Author Biography, Copyright Declaration, And Declaration Of Originality - Pit Iagi 2018

PROCEEDINGS, 7th ITB International Geothermal Workshop 2018 Institut Teknologi Bandung, Bandung, Indonesia, March 21–22, 2018

TECTONIC CONTROL TO GEOTHERMAL MANIFESTATION ON NON-RELATED YOUNG VOLCANIC SETTING IN SUMENEP-MADURA, EAST JAVA Topan Ramadhan, Kevin Jordan, Vernando Pratama Harefa, Fauzan Iqbal Hidayat, Muhammad Farhan Firdaus, Hafidh Fatur Riza

Geological Engineering, Faculty of Mineral Technology, Institut Sains & Teknologi AKPRIND Yogyakarta Jl. Kalisahak No. 28 Komplek Balapan, Yogyakarta e-mail: [email protected]

ABSTRACT In Sumenep-Madura there are 3 spot of geothermal manifestation such a hot springs. The generally pattern of appearance the manifestation is located at the end of the anticline limb which is the axis direction of folds relative East-West. The Physiographic of Sumenep-Madura area is a part of Rembang zone. Based on lithological association of the research area is composed of sedimentary rocks from the foreland basin or a part of the North East Java Basin. From the background by tectonic setting and geologic conditions developed from PaleogeneRecent in the research area, the Geothermal System manifested is not influence by volcanic activity. North East Java Basin is a basin formed by the extension regime that produces Rifting Basin. The accumulates sediment material continuously resulting loading to produce a geopressured system of the basin. Therefore, the fluid contained in the rock formations be warm up due to the system. Based on geological data of surface deformation occurring in research area are included in the Rembang anticlinorium zone where the folding pattern is influenced by the positive flower structure deformation pattern, which is a structure that develops above the basement fault based on the observation of the subsurface seismic. Then, by surface (morphology) ridge folds pattern distribution that’s showing east-west trend or called as the RMKS (Rembang - Madura - Kangean Sakala) fault zone by subsurface data. The mechanism and kinematics of the positive flower structure pattern becomes the plane of accommodates the migration of geothermal fluid based on geometry of structure that through to the basement. Therefore, by existing mechanism the control a formation of geothermal manifestation is

influenced by the pressure gradient where is associated with the sedimentary basin. Then, the positive flower structure pattern becomes the controller of the migration path and fluid transfer to the reservoir rock (Madura formation) in near surface.

Keywords: Rembang zone, geopressured system, positive flower structure, hot spring, SumenepMadura INTRODUCTION Indonesia is one of the countries with abundant oil and gas resources. For a long time oil and gas in Indonesia has been exploited, so the problem of oil and gas energy will be decreasing. The conditions under which oil and gas will disappear from the territory of the country really will happen because basically oil and gas energy resources can not be renewed. To anticipate the situation and condition of the scarcity of oil and gas energy resources, of course, there should be efforts and steps to find new oil and gas reserves, energy savings and alternative energy utilization that is the utilization of potential geothermal resources in the present. Geographically the position of the Indonesian archipelago lies in the encounter of three large plates (Eurasia, Indies-Australia and the Pacific) which makes Indonesia has a complex tectonic order. Geothermal potential in Indonesia is spread over two geological environments, namely the volcanic and non-volcanic geological environments. In geothermal areas associated with 1

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volcanic environments, there are now many developed and generating electrical energy that can be utilized. While in the geothermal area contained in the non-volcanic environment is still not developed optimally. Therefore, there is a need for further study on geosciences data in an area of geothermal potential, be it geological, geochemical and geophysical studies. Manifestation of a geothermal system in the form of hot water is a system of water system, heating process and conditions where the heated water is collected. Nonvolcanic geothermal systems are geothermal systems that are not directly related to volcanism and are generally outside the Quaternary volcanic path. This type of geothermal fluid usually has a lower temperature and is called a low enthalpy system. The non-volcanic system consists of various types grouped by geological and tectonic environments, one of which is geothermal geopressure system. The formation of the geopressure system is related to the inner part of the sedimentary basin, in which case the sedimentation process proceeds so quickly that the available fluids are trapped by the impermeable sedimentary layers at high pressure. Geothermal systems associated with geopressure or those in sedimentary environments generally have very thick depression, with a depth of 3 km to 4 km, at temperatures ranging from 90oC to 120oC. State that geothermal geopressure systems are formed when hot water is trapped and there is exchange or mixing with surrounding rocks. Geothermal in sedimentary basins are the result of interactions from various heat sources and heat transfer mechanisms where heat from depth is transferred to the surface.

Figure 1: Geopressured system in geothermal system (Bebout, et al., 1978 in Lund, 2007)

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Sumenep regency is one of the districts on the island of Madura with a lot of natural resources potential. Exploration of minerals, oil and natural gas has been done in several places in the district of Sumenep and its islands. Lombang village, Batangbantang sub-district, located in the northeast of the Madura archipelago, is one of the places that has the manifestation of geothermal resources. Most likely the potential of hot water can be utilized for the needs of local communities as one of alternative energy. Regional Geology Generally, the North East Java Basin is formed by several main structural elements from south to north of the Kendang - Madura Strait Zone, extending eastward, primarily characterized by fold structures, normal faults, and many upward faults. South Rembang Zone and Randublatung, which is a negative zone with an east-west trending structure and is primarily characterized by a folding pattern. There is also a dome structure associated with a cesarean structure such as the Ngimbang anticline. North and North Madura Rising Zones, erupted and eroded anticlinorium structures on Plio-Plistocene, associated with a horizontal fault system that leads to a continuous north-east direction of South Kalimantan. Based on the geological map of WaruSumenep Sheet (Situmorang drr., 1992), the research area includes from the northern part of the East Java Basin. The stratigraphic arrangements from old to young is Tawun Formation, Ngrayong Formation , Bulu Formation, Formation Pasean, Madura Formation, Formation Pamekasan, and Aluvium. Stratigraphic columns along with lithology are presented in Figure 1. Tawun formation is lithologically composed of claystone, napal, limestone lempungan with orbitoid inserts. This formation is of early Miocene Miocene and its sediment is deposited in a rather shallow (subterritorial) marine environment with a thickness of about 300 m. The Ngrayong formation that harmoniously aligns over Tawun Formation is a recurrent quartz sandstone with orbitoid and claystone limestone. This formation is Middle Miocene and deposited in a shallow marine environment (litoral) with a thickness of approximately 600 m. The Bulu Formation interfingering with Ngrayong Formation consists of limestone plates with inserts of the sandstone. This formation is middle Miocene middle end, precipitated in shallow marine environment (middle neritic zone) with thickness about 200 m.

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Method From this research we use existing data, ie through surface data and subsurface data. Surface data were obtained in the form of morphological analysis and geological data of surface structure, while from the subsurface data obtained seismic data and stratigraphic formation data of basin. Based on the data of surface geological structures can interpret the configuration of subsurface structures. The geological structure that was tried in this research was Rembang Madura Kangean Sakala Fault Zone. NORTH EAST JAVA BASIN

J A V A

SundaAsri Basin

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M

. ts

it lim

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it o lim

North West Java Basin

JAVA

Bogor

North East/East Java Basin North MADURA ern Sl ope eng Tr ough

– Kend

Southe

South West Java Basin

Pamekasan Formation is incompatible with the Madura Formation consisting of conglomerates, sandstones, claystone and limestones. Conglomerates are compact, solid, poorly sorted with the basic components consisting of the foraminifera limestone and limestone limestone and a thickness of about 4 m. The Pamekasan Formation is estimated to be Pleistocene. Since the time of Holocene has occurred pengerosian, and deposited alluvium consisting of fractional loose-sized clayloose and coral reef growth.

S E A SE

M

us

eo tac

NW

Figure 2: Stratigraphic Coloum of research area. (Situmorang et al., 1992)

The Pasean Formation, which overlaps in conformity of the Bulu Formation, is a marl with clay limestone, sandy limestone, oolitic limestones with texture fine to medium grain, well-coated and contains less quartz. This formation is end-Miocene and deposited in shallow seas (inner sublittoral) with a thickness of approximately 600 m. The Madurese formations are partially overlapping and some are not aligned to the Pasean Formation, the Bulu Formation, and the Ngrayong Formation and allegedly Pliocene-aged, while in the Tanjung Bumi-Pamekasan Sheet and Surabaya-Sapulu Sheet are Miocene End-Pliocene. The Madura Formation is comprised of limestone limestone and dolomite limestone. This rock unit varies between limestones, at the bottom of limestone, oolitic limestone, dolomite limestone. This formation is deposited in a shallow and steady marine environment with a thickness of about 250 meter.

e nit gra ge lan me us eo

Belitung Basin

SUMATRA

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N South Central Java Basin

0

200 km

Quaternary volcanoes

Tectonic setting of Java

Figure 3: Geologic Basin condition of Java Island (Situmorang et al., 1992)

North East Java Basin is a basin formed by the extension style that produces Basin Rifting. The basin is grouped into a deep arc basin and is a mobile area and is bounded by a stable exposure area. The northern part of this basin area called the East Java basin is mainly located in offshore areas. The basin consists of several parts of the basin (Depth of North Tuban, Depth of Pati or Muriah, East Florence basin, Central Deep) and high altitude (Karimunjawa, JSRidge, Bawean, Masalembo and Sibaru) generally controlled by tectonic activity during Late Cretaceous to Tertiary Early. The precipitation of limestones and shales along with episodic streaming sediments is very common throughout the Tertiary. The physiography of the basin of East Java North based on the division of East Java physiography by Van Bemmelen (1949) consists of mainland alluvium north coast of Java, Rembang / Rural Anticlinorium Rembang and Madura Zones including Cepu anticlinorium, and Randublatung zone which is a depression zone, including Dander, Pegat , and the Ngimbang hills. There are several stages of orogenesa that form the basin of this region, ie at upper limestone to Middle Eocene, Middle Miocene, Plio-Plistocene. In the upper limeeocene middle of the deformation follows the collision of the eastern Java sea plate with the sunda 3

exposure. in eocene rjadi rifting followed by activation of cesarean elevation pre-eocene and normal cesarean formation. Regression events occur at the time of appointment or orgensa during middle misoen, in this process large fault forming is RMKS fault zone which is Wrenching Left Lateral. PlioPlistocene, the final Pliocene forms folds to the final plistocene. The volcanic activity of the Sunda-Java arc beginning in the final pliocene continues today.

Figure 5: Geological condition of East Java Basin (after Satyana, 2004)

Figure 4: Configuration of east java basin crossing of RMKS Fault zone (after Satyana, 2004)

Figure 6: Ilustration folded forming controled by basement fault (Husein et al, 2016)

REMBANG ZONE The appearance of the morphology of the rembang zone comprises the anticlinorial crease hills that extend from the east-west. Rembang antklinorium hills based on their folding patterns form an en-echelon pattern. Hussein et al in 2015 in his research on the folds of Braholo Antiklin interprets that the formation of folds in the Rembang zone is controlled by an East North East (ENE) West South West (WSW) besement fault. In general, the Rembang zone is an antclinorium in which there are strong structures, faults and folds. ENE-WSW trending en-echelon envelope pattern indicates a major underlying sinusral shear or cesarean section in the basement that controls the formation of enechelon folds in the Rembang zone (Husein, 2016). Based on data, the en-echelon fold is controlled by reactivation by an ENE-WSW trending basement fault with an NS compression force direction where the basement fault movement accommodates the formation of folds in the rock above because the rock is ductile and based on the strike slip movement and with deformation of the transpression will form postive flower structure (Husein, 2016). 4

Therefore, the basement fracture in the Rembang zone is very instrumental to form the morphology and surface geological conditions of both the position of the rock to existing surface geological structures. The tectonic model in Rembang is divided into 3, namely surface structure, postive flower structure, and basement structure based on observation of geological data for both surface and subsurface. Researchers are very suspect and associate that the formation of folding folds antiklinorium Rembang controlled by a basement fault called Rembang Madura Kangean Sakala (RMKS) fault zone. RMKS fault zone has 650 km long geomotor and 15-40 km wide either in onshore Rembang or offshore Rembang (Satyana, 2004). The RMKS fault zone in neogen acts as a limiting sedimentation and the main controller of sedimentation in east java basin. RMKS fault zone is occoured at the hinge belt or shelf edge to slope area of a geologic transition from the stable eastern sunda shelf to the northern flatform to the deep-water area to the south (Satyana, 2004). Paleogen rifting in Rembang zone accommodates sediment to Rambang Basin and the

basin is formed high and low during the rifting phase. Due to the loading and configuration of existing basins of fluids present in rocks such as conate water heated in a geopressured system. With the configuration of basins like this can also support the existence of geopressured mechanisms to form the heat of the earth in the sediment basin.

Figure 7: Block diagram showing mechanism of postive flower structure it’s simplication from seismic data (Pluijm and Marshak 2004 in Husein, 2016)

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Figure 8: Rembang Madura Kangean Sakala Fault Zone in Java Island (Satyana et al, 2004)

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Commented [A7]: Figure 9 is not legible, you can enlarge it.

Figure 9: Structure Map of Madura Island (Mulhadiono et al, 1986)

In Neogen regime stress resulted in the formation of wrench deformation. RMKS fault zone where Madura Island passes has a controlled geological structure of the basement fault which is a

tectonic model of the postive flower structure resulting in a weak fracture to accommodate the migration of fluid that exists beneath the surface through the structure of the positife flower structure to the surface structure so as to control the emergence of the geothermal manifestation in Sumenep, Madura. Commented [A8]: Figure 10 is not legible, you can enlarge it.

Figure 10: Seismic crossing of RMKS Fault zone (Satyana et al, 2004)

RMKS fault zone with postive flower structure in addition observed from the interpretation of surface structure data also observed from existing seismic sections. Thus, the deep fault can accommodate the geothermal heat fluid to the

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surface through the interconnected frecture and fault. The map of the geological structure on the island of Madura shows the island of Madura there are folding structures, faults, and stocky in it are scattered throughout the island.

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Figure 11: The Schematic of geothermal system in Madura island (modifed by Latief et al, 1990)

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Figure 12: The fault distribution that cutting and crossing the lamb of fold axis (Modified by Global Mapper, 2018)

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The pattern of manifestations distribution in the study area appears in the fault zone with complex geological structural conditions and appears on the fold limb. The existing fault pattern is a fault that cuts the fold axis so as to give the appearance of a fold like a bending. The fault also accommodates the emergence of a zone of geothermal manifestation on the surface. Therefore, based on the existing data that the origin of geothermal fluid in the study area comes from fluid stored in rocks that are heated with geopressured system and then migrate to the surface through basement structures with postive flower structure model toward the surface geological structure of either faults or folds.

Figure 13: Geological Map with geothermal manifestation distribution in Sumenep, Madura-East Java (Modifed by Situmorang et al, 1992)

CONCLUSION Based on existing data, the research area is included in the Rembang zone where the morphology of the research area forms the folds of anticlinorium folds with en-echelon patterns. 1.

The en-echelon fold pattern is a pattern that is suspected of being controlled by the basement fault structure. Based on these assumptions that the geological structure and techntonic conditions of the research area are controlled by a sufficiently large basement fault and initiate structural and morphological conditions on the surface.

2.

Basement fault is Rembang-Madura-KangeanSakala (RMKS) fault zone which has relative direction of ENE-WSW, and acts as a geological boundary in East Java basin on 7

paleogen so as to accommodate sediment material to basin. 3.

RMKS fault zone plays a role in controlling the sedimentation of basins on paleogens and fluids that get trapped with sediment under heating due to geopressured systems.

4.

Deformation due to reactivation of the fault zone or RMKS fault zone accommodates fluid migration through the postive flower structure to the surface.

5.

The appearance of manifestation on the island of Madura also appeared in fault zones and wings folds so that RMKS is instrumental in controlling the emergence of manifestations.

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Husein, S., Sakur, M., and Setianto, A., 2016, “Sebaran Perlipatan En Echelon Pada Antiklinorium Rembang”, Prosiding Seminar Nasional Kebumian, Yogyakarta, 9, P 70-82.

Lateif, R., et al., 1990, “IPA Post Convetion Field Trip Madura Island Guide Book”, Indonesia Petroleum Association, Jakarta.

John ACKNOWLEDGEMENT

We would like to thank the IIGW committee for giving us the opportunity to publish our research. REFERENCES Bebout, D.G., Gavenda, V.J., and Gregory, A.R., 1978. “Geothermal Resources, Wilcox Group, Texas Gulf Coast”, U.S. Dept. of Energy, contract, l EY-76-S-05-4891, 82p Bransden, P.J.E., and Mathew, S.J., 1992, “Structural and Stratigraphic evolution of the east Java sea, Indonesia,” Proceeding Indonesian Petroleum Association (IPA), 21st Annual Convetion, p 417-454.

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