Chapter 3 Geologi Sumatra

Summary

This presentation delves into the geological characteristics of Sumatra, Indonesia, showcasing a detailed geological map of the region. The speaker discusses the complex stratigraphy, including volcanic deposits, sedimentary layers, and older intrusive rocks. Emphasis is placed on significant basins like Central Sumatra and South Sumatra, rich in hydrocarbons. Key geological features, such as faults, volcanic activity, and tectonic influences, are highlighted. The presentation also touches on the Sunda Shelf, its sedimentary processes, and the broader tectonic history, providing valuable insights into Sumatra's geological evolution and its resource potential.

Takeaways

• 😀 The geological map of Sumatera reveals diverse rock formations, ranging from Holocene sediments to older Triassic layers, as well as volcanic, intrusive, and metamorphic rocks.
• 😀 Sumatera’s geological structure is significantly influenced by tectonic activities, including rifting and subduction, which shape the region's fault systems and seismic events.
• 😀 The Sumatera Fault and Mentawai Fault play a major role in the region's seismic activity and have implications for volcanic and tectonic processes.
• 😀 Key hydrocarbon-rich areas in Sumatera include the Central and South Sumatra Basins, both of which are rich in sedimentary deposits and vital for oil and gas exploration.
• 😀 Fractured basement rocks, although unconventional, are becoming a focus of exploration due to their hydrocarbon accumulation potential.
• 😀 Sumatera’s stratigraphy demonstrates a transition from carbonate rocks to more volcanic and clastic deposits over time, spanning from Mesozoic to Cenozoic periods.
• 😀 Sedimentation in Sumatera is largely controlled by tectonic events and eustatic sea-level changes, which influence basin formation and sediment pathways.
• 😀 The region’s fault zones act as conduits for mineralization, potentially leading to valuable mineral deposits through hydrothermal fluid migration.
• 😀 The Sunda Shelf, which includes Sumatera, has a broad tectonic significance and plays a key role in the sedimentation processes and overall basin development.
• 😀 The tectonic history and sediment yields in Sumatera provide valuable insights into its geological evolution, including the dynamics of the Malay Basin and other extensional features.

Q & A

What is the main focus of the geological study of Sumatra in the transcript?

The main focus is on the geological formations, tectonic features, and the hydrocarbon potential of Sumatra. The study covers the various geological maps, stratigraphy, tectonic history, and resource exploration, especially in relation to oil and gas fields.

What are the primary geological formations in Sumatra?

The geological formations in Sumatra range from Holocene sedimentary rocks to older Triassic rocks. The region also includes volcanic deposits, intrusive igneous rocks (from Pliocene to Permian), and metamorphic rocks like phyllites and gneisses.

What is the significance of the Central Sumatra Basin?

The Central Sumatra Basin is significant because it is rich in sedimentary deposits, particularly in oil and gas fields. It is an area of considerable hydrocarbon accumulation, which has been developed extensively for resource extraction.

How do the tectonic features of Sumatra contribute to its geological history?

The tectonic features, such as the Sumatra fault system and the subduction zones, play a crucial role in shaping Sumatra's geological history. These structures are associated with seismic activity, volcanic formation, and the creation of mineral deposits, which also contribute to the region's resource potential.

What role do fractures in basement rocks play in Sumatra's exploration?

Fractured basement rocks are an area of growing interest in exploration because they have shown potential for hydrocarbon accumulation. Despite not being considered a conventional petroleum play, these rocks can store hydrocarbons, which makes them a target for further exploration in the region.

How does the Sumatra fault system impact the region?

The Sumatra fault system is a significant tectonic structure, as it represents the boundary between interacting tectonic plates (the Eurasian and Indo-Australian plates). This fault system causes frequent seismic events, volcanic activity, and contributes to the formation of mineral deposits, making it a key feature in Sumatra's geological framework.

What types of mineralization are associated with the Sumatra fault system?

The Sumatra fault system acts as a conduit for hydrothermal fluids, which can lead to mineralization in the surrounding rocks. This includes the formation of valuable mineral deposits, as the fault zones allow for the release of mineral-rich fluids, influencing the concentration of minerals in the area.

What is the significance of the Sunda Shelf in geological terms?

The Sunda Shelf, which includes Sumatra, is an important geological region characterized by continental margins, extensional basins, and rifting features. This shelf plays a key role in understanding sedimentation patterns, tectonic movements, and the formation of geological structures, making it crucial for exploration and study.

How do sea level changes affect sedimentation and exploration in Sumatra?

Sea level changes influence the accommodation space for sediments, affecting sedimentation patterns in the basins. These changes can control the deposition and preservation of sedimentary layers, which is vital for understanding hydrocarbon potential and resource exploration in the region.

What makes the Sunda Shelf and Sumatra's geological features unique?

The uniqueness of the Sunda Shelf and Sumatra lies in their complex tectonic history, which involves extensive rifting, faulting, and sedimentation. The region’s geological features, such as its rich sedimentary deposits, volcanic activity, and active fault systems, contribute to its significant potential for mineral resources and hydrocarbons.