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4. Other Mud volcanoes in East Java

4. Other Mud volcanoes in East Java

Mud volcanoes are common in the northern part of Java and Madura Island (Satyana, 2008).

Like elsewhere in the world, mud volcanoes in Java and Madura typically are located at the top of anticlines or along faults in the area.

This phenomenon is demonstrated by the Sangiran mud volcano which is located at the top of the truncated dome on an up-thrown fault block, while the Bleduk Kuwu mud volcano is located on the top of the Purwodadi anticline, The Api Kayangan (means Fire of Heaven, or Eternal Fire) mud volcano is at the top of the Bojonegoro anticline.

The Pengangson mud volcano located at the top of the Kedungwaru anticline, while the Pulungan and Kalang Anyar mud volcanoes are on the top of the Pulungan anticline. The Gunung Anyar (means New mountain) mud volcano is at the top of the Guyangan anticline, Bujel Tasek (Madura) and finally LUSI erupted on the extension of the Sekarputih anticlinal structure.

Most of the mud volcanoes in East Java, with the exception of LUSI, are in the relative quiescence period and some can be considered in the dormant period with minimal activity.

The existence of these mud volcanoes are described in the latter part of the paper


Fig. 31. Gravity map of East Java showing East Java Basin’s depositional centers (blue) in the Kendeng depression zone. Red dots are the identified mud volcanoes, while the triangles are magmatic volcano locations.



The presence of mud volcanoes in the northern East Java Basin, especially along the Kendeng depression zone, is a common phenomenon.

Their presence reflect the overpressure condition due to the very rapid deposition of the bluish-green mudstone and marlstone of the Sonde Formation during the Pliocene in a back arc basin setting that is folded and faulted (Dickinson, 1974).

In Central and East Java mud volcanoes are found within the Kendeng depression zone, except Bujel Tasek which appears in Rembang zone.

The Kalang Anyar, Gunung Anyar, Pulungan, Bujel Tasek (Madura) and LUSI are in a straight line trending NE-SW contiguous with the regional fault trend, originating from the crater of Mt Penanggungan of the Arjuno–Welirang volcanic complex, following the Watukosek fault escarpment in the southern mountain ranges northward to Bujel Tasek in Madura island (see figure 32).

4.1 Kalanganyar

Kalanganyar mud volcano is located approximately 3 km south of Juanda Airport and approximately 15 km North-East of LUSI. The phenomenon of mud volcanoes in this area has been identified and mapped on the 1936 geological map of the Dutch era, suggesting it

was formed long before the 1936 Duyfjes map. A temple known as Candi Tawangalun Majapahit (approximately 500 years ago) situated on the northern edge of the mud volcano suggest the significance of the mud volcano in the Majapahit era (see figure 33).

Interestingly, some parts of the temple’s material were made from material products of the Kalanganyar mud volcano.

The morphology of the Kalanganyar mud volcano forms a low relief hill overlying the alluvial plain deposit. The dimension of the main eruption cone is around 12x18 m.

Some activities are still evident such as gas bubbles and some fresh mud around the main eruption vent (see figure 34) with a temperature of ± 38 °C. The unit is composed of silt-sized material and grains of fine sand and clay and saltwater that forms salt deposits.

The low relief of the mud volcano suggests that the mud has very low viscosity. The mud shrinks during dry season to form dessicated mud crack structures that are commonly found in the area.

The mud material is derived from older rocks than the surrounding alluvial plains, correlatable with the mud at LUSI, the Upper Kalibeng Formation of Plio-Pleistocene age.

In the area around the active gas bubbles, rock fragments, such as siderite and salt deposits, are always found. The gas bursts are typically mild consisting of mixed gas, and formation fluids mainly connate water. Microbial activites are also found near the gas bubbles.

Mud breccias that are ejected from the Kalanganyar mud volcano are in the form of mud supported mudstone fragments which are light brown in color, composed of abundant carbonate mud, and quartz with opaque minerals in small quantities.

Rudstone (Embry and Klovan, 1971) which is gray - brownish gray, grain supported, with fragment components consisting of shells of molluscs (Gastropoda and Pelecypoda, with a dominance of Ostrea shells) measuring 10-20 cm are abundant (> 10%) and bound by the matrix and carbonate cement (Figure 35 A&B). Balanus fossils were largely found freed from the carbonate (Figure 35 C) although some were still found to be bound by carbonate cement.

The mud eruption carried younger sediments and boulders which contain mud breccias and limestones. The stratigraphic position of the mud breccia based on Balanus fossil found on limestone within the mud breccia, indicate that this was sourced from the Sonde Formation of Pliocene age.

The existence of mollusc and balanus contained in rudstone limestones suggest deposition in a shallow marine environment to the coastal littoral zone with strong

Fig. 32. Geological map overlaid with Google earth. Red stars are the identified mud volcano locations. The mud volcanoes are located across the top of anticlines and form a lineament.

Fig. 33. Tawangalun temple was built during the Hindu kingdom (500 years ago) situated in the Northern edge of Kalanganyar mud volcano. Some materials of the temple were made from fragments from the Kalanganyar mud volcano.

Fig. 34. Kalang Anyar mud volcano in Kalanganyar village, Sidoarjo, East Java energy currents.

The dominant grain supported matrix of rudstone further suggests a high energy depositional environment. A shallow marine environment is located on the continental shelf with the fore reef sea conditions that are less affected by the supply of silisiclastics.

The existence of mudstone with mud supported textures indicate deposition below wave base conditions on the back reef, rocks consequently do not experience the washing process (winnowing) by wave activity.

The older mud volcano material is thought to have been sourced from the deeper Upper Miocene Kalibeng Formation, suggesting a regressive sequence in this part of the Kendeng zone of the East Java Basin.


Fig. 35. (A)&(B) Sandstone with mollusc shells dominated by Ostrea , (C). Balanus fossils among carbonates and siderite.

4.2 Gunung Anyar

The Gunung Anyar mud volcano (means ”new mountain”) is located 8 km to the west-northwest of Kalang Anyar mud volcano and is surrounded by densely populated residential area in the Gununganyar village, Surabaya.

The morphology of the Gunung Anyar mud volcano is a northeast orientation and elongated hill-shaped geometry on the surrounding flat alluvial plains.

The dimension of the still active main eruption vent is approximately 8x9m. The ejected material is composed of silt-sized grains of predominantly fine sand and saltwater.

The temperature of the vent is ± 37.2 °C. More solid content than fluid has erupted from this mud volcano.

The lithology is similar to Kalang Anyar mud volcano where the composition is predominantly silt with the physical characteristics of brownish-grey, fine sand-sized to clay. In dry conditions, the structure shrinks, typically forming desiccated mud cracks.

Seepage of crude oil of black color is also visible among the small bubbles that are still active.



Fig. 36. Gunung Anyar Mud Volcano morphology at Gunung Anyar Village in the Southern part of Surabaya, East Java.

Based on rocks and fragments carried by the mud eruption, the erupted materials were sourced from the following stratigraphic layers:

a. Marl

Brown marl with some weathered surfaces, white in color, with clay-sized fossil planktonic foraminifera and sand-sized bentonic fragments. Fresh outcrops of limestone fragments that appear to be newly ejected by the mud volcano.

Stratigraphic position of the marl based on the physical properties and fossil content, indicate that this was derived from the Kalibeng and Sonde Formations.

b. Limestone

The limestone contains balanus fossils bounded by carbonate cement. The limestone based on fossil is thought to have been sourced from the Sonde Formation. The presence of balanus fossils typically suggest the coastal litoral zone depositional environment with the strong currents, while the texture of the limestone, suggest the low - moderate flow of energy environment with warm, calm and shallow waters possibly positioned on the back


c. Calcareous sandstone

Weathered brown sandstone, poorly sorted, sub-rounded, fine sand-sized, composed of quartz, feldspar, biotite, and calcite. Black mudstone associated with these calcareous sandstones is also found in small quantities. The sandstone may have been sourced from the Pucangan Formation, Pleistocene in age.

d. Molluscs sandstone (grenzbank)

Sandstone containing molluscs of freshwater and seawater were found in this location. The freshwater molluscs which are characterized by the thin shell bi-valves are more dominant than the seawater molluscs. The presence of mixed seawater and freshwater molluscs suggest shallow to transitional marine deposition environment.

Fig. 37. Crude oil seepage coming out with salty connate water along with bubbles in Gunung Anyar Village.

e. Silt

Silt makes up most of the mud volcanic area. It is composed of silt-sized grains of predominantly silisiclastic brownish-grey colored clay materials and the salt water. The temperature is around 37 °C at the mud conduit. The mud contains more solid silt and clay materials than fluid. Silts were derived from underlying older rocks of possibly Upper Kalibeng Formation of late Miocene. The presence of rock fragments, siderite, and seepage of black crude oil are almost always found within the vicinity of active bubbles.

4.3 Pengangson

The location of Pengangson mud volcano is in the village of Kepuhklagen, Wringinanom, Gresik Regency. Compared to other mud volcanoes in East Java, the Pengangson mud volcano is the most ideal example of a mud volcano.

The younger sediments outcropped and exposed at nearby excavated cliffs to the west of the mud volcano, and older rocks are found as fragments or clast carried by the mud volcano eruption.

The geological structural components at this site are also clearly visible, such as folds, fractures, fault lines and sedimentary structures.

The morphology is formed of low hills between the alluvial plain surrounding. The unit is composed of silt sediment material with dominant clay-sized grains.

The low temperature mud of ± 39.5 °C is typical of other mud volcanoes in other parts of East Java. The mud is thick and the liquid consists of a mix of formation fluid, crude oil seeps, salt deposits and gas bubbles.

Fig. 38. Pengangson Mud Volcano in Kepuhklagen village, Gresik, East Java.

The materials ejected by the mud volcano are the following:

a. Sandy Mudstone - Sandy Siltstone

Rock outcrops are generally brownish-grey in fresh and partially weathered condition.

Physical characteristics of the rock suggest that it is from the Sonde Formation. Based on the deposition enviroment, lithology, sedimentary structure, texture, mineralogical composition, and fossils suggest that this unit was deposited in a middle shelf environment - lower delta plain.

b. Tuffaceous Sandstone unit, Sonde Formation

The naming of the sandstone unit is based on the condition of the rock outcrop on the cliffs with tuffaceous sandstone lithology that shows the layered structure and planar crossbed.

Rock samples in this unit do not contain foraminifera because of the dominance of volcanic material in the rocks.

The composition of the constituent material of plagioclase and the presence of volcanic glass which tends to be wacke, suggests that the source is not far from the sedimentation basin.

The similarity of physical properties, and texture of rocks suggest this unit is part of the Sonde Formation.

c. Sandstone unit, Pucangan Formation

This unit is characterized by the presence of sedimentary structures such as grading, parallel lamination and slump structures. Outcrops of fresh rocks generally show somewhat weathered condition. The bottom of the unit is dominated by volcanic sandstone that contains calcareous mudstone layers. This unit is part of an eroded top of anticline. Interpretation of the environment based on the lithology data, sedimentary structure, texture, mineralogical composition, and fossils indicates that this unit was deposited on the inner shelf

environment -lower delta plain with traction and suspension flow mechanism. The sequence of lithologies indicates deposition in increasingly shallow conditions with the initial deposition on the inner shelf.

The similarity of physical properties, texture, structure, age and environment of deposition of rocks suggests that this unit is part of the Pucangan Formation.

d. Tuffaceous Mudstone

The outcrop of rocks is generally fresh or slightly weathered. Overall this unit is dominated by massive mudstone and tuff. The bedding trends west - east and slopes to the north and south.

Interpretation of the environment of deposition based on the lithology, texture, and  mineralogical composition is that this unit was deposited in a braided stream environment or sub flood plain and stream sediment was transported through the mechanism of


The similarity of physical properties and the texture of rocks suggests that this unit is part of the Kabuh Formation.

e. Volcanic sandstone

This unit is characterized by the presence of sedimentary structures such as grading, cross-lamination and parallel lamination. The outcrop of rocks generally show a somewhat weathered condition but rock structure is still visible. Interpretation of the environment of deposition based on the lithology, sedimentary structure, texture, and mineralogical composition suggests that this unit was deposited in a braided stream environment (minor channel) with traction flow mechanism. The similarity of physical properties, texture and structure of rocks suggests that this unit is part of the Kabuh Formation.

f. Silt unit

The naming of this rock unit is based upon the existence of a silt dominated mud volcano.

The morphology of mud volcanoes forms a low hill between the alluvial plains. The unit is composed of silt sediment material dominant by clay-sized grains with a temperature 39.5 °

C. From the main vent fluid, gas bubbles and salty water are released.

Fig. 39. Crude oil seepage, brownish-black in color together with mud and gas that comes out of a gryphon.

In the vicinity, bubble-shaped Gryphons, siderite, and salt deposits are commonly found (see figure 39). Rock fragments are found in a limited number that consist of calcarenite (Sandy micrite), calcareous sandstone, calcareous mudstone (Micritic mudrock in the Mount, 1985) and sandstones with molluscs.

This mud deposit in Wringinanom contains foraminifera planktonic fossils suggesting a middle Pliocene age to late Pliocene (N20-N21) mud source, while the content of bentonic neritic foraminifera suggests the bathymetry position in the middle neritic.

4.4 Bujel Tasek

Bujel Tasek mud volcano is found in the Katol Barat village, Bangkalan district of Madura island. The morphology of the Bujel Tasek mud volcano is very different from other mud volcanoes in East Java.

The shape is a cone edifice with a height of approximately 12 m with a diameter of approximately 5 m. The material that came out is a mixture of viscous mud, water and gas with a highly viscous mud.

This cone shape is actually a giant gryphon formed by the high viscosity mud of a larger mud volcano that covers the area.

Nearby this conic structure is a mud lake that represents an ancient mud caldera with mud conduits that are no longer active (see figure 40).

Fig. 40. Bujel Tasek mud volcano forms a cone morphology in the village of Katol Barat, Bangkalan, Madura island, East Java.

The mud sediment that came from the Lidah formation is characterized by its brownish-grey, fine clay. The mud breccia found is gravel to boulder sized, very abundant, with fragments ejected in the form of mudstone, calcareous sandstone, siderite and calcite.

The reddish-brown and gravel- pebble sized siderite mineral is found exposed. It is widely distributed, from the mud volcano to the valley. In addition, calcite is trapped in sandstones that fills the pores of the wood that look like silisified wood.


4.5 Bleduk Kuwu

This mud volcano is located in the Village Kuwu, Kradenan, Grobogan district, approximately 20 km south of Purwodadi in Central Java.

The object of interest in Bleduk is the mud flow containing gas and salty water that takes place almost continuously in an area with a diameter of approximately 650 m (see figure 41).

Etymologically, the name comes from Kuwu Bleduk. In the Javanese language 'Bleduk' means 'blast/burst' and 'kuwu' is derived from the word 'kuwur' which means 'run/scramble'.

Fig. 41. Bleduk Kuwu mud volcano during its almost continuous eruption. The gas is flammable and sometimes self-ignites. The expelled water is commercially used to extract salt. Eruptions generally occur four or five times a minute, as a burst of warm mud and gas.

The Kuwu mud volcano cluster covers about 45 hectares. The biggest vent can erupt materials as high as 5 meters with expelled mud in a diameter of about 9 meters. At the main Kuwu site the mud volcano usually erupts four or five times a minute consisting of

mud accompanied by the release of gas and water (sometimes oil). Often the eruptions are accompanied by an explosion as the gas self-ignites. The temperature of the mud ranges from 28-30ºC, while the smaller mud volcano is slightly cooler.

Bleduk Kuwu is surrounded by other mud volcanoes within a radius of approximately 1-2 km to the southwest, northeast and south with varying dimensional extents. To the southwest is Cangkring Bleduk mud volcano that occupies a larger area than the Bleduk Kuwu, while to the south is the Bleduk Banjarsari mud volcano, and to the East is Bleduk Crewek, and to the northeast is Medang Kamolan (figure 42). Other minor mud volcanoes in the area include Bledug Kesongo and Bledug Kropak.

Geologically, these mud volcanoes are located at the boundary between North Serayu and Kendeng Depressions. Seismic sections across these mud volcanoes show disturbed zones from the top of the Kujung Formation, the top of Wonocolo Formation to the surface.

The Bledug Kuwu disturbed zone is a chaotic mixture of upward convex and concave reflectors. Bledug Kesongo is characterized by a collapsed structure with upward concave horizons along the disturbed zone indicating a subsidence.

The lower part of Late Miocene Wonocolo shales is believed to be the source of mud based on its fossil content. Seismic sections, however, show that the source of mud may also come from Early Miocene Tuban shales.

Some diapirs also occur in this area and they are generally below the top of Wonocolo Formation. Folds in this area are considered to

form diapirs as suggested by some seismic sections (Satyana and Asnidar, 2008).


Fig. 42. Medang Kamolan mud volcano, located approximately 3 km northeast of Bleduk Kuwu mud volcano.

4.6 Offshore mud volcanoes

The existence of submarine mud volcanoes and mud diapirs in the Madura Strait, offshore areas of East Java is visible in the seismic profiles.

The cross sectional appearance looks like an upwards dipping strata around a venting system of seafloor-piercing shale diapir cutting the overlying sediment and forming a conic volcanic edifice (see figure 43).

The Madura Strait is an offshore extension of the Kendeng Depression. Thick Pliocene to Pleistocene sediments were deposited rapidly and compressed elisional system in the Madura Strait depression.

Deepwater sedimentation is still taking place in this portion of the Kendeng zone, and it has not been uplifted. In the Madura Strait area, east-west trending left lateral wrench faulting triggered mobilization of Miocene basinal shales during the Plio-Pleistocene, resulting in a series of shale diapirs.

Further south, the impact of ongoing subduction along the Java Trench becomes increasingly significant and structures are dominated by north-directed thrusting, which may be independent of basement faulting (Satyana and Asnidar, 2008).

On the basis of structural style and the tectonic events, Widjonarko (1990) divided the Madura Strait block into five structural domains: wrench domain, slide domain, western basinal domain, eastern basinal domain, and southeastern fault block domain. Wrench and

slide domains bound the Madura Strait to the Madura-Kangean High in the north.

Southeastern fault block becomes the southern border of offshore Madura Strait. The main parts of the Madura Strait where mud diapirs and volcanoes exist are composed by western and eastern basinal domains.

The Madura Strait Depression or Sub-Basin is one of the two deepest and thickest basins in Indonesia. In western basinal domain, very rapid sedimentation since the Late Miocene time resulted in the development of more than 3000 meters of Plio-Peistocene section.

Eastern basinal domain is similar to western domain, the only difference is that the eastern basinal domain began to subside in the late Oligocene – early Miocene, much earlier than the western domain (Satyana and Asnidar, 2008).



Fig. 43. Water Depth ~40 – 50 m in the offshore Madura Strait Stratigraphy of the Madura Strait started in Middle Eocene time by deposition of transgressive clastics unconformably on top of pre-Tertiary basement.

The deposition was terminated by a local uplift at the end of Eocene time. Subsidence during the Oligocene resulted in deposition of deep marine sediments.

An uplift at the end of the Oligocene resulted in a regional unconformity throughout the basin. During the Early Miocene time the rapid subsidence resulted in deposition of deep marine sediments in the area.

In the mid-Late Miocene time, the basin was filled and another uplift took place. After a short subsidence to the end of Late Miocene, sedimentation interrupted again by an uplift in Early Pliocene time.

The rapid subsidence in the late Pliocene time is characterized by the deposition of overpressured thick clays. The area subsided again into a shallow marine environment after the Plio-Pleistocene regional uplift (Widjonarko, 1990; Satyana and Asnidar, 2008).