan Darul Hikmah, Kabupaten Aceh Jaya, Provinsi Aceh, berumur Oligosen Akhir hingga Miosen Awal (Tersier) dan tersusun oleh batuan asal gunungapi, batupasir mikaan atau gampingan, batupasir konglomeratan, batulanau serta batulumpur. Sebagai bagian dari Cekungan Sibolga yang memiliki prospek hidrokarbon, batupasir Formasi Tangla berpotensi dimanfaatkan sebagai bahan baku industri, bahan konstruksi maupun reservoir. Penelitian ini bertujuan mengetahui kondisi geologi serta karakteristik batupasir Formasi Tangla melalui metode pemetaan geologi permukaan skala 1:25.000 dan analisis petrografi pada sayatan tipis batuan. Hasil pemetaan pada blok penelitian seluan 25 km2 mengidentifikasi 46 titik singkapan yang terbagi ke dalam empat satuan batuan, yaitu satuan batupasir, batulanau, batulempung dan endapan aluvium, dengan enam unit bentuklahan meliputi Perbukitan Cuestas (S6), Tebing dan Zona Kedudukan Laut (M2), Beaches (M3), Vegetated Tidal Flats (M9), Dasar sungai (F1) serta Dataran Aluvial (F12) dan pola aliran dominan berupa dendritik. Analisis petrografi terhadap tiga sampel batupasir dan satu sampel batulempung menghasilkan klasifikasi Quartz Arenite (sampel OT 12 dan OT 16), Quartz Wacke (OT 18) dan Mudrock (OT 15) berdasarkan klasifikasi Pettijohn (1975). Analisis tingkat kematangan tekstur menurut Nichols (2009) menunjukkan OT 12 tergolong submature, OT 16 tergolong mature dan OT 18 tergolong immature, mencerminkan variasi energi dan jarak transportasi sedimen pada saat pengendapan. Struktur geologi berupa kekar teridentifikasi dengan arah tegasan Barat Laut – Tenggara (NW-SE). Hasil penelitian ini menjadi data awal untuk evaluasi potensi batupasir Formasi Tangla sebagai reservoir maupun material konstruksi dan pemetaan geologi di wilayah Kecamatan Darul Hikmah, Kabupaten Aceh Jaya yang lebih detail.

The Tangla Formation is one of the major rock units exposed in Darul Hikmah District, Aceh Jaya Regency, Aceh Province. It is of Late Oligocene to Early Miocene (Tertiary) age and consists of volcanic-derived rocks, micaceous to calcareous sandstone, conglomeratic sandstone, siltstone, and mudstone. As part of the Sibolga Basin, which has hydrocarbon potential, the sandstones of the Tangla Formation are considered prospective as reservoir rocks as well as for industrial raw materials and construction materials. This study aims to determine the geological conditions and characterize the sandstone of the Tangla Formation through 1:25,000-scale geological mapping and petrographic analysis of rock thin sections. Geological mapping of the 25 km² study area identified 46 outcrops, which were classified into four lithological units: sandstone, siltstone, claystone, and alluvial deposits. Six geomorphological units were recognized, namely Cuesta Hills (S6), Sea Cliff and Shoreline Zone (M2), Beaches (M3), Vegetated Tidal Flats (M9), River Channel (F1), and Alluvial Plain (F12), with a predominantly dendritic drainage pattern. Petrographic analysis of three sandstone samples and one claystone sample classified the rocks as Quartz Arenite (samples OT12 and OT16), Quartz Wacke (OT18), and Mudrock (OT15) according to Pettijohn (1975). Textural maturity analysis based on Nichols (2009) indicates that sample OT12 is submature, OT16 is mature, and OT18 is immature, reflecting variations in depositional energy and sediment transport distance during sedimentation. Joint structures were identified with a northwest–southeast (NW–SE) principal stress orientation. The results of this study provide baseline data for evaluating the potential of the Tangla Formation sandstone as reservoir rocks and construction materials, while also supporting more detailed geological mapping in Darul Hikmah District, Aceh Jaya Regency.