TARAKAN BASIN - BORNEO

TARAKAN BASIN - BORNEO

Tarakan Basin, as the name implies, is around Tarakan Island. The island is geographically located in the Tarakan area, and its surrounding area, East Kalimantan Province, about 240 km north - northeast of Balikpapan. Geologically this island is located in the middle of the Tarakan Basin which is part of the NE Kalimantan Basin. Basically, the NE Kalimantan Basin is divided into 4 groups Sub basins: Tidung Sub Basin, Berau Sub Basin, Muara Sub-Basin, and Tarakan Sub-Basin.

Tarakan Basin is located in the northern part of Kalimantan Island. The area reaches 68,000 km2. In general, the northern part of this basin is limited by Mangkaliat exposure, in the East it is bordered by the Sulawesi Sea and in the West it is limited by the Central Range Complex.

 

Map of Location of the Tarakan Basin

Tarakan Basin can be divided into several sub-basins namely:

1. Tidung Sub-Basin

This sub-basin is located in the north and is on land extending to Sabah and developing during the Late Eocene to the Middle Miocene. Separated from the Berau Basin children to the south by the Latong Punggungan. Apart from Tarakan by the Sebuku Exposure, the anticline and fault rise northwestward along the coast and are bordered by a flat shear fault in northern Sempoa.

2. Tarakan Sub-Basin

This sub basin developed mainly in offshore areas filled with thick Plio-Pleistocene clastic deposits with deposition centers around Bunyu Island and Tarakan and have experienced pinchout and onlap to the west

and south.

3. Estuary Sub Basin

This sub basin is located off the coast of Tinggian Mangkalihat. It has the southernmost deposition center, developing off the coast. It is bounded by parallel parallel faults, the Mangkalihat and Maratua faults, cracked and passive margin sediments, and Oligocene carbonate structuring - Recent in the postrift section, which is the host rock at Eocene age.

4. Sub-Berau Basin

The Berau sub-basin is located in the southernmost part of the Tarakan Basin which developed from Eocene to Miocene and has a similar deposition history with the Tidung Sub-Basin. The dominant structure found on Tarakan Island is a normal fault trending Northwest to North with a fractured plane tilted to the East. Some of these faults are growth faults with roll over.

Tarakan Sub-Basin (Tossin and Kodir, 1996)

TEKTONIK

Tarakan Basin has a variety of faults, structural elements and trends. The tectonic history of the Tarakan basin begins with the extension phase from the Middle Eocene which forms a NW-SE direction wrench and influences the process of fracturing the Makassar strait which stops at the Early Miocene. This initial tectonic phase is the opening phase of the basin to the east which is indicated by the presence of enechelon block faulting which has a slope to the east.

From the Middle Miocene to the Pliocene is a more stable condition where sediment is deposited with a delta environment that spreads from several systems of distribution patterns from west to east. Examples of rivers that have a downstream in this area are the Proto-Kayan, Sesayap, Sembakung and several others. In this phase, the basin experiences subsidence due to the gravity of the load from the increasingly deltaic deposits, resulting in an electrical fault. The growth of the fault structure here indicates that the process of deployment of delta deposits to the west has taken place which has become less and begins to be deposited with carbonates. In the basin that leads to the east is composed of thick delta deposits, which are associated with normal syngenetic faults (normal faults that form together with precipitation).

The final tectonic phase in this basin is the compression process that occurs in Plio - Late Pleistocene due to the collision of the Philippine plate with the Borneo / East Kalimantan plate. This reactivates the existing structure and reverses the direction of some gravitational faults. However, a stronger force is in the northern part of the basin where the Miocene and Plosen deposits become folded and broken with NW - SE direction to WNE - ESE. In the eastern part of the basin, this compression phase forms a high structure because the sediment material is plastic so it forms the Bunyu and Tarakan anticlines.

From the tectonic phase it is believed that the deformation formed from the beginning of the tectonic process is the main controller of the formation of hydrocarbon deposits in the Tarakan basin.

Tectonic Order of the Tarakan Basin (Modified BEICIP, 1985)

REGIONAL GEOLOGY OF STRATIGRAPHY AND SEDIMENTATION

The Tarakan Basin is composed of Tertiary-aged rocks deposited on the Pre-Tierier bedrock. The dynamics of sedimentation in the Tarakan basin began at the Eocene age, initially the Tarakan Basin was a land area that deposited the Sembakung Formation - Green Formation. In the Oligocene a precipitation pattern of transgression is formed which is dominated by coarse clastic and carbonate rocks (Seilor Formation). The development of the transgression system continues until fine sediment is deposited (Nainputo Formation) and in some places reef limestone (Tabular Formation) is deposited. Then a regression occurs until the basin is lifted, and then coarse clastic sediments are deposited which the source is referred to as the Central Range Complex (LEMIGAS, 2006).

The depositional environment is a complex delta and stretches from West to East (Trained / Stretch Formation). The Tabul Formation is in the east which is a part of the Production Department which is composed of claystone facies. In the late Miocene, the elevation of Kuching took place, thus lifting the northern part of the Tarakan Basin. And in the Pliocene a delta environment was formed and deposited the Tarakan Formation.

The stratigraphy of the tarakan basin, from old to young is as follows:

Stratigraphy of the tarakan basin

Sembakung Formation

Early Tertiary rocks consist of the Sembakung Formation, which overlaps unaligned Late Cretaceous rocks, consisting of carbonic siliciclastic rocks from the litoral marine environment to the shallow sea at the time of the Eocene.

Green Formation

The Sujau Formation consists of clastic (conglomerates and sandstones), shale, and volcanic sediments. The clusters of the Sujau Formation represent the first stage of filling a "graben like" basin which may have been formed as a result of the burning of Makassar in the Early Eocene. The lithology of the composition of 1000 meters of volcanic acid, sandstone, volcaniclastic. The geological structure that develops is very complex and results in this area being strongly folded.

Seilor Formation

Micritic limestones from the Seilor Formation are deposited in harmony above the Sujau Formation and the Mangkabua Formation which consists of sea and marrow shales which are Oligocene to be a sign of succession change to basin.

Mangkabua Formation

In this formation there was a progradational change from the Seilor (micrite limestone) formation to a thick and massive batunapal. There are Nummulites fichteli (Marks, 1957) which are Oligocene. This formation eroded intensively at the end of the Oligocene because of the tectonic process in the form of lifting caused by volcanic activity.

Reference:

• Google.com
• Yahoo.com
• Wikipedia.com
• GDA Consultant, 2006, PRELIMINARY STUDY OF POTENTIAL HYDROCARBON IN Sangatta Block, Onshore, East Kalimantan, Pertamina UEP IV (Unpublished)
• http://nicoandreasnainggolan.blogspot.com/2014/04/tarakan-basin.html

KUTAI BASIN, BORNEO

KUTAI BASIN, BORNEO

REGIONAL GEOLOGY

The Kutai Basin is limited by the Paternoster platform, Barito Basin, and the Meratus Mountains to the south, with the Schwaner Block to the southwest, then Mangkalihat Tinggian to the north - northeast, and the Central Kalimantan Mountains (Moss and Chambers, 1999) to the west and north

  

Regional Kutai Basin

The Kutai Basin has a complex history (Moss et al., 1997), and is the only Indonesian basin that has evolved from the internal rifting fracture / foreland basin to marginal-sag. Most of the initial products fill the Kutai Basin have been reversed and exposed ( Satyana et al., 1999), in the Middle Miocene to the Late Miocene as a result of Micro Continent collision / block collisions.

From this event it caused the removal of basins, changes in the anticline axis and surface erosion that controls sedimentation in the Mahakam Delta. The Mahakam Delta is formed at the mouth of the Mahakam river on the east coast of the island of Borneo. With its coastline oriented towards NE-SW and limited by the Makassar Strait, the strait separates the islands of Borneo and Sulawesi.

REGIONAL STRATIGRAPHY

Stratigraphy Kutai Basin

 

Satyana et all, 1999 in the 2001 Outline of the Geology of Indonesia conducted a study and compiled the stratigraphy of the Kutai Basin from old to young as follows:

1) Beriun Formation

The Beriun Formation consists of claystone, alternating sandstones and limestones. Beriun Formation Middle Eocene - Late Eocene and deposited in fluviatyl to litoral environments.

2) Atan Formation

Above the Formation Beriun is deposited at the Atan Formation which is the result of settling after a decrease in basins and precipitation in the Beriun Formation. The Atan Formation consists of quartz limestones and sandstones. Atan Formation is in the Early Oligocene.

3) Angry Formation

The Angry Formation was arranged in harmony above the Atan Formation. The Marah Formation consists of claystone, quartz sandstone and limestone in the late Oligocene.

4) Pamaluan Formation

Precipitated during Early Miocene to Late Miocene in neritic environments, with characteristics of claystone lithology, shale, limestone, siltstone and quartz sandstone inserts. This formation is deposited in the delta to litoral environment.

5) Bebulu Formation

Precipitated during Early Miocene to Middle Miocene in neritic environments. The lithology characteristic of the Bebulu Formation is limestone.

6) Pulubalang Formation

The Pulubalang Formation is deposited in harmony above the Pamaluan Formation, consisting of alternating silt sand with a thin slate of sandstone and claystone. The age of this formation is Middle Miocene and deposited in the sub-litoral environment, sometimes influenced by marine influx. This formation has a relationship with the Bebulu Formation which is composed of sandstone limestones with shale

7) Balikpapan Formation

The Balikpapan Formation is deposited in harmony above the Pulubalang Formation. This formation consists of alternating between claystone and sandstone with coal inserts and limestones at the bottom. Drilling data that has been carried out in the Kutai Basin proves that the Balikpapan Formation was deposited with a delta system, in plain delta to delta front. The age of this formation is Middle Miocene - Late Miocene.

8) Kampungbaru Formation

The Kampung Baru Formation is Mio-Pliosen, located above the Balikpapan Formation, consisting of alternating sandstones, claystone and coal with thin limestone slabs as marine influx. This formation depositional environment is delta.

9) Mahakam Formation

The Mahakam Formation was formed during the Pleistocene - now. The deposition process is still going on until now, with lithological characteristics of loose material from clay to fine sand.

REGIONAL GEOLOGICAL STRUCTURE

Like some basins in other Southeast Asia, half grabens were formed during the Eocene as a result of extensional or regional expansion phases (Allen and Chambers, 1998). This expansion is a manifestation of the Indian Continent sub plate collision with the Asian Continent plate which spurred expansion along the strike-slip fault series with the northwest-southeast direction (NW-SE) which was the reactivation of the previous structure, the Adang-Lupar fault and the Mangka fault.

This basin begins to fill transgressive sediment deposits during the Late Eocene to the Oligocene. Then it was followed by a regressive sequence at the time of the Early Miocene which was the initiation of the current Mahakam Delta complex. The Mahakam Delta propagation process increased very significantly in the Middle Miocene, when the elevation of Kuching in the West was raised and the first inversion occurred. The progress is still ongoing today. The second invasion occurred during the Mio-Pliocene period, when the Sula-Banggai plate crashed into Sulawesi and produced a mega shear Palu-Koro.

The formation and development of the main structures that control the sub-Lower Kutai Basin are closely related to the Second Inversion tectonic process, namely geological structures with a northeast-southwest (NNE-SSW) direction pattern. According to Allen and Chambers, (1998) this pattern can be seen in the general structure revealed in the current Kutai Basin, namely in the form of recommended fault lines and anticline / anticlinorium complexes.

Another structural development is the northwest-lateral alignment pattern (NW-SE), in the form of normal faults which are manifestations of the pre-formed main force release. These faults are mainly in the northern part of the basin, cutting sediments of Middle Miocene and other older parts.

 Surface Geology Map of Kutai Area

Tectonic Setting Kutai Basin

The tectonic order of the Kutai basin can be summarized as follows:

• Early Synrift (Paleocene to Early Eocene): This stage of sediment consists of alluvial sediments filling the NE-SW and NNE-SSW topography resulting from rifting trends in the overland Kutai Basin. They overwrite in the late Cretaceous compression basement to the beginning of the Tertiary in the sea in the sequence.
• End of Synrift (Middle to Late Eocene): During this period, a large transgression occurred in the Kutai Basin, partly related to rifting in the Makassar Strait, and accumulated shale bathial sand inserts.
• Early Postrift (Oligocene to Early Miocene): During this period, bathial conditions continued to dominate and several thousand meters were dominated by accumulated shale. In the shallow structural area the carbonate platform develops
• End of Postrift (Middle Miocene to Quaternary): From the Middle Miocene and so on the sequences of progressaded deltas have grown steadily into the sea in the Makassar Strait, forming a sequence of Mahakam Delta, which is the main part of the hydrocarbon carrier in the basin. Various types of delta deposits on - and offshore develop in the formations of Balikpapan and Kampungbaru, including also deep sea slope facies and basin facies. And there are also excellent host rocks and reservoirs with interbedded sealing shale. After this period, a large erosion process occurred in the Kutai synrift sequence.

Reference:

• Yahoo.com
• Google.com
• Wikipedia.com
• http://www.academia.edu/7302602/Laporan_Proposal_Eksplorasi_Batubara_di_Cekungan_Kutai_Balikpapan_Kalimantan_Timur_-_Johan_Edwart