TECTONOSTRATIGRAPHY AND PALEOGEOGRAPHY IN THE MAMBERAMO BASIN, PAPUA

• Main Author: Hidayat, Arif
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/55911
• Institution: Institut Teknologi Bandung

The Mamberamo Basin is one of the basins in eastern Indonesia. This basin is located between the Central Ranges Mountains with the New Guinea Trench which is included in the North Papua Basin. This basin is formed on the oceanic plate. The Mamberamo Basin was originally a forearc basin but since the collision in the Oligocene between the island arc and the Indo-Australian Plate, the tectonics and sedimentation in the area have changed into a successor basin. The results of previous drilling, in this basin there is a depositional environment in the deep to shallow marine environment, this difference is closely related to the development of the basin. The history of the development of the Mamberamo basin can be determined by tectonostratigraphy analysis and paleogeography analysis. This tectonostratigraphy and paleogeography analysis is based on six well data, thirtyfive 2D seismic line along + 1,017.96 km and drilling well reports. The results of data processing and interpretation produce time structure maps, depth structure maps, thickness maps (isopach). The resulting thickness map at each time interval represent the tectonic and sediment deposition patterns that occur at that interval. These data are used to analyze tectonostratigraphy and paleogeography with the addition of biostratigraphy data. The intervals analyzed were from Middle Miocene to Holocene The collision that occurred at the Oligocene age resulted in a sinistral strike slip fault in the Early Miocene. This strike slip fault produces a north-south trending transtensional tectonic. Active oblique subduction in the Middle Miocene produced the Maramuni Arc in the east of New Guinea Island and the sinistral strike slip fault continues in North Papua. In the Middle Miocene to Early Pliocene interval, transtensional tectonic trending north-south (N-S) developed which resulted in the development of normal faults with a west-east direction (W-E). Transtensional in the Middle Miocene to Late Miocene age is influenced by oblique subduction. In the Late Miocene, there was an unconformity due to changes in tectonic activity after the orogeny (collision) of the Central Ranges was completed. The transtensional from Late Miocene to Early Pliocene was caused by a change in the direction of relative motion of the Caroline Micro Plate (part of the Pacific Plate) to the Indo-Australian Plate from southwest (SW) to west (W). The transtensional of this range produced thicker sediment deposits than the previous range. The pattern of sediment deposition at this interval is controlled by normal faults. The transtensional ends at the Early Pliocene age, this is characterized by a pattern of sedimentary deposits that are not controlled by normal faults and tend to thicken gradually towards the south in the Early Pliocene to Late Pliocene. In the Early Pleistocene to Holocene time span, transpressional tectonics trending north-south developed due to changes in the direction of motion of the Caroline-Pacific Plate relative to the Indo-Australian Plate from west (W) to southwest (SW). This interval causes the formation of a positive flower structure and controls the thickness of the sediment. The direction of sedimentation in the Pre Middle Miocene age came from the north originating from the Niengo Basement. In the Middle Miocene to Early Pleistocene interval, the direction of sedimentation originates from the north and south. The Niengo High is the sediment supply in the north, while the sediment supply from the south comes from carbonate platforms in the Middle Miocene and orogeny of the Central Ranges starting from the Middle Miocene. Sedimentation from the north stopped after the Niengo Basement was covered by sedimentary deposits originating from the south in the Late Pleistocene Age. The direction of sedimentation from the south lasted from the Middle Miocene age. The direction of sedimentation from the south is indicated from sandstones containing quartz originating from the continent (Central Ranges). Paleogeography based on biostratigraphic data, isopach maps, and literature study. The Middle Miocene is a carbonate depositional environment consisting of the shelf, reef, basin floor and turbidite apron. In the Late Miocene to Late Pliocene time span, it consisted of a shelf, slope, basin floor and submarine fan. In the Early to Late Pleistocene intervals it is shelf, whereas in Holocene it consists of littoral and shelf.